Search results for "Networks"
showing 10 items of 3260 documents
Cooperative Medium Access Control in Wireless Networks: The Two-Hop Case
2009
Cooperative communication has been recently proposed as a powerful means to improve network performance in wireless networks. However, most existing work focuses solely on one-hop source-destination cooperation. In this paper, we propose a novel cooperative MAC mechanism that is specially designed for two-hop cooperation communications where the source node and the destination node cannot hear each other directly. In this case, cooperative communication is operated in a two-hop manner and transmit-diversity is achieved by the reception of the same data packet forwarded through multiple relays towards a single destination. The proposed scheme employs an efficient relay selection algorithm to…
On the Benefits of Random Linear Coding for Unicast Applications in Disruption Tolerant Networks
2006
In this paper, we investigate the benefits of using a form of network coding known as Random Linear Coding (RLC) for unicast communications in a mobile Disruption Tolerant Network (DTN) under epidemic routing. Under RLC, DTN nodes store and then forward random linear combinations of packets as they encounter other DTN nodes. We first consider the case where there is a single block of packets propagating in the network and then consider the case where blocks of K packets arrive according to a Poisson arrival process. Our performance metric of interest is the delay until the last packet in a block is delivered. We show that for the single block case, when bandwidth is constrained, applying RL…
An optimal energy efficient cooperative retransmission MAC scheme in wireless networks
2011
While the benefits of cooperative diversity have been well studied in the literature, cooperative MAC protocol design has also attracted much attention recently. In the single-relay Cooperative Automatic Repeat reQuest (C-ARQ) protocol, the best relay node is selected in a distributed manner by relays using different backoff time before packet retransmission. However, this relay selection scheme does not work efficiently in a dense network scenario, due to possible high collision probability among different contending relays. In this paper, we propose an optimized relay selection scheme to maximize system energy efficiency by reducing collision probability. The energy efficiency performance…
Exploiting 3D Modelling and Life Cycle Assessment to Improve the Sustainability of Pavement Management
2020
Today road agencies worldwide face difficult decisions for construction, maintenance and rehabilitation of their road infrastructure as they try to balance limited budgets. This is further complicated rising environmental concerns over equipment and techniques used for these practices. This has led agencies to consider alternative approaches for smarter and sustainable pavement asset management systems. This paper considers the use of a low-cost 3D image modelling distress identification and classification proposal for data acquisition and analysis. To establish its environmental friendliness, a case study in Palermo, Italy, is considered wherein a Life Cycle Assessment (LCA) exercise is do…
MansOS
2010
Often software for wireless sensor networks (WSNs) is developed using a specific event based operating system (OS) such as TinyOS. However, this requires steep learning curve for the new developers. Other operating systems for embedded devices have limited support for new hardware platforms. Our goal is to provide an operating system for resource constrained devices that is easy to use for the wide range of researchers and developers familiar with C programming language and Unix operating system concepts. In addition, we provide a framework for agile portability to new hardware platforms, due to the nature of WSN systems that require specific hardware or features for the sensing tasks at ha…
Computer Programming Aptitude Test as a Tool for Reducing Student Attrition
2015
Submitted to the VTR conference to be held in Rezekne, June 2015
Blockchain based Inter-domain Latency Aware Routing Proposal in Software Defined Network
2018
Border gateway protocol (BGP) version 4 is routing current Internet for more than 20 years. BGP is the only protocol that has proven its routing capability of such size network with continually growing nature. Although BGP is scalable and network layer reachability information it lacks quality of service metrics like latency. BGP routing decision algorithm uses as-path length between autonomous systems (AS) as main factor for most of its best-path calculations. Because of more affordable peering architectures as-path length is generally decreasing in worldwide internet network resulting in less efficient routes for real-time internet protocol traffic. This study proposes future internet arc…
Trust-based framework for security enhancement of P2PSIP communication systems
2009
Today, Peer-to-Peer SIP based communication systems have attracted much attention from both academia and industry. The decentralized nature of P2P might provide the distributed peer-to-peer communication system without help of the traditional SIP server. However, it comes to the cost of reduced trustworthiness and may cause security problems, e.g. privacy leaks, unpredictable availability, etc. In this paper, we investigate on P2PSIP security issues and propose a subjective based trust model that offers trust services during P2PSIP session establishment. The main issues considered in this model include opinion calculation, opinion maintenance, data confidentiality and integrity, message rou…
Side Effects of Ambient Noise Immunity Techniques on Outdoor IEEE 802.11 Deployments
2008
A very common conclusion of many experimental studies about IEEE 802.11 outdoor network deployments is that their poor performance results derive from the unfavorable interference and multi-path signals in which the WLAN-cards are required to operate. Goal of this paper is to show that this condition does not always hold, and unexpected and inaccurated PHY layer implementations can be a primary cause of packet losses. With the support of extensive measurement campaigns led in our campus, we provide the performance evidence that IEEE 802.11 outdoor performance impairments are strongly affected by proprietary interference mitigation techniques that adaptively adjust the WLAN-card receiver sen…
A Multi-Relay Cooperative Automatic Repeat Request Protocol in Wireless Networks
2010
This paper proposes a Multi-relay Cooperative Automatic Repeat ReQuest protocol (MC-ARQ) for IEEE 802.11 based wireless networks. The proposed distributed relay selection scheme not only selects the best relays but also solves the collision problem among multiple contending relays, by sorting the relays in the network according to their instantaneous channel quality with the destination node. No prior information or explicit signaling among relay nodes is required. Both analytical and simulation results show that significant benefits can be achieved with the MC-ARQ protocol, compared with both the recently proposed PRCSMA scheme and the original non-cooperative DCF scheme.