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Communications Q & A

COMMUNICATIONS  Q & A

Q. What is AMPS?
Q. 
What is GSM?
Q. 
What is TDMA?
Q.
What is CDMA?
Q. 
What is the difference between TDMA and CDMA?
Q.
What is PCS?
Q. 
What is an ESN? 
Q. 
What is meant by dual-mode? 
Q.
What is a dual-band phone? 
Q.
What is N-AMPS?
Q.
What is D-AMPS?
Q.
Are D-AMPS and N-AMPS compatible with AMPS?
Q.
What is GSM1900?
Q.
What is a SIM card?
Q.
What are the potential health hazards to using a portable wireless phone?
Q.
What is IRIDIUM?  What is GlobalStar?
Q.
What is EVRC?
Q.
 In CDMA what is meant by "slot cycle index"?
Q.
Which digital phones are made by Motorola for use in the U. S.?
Q.
Which digital phones are made by Nokia for use in the U. S.?
Q.
Where can I get more information about the Nokia 6190?
Q.
Which digital phones are made by Ericsson for use in the U. S.?
Q.
Which digital phones are made by Qualcomm for use in the U. S.?
Q.
Which digital phones are made by Sony for use in the U. S.?
Q.
Which digital phones are made by Samsung for use in the U. S.?
Q.
Which digital phone should I buy?
Q.
Which wireless carrier should I sign up with?
Q.
Where can I get more information about CDMA?
Q.
Where can I get a comparison of the Sony Z100 phone to the Qulcomm Q phone?
Q.
What are the URLs for the major wireless phone manufacturers?
Q.
Where can I get more information about GSM? 
Q.
Where can I get more information about Short Messaging Service?
Q. 
What other helpful URLs are available? 
Q.
What is A Carrier? 
Q.
What is A/B Switching?
Q.
What is Access Fee?
Q.
What is Activation?
Q.
What is Activation Fee?
Q.
What is Airtime?
Q.
What is Alphanumeric Display?
Q.
What is Analog?
Q.
What is APC (Adaptive Power Control)?
Q.
What is Area Code?
Q.
What is Authentication?
Q.
What is Automatic Call Delivery?
Q.
What is B Carrier?
Q.
What is Bandwidth?
Q.
What is Broadband?
Q.
What is BTA (Basic Trading Area)?
Q.
What is Call Forwarding?
Q.
What is Call Setup?
Q.
What is Call Waiting?
Q.
What is Caller ID?
Q.
What is Carrier?
Q.
What is Cell?
Q.
What is Cell Site?
Q.
What is Cellular?
Q.
What is CO (Central Office)?
Q.
What is Clone (Cloning)?
Q.
What is Coverage Area?
Q.
What is Cross-talk?
Q.
What is Decibel (dB)?
Q.
What is Digital?
Q.
What is Dual band?
Q.
What is Dual mode?
Q.
What is Duplex?
Q.
What is FCC (Federal Communications Commission)?
Q.
What is Fingerprinting?
Q.
What is Follow-Me Roaming?
Q.
What is Handoff ?
Q.
What is Hands-Free Speakerphone?
Q.
What is Handset?
Q.
What is Handshake(ing)?
Q.
What is Home Coverage Area?
Q.
What is Interconnection Fee?
Q.
What is Landline ?
Q.
What is LCD (Liquid Crystal Display)?
Q.
What is LED (Light Emitting Diode)?
Q.
What is Memory Dialing?
Q.
What is MSA (Metropolitan Service Area)?
Q.
What is MTA (Major Trading Area)?
Q.
What is MTSO (Mobile Telephone Switching Office)?
Q.
What is NAM (Number Assignment Module)?
Q.
What is No Answer Transfer?
Q.
What is No Service Indicator?
Q.
What is Off Peak?
Q.
What is Paging?
Q.
What is Peak Period(s)?
Q.
What is POTS (Plain-Old-Telephone-Service)?
Q.
What is Prepaid Cellular/Wireless?
Q.
What is PSTN (Public Switched Telephone Network)?
Q  
What is Radio-frequency fingerprinting?
Q.
What is RF (Radio Frequency)?
Q.
What is RFI (Radio Frequency Interference)?
Q.
What is RF Noise?
Q.
What is Roaming?
Q.
What is Roaming Agreement?
Q.
What is RSA (Rural Service Area)?
Q
.What is Service Area?
Q.
What is Service plan?
Q.
What is Sensitivity?
Q.
What is Signal-to-noise ratio?
Q.
What is SMS (Short Messaging System)?
Q.
What is Spectrum?
Q.
What is Spread Spectrum?
Q.
What is Standby Time?
Q.
What is Subscriber?
Q.
What is System Selection Switch?
Q.
What is Talk Time?
Q.
What is Telecommunications Act of 1996?
Q.
What is Toll Charges?
Q.
What is Toll-Free Calling Area?
Q.
What is Voice-activated Dialing?
Q.
What is Voice Mail?
Q.
What is Wireless Carrier?
Q. AMPS/TDMA 800/CDMA 800 Comparison ?


Q What is AMPS?  UP

A.  The Advanced Mobile Phone System (AMPS) is the analog system used
in the United States for cellular telephones.  It uses Frequency Modulation
(FM).  AMPS uses the FDMA air interface.  The channels are 30Khz wide.  The
frequency band for AMPS is 824Mhz to 849Mhz and 869Mhz to 894Mhz.  

Q What is GSM?

A.  GSM was established in 1982 as a European standard for digital wireless
communications. The first system was on line in 1991. GSM is now used in many
countries around the world.  The original name was Groupe Sp?ial Mobile, but
now the most accepted name is Global System for Mobile Communications.
GSM uses a combination of FDMA and TDMA.  FDMA:  The 25Mhz band is
divided into 124 frequencies of 200Khz each.  One or more of those frequencies
are assigned to each base station.  TDMA:  Each of those frequencies uses 8
time slots.

Q What is TDMA?

A .  Time Division Multiple Access is an air interface that allows mobile
stations to use the same frequency, but are separated by time slots.

Q What is CDMA?

A . Code Division Multiple Access is an air interface that allows mobile
stations to use the same frequency, but are separated by unique digital codes.
CDMA uses spread spectrum techniques. The standard (IS-95) was published
by the Telecommunications Industry Association (TIA) in July, 1993 and
revised to IS-95A in May, 1995. IS-95B is being developed now.  The channels
are approximately 1.25Mhz wide.

Q What is the difference between TDMA and CDMA?  UP

A
The first thing you have to learn is that "TDMA" is used frequently as a
direct reference to IS-136.  This is an ambiguous reference, since there
are actually three technologies that presently use a form of Time Division
Multiple Access. Be careful when talking with people who use TDMA in
this way.

Of the four competing technologies, IS-136 (Cantel), GSM (Fido), and iDEN
(Mike) use their own versions of TDMA. IS-95 (Bell Mobility & Clearnet PCS)
is an implementation of CDMA.

US Carriers:
  IS-136:  AT&T, BellSouth, Southwestern Bell
  GSM:    Omnipoint, Pacific Bell Mobile Service, others
  IS-95:    Airtouch, GTE, Bell Atlantic, Sprint PCS, Primeco, others]

As you have already guessed, the main difference between TDMA and CDMA is
how they share the spectrum. TDMA does so using by assigning each user on a
channel a different "slot" in time. IS-136 and iDEN have 3 slots per
channel, while GSM has 8 slots per channel. Note that a GSM channel is much
wider than an IS-136 or iDEN channel. Each user "takes turns" transmitting
and receiving in their designated time slot.

CDMA on the other hand has everyone on the channel transmitting and
receiving AT THE SAME TIME. Conventional wisdom would lead you to believe
this is impossible, but it works because of a modulation technique known as
Spread Spectrum. A CDMA channel is very wide (1.25 Mhz actually). Each user
is only transmitting a small amount of data, which would normally fit well
into a much smaller (narrow) channel. What the transmitter does is to take
this small number of bits and spread it out over the entire 1.25 Mhz
channel. It does so using an encoding technique that makes each user's bits
interfere very little with everyone else's. The receiver's job is to
"unspread" the bits and extract only the data from the desired user.

Because this wide channel can accommodate many different people using it at
the same time, the channel is said have "soft capacity", since the upper
limit on the number of users is determined strictly by how much interference
a subscriber is willing to endure. Up to a certain point, the level of
inter-user interference is well within the capability of the voice coding
algorithm to correct. In a TDMA system, the capacity is "hard coded" by the
number of slots allocated to a channel.

CDMA also offers a unique feature known as "soft handoff". TDMA systems use
what is known as a "hard handoff", since the connection with one site must
be broken and then a new connection created. CDMA systems keep your call
connected through 3 (the spec allows up to 6, but that isn't used) different
sites. Your phone can pick and choose between these 3 sites at any time, and
can in fact combine the signals from two or more sites at the same time.

It would take volumes to go into the necessary detail required to explain
the true differences. I therefore recommend you buy a book called "Wireless
Personal Communications Systems" by David J. Goodman. It's an Addison-Wesley
publication, and its ISBN number is 0-201-63470-8. This book is a marvelous
source of information about the various technologies (excluding iDEN) used
in North America.

Q  What is PCS?  UP

A.  The Federal Communications Commission (FCC) opened a new frequency
band for digital phones and named the new service Personal Communication
Services (PCS).  The band is generally referred to as the 1900Mhz (1.9Ghz)
band.  The band is from 1850Mhz to 1990Mhz.

Q  What is an ESN?

A.  The Electronic Serial Number is a 32-bit number that is stored in the
phone. It is used, along with other numbers, to identify your phone.

Q  What is meant by dual-mode?

A.  A dual-mode phone operates on two modes.  Usually this refers to
phones that use digital and analog, however it also pertains to phones that
operate on AMPS and N-AMPS.

Q  What is a dual-band phone?

A.  A dual-band phone operates on the cellular band (800Mhz) and the
PCS band (1900Mhz).

Q  What is D-AMPS?

A.  The Digital Advanced Mobile Phone System is similar to GSM.
D-AMPS uses the TDMA air interface.  The main difference between GSM
and D-AMPS is that GSM uses 8 time slots rotated at 214 times per second
and D-AMPS uses 3 time slots rotated at 50 times per second.  The standard
for D-AMPS is IS-136.

Q  What is N-AMPS?

A .  Narrow-band Advanced Mobile Phone Service was developed by
Motorola.  The 30Khz channels used in AMPS were divided into three
10Khz channels to add more capacity to the cellular system.

Q  Are D-AMPS and N-AMPS compatible with AMPS?  UP

A.  Yes.  All D-AMPS and N-AMPS phones must be fully compatible with
AMPS systems.  In addition, any system that is using D-AMPS or N-AMPS must
also provide AMPS.  You can use either of those phones all over the United
States.

Q  What is GSM1900?

A.  It is the GSM system used in the United States on the PCS band.

Q  What is a SIM card?

A.  The SIM (Subscriber Identity Module) card is a "smart card" used by
a subscriber to GSM.  The card contains information about the user and can be
plugged into another GSM phone.  This allows the user to use another GSM
phone as if it was his/her own phone.

Q  What are the potential health hazards to using a portable wireless phone?

A.  The 'short' answer is that there is no known health hazards associated with
the proper use of portable wireless phones. For more technical information on this
subject go to http://www.fcc.gov/oet/.  The Office of Engineering and Technology
(OET) has a number of bulletins on the subject.  The two that you want to start
with are OET56 and OET65C.  OET56 gives a lot of other references.

Q  What is IRIDIUM?  What is GlobalStar?

A.  The IRIDIUM and GlobalStar systems will use low earth orbit satellites
for wireless communication. A special handset will allow the user to communicate
via ground based cellular or by satellite. For the latest information see:
http://www.iridium.com
http://www.globalstar.com

Q  What is EVRC?

A.. [Credit:  Bill Walker]
EVRC is the Enhanced Variable Rate Coder.  It is an 8 kbps vocoder
that's supposed to sound about as good as the current 13 kbps vocoder.
Thus, you can have the same voice quality while improving the capacity
of the system (which can handle more 8 kbps calls than 13 kbps calls.
As far as I know, the only place it's currently commercially deployed
is Korea.

Q  In CDMA what is meant by "slot cycle index"?  UP

A.  [Credit: Bill Walker]
On the CDMA Paging Channel (this is the shared channel that all phones
listen to for incoming calls and other control info), time is divided into
"slots".  To conserve power, phones that are currently idle only "wake up"
and listen for messages on the Paging Channel during their assigned
slots.  The slot cycle index determines how often the phone's slot comes
around.  If the slot cycle index is 0, the phone wakes up every 1.28
seconds.  If it's one, it wakes up every 2.56 seconds.  If it's two, it's
every 5.12 seconds, and so on.  The larger the setting, the more power is
conserved, but the longer it takes to page the phone for an incoming
call.  You can imagine that if it were set to 10.24 seconds, few callers
would hang on the line long enough for  you to answer your phone.

There are two settings that govern this.  One is the "preferred slot cycle
index" in the phone, and can be set via service programming.  The other is
the "maximum slot cycle index" set in the base station and broadcast in
overhead messages on the Paging Channel.  The phone has to use whichever
number is smaller.

Q  Which digital phones are made by Motorola for use in the U. S.?

[For updates, see A 5.3 for Motorola's URL]
A.  M75  800Mhz/AMPS/TDMA
           M70  800Mhz/AMPS/TDMA
           GSM 1.9 StarTAC(tm) 8500g/8000g  1900Mhz/GSM(TDMA)
           MicroTAC Select(tm) 6000e  1900Mhz/GSM(TDMA)
                    "               "         3000e         "           "          "
                    "               "         2000e         "           "          "
           MicroTAC(tm) SC-725  This is a CDMA phone.

Q  Which digital phones are made by Nokia for use in the U. S.?  UP

[NOTE: I no longer update the following list.  See A 5.3 for Nokia's URL]
A.  Nokia 2120  800Mhz/TDMA/AMPS (IS-54B)
           Nokia 2160       "            "           "     (same as 2120 but added IS-136 support)
           Nokia 2168       "            "           "     (IS-136)
           Nokia 2180  800Mhz/CDMA/AMPS (IS-95)
           Nokia 2190  1900Mhz/GSM(TDMA)
           Nokia 6120  800Mhz/TDMA/AMPS
           Nokia 6160  1900Mhz/TDMA and 800Mhz/TDMA/AMPS chosen in
                                that order. (Credit: Norman F. Smith)
           Nokia 6190  see A 3.2a

A .a  
Nokia 6190 is a GSM1900 handset.  It comes with a detachable analog module,
which (when inserted between the phone and battery) allows it to be used on
AMPS network.  AMPS is the old analog system which operates at 800 MHz.  So,
Nokia 6190 truly is a dual mode (GSM/AMPS) and dual band (1900/800) unit.

A .b
GSM Datacards and AMPS/DAMPS modems

The Nokia 2190 with a data card  works like this.  Since GSM networks
are all digital to start with no modem is necessary to convert to an
analog signal.  The data card acts as an interface between where the
computing device expects a modem to be and the phone.  Newer products
"Soft Modem" to eliminate any need for a hardware interface.
For GSM, basically you can say that there is no modem since nothing is
being MOdulated and DEModulated at your location. As your transmission
 is sent over the phone lines it hits a modem only when it reaches a stretch of
analog line.

If using the Nokia 2160 or 2180, the analog modems for the AMPS/DAMPS
system do basically the same thing in digital mode with the addition of
analog support. In analog support mode, you are basically just making a
regular call as if you would dialing out though a regular land line. The
average speeds in analog mode are 2400 to 4800 Bps.

You must of course dial into a special number in order to use the
digital mode for both systems. The average speeds in digital mode are
9600 to 14400 Bps.

Q  Where can I get more information about the Nokia 6190?  UP

A.  Steve Punter has a Web page dedicated to the Nokia 6190.
http://www.globalserve.net/~punter/Nokia6190.htm

Q  Which digital phones are made by Ericsson for use in the U. S.?

[NOTE:  I no longer update the following list.  See A 5.3 for Ericsson's URL]
A.  PD 328 & PD 398  Dual-band, Dual-mode.  AMPS & TDMA on 800 Mhz,
                                          TDMA only on 1900 Mhz.  Both phones are only
                                           available through Southwestern Bell.
           LX 77 & LX 100  Same specs as above, but only available through
                                         AT&T Wireless Services.
           DH 318, DH 368, DH 388  Listed as "Dual-mode".  Assume this means
                                         800Mhz/TDMA/AMPS
           CH 388 & CF 388  1900Mhz/TDMA (GSM-1900 phones)

Q  Which digital phones are made by Qualcomm for use in the U. S.?

[NOTE:  I no longer update the following list.  See A 5.3 for Qualcomm's URL]
A.  QCP-820  800Mhz/CDMA/AMPS
           QCP-1920  1900Mhz/CDMA
           QCP-2700  800Mhz/AMPS  1900Mhz/CDMA
            Q Phone  1900Mhz/CDMA
           Q800  800Mhz/CDMA/AMPS

Q  Which digital phones are made by Sony for use in the U. S.?

[NOTE:  I no longer update the following list.  See A 5.3 for Sony's URL]
A.  CM-M1300 800Mhz/CDMA/AMPS
           CM-S1101  1900Mhz/CDMA
           CM-B3200  800Mhz/AMPS  1900Mhz/CDMA
           CM-Z100  1900Mhz/CDMA  (very small..3.6" x 2.4" x 1", 5.3 oz.)
I have also seen posts giving CM-2100 as the model number for the CM-S1101. The
numbers listed above are taken directly from the shipping boxes on 3/23/98.

Q  Which digital phones are made by Samsung for use in the U. S.?  UP

[NOTE:  I no longer update the following list.  See A 5.3 for Samsung's URL]
A.  Samsung makes a model SCH-1000 and a model SCH-1900.  Both are 1900mhz,
CDMA only.

Q  Which digital phone should I buy?

A.
Which phone is "better" will depend more on the service provided by a
given carrier than the actual piece of equipment you hold in your
hand.

So backing up a bit, here is the way to answer your question:

First, investigate the various wireless carriers in your area. Look up
their price plans, get feedback from customers about their coverage
and reliability, and then finally see what kind of phones they offer.

Then, and only then, it starts to make sense to think about which
model of phone. You may well find the decision has already been made
for you--most digital carriers sell only certain phones that work with
their service.

 

Q  Which wireless carrier should I sign up with?

A.  See A 3.7.

V  HELPFUL URLs

Q  Where can I get more information about CDMA?

A.  Qualcomm, Inc.:  http://www.qualcomm.com
           CDMA Development Group:  
http://www.cdg.org

Q  Where can I get a comparison of the Sony Z100 phone to the
Qualcomm Q phone?
 

A.  http://www.geocities.com/yosemite/6686/sprintpcs.htm

Q30  What are the URLs for the major wireless phone manufacturers?  UP

A .  Qualcomm:  http://www.qualcomm.com
           Motorola:  
http://www.mot.com
           Nokia:  
http://www.nokia.com
           Ericsson:  
http://www.ericsson.com
           Samsung:  
http://www.samsung.com
           Sony:  
http://www.sel.sony.com/SEL/consumer/

Q  Where can I get more information about GSM?

A.  http://kbs.cs.tu-berlin.de/~jutta/gsm/js-intro.html
           
http://www.gsmworld.com

A .a  (Special Thanks to:  George Czajkowski)
GSM Memorandum of Understanding Association
(official GSM page, includes history of GSM):
http://www.gsmworld.com

Overview of the Global System for Mobile Communications (GSM):
http://ccnga.uwaterloo.ca/~jscouria/GSM/

An Introduction to GSM:
http://www.bellsouthdcs.com/balston.html

Global Systems for Mobile Communications (GSM): Services and Architecture:
http://www.dg-tech.com/gsm.htm

GSM Security and Encryption (technical paper):
http://www.semionoff.com/cellular/hacking/phreaking/gsm-secur.html

GSM Information:
http://www.bit.net.au/~nogi/gsm/

Robert's GSM Information Page:
http://huizen.dds.nl/~elsinga/gsm/

Cellular GSM Phones:
http://www.geocities.com/CapeCanaveral/2042/nokia.html

GSM all over the world (links to GSM related sites):
http://www.webring.org/cgi-bin/webring?ring=gsm;list

GSM Mobile Page in English:
http://hem.passagen.se/borjeg/index-en.htm

GSM North America:
http://www.communicreate.com/gsmnew.htm

GSMag International:
http://www.gsmag.com/

Q Where can I get more information about Short Messaging Service?

A.
GPA Technology Pty. Ltd.
http://www.winpos.com/SMS/sms.htm

Q What other helpful URLs are available?  UP

A .
Steve Punter's page.  Contains lots of interesting info.  Check it out!
http://www.arcx.com/sites

Comparisons of phones and services - national
http://www.wirelessoutpost.com
http://www.wirelessdimension.com

Comparisons of phones and services - Boston
http://www.picante.com/~gtaylor/cellphones.html

Description of CDMA technology
http://www.cdg.org/a_ross/

Wireless Today industry links
http://www.wirelesstoday.com/links.htm

Cellular Phone Information For Beginners
http://web.idirect.com/~aaa/p0000003.htm

 

 


Q.
A Carrier  UP

Most areas of the US have two cellular carriers, each of which operates on a different frequency band. One is designated the "A" carrier and the other is designated the "B" carrier. In some markets there may be only one carrier which may be "A" or "B".


Q.
A/B Switching

Most cellular phones have the ability to switch to the "A" or the "B" frequency bands. This feature is useful when roaming outside your home coverage area.


Q.
Access Fee

A monthly charge for the ability to connect to a wireless network. This fee is assessed monthly whether the phone is actually used or not.


Q.
Activation

Configuration of a wireless phone so that it is ready to be used to transmit and receive calls on the wireless network.


Q.
Activation Fee

A one-time up-front charge for activation of a wireless phone.


Q.
Airtime

Total time that a wireless phone is in connected and in use for talking. This includes use for calls both received and placed.


Q.
Alphanumeric Display   UP

A display, usually LCD, that has the ability to display both text and numbers. Most often found on the front of a wireless handset or pager.


Q.
Analog

A method of modulating radio signals so that they can carry information such as voice or data.


Q.
Antenna

A device that facilitates the transmission and reception of radio signals.


Q.
APC (Adaptive Power Control)

A feature of some wireless handsets that helps reduce power consumption to increase battery charge life.


Q.
Area Code

A three digit telephone number prefix assigned to a calling area.


Q.
Authentication    UP

A feature used to reduce fraud by confirming the identity of a phone to the wireless network.


Q.
Automatic Call Delivery

A service feature that allows a user to receive calls when roaming outside of the phone's home coverage area.


Q.
B Carrier

Most areas of the US have two cellular carriers, each of which operates on a different frequency band. One is designated the "A" carrier and the other is designated the "B" carrier. In some markets there may be only one carrier which may be "A" or "B".


Q.
Bandwidth

Describes the transmission capacity of a medium in terms of a range of frequencies. A greater bandwidth indicates the ability to transmit a greater amount of data over a given period of time.


Q.
Broadband

Describes a communications medium capable of transmitting a relatively large amount of data over a given period of time. A communications channel of high bandwidth.


Q.
BTA (Basic Trading Area)   UP

A geographic region defined by a group of counties that surround a city, which is the area's basic trading center. The boundaries of each BTA were formulated by Rand McNally & Co. and are used by the FCC determine service areas for PCS wireless licenses. The entire US and some of its territories is divided into 493 non-overlapping BTAs.


Q.
Call Forwarding

A feature that allows the transfer of incoming calls to another number of the users choice.


Q.
Call Setup

Activity that occurs in order to establish a call connection between a wireless handset and the wireless system.


Q.
Call Waiting

A feature that allows a user to be notified of another incoming call while a call is already in progress, and gives the user the ability to answer the second call while the first call remains on hold.


Q.
Caller ID

A feature that displays a caller's telephone number and/or name before the call is answered.


Q.
Carrier    UP

A company that provides telecommunications services.


Q.
CDMA (Code Division Multiple Access)

A digital communication technology used by some carriers to provide PCS service. Other technologies used are TDMA and GSM.


Q.
Cell

The area surrounding a cell site. The area in which calls are handled by a particular cell site


Q.
Cell Site

The transmission and reception equipment, including the base station antenna, that connects a cellular phone to the network.


Q.
Cellular
The type of wireless communication that is most familiar to mobile phones users. Called 'cellular' because the system uses many base stations to divide a service area into multiple 'cells'. Cellular calls are transferred from base station to base station as a user travels from cell to cell.


Q.
CO (Central Office)    UP

A connection point between the wireless phone system at the MTSO and the landline phone system at the PSTN.


Q.
Clone (Cloning)

A wireless phone that has been programmed to mimic another wireless phone. Often used to defraud a wireless carrier by placing illegal calls without any intention of payment.


Q.
Coverage Area

The geographic area served by a wireless system. Same as Service Area.


Q.
Cross-talk

A signal leak from one channel to another - often the cause of noise and distortion.


Q.
Decibel (dB)

A unit of measure used to express relative difference in power or intensity of sound.


Q.
Digital

A method of encoding information using a binary code of 0s and 1s. Most newer wireless phones and networks use digital technology.


Q.
Dual band    UP

A feature on some wireless phones that allows the handset to operate using either the 800 MHz cellular or the 1900 MHz PCS frequencies.

Q. Dual mode

A feature on some wireless phones that allows the handset to operate on both analog and digital networks.


Q.
Duplex

As in ordinary telephone service, a characteristic of a communications system where simultaneous transmission and reception is possible.


Q.
email

The ability to send and receive text messages through a wireless handset.


Q.
FCC (Federal Communications Commission)

A US government agency responsible for regulating communications industries.


Q.
Fingerprinting    UP

See Radio-frequency fingerprinting.


Q.
Follow-Me Roaming

The ability of a wireless system to forward incoming calls to a handset that is roaming outside its home service area without any pre-notification to the wireless carrier.


Q.
Handoff

The transfer of a wireless call in progress from one transmission site to another site without disconnection.


Q.
Hands-Free Speakerphone

A feature of some wireless phones that allows the users to talk and listen to calls without holding the phone against their head.


Q.
Handset    UP

Any hand held device used to transmit and receive calls from a wireless system. Also known as a wireless phone, a cellular phone, a mobile phone, a PCS phone and many other terms.


Q.
Handshake(ing)

Signals between a wireless phone and a wireless system to accomplish call setup.


Q.
Home Coverage Area

A designated area within which cellular calls are local and do not incur roaming or long distance charges.


Q.
Interconnection Fee

A fee charged for calls from wireless phones that must be routed to landline phones.


Q.
Landline

Traditional wired telephone service.


Q.
LCD (Liquid Crystal Display)

A flat panel screen used to display numbers and/or characters. Often found on a wireless handset.


Q.
LED (Light Emitting Diode)    UP

A light on a handset to alert the user of various conditions.


Q.
Memory Dialing

A feature of a wireless phone that allows multiple numbers to be stored in the phone itself for quick dialing by pressing one or two buttons.


Q.
MSA (Metropolitan Service Area)

An area defined by the US government for use in grouping census data and other statistics. MSAs include a city of at least 50,000 people or an urbanized area of at least 100,000 people and the counties that include these areas. Not all areas of the US are in an MSA. The FCC used these area definitions to license cellular telephone service carriers. There are 306 regions of the US designated as MSAs.


Q.
MTA (Major Trading Area)

An area consisting of two or more Basic Trading Areas as defined by Rand McNally & Co. These large areas are used by the FCC determine service areas for some PCS wireless licenses. The US is divided into 51 MTAs.


Q.
MTSO (Mobile Telephone Switching Office)

An office housing switches and computers to which all cell sites in an area are connected for the purpose of eventual connection to the PSTN. The MTSO handles the connection, tracking, status and billing of all wireless call activity in an assigned area.


Q.
NAM (Number Assignment Module)    UP

A component of a wireless phone that holds in electronic memory the telephone number and ESN of the phone.


Q.
No Answer Transfer

A feature of a wireless service that if a call is not answered in a specified number of rings, it will be transferred to another phone number of the users choice.


Q.
No Service Indicator

A feature of wireless phones that tells the user that wireless service is unavailable in a particular location. Usually an LED on the handset.


Q.
Off Peak

Any time of day, as determined by a wireless carrier, when there is lower communications traffic on the system. Carriers make this distinction to offer lower rates during these periods when demand is low.


Q.
Paging     UP

A feature of a wireless device that allows reception of a signal or alphanumeric message.


Q.
Peak Period(s)

Any time of day, as determined by a wireless carrier, when there is high levels of communications traffic on the system.


Q.
POTS (Plain-Old-Telephone-Service)

Another name for traditional wired, land based telephone service.


Q.
Prepaid Cellular/Wireless

A service plan offered by some wireless carriers that allows subscribers to pay in advance for wireless service.


Q.
PSTN (Public Switched Telephone Network)

A formal name for the world-wide telephone network.


Q.
Radio-frequency fingerprinting

An electronic process that identifies each individual wireless handset by examining its unique radio transmission characteristics. Fingerprinting is used to reduce fraud since the illegal phone can not duplicate the legal phone's radio-frequency fingerprint.


Q.
RF (Radio Frequency)    UP

A radio signal.


Q.
RFI (Radio Frequency Interference)

An undesired radio signal that interferes with a radio communications signal causing extraneous noise and/or signal dropouts.


Q.
RF Noise

Undesired radio signals that alters a radio communications signal causing extraneous sounds during transmission and/or reception.


Q.
Roaming

Using your wireless phone in an area outside its home coverage area. There is usually an additional charge for roaming.


Q.
Roaming Agreement

A agreement among wireless carriers allowing users to use their phone on systems other their own home systems. Roaming Fee charged for roaming.


Q.
RSA (Rural Service Area)     UP

Areas not included in MSAs are divided into RSAs. Generally these are the rural areas of the US. The FCC used RSAs to license cellular carriers in areas not included in MSAs. There are 428 RSAs in the US.


Q.
Service Area

The geographic area served by a wireless system. Same as Coverage Area.


Q.
Service plan

A contract between a wireless carrier and a wireless subscriber that details the terms of the wireless service including rates for activation, access and per minute usage.


Q.
Sensitivity

A measure of a receiver's ability to viably receive weak radio signals.


Q.
Signal-to-noise ratio

A measure of the power of a signal versus noise. A lower ratio means there is more noise relative to signal.


Q.
SMS (Short Messaging System)    UP

A feature of PCS phones(primarily GSM) that allows users to receive and sometimes transmit short text messages using their wireless phone.


Q.
Spectrum

The the entire range electromagnetic frequencies.


Q.
Spread Spectrum

A communications technology where a signal is transmitted over a broad range of frequencies and then re-assembled when received.


Q.
Standby Time

The time a phone is on but not actively transmitting or receiving a call.


Q.
Subscriber

A cellular phone user.


Q.
System Selection Switch

A feature of some cellular phones that allows switching between 'A' and 'B' cellular carriers. This feature is often used when roaming.


Q.
Talk Time    UP

The time a phone is on and actively transmitting or receiving a call.


Q.
Telecommunications Act of 1996

Federal legislation passed in 1996 intended to increase competition among wireless and wireline carriers for the benefit of consumers.


Q.
Toll Charges

Charges for placing long distance calls.


Q.
Toll-Free Calling Area

An area in which calls can be placed without incurring long distance charges.


Q.
Voice-activated Dialing     UP

A feature that allows users to speak words into a wireless phone to cause it to dial pre-programmed telephone numbers without using the buttons.


Q.
Voice Mail

A system that answers calls and allows users to reply to, save, delete or forward messages.


Q.
Wireless Carrier

A company that provides wireless telecommunications services


AMPS/TDMA 800/CDMA 800 Comparison

Frequency Range
of operation
(MHz)

Insertion
Loss
(dB) max.

Ripple in
BW (dB)
max.

V.S.W.R.
in BW
max.

Attenuation
dB min
(MHz)

Input
power
(W)

Dimensions
HxWxL
(mm)

TX

824-849

2.4

1.5

2.0

50

869-894

3.0

5.9x14.5x39.5

RX

869-894

3.5

1.2

2.0

47

824-849

TX

824-849

2.5

1.2

2.0

55

869-894

3.0

5.9x15.0x45.0

RX

869-894

3.8

1.5

2.0

50

824-849

TX

824-849

2.5

1.0

2.0

50

869-894

3.0

8.5x12.0x55.1

RX

869-894

3.5

1.5

2.0

55

824-849

TX

824-849

2.5

1.0

2.0

60

869-894

7.0

8.5x12.0x61.3

RX

869-894

3.0

1.5

2.0

60

824-849

 

TX

824-849

2.2

1.0

1.8

65

869-894

12.0

13.0x15.0x62.0

RX

869-894

3.5

1.2

1.8

60

824-849

13.0x15.0x62.0

 

TX

824-849

2.5

1.5

2.0

38

869-894

3.0
average

5.0x11.0x19.0

RX

869-894

4.0

1.6

2.0

45

824-849

TX

824-849

3.0

1.7

2.0

42

869-894

3.0
average

5.0x11.0x19.0

RX

869-894

3.8

1.8

2.0

42

824-849