Research Of Interference Cancellation Based On Orthogonal Gmsk Communication System

With the continuous development of information society and communication system continuing to increase uesr capacity, their contradiction with the limited spectrum resources has become increasingly prominent, which is the new obstacle that restricts the development of various types of communication technology. In order to solve the problem of scarce spectrum resources, the concept of frequency reuse has come out. It does to some extent alleviate the conflict between the system capacity with limited spectrum resources, but it also brings new issues of co-channel intertference. For this reason, people also have put forward various effective methods to solve co-channel interference. This paper that is based on orthogonal GMSK communication system and radio simulation system, studied the transmission of two co-channel signals which are also orthogonal. The receiver has used a varity of interference cancellation algorithms to realize the demodulation of two co-channel orthogonal signals. The whole orthogonal GMSK communication system has greatly improved the transmission rate and spectral efficiency compared with the original single-channel GMSK system.Firstly, the basic concepts of GMSK modulation and single antenna interference cancellation and the basic situations of the development of them are described briefly.Secondly, various modulation parameters of orthogonal GMSK communication system, specific transmission and the structure and principles of the receiver are discussed in detail.Then, this paper studied the algorithms of interference cancellation including IRC (Interference Rejection Combining) algorithm, VAR (Vector Valued Autoregressive)model algorithm and multiuser detection algorithm including JMLSE(Joint Maximum Likelihood Sequence Estimation) and JDDFSE(Joint Delayed Decision-feedback Sequence Estimation). This paper also analyzed and compared the performance of those algorithms based on the different channel parameters of the current orthogonal GMSK communication system.Finally, parallel interference cancellation algorithm is put forward. Combined with previous study of several algorithms, this paper gives the simulation results of the performance of PIC algorithm and the optimal scheme for the receiver of orthogonal GMSK communication system.