Backscatter-Aided Cooperative Transmission in Wireless-Powered Heterogeneous Networks

We propose backscatter-aided cooperative transmission for wireless-powered heterogeneous networks (WPHetNets). In WPHetNets, where various kinds of nodes such as high-power base station (e.g., TV tower and macro base station) and small-power access point (e.g., WiFi access point) coexist, we aim to increase transmission range and support fair communication through internet-of-things (IoT) device cooperation. For this, we first propose long-range bistatic backscatter (BB)-aided cooperative transmission with two-device cooperation where ambient backscatter (AB) enables short-range information exchange in sequential mode between devices nearby under energy neutral operation, termed 'Cooperation mode'. To ensure fairness between devices, we formulate common-throughput maximization problem where an algorithm for time allocation is presented. Compared with 'Non-cooperation mode' (i.e., no information exchange via AB) and active RF based cooperation schemes, the proposed scheme is shown to increase both the coverage and fairness between devices for battery-less IoT networks. We then generalize the architecture of backscatter-aided cooperative transmission with multiple-device cooperation where the information exchange is performed in sequential mode and parallel (broadcasting) mode. In the sequential mode, a graph-matching based suboptimal pairing algorithm is proposed whose validity is corroborated through comparison with a heuristic search based optimal pairing, and then we compare the two modes for multiple-device cooperation.