$4$A$)$ Compute the minimum number of bits required for the sequence number field to achieve $100\%$

utilization for the following scenario. Consider a $128103$ bits$/$sec satellite communication link with

one way propagation delay of $150$ msec $.$ Selective Retransmission $($repeat$)$ protocol is used on this

link to send data with a frame size of $1$ KB $.$ Neglect the transmission time of acknowledgement.

$4$B$)$ A group of N stations share $100$ Kbps slotted ALOHA channel. Each station output a $500$ bits frame

on an average of $5000$ ms even if previous one has not been sent. Compute the required value of

N $.$

$4$C$)$ Compute the appropriate bit rate and signal level for a channel with a $1$ Mhz bandwidth and has the

SNR value as $63$ db $.$