How to handle impulse response with negative delays from rayleighchan object?

Hi,

I use rayleighcan() object to create multipathdelays with the same sample frequency as input signal. To do that I call the function with the paramteters for the input signal and specific pathdelays and pathgains.

 samplingFreq =100000;
 dopplerFreq = 130;
 pathDelays = [1e-6 0 2e-6 5e-6];
 pathGains =[0, -3, -6, -9];

 fading = rayleighchan(1/samplingFreq,dopplerFreq,pathDelay,pathGains);

Now comes the problem: The pathdelays have different timings(higher frequency) than the input signal (sample frequency). Thus the rayleighchan object interpolate the impulse response of the channel to create a impulse response which matches the sampling frequency of the input signal. This new impulse response has negative delays. And here's my question: When I say I have a causal system I can just cut these neagtive PathGains, right?

Here is a normal impulse response (multipath delays have same freq. as input signal) :

and here is the IR of the raylieghchan() object with the above written parameters: