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Pipelining:
- Assumption was that trans. time is negligible
- Eg. 50Kbps channel, 500ms round trip propagation delay. Send 1000bit frames. t=0 ms the first fame is sent. t=270ms is when frame fully arrives at receiver and only at t = 520ms has the ack arrived back at the sender.
- Sender was blocked 500/520 or 96% of time.
- Solution: Choose w frames before blocking. In example above, w = 26, i.e, by the time it has sent 26 frames (t=520) the ack for 0 will have arrived. This is known as pipelining.