Abstract
This article proposes a hybrid of backscatter communication (BackCom) and wireless powered non-orthogonal multiple access (NOMA) network for Internet of Things (IoT) applications, which consists of one power beacon (PB), multiple energy-constrained IoT devices, and one information receiver (IR). In the proposed network, the IoT devices harvest energy and backscatter their information to the IR in turn when PB broadcasts energy signals, and then use the harvested energy to transmit information to the IR via uplink NOMA when PB keeps silent. Considering the non-overflowing energy constraint, a max-min throughput optimization problem is formulated to ensure the throughput fairness among different IoT devices by jointly optimizing the time resource for operating BackCom and uplink NOMA, the reflection coefficient of BackComs, the transmit power for uplink NOMA and the transmit power of the PB. Although the formulated problem is non-convex and challenging to solve, we first transform the original non-convex problem into an equivalent convex one with the aid of an inequality transformation approach and introducing several kinds of auxiliary variables, and then devise a two-layer iterative algorithm to obtain the optimal resource allocation. Simulation results are provided to verify the convergence of the devised iterative algorithm and validate that the proposed scheme achieves the highest max-min throughput by comparing it with three baseline schemes.
Highlights
In the era of Internet of Things (IoT), there will be ultra-massive battery-power IoT devices deployed in various communication systems, e.g., intelligent automatic manufacturing system, to monitor, and report data to the information fusion for realizing intelligent IoT services [1]
In Wireless powered communication network (WPCN), the IoT device first harvests energy from the radio frequency (RF) signals transmitted by the RF source, e.g., power beacon (PB), and follows the ‘‘harvest--transmit’’ protocol conveying its own message to its associated receiver via active transmissions, where the IoT device needs to generate the carrier signal and modulate its own message on the generated carrier [6]–[9]
We study the throughput maximization under the max-min fairness criterion for backscatter assisted wireless powered non-orthogonal multiple access (NOMA) networks to ensure the throughput fairness among different IoT devices
Summary
In the era of Internet of Things (IoT), there will be ultra-massive battery-power IoT devices deployed in various communication systems, e.g., intelligent automatic manufacturing system, to monitor, and report data to the information fusion for realizing intelligent IoT services [1]. In [15], the authors studied a point-to-point communication network, where the IoT device conveys information to the information fusion via backscattering the received signals or active transmissions In such a case, a joint time and reflection coefficient allocation scheme was proposed to maximize the achievable throughput. It has been validated that compared with the OMA, non-orthogonal multiple access (NOMA) scheme, one of novel multiple access schemes, achieves a larger throughput of the system while ensuring the fairness among transmission links Thanks to this advantage, various contributions (see [27]–[29] and reference therein) have been devoted to designing resource allocation schemes to satisfy different goals for wireless powered NOMA networks, where multiple IoT devices harvest energy firstly and transmit their information to the information fusion via uplink NOMA. Based on (5), the total achievable throughput of the i-th IoT device in the entire transmission block can be computed as
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