W.wan.6-2 Wireless WAN Case Study: WiMAX/802.16 W.wan.6 WiMAX/802.16 IEEE 802 suite WiMAX/802.16 PHY Dr.M.Y.Wu@CSE Shanghai Jiaotong University Shanghai, China Dr.W.Shu@ECE University of New Mexico Albuquerque, NM, USA MAC 802.16e Past & future 802.16 vs 802.11 WiMAX vs 3G End W.wan.6-3 W.wan.6-4 IEEE 802 suite IEEE802 suite IEEE 802 --- PAN/LAN/MAN Standards Wired 802.3 (Ethernet) Wireless 802.11: Wireless LAN WiFi 802.15: Wireless PAN Bluetooth 802.16: Wireless MAN WiMAX 802.20: Vehicular Mobility? MobilFi Standard downloads (free 6 months after publication) http://standards.ieee.org/getieee802 IEEE 802 --- PAN/LAN/MAN Standards
W.wan.6-5 W.wan.6-6 WiMAX = WLL + IEEE Standardization Use point-to-multipoint architecture with stationary rooftop or tower-mounted antennas Worldwide interoperability for Microwave Access WiMAX Standard: IEEE 802.16 Frequency spectrum around 30 GHz, LMDS, LOS, licensed around 3 GHz, MMDS,, licensed Last-mile technology: metropolitan area in scale Can serve as backhaul for wireless LANs (802.11) 802.16 10 66 GHz LOS Sep 2000 WiMAX = interoperable subset of this (< 6 GHz) 802.16a 2 11 GHz Jan 2003 802.16d Similar to.16a Jul 2004 802.16e Some Mobility Feb 2006 802.16 2004 2 66 GHz LOS/ Jul 2004 W.wan.6-7 W.wan.6-8 Completed 802.16 December 2001 WiMAX 802.16a/d 802.16e June 2004 (16d) February 2006 Spectrum 10-66 GHz < 11 GHz < 6 GHz Channel Conditions LOS Bit Rate 32 134 Mbps in 28MHz Up to 75 Mbps in 20MHz Up to 15 Mbps in 5MHz Modulation QPSK, 16QAM and 64QAM OFDM 256 FFT QPSK, 16QAM, 64QAM Scalable OFDMA 128 to 2048 FFT Mobility Fixed Fixed Portable Channel Bandwidth 20, 25 and 28 MHz 1.25 to 20 MHz 1.25 to 20 MHz Cell size 2-5 km 5-8 km, max 50km based on tower, antenna, tran power 2-5 km
W.wan.6-9 W.wan.6-10 Air Interface (PHYs with common MAC) 802.16: 10-66 GHz, 2002 802.16a: 2-11 GHz, 2003 Specification Including the MAC layer and PHY layer, of fixed pointto-multipoint broadband wireless access systems providing multiple services. The MAC layer is capable of supporting multiple PHY layer specifications optimized for the frequency bands of the application. The standard includes a particular PHY layer specification broadly applicable to systems operating between 10 and 66 GHz. Multipath signal ( problem, not in LOS) The composition of a primary signal plus duplicate or echoed images caused by reflections of signals off objects between the transmitter and the receiver The echoed signal is delayed in time and reduced in power, and it causes ISI (inter-symbol interface) Solution? (to overcoming multipath signals) Adaptive modulation FEC (Forward Error Correction) Spread Spectrum, OFDM Advanced antenna system Power control W.wan.6-11 W.wan.6-12 Adaptive modulation The further the subscriber is from the base station, the greater the likelihood of a lower form of modulation and a higher amount of coding and thus a lower bit-rate WiMAX raw bandwidth (Mbps), in theory Modulation code rate 1.75 MHz QPSK 1/2 1.45 QPSK 3/4 2.18 16 QAM 1/2 2.91 16 QAM 3/4 4.36 64 QAM 2/3 5.82 64 QAM 3/4 6.55 3.5 MHz 2.91 4.36 5.82 8.73 11.64 13.09 Modulation BPSK QPSK SNR 6dB 9dB 7.0 MHz 14.0 MHz 20.0 MHz 5.82 11.64 16.26 8.73 17.45 24.40 11.64 23.27 32.53 17.45 34.91 48.79 23.27 46.55 65.05 26.18 52.36 73.19 16 QAM 16dB 64 QAM 22dB
W.wan.6-13 W.wan.6-14 WiMAX coverage (Km), in theory Type of area Rural Rooftop antenna <20 km, * Window/fixed antenna <8 km Indoor/portable antenna < 4km OFDM = Orthogonal FDM A technique to increase transmission speed by multiplexing Uses one wide frequency channel by breaking it up into several sub-channels ORTHOGONALITY overlapping but distinguishable Suburban N/A <4 km <2 km Urban N/A <2 km <1 km * <50 Km is the theoretical maximum for LOS. Assumption is a base station and a rooftop antenna for better reception and maximum uplink power W.wan.6-15 W.wan.6-16 MAC PMP (Point-to-Multipoint), Connection oriented Support multiple 802.16 PHYs Dynamic TDMA-based MAC with on-demand bandwidth allocation. (low cost: SS doesn t Tx/Rx simultaneously) FDD Downlink & uplink on separate RF channels Unframed FDD for full-duplex SS Framed FDD, downlink in bursts Static asymmetry TDD Downlink & uplink time share the same RF channel Dynamic asymmetry WiMAX/802.16 MAC Uplink Uses a DAMA-TDMA technique Error correction uses Reed-Solomon code Modulation scheme based on QPSK Downlink Continuous downstream mode for A/V Simple TDM scheme is used for channel access Duplexing technique is frequency division duplex (FDD) Burst downstream mode for IP traffic DAMA-TDMA scheme is used for channel access Duplexing techniques are FDD with adaptive modulation, frequency shift division duplexing (FSDD), time division duplexing (TDD)
W.wan.6-17 W.wan.6-18 Technology considerations Licensed vs unlicensed LOS vs Half-duplex vs full-duplex P2P, PMP, Mesh Fixed, portable, mobile Cost performance throughput = channel bandwidth (Hz) X bits/hz Last-mile tech? T1 replacement WiFi backhaul 3G/4G? WiMAX/802.16e Fixed Portable IEEE 802.16-2004 standard is designed for fixed-access usage It uses a mounted antenna at the subscriber s site. Fixed model is an alternative to cable modem, DSL, 802.16e Targets the mobile market by adding portability. Mobile clients with IEEE 802.16e adapters can connect directly to the WiMAX network. 802.16e uses Orthogonal Frequency Division Multiple Access (OFDMA) W.wan.6-19 W.wan.6-20 WiMAX/802.16e Mobility in 802.16e: PHY Layer Sleep mode, paging enabled. Fast time alignment (ranging) mechanism Flexible FFT sizes depending on channel bandwidth to ensure OFDM symbol duration is compatible with mobility requirements Soft handover, i.e., transmit/receive from multiple BS Fast channel feedback Fast BSS handover involving maintenance of sync to multiple BS while transmitting/receiving from anchor BS New MIMO, STC modes MIMO soft-handoff based macro-diversity transmission Space-time codes for 3 antenna configurations. Fixed version has 2 and 4 antenna modes. WiMAX/802.16e Mobility in 802.16e: MAC Layer Handover (HO) process defined in MAC including cell reselection target BS scanning network re-entry HO decision and initiation and HO cancellation. Newly defined: MAC messages for each of the handover functions Broadcast paging message Neighbor topology advertisement messages Option of using mobile IP provided Full QoS supported. All four GSM/WCDMA classes.
W.wan.6-21 W.wan.6-22 WiMax past & future WiMax past & future Evolution of 802.16 Originally was for bands above 10 GHZ Corporate access, and back haul only, but no mass market 802.16a revision was added for bands below 10 GHZ and The current revision is 802.16 2004 which combines prior revisions into one 50Mbps 802.16 WiMAX Bandwidth vs mobility 802.16e will extend the standard to cover mobile applications Estimate equipment availability and cost 1 st generation: Fixed outdoor antenna/radio, 2005,~$350 2 nd generation: Indoor directional antenna/radio, 2006,~$250 3 rd generation: Integrated system in laptops, 2007 ~$100 20Mbps 10Mbps 802.11 802.16e Incoming 802.16g/i --- Network Management 802.16j --- Multihop relay specification 1Mbps 802.20 3G 802.16k --- MAC layer bridging fixed nomadic mobile W.wan.6-23 W.wan.6-24 Tropos Networks: Integration of 802.16 & 820.11 WiMAX/802.16 2-11 GHz Licensed, unlicensed Technology Spectrum WiFi/802.11b/g 2.4 GHz unlicensed WiMAX as backhaul < 50 km (typical 5km) Range < 200m Outdoor LOS & Coverage Indoor short range 5bps/Hz peak < 100Mbps in 20 MHz Data rate 2.7bps/Hz peak < 54Mbps in 20MHz Hundreds CPE Scalability Tens CPE On demand: A/V,data QoS No Connection oriented Connection type Connectionless TDD/FDD Full duplex No TDMA Multiple access CSMA/CA
W.wan.6-25 W.wan.6-26 Tropos Networks: Integration of 802.16 & 820.11 WiMAX as transport within the mesh Tropos Networks: Integration of 802.16 & 820.11 WiMAX as client connection W.wan.6-27 W.wan.6-28 WiMAX/802.16 vs 3G WiMAX in China WiMAX/802.16 Wireless broadband Technology Broadband 3G Mobile broadband BWA/802.16 in China BWA = Broadband Wireless Access 广带无线接入标准 Laptop centric Client Phones & laptops Fixed to portable mobility Roaming / mobility LOS or Channels Optimized for data Services Optimized for voice WiMAX potential 4G???