Throughput Maximization in Latency-Critical Downlink Communication with Hybrid BC-TDMA Strategy

In this paper, we focus on a downlink communication network providing latency-critical services to multiple sensor nodes (SNs). In order to promote the service capability, we adopt a hybrid broadcasting time-division multiple access (BCTDMA) strategy, in which different groups of SNs are assigned to independent time slots and in each time slot the grouped SNs are served in a data broadcasting manner. Taking the reliability constraints into account, we formulate an optimization problem maximizing the minimum achievable throughput among multiple SNs and aim at a joint SN grouping and blocklength allocation design based on the hybrid BC-TDMA strategy. To address the mix-integer nonconvex problem, we first characterize the optimal blocklength allocation for any given user grouping into a closed-form solution, based on which an iterative approach is proposed for efficiently extracting out the optimal grouping, such that the optimal joint solution can be analytically constructed. Finally, the proposed algorithm is validated via numerical results. The performance advantages of the hybrid strategy in throughput improvement are also highlighted, in comparison with benchmarks.