Optimal algorithms for scheduling uplink users transmissions in CDMA systems [articol]

Abstract

Early work on capacity analysis of CDMA systems promise a large increase in cellular capacity when compared to other multiple-access techniques. The uplink capacity is shown to be limited by the outage probability. In this work, we consider the problem of optimal scheduling of uplink user transmissions in a single CDMA cell. We assume that the system operates in a TD/CDMA manner, with time-slotted scheduling of transmissions, assisted by periodic feedback of channel and/or congestion information through control channels. The major observation arising from our analysis is that it is advantageous on the uplink to schedule “strong” users one-at-a-time, and “weak” users in larger groups. This contrasts with the downlink where one-at-a-time transmission for all users has shown to be the preferred mode in much previous work.