the aim of this book is to enable the reader to develop a sound knowledge of wideband communications, such as ofdm, applied in digital audio broadcasting, and cdma, the foundation of third generation mobile communications. as this is a fast growing field, graduates of engineering programmes as well as practising engineers should be familiar with the principles of wideband communications, particularly of ofdm and cdma in connection with mobile radio channels. thus, a textbook is necessary that provides a far-reaching treatise beginning from fundamentals to modern applications. focusing on relevant items, the book is intended to be rigorous, however readable. the fundamentals at the beginning of the book is reduced to a measure that suits the needs of further considerations and derivations, i.e. should not and can not replace textbooks specialising in digital communications or error-correcting coding etc. whilst working in industry, the authors were active in the fields of mobile communications (gsm) and digital audio broadcasting (dab) and have gained a thorough insight while contributing to different digital communication systems in connection with mobile radio channels. the authors felt there was the distinct need for this book through observing the continuous growth of telecommunications and information technology, which has resulted in expanding data transfer and in a need for increased data rate and bandwidth, and the forthcoming new communication systems featuring ever more complex modulation and demodulation techniques. as a result of lecturing at universities in this field the demand for such a textbook has become apparent.