Uplink Low-Power Scheduling for Delay-Bounded Industrial Wireless Networks Based on Imperfect Power-Domain NOMA

The power-domain non-orthogonal multiple access (NOMA) supports multiple packet reception, which can be leveraged for delay-bounded applications in industrial wireless networks (IWNs). However, it suffers from high power consumption on transmitters, which poses challenges for battery-powered wireless sensors. Given the delay bound for NOMA-based IWNs, the problem of minimizing aggregate power consumption of transmitters is therefore of great value. In a previous paper, we have addressed the problem under the model of perfect k-successive interference cancellation (k-SIC). In this paper, we study the same problem, however, under the model of imperfect k-SIC, which is more general in theory and more realistic in practice. For the existence of the optimal solution, we first present an explicit sufficient and necessary condition, which correlates three key parameters of network system together. We also propose a polynomial-time optimal algorithm with complexity O (n²). We further consider the same problem with discrete transmit powers, and present an approximation algorithm with complexity O (n²). Performance evaluation reveals that the delay bound requirement has tremendous impacts on both the aggregate power consumption and the maximum transmit power. Relative to the perfect SIC, the residual error caused by imperfect SIC results in extra power consumption of transmitters. However, the extra power consumption is gradually diminished with the further relaxation of the delay bound.