## Wireless Communication

Assignment No 1

1. Using the layer models in Figure, describe the ordering and delivery of a pizza, indicating the interactions at each level. Figure 1

2. The French and Chinese prime ministers need to come to an agreement by telephone, but neither speaks the other’s language. Further, neither has on hand a translator that can translate to the language of the other. However, both prime ministers have English translators on their staffs. Draw a diagram similar to Figure 1 to depict the situation, and describe the interaction and each level.

3. From the following figures, compute the maximum amplitude, frequency, time period and phase for each of the wave. The x-axis represents the time in sec and y-axis represents the amplitude.

4. Compute the amplitude, frequency, time period and phase for each of the following equations and also draw their respective waveforms. a. 10𝑆𝑖𝑛(2𝜋(100)𝑡) b. 20𝑆𝑖𝑛(2𝜋(30)𝑡 + 90) c. 5𝑆𝑖𝑛(500𝜋𝑡 + 180) d. 8𝑆𝑖𝑛(400𝜋𝑡 + 270)

5. Suppose that a digitized TV picture is to be transmitted from a source that uses a matrix of 480× 500 picture elements (pixels), where each pixel can take on one of 32 intensity values.

Assume that 30 pictures are sent per second. (This digital source is roughly equivalent to broadcast TV standards that have been adopted.).

a. Find the source rate R (bps). b. Assume that the TV picture is to be transmitted over a channel with 4.5-MHz bandwidth and a 35-dB signal-to-noise ratio. Find the capacity of the channel (bps).

Hint: Use Shannon’s Criteria.

6. Determine the isotropic free space loss at 4 GHz for the shortest path to a synchronous satellite from earth (35,863 km).

7. Given a signal as follows, compute the fundamental frequency, spectrum and bandwidth. Also calculate the channel capacity using Nyquest criteria using M= 2, 4, 8, where M is the number of levels. 𝑠(𝑡) = 5 sin(200𝜋𝑡) + sin(600𝜋𝑡)

8. Explain how the data rate over a channel can be increased, without increasing the bandwidth? What is the disadvantage of this approach? Hint: Nyquist Theorem

9. What is the main difference between Packet switching Virtual Circuit and Circuit Switching? Also discuss the advantages of Packet switching Virtual Circuit over Circuit Switching.

10. In a LOS communication, consider d = 40km, the requirement is to make two antennas (transmitter and receiver) such that the height of one antenna should be twice of the other. Considering this, find the appropriate heights of these two antennas.