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Analysis of 16QAM miceowave link

A single hop microwave line of sight link transmits a 16-QAM signal in clear air conditions at a bit rate of 40 Mbps. The transmitter and receiver have ideal RRC filters with Ã?± = 0.5. The receiver has an implementation margin of 1.0 dB.

a. What is the symbol rate and what is the bandwidth occupied by the 16-QAM signal?

b. The link must maintain a BER no higher than 10^-6. What is the minimum CNR in the receiver to meet this requirement?

c. When rain causes attenuation on the link the BER will eventually increase to 10^-6. The modulation at the transmitter automatically changes to QPSK, and the bit rate is reduced. What is the new bit rate on the link.

d. How much additional rain attenuation can occur when the link is using QPSK modulation, compared to 16-QAM?

Solution Preview

A single hop microwave line of sight link transmits a 16-QAM signal in clear air conditions at a bit rate of 40 Mbps. The transmitter and receiver have ideal RRC filters with Rolloff = 0.5. The receiver ...

Solution Summary

A single hop microwave line of sight link transmits a 16-QAM signal in clear air conditions at a bit rate of 40 Mbps. The transmitter and receiver have ideal RRC filters with Rolloff = 0.5. The receiver has an implementation margin of 1.0 dB.

The following are addressed to find

a. What is the symbol rate and what is the bandwidth occupied by the 16-QAM signal?

b. The link must maintain a BER no higher than 10^-6. What is the minimum CNR in the receiver to meet this requirement?

c. When rain causes attenuation on the link the BER will eventually increase to 10^-6. The modulation at the transmitter automatically changes to QPSK, and the bit rate is reduced. What is the new bit rate on the link.

d. How much additional rain attenuation can occur when the link is using QPSK modulation, compared to 16-QAM?

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