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Multiple Accesses Broadcasting (MABC) is a spectral efficient protocol in two-way relay channel (TWRC). The drawback of this protocol in decode-and-forward (DF) mode is decoding complexity at the relay's side. Erroneous decoding at the relay can bring about error propagation that leads to performance degradation in all of the relay networks operating in the DF mode. In this paper, we propose ML detection...
A multi-hop wireless transmission system employing both half duplex and imperfect full duplex relays is proposed. In this scheme, which uses Ksub-channels for transmission and reception over Rayleigh fading channels, we aim to mitigate the most dominant source of interference in each node by allocating different sub-channels to various groups of nodes. The outage probability of the proposed scheme...
In this paper, we consider adaptive quadratic amplitude modulation (QAM) for a cooperative network consists of a source, one decode-and-forward (DF) relay and a destination which are single antenna systems. For increasing the spectral efficiency of the system, we use adaptive modulation method for data transmission. We propose a new adaptive modulation scheme which has less complexity than available...
In this study, we enhance achievable sum-rate in an ad hoc network consisting of two source-destination pairs and k half-duplex Decode-and-Forward (DF) relays. We assume that two receivers use strong interference cancellation technique and can cancel strong interference. Then, in order to enhance the achievable sum-rate, we propose a novel relay selection scheme that can make Strong and Weak Interference...
In this paper, assuming transmission with fixed rate and fixed power, we derive the average duration of capacity outage and non-outage events of selective decode-and-forward relaying with repetition coding over slow Rayleigh fading channels. Furthermore, we develop high signal-to-noise ratio (SNR) approximations for both durations which provide significant insight into the impact of various system...
In this paper, we formulate an optimization problem for resource allocation and scheduling in orthogonal frequency division multiple access (OFDMA) half-duplex decode-and-forward (DF) relay assisted networks. Our problem formulation takes into account artificial noise generation to combat a multiple antenna eavesdropper. The secrecy data rate, power, and sub-carrier allocation policies are optimized...
We study a single-source single-destination wireless cooperative communication system with multiple relays operating in a modified decode-and-forward mode. Nakagami-m fading with additive white Gaussian noise is assumed for all inter-node channels. A packet feedback model is proposed to approximately characterize packet loss events in the wireless channel. An approximation to the steady state distribution...
In this paper, we investigate the diversity-multiplexing tradeoff (DMT) of a multi-hop coherent free-space optical (FSO) system over atmospheric channels. We consider a relay-assisted FSO system with decode-and-forward relay nodes and multiple heterodyne receivers with modal compensation. Based on a recently introduced statistical characterization for the combined effects of turbulence-induced amplitude...
Multi-path fading, one of the key factors that deteriorate quality of service (QOS) in Underwater Acoustic Networks (UANs), is investigated under different underwater scenarios in this paper. To improve the Bit Error Rate (BER) performance, the techniques of cooperative diversities are applied. Considering realistic physical model and cooperative diversity techniques, two asynchronous forwarding schemes,...
In this paper, the exact symbol error probability expression for a decode-and-forward cooperative relaying scheme using quadrature amplitude modulation (QAM) in the presence of Rayleigh fading and Bernoulli-Gaussian impulsive noise is derived. Different from, we only consider the practical receiver structure at the destination without requiring any knowledge of impulsive noise. Also, the source retransmission...
Relay-assisted network coding (NC) has attracted recent interests in increasing the transmission reliability and network throughput. By encoding the received packets from different source nodes, a relay node assists destinations to recover their desired information by forwarding the network coded packets. Previous work commonly assumes reliable inter-node channels and that relays always encode all...
In this paper, we propose a variable-rate based relay selection scheme for decode-and-forward cooperative networks. Adaptive modulation is used as a practical implementation of the variable-rate transmission. In specific, we exploit the variable rate transmission to choose the maximum rate, and select the best relay that has the best end-to-end path between the source and destination nodes. We derive...
This paper investigates a novel relaying strategy for cooperative networks over Nakagami-m fading channel, namely selection incremental relaying (SIR), which combines selection relaying (SR) with incremental relaying (IR) based on decode-and-forward (DF). The closed-form expression for the outage probabilities of both single relay and opportunistic relay strategies are derived. Simulation results...
Recently, two classes of high rate bilayer low-density parity-check (LDPC) codes have been proposed for Gaussian relay channels using bilayer density evolution technique. These two classes include bilayer lengthened LDPC codes and bilayer expurgated LDPC codes that have been used in a decode-and-forward relaying strategy. In this paper, we first study the decode-and-forward achievable rates for a...
In this paper, we study a decode-and-forward cooperative diversity scheme for wireless systems using the combination of bit-interleaved coded modulation (BICM) and orthogonal frequency division multiplexing (OFDM). We propose a simple cooperative maximum-ratio combining scheme for the destination which can successfully exploit the full spatial and frequency diversity offered by the channel. Taking...
In this paper, we investigate the wiretap channel in the presence of a cooperative relay node. We analyze and compare the outage performance of three cooperatives schemes: cooperative jamming (CJ), decode-and-forward (DF), and amplify-and-forward (AF) for the Rayleigh slow fading channel. In particular, we derive a closed-form expression for the outage probability for the DF and CJ strategies, which...
In cooperative OFDM networks, ordered subcarrier pairing (OSP) at the relay has been shown to improve the average end-to-end capacity evidently. In this paper, the statistical performance evaluations are provide for two-hop OFDM relay link with both amplify-and-forward (AF) and decode-and-forward (DF) protocol. First, closed-form expressions are derived for the probability density function (PDF) of...
The exact average capacities of rate adaptive single-relay selection decode-and-forward dual-hop relaying for block Rayleigh fading with two cooperation schemes, called parallel channel cooperation and repetition-based cooperation (RC), are obtained. General, dissimilar fading channels and the effect of the source-destination link are considered. Accurate approximations to the average capacity in...
In this paper, an adaptive forwarding strategy for wireless networks using relays in multi hop and cooperative network is discussed. Here two schemes, amplify-and-forward (AF) and decode-and-forward (DF) are chosen depending on channel condition. Further it allows switching between the two schemes according to channel condition. The bit error probability performance (BEP) for the proposed hybrid strategy...
We consider the problem of optimal power allocation over a family of parallel Gaussian relay channels, each with a different set of channels' power gains. The applied cooperative strategy is half-duplex regenerative decode-and-forward which is multiplexed orthogonally with a direct transmission link from the source node to the destination node. We assume the availability of channel-state-information...
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