Research On Channel Coding And Modulation Based On 60GHz Communication System

The 60 GHz millimeter-wave communication system is a short range system with ultra-high speed rates. The frequency of 60 G has a strong ability of anti-inference and its bandwidth is for free. The superiority of 60 GHz communication becomes more outstanding by the congestion of low spectrum and the increasing demand of large data rates. The research of 60 GHz communication systems has profound significance with the development of technology.Since the propagation distance of millimeter-wave signal is short, the signal is less affected in Line of Sight(LOS) channel. In Non Line of Sight(NLOS) channel, the obstacles absorption effect of signal influences the propagation. The signal can be recovered from the effects of the channel by channel coding with error detection and correction capability. The channel coding of 60 GHz communication system is Low Density Parity Check(LDPC) code. LDPC code is an efficient error correcting code which parity check matrix is sparse. There is an outstanding compromise between the performance and implementation complexity when using LDPC code in a high transmission rates communication system of 60 GHz.Recently Spatial Modulation(SM) is proposed as a new Multiple-Input Multiple-Output(MIMO) technology, the innovation of SM is mapping bit information for indexes of transmitting antenna and information transmission is through space mapping. SM can efficiently avoid the problems of Inter-Channel Interference(ICI) and Inter-Antenna Synchronization(IAS). Therefore, in the 60 GHz communication system with high transmission rate, the research of SM has certain significance.In this paper, we launch the following research work on the channel coding and SM in 60 GHz communication system:Chapter 2 analyzes the encoding and decoding algorithms of two LDPC codes are researched. The performances in 60 GHz communication systems of two codes are discussed. One of the LDPC codes is from the IEEE 802.11 ad standard and the other code is constructed in 60 GHz project. Firstly, the structure of two codes is analyzed and the corresponding encoding and decoding algorithm is given. Secondly, the Bit Error Ratio(BER) performance of LDPC codes with different code rate and length are given in 60 GHz channel. The result indicates the two LDPC code can both restore 60 GHz signal in different channel even if the quality of channel is poor.In chapter 3, SM is applied to the frequency selective fading channels based on the conventional signal detecting algorithm. Firstly, we study the system model of SM in the multipath channel. By analyzing the propagation process of SM’s signal in multipath channel, the trellis of antenna and channel is constructed. Then the Viterbi algorithm is used for signal detection. Different schemes of SM are simulated and discussed at last. Simulation results show that the signal detection algorithm proposed in this paper can effectively detect the SM’s signal in multipath channel and with high transmission rate the spatial modulation outperforms the traditional modulation.In chapter 4, SM based on simple 60 GHz channel model is discussed. The channels of 60 GHz communication system are equivalent to simple single-path and multi-path channel by analyzing the channel features. The traditional and proposed signal detection algorithms in chapter 3 are exploited in the equivalent multi-path channel. In the two equivalent channels, the performance of SM and its related schemes is analyzed and compared with conventional modulation schemes. Simulation results show that the performance of SM in LOS channel is not ideal by the channel correlation. When increasing the number of receiving antennas, the SM performance can approach traditional modulation. In NLOS channel, compared with the traditional modulation, SM and its derivative technique has better performance with high transmission rate.In conclusion, we mainly discuss LDPC codes and spatial modulation based on 60 GHz communication system. Suggestions about drawbacks are offered and a brief discussion about what need to be improved is given.