CN105812095A - Helicopter satellite communication Turbo code encoding method - Google Patents

Abstract

The invention relates to a helicopter satellite communication Turbo code encoding method. The method includes the following steps that: simulation comparison is performed on the bit error rates of Turbo codes at various input information positions under an occlusion condition, 6 input information positions with the maximum bit error rate and 6 input information positions with the minimum bit error rate are found out and are represented by Bmax and Bmin; the 6 high-error rate input information positions Bmax are replaced by known KB 010101 which is determined by a receiving side and a transmitting side; the KB information transmitting side only transmits generated check bits, and the check bits are transmitted after being modulated; since the receiving side knows the content of the KB, the KB can be restored from received code words which have passed through a channel, the weight of the KB is increased in decoding, and the weight of the KB is 200; and the position Q1 of check bits outputted by a first encoder in code words corresponding to the information positions Bmax and the position P0 of information bits in code words corresponding to the information positions Bmin are calculated out respectively, and the bit information in the Q1 is re transmitted and randomly assigned to the P0.

Description

A kind of helicopter satellite communication Turbo code coded method

Technical field

The present invention relates to a kind of helicopter satellite communication Turbo code coded method, belong to satellite communication coding techniques field.

Background technology

Communication (air-ground, the air-sea) mode of traditional helicopter and GCS Ground Communication System mainly has ultra short wave communication and microwave communication, and its communication distance is generally tens kilometers, causes that the mobility of helicopter and applied environment have been affected by serious restriction.Helicopter satellite communication system can provide the seamless coverage of relative broad range with relatively low cost, and is not limited by geographical conditions, has thoroughly broken away from the dependence to ground communication condition.Helicopter satellite communication signals can be subject to blocking of helicopter rotor, produces serious periodicity decline.Therefore select a kind of suitable channel decoding method, just seem necessary.

Turbo code is that professor C.Berrou of Britain communication university of France et al. proposes brand-new channel decoding algorithm on the international communication conference of 1993, is a kind of error control coding scheme close to Shannon capacity limit, close optimum error-correcting performance.Turbo code not only has uniqueness and excellent part in coding and decoding, and the thought of its iterative decoding also provides new thinking for the many difficult problems in solution communication, for instance iterative channel estimation and synchronization, and Turbo is balanced, Multiuser Detection and T-TCM etc..

The Turbo code of standard assumes that in code word, all bit energies are equal, but JHokfelt et al. have studied the method optimizing energy distribution under Low SNR, it was demonstrated that distributes more multi-energy to systematic bits during low signal-to-noise ratio and can improve decoding performance.Introduce Turbo code unequal loss protection concept; bit critical bit (CB in Turbo code information sequence, interference sensitivity is high is found out by simulation analysis; CrucialBits); and it is protected; the anti-interference making coding is improved; the method is by scanning for obtaining critical bit position to minimum weight code word, and the Realization of Simulation is relatively complicated.

Summary of the invention

The present invention seeks to; it is subject to the problem that lifting airscrew blocks for the lower satellite communication of over the horizon transmission; propose a kind of helicopter satellite communication Turbo code coded method, Turbo code critical bit can be protected also to be able to rotor blocks influence of fading correctly be translated when existing.Under the premise not dramatically increasing decoding complexity, reduce mistranslation code check, improve helicopter satellite communication system overall performance.

Technical scheme: helicopter satellite communication Turbo code coded method, comprises the steps:

Step one: compare by Turbo code bit error rate on each input information position under having circumstance of occlusion is carried out emulation, find out bit error rate the highest (i.e. critical bit) and minimum 6 input information positions respectively, use B_maxAnd B_minRepresent；

Step 2: 6 the high bit-error input information position B that will find_maxDetermine that known KB " 010101 " substitutes with receiving-transmitting sides, i.e. B_max=[010101], these positions are not re-used as information bit transmission information and use；

Step 3: known by step 2, KB=[010101], sends the code word after compound into Turbo interleaver and encoder is encoded, the KB then deleted in code word in systematic code field, KB information sender is only sent to the check bit of generation, be then passed through modulation and be transmitted；

Step 4: due to the content of the previously known KB of recipient, the reception code word after channel recovers KB in relevant position, invents the weights increasing KB when decoding, and weights take 200, calculate such as formula:

KB=200* [-11-11-11]

Step 5: calculate information position B respectively_maxThe position Q of the check bit of first encoder output in corresponding code word₁And B_minThe position P of the corresponding information bit in code word₀, then by Q₁In bit information retransmit and be assigned randomly to P₀Among these positions.

Here only critical bit is substituted by known bits, both can guarantee that critical bit position correctly translates, again because the proportion of whole information sequence is only small shared by the known bits added, thus the impact of code check is also only small.Secondly as the introducing of iteration and soft-decision algorithm, the power of KB is dispersed in other information bits, so just improves the decoding performance that helicopter satellite communication system is overall.

The present invention proposes critical bit unequal loss protection algorithm (CBUEP) based on helicopter satellite communication, and this algorithm mainly need to retransmit and be distributed in non-sensitive positions by critical bit to be protected, to ensure the correctness of decoding.

Beneficial effect: the present invention proposes a kind of helicopter satellite communication Turbo code coded method; propose critical bit unequal loss protection algorithm (CBUEP) based on helicopter satellite communication; need to retransmit and be distributed in non-sensitive positions by critical bit to be protected; correctly translate in decoding process thus ensure that Turbo code critical bit can not be blocked by lifting airscrew to affect; the method has the advantages such as anti-rotor blocks, little on the impact of encoding and decoding complexity, the Realization of Simulation is relatively simple, is effectively increased system error performance.

Accompanying drawing explanation

Fig. 1 is critical bit protection algorism schematic diagram provided by the invention.

Detailed description of the invention

Below in conjunction with accompanying drawing, the present invention will be further described.

Critical bit protection algorism provided by the invention is as shown in Figure 1.What mainly adopt is the Turbo code of 1/3 code check, and code word C is by the check bit Y of information bit X, first component coder coding output₁, information sequence interleaved after at the check bit Y of second component coder coding output₂Three parts are composited.

Calculate information position B respectively_maxThe position Q of the check bit of first encoder output in corresponding code word₁And B_minThe position P of the corresponding information bit in code word₀, then by Q₁In bit information retransmit and be assigned randomly to P₀Among these positions, cast out the low information bit of part sensitivity and protect the check bit of the information easily translating mistake.

Recipient is by P₀In bit information propose, then by P₀Zero setting, and by the bit information proposed and Q₁Correspondence position bit information phase adduction is assigned to Q₁, finally send into decoder for decoding.In figure illustrate: assume C2 C497 be B_maxThe check bit Q of first encoder output in corresponding code word₁Bit information, then position P₀With C2 C497 bit information insert (replacement).

Claims (1)

1. helicopter satellite communication Turbo code coded method, is characterized in that comprising the steps:

Step one: compare by Turbo code bit error rate on each input information position under having circumstance of occlusion is carried out emulation, find out 6 input information positions that bit error rate is high and minimum respectively, use B_maxAnd B_minRepresent；

Step 2: 6 the high bit-error input information position B that will find_maxDetermine that known KB substitutes with 010101 with receiving-transmitting sides, i.e. B_max=[010101], these positions are not re-used as information bit transmission information and use；

Step 3: known by step 2, KB=[010101], sends the code word after compound into Turbo interleaver and encoder is encoded, the KB then deleted in code word in systematic code field, KB information sender is only sent to the check bit of generation, be then passed through modulation and be transmitted；

Step 4: due to the content of the previously known KB of recipient, the reception code word after channel recovers KB in relevant position, invents the weights increasing KB when decoding, and weights take 200, calculate such as formula:

KB=200* [-11-11-11]

Step 5: calculate information position B respectively_maxThe position Q of the check bit of first encoder output in corresponding code word₁And B_minThe position P of the corresponding information bit in code word₀, then by Q₁In bit information retransmit and be assigned randomly to P₀Among these positions.