Chapter 2

1.      Explain the three basic propagation mechanisms whichimpact the propagation of signal in a mobile environment.

2.      Give complete classification of types of small-scale fading.

3.      What is large scale propagation? Explain in detail the free space propagationmodel

4.      Explain in detail the impulse response model of a multipath channel

5.      Explain in detail the types of small scale fading (including time delay andDoppler spread).

6.      Derive the expression for Feher’s upper bound.

7.      Explain (i ) The effects of multipath fading

(ii) Doppler spectrum

(iii) Multipath delay spread

8.      Derive an expression for a ground reflection model assuming distance between transmitter and receiver antenna is very large compare to heights of the antennas.

9.      Find median path loss using Okumura’s model for d=50 km hte=100 m,hre=10 m. If EIRP from base station is 1kW at 900 MHz, find receivedpower. Take Amu(900 Mhz(50 km))=43 dB and GAREA=9 dB.

10.  Compute the absolute mean path loss at d0=3m and at d=22 m for a mobile radio system operated in the 2.4-to 2.48 GHz authorized band. Assume the path loss exponent is n=3.5. Assume the first two meters are LOS, afterwards NLOS propagation should be assumed.

11.  Describe the concept of Doppler effect with relevant mathematical expressions.

12.  The received power at a distance of 100 km is 5 nw for a communication link. Determine the received power at a distance 200 km for the same link. Assume free space propagation mechanism.

13.  For the Knife-edge geometry of FIG.1 show that ʋ=α(2 d1 d2/(λ(d1+d2)))1/2 , approximately. Assume d1,d2>>h

14.  Suppose that a mobile station is moving along a straight smooth surface between base stations BS1 and BS2. The distance between BS1 and BS2 is 2000 m. Assume that the received power in dBm at Base station is given by Pr=P0- 10*n*log (d/d0), where d is the distance between mobile station and base station in meters. P0 is the power at distance d0 from the mobile. Assume that P0=0 dBm and d0=1 m. Let n denote path loss exponent which is 2.9. Given that the minimum usable level of signal is -88dBm and the mobile is currently connected to BS1, determine the hand-off margin if hand-off time is 4.5 second and the mobile speed is 100 km/hr.

15.  Explain free space propagation of radio signal.Establish the relation for thereceived power in free space. Define path loss in free space.Calculate thereceived power at a distance of 3 KM from the transmitter if the path loss exponent is 4.Assume that the transmitting power of 4 W at 1800MHz.,ashadow effect of 10.5 dB,and the path loss at a reference distance (do=100m) of -32dB.What is the allowable path loss? .