GATE IT 2004 | Question: 81

Question

In a sliding window $ARQ$ scheme, the transmitter's window size is $N$ and the receiver's window size is $M$. The minimum number of distinct sequence numbers required to ensure correct operation of the $ARQ$ scheme is

• A. $\min (M, N)$
• B. $\max (M, N)$
• C. $M + N$
• D. $MN$

Comments

I have this doubt too.

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This is from Kurose and Ross book

Direct

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GO to the Root of Concept: Video Explanation with timestamp: Efficiency,Throughput| Relation Between WindowSize & Sequence No. Sliding Window | With NOTES

Answer 1

We all know that sender window is taken to be equal to reeciver window

or you can say number of sequence numbers are divided equally to both

So if sender is M

and receiver is N

to maintain the equilibrium, M+N is a constant

Comments

@ShashankRustagi In case of GBN ARQ How many distinct sequence numbers are required?

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Sliding Window has two implementations

• SR
• GBN

In SR sender window size is equal to reciever window size

but in GBN sender window size is N and Reciever Window size is 1

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But M+N is always constant. I have read Kuruthe Ross

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@ShivangiChauhan in case of GBN, distinct sequence numbers is always M+N

where M is n-1 and N is 1

that means sender has n-1 bits and receiver has only 1 bit