Telecommunication Basics

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TELECOMMUNICATION BASICS

Compiled by : Muntasirur Rahman Rumman , KUET, EEE- 2k3 Batch

What is Communication & Telecommunication?

Ans. Communication: The word communication may be defined as the exchange of information of

any kind by any means from one location to another location.

Other word, communication is the transfer of information over distance. Information can take many

forms, including picture, writing, speech, signal and so on.

Telecommunication: Telecommunication is the transfer of information over distance via transmission

media such as wire or optical fiber.

What is data, information & signal?

Ans. Signal: A signal is an event that changes with time and can be used to convey information as a

means to facilitate communication

What is base band Signal?

A signal with frequency content centered around DC. Typically the modulating signal for an RF carrier

What is Modulation & Demodulation?

Modulation: The process of coding and decoding information for transmission. For example, a voice

conversation is coded into binary bits (digital information), transmitted and then decoded at the

receiving end

Demodulation: Process of recovering the original modulating signal from a modulated carrier. The

original modulating signal is usually the information being transmitted, typically voice or data.

What is the significance of Modulation?

Ans. Modulation is Significant due to the following

1. To reduce antenna size

2. To reduce interference

3. To increase signal strength (S/N ratio or capacity of the system)

Why Microwave Frequency is used in telecommunication?

Ans. a) Signal should be strong enough for point-to-point transmission. If the frequency is below the

microwave range then point to point transmission is impossible

b) For better S/N ratio

What is up link & down link frequency?

Link: The radio connection between a transmitter and a receiver.

Downlink: The transmission path from the base station down to the mobile station.

Downlink 869 – 894 MHz

Uplink The transmission path from the mobile station up to the base station.

Uplink 824 – 849 MHz

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What is the uplink & downlink frequency of GSM 900 & GSM 1800?

Ans. For GSM 900



Bandwidth 25 MHz

Carrier Separation 200 KHz

Radio Channel 125 ~ 124

Transmission Rate 270 Kbps (per time slot)

For GSM 1800



Bandwidth 75 MHz

Carrier Separation 200 KHz

Radio Channel 375

Transmission Rate 270 Kbps (per time slot)

CDMA (City Cell):

City Cell band 800MHz

Uplink 824 – 849

Downlink 869 – 894

Bandwidth 1.23 MHz

Mid frequency 824 + 30 x 283

=832.49 MHz

1st Carrier 283 (Carrier Number)

2nd

Carrier 241

Modulation QPSK

Sampling rate 8 sample / s

Bit rate 8 bit / sample

= 8 x 8 bit / s

= 64 bps

PCM 64 Kbps

64 Kbps Vocoder 9.6 kbps

What is Bandwidth & Beam width?

Bandwidth: The information-carrying capacity of a communications channel. Usually expressed in

Hertz (cycles per second) for analog circuits and in bits per second (bps) for digital circuits.

Beam width: The directiveness of a directional antenna. Define as the angle between two half power

points (-3 dB) points on either side of the main lobe of Radiation.

Why increased Bandwidth is necessary for proper Data Communication? Ans. To increase the system capacity, more bit rate etc.

Which band of frequency used in Bangladesh for GSM?

Ans. 900 MHz & 1800 MHz

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Give the data rate, bandwidth, bandwidth efficiency & Modulation used in GSM digital cellular.

Ans. In GSM- Digital Cellular

Data Rate 270kb/s

Bandwidth 200kHz

Bandwidth Efficiency 270/200 =1.35bits/sec/Hz

Modulation Gaussian Minimum Shift Keying (FSK with orthogonal

frequencies).

What type of modulation is used in CDMA & GSM?

Ans. The modulation technique QPSK (Quadrature Phase Shift Keying) & GMSK (Gaussian

Minimum Shift Keying) is used for CDMA & GSM respectively. GMSK is a form of continuous-

phase FSK, in which the phase is changed between symbols to provide a constant envelope.

Consequently, it is a popular alternative to QPSK.

What are the main advantages of CDMA technique?

Ans. The main advantages of CDMA are as follows:

1. Increased capacity

2. Improved voice quality, eliminating the audible effects of multipath fading

3. Enhanced privacy and security

4. Improved coverage characteristics which reduce the number of cell sites

5. Simplified system planning reduces deployment and operating costs

6. Reduced average transmitted power, thus increasing talk time for portable devices

7. Reduced interference to other electronic devices

8. Reduction in the number of calls dropped due to handoff failures

9. Development of a reliable transport mechanism for wireless data communications

10. Coexistence with previous technologies, due to CDMA and analog operating in two spectra with

no interference

What is Channel Separation?

The distance between adjacent frequencies on either the uplink or downlink is called channel

separation

Channel separation is 200 KHz

Transmission rate

The transmission rate over the air is 270 Kbps

What is Duplex distance?

The distance between one uplink frequency and its corresponding down link frequency is called duplex

distance

What is Traffic and Earlang?

Earlang: An earlang is a unit of telecommunication traffic measurement. It means hours of traffic in

an hour. For example, if a group of users made 30 calls in one hour and each call had an average call

duration of 5 minutes, then the number of earlang-

Minutes of traffic in an hour = nos. of calls x duration

= 30 x 5

=150

Hours of traffic in an hour = 150 / 60

=2.5

So, traffic figure =2.5 Earlangs.

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In GSM (GP) assume that network traffic per subscriber is 16-mili earlang. Now network traffic 29000

earlang.

What is cell?

Ans. A cell is a basic unit of a cellular system and is defined as the radio coverage given by one BS

antenna system

What is transmission medium? Classify it. Where are these media mainly used – in access or

trunk network?

Ans. Transmission media: The media through which signal is transmitted is known as transmission

media.

1) Copper – wire Access network

2) Radio – microwave Trunk & Access network

3) Optical fiber – fiber Trunk & Access network

4) Infrared

5) Microwave

Why optical fibers are so advantageous over other transmission media?

1. The light weight and no corrosiveness of the fiber make it very practical for aircraft &

automotive application

2. A single fiber can handle as many as voice channels as a 1500 pair cable can

3. The spacing of repeaters from 35 Km to 80 Km for fibers as opposed to from 1 Km to 1.5 Km

for wire is great advantageous

4. Fiber is immune to interference from lighting, cross talk and electromagnetic radiation

What is rectifier? What kind of voltage is used in telecommunication?

Ans. It is a device that employs two or more diodes to convert ac voltage into pulsating dc voltage.

DC voltage is used in telecommunication and its value is –48 volts.

Why negative system is used in transmission?

1. To eliminate higher harmonics

2. To ensure voltage stability

3. Less oxidization

What is guard band?

A set of frequencies or bandwidth used to prevent adjacent systems from interfering with each other.

Guard bands are typically used between different types of systems at the edges of the frequency

allocations.

What is sampling theorem?

Ans. Sampling theorem states that all information in the original signal will be include in the sampled

signal if the sampling frequency is greater than twice the highest frequency component in the original

signal (8 KHz > 2x 3.4 KHz)

What is the Nyquist’s theorem?

Ans. Nyquist’s theorem states that if B is the bandwidth of a transmission channel that carries a signal

having L levels, the maximum data rate is given by

R = 2B log2 L

If signal to noise ratio is S / N, the maximum data rate is given by

R = B log2 (1+S/N)

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What is Nyquist rate?

The minimum sampling rate proposed by Nyquist for converting a band limited waveform to digital

pulses. The rate must be at least twice the highest frequency component in the waveform being

sampled.

What is SNR? What is the effect of it on transmission?

Ans. The ratio of the signal strength to the noise level is called the signal to noise ratio (SNR).

If the SNR is high (i.e. the signal power is much greater than the noise power) few errors will occur.

However, as the SNR reduces, the noise may cause symbols to be demodulated incorrectly, and errors

will occur.

What is PCM? Describe it?

Ans. PCM (Pulse Code Modulation): A modulation technique in which analog (sound) signal is

converted into digital (binary) signal

In a PCM technique the total amplitude range of a signal is divided into a number of standard levels

that is known as sampling. Then the magnitude of each sample is quantized by a process known as

quantizing and digitized by coding in binary for transmission over a transmission channel / medium.

What is handoff & Handover?

Ans. The process of transferring a call in progress from the current base station to another without

interruption as the user moves out of range of the current base station.

The passing of a call signal from one base station to the next as the user moves out of range or the

network software re-routes the call.

What is Hard Hand off & Soft hand off?

Ans. In a traditional "hard" handoff, the connection to the current cell is broken, and then the

connection to the new cell is made. This is known as a "break-before-make" handoff. Since all cells in

CDMA use the same frequency, it is possible to make the connection to the new cell before leaving the

current cell. This is known as a "make-before-break" or "soft" handoff. Soft handoffs require less

power, which reduces interference and increases capacity

What is soft handoff ?

A process of establishing a call connection simultaneously to two separate base stations in a CDMA

system. This technique allows the use of a dual path in the handoff region to improve performance.

Soft handoff can only occur between base stations using the same RF channel ie. CDMA.

Why call drop occur?

Call drop occurs due to the followings

1. 1.If Ec /Io goes bad

2. Hand off failure

3. If Rx level is poor

4. If FER is bad [frame error rate]

5. PN pollution [if more than four strong signal is present]

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*** Why there are fluctuations in the signal (frequency) level in different places of the city and in

different times of the day?

Ans. The reasons that greatly affect the signal (frequency) level of wireless systems especially CDMA

are many but a few prime reasons are given below.

1) The first and foremost that affects the signal (frequency) level in any place is the subscriber

density. In engineering terms it is called Ec/Io. It means how far better your signal power is

than that of noise. This is created by the signals of other subscribers active in your region or

cell.

2) There is shrinkage of the coverage area of a cell for different numbers of subscribers present in

a cell area and thus the signal (frequency) level fluctuates in that at different times of the day.

3) The source of noise is not only the power radiation of subscribers but also from other sources

of noise. They are from Electronic machines elsewhere, Vehicles plying on roads & streets, Jet

engines etc.

4) The weather effect is also a prominent factor. Flashes of thunder, moisture affect the radio

(frequency) behavior and as a result signal (frequency) fluctuates.

5) The electro-magnetic wave travels in different paths (direct and reflected paths because of

Buildings and other elevations), that is called multi-path propagation in technical term. This

multi-path propagation causes different signal level in different time.

6) The metallic bodies of the transports reflect the electromagnetic radiation (frequency) and thus

the reflected radiation (frequency) interfere with the main signal (frequency) and produce

unwanted effects.

What is fading? What are the factors responsible for Fading?

Fading: The variation in signal strength from it normal value. Fading is normally negative and can be

either fast or slow. It is normally characterized by the distribution of fades, Gaussian, Rician, or

Rayleigh.

Fading of the RF signal is caused by several factors:

1. Multipath

2. Bad Line of Sight

3. Link Budget calculation

4. Weather conditions (Rain, wind etc.)

5. Interference

Flat fading-- A type of fading in a communications channel that attenuates or fades all frequencies in

the channel the same amount

What is Fresnel Zone?

The Fresnel zone is the area of a circle around the line of sight.

The Fresnel Zone is defined as follows:

R1= ½ Ö (lxD)

R: radius of the first Fresnel zone

l: wavelength

D: distance between sites

What is Fade Margin?

The difference between the Unfaded Receive Signal Level and the Maximum Receiver Sensitivity at

10 E-6 BER.

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What is Antenna Gain?

Antenna gain is a measure of directivity. It is defined as the ratio of the radiation intensity in a given

direction to the radiation intensity that would be obtained if the power accepted by the antenna was

radiated equally in all directions (isotropically). Antenna gain is expressed in dBi.

What is Inter Symbol Interference?

Ans. Inter Symbol Interference (SIS) is defined as the interference arises when energy from one

symbol slot is spread out over neighboring symbol slots.

The channel introduces ISI when the RMS delay spread becomes an appreciable fraction of the bit

period (say greater than 10%).

What are the basic characteristics of Spread Spectrum?

Spread Spectrum: A transmission technique in which a pseudo noise code, independent of the

information data is employed as a modulation wave-form to “spread” the signal energy over a

bandwidth much greater than the signal information bandwidth. At the receiver the signal is “dispread”

using a synchronized replica of the pseudo noise code.

The basic characteristics of spread spectrum system as follows:

1. The carrier is an unpredictable, or pseudorandom, wideband signal.

2. The bandwidth of the carrier is much wider than the bandwidth of the data modulation.

3. Reception is accomplished by cross correlation of the received wide-band signal with a

synchronously generated replica of the wide-band carrier.

What is Roaming?

Roaming Within your home network, this means that your mobile phone automatically sets up

communication procedures with different radio base stations when on the move.

International roaming means that you can use networks other than your own when traveling abroad.

What is interference? Define adjacent channel interference & Co-channel interference.

(Interference in Mobile radio Channel)

Ans. Interference is the result of other man-made radio transmissions. For example in the ISM band at

2.4GHz a large number of systems co-exist, such as Wireless LAN, Blue tooth, Microwave ovens, etc

Adjacent channel interference: Adjacent channel interference occurs when energy from a carrier

spills over into adjacent channels

Co-channel interference: Co-channel interference occurs when another transmission on the same

carrier frequency affects the receiver. This will often arise from transmissions in another cell in other

network.

What is co-channel interference?

Unwanted interference within a radio channel from another transmitter using the same channel at a

different location. Co-channel interference is very common in a frequency reuse system and must be

carefully controlled to prevent problems.

What is the difference between PDH & SDH data transmission?

In SDH, data transmit byte by byte and in PDH, data transmit bite by bite

On what factors polarization depends? Ans. Polarization depends on the orientation of the electric Field

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What is Aliasing effect?

Ans. A type of signal distortion that occurs when sampling frequency of a signal is less that the

Nyquist rate.

What do you mean by EDGE?

Ans. EDGE (Enhanced Data GSM Environment): A faster version of GSM is designed to deliver data

at rates up to 384 Kbps and enable the delivery of multimedia and other broadband applications to

mobile phone and computer users

What is Bluetooth?

A short-range radio technology developed by Ericsson and other companies that make it possible to

transmit signals over short distances between telephones, computers and other devices without having

to interconnect them with wires.

What is transport network? Classify them with definition.

Ans. Transport network is divided into two parts –

Access Network (AN)

Trunk Network

Access network: Users are grouped together by being connected to the same switching node. E.g. the

local exchange is a AN

Trunk network: The trunk network connects ANs and Node Network (NNs) with other ANs & NNs

Write down different STM-N. What is the number of PCM (2 Mbps) can be carried by one

STM-1?

STM – 1 155 Mbps (basic module)

STM – 4 620 Mbps

STM – 16 2.5 Gbps

63 PCM is carried by a STM – 1

What are differences betn

Circuit Switching and Packet switching?

Ans:

Circuit Switching Packet Switching

1. Direct electrical connection betn the 1. No direct electrical connection

Communicating parties

2. Real time or Conversational interaction 2.Fast enough for real time or conversational

betn the parties is possible interaction

3.Messages are not Stored 3.Messages are stored until delivered but not

filled

4. Switched path is established for the 4.The route is established dynamically for

entire conversation each packet

What is common channel signaling (CCS)?

Ans. Separating out the signaling from the actual data being carried as referred to as common channel

signaling

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What is the data rate of 24 & 30 channel of GSM 900?

Ans. R = 2Blog22

= 2x24x200x log22

=9600 Kbps.

***The GSM network can be divided into three broad parts

1. MS (SIM- Subscriber Identity Module; ME- Mobile Equipment) The Mobile station is carried

by the subscriber.

2. BSS (Base Transceiver Station; Base Station Controller) Base Station Subsystem controls the

radio link with the mobile station

3. NSS (HLR, VLR, EIR, AuC, MSC) – The Network Subsystem, the main part MSC perform the

switching of calls betn

the Mobile users and betn

mobile and fixed network users. The MSC

also handles the management operation

SIM – Subscriber Identity Module provides personal mobility

BTS – Base Transceiver Station houses the radio link (Transceiver) that defines a cell and handles the

R-link protocols with MS.

BSC – Base Station Controller manages all radio related function such as radio channel setup,

frequency hopping MS handovers. The BSC is the connection between the MS and MSC.

NSS – Network Station Subsystem

1. MSC provides the connection to the fixed networks, signaling between functional entities in the

network subsystem uses (SSS 7) signaling system number 7

2. The HLR & VLR together with MSC provides call routing and roaming capabilities of GSM.

HLR – Contains all administrative information & current location of the mobile. Location means

signaling address of the VLR associated with the mobile station.

VLR – contains selective administrative information from HLR necessary for call control &

provision of the subscriber services

4. The EIR & AuC are used for authentication and security purposes

EIR – is a database that contains a list of all valid ME on the network where each MS is identified by

its IMEI

AUC – A protected database that stores a copy of the secret key stored in each subscriber SIM.

What do you mean by a) GMSC b) RBS c) SWR d) SDH?

Ans. GMSC (Gateway Mobile Switching Center): A gateway is a node used to interconnect two

networks. The gateway is often implemented in an MSC. The MSC is then referred to as the GMSC

RBS (Radio Base Station): RBS acts as the interface betn MS’s and the network by providing radio

coverage from their antennae.

SWR (Standing Wave Ratio): The ratio of maximum current to minimum current along a transmission

line, as it is the ratio of maximum to minimum voltage. It is the measure of the mismatch betn the load

and the line. I t is the most important quantity calculated for a load.

SWR= Z0 / RL or SWR= RL / Z0

Where RL is the load resistance

SDH (Synchronous Digital Hierarchy): A new structure for digital multiplexing. It is a standardized

byte interleaved multiplexing hierarchy for digital synchronous and plesiochronous signals for mainly

optical transmission. In SDH we find multiplexing levels and signal levels.

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What is Switching & SONET/ SDH?

Ans. Switching: The process of interconnecting functional units, transmission channel or

telecommunication circuits for as long as it is required to convey signals is known as Switching.

SONET/ SDH: SONET/ SDH refers to a group of fiber optic transmission rates that can transport

digital signals with different capacities. (such as 1.5/ 2/ 6/ 34/ 45/ 140 Mbps within a transmission rates

of 155.52Mbps). It is defined by CCITU/ ITU-IS for world wide use and partly compatible with

SONET.

Bit rate of SONET 1.5 / 6 / 45 Mbps

Bit rate of SDH 1.5 / 2 / 6 / 34 / 45 / 140 Mbps

History of GSM:

The first digital cellular standard (GSM) is launched in 1991

In Sheba telecom



It started its operation in 25 June, 1995, Joint Venture by Bangladesh (Technology Resource Industries

51%) & Malaysia (Integrated Services Ltd. 49%)

What is OSI (Open System Interconnect)?

Ans. A reference model that describes a layered structure for modeling the interconnection and

exchange of information between users in a communications system. The 7 layers are

Application layer, Presentation layer, Session layer, Transport layer, Network layer, Data link layer,

Physical layer

Draw TCP/IP Stack.

TCP

IP FTP

SNMP ICMP

Telnet

TCP/ IP Stack

TCP/ IP is programmed for only raw data and converts it to logical data

Ping: Can’t convert data it can recognize only

SNMP: it is capable to give information about the system. It allows only those things which is known

to it

NTP: it synchronizes all data base servers of any type

What is the interface between MS & BTS?

UM interface(gsm radio air)

Define Propagation & Propagation channel?

Propagation: The process an electromagnetic wave undergoes as it is radiated from the antenna and

spreads out across the physical terrain. See also propagation channel.

Propagation channel: The physical medium electromagnetic wave propagation between the transmit

and receive antennas, and includes everything that influences the propagation between the two

antennas.

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Write down the name of the OSI layer on which the following instruments work?

Router - Network, HUB - Physical, Switch – Network & Physical, PC - Physical

What is cross talk?

The ability for unwanted information from one channel to "spill over" into an adjacent channel.

What is LOS?

A description of an unobstructed radio path or link between the transmitting and receiving antennas

of a communications system.

What do you mean by Path loss?

The amount of loss introduced by the propagation environment between a transmitter and receiver.

What is Diversity Channel & Frequency diversity?

Diversity Channel: A radio channel that not only introduces AWGN, but also the effects of multipath

and frequency selective fading.

Frequency diversity: The simultaneous use of multiple frequencies to transmit of information. This is a

technique used to overcome the effects of multipath fading, since the wavelength for different

frequencies result in different and uncorrelated fading characteristics.

What is C/I ratio?

Ans. The ratio of the carrier to the interference (from both sources) is called the carrier-to-interference

ratio (C/I). A certain C/I ratio is required to provide adequate quality transmission. Increasing the

carrier power at the receiver will increase the interference for other mobiles in the network.

What is baud (or signaling) rate?

The baud (or signaling) rate: The baud (or signaling) rate defines the number of symbols per second.

Each symbol represents n bits, and has M signal states where

M = 2n.This is called M-ary signaling

The maximum rate of information transfer through a base band channel is given by

fb = 2 W log2M bps

where fb =Capacity

W = bandwidth of modulating base band signal

The Nyquist bandwidth is the minimum bandwidth than can be used to represent a signal.

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What is diffraction?

A propagation phenomenon that allows radio waves to propagate beyond obstructions via secondary

waves created by the obstruction. Classic types of diffractions are smooth earth and knife-edge.

Microwave / Electromagnetic Radiation: Power that radiated into free space is governed by the

characteristics of free space is known as the EM radiation.

EM wave propagates through free space at the velocity that is near about light velocity i.e. 186000

miles/ hr or 3 x 108 m/s or 3 x 10

5 Km/ S

VSAT (Very Small Aperture Terminal)

The satellite is a microwave repeater, receiving signals from earth stations, amplifying them at

RF and retransmitting them to earth

To prevents interference the difference between uplink and downlink frequency is of about 2

GHz

These satellites are geostationary. They have the same angular velocity at the earth (i.e. one

complete cycle per 24 hours) and so they appear to be stationed over one on the glob

By the celestial mechanism the velocity depends on its distance from the earth and on whether

the satellite is in a circular on elliptical orbits

The actual orbital velocity of a geostationary satellite is 11000 Km/ hr or nearly 2 miles/s

INTELSAT (International Telecommunications Satellite Consortium)

INTELSAT 1, better known as Early Bird, was launched over the Atlantic in 1965; there were

only five earth stations to make use of the 66-telephone circuit it offered

Now there are over one dozen INTELSAT IV, IV-A, V-A satellites over the Atlantic, Indian

and Pacific Ocean

INTELSAT VI Satellites:

Launched in the late 1980

Capable of providing up to 20,000 telephone ckts each

TV services for international and domestic use

ISDN Channels

B Channel: Bearer, user data only. The B channel is a 64 kbps clear channel (i.e. no signaling

information) used for voice, data, text, image or video/ Graphics. Either circuit or packet switched

network

D Channel: Used for signaling information and can operate either 16 kbps or 64 kbps depending on

whether it is supporting two B channel. Also used for Telemetry, low speed packet data, alarm signal,

telephone-to-telephone text message

H Channel: There are three H channels all of which provides higher speed than the 64 kbps (B

channel) H 0; 384 kbps, H11, H12 used for video conferencing, high-speed facsimile packet switched

data. H11 speed 1.544 Mbps. H12 available only in Europe operate at 1.920 Mbps

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Briefing on CDMA system by PBTL

Overview of network:

System information

Suppliers

Functional briefing of MS, BTS, BSC and MSC

Benefits of CDMA over GSM:

Bandwidth

Voice Quality

No Cross connection

Easy migration to 3G

High cell range

Coverage Issues:

Range of coverage

o Hand-set (0db gain)

o FWT (9~12db gain)

Hand-over

Sectorization

Metro- and District coverage

Situation at the edge of cell

Capacity Issues:

TCH limitation

Noise (due to high density of customers and external antenna)

Congestion due to capacity (BHCA)

Standard:

IS-95A

CDMA 2000

Complain Issues:

Low network at the edge of cell

High density of subscribers leading to high noise

Indoor/Outdoor scenario

Congestion with GP

Authentication

Zone Issues:

Zone defining

Roaming issues

R-UIM Issues:

Hand-set compatibility

Fraud cases of ESN

Similarities/dissimilarities with SIM

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Write short note on Router, Vocoder &Transceiver? Router: A data switch that handles connections between different networks. A router identifies the

addresses on data passing through the switch, determines which route the

transmission should take and collects data in so-called packets that are then sent to their destinations.

Vocoder: Refers to a voice encoder that is a device that codes and decodes the human voice (sound

waves) into digital transmission. Higher vocoder speeds offer enhanced sound quality

Transceiver: A transmitter and receiver contained in one package. A 2- way radio or cell phone is an

example of a transceiver.

Wireless Dictionary Wireless dictionary Wireless Dictionary Wireless dictionary

2G

Second generation of wireless

communication systems. BCH

Broadcast Channels

3G

Third generation of wireless

communication systems. BER

Bit Error Rate

3GPP

Third-Generation Partnership

Project (W-CDMA) BERT

Bit Error Rate Tester

ACIR

Adjacent Channel

Interference Ratio bps

Bits per Second

ACLR

Adjacent Channel Leakage

Ratio BPSK

Binary Phase Shift Keying

ACTS

Advanced Communications

Technology and Services BS

Base Station

ADC Analog-to-Digital Converter

BSC

Base Station Controller

ADPCM

Adaptive Differential Pulse

Code Modulation BSIC

Base Station Identity Code

AGC Automatic Gain Control

BSS

Base Station Subsystem

AIN

Advanced Intelligent

Network BT

Bandwidth Time Product

AM Amplitude Modulation

BTS

Base Transceiver Station

AMPS

Advanced Mobile Phone

System C/I

carrier-to-interference ratio

ANSI

American National Standards

Institute C/N

carrier-to-noise ratio

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APC Automatic Power Control

CAI

Common Air Interface

ARDIS

Advanced Radio Data

Information Systems CBCH

Cell Broadcast Channel

ATM

Asynchronous Transfer

Mode CCH

Control Channel

AUC Authentication Center

CDMA

Code Division Multiple

Access

AWGN

Additive White Gaussian

Noise CDPD

Cellular Digital Packet Data

BCCH Broadcast Control Channel

CGSA

Cellular Geographic Service

Area

CIF

Common Intermediate Format

EDGE

Enhanced Data for Global

Evolution

CODEC

Coder/Decoder

EFR

Enhanced Full Rate

CPM

Continuous Phase Modulation

EIR

Equipment Identity Register

CTIA

Cellular Telecom Industry

Association ESN

Electronic Serial Number

CW

Continuous Wave

FCC

Federal Communications

Commission

DAC

Digital to Analog Converter

FCCH

Frequency Correction Channel

D-AMPS

Digital-Advanced Mobile

Phone System FDD

Frequency Division Duplex

dB

deciBel

FDMA

Frequency Division Multiple

Access

dBd

deciBels referenced to a

dipole antenna FER

Frame Erasure/Error Rate

dBi

deciBels referenced to an

isotropic antenna FH

Frequency Hopping

dBm

deciBels referenced to a

milliWatt FHSS

Frequency Hopped Spread

Spectrum

DCA

Dynamic Channel Allocation

FM

Frequency Modulation

DCCH

Dedicated Control Channel

FSK

Frequency Shift Keying

DCS-1800

Digital Communications

System - 1800 GGSN

Gateway GPRS Support Node

DL

Downlink

GMSK

Gaussian Minimum Shift

Keying

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DPM

Digital Phase Modulation

GPRS

General Packet Radio Service

DQPSK

Differential Quadrature Phase

Shift Keying GPS

Global Positioning System

DS

Direct Sequence

GSM

Global System for Mobile

Communication

DSSS

Direct Sequence Spread

Spectrum GSM 1800

A digital network working on a

frequency of 1800 MHz.

DTX

Discontinuous Transmission

HLR

Home Location Register

Eb/N0

Bit Energy-to-Noise Density

HSCSD

High Speed Circuit Switched

Data

IF

Intermediate Frequency

MSC

Mobile Switching Center

IMEI

International Mobile

Equipment Identity MSK

Minimum Shift Keying

IMSI


subscriber Identity N-AMPS

Narrowband Advanced Mobile

Phone System

IMT-2000


Telecommunication 2000 NMC

Network Management Center

IMTS

Improved Mobile Telephone

Service NSS

Network Switching Subsystem

IN

Intelligent Network

OFDM

Orthogonal Frequency Division

Multiplex

IP

Internet Protocol

OMC

Operations & Maintenance

Center

ISDN

Integrated Services Digital

Network. OQPSK

Offset Quadrature Phase Shift

Keying

ISI

Inter-Symbol Interference

OSI

Open System Interconnect

ITU

International

Telecommunications Union PA

Power Amplifier

LAN

Local Area Network

PABX

Private Automatic Branch

Exchange

LOS

loss of signal

PACS

Personal Access

Communications System

LOS

line of sight

PAM

pulse amplitude modulation

LPA

linear power amplifier

PBX

Private Branch Exchange

LSB

Least Significant Bit

PCH

Paging Channel

MAC

Medium Access Control

PCM

Pulse Code Modulation

17

MIN

Mobile Identification Number

PCN

Personal Communications

Network

MMM

Mobile Media Mode

PCS


Services

MMS

Multimedia Messaging

Service PCS


System

MS

Mobile Station

PDF

Probability Density Function

MSB

Most Significant Bit

PIN

Personal Identification Number

PLMN

Public Land-Mobile Network

SMS

Short Messaging Service

(Service Management System)

PMR

Private Mobile Radio

SNR

Signal-to-Noise Ratio

PN

Pseudo-Noise

SS

Spread Spectrum

PRMA

Packet Reservation Multiple

Access SS7

Signal System 7

PSK

Phase Shift Keying

SSD

Shared Secret Data

PSTN

Public Switched Telephone

Network TACS

Total Access Communications

System

QAM

Quadrature Amplitude

Modulation TAMS

Temporary Mobile Station

Identity

QPSK

Quadrature Phase Shift

Keying TCH

Traffic Channel

RACH

Random Access Channel

TCM

Trellis Code Modulation

RAN

Radio Access Network

TCP

Transmission Control Protocol

RF

Radio frequency

TDD

Time Division Duplex

RSSI

Received Signal Strength

Indication TDMA

Time Division Multiple Access

S/I

signal-to-interference ratio

TDTD

Time Division Transmit

Diversity

S/N

signal-to-noise ratio

UHF

Ultra High Frequency

SCCH

Signaling Control Channel

UL

Uplink

SCH

Synchronization Channel

UMTS

Universal Mobile

Telecommunications System

SDCCH

Slow Dedicated Control

Channel UWC

Universal Wireless Consortium

18

SDH

Synchronous Digital

Hierarchy VHF

Very High Frequency

SDMA

Space Division Multiple

Access VLR

Visitor Location Register

SHF

Super High Frequency

VOIP

Voice Over Internet Protocol

SIM Card

Subscriber Identity Module

Card VPN

Virtual Private Network

W3C

World Wide Web Consortium

WLAN

Wireless Local Area Network

WAP

Wireless Application Protocol

WLL

Wireless Local Loop

WCA

Wireless Communications

Association WOS

Wireless Office Systems

WCDMA

Wideband Code Division

Multiple Access WPABX

Wireless Private Automatic

Branch Exchange

WDM

Wavelength Division

Multiplexing

Documents

Telecommunication Basics