Joint Active User Identification and Multiuser Detection in DS-CDMA Cellular Communication Network

In cellular communication network, users are allowed to enter or leave the network arbitrarily. Hence, the number, identities and transmitted data of active users vary with time and have considerable impacts on the receiver's performance. The so-called problem of active user identification, which consists of determining the number and identities of active users, is usually solved prior to the problem of multiuser detection which means detecting the data transmitted by active users. Traditional methods implement the two parts separately with a two-stage decoder. In this paper we propose a Maximum A posteriori Probability (MAP) based method, which uses BCJR algorithm to execute active user identification and multiuser detection jointly. Simulation results show that the proposed method outperforms previous methods in detecting the number and identities of active users and data transmitted by active users.