Final answer:
The number of positive-going zero crossings about the rms value can be determined using the formula N = 2 * V * f * T, where V is the velocity of the mobile, f is the carrier frequency, and T is the time interval.
Step-by-step explanation:
In flat Rayleigh fading, a signal experiences random amplitude variations due to multipath propagation. The number of positive-going zero crossings about the rms value can be approximated by the formula:
N = 2 * V * f * T
Where N is the number of zero crossings, V is the velocity of the mobile (in m/s), f is the carrier frequency (in Hz), and T is the time interval (in seconds).
In this case, the velocity can be converted from km/hr to m/s by multiplying by 1000/3600. The carrier frequency is given as 6 GHz, which can be represented as 6 * 10^9 Hz. The time interval is given as 5 seconds. Plugging in these values into the formula, we can calculate the number of positive-going zero crossings.