Title: Towards a Real-time Wireless Powered Communication Network
Student: Zelin Yun
Major Advisor: Dr. Song Han
Associate Advisors: Dr. Shengli Zhou, Dr. Bing Wang
Review Committee Members: Dr. Suining He, Dr. Minmei Wang
Date/Time: Friday, March 31, 2023, 11:30 am
Location: WebEx Online
Meeting number: 2621 662 2562
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Wireless powered communication networks (WPCNs) have the great potential to reduce the battery replacement frequency and the network maintenance cost. A typical WPCN consists of two major components, the WPC user devices that are powered by harvesting energy from wireless signals, and a hybrid access point (HAP) that provides the wireless power to and collects data from the WPC user devices. Existing works on WPCNs mainly focused on the development of theoretical models and methods to analyze WPCN performance. However, those works made strong assumptions on the models which cannot be directly applied in real system implementation.
To fill this gap, in this dissertation we present the design, implementation and evaluation of a real-time wireless powered communication network, namely RT-WPCN. To address the doubly near-far problem commonly observed in WPCN, we propose a multi-hop time division multiple access (TDMA)-based data link layer (DLL) design and apply the beamforming technology on the HAP to improve the charging efficiency. Based on the system design, we develop a practical charging model and formulate the minimal user throughput maximization problem for multi-hop RT-WPCN and provide our solutions. The performance of the implemented RT-WPCN system and proposed scheduling algorithms are evaluated through extensive simulation-based and testbed experiments. Another key contribution of our RT-WPCN design is to improve the throughput of the WPC user device. We propose an advanced receiver design for the wireless communications between the WPC user device and the HAP. The advanced receiver design can achieve significantly better packet delivery ratio than the commercial off-the-shelf hardware so that the WPC user devices can use lower transmitting power while the HAP can still correctly receive the packets.
A disadvantage of the RT-WPCN design is that the coverage of the network is limited by the wireless charger since the HAP is stationary and the charging power attenuates along with the square of the charging distance. To address this issue, we further add mobile HAPs into the RT-WPCN system. Given that the information exchange among the mobile HAPs requires ultra-low-latency communications to enable the HAPs to charge the user devices and collect data in real time, we further propose the software-defined radio (SDR)-based RT-WiFi solution to serve as the communication fabric among the mobile HAPs and provide full-stack configurability. We present the overall system architecture of SRT-WiFi and discuss its key functions which can achieve better timing performance and solve the queue management and rate adaptation issues compared to existing solutions. To achieve effective network management with rate adaptation in multi-cluster SRT-WiFi, a novel scheduling problem is formulated, and an effective algorithm is proposed to solve the problem. A multi-cluster SRT-WiFi testbed is also developed to validate the design, and extensive experiments are performed to evaluate the performance at both device and system levels.