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## Rayleigh Channel Model

This section of MATLAB source code covers rayleigh Channel Model.

There are many channel models used for simulation in wireless signal transmission technologies. The most basic channel model used by designers is Rayleigh model. In this model, only Non Line of Sight(NLOS) components are simulated between transmitter and receiver. MATLAB provides built in function by name 'rayleighchan' as explained below along with rayleigh matlab code.

The MATLAB function is as below:
chl_res=rayleighchan(Ts,Fd,Tau,PdB);
Where, Ts=sampling time of the input signal in unit of seconds
Fd= Maximum doppler shift in unit of Hz.
Tau= raw vector consisting path delays in unit of seconds
PdB= raw vector cosisting path gains in unit of dB
chl_res= channel coefficients returned by matlab function rayleighchan

%MATLAB model of 3-path rayleigh channel model
clc;
clear all;
close all;
load file_ldacstxpkt; % baseband IQ vector
Tx_Packet=Tx_Packet.';
Ts=1e-4; % sampling time in second
Fd=100; % doppler frequency in Hz
Tau=[0 1.5e-4 2.5e-4]; % delay for the three paths
PdB=[0, -2, -6]; % power in each of the three paths
pkt_allones=ones(1,480)+i*ones(1,480);
% Rayleigh channel model
h = rayleighchan(Ts, Fd, Tau, PdB);
h.StoreHistory = true;
Rx_pkt_allones = filter(h, pkt_allones);
Rx_Packet = filter(h, Tx_Packet); % passing baseband IQ vector through rayleigh channel
figure;plot(h);
figure;plot(abs(Tx_Packet)); title('baseband IQ packet without rayleigh channel');
figure;plot(abs(Rx_Packet)); title('baseband IQ packet with rayleigh channel');
figure;plot(abs(Rx_pkt_allones)); title('baseband IQ of all ones after passing through rayleigh channel');

### PLOTS

Following are the plots which depicts rayleigh channel impulse response, baseband IQ vector without channel, baseband IQ vector with channel and channel response with baseband IQ vector consiting of all ones in the packet.