Energy-Efficient Resource Allocation for Short Packet Transmission in MISO Multicarrier NOMA

In this article, we investigate energy efficiency (EE) maximization of short packet transmission (SPT) in a downlink multiple-input single-output (MISO) multi-carrier non-orthogonal multiple access (MC-NOMA) communication system. We use the ratio of the effective throughput to the power as a performance metric to formulate a non-convex mixed-integer nonlinear programming (MINLP) problem. Then, a low-complexity three-step optimization framework is proposed for MINLP optimization. Under a given maximum transmit power and channel blocklength of each subcarrier, a block coordinate descent (BCD) based method is proposed to jointly optimize the power allocation coefficient, transmission rate, and transmit power within a single subcarrier. Then, we transform the subcarrier allocation problem into a weighted bipartite graph matching problem and obtain the optimal subcarrier allocation scheme using the Kuhn-Munkres (KM) algorithm. Finally, a dynamic programming (DP) method is proposed to obtain the optimal channel blocklength allocation scheme. The simulation results validate the effectiveness of the proposed three-step optimization framework and indicate that the MC-NOMA system achieves higher EE and higher effective throughput than the orthogonal frequency-division multiple access (OFDMA) system in SPT.

I. Introduction

The upcoming sixth-generation (6G) cellular network has high performance requirements, e.g., a short end-to-end (E2E) delay, high energy efficiency (EE), and large system capacity [1], [2]. A short frame structure and short packet transmission (SPT) are typically used in ultra-reliable and low-latency communications (URLLC) to reduce the E2E delay. Thus, SPT has attracted the attention of many researchers [3], [4]. In addition, non-orthogonal multiple access (NOMA) technology enables the transmission of multiple users on a resource block (RB) simultaneously, significantly improving the system capacity and reducing the delay [5], [6]. The combination of SPT and NOMA is a desirable approach that is expected to meet the key performance indicators (KPI) of 6G.