Search results for "ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS"
showing 10 items of 449 documents
Radio network aspects
2006
Publisher Summary This chapter reviews the mobile radio access network reference scenarios (MORANS)—used to study the performance of the radio cellular networks related to UMTS and the methodologies for the radio network performance evaluation, including the theoretical connectivity models,. It discusses the techniques for radio network optimization such as the packet scheduling for cellular systems or system capacity maximization through the use of multiple antennas. . In order to perform system simulations, reference values for the main parameters characterizing a WCDMA network, are required. MORANS is used for the identification of such parameters. The parameters are classified in two gr…
Testing the H.264 error-resilience on wireless ad-hoc networks
2004
The purpose of this paper is to provide a framework to tune and evaluate the performance of the H.264 codec in 802.11b wireless ad-hoc networks. The codec's error-resilience features are measured under stress conditions typical to these networks, and the most critical parameters are presented. We present solutions concerning the random packet loss problem and show how to quickly recover from packet loss bursts.
A space-division time-division multiple access scheme for high throughput provisioning in WLANs
2005
Directional antennas may dramatically increase the capacity of a Wireless LAN by allowing several stations to simultaneously communicate. Since deployment of directive/smart antennas on the customer's terminals is awkward (for technological, cost, robustness, and convenience reasons) it is of interest to deploy advanced antenna solutions only at the Access Point. When omnidirectional transmissions are used at the Mobile Stations, the asynchronous nature of the 802.11 MAC handshake structurally limits the possibility to exploit spatial reuse. Significant throughput enhancements can be achieved only at the expense of redesigning (part of) the 802.11 MAC protocol: mainly a form of synchronizat…
Using MANET Protocols in Wireless Sensor and Actor Networks
2008
Although there are several routing protocols for wireless sensor and actor networks (WSAN), none of them have became standard. Now, there are several standard protocols for mobile ad hoc networks (MANET) that have been developed for devices with higher computing features than the sensor nodes. On the other hand, one of the main characteristics of the MANET protocols is their scalability. In this paper, we show the performance of a WSAN, when MANET protocols are used, for several topologies. We will discuss and evaluate which standard protocol is the best one depending on the number of nodes in the topology and depending on their mobility. Finally we will show their comparison. As far as we …
A MANET Autoconfiguration System based on Bluetooth Technology
2006
The availability of both Wi-Fi and Bluetooth technologies on currently available devices offers the possibility to combine both in order to make the most out of their capabilities. In this paper we propose using Bluetooth technology to solve the configuration problem of the terminals conforming an IEEE 802.11-based ad-hoc network. The main objective of mobile ad- hoc networks (MANETs) is to extend the connectivity range of nodes through packet forwarding, thereby avoiding the use of a fixed infrastructure. However, since configuration of nodes is a complex issue, we provide a fast and reliable solution to auto-configure MANET terminals. Our solution is adequate for the quick setup and deplo…
Streaming for vehicular users via elastic proxy buffer management
2004
In this article we refer to the market of vehicular networks, where groups of customers located in the same public vehicle (e.g., a train or bus) connect to a terrestrial network through a wireless/satellite backbone link. Elastic buffering is a proxy management technique devised to decouple the multimedia information retrieval rate on the network backbone from the playout streaming rate at the user terminal. It has been shown in the past that the application of elastic buffering mechanisms in terrestrial networks brings significant advantages in terms of network effectiveness. We show that elastic buffering is an extremely effective means to reduce, or even eliminate, streaming service out…
On the Provisioning of Mobile Digital Terrestrial TV Services to Vehicles With DVB-T
2012
[EN] Most of the DVB-T (Digital Video Broadcasting -Terrestrial) networks deployments worldwide have been designed for fixed rooftop antennas and high transmission capacity, not providing good coverage level for vehicular mobile reception. This letter analyzes how to combine different technical solutions, so far studied individually, in order to increase the robustness of the transmission for vehicular reception to provide in-band mobile services. In particular, we consider: receive antenna diversity, hierarchical modulation, and Application Layer Forward Error Correction (AL-FEC). Performance evaluation results have been obtained by means of simulations, laboratory tests, and field measure…
BEP analysis of M-ary PSK modulation schemes over double Rice fading channels with EGC
2010
In this article, the performance of M-ary phase shift keying (PSK) modulation schemes over mobile-to-mobile (M2M) fading channels with equal gain combining (EGC) in cooperative networks is analyzed. Narrowband M2M fading channels under line-of-sight (LOS) propagation conditions are modeled as double Rice processes. A dual-hop amplify-and-forward relay network, where LOS components can exist in the transmission links between the source mobile station and the destination mobile station via K mobile relays, is studied. Here, the average bit error probability (BEP) is utilized to evaluate the performance of Mary PSK modulation schemes. A simple analytical approximation for the average BEP of M-…
MCMIPv6: Multicast Configuration-based Mobile IPv6 protocol
2010
International audience; Mobile IPv6 (MIPv6) and its basic extension for network mobility NEMO were initially designed to manage the mobility of device users and networks respectively while maintaining a permanent IP address. Nevertheless, the different MIPv6's experiments have shown many lacks in case of high mobility of nodes such as in vehicular networks. To overcome these lacks, many solutions have been proposed by the research community. The most famous ones are HMIPv6 and FMIPv6 tackling each a specific issue. On the one hand, FMIPv6 introduces a solution to effectively minimize the L2/L3 latency and avoid the packets losses during the handover procedure. On the other hand, HMIPv6 is e…
Group mobility impact over TCP and CBR traffic in mobile ad hoc networks
2004
We present an analysis of the effect that mobility models have over the performance of a mobile ad hoc network. We concentrate on group mobility because there is a growing attention on the development and evaluation of MANET's approach applied to personal area networks (PANs), especially based on Bluetooth technology. We investigate the effect that the mobility model has on the performance of CBR traffic and TCP traffic. We propose four different group mobility models and describe a mobility pattern generator called grcmob to be used with the ns-2 simulator. We perform a thorough evaluation of a MANET behavior using as a reference the behavior obtained with the random waypoint mobility mode…