The wireless channel introduces frequency-selective fading to the transmitted signal when the channel coherence bandwidth B_c is smaller than transmitted signal bandwidth B_s. In this chapter, we discuss the challenges and candidate solutions for digital wireless transmission over frequency-selective fading channels. We first discuss the effects of selective fading on digital wireless transmission. We then present two classes of transmission technologies for frequency-selective fading channels, namely equalization and multicarrier transmission. Special emphasis was placed on orthogonal frequency division multiplexing (OFDM) technology, the practical discrete implementations of multicarrier transmission, as several advanced wireless systems adopt this transmission technology.

Chapter Contents:

• 6.1 Effect of frequency-selective fading
• 6.2 Equalization
• 6.2.1 Equalizing receiver
• 6.2.2 Digital implementation
• 6.2.3 Adaptive implementation
• 6.3 Multicarrier transmission
• 6.4 Discrete implementation/OFDM
• 6.5 Challenges of OFDM transmission
• 6.6 Further readings
• Problems
• Bibliography

Inspec keywords: OFDM modulation; fading channels; equalisers

Other keywords: digital wireless transmission; wireless channel; frequency-selective fading; channel coherence bandwidth; transmitted signal bandwidth; transmission technology; advanced wireless systems; equalization; orthogonal frequency division multiplexing; frequency-selective fading channels; OFDM technology; multicarrier transmission

Subjects: Radio links and equipment; Communication channel equalisation and identification; Modulation and coding methods