onsider a bidirectional link that uses Selective Repeat ARQ with a window size of N $=7.$ Suppose that all frames are one unit long and use a time$-$out value of $2.$ Assume that the one$-$way propagation delay is $0\mathrm{.}5$ time unit, the processing times are negligible, and the ACK transmission time is one unit long. Assuming station A and B begin with their sequence numbers set to zero, show the pattern of transmissions and associated state transitions $($and sequence numbers$)$ for the following sequences of events.

a$)$ Station A sends $8$ frames in a row, starting at t $=0.$ All frames are received correctly.

b$)$ Station A sends $8$ frame in a row, starting at t $=0.$ All frames are received correctly, except frame $3$ is lost.