QoS provisioning wireless multimedia transmission over cognitive radio networks

The rapid growing of wireless multimedia applications increases the needs of spectrum resources, but today’s spectrum resources have become more and more scarce and large part of the assigned spectrum is in an inefficiency usage. Cognitive Radio (CR) technologies are proposed to solve current spectrum inefficiency problems and offer users a ubiquitous wireless accessing environment, relying on dynamic spectrum allocation. However, there are two unsolved problems in previous work: 1) based on the simplified Quality of Service (QoS) uniform assumption, specific requirements of different wireless multimedia applications cannot be satisfied; 2) aiming at single-objective optimization of spectrum utilization or handoff rate, the co-optimization of these two necessary objectives in CR networks has not been achieved. In this paper, we propose a Two-tier Cooperative Spectrum Allocation method (TCSA) to solve these two problems. TCSA consists of two functional parts: one is a Spectrum Adjacency Ranking algorithm implemented at the secondary users’ terminals to satisfy the QoS requirements for different wireless multimedia applications; and the other is a Max Hyper-weight Matching algorithm implemented at the cognitive engines of CR networks to co-optimize spectrum utilization and secondary users’ spectrum handoff rate. Simulation results show that, compared with the other Random matching algorithm and Cost minimized algorithm, TCSA can significantly improve the performance of CR networks in terms of secondary users’ throughput and spectrum handoff rate.     

Adaptive end-to-end QoS for multimedia over heterogeneous wireless networks

There has been a surge of interest for multimedia applications over wireless networks in recent years. A colossal number of ways have been proposed to decrease delay, delay jitter and loss in wireless networks and good user-perceived quality in video over internet. This paper studies the multimedia over heterogeneous wireless networks, requirements and problems, and proposes a new scheme to overcome the obstacles. The proposed scheme, takes into account the effects of Application-Level Wireless Multilevel ECN marking (AWMECN), thus helps us overcome the congestion/loss mistake problems. For handoff, handover and lossy link problems, it is considered that a freezing mechanism is in use in application layer and assumed that the upper layers can be aware of disconnection periods to make the rate adaptation decisions. Also a new scheme has been added to receiver to gracefully degrade the quality when no other action is available to combat the long delays without data which is caused by handoffs and wireless temporary disconnections. The transport layer mechanism is chosen to be UDP for avoiding TCP regarding problems. We believe that obtaining a good quality of video depends on good performance of all layers and tried to use the best mechanism in each layer.     

A QoS-based dynamic pricing approach for services provisioning in heterogeneous wireless access networks

In this paper we propose a simple QoS-based dynamic pricing approach for services provisioning in a heterogeneous wireless access network environment which attempts to increase user’s satisfaction level by firstly, maximizing the provided QoS level, and secondly, by applying dynamic pricing strategies according to the QoS. These strategies will allow service providers to maximize their profits. Simulation results demonstrate that the proposed dynamic pricing approach benefits both users and wireless service providers (WSPs). Results also suggest that users have better overall satisfaction due to a better QoS level and fairer prices. The analysis shows that our proposed pricing approach contributes to an increase in WSPs profits compared to the application of the flat-rate pricing model in a competitive market-model.     

QoS management in heterogeneous home networks

An OSGi (Open Services Gateway Initiative) home gateway system manages the integration of heterogeneous home networks protocols and devices to develop ubiquitous applications. Wired and wireless heterogeneous home networks have different QoS concerns. For instance, jitter and latency are important concerns in web phones, while packet loss ratio is important in on-line video. This study adopts UPnP QoS specification version 1.0 to design an adaptive QoS management mechanism based on the RMD (Resource Management in DiffServ) architecture. This study monitors real-time network traffic, and adaptively controls the bandwidth, to satisfy the minimum but most important quality for each application in home network congestion. Simulation results indicate that the average jitter, latency and packet loss are reduced by 0.1391 ms, 0.0066 s, and 5.43%, respectively. The packet loss ratio is reduced by 4.53%, and the throughput is increased by 1.2% in high definition video stream; the packet loss ratio is reduced by 1.89% for standard definition video stream, and in VoIP (Voice over IP) the jitter and latency are reduced to 0.0407 ms and 0.0209 s, respectively.     

无线多媒体传感器网络QoS路由算法研究

由于廉价的CMOS摄像头、麦克风的出现,以及对含有丰富信息的图像,视频和音频信息需求导致了无线多媒体传感器网络-(WMSN)的出现.WMSN具有资源有限、可变的信道容量、数据高度冗余等特点,使得WMSN的QoS路由具有极大的挑战性.提出了一种基于Mesh结构的WMSN,并在该结构体系下,提出了一种基于蚁群算法的QoS路由算法.实验研究表明,蚁群算法具有不依赖全局信息的优点,具有应用于WMSN的前景.实验同时表明,决定蚁群算法收敛速度以及会影响传感器网络性能的一些关键参数较难确定,需要进一步研究.     

Scheduling security-critical multimedia applications in heterogeneous networks

Security is becoming an increasingly important issue in the design of multimedia applications, which are widely used in the industry and academic organizations. However, existing scheduling schemes for real-time multimedia service in heterogeneous networks generally do not take into account security requirements when making allocation and control decisions. In this paper, we develop and evaluate a security-critical multimedia scheduling scheme in the framework of heterogeneous networks. At first, we construct a general media distortion model according to the observed parameters in each network, as well as each application’s characteristic. After that, we exploit a scalable graph-based authentication method which achieves a good trade-off between flexibility and efficiency. Furthermore, a security-critical scheduling scheme is proposed by taking into account applications’ timing and security requirements in addition to precedence constraints. The proposed scheme is applied to heuristically find resource allocations, which maximize the quality of security and the probability of meeting deadlines for all the multimedia applications running on heterogeneous networks. Extensive simulations are provided to demonstrate the effectiveness and feasibility of the proposed scheme.     

User-centric universal multimedia access in home networks

Much research is currently being conducted towards Universal Multimedia Access, aiming at removing barriers that arise when multimedia content is to be consumed with more and more heterogeneous devices and over diverse networks. We argue that users should be put at the center of the research work to enable user-centric multimedia access. In this paper we present the requirements for a user-centric multimedia access system in a networked home environment. These requirements are easy access to available content repositories, context awareness, content adaptation and session migration. After showing the limits of state-of-the-art technologies, we present the architecture of a system which allows unified access to the home network content, automatically delivered to rendering devices close to the user, adapted according to the rendering device constraints, and which is also capable of session mobility.     

A scalable multimedia QoS architecture for ad hoc networks

Communication demands have grown from separate data and voice to integrated multimedia, paving the way to converging fixed, mobile and IP networks. Supporting Multimedia is a challenging task for wireless ad hoc network designers. Multimedia forms high data rate traffic with stringent Quality of Service (QoS) requirements. Wireless ad hoc networks are characterized by frequent topology changes, unreliable wireless channel, network congestion and resource contention. Providing scalable QoS is the most important challenge for multimedia delivery over ad hoc networks. We introduce here a provisioning and routing architecture for ad hoc networks which scales well while provisioning QoS. The proposed architecture is analysed using a mix of HTTP, voice and video streaming applications over 54 Mbps 802.11 g-based ad hoc networks. The architecture is simulated and compared to well-known routing protocols using the OPNET Modeller. The results show that our architecture scales well with increase in the network size, and outperforms well-known routing protocols.     

基于业务区分的无线多媒体传感器网络QoS体系结构

无线多媒体传感器网络（WMSNs）的网络服务质量（QoS）一直是人们关心的核心问题,然而目前WMSNs的QoS保障研究主要针对单个协议层或特定应用场景,缺少系统性的QoS体系框架研究。结合无线传感器网络自身特点,利用图论对网络进行建模。在此基础上,提出一种三层可计算QoS指标体系,并根据各种应用不同QoS需求将应用分为四类,设计出一种基于业务区分的无线多媒体传感器网络QoS体系结构（DQoSAW）。以传输MPEG视频流为例对DQoSAW进行验证,实验结果表明DQoSAW能够显著改进WMSNs的整体性能。     

Availability of end-to-end ideal QoS in IP packet networks

Network processor technology has advanced to the point where high-precision time-based store-and-forward logic is readily incorporated into packet switches and routers. With appropriate scheduling, packets from multiple flows can be serviced without contending for link resources. Accordingly, packet flows traversing a network of switching elements can have both path and time determinacy attributes which support ideal end-to-end QoS (zero jitter, zero loss, acceptable end-to-end latency) for real-time UDP packet flows and guaranteed goodput for TCP flows. One approach to packing a network with a relatively large number of such deterministic flows, i.e. achieving high availability of the ideal QoS service in a network, uses precise buffering of packets at each switch, which introduces latency. This paper describes analysis methods for quantifying how much buffering may be necessary to achieve high (99.999%) availability. For typical network topologies the analysis shows that buffering latency requirements are very small compared to transport delays, even when the network is highly utilized with heterogeneous (e.g. voice, video, circuit emulation, and data) traffic. Actual physical implementations have empirically validated the analysis results as well as the scalability of the end-to-end, time-based forwarding approach and the end-to-end availability of ideal QoS services in IP packet networks.     

Qos-driven SCTP-based multimedia delivery over heterogeneous wireless networks

Stream Control Transport Protocol （SCTP）-based handover is supposedly the best suit for current mobile Internet users. However, prevalent SCTP-based handover solutions mostly evaluate candidate networks by a function of multiple attributes such as available bandwidth, delay, etc., which tend to vary often in burst and might cause the instability of handover decisions. Moreover, the SCTP congestion control strategy leads to sudden degradation of users＇ quality of experience for multimedia streaming service because of abrupt and frequent strong fluctuations in the transmission rate. In this paper, we propose a novel QoS-driven SCTP- based handover solution （SCTP-QD） appropriate for heterogeneous wireless multimedia transmission. A new network service and transport layer QoS-aware model is designed to help SCTP-QD accurately analyze the service stability and data transmission capacity for each path. A proper QoS-driven handover decision model is introduced in SCTP-QD in order to improve the SCTP handover efficiency while reducing unnecessary handoffs and fail-over probability. A proposal is finally addressed to help SCTP-QD avoid the slow start phase whenever handover occurs. The simulation results show that SCTP-QD outperforms existing solutions in terms of data delivery performance.     

On utility-fair bandwidth adaptation for multi-class traffic QoS provisioning in wireless networks

The ability to adjust the allocated bandwidth of ongoing calls to cope with wireless network resource fluctuations is becoming increasingly important. In this paper, we describe a utility-based bandwidth adaptation scheme for multi-class traffic quality-of-service (QoS) provisioning in wireless networks. With the proposed scheme, each call is assigned a utility function according to its adaptive characteristics. Depending on the network load the allocated bandwidth of ongoing calls are upgraded or degraded dynamically such that each call receives fair utility. The quantization of utility function by dividing the utility range into a fixed number of equal intervals is a key feature of our proposed utility-fair algorithm. Appropriate call admission control and bandwidth reservation policies are also integrated into the proposed scheme to provide QoS guarantees to the new and handoff calls. Extensive simulation experiments have been conducted to evaluate the performance of the proposed scheme compared with two other existing ones. Results show that our bandwidth adaptation scheme is effective in achieving utility fairness while keeping the call blocking and handoff dropping probabilities substantially low.     

Systematic performance modeling and characterization of heterogeneous IP networks

Accurate measurement and modeling of IP networks is essential for network design, planning, and management. Efforts are being made to detect the state of the network from end-to-end measurements using different techniques and paradigms. In this paper we propose a novel concept to use in the modeling of real network scenarios under measurement and analysis. We called this new concept Service Condition. We explain our proposal's motivations and we use some simple examples to show how to apply the Service Condition concept to the study of real heterogeneous network scenarios. To show the real applicability of our proposal, preliminary results from a performance evaluation study over real heterogeneous networks (where the integration of LAN, WLAN, ADSL, UMTS, and GPRS is present) are given.     

Multi-level cross-layer protocol for end-to-end delay provisioning in wireless multimedia sensor networks

Frontiers of Information Technology & Electronic Engineering - Rapid developments in information and communication technology in recent years have posed a significant challenge in wireless...     

一种WMSNs能量感知QoS路由机制设计

随着对监测数据的要求越来越高,多媒体传感器网络具有广泛的应用前景。由于多媒体信息对QoS的要求比较高和网络对能量的依赖较大,使得无线多媒体网络中QoS问题的研究极具挑战性。从网络层角度提出一种基于能量感知的可靠路由机制,通过充分考虑节点的剩余能量和路径的可靠性,选择相应的路由,从而提高了对网络资源的利用和网络的可靠性。仿真实验显示该机制能有效提高传输的可靠性,降低网络通信开销。     

QoS provisioning in IEEE 802.11-compliant networks: Past,present, and future

Proliferation of portable, wireless-enabled laptop computers and PDAs, cost-effective deployment of access points, and availability of the license-exempt bands and appropriate networking standards contribute to the conspicuous success of IEEE 802.11 WLANs. In the article, we provide a comprehensive overview of techniques for capacity improvement and QoS provisioning in the IEEE 802.11 protocol family. These techniques represent the R&D efforts both in the research community and the IEEE 802.11 Working Groups. Specifically, we summarize the operations of IEEE 802.11 legacy as well as its extension, introduce several protocol modeling techniques, and categorize the various approaches to improve protocol capacity, to provide QoS (by either devising new MAC protocol components or fine-tuning protocol parameters in IEEE 802.11), and to judiciously arbitrate radio resources (e.g., transmission rate and power). To demonstrate how to adapt QoS provisioning in newly emerging areas, we use the wireless mesh network as an example, discuss the role IEEE 802.11 plays in such a network, and outline research issues that arise.     

Energy-aware deployment of dense heterogeneous cellular networks with QoS constraints

The base station (BS) configuration is a key factor to improve energy efficiency (EE). In this paper, we focus on designing the network deployment parameters (i.e., BS densities) for biased K-tier heterogeneous cellular network (HCN) with quality of service (QoS) provisioning. Using appropriate approximations, we derive the closed-form expressions of optimal BS density across all tiers to minimize the area power consumption (APC) by applying the stochastic geometry theory, while satisfying the users’ QoS requirements. These results are used to obtain some new insights into the EE performance of biased HCN deployment. With the aid of this approach, the best type of BSs to be deployed or switched off for energy saving purposes can be identified from the perspectives of BS transmission power. More precisely, if the BS transmission power ratio between an arbitrary pair of tiers of K-tier HCN, e.g., the small cell BS and macro BS tiers, is higher than a threshold which is a function of path loss exponent, bias factor and power consumption, the small cell BSs are preferred. The opposite situation takes place otherwise. Furthermore, it is also shown that, compared to the unbiased HCN scenario, significant energy savings are possible by appropriately biasing the HCN and optimizing the BS density, subject to the QoS constraints among all tiers.     

DCCP下的一种流媒体重传机制

由于差错重传机制存在各种缺点,并不适合流媒体传输,若它的处理过程占用最小网络带宽和时间,将大大提高流媒体的质量。提出了一种基于DCCP的源端控制的选择重传机制（TBSR）,其重传由决策算法决定,而发送速率和拥塞控制由TFRC控制。仿真结果表明,机制能大大提高流媒体视频质量。     

Ant-based routing for wireless multimedia sensor networks using multiple QoS metrics

In wireless sensor networks, most routing protocols consider energy savings as the main objective and assume data traffic with unconstrained delivery requirements to be a given. However, the introduction of video and imaging sensors unveils additional challenges. The transmission of video and imaging data requires both energy efficiency and QoS assurance (end-to-end delay and packet loss requirements), in order to ensure the efficient use of sensor resources as well as the integrity of the information collected. This paper presents a QoS routing model for Wireless Multimedia Sensor Networks (WMSN). Moreover, based on the traditional ant-based algorithm, an ant-based multi-QoS routing metric (AntSensNet) is proposed. The AntSensNet protocol builds a hierarchical structure on the network before choosing suitable paths to meet various QoS requirements from different kinds of traffic, thus maximizing network utilization, while improving its performance. In addition, AntSensNet is able to use a efficient multi-path video packet scheduling in order to get minimum video distortion transmission. Finally, extensive simulations are conducted to assess the effectiveness of this novel solution and a detailed discussion regarding the effects of different system parameters is provided. Compared to typical routing algorithms in sensor networks and the traditional ant-based algorithm, this new algorithm has better convergence and provides significantly better QoS for multiple types of services in wireless multimedia sensor networks.