$2$A$)$ A CRC is constructed to generate a $4-$bit FCS for a $10-$bit message. The generator polynomial is $x^4+x2+x+1.$ Draw the shift register circuit and encode the data bit sequence $1101100110$ and give the codeword.

$2$B$)$ A channel has a data rate of $6$ kbps and a propagation time of $40$ ms $.$ Identify range of frame sizes does stop$-$and$-$wait give a line efficiency of at least $50\%?$

$2$C$)$ The bipolar$-$AMI waveform representing the binary sequence $0100101011$ is transmitted over a noisy channel. The received waveform is shown in Figure Q$2$C it contains a single error. Locate the