TDMA within the Air Interface

Question 1

How many timeslots are in each ARFCN?

Answer 1

8 timeslots, numbered 0 to 7

Question 2

What is being described by a complete cycle of timeslots?

Answer 2

A frame

Question 3

What is the duration of each frame?

Answer 3

4.62ms

Question 4

If each frame is equal to 4.62ms, what is the duration of one timeslot?

Answer 4

4.62/8 = 577 Micro seconds

Question 5

What timeslot is the Broadcast Control Channel associated with?

Answer 5

Timeslot 0

Question 6

What is the primary timeslot used to control all functions of a given cell?

Answer 6

Timeslot 0

Question 7

Name all relevant information the BTS will broadcast via the BCCH

Answer 7

MCC
MNC
Cell Idents
LAC
Encryption type 
NCC - Network Colour Code
BCC - Base Station Colour Code

Question 8

Name and explain the two states that timeslots 1-7 can exist in

Answer 8

Dedicated Control Channel (DCCH) - SMS/Incoming calls

Traffic Channel (TCH) - The phone call

Question 9

How is the MS informed of it’s timeslot allocation?

Answer 9

Via the BTS

Question 10

Explain the TA value ranges

Answer 10

0-63

0 - being up to 550m

Maximum of 35km, 64 x 550m

Question 11

What is a timing advance value dependent on?

Answer 11

The distance of the RF path

Question 12

What is meant if an MS is known the network as being in a detached state?

Answer 12

The MS is turned off/powered down and not connected to the network.

Question 13

Once the MS is registered with the network what state is it in?

Answer 13

An attached state, it now has full use of it’s authorised network services.

Question 14

What will the MS be doing whilst in an Idle state?

Answer 14

Monitoring timeslot for signalling information and incoming calls.

Question 15

Whilst in an Idle and Attached state to the network what is the MS said to be doing?

Answer 15

Camping on the network

Question 16

Name one advantage of mobile phone over a PSTN

Answer 16

It’s able to transit within the coverage area whilst maintaining network coverage.

Question 17

What is the BA List?

Answer 17

A list of up to 32 ARFCN broadcasted by the BTS for the MS to monitor

Question 18

The MS is programmed to select the 6 strongest frequencies from the BA List, what is this known as?

Answer 18

Neighbours List

Question 19

What will the MS automatically calculate every 5 seconds?

Answer 19

The Received Signal Strength Indicator

Question 20

When will the BSC perform a hand off?

Answer 20

When the signal quality drops below the predetermined quality threshold whilst in call.

Question 21

How long will the BSC monitor the quality of the new ARFCN for before deciding to move it onto the MS

Answer 21

5 seconds