An Adaptive Transmission Scheme for Amplify-and-Forward Relaying Networks

Abstract

Abstract-In this work, an adaptive scheme for amplify-andforward relaying networks is proposed, which selects a certain transmission mode for each communication process. Depending on the instantaneous channel conditions, one of the following modes is selected: direct transmission with no cooperation, cooperative transmission with half-duplex relaying and maximalratio combining at the destination, or cooperative transmission with full-duplex relaying and maximal-ratio combining at the destination. A three-node network is considered, containing a singleantenna source, a two-antenna relay that is able to implement full-duplex communication, and a single-antenna destination. Energy normalization per block is assumed, so that in those modes using cooperation the system's transmission power is shared between source and relay. The performance analysis is provided in terms of outage probability and energy efficiency. We derive a tight approximate expression in closed form for the outage probability and an approximate expression in integral form for the mean energy consumption. The results show that our scheme outperforms all of transmission modes separately in terms of outage probability, while being more energy efficient than the cooperative transmission modes. Additionally, the asymptotic analysis proves that the proposed scheme achieves full diversity order equal to 2, thus outperforming those schemes with direct transmission or full-duplex cooperation only.Index Terms-Amplify-and-forward, direct link, half duplex, full duplex, adaptive transmission mode, outage probability, relaying networks, energy efficiency.

Performance Analysis of Full-Duplex Relay-Aided NOMA Systems Using Partial Relay Selection

“…Fig. 8 illustrates the system sum rate versus the transmit SNR, as well as a comparison with OMA-based cooperative systems in which PRS among either multiple HD-AF relays or multiple FD-AF relays is employed 8 . In this case, the following system parameters are considered: number of relays K = 1, 2, 3, power allocation factors (a 1 , a 2 ) = (0.7, 0.3) and normalized distance of the links R k → D OMA , d R k DOMA = 0.5.…”

“…Monte Carlo simulations were provided to validate the accuracy of our formulas. Numerical results showed that an outage floor occurs due to the inherent 8 For both HD-OMA and FD-OMA systems, the network setup consists of one source, K relays, and two destinations, all operating on a TDMA basis, as in the FD-NOMA system considered herein. For the HD-OMA system, the source is assumed to send a message to each destination within one different fading block, which is divided into two time slots (one for the source-relay transmission and one for the relay-destination transmission).…”

“…In cooperative relaying networks, a relay node assists the communication between a source and a destination to improve the transmission range or to improve the reliability by leveraging spatial diversity [6]. According to the relay behavior, two main protocols are widely known, namely: decode-and-forward (DF), whereby the relay decodes and re-encodes the information signal before forwarding it [7]; and amplify-and-forward (AF), whereby the relay merely amplifies the received signal coming from the source and forwards it to the destination [8] 1 . Herein, we focus on the AF protocol, as it requires less computationally demanding processing at the relay, when compared to the other relaying protocols.…”

On the statistics of the ratio of nonconstrained arbitrary α‐μ random variables: A general framework and applications

“…Thus, γ SR =| h SR | 2 γ P /2 and γ RD =| h RD | 2 γ P /2 are the instantaneous received SNRs for the first‐ and second‐hop relaying links, respectively, where h SR and h RD are the corresponding channel coefficients, and γ P is the transmit system SNR. Moreover, due to imperfect stages of interference cancelation at the FD relay, a residual self‐interference (RSI) is considered, which can be modeled as a Rayleigh fading loop back channel, with channel coefficient , such that γ RR =| h RR | 2 γ P /2 is the instantaneous received SNR.…”

“…Another application where the statistics of the ratio of independent squared -RVs are considered is in FD relaying systems. 38,39 Let us consider the system depicted in Figure 3, which illustrates a two-hop FD relaying network composed of three nodes: one single-antenna source (S), one single-antenna destination (D), and one DF relay (R) equipped with one transmit antenna and one receive antenna to operate in FD mode. In this system, it is assumed that the direct link is highly attenuated, thus being neglected.…”