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Advanced Coding Comparison

Explore coding proposals, advanced FEC code requirements, and complexity comparison for TGn standards, including LDPC, Turbo Codes, and more. Recommendations and facts provided by experts from France Telecom.

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Advanced Coding Comparison

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  1. Advanced Coding Comparison Marie-Helene Hamon, John Benko France Telecom Claude Berrou ENST Bretagne Jacky Tousch TurboConcept Brian Edmonston iCoding John Benko, Marie-Helene Hamon, France Telecom

  2. Outline • Coding proposals in TGn • Advanced FEC Code Requirements for TGn • Comparing Codes • LDPCC vs. Turbo Codes • Facts & Recommendations John Benko, Marie-Helene Hamon, France Telecom

  3. Coding Proposals in TGn(Historical) Partial (13): • Nokia LDPC • Infocomm Research LDPC • ST Micro LDPC • Nortel LDPC • Panasonic LDPC • Hughes LDPC • Inprocomm LDPC • Sharp 7/8 CC • Philips Concatenated RS • Trellisware Hybrid LDPC/TurboCode • France Telecom Turbo Code • Motorola Turbo Code • Wwise Turbo Code Full: • TGnSync LDPC Optional • Wwise LDPC Optional • MitMot Turbo Code Optional • Qualcomm None John Benko, Marie-Helene Hamon, France Telecom

  4. Advanced FEC Code Requirements • Performance • Much better than 802.11a CC • Must have good performance for all blocksizes (small as well as large) • Small blocksize example: VoIP packets (as small as 50 bytes) • Large blocksize example: Streaming HD-Video • Latency • Low, < 6 us • Good performance with a small number of iterations • Implementation • Low Cost – small die size (memory and logic) • Mature, 802.11 – Chipsets require fast time to market Should not be held up due to a FEC without a well-defined implementation John Benko, Marie-Helene Hamon, France Telecom

  5. Complexity Comparison Chip Area • Number of Gates • Technology used (ex. ASIC 0.13 mm, average density of 222 kgates/mm2) • Degree of Parallelism (relates also to max decoded bit-rate) Latency < 6 ms • Number of Iterations • Degree of Parallelism • Clock Frequency used (typical Fclk=200 MHz) *Estimates from [4]+Estimates from [1] John Benko, Marie-Helene Hamon, France Telecom

  6. ST-Micro (Wwise)* LDPCC vs. TC • SISO AWGN • BPSK+ • N=1744 bits • Wwise LDPCC • -972 bits (121.5 bytes) • 12i => 600kGates, 6 us • Duo-Binary TC • -976 bits (122 bytes) • 8i, P=12 => 2.0 mm2, 5.12 us • TGnSync LDPCC • -Equivalent not found *Wwise Results from Berlin presentation [1] +BPSK, R=1/2 proposed as optional mode in Wwise John Benko, Marie-Helene Hamon, France Telecom

  7. Wwise LDPCC*, TC and CC • 2x2 SDM, AWGN • 64-QAM, R=3/4 • Gains over CC @ 10-2 PER • TC : ~3.2 dB • (8 iterations) • LDPCC: ~2.4 dB • (12 iterations) TC LDPCC CC *Wwise Results taken from [2] John Benko, Marie-Helene Hamon, France Telecom

  8. LDPCC from .16e* • SISO, AWGN, QPSK, R=1/2 • LDPCC - 50 iterations (unrealistic) • TC - 8 iterations (realistic) • TC Gains over LDPCC@ 10-2 PER • N=2304: 0.2 dB • N=576 : 0.3 dB • (increase with smaller block size) TC LDPCC TC LDPCC *LDPCC here [3] is slightly different from what is used in TGnSync John Benko, Marie-Helene Hamon, France Telecom

  9. LDPCCs vs. Turbo Codes (TCs) *Generalization John Benko, Marie-Helene Hamon, France Telecom

  10. Facts & Recommendations • Modularity • Performance of the FEC code is independant of system • Codes proposed can be easily put in WWise and TGnSync • Difficult to compare • From FRCC, code performance seen only in context of full system • Current two proposed specfications differ • Wwise nor TGnSych provided simulation results for their code with other proposal • Codes compared in performance should be of similar complexity • Very little complexity results have been seen to this date • Mature code • Enables pre and 1st production devices to ship with advanced coding options. • Action Item? • We need to re-think(create) the advanced coding selection process or we might get stuck with an advanced coding scheme that is not in the best interest of the 802.11n • Suggestion: Form a separate coding sub-group John Benko, Marie-Helene Hamon, France Telecom

  11. References • [1] IEEE 802.11-04/400r4, " ST Microelectronics LDPCC Partial Proposal for 802.11n CFP”, ST Micro, September 2004. • [2] IEEE 802.11/04-0877-09-000n, “WWiSE proposal response to functional requirements and comparison criteria.” • [3] IEEE 802.16e-0/006,  " LDPC Coding for OFDMA PHY", January 2005. • [4] IEEE 802.11-04/1382r1, "Turbo Codes: Complexity Estimates", TurboConcept France Telecom R&D, November 2004. • [5] http://www.uspto.gov • [6] C. Berrou, A. Glavieux, P. Thitimajshima, "Near Shannon limit error-correcting coding and decoding: Turbo Codes", ICC93, vol. 2, pp. 1064-1070, May 93. • [7] C. Berrou, "The ten-year-old turbo codes are entering into service", IEEE Communications Magazine, vol. 41, pp. 110-116, August 03. • [8] C. Berrou, M. Jezequel, C. Douillard, S. Kerouedan, "The advantages of non-binary turbo codes", Proc IEEE ITW 2001, pp. 61-63, Sept. 01. John Benko, Marie-Helene Hamon, France Telecom

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