Frequency-selective channel Basic in theory

1. What is frequency selective channel?
2. What is frequency selective fading channel?
3. What are the techniques can be used for reducing the effects of frequency selective fading?
4. What is doubly selective channels?

What is frequency selective channel?

Frequency selective channels are characterized by time varying nature of the channel. For simulating a frequency selective channel, it is mandatory to have N > 1. In contrast, if N = 1, it simulates a zero-mean fading channel where all the multipath signals arrive at the receiver at the same time.

What is frequency selective fading channel?

The time-varying gain of the channel output is also frequency dependent. When channels are time-varying and also dependent on frequency, they are called frequency-selective fading channels. Such channels are characterized by time-varying ISI, and thus require complex equalization.

What are the techniques can be used for reducing the effects of frequency selective fading?

Different techniques being employed to reduce the effect of fading using Diversity, rake receiver and equalization are also discussed. Keywords: Diversity, Equalization, Fading, Multipath Propagation, Rake receiver .

What is doubly selective channels?

focus of this paper is on learning doubly-selective channels, which are characterized by the fact that the delay spread and Doppler spread of the channel are large relative to the inverse of the signaling bandwidth and duration, respectively, i.e., Wτmax ≥ 1 and Tνmax ≥ 1.