Optimization of Resource Allocation in Relay Assisted Multi-user SCMA Uplink Network

In this paper, we study the optimization of resource allocation in dual-hop relay assisted multi-user sparse code multiple access (SCMA) uplink network. Based on this, an uplink transmission strategy with the combination of SCMA and orthogonal frequency division multiple access (OFDMA) is considered, where the user equipments (UEs) transmit information to a relay station (RS) via SCMA codebook assignment and then the RS amplifies and forwards the information to the base station (BS) through OFDMA subcarrier pairing. Under the individual power constraints on both UEs and RS, a problem of maximizing the weighted sum-rate of the system by joint power allocation, codebook assignment and subcarrier pairing is conceived. To tackle the complex issue, a twostep wise algorithm is proposed. Alternatively, we find the optimal power and codebook allocation based on the special feature of SCMA codebook, and then obtain the solution to subcarrier pairing with a new criteria for each possible subcarrier pair. Numerical results verify the effectiveness of the proposed algorithm in both weighted sum-rate and energy efficiency (EE).