Quality Of Service Extensions Research Articles

Performance Evaluation of 802.11e with typical data rates

The type of the applications for which Internet is being used has changed dramatically over the years. Some of the applications require the network to provide Quality of Service (QOS). IEEE 802.11e is the QOS extension of the Wireless Local Area Network standard IEEE 802.11. This paper does the performance evaluation of 802.11e with voice, video, data and background traffic. The data rates and packet sizes considered are those used in the real environment. The results show that the 802.11e achieves service differentiation. NS2 is used as a network simulator. Keywords -QOS, Normalized throughput, IEEE 802.11e, ns2, evaluation Nigerian Journal of Technological Research vol 7(1) 2012

Multipoint Relay Selections with QoS Support in Link State Routing Protocol for Multi-Hop Wireless Networks

In OLSR (Optimized Link State Routing Protocol), the multipoint relay mechanism has been introduced to minimize routing overhead for flooding control traffic. In order to achieve as low a routing overhead as possible, the selection of MPRs (multipoint relays) is designed to limit the overall number of such relays in the network. OLSR provides the shortest paths in terms of hops; however, it does not take into account the QoS (quality of service) requirements. Therefore, QOLSR (Quality OLSR), which adds a QoS extension to the OLSR, has been proposed. Although QOLSR provides the best QoS path, its selection process does not consider the number of MPRs, which causes an increase in the routing overhead. In this paper, we focus on the selection process of MPRs in link state QoS routing protocol. We propose three heuristics for high-efficiency selections: MIMS, MQES, and MCIS. The basic approach of these selections is to determine a smaller set of MPRs that provide better QoS paths between any two nodes. The main objective in doing so is to maximize the QoS effect while limiting the routing overhead. In addition, we evaluate the performance of the routing protocols with the proposed selections by simulation. The results indicate that MIMS and MCIS achieve high-efficiency selection; as compared to QOLSR, MIMS reduces the maintenance cost by 30%, while the throughput of the resultant path is decreased by 13%, and MCIS reduces the cost by 21% without any decrease in the throughput.

A QoS Driven Web Service Composition Method Based on ESGA (Elitist Selection Genetic Algorithm) with an Improved Initial Population Selection Strategy

With more and more web services being applied, the quality of service (QoS) becomes an important criterion in a service selection. We propose a UDDI process with QoS extension to support quality requests. Service providers can send functional and QoS information to the UDDI registry. As a component of the UDDI registry, the QoS calculator calculates the QoS value of each service to decide the optimal service and send the information back to the UDDI registry. After receiving the requestor's feedback, the QoS calculator re-calculates QoS of the service. In a service composition, component services and the composed service should satisfy local and global restrictions respectively. The QoS of component services aggregate to QoS of the composed service according to an aggregation rule. The QoS parameters may conflict with each other, so this problem is actually a multi-objective optimization. A service selection can be seen as a path formation and each node of the path is a service class. A genetic algorithm can be used to solve complicated global optimization problems. It is proved that a simplex genetic algorithm cannot converge to optimal global solution but the elitist selection genetic algorithm (ESGA) can. So we use ESGA to solve this problem. We use integer encoding as the encoding rule. A composed service can be seen as a chromosome and a gene is an integer that represents a service number in its service class. We use an initial population selection strategy instead of the random initial population creation method. In the strategy, if the fitness of a new composed service is worse than the average fitness of the selected composed services, it should be abandoned, otherwise it should be kept. We coordinate these objectives by assigning a weight to each parameter and the fitness function is the weighted sum of QoS parameters. In the stage of genetic operation, the penalty function is subtracted from the fitness of the composed service if it does not satisfy the restrictions. We use the roulette wheel selection method, single point crossover operator, and uniform mutation operator as genetic operators. It is shown that this method has better performance than the method using ESGA through an experiment.

Adding Quality of Service Extensions to the Enhanced Associativity Based Routing Protocol for Mobile Ad Hoc Networks (MANET)

This paper described how to discover routes that can satisfy QoS service requirements by using extensions to the Enhanced Associativity Bases Routing Protocol (EABR). These extensions were added to the messages used during route discovery. These extensions specify the service requirements, which must be met by nodes re-broadcasting a route request or returning a route reply for a destination. The performance analysis of EABR with QoS support showed that more overhead was incurred when the intermediate node discover that it cannot support the level of the QoS requested.

Adding Quality of Service Extensions to the Enhanced Associativity Based Routing Protocol for Mobile Ad Hoc Networks (MANET)

Adding Quality of Service Extensions to the Enhanced Associativity Based Routing Protocol for Mobile Ad Hoc Networks (MANET)

Advertising Interdomain QoS Routing Information

To enable end-to-end quality-of-service (QoS) guarantees in the Internet, based on the border gateway protocol (BGP), interdomain QoS information advertising, and routing are important. However, little research has been done in this area so far. Two major challenges, scalability and heterogeneity, make the QoS extension to BGP difficult. In the existing routing schemes, static and instantaneous QoS metrics, such as link capacity and available bandwidth, are used to represent QoS routing information, but neither of them can solve the two challenges well. In this paper, BGP is extended to advertise available bandwidth and delay information of routes, but, instead of using the traditional deterministic metrics, a series of statistical metrics, available bandwidth index (ABI), delay index (DI), available bandwidth histogram (ABH), and delay histogram (DH), are defined and applied to QoS information advertising and routing. Two major contributions of the proposed statistical metrics are: 1) QoS information is abstracted into one or several probability intervals and, thus, the heterogeneous and dynamic QoS information can be represented more flexibly and precisely and 2) by capturing the statistical property of the detailed distribution of QoS information, these new metrics are efficient and they can highly decrease the message overhead in routing, thereby making the QoS advertising and routing scalable. Our extensive simulations confirm both contributions of the QoS extension to BGP very well. Moreover, besides BGP, these statistical metrics can be applied to other networks and protocols to represent QoS information in a more scalable and precise way.

End-to-end QoS routing framework for differentiated services networks

Differentiated services (DiffServ) is the latest model proposed by Internet engineering task force (IETF) to support quality of service (QoS) in the Internet. It has flexibility and scalability advantages over the earlier model, namely, integrated services (IntServ). Currently, the DiffServ model is the preferred architecture widely accepted by Internet providers and the networking research community. The goal of the DiffServ model is to avoid maintaining large amount of state information in core routers, and carry out aggregate resource reservation at edge routers. Therefore, DiffServ calls for a very different routing framework from IntServ. In this paper, we propose two new QoS-based routing algorithms under the single service, multiple options (SiMO) framework for DiffServ architectures. These are kth-shortest QoS routing (kthQoSR) and maximum energy value QoS routing (EVQoSR). We also introduce QoS extensions to OSPF and compare it to our SiMO routing protocols. Our core routing strategy in SiMO, kthQoSR, is executed at the path level and selects one or more routes from a set of computed routes according to defined selection metrics. On the other hand, EVQoSR is a link level, online distributed routing algorithm. Through extensive simulations, we demonstrate that our proposed SiMO routing framework can achieve better route qualities in terms of load balancing, and network throughput.