Q$5.$ a$)$ Define IEEE $802\mathrm{.}15$ and briefly explain the main purpose of the standards.

b$)$ What is Zigbee, and how does it relate to IEEE $802\mathrm{.}15?$

c$)$ Explain the difference between IEEE $802\mathrm{.}15\mathrm{.}1$ and IEEE $802\mathrm{.}15\mathrm{.}4$ standards

d$)$ Briefly explain the followings in respect of IEEE $802\mathrm{.}15\mathrm{.}4$

i$)$ Power consumption

ii$)$ Range of IEEE $802\mathrm{.}15\mathrm{.}4$ networks

iii$)$ The frequency band used by IEEE $802\mathrm{.}15\mathrm{.}4.$

Q$6.$ a$)$ Briefly Explain how does the Carrier Sense Multiple Access with Collision Avoidance $($CSMA$/$CA$)$ protocol work in random access?

b$)$ What is the role of the back$-$off period in random access protocols?

c$)$ Discuss the challenges associated with hidden terminal and exposed terminal problems in random access networks and how can it be mitigated?

d$)$ In a WLAN installation, the maximum propagation delay is $0\mathrm{.}4$ sec $.$ The WLAN operates at a data rate of $10$ Mbps$,$ and packets have $400$ bits. Calculate the normalized throughput with three different CSMA protocols:

i$)$ unslotted nonpersistent

$($ii$)$ slotted persistent

$($iii$)$ slotted $1-$persistent CSMA.