Optimum Power Scheduling for CDMA Access Channels∗

We consider the system access problem for CDMA networks where the access channels are nonorthogonal to the traffic channels. In such systems, the accessing user can degrade the performance of existing users by introducing extra interference. We study how transmit power should be varied with each successive access attempt so that the linear combination of average power expended and the average delay experienced by the accessing user is minimized. The harm caused by the accessing user to the existing communication links is also considered. We find that for all cost functions we consider, the absence of an access deadline implies that each access attempt should be made at some constant power. With an imposed access deadline we find that the optimum sequence of transmit powers can be determined recursively.