# Wireless Networks

Topics: Radio, Decibel, Amplifier Pages: 2 (542 words) Published: November 4, 2012
Chapter 3 Mobile Radio Propagation: Large-Scale Path Loss
1. (a) Explain the advantages and disadvantages of the 2-ray ground reflection model in the analysis of path loss. (b) What insight does the 2-ray model provide about large-scale path loss that was disregarded when cellular systems used very large cells? 2 .In a 2-ray ground reflected model, assume that must be kept below 6.261 radians

for phase cancellation reasons. Assuming a receiver height of 2 m, and given a requirement that be less than 50 , what are the minimum allowable values for the T-R separation distance and the height of the transmitter antenna? The carrier frequency is 900 MHz. 3. In the 2-ray path loss model with ?derive an appropriate expression far the location of the signal nulls at the receiver. 4 .Compare the received power for the exact expressions for the 2-ray ground reflection model. Assume the height of the transmitter is 40 m and the height of the receiver is 3m. The frequency is 1800 MHz, and unity gain antennas are used. Plot the received. 5. Referring to Figure P3.3, compute d = d1, the first Fresnel zone distance between transmitter and receiver for a 2-ray ground reflected propagation path, in terms of and X. This is the distance at which path loss begins to transition from d to d behavior. Assume 6 .If the received power at a reference distance d0 = I km is equal to 1 microwatt, find the received powers at distances of 2 km, 5 kin, 10 km, and 20 km from the same transmitter for the following path loss models: (a) Free space; (b) n = 3; (c) n = 4; (d) 2-ray ground reflection using the exact expression; (e) extended Hata model. Assume f=1800 MHz, ht = 40m, hr = 3m, Gt=Gr=0dB. Plot each of these models on the same graph over the range of 1 km to 20km. 7 .Assume the received power at a reference distance d0 = 1 km is equal to 1 microwatt, and f=1800 MHz, ht = 40m, hr = 3m, Gt=Gr=0dB.Compute, compare, and plot the exact 2-ray ground reflection model with the approximate...