The Research Of HARQ Technology Based On MIMO System

In order to accommodate the change of multimedia services and high-speed data users, the next generation mobile communication systems should provide much higher data transmission rate and reliability. But, with the limitations of the reliable wireless frequency resource and the time-varying nature of wireless channel, communication systems always have high code error ratio and low spectrum utilization. So, it is a main hot spot that how to provide both higher data transmission rate and reliability for the future wireless communications.MIMO technology can improve the data transfer rate effectively, and with the high spectral efficiency, the hybrid automatic retransmission request techniques combine FEC with automatic repeat request transmission technology can guarantee the reliable transmission of information data effectively. This paper proposed hybrid automatic retransmission request techniques in MIMO systems based on the basic validity and reliability of the two contradictory indicatorsFirstly, this paper studied mainly for hybrid automatic retransmission request techniques based on pre-encoded in multiple-input multiple-output system, pre-coding extends the sub-data streams to different antennas, whose aim is to get multiplexing gain and diversity gain. Incremental redundancy technology is proposed to instead of traditional Chase merger, which combine incremental redundancy transmission is mainly incremental redundancy code word, to increase the probability of correct decoding and increase the data throughput. Through MATLAB simulation analysis the bit error rate and information rate using the traditional program and incremental redundancy scheme, which proved that adopt incremental redundancy scheme can bring the system gain.Secondly, the diversity multiplexing system is extended to the MIMO-ARQ. The results show that multiple-input multiple-output system can not only provide diversity to provide spatial multiplexing, and there is some basic trade-offs between the two gain. Adding delay to the system, and we set a different numbers of retransmission, simulation and analysis the multiplexing gain on the conditions of the different retransmission diversity gain diversity gain coefficient of multiplexing gain. The result show that, automatic retransmission request delay can make big change happen to diversity gain.Finally, the MIMO system proposed using antenna permutation in retransmission HARQ technique, Permutation technology can reduce the correlation of antenna wireless fading channel and improve system performance effectively. Simulation the practical using antenna permutation in different fading channel, low-speed mobile environment which use space diversity gain can make up the shortcomings of the time coherent channel diversity gain is not obvious, but the anti-frequency selective relatively is poor.