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Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com THE HANDBOOK OF AD HOC WIRELESS NETWORKS
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com THE HANDBOOK OF AD HOC WIRELESS NETWORKS Edited by Mohammad Ilyas Florida Atlantic University Boca Raton, Florida C RC PR E S S Boca Raton London New York Washington, D.C.
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com The Electrical Engineering Handbook Series Series Editor Richard C. Dorf University of California, Davis Titles Included in the Series The Handbook of Ad Hoc Wireless Networks, Mohammad Ilyas The Avionics Handbook, Cary R. Spitzer The Biomedical Engineering Handbook, 2nd Edition, Joseph D. Bronzino The Circuits and Filters Handbook, Second Edition, Wai-Kai Chen The Communications Handbook, 2nd Edition, Jerry Gibson The Computer Engineering Handbook, Vojin G. Oklobdzija The Control Handbook, William S. Levine The Digital Signal Processing Handbook, Vijay K. Madisetti & Douglas Williams The Electrical Engineering Handbook, 2nd Edition, Richard C. Dorf The Electric Power Engineering Handbook, Leo L. Grigsby The Electronics Handbook, Jerry C. Whitaker The Engineering Handbook, Richard C. Dorf The Handbook of Formulas and Tables for Signal Processing, Alexander D. Poularikas The Handbook of Nanoscience, Engineering, and Technology, William A. Goddard, III, Donald W. Brenner, Sergey E. Lyshevski, and Gerald J. Iafrate The Industrial Electronics Handbook, J. David Irwin The Measurement, Instrumentation, and Sensors Handbook, John G. Webster The Mechanical Systems Design Handbook, Osita D.I. Nwokah and Yidirim Hurmuzlu The Mechatronics Handbook, Robert H. Bishop The Mobile Communications Handbook, 2nd Edition, Jerry D. Gibson The Ocean Engineering Handbook, Ferial El-Hawary The RF and Microwave Handbook, Mike Golio The Technology Management Handbook, Richard C. Dorf The Transforms and Applications Handbook, 2nd Edition, Alexander D. Poularikas The VLSI Handbook, Wai-Kai Chen Forthcoming Titles The CRC Handbook of Engineering Tables, Richard C. Dorf The Engineering Handbook, Second Edition, Richard C. Dorf The Handbook of Optical Communication Networks, Mohammad Ilyas and Hussein T. Mouftah © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Library of Congress Cataloging-in-Publication Data The handbook of ad hoc wireless networks / edited by Mohammad Ilyas. p. cm. -- (The electrical engineering handbook series) Includes bibliographical references and index. ISBN 0-8493-1332-5 (alk. paper) 1. Wireless LANs. I. Ilyas, Mohammad, 1953- II. Series TK5105.78 .H36 2002 621.382--dc21 2002031316 This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the authors and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microﬁlming, and recording, or by any information storage or retrieval system, without prior permission in writing from the publisher. All rights reserved. Authorization to photocopy items for internal or personal use, or the personal or internal use of speciﬁc clients, may be granted by CRC Press LLC, provided that $1.50 per page photocopied is paid directly to Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923 USA The fee code for users of the Transactional Reporting Service is ISBN 0-8493-1332-5/03/$0.00+$1.50. The fee is subject to change without notice. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. The consent of CRC Press LLC does not extend to copying for general distribution, for promotion, for creating new works, or for resale. Speciﬁc permission must be obtained in writing from CRC Press LLC for such copying. Direct all inquiries to CRC Press LLC, 2000 N.W. Corporate Blvd., Boca Raton, Florida 33431. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identiﬁcation and explanation, without intent to infringe. Visit the CRC Press Web site at www.crcpress.com © 2003 by CRC Press LLC No claim to original U.S. Government works International Standard Book Number 0-8493-1332-5 Library of Congress Card Number 2002031316 Printed in the United States of America 1 2 3 4 5 6 7 8 9 0 Printed on acid-free paper © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Preface To meet the need for fast and reliable information exchange, communication networks have become an integral part of our society. The success of any corporation largely depends upon its ability to commu- nicate. Ad hoc wireless networks will enhance communication capability signiﬁcantly by providing connectivity from anywhere at any time. This handbook deals with wireless communication networks that are mobile and do not need any infrastructure. Users can establish an ad hoc wireless network on a temporary basis. When the need disappears, so will the network. As the ﬁeld of communications networks continues to evolve, a need for wireless connectivity and mobile communication is rapidly emerging. In general, wireless communication networks provide wire- less (and hence) mobile access to an existing communication network with a well-deﬁned infrastructure. Ad hoc wireless networks provide mobile communication capability to satisfy a need of a temporary nature and without the existence of any well-deﬁned infrastructure. In ad hoc wireless networks, com- munication devices establish a network on demand for a speciﬁc duration of time. Such networks have many potential applications including the following: • Disaster recovery situations • Defense applications (army, navy, air force) • Healthcare • Academic institutions • Corporate conventions/meetings This handbook has been prepared to ﬁll the need for comprehensive reference material on ad hoc wireless networks. The material presented in this handbook is intended for professionals who are design- ers and/or planners for emerging telecommunication networks, researchers (faculty members and grad- uate students), and those who would like to learn about this ﬁeld. The handbook is expected to serve as a source of comprehensive reference material on ad hoc wireless networks. It is organized in the following nine parts: • Introduction • Wireless transmission techniques • Wireless communication systems and protocols • Routing techniques in ad hoc wireless networks — part I • Routing techniques in ad hoc wireless networks — part II • Applications of ad hoc wireless networks • Power management in ad hoc wireless networks • Connection and trafﬁc management in ad hoc wireless networks • Security and privacy aspects of ad hoc wireless networks © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com The handbook has the following speciﬁc salient features: • It serves as a single comprehensive source of information and as reference material on ad hoc wireless networks. • It deals with an important and timely topic of emerging communication technology of tomorrow. • It presents accurate, up-to-date information on a broad range of topics related to ad hoc wireless networks. • It presents material authored by experts in the ﬁeld. • It presents the information in an organized and well-structured manner. Although the handbook is not precisely a textbook, it can certainly be used as a textbook for graduate courses and research-oriented courses that deal with ad hoc wireless networks. Any comments from readers will be highly appreciated. Many people have contributed to this handbook in their unique ways. The ﬁrst and foremost group that deserves immense gratitude is the group of highly talented and skilled researchers who have con- tributed 32 chapters. All of them have been extremely cooperative and professional. It has also been a pleasure to work with Nora Konopka, Helena Redshaw, and Susan Fox of CRC Press, and I am extremely grateful for their support and professionalism. My wife Parveen and my four children Saﬁa, Omar, Zakia, and Maha have extended their unconditional love and strong support throughout this project, and they all deserve very special thanks. Mohammad Ilyas Boca Raton, Florida © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com The Editor Mohammad Ilyas is a professor of computer science and engineering at Florida Atlantic University, Boca Raton, Florida. He received his B.Sc. degree in electrical engineering from the University of Engineering and Technology, Lahore, Pakistan, in 1976. In 1978, he was awarded a scholarship for his graduate studies, and he completed his M.S. degree in electrical and electronic engineering in June 1980 at Shiraz University, Shiraz, Iran. In September 1980, he joined the doctoral program at Queen’s University in Kingston, Ontario. He completed his Ph.D. degree in 1983. His doctoral research was about switching and ﬂow control techniques in computer communication networks. Since September 1983, he has been with the College of Engineering at Florida Atlantic University. From 1994 to 2000, he was chair of the Department of Computer Science and Engineering. During the 1993–94 academic year, he spent a sabbatical leave with the Department of Computer Engineering, King Saud University, Riyadh, Saudi Arabia. Dr. Ilyas has conducted successful research in various areas including trafﬁc management and con- gestion control in broadband/high-speed communication networks, trafﬁc characterization, wireless communication networks, performance modeling, and simulation. He has published one book and more than 120 research articles. He has supervised several Ph.D. dissertations and M.S. theses to completion. He has been a consultant to several national and international organizations. Dr. Ilyas is an active participant in several IEEE technical committees and activities and is a senior member of IEEE. © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com List of Contributors José Ferreira de Pei-Kai Hung George N. Aggélou Institute of Technology Rezende National Central University Athens, Greece Chung-Li, Taiwan Federal University of Rio de Janeiro Rio de Janeiro, Brazil Roberto Baldoni Aditya Karnik Universita’ di Roma, “La Sapienza” Nelson Fonseca Indian Institute of Science Roma, Italy Bangalore, India State University of Campinas Campinas, Brazil Roberto Beraldi Won-Ik Kim Universita’ di Roma, “La Sapienza” Holger Füßler ETRI Roma, Italy Taejon, South Korea University of Mannheim Mannheim, Germany Ezio Biglieri Anurag Kumar Politecnico di Torino Silvia Giordano Indian Institute of Science Torino, Italy Bangalore, India LCA-IC-EPFL Lausanne, Switzerland Satyabrata Chakrabarti Dong-Hee Kwon Sylvaine Algorithmics Zygmunt J. Haas POSTECH Aurora, Illinois Pohang, South Korea Cornell University Ithaca, New York Chaou-Tang Chang Chiew-Tong Lau National Chiao Tung University Hannes Hartenstein Nanyang Technological University Hsinchu, Taiwan Singapore, Singapore NEC Europe Ltd. Heidelberg, Germany Chih Min Chao Ben Lee National Central University Xiao Hannan Oregon State University Chung-Li, Taiwan Corvallis, Oregon National University of Singapore Singapore, Singapore Xiao Chen Bu-Sung Lee Southwest Texas State University Hossam S. Hassanein Nanyang Technological University San Marcos, Texas Singapore, Singapore Queen's University Kingston, Ontario, Canada Chua Kee Chaing Bo Li National University of Singapore Chih-Shun Hsu Hong Kong University of Science Singapore, Singapore and Technology National Central University Kowloon, Hong Kong Chung-Li, Taiwan Marco Conti Michele Lima Consiglio Nazionale delle Ricerche Cheng-Ta Hu Pisa, Italy State University of Parana West National Central University Cascavel, Brazil Chung-Li, Taiwan © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Ting-Yu Lin Matthew Sadiku Lei Wang National Chiao-Tung University Prairie View A&M University Tianjin University Hsinchu, Taiwan Prairie View, Texas Tianjin, People’s Republic of China Jiang Chuan Liu Ahmed M. Safwat Jörg Widmer Hong Kong University of Science Queen's University University of Mannheim and Technology Kingston, Ontario, Canada Mannheim, Germany Kowloon, Hong Kong Prince Samar Seah Khoon Guan Pascal Lorenz Winston Cornell University Universtiy of Haute Alsace Ithaca, New York National University of Singapore Colmar, France Singapore, Singapore Boon-Chong Seet Martin Mauve Jie Wu Nanyang Technological University University of Mannheim Singapore, Singapore Florida Atlantic University Mannheim, Germany Boca Raton, Florida Jang-Ping Sheu Amitabh Mishra Oliver Yang National Central University Virginia Polytechnic Institute and Chung-Li, Taiwan University of Ottawa State University Ottawa, Ontario, Canada Blacksburg, Virginia Yantai Shu Sal Yazbeck Tianjin University Sangman Moh Tianjin, People’s Republic of China Barry University ETRI Palm Beach Gardens, Florida Taejon, South Korea Kazem Sohraby Hee Yong Youn Lucent Technologies Hussein T. Mouftah Lincroft, New Jersey Sungkyunkwan University Queen's University Jangangu Chunchundong, South Kingston, Ontario, Canada Ivan Stojmenovic Korea University of Ottawa Ketan M. Nadkarni Chansu Yu Ottawa, Ontario, Canada Virginia Polytechnic Institute and Cleveland State University State University Young-Joo Suh Cleveland, Ohio Blacksburg, Virginia POSTECH Qian Zhang Pohang, South Korea Panagiotis Microsoft Research Papadimitratos Yu-Chee Tseng Beijing, People’s Republic of China Cornell University National Chiao-Tung University Ithaca, New York Dan Zhou Hsinchu, Taiwan Florida Atlantic University Marc R. Pearlman Kuochen Wang Boca Raton, Florida Cornell University National Chiao Tung University Ithaca, New York Wenwu Zhu Hsinchu, Taiwan Microsoft Research Beijing, People’s Republic of China © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Table of Contents 1 B o dy, Personal, and Local Ad Hoc Wireless Networks Ma rco Conti 2 Mu lticasting Techniques in Mobile Ad Hoc Networks Xi ao Chen a nd Jie Wu 3 Q ualit y o f Service in Mobile Ad Hoc Networks S at y abrata Chakrabarti and Amitabh Mishra 4 Power-Conservative Designs in Ad Hoc Wireless Networks Yu -Chee Tseng a nd Ting-Yu Lin 5 Pe rformance Analysis of Wireless Ad Hoc Networks An urag Kumar a nd Aditya Karnik 6 C o ding for the Wireless Channel E zio Big l ieri 7 Un icast Routing Techniques for Mobile Ad Hoc Networks Ro berto Beraldi a nd Roberto Baldoni 8 S a tellite Communications Matthew N.O. Sadiku 9 Wi reless Communication Protocols Pascal Lorenz 10 An Integrated Platform for Ad Hoc GSM Cellular Communications George N. Aggélou 11 I EEE 802.11 and B l uetooth: An Architectural Overview S al Yazbeck 12 Position-Based Routing in Ad Hoc Wireless Networks Jörg Widmer, Martin Mauve, Hannes Hartenstein, and Holger Füßler © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com 13 St r uctured Proactive and Reactive Routing for Wireless Mobile Ad Hoc Networks Ahmed M. Safwat, Hossam S. Hassanein, and Hussein T. Mouftah 14 Hybrid Routing: The Pursuit of an Adaptable and Scalable Routing Framework for Ad Hoc Networks Pr ince Samar, Marc R. Pearlman, and Zygmunt J. Haas 15 Ad aptive Routing in Ad Hoc Networks Ya ntai Shu, O liver Yang, a nd L ei Wang 16 Po sition-Based Ad Hoc Routes in Ad Hoc Networks S i lvia Giordano a nd Ivan Stojmenovic 17 Ro ute Discovery Optimization Techniques in Ad Hoc Networks B o on-Chong Seet, Bu-Sung Lee, a nd Chiew-Tong Lau 18 L o cation-Aware Routing and Applications of Mobile Ad Hoc Networks Yu-Chee Tseng and Chih-Sun Hsu 19 Mobility over Transport Control Protocol/Internet Protocol (TCP/IP) Jo sé Ferreira de Rezende, Michele Mara de Araújo Espíndula Lima, and Nelson Luis Saldanha da Fonseca 20 An Intelligent On-Demand Multicast Routing Protocol in Ad Hoc Networks Kuochen Wang and Chaou-Tang Chang 21 G PS-Based Reliable Routing Algorithms for Ad Hoc Networks Young-Joo Suh, Won-Ik Kim, and D ong-Hee Kwon 22 Power-Aware Wireless Mobile Ad Hoc Networks Ahmed Safwat, Hossam S. Hassanein, and Hussein T. Mouftah 23 E nergy Efﬁcient Multicast in Ad Hoc Networks Hee Yong Youn, Chansu Yu, Ben Lee, and Sangman Moh 24 E nergy-Conserving Grid Routing Protocol in Mobile Ad Hoc Networks Jang-Ping Sheu, Cheng-Ta Hu, and Chih-Min Chao 25 Routing Algorithms for Balanced Energy Consumption in Ad Hoc Networks He e Yong Youn, C hansu Yu, and B en Lee © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com 26 Resource Discovery in Mobile Ad Hoc Networks Ji angchuan Liu, Kazem Sohraby, Q ian Zhang, B o Li, a nd Wenwu Zhu 27 A n Integrated Platform for Quality-of-Service Support in Mobile Multimedia C lustered Ad Hoc Networks Ge orge N. Aggélou 28 Q uality of Service Models for Ad Hoc Wireless Networks Xi ao Hannan, Chua Kee Chaing, a nd Seah Khoon Guan Winston 29 S cheduling of Broadcasts in Multihop Wireless Networks Jang-Ping Sheu, Pei-Kai Hung, and C hih-Shun Hsu 30 S ecurity in Wireless Ad Hoc Networks — A Survey Amitabh Mishra a nd Ketan M. Nadkarni 31 S ecuring Mobile Ad Hoc Networks Panagiotis Papadimitratos a nd Zygmunt J. Haas 32 S ecurity Issues in Ad Hoc Networks D an Zhou © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com 1 Body, Personal, and Local Ad Hoc Wireless Networks Abstract 1.1 Introduction 1.2 Mobile Ad Hoc Networks Body Area Network • Personal Area Network • Wireless Local Area Network 1.3 Technologies for Ad Hoc Networks 1.4 IEEE 802.11 Architecture and Protocols EEE 802.11 DCF • EEE 802.11 RTS/CTS 1.5 A Technology for WBAN and WPAN: Bluetooth A Bluetooth Network • Bluetooth Data Transmission Acknowledgment Marco Conti References Consiglio Nazionale delle Ricerche Abstract A mobile ad hoc network (MANET) represents a system of wireless mobile nodes that can freely and dynamically self-organize into arbitrary and temporary network topologies, allowing people and devices to seamlessly internetwork in areas without any preexisting communication infrastructure. While many challenges remain to be resolved before large scale MANETs can be widely deployed, small-scale mobile ad hoc networks will soon appear. Network cards for single-hop ad hoc wireless networks are already on the market, and these technologies constitute the building blocks to construct small-scale ad hoc networks that extend the range of single-hop wireless technologies to few kilometers. It is therefore important to understand the qualitative and quantitative behavior of single-hop ad hoc wireless networks. The ﬁrst part of this chapter presents the taxonomy of single-hop wireless technologies. Speciﬁcally, we introduce the concept of Body, Personal, and Local wireless networks, and we discuss their applicative scenarios. The second part of the chapter focuses on the emerging networking standards for constructing small- scale ad hoc networks: IEEE 802.11 and Bluetooth. The IEEE 802.11 standard is a good platform to implement a single-hop local ad hoc network because of its extreme simplicity. Furthermore, multi-hop networks covering areas of several square kilometers could be built by exploiting the IEEE 802.11 technology. On smaller scales, the Bluetooth technologies can be exploited to build ad hoc wireless Personal and Body Area Networks, i.e., networks that connect devices placed on a person’s body or inside a small circle around it. The chapter presents the architectures and protocols of IEEE 802.11 and Bluetooth. In addition, the performance of these two technologies is discussed. © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com 1.1 Introduction In recent years, the proliferation of mobile computing devices (e.g., laptops, handheld digital devices, personal digital assistants [PDAs], and wearable computers) has driven a revolutionary change in the computing world. As shown in Fig. 1.1, we are moving from the Personal Computer (PC) age (i.e., one computing device per person) to the Ubiquitous Computing age in which individual users utilize, at the same time, several electronic platforms through which they can access all the required information whenever and wherever they may be [47]. The nature of ubiquitous devices makes wireless networks the easiest solution for their interconnection. This has led to rapid growth in the use of wireless technologies for the Local Area Network (LAN) environment. Beyond supporting wireless connectivity for ﬁxed, portable, and moving stations within a local area, wireless LAN (WLAN) technologies can provide a mobile and ubiquitous connection to Internet information services [10]. It is foreseeable that in the not- so-distant future, WLAN technologies will be utilized largely as means to access the Internet. WLAN products consume too much power and have excessive range for many personal consumer electronic and computer devices [40]. A new class of networks is therefore emerging: Personal Area Networks. A Personal Area Network (PAN) allows the proximal devices to dynamically share information with minimum power consumption [49]. LANs and PANs do not meet all the networking requirements of ubiquitous computing. Situations exist where carrying and holding a computer are not practical (e.g., assembly line work). A wearable computer solves these problems by distributing computer components (e.g., head-mounted displays, microphones, earphones, processors, and mass storage) on the body [21,49]. Users can thus receive job- critical information and maintain control of their devices while their hands remain free for other work. A network with a transmission range of a human body, i.e., a Body Area Network (BAN), constitutes the best solution for connecting wearable devices. Wireless connectivity is envisaged as a natural solution for BANs. One target of the ubiquitous computing revolution is the ability of the technology to adapt itself to the user without requiring that users modify their behavior and knowledge. PCs provided to their users a large set of new services that revolutionized their lives. However, to exploit the PC’s beneﬁts, users have had to adapt themselves to PC standards. The new trend is to help users in everyday life by exploiting technology and infrastructures that are hidden in the environment and do not require any major change in the users’ behavior. This new philosophy is the basis of the ambient intelligence concept [1]. The objective of ambient intelligence is the integration of digital devices and networks into the everyday environment. This will render accessible, through easy and “natural” interactions, a multitude of services and applica- tions. Ambient intelligence places the user at the center of the information society. This view heavily relies on wireless and mobile communications [36,37]. Speciﬁcally, advances in wireless communication will Personal Computing Ubiquitous Computing FIGURE 1.1 From PC age (one-to-one) to ubiquitous computing (one-to-many). © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com BAN PAN LAN WAN ~1m ~10m ~500m Range FIGURE 1.2 Ad hoc networks taxonomy. enable a radical new communication paradigm: self-organized information and communication systems [17]. In this new networking paradigm, the users’ mobile devices are the network, and they must coop- eratively provide the functionality that is usually provided by the network infrastructure (e.g., routers, switches, and servers). Such systems are sometimes referred to as mobile ad hoc networks (MANETs) [33] or as infrastructure-less wireless networks. 1.2 Mobile Ad Hoc Networks A Mobile Ad hoc NETwork (MANET) is a system of wireless mobile nodes that dynamically self-organize in arbitrary and temporary network topologies. People and vehicles can thus be internetworked in areas without a preexisting communication infrastructure or when the use of such infrastructure requires wireless extension [17]. As shown in Fig. 1.2, we can classify ad hoc networks, depending on their coverage area, into four main classes: Body, Personal, Local, and Wide Area Networks. Wide area ad hoc networks are mobile multi-hop wireless networks. They present many challenges that are still to be solved (e.g., addressing, routing, location management, security, etc.), and they are not likely to become available for some time. On smaller scales, mobile ad hoc networks will soon appear [6]. Speciﬁcally, ad hoc, single-hop BAN, PAN, and LAN wireless networks are beginning to appear on the market. These technologies constitute the building blocks to construct small multi-hop ad hoc networks that extend the range of the ad hoc networks’ technologies over a few radio hops [16,17]. 1.2.1 Body Area Network A Body Area Network is strongly correlated with wearable computers. The components of a wearable computer are distributed on the body (e.g., head-mounted displays, microphones, earphones, etc.), and a BAN provides the connectivity among these devices. Therefore, the main requirements of a BAN are [18,19]: 1. The ability to interconnect heterogeneous devices, ranging from complete devices (e.g., a mobile phone) to parts of a device (microphone, display, etc.) 2. Autoconﬁguration capability (Adding or removing a device from a BAN should be transparent to the user.) 3. Services integration (Isochronous data transfer of audio and video must coexist with non–real time data, e.g., Internet data trafﬁc.) 4. The ability to interconnect with the other BANs (to exchange data with other people) or PANs (e.g., to access the Internet) The communicating range of a BAN corresponds to the human body range, i.e., 1–2 meters. As wiring a body is generally cumbersome, wireless technologies constitute the best solution for interconnecting wearable devices. © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com One of the ﬁrst examples of BAN is the prototype developed by T.G. Zimmerman [48], which could provide data communication (with rates up to 400,000 bits per second) by exploiting the body as the channel. Speciﬁcally, Zimmerman showed that data can be transferred through the skin by exploiting a very small current (one billionth of an amp). Data transfer between two persons (i.e., BAN interconnec- tion) could be achieved through a simple handshake. A less visionary BAN prototype was developed in the framework of the MIThril project where a wired Ethernet network was adopted to interconnect wearable devices [35]. Marketable examples of BANs have just appeared (see [19], [32], and [38]). These examples consist of a few electronic devices (phone, MP3 player, headset, microphone, and controller), which are directly connected by wires integrated within a jacket. In the future, it might be expected that more devices (or parts of devices) will be connected using a mixture of wireless and wired technologies. 1.2.2 Personal Area Network Personal area networks connect mobile devices carried by users to other mobile and stationary devices. While a BAN is devoted to the interconnection of one-person wearable devices (see part a of Fig. 1.3), a PAN is a network in the environment around the person. A PAN communicating range is typically up to 10 meters, thus enabling (see part b of Fig. 1.3): 1. The interconnection of the BANs of people close to each other 2. The interconnection of a BAN with the environment around it Wireless PAN (WPAN) technologies in the 2.4 GHz ISM band are the most promising technologies for widespread PAN deployment. Spread spectrum is typically employed to reduce interference and utilize the bandwidth. The technologies for WPANs offer a wide space for innovative solutions and applications that could create radical changes in everyday life. We can foresee that a WPAN interface will be embedded not only in such devices as cellular phones, mobile computers, PDAs, and so on, but in every digital device. Obvious applications arise from the possibility of forming ad hoc networks with our workspace electronic devices, e.g., a PDA that automatically synchronizes with the desktop computer to transfer e-mail, ﬁles, and schedule information. Moreover, PANs make possible the design of innovative pervasive applications. For example, let us imagine a PDA (with a PAN interface) that upon your arrival at a location (e.g., home, ofﬁce, airport, etc.) automatically synchronizes (via the PAN network interface) with all the electronic devices within its 10-meter range. For example, when you arrive at home, your PDA can automatically unlock the door, turn on the house lights while you are getting in, and adjust the heat or air conditioning to your preset preferences. Similarly, when you arrive at the airport you can avoid the line at the check- in desk by using your handheld device to present an electronic ticket and automatically select your seat. (a) (b) FIGURE 1.3 Relationship between a Body (part a) and a Personal Area Network (part b). © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Serv er Legend: (a) (b) access point FIGURE 1.4 WLAN conﬁgurations: (a) ad hoc networking; (b) infrastructure-based. wired network 1.2.3 Wireless Local Area Network In the last few years, the use of wireless technologies in the LAN environment has become more and more important, and it is easy to foresee that the wireless LANs (WLANs) — as they offer greater ﬂexibility than wired LANs — will be the solution for home and ofﬁce automation. Like wired LANs, a WLAN has a communication range typical of a single building or a cluster of buildings, i.e., 100–500 meters. A WLAN should satisfy the same requirements typical of any LAN, including high capacity, full connectivity among attached stations, and broadcast capability. However, to meet these objectives, WLANs should be designed to face some issues speciﬁc to the wireless environment, such as security on the air, power consumption, mobility, and bandwidth limitation of the air interface [39]. Two different approaches can be followed in the implementation of a WLAN (see Fig. 1.4): an infra- structure-based approach or an ad hoc networking approach [39]. An infrastructure-based architecture imposes the existence of a centralized controller for each cell, often referred to as the Access Point (see Fig. 1.4b). The Access Point is normally connected to the wired network, thus providing Internet access to mobile devices. In contrast, an ad hoc network is a peer-to-peer network formed by a set of stations within the range of each other that dynamically conﬁgure themselves to set up a temporary network (see Fig. 1.4a). In the ad hoc conﬁguration, no ﬁxed controller is required, but a controller is dynamically elected among all the stations participating in the communication. 1.3 Technologies for Ad Hoc Networks The success of a network technology is connected to the development of networking products at a com- petitive price. A major factor in achieving this goal is the availability of appropriate networking standards. Currently, two main standards are emerging for ad hoc wireless networks: the IEEE 802.11 standard for WLANs [25] and the Bluetooth speciﬁcations1 for short-range wireless communications [3,4,34]. The IEEE 802.11 standard is a good platform for implementing a single-hop WLAN ad hoc network because of its extreme simplicity. Multi-hop networks covering areas of several square kilometers could also be built by exploiting the IEEE 802.11 technology. On smaller scales, technologies such as Bluetooth can be used to build ad hoc wireless Body and Personal Area Networks, i.e., networks that connect devices on the person, or placed around the person inside a circle with a radius of 10 meters. 1 The Bluetooth speciﬁcations are released by the Bluetooth Special Interest Group [12]. © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Here we present the architecture and protocols of IEEE 802.11 and Bluetooth. In addition, the per- formances of these technologies are analyzed. Two main performance indices will be considered: the throughput and the delay. As far as throughput is concerned, special attention will be paid to the Medium Access Control (MAC) protocol capacity [15,30], deﬁned as the maximum fraction of channel bandwidth used by successfully transmitted messages. This performance index is important because the bandwidth delivered by wireless networks is much lower than that of wired networks, e.g., 1–11 Mb/sec vs. 100–1000 Mb/sec [39]. Since a WLAN relies on a common transmission medium, the transmissions of the network stations must be coordinated by the MAC protocol. This coordination can be achieved by means of control information that is carried explicitly by control messages traveling along the medium (e.g., ACK messages) or can be provided implicitly by the medium itself using the carrier sensing to identify the channel as either active or idle. Control messages or message retransmissions due to collision remove channel bandwidth from that available for successful message transmission. Therefore, the capacity gives a good indication of the overheads required by the MAC protocol to perform its coordination task among stations or, in other words, of the effective bandwidth that can be used on a wireless link for data transmission. The delay can be deﬁned in several forms (access delay, queuing delay, propagation delay, etc.) depend- ing on the time instants considered during its measurement (see [15]). In computer networks, the response time (i.e., the time between the generation of a message at the sending station and its reception at the destination station) is the best value to measure the Quality of Service (QoS) perceived by the users. However, the response time depends on the amount of buffering inside the network, and it is not always meaningful for the evaluation of a LAN technology. For example, during congested periods, the buffers ﬁll up, and thus the response time does not depend on the LAN technology but it is mainly a function of the buffer length. For this reason, hereafter, the MAC delay index is used. The MAC delay of a station in a LAN is deﬁned as the time between the instant at which a packet comes to the head of the station transmission queue and the end of the packet transmission [15]. 1.4 IEEE 802.11 Architecture and Protocols In 1997, the IEEE adopted the ﬁrst wireless local area network standard, named IEEE 802.11, with data rates up to 2 Mb/sec [27]. Since then, several task groups (designated by letters) have been created to extend the IEEE 802.11 standard. Task groups 802.11b and 802.11a have completed their work by providing two relevant extensions to the original standard [25]. The 802.11b task group produced a standard for WLAN operations in the 2.4 GHz band, with data rates up to 11 Mb/sec. This standard, published in 1999, has been very successful. Currently, there are several IEEE 802.11b products available on the market. The 802.11a task group created a standard for WLAN operations in the 5 GHz band, with data rates up to 54 Mb/sec. Among the other task groups, it is worth mentioning task group 802.11e (which attempts to enhance the MAC with QoS features to support voice and video over 802.11 networks) and task group 802.11g (which is working to develop a higher-speed extension to 802.11b). The IEEE 802.11 standard speciﬁes a MAC layer and a physical layer for WLANs (see Fig. 1.5). The MAC layer provides to its users both contention-based and contention-free access control on a variety of physical layers. Speciﬁcally, three different technologies can be used at the physical layer: infrared, frequency hopping spread spectrum, and direct sequence spread spectrum [27]. The basic access method in the IEEE 802.11 MAC protocol is the Distributed Coordination Function (DCF), which is a Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) MAC protocol. Besides the DCF, the IEEE 802.11 also incorporates an alternative access method known as the Point Coordination Function (PCF). The PCF operates similarly to a polling system [15]; a point coordinator provides (through a polling mechanism) the transmission rights at a single station at a time. As the PCF access method cannot be adopted in ad hoc networks, in the following we will concentrate on the DCF access method only. © 2003 by CRC Press LLC
Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com contention free services contention services Point Coordination Function Distributed Coordination Function Physical Layer FIGURE 1.5 IEEE 802.11 architecture. Source DIFS EIFS DIFS DATA A CWA LA FS SI ACK Destination B LB CW B DIFS C LC CWC Other NAV CW Collision Length =L A (a) (b) FIGURE 1.6 IEEE 802.11 DCF: (a) a successful transmission; (b) a collision. 1.4.1 IEEE 802.11 DCF The DCF access method, hereafter referred to as Basic Access, is summarized in Fig. 1.6. When using the DCF, before a station initiates a transmission, it senses the channel to determine whether another station is transmitting. If the medium is found to be idle for an interval that exceeds the Distributed InterFrame Space (DIFS), the station continues with its transmission.2 The transmitted packet contains the projected length of the transmission. Each active station stores this information in a local variable named Network Allocation Vector (NAV). Therefore, the NAV contains the period of time the channel will remain busy (see Fig. 1.6a).3 The CSMA/CA protocol does not rely on the capability of the stations to detect a collision by hearing their own transmissions. Hence, immediate positive acknowledgments are employed to ascertain the successful reception of each packet transmission. Speciﬁcally, the receiver after the reception of the data frame (1) waits for a time interval, called the Short InterFrame Space (SIFS), which is less than the DIFS, and then (2) initiates the transmission of an acknowledgment (ACK) frame. The ACK is not transmitted if the packet is corrupted or lost due to collisions. A Cyclic Redundancy Check (CRC) algorithm is adopted to discover transmission errors. Collisions among stations occur when two or more stations start transmitting at the same time (see Fig. 1.6b). If an acknowledgment is not received, the data frame is presumed to have been lost, and a retransmission is scheduled. 2 To guarantee fair access to the shared medium, a station that has just transmitted a packet and has another packet ready for transmission must perform the backoff procedure before initiating the second transmission. 3 This prevents a station from listening to the channel during transmissions. This feature is useful to implement (among others) power-saving policies. © 2003 by CRC Press LLC