What is Papr and cyclic prefix in OFDM?

Drawbacks of OFDM are the requirement for a cyclic prefix (CP) to avoid interference between OFDM symbols and the high peak to average power ratio (PAPR). The CP causes transmission overhead and hence reduces throughput, while a high PAPR requires the use of less efficient linear amplifiers.

What is cyclic prefix in wireless communication?

In telecommunications, the term cyclic prefix refers to the prefixing of a symbol, with a repetition of the end. It provides a guard interval to eliminate intersymbol interference from the previous symbol.

How is cyclic prefix duration calculated?

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.

What is ISI and how it can be Minimised?

Countering ISI Separate symbols in time with guard periods. Apply an equalizer at the receiver, that, broadly speaking, attempts to undo the effect of the channel by applying an inverse filter.

What is the difference between cyclic prefix and guard interval?

The Guard Interval is the ratio of the Cyclic Prefix “CP1) Contention period, or 2) Cyclic prefix” time to the inverse FFT. Each symbol is transmitted for a slightly longer time, extended symbol time T(s), than the active (or useful) symbol time T(IFFT). The extra time is the guard interval.

How do you add cyclic prefix in OFDM in Matlab?

Since the channel delay is 3 symbols (CIR of length 3), we need to add atleast 2 CP symbols. Ncp = 2; \%number of symbols to copy and paste for CP s_cp = [s(end-Ncp+1:end) s]; \%copy last Ncp symbols from s and prefix it.

Why guard interval is provided in OFDM?

These transmissions may belong to different users (as in TDMA) or to the same user (as in OFDM). The purpose of the guard interval is to introduce immunity to propagation delays, echoes and reflections, to which digital data is normally very sensitive.

How do you control ISI?

Countering ISI

1. Separate symbols in time with guard periods.
2. Apply an equalizer at the receiver, that, broadly speaking, attempts to undo the effect of the channel by applying an inverse filter.

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]). -point DFT/IDFT wherever applicable.