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Bluetooth, WiFi, and
Cellular Data Wireless Explained
By: David
Johnson
- December 2nd, 2004
| This special feature article is here
to help explain the three wireless technologies seen in PDA devices
on the market today and give you a reference to decide which
technologies you need in your PDA. The three types of wireless
you will see built-in and available as expansions are: Bluetooth,
WiFi, and Cellular Data Wireless. Each type of wireless relates to a
type of wired connection, so for some, it may be easier to think
about it by its wired counterpart. Wireless is an important part of
PDA's as it is by far the easiest way to connect PDA's to other
devices, and allows for a lot of different options in getting you
device connected both to a local machine and to the internet. |
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Bluetooth
The easiest way to think of Bluetooth and its uses
is to relate it to USB. Bluetooth is, in essence, a wireless version of
USB. Especially in the case of getting your device connected to your
desktop/laptop machine, Bluetooth wireless will replace your USB
connection. But more than just that connectivity, Bluetooth will also
allow you to connect to other Bluetooth devices. For instance, with
Bluetooth, a PDA can be connected to a phone with Bluetooth. With the
appropriate service, your PDA can use the phone to access the internet.
PDA devices that double as phones can use Bluetooth to connect to a
Bluetooth headset, and new stereo headphones (liked those from HP) can
be connected to HP devices over Bluetooth. Bluetooth is short-range
wireless, only connecting to other devices within about 30 feet.
You may hear of different versions of
Bluetooth. At the present time there are two, version 1.0 and 1.1.
Version 1.0 of Bluetooth requires devices to bind together, making a
direct connection to each other, meaning that a device can only connect
to one other at a time. Version 1.1 allows for up to eight devices to
connect simultaneously at a higher speed (2 Mbps instead of 1 Mbps). Two
new versions of Bluetooth could be coming in the near future. Bluetooth
version 1.2 is planned to support higher communication rates 3 Mbps.
Similarly, Bluetooth version 2.0 will have even higher transfer rater
but will require more power.
WiFi (802.11)
To make a local area network with
wireless, WiFi is the way to do it. WiFi is also known by its IEEE
standard name, 802.11. The most common form of WiFi is 802.11b, but
recently 802.11g was introduced into the PDA market allowing for faster
connection speeds. WiFi is, in essence, a wireless version of Ethernet
in the form of a local area network. WiFi can make a local network
either through use of a wireless router or by added a wireless access
point to a wired local area network. WiFi can be used to connect two
devices directly (ad-hoc) though is usually used in infrastructure mode
for connection to access points. Some stores, like Starbucks, feature
WiFi networks for use by those that purchase an account on the service
for a monthly fee. WiFi is a moderate-range wireless, only connecting to
access points and other devices within 150-500 feet (depending on
obstructions)
As was noted earlier, there are
different types of WiFi, noted by the letter at the end of the 802.11.
The most common type of WiFi is 802.11b which has a bandwidth of 11
Mbps. 802.11a is seen in more businesses than consumer settings,
supporting 54 Mbps of bandwidth but runs on the 5 GHz wireless spectrum
as opposed to 802.11b which runs at the 2.4 GHz frequency (which is why
A and B devices are not compatible). 802.11a also has a dramatically
shorter range than other WiFi standards. Today, 802.11g is taking off as
a replacement for 802.11b. Like 802.11a, 802.11g supports a bandwidth of
up to 54 Mbps but like 802.11b, it runs at a frequency of 2.4 GHz and is
completely compatible with 802.11b devices (though they run at 11 Mbps
not 54 Mbps). In the future, 802.11n may be the new standard, running at
108 Mbps with improved access distances as well. 802.11n is also
expected to support MIMO (multiple input multiple output) adding
technology to bounce signals off walls. Companies like Belkin already
have "pre-n" devices available which boast features of the 802.11n
wireless standard even though the 802.11n standard isn't standard yet.
Cellular Data Wireless (GSM/GPRS, CDMA)
The only way to connect from anywhere is
to use a cellular data wireless connection. Cellular Data Wireless
(often just referred to as Wireless) comes in two forms, GSM/GPRS and
CDMA (sometimes also referred to as 1xRTT). Both forms are similar and
are decided on by networks. In the US, T-Mobile and Cingular are GSM/GPRS
based, and Verizon and Sprint networks use CDMA. Devices with this
wireless technology are usually only available from the cellular
provider itself. Cellular Data Wireless is, in essence, a wireless
version of a modem connection. It primarily only connects you to the
internet. In most cases, Cellular Data Wireless is much slower than
other types of wireless, but you can virtually connect from anywhere you
get cellular phone service. With GSM/GPRS, data speeds are about 40 Kbps
(a dial-up modem runs at near this speed). With CMDA, data speeds are
about 144 Kbps. Unlike the other two types of Wireless, a Cellular Data
Wireless network cannot be setup be setup by the consumer. Service must
be purchased from a cellular provider. Cellular Data Wireless is a
long-range wireless, allowing connectivity locally, nationally, and
internationally. Link: dojki
In the future, wireless networks will
boast new technologies for increased speed. EDGE is the next step for
many GSM/GPRS providers. Cingular already provides EDGE service in many
major cities and T-Mobile is planning to support EDGE as well. EDGE
increases the network speed to 100 Kbps. Further than that in the GSM/GPRS
market is UMTS and HSDPA, which increases data transfer speeds to up to
2 or 3 Mbps. The future for CMDA is similar. 1xEvDO is next after the
1xRTT CMDA standard and is already being introduced by Verizon in some
markets. 1xEvDO supports speeds of over 300 Kbps.
Final Thought
Not every user needs every type of wireless
connection. In many cases, no wireless connection is needed. Devices
without a wireless connection can often later support one through a
Compact Flash or Secure Digital card slot. Most new devices
include some type of wireless connection, and while you may not need it
at the time you buy the device, in many cases having some type of
wireless connectivity in your device will allow for more options in the
future. Hopefully this guide has given you a strong overview of the
three types of wireless technologies found in PDA's and can help you
make an educated decision on what would be best for your use.
Like always, any questions or comments you have are
welcome. Feel free to email me at
dave@davespda.com. You questions or comments may be
incorporated into this feature to help other users as well.
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