自适应算法在DSSS信号分集接收中的应用

Application of adaptive algorithm in DSSS signal diversity reception

分集接收技术由于能够获得分集增益,可提高多径信号的接收质量,因此在直接序列扩频系统中被广泛采用。常用的信号分集合并方法主要有选择性合并、等增益合并和最大比合并三种,其中最大比合并效果最佳,但需要准确地计算每路信号的信噪比,而采用自适应算法有效解决了准确计算信噪比的问题。因此,提出一种将RLS自适应算法与多径信号分集接收相结合的方法,它首先将接收到的多径信号分离为多路不同延时的信号,然后应用RLS自适应算法根据最小方差准则计算每一路信号的加权系数,通过对加权系数的更新获得最大分集增益,通过对不同的信号合并方式在多径信道下的性能进行仿真比较可知,采用RLS自适应算法的信号合并方式取得的性能最好。

Since diversity reception technology can obtain diversity gain,and improve the reception quality of multi？path signal,it has been widely used in direct sequence spread spectrum（DSSS）system. The general combining methods of signal di？versity include selective combining（SC）,equal gain combining（EGC）and maximal ratio combining（MRC）mainly. The MRC method has the best effect,and it is necessary to calculate SNR of each path signal precisely. The problem of calculation accurate SNR was solved by using adaptive algorithm effectively. The method of combining RLS adaptive algorithm with multi？path signal diversity reception is presented. The received multi？path signal is separated into different delayed signals by the method,then the weighting coefficient of each path signal is calculated according to the minimum variance criterion by using RLS adaptive algorithm, and the maximum diversity gain is obtained by updating the weighting coefficient. The performances of different signal combining ways under multi？path channels were simulated and compared,and it shows that the signal combining way of adopting RLS adap？tive algorithm gets the best performance.