Multi-modulus Blind Equalization Algorithm Based On Decision Feedback System

For mobile wireless communications systems, high utilization of multi-modulus signals used more and more frequently. Due to the different modulus values, as for multi-modulus signals, the cost function for basic blind equalization algorithms can not effective convergence, making the equalization is not ideal. In order to overcome the multi-modulus signal equalization algorithms do not effective convergence and inter-symbol interference. This paper basis on the previous studies to study the decision feedback equalization structural performance based on multi-modulus, by using decision feedback equalization structural performance, the inter-symbol interference of the received signal is can be reduced further.It combined modulus decision method, point decision method, the pre-coding technique, space-time coding technique, cooperative diversity, generalized multi-modulus algorithm and a series of tools. The main work of this paper includes the following sections:(1) Based on the modulus decision method and which the variable leakage can accurately track time-varying signals, proposed a multi-modulus blind equalization algorithm based on modified modulus decision, the simulation results show that this algorithm compared with the traditional modulus decision method, the convergence faster and the steady-state error is smaller. Second, base on the point decision method and which the cost function can be adjusted modulus value weighted multi-modulus algorithm, proposed a multi-modulus blind equalization algorithm based on point decision method, simulation results show that compared with the traditional multi-modulus blind equalization algorithm, steady-state error of the new algorithm are smaller, the signal is better balanced.(2)The pre-coding technique and combined with semi-blind equalization algorithm, proposed a multi-modulus semi-blind equalization algorithm based on pre-coding, the simulation results show that this algorithm computation complexity significantly reduced, and the convergence speed is increased. Second, the pre-coding technique combined with the space-time coding technique, and using cooperative diversity, proposed a pre-coding and space-time collaborative coding blind equalization algorithms, the results show that this algorithm can effectively improve the system bit error rate and the convergence faster.(3)The technique of carrierless amplitude/phase(CAP) signal characteristics, multi-modulus blind equalization algorithm is researched. Using the generalized multi-modulus blind equalization algorithm based on CAP, it can effectively equalization dense signal, the algorithm makes the dense signal more compact convergence with good results. Second, use of the multi-mode signals(QAM-CAP) based on generalized multi-modulus algorithm, proposed a multi-modulus generalized decision feedback blind equalization algorithm based on the multi-mode signals, the results show that this algorithm convergence faster, and it suit for the multi-mode signals.