ITTC Introduction to Communication Networks The University of Kansas EECS 563 MAC; Mobile and Wireless Networks

Transcription

1 Introduction to Communication Networks The University of Kansas EECS 563 MAC; Mobile and Wireless Networks James P.G. Sterbenz Department of Electrical Engineering & Computer Science Information Technology & Telecommunications Research Center The University of Kansas 16 November 2017 rev James P.G. Sterbenz

2 MAC; Mobile and Wireless Networks Outline MW.1 Wireless and mobile networking concepts MW.2 MAC functions and services MW.3 MAC algorithms MW.4 Wireless networks MW.5 Mobile networks 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-2

3 Geographic scope Wireless Networks Classification of Types distance over which links operate area of layer 2 subnetwork (not IP subnet) Mobility mobility of wireless nodes Coördination centralised vs. distributed control 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-3

4 Geographic scope Wireless Networks Classification of Types: Scope WBAN: wireless body area network WPAN: wireless personal area network WLAN: wireless local area network WMAN: wireless metropolitan network WWAN: wireless wide area network Mobility Coördination 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-4

5 Wireless Networks Classification of Types: Mobility Geographic scope WBAN, WPAN, WLAN, WMAN, WWAN Mobility fixed: nodes are stationary mobile: nodes are mobile some nodes may be fixed (e.g. base stations) nomadic: nodes are highly and routinely mobile may be frequently out of range of one-another Coördination 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-5

6 Wireless Networks Classification of Types: Coördination Geographic scope WBAN, WPAN, WLAN, WMAN, WWAN Mobility fixed, mobile, nomadic Coördination infrastructure: base station controls and transit traffic ad hoc or peer-to-peer: mobile nodes directly communicate 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-6

7 Wireless Networks Characteristics Wireless LANs very different from wired why? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-7

8 Wireless Networks Characteristics Wireless LANs very different from wired always use shared medium; MAC is required Wireless characteristics significant attenuation 1/r 2 multipath reflections increases attenuation to 1/r 4 noise and interference from one-another from other devices from environment jamming (physical DoS) open channel subject to eavesdropping 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-8

9 Wireless Networks Network Elements: Base Station Base station (BS) fixed wireless node one or more antennæ may be small (e.g. home hub) may have huge tower range is frequently called a cell typically connected to Internet via wired link BS cell Internet 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-9

10 Wireless Networks Network Elements: Base Station Base station (BS) fixed wireless node one or more antennæ may be small (e.g. home hub) may have huge tower range is frequently called a cell BS typically connected to Internet via wired link possibly wireless mulithop through other BSs BS cell Internet 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-10

11 Wireless Networks Network Elements: Wireless Node Base station (BS) Wireless node (WN) also called untethered node no wired network connection fixed or stationary node doesn t move wireless does not imply mobility typical example: laptop personal computer BS WN BS cell WN Internet 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-11

12 Wireless Networks Network Elements: Wireless Link Base station (BS) Wireless node (WN) Wireless link formed when 2 nodes in range associate BS BS cell Internet WN WN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-12

13 Wireless Networks Network Elements: Wireless Link Base station (BS) Wireless node (WN) Wireless link nodes associate BS BS cell interconnects BSs for backhaul Internet WN WN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-13

14 Wireless Networks Network Elements: Wireless Link Base station (BS) Wireless node (WN) Wireless link nodes associate interconnects BSs for backhaul interconnects WNs to BSs BS WN BS cell Internet WN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-14

15 Wireless Networks Network Elements: Wireless Link Base station (BS) Wireless node (WN) Wireless link nodes associate interconnects BSs for backhaul interconnects WNs to BSs interconnects WNs peer-to-peer BS WN BS cell WN Internet 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-15

16 MAC; Mobile and Wireless Networks MAC Functions and Services MW.1 Wireless and mobile networking concepts MW.2 MAC functions and services MW.3 MAC algorithms MW.4 Wireless networks MW.5 Mobile networks 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-16

17 L8 L7 L5 L4 L3 L2.5 L2 L1.5 L1 Medium Access Layer Hybrid Layer/Plane Cube data plane management plane control plane social application session transport network virtual link link MAC physical MAC layer: arbitration to shared medium in control plane 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-17

18 Medium Access Layer MAC Definition CPU network CPU M app station M app station Medium access control (MAC) arbitrates a channel in shared medium (free space, guided wire, or fiber) among stations (end systems, hosts) 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-18

19 application session transport network link/mac end system (station) Link and MAC Layer MAC Protocol network link/mac intermediate system network link/mac intermediate system MAC protocol (or algorithm) responsible for determining when node can transmit frame may fully distributed or coördinated network link/mac intermediate system network application session transport network link/mac end system (station) 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-19

20 MAC Layer Service and Interfaces MAC is in between physical layer 1 and link layer 2 lower link sublayer in IEEE 802 model MAC layer in control plane control over when to transmit a L2 frame but may have its own encapsulation (e.g. IEEE 802 legacy) layer 2 addresses needed for shared medium MAC layer service to link layer (L2) MAC layer encapsulate/decapsulate if appropriate initiate transfer of frame into the medium 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-20

21 MAC Layer Service and Interfaces MAC layer frame may encapsulate link layer frame done for link layer / MAC protocol independence IEEE 802: LLC (logical link control) over 802.N MAC link layer link layer H NPDU T frame H NPDU T MAC layer MAC layer H H NPDU T frame H H NPDU T physical layer physical layer 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-21

22 MAC; Mobile and Wireless Networks MAC Algorithms MW.1 Wireless and mobile networking concepts MW.2 MAC functions and services MW.3 MAC algorithms MW.4 Wireless networks MW.5 Mobile networks 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-22

23 Link Sharing Multiplexing vs. Multiple Access Multiplexing vs. multiple access Link multiplexing single transmitter dedicated point-to-point link Multiple access: multiple transmitters shared medium Lecture LL essentially physical layer multiplexing MAC algorithm needed to arbitrate free space RF 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-23

24 Channel Partitioning MAC Introduction and Assumptions Channel has sufficient capacity individual inter-station date rates less than channel capacity Multiple stations share a channel Channel partitioned into pieces pieces assigned to individual inter-station communication MAC arbitrates assignment 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-24

25 Channel Partitioning MAC Introduction and Assumptions Channel has sufficient capacity individual inter-station date rates less than channel capacity Multiple stations share a channel Channel partitioned into pieces pieces assigned to individual inter-station communication MAC arbitrates assignment Contention-free MAC partitioning ensures no contention in medium subject to engineering and design, e.g. sufficient guard bands 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-25

26 Channel Partitioning MAC Alternatives TDMA: time division multiple access FDMA: frequency division multiple access typically refers to RF CDMA: code division multiple access spread spectrum (later) Note similarity to multiplexing schemes TDMA ~ TDM essentially distributed physical layer versions of link muxing 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-26

27 channel 0 channel 1 channel n 1 channel 0 ITTC Channel Partitioning MAC TDMA TDMA: time division multiple access Channel divided into n time slots served cyclically generally equal size within a frequency band t f 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-27

28 Channel Partitioning MAC TDMA TDMA: time division multiple access Channel divided into n time slots served cyclically generally equal size within a frequency band MAC arbitrates how nodes assigned to slots static TDMA: slots reserved for particular stations (nodes) dynamic TDMA: slots scheduled based on traffic demand 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-28

29 channel 0 channel 1 channel 2 channel n 1 ITTC Channel Partitioning MAC FDMA FDMA: frequency division multiple access Channel divided into n frequency bands generally of equal bandwidth over period of time t f 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-29

30 Channel Partitioning MAC FDMA FDMA: frequency division multiple access Channel divided into n frequency bands generally of equal bandwidth over period of time MAC arbitrates how nodes assigned to frequencies static dynamic 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-30

31 Channel Partitioning MAC OFDMA OFDMA: orthogonal freq. div. multiple access based on OFDM using multiple carriers Channel consists of frequency band divided into closely spaced carriers adjacent carriers non-interfering: orthogonal Each link assigned subset of carriers MAC arbitrates how stations carrier subset 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-31

32 Link types Channel Partitioning MAC Link Duplexing half duplex: unidirectional hop-by-hop transfer full duplex: bidirectional hop-by-hop transfer Most communication requires full duplex link even unidirectional data transfer why? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-32

33 Link types Channel Partitioning MAC Link Duplexing half duplex: unidirectional hop-by-hop transfer full duplex: bidirectional hop-by-hop transfer Most communication requires full duplex link even unidirectional data transfer control messages such as ACKs for ARQ may be highly asymmetric Alternative strategies for full duplex separate end-to-end paths problem? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-33

34 Link types Channel Partitioning MAC Link Duplexing half duplex: unidirectional hop-by-hop transfer full duplex: bidirectional hop-by-hop transfer Most communication requires full duplex link even unidirectional data transfer control messages such as ACKs for ARQ may be highly asymmetric Alternative strategies for full duplex separate distinct end-to-end paths through network may have different loss & delay properties may be necessary in some cases (e.g. satellite) 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-34

35 Link types Channel Partitioning MAC Link Duplexing half duplex: unidirectional hop-by-hop transfer full duplex: bidirectional hop-by-hop transfer Most communication requires full duplex link even unidirectional data transfer control messages such as ACKs for ARQ may be highly asymmetric Alternative strategies for full duplex separate distinct end-to-end paths through network paired unidirectional links in same guided media e.g. 2 twisted-pair, 2 fiber 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-35

36 Link types Channel Partitioning MAC Link Duplexing half duplex: unidirectional hop-by-hop transfer full duplex: bidirectional hop-by-hop transfer Most communication requires full duplex link even unidirectional data transfer control messages such as ACKs for ARQ may be highly asymmetric Alternative strategies for full duplex separate distinct end-to-end paths through network paired unidirectional links in same guided media sharing same media (e.g. fiber or free space) 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-36

37 Channel Partitioning MAC Frequency Division Duplexing Duplexing : bidirectional transmission sharing media FDD: frequency division duplexing forward and reverse traffic assigned to different freq. bands simple scheme no collisions between forward and reverse packets less efficient use of spectrum under light load 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-37

38 Channel Partitioning MAC Time Division Duplexing Multiplexing in time and space for full duplex bidirectional data transmission FDD: frequency division duplexing TDD: time division duplexing forward and reverse traffic assigned to same freq. bands slots divided between upstream and downstream traffic asymmetric traffic needs dynamic bandwidth adjustment operates in conjunction with various channel multiplexing eg. TDD within FDMA 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-38

39 Channel Partitioning MAC Advantages and Disadvantages Channel partitioning advantages simple mechanism inherently fair with respect to station sharing best under high uniform and deterministic load 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-39

40 Channel Partitioning MAC Advantages and Disadvantages Channel partitioning advantages simple mechanism inherently fair with respect to station sharing best under high uniform and deterministic load Channel partitioning disadvantages per flow fairness more difficult inefficient under low load 1/n of channel bandwidth unless multiple partitions/station inefficient under high-nondeterministic load distributed partition assignment difficult; controller assigns multiple or variable partition sizes difficult to manage 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-40

41 Channel Partitioning MAC SDMA and Directional Antennæ Assumption so far omnidirectional antennæ radiate in all directions radiate even where not needed reduce channel capacity Directional antennæ radiate focused beam toward receiver reduce power use reduce interference: spatial reuse SDMA: space division multiple access MAC complexity of beam steering and station tracking 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-41

42 Channel Partitioning MAC Characteristics Characteristic Channel Partitioning Cöordinated Access Random Access Spread Spectrum Types TDMA (O)FDMA SDMA Complexity low Load Tolerance high deterministic Consequence of Contention Resilience poor Examples mesh 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-42

43 Coördinated Access MAC Introduction and Assumptions Channel has sufficient capacity individual inter-station date rates less than channel capacity Multiple stations share a channel Stations use channel for a period of time in a fully highly coördinated manner central controller (e.g. polling) algorithmic turn taking (e.g. token passing) MAC arbitrates [Kurose & Ross] call this taking turns MAC 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-43

44 Coördinated Access MAC Polling Controller grants channel access to station each station polled to determine if it needs to transmit 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-44

45 Coördinated Access MAC Token Passing Token grants channel access to station token passed between stations generally round robin Topologies bus IEEE never successful natural ring interconnection IEEE November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-45

46 Coördinated Access MAC Token Passing Resilience Token ring interface inserted in the ring what happens when station turned off? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-46

47 Coördinated Access MAC Token Passing Resilience Token ring interface inserted in the ring relay required to close circuit 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-47

48 Coördinated Access MAC Token Passing Resilience Token ring interface inserted in the ring relay required to close circuit Resilience to ring cuts problems? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-48

49 Coördinated Access MAC Token Passing Resilience Token ring interface inserted in the ring relay required to close circuit Resilience to ring cuts user unplugging station cuts ring 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-49

50 Coördinated Access MAC Token Passing Resilience Token ring interface inserted in the ring relay required to close circuit Resilience to ring cuts user unplugging station cuts ring dual ring resilient to single cut stations wrap to second ring 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-50

51 Coördinated Access MAC Advantages and Disadvantages Channel partitioning simple mechanism, best for high uniform load needs controller to assign time slots or frequency bands Coördinated access advantages nondeterministic algorithm good for nonuniform loads balances benefits of partitioning and random access good for relatively high load 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-51

52 Coördinated Access MAC Advantages and Disadvantages Channel partitioning simple mechanism, best for high uniform load needs controller to assign time slots or frequency bands Coördinated access advantages nondeterministic algorithm good for nonuniform loads balances benefits of partitioning and random access good for relatively high load Coördinated access disadvantages relatively complex network interface 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-52

53 Coördinated Access MAC Characteristics Characteristic Channel Partitioning Cöordinated Access Random Access Spread Spectrum Types TDMA (O)FDMA SDMA token ring polling Complexity low high Load Tolerance Consequence of Contention Resilience high deterministic higher degradation poor wired: moderate wireless: poor Examples mesh TR 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-53

54 Random Access MAC Introduction and Assumptions Multiple stations share a channel Stations use channel for a period of time generally entire channel (baseband access) in a fully distributed (random ) manner similar to statistical TDM MAC arbitrates What is simplest possible random access technique? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-54

55 Random Access MAC ALOHA ALOHA: 1970s radio network among Hawaiian islands Senders transmit whenever they have data (no MAC) A B C Performance metrics channel efficiency what fraction of transmission attempts are successful channel throughput what is the maximum carried load of the channel? t 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-55

56 Random Access MAC ALOHA ALOHA: 1970s radio network among Hawaiian islands Senders transmit whenever they have data (no MAC) A B C Problem collisions : transmissions interfere with one another t 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-56

57 Random Access MAC ALOHA ALOHA: 1970s radio network among Hawaiian islands Senders transmit whenever they have data (no MAC) A B C Problem collisions : transmissions interfere with one another even if only very small overlap t 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-57

58 Random Access MAC ALOHA ALOHA: 1970s radio network among Hawaiian islands Senders transmit whenever they have data (no MAC) A B C Problem collisions : transmissions interfere with one another even if only very small overlap can we do better? t 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-58

59 Random Access MAC Slotted ALOHA ALOHA: 1970s radio network among Hawaiian islands Senders transmit whenever they have data in slot A B C Problem collisions : transmissions interfere with one another improvement: divide time into slots t 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-59

60 Random Access MAC Slotted ALOHA ALOHA: 1970s radio network among Hawaiian islands Senders transmit whenever they have data in slot A B C Problem collisions : transmissions interfere with one another improvement: divide time into slots delay transmissions to next slot time t 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-60

61 Random Access MAC Slotted ALOHA ALOHA: 1970s radio network among Hawaiian islands Senders transmit whenever they have data in slot A B C Problem collisions : transmissions interfere with one another improvement: divide time into slots delay transmissions to next slot time slotted time reduces probability of collisions t 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-61

62 [throughput / packet time] ITTC Random Access MAC Unslotted vs. Slotted Performance 0.40 [adapted from Tannenbaum] slotted 0.10 unslotted G [attempts / packet time] Slotting approximately doubles performance slotted: Throughput = Ge G unslotted: Throughput = Ge 2G 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-62

63 Random Access MAC Challenges Multiple nodes must be able to share channel When 2 or more nodes simultaneously transmit signals garbled in a collision : none of them are successful How to arbitrate among them? MAC algorithm How can we do better than random transmission? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-63

64 Random Access MAC Contention Contention-based or random-access MAC nodes transmit when they have data subject to MAC per frame decision analogue to connectionless service collisions possible efficient channel utilisation in the absence of collisions 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-64

65 Random Access MAC Contention and Collisions What is the simplest way to reduce collisions? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-65

66 Random Access MAC CSMA (1-persistant) CSMA carrier sense multiple access nodes can sense if channel is in use by another station wait to transmit to avoid collision human analogy: don t interrupt others already speaking 1-persistant CSMA wait until channel free, then transmit (transmit with probability 1) Problem? How can we do better? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-66

67 Random Access MAC CSMA (non- and p -persistent) Problem: synchronisation of collisions waiting nodes will all transmit as soon as channel free Two options: Non-persistent CSMA if carrier sensed wait random period before trying again (rather than continuously sensing until channel free) better utilisation, but delayed even when unnecessary p -persistent CSMA (for slotted time) continuously sense carrier until channel is available but with only with probability p transmit on next slot 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-67

68 CSMA Collisions Collisions occur even with carrier sense due to propagation delay sender may not know channel already in use 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-68

69 CSMA Collisions Collisions still occur A B C D due to propagation delay sender may not know channel already in use Pr[collision] incr. w/ length B & D don t know other xmit 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-69

70 CSMA Collisions Collisions still occur A B C D due to propagation delay sender may not know channel already in use Pr[collision] incr. w/ length B & D don t know other xmit until signals meet near C and return Inefficient channel used by garbage Can we do better? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-70

71 CSMA/CD Collision Detection CSMA/CD: CSMA with collision detection station detecting a collision immediately ceases transmission human analogy: polite conservationist Worst case CD takes twice media propagation delay A transmits packet 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-71

72 CSMA/CD Collision Detection CSMA/CD: CSMA with collision detection station detecting a collision immediately ceases transmission human analogy: polite conservationist Worst case CD takes twice media propagation delay A transmits packet 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-72

73 CSMA/CD Collision Detection CSMA/CD: CSMA with collision detection station detecting a collision immediately ceases transmission human analogy: polite conservationist Worst case CD takes twice media propagation delay A transmits packet B transmits packet just before A reaches B 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-73

74 CSMA/CD Collision Detection CSMA/CD: CSMA with collision detection station detecting a collision immediately ceases transmission human analogy: polite conservationist Worst case CD takes twice media propagation delay A transmits packet B transmits packet just before A reaches B A+B interference travels back to A 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-74

75 CSMA/CD Collision Detection Efficiency CD frees channel earlier = 1 / [1+5t prop /t trans ] t prop max prop between nodes t trans time to transmit max frame A B C D Efficiency 1 as t prop 0 1 as t trans reclaimed capacity CD and abort 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-75

76 CSMA/CD Collision Detection Efficiency CD frees channel earlier = 1 / [1+5t prop /t trans ] t prop max prop between nodes t trans time to transmit max frame A B C D Efficiency 1 as t prop 0 1 as t trans Much better than CSMA still decentralized, simple, and cheap reclaimed capacity problem? CD and abort 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-76

77 CSMA/CD Backoff If stations all transmit after backoff, same problem need some way of un-synchronising retransmissions How? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-77

78 CSMA/CD Exponential Backoff If stations all transmit after backoff, same problem need some way of un-synchronising transmissions Exponential backoff: stations wait a random number of slot times before retrying binary exponential distribution: nth collision wait randomly among {0 2 n 1 } slots 1st collision: wait 0 or 1 slots 2nd collision: wait 0, 1, 2, or 3 slots low load: minimise delay moderate load: spread retries 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-78

79 CSMA/CD Problems Problems? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-79

80 CSMA/CD Problems: Collision Detection and Carrier Sense Problem with collision detection? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-80

81 CSMA/CD Problem with Collision Detection Problems with collision detection station must be able to simultaneously transmit and receive requires full duplex not possible for single wireless tranceiver at given frequency CSMA/CD not appropriate for wireless networks Ethernet evolution eliminated vast majority of CSMA/CD 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-81

82 CSMA Problem with Carrier Sense CSMA/CD not appropriate for wireless networks Problem with carrier sense? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-82

83 CSMA Problem with Carrier Sense CSMA/CD not appropriate for wireless networks Problem with carrier sense only appropriate when all nodes within range typically not the case for wireless networks problem? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-83

84 CSMA Problem with Carrier Sense CSMA/CD not appropriate for wireless networks Problem with carrier sense only appropriate when all nodes within range typically not the case for wireless networks problem: hidden nodes 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-84

85 Hidden nodes (terminals) CSMA Hidden Nodes some nodes are hidden from one another out of transmission range or obstruction unaware that they are causing collisions with hidden node 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-85

86 Hidden node problem CSMA Hidden Nodes C A B 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-86

87 Hidden node problem A can communicate with B CSMA Hidden Nodes C A B 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-87

88 CSMA Hidden Nodes Hidden node problem A can communicate with B C can communicate with B C A B 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-88

89 Hidden node problem A can communicate with B C can communicate with B CSMA Hidden Nodes A can not communicate with C A C B 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-89

90 Hidden node problem A can communicate with B C can communicate with B CSMA Hidden Nodes A can not communicate with C unaware of interference at B A C B 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-90

91 Hidden node problem A can communicate with B C can communicate with B CSMA Hidden Nodes A can not communicate with C unaware of interference at B Causes of hidden nodes line-of-sight obstructions A C B 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-91

92 Hidden node problem A can communicate with B C can communicate with B CSMA Hidden Nodes A can not communicate with C unaware of interference at B Causes of hidden nodes line-of-sight obstructions signal attenuation limited transmission range 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-92 A C A B C B

93 CSMA Exposed Nodes Exposed nodes (terminals) problem? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-93

94 CSMA Exposed Nodes Exposed nodes (terminals) some nodes are in range of one another prevent transmission because collision assumed 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-94

95 CSMA Exposed Nodes Exposed nodes (terminals) some nodes are in range of one another prevent transmission because collision assumed Example: B transmitting to C B C 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-95

96 CSMA Exposed Nodes Exposed nodes (terminals) some nodes are in range of one another prevent transmission because collision assumed Example: B transmitting to C but A hears B: won t transmit due to CA A B C 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-96

97 CSMA Exposed Nodes Exposed nodes (terminals) some nodes are in range of one another prevent transmission because collision assumed Example: B transmitting to C but A hears B: won t transmit due to CA even though it could to D without jamming B C D A B C 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-97

98 CSMA Exposed Nodes Exposed nodes (terminals) some nodes are in range of one another prevent transmission because collision assumed Solution? D A B C 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-98

99 CSMA Exposed Nodes Exposed nodes (terminals) some nodes are in range of one another prevent transmission because collision assumed Spatial reuse necessary directional antennæ one strategy EECS 882 D A B C 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-99

100 CSMA Alternative Improvement to CD CSMA/CD not practical for wireless networks full duplex problem hidden terminal problem Alternatives that are still better than (pure) CSMA? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-100

101 Collision avoidance (CA) CSMA Collision Avoidance attempt to avoid collision (but don t detect once occurs) 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-101

102 CSMA Collision Avoidance: Floor Acquisition Floor acquisition (FAMA: floor access multiple access) efficient negation to determine which node transmits may be in-band or out-of band (e.g. signalling frequency) similar to audio conference floor acquisition protocols 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-102

103 CSMA/CA MACA MACA: multiple access with collision avoidance in-band floor acquisition How? A B C 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-103

104 CSMA/CA MACA MACA: multiple access with collision avoidance in-band floor acquisition MACA operation (analogy: teleconference may I ) sender transmits RTS (request to send) if no carrier sense RTS A B C 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-104

105 CSMA/CA MACA MACA: multiple access with collision avoidance in-band floor acquisition MACA operation sender transmits RTS (request to send) intended receiver replies with CTS (clear to send) all nodes in range of both will detect at least 1 of RTS/CTS CTS CTS A B C 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-105

106 CSMA/CA MACA MACA: multiple access with collision avoidance in-band floor acquisition MACA operation sender transmits RTS (request to send) intended receiver replies with CTS (clear to send) all nodes in range of both will detect at least 1 of RTS/CTS if sender receives clear CTS it can transmit A B C 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-106

107 CSMA/CA MACAW MACAW: MACA for wireless CSMA/CA data frames acknowledged exponential backoff per send/receive pair modified backoff algorithm 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-107

108 Characteristic Types Random Access MAC Characteristics Channel Partitioning TDMA (O)FDMA SDMA Cöordinated Access token ring polling Random Access ALOHA, slot CSMA CD, CA Spread Spectrum Complexity low high low Load Tolerance Consequence of Contention Resilience Examples high deterministic higher lower degradation collisions poor mesh wired: moderate wireless: poor TR good old Ethernet November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-108

109 Spread Spectrum MAC Introduction and Assumptions Multiple stations share a channel Stations use channel for a period of time 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-109

110 Spread Spectrum MAC Introduction and Assumptions Multiple stations share a channel Stations use channel for a period of time Transmission spread in frequency spectrum coding techniques avoid interference CDMA: code division multiple access 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-110

111 Spread Spectrum MAC CDMA CDMA: code division multiple access Channel use different codes in a given frequency band over period of time Analogy: speaking English, German, Chinese, Hindi in the same room at the same time code 1 code 0 easier to converse in a given language (code) if interference is in different languages (codes) c code n 1 f t 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-111

112 Spread Spectrum MAC CDMA Types Frequency hopping (FH) transmissions rapidly hop among different frequency carriers pseudorandom sequence negotiated between tranceivers Direct sequence (DS) symbols multiplied by higher frequency chipping sequence 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-112

113 Spread Spectrum MAC DS CDMA Concepts All stations share same frequency band unique code assigned to each station Each station has its own chipping sequence unique code at chipping rate encoded signal = (original data) (chipping sequence) decoding: inner-product of encoded signal and chipping seq. Multiple stations transmit simultaneously minimal interference if codes are orthogonal analogy : conversations at the same time in different languages [suggested by D. Broyles] 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-113

114 sender receiver Spread Spectrum MAC DS CDMA Encode/Decode Example data bits code received input d 1 = d 0 = slot 1 slot 0 code slot 1 slot 0 Z i,m = d i. cm November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW slot 1 channel output slot 0 channel output channel output Z i,m M D i = S Z. i,m cm m=1 M d 1 = -1 slot 1 channel output [Kurose & Ross] d 0 = 1 slot 0 channel output

115 Spread Spectrum MAC DS CDMA Decode Example with Interference [Kurose & Ross] 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-115

116 Characteristic Types Spread Spectrum MAC Characteristics Channel Partitioning TDMA (O)FDMA SDMA Cöordinated Access token ring polling Random Access ALOHA, slot CSMA CD, CA Spread Spectrum CDMA FH, DS Complexity low high low high Load Tolerance Consequence of Contention Resilience Examples high deterministic higher lower degrades degradation collisions degradation poor wired: moderate wireless: poor TR good old Ethernet resistant to interference November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-116

117 MAC; Mobile and Wireless Networks Wireless Networks MW.1 Wireless and mobile networking concepts MW.2 MAC functions and services MW.3 MAC algorithms MW.4 Wireless networks MW.5 Mobile networks 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-117

118 Wireless Networks 802 Protocols by Geographical Scope WMAN WLAN WPAN IEEE WPAN IEEE WLAN IEEE WMAN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-118

119 Wireless Networks WLAN MW.1 Wireless and mobile networking concepts MW.2 MAC functions and services MW.3 MAC algorithms MW.4 Wireless networks MW WLAN MW WMAN and WiMAX MW WPAN and Bluetooth MW.4.4 Sensor networks MW.5 Mobile networks 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-119

120 IEEE Wireless Networks: WLAN Overview wireless links based loosely on Ethernet framing 6B MAC addresses, 4B FCS SNAP/LLC subheader enables simple cheap hubs and switches Unlicensed ISM/U-NII bands: 900 MHz, 2.4, 5.8 GHz significant interference from FHSS 2.4 GHz cordless phones Additional licensed bands: 3.7 GHz 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-120

121 Wireless Networks: WLAN Relation to other 802 Wireless Protocols WMAN IEEE WLAN WPAN 50 m first of the 802 wireless protocols design motivated by Ethernet sometimes called wireless Ethernet 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-121

122 Wi-Fi Wireless Networks: WLAN Wi-Fi Overview Wi-Fi alliance: note capitalisation and hyphen: Wi-Fi not WiFi nor Wifi standards compliance and interoperability testing commonly (but incorrectly) used as synonym for Wi-Fi ! 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-122

123 WLAN Deployment Scenarios Motivation for deploying WLANs? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-123

124 WLAN Deployment Scenarios Motivation for WLAN deployment cheaper than running Ethernet cables for desktops allows untethered access for laptops and PDAs 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-124

125 WLAN Deployment Scenarios Motivation for WLAN deployment cheaper than running Ethernet cables for desktops allows untethered access for laptops and PDAs Deployment scenarios home networks frequently the only network infrastructure why? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-125

126 WLAN Deployment Scenarios Motivation for WLAN deployment cheaper than running Ethernet cables for desktops allows untethered access for laptops and PDAs Deployment scenarios home networks frequently the only network infrastructure most homes not wired for networking 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-126

127 WLAN Deployment Scenarios Motivation for WLAN deployment cheaper than running Ethernet cables for desktops allows untethered access for laptops and PDAs Deployment scenarios home networks office buildings generally supplements wired LANs why? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-127

128 WLAN Deployment Scenarios Motivation for WLAN deployment cheaper than running Ethernet cables for desktops allows untethered access for laptops and PDAs Deployment scenarios home networks office buildings hotel lobbies, meeting rooms, classrooms, outdoor areas large spaces impractical to wire 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-128

129 WLAN Deployment Scenarios Motivation for WLAN deployment cheaper than running Ethernet cables for desktops allows untethered access for laptops and PDAs Deployment scenarios home networks office buildings hotel lobbies, meeting rooms, classrooms, outdoor area wireless hotspots free service to draw customers (e.g. Starbucks, McDonald s) free public service (e.g. MCI airport) for-profit service (e.g. T-Mobile) 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-129

130 WLAN Deployment Scenarios Motivation for WLAN deployment cheaper than running Ethernet cables for desktops allows untethered access for laptops and PDAs Deployment scenarios home networks office buildings hotel lobbies, meeting rooms, classrooms, outdoor area wireless hotspots public Internet service free public service (e.g. Lancaster University) fee-based service (e.g. Lawrence Freenet) 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-130

131 MAC Header WLAN Generic Frame Format [30B] frame control [2B] duration/id [2B] address 1 [6B] address 2 [6B] address 3 [6B] sequence control [6B] address 4 [6B] Frame body [0 2312B] frame control duration / ID address 1 address 2 address 3 sequence control address 4 frame body B MAC header 30B Trailer: FCS [4B] trailer FCS 4B 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-131

132 WLAN Header Format: Frame Control Type Frame control [2B] protocol version [2b] = 00 type [2b] 00 = management 01 = control 10 = data 11 = reserved subtype [4b] dependent on type frame control duration / ID address 1 address 2 address 3 sequence control address 4 frame body B MAC header 30B FCS trailer 4B 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-132

133 WLAN Header Format: Frame Control Addresses Address n [6B] IEEE MAC address types: individual station address multicast group 01-XX-XX-XX-XX-XX broadcast address FF-FF-FF-FF-FF-FF fields dependent on frame control type BSSID: BSS AP address DA: destination address (final recipient) SA: source address of frame (individual) RA: (immediate) receiver address TA: transmitter address frame control duration / ID address 1 address 2 address 3 sequence control address 4 frame body B FCS MAC header 30B trailer 4B 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-133

134 Frame body WLAN Body Format [0-2312B] variable length not present in control frames frame control duration / ID address 1 address 2 address 3 sequence control address 4 MAC header 30B frame body B FCS trailer 4B 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-134

135 FCS WLAN Trailer Format: CRC [4B] frame check sequence CRC-32 frame control duration / ID address 1 address 2 address 3 sequence control address 4 MAC header 30B frame body B FCS trailer 4B 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-135

136 WLAN Management Frame Management frame (type=01 subtype [4b]): beacon (re)association request response probe request response disassociation (de)authentication frame ctl type=10 duration destination address source address BSSID sequence control frame body B FCS MAC header 24B trailer 4B 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-136

137 WLAN Control Frame Control frame (type=01 subtype [4b]): collision avoidance 1011 RTS 1100 CTS data transfer 1101 ACK 1000 BlockAckReq 1001 BlockAck contention free operation 1110 CF-end 1111 CF-end+CF-ACK power save 1010 PS-poll (802.11n) (802.11n) frame ctl type=01 duration / ID address 1 address 2 address 3 sequence control address 4 frame body B MAC header 30B 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-137 FCS trailer 4B

138 Data frame (type=10) duration (μs) SA: source address DA: destination address BSSID of access point sequence control frame body LLC/SNAP payload FCS CRC WLAN Data Frame frame ctl type=10 duration ( s) destination address source address basic service set id sequence control LLC address 4 SNAP payload B FCS MAC header 30B LLC/SNAP subheader 8B payload trailer 4B 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-138

139 WLAN Link Types Link types (PHY and MAC) : original links at 1 2 Mb/s b, a: second set of link standards g: third link standard; common in late 2000s y: licensed 3.7 GHz n: 100 Mb/s link rate common in early 2010s ac: 500 Mb/s link rate (current) ax: ~ 2 Gb/s link rate (under development) Typically referred to by temporary standard number even after folded into revision a,b,g in ; n in ; ac in November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-139

140 IEEE b 2.4 GHz ISM/U-NII band WLAN Link Types: b formerly widest deployment 11 Mb/s maximum MAC rate actual performance highly dependent on environment 5 Mb/s goodput typical over 60m range with few obstructions adequate for most home, SOHO, and hotspot use exceeds rate of HFC and DSL access links DSSS coding; all stations use same chipping sequences what does this mean? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-140

141 IEEE a 5.8 GHz ISM/U-NII band WLAN Link Types: a higher rate alternative to b but more expensive simultaneously available with b a and b were IEEE working group numbers 54 Mb/s maximum MAC rate actual performance highly dependent on environment 24Mb/s goodput over 35m range typical deployment limited to users that needed higher rate high rate LAN applications users and campuses with higher rate Internet access links e.g. T3, 100M/1G Ethernet, SONET 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-141

142 IEEE g 2.4 GHz ISM/U-NII band WLAN Link Types: g backward compatible with b higher rate successor to b using OFDM 54 Mb/s maximum MAC rate actual performance highly dependent on environment was most common deployment in mid 2000s 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-142

143 IEEE n MAC rate of ~ 100 Mb/s Enhancements WLAN Link Types: n n physical layer MIMO (multiple-in multiple-output) antennæ 4 spatial multiplexing and beamforming new coding techniques n MAC frame aggregation and block acknowledgements n link layer framing longer payload: up to 7955B became most common deployment in 2010s 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-143

144 IEEE ac MAC rate of ~ 500 Mb/s WLAN Link Types: ac common on new equipment in mid-late 2010s Enhancements ac physical layer higher-order MIMO 8 new standard beamforming support for SDMA (directional antennæ) higher layer coding: 256-QAM binding of multiple OFDMA channels in single link 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-144

145 IEEE ax MAC rate of ~ 10 Gb/s WLAN Link Types: ax currently under standardisation Enhancements (likely) ax physical layer OFDMA MIMO uplink spatial reuse ax MAC smaller guard interval dynamic fragmentation TWT and dual NAV 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-145

146 WLAN Link Characteristics Link type year band (US) channel bw (US) channels us/eu/jp/* coding MAC rate typical range payload typical goodput Wavelan MHz 26 MHz DSSS 1 2 Mb/s GHz 83.5 MHz b GHz 83.5 MHz DSSS FHSS DSSS FHSS 1 2 Mb/s B 1 11 Mb/s 60 m B 5 Mb/s a GHz 300 MHz OFDM 6 54 Mb/s 35 m B 24 Mb/s g GHz 83.5 MHz 8 OFDM DSSS 6 54 Mb/s 1 11 Mb/s B 24 Mb/s y GHz licensed 50 MHz B 24 Mb/s n GHz 5.8 GHz 83.5 MHz 300 MHz OFDM MIMO < 248 Mb/s 75 m B 75 Mb/s ac GHz 500 Mb/s ad GHz 500 MHz *number nonoverlapping 1 Gb/s 10 m 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-146

147 Modes WLAN Subnetwork Modes and Terminology infrastructure mode: STAtions communicate through APs (access points) ad hoc mode: STAtions communicate directly BSS: basic service set subnetwork covered by a single AP (access point) typical mode of operation for home networks ESS: extended service set subnetwork covered by multiple APs sharing SSID distribution system (DS) connects multiple BSSs 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-147

148 Infrastructure mode WLAN Infrastructure Mode STAtions communicate through APs (access points) also called base station in a BSS (basic service set) most common configuration BSS 2 BSS 1 STA STA Internet AP STA STA STA 3 AP 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-148

149 Ad hoc mode WLAN Ad Hoc Mode STAtions communicate directly with one another access point infrastructure not needed rarely used occasionally used for inter-pc file transfer generally sign of misconfigured PC can be used as SSID DoS attack against AP BSS Internet 3 STA STA 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-149

150 Wireless Networks: WLAN Channels and Association Spectrum divided into channels at different freq g has 8 channels AP administrator chooses frequency for AP interference possible channel can be same as that chosen by neighboring AP Wireless node must associate with an AP scans channels listens for beacon frames containing APs SSID and MAC addr selects AP to associate with may perform authentication typically run DHCP to get IP address in AP subnet 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-150

151 WLAN MAC Options DCF: distributed coördination function random access MAC: CSMA/CA mandatory function typically the only option used in subnetworks PCF: point coördination function EECS 882 contention-free MAC with polling and ACKs optional function; not compliance tested by Wi-Fi generally not used not needed for small home networks HCF: hybrid coördination function EECS 882 enhancements for QoS in e 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-151

152 Typical deployment WLAN Deployment Characteristics infrastructure mode: AP + STAs in a BSS sensible to have some infrastructure for many LANs scalability and administrative issues for ad hoc mode IEEE didn t originally specify routing DCF: CSMA with or without CA: RTS/CTS when CA should be used? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-152

153 Typical deployment WLAN Deployment Characteristics infrastructure mode: AP + STAs in a BSS sensible to have some infrastructure for many LANs scalability and administrative issues for ad hoc mode IEEE didn t originally specify routing DCF: CSMA with or without CA: RTS/CTS turn off CA for single laptop at home and no close neighbours turn on CA for moderate to heavy load check administrative options in access point 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-153

154 WLAN Medium Access Control IEEE is typically CSMA and CDMA hybrid Variety of coding schemes DSSS: direct sequence spread spectrum FHSS: frequency hopping spread spectrum (rarely used) OFDM: orthogonal frequency division multiplexing (newer) Over which CSMA/CA MAC is typically run CSMA with optional RTS/CTS Within FDMA one of a set of channels 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-154

155 WLAN Medium Access Control IEEE is typically CSMA and CDMA hybrid Interframe spacing guard times between transmissions relative length determines priority why? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-155

156 WLAN Medium Access Control IEEE is typically CSMA and CDMA hybrid Inter-frame spacing (IFS) guard times between transmissions relative length determines priority shorter IFS will transmit first; longer will sense channel busy IFS types SIFS: short for control messages PIFS: PCF packet transmission DIFS: DCF frame transmission EIFS: extended for resynchronisation 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-156

157 Wireless Networks: WLAN CSMA/CA MAC CSMA/CA: collision avoidance RTS/CTS to reduce Pr[collision] Sender sense and wait for DIFS interval DIFS sense 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-157 1

158 Wireless Networks: WLAN CSMA/CA MAC CSMA/CA: collision avoidance RTS/CTS to reduce Pr[collision] Sender sense and wait for DIFS interval if channel free send RTS DIFS sense RTS 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-158 2

159 Wireless Networks: WLAN CSMA/CA MAC CSMA/CA: collision avoidance RTS/CTS to reduce Pr[collision] Sender sense and wait for DIFS interval if channel free send RTS Receiver wait for SIFS interval DIFS sense RTS SIFS 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-159 3

160 Wireless Networks: WLAN CSMA/CA MAC CSMA/CA: collision avoidance RTS/CTS to reduce Pr[collision] Sender sense and wait for DIFS interval if channel free send RTS Receiver wait for SIFS interval return CTS if channel idle receiver hears nodes hidden from sender DIFS sense RTS CTS SIFS 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-160 4

161 Wireless Networks: WLAN CSMA/CA MAC CSMA/CA: collision avoidance RTS/CTS to reduce Pr[collision] Sender sense and wait for DIFS interval if channel free send RTS Receiver wait for SIFS interval return CTS if channel idle Sender wait for SIFS interval why not DIFS? DIFS SIFS sense 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-161 RTS CTS SIFS 5

162 Wireless Networks: WLAN CSMA/CA MAC CSMA/CA: collision avoidance RTS/CTS to reduce Pr[collision] Sender sense and wait for DIFS interval if channel free send RTS Receiver wait for SIFS interval return CTS if channel idle Sender wait for SIFS interval DIFS already used to seize channel DIFS SIFS sense 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-162 RTS CTS SIFS 5

163 Wireless Networks: WLAN CSMA/CA MAC CSMA/CA: collision avoidance RTS/CTS to reduce Pr[collision] Sender sense and wait for DIFS interval if channel free send RTS Receiver wait for SIFS interval return CTS if channel idle Sender wait for SIFS interval transmit frame DIFS sense 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-163 SIFS RTS CTS frame SIFS 6

164 Wireless Networks: WLAN CSMA/CA MAC CSMA/CA: collision avoidance RTS/CTS to reduce Pr[collision] Sender sense, wait for DIFS, send RTS Receiver wait for SIFS, return CTS Sender wait for SIFS, transmit frame Receiver wait for SIFS interval and return ACK DIFS SIFS sense RTS CTS frame ACK SIFS SIFS 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-164 7

165 Wireless Networks: WLAN CSMA/CA MAC CSMA/CA: collision avoidance RTS/CTS to reduce Pr[collision] Sender sense, wait for DIFS, send RTS Receiver wait for SIFS, return CTS Sender wait for SIFS, transmit frame Receiver wait for SIFS interval and return ACK Sender must wait DIFS before next frame DIFS sense 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-165 SIFS DIFS RTS CTS frame ACK frame SIFS SIFS 8

166 Wireless Networks: WLAN Switching and Bridging Ethernet frequently used to interconnect APs Similar frame format makes bridging trivial map addresses copy LLC/SNAP copy payload frame ctl type=10 duration ( s) destination address source address basic service set id sequence control LLC address 4 SNAP MAC header 30B 14B LLC/SNAP subheader 8B preamble + SFD destination address source address length/type LLC SNAP copy FCS payload payload payload FCS trailer 4B FCS 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-166

167 Within BSS: no handoff WLAN Handoff Inter-BSS within IP subnet learning bridge in Ethernet switch not fast enough for real-time traffic with authentication IAPP inter-access point protocol F trial standard no longer in force unique association throughout ESS not fast enough for real-time traffic r: fast BSS transition EECS 882 overlaps association and authentication using cached keys 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-167

168 WLAN Mesh Networking specified ESS capability s: mesh standard Mesh points : relay APs or STAs BSS 2 STA BSS 1 Internet AP STA MP STA STA 3 AP AP MP STA 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-168 STA STA MP

169 Wireless Networks: WMAN Overview WirelessMAN: Wireless MANs IEEE grouper.ieee.org/groups/802/16 Metropolitan wireless networks originally intended for fixed wireless access standardisation and replacement for MMDS in GHz a additional operation in licensed bands 2 11 GHz b additional operation in unlicensed 5.8 GHz band Later support for mobility e 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-169

170 Wireless Networks: WMAN Relation to other 802 Wireless Protocols WMAN IEEE part of 2nd set of 802 wireless protocols ( & ) design motivated by MMDS WLAN WPAN 10 km no similarity to /Ethernet framing or operation 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-170

171 WiMAX Wireless Networks: WMAN WiMAX Overview Worldwide Interoperability for Microwave Access note capitalisation: WiMAX not WiMax standards compliance & interoperability tests similar in concept to Wi-Fi for deployment scenarios & service architecture recall that 802 mission is L1 and L2 only WiMAX ! 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-171

172 Wireless Networks: WMAN Physical and Link Characteristics (original) at Mb/s GHz licensed spectrum; LOS (line of sight) 2 5 km transmission radius; a and b at 75 Mb/s 2 11 GHz; non-los 7 10 km typical; 50 km max transmission radius e: mobile at 15 Mb/s 2 6 GHz; non-los 2 5 km transmission radius m: 100 Mb/s mobile; 1 Gb/s fixed intended for LTE-advanced 4G mobile cellular telephony 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-172

173 BS: base station WMAN Components directly connected to Internet infrastructure arranged as mesh with other base stations SS: subscriber station fixed SS communication with base station connected to LAN infrastructure, e.g. Ethernet, mobile SS mobile node such as PDA using e or m 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-173

174 WMAN Point-to-Multipoint (PMP) Mode PMP: point-to-multipoint topology BS: base station communicates with multiple SSs typically sectorised cell using multiple directional antennæ SS subscriber stations communicate through BSs BSS SS MT Internet STA STA AP STA 2 SS BS 3 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-174

175 Mesh mode BS SS (as in PMP) WMAN Mesh Mode BS BS multihop relay to SS BS BS mesh network (e.g for backhaul) SS SS ad hoc mode SS MT SS MT BSS Internet STA STA AP STA 2 SS BS BS 3 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-175

176 WMAN MAC and Link Layer Functions Link layer functions (called MAC layer in spec) error control ARQ hybrid ARQ with OFDMA scheduling and link adaptation for QoS Medium access control SC (single carrier) with FDD or TDD OFDMA (orthogonal frequency division multiple access) 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-176

177 WiMAX WMAN Reference Architecture only specifies air interface PHY, MAC, and link layers insufficient for service deployment architecture (ala 3G) Need for implementation agreements for equipment manufacturers service providers 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-177

178 WiMAX WMAN Reference Architecture only specifies air interface Need for implementation agreements WiMAX forum reference architecture specifies components, subnetworks, and their roles specifies service architecture including AAA, specifies reference points physical interfaces conceptual links (protocol and service relationships) 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-178

179 WiMAX WMAN Selected Reference Points ASN access service network WiMAX Forum ref points SS R1 R8 Intra-ASN RPs R1: BS SS R6: GW BS SS R1 BS R6 GW R3 R4: GW GW BS R4 Inter-ASN RPs R3: GW GW 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-179

180 and WiMAX Future Outlook as a MAN technology never widely deployed could be used for large campuses, e.g. KU as a mobile telephony e deployed for this, e.g. Sprint m certified for 4G IMT-Advanced largely abandoned switching to LTE Will probably not be in important future technology 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-180

181 Wireless Personal Networks Introduction and Definitions PAN: local area network links or subnetwork of shorter reach than LAN replacement for interconnect cables computer peripherals mobile phone headsets private intimate group of personal devices [IEEE 802] in personal operating space (POS) several meters: O (10 m) Examples wired: USB, IEEE 1394 Firewire wireless: IrDA, /Bluetooth, , Wireless USB 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-181

182 Wireless Networks: WPAN Bluetooth History Initial work done at Ericsson in Sweden Bluetooth named after Harald I Bluetooth SIG (special interest group) industry consortium formed in 1998 mobile telephone vendors: Ericsson, Nokia other electronics vendors: IBM, Intel, Toshiba Proprietary specification development membership was required to see draft specifications specifications now freely available (2.1 is current) page behemoth 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-182

183 Piconet Bluetooth WPAN Network Topology collection of devices in transmission range of master master dictates timing; transmits in odd-numbered slots up to 7 active slaves use even-numbered slots up to 247 parked (inactive) devices all slave slave communication through master Scatternet collection of piconets that share devices 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-183

184 Bluetooth WPAN Architecture Stovepipe protocol stack for very specialised domain driven by mobile telephone manufacturers physical through application layer Application profiles define vertical protocol slices, e.g.: generic access telephony printing data transfer Not compatible with other protocol stacks OSI, Internet, or IEEE 802 IEEE reworked as November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-184

185 Bluetooth WPAN Protocol Stack audio Phone apps Internet vcard mgmt applications software hardware audio AT modem TCS L2CAP: LLC and adaptation protocol baseband layer radio layer TCP IP PPP RFCOMM OBEX link manager HCI: host controller interface RFCCOMM: emulates serial port TCS: telephony control protocol specification SDP: service discovery protocol 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-185 S D P c o n t r o l HCI

186 Deployment status Bluetooth WPAN Deployment Status widely deployed in mobile telephones most commonly used for wireless headsets widely deployed in laptop computers Problems? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-186

187 Problems and issues Bluetooth WPAN Deployment Issues closed development process driven by mobile telephony incompatible with Internet and 802 architecture rectified by IEEE (future?) interference not considered interference with poor scalability in dense deployments (e.g CeBIT debacle) numerous security flaws competition looming from wireless USB architectural limitations 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-187

188 Bluetooth WPAN Architectural Limitations Significant architectural restrictions 3-bit address space only 8 active devices / piconet appalling lack of foresight evidently driven mobile telephone marketing folk personal networks easily far exceed 8 devices computer manufacturers (IBM, Intel) deny responsibility master/slave configuration scatternets consisting of multiple piconets problems largely rectified by IEEE future uncertain 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-188

189 Wireless Networks: WPAN Relation to other 802 Wireless Protocols WMAN IEEE WLAN WPAN 10 m part of 2nd set of 802 wireless protocols ( & ) design motivated by Bluetooth no similarity to /Ethernet framing or operation 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-189

190 WPAN WPAN Overview WPAN: Wireless Personal Area Networks IEEE grouper.ieee.org/groups/802/15 Personal and short-reach wireless network shorter range than initially motivated by Bluetooth & compatibility with November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-190

191 IEEE WPAN Standards Overview: Links wireless personal area networks Personal and short-reach wireless network : standardisation of Bluetooth physical/mac layers : co-existence of and in 2.4 GHz original goal of was to interoperate with : high rate and larger addresses : low energy for sensor networks : mesh networking : BAN body area networks : short range visible-light optical 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-191

192 IEEE WPAN Standards Overview: Networking wireless personal area networks Personal and short-reach wireless network : standardisation of Bluetooth physical/mac layers : co-existence of and in 2.4 GHz original goal of was to interoperate with : high rate and larger addresses : low energy for sensor networks : mesh networking : BAN body area networks : short range visible-light optical 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-192

193 and Bluetooth WPAN Physical Layer Characteristics 2.4 GHz unlicensed ISM band implications? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-193

194 and Bluetooth WPAN Physical Layer Characteristics 2.4 GHz unlicensed ISM band interference issues with b/g and cordless phones 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-194

195 and Bluetooth WPAN Physical Layer Characteristics 2.4 GHz unlicensed ISM band Three power classes class 1: mw with power control in 2 8 db steps class 2: mw with optional power control class 3: max 1 mw with optional power control Three line coding options GFSK (Gaussian FSK) line coding: 1b/symbol = 1Mb/s /4-DQPSK: 2b/symbol = 2Mb/s 8-DQPSK: 3b/symbol = 3Mb/s Low sensitivity receivers for low cost 70dBm for 0.1%BER at 1Mb/s, 0.01%BER at 2, 3 Mb/s 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-195

196 and Bluetooth WPAN Medium Access Control TDD (time division duplexing) simple to achieve over very short distances independent clocks are frequently synchronised 625μs / slot (27-bit slot number k) transmissions use 1, 3, or 5 slots masters begin transmission in even slot master slave k k+1 k+2 k+3 k+4 k+5 k November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-196

197 and Bluetooth WPAN Medium Access Control TDD (time division duplexing) simple to achieve over very short distances independent clocks are frequently synchronised 625μs / slot (27-bit slot number k) transmissions use 1, 3, or 5 slots masters begin transmission in even slot; slaves in odd slot master slave k k+1 k+2 k+3 k+4 k+5 k November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-197

198 TDD and Bluetooth WPAN Medium Access Control FHSS (frequency hopping spread spectrum) master slave FHSS robust to narrow-band interference 79 1MHz bands between and GHz (US) pseudorandom hopping sequence determined by master hop/s in connection for data transfer control significant interference with DSSS f(k) f(k+1) f(k+2) f(k+3) f(k+4) f(k+5) f(k+6) November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-198

199 and Bluetooth WPAN Piconet Piconet : up to 256 devices transmission range of master M 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-199

200 and Bluetooth WPAN Piconet Piconet : up to 256 devices transmission range of master Master dictates timing transmits in even-numbered slots M 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-200

201 and Bluetooth WPAN Piconet Piconet : up to 256 devices transmission range of master Master dictates timing transmits in even-numbered slots Slaves S M S S max of only 7 active at a time use odd-numbered slots 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-201

202 and Bluetooth WPAN Piconet Piconet : up to 256 devices transmission range of master Master dictates timing transmits in odd-numbered slots Slaves max of only 7 active at a time use even-numbered slots all slave slave communication through master S M S S 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-202

203 and Bluetooth WPAN Piconet Piconet : up to 256 devices transmission range of master Master dictates timing transmits in odd-numbered slots Slaves max of only 7 active at a time use even-numbered slots P P S P M P S S all slave slave communication through master Parked (inactive) devices max November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-203

204 Wireless Networks: WPAN Overview Task Group 3: High Rate PANs higher data rates: Mb/s multimedia and QoS ad-hoc and peer-to-peer networking better co-existence with November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-204

205 Piconets how to improve over Bluetooth/ ? WPAN Piconets 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-205

206 WPAN Piconets Piconets: 64K devices 16 b DEV address peer-to-peer data doesn t need to go via PNC why do we need a controller? PNC 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-206

207 WPAN Piconets Piconets: 64K devices 16 b DEV address peer-to-peer data doesn t need to go via PNC PNC: piconet coördinator beacons to all DEVs in piconet distributes timing PNC 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-207

208 /3 and Bluetooth Future Outlook Bluetooth widely deployed in spite of flaws substitute for a few wired peripherals mobile phone headset computer keyboard and mouse Bluetooth SIG has taken back development from not widely deployed may wait until needed more than 8 peripherals high-bandwidth multimedia 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-208

209 /3 and Bluetooth Future Outlook Bluetooth widely deployed in spite of flaws substitute for a few wired peripherals many security concerns Bluetooth SIG industry consortium has taken over standards; dormant only organisational membership with many terms Current version: Bluetooth 5 Bluetooth classic Bluetooth high speed (uses for data) Bluetooth LE (low energy) new protocols for IoT without 7-device restriction 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-209

210 Wireless Networks Sensor Network Overview Wireless sensor network (WSN) motivation remote sensing of environmental conditions e.g. temperature, chemical/radiological conditions perhaps remote actuation of control systems Sensor network characteristics network of sensors (and perhaps actuators) may be deployed in large numbers in remote areas low-power operation frequently essential difficult or impossible to replace battery large scale: manual configuration impractical sensor fields may have thousand or millions of nodes 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-210

211 Wireless Sensor Networks Application Examples Environmental monitoring long term, e.g. climate change short term, e.g. wildfire mapping Medical and health vital signs and ongoing biochemical monitoring automated drug dosing Intelligent buildings (IoT) fine-grained monitoring and control of temperature home automation Military and homeland security situational awareness 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-211

212 Wireless Sensor Networks Architectures Multihop communication with limited transmission power sensor actuator may conserve energy but energy use for transit traffic GW S sink 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-212

213 WSN Characteristics Differences from other WPANs WPAN: wireless personal network Energy concerns WPAN nodes have rechargeable or replaceable batteries WSN energy management more critical Limited mobility many sensors are stationary initial self-organisation more important dynamic reoptimisation less critical network must react to failed nodes that have no energy left 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-213

214 WSN Characteristics Differences from other Networks WSNs are data centric information important not necessarily related to particular nodes Examples average temperature of a region mapping of a storm or wildfire location of an animal Consequence? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-214

215 WSN Characteristics In-Network Processing WSNs frequently manipulate data in the network sensor nodes not only relay multihop traffic but also process it on the way More energy efficient processing generally cheaper then transmission e.g. nodes compute average, max, or min value significantly reduces communication cost referred to as sensor fusion 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-215

216 Aggregation WSN Characteristics In-Network Processing Types compute statistical functions on the way to the sink average, min, max, etc. Edge detection compute and convey boundaries between values e.g isotherms, isobars, storm edges, wildfire boundaries Trajectory tracking e.g. animal movement Other variants possible 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-216

217 Wireless Networks: WPAN Overview kb/s with multi-month to -year battery life target peer-to-peer networking extended addresses: 16 and 64 bit Generally intended for wireless sensor networks 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-217

218 Wireless Networks: WPAN ZigBee Overview ZigBee protocol specification upper level protocols for WSNs uses MAC and PHY ZigBee Alliance industry consortium that maintains standard similar to Bluetooth, but not a L1 7 stovepipe 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-218

219 and ZigBee Future Outlook Limited deployments until recently Becoming an important technology for IoT Internet of Things e.g. Osram Lightify smart bulbs base station connects to bulbs form multihop network Security concerns IoT devices have already been cracked many more have identified vulnerabilities there has never been a secure consumer platform 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-219

220 MAC; Mobile and Wireless Networks Mobile Networks MW.1 Wireless and mobile networking concepts MW.2 MAC functions and services MW.3 MAC algorithms MW.4 Wireless networks MW.5 Mobile networks 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-220

221 Mobility Overview So far, we ve been assuming fixed nodes end systems and intermediate systems (switches/routers) Mobility ability to move a device through the network Spectrum of mobility fixed: no movement (may still be wireless!) mobile: changes point of attachment to network requiring reconnection, e.g. DHCP allowing handoff, e.g. mobile IP, cellular telephony nomadic: frequent high-mobility, possible disconnected ops 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-221

222 Mobile Wireless Networks Characteristics Mobile networks wireless needed to enable mobility Dynamicity as nodes move layer 1 and 2 effects: link characteristics change e.g. signal strength, bandwidth, delay layer 3 effects: topologies change induces route changes layer 4 effects: end-to-end path characteristics change e.g. throughput, goodput, delay 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-222

223 Mobile Wireless Networks Network Elements: Mobile Node Base station (BS) Mobile node (MN) wireless node that moves BS BS cell MN Internet MN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-223

224 Mobile Wireless Networks Network Elements: Mobile Node Base station (BS) Mobile node (MN) wireless node that moves roams among base stations handoff between cells e.g. mobile telephone BS MN cell Internet MN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-224

225 Mobile Wireless Networks Network Elements: Mobile Node Base station (BS) cell Mobile node (MN) wireless node that moves roams among base stations handoff between cells e.g. mobile telephone BS MN Internet MN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-225

226 Mobile Wireless Networks Network Elements: Mobile Node Base station (BS) Mobile node (MN) wireless node that moves roams among base stations move with respect to one-another ad hoc network BS MN cell Internet MN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-226

227 Mobile Wireless Networks Network Elements: Mobile Node Base station (BS) Mobile node (MN) wireless node that moves roams among base stations move with respect to one-another ad hoc network BS cell Internet MN MN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-227

228 IP Mobility Overview Problem: node mobility between IP prefixes need to revisit IP-address/node bindings 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-228

229 DHCP Overview DHCP: dynamic host configuration protocol [RFC 2131] Allows node to dynamically obtain IP address as well as other configuration parameters, e.g. DNS server Benefits reduces manual configuration allows mobile nodes to easily move attachment point Problems? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-229

230 DHCP Overview DHCP: dynamic host configuration protocol [RFC 2131] Allows node to dynamically obtain IP address as well as other configuration parameters, e.g. DNS server Benefits reduces manual configuration allows mobile nodes to easily move attachment point Problems no handoff capabilities flows and sessions interrupted during move 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-230

231 Mobile IP Overview Mobile IP [RFC 3220] (designed by C.E. Perkins) designed to enable untethered Internet access with limited mobility without disrupting higher level protocol flows Simple way of forwarding IP packets to mobile nodes 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-231

232 Home Net Mobile IP Architecture Home Network AP MN IP IP IP IP IP AP /24 IP Home network: permanent (normal) home of MN MN: mobile node permanent address assigned from home network block e.g assigned from /24 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-232

233 Mobile IP Architecture Visited Network Home Net Visited Net AP IP IP IP IP AP MN IP /24 IP /24 Home network: permanent (normal) home of MN Visited Network: temporary location of MN e.g /24 CN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-233

234 Mobile IP Architecture Visited Network Home Net Visited Net AP IP IP IP IP AP MN IP MN /24 IP /24 Home network: permanent (normal) home of MN Visited Network: temporary location of MN e.g /24 problem? CN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-234

235 Home Net Mobile IP Architecture Visited Network Visited Net MN AP IP IP IP IP IP AP MN /24 IP /24 CN Home network: permanent (normal) home of MN Visited Network: temporary location of MN home IP addr not in visited block: packets fwd to wrong net e.g /24 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-235

236 Home Net Mobile IP Architecture Visited Network Visited Net MN AP IP IP IP IP IP AP MN /24 IP /24 CN Home network: permanent (normal) home of MN Visited Network: temporary location of MN home IP addr not in visited block: packets fwd to wrong net solution? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-236

237 Home Net Mobile IP Architecture Visited Network Visited Net MN AP IP IP IP IP IP AP MN /24 IP /24 CN Home network: permanent (normal) home of MN Visited Network: temporary location of MN home IP addr not in visited block: packets fwd to wrong net use DHCP to get address in visiting net: all flows interrupted 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-237

238 Home Net Mobile IP Architecture Visited Network Visited Net MN AP IP IP IP IP IP AP MN /24 IP /24 CN Home network: permanent (normal) home of MN Visited Network: temporary location of MN home IP addr not in visited block: packets fwd to wrong net solution? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-238

239 Home Net Mobile IP Architecture Visited Network Visited Net MN AP IP IP IP IP IP AP MN /24 IP /24 CN Home network: permanent (normal) home of MN Visited Network: temporary location of MN home IP addr not in visited block: packets fwd to wrong net mobile IP agents forward on behalf of MN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-239

240 Home Net Mobile IP Architecture Home Agent Visited Net MN HA AP IP IP IP IP IP AP MN /24 IP /24 CN Home network receives traffic destined for MN home agent (HA) receives traffic destined for MN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-240

241 Home Net Mobile IP Architecture Foreign Agent Visited Net MN HA AP IP IP IP IP IP AP FA MN /24 IP /24 CN Home agent (HA) forwards on behalf of MN to visited Foreign agent (FA) intercepts and relays to MN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-241

242 Home Net Mobile IP Architecture Foreign Agent Visited Net MN HA AP IP IP IP IP IP AP FA MN /24 IP /24 CN Home agent (HA) forwards on behalf of MN to visited Foreign agent (FA) intercepts and relays to MN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-242

243 Home Net Mobile IP Architecture Reverse Path Visited Net MN HA AP IP IP IP IP IP AP FA MN /24 IP /24 CN Home agent (HA) forwards on behalf of MN to visited Foreign agent (FA) intercepts and relays to MN Does MN need to use agents to send to CN? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-243

244 Home Net Mobile IP Architecture Reverse Path Visited Net MN HA AP IP IP IP IP IP AP FA MN /24 IP /24 Home agent (HA) forwards on behalf of MN to visited Foreign agent (FA) intercepts and relays to MN MN can address datagrams directly to CN issues? CN 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-244

245 Home Net Mobile IP Architecture Triangle Routing Visited Net MN HA AP IP IP IP IP IP AP FA MN /24 IP /24 CN Home agent (HA) forwards on behalf of MN to visited Foreign agent (FA) intercepts and relays to MN MN can address datagrams directly to CN triangle routing : forward path reverse path 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-245

246 Mobile IP Procedures Agent discovery with ICMP messages home and foreign agents advertise their service mobile nodes solicit the existence of an agent Registration request forwarding services from foreign agent registers care-of address with home agent Tunneling home agent tunnels datagrams to care-of address various methods, including IP-in-IP and GRE Handoff de- and re-register 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-247

247 Advantages Mobile IP Advantages and Disadvantages very simple mechanism Disadvantages hand-off latency may be seconds registration authentication many optimisations proposed triangle routing different forward and reverse paths security issues ingress and firewall address filtering of address mismatches 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-248

248 IP routers Mobile IP Reality most supported mobile IP for a long time Service providers some deployment within cellular telephony service providers Users very little actual use DHCP reattachment sufficient for many applications and Web transactions not yet much continuous wireless coverage very few users roam among hot spots mobile telephony has won this niche 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-249

249 Mobile Ad Hoc Networking Overview Mobile ad hoc networks MANETs in IETF jargon (pronounced ma-net not ma-nay) Mobile nodes are untethered Ad hoc no pre-existing infrastructure is assumed auto-configuration of nodes self-organisation of networks example: group of users meets in cave and forms a network 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-250

250 Multihop Mobile Ad Hoc Networking Multihop Networking nodes act as both end and intermediate systems users carry transit traffic security and performance implications 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-251

251 Mobile Ad Hoc Networking Impact of Mobility Dynamic nodes and topologies changing links, clustering, and federation topology difficult to achieve routing convergence Control loop delay mobility may exceed ability of control loops to react Impacts QoS changes in inter-node distance requires power adaptation changes density and impacts degree of connectivity latency issues (routing optimisations temporary) 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-252

252 Types Mobile Ad Hoc Networking Routing Algorithms proactive or table driven compute routes that may be needed low communication startup latency overhead of continuous route maintenance reactive or on-demand compute routes only when needed higher startup latency lower overall overhead Many proposed routing algorithms DSDV, AODV, OLSR, DSR, etc. 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-253

253 Mobile Wireless Telephony Motivation Untethered replacement for wired phones scenarios? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-254

254 Mobile Wireless Telephony Motivation Untethered replacement for wired phones cordless phone replacement within premises 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-255

255 Mobile Wireless Telephony Motivation Untethered replacement for wired phones cordless phone replacement within premises mobile telephones for use anywhere including while moving: driving, riding train or bus 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-256

256 Mobile Wireless Telephony Motivation Untethered replacement for wired phones cordless phone replacement within premises mobile telephones for use anywhere including while moving: driving, riding train or bus Design goals seamless mobility is prime requirement 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-257

257 Mobile Wireless Telephony Motivation Untethered replacement for wired phones cordless phone replacement within premises mobile telephones for use anywhere including while moving: driving, riding train or bus Design goals seamless mobility is prime requirement how is this different from mobile IP? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-258

258 Mobile Wireless Telephony Motivation Untethered replacement for wired phones cordless phone replacement within premises mobile telephones for use anywhere including while moving: driving, riding train or bus Design goals seamless mobility is prime requirement: handoff more aggressive requirement than for mobile IP 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-259

259 (0G) Wireless Telephony Early History 1946: FCC allocates 33 FM channels in 35,150,450 MHz band 1947: operator relay begins to US passenger trains 1960s: direct dialing from automobiles in home area extremely limited channel capacity 1977: Bell Labs begins first AMPS 1G cellular trial in Chicago 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-260

260 Cellular Network Topology Motivation Goal: wireless telephony everywhere Problem: how to place base stations? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-261

261 Cellular Network Topology Motivation How to place base stations randomly? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-262

262 Cellular Network Topology Motivation How to place base stations random: difficult for network traffic engineering 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-263

263 dead zones Cellular Network Topology Motivation How to place base stations random: difficult for network traffic engineering alternative? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-264

264 Cellular Network Topology Motivation How to place base stations regular tessellation in cellular structure what shape? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-265

265 Cellular Network Topology Motivation How to place base stations regular tessellation in cellular structure square grid? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-266

266 Cellular Network Topology Motivation How to place base stations regular tessellation in cellular structure square grid: very non-uniform distance between transmitters range of 1 to units alternative? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-267

267 Cellular Network Topology Hexagonal Cell Structure How to place base stations hexagonal tessellation is most efficient packing of circles e.g. beehive reality: exact location constrained by economics & regulation cell 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-268

268 Cellular Network Topology Hexagonal Cell Structure Hexagonal cell plan Problem? cell 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-269

269 Cellular Network Topology Hexagonal Cell Structure Hexagonal cell plan Problem: interference between adjacent cells solution? cell 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-270

270 Cellular Network Topology Hexagonal Cell Structure Hexagonal cell plan Adjacent cells need to use different frequencies avoid inter-cell interference signal-strength sensing for handoff how to allocate? cell 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-271

271 Cellular Network Topology Frequency Reuse Hexagonal cell plan Frequency reuse plan to assign frequencies to cells 4 frequency plan 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-272

272 Cellular Network Topology Frequency Reuse Hexagonal cell plan Frequency reuse plan to assign frequencies to cells 7 frequency plan 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-273

273 Cellular Network Topology Increasing Capacity Cell plan designed for a given traffic load what happens when traffic increases? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-274

274 Cellular Network Topology Increasing Capacity: Add Spectrum Add channels constrained by available spectrum e.g. channels added to US AMPS (taken from UHF television) 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-275

275 Cellular Network Topology Increasing Capacity: Dynamic Assignment Add channels Frequency borrowing adjust long-term allocation between cells limited applicability dynamically load balance channels among cells complexity 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-276

276 Add channels Cellular Network Topology Increasing Capacity: Sectorisation Frequency borrowing What else? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-277

277 Add channels Cellular Network Topology Increasing Capacity: Sectorisation Frequency borrowing Sectorisation (SDMA) replace omnidirectional antenna with directional antennæ 3, 4, and 6 sector designs common 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-278

278 Add channels Cellular Network Topology Increasing Capacity: Cell Splitting Frequency borrowing Sectorisation Cell splitting overlay microcells or picocells 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-279

279 Add channels Cellular Network Topology Increasing Capacity: Cell Splitting Frequency borrowing Sectorisation Cell splitting Combination of techniques 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-280

280 Cellular Network Mobility Problem How to support mobility between cells? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-281

281 Cellular Network Mobility Handoffs Handoffs (handovers) for mobility between cells without call/connection termination 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-282

282 Cellular Network Mobility Handoffs Handoffs (handovers) for mobility between cells without call/connection termination Handoff types hard handoff: break-before-make soft handoff: make-before-break Metrics? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-283

283 Handoff metrics Cellular Network Mobility Handoff Metrics call dropping probability handoff delay (due to signalling) interruption duration (time MT not connected to either BS) results in silence for voice and packet loss for data probability of unnecessary handoff todo: fig 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-284

284 Cellular Network Mobility Handoff Strategies Handoff strategies: relative signal strength handoff to BS with stronger signal problem? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-285

285 Cellular Network Mobility Handoff Strategies Handoff strategies: relative signal strength handoff to BS with stronger signal ping-pong oscillations between adjacent base stations alternatives? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-286

286 Cellular Network Mobility Handoff Strategies Handoff strategies: relative signal strength handoff to BS with stronger signal ping-pong oscillations between adjacent base stations Handoff optimisations thresholds hysteresis predictive future signal strength combinations HO B cell assignment relative signal strength HO A based on [Stallings 2005] fig. 10.7b 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-287

287 Mobile Telephone Network Roaming Roaming between service providers handoff service and billing agreements 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-288

288 Mobile Telephone Network Architecture Overview cell PSTN (wired) mobile terminal base station 4 MSC Network divided in cells each covered by base station hexagonal packing of circles adjacent cells use different frequencies (spatial reuse ) Mobile terminals move among cells Cells interconnected by mobile switching centers 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-289 MSC mobile switching center

289 Mobile Telephone Network Generations 1G: analog voice 2G: digital voice 2.5G: 2nd generation with new data services emerged with delay of 3G past planned deployment in G: moderate-rate data access ITU IMT (International Mobile Telecommunications) 4G: high-rate data access ITU IMT-Advanced: 1 Gb/s stationary / 100 Mb/s mobile 5G: very-high-rate data access & advanced services ITU IMT-2020 under early development 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-290

290 Mobile Cellular Telephony First Generation: Analog Voice 1G: analog voice 2G: digital voice 3G: moderate-rate data access 4G: high-rate data access 5G: very-high-rate data access with M2M 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-291

291 Mobile Cellular Telephony First Generation: Analog Voice 1G (first generation) mobile telephony voice: analog modulation of analog signal control: analog modulation of digital signal data: no support Development trials in 1970s first commercial services in 1980s ubiquitous in 1990s most cities & along freeways, motorways, autobahnen 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-292

292 1G Mobile Cellular Telephony Characteristics First generation: analog cellular telephony Handsets large and bulky similar in size to wired phones with lead-acid batteries e.g. bag phone later more compact with NiCd batteries with poor life e.g Motorola MicroTAC (total area coverage) flip phone Call characteristics attenuation and noise resulted in variable quality quality degraded significantly when handoff between cells 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-293

293 1G Mobile Cellular Telephony Deployed Systems 1G deployments: multiple incompatible systems AMPS (advanced mobile phone system) US, South America, Australia, China, Japan NMT, TACS, B/C-Netz, RTM, Radiocom no ability to roam between systems and countries limited roaming between compatible systems special roaming codes needed to receive calls AMPS: FCC granted two licenses per area A: second service provider / B: incumbent telco (e.g. RBOC) analogue coding with 30 khz channels 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-294

294 1G Mobile Cellular Telephony US AMPS Overview FCC granted two licenses for each market A: second service provider (e.g. Cellular One) B: incumbent wireline provider (e.g. RBOC) each allocated 333 voice + 21 control channels later expanded to 416 voice channels FCC reclaimed UHF TV channels Initially A/B network manually provisioned in phone phone identified by EIN no automatic roaming between carriers special roaming codes needed to receive calls phone#+serial#+pin transmitted in clear; cloning common 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-295

295 2G Mobile Cellular Telephony Motivation and Characteristics Problems with 1G cellular telephony analog voice transmission subject to noise and interference developed reputation for poor quality Solution digital coding of voice channels 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-296

296 Mobile Cellular Telephony Second Generation: Digital Voice 1G: analog voice 2G: digital voice 2.5G: 2nd generation with data over voice channels 2.75G: 2.5 generation with enhanced data rates 3G: moderate-rate data access 4G: high-rate data access 5G: very-high-rate data access with M2M 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-297

297 2G Mobile Cellular Telephony Characteristics Second generation: digital cellular telephony Handsets smaller than analog sets driven by more compact digital components and Moore s law later premium phones very small e.g Motorola StarTAC: 1st small clamshell Call characteristics marketing claim: clear voice with no dropped calls reality: better quality when signal strong worse quality when signal very weak, especially during handoff 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-298

298 2G Mobile Cellular Telephony Voice Network Architecture PSTN BSC HLR VLR MS BSC MSC 5 BTS BTS: base transceiver station cell tower and transceivers MS BSC: base station controller intelligence for multiple BTSs MSC: mobile switching center BTS HLR/VLR: home/visitor location registry 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-299

299 2G Mobile Cellular Telephony Deployed Systems 2G TDMA deployments GSM (global system for mobile communications) Europe and most of the world later US Cingular at&t iden US (Nextel Sprint), Canada D-AMPS (digital AMPS) US (AT&T US Cellular), Canada PDC (personal digital cellular) Japan, South Korea 2G CDMA deployments: IS-95 from Qualcomm US (Sprint, Verizon), Canada, Mexico, Australia, Korea, China, India, Israel, Sri Lanka, Venezuela, Brasil became dominant US, then lost market share lost US market share to GSM (T-Mobile, at&t/cingular) 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-300

300 channel 0 channel 1 channel n 1 channel n frame 0 framel 1 frame 4 frame 3 ITTC TDMA in FDMA/FDD slow FHSS FDMA set of full-duplex channels (FDMA) 124 in original GSM-900 FDD symmetric down/uplink channels TDMA FHSS 1 burst with 2 data fields / slot 8 slots / frame frame hierarchy 1 hop / ms frame 2G GSM TDMA Multiple Access 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW khz f down links t up links ms

301 2G Mobile Cellular Telephony Link Characteristics AMPS D-AMPS GSM cdmaone Introduced 1979/ Type analog digital digital digital Coding FM TDMA TDMA CDMA band MHz BS MT Channel BW 30 khz 30 khz 200 khz 1.25 MHz Duplex channels Mux. degree Max. xmit. power 3 W 3 W 20 W 200 mw Modulation FM + FSK /4 DQPSK GMSK QPSK based on [Stallings 2005] Table November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-302

302 2.75G GSM TDMA EDGE Overview EDGE: Enhanced Data Rates for GSM Evolution enhanced data packet transport over GSM meets technical definition of 3G but slower than current 3G technologies UMTS and EV-DO Data rate varies kb/s per 4 slots 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-303

303 Mobile Cellular Telephony Third Generation: Moderate Rate Data 1G: analog voice 2G: digital voice 3G: moderate-rate data access 4G: high-rate data access 5G: very-high-rate data access with M2M 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-304

304 3G Mobile Cellular Telephony Motivation and Characteristics Problems with 2G cellular telephony? 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-305

305 3G Mobile Cellular Telephony Motivation and Characteristics Problems with 2G cellular telephony nothing really, for voice but not engineered for data and Internet access but is this really the right device to access the Internet? Response of mobile service providers hack data services into and onto cellular infrastructure Market advantage widely deployed wireless infrastructure way ahead of predates November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-306

306 3G Mobile Cellular Telephony Standards and Interfaces IMT-2000: International Mobile Telecommunications 2000 ITU-R standard M.1457 for 3G networking Six IMT-2000 air interfaces; two widely deployed IMT-DS: direct sequence W-CDMA/UMTS (GSM evolution) IMT-MC: multicarrier CDMA2000 standardised by 3GPP2 IMT-TD: time division TD-CDMA standardised by 3GPP IMT-SC: single carrier EDGE (2.75G) IMT-FT: frequency time: DECT enhanced cordless telephone OFDMA TDD WMAN in 2007 based on e (Sprint) Sprint terminated e deployments 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-307

307 cdma2000 EV-DO Data Network Architecture backhaul AAA RNC Internet AT DOM aggr RNC PDSN IP BTS AT BTS DOM T1 backhaul BTS: base transceiver station DOM: data-only module RNC: radio network controller AAA: authentication, auth., & acct. PDSN: packet data serving node 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-308

308 3G Mobile Networking LTE Two competing standards LTE based on UMTS GSM standards work by 3GPP LTE has won UMB based on CDMA2000 (work by 3GPP2) Qualcomm ended work on UMB LTE: long term evolution (3GPP release 8) E-UTRAN: evolbed UMTS terrestrial radio access network OFDMA downlink, SC-FDMA uplink (single carrier) FDD or TDD link duplexing AIPN: all IP network data rates below that mandated by ITU for 4G 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-309

309 3G Mobile Networking LTE History 2004: initiated by NTT DoCoMo as E-UTRA E-UTRA enhancement of UTRA performance targets 100 M b/s downlink; 50 Mb/s uplink < 10 ms RTT 2007: first approved 3GPP technical specifications 2008: stable for commercial implementation 2009: first public LTE service in Stockholm and Oslo 2010: LTE service in Germany 2015: LTE deployment and substitution in US incorrectly branded as 4G 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-310

310 LTE Features: Architecture Simplified network architecture vs. 3G flat IP-based network replacing the GPRS core optimised for the IP-Multimedia Subsystem (IMS) circuit switching gone network partly self-organising Scheme for soft frequency reuse between cells inner part uses all sub-bands with less power outer part uses pre-served sub-bands with higher power Transition from 3G networks but with completely different radios and air interfaces 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-311

311 LTE Features: Performance Enhanced performance over early 3G higher data throughput using MIMO lower RTT for interactive and gaming applications Greater flexibility spectrum, bandwidth, rates Step towards 4G architecturally compatible but insufficient data rate: not 100 Mb/s / 1 Gb/s 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-312

312 LTE Physical Layer Flexibility E-UTRA (Evolved Universal Terrestrial Radio Access) Operating bands: MHz Channel bandwidth 1.4, 3, 5, 10, 15, or 20 MHz TDD and FDD Modulation: QPSK, 16QAM, 64QAM Multiple Access OFDMA (DL), SC-FDMA (UL) Peak data rates 300 Mbit/s DL; 75 Mbit/s UL Depends on UE category Cell radius: <1 km to 100 km 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-313

313 U u Mobility Management Entity Serving Gateway Packet-data network Gateway Home Subscriber Server Policy and Charging Rules Function UE 2 enode B MME S10 S3 GPRS enode B X2-U/-C X2-U/-C S1-MME MME S6 HSS UE 1 U u X2-U/-C enode B S1-MME S1-U S11 S4 PCRF enode B X2-U/-C S-GW S7 Rx+ E-UTRAN enode B S1-U S5 S8 (roaming) P-GW EPC (Evolved Packet Core) Internet, Operators 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-314 SGi [Schiller 2011]

314 Mobile Cellular Telephony Fourth Generation: High Rate Data 1G: analog voice 2G: digital voice 3G: moderate-rate data access 4G: high-rate data access 5G: very-high-rate data access with M2M 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-315

315 Fourth Generation Mobile Networking 4G Overview High data rates for modern smart phones mobile PSTN has become de facto mobile Internet access IMT-advanced (international mobile telecommunications) ITU-R M.2133, M Mb/s mobile 1 Gb/s stationary Service offerings many claimed based on , HSPA, and LTE not actually 4G are being spun as 4G by service providers 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-316

316 LTE and LTE-Advanced Overview LTE and LTE-A: long term evolution 3GPP successor to UMTS Appears to finally be worldwide converged standards air interfaces and link protocols deployment architecture and interfaces frequency bands but many complicate universal handset deployment e.g. China and India bands 39/40/41 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-317

317 LTE and LTE-Advanced Relationship to Mobile Telephony Generations LTE is next architectural generation in GSM family GSM UMTS E-UTRAN evolved UMTS terrestrial radio access ITU defines generations by capabilities 3G = ITU-R M.1457 IMT G = ITU-R M.1645 IMT-Advanced Relationship provider marketing folk want to sell you new & improved but doesn t reflect reality of ITR-R standards LTE = IMT2000 = 3G (referred to here as 3.9G) LTE-A = IMT-Advanced = 4G unless ITU redefines 4G 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-318

318 IMT-advanced IMT-Advanced Overview ITU-R M. series specification worldwide compatibility flexibility to efficiently support wide range of services interworking with other technologies requirement for 4G certification Desired features high data rates for mobile broadband services and apps 1 Gb/s stationary to 100 Mb/s high mobility worldwide roaming 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-319

319 LTE advanced successor to LTE LTE Advanced Overview 3GPP releases 10 and following data rates sufficient for IMT-A / 4G certification 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-320

320 Mobile Cellular Telephony Fifth Generation: High Rate Data 1G: analog voice 2G: digital voice 3G: moderate-rate data access 4G: high-rate data access 5G: very-high-rate data access with M2M 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-321

321 Fifth Generation Mobile Networking 5G Overview Very high data rates for evolving smart phones and other mobile devices aggregate capacity for many more devices P2P communications for efficiency Large number of devices continued increase in mobile device adoption M2M (machine-to-machine) communication for the IoT IMT-advanced (international mobile telecommunications) 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-322

322 EB ITTC 5G traffic predictions IMT G Overview 1 ZB = 1k EB = 1M PB = 1G TB 1 ZB/month = 4 PB/s traffic/month Non-Video Video M2M 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-323

323 IMT-2020 IMT G Overview vision and framework: ITU-R M.2083 timeline vision: 2012 development: 2016 deployment: 2020 usage scenarios enhanced mobile broadband ultra-reliable low-latency communications massive machine-type communications 16 November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-324

324 IMT G IMT G Comparison to 4G Peak data rate (Gbit/s) User experienced data rate (Mbit/s) Area traffic capacity 2 (Mbit/s/m ) IMT Spectrum efficiency 100 Network energy efficiency 10 1 IMT-advanced Mobility (km/h) Connection density 2 (devices/km ) 1 Latency (ms) M November 2017 KU EECS 563 Intro Comm Nets MAC Mobile Wireless ICN-MW-325