Performance Tuning of Dual-priority Delta Networks through Queuing Scheduling Disciplines

Differentiated Services (DiffServ) and other scheduling strategies are now widespread in the traditional, “best effort” Internet. These Internet Architectures offer Quality of Service (QoS) guarantees for important customers at the same time as supporting less critical applications of lower priority. Strict priority queuing (PQ), weighted round robin (WRR), and class-based weighted fair queuing (CBWFQ) are three common scheduling disciplines for differentiation of services in telecommunication networks. In this paper, a comparative performance study of the above PQ, WRR and CBWFQ queuing scheduling policies applied on a double-buffered, 6-stage Multistage Interconnection Network (MIN) that natively supports a 2-class priority mechanism is presented and analyzed using simulation experiments. We also consider a 10-stage MIN, to validate that the conclusions drawn from the 6-stage MIN apply to MINs of different sizes. The findings of this paper can be used by MIN designers to optimally configure their networks

A Fair and Efficient Packet Scheduling Scheme for IEEE 802.16 Broadband Wireless Access Systems

This paper proposes a fair and efficient QoS scheduling scheme for IEEE 802.16 BWA systems that satisfies both throughput and delay guarantee to various real and non-real time applications. The proposed QoS scheduling scheme is compared with an existing QoS scheduling scheme proposed in literature in recent past. Simulation results show that the proposed scheduling scheme can provide a tight QoS guarantee in terms of delay, delay violation rate and throughput for all types of traffic as defined in the WiMAX standard, thereby maintaining the fairness and helps to eliminate starvation of lower priority class services. Bandwidth utilization of the system and fairness index of the resources are also encountered to validate the QoS provided by our proposed scheduling scheme

Analysis and Evaluation of Quality of Service (QoS) Router using Round Robin (RR) and Weighted Round Robin (WRR)

The paper discuses a scheduling system for providing Quality of service (Qos) guaranteed in a network using Round Robin (RR) and Weighted Round Robin. It illustrates the simulation and analysis of data by evaluating the performance of Round Robin (RR) and Weighted Round Robin (WRR) schedulers. The evaluation and analysis of this schedulers' is based on different parameters such as the throughput, loss rate, fairness, jitter and delay Also, in analysis and evaluation of the two scheduling using different charts to demonstrate the effects of each parameter in order to decide an efficient algorithm between Round Robin (RR) and Weighted Round Robin (WRR.).The simulated output of the experiment enabled us to determine different result of parameter used and proof the schedulers that are best to used and that will help in improving the Qos in differentiated services. Keywords: Quality of Service(QoS), Round Robin (RR), Weighted Round Robin(WRR), Throughput, Scheduling, loss rate, fairness, jitter and delay

A quality of service architecture for WLAN-wired networks to enhance multimedia support

Includes abstract.Includes bibliographical references (leaves 77-84).The use of WLAN for the provision of IP multimedia services faces a number of challenges which include quality of service (QoS). Because WLAN users access multimedia services usually over a wired backbone, attention must be paid to QoS over the integrated WLAN-wired network. This research focuses on the provision of QoS to WLAN users accessing multimedia services over a wired backbone. In this thesis, the IEEE 802.11-2007 enhanced data channel access (EDCA) mechanism is used to provide prioritized QoS on the WLAN media access control (MAC) layer, while weighted round robin (WRR) queue scheduling is used to provide prioritized QoS at the IP layer. The inter-working of the EDCA scheme in the WLAN and the WRR scheduling scheme in the wired network provides end-to-end QoS on a WLAN-wired IP network. A mapping module is introduced to enable the inter-working of the EDCA and WRR mechanisms

Operational and Performance Issues of a CBQ router

The use of scheduling mechanisms like Class Based Queueing (CBQ) is expected to play a key role in next generation multiservice IP networks. In this paper we attempt an experimental evaluation of ALTQ/CBQ demonstrating its sensitivity to a wide range of parameters and link layer driver design issues. We pay attention to several CBQ internal parameters that affect performance drastically and particularly to “borrowing”, a key feature for flexible and efficient link sharing. We are also investigating cases where the link sharing rules are violated, explaining and correcting these effects wheneverpossible. Finally we evaluateCBQ performance and make suggestions for effective deployment in real networks.

A Priority-based Fair Queuing (PFQ) Model for Wireless Healthcare System

Healthcare is a very active research area, primarily due to the increase in the elderly population that leads to increasing number of emergency situations that require urgent actions. In recent years some of wireless networked medical devices were equipped with different sensors to measure and report on vital signs of patient remotely. The most important sensors are Heart Beat Rate (ECG), Pressure and Glucose sensors. However, the strict requirements and real-time nature of medical applications dictate the extreme importance and need for appropriate Quality of Service (QoS), fast and accurate delivery of a patient’s measurements in reliable e-Health ecosystem. As the elderly age and older adult population is increasing (65 years and above) due to the advancement in medicine and medical care in the last two decades; high QoS and reliable e-health ecosystem has become a major challenge in Healthcare especially for patients who require continuous monitoring and attention. Nevertheless, predictions have indicated that elderly population will be approximately 2 billion in developing countries by 2050 where availability of medical staff shall be unable to cope with this growth and emergency cases that need immediate intervention. On the other side, limitations in communication networks capacity, congestions and the humongous increase of devices, applications and IOT using the available communication networks add extra layer of challenges on E-health ecosystem such as time constraints, quality of measurements and signals reaching healthcare centres. Hence this research has tackled the delay and jitter parameters in E-health M2M wireless communication and succeeded in reducing them in comparison to current available models. The novelty of this research has succeeded in developing a new Priority Queuing model ‘’Priority Based-Fair Queuing’’ (PFQ) where a new priority level and concept of ‘’Patient’s Health Record’’ (PHR) has been developed and integrated with the Priority Parameters (PP) values of each sensor to add a second level of priority. The results and data analysis performed on the PFQ model under different scenarios simulating real M2M E-health environment have revealed that the PFQ has outperformed the results obtained from simulating the widely used current models such as First in First Out (FIFO) and Weight Fair Queuing (WFQ). PFQ model has improved transmission of ECG sensor data by decreasing delay and jitter in emergency cases by 83.32% and 75.88% respectively in comparison to FIFO and 46.65% and 60.13% with respect to WFQ model. Similarly, in pressure sensor the improvements were 82.41% and 71.5% and 68.43% and 73.36% in comparison to FIFO and WFQ respectively. Data transmission were also improved in the Glucose sensor by 80.85% and 64.7% and 92.1% and 83.17% in comparison to FIFO and WFQ respectively. However, non-emergency cases data transmission using PFQ model was negatively impacted and scored higher rates than FIFO and WFQ since PFQ tends to give higher priority to emergency cases. Thus, a derivative from the PFQ model has been developed to create a new version namely “Priority Based-Fair Queuing-Tolerated Delay” (PFQ-TD) to balance the data transmission between emergency and non-emergency cases where tolerated delay in emergency cases has been considered. PFQ-TD has succeeded in balancing fairly this issue and reducing the total average delay and jitter of emergency and non-emergency cases in all sensors and keep them within the acceptable allowable standards. PFQ-TD has improved the overall average delay and jitter in emergency and non-emergency cases among all sensors by 41% and 84% respectively in comparison to PFQ model

Delay tolerant networks with traffic differentiation capabilities

Dissertação de mestrado em Engineering of Computer Networks and Telematic ServicesIn the last few decades, an increasing growth of Internet usage was witnessed worldwide. However, infrastructures do not always allow the existence of Internet connectivity everywhere. Therefore, to address this issue, the concept of Delay Tolerant Networks (DTNs) was developed. DTNs purpose is to provide a different level of intermittent connectivity, dissimulating connection problems that arise in complex connectivity scenarios. Examples of such scenarios are, for instance, cities, where cars exchange information about their location; in underdeveloped countries, where Internet is inexistent; in freeways, where is not viable to provide infrastructures for a continuous connectivity, but cars, tolls, and services need to be aware of each other. Thus, DTNs constitute a possible solution for all the aforementioned communication environments. However, DTNs still faces some obstacles in terms of delivering a service with quality as it lacks specific mechanisms, such as traffic differentiation. Traffic differentiation is essential to provide different levels of service quality regarding delivering of messages. Current proposals to improve service delivery through traffic differentiation on DTNs are still under development or lack the proper testing and simulation. The main focus of these proposals is on buffer management mechanisms at each DTN node, instead of message prioritisation mechanisms. Message prioritisation allows some messages to be prioritised over others, improving the delivery rate and, therefore, increasing the probability of a message being correctly delivered. The present thesis implements traffic differentiation in DTNs based on prioritisation strategies, assuming a clear alternative to other buffer management proposals and message prioritisation. Using The One simulation tool, three popular DTNs routing protocols (Epidemic, Spray & Wait, and PRoPHET) are adapted to comply with traffic differentiation. The DTNs traffic prioritisation objective is achieved by designing, implementing and testing four distinct algorithms that classify and order messages according to their priority levels. These algorithms are based and extend some traditional traffic differentiation mechanisms, namely the well-known Priority Queuing and Weighted Round Robin strategies. Results from the simulation tests corroborate that the delivery rate of the messages is affected according to their priorities. Specifically, the simulation shows an increase in the delivery rate of high priority messages, with low impact on the total number of messages delivered, comparatively to the same scenario without differentiation capabilities. To conclude, DTNs can effectively benefit from traffic differentiation based on message prioritisation techniques, being a promising approach to improve service quality levels in such scenarios.Nas últimas décadas assistiu-se a um aumento crescente no uso da internet. Contudo, as infra-estruturas nem sempre permitem uma ligação à internet. Assim, para enfrentar este desafio, o conceito de Delay Tolerant Networks (DTN) foi desenvolvido. O objetivo das DTN é providenciar diferentes níveis de ligação intermitente, atenuando os problemas de ligação que surgem em cenários de conectividade complexa. Exemplos de tais cenários incluem, cidades, onde carros trocam informação da sua localização; países em vias de desenvolvimento, onde a internet é inexistente; em auto-estradas, onde não é viável conceber infra-estruturas que permitam uma conectividade permanente, mas onde carros, portagens e serviços necessitam de comunicar. Deste modo, as DTNs constituem uma solução possível para os ambientes indicados. Contudo, as DTNs ainda enfrentam alguns obstáculos na prestação de um serviço de qualidade, visto faltarem mecanismos específicos, como a diferenciação de tráfego. A diferenciação de tráfego é essencial para oferecer diferentes níveis de serviço de qualidade em termos de entrega de mensagens. As abordagens existentes para diferenciação de tráfego em DTNs ainda estão em fase de desenvolvimento. Estas focam-se principalmente nos mecanismos de gestão do buffer a cada nodo da DTN, em vez de ao nível de mecanismo de priorização das mensagens. A priorização de mensagens permite que algumas recebam prioridade em detrimento de outras, melhorando a taxa de entrega, aumentando a probabilidade desta ser entregue corretamente. Esta tese implementa diferenciação de tráfego em DTNs baseando-se em estratégias de priorização, assumindo-se como uma alternativa a outras abordagens de gestão de buffer e priorização de mensagens. Usando a ferramenta de simulação “The One”, foram adaptados três protocolos de routing DTN (Epidemic, Spray & Wait, and PRoPHET) de modo a obedecerem à diferenciação de tráfego. Este objetivo é alcançado pelo desenho, implementação e experimentação de quatro algoritmos que classificam as mensagens de acordo com o seu nível de prioridade, baseando-se em mecanismos tradicionais de diferenciação de tráfego, i.e. as estratégias de Priority Queuing e Weighted Round Robin. Os resultados demonstram que a taxa de entrega de mensagens é influenciada de acordo com as prioridades. Nomeadamente, há um aumento na taxa de entrega de mensagens com prioridade alta, com pouco impacto no número total de mensagens entregues, comparativamente com o mesmo cenário sem mecanismos de diferenciação. Em suma, as DTN podem beneficiar da diferenciação de tráfego baseado em técnicas de priorização de mensagens, representando uma abordagem à melhoria da qualidade de serviço bastante promissora