Asymptotic Analysis of Downlink OFDMA Capacity
The authors consider asymptotic performance of a downlink OFDMA system as the number of users and sub-channels increase. Specifically, they study the asymptotic growth in the weighted sum capacity, where each user is assigned a weight to reflect its quality of service. They begin by considering a limited feedback scheme, where each user is pre-assigned a threshold and feeds back one bit per sub-channel to indicate whether the channel gain is above the threshold or not. If more than one user requests the same sub-channel, the base station picks the user with the largest weight to transmit. In earlier work they analyzed such a scheme when each user has i.i.d. Rayleigh fading on each sub-channel.