A resource scheduling scheme based on feed-back for SCMA grant-free uplink transmission

Sparse code multiple access (SCMA) is a novel air-interface technology proposed for the fifth generation (5G) mobile communication system. SCMA aims for energy saving, low latency and massive connectivity to satisfy 5G demand. SCMA grant-free transmission has been proposed to ensure low latency and massive connectivity. In this paper, the connection and packets drop performance of SCMA and OFDMA through a pre-existing resource scheduling scheme for uplink grant-free transmission are analyzed. When UEs are erratically required to transmit a great number of packets continuously, the packet loss rate is too high, which is a problem of the pre-existing scheme. Hence, a resource scheduling scheme based on feed-back for uplink SCMA grant-free transmission is proposed to solve this problem. The simulation results demonstrate that SCMA has a lower packet loss rate than OFDMA with the same resources and UEs. In the heavy traffic scenario, the proposed resource scheduling scheme based on feed-back has a better packet drop performance than the pre-existing scheme.