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About this book

This book provides a comprehensive overview of multiple access techniques used in the cellular industry. The usage of multiple access techniques in telecommunications enables many users to share the same spectrum in the frequency domain, time domain, code domain or phase domain. Licenses are given, by the FCC, to operate wireless communication systems over given bands of frequencies, with the smaller bands, (channels), reused to provide services to other users. Thus, bandwidth efficiency is vital, as the speed and size of digital data networks continue to expand. This brief also uses numerous illustrations to bring students up-to-date in the practical applications of multiple access techniques, which can then be put to work in the industry. Primarily, electrical engineering students who study telecommunications, as well as engineers and designers working in wireless communications, would find this book useful.

Table of Contents

Frontmatter

Chapter 1. Introduction

Abstract
Multiple access techniques enable many users to share the same spectrum in the frequency domain, time domain, code domain, or phase domain. It begins with a frequency band, allocated by FCC (Federal Communication Commission). FCC provides licenses to operate wireless communication systems over given bands of frequencies. These bands of frequencies are finite and have to be further divided into smaller bands (Channels) and reused to provide services to other users. This is governed by the International Telecommunication Union (ITU). ITU generates standards such as FDMA, TDMA, CDMA, OFDMA, etc. for wireless communications. These standards along with numerous illustrations are presented to bring the students up-to-date in key concepts, underlying principles, and practical applications of multiple access techniques so that they can readily put them into work in the cellular industry.
Saleh Faruque

Chapter 2. Simplex, Duplex, FDD, and TDD

Abstract
In telecommunication, there are various ways to communicate between two points, referred to as mode of operation. This is usually done in three ways: simplex, half-duplex, and full duplex. Simplex is a one-way communication such as broadcasting. Half duplex is a two-way communication but one at a time such as taxi dispatch system. Full duplex is a method of two-way communication, where two users can communicate with each other simultaneously such as land-mobile telephone system. In full duplex communication, the link is maintained in both directions, either in the frequency domain or in the time domain. This is governed by two basic communication schemes: frequency division duplex (FDD) and time division duplex (TDD). A brief description of these communication modes is presented in this chapter.
Saleh Faruque

Chapter 3. Frequency Division Multiple Access (FDMA)

Abstract
FDMA (frequency division multiple access) is the oldest communication technique used in broadcasting, land-mobile two-way radio, etc. It begins with a band of frequencies, which is allocated by the FCC (Federal Communications Commission). This band of frequency is further divided into several narrow bands of frequencies, where each frequency, also known as channel, is used for full-duplex communication. The communication link is maintained in both directions, either in the frequency domain or in the time domain. This is governed by two basic modes of operations known as the Frequency Division Duplex (FDD) and Time Division Duplex (TDD). These topics, along with FDMA spectrum management and its attributes, are presented in this chapter.
Saleh Faruque

Chapter 4. Time Division Multiple Access (TDMA)

Abstract
Time division multiple access (TDMA) is a method of transmitting and receiving multiple independent signals over a single transmission channel. The TDMA at the transmit side, known as the multiplexer, assigns multiple channels in preassigned time slots. The TDMA at the receive side, known as the de-multiplexer, separates the incoming composite signal into parallel streams. Both multiplexer and de-multiplexer are synchronized by a common clock to receive data in accordance with the transmit sequence. This chapter presents the key concepts, underlying principles and practical applications of TDMA used in land-mobile telecommunication systems.
Saleh Faruque

Chapter 5. Code Division Multiple Access (CDMA)

Abstract
This chapter presents a brief overview of spread spectrum technique and shows how it relates to CDMA technology. Orthogonal codes and their properties are presented and show how orthogonal codes are generated and used to design CDMA radio. It is shown that CDMA capacity directly relates to code length.
Saleh Faruque

Chapter 6. Orthogonal Frequency Division Multiple Access (OFDMA)

Abstract
This chapter presents a brief overview of the OFDMA technique used in 4G WiMAX (Worldwide Interoperability for Microwave Access) and 4G LTE (Long-Term Evolution) cellular system. It is shown that OFDMA is an extension of FDMA, where each frequency band is placed at the null of the adjacent frequency band. This is governed by the well-known “Fourier transform,” so that adjacent frequency bands are orthogonal to each other. OFDMA is a full-duplex communication system. The communication link is maintained in both directions in the time domain known as time division duplex (TDD). Numerous illustrations are used to bring students up to date in key concepts, underlying principles, and practical applications of “Fourier transform,” spectrum, and orthogonal properties of spectrum, leading to OFDMA. Construction of OFDMA channels from the FCC-allocated band is presented to illustrate the concept.
Saleh Faruque
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