A joint multiple access scheme for uplink channels of CDMA systems

With the development of the communication industry, it is necessary to improve the capacity of CDMA systems. Some prominent approaches such as power control and smart antennas, have been proposed to improve the capacity of the CDMA system. In this paper, we present a joint multiple access scheme for uplink channels. The scheme is based on the code division multiple access scheme and spatial division multiple access scheme. In this scheme, the common spreading codes can be assigned to different mobile stations, so the number of users can be larger. The MMSE multiuser detector is used to detect signals that are spread by the same spreading code. In this paper, we also present an algorithm for the spreading codes assignment