1. IEEE Std. 802.16 Technique Overview nmgmt.cs.nchu.edu.tw 系統暨網路管理實驗室 Systems & Network Management Lab Reporter ：黃文帥 2007/09/18

2. nmgmt.nchu.edu.tw LOGO Contents What is WiMAX 1 Physical Layer 2 Frame Structure 3

3. nmgmt.nchu.edu.tw LOGO What is WiMAX  Scope: - Specifies the air interface, MAC (Medium Access Control), PHY (Physical Layer).  Purpose: - Enable rapid worldwide deployment of cost-effective broadband wireless access product. - Facilitate competition in broadband access by providing alternatives to wireless broadband access.  Main advantage: - Fast deployment, dynamic sharing of radio resources and low cost.

4. nmgmt.nchu.edu.tw LOGO What is WiMAX Deployment

5. nmgmt.nchu.edu.tw LOGO What is WiMAX Adaptive Modulation  Maximize throughput.  Minimize average power.  Minimize average bit error rate.

6. nmgmt.nchu.edu.tw LOGO What is WiMAX  802.11 is not strictly synchronized. 802.16 is a slotted system and all the transmission must be synchronize.  802.11 uses two-way (Data/ACK) or four-way (RTS/CTS/Data/ACK) handshaking to access channel and transmit data. 802.16 uses a three-way handshaking to set up connection before data transmission (Request/Grant/Transmit).  802.11 does not distinguish control channel and data channel. In 802.16, the control channel and data channel are separated.  In 802.11, a station must compete for every packet. In 802.16, a station can reserve multiple slots for the following packets. 802.11 vs 802.16

7. nmgmt.nchu.edu.tw LOGO Physical Layer  Support framing.  Support both Time Division Duplex (TDD) and Frequency Division Duplex (FDD), as well as half-duplex FDD (H-FDD).  Burst transmission format which supports adaptive burst profiling. - Data allocations within a frame are referred as bursts. - Transmission parameters, including the modulation and coding schemes (burst profiles), may be adjusted individually to each SS on a frame-by-frame basis. - Burst profiles are broadcast via MAC management messages Downlink Channel Descriptor (DCD) and Uplink Channel Descriptor (UCD) periodically. - The actual transmission bandwidth is allocated by BS and broadcast in MAC management messages Downlink MAP (DL-MAP) and Uplink MAP (UP-MAP) in each frame. - Adapt to multiple modulation levels ： BPSK, QPSK, QAM-16, QAM-64. Introduction

8. nmgmt.nchu.edu.tw LOGO Physical Layer  TDD - The UL and DL transmissions occur at different times and usually share the same frequency. (SS does not receive and transmit data at the same time) - A TDD frame has a fixed duration and contains one DL and one UL subframe, whose durations can vary.  FDD - The UL and DL channels are located on separate frequencies. - A fixed duration frame is used for both UL and DL transmissions. - The H-FDD SS does not receive and transmit data at the same time. PHY Duplexing Option

9. nmgmt.nchu.edu.tw LOGO Physical Layer TDD Frame Structure  PS (Physical Slot) - A unit of time, depend on the PHY specification, for allocating bandwidth.

10. nmgmt.nchu.edu.tw LOGO Physical Layer FDD Bandwidth Allocation

11. nmgmt.nchu.edu.tw LOGO Frame Structure Downlink Subframe  TTG/RTG (Transmit/Receive Transition Gap) - A gap between the downlink burst and the subsequent uplink burst in a time division duplex (TDD) transceiver.

12. nmgmt.nchu.edu.tw LOGO Frame Structure Uplink Subframe  SSTG (Subscriber Station Transition Gap)

13. nmgmt.nchu.edu.tw LOGO Frame Structure OFDMA Frame Structure