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In this paper, we consider an asynchronous relay network where different relaying paths are subject to different propagation delays thus causing inter-symbol-interference (ISI) at the destination. To eliminate such an ISI, orthogonal frequency division multiplexing (OFDM) is deployed at the source and destination but not at the relays. In fact each relay performs a simple amplify-and-forward operation:...
In this paper, we proposed an adaptive low latency MAC protocol for sensor networks based on cross-layer architecture, named LLS-MAC (Low Latency Sensor MAC). The new protocol is inspired by S-MAC. The advancement of LLS-MAC in packet end-to-end delay is mainly due to the continual data transmission scheme presented in this paper. For achieving this scheme, a cross-layer design approach is adopted...
The aim of this paper is to present a novel multipath routing approach in MANETs as new extensions to AODV, a well-known traditional reactive routing protocol. The approach is called Threshold efficient Routes in multipath AODV (TRAODV) which is a link-disjoint multipath extension that tries to optimise routing delay overhead in the route discovery process of traditional AODV. The optimisation in...
TCP, the facto standard used in today's Internet, has been found to perform poorly in Mobile Ad Hoc Networks (MANETs). This is exacerbated by contention with increasing UDP-based high priority multimedia traffic and the class differentiation introduced in current QoS protocols, which results into TCP starvation and increased spurious timeouts. In this paper, we propose a cross-layer TCP enhancement...
We present the distributed delay (DD) extension to the self-balancing supply/demand (SBSD) routing protocols for mobile ad hoc networks. SBSD controls flooding depth to limit network congestion and provides redundant broadcasts at each hop for reliable end-to-end delivery. In DD, the delay between a node's successive broadcasts increases with that node's one-hop density, to reduce broadcast redundancy...
Tolerant network (DTN) is a kind of network with high latency and frequent disconnection. To guarantee the success of delivering a message to the destination and to make time cost as low as possible, routers in this kind of network (DTN) need to multicopy the message and store it longer than routers in other kinds of network. This paper focuses on the relation and reciprocity between routing and buffer...
A Mobile Ad-hoc NETwork (MANET) is a wireless network set up temporarily without a wired infrastructure (routers, switches, servers, cables, access points, etc.). The wireless nodes in a MANET may move around and each one of them may need to forward packets for other components in the network. Several routing protocols such as DSR, AODV and DSDV have been proposed to facilitate communication in such...
This paper presents mathematical modeling and analysis for the total delay in disseminating safety messages in a vehicular ad hoc network (VANET). Node clustering can help in managing a large network and improving scalability, thus cluster based broadcasting is considered so as to prevent broadcast storms. Traffic flow theories developed in civil engineering are employed, which suggest different mathematical...
Due to their highly dynamic nature, vehicular ad hoc networks (VANETs) are occasionally found difficult for their parameter optimization. Some attempts have been made to challenge the difficulty by modeling VANETs mathematically to predict parameter values successfully such as average cluster size and the lifetime of a path. Nevertheless, there have been no systematic approaches to analyze both node...
This paper considers the problem of routing packets across a multi-hop wireless network while ensuring throughput optimality. One of the main challenges in the design of throughput optimal routing policies is identifying appropriate and universal Lyapunov functions with negative expected drift. The few well-known throughput optimal routing policies in the literature are constructed using simple quadratic...
This study evaluated the level of performance improvement in the form of a simulated experiment by adding fixed node in the middle of the network as a way to improve mobile ad.hoc network performance. The result showed that the performance level was much higher when fixed node was used together than when mobile node was used only, and the comparison of the mobile speed of mobile node also showed that...
In a wireless network, the set of transmitting nodes changes frequently because of the MAC scheduler and the traffic load. Analyzing the connectivity of such a network using static graphs would lead to pessimistic performance results. In this paper, we consider an ad hoc network with half-duplex radios that uses multihop routing and slotted ALOHA for the network MAC contention and introduce a random...
Advances in mobile networks and positioning technologies have made location information a valuable asset in vehicular ad-hoc networks (VANETs). However, the availability of such information must be weighted against the potential for abuse. In this paper, we investigate the problem of alleviating unauthorized tracking of target vehicles by adversaries in VANETs. We propose a vehicle density-based location...
Rate, energy and delay are three main parameters of interest in ad-hoc networks. In this paper, we discuss the problem of maximizing network utility and minimizing energy consumption while satisfying a given transmission delay constraint for each packet. We formulate this problem in the standard convex optimization form and subsequently discuss the tradeoff between utility, energy and delay in such...
In mobile wireless networks such as ad-hoc networks, sensor networks and mesh networks, wireless multihop transmission is adopted for data message transmission. For achieving higher throughput and shorter transmission delay, TDMA is one of more effective methods which avoid collisions and contentions than CSMA/CA and RTS/CTS. This paper proposes a reactive TDMA time slot assignment method in which...
Analytic model is proposed to evaluate the packet delay, the delay jitter and the packet loss probability of IEEE 802.11 Distributed Coordination Function (DCF) in multi-hop Ad Hoc Networks. This model can also be easily extended to analyze the Enhanced Distributed Channel Access (EDCA). By modeling each node as a discrete time G/G/1 queue, the closed form expressions of the delay, the delay jitter...
Nodes in ad hoc networks can be unfairly burdened to support many packet-relaying functions, resulting in excessive loads on these hot spots. This load on nodes appears in two major aspects: traffic and power consumption. Unbalanced traffic may lead to more delay, packet dropping, and decreasing packet delivery ratio (PDR). Unbalanced energy consumption leads to node failure, network partitioning...
Multicast routing with multiple constraints has become a very significant research issue in mobile ad hoc networks and focus on routing discovering. Compared with the existing methods, a routing discovering control with some constraints, such as delay, bandwidth and delay jitter, is described in this paper. Accordingly, a multicast routing protocol based on clustering (CMRP) is proposed. The each...
In this paper, we present an analytic model for evaluating the delay, delay jitter and the packet loss probability in multi-hop ad hoc networks using the IEEE 802.11 distributed coordination function (DCF) as MAC protocol. By modeling each node as a discrete time G/G/1 queue, we derive the closed form expressions of the end-to-end delay, delay jitter and the packet loss probability for different circumstances...
Wireless mesh networks (WMNs) are emerging as a key technology for the next-generation wireless networks owing to its attractive properties, such as dynamic self-organisation, quick deployment, easy maintenance, low cost, and high scalability. In this paper, we develop an analytical model to investigate the end-to-end delay in a random-access two-tier (i.e., the backhaul tier and access tier) WMN...
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