Wireless Data: Then and Now
Cory Forseth
Department of Computer Science
University of Wisconsin – Platteville
Abstract
Wireless data is becoming more and more pervasive in our society today, and its not going away any time soon. In the 8 years since wireless data transfers were first standardized, much progress has been made both with regards to the technology itself, and its applications. But there is a great deal in store for the wireless world; city-wide wireless networks; full, broadband-speed internet access on devices as small as cell phones, and much more. The future of wireless data is very exciting, and the applications are even more so. This paper will show the past, present and future of wireless data, as well as its applications.
Introduction
Wireless networks have become essential in our every-day lives. We use our cell phones to call and text message our colleagues and loved ones. We use the Wi-Fi hot spot at the local coffee shop to get work done on a weekend while enjoying our favorite brew. We check our email in the airport before catching our flight. We research our presentations in the hotel room before the next day’s meetings.
While the first example can be done with a decades old digital cellular network, the rest need a more robust type of network. Wireless data networks have been standardized since the late 1990s and have revolutionized the communications industry. From enabling your cell phone to be more than just a phone, to making it possible for every student on a college campus to have their own laptop and never having to connect it physically to a network. But there is still room for advancement. New technologies will enable entire metropolitan areas to have access to a single wireless network. New devices will be able to roam seamlessly between different types of networks without losing internet connectivity.
Different types of wireless data networks fill different niches in our world. Some allow for communication over a few feet, some over hundreds of feet, while others only stop after several miles. All of these have their own applications, strength and weaknesses, but each is just as important as the last to enable our lifestyle to be what it is today.
Personal Area Networks
One type of wireless data network is the personal area network (PAN). PANs are just what they sound like; a network within your own personal space. Data within a PAN is generally shared between several of your own devices. Set your digital camera near your laptop and without any connection, your computer identifies it and automatically downloads pictures off of it. Or answer a call coming in on your cell without ever having to take the handset out of your pocket because the phone discovered your headset and automatically routed the call to it instead. Of the protocols that currently run in a PAN, the most common is Bluetooth.
Bluetooth
The first standard of Bluetooth, 1.2, was adopted in November, 2003 with version 2.0 coming a year later. [1] Bluetooth devices operate over a distance from 1 to 100 meters, depending on their classification and power output.
Table 1: Bluetooth class specifications [2]
Class / Maximum Power Output – mW (dBm) / Approximate RangeClass 1 / 100 mW (20 dBm) / 100 meters
Class 2 / 2.5 mW (4 dBm) / 10 meters
Class 3 / 1 mW (0 dBm) / 1 meter
Bluetooth uses a master/slave relationship to form a network. The master device can at any time search for discoverable devices within its range to try and connect to. Once it finds something, negotiations take place and if the devices are compatible, they can connect. At any time, the master can send information to the slave, or they can switch places, the slave becomes the master and sends information the other way. All of this connection is often done on the fly and in the background; no user interaction is required, making Bluetooth networks insanely simple to use.
A master can be actively connected to seven devices at once, but can only send information to one device at a time. To still efficiently communicate between the seven devices the master switches quickly between all of its connected devices. In addition to this, it can have 255 other inactive deviceswhich it can bring up to activity at any time.
Let’s say you have a laptop that is Bluetooth enabled. The internal Bluetooth transmitter is a class 2 device with a range of about 10 meters. Because Bluetooth uses radio waves as a means of data transmission, your laptop can discover devices in different rooms or on different floors of your house. Your computer can be connected to your digital camera downloading pictures off of it; printing a document on your printer in the office; synching your music, calendar and address book with your PDA; browsing the web (which you’re connected to via a Bluetooth link to your son’s desktop) with your cool new mouse - all while you are floating in your pool in your back yard. You guessed it; all of the devices are Bluetooth enabled. And because your computer just scanned for devices that it could connect to and use, your set-up time for all of this was nil. All you did was turn on the computer and it did the rest.
Other PAN Protocols
While Bluetooth is by far the most common PAN protocol used today, there are a few very recent additions to the list that show some promise.
Wibree
Wibree is a new type of short range, low power communication similar to Bluetooth. It is designed as a standalone but can also easily compliment Bluetooth in its applications. One possible use is a sports watch that communicates with sensors worn on the body during a workout to collect information like heart and respiration rate or sensors in shoes for statistics on speed, distance or acceleration. It could then store this information until it can send it to a computer for later use. Other applications in medicine, entertainment and just about any other field you can think of have been proposed. [3]
Wibree transmitters are similar to Bluetooth chips but are made to run on button batteries (think watch battery). They are extremely low power which limits their distance, but their ability to work hand-in-hand with Bluetooth transmitters almost nullifies this deficiency. Essentially Wibree is a leaner version of the Bluetooth already on the market.
ZigBee
ZigBee is like Wibree in that it uses extremely low power, low bandwidth transmitters to communicate over a network, but it’s a different kind of network. A ZigBee network can contain more than 65,000 active devices, each of which can operate on a single AA battery for years. ZigBee devices can detect smoke or motion, control lights, control outlets, or any number of other simple monitoring/controlling tasks. A ZigBee network can be used for automation and security in a home or business, for relatively low cost. Because it is all wireless, no time needs to be spent running wires, only connecting a few base devices to a main power source.
Local Area Networks
Most people think of local area networks (LANs) when they think of wireless data networks. You sit down with a laptop, scan for a wireless network, connect and surf the net. It takes some setup, but provides broadband-like speeds and can do anything an Ethernet connection can do. This type of network is now more frequently called Wi-Fi. Everywhere you go you can find a Wi-Fi hotspot; restaurants, cafes, hotels, airports, office buildings, parks, schools, the list goes on and on.
Wi-Fi has actually come a long way in its relatively short life. Several different standards have come and gone with a new standard on the horizon.
Table 2: Wi-Fi protocol specifications
Protocol / Release Date / Data Rate (Max) / Range (Max)802.11a / 1999 / 54 Mbit/s / 75 meters
802.11b / 1999 / 11 Mbit/s / 100 meters
802.11g / 2003 / 54 Mbit/s / 100 meters
802.11n / 2007* / 540 Mbit/s / 126 meters
*The 802.11n standard is not yet complete. It is scheduled for release in 2007
802.11a/b
Around the year 2000, two standards of wireless data communication were released, 802.11a and 802.11b. 802.11b was more widely adopted and became the more frequently used of the two. This is because 802.11a has a more limited range and early releases were poorly implemented and only exasperated this effect. [5] Even with its superior speed capabilities, 802.11a was pushed by the wayside as 802.11b took its place as the standard to be used.
802.11g
Three years into 802.11b’s reign over the Wi-Fi world, 802.11g was released to the world. 802.11g was the best of both worlds, combining 802.11a’s speed with 802.11b’s range. It was quickly adopted even before the standards official release, partly because it is compatible with all 802.11b networks which means that a consumer can buy a 802.11g receiver for their laptop and not have to worry about whether or not the network is 802.11b or 802.11g. It just works with both. Currently, most wireless networks and Wi-Fi hotspots are 802.11g networks.
802.11g can also operate in 2-channel broadcast mode, known as SuperG or SpeedBoost depending on which company makes the wireless router. This boosts the maximum speed up to 108 Mbit/s.
802.11n
The next evolution of Wi-Fi will be a bigger leap than any before. 802.11n is ten times faster than the 802.11g networks we have now, have a greater range, and be much more reliable. The reason for the increase in both speed and reliability is the new MIMO (multiple input multiple output) spatial multiplexing. This means that the wireless router transmits on as many parallel channels as it has antennas. If the transmitter has X antennas, the signal is split into X data streams (demultiplexed) and transmitted. The data streams are received at the transmitter, unscrambled and re-multiplexed. Any extra antennas on either end are just used to further enhance the reliability of the data stream and the link speed. [6] Theoretically with this form of transmitting data, the improvement in link speed and integrity is limited only by the least number of antennas on either end.
This new multi-channel broadcast may allow for huge jumps in speed and reliability as manufacturers figure out how to cram more and more antennas onto both transmitter and receiver.
Wide Area Networks
In order for Wi-Fi to provide anything over the 100 meter radius that 802.11g can provide, more base stations need to be added. This can be done to make a network as big as the owner wants, limited only by how much he wants to spend. At a point it becomes so cost-ineffective to expand that a practical limit to the size of a Wi-Fi network emerges. It is at this point that anyone wishing to expand the network would need to look at a Wide Area Network (WAN).
Generally the term WAN is simply used to describe a network of LANs, where routers are places in between large corporate or public networks so that the computers in each network can share resources with each other. A good example of a WAN would be BadgerNet, the ISP for the university. It is a network that connects every UW System school and most public high and middle schools together. It also connects to two of the internet backbone servers to provide internet access to all of its connected schools. Looking at this example you can see that wired WANs can span an obscene number of computers and a huge land area, spanning across state and even national boundaries.
Wireless WANs don’t quite span as big an area, but in terms of wireless data networks, they do span very large areas.
WiMax
WiMAX as a protocol could revolutionize the way we think about getting information. It is not simply another standard that will extend the range of current wireless networks; it is a new type of wireless capable of spanning a 6 mile radius with a single base station. With the internet access provided by this one base station, customers could use VoIP instead of a normal land line, Internet TV as opposed to standard cable, all while still getting DSL-like speeds on the internet.
A single WiMAX base station can deliver speeds of up to 72 Mbit/s to thousands of customers in its 6-mile radius. Instead of using your cell phone to download small, compressed videos, you can use a PDA and do the same thing, but at broadband speeds, all while walking down the street. There is no need to worry about switching networks, because it is all one network. WiMAX also delivers adequate service to non-line-of-site locations, meaning in a downtown, urban environment (a large market for this technology) buildings will not hinder connectivity when moving around. [7]
This technology might also have future applications in smart cars. It could provide up-to-the-second traffic updates, navigation with considerations for any sort of construction, and new entertainment systems to replace the DVD systems that come in some mini-vans today. Instead of parents putting in a DVD to placate the children in the back seat, they can stream their kids favorite TV to their car over the internet. The possibility also arises to have an ADT-like security system in your car, monitoring it for burglary, vandalism, accidents, fires, anything you can think of, and notifying the authorities instantly, without a need for a phone call from the occupant of the vehicle.
In more rural areas, it can extend current DSL networks to reach a much broader audience without the need to run more cables. People who previously only had access to dial-up can now get the same broadband internet as those in more populated areas.
Clearly WiMAX will have huge impacts on the wireless data world. The applications are practically endless and any opportunities are ripe for entrepreneurs to come up with a new application, develop it and make their millions. WiMAX could easily change the way we live our daily lives.
Conclusion
Wireless data networks have already changed the way the world thinks about the internet. No longer is it something you can only access sitting at a desk in the office or at school. Everywhere you look, the internet is there and easy to access. In the past 8 years since the release of the 802.11 standard and its products, the gap between us all has narrowed. When you can order a cup of coffee at Starbucks and drink it while teleconferencing with people from around the world right there in the coffee shop, it’s hard not to think that the world just got a little bit smaller.
But the end is nowhere in sight. New and emerging technologies threaten to shrink this little globe of ours even further, but that is a good thing. With a more omnipresent internet connection comes a greater ability to communicate with the world, whether it be finding the nearest sushi restaurant or letting authorities know where our car just went off the road.
The possibilities are endless and impossible to predict, but that uncertainty is what makes new technologies so exciting.
References
[1] Bluetooth.com | The Official Bluetooth Technology Info Site. (
[2] Bluetooth – Wikipedia. (
[3] Wibree. (
[4] “So, Who Needs ZigBee?” 8 Nov 2005. 27 Mar 2007. (
[5] IEEE 802.11 – Wikipedia. (
[6] D. Gesbert. “Smart antennas and special multiplexing”. Jun 1999. 27 Mar 2007. (
[7] WiMAX Overview – WiMAX. (
[8] Comparison of Wireless Data Standards – Wikipedia. (
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