Q$1$: Two neighboring nodes $($ A and $B)$ are using a sliding$-$window protocol with $3-$bit sequence numbers. As the ARQ mechanism, GO$-$Back$-N$ is used. Assuming $A$ is transmitting, and $B$ is receiving, show the window position for the following succession of events. Hint: First find the window size

a$)$ Before A sends any frames

b$)$ After A sends frames $0,1,2,3$ and $B$ acknowledges $0,1$ and

c$)$ the ACKs are received by A

d$)$ An error occurs in frame $2.$

Q$2$: A channel has a data rate of $200kbps$ and a propagation delay of $20ms.$ Calculate, for what range of frame size does stop and wait flow control give an efficiency of $75\%.$