W.wan.4-2 Wireless LANs & ANs Case tudy: Bluetooth & IEEE802.15 W.lan.4 Dr..Y.Wu@CE hanghai Jiaotong University hanghai, China Dr.W.hu@ECE University of New exico Albuquerque, N, UA ANs: Bluetooth & 802.15 Bluetooth Overview iconets & catternets HY layer AC layer Logical Link Control anagement 802.15 & others End W.wan.4-3 W.wan.4-4 ANs: ersonal area networks AN = Networks that connect devices within a small range Typically 10-100 meters Applications Realtime data and voice transmissions Cable replacement, get rid off net of wires Hook laptop, DA, headphones,printer, camera Ad hoc networking ensor networks RFIDs Bluetooth overview Overview Universal radio interface for ad-hoc wireless connectivity hort range (10 m), low power consumption, licensefree 2.45 GHz I Interconnecting laptop, DA, headphones,printer, camera, replacement of IrDA pecifies the physical, link, and AC layers Applications built on top of Bluebooth using HCI (Host Control Interface)
W.wan.4-5 W.wan.4-6 Bluetooth history History 1994: Ericsson C-link project 1998: foundation of Bluetooth IG, at www.bluetooth.org 2001: spec. version 1.1 released 2005: 5 million chips/week ponsors Initial: Ericsson, Nokia, IB, Intel, Toshiba Expended in 1999: 3Com, icrosoft, otorola, Agere (was: Lucent), ore than 2500 members in IG as adopters Common specification and certification of products Bluetooth history History and Hi-tech The name "Bluetooth" is taken from the 10th century Danish King Harald Blatand - or Harold Bluetooth in English. W.wan.4-7 W.wan.4-8 Bluetooth design Design goals Global operation on voice & data No fixed infrastructure required for network setup mall, low-power, low-cost radio, embedded in devices, goal: $5-10/node; in 2005: $50/UB bluetooth Topology Overlapping piconets (stars) forming a scatternet aster-slave connection One of the first modules (Ericsson). Bluetooth architecture: piconet Components aster node One per piconet lave node Up to 7 per piconet arked node Connected, but not actively participating, up to 256 per piconet, limited listening tandby node Not connected, only native clock is running B =aster =lave B =arked B=tandby
W.wan.4-9 W.wan.4-10 Bluetooth architecture: piconet Bluetooth architecture: scatternets Collection of devices connected in an ad hoc fashion One unit acts as master and the others (max 7) as slaves Each piconet has a unique hopping pattern aster announce its clock & ID aster determines hopping pattern (by its 48-bit device address) laves have to synchronize (articipation in) B =aster =lave B =arked B=tandby =aster =lave =arked B=tandby B B catternets: Linking of multiple co-located piconets through the sharing of common master or slave devices Communication between piconets Devices jumping back and forth between the piconets B iconets (each with a capacity of 720 kbit/s) W.wan.4-11 W.wan.4-12 Bluetooth architecture: scatternets Bluetooth protocol stack Within a piconet Every active members (master/slaves) share 1 Hz bandwidth Among co-located piconets They can co-exist by hopping independently Aggregately share 79 Hz bandwidth Interconnect of co-located piconets scatternets Nodes can belong to multiple piconets by TD Can be a slave in two different piconets Can be a master in one piconet and a slave in another piconet Cannot be a master in two different piconets, since master defines a piconet No standard for synchronize between piconets Inefficient use of resources, cause drop of connection App Transport Network Link HY Audio Apps Audio Internet Apps Telephony Apps TC/UD AT I odem interface RFCO (erial Line Interface) Logical Link Control & Adaptation rotocol (L2CA) Baseband RAdio vcard Apps anagement Apps ervice Discov rotocol (D) Link anager Host Control Interface (HCI)
W.wan.4-13 W.wan.4-14 Bluetooth: protocol stack Radio Baseband Frequency hopping selection Connection creation & management AC Link management ower management ecurity management LLC & adaptation protocol Bluetooth HY: radio 2.4 GHz I band (2402-2480) 79 RF hopping channels 1 Hz carrier spacing GFK modulation Devices within 10m can share up to 865 kbps (<1 mbps) eak Tx power 20 dbm FH/TDD/TDA Frequency hopping, good protection against interference Hopping sequence with 1600 hops/s in a pseudo random fashion, determined by a master, Time division duplex for send/receive separation Low cost, low power implementation W.wan.4-15 W.wan.4-16 Bluetooth HY: radio All devices in a piconet hop together aster gives slaves its clock and device ID Hopping pattern: determined by device ID hase in hopping pattern determined by clock Channels 79 1 Hz channels, each divided into 625 μs slots 1600 hops/s, hop occurs after each packet transmitted ackets can be 1, 3, or 5 slots in length Clocks Native clock, 28-bit, ticks 3,200 times/s 312.5 μs, ½ length of hopping slot Bluetooth HY: radio Transmitting packets in multiple slots Hop freq used for 1 st slot will remain for others Freq used with the following slots are catching back to the regular sequence 625 µs f k f k+1 f k+2 f k+3 f k+4 f k+5 f k f k f k+3 f k+4 f k+5 f k+6 f k+6 f k+1 f k+6 t t t
W.wan.4-17 W.wan.4-18 Bluetooth HY: radio TDD (Time Division Duplex) Transmit and receive in alternate time slots aster-slave architecture aster transmits in an even-numbered slot lave transmits in following odd-numbered slot Traffic scheduling aster polls slaves explicitly or implicitly ending a master-to-slave data/control packet aster can adjust scheduling algorithm dynamically cheduling algorithms are not specified in Bluetooth standard Bluetooth HY: radio Low power design Transmission 1 mw to reach 10m, to reach 100m, amplify signal to 100mW Class 1: greatest distance ax 100mW (+20dBm), min 1mW, power control required Class 2: ax 2.4mW (+4dBm), min.25mw, power control optional Class 3: lowest power, 1mW Active 50-100mW active power Voice mode, 8-30 ma, 75 hours Data mode, average 5 ma at 20 kbps, 120 hours tandby tandby current < 0.3 ma, 3 months Bluetooth AC: link types W.wan.4-19 Bluetooth AC: link types W.wan.4-20 Voice link CO (ynchronous Connection Oriented) FEC (forward error correction), no retransmission, 64 kbit/s duplex, point-to-point, circuit switched eriodic single slot packet assignment aster can support up to 3 CO links at the same time Data link ACL (Asynchronous ConnectionLess) Asynchronous, fast acknowledge, point-to-multipoint, packet switched Variable packet size (1,3,5 slots), asymmetric bandwidth up to 433.9 kbps symm or 723.2/57.6 kbps asymmetric Forward error detection (2/3 FEC) and retransmission Achievable data rate on the ACL link Dx = x-slot 2/3 FEC protected; DHx = x-slot unproteted Type D1 DH1 D3 DH3 D5 DH5 ymmetric (kbps) 108.8 172.8 256.0 384.0 286.7 432.6 Asymmetric (kbps) 108.0 172.8 384.0 576.0 477.8 721.0 108.8 172.8 54.4 86.4 36.3 57.6
W.wan.4-21 W.wan.4-22 Baseband AC: link types Bluetooth: baseband olling-based TDD packet transmission 625µs slots, master polls slaves CO & ACL can co-exist ATER LAVE 1 LAVE 2 CO ACL CO ACL CO ACL CO ACL f 0 f 4 f 6 f 8 f 12 f 14 f 18 f 20 f 1 f 7 f 9 f 13 f 19 f 5 f 21 f 17 tandby: do nothing Inquire: search for other devices age: connect to a specific device Connected: participate in a piconet ark: release AA, get A niff: listen periodically, not each slot Hold: stop ACL, CO still possible, possibly participate in another piconet detach standby transmit AA park A inquiry hold AA page connected AA sniff AA unconnected connecting active low power W.wan.4-23 W.wan.4-24 Bluetooth: baseband Addressing Logical address Active ember Address (A_ADDR, 3 bit) ax 2 3 = 8 active members arked ember Address (_ADDR, 8 bit) ax 2 8 = 256 parked members Device address, 48-bit, unique worldwide, is partitioned into 3 parts the lower address part (LA) is used in piconet ID, error checking, security check, etc. the remaining two parts are proprietary address of the manufacture organizations Bluetooth: connection management Initially, all the nodes in standby mode. omeone begins Inquiry/age to form a new piconet Inquiry, to collect information about nearby devices otential master: Inquiry: follow a known frequency hopping sequence (only 32 frequencies used with the fixed IAC (Inquiry Access Code)) to announce the master ID Upon receipt of DAC, goto age state otential slaves: Inquiry can: hopping at very slow speed for the same 32 frequencies Inquiry Response: upon receiving IAC, wait for a random time, then send DAC (Device Access Code) to request to join to the new piconet, goto age can state
W.wan.4-25 W.wan.4-26 Bluetooth: connection management age, to establish connection aster to be: age: adjust frequency and send a paging message to the slave to be to allow it join, with slave s FH known Responded back in previous Inquiry In an existing piconet, the master helped two slaves to form a new piconet age Response: Upon receipt of a slave s DAC, send page response message including CAC (Channel Access Code); Connection established lave to be age scan: upon receipt of aging message, respond back its DAC (Device Access Code) Waiting for CAC and then adjust clock to join piconet Bluetooth: baseband Access code derived from the master Three types CAC (Channel Access Code): Used to identify a piconet DAC (Device Access Code) Used for paging & its subsequent response IAC (Inquiry Access Code) Used for inquiry phase W.wan.4-27 W.wan.4-28 Bluetooth: baseband Low-level packet definition Access code derived from the master acket header, 18-bit, with 1/3 FEC to have 54-bit 3-bit A_ADDR (broadcast + 7 slaves), 4-bit packet type, 1-bit flow control, alternating bit ARQ/EQ, 8-bit header-error-control 4 64 (4) preamble sync. (trailer) 68(72) 54 0-2745 bits access code packet header payload 3 4 1 1 1 8 bits A address type flow ARQN EQN HEC Bluetooth AC: packets acket formats Access Code, 48-bit, 2/3 FEC 72-bit acket Header, 18-bit, 1/3 FEC 54-bit ayload, max 2745 ignaling (control) packets ID, Null, oll, FH, D1, Data/voice packets CO: Voice HV1, HV2, HV3, DV, ACL: Data D1, D2, D3,
W.wan.4-29 W.wan.4-30 Bluetooth AC: L L (Link anagement rotocol) ower management ecurity management Authentication on device Challenge-response mechanism Based on a commonly shared secret key Generated by IN (personal identification number) Encryption on link Bluetooth AC: low power ower saving in an active state Receiver can determine quickly if continued reception needed or not by correlating incoming packet with piconet access code If not (takes 100μs), return to sleep for this receiving slot, as well as the following sending slot unless it s master If yes, detect the destination slave address If matched, continue receiving Otherwise, go back to sleep for this receiving slot, as well as the following sending slot Low power states ark, Hold, niff W.wan.4-31 W.wan.4-32 Bluetooth AC: low power HOLD mode Low power state Devices connected but not participating If no communication needed for some time, master can put slave in HOLD mode to allow a slave to Goto sleep witch to another piconet erform scanning, inquiry or paging After Hold expires, slave returns to channel CO: ynchronization remains during HOLD period, no ACL NIFF mode, similar to HOLD mode lave can skip some receive slots to save power aster and slave agree on which slots slave will listen to channel Bluetooth AC: low power ARK mode -- Low power state otivation Low duty-cycle mode low power Help master to handle more than 7 slaves Give up its A_ADDR, obtain a 8-bit _ADDR lave wakes up occasionally to resynchronize with master & check for broadcasting aster establishes beacon channel Enable parked slaves to remain synchronized to piconet Allow master to broadcast (dest addr: all 0s) lave cannot communication until unpacked
W.wan.4-33 W.wan.4-34 Bluetooth: low power example ower consumption in BlueCore 2: typical Average Current Consumption, with VDD=1.8V Temperature = 20 C Active ode CO connection HV3 (1s interval niff ode) (lave) CO connection HV3 (1s interval niff ode) (aster) CO connection HV1 (lave) CO connection HV1 (aster) ACL data transfer 115.2kbps UART (aster) ACL data transfer 720kbps UB (lave) ACL data transfer 720kbps UB (aster) 26.0 ma 26.0 ma 53.0 ma 53.0 ma 15.5 ma 53.0 ma 53.0 ma ACL connection, niff ode 40ms interval, 38.4kbps UART 4.0 ma ACL connection, niff ode 1.28s interval, 38.4kbps UART 0.5 ma Low power mode arked lave, 1.28s beacon interval, 38.4kbps UART 0.6 ma tandby ode (Connected to host, no RF activity) 47.0 µa Deep leep ode(2) 20.0 µa ource: www.csr.com ANs: Bluetooth & 802.15 Bluetooth Overview iconets & catternets HY layer AC layer Logical Link Control anagement 802.15 & others End W.wan.4-35 W.wan.4-36 Bluetooth: L2CA L2CA (Logical Link Control and Adaptation rotocol) imple data link protocol on top of baseband Connection oriented Connectionless, and ignaling channels rotocol multiplexing RFCO, D, telephony control egmentation & reassembly Up to 64kbyte user data, 16 bit CRC used from baseband Qo flow specification per channel Follows RFC 1363, specifies delay, jitter, bursts, bandwidth Group abstraction Create/close group, add/remove member Bluetooth: L2CA Establish logical channels over baseband L2CA baseband lave aster lave L2CA L2CA 2 d 1 1 d d d d 1 1 d d 2 baseband baseband signalling ACL connectionless connection-oriented
W.wan.4-37 W.wan.4-38 L2CA packet formats L2CA packet formats CID=1, signal CID=2, ACL CID, CO Connectionless DU 2 2 2 0-65533 bytes length CID=2 payload Connection-oriented DU 2 2 0-65535 bytes length CID payload ignaling command DU 2 2 bytes length CID=1 One or more commands 1 1 2 0 code ID length data ANs: Bluetooth & 802.15 Bluetooth Overview iconets & catternets HY layer AC layer Logical Link Control anagement 802.15 & others End W.wan.4-39 W.wan.4-40 Bluetooth: D D (ervice Discovery rotocol) Inquiry/response protocol for discovering services earching for and browsing services in radio proximity Adapted to the highly dynamic environment Can be complemented by others like L, Jini, alutation, Defines discovery only, not the usage of services Caching of discovered services Gradual discovery ervice record format Information about services provided by attributes Attributes are composed of an 16 bit ID (name) and a value values may be derived from 128 bit Universally Unique Identifiers (UUID) Bluetooth: apps support RFCO Emulation of a serial port (supports a large base of legacy applications) Allows multiple ports over a single physical channel Telephony Control rotocol pecification (TC) Call control (setup, release) Group management OBEX Exchange of objects, IrDA replacement WA Interacting with applications on cellular phones
W.wan.4-41 W.wan.4-42 Bluetooth: profiles Represent default solutions for a certain usage model Vertical slice through the protocol stack Basis for interoperability 13 profiles group into 4 categories: Generic profiles: Generic Access Applications D Telephony profiles Cordless, Intercom Headset rofile Networking profiles LAN, FAX, dialup erial profiles rofiles erial port, UB rotocols ANs: Bluetooth & 802.15 Bluetooth Overview iconets & catternets HY layer AC layer Logical Link Control anagement 802.15 & others End W.wan.4-43 W.wan.4-44 WAN: IEEE 802.15 802.15-2: Coexistance Coexistence of Wireless ersonal Area Networks (802.15) and Wireless Local Area Networks (802.11), quantify the mutual interference 802.15-3: High-Rate tandard for high-rate (20bit/s or greater) WANs, while still low-power/low-cost Data Rates: 11, 22, 33, 44, 55 bit/s Qo isochronous protocol Ad hoc peer-to-peer networking ecurity Designed to meet the demanding requirements of portable consumer imaging and multimedia applications WAN: IEEE 802.15 everal working groups extend the 802.15.3 standard 802.15.3a: Alternative HY with higher data rate as extension to 802.15.3 Applications: multimedia, picture transmission 802.15.3b: Enhanced interoperability of AC Correction of errors and ambiguities in the standard 802.15.3c: Alternative HY at 57-64 GHz Goal: data rates above 2 Gbps
W.wan.4-45 W.wan.4-46 WAN: IEEE 802.15 & ZigBee 802.15-4: Low-Rate, Very Low-ower Low data rate solution with multi-month to multi-year battery life and very low complexity otential applications are sensors, interactive toys, smart badges, remote controls, and home automation Data rates of 20-250 kbit/s, latency down to 15 ms aster-lave or eer-to-eer operation Up to 254 devices or 64516 simpler nodes upport for critical latency devices, such as joysticks 16 channels in the 2.4 GHz I band, 10 channels in the 915 Hz U I band ZigBee Relation to 802.15.4 similar to Bluetooth / 802.15.1 ushed by Chipcon, ember, freescale (otorola), Honeywell, itsubishi, otorola, hilips, amsung ore than 150 members romoter (40000$/Jahr), articipant (9500$/Jahr), Adopter (3500$/Jahr) No free access to the specifications (only promoters and participants) ZigBee platforms comprise IEEE 802.15.4 for layers 1 and 2 ZigBee protocol stack up to the applications W.wan.4-47 W.wan.4-48 WAN: IEEE 802.15.4 Other IEEE802.xx 802.15.4a: Alternative HY with lower data rate as extension to 802.15.4 roperties: precise localization (< 1m precision), extremely low power consumption, longer range Two HY alternatives UWB (Ultra Wideband): ultra short pulses, communication and localization C (Chirp pread pectrum): communication only 802.15.4b: Extensions, corrections, and clarifications regarding 802.15.4 Usage of new bands, more flexible security mechanisms 802.15.5: esh Networking artial meshes, full meshes Range extension, more robustness, longer battery live IEEE 802.16: Broadband Wireless Access/ WirelessAN/Wiax Wireless distribution system, e.g., for the last mile, alternative to DL 75 bit/s up to 50 km LO, up to 10 km NLO; 2-66 GHz band Initial standards without roaming or mobility support 802.16e adds mobility support, allows for roaming at 150 km/h Unclear relation to 802.20, 802.16 started as fixed system IEEE 802.20: obile Broadband Wireless Access (BWA) Licensed bands < 3.5 GHz, optimized for I traffic eak rate > 1 bit/s per user Different mobility classes up to 250 km/h and ranges up to 15 km IEEE 802.22: Wireless Regional Area Networks (WRAN) Radio-based HY/AC for use by license-exempt devices on a noninterfering basis in spectrum that is allocated to the TV Broadcast ervice
W.wan.4-49 W.wan.4-50 802.11 vs. 802.15/Bluetooth f [Hz] 2402 Bluetooth may act like a rogue member of the 802.11 network Does not know anything about gaps, inter frame spacing etc. IEEE 802.15-2 discusses these problems roposal: Adaptive Frequency Hopping a non-collaborative Coexistence echanism Real effects? any different opinions, publications, tests, formulae, Results from complete breakdown to almost no effect Bluetooth (FH) seems more robust than 802.11b (D) 2480 802.11b DIF DIF 500 byte DIF 100 byte IF IF DIF DIF 100 byte 1000 byte IF 500 byte DIF 100 byte IF IF DIF IF DIF DIF 100 byte IF 500 byte DIF 100 byte IF 3 channels (separated by installation) 802.15.1 79 channels (separated by hopping pattern) t Readings Textbooks C.. Ram urthy & B.. anoj, Ad Hoc Wireless Networks, Chapter 2.5, Bluetooth, pages 88-98. W. tallings, Wireless Communications & Networks, Chapter 15, Bluetooth and IEEE 802.15, pages 463-510. W.wan.4-51 ANs: Bluetooth & 802.15 Bluetooth Overview iconets & catternets HY layer AC layer Logical Link Control anagement 802.15 & others End