Consider the multiple access algorithm CSMA$/$CA for the wireless $802\mathrm{.}11$ protocol.

$($a$)(2$ points$)$ Explain what CSMA is and why it improves efficiency.

$($b$)(2$ points$)$ Why is there no CD $($collision detection$)$ in $802\mathrm{.}11?$

$($c$)(3$ points$)$ The CSMA$/$CA protocol results in the senders taking turns to transmit frames in a randomized fashion. Explain why that is the case.

$($d$)(3$ points$)$ Consider two nodes with frames to transmit. Node $1$ uses an earlier version of $802\mathrm{.}11$ with $10$ Mbps transmission rate. Node $2$ uses a newer version with $1$ Gbps transmission rate. What is the resulting throughput under CSMA$/$CA$?$

$($e$)(3$ points$)$ In addition to CSMA$/$CA$,$ there is also the RTS$/$CTS option where a wireless station and the access point use the RTS$/$CTS messages to reserve time for exclusive use. How is the scheme different from TDMA?