Joint Uplink and Downlink Coverage Analysis of Cellular-based RF-powered IoT Network

摘要

Ambient radio frequency (RF) energy harvesting has emerged as a promisingsolution for powering small devices and sensors in massive Internet of Things(IoT) ecosystem due to its ubiquity and cost efficiency. In this paper, westudy joint uplink and downlink coverage of cellular-based ambient RF energyharvesting IoT where the cellular network is assumed to be the only source ofRF energy. We consider a time division-based approach for power and informationtransmission where each time-slot is partitioned into three sub-slots: (i)charging sub-slot during which the cellular base stations (BSs) act as RFchargers for the IoT devices, which then use the energy harvested in thissub-slot for information transmission and/or reception during the remaining twosub-slots, (ii) downlink sub-slot during which the IoT device receivesinformation from the associated BS, and (iii) uplink sub-slot during which theIoT device transmits information to the associated BS. For this setup, wecharacterize the joint coverage probability, which is the joint probability ofthe events that the typical device harvests sufficient energy in the given timeslot and is under both uplink and downlink signal-to-interference-plus-noiseratio (SINR) coverage with respect to its associated BS. This metricsignificantly generalizes the prior art on energy harvesting communications,which usually focused on downlink or uplink coverage separately. The keytechnical challenge is in handling the correlation between the amount of energyharvested in the charging sub-slot and the information signal quality (SINR) inthe downlink and uplink sub-slots. Dominant BS-based approach is developed toderive tight approximation for this joint coverage probability. Several systemdesign insights including comparison with regularly powered IoT network andthroughput-optimal slot partitioning are also provided.