Performance evaluation of wireless IEEE 802.11(b) used for ad-hoc networks in an e-learning classroom network

Evaluation of wireless networks for performance evaluation is a popular research area and a wealth of literature exists in this area. Wireless networks in infrastructure mode as well as Ad-hoc networks such as MANETs are considered extensively. Simulation results are provided for E-learning scenarios for cases where wireless networks in infrastructure mode are employed, however the possibilities of using ad- hoc networks and performance evaluation of e-learning scenarios with ad hoc networks are not considered. This paper presents an evaluation of the performances for wireless Ad-hoc networks employed in typical e-learning environment by using the OPNET modeller. Numerical simulation results, discussions and comparisons are provided. The results can be of great help for optimisation studies in typical e-learning environments. The performance issues are considered together with scalability concerns

Improving the Performance of Wireless LANs

This book quantifies the key factors of WLAN performance and describes methods for improvement. It provides theoretical background and empirical results for the optimum planning and deployment of indoor WLAN systems, explaining the fundamentals while supplying guidelines for design, modeling, and performance evaluation. It discusses environmental effects on WLAN systems, protocol redesign for routing and MAC, and traffic distribution; examines emerging and future network technologies; and includes radio propagation and site measurements, simulations for various network design scenarios, numerous illustrations, practical examples, and learning aids

A Quantitative Analysis of Performance in a Multi-Protocol Ad Hoc 802.11b-based Wireless Local Network

The popularity of the Internet and the growing demand for ubiquitous connectivity accelerate the need for viable wireless local area network (WLAN) solutions. As a consequence, increasing number of manufacturers have adopted the Institute of Electrical and Electronic Engineers (IEEE) 802.11a/b/g set of WLAN standards and produced inexpensive wireless products to expand capabilities of existing LANs. IEEE 802.11 b wireless products are widely accepted. Mobile ad hoc networks, a variant of the 802.11 standards, exist without the requirement for a wired infrastructure or host to provide routing, connectivity, and maintenance services. Because of the high variability of environments in which ad hoc networks operate, numerous routing protocols are proposed. Research indicates that these protocols are unsuited for efficient operation in multiple environments. In this investigation, the author examined the effect of multiple protocols on throughput and end-to-end delay in simulated ad hoc networks. The author selected the ad hoc on-demand distance vector (AODV) and dynamic source routing (DSR) routing protocols for this research. The outcomes from the simulations conducted indicated increased end-to-end delay and reduced packet throughput as a result of the mixed populations of the AODV and DSR ad hoc routing protocols. The results also indicated that increasing node density and velocity improved packet throughput and reduced end-to-end delay

Energy aware routing protocols in ad hoc wireless networks

In Mobile Ad hoc Network, communication at mobile nodes can be achieved by using multi-hop wireless links. The architecture of such a network is based, not on a centralized base station but on each node acting as a router to forward data packets to other nodes in the network. The aim of each protocol, in an ad hoc network, is to find valid routes between two communicating nodes. These protocols must be able to handle high mobility of the nodes which often cause changes in the network topology. Every ad hoc network protocol uses some form of a routing algorithm to transmit between nodes based on a mechanism that forwards packets from one node to another in the network. These algorithms have their own way of finding a new route or modifying an existing one when there are changes in the network. The novel area of this research is a proposed routing algorithm which improves routing and limits redundant packet forwarding, especially in dense networks. It reduces the routing messages and consequently power consumption, which increases the average remaining power and the lifetime of the network. The first aim of this research was to evaluate various routing algorithms in terms of power. The next step was to modify an existing ad hoc routing protocol in order to improve the power consumption. This resulted in the implementation of a dynamic probabilistic algorithm in the route request mechanism of an ad hoc On-Demand Distance Vector protocol which led to a 3.0% improvement in energy consumption. A further extension of the approach using Bayesian theory led to 3.3% improvement in terms of energy consumption as a consequence of a reduction in MAC Load for all network sizes, up to 100 nodes.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Software defined wireless sensor networks application opportunities for efficient network management : a survey

Wireless Sensor Networks (WSNs) are commonly used information technologies of modern networking and computing platforms. Today's network computing applications are faced with a high demand of powerful network functionalities. Functional network reach is central to customer satisfaction such as in mobile networks and cloud computing environments. However, efficient management of WSNs remains a challenge, due to problems supplemental to them. Recent technology shift proposes Software Defined Networking (SDN) for improving computing networks. This review paper highlights application challenges faced by WSNs for monitored environments and those faced by the proposed approaches, as well as opportunities that can be realized on applications of WSNs using SDN. We also highlight Implementation considerations by focusing on critical aspects that should not be disregarded when attempting to improve network functionalities. We then propose a strategy for Software Defined Wireless Sensor Network (SDWSN) as an effort for application improvement in monitored environments.The National Research Foundation (NRF) of South Africa (grant number: RDYR160404161474 and IFR160118156967).http://www.elsevier.com/locate/compeleceng2019-02-01hj2018Electrical, Electronic and Computer Engineerin

An Analysis of Electromagnetic Interference (EMI) of Ultra Wideband(UWB) and IEEE 802.11A Wireless Local Area Network (WLAN) Employing Orthogonal Frequency Division Multiplexing (OFDM)

Military communications require the rapid deployment of mobile, high-bandwidth systems. These systems must provide anytime, anywhere capabilities with minimal interference to existing military, private, and commercial communications. Ultra Wideband (UWB) technology is being advanced as the next generation radio technology and has the potential to revolutionize indoor wireless communications. The ability of UWB to mitigate multipath fading, provide high-throughput data rates (e.g., greater than 100 Mbps), provide excellent signal penetration (e.g., through walls), and low implementation costs makes it an ideal technology for a wide range of private and public sector applications. Preliminary UWB studies conducted by The Institute for Telecommunications Science (ITS) and the Defense Advanced Research Projects Agency (DARPA) have discovered that potential exists for harmful interference to occur. While these studies have provided initial performance estimates, the interference effects of UWB transmissions on coexisting spectral users are largely unknown. This research characterizes the electromagnetic interference (EMI) effects of UWB on the throughput performance of an IEEE 802.11a ad-hoc network. Radiated measurements in an anechoic chamber investigate interference performance using three modulation schemes (BPSK, BPPM, and OOK) and four pulse repetition frequencies over two Unlicensed National Information Infrastructure (U-NII) channels. Results indicate that OOK and BPPM can degrade throughput performance by up to 20% at lower pulse repetition frequencies (PRFs) in lower U-NII channels. Minimal performance degradation (less than one percent) due to interference was observed for BPSK at the lower PRFs and higher U-NII channels

SIMULATION AND ANALYSIS OF VEHICULAR AD-HOC NETWORKS IN URBAN AND RURAL AREAS

According to the American National Highway Traffic Safety Administration, in 2010, there were an estimated 5,419,000 police-reported traffic crashes, in which 32,885 people were killed and 2,239,000 people were injured in the US alone. Vehicular Ad-Hoc Network (VANET) is an emerging technology which promises to decrease car accidents by providing several safety related services such as blind spot, forward collision and sudden braking ahead warnings. Unfortunately, research of VANET is hindered by the extremely high cost and complexity of field testing. Hence it becomes important to simulate VANET protocols and applications thoroughly before attempting to implement them. This thesis studies the feasibility of common mobility and wireless channel models in VANET simulation and provides a general overview of the currently available VANET simulators and their features. Six different simulation scenarios are performed to evaluate the performance of AODV, DSDV, DSR and OLSR Ad-Hoc routing protocols with UDP and TCP packets. Simulation results indicate that reactive protocols are more robust and suitable for the highly dynamic VANET networks. Furthermore, TCP is found to be more suitable for VANET safety applications due to the high delay and packet drop of UDP packets.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Design of interface selection protocols for multi-homed wireless networks

This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University on 10 December 2010.The IEEE 802.11/802.16 standards conformant wireless communication stations have multi-homing transmission capability. To achieve greater communication efficiency, multi-homing capable stations use handover mechanism to select appropriate transmission channel according to variations in the channel quality. This thesis presents three internal-linked handover schemes, (1) Interface Selection Protocol (ISP), belonging to Wireless Local Area Network (WLAN)- Worldwide Interoperability for Microwave Access (WiMAX) environment (2) Fast Channel Scanning (FCS) and (3) Traffic Manager (TM), (2) and (3) belonging to WiMAX Environment. The proposed schemes in this thesis use a novel mechanism of providing a reliable communication route. This solution is based on a cross-layer communication framework, where the interface selection module uses various network related parameters from Medium Access Control (MAC) sub-layer/Physical Layer (PHY) across the protocol suite for decision making at the Network layer. The proposed solutions are highly responsive when compared with existing multi-homed schemes; responsiveness is one of the key factors in the design of such protocols. Selected route under these schemes is based on the most up to date link-layer information. Therefore, such a route is not only reliable in terms of route optimization but it also fulfils the application demands in terms of throughput and delay. Design of ISP protocol use probing frames during the route discovery process. The 802.11 mandates the use of different rates for data transmission frames. The ISP-metric can be incorporated into various routing aspects and its applicability is determined by the possibility of provision of MAC dependent parameters that are used to determine the best path metric values. In many cases, higher device density, interference and mobility cause variable medium access delays. It causes creation of ‘unreachable zones’, where destination is marked as unreachable. However, by use of the best path metric, the destination has been made reachable, anytime and anywhere, because of the intelligent use of the probing frames and interface selection algorithm implemented. The IEEE 802.16e introduces several MAC level queues for different access categories, maintaining service requirement within these queues; which imply that frames from a higher priority queue, i.e. video frames, are serviced more frequently than those belonging to lower priority queues. Such an enhancement at the MAC sub-layer introduces uneven queuing delays. Conventional routing protocols are unaware of such MAC specific constraints and as a result, these factors are not considered which result in channel performance degradation. To meet such challenges, the thesis presents FCS and TM schemes for WiMAX. For FCS, Its solution is to improve the mobile WiMAX handover and address the scanning latency. Since minimum scanning time is the most important issue in the handover process. This handover scheme aims to utilize the channel efficiently and apply such a procedure to reduce the time it takes to scan the neighboring access stations. TM uses MAC and physical layer (PHY) specific information in the interface metric and maintains a separate path to destination by applying an alternative interface operation. Simulation tests and comparisons with existing multi-homed protocols and handover schemes demonstrate the effectiveness of incorporating the medium dependent parameters. Moreover, show that suggested schemes, have shown better performance in terms of end-to-end delay and throughput, with efficiency up to 40% in specific test scenarios

Energy-efficient vertical handover parameters, classification and solutions over wireless heterogeneous networks: a comprehensive survey

In the last few decades, the popularity of wireless networks has been growing dramatically for both home and business networking. Nowadays, smart mobile devices equipped with various wireless networking interfaces are used to access the Internet, communicate, socialize and handle short or long-term businesses. As these devices rely on their limited batteries, energy-efficiency has become one of the major issues in both academia and industry. Due to terminal mobility, the variety of radio access technologies and the necessity of connecting to the Internet anytime and anywhere, energy-efficient handover process within the wireless heterogeneous networks has sparked remarkable attention in recent years. In this context, this paper first addresses the impact of specific information (local, network-assisted, QoS-related, user preferences, etc.) received remotely or locally on the energy efficiency as well as the impact of vertical handover phases, and methods. It presents energy-centric state-of-the-art vertical handover approaches and their impact on energy efficiency. The paper also discusses the recommendations on possible energy gains at different stages of the vertical handover process