Handoff resource prediction in multimedia wireless networks

This paper presents a local-based approach for predicting handoff resources in multimedia wireless networks, where the underlying prediction mechanism is the recursive least-squares (RLS) algorithm. Performance of the proposed handoff resource prediction scheme is evaluated for a multimedia wireless network characterized by various handoff traffic conditions, different bandwidth requirements, and general call and channel holding time distributions. The accuracy of handoff resource prediction is measured in terms of a mean-square-error metric. Results from performance evaluation show that the proposed RLS-based scheme has better resource prediction accuracy than Wiener-filter and autoregressive (AR) processes. It is shown that the proposed RLS-based handoff resource prediction scheme achieves capacity gains of up to 60% and 23% compared to the Wiener- and AR-based schemes, respectively.     

An adaptive resource reservation strategy for handoff in wireless CDMA cellular networks

A threshold-based adaptive resource reservation scheme for soft handoff calls in wireless code division multiple access (CDMA) cellular networks is proposed. The scheme gives handoff calls a higher admission priority than new calls, and is designed to adaptively adjust the reservation-request time threshold according to the varying traffic load. The individual reservation requests form a common reservation pool, and handoff calls are served on a first-come, first-served basis. With the proposed scheme, a minimum grade of service (GoS) in terms of new call blocking and handoff call dropping probabilities can be achieved. Simulation results are given to demonstrate the improvement in the GoS performance in comparison with other schemes.     

QoS on LEO satellites

This paper discusses the role played by wireless network infrastructure in mobile commerce applications. The user's perception of service quality depends on the available resources and capabilities of the network. The new generation of low earth orbit (LEO) mobile satellite networks, deployed at altitudes ranging from 500 km to 2000 km, are well suited to handle multimedia traffic and to offer end-users equipped with hand-held devices at low cost-per minute access to network services. A wide range of multimedia services and applications are expected to provide users with QoS based asynchronous transfer mode (ATM) technology. LEO satellite networks provide significant wide area coverage, unique broadcast capability, ability to meet different QoS requirements, the ability to communicate with hand-held devices and low cost access. The main resources in the LEO networks are satellite radio bandwidth and the buffer capacity of the onboard ATM switch. The most important ATM resource management function is connection and call admission control. The real objective of this article is to introduce the general framework of resource reservation in multimedia LEO satellite networks which offers a unified approach to handle all the important aspects of resource reservation and radio-resource management functions required by E-commerce and mobile commerce applications.     

一种有效的802.16 BWA系统MAC层QoS框架

IEEE 802.16系列标准定义了WiMAX的无线空中接口,尽管标准详细的定义了MAC层信号机制,但并没有一套完整的资源管理调度机制,而资源管理和调度是影响QoS性能的重要部分.本文首先简要介绍了IEEE 802.16协议,分析了其QoS机制的主要内容,包括带宽的请求分配机制,准人和调度机制等.然后提出了一套有效的QoS框架,主要包括准入控制策略和上行调度策略.为了让不同业务的QoS得到保证,文章重点探讨了多优先级公平队列算法(MPFQ),通过这套机制,可以为不同级别的业务提供不同等级的Qos服务.     

Resource management in LEO satellite networks

To provide truly global coverage needed by increased Personal Communication Services (PCS), a new generation of mobile satellite networks has been proposed. These low Earth orbit (LEO) mobile satellite networks handle multimedia traffic and can be used for non-real-time as well as real-time service to remote areas. Due to the many handoffs, resource management and connection admission control are important tasks for fair bandwidth sharing and QoS guarantees. Because the total link capacity has to be divided among several carriers and given the limited buffer capacity of the ATM switch, resource management is vital. It ensures the ability of the network to provide users with their negotiated QoS while protecting the network and the end-systems from congestion. We introduced a simple connection admission control (CAC) priority policy based on the delay and cell loss requirements for the investigated types of traffic. We took into account the handoff status of the satellite beams involved. Thus, we propose an onboard buffer architecture with separated buffers for new calls and intra-satellite handoff calls. The priority scheme applied is as follows: highest priority is given to CBR, followed by rt-VBR, nrtVBR and ABR.     

Fairness based channel borrowing strategy in multimedia LEO satellite communications

A novel bandwidth allocation strategy along with a connection admission control technique was proposed to improve the utilization of network resources. It provides the network with better quality-of-service (QoS) guarantees, such as new call blocking probability (CBP) and handoff call dropping probability (CDP) in multimedia low earth orbit (LEO) satellite networks. Simulation results show that, compared with other bandwidth allocation schemes, the proposed scheme offers very low call dropping probability for real-time connections while, at the same time, keeping resource utilization high. Finally we discussed the fairness for the borrowed nonreal-time connections under three different channel borrowing methods. Translated from Journal on Communications, 2006, 27(8): 10–17 [译自: 通信学报]     

Enhanced soft-handoff scheme for real-time streaming services in intelligent transportation systems based on CDMA

Code division multiple access (CDMA)-based radio-on-fiber road-vehicle communication systems were proposed to support real-time streaming services in intelligent transportation systems (ITSs). Soft handoff should be provided for real-time streaming services because these services are required to guarantee real-time property and quality of service (QoS). However, soft handoff of real-time streaming services causes the shortage of resource in view of the system. In this paper, the double-adjustment soft-handoff (DASH) scheme is proposed to support seamless service regardless of the shortage of resource and maximize the resource efficiency when real-time streaming services are served in CDMA-based ITSs. The DASH scheme adjusts the data rate of a call when it starts and finishes soft handoff. The performance of the DASH scheme is evaluated by analytical and simulation methods. Performances are evaluated with respect to the blocking probability, the handoff failure probability, and the carried traffic. Numerical results show that the proposed scheme can give relative good maintenance of calls and good throughput.     

ASAR: An ant-based service-aware routing algorithm for multimedia sensor networks

Aimed at three basic services (event-driven, data query and stream query), the paper presents a QoS routing model for multimedia sensor networks. Moreover, based on the traditional ant-based algorithm, we propose an ant-based service-aware routing (ASAR) algorithm. The ASAR chooses suitable paths to meet diverse QoS requirements from different kinds of services, thus maximizing network utilization and improving network performance. Finally, extensive simulation is conducted to verify the effectiveness of our solution and we give a detailed discussion on the effects of different system parameters. Compared to the typical routing algorithm in sensor networks and the traditional ant-based algorithm, our ASAR algorithm has better convergence and significantly provides better QoS for multiple types of services in the multimedia sensor networks. __________ Translated from Acta Electronica Sinica, 2007, 35(4): 705–711 [译自: 电子学报]     

Predictive call admission control for multimedia streaming in CDMA cellular environments

Third-generation (3G) wireless networks based on code-division multiple access (CDMA) have been engineered to provide mobile users with voice as well as advanced packet data services. Support of Internet-based multimedia streaming services is considered a critical factor for future deployment of such networks. Provisioning streaming services in a dependable way, however, requires supporting data transmission at relatively high data rates while maintaining session quality during both intracell and intercell user movements. In this paper, an adaptive bandwidth allocation and admission control scheme is proposed for managing network resources for a streaming service. Streaming requests are assumed to be served by an adaptive server capable of choosing suitable video streaming parameters (e.g., video resolution, frame rate, and encoding parameters) in response to possible requests from the wireless network to vary the currently allocated bandwidth. The devised admission control scheme exploits a priori knowledge of user mobility patterns to minimize the risk of running into an overload condition after acceptance of a new multimedia streaming connection. The obtained simulation results show that, compared to a nonpredictive admission control scheme, the proposed scheme achieves a lower forced-termination probability and higher throughput, while consuming less base-station transmission energy.     

Performance evaluation of soft handoff for multimedia services in intelligent transportation systems based on CDMA

To support multimedia services in intelligent transportation systems (ITS), CDMA based radio-on-fiber road-vehicle communication systems were proposed. Soft handoff should be provided for multimedia services because these services are required to guarantee real-time property and quality of service (QoS). The performance evaluation of soft handoff is important in view of system management such as determination of optimal resource allocation, cell configuration, and admission strategy. But, the performance evaluation of soft handoff when multimedia services are serviced has not been previously researched, even though there have been some previous works for voice-call service. In this paper, we develop a new analytical model of soft handoff when multimedia services are served in CDMA based ITS. We evaluate the performance of soft handoff scheme by analytical and simulational method. Blocking probability, handoff failure probability and carried traffic are obtained.     

Cross-Layer Design of Dynamic Bandwidth Allocation in DVB-RCS

In this paper, a novel cross-layer framework for optimizing the dynamic bandwidth allocation (DBA) of a digital video broadcast (DVB)-return channel satellite (RCS) system using adaptive coding is proposed. The design of the medium access control (MAC) methods taking into account the adaptive physical layer and higher layers' quality of service (QoS) requirements is cast as an optimization problem by using the network utility maximization (NUM) framework applied within the satellite subnetwork. Hierarchical and global solving procedures fully compliant with the DVB-RCS standard are proposed. They do not only provide minimum bandwidth guarantees but also maximize fairness. Further, they allow a joint optimization of the time slot size and overall system efficiency while minimizing signalling overhead. A reduced computational complexity algorithm to solve the DBA problem is presented. In practical terms, it increases the number of connections with absolute and relative QoS requirements the system can manage and facilitates the interoperability of the satellite network within an Internet protocol (IP) environment.     

An efficient wireless resource management scheme to support handoff data recovery in packet-switched cellular multicast networks

To support data transfer reliability similar to that of a fixed multicast network, migrating terminals in a packet-switched cellular wireless multicast network supporting reliable multicast data transfer need to recover lost data during handoffs before they can merge into the respective multicast groups in the new cells. The multicast groups in packet-switched wireless networks typically share resources on a statistical multiplexed basis. To minimize impact on other terminals, this paper proposes to allow part of a multicast group's assigned bandwidth to be shared by the handoff terminals for transient data recovery using the proposed Weighted Fair Share (WFS) method with optimal weight selection. Handoff terminals are admitted into the new cell using the proposed Multicast Connection Admission Control (MCAC) scheme. These methods together constitute the Fair and Efficient Wireless Multicast resource management Scheme (FEWMS) presented in this paper. Under FEWMS, a migrating terminal can quickly recover lost data and merge into the existing multicast group during a handoff. Simulations using self-similar traffic sources show that the proposed method reduces the handoff failure probability of migrating terminals and the average packet delay of the multicast group, and increases the overall system throughput, compared with an existing proposal. Evaluations of different performance measures show that the system throughput does not give a complete picture of the system performance, as different resource management schemes may have substantial impact on other performance measures such as average delay and handoff failure probability.     

CMT‐CQA: Cross‐layer QoS‐aware adaptive concurrent multipath data transfer in heterogeneous networks

Stream control transport protocol (SCTP)‐based concurrent multipath transfer (CMT) can help multi‐homed devices to increase their throughput by making use of parallel transmissions over multiple paths and bandwidth aggregation. However, if CMT cannot identify wireless error, it cannot really achieve the desired performance. Furthermore, if CMT only utilizes all available paths for data delivery, it will undoubtedly degrade application‐level performance since the asymmetric paths may involve large quality differences. This paper proposes a novel cross‐layer quality‐of‐service (QoS)‐aware adaptive CMT (CMT‐CQA) with the following aims: (i) to provide an adaptive ‘CMT‐to‐partial CMT’ adjustment strategy for efficient bandwidth aggregation by jointly considering transport layer QoS, MAC layer QoS, and path history information; (ii) to address an enhanced congestion window (cwnd) fast recovery mechanism to reduce bursty transmission in multi‐homed wireless network environments where fail‐over occurs frequently; and (iii) to introduce a proper multimedia transmission behavior to improve users' quality of experience (QoE) for multimedia streaming service. Simulation results show that CMT‐CQA outperforms the existing CMT solutions in terms of performance and QoS. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

基于虚剩余带宽的多个路由表的多类别QoS路由

现在以及将来的网络通需要支持有QoS请求的应用,而这对于大型复杂的网络结构是一个挑战,一些研究已经解决了QoS路由的一部分问题.本文在虚剩余带宽的多个路由表的基础上提出了一种新的QoS路由,允许在多个业务类之间动态地共享链路资源.路由算法尽可能为QoS业务选择best-effort业务轻载的链路,从而整体提升网络的性能.通过进一步的仿真,可以看出在链路负载不均衡的时候,QoS业务的丢包率以及best-effort业务的吞吐量都有很大的改善.     

基于业务优先级的电力调度数据网拥塞规避算法

为了保障电力调度数据网的可靠性,提出一种基于业务优先级的电力调度数据网拥塞规避算法。首先,根据不同业务对时延、带宽要求的不同,将其划分为具有不同优先等级的业务。其次,判断节点的拥塞状态,并对严重拥塞或中度拥塞节点缓存队列中的数据按业务优先级进行位置调整,丢弃位于严重拥塞阈值后的低优先级业务,并通知其源节点重新选择路由。最后,建立适应度函数,根据二进制粒子群优化(Binary Particle Swarm Optimization,BPSO)算法进行路由重新选择。仿真结果表明,算法优先保证了高优先级业务的服务质量(Quality of Service,QoS),从而优化了网络资源,均衡了网络负载。     

电力通信ATM网络中的QoS技术

介绍了ATM网络中的端到端QoS技术的概念,分析了QoS定义的基本参数、ATM针对不同QoS提供的不同业务,以及QoS在ATM网络中的实现方法;提出了电力通信网中数据按ATM业务类划分的方法,指出在电力通信中采用QoS技术的必要性。     

多媒体应用的分布式动态信道选择算法

在异构无线网络上支持多媒体应用是一个普遍和具有挑战的问题.对异构网络下不同用户传输不同的多媒体应用提出了一种分布式动态信道选择算法.不同于以前的研究很少考虑多媒体用户的应用层需求,算法考虑了不同多媒体用户有不同的传输速率需求、不同的效用函数和不同的时延阀值等.为了有效地分布式管理可用信道资源,通过对优先级虚拟队列进行优...     

面向需求响应业务的灵活弹性传输策略

随着需求响应(demand response,DR)不断深化实践,未来需要依靠高可靠的信息交互支撑精细化的DR控制.然而在DR无线通信场景下,复杂的信道环境极大影响DR高效的信息交互,现有技术难以匹配和满足DR业务的特性.针对DR无线传输中的信道质量问题,设计了面向DR业务的灵活弹性传输策略,该策略通过自适应编码实现....     

基于智能光网络系统的配用电业务承载方案研究

配用电无源光通信网络是连接10 kV及0.4 kV设备的通信基础设施,具有高效、稳定、安全等特点。针对配电领域业务分布范围广、安全形势严峻、光纤资源规模大、运维抢修难度高等难题,设计配用电多业务综合承载及安全防护方案。提出一种光网络智能管理系统,能够实现光纤资源标签电子化、运维抢修智能化目标。基于该智能系统自动生成网络拓扑信息,研究并提出了一种面向多业务的QoS(服务质量)路由策略。通过仿真分析可知,该策略采用的群智能优化算法可为特定业务提供端到端QoS最优转发路径,保障业务的通信QoS需求,收敛速度较快,提升了通信网对电力业务的承载能力。     

多跳中继通信网STDM模式链路容量分析

下一代基于中继节点的多跳蜂窝网络将支持更高速率的多媒体移动业务.多跳中继链路能够有效改善无线通信链路的信道质量,有利于系统容量的提高,但是中继节点的引入代价属于额外无线信道资源的消耗,将会降低系统容量.因此本文提出了空间时分复用(STDM)的多跳中继链路模型,使得中继无线信道资源能够空间复用,通过理论分析和数值仿真,在保证一定的链路距离下,与传统严格时间正交的模式相比,STDM模式的链路吞吐量可以成倍的提高.