Reliability-Oriented Resource Allocation in Short-Packet Backscatter Communications

In this paper, we investigate a short-packet backscatter communication (BackCom) network, where multiple Internet of Things (IoT) nodes (INs) subsequently backscatter their short-packet data to the information receiver via BackCom. In order to improve the reliability of the investigated network, we formulate an optimization problem to minimize the maximum error probability (EP) among all INs by jointly optimizing the transmit power (TP) of the dedicated energy source (ES), the short-packet blocklength and power reflection coefficient (PRC) at each IN. The problem is formulated as a mixed-integer non-linear programming problem. To tackle it, we first derive the close-form expressions for both the optimal TP at the ES and the optimal PRC at each IN, resulting in two subproblems where the optimal TP and PRC are utilized. Then the optimal solution to the original problem (OP) corresponds to that of the subproblem with the lower EP at the worst IN. After replacing integer variables with continuous ones, the convexities of the two subproblems are demonstrated. Consequently, the solution to the OP can be achieved by addressing the two subproblems via convex tools and utilizing an integer conversion method. Simulation results show the superiority of the proposed scheme in terms of the EP by comparing with several benchmark schemes.

I. Introduction

The realization of the Internet of Everything hinges upon the integration of ultra-large scale Internet of Things (IoT) nodes (INs), which are anticipated to be interconnected and function cooperatively. However, the constrained battery lifespan inherent in each IN presents a formidable obstacle to realizing this vision. One particularly promising solution is backscatter communication (BackCom), which enables INs to not only modulate their information onto existing radio frequency (RF) signals for information transmission, but also harvest energy from these RF signals [1], [2]. Compared to existing wireless powered communication (WPC), BackCom functions as a passive communication paradigm, eliminating the requirement for carrier generation and the utilization of high-power consumption components [3]. Consequently, BackCom exhibits lower power consumption than WPC, effectively addressing the aforementioned obstacles.