1. WiMAX Protocol CSCE 4520/5520 Fall 2006 Shori Fukatsu

2. 2 Contents List WiMAX Protocol About WiMAX Physical layer MAC layer Fixed / Mobile WiMAX WiMAX vs Wi-Fi WiMAX applications Reference Quiz

3. 3 WiMAX Worldwide Interoperability for Microwave Access “a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL” Metropolitan Area Network (MAN) Based on IEEE 802.16

4. 4 Purpose of WiMAX To provide point-to-multipoint wireless access to Internet and other networks To provide high data rates over 10-40km

5. 5

6. 6 WiMAX Architecture MIB – Management Information Base

7. 7 802.16 protocol

8. 8 802.16 protocol stack 802.16 covers data link and physical layer

9. 9 IEEE 802.16 Standards 802.16.1 (10-66 GHz, line-of-sight, up to 134Mbit/s) 802.16.2 (minimizing interference between coexisting WMANs.) 802.16a (2-11 Ghz, Mesh, non-line-of-sight) 802.16b (5-6 Ghz) 802.16c (detailed system profiles) 802.16e (Mobile Wireless MAN) – called MobileWiMAX

10. 10

11. 11 Physical layer (PHY)

12. 12 PHY cont. QPSK: 2 bits/baud (< 10km) QAM-16: 4 bits/baud (6-10km) QAM-64: 6 bits/baud (>6km) Example: a 25 MHz bandwidth, QPSK can deliver 50 Mbps, QAM-16 100 Mbps, QAM-64 150 Mbps 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 25 Bd means that 25 symbols are transmitted per second.

13. 13 PHY cont. TDD (time-division duplex) - use same bandwidth for uplink and downlink - controlled by timing FDD (frequency-division duplex) - use different frequency for uplink and downlink OFDM (orthogonal frequency-division multiplexing) - enhancement of frequency division multiplexing (FDM) - maximize use of bandwidth

14. 14 TDD and FDD

15. 15 OFDM FDMOFDM OFDM uses bandwidth which is not available for use in FDM

16. 16 MAC layer Protocol-Independent core (IP, ATM, etc) Support multiple 802.16 PHYs

17. 17 MAC cont. Each MAC packet contains three components 1. MAC header; contains frame control information 2. variable length frame body; contains information specific to the frame type 3. frame check sequence (FCS); contains an IEEE 32-bit cyclic redundancy code (CRC).

18. 18 MAC cont. Generic Uplink/Downlink header

19. 19 Downlink Header

20. 20 Downlink Header Encryption Control (EC): Indicates whether the payload is encrypted Encryption Key Sequence (EKS): An index into a vector of encryption key information Length: Length in bytes of the entire MAC frame Connection Identifier: A unidirectional, MAClayer address that identifies a connection to equivalent peers Header Type: Indicates whether this is a generic or bandwidth request header ARQ Indicator: Indicates whether the frame belongs to an ARQ enabled connection Fragment Control: Used in fragmentation and reassembly Fragment Sequence Number: Sequence number of the current fragment Header Check Sequence: 8-bit CRC to detect errors in the header

21. 21 Uplink Header

22. 22 Uplink Header Slip indicator: indicate a slip of uplink grants relative to the uplink queue depth Poll-me: request a poll by the base station Grants per interval: the number of bandwidth grants required in the next time interval Piggyback request: the number of bytes of uplink capacity requested

23. 23 Bandwidth request and allocation SSs may request bandwidth in 3 ways:  Use the ”contention request opportunities” interval upon being polled by the BS (multicast or broadcast poll).  Send a standalone MAC message called ”BW request” in an allready granted slot.  Piggyback a BW request message on a data packet.

24. 24 Bandwidth request and allocation cont. BS grants/allocates bandwidth in one of two modes: Grant Per Subscriber Station (GPSS) Grant Per Connection (GPC) Decision based on requested bandwidth and QoS requirements vs available resources. Grants are realized through the UL-MAP (Uplink message).

25. 25 Bandwidth request and allocation cont.

26. 26 Fixed and Mobile WiMAX Fixed WiMAX is optimized for home/office networks Mobile WiMAX is optimized for mobiles

27. 27 Fixed WiMAX IEEE 802.16d T1/E1 substitute 1BS – thousands of user < 50km coverage < 75Mbps

28. 28 Fixed WiMAX Architecture

29. 29 Mobile WiMAX IEEE 802.16e 2-3km coverage (optimal) High speed hand over (< 50ms latencies) Ensures performance at vehicular speeds greater than 120km/h < 30Mbps for downlink < 15Mbps for uplink

30. 30 WiMAX vs Wi-Fi

31. 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)

32. 32 Comparison of WiMAX, WiFi and 3G technology

33. 33 WiMAX vs Wi-Fi cont.

34. 34 WiMAX applications Broadband Internet Multimedia IP multimedia subsystem (IMS) Cellular Alternative

35. 35 Broadband Internet Fixed WiMAX is substitute for T1 Mobile WiMAX has larger coverage than WiFi

36. 36 Multimedia Mobile TV IPTV (TV broadcasting via IP network)

37. 37 Traditional networks Different device, different network For example: TV is only for watching TV Phone is only for call

38. 38 IMS network One network provides multiple things For example: Watch TV and use Internet via cell phone

39. 39 WiMAX as cellular alternative Support IP by default VoIP

40. 40

41. 41 Reference Frank Ohrtman: “Wimax overview”: http://www.wimax.com/education/wimax/wimax_overview http://www.wimax.com/education/wimax/wimax_overview “The 802.16 WirelessMAN™ MAC: It’s Done, but What Is It?” (2001- 11-12) Zheng Yu Huang (2006-10-25):”Considerations for Next Generation Telecommunications Deployments in China”, Intel Corporation Michael Richardson and Patrick Ryan (2006-3-19): “WiMAX: Opportunity or Hype?” “Adaptive Modulation” (2004), Intel Corporation Tim Sanders (2005-9-21): ”WiMax/802.16 Revealed”, http://www.wi- fiplanet.com/tutorials/article.php/3550476http://www.wi- fiplanet.com/tutorials/article.php/3550476 Michael F. Finneran (2004-6-1) “WiMAX versus Wi-Fi”, dBrn Associates, Inc.

42. 42 Israel Koffman and Vincentzio Roman (2002): “Broadband Wireless Access Solutions Based on OFDM Access in IEEE 802.16”, IEEE Communications Magazine April 2002 WiMAX Forum (2006-8): “Mobile WiMAX – Part I: A Technical Overview and Performance Evaluation” dailywireless.org (2005-7-8): “Mobile WiMAX Chips”, http://www.dailywireless.org/2005/07/08/mobile-wimax-chips/ http://www.dailywireless.org/2005/07/08/mobile-wimax-chips/ 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 Robert Healey (2003):“Network Architecture for WiMAX applications”, Juniper Networks, Inc. Kuo-Hui Li (2006-6-5): “WiMAX Network Architecture”, Intel Mobility Group “Technology Primer WiMAX”, http://www.tektronix.com/wimaxhttp://www.tektronix.com/wimax

43. 43 Quiz 1. How much bps can QPSK (2bits/Bd), QAM-16 (4bits/Bd) and QAM-64 (6bits/Bd) can deliver if a bandwidth is 20MHz? 2. What is the difference between OFDM and FDM? 3. What are the differences between WiMAX and Wi-Fi?

44. 44 Answer 1. QPSK - 40Mbps, QAM-16 - 80Mbps, QAM-64 -120Mbps (slide #11) 2. See slide #14 3. The main difference is that WiMAX is focused on MAN, while Wi-Fi is LAN technology. (slide #30-33)