WiMAX

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WiMAX

  1. 1. WiMAX Protocol CSCE 4520/5520 Fall 2006 Shori Fukatsu
  2. 2. Contents List <ul><li>WiMAX Protocol </li></ul><ul><ul><li>About WiMAX </li></ul></ul><ul><ul><li>Physical layer </li></ul></ul><ul><ul><li>MAC layer </li></ul></ul><ul><li>Fixed / Mobile WiMAX </li></ul><ul><li>WiMAX vs Wi-Fi </li></ul><ul><li>WiMAX applications </li></ul><ul><li>Reference </li></ul><ul><li>Quiz </li></ul>
  3. 3. WiMAX <ul><li>W orldwide I nteroperability for M icrowave Acc ess </li></ul><ul><li>“ a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL” </li></ul><ul><li>Metropolitan Area Network (MAN) </li></ul><ul><li>Based on IEEE 802.16 </li></ul>
  4. 4. Purpose of WiMAX <ul><li>To provide point-to-multipoint wireless access to Internet and other networks </li></ul><ul><li>To provide high data rates over 10-40km </li></ul>
  5. 6. WiMAX Architecture MIB – Management Information Base
  6. 7. 802.16 protocol
  7. 8. 802.16 protocol stack <ul><li>802.16 covers data link and physical layer </li></ul>
  8. 9. IEEE 802.16 Standards <ul><li>802.16.1 (10-66 GHz, line-of-sight, up to 134Mbit/s) </li></ul><ul><li>802.16.2 (minimizing interference between coexisting WMANs.) </li></ul><ul><li>802.16a (2-11 Ghz, Mesh, non-line-of-sight) </li></ul><ul><li>802.16b (5-6 Ghz) </li></ul><ul><li>802.16c (detailed system profiles) </li></ul><ul><li>802.16e (Mobile Wireless MAN) – called MobileWiMAX </li></ul>
  9. 11. Physical layer (PHY)
  10. 12. PHY cont. <ul><li>QPSK : 2 bits/baud (< 10km) </li></ul><ul><li>QAM-16 : 4 bits/baud (6-10km) </li></ul><ul><li>QAM-64 : 6 bits/baud (>6km) </li></ul><ul><li>Example: a 25 MHz bandwidth, QPSK can deliver 50 Mbps, QAM-16 100 Mbps, QAM-64 150 Mbps </li></ul><ul><li>Baud (Bd): measure of the symbol rate; the number of distinct symbolic changes (signalling event) made to the transmission medium per second in a digitally modulated signal </li></ul><ul><li>25 Bd means that 25 symbols are transmitted per second. </li></ul>
  11. 13. PHY cont. <ul><li>TDD (time-division duplex) </li></ul><ul><li>- use same bandwidth for uplink and downlink </li></ul><ul><li>- controlled by timing </li></ul><ul><li>FDD (frequency-division duplex) </li></ul><ul><li>- use different frequency for uplink and downlink </li></ul><ul><li>OFDM (orthogonal frequency-division multiplexing) </li></ul><ul><li>- enhancement of frequency division multiplexing (FDM) </li></ul><ul><li>- maximize use of bandwidth </li></ul>
  12. 14. TDD and FDD
  13. 15. OFDM FDM OFDM OFDM uses bandwidth which is not available for use in FDM
  14. 16. MAC layer <ul><li>Protocol-Independent core (IP, ATM, etc) </li></ul><ul><li>Support multiple 802.16 PHYs </li></ul>
  15. 17. MAC cont. <ul><li>Each MAC packet contains three components </li></ul><ul><li>MAC header; contains frame control information </li></ul><ul><li>variable length f rame body; contains information specific to the frame type </li></ul><ul><li>frame check sequence (FCS); contains an IEEE 32-bit cyclic redundancy code (CRC). </li></ul>
  16. 18. MAC cont. <ul><li>Generic Uplink/Downlink header </li></ul>
  17. 19. Downlink Header
  18. 20. Downlink Header <ul><li>Encryption Control (EC): Indicates whether the payload is encrypted </li></ul><ul><li>Encryption Key Sequence (EKS): An index into a vector of encryption key information </li></ul><ul><li>Length : Length in bytes of the entire MAC frame </li></ul><ul><li>Connection Identifier : A unidirectional, MAClayer address that identifies a connection to equivalent peers </li></ul><ul><li>Header Type : Indicates whether this is a generic or bandwidth request header </li></ul><ul><li>ARQ Indicator : Indicates whether the frame belongs to an ARQ enabled connection </li></ul><ul><li>Fragment Control : Used in fragmentation and reassembly </li></ul><ul><li>Fragment Sequence Number : Sequence number of the current fragment </li></ul><ul><li>Header Check Sequence : 8-bit CRC to detect errors in the header </li></ul>
  19. 21. Uplink Header
  20. 22. Uplink Header <ul><li>Slip indicator : indicate a slip of uplink grants relative to the uplink queue depth </li></ul><ul><li>Poll-me : request a poll by the base station </li></ul><ul><li>Grants per interval : the number of bandwidth grants required in the next time interval </li></ul><ul><li>Piggyback request : the number of bytes of uplink capacity requested </li></ul>
  21. 23. Bandwidth request and allocation <ul><li>SSs may request bandwidth in 3 ways: </li></ul><ul><ul><ul><ul><li>Use the ”contention request opportunities” interval upon being polled by the BS (multicast or broadcast poll). </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Send a standalone MAC message called ”BW request” in an allready granted slot. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Piggyback a BW request message on a data packet. </li></ul></ul></ul></ul>
  22. 24. Bandwidth request and allocation cont. <ul><li>BS grants/allocates bandwidth in one of two modes: </li></ul><ul><ul><ul><li>Grant Per Subscriber Station (GPSS) </li></ul></ul></ul><ul><ul><ul><li>Grant Per Connection (GPC) </li></ul></ul></ul><ul><li>Decision based on requested bandwidth and QoS requirements vs available resources. </li></ul><ul><li>Grants are realized through the UL-MAP (Uplink message). </li></ul>
  23. 25. Bandwidth request and allocation cont.
  24. 26. Fixed and Mobile WiMAX <ul><li>Fixed WiMAX is optimized for home/office networks </li></ul><ul><li>Mobile WiMAX is optimized for mobiles </li></ul>
  25. 27. Fixed WiMAX <ul><li>IEEE 802.16d </li></ul><ul><li>T1/E1 substitute </li></ul><ul><li>1BS – thousands of user </li></ul><ul><li>< 50km coverage </li></ul><ul><li>< 75Mbps </li></ul>
  26. 28. Fixed WiMAX Architecture
  27. 29. Mobile WiMAX <ul><li>IEEE 802.16e </li></ul><ul><li>2-3km coverage (optimal) </li></ul><ul><li>High speed hand over </li></ul><ul><li>(< 50ms latencies) </li></ul><ul><li>Ensures performance at vehicular speeds greater than 120km/h </li></ul><ul><li>< 30Mbps for downlink </li></ul><ul><li>< 15Mbps for uplink </li></ul>
  28. 30. WiMAX vs Wi-Fi
  29. 31. WiMAX vs Wi-Fi cont. WiMAX is designed to cover large area (multiple homes/buildings), while Wi-Fi is to cover small area (a home/building)
  30. 32. Comparison of WiMAX, WiFi and 3G technology
  31. 33. WiMAX vs Wi-Fi cont.
  32. 34. WiMAX applications <ul><li>Broadband Internet </li></ul><ul><li>Multimedia </li></ul><ul><li>IP multimedia subsystem (IMS) </li></ul><ul><li>Cellular Alternative </li></ul>
  33. 35. Broadband Internet <ul><li>Fixed WiMAX is substitute for T1 </li></ul><ul><li>Mobile WiMAX has larger coverage than WiFi </li></ul>
  34. 36. Multimedia <ul><li>Mobile TV </li></ul><ul><li>IPTV (TV broadcasting via IP network) </li></ul>
  35. 37. Traditional networks <ul><li>Different device, different network </li></ul><ul><li>For example: </li></ul><ul><li>TV is only for watching TV </li></ul><ul><li>Phone is only for call </li></ul>
  36. 38. IMS network <ul><li>One network provides multiple things </li></ul><ul><li>For example: </li></ul><ul><li>Watch TV and use Internet via cell phone </li></ul>
  37. 39. WiMAX as cellular alternative <ul><li>Support IP by default </li></ul><ul><li>VoIP </li></ul>
  38. 41. Reference <ul><li>Frank Ohrtman: “Wimax overview”: http:// www.wimax.com/education/wimax/wimax_overview </li></ul><ul><li>“ The 802.16 WirelessMAN™ MAC: It’s Done, but What Is It?” (2001-11-12) </li></ul><ul><li>Zheng Yu Huang (2006-10-25):”Considerations for Next Generation Telecommunications Deployments in China”, Intel Corporation </li></ul><ul><li>Michael Richardson and Patrick Ryan (2006-3-19): “WiMAX: Opportunity or Hype?” </li></ul><ul><li>“ Adaptive Modulation” (2004), Intel Corporation </li></ul><ul><li>Tim Sanders (2005-9-21): ”WiMax/802.16 Revealed”, http://www.wi-fiplanet.com/tutorials/article.php/3550476 </li></ul><ul><li>Michael F. Finneran (2004-6-1) “WiMAX versus Wi-Fi”, dBrn Associates, Inc. </li></ul>
  39. 42. <ul><li>Israel Koffman and Vincentzio Roman (2002): “Broadband Wireless Access Solutions Based on OFDM Access in IEEE 802.16”, IEEE Communications Magazine April 2002 </li></ul><ul><li>WiMAX Forum (2006-8): “Mobile WiMAX – Part I: A Technical Overview and Performance Evaluation” </li></ul><ul><li>dailywireless.org (2005-7-8): “Mobile WiMAX Chips”, http://www.dailywireless.org/2005/07/08/mobile-wimax-chips/ </li></ul><ul><li>Carl Eklund, Roger B. Marks, Kenneth L. Stanwood and Stanley Wang (2002-6): “IEEE Standard 802.16: A Technical Overview of the WirelessMAN™ Air Interface for Broadband Wireless Access”, IEEE Communications Magazine June 2002 </li></ul><ul><li>Robert Healey (2003):“Network Architecture for WiMAX applications”, Juniper Networks, Inc. </li></ul><ul><li>Kuo-Hui Li (2006-6-5): “WiMAX Network Architecture”, Intel Mobility Group </li></ul><ul><li>“ Technology Primer WiMAX”, http:// www.tektronix.com/wimax </li></ul>
  40. 43. Quiz <ul><li>How much bps can QPSK (2bits/Bd), QAM-16 (4bits/Bd) and QAM-64 (6bits/Bd) can deliver if a bandwidth is 20MHz? </li></ul><ul><li>What is the difference between OFDM and FDM? </li></ul><ul><li>What are the differences between WiMAX and Wi-Fi? </li></ul>
  41. 44. Answer <ul><li>QPSK - 40Mbps, QAM-16 - 80Mbps, QAM-64 -120Mbps (slide #11) </li></ul><ul><li>See slide #14 </li></ul><ul><li>The main difference is that WiMAX is focused on MAN, while Wi-Fi is LAN technology. (slide #30-33) </li></ul>

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