Band-limitation effect on statistical properties of class-A interference

The effect of band limitation on the statistical properties of Middleton's class A noise model is investigated. It is found that a uniformly weighted sum of statistically independent and identically distributed class A random variables becomes a new class A random variable with reduced impulsiveness. It is also found that bandlimited noise becomes class A noise if the impulse response of the filter has a rectangular envelope waveform. Since matched filters employed by DS-SS (direct sequence spread spectrum) or OFDM (orthogonal frequency division multiplex) systems usually satisfy the above condition, the results can be widely applied to the evaluation of the error probability of signal detection in such communication systems subjected to class A interference.