Scheduling for the downlink in a CDMA network with imperfect channel estimation

In this paper, the problem of scheduling for a single user on the downlink of a WCDMA network is addressed. Expressions are derived for the optimal effective bit rates when adaptive modulation and coding (AMC) and multicode transmission are employed. Traffic load aware scheduling is also studied. Since the selection of the modulation and coding scheme (MCS) and the number of multicodes requires an estimation of the downlink SIR, it is important to assess the performance degradation due to estimation errors. It is shown that the effective bit rate is quite sensitive to SIR estimation errors. The sensitivity can be reduced by using a conservative estimate of the SIR.