IEEE802.16e-2005 Mobile WiMAX PHY Layer Simulation

1. IEEE802.16e-2005 Mobile WiMAX PHY Layer Simulation Prepared by RGS SZR Software Consulting September 2009

2. Mobile WiMAX PHY Layer Simulation • Fixed WiMAX PHY layer model per IEEE802.16-2004 std was developed in 2008. • The model calculates the BER as the signal propagates through the various stages of the physical layer and the communications channel. TRANSMITTED DATA RANDOMIZER RS-CC ENCODER INTERLEAVER MODULATOR TRANSMITTER CHANNEL SIMULATION RECEIVED DATA DE-RANDOMIZER DECODER DE-INTERLEAVER DEMODULATOR RECEIVER • TOTAL NUMBER OF BITS • NUMBER OF BIT ERRORS • BIT ERROR RATE (BER) BIT ERROR RATE CALCULATION SZR Software Consulting

3. Mobile WiMAX PHY Layer Simulation • The fixed WiMAX PHY layer simulation model developed code for the following basic building blocks common to fixed and mobile WiMAX: • Randomization • Reed-Solomon and Convolutional Coding • Interleaving • Modulation (BPSK, QPSK, 16-QAM, 64-QAM) • DL and UL subcarrier permutations (PUSC, FUSC, AMC) • FFT and IFFT transforms • Cyclic Prefix insertion and removal • Channel modeling • Channel estimation (preamble-based) • Fixed WiMAX uses OFDM technology (2.5 MHz bandwidth). • For the mobile WiMAX simulation additional code was developed to implement scalable OFDMA (1.25, 5.0, 10.0, and 20.0 MHz bandwidths). SZR Software Consulting

4. Mobile WiMAX PHY Layer Simulation • For mobile WiMAX, the downlink (BS to SS) and uplink (SS to BS) are simulated: DOWNLINK UPLINK BASE STATION SUBSCRIBER (MOBILE) STATION The DL and UL chains both consist of the same randomization, convolutional encoding, interleaving, modulation, transmitter, channel simulation, receiver, channel estimation, demodulation, de-interleaving, decoding, and de-randomization steps. SZR Software Consulting

5. Mobile WiMAX PHY Layer Simulation • Parameters for the downlink (DL) and uplink (UL) are specified by the Media Access Control (MAC) layer. • The MAC layer completely defines the WiMAX waveform (e.g. bandwidth, cyclic prefix) and the WiMAX frame. • The WiMAX frame consists of the DL and UL subframes. • The DL subframe defines how data is to be transmitted to the SS’s and also contains management and control information. • The UL subframe defines how the BS expects to receive data from the SS’s. • The WiMAX frame is typically 5-msec long but can vary. • The number of subcarrier frequencies depends on the nominal bandwidth used. DL SUBFRAME UL SUBFRAME Subcarriers Frame duration (msec) SZR Software Consulting

6. Mobile WiMAX PHY Layer Simulation • The mobile WiMAX simulation model GUI permits the WiMAX frame to be completely specified, and is effectively a pseudo-MAC layer simulation: SZR Software Consulting

7. Mobile WiMAX PHY Layer Simulation • The GUI enables the specification of the following parameters: • Waveform setup: • Bandwidth (1.25, 5.0, 10.0, or 20.0 MHz, nominal 10.0 MHz) • Cyclic prefix size (1/32 to 1/4, nominal 1/8) • Frame duration (2.0 to 20.0 msec, nominal 5.0 msec) • Overhead regions setup (for preamble, FCH, DL/UL maps) • Preamble setup: • Cell IDs per segment • Boosting (nominal 9-dB) • Frame control header (FCH) setup • DL/UL zone setup: • Maximum of 5 DL zone switches (PUSC, FUSC or AMC) • Maximum of 3 UL zone switches (PUSC, OPUSC or AMC) • DL data bursts setup • UL data bursts setup SZR Software Consulting

8. Mobile WiMAX PHY Layer Simulation Frame preamble (yellow), FCH (magenta) and DL MAP (green) regions generated automatically by the simulation model DIUC of each burst (modulation type, coding type and rate) Each burst can be assigned up to 6 connection IDs A maximum of 10 DL databursts can be specified in the DL sub-frame Location of burst within sub-frame Data capacity of burst in bytes Subcarrier permutation mode of current zone Boosting, repetition code and transmit data type Base station ID DL databursts setup SZR Software Consulting

9. Mobile WiMAX PHY Layer Simulation A maximum of 10 UL databursts can be specified in the UL sub-frame UL burst allocation type UIUC of each burst (modulation type, coding type and rate) Connection ID assigned to burst UL MAP appended is automatically following the DL MAP Data capacity of burst (UBS) in bytes and subcarrier permutation mode of current zone Allocation start time UL databursts setup SZR Software Consulting

10. Mobile WiMAX PHY Layer Simulation • A WiMAX cell is simulated containing up to 6 SS’s. • The ‘Simulation -> Setup’ menu is used to specify for each SS: • Connection ID (CID) • Channel type (SUI channel number and instance) • Channel signal-to-noise ratio (SNR) • 6 SUI (Stanford University Interim) channel models can be specified, for different multipath fading characteristics (i.e. pathloss, delay spread, Doppler spread, K-factor). • White Gaussian channel noise can be specified from 10 to 60-dB. • The fading channel characteristics are displayed (below). Fading channel relative path gains vs. path delays Fading channel magnitude frequency response curve SZR Software Consulting

11. Mobile WiMAX PHY Layer Simulation • The simulation is executed as ‘Simulation -> Run’. • The DL is simulated first: • BS transmits the frame to all SS’s within the cell. • All SS’s receive the frame, decode the FCH and DL/UL maps. • On FCH or DL/UL map decode error the frame is dropped. • If the SS has not been assigned a CID the frame is dropped. • The SS decodes the DL databurst (if any) and obtains all parameters it needs for the (subsequent) UL transmission. • The simulation compares the transmitted and received data, calculates and displays the DL BER. • Next the UL is simulated: • The SS packs the databurst(s) (if any) and transmits to the BS. • The BS receives the frame and decodes the data per the UL burst allocations. • The simulation compares the transmitted and received data, calculates and displays the UL BER. SZR Software Consulting

12. Mobile WiMAX PHY Layer Simulation The WiMAX cell containing up to 6 subscriber station. Status messages are displayed as the simulation runs. Plots of fading channels for each SS. The channel estimate is shown in black. Note the poor quality of the channel estimate for SS #4 results in a UL MAP extraction error, hence the frame is dropped. The simulation results box displays the BER for each databurst. Note in this case only 3 DL bursts were transmitted at different modulations and channel types. The simulation status message box contains a complete listing of all simulation steps for debugging and verification purposes. Example simulation run (DL only) SZR Software Consulting

13. Mobile WiMAX PHY Layer Simulation • The simulation model generates a detailed output listing of all steps for software debugging and verification: • Starting downlink PHY layer simulation.. • DL MAP length: 8-slots • Applying FEC and modulating DL MAP message.. • UL MAP length: 7-slots • Applying FEC and modulating UL MAP message.. • Creating mapping matrix.. • Generating random data for each burst.. • Data burst: 1 UBS: 54-bytes • Tx data 1: 0xFF7B39C3... • Data burst: 2 UBS: 96-bytes • Tx data 2: 0x38A4FE51... • Data burst: 3 UBS: 90-bytes • Tx data 3: 0x6260703D... • Applying FEC and modulating data for each burst.. • Data burst: 1 • DIUC: 0 (QPSK(CC)1/2) • Ncpc: 2 code rate: 0.5 mod type: 2 • . . . . SZR Software Consulting

14. Mobile WiMAX PHY Layer Simulation • Summary • The DL and UL portions of the mobile WiMAX simulation (Version V11) are basically complete with the exception of the following: • Zone switches (all DL and UL burst are in the 1st PUSC zone), • Segmentation (none used), • Data repetition (none used), • Data types (random data only), • Adaptive modulation and coding (AMC), • Channel quality, CDMA ranging and PAPR reduction channels, • UL block-type allocations, • Handling of extended DIUC and UIUC types, • MAC-layer management and control messages, • Interface of I/Q data to external signal generator and signal analyzer hardware. • The above functionalities will be included in subsequent software versions. SZR Software Consulting