HNS Proposal for 802.11n Physical Layer doc.: IEEE 802.11-04-0941-00-000n Sept 2004 HNS Proposal for 802.11n Physical Layer Mustafa Eroz, Feng-Wen Sun, & Lin-Nan Lee meroz@hns.com fsun@hns.com llee@hns.com Hughes Network Systems 11717 Exploration Lane Germantown, MD 20876 Mustafa Eroz, Hughes Network Systems Mustafa Eroz, Hughes Network Systems

Proposal Topics PHY and Air Interface Description doc.: IEEE 802.11-04-0941-00-000n Sept 2004 Proposal Topics PHY and Air Interface Description Supported Rate Set (mandatory/optional) Preamble Design Approach Block Diagram used for Simulation Spectral Mask with non-linear model Short Block Length LDPC Performance Curves Mustafa Eroz, Hughes Network Systems Mustafa Eroz, Hughes Network Systems

Sept 2004 PHY and Air Interface The air interface is built upon IEEE 802.11a (1999) PHY specifications and associated overhead OFDM Modulation with PSK and QAM (20/64) MHz channel spacing, 52 Sub-carrier set 48 data carriers and 4 pilots (center location not used) Preamble modified for MIMO Compatible with 802.11a air-interface 2, 3 and 4 TX antenna HT modes support One TX Antenna mode for legacy STA support PHY-MAC maximum efficiency of 60% assumed In AP-STA test, 100Mbps at MSDU  167 Mbps at PHY Mustafa Eroz, Hughes Network Systems

802.11n Rate Set Supported Sept 2004 No. of TX Antennas Modulation Type Transmit bits per channel use Code Rate Info. Bytes per channel. use PHY Info Rate (Mbps) MAC Info Rate (Mbps) @60% of PHY Rate 4 BPSK 192 1/2 12 30 18 2/3 45 27 QPSK 384 24 60 36 8-PSK 576 90 54 16-QAM 768 48 120 72 32-QAM 960 150 64-QAM 1152 180 108 96 240 144 3 288 864 56 140 84 2 6 15 9 480 75 Mustafa Eroz, Hughes Network Systems

Preamble/ Pilot Approach to HNS PHY Proposal Sept 2004 Preamble/ Pilot Approach to HNS PHY Proposal We base our approach on the 802.11a OFDM Specifications There are 53 frequency bins in 802.11a OFDM Indexed -26, -25, …-1, 0, 1 … 25 and 26. The zero index (frequency location) is not used. -21, -7, 7 and 21 are used as Pilots during data transmission Modulated by127 bit long PN code (x7 + x4 + 1) on the ‘1st’ Antenna Use the same frequency set on each of the TX Antennas Use different phase of the 127 bit PN (quasi-orthogonal) on each of the other Antennas 48 remaining bins are used for data transmission Each TX antenna uses the same 48 sub-carrier set but with different data stream The transmission commences with an 802.11a specified preamble called the PLCP preamble 8 usec ‘short’ preamble with only 12 sub-carriers active 8 usec ‘long’ preamble all sub-carriers active per a specified 52 bit sequence Short preamble empty bins are used by secondary antennas  4 TX supported 52 bits of the Long preamble are transmitted sequentially over the TX antenna set Mustafa Eroz, Hughes Network Systems

Preamble Approach for Multiple TX Antennas Sept 2004 (-26) (26) Δf 0.3125 MHz 1 1 -1 -1 1 1 . . . . . . . . . Proposed: Long Preamble Sequence Spread Sequentially over the Four TX Antennas Proposed: Short Training Preamble (First 8 usec) over one ‘First’ and Three ‘Other’ Antennas 1+ j -1- j Preamble Duration = 8 usec Preamble duration = 8 usec 1.0 IEEE 802.11a Standard Short Training Preamble (i.e. first 8 usec) from one TX Antenna - 26 + 26 First Antena (s0) Other Antennas (s1, s2 and s3) . . . . . . -1 1 1 1 1 L-26,26 per section 17.3.3 Std 802.11a -1999 Preamble Approach for Multiple TX Antennas Mustafa Eroz, Hughes Network Systems

Simulation Block Diagram: 3 TX by 2 RX Example Sept 2004 Simulation Block Diagram: 3 TX by 2 RX Example IFFT Prefix Digital-RF-PA FFT Remove P/fix OFDM Symbol Generator (frequency domain) Preamble Attachment & 1:3 OFDM Demux Insert Pilots PSK/QAM Modulator LDPC Encoder MIMO LDPC Block Formatter Information bits MIMO Preambles RF-Digital PA = Rapp’s model, p=3 LNA NF = 10dB Prefix Timing/Channel Estimation/Symbol Timing/ Frequency/Phase Acquisition/Tracking DETECTION MAP (LLR) Iterative Detector DECODER y1 y2 y = [y1 y2]T y = Ax + n, ‘A’ per 802.11n Channel Model Reconstruct PSDU In out x = [x1 x2 x3]T x1 x2 x3 iteration Channel Estimates Mustafa Eroz, Hughes Network Systems

Simulation Conditions Sept 2004 Simulation Conditions 2,3 and 4 TX antenna cases simulated NLOS Model for B, D and E used in simulation Used Florescent light effects for Model D&E Antenna Spacing of half-wavelength used Mustafa Eroz, Hughes Network Systems

Transmit Spectrum of the OFDM Signal Through PA Model Sept 2004 Transmit Spectrum of the OFDM Signal Through PA Model OFDM Signal 16-QAM after Non-linear Amplifier IBO = 8 dB OFDM Signal 16-QAM after Non-linear Amplifier IBO = 3 dB Fully compliant with spectral mask Essentially the same spectral density for 64-QAM Mustafa Eroz, Hughes Network Systems

Simulation Methodology Sept 2004 Simulation Methodology Coding and BB TX module Applies appropriate padding to info bits at encoder input as needed 192 Transmission (coded) bit blocks into a LDPC encoder Perform row-column interleaving generate PSK/QAM modulation symbols OFDM and Channel Model Arranges into transmission vector for 2, 3 or 4 TX antennas Converts modulation symbol stream into OFDM symbols with cyclic prefix, 4 usec/OFDM Symbol Runs through channel model Detects OFDM signals on each of the RX antenna Delivers demodulated samples from each RX antenna to MAP detector Mustafa Eroz, Hughes Network Systems

Performance for Channel Model B doc.: IEEE 802.11-04-0941-00-000n Sept 2004 Performance for Channel Model B Mustafa Eroz, Hughes Network Systems Mustafa Eroz, Hughes Network Systems

Performance for Channel Model D Sept 2004 Performance for Channel Model D Mustafa Eroz, Hughes Network Systems

Performance for Channel Model E Sept 2004 Performance for Channel Model E Mustafa Eroz, Hughes Network Systems

AWGN Channel Performance Sept 2004 AWGN Channel Performance Mustafa Eroz, Hughes Network Systems