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ECS528U - Communications Systems - 2025/26

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A digital communication systems is using an -ary NRZ bipolar encoding between and .

Estimate the value of when M=4 and the SER is 0.01.

Chose the answer closer to value that you obtained

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In the context of Multi-level Unipolar NRZ with , what we can say about the SER at the limit when  ?

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Considering a Binary Symmetric (BSC) channel with associated probability , how much is the probability that a bit transmitted as 0 is received as 1?

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We are transmitting by using a bipolar NRZ where a value of -1 Volts is associated to the bit 0, while a value of 1.5 Volts is associated to the bit 1. Assuming that the probability of having a bit 0 and that the probability of having a bit 1 , evaluate the average energy per bit when 1Khz.

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Imagine to have a bitstream in baseband encoded using a unipolar NRZ where the bit 0 is encoded with 0 Volts and the Bit 1 with a generic value V. 

Assuming that the channel is affected by AWGN noise with a generic value , are there any other types of encoding that permits to keep the exact same BER but with lower energy per bit ?   

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Imagine that your system is using a bipolar NRZ encoding where the pulses can span between and volts. If we use a -ary encoding with and , How much is the BER?

Hint: You need the Q-function for the BER and NOT SER. 

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Consider a unipolar NRZ which transmits transmits 1’s and 0’s with equal probability. Logic 1’s are represented by a 5 volt level, while logic 0’s are represented by a 0 volt level. What is the mean energy per bit if the bitrate is 1kbps? Is it:

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Which of the following encoding represents the Fibonacci encoding for the number 42

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In the case of -ary unipolar NRZ with M=4 and maximum value of voltage V=1 Volts, calculate the energy per symbol in the case the symbol Rate . In this case assume the following Probabilities for the symbols:

  • Pr(00) = 0.4
  • Pr(01) = 0.1
  • Pr(11) = 0.1
  • Pr(10) = 0.4

The symbols are encoded using the gray coding as follows:

  • 00 is associate with 0 volts;
  • 01 is associated with Volts;
  • 11 is associated with Volts;
  • 10 is associated with Volts;
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Evaluate the entropy of these symbols with the following probabilities and codes:

P(A)=0.3 code=11, P(B)=0.3 code=10, P(C)=0.3 code=01, P(D)=0.1 code=00

Is it (approximately):

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