: To improve downlink packet throughput, the base schedules a mobile when its signal to interference ratio is higher than on average. The mobiles measure downlink pilots from the serving and interfering basestations, calculating the SIR, and feeding back their achievable downlink rates. We examine the prediction of the signal to interference ratio by the mobile. Both signal and interference are modeled as auto-regressive (AR) stochastic processes. We derive the density function of the conditional SIR, in order for the mobile to determine the backoff margin required for a percentage of packets to be decoded successfully.