Orthogonal Frequency Division Multiplexing for Wireless Communications

Frequency division multiplexing (FDM) is a technology that transmits multiple signals simultaneously over a single transmission path, such as a cable or wireless system. Each signal travels within its own unique frequency range (carrier), which is modulated by the data (text, voice, video, etc.).

Orthogonal FDM's (OFDM) spread spectrum technique distributes the data over a large number of carriers that are spaced apart at precise frequencies. This spacing provides the "orthogonality" in this technique which prevents the demodulators from seeing frequencies other than their own. The benefits of OFDM are high spectral efficiency, resiliency to RF interference, and lower multi-path distortion. This is useful because in a typical terrestrial broadcasting scenario there are multipath-channels (i.e. the transmitted signal arrives at the receiver using various paths of different length). Since multiple versions of the signal interfere with each other (inter symbol interference (ISI)) it becomes very hard to extract the original information.

OFDM is sometimes called multi-carrier or discrete multi-tone modulation. It is the modulation technique used for digital TV in Europe, Japan and Australia.

OFDM (Orthogonal frequency division multiplexing} has been shown to be an effective technique to combat multipath fading in wireless channels. It is being used in various wireless communication systems such as in Digital Audio Broadcasting (DAB) and Video Broadcasting (DVB) in Europe and many of IEEE 802.11 and IEEE 802.16 standards.

This book provides a comprehensive introduction to the theory and practice of OFDM for wireless communications. It includes basic concepts of OFDM, performance optimization, time- and frequency-offset estimation, channel estimation, peak-to-average power ratio reduction, and MIMO OFDM techniques. The key concepts are developed with detailed derivations and proofs to make the material accessible and easy to follow by both students and professionals. While chapters have been written by experts in their respective subject area, the authors have tried to make symbols, notations, presentations and styles consistent. To facilitate readers, the material includes extensive references as well as a large and useful index at the end of the book.

OFDM for Wireless Communications is highly recommended for graduate level courses in advanced digital communication and professional seminars and tutorials on wireless OFDM.