This letter studies the application of backscatter communications (BackCom) assisted non-orthogonal multiple access (BAC-NOMA) to the envisioned sixth-generation (6G) ultra-massive machine type communications (umMTC). In particular, the proposed BAC-NOMA transmission scheme can realize simultaneous energy and spectrum cooperation between uplink and downlink users, which is important to support massive connectivity and stringent energy constraints in umMTC. Furthermore, a resource allocation problem for maximizing the uplink throughput and suppressing the interference between downlink and uplink transmission is formulated as an optimization problem and the corresponding optimal resource allocation policy is obtained. Computer simulations are provided to demonstrate the superior performance of BAC-NOMA.

翻译：这封信研究了对设想的第六代(6G)超大型机器型通信(超大型)采用反向散射通信(BackCom)的辅助非横向多重接入(BAC-NOMA),特别是拟议的BAC-NOMA传输计划可以实现上行和下行用户之间的同步能源和频谱合作,这对于支持超大型连通和超下行用户的严格能源限制十分重要。 此外,在最大程度实现上端连通和抑制下端连通和上端联传输之间的干扰方面存在资源分配问题,这是一个优化问题,并获得了相应的最佳资源分配政策,提供了计算机模拟,以展示BAC-NOMA的优异性表现。