Question $2[22]$

Consider the wireless topology above, comprised of $6$ nodes. Circles around each node illustrate their transmission range, e$.$g$.$ A$\text{'}$s range is shown by the dotted, shaded circle. Assume that the transmissions of two nodes will interfere at a location if and only if they transmit at the same time and their transmission areas overlap. In these problems, assume that losses only occur due to collisions.

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Degree and Diploma Examinations: June $2018$

Introduction to Data Communication and Networking: CSI $21$M$2$

List both the hidden and exposed terminals in each of the following:

a$.$ When node A transmits to node B$.[3]$

b$.$ When node B transmits to node C$.[3]$

You are considering using a "Request to Send $($RTS$)/$ Clear to Send $($CTS$)"$ protocol to reduce these potential problems from hidden and exposed terminals.

c$.$ When using RTS$/$CTS$,$ explain what would prevent a hidden terminal from clobbering a sender$?[2]$

d$.$ When using RTS$/$CTS$,$ explain how an exposed terminal decides it is safe to send to another destination? $[2]$

e$.$ Is RTS$/$CTS more like statistical $($time$-$division$)$ multiplexing, normal time division multiplexing, or frequency$-$division multiplexing? No explanation needed. $[1]$

f$.$ Why csma$/$cd is not suitable for wireless LAN? Explain your answer. $[4]$

Consider the Ethernet like network of self$-$learning switches S$1,$ S$2,$ S$3,$ S$4,$ S$5$ and S$6$ shown below. Assume the following $3$ frames delivered since the switches have started working: F$->$A $($frame sent from F to A$),$ D$->$C and C $->$ B$.$ List the switches through which the $4^{th}$ frame sent from $A$ to $E($A$->$E will be sent$).[3]$

g$.$ Why do we need the spanning tree protocol in Ethernet LANs? Use an example. $[4]$