BER Analysis of a NOMA Enhanced Backscatter Communication System

Backscatter communication (BackCom) has been emerging as a prospective candidate in tackling lifetime management problems for massively deployed Internet-of-Things (IoT) devices. This passive sensing approach allows a backscatter node (BN) to transmit information by reflecting the incident signal from a reader without initiating its transmission. Power-domain non-orthogonal multiple access (PD-NOMA), i.e., multiplexing the BNs with different backscatter power levels, being a prime candidate for multiple access in 5G systems is fully exploited in this work to multiplex multiple BNs. Recently, a great deal of attention has been devoted to the study of NOMA-aided BackCom networks in the context of outage probabilities and system throughput. However, the exact closed-form expressions of bit error rate (BER) for such a system has not been studied in the literature. In this paper, we derive the analytical BER expressions for a two BN BackCom system employing NOMA with imperfect successive interference cancellation (SIC) over an additive white Gaussian noise (AWGN) channel. The obtained BER expressions are utilized to evaluate the optimum reflection coefficients of BNs needed for the most optimal system performance in terms of BER and range of communication.