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IEEE 802.20 – Mobile Broadband Wireless Access

IEEE 802.20 – Mobile Broadband Wireless Access. Abstract.

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IEEE 802.20 – Mobile Broadband Wireless Access

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  1. IEEE 802.20 – Mobile Broadband Wireless Access

  2. Abstract Mobile Broadband Wireless Access (802.20) is a IEEE standard formed to develop a cellular standard that focuses on vehicular mobility in a metropolitan area environment. It falls under the WWAN category. It is a packet switched technology, designed to operate in frequencies below 3.5 GHz and optimized to carry IP traffic for mobile users traveling with speeds up to 250 km/h. Standard includes Physical and MAC layer specifications and is compatible to 802 Architecture and Functional requirements

  3. IEEE 802.20 – Outline • Motivation for new Standard • Services and Applications • Physical Layer • MAC Layer • Handoff procedures • Comparison between 802.20 and 802.16e • Conclusion

  4. Motivation for new Standard – IEEE 802.20 • Wi-Max was designed to provide broadband wireless access and aims at maximizing throughput rather than mobility • 802.20 is the first standard that takes into consideration mobility classes, with speeds up to 250 km/h • Extends broadband wireless access to mobile users • Approved Dec 11th 2002, Nicknamed as Mobile-Fi • Optimized for high speed IP based wireless data service • The standard forms the basis of seamless integration of – work, home and mobile

  5. IEEE 802.20 : Services Vision of a seamless integration of three user domains: work, home and mobile. From “IEEE 802.20 System Requirement V1.0”, P802.20-PD-06r1, [1]

  6. IEEE 802.20 – Mission and Scope of Project • The goal is to enable worldwide deployment of affordable, always-on, ubiquitous mobile broadband wireless access networks. To ensure co-existence and compatibility. Scope : • To develop specification of Physical and MAC layers of the air interface • Operating in licensed bands below 3.5 GHz • Optimized for IP-data transport • Offers Peak data rates per user in excess of 1Mbps • Support vehicular mobility of 250 Km/h in a MAN environment From ”Mission and Scope”, http://ieee802.org/20/index.html

  7. IEEE 802.20 : Services • Supports video, full graphic web browsing, e-mail, file transfer, streaming video and audio. • IP Multicast • Location-Based-Servers. • VPN connections • VoIP • On-line multiplayer gaming • Broadcast and Multicast support • Needs a PC card interface with devices. From “IEEE 802.20 System Requirement V1.0”, P802.20-PD-06r1, [1]

  8. Example - Railway Application • 802.20 based Broadband Railroad Digital Network – BRDN • Meet the ever-increasing demand for M-commerce and Wi-Fi enabled trains • 802.20 was selected since it supports high speeds From “IEEE 802.20 Based Broadband Railroad Digital Network - The Infrastructure for M-Commerce on the Train ”, [10]

  9. 802.20 Features From “IEEE 802.20 System Requirement V1.0”, P802.20-PD-06r1, [1]

  10. IEEE 802.20: Network Architecture • Access Network: Collection of Access Nodes or Access Points. • AT can be in communication with more that one Access Node • Each AN-AT pairing has its own protocol stack - ROUTE • Serving Access Node: Access Point housing serving sector. • Contains sector that provides air-interface attachment for the AT • Routes can be tunneled between ANs without the serving AN needing to read the or manage the packet exchanged • Changes based on radio conditions • Anchor Access Node: Access Pointthat provides internet connectivity. • May change to minimize the number of hops a packet has to traverse to reach the AT From “UMBFDD Draft Technology Overview”, IEEE C802.20-07/09, [2]

  11. Protocol Layering – 802.20 • Application Sublayer • Radio Link Sublayer • Lower MAC Layer • Physical Layer From “FDD Technology overview presentation”, IEEE C802.20-05-59r1, [5]

  12. Physical Layer • System is deployable in 1.25 - 20 MHz flexible bandwidths • Targets cell radius of 15km • Bandwidths supports Frequency and Time Division Duplexing • Reverse links support both CDMA and OFDMA • CDMA is used for low rate data transmissions • Also supports the option of fast frequency hopping spread spectrum technology – Flash-OFDM • Forward links support OFDMA • The system uses Adaptive Coding and Modulation • Supports QPSK, 16 QAM, 8-PSK and 64 QAM • Support Hybrid ARQ • Frequency reuse - Fractional Frequency Reuse FFR From “Draft Standard for Local and Metropolitan Area Networks – Standard Air Interface for Mobile Broadband Wireless Access Systems Supporting Vehicular Mobility – Physical and Media Access Control Layer Specification”, IEEE 802.20/D3.0m, [4]

  13. Fractional Frequency reuse FFR Figure. Fractional Frequency ReuseF1, F2, and F3 are different sets of sub-channels, allocated to users at cell edges. F = F1+F2+F3. The whole sub-channels (F) are allocated to users at cell centers From “Fraction Frequency Re-use”, www.conniq.com/WiMAX/images/fractional-frequency-reuse [3]

  14. Physical Layer (Contd) • Error Detection • CRC – 24 bits for Data Channels and 9 bits for dedicated control channels • Forward Error Correction • turbo codes, convolutional codes and LDPC codes • Standard defines Physical channels - Forward and Reverse Channels • Separate channels for Control and Traffic • Channels have unique modulation, encodings and purpose • CDMA and OFDM control channels are used • CDMA Control Channels are preferred for Fast Access and Fast request • CDMA control channels provides efficient handoff control • OFDMA Control Channels are used for highly periodic control transmissions – CQI From “Draft Standard for Local and Metropolitan Area Networks – Standard Air Interface for Mobile Broadband Wireless Access Systems Supporting Vehicular Mobility – Physical and Media Access Control Layer Specification”, IEEE 802.20/D3.0m, [4]

  15. Physical Layer (contd) • Forward Channels : Forward Link Channels From “Draft Standard for Local and Metropolitan Area Networks – Standard Air Interface for Mobile Broadband Wireless Access Systems Supporting Vehicular Mobility – Physical and Media Access Control Layer Specification”, IEEE 802.20/D3.0m, [4]

  16. Physical Layer (contd) • Reverse Link Channels From “Draft Standard for Local and Metropolitan Area Networks – Standard Air Interface for Mobile Broadband Wireless Access Systems Supporting Vehicular Mobility – Physical and Media Access Control Layer Specification”, IEEE 802.20/D3.0m, [4]

  17. Physical Layer (contd) • Transmission in the FL and RL is divided into units of superframes • In FDD, each superframe consists of 25 PHY frames • In 1:1 TDD, 4 FL frames , 4 RL Frames are transmitted FDD Super frame Structure TDD Super frame Structure From “Draft Standard for Local and Metropolitan Area Networks – Standard Air Interface for Mobile Broadband Wireless Access Systems Supporting Vehicular Mobility – Physical and Media Access Control Layer Specification”, IEEE 802.20/D3.0m, [4]

  18. Physical Layer (contd) • Power control • Fast closed loop power control • Standard has mechanism for inactive mode and active mode • Supports Multi-antenna capability in both Access Nodes and Mobile Terminals

  19. Addressing • AT Addressing • UATI: Universal Access Terminal Identifier • 128 bits – temporary identity given by the system • Not hardware derived, therefore not unique. • Not used to resolve identity of AT • Shortened – 32 bits used for paging. • MACID • 11 bits long • AT assigned one MACID per sector. • Unique within the sector • Used to exchange unicast packets with AT • Does not require IP address assigned to the AT to operate • Does not use EUI-48 bits or 64 bits given to AT for during it manufacture. From “Draft Standard for Local and Metropolitan Area Networks – Standard Air Interface for Mobile Broadband Wireless Access Systems Supporting Vehicular Mobility – Physical and Media Access Control Layer Specification”, IEEE 802.20/D3.0m, [4]

  20. MAC Layer • Some Protocols used • Basic packet consolidation protocol • Provides packet consolidation on the transmit side and de-multiplexing on receive side • Protocol maintains 2 token buckets for each stream • They could be used for traffic policing and shaping • Or to hint the scheduler for transmission • Consolidated packet : consists of route packets from upper layers • Given the transmission rate, the length of packet should not increase the maximum payload size. • Along with packets received from upper layers, priority and transmission deadlines could also be included From “Draft Standard for Local and Metropolitan Area Networks – Standard Air Interface for Mobile Broadband Wireless Access Systems Supporting Vehicular Mobility – Physical and Media Access Control Layer Specification”, IEEE 802.20/D3.0m, [4]

  21. MAC Layer (contd) • Basic Access Channel MAC protocol • Describes procedures for AT and AN to transmit and receive Access Probe • Access Probe used for initial access or handoff • AN responds to Access Probe with a Access Grant • Protocol defines Ns and Np. Access Sequence From “Draft Standard for Local and Metropolitan Area Networks – Standard Air Interface for Mobile Broadband Wireless Access Systems Supporting Vehicular Mobility – Physical and Media Access Control Layer Specification”, IEEE 802.20/D3.0m, [4]

  22. MAC Layer (contd) • Basic Reverse Traffic Channel MAC Protocol • Assignments are specified by set of hop-ports and PHY frames • Hop-ports assigned for a given set of PHY frames for particular AT. • Sets of hop-ports are assigned in assignment blocks using channel tree • Transmission is multiplexed in time and frequency domain • Basic Forward Traffic Channel MAC Protocol • Defines procedures required for an AN to transmit and AT to receive • Transmission is multiplexed in time and frequency domain • Uses MACID assigned to AT ( unique in sector ) From “FDD Technology overview presentation”, IEEE C802.20-05-59r1, [5]

  23. Radio Link Protocol • Provides segmentation and reassembly • Ensures in order delivery of upper layer packets even during handoff • Increases link layer reliability through NACK transmission • QoS support – defines multiple flows QoS Implementation From “FDD Technology overview presentation”, IEEE C802.20-05-59r1, [5]

  24. QoS (contd) • RL and FL subband scheduling • Multi-user diversity gains through frequency sensitive scheduling • enables multi-user diversity gains for latency sensitive users • Design supports two hopping modes • diversity mode - global hopping across the band • subband mode-localized hopping Subband Scheduling From “FDD Technology overview presentation”, IEEE C802.20-05-59r1, [5]

  25. Handoff • Important feature of cellular mobility • Types of Handoffs • Inter-sector • Inter-Access Node • Inter-carrier • Desired Characteristics • Minimize MAC/Network layer signaling overhead • Minimize latency for handoff decisions • In Layer 1 and layer 2 handoff • In Layer 3 handoff • 802.20 proposes to use: • Mobile Controlled Handoff (MIP4) and Network Controlled Handoff • Layer 2 triggers (Low Latency MIPv4) • Make before break technique ( MIP4 MBB) From “Mobile-Controlled Handoff for MBWA”, IEEE C802.20-03/17, [6]

  26. Handoff (contd) • Mobile controlled Handoff • Consider : Inter-Sector or Inter AN : Layer 2 Handoff • Uses 2 control channels - R-CQICH and R-REQCH • For FL handoff: AT monitors R-CQICH of all sectors in active set • For RL handoff: AT uses R-REQCH to indicate the desired RL sector • Handoff completes when AT receives assignment from new sector Forward Link Handoff Reverse Link Handoff From “FDD Technology overview presentation”, IEEE C802.20-05-59r1, [5]

  27. Handoff(contd) • Layer 2 Triggers to Network Layer • During Layer 3 Handoffs ( different IP subnet) • A significant percentage of handoffs between 802.20 Access Nodes is likely to cause a cause layer 3 handoff due to high speed mobility in MA environment • IEEE 802.20, proposes to use layer 2 triggers along with Mobile IP to reduce the latency in Mobile IP ( RFC 4881) From “Support for Layer 2 Triggers for Faster Handoffs”, IEEE P802.20-03/95 [7]

  28. Handoff (contd) • Make-Before-Break • Mobile maintains PHY and MAC connectivity with more than one Access Node (BS) • Resources in new Access Node are allocated before releasing resources in the old Access Node • This helps in reducing handoff latency • Improves performance – reducing packet loss Inter-Base Tunnel Layer 3 Handoff From “Handoff procedure for MBWA”, IEEE C802.20-03/85, [6]

  29. Difference Between 802.20 and 802.16e From “MBWA and 802.16e: Two Markets –Two Projects”, [14] and “MBWA 802.20: A Comparison with Mobile WiMax“, http://ieee802.org/20/Contributions.html

  30. Future • 802.20 currently in final stages of standardization • Kyocera announces - 802.20 will begin to appear in their iBurst base stations and terminals by the 4th quarter of 2009 “Kyocera enhances iBurst with Mobile Broadband Technology”, http://global.kyocera.com/prdct/telecom/office/iburst/news/080410.html

  31. Conclusion IEEE 802.20 specifies unique solution to PHY and MAC layer of the air interface operating in the licensed spectrum below 3.4 GHz. The standard provides support to vehicular mobility in metropolitan environment and covers wide area of up to 15 km. The standard uses combination of OFDMA, CDMA, Fast Frequency Hopping spread spectrum technologies, better cell architectures, advanced digital signal processing techniques like Adaptive Antennas and better handoff techniques to achieve its goal.

  32. References [1] IEEE 802.20-PD-06r1, “IEEE 802.20 System Requirement Document (V 1.0)” [2] IEEE C802.20-07/09, “UMBFDD Draft Technology Overview” [3] “Fraction Frequency Re-use”, www.conniq.com/WiMAX/images/fractional-frequency-reuse, retrieved April 26,2008 [4] IEEE 802.20/D3.0m, “Draft Standard for Local and Metropolitan Area Networks – Standard Air Interface for Mobile Broadband Wireless Access Systems Supporting Vehicular Mobility – Physical and Media Access Control Layer Specification”, November 2007 [5] IEEE C802.20-05-59r1, “FDD Technology overview presentation” [6] IEEE C802.20-03/84, “Handoff procedure for MBWA” [7] IEEE P802.20-03/95, “Support for Layer 2 Triggers for Faster Handoffs” [8] Lawton, George. "What Lies Ahead for Cellular Technology." IEEE Computer Journal 38(6) (2005): 14-17 [9] Kuran, Mehmet S, Tuna Tugcu, and "A Survey on Emerging Broadband Wireless Access technologies." Science Direct Computer Networks 51(2007): 3013-3046 [10] Zou, Fumin, Xinhua Jiang. "IEEE 802.20 Based Broadband Railroad Digital Network - The Infrastructure for M-Commerce on the Train." The 4th International Conference on Electronic Commerce (ICEB) 2004: 771-776. [11] EEE 802.20 Working Group, System requirements for 802.20 Mobile Broadband Wireless Access Systems http://www.ieee802.org/20/Contribs/C802.20-06-04.pdf.

  33. Refernces (contd) [12] http://www.wimax.com/ [13] “Kyocera enhances iBurst with Mobile Broadband Technology”, http://global.kyocera.com/prdct/telecom/office/iburst/news/080410.html, Retrieved April 26, 2008 [14] “MBWA and 802.16e: Two Markets –Two Projects”, 802.16sgm-02/16 or 802m_ecsg-02/15

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