This chapter has discussed how a commonbroadcast medium can be shared among many contending users. Multiple access protocols differ primarily by the amount of coordination needed to control potentially conflicting packet transmissions. Ato neextreme is random access where no coordinationis provideda ndp acket collisions arep ossible. Atthe other endo fthe spectrum, the class of fixed assignment access protocols eliminates collisions entirely butpay the price ofadditional overhead required forscheduling user access. Hybrid access protocolsb etweenthese two extremes exist While these protocols attempt to combine the advantages ofrandom andfixed access, they also suffer the c ombined drawbacks and overhead ofboth classes of access schemes. Amongt he many factors that determine the performance ofa n access protocol include the propagation delay/packet transmission timeratio, the message arrival process, the types of feedback information available, the user population, and the ability of the user to sense the activities in the network. BIBLIOGRAPHY [ABRA93] Abramson, N. , Multiple Access Communications , IEEE Press, 1993. [BERT92] Bertsekas, D. and Gallager, R. , Data Networks , Prentice Hall, 1992. [CHOU83]Chou,W, ComputerCommunications Volume1:Principles , Prentice Hall, 1983. [CIDO87] Cidon, I. andSidi, M. , "Erasures and Noise in Splitting Multiple Access Algorithms", IEEE Transactions on Information Theory, Vol. 33, No. 1, January 1987, pp. 132 - 140. [CIDO88] Cidon, I, Kodesh, H. and Sidi, M. , "Erasure, Capture and Random Power Level Selectionin Multiple Access Systems", IEEE Transactions on Communications , Vol. 3 6,N o. 3,March 1988, pp. 263 - 271.

This chapter has discussed how a commonbroadcast medium can be shared among many contending users. Multiple access protocols differ primarily by the amount of coordination needed to control potentially conflicting packet transmissions. Ato neextreme is random access where no coordinationis provideda ndp acket collisions arep ossible. Atthe other endo fthe spectrum, the class of fixed assignment access protocols eliminates collisions entirely butpay the price ofadditional overhead required forscheduling user access. Hybrid access protocolsb etweenthese two extremes exist While these protocols attempt to combine the advantages ofrandom andfixed access, they also suffer the c ombined drawbacks and overhead ofboth classes of access schemes. Amongt he many factors that determine the performance ofa n access protocol include the propagation delay/packet transmission timeratio, the message arrival process, the types of feedback information available, the user population, and the ability of the user to sense the activities in the network. BIBLIOGRAPHY [ABRA93] Abramson, N. , Multiple Access Communications , IEEE Press, 1993. [BERT92] Bertsekas, D. and Gallager, R. , Data Networks , Prentice Hall, 1992. [CHOU83]Chou,W, ComputerCommunications Volume1:Principles , Prentice Hall, 1983. [CIDO87] Cidon, I. andSidi, M. , "Erasures and Noise in Splitting Multiple Access Algorithms", IEEE Transactions on Information Theory, Vol. 33, No. 1, January 1987, pp. 132 - 140. [CIDO88] Cidon, I, Kodesh, H. and Sidi, M. , "Erasure, Capture and Random Power Level Selectionin Multiple Access Systems", IEEE Transactions on Communications , Vol. 3 6,N o. 3,March 1988, pp. 263 - 271.

This indispensable book provides you with the key practical tools and background knowledge for deploying WiFi networks, as well as a solid appreciation of the emerging technologies. Thirty-eight self-contained contributions written by CTOs, prominent academic-based researchers, and industry leaders set out the physical and engineering principles underpinning the latest developments, and examine future potential. Topics covered include quality of service, security, high throughput 802.11, WLAN/cellular interworking, coexistence, network and radio research management, hardware design, hotspots, and public wireless broadband. Future WiFi standards and technologies, including the new 802.11 initiatives - 802.11s, 802.11n and 802.11k - are addressed, as are the various Wi Fi applications. Other emerging WiFi technologies covered include MIMO systems, intelligent (cognitive) systems, multihop (mesh) networks, WiFi sensors, WiFi RFID, WiFi mixed-mobile convergence, and long-range WiFi. This is an invaluable resource for researchers and graduate students in electrical engineering and computer science departments, as well as practitioners in the wireless communications industry.

Broadband Last Mile: Access Technologies for Multimedia Communications provides in-depth treatments of access technologies and the applications that rely upon them or support them. It examines innovations and enhancements along multiple dimensions in access, with the overarching goal of ensuring that the last mile is not the weak link in the broadband chain. Written by experts from the academic and commercial segments of the field, the book's self-contained sections address topics related to the disciplines of communications, networking, computing, and signal processing. The core of this treatment contains contemporary reviews of broadband pipes in the classes of copper, cable, fiber, wireless, and satellite. It emphasizes the coexistence of these classes within a network, the importance of optical communications for unprecedented bandwidth, and the flexibility and mobility provided by wireless. The book also includes perspective on the increasingly important topic of network management, providing insights that are true regardless of the nature of the pipe. The text concludes with a discussion of newly emerging applications and broadband services. This book offers an all-in-one treatment of the physical pipes and network architectures that make rich and increasingly personalized applications possible. It serves as a valuable resource for researchers and practitioners working in the increasingly pervasive field of broadband.