On-Off keying for wireless communication channel estimation

1. How is channel estimation done in wireless communication?
2. Why do we require channel estimation in advanced wireless communication?

How is channel estimation done in wireless communication?

Channel estimation can be carried out in different ways: with or without the help of a parametric model, using frequency and/or time correlation properties in the wireless channel, blind methods or those based on training pilots, adaptive or non-adaptive methods.

Why do we require channel estimation in advanced wireless communication?

So channel estimation technique is introduced to improve accuracy of the received signal. The radio channels in mobile communication systems are usually multipath fading channels, which are causing inter symbol interference (ISI) in the received signal.