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Über dieses Buch

Computer communication networks have come of age. Today, there is hardly any professional, particularly in engineering, that has not been the user of such a network. This proliferation requires the thorough understanding of the behavior of networks by those who are responsible for their operation as well as by those whose task it is to design such networks. This is probably the reason for the large number of books, monographs, and articles treating relevant issues, problems, and solutions in this field. Among all computer network architectures, those based on broadcast mul­ tiple access channels stand out in their uniqueness. These networks appear naturally in environments requiring user mobility where the use of any fixed wiring is impossible and a wireless channel is the only available option. Because of their desirable characteristics multiple access networks are now used even in environments where a wired point-to-point network could have been installed. The understanding of the operation of multiple access network through their performance analysis is the focus of this book.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract
Three major components characterize computer communication networks:switches, channels, and protocols. The switches (or nodes) are the hardware entities that house the data communication functions; the protocols are the sets of rules and agreements among the communicating parties that dictate the behavior of the switches, and the channel is the physical medium over which signals, representing data, travel from one switch to another.
Raphael Rom, Moshe Sidi

Chapter 2. Conflict-Free Access Protocols

Abstract
Conflict-free protocols are designed to ensure that a transmission, whenever made, is not interfered by any other transmission and is therefore successful. This is achieved by allocating the channel to the users without any overlap between the portions of the channel allocated to different users. An important advantage of conflict-free access protocols is the ability to ensure fairness among users and the ability to control the packet delay—a feature that may be essential in real-time applications.
Raphael Rom, Moshe Sidi

Chapter 3. Aloha Protocols

Abstract
The Aloha family of protocols is probably the richest family of multiple access protocols. Its popularity is due first of all to seniority, as it is the first random access technique introduced. Second, many of these protocols are so simple that their implementation is straightforward. Many local area networks of today implement some sophisticated variants of this family’s protocols.
Raphael Rom, Moshe Sidi

Chapter 4. Carrier Sensing Protocols

Abstract
The Aloha schemes, described in the previous chapter, exhibited fairly poor performance which can be attributed to the “impolite” behavior of the users namely, whenever one has a packet to transmit he does so without consideration of others. It does not take much to realize that even little consideration can benefit all. Consider a behavior that we generically characterize as “listen before talk”, that is, every user before attempting any transmission listens whether somebody else is already using the channel. If this is the case the user will refrain from transmission to the benefit of all; his packet will clearly not be successful if transmitted and, further, disturbing another user will cause the currently transmitted packet to be retransmitted, possibly disturbing yet another packet.
Raphael Rom, Moshe Sidi

Chapter 5. Collision Resolution Protocols

Abstract
We have seen that the original Aloha protocol is inherently unstable in the absence of some external control. If we look into the philosophy behind the Aloha protocol, we notice that there is no sincere attempt to resolve collisions among packets as soon as they occur. Instead, the attempts to resolve collisions are always deferred to the future, with the hope that things will then work out, somehow, but they never do.
Raphael Rom, Moshe Sidi

Chapter 6. Additional Topics

Abstract
The field of multiple access systems is much too broad to be contained in a single book. Although we treated in depth many fundamental protocols and systems, we were able to uncover just the tip of the iceberg. Many important and interesting subjects in this field were not discussed in the book, either because they are beyond the scope we planned for the book or because they are still in a formative and fragmentary stage of research. This section is devoted to short descriptions of several of these subjects.
Raphael Rom, Moshe Sidi

Backmatter

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