Improved Cooperative CDMA Using Blind Adaptive Interference Cancellation

In this paper, we introduce blind adaptive interference cancellation for a practical uplink CDMA effected by multiple access interference (MAI) in cooperative communications systems scenario. During the collaboration phase, each paired users exchange their data to communicate with the base-station by using their own and pairing users' channels to achieve the spatial diversity. The base-station performs ranking of users' power and detects the strongest using the successive interference cancellation (SIC) principle to gradually remove MAI from the desired signals. The proposed scheme uses an improved SIC which performs adaptive despreading to form better estimates of users' data and then uses blind MAI estimation and cancellation by making use of the despreader weights to minimize the residual MAI. Simulation results show that the scheme achieves better diversity gain and allows much higher number of users to share the same bandwidth compared with conventional cooperative schemes.