Post on 03-Apr-2018
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
1/22
doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 1
Partial Proposal:
Turbo Codes
Marie-Helene Hamon, Olivier Seller, John Benko France Telecom
Claude Berrou ENST Bretagne
Jacky Tousch TurboConcept
Brian Edmonston iCoding
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
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doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 2
Outline
Part I: Turbo Codes
Part II: Turbo Codes for 802.11n
Why TC for 802.11n?
Flexibility
Performance
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
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doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 3
Outline
Part I: Turbo Codes
Part II: Turbo Codes for 802.11n
Why TC for 802.11n?
Flexibility
Performance
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
4/22
doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 4
Known applications
of convolutional
turbo codes
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)
binary,
8-state
tail bits 13, 15, 17 1/4, 1/3, 1/2
DVB-RCS
(Return Channelover Satellite)
duo-binary,
8-state
circular 15, 13 1/3 up to 6/7
DVB-RCT
(Return Channel
over Terrestrial)
duo-binary,
8-state
circular 15, 13 1/2, 3/4
Inmarsat
(M4)
binary,
16-state
no 23, 35 1/2
Eutelsat
(Skyplex)
duo-binary,
8-state
circular 15, 13 4/5, 6/7
IEEE 802.16
(WiMAX)
duo-binary,
8-state
circular 15, 13 1/2 up to 7/8
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
5/22
doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 5
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
Simplicity
Performance and simplicity
Performance
Performance
Throughput
Maturity
Power consumption
Performance and simplicity
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
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doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 6
kbinarydata
permutation
Y1
Y2
X
permutation
k/2binarycouples
pol ynom i al s 15, 13 ( or 13, 15)
kbinarydata
permutation
Y1
X
permutation
k/2binarycouples
(a) (b)
The TCs used in practice
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
7/22
doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 7
The turbo code proposed for all sizes, all coding rates
permutation
(N)N = k/2
couplesof data
co
deword
systematic part
redundancy part
1
2
punctu-ring
Y
A
B
A
B
Y
systematic part
redundancy part+
circular (tail-biting)encoding
Very simple algorithmic permutation:
i =0,, N-1, j = 0, ...N-1
level 1: ifj mod. 2 = 0, let (A,B) = (B,A) (invert the couple)
level 2:
- ifj mod. 4 = 0, thenP= 0;
- ifj mod. 4 = 1, thenP=N/2 +P1;
- ifj mod. 4 = 2, thenP=P2;
- ifj mod. 4 = 3, thenP= N/2 +P3.
i =P0*j +P+1 mod.N
No ROM
Quasi-regular (no routing issue)
Versatility
Inherent parallelism
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
8/22
doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 8
Decoding
Max-Log-MAP algorithm
Sliding window
FER
5
5
5
5
10-3
10-4
10-1
10-2
Eb/N0 (dB)3 4
Full MAP Max-Log-MAP
Theoretical limit
(sphere packing bound)
Gaussian,
1504 bits,
R = 4/5
+ inherent parallelism, easy connectivity (quasi-regular permutation)
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
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doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 9
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
+
8.5xkfor extrinsic information
+ 4000 for sliding window
(example: 72,000 bits for 1000-byte block)
No ROM
For 0.18m CMOS
Duo-binary TC decoders are already available from several providers
(iCoding Tech., TurboConcept, ECC, Xilinx, Altera, )
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
10/22
doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 10
Outline
Part I: Turbo Codes
Part II: Turbo Codes for 802.11n
Why TC for 802.11n?
Flexibility
Performance
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
11/22
doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 11
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
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
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doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 12
Duo-Binary Turbo Code
s1 s3s2A
B
W
systematic part
redundancy partY
permutation
(k/2)N = k/2 couples
of data
c
o
de
w
o
r
d
systematic part
redundancy part
1
2
puncturing
Y1 or 2W1 or 2
A
B
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
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doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 13
Duo-Binary Turbo Code
Duo-binary input: Reduction ofLatency & 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
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
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doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 14
# of Iterations vs. Performance
The number of
iterations canbe adjusted for
better
performance
complexity
trade-off
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
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doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 15
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
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
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doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 16
Performance: AWGN
3.5-4 dB
gain over
802.11a CC
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
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doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 17
Performance: model B
~3 dB
gain over
802.11a
CC
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
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doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 18
Performance: model D
~3 dB
gain over
802.11a
CC
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
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doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 19
Performance: model E
~3 dB
gain over
802.11a
CC
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
20/22
doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 20
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
7/28/2019 11 04 0903-00-000n Turbo Codes Partial Proposal Presentation Slides
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doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 21
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 betterthan UMTS TCs
Significant performance gain over .11a CC: 3.5 - 4 dB on AWGN channel
3 dB on 802.11n channel models
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doc.: IEEE 802.11-04/903-00-0000n
Submission
September 2004
France TelecomSlide 22
References
[1] IEEE 802.11-04/003, "Turbo Codes for 802.11n", France Telecom R&D, ENSTBretagne, iCoding Technology, TurboConcept, January 2004.
[2] IEEE 802.11-04/243, "Turbo Codes for 802.11n", France Telecom R&D,iCodingTechnology, 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-correctingcoding 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", IEEECommunications Magazine, vol. 41, pp. 110-116, August 03.
[6] C. Berrou, M. Jezequel, C. Douillard, S. Kerouedan, "The advantages of non-binaryturbo codes", Proc IEEE ITW 2001, pp. 61-63, Sept. 01.
[7] TS25.212 : 3rd Generation Partnership Project (3GPP) ; Technical SpecificationGroup (TSG) ; Radio Access Network (RAN) ; Working Group 1 (WG1); "Multiplexingand channel coding (FDD)". October 1999.
[8] EN 301 790 : Digital Video Broadcasting (DVB) "Interaction channel or satellitedistribution systems". December 2000.
[9] EN 301 958 : Digital Video Broadcasting (DVB) "Specification of interactionchannel for digital terrestrial TV including multiple access OFDM". March 2002.