At the core of modern computer networking is wireless communication. The modulation of transmitted information is the noise-immune and powerful vehicle that safely carries the weak source analog/digital information for long distances over the noisy ether. Hence, modulation is essential for the integrity and advancement of the data communication field, which is the backbone of computer networking and the Internet. The author breaks down the complexity of different signal modulation techniques in a simple fashion. Thus, the book is easy to understand, with a smooth flow of presentation and a focus on key technical factors. It also provides specific and useful examples at the end of each section.
The book discusses the implementation of different wireless modulation mechanisms that carry information between source and destination over a cheap, yet challenging, medium. These modulation processes use a powerful and noise-immune sinusoidal wave carrier (continuous and periodic). As the input signal changes, the carrier amplitude (signal power), frequency (how often the carrier goes through a cycle), or phase-shift (the carrier elapsed portion relative to the origin) will be changed accordingly to modulate input signals (AM/ASK, FM/FSK, or PSK, respectively). The book also covers important related technical aspects: signal spectrum bandwidth (BW), AM double-sideband-suppressed carriers, the power and BW-efficient single-side band modulation, block coding with parity bits, error analysis, and signal-to-noise effect on modulated signal. In the wireless communication field, it is essential to modulate the very weak analog (continuous) signals (for example, voice and computer digital data) before transmitting them wirelessly. Such analog carrier modulation should overcome the challenge of maintaining the efficient wireless exchange of information over long distances, using a noisy, error-prone, and limited BW media. The aim of modulation advances is to entertain applications that demand quality of service (QoS) (for example, low error and high data transmission rate), which requires very clever and efficient encoding and modulation techniques. This book will aid in the thorough understanding of some basic/solid modulation techniques as a stepping stone to proceed to explore further advances in the field. For example, it will help in the understanding of the prominent IEEE 802 physical protocols standards, along with the most recent development of the gigabit/sec standards such as IEEE 802.11ac and 802.11ad.
The book introduces the utilization of different components of a periodic sinusoidal carrier, such as amplitude (power level), frequency, or phase in the modulation process. At the transmission source (analog input signals), the amplitude or frequency of the carrier is varied, according to the variations on the input signal, to obtain its amplitude or frequency modulation (AM or FM). For modulating digital input signals, the amplitude, frequency, or phase-shift (one only) of the carrier will change in accordance with the input digital signal. Hence, we obtain amplitude, frequency, or phase shift keying modulated carrier signals (ASK, FSK, and PSK, respectively). At the receiving end, an opposite demodulation process is carried out to detect the received modulated carrier’s amplitude, frequency, and phase in order to extract the original input digital signal values. The author explores the aforementioned modulation techniques in a very pedagogic way, with concise time and frequency domains analysis to prove key modulation formulas/factors (for example, BW, bit error rate (BER), and word error rate (WER)). In the process, the author compares the pros and cons of each the above modulation techniques.
Some significant related factors in the process are: (1) the bandwidth of the transmitted data’s modulated signals and its effect on the maximum data rate, and (2) the block encoding and error correction of the input signal code. It is stated that the signal BW, in the frequency spectrum, is the width of the variation around the central carrier frequency, which is a result of the input digital signal state (0 and 1) variations. Moreover, the book analyzes the block encoding of modulated information with additional redundant bits to allow the correction of erroneous bits. In such analysis, the uncoded/coded word error (WER-U/C) is obtained as a function of the BER and bit-coded energy-to-noise ratio. The BW-efficient N-ary complementary codes, which are modulated via M-ary PSK modulation, are also presented and analyzed. The parallel input bit-stream is mapped into N unique conventional and orthogonal codes, which are then M-ary PSK modulated, and then recovered at the receiver via code correlation and a table lookup validation.
Despite the great aspects of the book, it lacks the discussion of the important N-quadrature amplitude modulation (QAM) encoding (2N combinations of amplitude- and phase-shift carrier modulations, encoding N bits/change), which is used in wireless applications/protocols. Yet overall, the book is a concise, brief, informative, and excellent tutorial for introducing readers to wireless signal modulation. This book is an exemplar in its domain. It is very useful as a complementary source/reference for undergraduate students in the area of wireless data communication.
