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Question

PURE ALOHA:

Vulnerable time:

Let us find the length of time, the vulnerable time, in which there
is a possibility of collision. We assume that the stations send fixed-length frames with
each frame taking T to send.

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so in pure aloha

vulnerable time(VT)

VT = 2 * transmission time

OR

VT = 2 * prapogation time

i m confused?????????????????????