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Pooling mobile nodes in vicinity as a collaborative community offers an opportunity for multi-homed mobile nodes to enable multipath transmission even when there is no multiple access coverage. However, packet collisions exist within the collaborative community when a contention-based channel access such as IEEE 802.11 is applied. As a result, the overall multipath performance may degrade if a regular...
In opportunistic networks, mobile nodes such as mobile phones and PDAs use the mobility of devices in addition to wireless forwarding between intermediate nodes to facilitate communication without requiring a simultaneous path between source and destination.Without guaranteed connectivity, the strategy for forwarding messages has a significant effect on system performance. Most of the existing research...
A number of recently proposed systems provide secure and privacy-preserving data dissemination by leveraging pre-existing social trust relations and effectively mapping them into communication links. However, as we show in this paper, the underlying trust graph may not be optimal as a communication overlay. It has relatively long path lengths and it can be easily partitioned in scenarios where users...
Despite much recent research on peer-to-peer (P2P) protocols for the Internet, there have been relatively few practical protocols designed to explicitly account for Network Address Translation gateways (NATs). Those P2P protocols that do handle NATs circumvent them using relaying and hole-punching techniques to route packets to nodes residing behind NATs. In this paper, we present Croupier, a peer...
Beaconless position-based forwarding protocols have recently evolved as a promising solution for packet forwarding in wireless sensor networks. Quite a few variants of this class of forwarding protocols have been proposed over the years. One common observation is that they have all been evaluated from the perspective of a single node. Although useful, but a solid understanding of the end-to-end performance...
In this paper we examine opportunistic content distribution. We design and evaluate a caching strategy where a node will fetch and share contents on behalf of other nodes, although the contents are not of its own interest. We propose three caching options for improving the use of network resources: relay request on demand, hop-limit, and greedy relay request. The proposed strategies are implemented...
Cloud services have attracted much attention in recent years as networking systems for the information connection devices of organizations or enterprises around the world have become increasingly sophisticated. Cloud services also provide a variety of services for users, including virtual hosting services, storage services, and Web application services. Distributed computing and the peer-to-peer (P2P)...
We propose in [1] a collaborative broadcast scheme for wireless networks, which applies the Uncoordinated Frequency Hopping (UFH) technique to counteract jamming and exploits node cooperation to enhance broadcast efficiency. In this scheme, some nodes that already obtain the broadcast message are selected to relay the message to other nodes. In this paper, we extend the study to the generalized multihop...
We consider communication in the uplink of a wireless mesh or sensor network. A group of mobile radios or sensors (hereafter called "nodes") have information to transmit to one or more access points (APs) (or "sinks"). When the channels from the nodes to the APs suffer from fading, direct transmissions to the APs may fail with a high probability, and packets may need to be relayed...
Security has been recognized as a key issue for the expansion of eHealth application, where highly sensitive patient's medical data are routed through a non-secure wireless network. In this paper, we look into the various security and privacy requirements for the eHealth application and propose an agent-based secure and trustworthy packet-forwarding Protocol (ASTP) considering the neighbor nodes previous...
We investigate the impact of cooperative relaying on uplink multi-user (MU) wireless video transmission. We formulate the problem as an MU Markov decision process (MDP) that explicitly considers the cooperation at the physical layer and the medium access control sublayer, the video users' heterogeneous traffic characteristics, and the dynamically varying network conditions. Although MDPs notoriously...
Cooperative Network-Coded Hybrid ARQ (Coop-NC HARQ) has recently been proposed as a smart way to improve Decode & Forward (D&F) relaying. According to this idea, cooperators send HARQ redundancy on behalf of a source coded together with a data packet intended for the destination they are helping and taken from their own queue. This paper applies for the first time such a technique in ad hoc...
Distortion exponent (DE) is the asymptotic exponential decay rate of the expected distortion between a source and its reconstruction in the high- SNR regime. This paper presents two improvements to the existing DE analyses of two-way relaying networks, where two users communicate in both directions with the help of a relay. First, we allow the users to have different bandwidth ratios, and derive the...
Delay/Disruption Tolerant Network (DTN) differs from the conventional networks in that it has no continuous or contemporaneous connections among wireless nodes. Its inherent characteristic of intermittent connections makes existing routing solutions hardly to be applied directly. Epidemic routing using random linear network coding has been studied and proved as an efficient way for light data delivery...
In this paper, we consider the power allocation problem in a network coded multiuser two-way relaying network, where multiple pairs of users exchange information with the help of a relay node. An auction-based power allocation scheme is proposed to solve the power competition among multiple user pairs. To maximize the utility of the whole pair, each two users in the pair bid as a single player, with...
In this paper, we present a cooperative transmission approach to reduce the end-to-end delay in the context of AODV based multi hop wireless networks. The underneath idea is to effectively increase the average reach of each hop so that data packets can arrive at the destination in less number of hops with lower end-to-end delay. The existing approaches of increasing transmitted power are not effective...
The multi-hop cellular network (MCN) is an evolved paradigm for mobile communications, which integrates the ad hoc characteristics into the conventional cellular systems. Similar to ad hoc networks, the performance of MCNs relies on the hypothesis that each node accepts to forward traffic for the benefit of others, which may not hold with the possible presence of selfish users. In order to stimulate...
Simple yet cost effective hybrid Wireless Sensor Networks (WSN) with both standard nodes and transmit-only nodes are promising for their great potential as the "edge" of the "Internet of Things". However the lack of receivers at many transmit-only nodes in the hybrid network renders most existing MAC protocols invalid. Our previous efforts showed the benefits of this hybrid architecture...
Delay/Disruption tolerant networks (DTNs) are self-organized wireless networks, where end-to-end network connectivity is not available and the data forwarding relies on the assumption that the intermediate nodes are ready to ``store, carry and forward'' messages in an opportunistic way. This assumption can be easily violated by the selfish nodes which may be unwilling to use their precious resources...
Beaconless position-based forwarding protocols have recently evolved as a promising solution for packet forwarding in wireless sensor networks. However, as the network density grows, the overhead incurred grows significantly. As such, end-to-end energy and delay performance is adversely impacted. Motivated by the need for a forwarding mechanism that is more tolerant to growth in node density, an alternative...
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