Blind User Detection in Doubly Dispersive DS/CDMA Fading Channels

In this work, we consider the problem of detecting the presence of a new user in a direct-sequence/code-division-multiple-access (DS/CDMA) system with a doubly dispersive fading channel, and we propose a novel blind detection strategy that only requires knowledge of the spreading code of the user to be detected, but no prior information as to the time-varying channel impulse response and the structure of the multiaccess interference. The proposed detector has a bounded constant false alarm rate (CFAR) under the design assumptions while providing satisfactory detection performance even in the presence of strong cochannel interference and high user mobility.