Partial Proposal: Turbo Codes Month 2000 doc.: IEEE 802.11-00/xxx September 2004 Partial Proposal: Turbo Codes Marie-Helene Hamon, Olivier Seller, John Benko France Telecom Claude Berrou ENST Bretagne Jacky Tousch TurboConcept Brian Edmonston iCoding France Telecom John Doe, His Company

Outline Part I: Turbo Codes Part II: Turbo Codes for 802.11n Month 2000 doc.: IEEE 802.11-00/xxx September 2004 Outline Part I: Turbo Codes Part II: Turbo Codes for 802.11n Why TC for 802.11n? Flexibility Performance France Telecom John Doe, His Company

Outline Part I: Turbo Codes Part II: Turbo Codes for 802.11n Month 2000 doc.: IEEE 802.11-00/xxx September 2004 Outline Part I: Turbo Codes Part II: Turbo Codes for 802.11n Why TC for 802.11n? Flexibility Performance France Telecom John Doe, His Company

Known applications of convolutional turbo codes Month 2000 doc.: IEEE 802.11-00/xxx September 2004 Application turbo code termination polynomials rates CCSDS (deep space) binary, 16-state tail bits 23, 33, 25, 37 1/6, 1/4, 1/3, 1/2 UMTS, CDMA2000 (3G Mobile) 8-state 13, 15, 17 1/4, 1/3, 1/2 DVB-RCS (Return Channel over Satellite) duo-binary, circular 15, 13 1/3 up to 6/7 DVB-RCT (Return Channel over Terrestrial) 1/2, 3/4 Inmarsat (M4) no 23, 35 1/2 Eutelsat (Skyplex) 4/5, 6/7 IEEE 802.16 (WiMAX) 1/2 up to 7/8 Known applications of convolutional turbo codes France Telecom John Doe, His Company

Main progress in turbo coding/decoding since 1993 September 2004 Main progress in turbo coding/decoding since 1993 Max-Log-MAP and Max*-Log-MAP algorithms Sliding window Duo-binary turbo codes Circular (tail-biting) encoding Permutations Parallelism Computation or estimation of Minimum Hamming distances (MHDs) Stopping criterion Bit-interleaved turbo coded modulation Simplicity Performance and simplicity Performance Throughput Maturity Power consumption France Telecom

The TCs used in practice September 2004 The TCs used in practice France Telecom

The turbo code proposed for all sizes, all coding rates September 2004 The turbo code proposed for all sizes, all coding rates Very simple algorithmic permutation: i = 0, …, N-1, j = 0, ...N-1 level 1: if j mod. 2 = 0, let (A,B) = (B,A) (invert the couple) level 2: - if j mod. 4 = 0, then P = 0; - if j mod. 4 = 1, then P = N/2 + P1; - if j mod. 4 = 2, then P = P2; - if j mod. 4 = 3, then P = N/2 + P3. i = P0*j + P +1 mod. N No ROM Quasi-regular (no routing issue) Versatility Inherent parallelism France Telecom

Decoding Max-Log-MAP algorithm Sliding window September 2004 Decoding Max-Log-MAP algorithm Sliding window + inherent parallelism, easy connectivity (quasi-regular permutation) France Telecom

Decoding complexity Useful rate: 100 Mbps with 8 iterations September 2004 Decoding complexity Useful rate: 100 Mbps with 8 iterations 5-bit quantization (data and extrinsic) Gates 164,000 @ Clock = 100 Mhz 82,000 @ Clock = 200 Mhz 54,000 @ Clock = 400 Mhz RAM Data input buffer + 8.5xk for extrinsic information + 4000 for sliding window (example: 72,000 bits for 1000-byte block) For 0.18m CMOS No ROM Duo-binary TC decoders are already available from several providers (iCoding Tech., TurboConcept, ECC, Xilinx, Altera, …) France Telecom

Outline Part I: Turbo Codes Part II: Turbo Codes for 802.11n Month 2000 doc.: IEEE 802.11-00/xxx September 2004 Outline Part I: Turbo Codes Part II: Turbo Codes for 802.11n Why TC for 802.11n? Flexibility Performance France Telecom John Doe, His Company

Introduction Purpose Properties of Turbo Codes (TCs) September 2004 Introduction Purpose Show the multiple benefits of TCs for 802.11n standard Overview of duo-binary TCs Comparison between TC and .11a Convolutional Code High Flexibility Complexity Properties of Turbo Codes (TCs) Rely on soft iterative decoding to achieve high coding gains Good performance, near channel capacity for long blocks Easy adaptation in the standard frame (easy block size adaptation to the MAC layer) Well controlled hardware development and complexity TC advantages led to recent adoption in standards France Telecom

September 2004 Duo-Binary Turbo Code France Telecom

Duo-Binary Turbo Code Duo-binary input: September 2004 Duo-Binary Turbo Code Duo-binary input: Reduction of Latency & Complexity (compared to UMTS TCs) Complexity per decoded bit is 35 % lower than binary UMTS TCs. Better convergence in the iterative decoding process Circular Recursive Systematic Codes Constituent codes No trellis termination overhead! Original permuter scheme Larger minimum distance Better asymptotic performance France Telecom

# of Iterations vs. Performance September 2004 # of Iterations vs. Performance The number of iterations can be adjusted for better performance – complexity trade-off France Telecom

Simulation Environment September 2004 Simulation Environment Both Turbo Codes and 802.11a CCs simulated Simulation chain based on 802.11a PHY model SISO configuration CC59 and CC67 followed Simulated Channels: AWGN, models B, D, E No PHY impairments Packet size of 1000 bytes. Minimum of 100 packet errors Assume perfect channel estimation & synchronization Turbo Code settings: 8-state Duo-Binary Convolutional Turbo Codes Max-Log-MAP decoding 8 iterations France Telecom

Performance: AWGN 3.5-4 dB gain over 802.11a CC September 2004 France Telecom

Performance: model B ~3 dB gain over 802.11a CC September 2004 France Telecom

Performance: model D ~3 dB gain over 802.11a CC September 2004 France Telecom

Performance: model E ~3 dB gain over 802.11a CC September 2004 France Telecom

Flexibility All Coding Rates possible (no limitations) September 2004 Flexibility All Coding Rates possible (no limitations) Same encoder/decoder for: any coding rate via simple puncturing adaptation different block sizes via adjusting permutation parameters 4 parameters are used per block size to define an interleaver Higher PHY data rates enabled with TCs: High coding gains over 802.11a CC ( =>lower PER) More efficient transmission modes enabled more often. Combination with higher-order constellations Better system efficiency ARQ algorithm used less frequently France Telecom

Conclusions Mature, stable, well established and implemented September 2004 Conclusions Mature, stable, well established and implemented Multiple Patents, but well defined licensing All other advanced FECs also have patents Complexity: Show 35% decrease in complexity per decoded bit over UMTS TCs Performance is slightly better than UMTS TCs Significant performance gain over .11a CC: 3.5 - 4 dB on AWGN channel 3 dB on 802.11n channel models France Telecom

September 2004 References [1] IEEE 802.11-04/003, "Turbo Codes for 802.11n", France Telecom R&D, ENST Bretagne, iCoding Technology, TurboConcept, January 2004. [2] IEEE 802.11-04/243, "Turbo Codes for 802.11n", France Telecom R&D,iCoding Technology, May 2004. [3] IEEE 802-04/256, "PCCC Turbo Codes for IEEE 802.11n", IMEC, March 2004. [4] C. Berrou, A. Glavieux, P. Thitimajshima, "Near Shannon limit error-correcting coding and decoding: Turbo Codes", ICC93, vol. 2, pp. 1064-1070, May 93. [5] C. Berrou, "The ten-year-old turbo codes are entering into service", IEEE Communications Magazine, vol. 41, pp. 110-116, August 03. [6] C. Berrou, M. Jezequel, C. Douillard, S. Kerouedan, "The advantages of non-binary turbo codes", Proc IEEE ITW 2001, pp. 61-63, Sept. 01. [7] TS25.212 : 3rd Generation Partnership Project (3GPP) ; Technical Specification Group (TSG) ; Radio Access Network (RAN) ; Working Group 1 (WG1); "Multiplexing and channel coding (FDD)". October 1999. [8] EN 301 790 : Digital Video Broadcasting (DVB) "Interaction channel or satellite distribution systems". December 2000. [9] EN 301 958 : Digital Video Broadcasting (DVB) "Specification of interaction channel for digital terrestrial TV including multiple access OFDM". March 2002. France Telecom