root/ResearchApps/PHY/WARPLAB/WARPLab_SISO_MIMO2x2/M_Code/warplab_siso_example_ChannelEstim.m

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Using Warplab (SISO configuration) to Estimate the Amplitude and Phase of
% a Narrowband Flat Fading Wireless Channel 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% To run this code the boards must be programmed with the
% warplab_siso_v02.bit bitstream

% The specific steps implemented in this script are the following:

% 0. Transmit a narrowband signal using Warplab 
% 1. Remove from the received vector the samples that do not correspond to 
% transmitted data.
% 2. Compute the amplitude and the phase of the transmitted and received 
% sammples
% 3. Compute the channel amplitude and channel phase per sample

% Note: The amplitude and phase computed in this exercise correspond to the
% amplitude and phase of the channel together with the amplitude and phase 
% of the hardware. In other words, the effect of the radios (like gains and
% carrier frequency offset)is also part of the channel.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 0. Transmit a narrowband signal using warplab
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Follow the steps for transmission and reception of data using Warplab.
% These are the steps in the matlab script warplab_example_TxRx.m

% This example transmits the following narrowband signal
% t = 0:(1/40e6):TxLength/40e6 - 1/40e6; 
% TxData = exp(t*j*2*pi*1e6); 

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 0.0. Initializaton and definition of parameters
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%Load some global definitions (packet types, etc.)
warplab_defines

% Create Socket handles and intialize nodes
[socketHandles, packetNum] = warplab_initialize;

%Separate the socket handles for easier access
% The first socket handle is always the magic SYNC
% The rest can be arranged in any combination of Tx and Rx
udp_Sync = socketHandles(1);
udp_Tx = socketHandles(2);
udp_RxA = socketHandles(3);

% Define the warplab options (parameters)
CaptOffset = 1000; %Number of noise samples per Rx capture. In [0:2^14]
TxLength = 2^14-1000; %Length of transmission. In [0:2^14-CaptOffset]
TransMode = 0; %Transmission mode. In [0:1] 
               % 0: Single Transmission 
               % 1: Continuous Transmission. Tx board will continue 
               % transmitting the vector of samples until the user manually
               % disables the transmitter. 
CarrierChannel = 8; % Channel in the 2.4 GHz band. In [1:14]
TxGainBB = 3; %Tx Baseband Gain. In [0:3]
TxGainRF = 40; %Tx RF Gain. In [0:63]
RxGainBB = 15; %Rx Baseband Gain. In [0:31]
RxGainRF = 1; %Rx RF Gain. In [1:3]

% Define the options vector; the order of options is set by the FPGA's code
% (C code)
optionsVector = [CaptOffset TxLength-1 TransMode CarrierChannel (RxGainBB + RxGainRF*2^16) (TxGainRF + TxGainBB*2^16)]; 
% Send options vector to the nodes
warplab_setOptions(socketHandles,optionsVector);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 0.1. Generate a vector of samples to transmit and send the samples to the 
% Warp board (Sample Frequency is 40MHz)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Prepare some data to be transmitted
t = 0:(1/40e6):TxLength/40e6 - 1/40e6; %Create time vector.
TxData = exp(t*j*2*pi*1e6); % Create a signal to transmit. Signal must be a
% row vector. The signal can be real or complex, the only constraint is
% that the amplitude of the real part must be in [-1:1] and the amplitude 
% of the imaginary part must be in [-1:1]

% Download the samples to be transmitted
warplab_writeSMWO(udp_Tx, TxData, RADIO2_TXDATA);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 0.2. Prepare boards for transmission and reception and send trigger to 
% start transmission and reception (trigger is the SYNC packet)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Enable transmitter radio path in transmitter node
warplab_sendCmd(udp_Tx, RADIO2_TXEN, packetNum);

% Enable receiver radio path in receiver node
warplab_sendCmd(udp_RxA, RADIO2_RXEN, packetNum);

% Prime transmitter state machine in transmitter node. Transmitter will be 
% waiting for the SYNC packet. Transmission will be triggered when the 
% transmitter node receives the SYNC packet.
warplab_sendCmd(udp_Tx, TX_START, packetNum);

% Prime receiver state machine in receiver node. Receiver will be waiting 
% for the SYNC packet. Capture will be triggered when the receiver 
% node receives the SYNC packet.
warplab_sendCmd(udp_RxA, RX_START, packetNum);

% Send the SYNC packet
warplab_sendSync(udp_Sync);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 0.3. Read the received smaples from the Warp board
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Read back the received samples
[RawRxData] = warplab_readSMRO(udp_RxA, RADIO2_RXDATA, TxLength+CaptOffset);
% Process the received samples to obtain meaningful data
[RxData,RxOTR] = warplab_processRawRxData(RawRxData);
% Read stored RSSI data
[RawRSSIData] = warplab_readSMRO(udp_RxA, RADIO2_RSSIDATA, (TxLength+CaptOffset)/8);
% Procecss Raw RSSI data to obtain meningful RSSI values
[RxRSSI] = warplab_processRawRSSIData(RawRSSIData);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 0.4. Reset and disable the boards
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Reset the receiver
warplab_sendCmd(udp_RxA, RX_DONEREADING, packetNum);

% Disable the receiver radio
warplab_sendCmd(udp_RxA, RADIO2_RXDIS, packetNum);

% Disable the transmitter radio
warplab_sendCmd(udp_Tx, RADIO2_TXDIS, packetNum);

% Close sockets
pnet('closeall');

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 0.5. Plot the transmitted and received data
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
figure;
subplot(2,2,1);
plot(real(TxData));
title('Tx I');
xlabel('n (samples)'); ylabel('Amplitude');
axis([0 2^14 -1 1]); % Set axis ranges.
subplot(2,2,2);
plot(imag(TxData));
title('Tx Q');
xlabel('n (samples)'); ylabel('Amplitude');
axis([0 2^14 -1 1]); % Set axis ranges.
subplot(2,2,3);
plot(real(RxData));
title('Rx I');
xlabel('n (samples)'); ylabel('Amplitude');
axis([0 2^14 -1 1]); % Set axis ranges.
subplot(2,2,4);
plot(imag(RxData));
title('Rx Q');
xlabel('n (samples)'); ylabel('Amplitude');
axis([0 2^14 -1 1]); % Set axis ranges.


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 1. Remove from the received vector the samples that do not correspond to 
% transmitted data. In other words, remove from the received vector samples
% 1 to CaptOffset. This step will remove samples that correspond to measured
% noise and make the RxData vector the same length as the TxData vector
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
RxData = RxData(CaptOffset+1:end);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 2. Compute the amplitude and the phase of the transmitted and received 
% sammples
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Compute the magnitude per sample of the transmitted and received
% data
mag_TxData = abs(TxData);
mag_RxData = abs(RxData);

% Compute the phase per sample of the transmitted and received data
phase_TxData = angle(TxData);
phase_TxData_unw = unwrap(phase_TxData);
phase_TxData = phase_TxData *180/pi; %Convert to degrees
phase_TxData_unw = phase_TxData_unw *180/pi; %Convert to degrees
phase_RxData = angle(RxData);
phase_RxData_unw = unwrap(phase_RxData);
phase_RxData = phase_RxData *180/pi; %Convert to degrees
phase_RxData_unw = phase_RxData_unw *180/pi; %Convert to degrees

% Plot magnitude and phase of transmitted and received samples
figure;
subplot(2,3,1);
plot(mag_TxData);
title('Tx Magnitude');
xlabel('n (samples)'); ylabel('Amplitude');
subplot(2,3,2);
plot(phase_TxData);
title('Tx Phase');
xlabel('n (samples)'); ylabel('Degrees');
subplot(2,3,3);
plot(phase_TxData_unw);
title('Tx Phase unwrapped');
xlabel('n (samples)'); ylabel('Degrees');
subplot(2,3,4);
plot(mag_RxData);
title('Rx Magnitude');
xlabel('n (samples)'); ylabel('Amplitude');
subplot(2,3,5);
plot(phase_RxData);
title('Rx Phase');
xlabel('n (samples)'); ylabel('Degrees');
subplot(2,3,6);
plot(phase_RxData_unw);
title('Rx Phase unwrapped');
xlabel('n (samples)'); ylabel('Degrees');


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 3. Compute the channel amplitude and channel phase per sample
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Compute the channel amplitude
channel_amplitude = mag_RxData./mag_TxData;

% Compute the channel phase 
channel_phase = phase_RxData_unw - phase_TxData_unw;

% Plot channel amplitude and phase
figure
subplot(2,1,1)
plot(channel_amplitude)
title('Channel Amplitude per sample');
xlabel('n (samples)'); ylabel('Amplitude');
subplot(2,1,2)
plot(channel_phase)
title('Channel Phase per sample');
xlabel('n (samples)'); ylabel('Degrees');