What is the significance of pilot carriers in ofdm [duplicate]

1. Why are pilots used in OFDM?
2. What are pilot subcarriers in OFDM?
3. Why pilot symbols are used?
4. What is pilot based channel estimation?

Why are pilots used in OFDM?

In each OFDM symbol, four of the subcarriers are dedicated to pilot signals in order to make the coherent detection robust against frequency offsets and phase noise.

What are pilot subcarriers in OFDM?

Pilot Subcarriers: The pilot subcarriers do not carry modulated data; however, they are used for synchronization purposes between the receiver and transmitter.

Why pilot symbols are used?

The pilot symbols are constructed to be nonoverlapping in frequency to allow simultaneous sounding of the multiple channels. The time- varying channel responses are tracked by interpolating a set of estimates obtained through periodically transmitted pilot symbols.

What is pilot based channel estimation?

Pilot-based channel estimation estimates the channel information by obtaining the impulse response from all sub-carriers by pilot. Compared with blind channel estimation, which uses statistical information of the received signals, pilot-based channel estimation is a practical and an effective method.