Joint relay selection and power control for robust cooperative multicast in MmWave WPANs

Abstract

We put forward a joint optimization algorithm for relay selection and source & relay power allocations under lineof-sight (LoS) and non-LoS mixed conditions for both power saving and robustness enhancement in practical cooperative multicast millimeter-wave (mmWave) wireless personal area networks (WPANs). Firstly, a novel beam training protocol capable of overhearing is devised to filter relay candidates with non-LoS links and avoid relays selection for LoS paths through feedback 1-bit channel amplitude information (CAI). Secondly, we provide the problem formulation that minimizes the maximum total transmit power consumption under constraints of maximum tolerable outage probability and limited power. As these two problems are coupled together, the formulation is non-convex with extremely high complexity of finding optimal solution. By introducing relaxation method and Lagrange multipliers algorithm, we propose an optimal approach to reduce complexity while maintaining reasonable performance, and derive a closed-form expression of optimal joint relay selection and power allocation. Lastly, simulation results indicate significant improvements both on outage probability and power consumption performances over the existing sum transmit power minimization algorithm.

Optimal power allocation for physical layer security in device‐to‐device communications using untrusted relays

“…In Figure , ESR in terms of ρ in WJ scenario is evaluated for OPA and non‐OPA modes in the first phase for topologies T1 and T2, and for untrusted relays and trusted relays. In this figure, the untrusted relay scenario in this paper is compared with the trusted relay mentioned in other works . It is assumed that in the second phase, OPA has been done for ξ = ξ * .…”

“…Millimeter wave is an effective way to mitigate the data traffic demand in the 5G wireless communication system. The problem of assigning optimal power between the transmitter and the selected relay has been studied in the work of Chu et al In the first phase, all users decode the signals successfully, and in the second phase, one of them is selected as a relay to reencode and send the signal. This method requires double coding of the transmitted signal.…”

“…A long this line, we proceed to the OPA problem and secrecy rate analysis for the mentioned scenarios under two topologies T1 and T2. So far, the relays assisted cellular communications, D2D communication using trusted relays, and the security in cellular and D2D communications are investigated. Here, we consider an overlay D2D pair that communicates with each other through an untrusted AF relay, where in addition to helping data transmission also plays the role of the eavesdropper.…”