In this article, we propose multiple-relay selection schemes for multiple source nodes in amplify-and-forward wireless relay networks based on the sum capacity maximization criterion. Both optimal and sub-optimal relay selection criteria are discussed, considering that sub-optimal approaches demonstrate advantages in reduced computational complexity. Using semi-definite programming convex optim...

The capacity of a class of deterministic relay channels with transmitter input X , receiver output Y , relay output Y = f(X;Y ), and separate noiseless communication link of capacity R from the relay to the receiver, is shown to be C(R ) = supminfI(X;Y ) +R ; I(X;Y; Y )g: Roughly speaking, every bit from the relay is worth one bit to the receiver until saturation at capacity.

wireless sensor networks are composed of hundreds or thousands of small nodes called sensor that work together and are associated with a specific task or tasks to do. each of these nodes includes sensor, processor, communication components, a small memory and a source of energy. it is expected that wireless sensor networks will be used widely in many applications in near future. scalability and...

This paper focuses on relay node scheduling method which is based on an improved discrete Markov chain. It presents a single relay node’s existing state, analyzes its access behavior, and summarizes various linear system design, according to our present balanced equations and form state transition probability, nodes are scheduled in relay network, the improved discrete time Markov chain is used...

Validation and diagnosis of relay operation is very important to protection engineers in fault analysis. This paper presents development of an expert system based automated analysis solution, which performs validation and diagnosis of digital protective relay operation in great detail by analyzing data contained in various relay reports and files. In the system, forward chaining reasoning is us...

Cognitive relay networks (CRNs) combine cognitive radio technique and cooperative relay technology. Cognitive radio offers a tempting solution to increase spectrum usage efficiency by proposing opportunistic usage of frequency bands between primary and secondary users. Many techniques are used to improve the performance of the cognitive relay networks. One of these techniques is using multiple ...

Manuscript Received 23-October-2012 and revised 16-Janaury-2013 ISSN: 2322-4088 Accepted on daymonth-year Abstract— In this paper, Ultra-wideband (UWB) multiple access relay channel with correlated noises at the relay and receiver is investigated. We obtain outer and inner bounds for the IEEE 802.15.3a UWB multiple access relay channel, and also, a diversity gain bound. Finally, we evaluate som...

In this article, we address the goal of achieving performance gains under heavy-load and fast fading conditions. CoopMACI protocol proposed in Proceedings of the IEEE International Conference on Communications (ICC), Seoul, Korea, picks either direct path or relay path based on rate comparison to enhance average throughput and delay performances. However, CoopMACI performance deteriorates under...

In this paper, we study the performance of dual hop relaying in which the best relay selected by partial relay selection will help the source-destination link to overcome the channel impairment. Specifically, closed-form expressions for outage probability, symbol error probability and achievable diversity gain are derived using the statistical characteristic of the signal-to-noise ratio. Numeri...

In the light of the characteristics of random change that underwater sensor change by time, space and frequency, select the best relay node to improve communication quality and get the diversity gain. A new optimal relay selection method is proposed in this paper, by considering two indexes synthetically that channel gain and underwater acoustic communication long time delay to select the best ...