Joint WiFi Offloading and Resource Allocation for RF-Powered Wireless Networks Assisted by Ambient Backscatter

Abstract

We consider the problem of joint dynamic WiFi offloading and resource allocation for radio frequency (RF) powered wireless systems assisted by ambient backscatter, where a cellular base station (BS), a WiFi access point (AP), and multiple energy harvesting (EH) mobiles coexist. In the system, each mobile can dynamically access the cellular network or the WiFi network. When the mobile accesses the WiFi network, it can either adopt the ambient backscatter technique to backscatter ambient RF signals for data transfer (i.e., backscatter mode), or harvest energy from ambient RF signals and then utilize the harvested energy to transmit data (i.e., harvest-then-transmit (HTT) mode). When the mobile accesses the cellular network, it can only work in HTT mode, since the communication range of the ambient backscatter technique is limited nowadays which may not be suitable for data transmission in the cellular network. We first formulate two dynamic WiFi offloading and resource allocation problems for the cases without and with concurrent ambient backscatter (i.e., multiple mobiles can backscatter signals concurrently), aiming to minimize the weighted sum of energy consumption and data transmission time of all mobiles. Then, we develop an asymptotically optimal algorithm and a suboptimal algorithm for the cases without and with concurrent ambient backscatter, respectively. Finally, we validate and evaluate the performance of the proposed algorithms through numerical analyses.