How many times the data can be sent on average to send the entire message through?

Question

The data from Network layer is divided into 10 frames at data link layer. Assume each frame has 70% probability to reach safely(without corrupted) and no retransmissions are there for corrupted packets. How many times the data can be sent on average to send the entire message through?

1.   35
2.   14.28
3.   32.3

Comments

https://gateoverflow.in/92937/me-test

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@sudsho,pls tell the sequqence whent here is retransmissiom for lost packets..

will it be like 10*0.3 + 10 *0.3*0.3 + 10 *0.3*0.3*0.3..??as for first try 10*0.3 will be lost then again we try again..

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here since we cant retransmit therefore u have to try for a successful event...if 1 packet can reach destination in 0.7 chance than for 10 frames it will be (0.7)¹⁰....this is the success probability...now if probability of something to occur is p, then the event will occur if we try it for 1/p times..so do 1/(0.7)¹⁰

if u can retransmit also then ur method is correct..

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THANKS

Answer 1

lep p= probability of getting unsuccessful transmission and "n" packets being sent

1) for n packets , number of retransmission = n*p

2) for retransmitted n*p packets , again we have to retransmit (np)*p packets

and recursion will continue

therefore total number of retransmitted packet =  np+np² +np³ +....................= np/(1=p)

in our case p= 1-0.7 =0.3 , n= 10 , therefore retransmitted packets = 10*0.3/0,7= 4.28

therefore total transmitted packets = 10+4.28 =14.28