Optimal and suboptimal resource allocations for multi-hop MIMO-OFDMA networks

This paper considers the problem of resource allocation for weighted sum rate maximization in a decode-and-forward (DF) based multi-hop MIMO-OFDMA systems. The optimal solution of joint subcarrier assignment (user and relay selections) and power allocation is obtained by solving a dual problem. We derive the necessary conditions for the optimal power allocation and propose a suboptimal algorithm with a closed-form based general power allocation solution. This suboptimal algorithm, as numerical results verify that, suffers from minor performance loss against that achievable by the optimal solution when SNR is high. It is observed that the corresponding closed-form power allocation yields 8% performance gain when compared with the equal power allocation.