A BPAM system uses the modified duobinary pulse and amplitude levels of +1 and -1 to represent bits ‘1’ and ‘0’ respectively. No precoding is applied to the bits prior to transmission. The MF output sequence at the receiver is as follows:
1.9 1.8 -0.1 0.1 -0.1 -0.1
Draw the transmitted and received signal constellations. Mark the decision threshold, decision regions and clearly state the decision rule for symbol by symbol detection. Perform symbol by symbol detection and mark detection errors for the following MF output sequence.
Derive state and trellis diagrams representing the MF output based on system memory.
At a certain phase of MLSD using the Viterbi algorithm find the metrics of all states in the trellis is 1, calculate the states’ metrics for the next decoding step if the incoming MF sample is 0.4.
d. Would MLSD perform better than symbol by symbol detection for the received MF sequence given in Section b.? Explain your answer.