Wireless relay networks have been studied extensively in the recent literature. Amplify and forward (AF) is one of the most widely used type of relaying. Even though special cases such as channel-noise-assisted, channel-assisted and blind relay modes have been analyzed, a unified performance analysis seems to be not available. In this paper, we present unified performance analysis results for t...

We examine a network consisting of one source, one destination and two amplifying and forwarding relays and consider a scenario in which destination and relays can have various processing limitations. For all possible diversity combining schemes at the relays and at the destination, we find diversity order results analytically and confirm our findings through numerical calculations of bit error...

This paper proposes a novel green cooperative diversity technique based on suboptimal template-based ultra-wideband (UWB) wireless body sensor networks (WBSNs) using amplify-and-forward (AF) relays. In addition, it analyzes the bit-error-rate (BER) performance of the proposed nodes. The analysis is based on the moment-generating function (MGF) of the total signal-to-noise ratio (SNR) at the des...

This paper extends the amplify-and-forward based wireless network coding (AFNC) for single-relay network to multi-relay network with a chain topology. Direct application of the relaying protocol utilized in the conventional single-relay AFNC to the multi-relay scenario causes two major problems: the phenomenon of back stream of data, which we call data reflection, and inter-hop interference. We...

In cooperative relay networks, Channel State Information (CSI) is estimated at receiver. The estimated CSI is sent back to the relays through feedback link. This estimated CSI is often outdated due to feedback delay and the estimated outdated CSI is used for relay selection and detection which affects the performance of the system. The outage and error rate performance of the relay selection sc...

In this paper, we investigate the cooperative beamforming (BF) design problem for amplify-and-forward relay networks over frequency-selective channels. Orthogonal frequency division multiplexing (OFDM) transmission is employed to resist the multipath effects. We focus on the time-domain (TD) BF due to the lower implementation complexity and less feedback requirement from the destination to perf...

This paper studies the problem of detecting a potential malicious relay node by a source node that relies on the relay to forward information to other nodes. The channel model of two source nodes simultaneously sending symbols to a relay is considered. The relay is contracted to forward the symbols that it receives back to the sources in the amplify-and-forward manner. However there is a chance...

This paper derives an optimum relay position of amplify-and-forward (AF) cooperative communications with the differential transmission. As a performance benchmark, we utilize the probability of outage, which is defined as a probability that the instantaneous signal-tonoise power ratio (SNR) becomes lower than a certain threshold. The optimum relay position is found based on the theoretical expr...

We develop a framework for spectrum sensing in cooperative amplify-and-forward cognitive radio networks. We consider a stochastic model where relays are assigned in cognitive radio networks to transmit the primary user’s signal to a cognitive Secondary Base Station (SBS). We develop the Bayesian optimal decision rule under various scenarios of Channel State Information (CSI) varying from perfec...