Feedback outage correlated with CQI and its impact on multiuser diversity in Rayleigh fading channels

This letter addresses a feedback outage when the channel condition of the feedback channel is correlated with that of the traffic channel the quality information of which is being carried by the feedback, and its impact on the multiuser diversity in flat Rayleigh fading channels. The correlation is described by the time delay as well as the frequency separation between the traffic and the feedback channel. The average capacity is provided in terms of the time and the frequency factor. With numerical investigations, we show that the capacity degradation due to the feedback outage is generally saturated at the great frequency separation approximately over 45 MHz (e.g., in present IS-95 cellular systems), within which it fluctuates depending on the feedback delay