Transcript Многопороговые алгоритмы, реализованны

Optimum Decoding
Characteristics Achievement
on the Basis of
Multithreshold Algorithms
(for ISCTA’07)
Space Research Institute RAS
United Radioelectronic Technologies
--------
V.V.Zolotarev, S.V.Averin,
I.V.Chulkov
Application of
noiseproof coding is
necessary,
because:
•
•
•
•
•
•
1. The large code gain can be received!
Thus:
2. Distance of communication increases.
3. Data transmission reliability and speed
increases.
4. The sizes of aerials considerably decrease.
6. Work of a communication system is provided
at essential higher noise
levels.
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The lower estimations for error probabilities of
an optimum decoding block codes with R=1/2 in BSC.
Even codes of length n=1000 are inefficient at
probability of an error Ро~0.08 in the channel.
But the theory states, that it is possible to work
successfully if P0<0.11 when C>R
C=R
n=24
0,11
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Threshold repeated short
convolutional code decoding
R=1/2 d=5
But it was a weak result!
Information
Out
Out
Syndrome
Threshold
element
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Repeated Application Efficiency
of the Threshold Algorithm
1
1) попытка 1
2) попытка 2
Доля исправляемых блоков
Part of
good
decoded0.8
blocks
0.6
0.4
2
Very
1
good!
0.2
0
10
2
d=11 R=1/2
n=1000
20
30
Why is it
much more
than d/2?
1
40
блоке
N Число
errors ошибок
in code вblock
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60
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The Convolutional Multithreshold
Decoder for a Code
with R=1/2, d=5 and 3 iterations
uˆ
vˆ
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
6
5
4
3
2
1
0
6
5
4
3
2
1
0
6
5
4
3
2
1
0
T1
T2
T3
It is - discovery!
Рис. 1. Многопороговый декодер сверточного СОК с R=1/2, d=5 и nA=14
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The Block Multithreshold Decoder
for Code with R=1/2 and d=5
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SOFTWARE IMPLEMENTATION OF
MULTITHRESHOLD DECODER
1. The complexity of software implementation:
NMTD1=(I+1)(d+2) additive equivalent operations
on an information bit, where I is number of
iterations and d is a minimal code distance.
2. MTD is applicable for codes with d<20 and
needs about 10-20 decoding iterations.
3. It’s possible to decrease number of operations
to NMTD2~4d+3I operations. It is much less than
turbo codes decoder complexity!
-In ~100 times more quickly, than for turbo codes!
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Chipset MTD Decoder
at PLIS Xilinx
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NEW DECODER IN ALTERA PLIS
FOR SPEED 600Mb/s AND MORE IN THE SPACE CHANNEL
Декодер МПД на ПЛИС ALTERA, 640 Мб/с Pb(e)~10-7
Created – Создано - in 2007
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HARDWARE IMPLEMENTATION OF
MULTITHRESHOLD DECODER
1. MTD consists of shift registers. They are the
fastest elements in PLIS or BIS. The part of other
elements in MTD is less than 1%.
2. MTD consists of 6 - 40 parallel shift registers
and one-step threshold elements. That’s why the
complexity of MTD implemented on PLIS is in
100 and more times faster than other decoder
3. Characteristics of MTD PLIS codec :
- speed is about 320 - 960 Mbps and more,
- coding gain is about 6,5 - 9,5 dB.
So, decoding speed is as for single 2 bit adder!
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Characteristics MTD, VA and a Turbo Codes in Gaussian Channels at R=1/2
1,E+00
С=1/2
Bit error rate Pb(e)_
1,E-01
MTDNEC
1,E-02
MTD-L
MTDmd2
VA+RS
MTD-X
1,E-03
VA К=7
1,E-04
1,E-05
MTD+
CC2
TURBO
1,E-06
MTD+CC3
1,E-07
0
0,5
1
1,5
2
2,5
3
3,5
4
RATIO Eb/N0, dB
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Which decoder must be used?
- Most simple and effective !!!
Improvements in decoder effectiveness
CG - the history of increments
10
9
8
CG,dB
7
Turbo
6
5
4
3
ЭВК
CC: VA:RS
VA
MTD
TD
2
1
0
1965
1970
1975
1980
1985
1990
1995
2000
cc:
turbo,
MTD,
LDPC?
?
2005 2010
Years
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Reference book
«Помехоустойчивое
кодирование.
Методы и алгоритмы»
под редакцией
Ю.Б.Зубарева
Авторы: В.В.Золотарёв, Г.В.Овечкин
Издательство
«Горячая линия - Телеком», 2004г.
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В.В.Золотарёв
Теория и алгоритмы
многопорогового
декодирования
Под редакцией
члена-корреспондента РАН
Ю.Б.Зубарева
Издательства
«Радио и связь»,
«Горячая линия - Телеком»
2006 г.
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Conclusions
1. We
have invented effective iterative
MTD algorithms 35 years ago.
2. Complexity of program versions MTD - for today
an absolute minimum of calculations. A difference from a
turbo codes on number of operations at comparable
efficiency of ~100 times!
3. Hardware MTD can be faster than a turbo decoders up
to 1000 times!
4. Decisions MTD quickly aspire to decisions of the
optimum decoder (OD) even for large noise level
5. MTD – is the absolute leader by criteria
"speed" and "complexity-efficiency".
6. MTD – is one of the leading algorithms!
WE SUGGEST TO WORK TOGETHER!
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SRI RAS, URT
In Russia: e-mail: [email protected]
Work ph.: +7 495 333 45 45, +7 495 573 51 32
mоb.: +7 916 518 86 28,
V.V.Zolotarev, S.V.Averin, I.V.Chulkov
www.mtdbest.iki.rssi.ru
17.07.2007
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Space Research Institute RAS
т.+7-(495)-333-45-45
E-mail: [email protected]
моб.: +7-916-518-86-28
www.mtdbest.iki.rssi.ru
17.07.2007 г.
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