getPathFilters

Get path filter impulse response for 3-D MIMO fading channel

Syntax

pathFilters = getPathFilters(lte3d)

Description

pathFilters = getPathFilters(lte3d) returns path filter impulse responses for the 3-D multi-input/multi-output (MIMO) fading channel object specified by lte3d. You can use this information, along with the pathGains output argument returned by the channel object, to reconstruct a perfect channel estimate.

example

Examples

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Reconstruct Channel Impulse Response Using 3-D Channel Path Filters

Open Live Script

Reconstruct the channel impulse response and perform timing offset estimation using path filters of an lte3DChannel System object.

Configure a channel for delay profile CDL-B from TR 38.901 Section 7.7.1, with 1000 ns delay spread, 2 transmit antennas, and 1 receive antenna.

lte3d = lte3DChannel.makeCDL('CDL-B',1000e-9);
lte3d.Seed = 11;
lte3d.TransmitAntennaArray.Size = [1 1 2];
lte3d.ReceiveAntennaArray.Size = [1 1 1];

Create an LTE waveform for reference measurement channel (RMC) R.10 (10MHz, QPSK, R=1/3, 2 CRS ports).

rmc = lteRMCDL('R.10');
rmc.TotSubframes = 1;
data = [1; 0; 0; 1];
[txWaveform,~,txInfo] = lteRMCDLTool(rmc,data);
lte3d.SampleRate = txInfo.SamplingRate;

Pass the waveform through the channel.

[rxWaveform,pathGains] = lte3d(txWaveform);

Perform timing offset estimation using cell-specific reference signals.

corrcfg.CellRS = 'On';
offset = lteDLFrameOffset(rmc,rxWaveform,corrcfg)

offset = 
15

Obtain the path filters used in channel filtering.

pathFilters = getPathFilters(lte3d);

Reconstruct the channel impulse response using the path filters and path gains. Take the average of path gains across all time samples (first dimension). Construct the impulse response, h, for each transmit and receive antenna. Sum the responses for each transmit antenna.

[~,Np,P,R] = size(pathGains);
Nh = size(pathFilters,1);
h = zeros([Nh P R]);
pathGains = permute(mean(pathGains,1),[2 3 4 1]);
for np = 1:Np
    h = h + pathFilters(:,np) .* pathGains(np,:,:);
end
h = permute(sum(h,2),[1 3 2]);
mag = abs(h);

Plot the magnitude of the channel impulse response.

plot(mag,'o:')
title('Magnitude of Channel Impulse Response')
xlabel('Samples')
ylabel('Magnitude')

Figure contains an axes object. The axes object with title Magnitude of Channel Impulse Response, xlabel Samples, ylabel Magnitude contains an object of type line.