Wireless Data Communications for Beginners
- Empower yourself to Make the Right Decisions -
Thinking about mobile computing? If you are on
the road in North America, then WIRELESS connectivity may be the
answer. We are providing an overview of connecting to the
Internet using wireless technology, which will help you make an
informed decision to meet your needs.
When choosing wireless connectivity for remote data access, the
most important considerations are:
Coverage -- Places from where you can connect.
Speed -- The speed of your connection.
Set-up Costs -- Initial setup costs including equipment.
Monthly Costs -- On-going costs associated with the service.
Currently in North America, there are three (3) ways mobile
computing users gain wireless access to the Internet while on the
road. They are:
1. Satellite
2. Wi-Fi
3. Cellular
Two-way Satellite communication, where you can send and
receive data using a Satellite is the best solution money can
buy. While you cannot use it in motion or in extreme weather
conditions, basically from anywhere (within the satellite
footprint) across the nation where you have a direct line of sight
to the Southern sky (this is because the satellites are positioned
hundreds of miles above the equator in a geo-stationary orbit) you
would be able to establish data connections using a dish antenna. Users typically experience connection speeds of
400-1000Kbps for receiving, with slowest speeds during prime time.
Sending speeds are modem-like, ranging from 20-80kbps. This
premium performance comes with a hefty price tag. Initial setup
cost can be upwards of $5,000 with a $99 per month charge for
unlimited use. Each provider offers a custom hardware solution and
it is generally not compatible across two providers.
Wi-Fi / 802.11x is another technology
becoming
popular. It is used in businesses to create or extend the office
LAN to devices where hard wiring is either not feasible or
impractical. It also provides the added benefit of untethered
mobility within close proximity of the Wi-Fi access points. In
homes Wi-Fi has become popular for providing a shared access to
the Internet for more than one computer, without having to wire
them together. While Wi-Fi eliminates the need for wiring each
user (biggest attraction), this method requires the user to be in
close proximity of the Wi-Fi access point. A private Wi-Fi access
point (AP) installed in home is generally secured by enabling
encrypted transmission between the access point and connected
devices. This effectively excludes anyone from outside trying to
break into and gaining control of the in home network and attached
devices / computers.
Wi-Fi Hotspots on the other hand are left open
with no encryption enabled to allow easy access for the patrons.
This however brings with it added security considerations. Wi-Fi
hotspot users must be conscious of security, as anyone else with a
Wi-Fi adaptor and some software (which is readily available) can
intercept and record their transmission. It is therefore very
important to learn about ways to protect your information when
using public Wi-Fi hotspots. Also, it is essential whenever you
transmit sensitive information, such as online banking or credit
card number, that you access website pages starting with https:
and not just http:. The extra “s” is what does the magic and
ensures that your transmission is secure. Also a Firewall, which
is an added level of security and can be setup in your computer or
your internal network, is highly recommended as it prevents
anyone from outside gaining control of your computer.
As far as
speed is concerned, do not get fooled
by the touted transmission speed of Wi-Fi which is 11 or 54 Mbps
depending on the variant being used. Rather the connection
throughput you will experience would be mostly determined by
throughput of the link into the Internet from the Wireless network
and by number of users using it at the time.
Starbucks, MacDonald’s, RV campgrounds, Flying J
truck stops are all examples of establishments offering this mode
of Internet access to their patrons in and around their
establishment.
As more and more Wi-Fi Hotspots come online and
roaming and billing on them becomes unified, this method of
Internet access on the road will become more and more prevalent.
Cellular access is most popular among mobile
users mainly because of lower cost and familiarity with cell phone
use. It also provides a range of connection speeds and cost mix
which allows the user flexibility in choosing the right
combination to satisfy their needs. However to make the right
choice, it is helpful if you understand the different technologies
in use by the Cellular Service Providers, their corresponding
coverage and implications.
Analog Cellular – Generation 1
Back in 1983 when first commercial cellular
service in the US was made available by Ameritech in the Chicago
area, the technology deployed was Analog called AMPS cellular.
The AMPS cellular networks still in use today, therefore covers
most of the nation providing coverage in excess of 95%+ of the
geographic area. Data connection speeds using AMPS cellular
network are typically 9.6 Kbps and can range from 4.8 – 14.4 Kbps
depending on the signal strength. Data calls by the network are
treated the same as voice calls and are billed by minutes of use.
This is great for users who have free unlimited weeknights and
weekend minutes in their plans. While each AMPS cell tower can
cover a wide geographic area (why AMPS is still the only coverage
available in rural areas) it is limited in the number of calls it
can support at the same time. (Capacity)
Digital Cellular – Generation 2
Capacity was the major reason why service
providers in addition to their AMPS networks started to use
Digital cellular technologies in early 1990s. While it provided
increased capacity and call security, its use limits the area each
cellular tower can cover. Hence the build out of these
technologies like CDMA which started in 1996 has still only
reached around 70% of the nation’s geographical area. Coverage is
focused around urban areas and busy corridors between cities.
This is the reason why most Cellular Service Providers supply Dual
Mode (Digital + AMPS) cell phones to allow for the most possible
places from where a cellular call can be made. Data connection
speed using Digital cellular network is set at 14.4 Kbps all the
time. While Data calls are treated differently from voice calls
by the network, they are still billed by minutes of use. TDMA,
CDMA, iDEN and GSM are examples of technologies implemented. Major
technologies in use in North America at the time were TDMA (AT&T,
BellSouth, SBC ...) and CDMA (Bell Atlantic Mobile, GTE, Sprint
...)
Always On – Generation 2.5
Increased Data connection speeds and more capacity was yet
again the reason for the networks to implement upgrade of
technology starting 2001. These technologies for data moved
to packet data connections billed by amount of data transferred
rather than minutes of use or connection time. Data
connection throughput typically now matches or exceeds that of
landline 56 Kbps connections (60 Kbps – 80 Kbps downloads),
however the user needs to subscribe to a separate data plan ($79
per month currently for unlimited usage or less for use up to a
maximum amount as specified by the plan. Anything above has to be
paid extra much like your voice plan if not unlimited). Also
packet data connections while not restricted by connection time
are shared data connections. This means that in peak times
when there could be many users doing data within a cell coverage
area, this would result in lower than typical data connection
throughput experienced by each user. Coverage is similar to
the basic digital network. GSM-GPRS and CDMA 1X are examples
of technologies implemented.
A major change which occurred in North America
leading to the implementation of GEN2.5 technology upgrades, was
that service providers like AT&T, Bell South, SBC, US Cellular,
Alltel, and Rogers who were using TDMA digital technology in their
networks, found they had no choice but to abandon TDMA which could
not offer an upgrade path in technology unlike GSM and CDMA. i.e. GSM to GPRS and CDMA to 1X. GSM
technology which was exclusively being used in Europe and other
places in the World, before this time in North America was a distant third
with TDMA being the dominant followed by CDMA. Most of the large
TDMA CSPs with huge installed infrastructure opted to go with GSM
because transition costs were lower compared to transitioning to
CDMA technology. Unlike North American handsets which in majority
were dual mode, GSM handsets used in Europe and other places in
the World were single mode only. Carriers in North America
decided to take this opportunity of breaking away from AMPS and
not asking the handset manufacturers for dual mode GSM+AMPS
handsets. For this reason they had to offer expensive special
GAIT handsets with multiple radios (TDMA+AMPS+GSM) while their
networks were transitioning from TDMA to GSM/GPRS. They
discontinued these handsets as soon as the transition was
completed. Some of the smaller service providers like US cellular
and Alltel deciding to go the CDMA route instead of GSM and
continue to offer AMPS support to their subscribers. The
resulting reality is that none of the GSM handsets offered today
support AMPS. This is the reason why CDMA providers have gained
subscribers in North America at the cost of TDMA providers which
could not adequately offer handsets for their ONE RATE maximum
coverage nationwide plans. CDMA providers on the other hand
continued to offer Dual Mode handsets to their customers offering
maximum possible cellular coverage across the nation and still do
so today. Hype aside, CDMA is a better, faster technology for
cellular DATA than GSM.
Always On – Generation 3
Networks are currently rolling out new
technologies as an upgrade to the 2.5G which for data provides
packet data connections at broadband like speeds (400 Kbps – 700
Kbps downloads). GSM-EDGE and CDMA 1X EV-DO are examples of
technologies being implemented. Coverage is limited to a few
cities presently, however it falls back to GEN2.5 network
technology whenever GEN3 coverage is unavailable. Data plan
subscription costs are same at $79 monthly for unlimited use.
Let us now look at the initial equipment required for cellular data today.
We will review each one of the multiple choices below
for their pros and cons.
1. Use of a custom PC Card adaptor: -
These adaptors are generally available
from the service provider
for use on their digital network only. The adaptor with the
wireless radio built-in requires activation of another mobile
device in your account and must be coupled with the corresponding
data plan for its use. These adaptors offer the most flexibility
in terms of mobility and ability to do data keeping your cell
phone free to make and receive voice calls. However this
flexibility comes at a price. Furthermore users should keep in
mind that the adaptor cannot have its radio upgraded as the
technology changes which would require them to pay for a new
adaptor when the upgrade in technology is implemented in the
network. While the service providers offer free upgrades of cell
phones regularly, to reward loyalty of their subscribers they do
not do it for the data adaptors. If the adaptor is lost or the
technology changes, it would cost around $350 to get a new one.
2. Use of a Mobile Data Kit for your cell
phone: - These kits allow data in digital
mode only by attaching
your cell phone to a PC, laptop etc. This least cost approach is
the more popular way mobile data users access the Internet from
the road. This setup enables you to use your cell phone for data
as well as voice though not at the same time. You can purchase
kits which have cell phone chargers built-in for use with the
laptop. This makes traveling easier with one less charger to
carry. If the adaptor is lost or the user needs to upgrade for a
different brand cell phone, it could cost around $69 to get a new
one. There are cell phones on the horizon which will allow for
data and voice at the same time. Don’t hold your breath tough!
3. Use of a Multi-Mode Data adaptor: -
For users whose travels take them frequently to rural or remote
areas where cellular coverage becomes a concern, use of a digital
only data solution is not enough. For these users connectivity
from such places is more important than high speed connections
which are only possible around cities or busy corridors between
them. Use of a multi-mode data adaptor
has become popular among
these users. The CellFlex adaptor as it is known when coupled
with a multi-mode cell phone provides all in one solution to do
data by integrating digital as well as analog modems in a single
adaptor. As we have seen above, the largest geographic cellular
coverage in North America (95%+) is still Analog AMP. Using an
adaptor which could connect in Analog areas as backup is a welcome
peace of mind. Users should note that while the CellFlex adaptors
provide connectivity in digital and analog, their connection speed
in AMPS is limited by the strength of the cellular signal
available. If the adaptor is lost, it could cost around $110 to
get a new one and if the user needs to upgrade for a different
brand cell phone, it could cost around $39 to get a new cell phone
cable. No need to change the PC Card adaptor which is software
upgradeable.
Finally you have to consider how you will be
accessing the Internet from the road, i.e. do you need a 3rd party
Internet Service Provider (ISP) account. When Internet use by
consumers started back in the early nineties, it was only dialup
and thus required users to go through an ISP who (1) would provide
the interface from the telephone network into the Internet network
for Web browsing and (2) also maintained the domain name and
e-mail addresses required to send and receives messages. This is
because in the dialup world which we are so used to; our telephone
number is how we are addressed and contacted on the telephone
network (AAA-NNN-NNNN). On the Internet network however, we are
contacted by using our electronic e-mail address (YourName@ISPName.com)
and are addressed by an Internet Protocol (IP) address for Web
browsing. The ISP acts as a gateway to the Internet.
Wireless Service Providers for packet data
access only (Satellite, Cellular Packet, Hotspots) by design
provide you Web browsing into the Internet network included with
the service. For e-mail, one can use any one of the Web mail
providers (Hotmail, MSN mail, Yahoo mail) which are generally free
for basic e-mail messaging or a nominal fee for more heavy use.
Digital Circuit Switched data users also can do the same if their
cellular service provider supports “Quick Network Connect” (QNC)
feature on their network. Otherwise for standard circuit switched
digital or analog cellular connections you must have a 3rd party
ISP account to connect into the Internet. Existing Internet users
with ISP accounts and assigned e-mail address need to stay with
their ISP if they cannot live with the changed e-mail address
which must be communicated to their family or friends. ISP users
should note that Web mail has no long distance charges associated
with access to their web mail from anywhere in the World. It’s
FREE!
In summary you do NOT need a 3rd party Internet
account if:
- Your wireless cellular service
provider provides you Internet access with the data service.
- Using Web mail, you can live with a
new e-mail address for family and friends to contact you.
- You will not be needing dialup or
analog cellular to access the Internet.
- You do not use any other especial
service only provided by your ISP.
If any one of the above is a NO, having a 3rd
party ISP account is advisable.
In closing, I hope that after reading this information
you will gain a good basic understanding of wireless data. I
have tried to answer most of the question a beginner would ask
related to wireless data from the road. More detailed
information is available on the net for anyone interested.
This information document is free for
distribution and can be copied without any notice to the author.
While I have made every effort to cross-check for inaccuracies,
yet with constant changes in this field I cannot claim that it
will remain accurate in every detail. - May 2005
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