Novel Multiuser Interference Canceling Scheme in TDD CDMA Systems
Ji Wang · Dianzi xuebao · 2000
Conventional multiuser interference canceling is always done in the uplink.In this paper,a novel multiuser processing scheme used in the downlink of TDD CDMA (Time division dupler code division multiple access) systems is proposed.In TDD CDMA systems,the downlink multipath channel parameter can be estimated from the uplink.In this paper,we use the instantaneous channel parameter to calculate the spreading spectrum code and despreading code for different users.We present the optimal criterion of the generation of the spreading code and despreading code,so that the multiple access interference can be greatly reduced.Numerical results show that our scheme can geratly increase the signal to interference and noise ratio,compared with conventional CDMA systems which use Gold sequence as the spreading code.