Please solve both 'A' and 'B' part

4 a) Two stations A and B use Go-Back-N ARQ mechanism with 3 bit. sequence number and sender's window size of 4. Assume station A is transmitting and station B is receiving, show (by drawing) the sender's window position for the following succession of events: (i) At the beginning, before station A sends any frame (ii) After station A sends frame 0, 1, 2 and 3 and receives acknowledgement from B for 0 and 1. (iii) After station A sends frames 4 and 5 and receives acknowledgement for frame 4 (i.e. RR 5). (iv) After station A sends frames 6 and 7 but no acknowledgment is yet being received b) Consider HDLC protocol with the value of (8 - bit) control field as 01100100. Find the following: (i) Type of frame (ii) Sequence number of sender (iii) Sequence number of receiver (iv) Till which frame number receiver has received frames successfully