A Spectral and Energy Efficiency of Adaptive Modulation (AM) with Power Control in Wireless Sensor Network

Abstract

This paper presents a combination of power control and adaptive modulation performance in wireless sensor networks (WSN). WSN comprised numerous smart and small sensor nodes with limited power, memory, and processing. Furthermore, there is an impairment wireless channel between the sensor node and the coordinator node. Energy and spectral efficiency are essential issues in WSN. These two targets can be reached by applying a combination of power control and adaptive modulation. This work proposes a power control system to determine the modulation level through feedback SNR value of instantaneous wireless channel condition. The modulation level continuously changed based on the wireless channel condition. This adaptive modulation increases spectral efficiency. A better channel condition will drive to switch into a higher modulation level and vice versa. The result shows that the existence of power control can increase by about 9% of spectral efficiency than a system without power control. The system without power control just has a 91 % of selection probability, while the system equipped with power control creates a 100 % selection probability at the same of modulation level (16 QAM). Besides, combining power control with adaptive modulation also adjusts transmitting power at sensor nodes so that the effective use of transmitting power at the sensor node can be achieved. Combining power control and adaptive modulation can decrease the power consumption, enlarge the spectral efficiency with specific target bit error rate (BER), reduce the interference level, and significantly improve the WSN system performance.