Wireless Metropolitan Area Networks WMANs Raj Jain Professor of CSE Washington University in Saint Louis Saint Louis MO 63130 Jain cse wustl edu These slides are available on line at http www cse wustl edu jain cse574 06 Washington University in St Louis CSE574s 6 1 2006 Raj Jain Overview IEEE 802 16 WiMAX LMDS MMDS IEEE 802 20 Mobile Broadband Wireless Access IEEE 802 21 Handover IEEE 802 22 Wireless Regional Area Networks Washington University in St Louis CSE574s 6 2 2006 Raj Jain Broadband Wireless Access Non Line of Sight Point to Multipoint Point to Point Backhaul MTU Telco Core Congested Areas Washington University in St Louis CSE574s 6 3 Rural Areas 2006 Raj Jain IEEE 802 16 Key Features Broadband Wireless Access Up to 50 km Up to 70 Mbps Data rate vs Distance trade off using adaptive modulation 64QAM to BPSK Offers non line of site NLOS operation 1 5 to 28 MHz channels Hundreds of simultaneous sessions per channel Delivers 1 Mbps per user Both Licensed and license exempt spectrum QoS for voice video and T1 E1 continuous and bursty traffic Support Point to multipoint and Mesh network models Washington University in St Louis CSE574s 6 4 2006 Raj Jain WiMAX A vendor organization for ensuring interoperability A WiMAX certified product will work with other WiMAX certified products Plugfests started November 2005 3rd WiMAX plug fest in France March 2006 WiMAX forum lists certified base stations and subscriber stations from Aperto Networks Redline Communications and SEQUANS Communications More to come Outdoor subscriber stations similar to satellite dish by 2006 350 Indoor subscriber stations by 2006 2007 250 Portable modems for laptops by 2007 2008 100 Washington University in St Louis CSE574s 6 5 2006 Raj Jain Duplexing Options Duplex Bi Directional Communication Full Duplex Both directions at the same time Frequency 1 Base Frequency 2 This is known as Frequency division duplexing FDD Half duplex One direction at a time Base Subscriber Subscriber This is known as Time division duplex TDD Half Duplex FDD HFDD Two frequencies But either transmitter or receiver is on Base Freq1 Freq2 Freq1 Freq2 Freq1 Subscriber Washington University in St Louis CSE574s 6 6 2006 Raj Jain OFDMA Orthogonal Frequency Division Multiple Access A large number of subcarriers e g 2048 Each user has a subset of subcarriers OFDMA is a form of FDMA U1 U2 U3 Washington University in St Louis CSE574s 6 7 2006 Raj Jain IEEE 802 16 PHYs Function LOS Freq Band Carrier Duplexing WirelessMAN SC Pt to pt LOS 10 66 GHz Single TDD FDD WirelessMAN SCa Pt to pt LOS 2 11 GHz Licensed Single TDD FDD WirelessMAN OFDM Pt to mpt NLOS 2 11 GHz Licensed 256 TDD FDD WirelessMAN OFDMA 16e Pt to mpt NLOS 2 11 GHz Licensed 2048 TDD FDD WirelessHUMAN High speed Unlicensed Pt to mpt NLOS 2 11 GHz License Exempt 1 256 2048 TDD Dynamic Freq Sel Washington University in St Louis CSE574s 6 8 2006 Raj Jain IEEE 802 16 PHY Other Features Adaptive Modulation and Coding Space Time Block Codes STBC Adaptive Antenna System Washington University in St Louis CSE574s 6 9 2006 Raj Jain Space Time Block Codes STBC Invented 1998 by Vahid Tarokh Transmit multiple redundant copies of the data from multiple antennas Precisely coordinate distribution of symbols in space and time Receiver combines multiple copies of the received signals optimally to overcome multipath Example Two antennas Antenna 1 Antenna 2 Time Slot 1 S1 S2 S2 S1 Slot 2 Space S1 is complex conjugate of S1 columns are orthogonal Washington University in St Louis CSE574s 6 10 2006 Raj Jain Adaptive Antenna System AAS Base Station Subscriber Station Multiple antennas are used to transmit a subset of OFDM subcarriers each Example 4 Antennas 192 data subcarriers plus 8 pilot subcarriers are divided into 4 groups of 50 subcarriers each Each of the four antennas transmits one group Receivers perform channel estimation on each beam Receivers feedback the channel information to transmitter Transmitters adjust the beam forming accordingly IEEE 802 16 has MAC messages and burst format required for AAS Allows mixing non AAS and AAS subscribers Washington University in St Louis CSE574s 6 11 2006 Raj Jain 802 16 Frame Structure TDD DL Subframe UL Subframe DL Subframe UL Subframe Preamble FCH Burst 1 Burst n Contention for Contention for Initial Ranging Bandwidth Req Burst 1 Burst 2 Burst m Preamble UL Burst TDD Time Division Duplexing FDD Freq Div Duplexing DL Downlink Base to subscriber UL Uplink FCH Frame control header Burst Profile Down link map Uplink map DL channel descriptor etc Washington University in St Louis CSE574s 6 12 2006 Raj Jain 802 16 AAS Zone Structure DL Subframe Preamble FCH Burst 1 FDD Burst n AAS Zone UL Subframe Slot for IR Slot for BR Burst 1 DL Subframe TDD Burst m AAS Zone UL Subframe Non AAS AAS Zone Non AAS AAS Zone Washington University in St Louis CSE574s 6 13 2006 Raj Jain IEEE 802 16 Protocol Structure Service Specific Convergence Sublayer CS MAC MAC Common Part Sublayer CPS Security Sublayer PHY Physical Layer PHY CS Maps packets and ATM cells CPS Fragmentation and reassembly of large MAC SDUs Packing and unpacking of several small MAC SDUs QoS control Scheduling and retransmission of MAC PDUs Bandwidth request Automatic repeat request ARQ using sliding windows Washington University in St Louis CSE574s 6 14 2006 Raj Jain IEEE 802 16 QoS Classes Connection oriented one or more unidirectional connections between subscriber and base Four Service Classes 1 Unsolicited Grant Service UGS CBR traffic like voice 2 Real Time Polling Services rtPS rtVBR like MPEG video 3 Non Real Time Polling Service nrtPS nrtVBR e g FTP 4 Best Effort BE Washington University in St Louis CSE574s 6 15 2006 Raj Jain Scheduling and Link Adaptation Scheduling Base schedules usage of the air link among the subscribers Packet schedulers at the base and subscribers give transmission opportunities to multiple connection queues Link Adaptation Base determines the contents of the DL and UL portions of each frame Base determines the appropriate burst profile code rate modulation level and so on for each subscriber Base determines the bandwidth requirements of the individual subscribers based on the service classes of the connections and on the status of the traffic queues at the base and subscriber Washington University in St Louis CSE574s 6 16 2006 Raj Jain 802 16 MAC Frame Format Generic Frame 1 Encry Frame Checksum Encryption Frame pted Type Present Key Length 1b 1b 6b 1b 1b 2b 1b 16b Connection
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