Research On Adaptive Equalize Algorithm In MC-CDMA

In Mobile Communications, ISI is always one of the main factors which affect the communication quality. MC-CDMA uses the Cycle Prefix technology of OFDM to reduce ISI, but cycle Prefix bring the low bandwidth utilization rate. In order not to use Cycle Prefix, it need to use equalizer to reduce ISI. Also in mobile wireless communications, the channel changes with time, simple linear equalizer is difficult to meet the system requirements, so we should use the adaptive equalizer which has strong ability to adapt to changes.Firstly, this paper introduce the background and the significance of this research, and then introduce the principle of MC-CDMA system, expounded the basic concept of equalize. Then study several algorithms of adaptive equalizer, including traditional LMS algorithm, RLS algorithm, blind equalization CMA. The traditional LMS algorithm is relatively simple and easy to achieve works, but in convergence rate and convergence precision adjustment step on the request is contradictory, variable step LMS algorithm is able to effectively solve this contradictory. This paper raised a improved variable step LMS adaptive equalization algorithms. Through the MATLAB simulations, this paper proved this new algorithm has improved convergence properties. At last, simulate the MC-CDMA system use this improved variable step LMS algorithm, the conclusion shown improved variable step LMS algorithm raised the bit error rate performance of MC-CDMA system.