Tiered bandwidth reservation scheme for multimedia wireless networks

It is important to provide quality of service (QoS) guarantees if we want to support multimedia applications over wireless networks. In this paper, considering the features of tiering in sectored cellular networks, we propose a novel scheme for bandwidth reservation to approach QoS provisioning. By predicting the movement of each connection, the reserving of bandwidth is only required in needful neighboring cells instead of in all neighboring cells. In addition, an admission control mechanism incorporated with bandwidth borrowing assists in distributing scarce wireless bandwidth in more adaptive way. Through mathematical analysis, we proof the advantages of tier‐based approach and the bound for the selection of tiered boundary. The simulation results also verify that our scheme can achieve superior performance than traditional schemes regarding no bandwidth reserving, fixed bandwidth reserving, and bandwidth borrowing in sectored cellular networks when performance metrics are measured in terms of the connection dropping probability (CDP), connection blocking probability (CBP), and bandwidth utilization (BU). Copyright © 2008 John Wiley & Sons, Ltd.     

无线自组织网络中基于QoS保障准则的可用带宽估计

对无线自组织网络中可用带宽估计问题进行了研究,提出了在估计过程中必须将全局服务质量（QoS）保障作为可用带宽的估计准则。建立了无线自组织网络中非饱和条件下异构的分析模型,该模型能将业务流的QoS度量映射为网络参数,在此基础上设计了能提供QoS保障的可用带宽估计算法。本文所提出的估计算法将包括时延、丢包率与吞吐量在内的QoS需求不被破坏作为可用带宽估计的约束条件,克服了现有的工作将无约束的最大可达吞吐量作为可用带宽因而导致业务的QoS可能受到影响这一缺陷,从而使得估计结果更加合理与准确。仿真实验证明了分析模型与可用带宽估计算法的准确性。      

一种基于蚁群优化的多媒体传感器网络服务感知路由算法

本文针对多媒体传感器网络中三类基本服务:异常事件告警服务、信息查询服务以及流媒体查询服务,分析了不同服务的QoS需求,并抽象出多媒体传感器网络QoS路由模型.进而,利用改进的蚁群算法,设计了一个基于蚁群优化的服务感知路由算法ASAR (Ant-colony optimization based Service Aware Routing).本文设计服务感知的路由协议,旨在依据各类媒体数据包不同的QoS需求,选择相应的路由以合理利用全网资源、提高网络性能.最后,我们通过NS2仿真表明了较其他路由算法,本文提出的方法能够为多媒体传感器网络的多种服务提供更好的QoS保障,同时,比传统的蚁群算法具有更好的收敛性.     

Quality of service analysis and improvement with cross layer power allocation in multirelay networks

Quality of service (QoS) guarantee is the main performance metric for designing future wireless networks. For real time applications over wireless links, statistical delay QoS guarantee is the most important QoS metrics. The main goal of this paper is studying the effects of multi‐decode‐and‐forward‐relaying transmission on delay QoS guarantee and user satisfaction. For this end, we first propose an approach to simplify the analysis of statistical delay QoS guarantee by the use of a curve named QoS analysis curve. The QoS analysis curve of any system is based on its effective capacity (EC) function. So, we derive a closed‐form expression for the EC function of a multi‐decode‐and‐forward‐relay network to reduce the computational complexity of finding this quantity. After that, for improving the QoS guarantee performance of a multi‐decode‐and‐forward‐relaying system, the EC of the system is maximized by the use of power allocation (PA) technique. At first, an adaptive PA (APA) algorithm is proposed in which the source and relays PA policies are derived analytically. Although, the overhead of this algorithm is large, it significantly improves the statistical delay QoS guarantee performance. Then, for the systems that cannot tolerate the required large overhead of APA, a fixed PA scheme is presented, which is based on particle swarm optimization algorithm. There is a tradeoff between providing the delay QoS guarantee and the required overhead, in selecting APA or fixed PA schemes. The numerical results validate our analytical outcomes and evaluate our proposed algorithms.     

Optimizing event detection in low duty-cycled sensor networks

Duty cycling is a fundamental approach to conserving energy in sensor networks; however, it brings challenges to event detection in the sense that an event may be undetected or undergo a certain delay before it is detected, in particular when sensors are low duty-cycled. We investigate the fundamental relationship between event detection and energy efficiency. We quantify event detection performance by deriving the closed forms of detection delay and detectability with a relatively simple model. We also characterize the intrinsic tradeoff that exists between detection performance and system lifetime, which helps flexible design decisions for sensor networks. In addition, we propose a fully localized algorithm called CAS to cooperatively determine sensor wakeups. Without relying on location information, the distributed algorithm is easy to implement and scalable to network density and scale. Theoretical bounds of event detection are also studied to facilitate comparative study. Comprehensive experiments are conducted and results demonstrate that the proposed algorithm significantly improves event detection performance in terms of detection latency and detection probability. It reduces as high as 31% of detection delay and increases as much as 25% of detectability compared with the random independent scheme.     

Upstream congestion control in wireless sensor networks through cross-layer optimization

Congestion in wireless sensor networks not only causes packet loss, but also leads to excessive energy consumption. Therefore congestion in WSNs needs to be controlled in order to prolong system lifetime. In addition, this is also necessary to improve fairness and provide better quality of service (QoS), which is required by multimedia applications in wireless multimedia sensor networks. In this paper, we propose a novel upstream congestion control protocol for WSNs, called priority-based congestion control protocol (PCCP). Unlike existing work, PCCP innovatively measures congestion degree as the ratio of packet inter-arrival time along over packet service time. PCCP still introduced node priority index to reflect the importance of each sensor node. Based on the introduced congestion degree and node priority index, PCCP utilizes a cross-layer optimization and imposes a hop-by-hop approach to control congestion. We have demonstrated that PCCP achieves efficient congestion control and flexible weighted fairness for both single-path and multi-path routing, as a result this leads to higher energy efficiency and better QoS in terms of both packet loss rate and delay.     

PCQoS: power controlled QoS tuning for wireless ad hoc networks

Mobile ad hoc networks typically use a common transmission power approach for the discovery of routes and the transmission of data packets. In this paper we present PCQoS; a power-controlled Quality of Service (QoS) scheme for wireless ad hoc networks which builds QoS mechanisms for specific applications that wish to tradeoff better QoS performance for sub-optimal paths. PCQoS allows selected flows to modify their transmit power as a way to add and remove relay nodes from their paths in order to coarsely modify their observed application QoS performance. We present simulation results and show that PCQoS can be used to provide coarse control over traditional QoS metrics (e.g., delay, throughput). To the best of our knowledge the PCQoS protocol represents the first attempt to use variable-range transmission control as a means to provide QoS differentiation to applications in wireless ad hoc networks.     

Service-specific resource allocation in WDM networks with quality constraints

The need to establish wavelength-routed connections in a service-differentiated fashion is becoming increasingly important due to a variety of candidate client networks (e.g., IP, SDH, ATM) and the requirements for QoS-delivery within transport layers. The multiservice operation changes the way we deal with wavelength-routed paths, as they are now being characterized by manifold properties, such as transmission quality, restoration, network management, and policies. We propose a generic approach to service-differentiated connection accommodation in wavelength-routed networks where, for the network state representation, the supplementary network graphs are defined and referred to as service-specific wavelength-resource graphs. These graphs are used for the appropriate allocation of wavelengths on concatenated physical resources building a wavelength route, along which the necessary transmission quality is achieved and the required management and surveillance functions are provided. By considering twofold wavelength routing metrics, i.e., QoS metrics (service requirements) and resource metrics (quality constraints), these graphs can yield the solution to the QoS-routing problem, i.e., the provision of service-specific guarantees under quality constraints-a feature that is still missing from the existing architectures. The numerical analysis of dynamically reconfigurable multiservice WDM networks is presented for regular network operation as well as for optical network service restoration.     

Effective capacity: a wireless link model for support of quality of service

To facilitate the efficient support of quality of service (QoS) in next-generation wireless networks, it is essential to model a wireless channel in terms of connection-level QoS metrics such as data rate, delay, and delay-violation probability. However, the existing wireless channel models, i.e., physical-layer channel models, do not explicitly characterize a wireless channel in terms of these QoS metrics. In this paper, we propose and develop a link-layer channel model termed effective capacity (EC). In this approach, we first model a wireless link by two EC functions, namely, the probability of nonempty buffer, and the QoS exponent of a connection. Then, we propose a simple and efficient algorithm to estimate these EC functions. The physical-layer analogs of these two link-layer EC functions are the marginal distribution (e.g., Rayleigh-Ricean distribution) and the Doppler spectrum, respectively. The key advantages of the EC link-layer modeling and estimation are: 1) ease of translation into QoS guarantees, such as delay bounds; 2) simplicity of implementation; and 3) accuracy, and hence, efficiency in admission control and resource reservation. We illustrate the advantage of our approach with a set of simulation experiments, which show that the actual QoS metric is closely approximated by the QoS metric predicted by the EC link-layer model, under a wide range of conditions.     

QoS-based routing of multimedia streams in computer networks

Continuous media such as audio and video require a certain quality-of-service (QoS) when transferred through computer networks. The selection of a network route for a particular media stream should hence take into account which route is best-suited for providing this QoS. QoSFinder is a method for QoS-based routing of multimedia streams. It is based on a path vector protocol that takes into account throughput, delay, and loss rate of individual route segments. A simulation of QoSFinder shows that its heuristic is superior to metrics that are only based on one of these parameters. QoSFinder increases the probability of finding suitable paths through networks for distributed multimedia applications     

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.     

Bandwidth allocation for multiservice access on EPONs

Ethernet passive optical networks are a low-cost high-speed solution to the bottleneck problem of the broadband access network. A major characteristic of EPONs is the shared upstream channel among end users, mandating efficient medium access control to facilitate statistical multiplexing and provision multiple services for different types of traffic. This article addresses and provides an overview of the upstream bandwidth allocation issue for multiservice access provisioning over EPONs, and proposes an algorithm for dynamic bandwidth allocation with service differentiation. Based on the multipoint control protocol (MPCP) and bursty traffic prediction, our algorithm enhances QoS metrics such as average frame delay, average queue length, and frame loss probability over other existing protocols     

A Framework for Transaction-Level Quality of Service for M-Commerce Applications

In the emerging wireless Internet environment involving m-commerce and other mobile applications, an increasing number of users are likely to adopt mobile transactions. These transactions may have very diverse requirements and some of them may require a significant amount of network resources and/or bounded delays. One of many unique characteristics of transactions involving a financial value is the criticality of its completion. The unique requirements of mobile transactions necessitate the introduction of new metrics for quality-of-service. So far, most of the quality-of-service research in wireless networks has focused on call or connection- level QoS. In this paper, we propose a framework to support QoS requirements of mobile transactions by resource allocation at the connection level, transaction level, and a combination of connection and transaction levels. To measure the QoS effectiveness of mobile transactions, two new metrics, transaction completion probability and transaction response time, are introduced. Simulation and analytical models are used for computing different metrics for transaction performance under varying network and traffic conditions. The results show that the balanced transaction and connection level resource allocation can improve the probability of transactions completion and resource utilization. This improvement is at the cost of slightly increased processing overload, which is dependent on both the group size and number of transactions during a connection.     

Enabling seamless multimedia wireless access through QoS‐based bandwidth adaptation

Effective support of real‐time multimedia applications in wireless access networks, viz. cellular networks and wireless LANs, requires a dynamic bandwidth adaptation framework where the bandwidth of an ongoing call is continuously monitored and adjusted. Since bandwidth is a scarce resource in wireless networking, it needs to be carefully allocated amidst competing connections with different Quality of Service (QoS) requirements. In this paper, we propose a new framework called QoS‐adaptive multimedia wireless access (QoS‐AMWA) for supporting heterogeneous traffic with different QoS requirements in wireless cellular networks. The QoS‐AMWA framework combines the following components: (i) a threshold‐based bandwidth allocation policy that gives priority to handoff calls over new calls and prioritizes between different classes of handoff calls by assigning a threshold to each class, (ii) an efficient threshold‐type connection admission control algorithm, and (iii) a bandwidth adaptation algorithm that dynamically adjusts the bandwidth of an ongoing multimedia call to minimize the number of calls receiving lower bandwidth than the requested. The framework can be modeled as a multi‐dimensional Markov chain, and therefore, a product‐form solution is provided. The QoS metrics—new call blocking probability (NCBP), handoff call dropping probability (HCDB), and degradation probability (DP)—are derived. The analytical results are supported by simulation and show that this work improves the service quality by minimizing the handoff call dropping probability and maintaining the bandwidth utilization efficiently. Copyright © 2006 John Wiley & Sons, Ltd.     

PRIN: A Priority-Based Energy Efficient MAC Protocol for Wireless Sensor Networks Varying the Sample Inter-Arrival Time

Wireless sensor networks (WSNs) are used in a variety of applications to sense and transfer information to the centralized node with energy efficiency increasing the network’s lifespan. Other factors, such as quality of service (QoS) is also important to improve the performance of the WSNs, by increasing throughput and reducing end-to-end delay. In this paper, we evaluate the importance of QoS in the Medium Access Control (MAC) protocol for WSNs using different metrics and parameters such as energy efficiency, throughput, delay, and the network lifespan. We propose a new QoS MAC protocol, “PRIority in Node” (PRIN), using static priority in the source and the intermediate node and priority among the node which is one hop from the sink node to achieve QoS in WSNs. Simulation results are compared with those of the synchronous MAC protocol in terms of QoS parameters to show the improved performance of the proposed MAC protocol.     

Collision-minimizing CSMA and its applications to wireless sensor networks

Recent research in sensor networks, wireless location systems, and power-saving in ad hoc networks suggests that some applications' wireless traffic be modeled as an event-driven workload: a workload where many nodes send traffic at the time of an event, not all reports of the event are needed by higher level protocols and applications, and events occur infrequently relative to the time needed to deliver all required event reports. We identify several applications that motivate the event-driven workload and propose a protocol that is optimal for this workload. Our proposed protocol, named CSMA/p/sup */, is nonpersistent carrier sense multiple access (CSMA) with a carefully chosen nonuniform probability distribution p/sup */ that nodes use to randomly select contention slots. We show that CSMA/p/sup */ is optimal in the sense that p/sup */ is the unique probability distribution that minimizes collisions between contending stations. CSMA/p/sup */ has knowledge of N. We conclude with an exploration of how p/sup */ could be used to build a more practical medium access control protocol via a probability distribution with no knowledge of N that approximates p/sup */.     

Robust and Efficient Aggregate Query Processing in Wireless Sensor Networks

Wireless sensor networks have been widely used in many applications, such as soil temperature monitoring for plant growth and abnormal event detection of industrial parameters. Among these applications, aggregate queries, such as SUM, COUNT, AVERAGE, MIN and MAX are often used to collect statistical data. Due to the low quality sensing devices or random environmental disturbances, sensor data are often noisy. Hence, the idea of moving average, which computes the average over consecutive aggregate data, is introduced to offset the effect. The high link loss rate, however, makes the result after averaging still inaccurate. To address this issue, we propose a PCM-based data transmission scheme to “make up” the possibly lost data. Specifically, we focus on obtaining robust aggregate results under high link loss rate. In order to reduce the communication traffic that dominates the energy consumption of the sensor network, we also design an intelligent path selection algorithm for our scheme. Our extensive simulation results have shown that this technique outperforms its counterparts under various sensor network conditions.     

QoS-aware multicast routing for the Internet: the design andevaluation of QoSMIC

One of the main problems of the current Internet infrastructure is its inability to provide services at consistent quality-of-service (QoS) levels. At the same time, many emerging Internet applications, such as teleeducation, and teleconferencing, require multicast protocols that will provide the necessary QoS. In this paper, we propose QoSMIC, a multicast routing protocol for the Internet, that provides QoS-sensitive paths in a scalable, resource-efficient, and flexible way. QoSMIC differs from the previous protocols in that it identifies multiple paths and selects the one that can provide the required QoS. Two other key advantages of QoSMIC are its flexibility and adaptivity. First, the distribution tree does not have to be rooted at a preselected core router. Second, we can tradeoff between efficiency metrics depending on our needs; for example, we can tradeoff routing efficiency for a reduction in the control messages. Extensive simulations show that our protocol improves the resources utilization and the end-to-end performance compared to the current protocols. Specifically, our protocol reduces the call blocking probability by a factor of six and reduces the end-to-end delay by as much as 90% compared to the PIM protocol     

Cluster head election techniques for coverage preservation in wireless sensor networks

Coverage preservation is one of the basic QoS requirements of wireless sensor networks, yet this problem has not been sufficiently explored in the context of cluster-based sensor networks. Specifically, it is not known how to select the best candidates for the cluster head roles in applications that require complete coverage of the monitored area over long periods of time. In this paper, we take a unique look at the cluster head election problem, specifically concentrating on applications where the maintenance of full network coverage is the main requirement. Our approach for cluster-based network organization is based on a set of coverage-aware cost metrics that favor nodes deployed in densely populated network areas as better candidates for cluster head nodes, active sensor nodes and routers. Compared with using traditional energy-based selection methods, using coverage-aware selection of cluster head nodes, active sensor nodes and routers in a clustered sensor network increases the time during which full coverage of the monitored area can be maintained anywhere from 25% to 4.5×, depending on the application scenario.     

EARQ: Energy Aware Routing for Real-Time and Reliable Communication in Wireless Industrial Sensor Networks

Wireless industrial sensor networks are wireless sensor networks which have been adapted to industrial applications. Most techniques for wireless sensor networks can be applied to wireless industrial sensor networks. However, for industrial applications of wireless industrial sensor networks, new requirements such as real-time, reliable delivery need to be considered. In this paper, we propose EARQ, which is a novel routing protocol for wireless industrial sensor networks. It provides real-time, reliable delivery of a packet, while considering energy awareness. In EARQ, a node estimates the energy cost, delay and reliability of a path to the sink node, based only on information from neighboring nodes. Then, it calculates the probability of selecting a path, using the estimates. When packet forwarding is required, it randomly selects the next node. A path with lower energy cost is likely to be selected, because the probability is inversely proportional to the energy cost to the sink node. To achieve real-time delivery, only paths that may deliver a packet in time are selected. To achieve reliability, it may send a redundant packet via an alternate path, but only if it is a source of a packet. Experimental results show that EARQ is suitable for industrial applications, due to its capability for energy efficient, real-time, reliable communications.