Question

Problem 2.13 A wireless channel has impulse response given by h(t) 2t 0.1) +j8(t 0.64)-0.86(t-2.2), where the unit of time is in microseconds (a) What is the delay spread and coherence bandwidth? (b) Plot the magnitude and phase of the channel transfer function H(f) over the interval -2Be,2Be], where Be denotes the coherence bandwidth computed in (a). Comment on how the phase behaves when H(f) is small. (c) Express | H(f)l in dB, taking 0 dB as the gain of a nominal channel hnom(t) 26(t-0.1) corresponding to the first ray alone. What are the fading depths that you see with respect to this nominal? Define the average channel power gain over a band -W/2, W/2] as W/2 This is a simplified measure of how increasing signal bandwidth W can help compensate for frequency-selective fading: we hope that, as W gets large, we can average out fluctuations in IH(f)1.

Answer 1

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