Adaptive Equalization Algorithm & Simulation Based On HF Channel

Adaptive technology can improve wireless communication quality and reduce the system bit error rate in the situation of not increasing the emissive power. So along with the requests that the wireless communication quality and the data output rate are enhanced daily by people, each kind of adaptive technology are more and more widespread applied. According to the actual communication system need, based on the existing channel equalization algorithm and HF channel, this article launches the adaptive equalization algorithm research, in order to find the most effective algorithm to fight with inter symbol interference.During in the parsing the two traditional adaptive channel balanced algorithms: LMS and RLS algorithm principles and the realization process foundation, this paper has pointed out the length of stride factor adjustment principle, in view of the LMS algorithm length of stride factor to the convergence rate and the stable request contradiction. Then present three kind of improvements algorithm: Normalized LMS algorithm, LMS/F, changes the length of stride normalization solution correlation algorithm. At the same time, in view of the RLS algorithm shortcomings that complexity is big and needs huge storage space, unstable, also when the Kalman gain vector approaches 0, the algorithm can not track to the channel change, this paper has enumerated the current existence some improvement algorithms. Then this paper gives the AFA equalization algorithm inferential reasoning in detail. This article simulation based on a wireless communications system platform.The platform's design mainly aims at the existence questions in the digital communication of inter symbol interference and noise. It contains three parts: the transmission, the channel and the receiver. The transmission and the receiver include: the channel coding module, in order to resist the noise effectively; the interweaver module, in the purpose dispersing the burst errors so that reduce the decoding module wrong slices; general equalizer module to simulate each kind of adaptive channel equalization algorithm and so on. At the same time, to make the equalization algorithm have more points and more effective, the channel part has been designed according to the HF channel transmission characteristic. Watterson model takes the reference, whose structure is simple and the complexity of operation order was small, also can effectively simulate the HF channel characteristic that changed along with time, with using the bad HF channel parameters which are produced by CCIR(Consultative Committee of International Radio). Under the wireless communication system platform and HF channel, the article has simulated traditional LMS and the RLS algorithm, as well as their respective improvement algorithms. Based on the simulation result, this paper has made the conclusion: AFA equalization algorithm is the best whose complexity is lower and tracking speed is faster.