1,830 research outputs found
Implementation of QoS onto virtual bus network
Quality of Service (QoS) is a key issue in a multimedia environment because multimedia applications are sensitive to delay. The virtual bus architecture is a hierarchical access network structure that has been proposed to simplify network signaling. The network employs an interconnection of hierarchical database to support advanced routing of the signaling and traffic load. Therefore, the requirements and management of quality of service is important in the virtual bus network particularly to support multimedia applications. QoS and traffic parameters are specified for each class type and the OMNeT model has been described
Distributed QoS Guarantees for Realtime Traffic in Ad Hoc Networks
In this paper, we propose a new cross-layer framework, named QPART ( QoS br>rotocol for Adhoc Realtime Traffic), which provides QoS guarantees to real-time multimedia applications for wireless ad hoc networks. By adapting the contention window sizes at the MAC layer, QPART schedules packets of flows according to their unique QoS requirements. QPART implements priority-based admission control and conflict resolution to ensure that the requirements of admitted realtime flows is smaller than the network capacity. The novelty of QPART is that it is robust to mobility and variances in channel capacity and imposes no control message overhead on the network
Resource Allocation in Wireless Networks with RF Energy Harvesting and Transfer
Radio frequency (RF) energy harvesting and transfer techniques have recently
become alternative methods to power the next generation of wireless networks.
As this emerging technology enables proactive replenishment of wireless
devices, it is advantageous in supporting applications with quality-of-service
(QoS) requirement. This article focuses on the resource allocation issues in
wireless networks with RF energy harvesting capability, referred to as RF
energy harvesting networks (RF-EHNs). First, we present an overview of the
RF-EHNs, followed by a review of a variety of issues regarding resource
allocation. Then, we present a case study of designing in the receiver
operation policy, which is of paramount importance in the RF-EHNs. We focus on
QoS support and service differentiation, which have not been addressed by
previous literatures. Furthermore, we outline some open research directions.Comment: To appear in IEEE Networ
Multipath routing and QoS provisioning in mobile ad hoc networks
PhDA Mobile Ad Hoc Networks (MANET) is a collection of mobile nodes that can
communicate with each other using multihop wireless links without utilizing any
fixed based-station infrastructure and centralized management. Each mobile node
in the network acts as both a host generating flows or being destination of flows
and a router forwarding flows directed to other nodes.
Future applications of MANETs are expected to be based on all-IP
architecture and be capable of carrying multitude real-time multimedia
applications such as voice and video as well as data. It is very necessary for
MANETs to have an efficient routing and quality of service (QoS) mechanism to
support diverse applications.
This thesis proposes an on-demand Node-Disjoint Multipath Routing protocol
(NDMR) with low broadcast redundancy. Multipath routing allows the
establishment of multiple paths between a single source and single destination
node. It is also beneficial to avoid traffic congestion and frequent link breaks in
communication because of the mobility of nodes. The important components of
the protocol, such as path accumulation, decreasing routing overhead and
selecting node-disjoint paths, are explained. Because the new protocol
significantly reduces the total number of Route Request packets, this results in an
increased delivery ratio, smaller end-to-end delays for data packets, lower control
overhead and fewer collisions of packets.
Although NDMR provides node-disjoint multipath routing with low route
overhead in MANETs, it is only a best-effort routing approach, which is not
enough to support QoS. DiffServ is a standard approach for a more scalable way
to achieve QoS in any IP network and could potentially be used to provide QoS
in MANETs because it minimises the need for signalling. However, one of the
biggest drawbacks of DiffServ is that the QoS provisioning is separate from the
routing process. This thesis presents a Multipath QoS Routing protocol for
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supporting DiffServ (MQRD), which combines the advantages of NDMR and
DiffServ. The protocol can classify network traffic into different priority levels
and apply priority scheduling and queuing management mechanisms to obtain
QoS guarantees
IP-based virtual private networks and proportional quality of service differentiation
IP-based virtual private networks (VPNs) have the potential of delivering cost-effective, secure, and private network-like services. Having surveyed current enabling techniques, an overall picture of IP VPN implementations is presented.
In order to provision the equivalent quality of service (QoS) of legacy connection-oriented layer 2 VPNs (e.g., Frame Relay and ATM), IP VPNs have to overcome the intrinsically best effort characteristics of the Internet. Subsequently, a hierarchical QoS guarantee framework for IP VPNs is proposed, stitching together development progresses from recent research and engineering work.
To differentiate IP VPN QoS, the proportional QoS differentiation model, whose QoS specification granularity compromises that of IntServ and Diffserv, emerges as a potential solution. The investigation of its claimed capability of providing the predictable and controllable QoS differentiation is then conducted.
With respect to the loss rate differentiation, the packet shortage phenomenon shown in two classical proportional loss rate (PLR) dropping schemes is studied. On the pursuit of a feasible solution, the potential of compromising the system resource, that is, the buffer, is ruled out; instead, an enhanced debt-aware mechanism is suggested to relieve the negative effects of packet shortage. Simulation results show that debt-aware partially curbs the biased loss rate ratios, and improves the queueing delay performance as well.
With respect to the delay differentiation, the dynamic behavior of the average delay difference between successive classes is first analyzed, aiming to gain insights of system dynamics. Then, two classical delay differentiation mechanisms, that is,proportional average delay (PAD) and waiting time priority (WTP), are simulated and discussed. Based on observations on their differentiation performances over both short and long time periods, a combined delay differentiation (CDD) scheme is introduced. Simulations are utilized to validate this method.
Both loss and delay differentiations are based on a series of differentiation parameters. Though previous work on the selection of delay differentiation parameters has been presented, that of loss differentiation parameters mostly relied on network operators\u27 experience. A quantitative guideline, based on the principles of queueing and optimization, is then proposed to compute loss differentiation parameters. Aside from analysis, the new approach is substantiated by numerical results
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