If 4 bits are allocated for sequence number then calculate the difference between max sender window size in Go-Back-N ARQ and Selective Repeat ARQ.
(A) 0
(B) 8
(C) 7
(D) None of these.


Answer: (C)

Explanation: In Go-Back-N ARQ max sender window size < 2^m and in Selective Repeat ARQ max sender window size <= 2^{m – 1}, where m is number of sequence bit.
Go-Back-N ARQ max sender window size < 2⁴
Go-Back-N ARQ max sender window size < 16 = 15 Selective Repeat ARQ max sender window size <= 2^{4 – 1}
Selective Repeat ARQ max sender window size <= 2³
Selective Repeat ARQ max sender window size <= 8 Difference = (15 - 8) = 7 So, option (C) is correct.

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