Source‐sum‐power minimization in multiple‐sensor single‐AF relay‐based IoT networks with outage constraints and under hardware impairments and imperfect CSI

Abstract

SummaryThis paper investigates the optimal power allocation to minimize the source‐sum‐power consumption of Internet of Things networks in the presence of transceiver hardware impairments and imperfect channel estimates, where N single‐antenna sensors communicate with a single‐antenna destination via a single‐antenna half‐duplex amplify‐and‐forward relay. We assume that the consideration of remote‐area wireless sensor application restricts the direct communication between the sensors and destination. Specifically, we first derive the exact and asymptotic outage probability expressions under hardware impairments and imperfect channel estimates over Rayleigh fading channels. Then, we formulate and evaluate an optimization problem for source‐sum‐power minimization taking both the power and outage constraints into account in the presence of transceiver hardware impairments and imperfect channel estimates with the help of Karush‐Kuhn‐Tucker conditions. The numerical results corroborate our theoretical findings and demonstrate the optimality of the considered system. Moreover, our results reveal that (i) the system's diversity order reduces to zero because of the irreducible error floor occurs from the fixed channel estimation errors, (ii) the source‐sum‐power consumption reduces with the increased maximum available relay power and increases as the number of sensor nodes increases, (iii) the hardware impairments and imperfect channel estimates significantly increase the source‐sum‐power consumption, and (iv) the proposed source‐sum power minimization scheme can optimize the performance of the considered system. Also, we compare our proposed optimal power allocation scheme with the uniform power allocation scheme, from which it is shown that the proposed scheme is better than the uniform one irrespective of the involved parameters. Furthermore, we compare our proposed scheme with some existing approaches, such as time division scheme and decode‐and‐forward relay scenario, in terms of outage probability and source‐sum‐power minimization.