Research Of High Reliability Non-Orthogonal Multiple Access Technology For Industrial Wireless Networks

Industrial wireless networks are important parts of the "Made in China 2025" strategy,and are typical application scenarios of the fifth generation(5G)mobile communication system.Power-Domain Non-Orthogonal Multiple(PD-NOMA)technology is one of the candidate media access technologies for 5G decoding with Successive Interference Cancellation(SIC).Although it can bring advantages such as low latency,its transmission reliability is depressed due to its larger self-interference.How to achieve a suitable trade-off between low latency and high reliability,that is,to ensure the highest reliability under the premise of guaranteed transmission delay,has been widely concerned.It is a feasible idea to improve the reliability of uplink transmissions through joint optimization of user scheduling and power allocation.Based on the 2-SIC receiver and the k-SIC receiver,which is more general,this paper mainly studies:(1)A PD-NOMA transmission reliability model based on SIC is established.Specifically,the uplink transmission reliability of a binary phase shift keying modulated NOMA system with multiple users and one sink is modeled,and a closed-form expression of transmission reliability,which is based on the average bit error rate of multiple users,is therefore presented creatively.(2)Based on the reliability model in(1),it is proved that the original problem of joint optimization of user scheduling and power allocation can be decomposed into a two-stage optimization problem: namely,the multi-slot user scheduling sub-problem and the single-slot power allocation sub-problem,and the decomposition greatly reduces the complexity of problem solving.(3)Based on the closed-form expression in(1),for the single-slot power allocation sub-problem,an optimal power allocation strategy is designed.(4)Based on the closed-form expression in(1),for the multi-slot user scheduling sub-problem,an optimal user grouping algorithm is designed.(5)Based on the theoretic foundation brought by step(2),and the algorithms designed in step(3)and step(4),a reliability-optimal algorithm with guaranteed delay is designed with complexity O(nlogn)of 2-SIC based and 3O(n)of k-SIC based.The performance evaluations show that the reliability-optimal algorithm can achieve the highest transmission reliability while keeping the guaranteed transmission delay.Besides,the transmission reliability increases exponentially with the decreasing in real-time performance requirements,which means that the transmission reliability will increase rapidly once the transmission delay requirements is relaxed slightly.