Quality Of Service Priority Research Articles

Modeling and Performance Evaluation of Multi-Class Queuing System with QoS and Priority Constraints

Many service providers often categorize their users into multi-classes, depending on their service requirements. Each class has strict quality of service (QoS) demands (e.g., minimum required service rate or transfer time) that must be ensured throughout its service. In some cases, priorities are also assigned in a multi-class user’s environment to ensure that the important class user shall be serviced first. In this paper, we have developed a novel Markov chain based analytical model to investigate and evaluate a multi-class queuing system with a strict QoS requirement and priority constraints. Experimental analysis is conducted for two users classes, i.e., class-1 (may be free/student users) and class-2 (may be paid/research users). Each class requests have strict QoS requirements in terms of the minimum required rate (MRR) that must be ensured throughout its lifetime once the request is admitted into the system. Secondly, class-2 requests have preemption priority over class-1, i.e., if there is no room for newly arriving class-2 requests, then one or more active flows of class-1 can be ejected in order to accommodate high-class requests. Model results are validated through simulation results and performance measures of our interest include blocking probability (BP) of individual classes and the overall system, effect of higher-class jobs on lower-class jobs, and link capacity utilization. The proposed model can be instrumental in developing advanced connection admission control (CAC), efficient resource dimensioning, and capacity planning of the queuing system.

Joint relay‐and‐antenna selection for cooperative non‐orthogonal multiple access

Non-orthogonal multiple access (NOMA) has been widely recognised as a promising technology due to its potential to achieve high spectral efficiency and massive connectivity. The authors study a multiple-relay multiple-input and multiple-output cooperative NOMA system. In particular, a joint relay-and-antenna selection (JRAS) scheme with coordinated direct and relay transmission is proposed, which makes it possible to maximise the instantaneous rate of far user with high quality ofservice (QoS) priority while guaranteeing the requirement of near user with low QoS priority. Then, closed-form expressions for outage probability are derived and asymptotic expressions for outage probability in the high signal-to-noise ratio regime are also obtained in order to provide further insights. Analysis results demonstrate that the proposed JRAS scheme significantly enhances the outage performance for cooperative NOMA, and simulation results are provided to verify the accuracy of theoretical analysis.

QoS-aware Service Composition Using Fuzzy Set Theory and Genetic Algorithm

The quality of service (QoS)-aware service composition problem is a lively topic of debate because of the fuzziness in the quality data and the user-oriented specific QoS requirements. The aim of this paper is to develop a model to select the most suitable service composition in a way that maximizes solutions expressed as functions over fuzzy/crisp QoS attributes, while satisfying user’s QoS requirements. In this paper, based on fuzzy set theory (FST) and genetic algorithm (GA), a triangular fuzzy genetic algorithm (TGA) is proposed for solving the service composition problem. The following set of strategies are presented: a quality model including crisp and fuzzy properties represented by triangular fuzzy numbers, a feasible method of normalizing the QoS matrix, aggregating formulas of each control structure for eight properties, a practicable method of defuzzification, a global best strategy with a fitness function which calculates the QoS priority vector and is considered as an objective evaluation criterion for selecting an optimal solution that meets user’s preferences best. Empirical comparisons with two algorithms on different scales of composite service indicate that TGA is highly competitive in regards to search capability, especially when the problem size is large. The results may be helpful to designers in selecting the best services for building a service-oriented system.

English

Different quality-of-service (QoS) required types of multimedia services and need a guaranteed service rate in wireless multimedia networks. When the number of user arrivals increases, bandwidth degradations may occur due to limited bandwidth nature of cellular wireless networks. The bandwidth that should be assigned to user cannot be met for QoS provisioning in congested network. In this paper, a priority-based call admission control scheme with bandwidth adaptation is proposed to provide the required QoS to service users and to utilize the bandwidth effectively. An analytical model is developed to evaluate the numerical results. Proposed scheme differentiates the services according to their call-level QoS priorities as non-prioritized and prioritized calls and provides the satisfactory QoS under the upper bound limitations. Further, bandwidth adaptation policy maintains the higher performance results in terms of blocking and dropping probabilities, resource utilization and throughput of non-prioritized calls.   Key words:  Priority-based call admission control (CAC), bandwidth adaptation, quality-of-service (QoS), bandwidth allocation.

Cellular Multiuser Two-Way MIMO AF Relaying via Signal Space Alignment: Minimum Weighted SINR Maximization

In this paper, we consider linear MIMO transceiver design for a cellular two-way amplify-and-forward relaying system consisting of a single multi-antenna base station, a single multi-antenna relay station, and multiple multi-antenna mobile stations (MSs). Due to the two-way transmission, the MSs could suffer from tremendous multi-user interference. We apply an interference management model exploiting signal space alignment and propose a transceiver design algorithm, which allows for alleviating the loss in spectral efficiency due to half-duplex operation and providing flexible performance optimization accounting for each user's quality of service priorities. Numerical comparisons to conventional two-way relaying schemes based on bidirectional channel inversion and spatial division multiple access-only processing show that the proposed scheme achieves superior error rate and average data rate performance.

A linguistic decision support model for QoS priorities in networking

Networking resources and technologies are mission-critical in organizations, companies, universities, etc. Their relevance implies the necessity of including tools for Quality of Service (QoS) that assure the performance of such critical services. To address this problem and guarantee a sufficient bandwidth transmission for critical applications/services, different strategies and QoS tools based on the administrator’s knowledge may be used. However it is common that network administrators might have a nonrealistic view about the needs of users and organizations. Consequently it seems convenient to take into account such users’ necessities for traffic prioritization even though they could involve uncertainty and subjectivity. This paper proposes a linguistic decision support model for traffic prioritization in networking, which uses a group decision making process that gathers user’s needs in order to improve organizational productivity. This model manages the inherent uncertainty, imprecision and vagueness of users’ necessities, modeling the information by means of linguistic information and offering a flexible framework that provides multiple linguistic scales to the experts, according to their degree of knowledge. Thereby, this decision support model will consist of two processes: (i) A linguistic decision analysis process that evaluates and assesses priorities for QoS of the network services according to users and organizations’ necessities. (ii) A priority assignment process that sets up the network traffic in agreement with the previous values.

On the Tradeoff Between Energy Saving and QoS Support for Video Delivery in EEE-Based FiWi Networks Using Real-World Traffic Traces

There is a tradeoff between energy saving and performance in green networks since energy saving is generally achieved by rerouting packets along a substitute path with more hops to put low-load nodes to sleep or assembling several packets before sending them to reduce the number of wake and sleep time intervals of transmitting ports. Fiber-Wireless (FiWi) access networks must be able to transport video traffic in an efficient way due to the fact that video will account for the largest part of global consumer traffic. To reduce the energy consumption of FiWi networks and guarantee the performance of video applications, issues related to the energy-efficient Quality-of-Service (QoS) support for video delivery in IEEE 803.3az Energy Efficient Ethernet (EEE)-based FiWi access networks are addressed in this paper. We extend EEE packet coalescing by considering QoS priorities and the shared nature of FiWi networks and improve the QoS support for video delivery by proposing a green QoS differentiated routing strategy. In addition, to better evaluate the performance of our scheme in a real-world setting, we carry out traffic measurements for the research on EEE-based networks and use them in our simulations. Our results show that the proposed scheme can effectively guarantee video delivery and reduce the energy consumption of EEE-based FiWi access networks.

MAC-Frame Receiving-Opportunity Control for Flow QoS in Wireless LANs

QoS (Quality of Service) control in WLAN (IEEE802.1 Wireless LAN) is becoming increasingly important because WLAN is widely deployed as an access network and also plays a key role in providing seamless QoS communication between wired networks and wireless terminals. Although previous research has attempted to increase total throughput or available bandwidth in WLAN, few studies have treated individual TCP/UDP flow QoS. EDCA in IEEE802.11e might provide prioritized QoS functions that would partially address this problem. However, in uplink flow, which is defined as data moving from a terminal toward an Access Point, EDCA has limitations. These manifest themselves both across classes and in differentiated QoS control between terminals in the same class. Furthermore, 802.11e requires modification of terminals as well as other alterations proposed by other researchers. Instead of 802.11e or other modifications of 802.11, we propose an approach to controlling QoS that requires no terminal modifications or installation of additional soft-ware/hardware. The proposed idea is MAC-frame Receiving-Opportunity Control (ROC), in which a MAC (Media Access Control) frame is completely delivered only if it has sufficiently high priority; otherwise either the MAC frame is discarded or an Acknowledge (ACK) to the frame is not sent. The frame that was discarded is forced to accept a back-off waiting time for retransmission, consistent with 802.11DCF. This results in QoS degradation for low priority flows and eventually results in QoS improvements for high priority flows. Performance evaluation shows that the ROC causes some performance degradation in total WLAN throughput but can achieve not only QoS priority control but also arbitrary throughput performance. In particular, the ROC (in the MAC layer) can also permit different throughputs for high priority and low priority flows, conditioned on control processes in other layers. These may include rate adaptation (in the MAC layer) and TCP congestion control (in the TCP layer).

Improving the Quality of Service Guarantee in an Asynchronous Transfer Mode (ATM) Network

This study presents a technique for improving the quality of service (QoS ) guarantee in an ATM network. In the proposed model, it was assumed that high priority traffic have been allocated a switch resource to guarantee a given QoS and low priority cells are allowed to enter the buffer, to improve the exploitation of reserved resources. The proposed technique was backed up with an exact analytical model for evaluating the cell loss probability of high and low priority cells. The performance of the proposed model was evaluated using C++ programming language. The results of the simulation shows that the loss probability of both high and low cells reduces as the buffer capacity increase and that the performance of high priority cell is better than that of low priority cell.

Flexible call admission control for multiclass services in wireless LANs

A call admission control algorithm must try to admit as many calls as possible provided the Quality of Service (QoS) requirements can be met without violating those of previously admitted calls. In this paper, we propose a simple and effective call admission control algorithm and its associated resource allocation mechanism, which together will be referred to as the Flexible Call Admission Control (FAC), for the recently proposed Multi-Pattern (MP) Wireless Local Area Networks (WLANs). The proposed scheme effectively takes the advantages of flexible pattern assignment in MP WLANs and the rate-adaptive feature of multimedia services to support multiple classes of traffic with diverse QoS requirements and priority levels. With the use of an innovative performance estimation mechanism, the proposed admission control and resource allocation algorithm has considerably lower complexity than that of the existing schemes. Simulation results have demonstrated that the use of MP FAC provides much higher system throughput and lower call blocking probability. It should be emphasised that this scheme, although designed for MP WLANs, also works well with existing standard WLANs.

Optimized QoS priority routing for service tunability and overhead reduction using swarm based active network scheme

As technology is moving towards the pervasive computing environments with billions of users, devices, and services, the Quality of Service (QoS) becomes a necessity and an essential element for end-to-end real time applications. The concept of active network has been recently adopted in order to provide a framework in which executable code within data packets executes upon intermediate network nodes and to facilitate delay services in the network. This paper describes the combination of the active network concept with swarm based control method called Swarm-based Active Network scheme for optimized QoS priority routing. This hybrid scenario is using the bandwidth clustering approach in which packets are following the predetermined path allocated by swarm based packets (embedded swarms). This mechanism enables the adaptation of the system to new conditions, as well as additional information to be passed to neighboring nodes for which information is embodied in transmitted packets. The proposed swarm based scheme does not require message brokers to fulfill QoS demands issued by applications. Additionally, it computes efficiently the available resources that satisfy the QoS requirements of requests. Thorough examination is made for the performance and reliability of the Swarm based Active Network scheme for different traffic measures and for the corresponding QoS offered in terms of the end-to-end delay, available bandwidth and packet loss. This scheme offers a decentralized way to efficiently increase the overall network utilization, allowing scalability and efficient usage of network bandwidth.

Dynamic handoff scheme in differentiated QoS wireless multimedia networks

Handoff is one of the key elements in ensuring quality of service (QoS) in mobile wireless networks. Handoff connections generally have higher priority than new connections. Traditional reservation policies that reserve some channels for handoff connections are not adaptive to traffic load changes. This paper proposes a new Dynamic Guard Channel (DGC) scheme, which (1) combines differentiated QoS service model and priority handoff mechanism; (2) provides fairness for differentiated QoS services; (3) adapts to various traffic loads because it adopts passive feedback mechanism if we assume a stationary distribution for the mean arrival times; (4) does not need to exchange state information among different cells, so it is easy to implement and is simple enough to be used in real world scenarios; (5) utilizes network resource efficiently and puts a bound on each service blocking probability. The simulation results show that the ratios among different QoS service probabilities are guaranteed to predefined values and system utilization is improved.