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stdchan

Construct channel System object from set of standardized channel models

Syntax

chan = stdchan(chantype,rs,fd)

Description

example

chan = stdchan(chantype,rs,fd) constructs a fading channel object chan according to the specified chantype. chantype is chosen from the channel models listed in Supported Standards. rs is the sampling rate of the input signal and fd is the maximum Doppler shift.

Examples

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Set the sample rate and the maximum Doppler shift.

rs = 20e6;
fd = 3;

Create a CDMA Typical Urban channel model (TUx) channel object and turn on frequency response visualization.

chan = stdchan('cdmaTUx',rs,fd);
chan.Visualization = 'Frequency response';

Generate random data and apply QPSK modulation.

data = randi([0 3],10000,1);
txSig = pskmod(data,4,pi/4);

Filter the QPSK signal through the CDMA channel.

y = chan(txSig);

Create a channel model useful for GSM and EDGE simulations. Experiment with low speed and high speed conditions.

Configure parameters and System objects

Frame configuration.

M = 8; % Modulation order, 8-PSK
Rbit = 9600; % Input bit rate
Rs = Rbit / log2(M); % Symbol rate
Nsamples = 5e2; % Number of samples per frame
Nframes = 10; % Number of frames

Speed and channel configuration.

v = 10 * 1e3/3600; % Mobile speed (m/s)
fc = 1800e6; % Carrier frequency
c = physconst('LightSpeed'); % Speed of light in free space
fd = v*fc/c; % Maximum Doppler shift of diffuse component

Create System objects for modulator and channel.

modulator  = comm.PSKModulator(M,'PhaseOffset',0);

channel = stdchan('gsmeqx6',Rs,fd);
channel.RandomStream = 'mt19937ar with seed'; % set for reproducibility
channel.Visualization = 'Impulse and frequency responses';
channel.SamplesToDisplay = '100%';

refC = constellation(modulator);
constDiagram = comm.ConstellationDiagram( ...
    'ReferenceConstellation',refC, ...
    'XLimits',[-3 3],'YLimits',[-3 3]);

Simulate at low speed

for iFrames = 1:Nframes
    msg = randi([0 M-1], Nsamples, 1);
    modSignal = modulator(msg);
    chanOut = channel(modSignal);
    constDiagram(chanOut);
end

Simulate at high speed

Release and reconfigure objects.

release(constDiagram);
release(channel);

v = 120 * 1e3 / 3600; % Mobile speed (m/s)
fd = v*fc/c; % Maximum Doppler shift of diffuse component

channel.MaximumDopplerShift = fd; % Adjust maximum doppler shift

for iFrames = 1:Nframes
    msg = randi([0 M-1], Nsamples, 1);
    modSignal = modulator(msg);
    chanOut = channel(modSignal);
    constDiagram(chanOut);
end

Input Arguments

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Channel type, specified as a string or character vector. Valid options are listed in Supported Standards.

Example: stdchan('gsmRAx6c1',rs,fd), configures a channel model for the GSM typical case for rural area (RAx), 6 taps, case 1, with a sample rate rs, and maximum Doppler shift fd

Data Types: char | string

Sample rate in Hertz, specified as a scalar.

Data Types: double

Maximum Doppler shift in Hertz, specified as a scalar.

Data Types: double

Output Arguments

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Channel object, returned as a comm.RayleighChannel or comm.RicianChannel System object.

More About

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Supported Standards

For GSM, CDMA, and ITU-R HF standards, call stdchan to return a comm.RayleighChannel or comm.RicianChannel System object modeling one of these profiles.

GSM/EDGE channel models (3GPP TS 45.005 V7.9.0 (2007-2), 3GPP TS 05.05 V8.20.0 (2005-11)):

Channel modelProfile
gsmRAx6c1Typical case for rural area (RAx), 6 taps, case 1
gsmRAx4c2Typical case for rural area (RAx), 4 taps, case 2
gsmHTx12c1Typical case for hilly terrain (HTx), 12 taps, case 1
gsmHTx12c2Typical case for hilly terrain (HTx), 12 taps, case 2
gsmHTx6c1Typical case for hilly terrain (HTx), 6 taps, case 1
gsmHTx6c2Typical case for hilly terrain (HTx), 6 taps, case 2
gsmTUx12c1Typical case for urban area (TUx), 12 taps, case 1
gsmTUx12c1Typical case for urban area (TUx), 12 taps, case 2
gsmTUx6c1Typical case for urban area (TUx), 6 taps, case 1
gsmTUx6c2Typical case for urban area (TUx), 6 taps, case 2
gsmEQx6Profile for equalization test (EQx), 6 taps
gsmTIx2Typical case for very small cells (TIx), 2 taps

CDMA channel models for deployment evaluation (3GPP TR 25.943 V6.0.0 (2004-12)):

Channel modelProfile
cdmaTUxTypical Urban channel model (TUx)
cdmaRAxRural Area channel model (RAx)
cdmaHTxHilly Terrain channel model (HTx)

ITU-R HF channel models (ITU-R F.1487 (2000)) (FD must be 1 to obtain the correct frequency spreads for these models.):

Channel modelProfile
iturHFLQLow latitudes, Quiet conditions
iturHFLMLow latitudes, Moderate conditions
iturHFLDLow latitudes, Disturbed conditions
iturHFMQMedium latitudes, Quiet conditions
iturHFMMMedium latitudes, Moderate conditions
iturHFMDMedium latitudes, Disturbed conditions
iturHFMDVMedium latitudes, Disturbed conditions near vertical incidence
iturHFHQHigh latitudes, Quiet conditions
iturHFHMHigh latitudes, Moderate conditions
iturHFHDHigh latitudes, Disturbed conditions

See Also

Functions

System Objects

Introduced in R2007b