A Multi-Hop Resource Reservation Scheme for Seamless Real-Time QoS Guarantee in WiMedia Distributed MAC Protocol

In this paper, a multi-hop range conflict-free resource reservation scheme for UWB (Ultra Wide Band) WPAN (Wireless Personal Area Network) with D-MAC (Distributed Medium Access Control) is proposed. Unlike the centralized IEEE 802.15.3 MAC, the D-MAC UWB specified by WiMedia Alliance supports DRP (Distributed Reservation Protocol) mechanism which makes all devices be self-organized and removes the SOP (Simultaneous Operating Piconet) problem, i.e., packet collisions between overlapped piconets in the centralized IEEE 802.15.3 MAC. However, since each device’s mobility perspective in multi-hop environment has not been taken into account in the current WiMedia D-MAC, it may cause a “mobile” hidden node problem. In addition, once a DRP conflict occurs due to the mobile hidden node problem, only one of the DRP reservations involved in that DRP conflict maintains the reserved MASs, while the other DRP reservations must be terminated and DRP negotiations for them have to be re-started although only a few MASs are overlapped. Such DRP termination and renegotiation time delays due to the DRP conflicts can be a critical problem to the mobile devices transceiving real-time QoS traffic streams. Therefore, we propose a mechanism to prevent and resolve multi-hop range DRP conflicts due to each device’s mobility in D-MAC environment and demonstrate its guaranteed Seamless QoS and prioritized real-time QoS performances via numerical analyses.     

A Cooperative MAC Protocol for QoS Enhancement in Wireless USB Networks

Wireless USB (WUSB) is the USB technology merged with WiMedia PHY/MAC based on success of wired USB, and it can be applied to various mobile applications such as laptop, cellular phone, etc. Also, WUSB can provide the better user convenience than wired USB applications as well as be applied to the legacy USB application, since it provides high speed connection between host and devices for the compatibility with USB 2.0 specification and removes the cable among devices using the USB protocol. However the current WUSB protocol can’t prevent the QoS degradation occurred by mobile nodes with low data rate. This problem causes the critical problems in QoS provisioning to isochronous streams and mobile applications. Therefore, we propose a new cooperative MAC protocol for WUSB network with virtual MIMO (multi input multi output) link. Based on instantaneous channel state information among WUSB devices, our proposed protocol can intelligently select the transmission path with higher data rate between WUSB host and WUSB device as well as between WUSB device and WUSB device. Thus our proposed protocol can provide advanced QoS with minimum delay for real-time multimedia services.     

A Centralized MAC Protocol for QoS Support in UWB-Based Wireless Networks

In this paper we introduce a novel MAC protocol that provides Quality of Service (QoS) support for multimedia traffic in UWB-based wireless local area networks. The proposed protocol allocates transmission opportunities to QoS and best effort traffic using a set of scheduling and resource control algorithms. The algorithms account for the UWB characteristics such as the co-existence of multiple simultaneous transmissions as well as the possibility of dynamically assigning the nodes' transmission rate and power. The simulation results show that the proposed protocol can provide QoS support while optimizing resource utilization. Yuechun Chu received her B.Sc. degree in electrical engineering from Shanghai University, China, in 1996 and M.Sc. degree in electrical engineering from University of Science and Technology of China in 1999. She is currently pursuing the Ph.D. degree in the department of electrical and computer engineering at the University of Massachusetts Amherst. Her research interests include MAC protocol design for UWB-based networks, wireless multimedia applications, and architectures and protocols for wireless networks with QoS guarantees. Aura Ganz is currently an Associate Professor and Director of the Multimedia Networks Laboratory at the ECE Department, University of Massachusetts at Amherst. She has experience in topics related to multimedia wireless networks, optical networks and ubiquitous computing. The research results are validated by a combination of analytical, simulation and prototyping tools. She has published a book “Multimedia Wireless Networks: Technologies, Standards and QoS” (Prentice Hall) and authored over one hundred and fifty peer reviewed publications. Dr. Ganz received her BSc, MSc and Ph.D degrees in Computer Science from the Technion in Israel.     

一种提供良好QoS保障的Ad Hoc网络MAC协议

为有效减小Ad Hoc网络实时业务节点的信道接入时延,提升对多媒体业务的服务质量(QoS)保障,在研究时隙分配类多址协议的基础上,设计了一种新的基于时隙重构的分组预约协议。新协议时隙结构简单,具有较好的冲突化解能力,通过对空闲数据时隙的重构利用以及层级式的接入控制,取得了较好的时延保障性能。     

PLC家庭网络MAC协议与QoS保证

由于电力线介质条件恶劣,物理信道传输不稳定,PLC MAC协议的设计较为困难.本文首先介绍了PLC家庭网络的拓扑结构和多媒体业务的QoS要求,然后分析和比较了各类MAC协议对PLC家庭网络的适用性和QoS保证能力,并对有竞争与无竞争的PLC MAC协议研究的最新成果及其采用的QoS保证机制进行了分析.本文认为有竞争与无竞争方式相结合的混合型MAC协议是最适合PLC家庭网络的MAC协议.     

MAC Protocols for Distributed Cooperative Communication Networks

Distributed cooperative networks use the cooperation among nodes to fulfill network resource sharing. However,designing an efficient Media Access Control (MAC) protocol is a key issue for the distributed cooperative network. Based on the principle of MAC-layer cooperation,this paper discusses problems and challenges for MAC protocol design in the distributed cooperative network. Through the analysis of typical cooperative MAC protocols and their performance,this paper concludes that only a reasonable MAC pr...     

分布式协作通信网络中的MAC层协议

分布式协作网络通过节点间的相互合作来达到网络资源的共享,然而如何设计高效的媒体访问控制（MAC）层协议是分布式协作通信网络中的核心问题之一。文章基于MAC层协作的动机,探讨了分布式协作网络中MAC层协议设计所面临的问题和挑战,基于近年来涌现的典型协作MAC协议和协议性能的分析,得出结论：只有全面考虑分布式网络的特点和需求,合理地设计协议的各个环节,才能使协同通信技术在分布式网络中得到更好应用。     

Mobility and QoS Support in Mobile IP Networks

1　IntroductionAnall IP basedmobilenetworksuchas 4G ,whoseaccessandcorenetworksarebasedonIP ,hasintrinsicadvantagesoverits predecessors.Forstarters ,IPiscompatiblewith ,andindependentof,theactualradioaccesstechnology .WithIP ,onecanbasicallygetridofthelock inbetweenthecorenet workprotocol,thelinklayerandtheradioaccessprotocol.IPtoleratesavarietyofradioaccessproto cols.Itsupportsthedesignofacorenetworkthatgivescompleteflexibilitynomatterwhattheradioaccessnetworkis.Onecouldbeacorenetworkpro…     

A New MAC Protocol Ensuring the Multimedia Traffic QoS for CDMA Networks

This paper describes the CDMAC, a new Medium Access Control (MAC)protocol for multimedia traffic in CDMA wireless networks. Theprotocol intends to extract the maximum capacity and flexibilityout of the CDMA scheme and at the same time guarantee the expectedQoS of different service types. CDMAC is able to maintain QoSrequirements thanks to the shaping, policing and trafficdifferentiation performed by the scheduler. Moreover, an iterativealgorithm, applied at the beginning of each frame, is used to findthe optimal power vector for all mobiles present in the system,which maximize the system capacity. The basic constraint of thecapacity maximization process is that the BER QoS of eachconnection should be fulfilled. Finally a distributedimplementation, feasible in a practical scenario, is presented.     

A Robust and Cooperative MAC Protocol for IEEE 802.11a Wireless Networks

In wireless networks, it is well known that the interference of hidden nodes can interrupt frame receptions. Although several solutions have been proposed to alleviate the problem of DATA corruptions at receivers, control frame corruptions at transmitters have not been considered yet. In this paper, we propose an enhanced MAC protocol, called Robust and Cooperative Medium Access Control (RCMAC), to improve the network throughput and fairness by reducing control frame losses at transmitters. RCMAC uses a relay mechanism to allow transmitters of long distance links to receive control frames more robustly by relaying control frames via relay nodes. Furthermore, RCMAC improves the network throughput through fast two-hop DATA transmissions via relay nodes. Our extensive simulation results show that RCMAC has better performance than existing well-known MAC protocols.     

Ad Hoc网络支持QoS保障的多信道MAC协议

提出一种基于多信道的Qo S保障方案,结合业务区分和资源预留两种Qo S保障策略,保证优先级高的业务及时接入信道;并且建立节点发送链表,给数据通信预留一段时间,实现数据信道上连续的帧交换,有效地使用了数据信道资源。     

Distributed Sequential Access MAC Protocol for Single-Hop Wireless Networks

Medium access control overhead is the primary reason for low throughput in wireless networks. Performing blind contentions, contentions without any information of other contenders, and exchanging control message are time-consuming control operations. In this study, we propose a new MAC protocol called distributed sequential access MAC (DSA-MAC) which provides the transmission order without any explicit control operations. It may induce very light control overhead; therefore, compared to existing wireless MAC protocols, DSA-MAC can remarkably enhance network throughput.     

一种适用于多跳Ad Hoc网络的增强型协作多址接入协议

 针对多跳Ad Hoc网络提出一种增强型协作多址接入协议.该协议联合考虑数据传输速率和隐藏终端对协作网络性能的影响,通过优化协议的握手规则和协同节点的选择策略,从而在不引入开销的条件下,有效提高了网络的饱和吞吐量并降低了业务的接入时延.另外,基于对节点行为及其所处状态概率的分析,本文建立了协作多址协议在多跳Ad Hoc网络中的饱和吞吐量分析模型,并给出相应的理论分析结果.最后,通过在多跳Ad Hoc网络中的大量仿真,评估了所提增强型协作多址接入协议和分析模型的性能.仿真结果表明:相对于已有的协作多址协议该协议能够有效提高网络的饱和吞吐量.此外,仿真结果和理论分析结果能够很好的匹配,从而也证明了分析模型的正确性和有效性.     

安全保障：无线Mesh网络中支持QoS的DSR路由协议的改进与实现

随着无线Mesh网络传输多媒体业务需求的增加,要求网络支持服务质量（QoS）,本文基于DSR协议设计了一个支持QoS的路由协议算法QDSR（QoS-DSR）。该算法保证了数据流的带宽、时延的QoS需求,根据路径跳数和节点拥塞情况定义路由代价函数,选择最优路径。仿真结果表明,与DSR相比,QDSR提高了网络吞吐量,降低了平均端到端延时,提高了网络利用率,更好地满足业务的QoS需求,并且具有更强的适用性和可扩展性。     

一种基于服务质量的节能无线传感器网络MAC协议

为了平衡网络能耗与QoS,提出了一种基于服务质量的节能MAC协议-QE-MAC.该协议一方面采用由Hill等人提出的低能量载波侦听技术降低节点能耗,另一方面,采用冲突避免、回复确认、区分优先级和失败重传等机制确保分组传输的可靠性,以及使用业务固定短周期发起策略来解决分组接收的时延过大问题.模拟实验和测试结果都表明,QE-MAC能够以较低的网络能耗提供良好的QoS.     

A Priority MAC Protocol to Support Real-Time Traffic in Ad Hoc Networks

Carrier sense multiple access and its variants have been widely used in mobile ad hoc networks. However, most existing access mechanisms cannot guarantee quality for real-time traffic. This paper presents a distributed medium access control protocol that provides multiple priority levels for stations to compete for the wireless channel. One common channel is assumed to be shared by all stations. Stations are assumed to be able to hear each other (i.e., the network is fully connected). The channel is accessed by stations according to their priorities, and for stations with the same priority, they send frames in a round robin manner. The channel access procedure is divided into three stages: priorities classification period, ID initialization period, and transmission period. Simulation results indicate that our protocol provides high channel utilization and bounded delays for real-time frames.     

一种基于Ad Hoc网络的协作MAC方案

在 IEEE 802.11b MAC层协议的研究基础上,提出了一种基于无线Ad Hoc网络的最佳中继选择策略,该策略综合考虑瞬时信道信息和节点剩余能量,能够有效防止信道条件好的节点的过度使用,并能保证系统高吞吐量。文中以饱和吞吐量和网络生存时间为性能指标,对新算法和以往协作MAC算法进行仿真和比较,结果表明新算法在网络吞吐量下降不明显的情况下,能大大增加网络生存时间。     

BTAC: A Busy Tone Based Cooperative MAC Protocol for Wireless Local Area Networks

Cooperative communications has been actively studied as an effective approach to achieve multi-user/spatial diversity gains and better overall system performance by coordinating multiple users in a dynamic wireless network to share their resources and capabilities. Based on the concept of cooperative communications, this paper proposes and analyzes a Busy Tone based cooperative Medium Access Control (MAC) protocol, namely BTAC, for multi-rate Wireless Local Area Networks (WLANs). A cross-layer Markov chain model is then developed to evaluate the performance of BTAC under dynamic wireless channel conditions. Analytical and simulation results show our BTAC protocol is simple, robust, fully compatible with the IEEE 802.11b standard and can achieve better throughput and delay performance than the standard Distributed Coordination Function (DCF) protocol and the recently-proposed CoopMAC protocol.     

无线协作网络中具有QoS保障的 能量高效的干扰源选择方法

Aiming at achieving better Quality of Service (QoS) provisioning in distributed wireless cooperative networks, a novel energy efficient jammer selection approach is proposed in this paper. We employ Secrecy Capacity (SC) to characterize the security of transmission. In order to accurately describe the time-varying characteristic, related channels are modeled as Finite-State Markov Channels (FSMCs). The remaining energy of candidate node is considered in a similar way. Accordingly, jammer selection is modeled as Restless Multi-armed Bandit problem for the sake of energy balance and security. Primal-dual heuristic and priority-index heuristic are exploited to select the optimal jammer quickly and effectively. In the simulation, numerical evaluation of SC and networks lifetime results show that the proposed approach outperforms the existing ones.     

A Fair and QoS-Aware Resource Allocation Scheme in UWB WPANs with WiMedia Distributed MAC

Merits of distributed medium access control specified by WiMedia Alliance such as distributed nature and high data rate make it a favorite candidate standard for high rate wireless personal area network. However, the current WiMedia MAC standard has not considered supporting Quality of Service (QoS) even though QoS parameters such as a range of service rates are provided to each traffic stream (TS). Therefore, we propose a fair and QoS-aware resource allocation method that provides a fair and maximized QoS for all TSs according to the current traffic load condition and differentiates SoQ among different QoS classes while guaranteeing fairness of SoQ within a QoS class in a fully distributed manner. Even in case that the traffic load varies, each device independently recognizes the changes and calculates fair and maximum allowable service rates for TSs. From the simulation results, it is proven that the proposed method achieves high capacity of TSs and fair QoS provisioning under various traffic load conditions.