Energy efficient short-packet downlink transmission with non-orthogonal multiple access

Abstract

Non-orthogonal multiple access (NOMA) and short-packet transmission are two critical techniques to fulfill the low latency demands by the emerging Internet of Things (IoT). Recent work disclosed that, in the NOMA based short-packet downlink transmission system, transmission rate control and power allocation can be utilized to maximize the effective throughput of the near user for the given far user effective throughput. For the sake of the energy sustainability, in this paper we focus on the energy efficient NOMA based short-packet downlink transmission design. Given the desired target effective transmission throughput requirements by two NOMA users, we formulate the energy consumption minimization problem to derive the least required energy consumption for the requested effective transmission throughput performance. And our analysis reveals some insights into the energy efficient NOMA-based short packet transmission design. Firstly, when the sum of the requested effective throughput by two users in the NOMA based downlink short packet transmission system is fixed, the least required transmit power is fixed as well; Secondly, our analysis discloses that, there exists such a region, in which the least required power allocated to the user closer to the AP will be primarily dependent on its requested effective throughput and its channel conditions; Finally, it is unveiled that, selecting the user that is closer to the AP with larger effective transmission throughput requirement is more recommended to realize energy efficient NOMA based short-packet downlink transmission system.