Joint Optimal Subcarrier and Power Allocation for Wireless Cooperative Networks Over OFDM Fading Channels

In this paper, we consider the adaptive subcarrier assignment and fair power control strategy that minimize a cost function of average relay powers for multiuser wireless orthogonal frequency-division multiplexing (OFDM) networks, where a set of relays assists communication between sources and destinations with an amplify-and-forward strategy. Using a class of β-fair cost functions to balance the tradeoff between energy efficiency and fairness, joint optimal subcarrier and power-allocation schemes at the relays are derived in a quasi-closed form. In addition, we develop novel stochastic algorithms capable of dynamically learning the intended wireless channels on the fly to approach the optimal policy. Numerical results are provided to evaluate the proposed schemes for multiuser OFDM relay networks over block-fading channels.