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Intermittently Connected Mobile Networks (ICMNs) are sparse wireless networks where most of the time an end-to-end path does not exist from source to destination. These networks are characterized by opportunistic connectivity, long and variable delay, asymmetric data rate and high error rate. Hence, they can be appropriately modeled as Delay-Tolerant Networks (DTNs). In this paper, the performance...
The physical-layer network coding (PNC) has become a hot research topic, since it can potentially reduce the transmission time slots and increase the channel capacity. However, current studies are mainly concentrated on three nodes (two users and one relay) network. This paper considers a specific multiuser network that includes M (M>2) users with one relay, and illustrates the transmission scheme...
To ensure security in data transmission is one of the most important issues for wireless relay networks. In this paper, we consider a cooperative network, consisting of one source node, one destination node, one eavesdropper node, and a number of relay nodes. Specifically, the source selects several relay nodes which can help forward the signal to the corresponding destination to achieve the best...
The operation of Ad-hoc networks depends on the cooperation among nodes to provide connectivity and communication routes. However, such an ideal situation may not always be achievable in practice. Some nodes may behave maliciously, resulting in degradation of the performance of the network or even disruption of its operation altogether. To mitigate the effect of such nodes and to achieve higher levels...
In this paper, we consider a new scheme based on jointly network and rateless coding for a multiple-access relay channel. In the scheme, whenever the relay can decode multiple messages of the users, it jointly encodes them using a larger rateless code. This scheme is compared with direct transmission and the conventional relaying scheme in which the relay helps each user independently at orthogonal...
In multiple-relay cooperative wireless networks, opportunistic relaying is a promising scheme, where the most challenging problem is to choose the best relay efficiently. The traditional opportunistic relay selection scheme is based on the channel conditions of source-relay (S-R) and relay-destination (R-D) links. In comparison with conventional narrowband networks, an appealing merit of impulse radio...
In a wireless sensor network with relaying capability, intermediate relay nodes are with limited energy budget. To maximize lifetime of relay nodes, selective relay strategies, requiring full channel state information (CSI), are used to utilizes the best relaying channel. Pilot overhead on relay nodes lifetime is reduced by assuming pilot transmission from destination instead of relay nodes. This...
Due to the limited energy-source and mostly unattended nature of the wireless sensor networks, efficient use of energy has a critical importance on the lifetime of the applications accomplished by such networks. Although in most of the cases sensor nodes are battery-powered, there are application scenarios in which battery- and mains-powered nodes coexist. In this paper, we present an approach and...
Radio waves are the medium used by sensors to communicate and exchange data. The unconstrained accessibility to any information carried over this medium is a security issue in many sensor-based applications. Ensuring protected wireless communications is a problem that has received a lot of attention in the context of ad hoc networks. However, due to hardware constraints of sensors along with multi-hop...
Future cellular systems target the provision of high-speed multimedia and data services. However, support of such new services intensifies traffic burstiness and poses an increase of threat of congestion. This paper proposes a cooperative cellular architecture through which load balancing is achieved by exploiting the broadcast nature of radio waves and using minimum overhead. Unlike other existing...
Cooperative diversity has emerged as a promising approach to improving reception reliability by realizing spatial diversity gains for nodes with single antenna. We consider here cooperative ad-hoc wireless networks where communications between two nodes can be assisted by a single relay using two time slots. This paper continues our investigation of PHY techniques and cross-layer routing algorithms...
In this paper we present a novel technology named probability dynamic relay handover (PDRH) for the benefit of providing a mechanism to recover from selective attacks on some important terminals of JTIDS. The key points of PDRH are the probability model to simulate selective attacks using the theory of scale-free network and addressing for a new relay node. In simulation based on OPNET Modeler 10...
In mobile ad hoc net work, transmitting a packet from source to destination needs cooperation among nodes. Since there may be selfish nodes in the network and these selfish nodes are reluctant to relay packets for other nodes in order to protect resources of their own, the performance of the whole network will be influenced. We propose a cooperative incentive mechanism based on game theory. When determining...
In this paper we propose a new scheme for multi-hop forwarding in wireless networks. This new scheme is based on detection and forwarding of the received messages at the physical layer, without further processing at the higher layers. We derive a new expression for the symbol error rate in this proposed multi-hop detect-and-forward network by modeling the transmission line as a Markov Chain. The derived...
In classical routing strategies for multihop mobile wireless networks packets are routed on a pre-defined route usually obtained by a shortest path routing protocol. In opportunistic routing schemes, for each packet and each hop, the next relay is found by dynamically selecting the node that captures the packet transmission and which is the nearest to the destination. Such a scheme allows each packet...
A principal factor in sensor network design is energy efficiency. In this work, we propose to extend the lifetime of sensor networks using appropriate choice of sensor node distribution. The key idea of our scheme is to deploy more nodes in areas of extensive energy usage. Using this scheme of sensor node distribution, we use probabilistic angular routing to route data packets from the sensor nodes...
In this paper, we propose an intervehicle information dissemination protocol called received message-dependent protocol (RMDP) that propagates the preceding traffic information to the following vehicles and discuss its performance. The proposed protocol autonomously changes the dissemination interval, depending on the number of reception messages and detected reception errors, in order to avoid message...
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