ATM突发性业务阻塞控制

在ＡＴＭ网里业务阻塞控制是一个十分重要的问题，本文对一种缓冲漏桶业务阻塞控制算法在突发性业务输入情况下的性能进行了计算机模拟分析，模拟结构表明缓冲漏桶算法是一种适合于突发性业务的阻塞控制算法，文章在模拟结果的基础上给出了缓冲漏桶算法中参量选择的算法。     

Delay Analysis for Maximal Scheduling With Flow Control in Wireless Networks With Bursty Traffic

We consider the delay properties of one-hop networks with general interference constraints and multiple traffic streams with time-correlated arrivals. We first treat the case when arrivals are modulated by independent finite state Markov chains. We show that the well known maximal scheduling algorithm achieves average delay that grows at most logarithmically in the largest number of interferers at any link. Further, in the important special case when each Markov process has at most two states (such as bursty ON/OFF sources), we prove that average delay is independent of the number of nodes and links in the network, and hence is order-optimal. We provide tight delay bounds in terms of the individual auto-correlation parameters of the traffic sources. These are perhaps the first order-optimal delay results for controlled queueing networks that explicitly account for such statistical information. Our analysis treats cases both with and without flow control.      

Distributed Medium Access Control Next-Generation CDMA Wireless Networks

The next-generation wireless networks are expected to have a simple infrastructure with distributed control. In this article, we consider a generic distributed network model for future wireless multimedia communications with a code-division multiple access (CDMA) air interface. For the medium access control (MAC) of the network model, we provide an overview of recent research efforts on distributed code assignment and interference control and identify their limitations when applied in next-generation wireless networks supporting multimedia traffic. We also propose a novel distributed MAC scheme to address these limitations, where active receivers determine whether a candidate transmitter should transmit its traffic or defer its transmission to a later time. Simulation results are given to demonstrate the effectiveness of the proposed distributed MAC scheme.     

基于QoS的无线ATM网的MAC协议

首先介绍了传统OSI模型中介质接入控制（MediumAccessControl,MAC）协议及其在有线本地网中的应用。接着针对无线ATM网的特．或对两种基于服务质量（Quakity—of－Service，QoS）的MAC协议进行了详细的阐述。最后指出了它们相对于传统的MAC协议的优越性。     

Energy-Efficient, Collision-Free Medium Access Control for Wireless Sensor Networks

The traffic-adaptive medium access protocol (TRAMA) is introduced for energy-efficient collision-free channel access in wireless sensor networks. TRAMA reduces energy consumption by ensuring that unicast and broadcast transmissions incur no collisions, and by allowing nodes to assume a low-power, idle state whenever they are not transmitting or receiving. TRAMA assumes that time is slotted and uses a distributed election scheme based on information about traffic at each node to determine which node can transmit at a particular time slot. Using traffic information, TRAMA avoids assigning time slots to nodes with no traffic to send, and also allows nodes to determine when they can switch off to idle mode and not listen to the channel. TRAMA is shown to be fair and correct, in that no idle node is an intended receiver and no receiver suffers collisions. An analytical model to quantify the performance of TRAMA is presented and the results are verified by simulation. The performance of TRAMA is evaluated through extensive simulations using both synthetic- as well as sensor-network scenarios. The results indicate that TRAMA outperforms contention-based protocols (CSMA, 802.11 and S-MAC) and also static scheduled-access protocols (NAMA) with significant energy savings. This work was supported in part by the NSF-NGI grant number ANI-9813724 and by the Jack Baskin Chair of Computer Engineering at UCSC. Venkatesh Rajendran received the B.E. degree in Electronics and Communication Engineering from the Anna University in 2001, and M.S. in Computer Engineering from the University of California, Santa Cruz (UCSC) in 2003. He is currently working towards his Ph.D at UCSC. He is a graduate student researcher at the Inter-networking Research Lab (INRG). His research interests are in wireless communication system design, energy-aware media access control protocols for wireless ad hoc networks, smart sensor networks, reliable multi-casting, wireless multi-carrier communications, digital signal processing, adaptive modulation, and smart antenna systems. Katia Obraczka received the B.S. and M.S. degrees in electrical and computer engineering from the Federal University of Rio de Janeiro, Brazil, and the M.S. and Ph.D. degrees in computer science from the University of Southern California (USC). She is an Assistant Professor of Computer Engineering at the University of California, Santa Cruz. Before joining UCSC, she held a research scientist position at USC's Information Sciences Institute and a research faculty appointment at USC's Computer Science Department. Her research interests include computer networks, more specifically, network protocol design and evaluation in wire-line as well as wireless (in particular, multi-hop ad hoc) networks, distributed systems, and Internet information systems. J.J. Garcia-Luna-Aceves received the M.S. and Ph.D. degrees in electrical engineering from the University of Hawaii, Honolulu, HI, in 1980 and 1983, respectively. He is the Baskin Professor of Computer Engineering at the University of California, Santa Cruz (UCSC). Dr. Garcia-Luna-Aceves directs the Computer Communication Research Group (CCRG), which is part of the Information Technologies Institute of the Baskin School of Engineering at UCSC. He has been a Visiting Professor at Sun Laboratories and a consultant on protocol design for Nokia. Prior to joining UCSC in 1993, he was a Center Director at SRI International (SRI) in Menlo Park, California. Dr. Garcia-Luna-Aceves has published a book and more than 250 refereed papers and three U.S patents, and has directed more than 18 Ph.D. theses at UCSC. He has been Program Co-Chair of ACM MobiHoc 2002 and ACM Mobicom 2000; Chair of the ACM SIG Multimedia; General Chair of ACM Multimedia '93 and ACM SIGCOMM '88; and Program Chair of IEEE MULTIMEDIA '92, ACM SIGCOMM '87, and ACM SIGCOMM '86. He has served in the IEEE Internet Technology Award Committee, the IEEE Richard W. Hamming Medal Committee, and the National Research Council Panel on Digitization and Communications Science of the Army Research Laboratory Technical Assessment Board. HE has been on the editorial boards of the IEEE/ACM Transactions on Networking, the Multimedia Systems Journal, and the Journal of High Speed Networks. He received the SRI International Exceptional-Achievement Award in 1985 and 1989, and is a senior member of the IEEE.     

无线自组织应急通信网络的多信道介质访问控制

文章研究了多信道资源分配算法,并对其5个重要过程：获取节点请求列表过程、请求分类缓冲过程、请求队列截取过程、资源分配过程、节点使用分配结果过程进行了探讨。文章认为在算法中可以考虑增加请求信息的内容以完善分配机制,加入自适应的优先级预留比例调整机制,添加和完善更高效地分配时隙、信道二维资源。     

无线Ad Hoc网络中基于业务感知的多信道MAC协议(英文)

Existing multi-channel Medium Access Control (MAC) protocols have been demonstrated to significantly increase wireless network performance compared to single channel MAC protocols. Traditionally, the channelization structure in IEEE 802.11 based wireless networks is pre-configured, and the entire available spectrum is divided into subchannels and equal channel widths. In contrast, this paper presents a Traffic-Aware Channelization MAC (TAC-MAC) protocol for wireless ad hoc networks, where each node is equipped with a single half duplex transceiver. TAC-MAC works in a distributed, fine-grai-ned manner, which dynamically divides variable-width subchannels and allocates subchannel width based on the Orthogonal Frequency Division Multiplexing (OFDM) technique according to the traffic demands of nodes. Simulations show that the TAC-MAC can significantly improve network throughput and reduce packet delay compared with both fixed-width multi-channel MAC and single channel 802.11 protocols, which illustrates a new paradigm for high-efficient multi-channel MAC design in wireless ad hoc networks.     

一种提供时延QoS保障的无线网络MAC协议

本文从提高系统工作效率的角度出发,提出了一种基于无争用集中控制的忙队列周期查询(BQPO)控制协议.该协议为时延QoS要求较高的无线终端提供了稳定可靠的保障,通过系统建模分析获得了系统的信息分组平均等待时间的解析结果.仿真实验结果表明理论分析和仿真实验的一致性与合理性,与PCF控制方式相比,BQPO协议具有更好的稳定性和时延QoS保障.     

Performance Analysis for a New Medium Access Control Protocol in Wireless LANs

One fundamental issue in high-speed wireless local area networks (LANs) is to develop efficient medium access control (MAC) protocols. In this paper, we focus on the performance improvement in both MAC layer and transport layer by using a novel medium access control protocol for high-speed wireless LANs deploying carrier sense multiple access/collision avoidance (CSMA/CA). We first present a recently proposed distributed contention-based MAC protocol utilizing a Fast Collision Resolution (FCR) algorithm and show that the proposed FCR algorithm provides high throughput and low latency while improving the fairness performance. The performance of the FCR algorithm is compared with that of the IEEE 802.11 MAC algorithm via extensive simulation studies on both MAC layer and transport layer. The results show that the FCR algorithm achieves a significantly higher efficiency than the IEEE 802.11 MAC and can significantly improve transport layer performance.     

A-MAC: Adaptive Medium Access Control for Next Generation Wireless Terminals

Next generation (NG) wireless networks are envisioned to provide high bandwidth to mobile users via bandwidth aggregation over heterogeneous wireless architectures. NG wireless networks, however, impose challenges due to their architectural heterogeneity in terms of different access schemes, resource allocation techniques as well as diverse quality of service requirements. These heterogeneities must be captured and handled dynamically as mobile terminals roam between different wireless architectures. However, to address these challenges, the existing proposals require either a significant modification in the network structure and in base stations or a completely new architecture, which lead to integration problems in terms of implementation costs, scalability and backward compatibility. Thus, the integration of the existing medium access schemes, e.g., CSMA, TDMA and CDMA, dictates an adaptive and seamless medium access control (MAC) layer that can achieve high network utilization and meet diverse quality of service (QoS) requirements. In this paper, an adaptive medium access control (A-MAC) layer is proposed to address the heterogeneities posed by the NG wireless networks. A-MAC introduces a two-layered MAC framework that accomplishes the adaptivity to both architectural heterogeneities and diverse QoS requirements. A novel virtual cube concept is introduced as a unified metric to model heterogeneous access schemes and capture their behavior. Based on the virtual cube concept, A-MAC provides architecture-independent decision and QoS based scheduling algorithms for efficient multi-network access. A-MAC performs seamless medium access to multiple networks without requiring any additional modifications in the existing network structures. It is shown via extensive simulations that A-MAC provides adaptivity to the heterogeneities in NG wireless networks and achieves high performance.     

A MAC Protocol for Bursty Traffic Ad-Hoc Wireless LANs with Energy Efficiency

A Self-Adaptive Low Power MAC protocol with carrier sensing for ad-hoc Wireless LANs (WLANs), which is capable of operating efficiently under bursty traffic is proposed in this letter. The protocol utilizes a Learning Automaton structure at each station of the WLAN. Each such structure uses the network feedback to select the mobile station that will transmit. A low-power mode is implemented in order to significantly reduce the energy consumption of the protocol. Simulation results reveal that the low power mode of the proposed protocol reduces the average energy consumption at the mobile stations by as much as 70%.     

Modeling and Analysis of Active Queue Management Schemes under Bursty Traffic

Traffic congestion arising from the shared nature of uplink channels in wireless networks can cause serious problems for the provision of QoS to various services. One approach to overcome these problems is to implement some effective congestion control mechanisms at the downlink buffer at the mobile network link layer or at gateways on the behalf of wireless network access points. Active queue management (AQM) is an effective mechanism to support end-to-end traffic congestion control in modern high-speed networks. Initially developed for Internet routers, AQM is now being also considered as an effective congestion control mechanism to enhance TCP performance over 3G links. This paper proposes an analytical performance model for AQM using various dropping functions. The selection of different dropping functions and threshold values required for this scheme plays a critical role on its effectiveness. The model uses a well-known Markov-modulated Poisson process (MMPP) to capture traffic burstiness and correlations. The validity of the model has been demonstrated through simulation experiments. Extensive analytical results have indicated that exponential dropping function is a good choice for AQM to support efficient congestion control.     

GSHMAC: Green and Secure Hybrid Medium Access Control for Wireless Sensor Network

The cost efficiency of wireless platforms and their easy deployment enable the applicability of it in widespread application domains. Wireless sensor networks (WSNs) are not excluded from it. Their application domains vary from industrial monitoring to military applications. A WSN is a resource-constrained network and energy of the WSN node is a valuable resource. Like every other network, WSNs are also vulnerable to security attacks. A security attack can results in networks consuming more resources, leading to earlier depletion of node energy. A significant part of the resource consumption in a WSN is controlled by the medium access control (MAC) mechanism. This paper focuses on WSN MAC mechanisms and countermeasures for attacks targeting the MAC layer in a WSN. Denial of sleep attacks are the most relevant for WSN MAC as these types of attacks have shattered effects, which bring down the sensor lifetime from years to days. This paper proposes a secure hybrid MAC mechanism, Green and Secure Hybrid Medium Access Control (GSHMAC) to overcome the devastating effect of WSN MAC attacks. The proposed mechanism provides features such as collision threshold-based MAC mode control and countermeasures on WSN MAC using internal MAC mechanisms. GSHMAC shows improved energy-efficiency, delay, and throughput in the presence of attacks, as compared with state-of-art secure MAC mechanisms.     

SYN-MAC: A Distributed Medium Access Control Protocol for Synchronized Wireless Networks

In this paper, we propose a novel medium access control (MAC) protocol, called SYN-MAC (for SYNchronized MAC), based on a binary countdown approach tailored for wireless networks. SYN-MAC has several attractive features such as simplicity, robustness, high efficiency, fairness, and quality of service capability. We evaluate SYN-MAC in terms of collision probability, system throughput, and packet delay, via both analysis and simulation. Our results show that, with properly chosen parameters, SYN-MAC can achieve a very low collision probability, packet delay tolerance, and extremely high channel efficiency (of > 90%) under a wide range of traffic load. As a result, SYN-MAC may serve as an alternative to IEEE 802.11 for the wireless stations in synchronized networks.This work is supported in part by National Science Foundation CAREER Award under Award Number CNS-0347686, by U.S. Department of Energy (DoE) under Award Number DE-FG02-04ER46136, and by Board of Regents, State of Louisiana under Contract Number No. DOE/LEQSF(2004-07)-ULL and LEQSF(2003-06)-RD-A-37. Part of this work was presented in the student poster session of IEEE International Conference on Network Protocols (ICNP) 2003, Atlanta, GA.Hongyi Wu is currently a tenure-track Assistant Professor in the Center for Advanced Computer Studies (CACS), University of Louisiana (UL) at Lafayette. He received his Ph.D. degree in computer science and M.S. degree in electrical engineering from State University of New York (SUNY) at Buffalo in 2002 and 2000, respectively. He received his B.S. degree in scientific instruments from Zhejiang University in 1996. His research interests include wireless mobile ad hoc networks, wireless sensor networks, next generation cellular systems, and integrated heterogeneous wireless systems. He has served as symposium chair, session chair, and technical committee member of several IEEE conferences, and a guest editor of ACM MONET special issue on Integration of Heterogeneous Wireless Technologies. He has published more than two dozens of technical papers in leading journals and conference proceedings.Anant P. Utgikar (S’03) graduated with B.Tech. in Electrical Engineering from IIT—Bombay in 2001. He received M.S. in Computer Engineering from Univ. of Louisiana at Lafayette (UL Lafayette) in 2003. Presently he is working towards Ph.D. at UL Lafayette. His research interests include computer networking, logic design, software, simulation, mobile computing and distributed systems. His contributions to network simulator NS2 were ranked in top-5 of over 240,000 pages by Google. He has won many programming competitions, IEEE, IEE technical paper presentation contests as undergraduate and High School Science-Math Olympiads in India. He was honored by Govt. of India for outstanding performance at national level in XII-th. He has authored a book chapter on Reservation Based MAC protocols. He has published in IEEE ICNP’03, IEEE SiPS’03 and IEEE CAMP’03. He was invited with travel grant to NS2 workshop’02 at USC/ISI, ICNP’03 and SiPS’03. He has been in organizing team of IEEE CAMP 2003 and CyberSecurity Workshop 2003. He has served as Reviewer for IEEE-VTC and ACM-MONET. He has held positions of Student Government Senator and Secretary, Graduate Students Organization at UL Lafayette. He has contributed as volunteer to National Science-Technology-Math ESTME Week organised by NSF and DoE, USA.Nian-Feng Tzeng received the Ph.D. degree in Computer Science from the University of Illinois at Urbana-Champaign. Since 1987, he has been with Center for Advanced Computer Studies, the University of Louisiana at Lafayette, where he is currently a professor. His current research interest is in the areas of computer communications and networks, high-performance computer systems, parallel and distributed processing and fault-tolerant computing. He was on the editorial board of the IEEE Transactions on Parallel and Distributed Systems, 1998–2001, and on the editorial board of the IEEE Transactions on Computers, 1994–1998. He served as a Distinguished Visitor of the IEEE Computer Society, 1994–1997, and was the Chair of Technical Committee on Distributed Processing, the IEEE Computer Society, from 1999 till 2002. He has been on the technical program committees of various conferences and will serve as the Technical Program Chair of the 10th International Conference on Parallel and Distributed Systems, July 2004.Dr. Tzeng is the recipient of the outstanding paper award of the 10th International Conference on Distributed Computing Systems, May 1990. He received the University Foundation Distinguished Professor Award in 1997.     

无线Ad Hoc 网的公平性问题

目前的Ad hoe网中，为了解决隐蔽站问题提出了许多方法，IEEE 802.11 DCF MAC协议作为一种在无线Ad hoe网中被建议使用的标准，受到人们的关注。在IEEE 802．11 DCF中通过使用RTS／CTS握手，以及ACK确认帧，减轻了隐蔽站的影响，但它将导致“捕获”效应，即一些站占有共享信道，而其他站得不到信道，这也叫“公平性”问题。这篇文章叙述了一些有关“公平性”的解决办法，并通过仿真，说明改变IEEE 802．11中的退避算法，可提高Ad hoe网的公平性。     

An Integrated Medium Access Control and Traffic Management Architecture for DVB-RCS SkyplexNet Satellite Systems

The growing development of standard Internet services and the emerging exploitation of several broadband multimedia contents disclosing in the last years, significantly promoted scenarios where Satellite Networks can play key roles. Several satellite networks are currently implemented according to the Digital Video Broadcasting-Return Channel via Satellite (DVB-RCS) standard, assuming to operate with a transparent satellite and an hub-centric (star) network topology. The present work addresses the SkyplexNet (SKN) system: an advanced Broadband Satellite Network for meshed connectivity developed by Alenia Spazio, within the framework of ESA Artes 3 – Line 1 Program, according to the DVB-RCS standard with duly extensions for the on-Board multiplexing capability of the Skyplex Units currently embarked on HotBird VI and W3A satellites. In this paper an architecture design study aiming at integrating the Medium Access Control (MAC) and Traffic Management (TM) functionality in a DVB-RCS like Network is presented. The envisaged Traffic Management schemes shall enable the SKN System to guarantee an adequate support of various Quality of Service (QoS) requirements and their application according to pre-defined Traffic Profiles established at connection set up phase with the support of physical medium access management functions. The functional architectures studied for the SKN Inter-Working Layer, from Internet protocols to SkyplexNet ones, and the SKN MAC layer have been also analysed on the interoperability level of these layers in order to deploy such functions as SKN connection mapping, packet scheduling and Bandwidth on Demand (BoD) policies. In this paper two different schemes of Traffic Management and MAC are presented reporting a detailed analysis of advantages and drawbacks of both approaches to be taken into account for future SkyplexNet system implementations. Fabrizio Di Cola is a Network and System Engineer of the Telecommunication Mission Unit of Alenia Spazio company (Italy). He received the M.S. degree in Telecommunication Engineering from University of Rome “La Sapienza” in 1998 and he is in Alenia Spazio since 2000. He is currently involved in the design and deployment of the Ground Segment of EuroSkyWay and SkyplexNet satellite systems as responsible for the Satellite User terminals Design and Development. He also contributes to System Engineering in the framework of several ESA and EC projects. From 1999 up to 2000, he worked as Researcher in the University of Bradford (Bradford, UK), Telecommunication Research Centre, within the “Satellite Mobile Group”. His activity focused on several aspects of the Mobility Management within telecommunications network integrating satellite and terrestrial networks. Emiliano Micaloni was born in Rome, Italy, in 1977. He is a Junior Telecommunication System Engineer involved since 2003 in a collaboration between University of Rome “La Sapienza” and the TLC Mission Unit of Alenia Spazio company (Italy). He received his Master Degree in Electronic Engineering from the University of Rome “La Sapienza”, Italy, in 2002, defending a thesis on Connection and Congestion Control for Geostationary Satellite Networks. Currently his area of interest concerns the Medium Access Control in the SkyplexNet Satellite Network, also contributing at the development activities for the SkyplexNet Satellite Terminals. In 2002–03 he collaborated with the “Computer Science and Systems” Department of “La Sapienza“ implementing solutions for Traffic Management and Quality of Service in Satellite Networks. All his activities are carried out in the framework of different ESA and EU IST projects. Luigi Secondiani received his M.S. degree in Telecommunication Engineering from University of Rome “La Sapienza” in 1997. From 1998 to 1999 he received a post-degree grant issued by the “Infocom” Department of the University of Rome “La Sapienza” in the frame of the ACTS 4th framework programme. Since December 1999 he works as a Network Engineer in Alenia Spazio-TLC Mission Unit, and he is currently involved in Alenia's activities on EC, ESA and NATO programmes. His main research interests mainly lie on interworking between Next Generation Satellite Systems (NGSS) and IP networks, with particular emphasis on network architectures, terminal's architectures and routing issues. Giuseppe Tomasicchio is a Senior Telecommunication System Engineer of the TLC Mission Unit of Alenia Spazio company (Italy). He received his degree in 1989 from University of Bari (Italy) in the Artificial Intelligence field. He received a Post-degree Diploma on Technologies of Educational Communication in 1991 and a Post-degree Engineering Specialisation Diploma in Signal Processing in 1994 from University of Bari. Currently he is responsible of the Ground System Design of EuroSkyWay/SkyplexNet satellite systems and of the Network Operations and Service Centres engineering in satellite networks devoted to multimedia applications in the framework of different ESA and EC projects. In 1997–98 he was responsible at CERN (Geneva, Switzerland) of the Data Acquisition System involving the readout, calibration, event display and the networking setup tasks of high energy physics experiments. From 1994 to 1998 he was at INFN (Italian Institute for Nuclear Physics) as researcher. In 1994 he was an IS-specialist in the Italian Government data processing centre and collaborated with the Government Seismic Service for GIS processing. He worked in 1991–92 as a fellow of DIGITAL Corporation for a join research activity at INFN in the field of Image processing and Pattern recognition applied to raw-data images produced from detectors in high energy physics experiments at CERN. He is author of several scientific and engineering papers.     

A Medium Access Control Protocol for Voice/Data Integrated Wireless CDMA Systems

In this paper, a medium access control protocol is proposed for integrated voice and data services in wireless local networks. Uplink channels for the proposed protocol are composed of time slots with multiple spreading codes per slot based on slotted code division multiple access (CDMA) systems. The proposed protocol uses spreading code sensing and reservation schemes. This protocol gives higher access priority to delay‐sensitive voice traffic than to data traffic. The voice terminal reserves an available spreading code to transmit multiple voice packets during a talkspurt. On the other hand, the data terminal transmits a packet without making a reservation over one of the available spreading codes that are not used by voice terminals. In this protocol, voice packets do not come into collision with data packets. The numerical results show that this protocol can increase the system capacity for voice service by applying the reservation scheme. The performance for data traffic will decrease in the case of high voice traffic load because of its low access priority. But it shows that the data traffic performance can be increased in proportion to the number of spreading codes.