Sample time in convolution
It is right to perform the convolution between two signals with diffrent sample times?


No, aside from a very few special use cases (if you have to ask, not yours), you need to resample either of them so that both are at the same sample rate.

Also notice that sampling a channel impulse response at 8 Hz only gives you information about these 8 Hz (or 4 Hz, depending on whether this is real direct sampling or a sampled equivalent complex baseband representation of the channel). You're trying to apply it to a 100 Hz (or 200 Hz, depending...) wide channel: that won't give you anything useful, even if you resampled. Your channel impulse response measurement simply isn't sufficient.