Hi I have this assignment due tomorrow and im stuck.. its really getting to me..

any help would be great..

I have 2 questions:

Its about sliding window protocol:

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Following information given:
Transmission rate: 10 bits/usec
Signal Speed 200meters/usec
Time to create 1 frame = 1usec
Number of bits in a frame = 200
number of data bits in a frame =160
window size

assume acknowledgement is piggy backed

I need to know at what distance will the first acknowledgement arrive precesely when the last frame in the window is sent.

and

what is the effective data rate
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also


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The following three messages are to be transmitted over a data link.
Each message is to be protected by a 3-bit CRC generated using the polynomial: G(x) = x3 + x2 +1. Derive the CRC check bits for each of the three messages and show the respective messages transmitted.
(a) 0 0 0 0
(b) 0 0 0 1
(c) 0 0 1 0

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any help with these questions would be great..