example_mimo.asv

这是一个关于ofdm在802.11协议下的源码

clear all;
close all;

% User-defined parameters %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Direction of connection
Connection = 'downlink';
% Distance Tx-Rx
Distance_Tx_Rx_m = 3;
% Carrier frequency
CarrierFrequency_Hz = 5.25e9;
% Power line frequency
PowerLineFrequency_Hz = 50; %? lid
% Antenna configuration at Tx
NumberOfTxAntennas = 2;
Spacing_Tx         = 1;
% Antenna configuration at Rx
NumberOfRxAntennas = 2;
Spacing_Rx         = .5;
% IEEE 802.11 case to be simulated
IEEE_802_11_Case = 'E';
% Complex field or real power correlation coefficients?
CorrelationCoefficientType = 'complex';
% Simulation length, in coherence times
SimulationLengthInCoherenceTimes = 100;
% NumberOfIterations of the vector of fading coefficients
FadingNumberOfIterations = 512;%? lid
% Sampling rate
SamplingRate_Hz = 125000;
% Factor defining the lower rate at which channel samples are collected
DownSamplingFactor = 48;
% Seed of Random Generator
RandomSeed = 0;

% Revision history
%
% February 2004   - Bug fixes
%                   o AoA/AoD at mobile hard-coded to 45 degrees
%                     Thanks to Steven Howard and Irina Medvedev, Qualcomm
%                     (USA) for reporting the bug.
%                   o Aliasing of the fluorescent effect due to a too low
%                     FadingSamplingFrequency_Hz. Channel response now
%                     interpolated in two steps, before and after
%                     the addition of the fluorescent effect, such that
%                     the highest harmonic of this effect falls within
%                     the Nyquist frequency of the fading. Thanks to
%                     Stefano Valle and Angelo Poloni, STMicroelectronics
%                     Srl, Italy for fixing this bug.
% January 2004    - Introduced PDP normalisation following a suggestion
%                   by Hemanth Sampath, Marvell. Fixed LOS component
%                   addition, with help of Steve Howard, Qualcomm.
%                   Improved initialisation of filter states to cancel
%                   transients; implementation by Stefano Valle and
%                   Angelo Poloni, STMicroelectronics Srl, Italy
%                   ( Bas Dijkstra and Laurent Schumacher )
% December 2003   - Fixed three brugs reported by Stefano Valle and
%                   Angelo Poloni, STMicroelectronics Srl, Italy
%                   ( Bas Dijkstra and Laurent Schumacher )
% November 2003   - Updated to rely on time-domain fading generation
%                   in compliance with IEEE 802.11-03/940r1
%                   Filters designed by Stefano Valle and
%                   Angelo Poloni, STMicroelectronics Srl, Italy
%                   ( Bas Dijkstra and Laurent Schumacher )
% October 2003    - Updated in compliance with IEEE 802.11-03/161r2
%                   ( Bas Dijkstra )
% February 2002   - Creation
%                   ( Laurent Schumacher )
%
%
% STANDARD DISCLAIMER
%
% The Computer Science Institute of the University of Namur (hereafter
% "FUNDP-INFO") is furnishing this item "as is". FUNDP-INFO does not
% provide any warranty of the item whatsoever, whether express,
% implied, or statutory, including, but not limited to, any warranty
% of merchantability or fitness for a particular purpose or any
% warranty that the contents of the item will be error-free.
%
% In no respect shall FUNDP-INFO incur any liability for any damages,
% including, but not limited to, direct, indirect, special, or
% consequential damages arising out of, resulting from, or any way
% connected to the use of the item, whether or not based upon
% warranty, contract, tort, or otherwise; whether or not injury was
% sustained by persons or property or otherwise; and whether or not
% loss was sustained from, or arose out of, the results of, the
% item, or any services that may be provided by FUNDP-INFO.
%
% (c) Laurent Schumacher, FUNDP-INFO - January 2004

% Hard-coded parameters %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% According to IEEE 802.11-03/0940r1

% Speed of movement of scattering environment (p. 17)
v0_kmh                    = 1.2;
% Speed of car passing by (p. 18)
v1_kmh                    = 40;
% Fluorescent effect - Mean of the Gaussian random variable (p. 29)
GaussianMean              = 0.0203;
% Fluorescent effect - Standard deviation of the Gaussian random variable (p. 29)
GaussianStandardDeviation = 0.0107;

% Filter design - Not to be changed unless the filters hard coded in init_fading_time.m
% will not fit any more

% Filter order
Filter_Order = 7;
% Normalised Doppler spread f_D
f_D_norm     = 1/300;

% Initialisation %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Random generator

if (RandomSeed ~= 0)
    randn('state',RandomSeed);
else
    randn('state',sum(100*clock));
end;
RandState = randn('state'); 

% Parameters' conversion

Wavelength_m = 3e8/CarrierFrequency_Hz;
% SpeedOfMovement_ms = SpeedOfMovement_kmh/3.6;
v0_ms        = v0_kmh/3.6;
v1_ms        = v1_kmh/3.6;
% Cut-off frequency f_D, in Hz
f_D_Hz       = v0_ms/Wavelength_m;
% Spike frequency, in Hz
f_spike_Hz   = v1_ms/Wavelength_m;

% Definition of time scales

SamplingTime_s = 1/SamplingRate_Hz;
% Fading sampling
FadingSamplingFrequency_Hz = f_D_Hz/f_D_norm;
FadingSamplingTime_s       = 1/FadingSamplingFrequency_Hz;
% Check for aliasing of the fluorescent effect
% Highest harmonic                             = 10*PowerLineFrequency_Hz
% Nyquist frequency of the first interpolation = 1/2 *(10*FadingSamplingFrequency_Hz)
if ((10*PowerLineFrequency_Hz)>(5*FadingSamplingFrequency_Hz))
    disp('Warning! Aliasing of the fluorescent effect!');
    disp('Highest harmonic falls beyond Nyquist frequency of the fading samples!');
end;
% Oversampling factor
OversamplingFactor = SamplingRate_Hz/FadingSamplingFrequency_Hz;

% Derivation of the PDP and the correlation matrices

[PDP_linear, RTx, RRx, FadingType, RiceMatrix, RiceFactor_dB, ...
        PathLoss_dB, ShadowFading_dB, DirectionOfMovement_rad, ...
        Angle_rad, sigma_rad] = ...
    IEEE_802_11_Cases(Connection, IEEE_802_11_Case, ...
                      CorrelationCoefficientType, CarrierFrequency_Hz,...
                      NumberOfTxAntennas, Spacing_Tx, NumberOfRxAntennas, ...
                      Spacing_Rx, Distance_Tx_Rx_m);
                                    
% Parameters assessment

NumberOfIterations = floor((SimulationLengthInCoherenceTimes/f_D_Hz)/(FadingNumberOfIterations*FadingSamplingTime_s));
NumberOfSamplesPerIteration = floor((FadingNumberOfIterations*FadingSamplingTime_s)/SamplingTime_s);
disp(['Simulation length: ',num2str(SimulationLengthInCoherenceTimes),' coherence times']);
disp([num2str(NumberOfIterations),' vectors of ',num2str(FadingNumberOfIterations),...
      ' fading samples generated @ ',num2str(FadingSamplingFrequency_Hz),' Hz will be used internally']);
disp(['to produce ', num2str(NumberOfIterations*NumberOfSamplesPerIteration),...
      ' interpolated samples @ ',num2str(SamplingRate_Hz),' Hz']);
disp(['Oversampling factor of the fades = ',num2str(SamplingRate_Hz),'/',num2str(FadingSamplingFrequency_Hz),' = ',...
        num2str(OversamplingFactor)]);
disp([num2str(floor(NumberOfIterations*NumberOfSamplesPerIteration/DownSamplingFactor)),' interpolated',...
      ' samples will be collected in H and stored in tmp.mat']);
disp(['Sampling frequency of H samples = ',num2str(SamplingRate_Hz),'/',...
        num2str(DownSamplingFactor),' = ',num2str(SamplingRate_Hz/DownSamplingFactor),' Hz']);
disp(' ');

% Initialisation of size variable

NumberOfPaths = size(PDP_linear,2);

% Initialisation of fading filter state

% "Dummy" call in order to fill the filter states with realistic values.
% Filters have a very long transient and steady state is achieved after
% 800-1000 filtered samples. Fading samples generated during the transient
% phase should not be used in the channel model, because their variance
% is lower than expected.
[DummyMatrix, FilterStatesOut, RandState] =  init_fading_time(1000, ...
    NumberOfTxAntennas, NumberOfRxAntennas, NumberOfPaths, FadingType, ...
    zeros(Filter_Order,NumberOfTxAntennas*NumberOfRxAntennas*NumberOfPaths), ...
    RandState);
clear DummyMatrix;

% Computation of the correlation matrices, one for each tap

[C, R] = init_MIMO_channel(RTx, RRx, CorrelationCoefficientType);

% Initialisation of the LOS component
RiceFactor_linear = 10.^(.1.*RiceFactor_dB);
RiceVectorLOS     = [];
RiceVectorNLOS    = [];

% Computation of the power delay profile of the (LOS+NLOS) power

% The PDP is defined as the time dispersion of the NLOS power. The addition
% of the LOS component modifies the time dispersion of the total power.
pdp_linear = PDP_linear(1,:).*(1+RiceFactor_linear);
% Normalisation of the power delay profile of the (LOS+NLOS) power
pdp_linear = pdp_linear./sum(pdp_linear);

clear tmp;
tmp = reshape(RiceMatrix, NumberOfTxAntennas*NumberOfRxAntennas, 1);
for (ii = 1:NumberOfPaths)
    RiceVectorLOS  = [RiceVectorLOS; ...
                      sqrt(pdp_linear(1,ii)).*sqrt(RiceFactor_linear(ii)/(RiceFactor_linear(ii)+1)).*tmp];
    RiceVectorNLOS = [RiceVectorNLOS; sqrt(1/(RiceFactor_linear(ii)+1)).*ones(NumberOfTxAntennas*NumberOfRxAntennas, 1)];
    R_index_low    = (ii-1)*(NumberOfTxAntennas*NumberOfRxAntennas)+1;
    R_index_high   = ii*NumberOfTxAntennas*NumberOfRxAntennas;
    R(R_index_low:R_index_high,R_index_low:R_index_high) = ...
        (RiceFactor_linear(ii)/(RiceFactor_linear(ii)+1)).*(tmp*tmp') ...
        + (1/(RiceFactor_linear(ii)+1)).*R(R_index_low:R_index_high,R_index_low:R_index_high);
end;

% Initialization of fluorescent effects random variables

% Random phase
Random_Phase                   = rand(1)*2*pi;
% Gaussian random variable
X                              = randn(1)*GaussianStandardDeviation + GaussianMean;
% Ratio
RandomInterfererToCarrierRatio = X^2;

% Main Loop %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

RunningTimeInstant_s                = 0;
FadingOffset_s                      = 0;
TwoLastColumnsOfOldFadingMatrixTime = [];
CorrelatedFading                    = [];
H                                   = [];

for ii = 1:NumberOfIterations;
    
    % Simulation tracking
    time = clock;
    disp([num2str(time(4)),':',num2str(time(5)),'.',num2str(floor(time(6))),...
               ' - Iteration ',num2str(ii),'/',num2str(NumberOfIterations)]);
    
    % Time references
    FadingTime_s  = FadingOffset_s-((ii~=1)*2*FadingSamplingTime_s):FadingSamplingTime_s:...
                    FadingOffset_s+((FadingNumberOfIterations-1)*FadingSamplingTime_s);
    OversampledFadingTime_s = FadingTime_s(1):.1*FadingSamplingTime_s:...
                              FadingTime_s(size(FadingTime_s,2));
    RunningTime_s = RunningTimeInstant_s:SamplingTime_s:...
                    (floor((FadingTime_s(1,size(FadingTime_s,2)))/SamplingTime_s)...
                     -(mod(FadingTime_s(1,size(FadingTime_s,2)),SamplingTime_s)==0))*SamplingTime_s;
    HSamples      = find((mod(RunningTime_s,DownSamplingFactor*SamplingTime_s)<(.1*SamplingTime_s))|...
                         (mod(RunningTime_s,DownSamplingFactor*SamplingTime_s)>((DownSamplingFactor-.1)*SamplingTime_s)));
    
    % Computation of the matrix of fading coefficients    
    [NewFadingMatrixTime, FilterStatesOut, RandState] = init_fading_time(FadingNumberOfIterations, ...
        NumberOfTxAntennas, NumberOfRxAntennas, NumberOfPaths, FadingType, ...
        FilterStatesOut, RandState);
    FadingMatrixTime                    = [TwoLastColumnsOfOldFadingMatrixTime, NewFadingMatrixTime];
    TwoLastColumnsOfOldFadingMatrixTime = NewFadingMatrixTime(:,FadingNumberOfIterations-1:FadingNumberOfIterations);

    % Spatial correlation of the fading matrix
    FadingMatrixTime = C * FadingMatrixTime;
    
    % Initalisation of normalisation diagonal matrix
    pdp_coef = [];
    for jj = 1:size(pdp_linear,2)
        pdp_coef = [pdp_coef, sqrt(pdp_linear(1,jj)).*ones(1,size(FadingMatrixTime,1)/size(pdp_linear,2))];
    end;
    
    % Normalisation of the correlated fading processes
    FadingMatrixTime = diag(pdp_coef)*FadingMatrixTime;
    
    % Calculation of the Rice phasor
    % AoA/AoD hard-coded to 45 degrees
    RicePhasor = exp(j.*2.*pi.*f_D_Hz.*cos(pi/4).*FadingTime_s);
    
    % Addition of the Rice component
    FadingMatrixTime = (RiceVectorLOS*RicePhasor)+(RiceVectorNLOS*ones(1,size(FadingMatrixTime,2))).*FadingMatrixTime;

    % First (partial) interpolation, at 10*FadingSamplingFrequency_Hz
    % to avoid aliasing of the fluorescent effect
    OversampledFadingMatrixTime = (interp1(FadingTime_s.',FadingMatrixTime.',OversampledFadingTime_s.','linear')).';

    % Call to generate fluorescent light effects in models D and E
    if (IEEE_802_11_Case == 'D' | IEEE_802_11_Case == 'E')
        OversampledFadingMatrixTime = add_fluorescent_effects(OversampledFadingMatrixTime, IEEE_802_11_Case, ...
                                      PowerLineFrequency_Hz, NumberOfTxAntennas, NumberOfRxAntennas, ...
                                      OversampledFadingTime_s, RandomInterfererToCarrierRatio, Random_Phase);
    end;
    
    % Large-scale fading
    OversampledFadingMatrixTime = OversampledFadingMatrixTime./sqrt(10.^(.1*(PathLoss_dB+ShadowFading_dB)));

    % Second interpolation, at SamplingRate_Hz
    CorrelatedFading = (interp1(OversampledFadingTime_s.',OversampledFadingMatrixTime.',RunningTime_s.','linear')).';
    H                = [H, CorrelatedFading(:,HSamples)];
    
    % Update of book-keeping variables
    FadingOffset_s       = FadingTime_s(size(FadingTime_s,2))+FadingSamplingTime_s;
    RunningTimeInstant_s = RunningTime_s(1,size(RunningTime_s,2))+SamplingTime_s;
end;

temp_H = H;
clear H;
NumberOfHSamples = size(temp_H,2);
H = zeros(NumberOfTxAntennas,NumberOfRxAntennas,NumberOfPaths,NumberOfHSamples);
for ii = 1:size(temp_H,2)
    for jj = 1:NumberOfPaths
        for kk = 1:NumberOfRxAntennas
            for ll = 1:NumberOfTxAntennas
                 H(ll,kk,jj,ii) = temp_H(((jj-1)*NumberOfTxAntennas+(ll-1))*NumberOfRxAntennas+kk, ii);
             end;
        end;
    end;
end;
save tmp H;

% Validation of MIMO channel %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

plot_MIMO;