Channel-Adaptive Resource Allocation for Cognitive OFDMA Radios Based on Limited-Rate Feedback

Tailored for the emerging class of cognitive radio networks comprising primary and secondary wireless users, the present paper deals with channel-adaptive allocation of sub-carriers, rate and power resources for Orthogonal Frequency-Division Multiple Access (OFDMA). Users rely on adaptive modulation and coding that they select in accordance with the limited-rate feedback they receive from the access point. The access point uses channel state information to maximize the weighted average sum-rate of the network while respecting rate and power constraints on the primary and secondary users. When the channel distribution is available, the optimal off-line allocation is obtained to benchmark performance.