23-Nov-09, 01:39 PM
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Wireless Telephone Service on Campus
[Creation Date: 10-May-00]
Wireless Telephone Service on Campus
By Joan M. Bonner
OIT/Voice Processing
Wireless communications is based on the ability of user equipment to
transmit radio broadcasts through the airways that are received by other
wireless or wireline equipment. Wireless networks can be land-based or
satelite based. In both cases, the user information is transported via
Radio Frequency.
Cellular Communications
Cellular communications provide users with expansive flexibility when
compared to traditional wireline services. The cellular concept divides
an area into a pattern of cells, each served by a base station with its
own antenannas, transmitters and receivers, and asociated electronics.
The components of a cellular system include cellphone, multiple cell
sites, a Mobile Telephone Switching Office (MTSO) and the public
(wireline) network. A call placed from a cellular phone arrives at a
low powered transceiver which designates an appropriate cell. All cells
connect to the MTSO, which connects to the public telephone network.
The same process happens in reverse when a caller using a regular phone
places a call to a cellular phone. Because each cell is linked to the
next via a computer, a call is automatically switched from one cell to
the next while the caller is driving. A transmitting-receiving tower is
located on campus and provides cellular service from both CellularOne
and Verizon Wireless.
Choosing a Cellular Phone
The four top reasons why people subscribe to cellular service are:
- Safety
- Convenience
- Time Saving
- Accessibility
If you've never had a cellular phone, how do you choose one? First you need to answer a few simple questions:
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- When am I going to use the phone? Mostly during the day, at night or on weekends?
How often do I plan on using the phone? A lot or occassionally?
Will I use it in the car or do I want to be able to take it anywhere?
What will I use the phone for? Work or just an emergency?
The purpose of answering the above questions is to assist you in determining the ideal cellular phone for your needs.
Four types of cellular phones
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- Mobile phones - in your car
- Permanently installed in the vehicle
- A full 3 watts of power and an outside antenna to provide the best possible reception
- Standby and talk times are unlimited because the phone is powered from the carÕs battery
- Great for people who need to use their phone only in their car
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- Transportable phones - in or out of your car
- Semi-permanent vehicle installation or portable capability
- Phone has its own battery which is usually large and heavy
- Full 3 watt models that can be connected to an outside antenna
- Used by people who need the best transmission when away from their car or who frequently travel in a fringe area
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- Portable phones - in your hand or on your hip
- Designed for portable use but can be adapted for automobile use
- Powered from a rechargeable battery
- Can be charged at home with an overnight charger or in the car with a vehicle power adapter
- Six tenths of a watt of power is enough in most areas
- Used by people who want the freedom to use their phone out of their car and donÕt want to carry a heavy bag phone
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- Microportable phones - in your pocket
- Same as portable but even smaller, usually less than 8 ounces
- Usually purchased by a business user who will want to take full advantage of the features and size of these phones
- Some of these units provide battery times comparable to portables, but at a lot less weight and size
- The microportables are usually more expensive because thy may contain a lighter weight battery or more features.
Analog vs. Digital Service
Currently, most cellular telephony is based on analog transmission at
800 MHz . However, digital services are becoming more available
throughout the US and the major cellular service providers are planning
for such a move. One reason is that digital cellular can offer
subscribers the benefits of enhanced services such as increased call
reliability, greater voice clarity, inherent privacy, voice messaging,
Caller ID and longer talk time as well as FAX and data capabilities.
A dual mode phone provides both analog and digital service. This will
allow you to use existing analog cellular service where digital does not
yet exist. Although most service areas will be digital someday, not all
markets are digital now. You will also need to make sure you get the
right type of digital phone for the system where you will be using the
service. Generally you will want either a TDMA or a CDMA dual-mode
phone.
The Technologies Today
There are three important digital cellular standards in the world. Time
Division Multiple Access (TDMA), Code Division Multiple Access (CDMA),
and Europe has Global System for Mobile Communication (GSM). In TDMA,
the available spectrum is sliced into a number of frequency channels,
each of which is shared by multiple users at one time. TDMA maintains
separate frequency channels, subdivided in time. TDMA allows efficient
utilization and permits digital islands to be installed where necessary
to support the existing analog network. CDMA is a variation on spread
spectrum developed for military communications. Each user is assigned a
unique code to identify and separate calls sharing the same frequency at
the same time. Users share one wide frequency band, using unique codes
to identify and separate calls. GSM is the operating cellular system in
many countries outside the United States where subscribers roam without
borders. GSM offers the convenience of one phone number enabling users
to be contacted wherever they may be traveling, providing GSM coverage
is available.
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TDMA phones are idle between bursts, consuming less power than analog phones. Subscribers can talk nearly twice as long without a battery change.
CDMA utilizes a patented method of handing off calls between cells, know as "soft handoff." This method dramatically reduces the chances of call disruptions during handoff or of dropped calls due to a failed handoff.
GSM operates on a different frequency than US cellular service and US cellular phone service will not operate overseas.
In the future, satellite and Personal Communications Service (PCS) will
continue to emerge, offering additional choices in technology. PCS is a
comprehensive communications service that offers services through
micro-cellular technology. PCS subscribers carry low-power, pocket
sized phones that are operational within a short distance (a few hundred
feet) of a transmitter. PCS features advanced applications such as
custom call screening and call blocking. Some analysts believe that
when fuly implemented, PCS may replace conventional wired
telecommunications based on location to location dialing for voice and
data transmissions. Callers will dial person-to-person instead, since
phone numbers will be assigned to people, not to places. A personal
number will be the same wherever the person is located.
Airtime charges on a mobile originated call begin when connection to the
cellular net is established. Each partial minute of airtime is billed
as a full minute. The user is responsible for airtime, monthly access
fees, long distance, toll, and roaming charges. Service activation
requires credit approval. There is an early termination fee for
contracts cancelled prior to the expiration of a 12-month contract.
How can I get more information?
To receive an information packet, coverage
maps or the current monthly specials on equipment with either
CellularOne or Verizon Wireless, please call the Telecommunications
System Office at 545-4706. To receive faxed documents, call 577-0098
and choose option 2. Personal or Corporate users interested in
CellularOne can also call Tom Honecker direct at 413-626-7874. Personal
or Corporate users interested in Verizon Wireless service can reach
David Martin at 413-531-5100.
Contact Information
Telecom Web Administrator
tech-services@oit.umass.edu
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