In question $8,$ if the two stations use sliding window protocol with a

window size of $80,$ the maximum line efficiency will be up to:

$($a$)10\%$

$($b$)100\%$

$($c$)80\%$

$($d$)1$

$8\mathrm{.}2$

$($a$)$

$($b$)$

$($c$)$

$($d$)$

$9)$ A communication link has a bit error rate BER$=0\mathrm{.}02.$ Using a

frame length of $800$ bits, the probability of receiving a frame correctly

is given by:

$($a$)1$

$($b$)0\mathrm{.}2($c$)1-(1-0\mathrm{.}02)800$

$($d$)(1-0\mathrm{.}02)800$

$9$

$($a$)$

$($b$)$

$($c$)$

$($d$)$

$10)$ Two stations $($A$)$ and $($B$)$ use selective$-$reject ARQ to exchange

frames of $100$ bits at a data rate of $10$ Mbps$.$ The two stations are

connected by a full duplex line $10$ km long. Assume the velocity is $108$

m$/$s and a BER$=5$x$104.$

The window size to achieve an efficiency of $80\%$ is:

$($a$)18$

$($b$)17$

$($c$)17\mathrm{.}68$

$($d$)17\mathrm{.}684$

$10\mathrm{.}1($a$)$

$($b$)$

$($c$)$

$($d$)$