Reconstruct Channel Impulse Response Using CDL Channel Path Filters

Reconstruct the channel impulse response and perform timing offset estimation using path filters of a Clustered Delay Line (CDL) channel model with delay profile CDL-D from TR 38.901 Section 7.7.1.

Define the channel configuration structure using annrCDLChannelSystem object. Use delay profile CDL-D, a delay spread of 10 ns, and UT velocity of 15 km/h:

v = 15.0;% UT velocity in km/hfc = 4e9;% carrier frequency in Hzc = physconst('lightspeed');% speed of light in m/sfd = (v*1000/3600)/c*fc;% UT max Doppler frequency in Hzcdl = nrCDLChannel; cdl.DelayProfile ='CDL-D'; cdl.DelaySpread = 10e-9; cdl.CarrierFrequency = fc; cdl.MaximumDopplerShift = fd;

配置传输数组(M N P毫克Ng) = (22 2 1 1], representing 1 panel (Mg=1, Ng=1) with a 2-by-2 antenna array (M=2, N=2) and P=2 polarization angles. Configure the receive antenna array as [M N P Mg Ng] = [1 1 2 1 1], representing a single pair of cross-polarized co-located antennas.

cdl.TransmitAntennaArray.Size = [2 2 2 1 1]; cdl.ReceiveAntennaArray.Size = [1 1 2 1 1];

Create a random waveform of 1 subframe duration with 8 antennas.

SR = 15.36e6; T = SR * 1e-3; cdl.SampleRate = SR; cdlinfo = info(cdl); Nt = cdlinfo.NumTransmitAntennas; txWaveform = complex(randn(T,Nt),randn(T,Nt));

Transmit the input waveform through the channel.

[rxWaveform,pathGains] = cdl(txWaveform);

Obtain the path filters used in channel filtering.

pathFilters = getPathFilters(cdl);

Perform timing offset estimation usingnrPerfectTimingEstmate.

[offset,mag] = nrPerfectTimingEstimate(pathGains,pathFilters);

Plot the magnitude of the channel impulse response.

[Nh,Nr] = size(mag); plot(0:(Nh-1),mag,'o:'); holdon; plot([offset offset],[0 max(mag(:))*1.25],'k:','LineWidth',2); axis([0 Nh-1 0 max(mag(:))*1.25]); legends ="|h|, antenna "+ num2cell(1:Nr); legend([legends"Timing offset estimate"]); ylabel('|h|'); xlabel('Channel impulse response samples');

See Also

Functions

• nrPerfectTimingEstimate