The Cyclic Prefix for OFDM¶
In a previous post, we have elaborated about the building blocks of OFDM.
There, we have stated two benefits of using a cyclic prefix between subsequent OFDM symbols:
- The CP isolates different OFDM blocks from each other when the wireless channel contains multiple paths, i.e. is frequency-selective.
- The CP turns the linear convolution with the channel into a circular convolution. Only with a circular convolution, we can use the single-tap equalization OFDM is so famous for.
In the following, we will elaborate on these two aspects. First, let us define some parameters for our OFDM system:
N = 128 # OFDM block length (i.e. subcarrier count)
NCP = 32 # Length of OFDM CP
ofdm1 = np.arange(N) # generate some arbitrary signal for one OFDM block
ofdm2 = 2* ...