Wireless-Powered Communications: Performance Analysis and Optimization

• Published in: IEEE transactions on communications Vol. 63; no. 12; pp. 5178 - 5190
• Main Authors: Caijun Zhong, Xiaoming Chen, Zhaoyang Zhang, Karagiannidis, George K.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-12-2015; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antennas; Channels; Delay; Delays; Energy beamforming; Exact solutions; Fading; Fading channels; Interference; Mathematical analysis; Mathematical models; Metalworking industry; Multiple antennas; Optimization; Resource allocation; Throughput; Wide area networks; Wireless communication; Wireless powered communications; resource allocation; wireless-powered communications; multiple antennas; Energy beamforming
• ISSN: 0090-6778; 1558-0857
• DOI: 10.1109/TCOMM.2015.2488640

This paper investigates the average throughput of a wireless-powered communications system, where an energy constrained source, powered by a dedicated power beacon (PB), communicates with a destination. It is assumed that the PB is capable of performing channel estimation, digital beamforming, and spectrum sensing as a communication device. Considering a time-splitting approach, the source first harvests energy from the PB equipped with multiple antennas, and then transmits information to the destination. Assuming Nakagami-m fading channels, analytical expressions for the average throughput are derived for two different transmission modes, namely, delay tolerant and delay intolerant. In addition, closed-form solutions for the optimal time split, which maximize the average throughput are obtained in some special cases, i.e., high-transmit power regime and large number of antennas. Finally, the impact of cochannel interference is studied. Numerical and simulation results have shown that increasing the number of transmit antennas at the PB is an effective tool to improve the average throughput and the interference can be potentially exploited to enhance the average throughput, since it can be utilized as an extra source of energy. Also, the impact of fading severity level of the energy transfer link on the average throughput is not significant, especially if the number of PB antennas is large. Finally, it is observed that the source position has a great impact on the average throughput.