Path Loss/RF Power/Bit Rates

A microwave line of sight link transmits a 10.0 GHz signal a distance of 25 km across a river estuary. The transmitter delivers 2 W to the transmitting antenna. The antennas at each end of the link have a gain of 36 dB. The receiver has a noise bandwidth of 20 MHz with rms noise power of -120.0 dBW. The transmitter and receiver have ideal RRC filters with ? = 0.25. The receiver has an implementation margin of 2.0 dB.

a. Calculate the path loss for this link in dB.

b. Calculate the RF power at the input to the receiver in dBW and the CNR in dB. Ignore any losses on the link.

c. How many bits are transmitted by each symbol in a 256 QAM signal?
What is the bit rate of the 256-QAM signal?

d. The river estuary is tidal causing the surface level of the water to rise and fall. At certain times of day, reflections from the water surface cause deep fading of the received signal. The modulation at the transmitter is changed to QPSK in deep fades. What is the new bit rate on the link?

e. State two ways in which the effect of multipath fading can be reduced on this link. Explain how each of the methods can reduce the depth of fading caused by multipath.