Bandwidth Issues - IT Library : ZDNet Asia

White Papers

Case Studies

Vendor Webcast

Show all content

Title Date Added Company

Bandwidth-Constrained Clustering in Ad Hoc Networks 0000-00-00 Lulea University of Technology

This paper presents a survey of the basic mechanisms and properties of existing clustering algorithms for wireless ad hoc networks. Based on this evaluation, the paper then proposed a new algorithm with improved stability and a lower communication overhead. This is partly achieved by using a maintenance function that modifies the existing clustering structure rather than building a new one from scratch. Preliminary simulations seem to indicate that the algorithm produces clusters of about the same size and stability as a comparable existing algorithm, while sending significantly fewer messages.

Tags: Software Engineering, Mobile - Wireless Communications

Scale-Lag Diversity Reception in Mobile Wideband Channels 0000-00-00 Ohio State University

This paper considers the effect of mobility on a wideband Direct Sequence Spread Spectrum (DSSS) communication system, and study a scale-lag Rake receiver capable of leveraging the diversity that results from mobility. A wideband signal has a large bandwidth-to center frequency ratio, such that the typical narrowband Doppler spread assumptions do not apply to mobile channels. Instead, the paper assumes a more general temporal scaling phenomenon, i.e., a dilation of the transmitted signal's time support. Such analysis applies, for example, to Ultra-Wideband (UWB) radio frequency channels and underwater wideband acoustic channels.

Tags: Mobile - Wireless Communications

Estimation of RTT and Bandwidth for Congestion Control Applications in Communication Networks 2007-08-04 KTH - Royal Institute of Technology

Heterogeneous communication networks with their variety of application demands, uncertain time-varying traffic load, and mixture of wired and wireless links pose several challenging problem in modeling and control. This paper focuses on the Round-Trip Time (RTT), which is a particularly important variable for efficient end-to-end congestion control, and on bandwidth estimation. Based on a simple aggregated model of the network, an algorithm combining a Kalman filter and a change detection algorithm is proposed for RTT estimation. It is illustrated on real data that this algorithm provides estimates of significantly better accuracy as compared to the RTT estimator currently used in TCP, especially in scenarios where new cross-traffic flows cause bottle-neck queues to rapidly build up which in turn induces rapid changes of the RTT.

Tags: TCP - IP

Improving Start-Up and Steady-State Behavior of TCP in High Bandwidth-Delay Product Networks 2007-08-01 Case Western Reserve University

It has been long known that the standard Transmission Control Protocol (TCP) yields limited performance in high bandwidth-delay product (BDP) networks due to its conservative Slow Start and Congestion Avoidance algorithms. This paper focuses on TCP modifications to improve both TCP's start-up and steady-state behavior. First, the paper proposes Jump Start, a new technique which has the potential to speedup the start-up of TCP by ignoring the Slow Start. It allows a higher initial sending rate but keeps the remaining of TCP unchanged. Second, EXP-TCP is introduced, a new TCP variant which replaces the additive-increase rule of the Congestion Avoidance with an exponential-increase algorithm. It decouples TCP efficiency control and fairness control to achieve both high performance and good fairness.

Tags: TCP - IP

On the Relation Between Bandwidth and Robustness of UWB Channel in Complex Confined Areas 2007-07-28 Universite Laval

Ultra-Wideband (UWB) communication has been the subject of extensive research in recent years due to its unique capabilities and potential applications, particularly in short-range multiple access wireless communications. However, many important aspects of UWB-based communication systems have not yet been thoroughly investigated. The propagation of UWB signals is the single most important issue with significant impacts on the future direction, scope, and generally the extent of the success of UWB technology. The objective of this dissertation is to obtain a quantitative analysis of the relation between robusteness and signal bandwidth of the UWB channel propagation in underground mines.

Tags: Broadband, Mobile - Wireless Communications

SEAD: Secure Efficient Distance Vector Routing for Mobile Wireless Ad Hoc Networks 0000-00-00 Carnegie Mellon University

An ad hoc network is a collection of wireless computers (nodes), communicating among themselves over possibly multihop paths, without the help of any infrastructure such as base stations or access points. This paper designs and evaluates the Secure Efficient Ad hoc Distance vector routing protocol (SEAD), a secure ad hoc network routing protocol based on the design of the Destination-Sequenced Distance-Vector routing protocol (DSDV). In order to support use with nodes of limited CPU processing capability, and to guard against Denial-of-Service (DoS) attacks in which an attacker attempts to cause other nodes to consume excess network bandwidth or processing time, it use efficient one-way hash functions and do not use asymmetric cryptographic operations in the protocol.

Tags: Wireless

A Bandwidth-on-Demand System Case-Study Based on GN2 Project Experiences 2007-07-16 GARR

The JRA3 Activity of GN2 project is heading to implement a multi-domain, heterogeneous technologies bandwidth reservation system for end users. During the design and implementation efforts of the last two years, project participants have come across a set of problems and decisions that are common for reservation systems. Having in mind the specific project objectives, supported by the knowledge and experience from similar efforts around the world, the JRA3 team has been working to identify the most suitable, and flexible approaches for inter-domain Bandwidth-on-Demand (BoD) provisioning issues. This paper presents the assumptions and decisions made so far, their background, pros and cons, and their consequences for the further project development.

Tags: Network Administration

TCP Prediction for Adaptive Applications 2007-07-15 Deutsche Telekom

Adaptive applications, such as real-time multimedia streaming applications, are increasingly using TCP as their underlying transport protocol. To adapt the content, an elastic application needs a prediction of the future available bandwidth. Unfortunately, the socket API does not allow an application to get information from the transport layer. Therefore, this paper proposes an approach where a monitor collects packet information from the network interface, creates a time series by sampling the packet information, and uses prediction models to assess the future available bandwidth.

Tags: TCP - IP

Bandwidth Provisioning in Infrastructure-Based Wireless Networks Employing Directional Antennas 2007-07-10 Pennsylvania State University

Motivated by the widespread proliferation of wireless networks employing directional antennas, the paper study the problem of provisioning bandwidth in such networks. Given a set of subscribers and one or more access points possessing directional antennas, the paper formalizes the problem of orienting these antennas in two fundamental settings; subscriber-centric, where the objective is to fairly allocate bandwidth among the subscribers; and provider-centric, where the objective is to maximize the revenue generated by satisfying the bandwidth requirements of subscribers. For both the problems, it first designs algorithms for a network with only one access point working under the assumption that the number of antennas does not exceed the number of non-interfering channels.

Tags: Wireless Internet, Mobile - Wireless Communications

Viewpointe Revolutionizes the Banking Industry, One Payment at a Time 2007-07-01 Verizon

Viewpointe has achieved success by developing an open, scalable archive solution that enables multiple companies to store infinite amounts of documents within the same platform - making the sharing of critical information possible. The company wanted to obtain a secure, flexible, and scalable solution and ensure bandwidth availability, performance, and efficiency. The challenge was to reduce the total cost of ownership. Leveraging its extensive managed service portfolio, Verizon Business designed and deployed a fully managed Extranet solution for Viewpointe, utilizing their managed IP VPN solution. Because it's a fully managed service, Viewpointe can leverage Verizon Business's engineering expertise and internal staff to manage, monitors, and maintain the solution, freeing up internal personnel to focus on their core business.

Tags: TCP - IP, VPNs

Jump to 1 2 3 4 5 [6] 7 8 9 10

Title	Date Added	Company
Bandwidth-Constrained Clustering in Ad Hoc Networks	0000-00-00	Lulea University of Technology
This paper presents a survey of the basic mechanisms and properties of existing clustering algorithms for wireless ad hoc networks. Based on this evaluation, the paper then proposed a new algorithm with improved stability and a lower communication overhead. This is partly achieved by using a maintenance function that modifies the existing clustering structure rather than building a new one from scratch. Preliminary simulations seem to indicate that the algorithm produces clusters of about the same size and stability as a comparable existing algorithm, while sending significantly fewer messages. Tags: Software Engineering, Mobile - Wireless Communications
Scale-Lag Diversity Reception in Mobile Wideband Channels	0000-00-00	Ohio State University
This paper considers the effect of mobility on a wideband Direct Sequence Spread Spectrum (DSSS) communication system, and study a scale-lag Rake receiver capable of leveraging the diversity that results from mobility. A wideband signal has a large bandwidth-to center frequency ratio, such that the typical narrowband Doppler spread assumptions do not apply to mobile channels. Instead, the paper assumes a more general temporal scaling phenomenon, i.e., a dilation of the transmitted signal's time support. Such analysis applies, for example, to Ultra-Wideband (UWB) radio frequency channels and underwater wideband acoustic channels. Tags: Mobile - Wireless Communications
Estimation of RTT and Bandwidth for Congestion Control Applications in Communication Networks	2007-08-04	KTH - Royal Institute of Technology
Heterogeneous communication networks with their variety of application demands, uncertain time-varying traffic load, and mixture of wired and wireless links pose several challenging problem in modeling and control. This paper focuses on the Round-Trip Time (RTT), which is a particularly important variable for efficient end-to-end congestion control, and on bandwidth estimation. Based on a simple aggregated model of the network, an algorithm combining a Kalman filter and a change detection algorithm is proposed for RTT estimation. It is illustrated on real data that this algorithm provides estimates of significantly better accuracy as compared to the RTT estimator currently used in TCP, especially in scenarios where new cross-traffic flows cause bottle-neck queues to rapidly build up which in turn induces rapid changes of the RTT. Tags: TCP - IP
Improving Start-Up and Steady-State Behavior of TCP in High Bandwidth-Delay Product Networks	2007-08-01	Case Western Reserve University
It has been long known that the standard Transmission Control Protocol (TCP) yields limited performance in high bandwidth-delay product (BDP) networks due to its conservative Slow Start and Congestion Avoidance algorithms. This paper focuses on TCP modifications to improve both TCP's start-up and steady-state behavior. First, the paper proposes Jump Start, a new technique which has the potential to speedup the start-up of TCP by ignoring the Slow Start. It allows a higher initial sending rate but keeps the remaining of TCP unchanged. Second, EXP-TCP is introduced, a new TCP variant which replaces the additive-increase rule of the Congestion Avoidance with an exponential-increase algorithm. It decouples TCP efficiency control and fairness control to achieve both high performance and good fairness. Tags: TCP - IP
On the Relation Between Bandwidth and Robustness of UWB Channel in Complex Confined Areas	2007-07-28	Universite Laval
Ultra-Wideband (UWB) communication has been the subject of extensive research in recent years due to its unique capabilities and potential applications, particularly in short-range multiple access wireless communications. However, many important aspects of UWB-based communication systems have not yet been thoroughly investigated. The propagation of UWB signals is the single most important issue with significant impacts on the future direction, scope, and generally the extent of the success of UWB technology. The objective of this dissertation is to obtain a quantitative analysis of the relation between robusteness and signal bandwidth of the UWB channel propagation in underground mines. Tags: Broadband, Mobile - Wireless Communications
SEAD: Secure Efficient Distance Vector Routing for Mobile Wireless Ad Hoc Networks	0000-00-00	Carnegie Mellon University
An ad hoc network is a collection of wireless computers (nodes), communicating among themselves over possibly multihop paths, without the help of any infrastructure such as base stations or access points. This paper designs and evaluates the Secure Efficient Ad hoc Distance vector routing protocol (SEAD), a secure ad hoc network routing protocol based on the design of the Destination-Sequenced Distance-Vector routing protocol (DSDV). In order to support use with nodes of limited CPU processing capability, and to guard against Denial-of-Service (DoS) attacks in which an attacker attempts to cause other nodes to consume excess network bandwidth or processing time, it use efficient one-way hash functions and do not use asymmetric cryptographic operations in the protocol. Tags: Wireless
A Bandwidth-on-Demand System Case-Study Based on GN2 Project Experiences	2007-07-16	GARR
The JRA3 Activity of GN2 project is heading to implement a multi-domain, heterogeneous technologies bandwidth reservation system for end users. During the design and implementation efforts of the last two years, project participants have come across a set of problems and decisions that are common for reservation systems. Having in mind the specific project objectives, supported by the knowledge and experience from similar efforts around the world, the JRA3 team has been working to identify the most suitable, and flexible approaches for inter-domain Bandwidth-on-Demand (BoD) provisioning issues. This paper presents the assumptions and decisions made so far, their background, pros and cons, and their consequences for the further project development. Tags: Network Administration
TCP Prediction for Adaptive Applications	2007-07-15	Deutsche Telekom
Adaptive applications, such as real-time multimedia streaming applications, are increasingly using TCP as their underlying transport protocol. To adapt the content, an elastic application needs a prediction of the future available bandwidth. Unfortunately, the socket API does not allow an application to get information from the transport layer. Therefore, this paper proposes an approach where a monitor collects packet information from the network interface, creates a time series by sampling the packet information, and uses prediction models to assess the future available bandwidth. Tags: TCP - IP
Bandwidth Provisioning in Infrastructure-Based Wireless Networks Employing Directional Antennas	2007-07-10	Pennsylvania State University
Motivated by the widespread proliferation of wireless networks employing directional antennas, the paper study the problem of provisioning bandwidth in such networks. Given a set of subscribers and one or more access points possessing directional antennas, the paper formalizes the problem of orienting these antennas in two fundamental settings; subscriber-centric, where the objective is to fairly allocate bandwidth among the subscribers; and provider-centric, where the objective is to maximize the revenue generated by satisfying the bandwidth requirements of subscribers. For both the problems, it first designs algorithms for a network with only one access point working under the assumption that the number of antennas does not exceed the number of non-interfering channels. Tags: Wireless Internet, Mobile - Wireless Communications
Viewpointe Revolutionizes the Banking Industry, One Payment at a Time	2007-07-01	Verizon
Viewpointe has achieved success by developing an open, scalable archive solution that enables multiple companies to store infinite amounts of documents within the same platform - making the sharing of critical information possible. The company wanted to obtain a secure, flexible, and scalable solution and ensure bandwidth availability, performance, and efficiency. The challenge was to reduce the total cost of ownership. Leveraging its extensive managed service portfolio, Verizon Business designed and deployed a fully managed Extranet solution for Viewpointe, utilizing their managed IP VPN solution. Because it's a fully managed service, Viewpointe can leverage Verizon Business's engineering expertise and internal staff to manage, monitors, and maintain the solution, freeing up internal personnel to focus on their core business. Tags: TCP - IP, VPNs