$($d$)$ Outline four parameters defined in Internet Protocol services.

$(4$ marks$)$

$8.($a$)$ Describe the following cells as used in cellular mobile communication:

$($i$)$ micro cells;

$($ii$)$ pico cells.

$(4$ marks$)$

$($b$)$ Figure $2$ shows a block diagram of an encryption technique. Describe its operation.

$(6$ marks$)$

Fig. $2$

$($c$)($i$)$ State three types of $3G$ network technologies.

$(3$ marks$)$

$($ii$)$ A GSM $900MHz$ digital cellular network has the following characteristics:

Up$-$link and down$-$link of $925-945MHz$ and $965-985MHz$ respectively. RF channel spacing $=400kHz$

Number of users per RF channel $=16.$

Determine the:

I. channel bandwidth;

II$.$ up$-$link RF channels;

III. total number of up$-$link TDM channels.

$(7$ marks$)$