SELF DOUBT

Question

Two CSMA/CD stations are each trying to transmit large files of multiple frames. After each frame is sent, they contend for the channel using the binary exponential back-off algorithm.

The probability that the contention ends in round 3 is _____  (up to 3 decimal points)

Comments

0.375

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hmm plzz explain i am getting 0.875 ...

what is the meaning of this ends in 3rd collison i am doing like there are 8 cases at last out of 64 in which collison so

1-8/64= 1-1/8=7/8 =0.875

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0.0625????

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@Deepanshu

round $1$ there will be contention always as $A$ chooses from $\left \{0\right \}$ and $B$ also chooses from $\left \{0 \right \}$.

In round $2$, the probability of contention would be $\frac{2}{2*2}=\frac{1}{2}$

In round $3$, probability that contention will not occur would be $1-\frac{4}{4*4}=1-\frac{1}{4}$

required probability = $1*\frac{1}{2}*(1-\frac{1}{4})=0.375$

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in round 1 isnt values are 4 and collision in 1/4

as 4 values 00,11,01,10  now collison at 00 and 11

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how $4$ in the first round, initially the set only has $\left \{ 0\right \}$

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Shobhit Joshi plzz ellaborate for basic case means for n=1 i think i am doing base condition wrong

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In the first round $n=1$, both will choose from $(0), (0)$. So, they will surely collide.

In the second round $n=2$, both have to choose from $(0,1), (0,1)$. This time they may collide or not the one that looses the set gets $(0,1,2,3)$, if both collide $i.e$ when they choose $(0,0),(1,1)$, so both the sets will get double cardinality

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okk so base condition is wrong in base i am assuming 4 values from0,1

but it is just 0 

Shobhit Joshi thanku :)

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@Deepanshu dua mein Yaad rakhna :)

 

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Shobhit Joshi :)

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@Deepanshu bhai dua baat ra qa :p mujhe v bhej de thoda sa :p

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arvin : )

bhaiiii   meri dua se mera hi kuch nhi ho rha ... :P  mujhe khud dua nhi duayon ki jarurt hai ek aadhe se kuch nhi bnne wala apna ..

 jis jisne iss question mein comment kiya sbhi ke  bahut shi marks aayien  gate mein  : )

 

 

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@Deepanshu wo mangne walo ko kuch b ni dega na dua na dawa  :p islea prepare for cbt... :p

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Please donot misuse the word "self doubt". 
http://omikron.eit.lth.se/ETSN01/ETSN01/tutorials/Tutorial8.pdf