Special Features

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.


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.

Feel free to email me about your own PDA, questions, comments, articles, rumors, and reviews.  I can be reached at dave@davespda.com.