How does MATLAB structure the path gain matrix that the step function outputs for the LTEMIMO object?

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Nikolai 2013-8-1

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评论： hussain ali 2013-12-13

I am developing a sphere decoder for a MIMO-CDMA communication system. In order for it to operate correctly the channel must be represented as a matrix. MATLAB outputs a vector of path gains corresponding to each discreet path for each Nt-Nr link. Is there any way to align the vectors (path gains) so that the filtering operation performed by the step function may be represented by a single matrix multiplication:

Y = HX,

where H channel, x is the input and y is the output?

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Answer 1

Yue Shang 2013-9-11

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You have the Y = HX format only when the channel is static and has one discrete path. Here is an example:

>> hChan = comm.MIMOChannel('MaximumDopplerShift', 0, 'PathGainsOutputPort', true);

>> X = rand(10, 2);

>> [Y, H] = step(hChan, X);

>> disp(Y - X*squeeze(H(1,1,:,:))) % Verify Y = X*H

The H is a 10x1x2x2 array, but it repeats along the first dimension (time domain) because the channel is static (MaximumDopplerShift property is 0).

For comm.LTEMIMOChannel, you may not be able to do this because all the channel profiles have a non-zero Doppler shift. You can try to configure an equivalent comm.MIMOChannel to model LTE in this case.