1Kb = 1 * 1024 * 8 bits = 8192 Bits
SWS (Sender Window Size) = 1+2a or Number of bits in transmission channel (RTT * bandwidth )
Using second
RTT = transmission time + 2* propgaiton delay
= 8192 / 3 * 10^9 + 8192 / 60 * 10^6 + 2* ( 5* 10^5/ 2*10^8 + 15*10^3/2*10^8)
= 5.29 ms
FIber Optic Velocity ~ 2 * 10^8. ~ 75-80%
SWS = RTT * Bandiwidth ( Taking Min(3Gbps, 50Mbps) )
= 5.29 * 60Mbps = 31.74
~~ 32 Packets.