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For channels with a large noise level: MTD -. Quick Decoders. IKI RAS Dr. Sc. V. V. Zolotarev. 0 1 0 0 0?1110? 01? 0 1 # ?. The main limitation in information theory for coding. The condition must be always satisfied : R < C !

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For channels with a large noise level: MTD -

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For channels with a large noise level:MTD -

Quick Decoders


Dr. Sc. V. V. Zolotarev

0 1 0 0 0?1110? 01? 0 1 # ?

The main limitation in information theory for coding

  • The condition must be always satisfied:

  • R < C !

  • Here: R - code rate, C - channel capacity.

  • In this case digital transmission is possible with an arbitrary small probability of an error.

V.V.Zolotarev. The quick decoders

Whenever possible - it is else easier!!!

An example of the encoder

for a convolutional code

with a code rate R=1/2.

V.V.Zolotarev. The quick decoders

The lower estimations of error probabilities of optimum block code decoding with R=1/2 in BSC. Even the codes with length n=1000 are ineffective at channel error probability Po > 0.07. But the theory affirms, that it is possible to work successfully at Po < 0.11, in accordance to main condition C > 1/2. And it is true for total searching methods!

V.V.Zolotarev. The quick decoders

Main problems of coding technics

  • 1.Decoding - more simple!.

  • 2. Reliability - better!.

  • 3.To take into account real communications’ requirements

  • 4. How must they achieve it? With iterative multithreshold decoders (MTD)!!!

V.V.Zolotarev. The quick decoders

Multithreshold decoding (MTD)

  • If MTD for a long time changes characters of the received data, it can achieve the solution of the optimum decoder (OD)with linear decoder complexity

    It is - a result

    of iterative methods application

  • Usually "price" of the OD solution

    (as for Viterbi algorithm) - total search,

    But for MTD the complexity is linear !!!

V.V.Zolotarev. The quick decoders

Рис. 1. Многопороговый декодер сверточного СОК с R=1/2, d=5 и nA=14

This is convolutional MTD with R=1/2, d=5 and 3 iterations

V.V.Zolotarev. The quick decoders

Hard realization complexity (VLSI)

1. MTD contains almost only memory or shift registers. They are most quick elements in all PLIS or VLSI. Other scheme elements - are less than 1% . 2. MTD has 3 - 40 such registers and threshold switches (TS) are with instant function calculation reaction. So this decoders appear to be for some code parametersin ~ 1000 times more quickthan turbo and others decoders!

V.V.Zolotarev. The quick decoders

Minimum computations in MTD(number of operations per bit, software realization)

Typical complexity: N1=C0*d*I,

but in MTD: onlyN2=C1*d+C2*I,

- Sum d and I, no multiplications(!!!)

Ci- little integers, d – code distance, I-iterations.

  • It is in ~ 100 times (!!!)more simple than for turbo codes also!

V.V.Zolotarev. The quick decoders

The explanation of MTD efficiency

  • 1. The special very simple iterative procedure was created.

  • 2. The new codes with minimal grouping of errors were constructed.

  • 3. The optimization of many hundreds parameters of the decoder is carried out.

  • Problems 1 и 2 - «very heavy»

  • task 3 - it was not even claimed!

V.V.Zolotarev. The quick decoders

What is needed for communications?

  • Prof. Berlecamp(USA) said in 1980 in IEEE survey:

    “ It is a code gain”,

    - the measure of signal power growth effect due to coding of transmitting data with profit ~$1 million for 1 dB of code gain.

  • Now it is else much more desirable {see our survey in main Russian communication magazine «Electrosvaz» No.9, 2003; its translation is placed at our web-site too}

  • Every 1 dB of code gain gives for communication nets profit up to hundreds millions of dollars now!

V.V.Zolotarev. The quick decoders

Code Gain - power increase effect!

V.V.Zolotarev. The quick decoders

The scientific and technological revolutions in coding

V.V.Zolotarev. The quick decoders

Welcome for everybody! Visitors of oursite in March, 2004.

~1 Gbytes asked data from us for more than 5000 site visitors of 38 countries in 2004.

V.V.Zolotarev. The quick decoders


1. We discovered iterative MTD methods 32 years ago.

2. Complexity of software MTD is absolutely minimal.

Difference is ~100 times with turbo codes!

3.Hardware MTD is ~1000 times more quick than turbo!

4. MTD decisions very quickly converge to optimal decoder (OD) results!

5. MTD is absolute leader among all decoders on criterion “complexity-effectiveness”. 6. So we are absolute leaders forever in decoding! We go ahead of the whole world!

V.V.Zolotarev. The quick decoders

Thank you!




Space Research Institute RAS

In Russia: e-mail:

Work tel. +7 095 333 23 56, +7 095 261 54 44

mоb.: +7 916 518 86 28, V.V.Zolotarev

V.V.Zolotarev. The quick decoders

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