Backscatter-NOMA: A Symbiotic System of Cellular and Internet-of-Things Networks

Abstract

Non-orthogonal multiple access (NOMA) is envisioned as a key technology to enhance the spectrum efficiency for 5G cellular networks. Meanwhile, ambient backscatter communication is a promising solution to the Internet of Things (IoT), due to its high spectrum efficiency and power efficiency. In this paper, we are interested in a symbiotic system of cellular and IoT networks and propose a backscatter-NOMA system, which incorporates a downlink NOMA system with a backscatter device (BD). In the proposed system, the base station (BS) transmits information to two cellular users according to the NOMA protocol, while a BD transmits its information over the BS signals to one cellular user using the passive radio technology. In particular, if the BS only serves the cellular user that decodes BD information, the backscatter-NOMA system turns into a symbiotic radio (SR) system. We derive the expressions of the outage probabilities and the ergodic rates and analyze the corresponding diversity orders and slopes for both backscatter-NOMA and SR systems. Finally, we provide the numerical results to verify the theoretical analysis and demonstrate the interrelationship between the cellular networks and the IoT networks. INDEX TERMS Non-orthogonal multiple access (NOMA), Internet-of-Things (IoT), ambient backscatter communication (AmBC), symbiotic radio (SR), outage probability, ergodic rate. I. INTRODUCTION Non-orthogonal multiple access (NOMA) is an effective solution to accommodate the data traffic in 5G networks due to its spectrum-efficiency [1]-[6] and has stimulated the upsurge of interest from both academia and industry [7]-[16]. Different from the conventional orthogonal multiple access (OMA) techniques which allow only one user to access the networks in each orthogonal resource block (e.g., a time slot, a frequency channel, a spreading code, or an orthogonal spatial degree of freedom), NOMA enables more than one user to access the networks in the same resource block and distinguishes them by exploiting the power domain. Thus, NOMA system is more spectrum-efficient than conventional OMA system especially when one of the NOMA users is far away from the base station (BS) [3]. The associate editor coordinating the review of this manuscript and approving it for publication was Zhiyong Chen.

Energy-Efficient UAV Backscatter Communication with Joint Trajectory and Resource Optimization

“…Substituting the lower bound (27) and (29) into problem (26) and introducing slack variables {z(i)} to replace q(i) −q(i − 1) in constraint (25c), we have the following optimization problem…”

Resource Allocations for Symbiotic Radio With Finite Blocklength Backscatter Link

“…The FD BD can extract a portion of the original signal from the PT to decode the information, and simultaneously transmits its own information to the receiver via backscattering the remaining portion of the original signal [17], [18]. Integration of non-orthogonal multiple access (NOMA) into the SR system was presented to form a symbiotic network (i.e., including cellular and IoT networks) [19]. Specifically, a Base Station (BS) broadcasts the NOMA signal to two cellular users, while a BD modulates its own information over the original signals from the BS to a cellular user via the passive radio frequency.…”

Energy-Efficient Resource Allocation for NOMA-based Backscatter Communications

“…To overcome the near-far problem in communication systems, NOMA-based BackCom systems have been investigated to improve system capacity and spectrum utilization [6]. In [7], the closed-form expression of the outage probability and the ergodic rate of NOMA users have been provided for a downlink NOMA-based BackCom system. In [8], the outage probability has been derived for a NOMA-based BackCom system where the base station (BS) is equipped with multiple antennas.…”