IEEE MAC and PHY Specifications for Broadband WMAN

Transcription

1 IEEE MAC and PHY Specifications for Broadband WMAN 中央大學通訊系許獻聰 edu.tw TKU HSNL WMAN - 1

2 Resources Part Source : Roger B. Marks, National Institute of Standards and Technology Boulder, Colorado, USA Chair, IEEE Working Group TKU HSNL WMAN - 2

3 Broadband Access to Buildings Metro Ethernet Wireless Ethernet First/Last mile access Fast local connection to network Target Applications (similar as DSL and CableModem)» Data» Voice» Video distribution» Real-time videoconferencing High-capacity cable/fiber to every user is expensive Network operators demand it Business and residential customers demand it TKU HSNL WMAN - 3

4 Wireless Metropolitan Area Network TKU HSNL WMAN - 4

5 Application TKU HSNL WMAN - 5

6 Features (1/2) Broad bandwidth Up to Mbit/s in 28 MHz channel (in GHz) (UWB?)» 32Mb/s Mb/s» 20/25/28MHz per channel line of sight is required and multipath is negligible (short wavelength). Supports multiple services simultaneously with full QoS Efficiently transport IPv4, IPv6, ATM, Ethernet, etc. Wireless transportation system. Bandwidth on demand (frame by frame) Similar to HIPERLAN Type II (frame-based protocol) Centralized control MAC designed for efficient used of spectrum Comprehensive, modern, and extensible security ()tensions to mobility are coming next. TKU HSNL WMAN - 6

7 Features (2/2) Supports multiple frequency allocations from 2-66 GHz in (10-66GHz) and a (2-11GHz) Single carrier (SC) for line-of of-sight situations OFDM and OFDMA for non-line line-of-sight situations» OFDMA : orthogonal frequency division multiple access Access schemes: TDD (time division duplex) and FDD (frequency division duplex) Link adaptation: Adaptive modulation and coding Point-to-multipoint (star) topology and mesh network extension Support for adaptive antennas and space-time coding (in a) Extensions to mobility. (IEEE e started from Jan. 2003) ()tensions to mobility are coming next. TKU HSNL WMAN - 7

8 IEEE Standard and amendments Fixed Broadband Wireless Access (FBWA) Systems Air Interface (MAC and PHY) Band 10-66GHz (ranges 1/2/3 : GHz/ GHz) 25/28MHz per channel 23.5GHz/ GHz/43.5- line-of of-sight (LOS) requirement One PHY» WirelessMAN-SC (Single Sarrier) Point-to to-multipoint Topology (Star) TDD/FDD with burst profile option (depending on SNR) Completed in October 2001 Published in April 2002 Followup interoperability projects c (Profiles): published in Jan (PICS): in ballot; completion expected Mar 2003» PICS : Protocol Implementation Conformance Statement ( 10-66GHz Coexistence of FBWA Systems )» Focus on 23.5 to 43.5 GHz (local multipoint distribution service (LMDS), millimeter wave, etc.,)» WiMAX submitted proposal in Jan 2003 TKU HSNL WMAN - 8

9 IEEE a Standard Medium Access Control Modifications and Additional Physical Layer Specifications for 2 11 GHz Band 2-11GHz Non-line line-of-sight (NLOS) requirement and Multi-path issue Near-LOS License-exempt exempt band GHz (802.11a and HIPERLAN II) Three PHYs» WirelessMAN-SC2 (single carrier)» WirelessMAN-OFDM (multiple carriers with 256-point transform) is mandatory for license exempt bands» WirelessMAN-OFDMA (multiple carriers with 2048-point transform) Multiple access is provided by addressing a subset of the multiple carriers to individual receivers. Advanced Antenna Systems (AAS) is optional Add mesh network topology (MAC) provide automatic repeat request (ARQ) retransmission (MAC) Completed in November 2002 and Approved April 2003 IEEE e (mobility) first meeting in 2004 D5 IEEE a (coexistence including 2-11GHz) TKU HSNL WMAN - 9

10 IEEE a Standard license-exempt bands below 11 GHz The PHY and MAC introduce mechanisms such as dynamic frequency selection (DFS) to detect and avoid interference. TKU HSNL WMAN - 10

11 IEEE Standard IEEE Std Air Interface for Fixed Broadband Wireless Access Systems - IEEE d Approved 24 June 2004 This standard revises and consolidates IEEE Std , IEEE Std a -2003, and IEEE Std c IEEE Std f MIB IEEE Std g System/resource/handover Management Interoperability TKU HSNL WMAN - 11

12 IEEE e Enhance IEEE PHY is similar to Focus on 2-6GHz MHZ per channel Enhance OFDMA PHY Data rate» Supports 2048-point, 1024-point, 512-point and 128-point FFT 10Mhz/channel, OFDM-64QAM provides 30Mbps Max. moving speed : 120km/h Range : several Kms Chip appears in 2006 vs. IEEE Below 3.5GHz Max. moving speed : 250Km/h (high-speed train) vs. 3G TKU HSNL WMAN - 12

13 Wimax Evolution Source : Siemens, 2004 TKU HSNL WMAN - 13

14 WiMAX Forum WiMAX (Worldwide Interoperability for Microwave Access) Like WECA in IEEE WLAN Mission: To promote deployment of BWA by using a global standard and certifying interoperability of products and technologies. Principles: Support IEEE x 2-66 GHz (16a : 2-11 GHz and 16 : 10-66GHz) Propose access profiles for the IEEE standard Guarantee known interoperability level Open for everyone to participate Developing & submitting baseline test specs TKU HSNL WMAN - 14

15 Point-to-Multipoint configuration Two components Subscriber Stations (SSs( SSs)» SS typically serves a building (business or residence) Base Station (BS)» connected to public networks» BS serves Subscriber Stations» provide SS with first-mile(or last mile) access to public networks Compared to a Wireless LAN Multimedia QoS not only contention-based connection-oriented Many more users Much higher data rates Much longer distances TKU HSNL WMAN - 15

16 Mesh Topology (defined in a) Dynamic topology Self-organizing network More complicated TKU HSNL WMAN - 16

17 IEEE vs. ETSI Frequent communications between WG and ETSI (European Telecom Standards Institute) ETSI HIPERACCESS Above 11 GHz (outdoor, 11-40GHz, 5Km, 25Mb/s) ETSI began first, but IEEE finished first has encouraged harmonization ETSI HIPERMAN Below 11 GHz (outdoor) IEEE began first Healthy cooperation Harmonized with a OFDM HIPERMAN ETSI HIPERLAN 5GHz (indoor/outdoor) 6-54Mb/s Irrelative with ETSI HIPERLINK 17GHz (150m, point-2-point) point) 155Mb/s (OC3) Irrelative with TKU HSNL WMAN - 17

18 MAC Overview Connection-oriented oriented Supports difficult user environments High bandwidth, hundreds of users per channel For variable Continuous and burst traffic Very efficient use of spectrum Protocol-Independent core (ATM, IP, Ethernet, ) Balances between stability of contentionless and efficiency of contention-based operation Negotiate the burst profile between sender and receiver Flexible QoS offerings CBR, rt-vbr, nrt-vbr, BE, with granularity within classes Supports multiple PHYs TKU HSNL WMAN - 18

19 Protocol Stack Packet convergence Sublayer (PCS) ATM packet SSCS (security sublayer ) TKU HSNL WMAN - 19

20 Service Specific Convergence Sublayer (SSCS) The CS performs the following functions: accepting higher-layer PDUs from the higher layer performing classification of higher-layer PDUs processing (if required) the higher-layer PDUs based on the classification delivering CS PDUs to the appropriate MAC SAP receiving CS PDUs from the peer entity Currently, two CS specifications are provided Asyncronous Transfer Mode (ATM) CS Packet CS» Such as IP, PPP, Ethernet, etc., Other CSs may be specified in the future. TKU HSNL WMAN - 20

21 Packet Convergence Sublayer (PCS) Packet convergence sublayer (PCS) The packet CS resides on top of the Common Part Sublayer (CPS) The PCS performs the following functions, utilizing the services of the MAC sublayer: a) Classification of the higher-layer protocol PDU into the appropriate connection b) Suppression of payload header information (optional) c) Delivery of the resulting CS PDU to the MAC SAP associated with the service flow for transport to the peer MAC SAP d) Receipt of the CS PDU from the peer MAC SAP e) Rebuilding of any suppressed payload header information (optional) TKU HSNL WMAN - 21

22 Packet Process Procedure A classifier is a set of matching criteria applied to each packet It consists of some protocol-specific packet matching criteria (destination IP address, for example), a classifier priority, and a reference to a CID. The service flow characteristics of the connection provide the QoS for that packet Several classifiers may each refer to the same service flow. Downlink classifiers are applied by the BS to packets it is transmitting and uplink classifiers are applied at the SS. a packet fails to match the set of defined classifiers. CS/SS shall discard the packet. Packet Classifier(s) CID/SFID CID PHSI mapper SFID SFID/QoS mapper SFID/PHSI (sender) CID/PHSI (receiver) PHS ruler QoS Parameters (used in scheduler) TKU HSNL WMAN - 22

23 Common Part Sublayer (CPS) The MAC CPS provides the core MAC functionality of system access, bandwidth allocation, connection establishment, and connection maintenance: a) System Access b) Bandwidth Request/Allocation c) Connection Establishment/Maintenance e) Quality of Service (QoS( QoS) TKU HSNL WMAN - 23

24 Security Sublayer The security sublayer providing a) authentication, b) secure key exchange, and c) Encryption Two component protocols Encapsulation protocol» Cryptographic suites Key management protocol (PKM)» Create and exchange traffic encryption key (TEK) TKU HSNL WMAN - 24

25 Classifications A MAC SDU is mapped onto a particular connection for transmission between MAC peers According to protocol-specific packet matching criteria (e.g. destination IP address), classifier priority and a reference to a CID (connection ID)» creates an association with the service flow ID (SFID) 32 bits service flow ID (SFID) Conn. ID (CID) PHS CID+PHSI PHS TKU HSNL WMAN - 25

26 Classifications PHS service flow ID (SFID) Conn. ID (CID) TKU HSNL WMAN - 26

27 Classifications A MAC SDU is mapped onto a particular connection for transmission between MAC peers according to protocol-specific packet matching criteria (e.g. IP address), classifier priority and a reference to a CID. SS and BS use multiple classifiers. Each classifier contains a priority field which determines the search order for the classifier. Searching algorithm is similar to policy-based search algorithm (e.g. Firewall) Classifiers can be added by dynamic signaling. Simple Network Management Protocol (SNMP)- based operations can only view Classifiers, no add/delete TKU HSNL WMAN - 27

28 Payload Header Suppression (PHS) For some payload protocols, each payload consists of an 8-bit payload header suppression index (PHSI) followed by the actual payload. A value of zero in the PHSI indicates no payload header suppression has been applied to the PDU. Otherwise, the value in the index identifies the rules for suppression. MAC header 8-bit PHSI refer the payload header suppression field (PHSF) TKU HSNL WMAN - 28

29 Payload Header Suppression (PHS) If PHS is enabled at MAC connection, each MAC SDU is prefixed with a PHSI, which references the Payload Header Suppression Field (PHSF). The classifier uniquely maps packets to its associated PHS Rule. The receiving entity uses the CID and the PHSI to restore the PHSF. (CID+PHSI PHSF/PHSM/PHSS) When a classifier is deleted, any associated PHS rule shall also be deleted. TKU HSNL WMAN - 29

30 PHS operation TKU HSNL WMAN - 30

31 Payload Header Suppression (PHS) Rule Payload header suppression valid (PHSV) : option to verify or not verify the payload header before suppressing it Payload header suppression mask (PHSM) option to allow select bytes not to be suppressed. Such as IP sequence numbers should not be supressed Payload header suppression size (PHSS) Payload header suppression field (PHSF) Payload header suppression index (PHSI) Service flow ID (SFID). PHS rules are indexed by the combination of (SFID, PHSI) Preconfigured header format or higher-level signaling protocols are outside the scope of specification TKU HSNL WMAN - 31

32 PHS with masking A,C,E are compressed Only sends B and E TKU HSNL WMAN - 32

33 PHS Rules The BS shall define the PHSI when the PHS Rule is created The SS or BS may define the PHSS and PHSF. To change the value of a PHSF on a service flow, a new PHS rule shall be defined It is possible to partially specify a PHS rule (in particular the size of the rule) at the time a service flow is created Values of some fields [for example: IP addresses, User Datagram Protocol (UDP) port numbers, etc.] may be unknown and would be provided in a subsequent DSC as part of the activation of the service flow using the Set PHS Rule DSC Action TKU HSNL WMAN - 33

34 PHS Signaling PHS requires the creation of the following three objects: a) Dynamic Service Flow (DSA/DSC/DSD) Addition/Change/Deletion b) Classifier c) PHS rule (PHSI is assigned by BS) TKU HSNL WMAN - 34

35 Connection ID (CID) A unidirectional mapping between BS and SS MAC peers for the purpose of transporting a service flow s traffic Connections are identified by a connection identifier (CID) All traffic is carried on a connection, even for service flows that implement connectionless protocols CID maps to a service flow identifier (SFID), which defines the Quality of Service (QoS( QoS) parameters of the service flow associated with that connection. Security associations (SAs( SAs) also exist between keying material and CIDs. TKU HSNL WMAN - 35

36 Connection ID (CID) Connections are identified by a 16-bit CID At SS initialization, three management connections in each direction (uplink and downlink) shall be established between the SS and the BS. The basic connection is used for exchanging short, time- urgent management messages.» such as DBPC-REQ/RSP : Downlink Burst Profile Change Req/Rsp, RNG-REQ/RSP : Ranging Req/Rsp The primary management connection is used for exchanging longer, more delay tolerant MAC management messages.» Such as DSA/DSC/DSD_REQ/RSP/ACK, REG_REQ/RSP The Secondary Management Connection is used for transferring delay tolerant, standards based DHCP, TFTP, SNMP, etc., management messages. TKU HSNL WMAN - 36

37 Connection ID (CID) BS returns Basic CID and Primary CID to SS via RNG-RSP messages. BS returns Secondary CID to SS via REG-RSP messages (optional). The same CID value is assigned to both members (uplink and downlink) of each connection pair. Many higher-layer sessions may operate over the same wireless CID. TKU HSNL WMAN - 37

38 Connection ID (CID) TKU HSNL WMAN - 38

39 MAC Protocol TKU HSNL WMAN - 39

40 MAC overview Wireless link operates with sectorized antenna is capable of handling multiple independent sectors simultaneously (channel reuse) Subscriber stations share the uplink to the BS on a demand basis. Four different types of uplink scheduling mechanisms Unsolicited bandwidth grants (CBR) Polling (unicast polling)» guarantees applications receive service on a deterministic basis (delay tolerant services) Contention procedures» contention may be used to avoid individual polling of SSs that have been inactive for a long period (multicast/broadcast polling) Bandwidth stealing» a portion of the bandwidth allocated in response to a bandwidth request for a connection to send another bandwidth request rather than sending data Piggyback (via grant subheader ; w/o scheduling) TKU HSNL WMAN - 40

41 MAC overview Service flows provide a mechanism for uplink and downlink QoS management. In particular, they are integral to the bandwidth allocation process. An SS requests uplink bandwidth on a per connection basis (implicitly identifying the service flow). Bandwidth is granted by the BS to an SS as an aggregate of grants in response to per connection requests from the SS. TKU HSNL WMAN - 41

42 MPDU format 6 octets MAC PDU formats CRC capability is mandatory for SCa, OFDM and OFDMA PHY layers HT=0 Generic HT=1 Bandwidth Request Connections are identified by a 16-bit CID. TKU HSNL WMAN - 42

43 Generic MAC Header Management frame TKU HSNL WMAN - 43

44 Type encodings (in Generic Header) Type bits Bit mapping TKU HSNL WMAN - 44

45 Bandwidth Request MAC Header 000 : incremental (BS adds the needed quantity of CID) 001 : aggregate (BS replaces the needed quantity of CID) TKU HSNL WMAN - 45

46 Bandwidth Request The Bandwidth Request shall have the following properties: a) length of the header = 6 bytes b) EC field = 0 (indicating no encryption) c) CID (Basic) indicates the connection for which uplink bandwidth is requested. d) Bandwidth Request (BR) field indicates the number of bytes requested. e) The allowed types for bandwidth requests are 000 for incremental and 001 for aggregate. TKU HSNL WMAN - 46

47 Subheader Types Five types of subheaders Mesh Fragmentation FASTFEEDBACK_Allocation (MIMO) Grant Management Packing The subheaders are inserted in MAC PDUs immediately following the Generic MAC header. Sequence» Grant -> Fragmentation» Mesh -> others» others -> FastFeedback_allocation The Packing and Fragmentation subheaders are mutually exclusive and shall not both be present within the same MAC PDU TKU HSNL WMAN - 47

48 MPDU Transmission long Ethernet packet Short ATM cells TKU HSNL WMAN - 48

49 Concatenation Mandatory capability Multiple MAC PDUs may be concatenated into a single transmission in either the uplink or downlink directions. each MAC PDU is identified by a unique CID Bandwidth stealing TKU HSNL WMAN - 49

50 Packing The capability of unpacking is mandatory. pack multiple MAC SDUs into a single MAC PDU. Differs from concatenation Packing makes use of the connection attribute indicating whether the connection carries fixed- length or variable-length length packets. The construction of PDUs varies for ARQ and non- ARQ connections with respect to packing and fragmentation syntax TKU HSNL WMAN - 50

51 Packing for non-arq connections Packing fixed-length MAC SDUs the Request/Transmission Policy shall be set to allow packing and prohibit fragmentation, and the SDU size shall be included in DSA-REQ message when establishing the connection If the MAC SDU size is n bytes, the receiver unpacks simply by knowing that the length field in the MAC header will be n k+j, where k is the number of MAC SDUs packed into the MAC PDU and j is the size of the MAC header and any prepended MAC subheaders. no added overhead TKU HSNL WMAN - 51

52 Packing for non-arq connections Packing variable-length MAC SDUs indication of where one MAC SDU ends and another begins. the MAC attaches a Packing subheader (PSH) to each MAC SDU unfragmented MAC SDUs and MAC SDU fragments may both be present in the same MAC PDU TKU HSNL WMAN - 52

53 Packing for non-arq connections Simultaneous fragmentation and packing allows efficient use of the airlink when a Packing subheader (PSH) is present, the fragmentation information for individual MAC SDUs or MAC SDU fragments is contained in the corresponding Packing subheader. Else (If no PSH is present), the fragmentation information for individual MAC SDU fragments is contained in the corresponding Fragmentation subheader (FSH) TKU HSNL WMAN - 53

54 Packing for non-arq connections PSH FSH PSH TKU HSNL WMAN - 54

55 Packing for ARQ-enabled connections Each of the packed MAC SDU or MAC SDU fragments or ARQ feedback payload requires its own Packing subheader A MAC SDU may be partitioned into multiple fragments that are then packed into the same MAC PDU for the first transmission. MAC PDUs may have fragments from the same or different SDUs, including a mix of first transmissions and retransmissions. The 11-bit BSN and 2-bit FC fields uniquely identify each fragment or non-fragmented SDU. TKU HSNL WMAN - 55

56 Payload Type Payload Type indicates whether MAC subheaders (Packing/Fragmentation/Grant) present or not. packing/ fragmentation packing/ fragmentation/ grant/ p+g/ f+g TKU HSNL WMAN - 56

57 MAC Subheader Three types of MAC subheaders may be present. The grant management subheader is used by an SS to convey bandwidth management needs to its BS. The fragmentation subheader contains information that indicates the presence and orientation in the payload of any fragments of SDUs. (e.g. long Ethernet packet) The packing subheader is used to indicate the packing of multiple SDUs into a single PDU. (e.g. ATM cells) TKU HSNL WMAN - 57

58 Fragmentation Subheader format TKU HSNL WMAN - 58

59 Grant Subheader format (incremental mode only 16bits vs. 19 bits) is used to request to be polled for a different, non-ugs connection set when service flow has exceeded its transmit queue depth TKU HSNL WMAN - 59

60 Packing Subheader format TKU HSNL WMAN - 60

61 MAC Management Messages MAC Management messages on the Basic, Broadcast, and Initial Ranging connections shall neither be fragmented nor packed. Primary Management is allowed! 1 byte TKU HSNL WMAN - 61

62 MAC Management Messages TKU HSNL WMAN - 62

63 MAC Management Messages TKU HSNL WMAN - 63

64 MAC Management Messages AAS : adaptive antenna system TKU HSNL WMAN - 64

65 SS Initialization Overview Downlink Sync Auth. Key Xchange Get Uplink Parameters Setup Time Ranging Register Download Configuration File Capability Negotiation DHCP Setup connection and service flow TKU HSNL WMAN - 65

66 Steps 1) Scan for downlink channel and establish synchronization with the BS 2) Obtain transmit parameters (from UCD message) (uplink channel descriptor) 3) Perform ranging (RNG( RNG-REQ REQ and RNG-RSP RSP) 4) Negotiate basic capabilities 5) Authorize SS and perform key exchange 6) Perform registration 7) Establish IP connectivity (DHCP( DHCP) optional 8) Establish time of day optional 9) Transfer operational parameters (TFTP( TFTP) optional 10) Set up connections Option : indicated by REG-REQ message TKU HSNL WMAN - 66

67 Uplink Channel Descriptor (UCD) message Configuration Change Count Incremented by one (modulo 256) by the BS whenever any of the values of this channel descriptor change. This value is also referenced from the UL-MAP messages. Ranging Backoff Start Initial backoff window size for initial ranging contention Ranging Backoff End Final backoff window size for initial ranging contention Request Backoff Start Initial backoff window size for contention BW requests Request Backoff End Final backoff window size for contention BW requests All above parameters are expressed as a power of 2. Values of n range 0 15 the highest order bits shall be unused and set to 0 The Uplink_Burst_Profile is a compound TLV encoding that associates with a UIUC, TKU HSNL WMAN - 67

68 Uplink map (UL-MAP) message Uplink Channel ID (for Channelized PHY) UCD Count Matches the value of the Configuration Change Count of the UCD, which describes the uplink burst profiles that apply to this map. Allocation Start Time Effective start time of the uplink allocation defined by the UL-MAP units are PHY-specific (pp. 153)» minislots : SC and SCa PHY layers» symbols and subchannels : OFDM and OFDMA PHY layers Map IEs The contents of a UL-MAP IE is PHY-specification dependent. TKU HSNL WMAN - 68

69 Uplink interval definition Request IE BS specifies an uplink interval for bandwidth requests The character of this IE changes depending on the type of CID used in the IE» Broadcast or multicast CID (poll) : an invitation for SSs to contend for requests.» Unicast CID (poll) : an invitation for a particular SS to request bandwidth» part of a QoS scheduling scheme that is vendor dependent For bandwidth request contention opportunities, the BS shall allocate a grant that is an integer multiple of the value of Bandwidth request opportunity size (in unit of PS) which shall be published in each UCD transmission. TKU HSNL WMAN - 69

70 Uplink interval definition Initial Ranging IE An interval is allocated in UL-MAPs» the maximum round-trip propagation delay plus the transmission time of the RNG-REQ message For ranging contention opportunities, the BS shall allocate a grant that is an integer multiple of the value of Ranging request opportunity size, (in unit of PS) which shall be published in each UCD transmission. Data Grant Burst Type IEs provide an opportunity for an SS to transmit one or more uplink PDUs. TKU HSNL WMAN - 70

71 Ranging request (RNG-REQ) message transmitted by the SS at initial ranging (initialization) and data grant intervals (periodically) To determine network delay To determine power To change downlink burst profile If sent in a data grant interval, the CID is always equal to the Basic CID. the SS received the UCD TKU HSNL WMAN - 71

72 Ranging Request (RNG-REQ) message when the SS is attempting to join the network, two parameters are included in the RNG-REQ message Requested Downlink Burst Profile (1 byte)» Bits 0-3 : DIUC» Bits 4-7 : 4 LSB of Configuration Change Count value SS MAC Address during initial ranging on the SS s Basic connection, the parameter MAC Version is provided 1 : : c-2002 and its predecessors 3 : a-2003 and its predecessors 4 : AAS broadcast capability may be included in the RNG-REQ message: Applied for SCa/OFDM/OFDMA TKU HSNL WMAN - 72

73 Ranging Request (RNG-REQ) message after the SS has received an RNG-RSP, two parameters are included in the subsequent RNG-REQ message : Requested Downlink Burst Profile (1 byte)» Bits 0-3 : DIUC» Bits 4-7 : 4 LSB of Configuration Change Count value Ranging Anomalies (1 byte)» Bit #0 SS already at maximum power.» Bit #1 SS already at minimum power.» Bit #2 Sum of commanded timing adjustments is too large. TKU HSNL WMAN - 73

74 Ranging response (RNG-RSP) message transmitted by the BS in response to a received RNG-REQ may also be transmitted asynchronously to send corrections based on measurements that have been made on other received data or MAC messages TKU HSNL WMAN - 74

75 Ranging response (RNG-RSP) message Ranging Status 1 = continue, 2 = abort, 3 = success, 4 = rerange Timing Adjust Information (signed 32-bit) Power Adjust Information (signed 8-bit, 0.25 db units) Downlink Frequency Override Center frequency, in khz, SS redoes initial ranging. Uplink Channel ID Override Licensed bands: The identifier of the uplink channel with which the SS is to redo initial ranging License-exempt bands: The Channel Nr where the SS should redo initial ranging. Downlink Operational Burst Profile (2 bytes) Byte 0: the least robust DIUC that may be used by the BS for transmissions to the SS. Byte 1: Configuration Change Count value of DCD defining the burst profile associated with DIUC. TKU HSNL WMAN - 75

76 Ranging response (RNG-RSP) message Basic CID (2 bytes) A required parameter if the RNG-RSP message is being sent on the Initial Ranging CID in response to a RNG-REQ message that was sent on the Initial Ranging CID. Primary Management CID (2 bytes) A required parameter if the RNG-RSP message is being sent on the Initial Ranging CID in response to a RNG-REQ message that was sent on the Initial Ranging CID. SS MAC Address (48-bit) A required parameter when the CID in the MAC header is the Initial Ranging CID. Offset Frequency Adjust Information (signed 32- bit, Hz units) fine-frequency adjustment within a channel AAS broadcast permission TKU HSNL WMAN - 76

77 Ranging response (RNG-RSP) message WirelessMAN-SCa or WirelessMAN-OFDM PHY-specific parameters Frame Number (3 bytes)» the corresponding RNG-REQ message or subchannelized initial ranging indication (for OFDM) was received.» When Frame Number is included, SS MAC Address shall not appear. Initial Ranging Opportunity Number (1 byte)» Initial Ranging opportunity within the frame in which the corresponding RNG-REQ message or subchannelized initial ranging indication (for OFDM) was received.» If not provided, and Frame Number is included in the message, Initial Ranging Opportunity is assumed to be one. WirelessMAN-OFDM PHY-specific parameter Ranging Subchannel WirelessMAN-OFDMA PHY when an initial ranging message based on code division multiple access (CDMA) is received, Ranging code attributes (OFDMA time symbols reference, subchannel reference, and frame number) TKU HSNL WMAN - 77

78 Registration request (REG-REQ) message Include parameter: Primary Management CID (in the generic MAC header) The CID in the generic MAC header is the Primary Management CID for this SS, as assigned in the RNG-RSP message. TKU HSNL WMAN - 78

79 Registration request (REG-REQ) message The REG-REQ shall contain the following TLVs: Hashed Message Authentication Code (HMAC) Tuple» Shall be final attribute in the message s TLV attribute list.» In Mesh Mode, message digest is calculated using HMAC_KEY_U. IP Version SS Capabilities Encodings Vendor ID Encoding Vendor-specific information Convergence Sublayer Capabilities ARQ Parameters For PMP operation, the REG-REQ shall contain the following TLVs: Uplink CID Support SS management support» w/ or w/o secondary management connection IP management mode TKU HSNL WMAN - 79

80 Registration response (REG-RSP) message Include parameter: Primary Management CID (in the generic MAC header) Response» 0 = OK» 1 = Message authentication failure TKU HSNL WMAN - 80

81 Registration response (REG-RSP) message The REG-RSP shall contain the following TLVs SS Capabilities Encodings» Response to the capabilities of the requester provided in the REG-REQ.» indicates whether or not the capabilities may be used. IP Version Vendor ID Encoding Vendor-specific information ARQ Parameters» ARQ and fragmentation parameters specified by the BS to complete ARQ parameter negotiation for the secondary management connection. IP management mode» Response to REG-REQ indication of whether or not the requester wishes to accept IP-based traffic on the Secondary Management Connection, once the initialization process has completed. TKU HSNL WMAN - 81

82 Contention resolution Collisions may occur during Initial Ranging and Request intervals. After a contention transmission, the SS waits for a Data Grant Burst Type IE in a subsequent map (bandwidth request) waits for a RNG-RSP message (initial ranging) truncated binary exponential backoff with the initial backoff window and the maximum backoff window are controlled by the BS are specified as part of the UCD message and represent a power-of of-two value. Request IEs or Initial Ranging IEs allocate contention intervals in the UL-MAP messages Random backoff (in slots) may across multiple intervals assigned in IEs. TKU HSNL WMAN - 82

83 Contention resolution retry when range timeout (200ms no range response) data grant timeout (10ms no data grant - service QoS dependent) Until reaches the maximum number of retries while deferring, if SS receives a unicast Request IE or Data Grant Burst Type IE, it shall stop the contention resolution process BS may set up the Request (or Ranging) Backoff Start and Request (or Ranging) Backoff End to emulate an Ethernet-style backoff by setting Request (or Ranging) Backoff Start = 0 and Request (or Ranging) Backoff End = 10 in the UCD message Open issue for optimize window (beyond the scope of standard) TKU HSNL WMAN - 83

84 Transmission opportunities The size of an individual transmission opportunity for each type of contention IE shall be published in each transmitted UCD message. The BS shall always allocate bandwidth for contention IEs in integer multiples of these published values. WirelessMAN-SC system for example,» frame duration =1 ms,» each PS = 4 symbols, each minislot = 2 PSs,» uplink preamble =16 symbols = 2 minislots,» SS transition gap (SSTG) = 24 symbols = 3 minislots.» For QPSK, each transmission opportunity requires 8 minislots: 3 for the SSTG, 2 for the preamble, and 3 for the bandwidth request message.» This payload requirement would be specified as a value of 16 (pp. 167) assigned to the UCD TLV Bandwidth request opportunity size TKU HSNL WMAN - 84

85 Transmission opportunities One Request IE with 24 minislots indicates there will be three transmission opportunities TKU HSNL WMAN - 85

86 PHY Layer TKU HSNL WMAN - 86

87 Multiple Access and Duplexing On DL, SS addressed by BS in TDM stream On UL, SS is allotted a variable length TDMA slot Time-Division Duplex (TDD) DL & UL time-share the same RF channel Dynamic asymmetry (also named as Demand Assigned Multiple Access : DAMA) Half-duplex SS does not transmit/receive simultaneously (low cost) Frequency-Division Duplex (FDD) DL & UL on separate RF channels Static asymmetry Full-duplex SSs supported Half-duplex SSs supported (low cost)» SS does not transmit/receive simultaneously» Need resynchronization TKU HSNL WMAN - 87

88 TDD Frame Frame duration: 0.5/1/2 ms (SC), 2.5/4/5/8/10/12.5/20 ms (OFDM), 2/2.5/5/8/10/12.5/20ms (OFDMA) Physical Slot (PS) = 4 symbols (SC/a), 4/sampling_freq(Fs) (OFDM/A) Minislot : A unit of uplink bandwidth allocation equivalent to n physical slots (PSs( PSs), where n = 2 m and m is an integer ranging from 0 through 7. TKU HSNL WMAN - 88

89 Adaptive Burst Profiles Burst profile Modulations and FEC Dynamically assigned according to link conditions Burst by burst, per subscriber station Trade-off capacity vs. robustness in real time Roughly doubled capacity for the same cell Burst profile for downlink broadcast channel is wellknown and robust Other burst profiles can be configured on the fly SS capabilities recognized at registration» SBC-REQ/RSP TKU HSNL WMAN - 89

90 System Parameters QPSK, 16-QAM and 64-QAM TKU HSNL WMAN - 90

91 Radio Link control RLC control transition of burst profile power level ranging RLC begins with periodic BS broadcast of the burst profiles that have been chosen for the uplink and downlink according to rain region and equipment capabilities. Burst profiles for the downlink/uplink are each tagged with a Downlink/Uplink Interval Usage Code (DIUC/UIUC). TKU HSNL WMAN - 91

92 Ranging and Power Control During initialization, the SS performs initial power leveling and ranging using ranging request (RNG- REQ) messages transmitted in initial maintenance windows. The adjustments to the SS s transmit time advance, as well as power adjustments, are returned to the SS in ranging response (RNG-RSP) RSP) messages. For ongoing ranging and power adjustments, the BS may transmit unsolicited RNG-RSP RSP messages commanding the SS to adjust its power or timing. It is not included in burst profile TKU HSNL WMAN - 92

93 Burst Profile Set of parameters that describe the uplink or downlink transmission properties associated with an interval usage code (IUC). The burst profile to use for any uplink transmission is defined by the Uplink Interval Usage Code (UIUC). Each UIUC is mapped to a burst profile in the UCD message Each profile contains parameters such as a) modulation type b) forward error correction (FEC) type c) preamble length d) guard times TKU HSNL WMAN - 93

94 Burst Profile If the received CINR goes outside of the allowed operating region, the SS requests a change to a new burst profile using one of two methods If the SS has been granted uplink bandwidth, it shall send a DBPC-REQ message in that allocation. The BS responds with a DBPC-RSP message. If grant is not available and the SS requires a more robust burst profile on the downlink, it shall send a RNG-REQ message in an Initial Ranging interval. Note : using the Basic CID of the SS TKU HSNL WMAN - 94

95 Burst profile transition C/(N+I) :carrier to noise and interference ratio DL-MAP Ranging request (RNG-REQ) or downlink burst profile change request (DBPC-REQ) As SS receives unclear signals! Transition to a more robust burst profile. TKU HSNL WMAN - 95

96 Burst profile Transition C/(N+I) :carrier to noise and interference ratio As SS receives strong signals! Transition to a less robust burst profile. TKU HSNL WMAN - 96

97 Burst profile threshold C/(N+I) :carrier to noise and interference ratio TKU HSNL WMAN - 97

98 Map relevance and synchronization (TDD) ATDD : adaptive time division duplexing TKU HSNL WMAN - 98

99 Map relevance and synchronization (FDD) TKU HSNL WMAN - 99

100 Map relevance WirelessMAN-SC PHY & WirelessMAN-OFDM PHY Allocation Start Time (AST) is subject to the following limitations:» FDD : minimum AST value = round trip delay + T proc, maximum AST value = T f (i.e., the beginning of the next frame).» TDD : the AST value is either the ATDD split or the ATDD split + T f. The allocation shall be within a single frame. WirelessMAN-SCa PHY & WirelessMAN-OFDMA PHY Allocation Start Time shall be subject to the following limitations:» Minimum value: Allocation Start Time T f» Maximum value: Allocation Start Time < 2 T f TKU HSNL WMAN - 100

101 Optional MAC AAS Support Adaptive Antenna System (AAS) - optional the use of more than one antenna element, can improve range and system capacity by adapting the antenna pattern and concentrating its radiation to each individual subscriber. Support in WirelessMAN-SCa, OFDM, and OFDMA spectral efficiency can be increased linearly with the number of antenna elements achieved by steering beams to multiple users simultaneously so as to realize an inter-cell frequency reuse. signal-to-noise ratio (SNR) gain realized by coherently combining multiple signals, and the ability to direct this gain to particular users. MIMO/SIMO/MISO. TKU HSNL WMAN - 101

102 Optional MAC AAS Support provides a mechanism to migrate from a non-aas system to an AAS enabled system dedicating part of the frame to non-aas traffic and part to AAS traffic time TKU HSNL WMAN - 102

103 Optional MAC AAS Support Alerting the BS about presence of a new SS in an AAS system AAS BS may reserve a fixed, pre-defined part of the frame as initial-ranging contention slots (called AAS-alert-slots) for this alert procedure FDD/TDD support use channel state information of both downlink and uplink Two ways :» (reciprocity) using the uplink channel state estimation as the downlink channel state (TDD)» (feedback) transmitting the estimated channel state from the SS to BS. (FDD or TDD) using two MAC control messages:» AAS-FBCK-REQ and AAS-FBCK-RSP» The BS shall provide an uplink allocation to enable the SS to transmit this response.» Using FDD, the BS shall issue AAS-FBCK-REQ messages.» Using TDD, the BS may issue AAS-FBCK messages. (pp. 165) TKU HSNL WMAN - 103

104 Burst FDD Framing Allows scheduling flexibility TKU HSNL WMAN - 104

105 Uplink TDD/FDD Subframe (ranging) (band. req) UIUC: Uplink Interval Usage Code TKU HSNL WMAN - 105

106 TDD Downlink Subframe DIUC: Downlink Interval Usage Code TKU HSNL WMAN - 106

107 FDD Downlink Subframe TDMA portion: transmits data to some half-duplex SSs (the ones scheduled to transmit earlier in the frame than they receive) Need preamble to re-sync (carrier phase) TKU HSNL WMAN - 107

108 Receive/transmit Transition Gap (RTG) in TDD A gap between the uplink burst and the subsequent downlink burst in a TDD transceiver. Not applicable for FDD systems transmit/receive transition gap (TTG) : similar TKU HSNL WMAN - 108

109 Adaptive PHY Adaptive modulation TKU HSNL WMAN - 109

110 Nine Data Rates in Modulation Schemes : QPSK, 16-QAM and 64-QAM 20 MHz/channel (4M PSs/frame/ms = 16Msymols/ms) 32Mbps / 64Mbps / 96Mbps 25 MHz/channel (5M PSs/frame/ms = 20Msymbols/ms) 40Mbps / 80Mbps / 120Mbps 28 MHz/channel (5.6M PSs/frame/ms = 22.4Msymbols/ms) 44.8Mbps / 89.6Mbps / 134.4Mbps Uplink mandatory US European downlink mandatory 0.5, 1 or 2 ms TKU HSNL WMAN - 110

111 10-66 GHz PHY parameters TKU HSNL WMAN - 111

112 Uplink PHY TKU HSNL WMAN - 112

113 Downlink PHY TKU HSNL WMAN - 113

114 Shortened FEC blocks TDMA/TDM case Reed-Solomon over Galois field GF(256) TDMA w/ TDM w/o TKU HSNL WMAN - 114

115 IEEE a Medium Access Control Modifications and Additional Physical Layer Specifications for 2-11 GHz TKU HSNL WMAN - 115

116 802.16a PHY Alternatives Different Applications, Bandplans, and Regulatory OFDM (WirelessMAN( WirelessMAN-OFDM Air Interface) 256-point FFT with OFDM (TDD/FDD) OFDMA (WirelessMAN( WirelessMAN-OFDMA Air Interface) 2048-point FFT with OFDMA (TDD/FDD) CDMA ranging code Single-Carrier (WirelessMAN( WirelessMAN-SCa Air Interface) TDMA (TDD/FDD) BPSK, QPSK, 4-QAM, 16-QAM, 64-QAM Most vendors will use Frequency-Domain Equalization for solving delay spread issue TKU HSNL WMAN - 116

117 Key a MAC/PHY Features 2-11GHz License-exempt exempt band GHz OFDM/OFDMA support ARQ Space-Time Coding (STC) There are two transmit antennas on the BS side and one reception antenna on the SS side. Dynamic Frequency Selection (DFS) license-exempt Adaptive Antenna System (AAS) support Mesh Mode Optional topology for license-exempt operation only (TDD only) Subscriber-to-Subscriber communications Complex topology and messaging TKU HSNL WMAN - 117

118 Features OFDM (WirelessMAN( WirelessMAN-OFDM Air Interface) Two contention based BW request mechanisms» Bandwidth Request Header» Focused Contention Transmission with Contention Code over Contention Channel consisting of 4 carriers OFDMA (WirelessMAN( WirelessMAN-OFDMA Air Interface) Two contention based BW request mechanisms» Bandwidth Request Header» Specifies a Ranging Subchannel and a subset of Ranging Codes that are used for contention-based BW requests (CDMA mechanism) The WirelessHUMAN system provides optional support for Mesh topology. Unlike the point-2-multipoint (PMP) mode, there are no clearly separate downlink and uplink subframes in the Mesh mode. TKU HSNL WMAN - 118

119 Mesh-based WirelessMAN Source: Nokia Networks TKU HSNL WMAN - 119

120 Mesh Networks Mesh systems typically use omnidirectional or 360 steerable antennas, but can also be co-located using sector antennas. Directed Mesh (DM) : The realization of a physical mesh using substantially directional antennas. Nodes : systems in Mesh networks Mesh BS : a system that has a direct connection to backhaul services outside the Mesh network. Mesh SS : all the other systems of a Mesh network Neighbor : The nodes with which a node has direct links Neighborhood :Neighbors of a node form a neighborhood (onehop) Extended neighborhood : all the neighbors of the neighborhood (two-hops) TKU HSNL WMAN - 120

121 Mesh Networks Using distributed scheduling, all the nodes including the Mesh BS shall coordinate their transmissions in their two-hop neighborhood and shall broadcast their schedules (available resources, requests and grants) to all their neighbors. (Optionally) the schedule may also be established by directed uncoordinated requests and grants between two nodes. Nodes shall ensure that the transmissions do not collide with the traffic scheduled by any other node in two-hop neighborhood. TKU HSNL WMAN - 121

122 Mesh Networks Using centralized scheduling, the Mesh BS shall gather resource requests from all the Mesh SSs within a certain hop range. determine the amount of granted resources for each link the grant messages do not contain the actual schedule, but each node shall compute it by using the predetermined algorithm with given parameters. QoS is provisioned over links on a message-bymessage basis. TKU HSNL WMAN - 122

123 Mesh Networks 48-bit universal MAC address When authorized to the network the node receives a 16-bit node identifier (Node ID) upon a request to the Mesh BS Node ID is transferred in the Mesh subheader, which follows the generic MAC header, in both unicast and broadcast messages. For addressing nodes in the local neighborhood, 8-bit link identifiers (Link IDs) shall be used. The Link ID is transmitted as part of the CID in the generic MAC header in unicast messages. The Link IDs shall be used in distributed scheduling to identify resource requests and grants. Since these messages are broadcast, the receiver nodes can determine the schedule using the transmitter s Node ID in the Mesh subheader, and the Link ID in the payload of the MSH- DSCH (Mesh Mode Schedule with Distributed Scheduling) message. TKU HSNL WMAN - 123

124 Mesh Networks 8 bits Messages with larger Drop Precedence shall have higher dropping likelihood during congestion. TKU HSNL WMAN - 124

125 IEEE and 16a Mesh topology * Mesh topology * 5-6GHz 5MHz/channel ; 200 channels HUMAN : High-Speed Unlicensed Metropolitan Area Network TKU HSNL WMAN - 125

126 OFDM/OFDMA raw bitrates (Mbps) TKU HSNL WMAN - 126

127 Adaptive Antenna System A system adaptively exploiting more than one antenna to improve the coverage and the system capacity Adapt the antenna pattern and concentrating its radiation to each individual subscriber The spectral efficiency can be increased linearly with the number of antenna elements steering beams to multiple users simultaneously so as to realize an inter-cell frequency reuse Reduce interference TKU HSNL WMAN - 127

128 THANK YOU! Questions? TKU HSNL WMAN - 128