Ofdm circular convolution

1. Why CP is added in OFDM?
2. Why is cyclic prefix required in OFDM?
3. How do you find the length of the cyclic prefix in OFDM?
4. How the addition of cyclic prefix converts linear convolution to circular convolution?

Why CP is added in OFDM?

To combat the intersymbol interference (ISI) in a multipath channel, a cyclic prefix (CP) is inserted in the OFDM symbol. The CP refers to the cyclic extension of an OFDM symbol, that is, appending the last samples of the OFDM symbol to the front of the symbol as illustrated in Fig. 5.6.

Why is cyclic prefix required in OFDM?

Why is a cyclic prefix required in an OFDMA? Explanation: Use of cyclic prefix is a key element of enabling the OFDM signal to operate reliably. The cyclic prefix acts as a buffer region or guard interval to protect the OFDM signals from intersymbol interference.

How do you find the length of the cyclic prefix in OFDM?

Therefore, the number of samples allocated for cyclic prefix can be calculated as Ncp=Tcp*N/T, where N is the FFT/IFFT length, T is the IFFT/FFT period and Tcp is the duration of cyclic prefix.

How the addition of cyclic prefix converts linear convolution to circular convolution?

The linear convolution can be converted into circular convolution by adding Cyclic Prefix (CP) in the OFDM architecture. The addition of CP makes the linear convolution imparted by the channel appear as circular convolution to the DFT process at the receiver (Reference [1]).