Problem%20Set%203%202007%20Solutions

Problem%20Set%203%202007%20Solutions - Simon Fraser...

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Simon Fraser University School of Engineering Science Engineering Science 427 Semester 20 0 7 -1 Solutions Problem Set 3 Date: April 16 200 7 , Practice Problems, do not hand in Question 1: Consider a 1Mbps satellite channel. Frame length is 1000 bits (50 bits of overhead and the remainder user data) and the probability of an unsuccessful frame transmission is p . Assume that the errors on different frames are independent. Neglect the acknowledgement transmission time and receiver processing time, and assume a go-back- N method of error control. Assume p = 0.01 and t p = 350 ms. (a) What is the average number of transmissions per frame? (b) What is the maximum possible throughput for this go-back- N channel, in frames per second? (c) Repeat parts (a) and (b) assuming a selective repeat error control scheme with an assumed infinite reordering buffer. Solution: (a) The average number of transmissions per frame, , is given by: (b) The maximum possible throughput for this Go-back-N channel, , in frames per second, is found as follows: For , , , = 123.8 frames/second. (c) Repeating part (a), the average number of transmissions per frame is: Repeating part (b), the maximum possible throughput for this Selective Repeat chan- nel, in frames per second, is found as follows: N r , GBN N r , GBN =( 1 p )∑ i = 1
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This note was uploaded on 10/09/2009 for the course ENSC 1156 taught by Professor Rhardy during the Spring '07 term at Simon Fraser.

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Problem%20Set%203%202007%20Solutions - Simon Fraser...

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