The goal of the dissertation study was to evaluate the existing DG scheduling algorithm. The evaluation was developed through previously explored simulated analyses of DGs performed by researchers in the field of DG scheduling optimization and to improve the current RT framework of the DG at TTU. The author analyzed the RT of an actual DG, thereby enabling other investigators to compare theoretical results with the results of this dissertation case study. Two statistical methods were used to formulate and validate predictive models: multiple linear regression and graphical exploratory data analysis techniques. Using both statistical methods, the author was able to determine that the theoretical model was able to predict the significance of four independent variables of resource fragmentation, computational volatility, resource management, and grid job scheduling on the dependent variables quality of service and job performance affecting RT. After an experimental case study analysis of the DG variables, the author identified the best DG resources to perform optimization of run-time performance of DG at TTU. The projected outcome of this investigation is the improved job scheduling techniques of the DG at TTU.

The Quality of Service (QoS) is a profound concept which is gaining increasing attention in the Internet industry. Best-effort applications are now no longer acceptable in certain situations needing high bandwidth provisioning, low loss and streaming of multimedia applications. New emerging multimedia applications are requiring new levels of quality of services beyond those supported by best-effort networks. Quality of service routing is an essential part in any QoS architecture in communication networks. QoS routing aims to select a path among the many possible choices that has sufficient resources to accommodate the QoS requirements. QoS routing can significantly improve the network performance due to its awareness of the network QoS state. Most QoS routing algorithms require maintenance of the global network's state information to make routing decisions. Global state information needs to be periodically exchanged among routers since the efficiency of a routing algorithm depends on link-state information accuracy. However, most QoS routing algorithms suffer from scalability due to the high communication overhead and the high computation effort associated with maintaining accurate link state information and distributing global state information to each node in the network. The ultimate goal of this thesis is to contribute towards enhancing the scalability of QoS routing algorithms. Towards this goal, the thesis is focused on Localised QoS routing algorithms proposed to overcome the problems of using global network state information. Using such an approach, the source node makes routing decisions based on the local state information for each node in the path. Localised QoS routing algorithms avoid the problems associated in the global network state, like high communication and processing overheads. In Localised QoS routing algorithms each source node maintains a predetermined set of candidate paths for each destination and avoids the problems associated with the maintenance of a global network state by using locally collected flow statistics and flow blocking probabilities.

Quality of Service (QoS) routing considered as one of the major components of the QoS framework in communication networks. The concept of QoS routing has emerged from the fact that routers direct traffic from source to destination, depending on data types, network constraints and requirements to achieve network performance efficiency. It has been introduced to administer, monitor and improve the performance of computer networks. Many QoS routing algorithms are used to maximize network performance by balancing traffic distributed over multiple paths. Its major components include bandwidth, delay, jitter, cost, and loss probability in order to measure the end users' requirements, optimize network resource usage and balance traffic load. The majority of existing QoS algorithms require the maintenance of the global network state information and use it to make routing decisions. The global QoS network state needs to be exchanged periodically among routers since the efficiency of a routing algorithm depends on the accuracy of link-state information. However, most of QoS routing algorithms suffer from scalability problems, because of the high communication overhead and the high computation effort associated with marinating and distributing the global state information to each node in the network. The goal of this thesis is to contribute to enhancing the scalability of QoS routing algorithms. Motivated by this, the thesis is focused on localized QoS routing that is proposed to achieve QoS guarantees and overcome the problems of using global network state information such as high communication overhead caused by frequent state information updates, inaccuracy of link-state information for large QoS state update intervals and the route oscillating due to the view of state information. Using such an approach, the source node makes its own routing decisions based on the information that is local to each node in the path. Localized QoS routing does not need the global network state to be exchanged among network nodes because it infers the network state and avoids all the problems associated with it, like high communication and processing overheads and oscillating behaviour. In localized QoS routing each source node is required to first determine a set of candidate paths to each possible destination. In this thesis we have developed localized QoS routing algorithms that select a path based on its quality to satisfy the connection requirements. In the first part of the thesis a localized routing algorithm has been developed that relies on the average residual bandwidth that each path can support to make routing decisions. In the second part of the thesis, we have developed a localized delay-based QoS routing (DBR) algorithm which relies on a delay constraint that each path satisfies to make routing decisions. We also modify credit-based routing (CBR) so that this uses delay instead of bandwidth. Finally, we have developed a localized QoS routing algorithm for routing in two levels of a hierarchal network and this relies on residual bandwidth to make routing decisions in a hierarchical network like the internet. We have compared the performance of the proposed localized routing algorithms with other localized and global QoS routing algorithms under different ranges of workloads, system parameters and network topologies. Simulation results have indicated that the proposed algorithms indeed outperform algorithms that use the basics of schemes that currently operate on the internet, even for a small update interval of link state. The proposed algorithms have also reduced the routing overhead significantly and utilize network resources efficiently.

In this thesis we have focused in the wireless environment and how to run voice application over it. Conducive environment that makes it possible for the voice services to run in wireless is necessary. As we know this well that wireless is a contemporary technology due to it low cost and its effectiveness, and one major advantage of it is the mobility that is one fell free to move anywhere but have the access to the resource. So this makes wireless networks of great value, we in this thesis have focused on wireless LAN’s. In second part of the thesis we have shed some light on the VoIP showing how it works in the wireless environment. Analysis phase is relatively more important phase then the previous section which shows issues or hindrances in carrying voice over wireless environment. This analysis shows that these issues still prevails and should be addresses and the corresponding results are also discussed and by looking at those results we have derived a summery out of it. Next chapter we firstly tried to explain why we have chosen specific protocols and then showing some graphical representation measurements that are to address the problem based on the work done. We tried to evaluate EDCF and DCF as these play important role in handling real time applications like voice. After that we proposed a scheme through which these effects can be minimized and to enhance the method is necessary to avoid the issues still in effect. / Thesis is Part for Master program in Electrical Engineering with Emphasis on Telecommunication(2007-2009).We have had a very nice time doing this thesis as there was alot of learning. Our examinator was allways there to help us, we are thankfull to Richard for his endless support.

網際網路的蓬勃發展造就了近年來通訊網路的重大改革，將原有circuit switching與packet switch網路整合成一個單一的All-IP網路已成趨勢，除了降低網路建置、維護與營運管理成本外，還提供一新的服務平台來支援所有的應用服務。新的網路造就新的應用服務，也產生了更形複雜的服務品質問題，針對這個問題，本研究團隊提出的Budget-Based QoS以分散預算的方式，採事先規劃、分散式的方法，簡化管理、追求效率與不增加管理複雜度為原則，提供端對端的網路服務品質保證。此架構下，核心網路的資源配置是由Bandwidth Broker (BB)統籌分配整個網域的資源，資源配置採以批發零售的方式，每個Ingress Router根據需求預測向BB預先批購資源，BB再依此配置資源給各個Ingress Router。為了彌補預測誤差所造成的資源浪費，本研究提出了數種資源配置的方式試圖提升網路資源的使用率，其中中央保留資源法以中央統籌的方式，即時的配置事先保留的資源給有需要的Ingress Router；超額分配法則以類似航空公司訂位的方式，大膽地超額配置資源給各個Ingress Router試圖增加資源使用率。文章的最後以簡單的模擬與實驗數據來說明上述兩種資源配置法彌補預測誤差的效能，並提供網域的經營者參考，方便在不同的環境下對於不同的資源配置法做出選擇。 / Because of great progress of communication and computer technology, aggressive deployment of broadband fiber optical network, advance of Internet technology, and the global standardization of IP technology, the telecommunication industry is moving toward a converged network, which uses a single global IP based packet-switching network to carry all types of network traffics. In these types of network traffics, different traffic types require corresponding service to ensure end- to-end quality. For carrying all types of network traffics on All-IP network, BBQ (Budget-Based QoS) research group propose a QoS system architecture to provide end-to-end QoS guarantee. In this thesis, basing on BBQ QoS system, we propose resource pre-planning mechanism to management core network. According to demand forecast from historical data and considering pre-planning cost, pre-planning mechanism will find optimal policy to reduce management cost. In order to compensate the potential resource waste due to forecasting error, several resource allocation approach are proposed. Central Pool approach reserves resource in central pool and allocates it to those Ingress Routers who need. Overbook approach is similar to overbooking in airline booking system. It over-commits resource to Ingress Routers to improve resource utilization. In the end of this thesis, we simulate the two resource allocation approach and evaluate the performance through experiments under different circumstances. According to those evaluation, system provider can easily choose the proper allocation approach in different environments.

未來行動通訊網路之傳輸層將以IP技術為主，各種IP多媒體服務的興起將產生複雜的訊務及動態且多樣化的服務品質(Quality of Service，QoS)需求；加上行動通訊網路具高度不穩定的特性，造成即時服務(real-time service)在IP傳輸層上的效能不彰，無法有效保證一定的服務品質。為有效滿足動態且多樣化的服務品質需求，不只需針對平均頻寬、延遲、抖動和封包丟失率作控制，更需即時的服務品質回饋機制以動態與精確的控制服務品質。本論文提出一回饋型服務品質控制架構與方法，將需要服務品質保證之即時服務的效能轉換為使用者滿意度並即時回饋此滿意度，以動態協商資源並調整到所需之服務品質。如此不僅更能真實反應使用者滿意程度，更能有效提升網路資源的使用。我們選擇UMTS系統，乃因該系統是以IP傳輸介面為傳輸層，並亟需服務品質控制的系統。末了，我們以模擬實驗來驗證本論文之回饋型服務品質控制架構的效能。 / IP technology will be the core technology of transmission layer in the future mobile communication network. The rise of varied IP-based multimedia services will produce complicated traffic and diversified service quality (Quality of Service, QoS) demands. In addition, the wireless mobile communication network is highly error-prone, this will cause real-time services to have poor performance in IP transmission layer, and hard to guarantee services with a certain quality. To meet this, we not only need to control average bandwidth, delay, jitter and packet loss, but also a well-defined prompt feedback mechanism to dynamically and accurately control the service quality. This thesis proposes a feedback-based QoS control framework to convert QoS parameters of real-time services into user's satisfaction and then feedback this satisfaction immediately. The feedback information is used to dynamically negotiate demanding resource to guarantee a certain service quality. This framework can not only more closely reflect user's satisfaction, but also enhance the network resource usage more effectively. We choose UMTS as our target system is because its transmission layer is based on IP transmission interface, and it has emergent need to have better QoS control. At the end, we use Network Simulator-2 to verify the proposed framework is more effective.

802.16與802.11e均有提供服務品質(QoS)，但是其MAC並不相同，為了達到QoS的保證，我們使用馬可夫鍊(Markov Chain)模型分析在不同連線數量時802.11e EDCA的延遲時間(delay time)。然後，我們可以再利用允入控制(CAC)機制限制連線的數量以保證延遲時間的需求，並使用令牌桶(Token Bucket)機制，在滿足延遲及頻寬的需求下控制輸出流量，在我們的令牌桶機制中可以依照頻寬需求的變化自動調整令牌(Token)產生速率，最後使用封包丟棄機制提升吞吐量(throughput)。 　　在提出我們的方法後，我們使用Qualnet模擬器驗證延遲時間、封包丟棄率及吞吐量，結果表示我們所提出的方法在三方面都有明顯的改進。 / IEEE 802.16 and 802.11e both provide Quality of Service (QoS), but the MAC of betweens is different. Ensuring the QoS guarantee, we use a Markov Chain model to analyze the 802.11e EDCA delay time under variance number of connections. Therefore, we can employ a CAC mechanism constraining the number of connections to guarantee the delay requirement. Further, considering the delay requirement and the bandwidth, we use a Token Bucket mechanism to throttle the traffic output that ensures the delay and bandwidth to be satisfied. And our Token Bucket mechanism can tune the token rate automatically by bandwidth requirement. Finally, we use the Packet Drop mechanism to improve throughput. After my methodology, we validate the delay, packet drop rate and throughput by simulator Qualnet. We have significant improvement in delay, drop rate, and throughput.

受到封包網路原本忽略時效性特性之影響，對時效性要求極高的多媒體網路服務，如Voice over IP (VoIP)以及Video on Demand (VoD)在All-IP整合的核心網路上提供時，其服務品質低於傳統之電路交換網路。 封包在網路的傳遞過程中受到各種因素之影響，於到達目的地時，可能會造成long delay time，high jitter或packet loss，而在目的地端幾乎已經沒有補救機會，故而如果能在傳遞的過程中，依封包的時效性及重要性做適度的次序調動(rescheduling)而不要依序傳遞(FIFO)，讓過遲的封包提前送出，而將有時間餘裕的封包稍緩送出，如此截長補短，可提高網路效能及整體QoS滿意度。 我們在BBQ (Budget-Base QoS)的架構下發展一套簡單而有效的方法，在單佇列(Single Preemptive Queue)及多佇列(Multiple FIFO Queue)的router架構下，根據封包時效性及重要性賦予合適的profit function，並參考封包在後續路程上各router的負載狀態以便能更精確預估封包是否能及時到達目的地並調整profit function參數以調整封包的送出順序，如此能提高排程的效能。 我們先對單一服務等級的封包排程進行研究，獲得參數調整之技巧，再根據其結果設計多服務等級的封包排程方法，其重點在於如何調配profit function給不同的服務等級。 我們藉由NS-2模擬模擬器進行實驗，評估本方法的效能，實驗結果顯示我們的方法可以較每個router僅根據自身所知的資訊進行排程更可以有效提高網路效能，且能對不同的服務等級做差異化處理以提高整體QoS滿意度。最後在多等級服務的實驗環境及評估指標下，網路高負載的情況，本方法與Simulated Priority Queue排程演算法比較可以提升34%的整體滿意度。 / Running time sensitive multimedia services such as Voice-over-IP (VoIP) and Video-on-Demand (VoD) on All-IP networks may have lower quality than that on the traditional circuit-switched networks. Influenced by many factors, packets transported on a packet-switched network, may suffer from long delay time, large jitter and high packet loss rate. When a packet arrives its destination late, there is no way to correct the problem. Thus, it will be beneficial if routers could forward packets base on their timeliness and importance, instead of using First-In-First-Out (FIFO) service plan, giving important late packets proper precedence. The overall QoS satisfaction will be improved significantly. In this thesis, we develop a simple and effective scheduling policy based on this concept for the environments where packets have predefined hop-by-hop time schedule. Routers are assumed in two different queue architectures: ideal Single Preemptive Queue router and practical Multiple FIFO Queue router. To forward a packet, a router first assigns a suitable profit function to the packet based on its timeliness and importance as well as the loading status in its succeeding routers along its predefined traveling path, then inserts the packet into an appropriate position in the output queues. Taking the loading status of succeeding routers into account could predict more accurately whether the packet could reach its destination on time or not. We conduct the research for the single service class environments first to learn the characteristics of this new scheduling policy, and then for the multiple service class environments based on the knowledge acquired. The challenge is to find the best way to assign proper profit functions to different classes of packets in order to utilize resources more wisely, e.g. urgent and important packets get precedence. We evaluate the performance of this approach by simulation using NS-2 network simulator. Simulation results show that our approach outperforms our previous version which doesn't take the loading status of succeeding routers into account. Furthermore, our approach can outperform the Simulated Priority Queue by at least 34% under heavy load and our evaluation metrics.

WiMAX發展至今已經制定出許多標準的規格，但在call admission control (CAC)、bandwidth request (BR)、bandwidth allocation和schedule的細節設計上並沒有標準的規劃和演算法。本文中，我們提出一個CAC機制叫作multi-modulation CAC。不同於目前大部分的CAC機制僅考慮到單一調變(modulation)的情況，我們的研究聚焦在多調變的環境上。並利用multi-modulation CAC改善傳統CAC無法在多調變底下正常運作的問題。我們提出的理論中，BS的CAC是藉由剩餘slot數決定是否要接受連線。最後，我們用網路模擬器NS-2 (network simulator version 2)作為測試實驗架構並分析評估實驗的系統效能。 / So far, WiMAX forum has worked out many specifications of the IEEE 802.16 standard. However, it does not have detailed mechanisms of connection admission control (CAC)、bandwidth request (BR)、bandwidth allocation and scheduling. In this thesis, we propose an admission control scheme called multi-modulation CAC. Rather than most CAC only considering the single modulation environment, our study focused on multi-modulation environment. We use the multi-modulation CAC to improve the traditional CAC can’t work well in multi-modulation environment. With the proposed scheme, base station performs connection admission control to decide whether or not to accept connection requests by number of the remained slot. Finally, we use NS-2 (network simulator version 2) as network simulator and develop an analytical model to evaluate the system performance.

With the rapid development of cellular communication techniques, many recent studies have focused on improving the quality of service (QoS) in cellular networks. One characteristic of the systems in cellular networks, which can have direct impact on the system QoS, is the fluctuation of the system capacity. In this thesis, the QoS of systems with capacity fluctuations is studied from two perspectives: (1) priority queueing systems with preemption, and (2) the M/M/~C/~C system. In the first part, we propose two models with controlled preemption and analyze their performance in the context of a single reference cell that supports two kinds of traffic (new calls and handoff calls). The formulae for calculating the performance measures of interest (i.e., handoff call blocking probability, new call blocking and dropping probabilities) are developed, and the procedures for solving optimization problems for the optimal number of channels required for each proposed model are established. The proposed controlled preemption models are then compared to existing non-preemption and full preemption models from the following three perspectives: (i) channel utilization, (ii) low priority call (i.e., new calls) performance, and (iii) flexibility to meet various constraints. The results showed that the proposed controlled preemption models are the best models overall. In the second part, the loss system with stochastic capacity, denoted by M/M/~C/~C, is analyzed using the Markov regenerative process (MRGP) method. Three different distributions of capacity interchange times (exponential, gamma, and Pareto) and three different capacity variation patterns (skip-free, distance-based, and uniform-based) are considered. Analytic expressions are derived to calculate call blocking and dropping probabilities and are verified by call level simulations. Finally, numerical examples are provided to determine the impact of different distributions of capacity interchange times and different capacity variation patterns on system performance.