Performance Analysis Of LDPC In Multi-antenna Wireless Communication Systems

With the rapid development of wireless communication technologies, the growingnumber of mobile subscribers and high-speed data services, capacity and reliability has beenthreatened in communication systems. However, it is always a major bottleneck to keepbalance between capacity and reliability of the system. As a chief anti-interference technology,channel coding is increasingly playing an important role in the field of digital transmission.The performances of LDPC coding permitted a very close approach to the Shannon limit,which greatly raise the level of information reliability. But the capacity of the system is farfrom a standard of transmitting. As an advanced technology in the future, distributed antennasystem is widely accepted by its wide coverage and large throughput network. The channelcoding which based on LDPC coding theorem is introduced into this system. The studymainly discuss the combined scheme of ZF pre-coding and LDPC codes. Simulations werealso conducted in DAS and multi-user MIMO downlinks.In the first place there is analysis of LDPC coding theory. A type of check matrixwithout cycles of length4and6which based on the LDPC construction principle wasproposed to realize the best decoding algorithm. In order to decrease the encoding complexityof the check matrix, a fast encoding scheme was introduced for QC-LDPC. Analysis andcomparison were carried out with the above strategies.Secondly, in addition to explain the basic theory of LDPC codes, channel coding andmulti-antenna systems were band together, any possible influential factors has long been theobject of intensive study. Multi-user MIMO downlinks were proposed on the basis of MIMOsystems, the reliability of MIMO downlinks were improved dramatically by using blockdiagonalization zero-forcing algorithm and LDPC coding.Finally, aiming at the poor quality of signal received by the mobile zone users, adistributed antenna systems and LDPC scheme was designed in this paper. In response to amobile station, ZF pre-coding methods are processed jointly to improve the BER performanceof the mobile station. The Belief Propagation (BP) algorithm was adopted to decode thereceived signal. Simulations verify analysis conclusions and show that, comparing with thetraditional liner pre-coding method with MIMO channels, this proposed project couldradically decrease the BER and improve the reliability of system. Furthermore, it has a broadscope on market of future mobile communication field.