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RSS feedsFew technologies in recent times have generated quite as much interest as wireless networking, and justifiably so. During a period of overhyped technologies, it's refreshing to find one that genuinely delivers unique and compelling services to both consumers and businesses at every level.
Like all technologies though, wireless networking isn't perfect. While deserving much of its recent backslapping, there are a number of important issues every existing or potential wireless user should be aware of.
Beyond the most common issues of standards, compatibility and security, there are increasing concerns over interference and congestion with other networks or devices sharing the same radio frequencies.
Head out on the road, and a whole raft of additional issues arise, including the safety of public hotspots, and whether your kit will operate or even be legal while abroad.
Then there's raw performance. Building a wireless network may be as easy as fitting an Access Point, but where should it be located for the best results, and what happens if you want to extend your coverage?
Theoretical speeds may also look sufficient on paper, but in practice is wireless really suitable for applications such as streaming high-quality audio and video?
There are certainly plenty of issues to consider, but rest assured we've got the answers to these and more.
We'll explain what to look out for and, most crucially, how to solve both common and obscure wireless worries, allowing you to relax and make the most of this impressive and enjoyable technology.
Standards and compatibility
Before worrying about performance, security and interference, the first wireless issue you may experience is plain and simple incompatibility.
Over a few short years, the original 802.11 wireless Ethernet standard has enjoyed a raft of extensions, each identified by a lower-case letter tagged on the end. Some refer to entire physical layers designed for networking, while others specifically enhance security, quality of service and interoperability.
The crucial thing, though, is that certain combinations may work together, while others won't.
Third-party certification may aim to simplify compatibility concerns, but introduces additional terms and branding. Finally, manufacturers eager to gain a competitive edge may release products based on a new standard while it's still in draft form.
It's potentially confusing, so here's a brief compatibility overview of the main standards and certifications in common use.
There are currently three physical layer standards for wireless networking called 802.11a, 802.11b and 802.11g. The first, and most widespread, is 802.11b, operating on a frequency of 2.4GHz and delivering a maximum speed of 11Mbps.
In theory all devices conforming to the 802.11b standard should work together, but offering additional reassurance is the independent Wi-Fi Alliance with its own compatibility and certification process. Products sporting the Wi-Fi badge are assured to work together.
Note 802.11b+ refers to a technology which claims to double data rates to 22Mbps. For this to work, the relevant devices must all support 802.11b+.
The second wireless physical layer standard is 802.11a, operating at a frequency of 5GHz and offering speeds up to 54Mbps. Since 802.11a operates on a different frequency to 802.11b, they are simply incompatible. 802.11a devices won't work on an 802.11b network and vice versa.
Again, while all devices conforming to the 802.11a standard should work together, the Wi-Fi Alliance has also begun certifying them, with a new extended badge differentiating products designed for different frequencies.
Offering some relief to those wanting to use both types of networks though, dual-band equipment is now available, supporting both 802.11a and 802.11b.
The third and latest wireless physical layer standard is 802.11g, matching the 54Mbps speed of 802.11a, but operating on the same 2.4GHz frequency of 802.11b - this gives 802.11g the unique advantage of being backwards compatible with 802.11b.
In theory, an 802.11g device should work on an 802.11b network and vice versa, although to enjoy 54Mbps, both the device and network need to support 802.11g.
The official 802.11g standard was completed in June 2003, but numerous products based on an earlier draft specification have already been on sale for some months.
While each supplier has offered assurances of compatibility with the final 802.11g specification (or upgrades if they don't), it's too early to tell if there are any serious concerns for early adopters.
In our own tests with draft 802.11g equipment, we measured similar speeds to 802.11a, and confirmed compatibility with 802.11b devices. Unfortunately, once an 802.11b device was connected to our draft 802.11g network though, it forced all draft 802.11g devices to operate at the slower 802.11b speeds.
Despite being a recognised problem, several 802.11g manufacturers now claim this has been fixed. One solution involves building access points with two antennas, but until such products or those conforming to the final specification are tested, we can't comment.
Early adopters of draft 802.11g equipment may wish to contact their supplier for information on possible updates, although if they're exclusively using 802.11g devices, they should be fine.
With the specification now finalised and officially ratified by the IEEE, we should soon know what 802.11g is truly capable of, warts and all; Wi-Fi certification will follow soon after. Suffice it to say we will keep you updated with all the news and test results.
In the meantime, users interested in supporting the maximum number of standards should consider new tri-mode/dual-band products supporting 802.11a, b and g.
Finally we should mention Intel's Centrino brand, which can be applied to notebook computers featuring a Pentium M processor, Intel 855 chipset and an Intel integrated wireless network connection. The first Centrino notebooks employ 802.11b, although we can expect dual-band 802.11a /b in the near future, and 802.11g support probably added in the new year.
Larger enterprise users may additionally be interested in products with Cisco-compatible extensions, which assure compatibility with Cisco's wireless security suite. Centrino notebooks and products based on new Atheros chipsets already support Cisco-compatible extensions.
Frequencies and regulations
In the previous section we said all devices conforming to the same physical layer standards should work together - so one 802.11b device should work with another 802.11b device and so on.
One potentially large fly in the ointment, though, is how radio resources have been split up worldwide, with countries often using different regulations or reserving certain frequencies for non-public use.
Consequently, while all devices conforming to the same physical layer standard and originating from the same country should work together, taking them abroad may be an entirely different matter. A wireless globetrotter could find themselves abroad with equipment that simply doesn't work or may even be illegal.
This is clearly a big issue for anyone using corporate, domestic or public wireless networks, while on holiday or business travel.
To discover which products can work together and whether they're allowed in certain countries, you must delve into certified frequency ranges and radio channels. In doing so, the broader capabilities, potential congestion and ultimate capacity of various standards are revealed.
802.11b and 802.11g are described as operating on a frequency of 2.4GHz, but their range potentially runs from 2.412 to 2.484GHz. This range defines 14 radio channels, but the full number are only certified for use in Japan.
ETSI (European Telecommunications Standards Institute) regions in Europe have certified 2.412 to 2.472GHz for 802.11b and g, allowing channels 1 to 13 to be used. North America and Spain are the most restrictive, allowing a range of 2.412 to 2.462GHz with channels 1 to 11.
Consequently you can use channels one to 11 in any of these regions, but 12 and 13 are only certified for ETSI Europe and Japan, while 14 is for use in Japan.
Wireless kit bought in various regions should conform to that region's regulations, but check the specs to see if it was designed for use elsewhere. We've recently reported US-spec cards being sold in the UK, for instance.
In practice for 802.11b and 802.11g, channel selection is rarely a problem. The channel is set on an access point, after which all clients configure themselves. The only potential problem is if, say, a European access point has been set to channel 12 or 13, preventing a US client from connecting.
The worst case scenario is a Japanese access point set to 14, blocking everyone apart from local clients.
We can only hope that public hotspot and corporate network administrators stick to channels one to 11 for international compatibility. There are additional issues with 802.11b and 802.11g channels in terms of congestion, which we'll discuss later.
What is 802.11a?
802.11a is described as operating at 5GHz, but its actual range potentially runs in three bands of 5.15-5.25GHz, 5.25-5.35GHz and 5.725-5.825GHz.
Each band defines four channels, making 12 in total, although the upper band is expected to be used for higher-power applications only, such as inter-building connections.
North America has approved use of all 12 channels, although only the first eight are really applicable for general use. Europe has been slower to approve, as much of the 5GHz spectrum is already used for satellite, radar and military applications.
The UK, Germany, Finland and Netherlands have agreed to allow low-power operation in the first eight channels, although most of the rest of Europe, along with Japan, are limited to the first four channels of the lower band only. This situation is subject to change as regulations are updated.
Understandably concerned with potential radar and military conflict, Europe has set two further regulations for 802.11a equipment.
Dynamic Frequency Selection (DFS) senses existing broadcasts in the spectrum and automatically avoids them, while Transmit Power Control (TPC) adjusts the signal power depending on proximity of devices and essentially prevents them from unnecessarily shouting at each other.
DFS and TPC are now mandatory for 802.11a equipment in Europe but not in North America, although to ensure international compatibility, we believe all future 802.11a devices will support them both.
Until DFS and TPC become a standard part of 802.11a though, potential global users should look out for products labelled with 802.11d (to automatically configure clients to access points worldwide) and 802.11h (which takes the stricter European regulations on 5GHz networking onboard).
In Part 2 of The Pros and Cons of Wireless, we'll provide you with the solutions to more Wi-Fi related conundrums, including congestion, security and how to enjoy a cable-free life.
See also:
All Wireless Technology
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