Research On Harq Technique And Its Application In 1xev-do

On the mobile communication systems, the effects of multi-path fading and Doppler shift may seriously worsen the performance, and may cause the co-existence of random errors and burst errors. Hybrid ARQ (ARQ) technology is the combination of FEC and ARQ. This kind of system has not only the ability of error correction, but also the ability of detecting errors which can not be corrected. The main problems of HARQ are as follows:(1)Weight estimation algorithm is complicated whereas simplified algorithm is focused on AWGN channel, thus equal weighted combining is used which may lead to bad higher BER;(2)Usage of Turbo LLR is insufficient (3) Techniques of RC-LDPC conformation are not systematical. Aimed at the problems, the main works are as follows:Basic principles of traditional ARQ and all kinds of HARQ schemes are introduced, the paper discusses the main combining technologies of HARQ, and the performance of three kinds of HARQ is analyzed and simulated.Second, a new weight estimation algorithm based on received sequence in Rayleigh fading channel is proposed. A formula of SNR and amplitude is derived based on their relationship and the amplitude fading factor's probability density function the SNR would be used in Chase combining. Simulation results show its good performance of the new algorithm.Third, the paper proposes two novel algorithms in HARQ system, aiming at the insufficient usage of LLR. The LLR-Turbo stores faulty frame's LLR and uses it in combined frame to improve BER performance; CRC-LVR operates CRC firstly, if it fails, LVR check would be done, and its purpose is to lower decoding postpone, Simulation shows new algorithms are effective.Fourth, a kind of RC-LDPC conformation algorithm is proposed. This algorithm uses Gaussian approximation theory and Differential Evolution to search optimized degree distribution of irregular LDPC. And weight increasing parity check matrix is designed by PEG, then sequential punctures the matrix from smallest degree. Simulation results indicate conformation algorithm can achieve high performance, and sequential puncturing does not need to transfer check matrix.Finally, the HARQ system and weight estimation algorithm in Rayleigh channels is realized based on discussion of parameter configuration of TCP2 on DSP. And performance of Turbo decoding and HARQ is performed using TCP2. Emulation indicates TCP2 can fulfill the system performance requirement, the good performance of HARQ and the efficiency of the weight estimation algorithm in Rayleigh channels.