In this paper, a cooperative algorithm to improve the orthogonal space-timefrequency block codes (OSTFBC) in frequency selective channels for 2*1, 2*2, 4*1, 4*2 MIMO-OFDM systems, is presented. The algorithm of three node, a source node, a relay node and a destination node is formed, and is implemented in two stages. During the first stage, the destination and the relay antennas receive the sym...

In this study, we introduce a new two-way relay channel and obtain an inner bound and an outer bound for the discrete and memoryless multiple access relay channels with receiver-source feedback via two-way relay channel in which end nodes exchange signals by a relay node. And we extend these results to the Gaussian case. By numerical computing, we show that our inner bound is the same with o...

This paper introduces three coding strategies for using the Luby Transform (LT) code in a relay aided power-line communication scheme. In the first method, the relay decodes the received packets and re-encodes them for transmission towards the destination. In the second method, the relay only forwardes a random linear combination of its received packets towards the destination, while in the thi...

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 concerns two-hop communication over relay-assisted Block fading channel. It is assumed there is not a direct link between the transmitter and the affiliated destination and the communication occurs in two hops through the use of a relay, where the amplify and forward (AF) strategy is employed at this node. In this case, in a Rayleigh block fading channel, the optimal weight function ...

in this paper two different rateless transmissionschemes are developed. in the proposed scheme, relay node candecode and forward the message to the destination if they areable to decode it, or amplify and forward the message to thedestination. based on the analysis and simulation resultsprovided in this paper, the proposed method has bettertransmission time than the scheme which only the relay ...

This paper investigates rate adaptation schemes for decoding-and-forward (DF) relay system based on random projections codes (RPC). We consider a classic three node relay system model, where relay node performs on half-duplex mode. Then, we give out receiving diversity relay scheme and coding diversity relay scheme, and present their jointly decoding methods. Furthermore, we discuss the perform...

Secured communications in the presence of eavesdropper node is grave for the successful operations in the wireless relay networks. In the proposed work, choose two hop wireless relay networks to enhance security against the eavesdropper node. This paper considers four node networks, they are one source, and three decode and forward relay, one destination and one eavesdropper node. To transmit t...

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 ...

A method of cooperative relay selection based on network coding security is proposed for relay selection problem of cooperative communication system security in networked multi-relay scenarios, which is different from the existing relay node selection method. The algorithm not only merged with timestamp and homomorphic signature to construct the node degree of safety to find reliable relay, at ...