Frequency division duplex simulation - Am I correct?

Greetings community,

Im working on full FDD simulation based on OFDM. Here's the situation.

Assume that given OFDM band is divided into 2 subbands (blue band - 20 carriers - right side from DC, red band - 20 carriers - left side from DC, DC is set to NULL). User #1 is sending via blue band, and User #2 via red band. Receiving procedure are flipped (User #1 is receiving on red, and User #2 receiving on blue).

Now assume, that both of them wants to transmit almost simultaneously (with 20 samples delay).

My question is simple:

Will User #2 receive only signal from User #1 ? Or a mixed signal from User #1 and his own transmission?

Im asking because I read about self transmission cancellation techniques etc. in real world (ie. software defined radio).

Without cancellation, received signal is damaged, probably by ICI (inter channel interferences). Linking code:

 clc;
 clear all;
 close all;

 %%simulation parameters

 nfft = 128; % fft size
 band_size = 20; % band size in carrier's 

 %%transmission indices

 carrier_indices = -nfft/2:1:(nfft/2-1);

 blue_band_indices = carrier_indices(nfft/2+2:nfft/2+band_size+1) + nfft/2 + 1;
 red_band_indices = carrier_indices(nfft/2+1-band_size:nfft/2) + nfft/2 + 1;

 %%data modulation

 modulator = comm.BPSKModulator;
 data = randi([0 1], band_size, 1);
 complex_data = step(modulator, data);

 %%ofdm modulation
 % user_1 sending at blue band
 user_1_send_frame = zeros(1,nfft); % empty frame
 user_1_send_frame(blue_band_indices) = complex_data; % carrier mapping at blue band
 user_1_send_frame = ifft(fftshift(user_1_send_frame)); % time domain signal
 % user_2 sending at red band
 user_2_send_frame = zeros(1,nfft); % empty frame
 user_2_send_frame(red_band_indices) = complex_data; % carrier mapping at red band
 user_2_send_frame = ifft(fftshift(user_2_send_frame)); % time domain signal

 %%adding delay between user_1 and user_2 sending procedures

 delay = zeros(1,20);

 user_1_send_frame = [user_1_send_frame delay];
 user_2_send_frame = [delay user_2_send_frame];

 %%combining signals

 user_2_received_signal = user_1_send_frame + user_2_send_frame;

 %%user_2 trying to receive on blue band (signal send by user_1)

 user_2_receive_frame = fftshift(fft(user_2_received_signal(1:nfft))); % user_2 computing fft
 user_2_receive_frame = user_2_receive_frame(blue_band_indices);

 %%plots

 plot_frame = zeros(2,nfft);
 plot_frame(1,blue_band_indices) = 1;
 plot_frame(2,red_band_indices) = 1;

 figure(1);
 bar(plot_frame(1,:),'b');
 hold on;
 bar(plot_frame(2,:),'r');

 scatterplot(user_2_receive_frame);

Answer 1

[en2]

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