CMC ICT3207 Call Flow

Associate Professor

Dept. of Electrical and Electronic Engineering

University of Dhaka

Dr.

Mohammad

J

unaebur

R

ashid (

JR

)

1

ICT3207: Cellular and Mobile Communication (3.0 Cr)

Course Teacher

Bangladesh University of Professionals

Lecture 08

Analog cellular mobile specifications

ICT3207: CMC

1. Home mobile station (unit): A mobile station that is subscribed in its cellular system.

2. Land station: A station other than a mobile station, which links to the mobile station.

3. Control channel: A channel used for the transmission of digital control information from a

land station to a mobile station, or vice versa.

4. Forward control channel (FDCC): A control channel used from a land station to a mobile

station.

5. Reverse control channel (RECC): A control channel used from a mobile station to a land station.

6. Forward voice channel (FVC): A voice channel used from a land station to a mobile unit. 7. Reverse voice channel (RVC): A voice channel used from a mobile station to a land

station.

8. Set-up channels: A number of designated control channels.

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Lecture 08

Analog cellular mobile specifications

ICT3207: CMC

10. Paging channel: The act of seeking a mobile station when an incoming call from the land

line has been placed to it.

11. Digital color code (DC): A digital signal transmitted by a forward control channel to

detect capture of an interfering mobile station. There are four codes (See signaling format). 12. Flash request: A message sent on a voice channel from a mobile station to a land station

indicating a user's desire to invoke special processing, such as an emergency.

13. Signaling tone: A 10-kHz tone transmitted by the mobile station on a voice channel. It serves several functions.

14. Handoff: The act of transferring a mobile station from one voice channel to another voice channel. There are two kinds of

handoffs-a. Inter-handoff, from one cell to another cell

Lecture 08

Analog cellular mobile specifications

ICT3207: CMC

15. Numeric information: Used to describe the operation of the mobile station.

Numeric indicators

MIN - mobile identification number

MIN1 - 24 bits that correspond to the seven-digit directory number assigned to the mobile station

MIN2 - 10 bits that correspond to the three-digit area code

BIS - Identifies whether a mobile station must check an idle-to-busy transition on a reverse control channel when accessing a system. In a forward control channel busy-idle bit inserts in

every 10-bit interval of a transmitted bit stream.

CCLIST – scanned by a mobile station on a list of control channels

CMAX – maximum number of control channels to be scanned by the mobile station (up to 21

channels)

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Lecture 08

Analog cellular mobile specifications

ICT3207: CMC

MAXSZTR - maximum number of seizure attempts allowed on a reversed control channel

NBUSY - number of times a mobile station attempts to seize a reverse control channel and finds it busy

NSZTR - number of times a mobile station attempts to seize a reverse control channel and

fails

PL - mobile station RF power level

SCC - a digital number that is stored and used to identify which SAT frequency a mobile station should be received on

16. Paging: The act of seeking a mobile station when an incoming call from the land station

has been placed to it.

17. Paging channel: A forward control channel which is used to page mobile stations and send

orders.

18. Registration: The procedure by which a mobile station identifies itself to a land station as

Lecture 08

Analog cellular mobile specifications

ICT3207: CMC

19. Roamer: A mobile station which operates in a cellular system other than the one from

which service is subscribed.

20. Supervisory audio tone (SAT): One of three tones in the 6-kHz region; there is one SAT

frequency for each land station. In certain circumstances, there is one SAT frequency for each sector of each land station.

21. System identification (SID): A digital identification uniquely associated with a cellular

system.

22. Electronic serial number (ESN): Each mobile station has an ESN assigned by the

manufacturer as well as International Mobile Equipment Identity (IMEI).

23. Group identification: A subset of the most significant bits of SID that is used to identify a

group of cellular systems, such as GP, BL, Robi, Rogers, PacTel systems,

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Lecture 08

Mobile Unit: Power

ICT3207: CMC

• A power level of 0 dBm corresponds to a power of 1 milliwatt. To express an arbitrary

Lecture 08

Mobile Unit: Power

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Lecture 08

Mobile Unit: Power

ICT3207: CMC

• Let P₀ be the specified power and f₀ be the specified frequency channel. P and f are the

operating power and frequency, respectively.

• Power level (carrier-off condition) requires P < -60 dBm in 2 ms

• Power level (carrier-on-condition) within 3 dB of specified power (P₀) within 2 ms

• Power level (off-frequency condition), if |f-f_c|>1 kHz, do not transmit; then P < - 60 dBm

• Power transmitted levels are maximum effective radiated power (ERP) with respect to a

half-wave dipole

• Each mobile station power class I has eight full power levels (0 to 7), with power level 0

being the highest. Each level has a 4-dB drop. The total power control range for power class I

Lecture 08

Mobile Unit: Modulation

ICT3207: CMC

1. Compressor / expandor (compandor): A 2:1 syllabic compander is used. Every 2-dB change in input level converts (compresses) to 1 dB at output (at the transmitted side). Then

reverse the two numbers (expand) at the received side. It serves two purposes:

a. To confine the energy in the channel bandwidth b. To generate a quieting effect during a speech pulse

2. Preemphasis / deemphasis:

In processing electronic audio signals, pre-emphasis refers to a system process designed to

increase the magnitude of some (usually higher) frequencies with respect to the magnitude of

other (usually lower) frequencies in order to improve the overall signal-to-noise ratio by minimizing the adverse effects of attenuation or distortion. The mirror operation is called

de-emphasis, and the system as a whole is called emphasis.

The frequency response is decided by special time constants. The cutoff frequency can be

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Lecture 08

Mobile Unit: Modulation

ICT3207: CMC

• The preemphasis network and its response are shown in Fig. 3.1. The improvement factor

ρ_FM is

• For f₂/f₁ <2, ρ_FM approaches 1.

• For wideband, f₂ > f₁. Thus

Lecture 08

Mobile Unit: Modulation

ICT3207: CMC

3. Deviation limiter: Mobile station must limit the instantaneous frequency deviation to ± 12

kHz.

• The advantage of using a Manchester code in a voice channel is that the energy of this code

is concentrated at the transmission rate of 10 kHz.

• Therefore, a burst of signals transmitted over the voice channel can be detected. The

Manchester code is applied to both control channels and voice channels. 4. Wideband data signal: A NRZ

(non-return-to-zero) binary data stream is encoded to a Manchester (biphase) code (Fig. 3.3). It

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Lecture 08

Mobile Unit: Modulation

Lecture 08

Mobile Unit: Frequency Band

ICT3207: CMC

Mobile Unit: Security and Identification

1. Mobile identification number (MIN): A binary number of 34 bits (234 _{≈ 1.7×10}10_{) derived}

from a 10-digit directory telephone number.

2. Electronic serial number (ESN): A 32-bit binary number that uniquely identifies a mobile unit and must be set by the factory. Attempts to change the serial number circuit should

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Lecture 08

Mobile Unit: Security and Identification

3 First paging channel (FIRSTCHP): An 11-bit system which identifies the channel number

of the first paging channel when the mobile station is "home." It is stored in the mobile unit 4. Home system identification (SID): Fifteen-bit system used to identify the home station.

The least significant bit is 1 for a Block A system, otherwise 0 for a Block B system (GSM

or CSMA; SIM1 and SIM2)

5. Preferred system selection: Provided as a means for selecting the preferred system as

either system A or system B within a mobile station.

Mobile Unit: Supervision

SAT (supervisory audio tone)

1. SAT function: There are three SAT tones: 5970, 6000, and 6080Hz. The tolerance of each tone is ± 15 Hz. The features of the SAT tones are

Lecture 08

Mobile Unit: Supervision

b. One SAT tone is added to each forward voice channel (FVC) by a land station. The mobile station detects, filters, and modulates on the reversed voice channel (RVC) with this same

tone.

c. SAT is suspended during transmission of wideband data (a burst of signaling of 10 kbps), information, or other control features on the reverse voice channel.

d. It is not suspended when a signaling tone (10 kHz) is sent.

e. The received audio transmission must be muted if the measured SAT and SCC do not

agree with each other.

2. SAT transmission. The tone modulation index is 1/3. It is a narrowband FM. The deviation ΔF = ± 2 kHz is centered around each SAT tone.

3. Fade timing status of SAT: The transmitter is turned off if-no valid SAT tone can be detected or the measured SAT does not agree with the SAT color code (SCC) of each cell

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Lecture 08

Mobile Unit: Supervision

• Signaling tone. Signaling tones must be kept within 10 kHz ± 1 Hz and produce a nominal

frequency deviation of ±8 kHz of the carrier frequency.

• It is used over the voice channel. It serves three functions.

1. Flush for special orders 2. Terminate the cells

3. Order confirmation

• Malfunction timer set at 60 s: The transmission will cease when the timer exceeds 60 s. The