Fading channel occurs when



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Chuyển đổi dữ liệu01.01.2022
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ĐỒ ÁN MÔN TRUYỀN THÔNG DI ĐỘNG K2018, R-REC-F.1101-0-199409-I!!MSW-E, Ho ng Th Hu , Bai-4, VNU, document tailieudaihoc

1.

2.

Determine the maximum and minimum spectral frequencies received from a stationary GSM transmitter that has a center frequency of exactly 1950.000000 MHz, assuming that the receiver is traveling at speeds of: (a) 1 km/hr; (b) 5 km/hr; (c) 100 km/hr; and (d) 1000 km/hr.



3.
Given that the coherence bandwidth is approximated by Equation (5.39), show that a flat

fading channel occurs when . Hint: Note that is an RF bandwidth, and assume

that , is the reciprocal of the baseband signal bandwidth.

4

If a particular modulation provides suitable BER performance whenever



determine the smallest symbol period , (and thus the greatest symbol rate) that may be

sent through RF channels shown in Figure P5.6, without using an equalizer.



5.

If a baseband binary message with a bit rate is modulated by an RF carrier

using BPSK, answer the following:

(a) Find the range of values required for the rms delay spread of the channel such that the

received signal is a flat-fading signal.

(b) If the modulation carrier frequency is 5.8 GHz, what is the coherence time of the channel,

assuming a vehicle speed of 30 miles per hour?

(c) For your answer in (b), is the channel "fast" or "slow" fading?

(d) Given your answer in (b), how many bits are sent while the channel appears "static"?
6

For the power delay profiles in Figure P5.6, estimate the 90% correlation and 50% correlation

coherence bandwidths.

7.

Given that the probability density function of a Rayleigh distributed envelope is given by where is the variance, show that the cumulative distribution



function is given as . Find the percentage of time that a signal is

10 dB or more below the rms value for a Rayleigh fading signal.
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