Two station communicate via 1Mbps Network links with a propagation delay of 27 msec. the network serves meraly to re transmit data receive from one station to another with negligible switching delay. Data is transmitted between two stations using HDLC frames of 1000 bits

a) Determind the Minimum window size which allows optimum troughout

b) When apply goback N ARQ system with 3bits is sequence and 936bits in each frame

i. Find utlization U and throughput obtained on link has free error

ii. Find utlization U and throughput obtained on link has BER=0.001