Wireless powered backscatter-aided cooperative communication scheme for IoT

This paper demonstrates that the cooperation between two types of user equipment-backscatter devices and radio frequency energy harvesting devices-leads to increased weighted sum throughput when the reflected signal from a backscatter device is leveraged. In our system model, a hybrid access point acts as a source of energy as well as a sink for both the devices by first emitting an energy signal to both the devices over the downlink and then receiving the information signal transmitted by those devices over the uplink in the consecutive slots. By recognizing the dependency of the weighted sum throughput on the antenna gain values and the duration over which the energy signal is transmitted, we formulate an optimization problem to maximize the weighted sum throughput over a joint set of these two system variables. To solve this optimization problem, which is non-convex due to the chosen objective function, we present an iterative algorithm, based on the coordinate descent method along with its convergence analysis. We even develop a low-complexity solution technique that provides a sub-optimal solution to the same optimization problem. The simulation results illustrate the superiority of our proposed scheme by presenting its comparison with two other schemes and a benchmark scheme when the system's key parameters such as the transmit power, the distance between the devices, etc. are varied.