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WiMAX WiMAX Presentation Transcript

  • WiMAX Protocol CSCE 4520/5520 Fall 2006 Shori Fukatsu
  • Contents List
    • WiMAX Protocol
      • About WiMAX
      • Physical layer
      • MAC layer
    • Fixed / Mobile WiMAX
    • WiMAX vs Wi-Fi
    • WiMAX applications
    • Reference
    • Quiz
  • WiMAX
    • W orldwide I nteroperability for M icrowave Acc ess
    • “ 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
    View slide
  • Purpose of WiMAX
    • To provide point-to-multipoint wireless access to Internet and other networks
    • To provide high data rates over 10-40km
    View slide
  • WiMAX Architecture MIB – Management Information Base
  • 802.16 protocol
  • 802.16 protocol stack
    • 802.16 covers data link and physical layer
  • 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
  • Physical layer (PHY)
  • 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.
  • 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
  • TDD and FDD
  • OFDM FDM OFDM OFDM uses bandwidth which is not available for use in FDM
  • MAC layer
    • Protocol-Independent core (IP, ATM, etc)
    • Support multiple 802.16 PHYs
  • MAC cont.
    • Each MAC packet contains three components
    • MAC header; contains frame control information
    • variable length f rame body; contains information specific to the frame type
    • frame check sequence (FCS); contains an IEEE 32-bit cyclic redundancy code (CRC).
  • MAC cont.
    • Generic Uplink/Downlink header
  • Downlink Header
  • 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
  • Uplink Header
  • 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
  • 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.
  • 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).
  • Bandwidth request and allocation cont.
  • Fixed and Mobile WiMAX
    • Fixed WiMAX is optimized for home/office networks
    • Mobile WiMAX is optimized for mobiles
  • Fixed WiMAX
    • IEEE 802.16d
    • T1/E1 substitute
    • 1BS – thousands of user
    • < 50km coverage
    • < 75Mbps
  • Fixed WiMAX Architecture
  • 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
  • WiMAX vs Wi-Fi
  • 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)
  • Comparison of WiMAX, WiFi and 3G technology
  • WiMAX vs Wi-Fi cont.
  • WiMAX applications
    • Broadband Internet
    • Multimedia
    • IP multimedia subsystem (IMS)
    • Cellular Alternative
  • Broadband Internet
    • Fixed WiMAX is substitute for T1
    • Mobile WiMAX has larger coverage than WiFi
  • Multimedia
    • Mobile TV
    • IPTV (TV broadcasting via IP network)
  • Traditional networks
    • Different device, different network
    • For example:
    • TV is only for watching TV
    • Phone is only for call
  • IMS network
    • One network provides multiple things
    • For example:
    • Watch TV and use Internet via cell phone
  • WiMAX as cellular alternative
    • Support IP by default
    • VoIP
  • Reference
    • Frank Ohrtman: “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/3550476
    • Michael F. Finneran (2004-6-1) “WiMAX versus Wi-Fi”, dBrn Associates, Inc.
    • 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/
    • 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/wimax
  • Quiz
    • How much bps can QPSK (2bits/Bd), QAM-16 (4bits/Bd) and QAM-64 (6bits/Bd) can deliver if a bandwidth is 20MHz?
    • What is the difference between OFDM and FDM?
    • What are the differences between WiMAX and Wi-Fi?
  • Answer
    • QPSK - 40Mbps, QAM-16 - 80Mbps, QAM-64 -120Mbps (slide #11)
    • See slide #14
    • The main difference is that WiMAX is focused on MAN, while Wi-Fi is LAN technology. (slide #30-33)