CODEWITHSUNDEEP
matlabusrp
SAM
SAM

Reputation: 53

MATLAB signal up conversion and transmitting over the air

I have created an OFDM signal (WLAN) in MATLAB and saved the complex valued signal in a file. I then transfer the file to USRP-B210 (Software Defined Radio) and transmit over the air. Note that in MATLAB, I do not require to up-convert the signal to IF(intermediate frequency), as it is done by the radio device itself.

The signal is received by the receiver (which down-converts) and saves the file in local disk. I then process the receive file in MATLAB. Everything works perfect, and data is decoded correctly.

Now, I want to apply a Rayleigh Channel (that has Delay-Doppler effect over multipath channel). MATLAB has built in function for that Fading Channel. In such case, my signal transfer works fine with minor degradation in performance (BER). But degrades as I increase Delay-Doppler effect.

My question is, while I use the channel model, I am not doing any upconversion of the baseband signal before passing it to the channel model function. Was that necessary ? Because applying channel model on the base band sounds incorrect. In that case what other options do I have ?

Upvotes: 0

Views: 354

Answers (1)

GrapefruitIsAwesome
GrapefruitIsAwesome

Reputation: 488

I am not super familiar with this toolbox from MATLAB, but a quick look at the help page for comm.RayleighChannel doesn't seem to show any inputs that are carrier frequency based. This would imply that the channel model is carrier independent. As such, it should be able to be applied to a complex baseband signal just as readily as to an upconverted pass-band signal.

rayChan = 
  comm.RayleighChannel with properties:

             SampleRate: 100000
             PathDelays: 0
       AveragePathGains: 0
     NormalizePathGains: true
    MaximumDopplerShift: 130
        DopplerSpectrum: [1x1 struct]
       ChannelFiltering: true
    PathGainsOutputPort: false

Upvotes: 1

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