Voice/Data Integrated Wireless Channel Access in Third Generation Digital Cellular Networks: The Performance of Bursty Data Generated by Interactive Applications

Mobile wireless communications, which includecellular telephones, land mobile radio, and personalcommunications systems, have experienced enormous growthover the last decade. Data services represent a critical component of future wirelesscommunications, but have received little attention sofar. While some attention has been given to specializedmobile data networks, less has been directed at the ongoing design of data services in evolvingthird generation digital cellular wireless networks. Inthis work we present the results of a simulation studythat explores the performance of a Reservation Random Access (RRA) scheme for transmittingdata packets over a common radio broadcast channel in acellular radio environment. In addition to voicetraffic, we consider data packet traffic generated by interactive applications. It is expected thatsuch applications will be very important in thirdgeneration wireless access mobile communication systems.Through an extensive simulation study of the data message delay distribution, we show that theproposed RRA scheme, originally designed under thePoisson data message arrival process assumption, canalso efficiently operate and be optimized under theextremely bursty data message arrival processcharacterized by independent, identically distributed,Pareto message interarrival times.     

A Time Reuse Capture Access (TRCA) Protocol for PCS and Wireless ATM Applications

The Time Reuse Capture Access (TRCA) protocol isa medium access control protocol appropriate forpersonal communications and wireless AsynchronousTransfer Mode (ATM) applications. It is based on time reuse rather than frequency reuse. Frequencychannels are reused in every cell (frequency reuse one).Each FDMA channel has a TDMA frame structure. The numberof slots in the frame is equal to the time reuse factor and each slot is assigned to aspecific cell in the reuse cluster. Each mobile usertransmits in its assigned frequency channel and TDMAtime slot which corresponds to the cell it currently belongs. The protocol also exploits the powercapture phenomenon in which simultaneous transmissionsof users in adjacent cells may be successfully received.Two possible applications of the proposed TRCA protocol are considered in this paper. In thefirst application, TRCA is used for random packet accessin wireless personal communication. Users transmit theirpackets using the assigned and non-assigned time slots to take advantage of the effect ofcapture and non-uniform traffic loads. The portion oftransmissions that takes place in each time slot iscontrolled so that the overall throughput is maximized. In the second application, TRCA is used forreliable transmission of ATM cell over a wirelesschannel. The proposed protocol allows the transmissionof continuous bit rate (CBR) ATM cells over a wireless link so that bit error rate (BER) and delayrequirements are met. Transmissions take place in theassigned time slots but the non-assigned time slots canbe used for re-transmission if the previous transmission was unsuccessful.     

A Bandwidth Reservation Multiple Access Protocol for Wireless ATM Local Networks

A bandwidth reservation multiple access scheme(BRMA) is proposed to resolve contention and assignbandwidth among multiple users trying to gain access toa common channel such as in mobile users contending for resources in an ATM-based cellular networkor a wireless local area network (LAN) with shortpropagation delays. The protocol is best suited tosupport variable-bit-rate (VBR) traffic that exhibits high temporal fluctuations. Each mobile user isconnected end-to-end to another user over virtualchannels via the base station that is connected to thewired ATM B-ISDN network. The channel capacity is modeled as a time frame with a fixed duration.Each frame starts with minislots, to resolve contentionand reserve bandwidth, followed by data-transmissionslots. Every contending user places a request for data slots in one of the minislots. If therequest is granted by the base station through adownlink broadcast channel, the user then startstransmission in the assigned slot(s). The number ofassigned slots varies according to the required qualityof service (QoS), such as delay and packet lossprobability. A speech activity detector is utilized inorder to indicate the talkspurts to avoid wastingbandwidth. Due to its asynchronous nature, BRMA is ratherinsensitive to the burstiness of the traffic. Since theassignment of the minislots is deterministic, therequest channels are contention-free and the data channels are collision-free. Hence, in spite ofthe overhead (minislots) in each frame, BRMA provideshigher throughput than Packet Reservation MultipleAccess (PRMA) for the same QoS, especially for high-speed systems. A better delay performance is alsoachieved for data traffic compared to Slotted Alohareservation-type protocol PRMA. In addition, BRMAperforms better in terms of bandwidth efficiency thanthe conventional TDMA or the Dynamic TDMA, wherespeech activity detectors are very difficult toimplement.     

Group Based Common-Receiver/DS CDMA Wireless Networks And (GBCR) Code Protocol for Its Performance Study

A spreading code protocol (GBCR protocol)suitable for DS CDMA wireless data networks is proposedin this paper. The network is co-ordinated by a centralstation (CS) which maintains a database tracking each user's status. Users are divided intogroups, each of which is assigned a group-basedcommon (GBC) code used by a transmitter in thegroup to acquire the current state of its target. Data communication is allowed only after apositive ACK packet from the CS is received by thetransmitter, so that all successful terminals aresheltered by the CS from possible third-partyinterference which may use the same receiver-based code.Analytical results reveal that the GBCR protocol caneffectively improve network stability andthroughput-delay performance.     

Performance Evaluation of a Logical Link Control Protocol for an ATM Air Interface

The paper deals with error control proceduresbased on repetitions necessary for an ATM air interface,which enables a full integration of wireless (W) ATMterminals into a fixed ATM network. The architecture and functionality of an additional LLC layer atthe air interface are explained. A set of ARQ protocolsfor the different ATM service classes is investigated.The protocol for VBR services is able to control the number of retransmissions depending on therequirements on maximum delay and residual cell lossratio. It also takes into account instantaneousconditions such as channel load from other sources.Furthermore, the protocol is able to discard ATM cells toavoid and resolve congestion. The performance of theprotocol has been evaluated by simulations.     

A Novel Multiaccess Strategy for Multimedia Wireless LANs

The main focus of the research presented in thispaper is to evaluate how efficiently a commoncommunication medium such as broadcast radio can beshared by a large number of network devices in anin-building environment. The goal is to recommend anoptimal method to fulfil the demanding requirementsdictated by broadband multimedia applications operatingin wireless local area networks. To this end, apractical and efficient multiaccess scheme calledreserved polling is proposed and analyzed.It is shown that the new method is able to handle anintegrated mix of multimedia traffic and operaterobustly in an unreliable wireless transport medium. Ananalytical approach based on queueing theory is employedto gain some insight into the complex behavior of theprotocol. This approach appears to be accurate in predicting its performance for both bursty andperiodic traffic types. The analytical results areverified by network simulation.     

支持话音/数据分组并传的UPMA多址接入协议

本文提出了一种新的、支持数据/话音业务并传的多址接入协议——根据用户数目妥善安排分组传输的多址接入(User-dependent Perfect-scheduling Multiple Access——UPMA)协议,它根据实际需求对上、下行带宽资源实行动态分配.UPMA协议对不同的业务类型赋予不同的优先级,并用轮询方式妥善地安排节点的分组传输;同时,它采用独特的帧结构,使话音业务总是能够得到优先传输.本文还提出了一种高效的竞争接入算法,以保证激活的节点能够快速接入信道.最后,对UPMA协议的性能进行了仿真并与MPRMA协议的性能进行了比较,结果证明UPMA协议有更好的性能.     

一种适用于IBSS网络的无线接入认证协议

针对目前无线局域网接入认证协议WAPI与RSNA在IBSS模式下运行复杂及密钥管理协议存在DoS攻击等问题,该文采用实体认证角色的自适应选择策略,对密钥管理协议进行改进,提出了一种安全性更强、执行效率更高的适用于IBSS网络的无线接入认证协议,并利用CK模型对其进行了分析。分析结果表明：在密钥加密算法是CCA安全及密钥导出算法是伪随机的前提下,协议在UM下是SK-secure的。最后,以WAPI协议为例,给出新协议与原始协议的性能对比。     

A Relay-Aided Media Access (RAMA) Protocol in Multirate Wireless Networks

The IEEE 802.11 standard inherently supports multiple data rates at the physical layer. Various rate adaptation mechanisms have been proposed to exploit this multirate capability by automatically adapting the transmission rate to best utilize the wireless spectrum. This study is primarily motivated by the observation that in a wireless network, a multihop high-rate path can potentially achieve better throughput and delay than using a single-hop low-rate path for transmission. Specifically, this paper introduces a relay-aided media access (RAMA) protocol by taking advantage of the existence of such multihop high-rate links. This is demonstrated by replacing one low-rate link with two high-rate links using a relay node. One of the key novelties in the proposed RAMA protocol is that the transmission from the immediate relay node to the destination node is free of contention. Results from analysis and simulations show that RAMA can significantly improve performances in terms of both throughput and delay.     

无线网络中中继协助的媒体接入协议

IEEE 802.11在物理层支持多速率.目前已提出许多机制通过自动调整速率充分利用多速率能力.本文观察到在无线网络中,相对于单跳的低速率链路,多跳高速率的路径可以减少信道占用时间,并提出了中继协助的媒体接入协议(Relay Aided Media Access,RAMA).RAMA利用中继节点将一跳低速链路拆为两跳高速链路.大量仿真结果表明,RAMA能够提供更好的吞吐量和时延性能.     

一种无线传感器网络的访问控制协议

传感器网络中的节点存在由于能量耗尽或恶意攻击而丧失作用的威胁,因此需要新节点的加入.利用Bloom Filter技术,提出了一种访问控制协议.本协议不仅便于实现新节点、旧节点的双向认证和密钥协商,而且便于实现节点的加入与撤消.通过性能分析和安全性分析说明了该协议的有效性.     

一种并行传输的水声Ad hoc网络多址接入(PTMA)协议

由于存在"隐藏终端"和"暴露终端"的问题,无线Ad hoc网络的应用受到极大的限制.进一步,由于水声信道的特点,例如有用的频率带宽很窄,强时变、多途和长传播时延,使得设计水声Ad hoc网络具有自身特点和难度.本文中,我们为此提出了一种新的多址接入控制(MAC)协议,即并行传输多址接入(PTMA)协议.该协议基于如下思想:为消除冲突而进行多信道预约,这样能在多个信道上并行地传输数据;为缩短等待clear_-to_-send(CTS)的时间,当request_-to_-send(RTS)刚发送完就立即发送分组数据,而不必收到CTS后再发.通过使用OPNET Modeler/Radio仿真器得到的仿真结果显示:PTMA协议能取得较之于适合无线Ad hoc网络的多址接入协议更高的吞吐性能和较低的端到端传播时延.     

Dynamic Code Assignment Medium Access (DCAMA) Protocol for Wireless Integrated Services Networks

A medium access control (MAC) protocol for wireless mobile networks that supports integrated services and provides quality of service (QoS) support is presented and evaluated via simulation. A controlled random access protocol which allows all terminals to dynamically share a group of spread spectrum spreading codes is used. The protocol provides mobile terminals the access control required for efficient transfer of integrated traffic with QoS guarantees. Two service classes are provided; "best-effort" service, with priority queueing, and reserved bandwidth circuit service. The performance of the protocol is evaluated via simulation for traffic consisting of integrated voice, data and compressed video. The performance assessment measure is packet delay.     

无线数字家庭网络泛在接入技术

数字家庭网络是通信领域的一个重要分支，近年来发展非常迅速。基于电信网络的数字家庭网络体系结构在中国已经标准化，但就接入方式而言，只是定义了可以使用无线方式，如何组建无线数字家庭网络是未来研究的重点。文章提出了无线数字家庭网络泛在接入概念，给出了无线泛在接入网络体系结构，并就其中的关键技术进行了探讨，包括感知无线电、无线网状网（Mesh）网络理论、通用接入点链路转换机制、业务的QoS保障机制以及电磁兼容和异构系统共存机制等。     

移动Ad Hoc网络中一种分布式QoS保证的多址接入协议

基于随机竞争和冲突解决的思想,本文为多跳移动Ad Hoc网络提出了一种分布式服务质量(QoS)保证的多址接入(QMA)协议.该协议中,节点在发送业务分组前利用预报突发进行竞争接入,节点根据业务分组时延情况和最早失效优先原则确定预报突发的长度,所发预报突发能持续到最后的节点优先获得接入.同时,具有实时业务的节点可以按照其优先级在更早的竞争微时隙中开始发送预报突发,而有非实时业务的节点只能在前面竞争微时隙空闲的情况下,才能在后面的微时隙开始发送预报突发,因此发送实时业务的节点可以比发送非实时业务的节点更优先接入信道,从而在移动Ad Hoc网络中实现了对多媒体业务的QoS保证.最后利用OPNET仿真评估了QMA协议的多址性能,并与IEEE 802.11e协议的性能做了比较,结果表明QMA协议可以提供较高的吞吐量和较低的实时业务时延.     

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.     

A Random Access Protocol with Multi-Packet Reception for Infrastructure-Less Wireless Autonomic Networks

A random access protocol with multi-packet reception (MPR) capability for infrastructure-less wireless autonomic networks is introduced and analyzed. In these networks mobile nodes may communicate with each other directly without a central entity (base station), where each mobile node either will be in a transmitting mode or in a receiving mode or in an idle mode. The throughput per node and the packet retransmission probability depend exclusively on the MPR capability and the ratio of the transmission probability and the receiving probability of each mobile node. For a given ratio of the transmission probability and the receiving probability of each mobile node, throughput-delay performance increases with the increase of MPR capability. In the proposed infrastructure-less networks, mobile nodes can control the network traffic very precisely by controlling the three parameters. These three parameters are transmission probability, receiving probability and idle mode probability of each mobile node. Since each mobile node can control the network traffic very precisely to obtain the maximum throughput, the network is autonomic, i.e., self-optimizing. The optimum transmission probability of each mobile node to obtain the maximum throughput is evaluated. The throughput utility increases with the increase of MPR capability. On the other hand, the cost per mobile node also increases with the increase of MPR capability. Therefore the MPR capability should be optimized to provide reasonable trade-off between the throughput per node and the cost per mobile node. The results of this study may be used for a system design of an infrastructure-less contention-based multiple access schemes with MPR capability.     

A New Transport Protocol for Broadcasting/Multicasting MPEG-2 Video Over Wireless ATM Access Networks

Because of the telecommunications de-regulation act and progress in wireless technologies, we will see the co-existence of heterogeneous broadband access infrastructures in the broadband video service industry in the near future. In this paper, we addressed the error control issue when transmitting MPEG-2 video streams over wireless access networks for broadband video broadcast or multicast services. An end-to-end transport protocol based on ATM and wireless ATM technologies is proposed. For video services, the underlying transport network should be transparent and quality should be maintained uniformly over all the segments whether wireline or wireless links. For network resources to be used efficiently, error control should be applied locally on the wireless segments so as to avoid the excessive overhead over the reliable wireline portions. Because a broadband video broadcast or multicast service is a one-to-multiple point service, FEC is the most prevalent error control mechanism. Due to the important role of MPEG-2 control information in the decoding process, priority MPEG-2 control information has to be differentiated from MPEG-2 data information, and excess error protection has to be allocated to it in order to achieve satisfactory QoS. Therefore, a header redundancy FEC (HRFEC) scheme for error control is applied at the local distribution centers before the MPEG-2 encoded video streams are transmitted over the wireless channels. HRFEC is an FEC-based selective protection scheme, which allocates extra error protection to important control information. Simulation results show that the quality of the reconstructed video sequence is vastly improved by using HRFEC, when the channel condition is poor.     

无线供电混合多址接入网络的资源分配

无线供电技术是延长无线网络节点寿命的有效方案。该文研究一个由基站和多个分簇用户组成的无线供电混合多址接入系统。系统的传输分为两个阶段。在第1阶段,基站向用户广播能量;在第2阶段,用户向基站传输信息。用户簇和用户簇之间采用时分多址接入,分时传输;同一簇内多个用户采用非正交多址接入,同时传输。该文研究联合优化系统的各阶段的传输时间、基站的发射功率、用户的发射功率等资源,分别以优化网络频谱效率和用户簇之间的公平性为目的,提出最大化网络吞吐量和最大化用户簇的最小吞吐量的联合资源分配算法。研究结果表明所提的两种算法分别能有效提高系统的频谱效率和保证用户簇之间的公平性。     

rDCF: A Relay-Enabled Medium Access Control Protocol for Wireless Ad Hoc Networks

It is well known that IEEE 802.11 provides a physical layer multirate capability and, hence, MAC layer mechanisms are needed to exploit this capability. Several solutions have been proposed to achieve this goal. However, these solutions only consider how to exploit good channel quality for the direct link between the sender and the receiver. Since IEEE 802.11 supports multiple transmission rates in response to different channel conditions, data packets may be delivered faster through a relay node than through the direct link if the direct link has low quality and low rate. In this paper, we propose a novel MAC layer relay-enabled distributed coordination function (DCF) protocol, called rDCF, to further exploit the physical layer multirate capability. We design a protocol to assist the sender, the relay node, and the receiver to reach an agreement on which data rate to use and whether to transmit the data through a relay node. Considering various issues, such as, bandwidth utilization, channel errors, and security, we propose techniques to further improve the performance of rDCF. Simulation results show that rDCF can significantly reduce the packet delay, improve the system throughput, and alleviate the impact of channel errors on fairness.