1. A GPS transmitter is 19 800 km above the surface of the Earth and is transmitting at a power of 45 W. Calculate the received power (in Watts per square metre) of a GPS receiver on the surface of the Earth.

 

2. A wireless network offers a maximum data rate of 1.2 Gbps. If a 12 MB file is compressed using a compression ratio of 3, and a throughput of 60% can be achieved, calculate the time taken to transmit the file over the wireless network. (Assume there are no other transmissions occurring at the same time, no error control is being used, and that file size is a multiple of 2 in your calculation).

 2a. What would be the effect on the data rate, and therefore your answer to point(2), if the transmission in point(2) assumed the use of 64-QAM but this was changed to 1024-QAM?

 2b. Give one other way of reducing the time taken to transmit the file in point (2)