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IEEE 802.16 MAC and PHY Specifications for Broadband WMAN

IEEE 802.16 MAC and PHY Specifications for Broadband WMAN. 長庚大學資工系 陳仁暉 Tel : (03) 211-8800 ext. 5990 E-mail: jhchen@mail.cgu.edu.tw. Resources.

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IEEE 802.16 MAC and PHY Specifications for Broadband WMAN

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  1. IEEE 802.16MAC and PHY Specifications for Broadband WMAN 長庚大學資工系 陳仁暉 Tel : (03) 211-8800 ext. 5990 E-mail: jhchen@mail.cgu.edu.tw

  2. Resources Part Source : Roger B. Marks, National Institute of Standards and Technology Boulder, Colorado, USA Chair, IEEE 802.16 Working Group http://WirelessMAN.org

  3. Broadband Access to Buildings • Metro Ethernet • 802.11 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

  4. Wireless Metropolitan Area Network

  5. Application

  6. Features (1/2) • Broad bandwidth • Up to 134.4 Mbit/s in 28 MHz channel (in 10-66 GHz) (UWB ?) • 32Mb/s - 134.4Mb/s • 20/25/28MHz per channel • line of sight is requiredandmultipath 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.

  7. Features (2/2) • Supports multiple frequency allocations from 2-66 GHz in 802.16 (10-66GHz) and 802.16a (2-11GHz) • Single carrier (SC) for line-of-sight situations • OFDM and OFDMA for non-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 802.16a) • Extensions to mobility. (IEEE 802.16e started from Jan. 2003)()tensions to mobility are coming next.

  8. IEEE 802.16 Standard and amendments • Fixed Broadband Wireless Access (FBWA) Systems • Air Interface (MAC and PHY) • Band 10-66GHz (ranges 1/2/3 : 10-23.5GHz/23.5-43.5GHz/43.5-66GHz) 25/28MHz per channel • line-of-sight (LOS) requirement • One PHY • WirelessMAN-SC(Single Carrier) • Point-to-Multipoint Topology (Star) • TDD/FDD with burst profile option (depending on SNR) • Completed in October 2001 • Published in April 2002 • Followup interoperability projects • 802.16c (Profiles): published in Jan 2003 • 802.16.1 (PICS): in ballot; completion expected Mar 2003 • PICS : Protocol Implementation Conformance Statement • 802.16.2 (“10-66GHz Coexistence of FBWA Systems”) • Focus on 23.5 to 43.5 GHz (local multipoint distribution service (LMDS), millimeter wave, etc.,) • WiMAXsubmitted proposal in Jan 2003

  9. IEEE 802.16a Standard • “Medium Access Control Modifications and Additional Physical Layer Specifications for 2–11 GHz” • Band2-11GHz • Non-line-of-sight (NLOS) requirement and Multi-path issue • Near-LOS • License-exempt band 5-6 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 ApprovedApril 2003 • IEEE 802.16e (mobility) first meeting in 2004 D5 • IEEE 802.16.2a (coexistence including 2-11GHz)

  10. IEEE 802.16a Standard • license-exempt bands below 11 GHz • The PHY and MAC introduce mechanisms such as dynamic frequency selection (DFS) to detect and avoid interference.

  11. IEEE 802.16-2004 Standard • IEEE Std 802.16™-2004 • “Air Interface for Fixed Broadband Wireless Access Systems” - IEEE 802.16d • Approved 24 June 2004 • This standard revises and consolidates IEEE Std 802.16-2001, IEEE Std 802.16a™-2003, and IEEE Std 802.16c™-2002. • IEEE Std 802.16f • MIB (Management Information Base) • IEEE Std 802.16g • System/resource/handover Management • Interoperability

  12. IEEE 802.16e • Enhance IEEE 802.16-2004 • PHY is similar to 802.16-2004 • Focus on 2-6GHz • 1.75-20MHZ per channel • Enhance OFDMA PHY • Supports 2048-point, 1024-point, 512-point and 128-point FFT • Data rate • 10Mhz/channel, OFDM-64QAM provides 30Mbps • Max. moving speed : 120km/h • Range : several Kms • Chip appears in 2006 • vs. IEEE 802.20 • Below 3.5GHz • Max. moving speed : 250Km/h (high-speed train) • vs. 3G

  13. 802.16 Air Interface

  14. WiMAX Evolution Source : Siemens, 2004

  15. WiMAX Forum • WiMAX (Worldwide Interoperability for Microwave Access) • LikeWECAin IEEE 802.11 WLAN • Mission: • To promote deployment of BWA by using a global standard and certifying interoperability of products and technologies. • Principles: • Support IEEE 802.16x • 2-66 GHz (16a : 2-11 GHz and 16 : 10-66GHz) • Propose access profiles for the IEEE 802.16 standard • Guarantee known interoperability level • Open for everyone to participate • Developing & submitting baseline test specs

  16. Point-to-Multipoint configuration • Two components • Subscriber Stations (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

  17. Mesh Topology (defined in 802.16a) • Dynamic topology • Self-organizing network • More complicated

  18. IEEE 802.16 vs. ETSI • Frequent communications between 802.16 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 • 802.16 has encouraged harmonization • ETSI HIPERMAN • Below 11 GHz (outdoor) • IEEE began first • Healthy cooperation • Harmonized with 802.16a OFDM HIPERMAN • ETSI HIPERLAN • 5GHz (indoor/outdoor) • 6-54Mb/s • Irrelative with 802.16 • ETSI HIPERLINK • 17GHz (150m, point-2-point) • 155Mb/s (OC3) • Irrelative with 802.16

  19. IEEE 802.16 Working Group

  20. MAC Overview • Connection-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 802.16 PHYs

  21. Protocol Stack packet ATM SSCS Packet convergence Sublayer (PCS) (security sublayer 16-2004)

  22. 802.16 MAC Reference Model • Convergence Sublayer (CS) • Mapping external network data into MAC SDU • Classifying external network SDU • Associating to MAC connection ID • Payload header suppression • Common Part Sublayer (CPS) • Core MAC functionality • System access • Bandwidth allocation • Connection establishment • Connection maintenance • Security Sublayer • Authentication • Security key exchange • Encryption • PHY • Multiple sections • Each appropriate to a frequency range and application

  23. 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.

  24. 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)

  25. 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. QoS Parameters (used in scheduler) SFID/QoS mapper SFID CID/SFID PHSI mapper CID Packet Classifier(s) PHS ruler SFID/PHSI (sender) CID/PHSI (receiver)

  26. 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)

  27. Security Sublayer • The security sublayer providing • authentication, • secure key exchange, and • Encryption • Two component protocols • Encapsulation protocol • Cryptographic suites • Key management protocol (PKM) • Create and exchange traffic encryption key (TEK)

  28. 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) PHS PHS Conn. ID (CID) CID+PHSI

  29. Classifications service flow ID (SFID) PHS Conn. ID (CID)

  30. Classifications • A MAC SDU is mappedonto 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

  31. Payload Header Suppression (PHS) • For some payload protocols, each payload consists of an 8-bitpayload 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. 8-bit MAC header PHSI refer the payload header suppression field (PHSF)

  32. 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.

  33. PHS operation

  34. 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 asIP 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

  35. PHS with masking A,C,E are compressed Only sends B and E

  36. 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

  37. PHS Signaling • PHS requires the creation of the following three objects: • Dynamic Service Flow (DSA/DSC/DSD) • Addition/Change/Deletion b) Classifier c) PHS rule (PHSI is assigned by BS since BS has many SSs)

  38. 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 • CIDmaps to a service flow identifier (SFID), which defines the Quality of Service (QoS)parameters of the service flow associated with that connection. • Security associations (SAs) also exist between keying material and CIDs.

  39. Connection ID (CID) • Connections are identified by a 16-bit CID • At SS initialization, three management connectionsin 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.

  40. 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-layersessions may operate over the same wireless CID.

  41. Connection ID (CID)

  42. MAC Protocol

  43. 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)

  44. MAC overview • Service flows provide a mechanism for uplink and downlink QoS management. • In particular, they areintegral 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.

  45. OFDM Frame Structure with TDD DLFP: Downlink Frame Prefix FCH: Frame Control Header TTG: Transmission Transition Gap RTG: Receive Transition Gap

  46. OFDM frame structure with FDD (download)

  47. OFDM frame structure with FDD (upload)

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

  49. Generic MAC Header

  50. Type encodings (in Generic Header) Type bits Bit mapping

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