stdchan

Construct channel System object from set of standardized channel models

Syntax

chan = stdchan(chantype,rs,fd)

Description

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

Filter Signal Through CDMA Channel

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);

GSM and EDGE Channel Model

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

chantype — Channel type

string | character vector

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

rs — Sample rate

scalar

Sample rate in Hertz, specified as a scalar.

Data Types: double

fd — Maximum Doppler shift

scalar

Maximum Doppler shift in Hertz, specified as a scalar.

Data Types: double

Output Arguments

chan — Channel object

System object™

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

More About

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 model	Profile
gsmRAx6c1	Typical case for rural area (RAx), 6 taps, case 1
gsmRAx4c2	Typical case for rural area (RAx), 4 taps, case 2
gsmHTx12c1	Typical case for hilly terrain (HTx), 12 taps, case 1
gsmHTx12c2	Typical case for hilly terrain (HTx), 12 taps, case 2
gsmHTx6c1	Typical case for hilly terrain (HTx), 6 taps, case 1
gsmHTx6c2	Typical case for hilly terrain (HTx), 6 taps, case 2
gsmTUx12c1	Typical case for urban area (TUx), 12 taps, case 1
gsmTUx12c1	Typical case for urban area (TUx), 12 taps, case 2
gsmTUx6c1	Typical case for urban area (TUx), 6 taps, case 1
gsmTUx6c2	Typical case for urban area (TUx), 6 taps, case 2
gsmEQx6	Profile for equalization test (EQx), 6 taps
gsmTIx2	Typical case for very small cells (TIx), 2 taps

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

Channel model	Profile
cdmaTUx	Typical Urban channel model (TUx)
cdmaRAx	Rural Area channel model (RAx)
cdmaHTx	Hilly 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 model	Profile
iturHFLQ	Low latitudes, Quiet conditions
iturHFLM	Low latitudes, Moderate conditions
iturHFLD	Low latitudes, Disturbed conditions
iturHFMQ	Medium latitudes, Quiet conditions
iturHFMM	Medium latitudes, Moderate conditions
iturHFMD	Medium latitudes, Disturbed conditions
iturHFMDV	Medium latitudes, Disturbed conditions near vertical incidence
iturHFHQ	High latitudes, Quiet conditions
iturHFHM	High latitudes, Moderate conditions
iturHFHD	High latitudes, Disturbed conditions