Wireless multimedia sensor networks (WMSNs) are networks of interconnected devices that allow retrieving video and audio streams, still images, and scalar data from the environment. In a densely deployed WMSN, there exists correlation among the observations of camera sensors with overlapped coverage areas, which introduces substantial data redundancy in the network. In this dissertation, efficient communication schemes are designed for WMSNs by leveraging the correlation of visual information observed by camera sensors. First, a spatial correlation model is developed to estimate the correlation of visual information and the joint entropy of multiple correlated camera sensors. The compression performance of correlated visual information is then studied. An entropy-based divergence measure is proposed to predict the compression efficiency of performing joint coding on the images from correlated cameras. Based on the predicted compression efficiency, a clustered coding technique is proposed that maximizes the overall compression gain of the visual information gathered in WMSNs. The correlation of visual information is then utilized to design a network scheduling scheme to maximize the lifetime of WMSNs. Furthermore, as many WMSN applications require QoS support, a correlation-aware QoS routing algorithm is introduced that can efficiently deliver visual information under QoS constraints. Evaluation results show that, by utilizing the correlation of visual information in the communication process, the energy efficiency and networking performance of WMSNs could be improved significantly.

In the next generation of networks we will begin to see the true convergence of voice, multimedia, and data traffic. This merging of various dedicated networks will occur both in the wired and wireless domains. Given the growth in the areas of wireless voice and data, we see that the combination of mobile and Internet communication constitutes the driving force behind the third-generation wireless system and makes the basis for the fourth-generation wireless system. For services like voice over IP over wireless (VoIPoW), the main challenge is to achieve QoS and spectrum efficiency. In order to support better QoS the IETF Mobile IP Working Group is discussing a number of enhancements to the base protocol to reduce the latency, packet loss and signaling overhead experienced during handoff. This support also includes both the call admission and the subsequent scheduling of packet transmissions. In this thesis, we will first survey the work done on issues related to QoS provisioning for wireless network and then will address bandwidth allocation problem in packet radio network with special emphasis on wireline to wireless internetworking zone. The main aim of the thesis is to evolve a strategy to reduce the call dropping probability by negotiating the QoS in those conditions when we do not have the sufficient resources (mainly bandwidth) to allocate. In order to achieve the QoS we have investigated the behaviour of the Real-time Voice traffic on a wireless link and its relation to the associated quality of service. This investigation opens a way for QoS negotiation, in a condition like during handoff, when the network is not able to sustain the negotiated bandwidth. The main results of this work are, that even with reduced bandwidth, quality for speech can be maintained at a reasonable level and this way the call dropping can be reduced. Such a scheme is useful in those conditions when we do not have the sufficient bandwidth to allocate like during a handoff of a mobile host from one cell to another. Moreover the bandwidth is a scarce resource in wireless domain so there should be an efficient call admission control policy. Many call admission control policies are proposed in the literature; here we propose a simple scheme for real-time traffic, specially speech, in a base station which increases the system throughput. In addition to above, we have also experimented with Cellular IP, one of the implementations of proposed micro-mobility architecture to provide faster handoff and seamless mobility in wired and wireless network.

The aim of this work is to understand the requirements behind Quality of Service (QoS) for Multihop Wireless Networks and evaluate the performance of different such strategies. This work starts by establishing the basis for requirement of QoS and evaluates different approaches for providing QoS. Bandwidth is selected as the most important resource amongst the resources identified for ensuring QoS. The problem is modeled as an optimization problem that tries to maximize the amount of bandwidth available in the system while providing bounds over the bandwidth available over a route. Other QoS parameters are bound by hard limits and are not involved in the optimization problem. The existence of spatial reuse rules has been established through simulations for a TCP based network. This establishes that the reuse rules are independent of the MAC and network layer protocols used. This idea is used in designing the simulations for strategies that use controlled spatial reuse and give known bounds for QoS. Simulations take the network and a set of connections to generate the best possible schedule that guarantees bandwidth to individual connections and maximizes the total number of slots used in the entire system. The total number of slots used is a measure of the bandwidth in use. The set of graphs and connections is generated by a random graph and connection generator and the data set is large enough to average the results. There are two different approaches used for scheduling the connections. The first approach uses graph coloring and provides a simpler implementation in terms of network deployments. Second approach uses on-demand slot allocation. The approaches are compared for their pros and cons. The first approach uses graph coloring to allocate fixed number of slots to each link. This makes an equivalent of a wired network with fixed bandwidth over each link. This network is simpler to operate and analyze at the cost of one time expense of graph coloring. The assumption here is that the network is static or has low mobility. The on demand approach is more flexible in terms of slot assignment and is adaptable to the changing traffic patterns. The cons are that connection establishment is more expensive in terms of bandwidth required and is more complicated and difficult to analyze. The advantages include low initial network establishment cost and accommodation of mobility.

WCDMA是一個寬頻直接序列分碼多工存取(DS-CDMA)系統，使用正交可變展頻係數(Orthogonal Variable Spreading Factor，OVSF)碼以支援多樣化的資料傳輸速率，提供可變動位元速率和服務品質(Quality of Service，QoS)保障，以滿足使用者對多媒體應用服務的需求。在本研究中我們將訊務分群並配置符合的正交變數展頻係數碼的方式，來處理資源分配的問題，期讓每位使用者都能有滿意的服務品質。在論文中，為提供不同等級的差別服務以兼顧QoS和避免頻寬浪費，我們提出以動態群組配置的方式，從所有提出服務要求的訊務中，依其服務優先等級順序，挑選適合的訊務，將其放置於同一群組。系統會配置一OVSF碼給此群組，透過分時共用來進行資料傳輸，使其能提供多樣化的資料傳輸速率，減少碼阻斷，提高系統頻寬的使用率，並滿足使用者對服務品質的需求。實驗模擬顯示，本研究所提出的方法能提供多樣化的資料傳輸速率，並能有效減少碼阻斷，提高頻寬及系統使用率，並達到QoS的要求。 / WCDMA is a wideband Direct-Sequence Code Division Multiple Access (DS-CDMA) system, it uses Orthogonal Variable Spreading Factor (OVSF) codes to support diverse data transmission rates. Orthogonal variable spreading factor codes have the ability to provide variable bit rates and QoS to meet different multimedia application requirements. In this research, we group the traffic and use Orthogonal Variable Spreading Factor (OVSF) technique to deal with resource allocation problem in order to offer satisfactory quality of service to the users. We propose dynamic group allocation method to provide differentiated services in order to meet the QoS requirement and avoid bandwidth wasting. From all those requested services, we move all those services of the same service priority to the same group. The system will subsequently assign OVSF code to each group. Data transmission of each group is based on time-sharing mechanism. Simulations show that the proposed method can provide diverse data transmission rates, and is able to reduce code blocking rate, increase bandwidth and system utilization, and meet the QoS requirement.

Monitoring and controlling smart grid assets in a timely and reliable manner is highly desired for emerging smart grid applications. Wireless Sensor Networks (WSNs) are anticipated to be widely utilized in a broad range of smart grid applications due to their numerous advantages along with their successful adoption in various critical areas including military and health care. Despite these advantages, the use of WSNs in such critical applications has brought forward a new challenge of ful lling the Quality of Service (QoS) requirements of these applications. Providing QoS support is a challenging issue due to highly resource constrained nature of sensor nodes, unreliable wireless links and harsh operation environments. In this thesis we critically investigate the problem of QoS provisioning in WSNs. We identify challenges, limitations and requirements for applying QoS provisioning for WSNs in smart grid applications. We nd that the topic of data prioritization techniques at the MAC layer to provide delay bounds in condition monitoring applications is not well developed. We develop six novel QoS schemes that provide data di erentiation and reduce the latency of high priority tra c in a smart grid context. These schemes are namely; Delay-Responsive Cross layer (DRX), Fair and Delay-aware Cross layer (FDRX), Delay-Responsive Cross layer with Linear backo (LDRX), Adaptive Realistic and Stable Model (ARSM), Adaptive Inter-cluster head Delay Control (AIDC) and QoS-aware GTS Allocation (QGA). Furthermore, we propose a new Markov-based model for IEEE 802.15.4 MAC namely, Realistic and Stable Markovbased (RSM). RSM considers actual network conditions and enhances the stability of the WSNs. We show through analytical and simulation results that all of the presented schemes reduce the end-to-end delay while maintaining good energy consumption and data delivery values.

In this study, a dynamic resource management and subscriber profile prediction scheme for mobile communication systems is presented. The aim is to achieve a high level of QoS for both handoff calls and new calls, while at the same time to improve the utilization of wireless network resources. The simultaneous satisfaction of these two actually conflicting interests will be thanks to two major key features. First, it will be due to the individual subscriber profile based prior information about handoff reservation requests that are provided by the mobile terminals. This information is based on the cell transition probabilities calculated by the mobile itself using collected information during past operations. Second, it will be due to a two-way approach implemented in the resource management processes. The two-way approach controls both the amount of reserved radio channels and the new call admission in a dynamic way, depending on the subscriber mobility and network traffic conditions.

為了進一步支援無線網路上的服務品質(QoS)，IEEE 802.11e通訊協定目前正在制訂中。其提供兩種媒介存取方式，一為基礎的進階分散存取(EDCA)，另一種是建構在進階分散存取下的混合控制存取(HCCA)。802.11e中，藉由不同的訊框間隔(IFS)與競爭視窗(CW)相關參數的設定以區隔不同的存取等級(AC)。為了在802.11e網路下進一步的發展有效的服務品質管理機制，我們提出了一個數學模型以分析在進階分散存取網路下所使用的頻寬與媒體存取層所延遲的時間。在這個模型下，每個站台可以支援多個不同等級的資料流(聲音/影音與資料)。透過這個數學模型，允入控制與資源管理可以很容易實現，也可以支援不同應用程式的不同需求。 / For supporting Quality of Service (QoS) for wireless networks, the IEEE 802.11 Task Group E currently defines enhancements to the IEEE 802.11 MAC, called 802.11e. The IEEE 802.11e provides two mechanisms for the support of applications with QoS requirements, namely, Enhanced Distributed Channel Access (EDCA) and HCF Controlled Channel Access (HCCA). EDCA mechanism defines four access categories (ACs) that provide support for the delivery of traffic with user priorities. Different AC uses various Inter-Frame Space (IFS) and Contention Window (CW) parameters. In order to further develop efficient QoS management for the IEEE 802.11e networks, we propose an analytical model to evaluate throughput and MAC delay of the basic access method of the IEEE 802.11e - EDCA. Our Markov chains consider the situation of different multimedia (voice/video and data) traffic flows in a mobile station. This is improved from previous work, and closer to real usage scenarios. The correctness of our analysis has been validated via simulation results. Throughout our model, call admission control (CAC) and resource management can be easily applied, and thus QoS for hybrid requirements is supported.

在未來異質網路的整合環境中，QoS的問題益形重要，而以現今的網路環境而言，最有可能的異質網路整合是UMTS與WLAN。在本計畫中，我們將以UMTS與WLAN的異質網路整合環境作為基礎，提出Pricing-Improved QoS的觀念，結合Non usage-based pricing、Usage-based pricing、Static pricing和Dynamic pricing的優點以及DiffServ (Differentiated Services)劃分服務等級(service level)的機制，實際設計出使用者效用函數(utility function)與網路成本函數(cost function)，並以分級訂價方式訂定價格。藉著價格機能，讓使用者表達其對服務等級的需求或期望，並使網路資源適當地分配給各種服務，避免資源浪費或錯置的情形，以符合QoS的需求並提高整體社會福利及增加廠商收益。 / The issue of QoS is getting more and more important in the future integration of heterogeneous networks, and the most feasible integration is UMTS and WLAN as for present network environment. In our research, we would propose the concept of pricing-improved QoS combined with the advantage of usage-based, non usage-based, static, and dynamic pricing schemes and the mechanism of differentiated service classess of DiffServ (Differentiated Services) based on the integration of UMTS and WLAN. We would propose the utility function and cost function in detail, and price by differentiated service classes. By the affection of price, a user could express the service class he actually needs and expects. Network resources would be allocated appropriately to each service class avoiding the inappropriate allocation and wastage. This would meet the requirement of QoS and improve the providers’ revenue and overall social welfare.

隨著無線通訊技術快速的發展，使用者對無線傳輸及品質的要求日益提升。第三代合作夥伴計劃3rd Generation Partnership Project (3GPP)所提出的長期演進技術Long Term Evolution (LTE)，是邁入第四代行動通訊系統(4G)的極佳選擇。其中以Single Carrier - Frequency Division Multiple Access (SC-FDMA)系統作為上行鏈路的主要通信技術。 然而，在上行SC-FDMA中有連續性資源塊配置的規定以及所配置之資源塊需使用相同調變技術的限制。一般而言資源分配的好壞會影響傳輸速率(data rate)與系統效能。因此，如何分配資源以改善傳輸速率與增進系統效能是本論文的研究重點。 目前，已有許多文獻在探討如何透過偵測頻率響應(frequency response)，解決資源分配的問題。但我們發現，透過偵測頻率響應的好壞進行優先權排班，無法有效符合現實網路服務的實際需求。在本論文中，我們擬以三階段的演算法來改善系統中資源分配的問題。第一階段，在time domain排班時根據不同的Quality of Service (QoS)特性區分User Equipment (UE)。在第二階段frequency domain排班時依據通道品質好壞決定優先權以分配無線電資源給UE。最後，我們根據SC-FDMA的兩大重要限制，提出在LTE上行系統中資源分配方法，在滿足Guaranteed Bit Rate (GBR)服務之時間延遲的限制時，亦能提升整體系統效能。 在模擬分析中，我們利用NS3進行模擬實驗分析，將我們所提出的三階段演算法在不同比例之網路服務類別的要求下，與固定子載波動態資源分配機制以及適應性動態子載波分配機制進行比較。實驗結果顯示，我們的方法在VoIP的average delay time相較於適應性動態分配法最多可改善約82.9%，real time gaming最多可改善約84.9%，而整體系統頻帶利用率(spectrum utilization)相較於固定與適應性分配機制最多可提升約15.3%。 / Long Term Evolution (LTE) is the latest standard of 3rd Generation Partnership Project (3GPP), which is one of the most promising technology for 4G mobile networks. The goal of LTE is to provide high data rate transmission, scalable bandwidth, low latency, and high-mobility. To achieve this goal, the LTE employs Orthogonal Frequency Division Multiplexing (OFDM) for downlink data transmission and Single Carrier - Frequency Division Multiple Access (SC-FDMA) for uplink transmission. This thesis focuses on the resource allocation problem of LTE SC-FDMA system. We propose a three-stage approach to improve resource allocation performance. In the first stage, we design a time domain scheduling according to different QoS features and time delay requirement to distinguish user equipment (UE). In the second stage, we design a frequency domain scheduling based on channel state information to give priorities to UEs. Finally, we propose resource allocation methods for LTE uplink under the two constraints of SC-FDMA. The proposed methods are proved to be able to meet the real-time service delay constraints and enhance overall system performance. In the simulations, the proposed three stage algorithms are compared to fixed sub-carrier dynamic resource allocation algorithm and adaptive dynamic sub-carrier algorithm against different proportions of network services. Simulation results show that our method outperforms the other two methods in terms of throughput, transmission delay and packet loss ratio.

Σκοπός της παρούσας διπλωματικής εργασίας ήταν η μελέτη των παραμέτρων που επηρεάζουν την ποιότητα εξυπηρέτησης (QoS – Quality of Service) των εφαρμογών VoIP μέσω των διαφόρων τεχνολογιών ευρυζωνικής πρόσβασης. / Aim of the present diplomatic assigment was the study of parameters that affect the quality of service (QoS) of VoIP applications via the various broadband access technologies.