QoS Provisioning in Wireless/Mobile Multimedia Networks Using an Adaptive Framework

Recently there is a growing interest in the adaptive multimedia networking where the bandwidth of an ongoing multimedia call can be dynamically adjusted. In the wireless/mobile multimedia networks using the adaptive framework, the existing QoS provisioning focused on the call blocking probability and the forced termination probability should be modified. We, therefore, redefine a QoS parameter – the cell overload probability – from the viewpoint of the adaptive multimedia networking. Then, we propose a distributed call admission control (CAC) algorithm that guarantees the upper bound of the cell overload probability. Also, a bandwidth adaptation algorithm which seeks to minimize the cell overload probability is also presented. Simulation experiments are carried out to verify the performance of the proposed CAC algorithm. Furthermore, the performance of the adaptive wireless/mobile network is compared to that of the existing non-adaptive wireless/mobile networks. As a further step in QoS provisioning, we propose another QoS parameter, the degradation period ratio, and discuss analytically how the CAC algorithm guarantees the upper bound of the degradation period ratio.     

On Bandwidth Allocation for Data Dissemination in Cellular Mobile Networks

Wireless bandwidth is a scarce resource in a cellular mobile network. As such, it is important to effectively allocate bandwidth to each cell such that the overall system performance is optimized. Channel allocation strategies have been extensively studied for voice communications in cellular networks. However, for data dissemination applications, studies on bandwidth allocation have thus far been limited to a single-cell environment. This paper investigates the problem of bandwidth allocation for data dissemination in a multi-cell environment, which, to the best of our knowledge, has not been investigated before. The performance objective is to minimize the overall expected access latency given the workload for each cell in a data dissemination system. Two heuristic techniques, called compact allocation and cluster-step allocation, are proposed to effectively allocate bandwidth for a cellular network. Simulation experiments are conducted to evaluate the performance of the proposed bandwidth allocation schemes. Experimental results show that the proposed schemes substantially outperform the uniform allocation and proportional allocation schemes.     

Combining Bandwidth Borrowing and Reservation in Cellular Networks

In the third generation cellular networks and beyond, a wide variety of different services are/will be provided by the operators. Out of QoS reasons, it is preferable to assign higher priority to certain connection types. These include calls carrying delay-sensitive services and already ongoing calls. In this paper, a prioritization method combining bandwidth borrowing and reservation, called BBR, will be presented. BBR monitors the rate-adaptiveness of the ongoing calls in a cell. Simultaneously, advanced movement predictions are applied to estimate the arrival rate to each cell. If it is determined that the use of bandwidth borrowing (temporarily reducing the data rate of other connections in the same cell) is not sufficient to support the high priority calls that are expected to arrive, a portion of the assigned bandwidth to the cell is exclusively reserved for these calls to prevent call dropping. The scheme enables the operator to increase the average user satisfaction in the network. This is achieved by defining appropriate penalty functions for the events of blocking, dropping and bandwidth reduction of a call.     

Efficient QoS Provisioning for Adaptive Multimedia in Mobile Communication Networks by Reinforcement Learning

The scarcity and large fluctuations of link bandwidth in wireless networks have motivated the development of adaptive multimedia services in mobile communication networks, where it is possible to increase or decrease the bandwidth of individual ongoing flows. This paper studies the issues of quality of service (QoS) provisioning in such systems. In particular, call admission control and bandwidth adaptation are formulated as a constrained Markov decision problem. The rapid growth in the number of states and the difficulty in estimating state transition probabilities in practical systems make it very difficult to employ classical methods to find the optimal policy. We present a novel approach that uses a form of discounted reward reinforcement learning known as Q-learning to solve QoS provisioning for wireless adaptive multimedia. Q-learning does not require the explicit state transition model to solve the Markov decision problem; therefore more general and realistic assumptions can be applied to the underlying system model for this approach than in previous schemes. Moreover, the proposed scheme can efficiently handle the large state space and action set of the wireless adaptive multimedia QoS provisioning problem. Handoff dropping probability and average allocated bandwidth are considered as QoS constraints in our model and can be guaranteed simultaneously. Simulation results demonstrate the effectiveness of the proposed scheme in adaptive multimedia mobile communication networks. This work is based in part on a paper presented at BroadNet's 04, San Jose, CA, Oct. 2004. Fei Yu received the M.S. degree in Computer Engineering from Beijing University of Posts and Telecommunications, P.R. China, in 1998, and the Ph.D. degree in Electrical Engineering from the University of British Columbia (UBC), Canada, in 2003. From 1998 to 1999, Dr. Yu was a system engineer at China Telecom, P.R. China, working on the planning, design and performance analysis of national SS7 and GSM networks. From 2002 to 2004, He was a research and development engineer at Ericsson Mobile Platforms, Sweden, where he worked on dual-mode UMTS/GPRS handsets. He is currently a postdoctoral research fellow at UBC. His research interests are quality of service, cross-layer design and mobility management in wireless networks. Vincent W.S. Wong (S'94-M'00) received the B.Sc. (with distinction) degree from the University of Manitoba, Winnipeg, MB, Canada, in 1994, the M.A.Sc. degree from the University of Waterloo, Waterloo, ON, Canada, in 1996, and the Ph.D. degree from the University of British Columbia (UBC), Vancouver, BC, Canada, in 2000, all in electrical engineering. From 2000 to 2001, he was a Systems Engineer at PMC-Sierra, Inc., Burnaby, BC. Since 2002, he has been with the Department of Electrical and Computer Engineering, UBC, where he is currently an Assistant Professor. His research interests are in wireless communications and networking. Dr. Wong received the Natural Science and Engineering Research Council (NSERC) postgraduate scholarship and the Fessenden Postgraduate Scholarship from Communications Research Centre, Industry Canada, during his graduate studies. Victor C.M. Leung received the B.A.Sc. (Hons.) degree in electrical engineering from the University of British Columbia (U.B.C.) in 1977, and was awarded the APEBC Gold Medal as the head of the graduating class in the Faculty of Applied Science. He attended graduate school at U.B.C. on a Natural Sciences and Engineering Research Council Postgraduate Scholarship and obtained the Ph.D. degree in electrical engineering in 1981. From 1981 to 1987, Dr. Leung was a Senior Member of Technical Staff at Microtel Pacific Research Ltd. (later renamed MPR Teltech Ltd.), specializing in the planning, design and analysis of satellite communication systems. He also held a part-time position as Visiting Assistant Professor at Simon Fraser University in 1986 and 1987. In 1988, he was a Lecturer in the Department of Electronics at the Chinese University of Hong Kong. He joined the Department of Electrical Engineering at U.B.C. in 1989, where he is a Professor, Associate Head of Graduate Affairs, holder of the TELUS Mobility Industrial Research Chair in Advanced Telecommunications Engineering, and a member of the Institute for Computing, Information and Cognitive Systems. His research interests are in the areas of architectural and protocol design and performance analysis for computer and telecommunication networks, with applications in satellite, mobile, personal communications and high speed networks. Dr. Leung is a Fellow of IEEE and a voting member of ACM. He is an editor of the IEEE Transactions on Wireless Communications, and an associate editor of the IEEE Transactions on Vehicular Technology. He has served on the technical program committees of numerous conferences, and is serving as the Technical Program Vice-Chair of IEEE WCNC 2005.     

Multi-class Bandwidth Reservation Scheme Based on Mobility Prediction for Handoff in Multimedia Wireless/Mobile Cellular Networks

Next generation of wireless cellular networks aim at supporting a diverse range of multimedia services to Mobile Terminal (MT) with guaranteed Quality of Service (QoS). The challenge is to maintain the playing continuity of multimedia streams during handoff. In this paper, a bandwidth reservation scheme based on mobility prediction is proposed, to enable high accurate prediction of next crossing cell (target cell) which a MT is going to, in order to avoid too early or over reservation resulting in a waste of resources. The amount of bandwidth to be reserved is dynamically adjusted according to (a) the current position (location) and the extrapolated direction of MT and; (b) the sector and zones of the cell. A Call Admission Control scheme (CAC) is also considered to further guarantee the QoS of real time traffic. The performance of the system is evaluated through discrete event simulation of the wireless cellular environment. Simulation results show that the proposed scheme as compared to several existing schemes is able to reduce the Handoff Call Dropping Probability (HCDP) of real time traffic and the number of terminated ongoing calls of non-real time traffic. In addition, it is efficient to reduce the number of cancelled reservation and subsequently increase the system bandwidth utilization.

An Efficient and Adaptive Bandwidth Allocation Scheme for Mobile Wireless Networks Using an On-Line Local Estimation Technique

The next generation of mobile wireless networks has to provide the quality-of-service (QoS) for a variety of applications. One of the key generic QoS parameters is the call dropping probability, which has to be maintained at a predefined level independent of the traffic condition. In the presence of bursty data and the emerging multimedia traffic, an adaptive and dynamic bandwidth allocation is essential in ensuring this QoS. The paradox, however, is that all existing dynamic bandwidth allocation schemes require the prior knowledge of all traffic parameters or/and user mobility parameters. In addition, most proposals require extensive status information exchange among cells in order to dynamically readjust the control parameters, thus making them difficult to be used in actual deployment.In this paper, we introduce a novel adaptive bandwidth allocation scheme which estimates dynamically the changing traffic parameters through local on-line estimation. Such estimations are restricted to each individual cell, thus completely eliminating the signaling overhead for information exchange among cells. Furthermore, we propose the use of a probabilistic control policy, which achieves a high channel utilization, and leads to an effective and stable control. Through simulations, we show that our proposed adaptive bandwidth allocation scheme can guarantee the predetermined call dropping probability under changing traffic conditions while at the same time achieving a high channel utilization.     

移动网络中流媒体业务适配承载带宽的解决方案研究

YouTube、优酷、PPLive等一大批以流媒体为载体的视频网站的火爆,意味着流媒体时代的到来。然而,由于移动网络通信环境的不确定性,不能提供稳定的带宽,不能保障流媒体的业务质量。在研究流媒体业务特征、通信标准的基础上,提出一种基于移动核心网信令的,向流媒体业务平台告知移动网络无线链路实时带宽的方法。流媒体平台可根据当前带宽,及时地调整流媒体编码速率,以达到节约网络资源,改善用户业务感受的效果。     

A Call Admission Control Mechanism Using Mobility Graph in Mobile Multimedia Networks

One of the important issues in providing efficient multimedia traffic on a mobile computing environment is to guarantee the mobile host (client) with consistent QoS (Quality of Service). However, the QoS negotiated between the client and the network in one cell may not be honored due to client mobility, causing hand-offs between cells. In this paper, a call admission control mechanism is proposed to provide a consistent QoS guarantee for multimedia traffic on a mobile computing environment. Each cell can reserve fractional bandwidth for hand-off calls to its adjacent cells. It is important to determine the right amount of bandwidth reserved for hand-off calls because the blocking probability of new calls may increase if the amount of reserved bandwidth is more than necessary. An adaptive bandwidth reservation based on a mobility graph and a 2-tier cell structure is proposed to determine the amount of bandwidth to be reserved in the cell and to control dynamically its amount according to network conditions. We also propose a call admission control based on this bandwidth reservation and ``next-cell prediction' scheme using a mobility graph. In order to evaluate the performance of our call admission control mechanism, we measure metrics such as blocking probability of new calls, dropping probability of hand-off calls, and bandwidth utilization. The simulation results show that the performance of our mechanism is superior to that of existing mechanisms such as NR-CAT2, FR-CAT2, and AR-CAT2.     

A Bandwidth Control Method Providing Entrance QoS for Multimedia Communication

1 Motivation Nowadays , the QoS provided by the wideband IPnetwork starts at an edge-router and ends at anotheredge-router .Therefore ,the trunk QoSisfinished,suchas RSVP[1]and DiffServ[2].In order to complete theend-to-end QoS,the mechanism of entrance QoS (thebandwidth controller) is introduced. As Fig.1 shows ,if the bandwidth controller circledby the dashed frame is not used,the Ethernet is con-nected with the router directly through 100 Mbit/sbandwidth. Then this router is connect…     

集成Ad Hoc和移动蜂窝网络系统的切换算法

传统切换算法不能适应多准则切换的要求,基于多准则切换算法的实现越来越重要,必须发展新的技术来提高切换算法的有效性,在用户满意度和网络效率间形成平衡。智能和优化切换算法对像集成自组网(Ad hoc)和蜂窝网络结构的混合网络具有很好的适应性和鲁棒性,能够根据未来混合网络中的各种业务类型的服务质量需求、网络状态以及移动节点条件等多种因素的变化进行自适应切换,可以运用这些智能优化算法来进行更加有效的切换判决,从而提高系统的性能。更进一步的研究方向是在集成Ad hoc和蜂窝网络的环境下,使用智能或优化技术设计垂直切换算法来提高系统整体性能。     

Hierarchical Dynamic Bandwidth Allocation Algorithm for Multimedia Services over Ethernet PONs

In this paper, we propose a new dynamic bandwidth allocation (DBA) algorithm for multimedia services over Ethernet PONs (passive optical networks). The proposed algorithm is composed of a low‐level scheduler in the optical network unit (ONU) and a high‐level scheduler in the optical line terminal (OLT). The hierarchical DBA algorithm can provide expansibility and efficient resource allocation in an Ethernet PON system in which the packet scheduler is separated from the queues. In the proposed DBA algorithm, the OLT allocates bandwidth to the ONUs in proportion to the weight associated with their class and queue length, while the ONU preferentially allocates its bandwidth to queues with a static priority order. The proposed algorithm provides an efficient resource utilization by reducing the unused remaining bandwidth caused by the variable length of the packets. We also define the service classes and present control message formats conforming to the multi‐point control protocol (MPCP) over an Ethernet PON. In order to evaluate the performance, we designed an Ethernet PON system on the basis of IEEE 802.3ah “Ethernet in the first mile” (EFM) using OPNET and carried out simulations. The results are analyzed in terms of the channel utilization, queuing delay, and ratio of the unused remaining bandwidth.     

A Novel Effective Bandwidth Based Call Admission Control for Multimedia CDMA Systems

A novel Call Admission Control(CAC)scheme is proposed for multimedia CDMA systems.The effectivebandwidth of real time calls is reserved in the CAC with the consideration of active factors.The admission of non-real timecalls is controlled by the system according to the residual effective bandwidth left from real time calls.Simulation resultshave shown that the novel CAC has greatly enlarged the admission region for real time calls and make the transmission de-lay of non-real time calls under an acceptable level.     

普适环境下带宽自适应的组播策略

提出一种以树状拓扑为主干,Mesh状拓扑为辅助的组播策略.首先定义严格单源树状拓扑,并根据普适环境下结点的自治性行为提出放松单源树状拓扑.其次分析树状拓扑动态性带来的带宽瓶颈问题.通过Mesh状辅助拓扑和结点带宽使用情况动态调整结点状态,实现了自适应的带宽使用策略,保证了较高的使用率和可用性.分析模拟结果表明,与现有的方法相比,该策略能够取得较好的组播性能.     

On the Capacity Enhancement of a Cellular CDMA Channel with Asymmetrical Bandwidth Allocation

Capacity enhancement of cellular CDMA is analyzed using an asymmetrical-bandwidth-allocation approach. Cellular CDMA systems with and without successive interference cancellation are considered. The main source of interference is interuser interference and, in particular, a 9-cell configuration is employed to account for interference from surrounding cells. By transferring more bandwidth or, equivalently, processing gain from the forward link to the reverse link, we have effectively balanced their performance and raised the overall capacity of the cellular system. The optimum bandwidth allocation is easily obtained from the performance curves of both links. For a typical cellular CDMA with a bit error rate of 10-³, the capacity gain of this approach is about 40%. If successive interference cancellation is employed and both links have the same quality, then both links should have equal bandwidth. However, in a situation where imperfect power control occurs, our studies indicate that using interference cancellation alone achieves a 25% increase in capacity, while enhancement with an asymmetrical bandwidth allocation overlay raises this gain to 68%.     

On Channel Adaptive Multiple Access Control without Contention Queue for Wireless Multimedia Services

As tetherless multimedia computing environments are becoming much desired, broadband wireless communication infrastructures for providing wireless multimedia services will play an important role, and thus, are expected to proliferate. However, despite much research efforts have been expended, the multiple access control of the precious bandwidth remains a challenging problem because of the existence of two common drawbacks in the state-of-the-art protocols: (1) channel condition is ignored or not exploited, and (2) inflexible or biased time slots allocation algorithms are used. Indeed, existing protocols mostly ignore the burst errors due to fading and shadowing, which are inevitable in a mobile and wireless communication environment. A few protocols take into account the burst errors but just handle the errors in a passive manner. Most of the existing protocols employ an inflexible or biased allocation algorithm such that over-provisioning may occur for a certain class of users at the expense of the poor service quality received by other users. In this paper, a new MAC protocol, called SCAMA (synergistic channel adaptive multiple access) is proposed. The proposed protocol works closely with the underlying physical layer in that through observing the channel state information (CSI) of each mobile user, the MAC protocol first segregates a set of users with good CSI from requests gathered in the request contention phase of an uplink frame. The MAC protocol then judiciously allocates information time slots to the users according to the respective traffic types, CSI, urgency, and throughput, which are collectively represented by a novel and flexible priority function. Despite that contention request queue is not used in the protocol, the SCAMA protocol is robust in that it can avoid the congestion collapse which occur in other protocols.     

基于漏窗机制实时自适应多媒体同步

本文分析了实时多媒体同步问题以及相关研究,提出了一个基于漏窗机制实时自适应多媒体同步方案,该方案具有算法简单的特点,并且具有良好的自适应能力,可以适应各种网络变化,各种延迟特性,同样也适用于各种媒体类型,完全可以满足实时多媒体同步的需求。     

移动电视业务动态自适应带宽管理方案

为了向移动电视支持的无线移动多媒体应用提供服务品质保证,提出一个动态自适应的带宽管理方案的建议.比较于现存的带宽管理方案,在接纳同样数目的新多媒体流的情况下,建议的方案减少了需要进行服务质量下滑多媒体流的数目和发生频繁品质改变的可能性.     

Spectral Efficiency of Dynamic Time Division Duplex Fixed Wireless Cellular System for Asymmetric and Dynamic Multimedia Traffic

We analyze spectral efficiency of dynamic time division duplex in a fixed wireless cellular network. Conventionally, spectral efficiency has been analyzed for static and fully loaded systems. In this paper, we investigate how asymmetric and dynamic traffic affect the spectral efficiency of Time-Division-Duplex (TDD) systems. Recently, dynamic TDD (D-TDD) has gained much attention as an efficient duplex scheme for high-speed data communications, because adaptive switching ability enables the system to obtain statistical multiplexing gain by exploiting dynamic and asymmetric data traffic. However, it has been noted that a rather strong co-channel interference can be present due to adaptive switching in a cellular network that uses frequency reuse. Thus, benefits of dynamic TDD may not be justifiable unless a proper countermeasure is employed. To suppress the effect of strong co-channel interference, we employ time slot allocation (TSA) strategy along with sector antenna layouts, as proposed in our previous work Jeong and Kavehrad (IEEE and Transactions on communication, Vol. 50, no.10 pp. 1627–1636, 2002). We note that higher spectral efficiency is obtained in D-TDD systems by employing TSA strategy. We also evaluated spectral efficiency of D-TDD system employing adaptive modulation, assuming that traffic is delay tolerant. It is observed that five times higher spectral efficiency can be obtained by employing adaptive modulation. The effect of variance of ratio of offered load on uplink and downlink is also evaluated. Our computer simulation results show that spectral efficiency of D-TDD system with time slot allocation algorithm is more than that of static TDD (S-TDD) over a large range of traffic variation. In conclusion, D-TDD system can take advantage of statistical multiplexing gain of dynamic traffic by adaptively positioning the boundary to the varying traffic bandwidth in its two-way transmissions when TSA strategy is employed for suppression of strong co-channel interference.     

一种IEEE 802.16无线网络的优化带宽调度策略

提出了一种基于预测的自适应实时轮询业务带宽分配机制:SS依据当前带宽需求和以往的实际分配带宽,对实时业务数据包所需求的确切带宽进行预测并调度.给出了数学分析模型和仿真,结果表明,与传统的带宽分配机制相比,该自适应的带宽分配算法能更好地改善系统性能,提高吞吐量,减少时延,减少缓冲区需求.