Wireless Choices: Networking Technologies and Windows XP
Published: September 3, 2002
By Barb Bowman
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Wireless networking products seem to be multiplying by the minute. Confused friends and co-workers often ask me what kind of wireless networking hardware they should buy and which wireless standard to choose.
If you want to set up a wireless network and want to know how fast wireless is, how it works with Windows XP, or which version of the 802.11 standard you should choose, you'll find answers in this column. While I don't have a one-size-fits-all solution, I will tell you what to expect from a wireless network, and I'll help you pick the wireless technology that fits your needs.
For help in sorting out the versions of the 802.11 wireless standard, read the 802.11 Planet tutorial, Alphabet Soup. Another article, Lay of the Wireless LAN, provides a general survey of wireless LAN technology and products. My earlier column, 802.11a Wireless Networking, compares the widely available WiFi 802.11b standard with the newer, high-speed 802.11a.
Dream Wireless World
In a dream technology world, I'd have multiple-choice connectivity for the different versions of the 802.11 standard. Depending where I was using my PC, and what I needed to do online, I could choose the best network connection. In this one-click setup, I could choose among wireless technologies:
| • | 802.11b (This 2.4 gigahertz is the most commonly available and is found at public hot spots, such as Starbucks and public airports.) |
| • | 802.11b+ (A slightly faster version of 802.11b that is now used in some networks.) |
| • | 802.11g (This technology is not yet available but the standard promises a data rate of 54 megabits per second using the 2.4 gigahertz band.) |
| • | 802.11a (The fastest of 802.11 available today transmits 54 Mbps in the 5 GHz band.) |
In that world, I could purchase a single wireless PC Card adapter. It could handle all of the wireless technologies. It could determine the best available connection. Using Wireless Zero Configuration in Windows XP, the adapter could rate the connections for speed and signal strength, then offer me a choice, or automatically connect to the best. But we're not there yet.
Current Wireless Technologies
Among the technologies we have today, 802.11b, also referred to as wireless fidelity (Wi-Fi), is the mainstream choice. These products are widely available and relatively inexpensive. The cost of a wireless 802.11b PC Card is often under $100, and wireless access points can be found at $200 and up.
A newer technology, 802.11b+, is less widely available but it has some advantages. It uses the Packet Binary Convolutional Code (PBCC) that was once considered, but rejected for the upcoming 802.11g standard. PBCC is offered in chips from Texas Instruments. Although 802.11b+ technology offers only a 20 percent increase in speed over the 802.11b standard, that 2–3 Mbps gain can be just enough to provide a better overall experience. You can get better range and bandwidth than 802.11b, at a cheaper price than with 802.11a. Another advantage can be seen in devices where 802.11b+ is employed in chipsets that are also designed to be compatible with the Wi-Fi 802.11b standard. You can use such devices with both types of networks.
The fastest version available today, 802.11a, is available only in a limited number of devices, targeted primarily at business users. This standard uses orthogonal frequency division multiplexing (OFDM) modulation technology. (For more information about this technology, see the OFDM Forum.) You can expect to pay a premium price for this equipment.
Of course, there is always a better, faster technology in the works. In this case, it's 802.11g. For information about the 802.11g standard on the horizon, read the 802.11 Planet article, 802.11g: Ready or Not?.
Connectivity and Throughput Needs
Most residential and small office Internet connections, even broadband cable or DSL, are slower than any of the available wireless 802.11 technologies. So the wireless technology and equipment you choose will have no impact on Web browsing, e-mail, or file downloads on the Internet. If your Internet Service Provider offers a 1.5 Mbps connection, the maximum speed from the Internet through your modem will not be increased by installing an 11 Mbps or 54 Mbps wireless network. When you're making decisions on wireless standards and hardware, the real consideration is the type of connectivity needed for the computers on the home network.
Questions to ask yourself when purchasing a wireless network, include:
| • | How you will use your network? |
| • | Which wireless standard will give you the most speed in your home or office? |
| • | What kind of wireless hardware do you need? |
How Will You Use Your Wireless Connection?
If you don't typically transfer large files between computers and want to use your wireless network primarily to share an Internet connection, the 802.11b standard is the best choice. Business travelers with laptops can use 802.11b on the road (see my earlier column, On the Road, for more information), and use the same wireless PC Card adapter to connect to a wireless network at home.
For home and small office users who regularly transfer large files between computers, 802.11b throughput is not fast enough. The 802.11b+ technology offered by vendors such as D-Link in their Air Plus line, provides an additional 2-3 Mbps speed.
If this is still not fast enough for your needs, you may want to consider 802.11a technology.
In close proximity to an access point (in the same room, with no walls or floors to dilute the signal), 802.11a provides triple the effective speed of 802.11b. It's definitely a technology suitable for high volume data transfer.
If your special interest is in streaming media between computers on your home network, here's how the standards rate:
| • | 802.11a can effectively handle streaming DVD-quality video and audio at its higher rates only. The effectiveness decreases as the signal strength decreases. |
| • | In streaming media formats that provide less than DVD-quality video, performance is adequate over 802.11b wireless LANs. Streaming audio will work quite well. Windows Media format streaming is particularly well suited for 802.11b. |
| • | 802.11b+ equipment may provide a slightly better experience with its speed boost, and these adapters are compatible with standard 802.11b equipment. |
Which Wireless Technology Works for Your Network?
The number of walls, floors, and distance from the wireless access point or router makes a difference in the speed of your connection. The more walls and floors between the wireless access point/router, the weaker the signal. Performance will also vary depending on whether your configuration is connecting wireless PC to wireless PC (ad hoc), a wired PC to a wireless PC through infrastructure such as a router, or a wireless PC to a wireless PC through an access point. For example, two wireless PCs connected via an access point will move data slower than two wireless computers in an ad hoc configuration. With the exception of the Atheros chipset-based 802.11a hardware, enabling WEP security adds some overhead and decreased effective throughput in the wireless networks I have tested.
The speed designations of the three available wireless technologies state the following maximum rated speeds:
| • | 11 Mbps for 802.11b |
| • | 22 Mbps for 802.11b+ |
| • | 54 Mbps for 802.11a. |
Will you get these speeds effectively? Unfortunately, no. Generally speaking, all three wireless standards have adaptive speeds that fallback or improve when the computer is moved farther from or closer to the wireless access point or router, or when the number of walls or floors in the way changes.
In addition to walls and floors, susceptibility to interruptions in the wireless signal also affects what kind of sustained performance you can expect in your wireless network. Some microwave ovens and 2.4 GHz phones disrupt 802.11b communications because they share the same wireless band. Changing the channel on the 2.4 GHz phone or wireless base station or router can help overcome interference. If you live in a large apartment or condo complex where multiple 2.4 GHz cordless phones and microwaves are in use, it's possible you'll experience dropped connections using 802.11b or 802.11b+ in Wi-Fi mode. In this environment, 802.11a may be the best choice.
The working rule is that an 802.11b connection will remain at a consistent speed longer and not fall back to a lower speed (5.5 Mbps, 2 Mbps, and 1 Mbps) at longer distances than either 802.11b+ or 802.11a.
802.11a speed starts at 54 Mbps, but it drops very quickly through the range of 48, 36, 24, 18, 12, 9, and 6 Mbps as distance from the wireless access point increases. Similarly, 802.11b+ will drop quickly to 11, 5.5, 2, and 1 Mbps.
Windows XP will display both Speed and Signal Strength when a computer first connects to a wireless network, or when the mouse is positioned over the notification area icon for the connection. This is not the actual speed of the connection, but should be used as an indicator of the health of the wireless connection. As shown in Figure 1, Windows XP initially determined that the 802.11a network connection can operate at the highest rated maximum speed of up to 54 Mbps.
Figure 1
Two floors away from a wireless D-Link DWL-5000AP 802.11a access point, I measured the actual throughput rate between two computers on the network by transferring a 200 MB file and manually clocking the time. I calculated the average speed through the access point at 20 Mbps. For additional verification, I used Qcheck, a great free utility available from NetIQ.
When testing 802.11a hardware, beyond 10 feet of the access point and with any floors or walls in the way, the connection rate was not constant. It fell back and forward throughout the file transfer. During the course of the test transfer, the speed and signal strength reported by Windows XP varied from 6 Mbps to 54 Mbps. I viewed the changes by clicking the Wireless Network Connection icon in the notification area that displays the Wireless Network Connection Status.
Using a D-Link Air Plus 802.11b+ adapter on the same laptop computer in the same location with a D-Link 802.11b+ DWL-900AP+ access point, the signal strength and speed remained absolutely solid without any fallback or degradation while transferring the same 200 MB file. The measured effective speed was 6.1 Mbps (Windows reported a steady 22.0 Mbps rating).
Figure 2
To round out the comparison, I used one of my Orinoco/Agere 802.11b PC Cards and an Orinoco AP500 to perform the same file transfer. As expected, the signal strength and speed were steady. The measured effective speed was 4.4 Mbps (Windows reported a steady 11.0 Mbps rating).
Figure 3
The bottom line on speed versus cost is that the more expensive 802.11a hardware can provide an effective throughput that is approximately 4 times faster than 802.11b under optimum conditions. This technology is a real productivity booster for small office and residential users with a need for speed. For those with needs focused mainly on Internet connectivity, 802.11b+, available at nearly the same price as 802.11b is solid, compatible with the Wi-Fi standard, and offers incremental increases in performance for occasional file and data transfers over the network.
Choosing Hardware for Your Wireless Network
How do you add wireless capability to an existing wired network? The easiest solution is to add a wireless access point and plug it into an available port on your router (or hub if you're using Windows XP Internet Connection Sharing).
In almost all cases, the access point you purchase today will not be upgradeable to future faster wireless standards. A small number of wireless access points for the enterprise market employ PC Card slots to handle wireless functions and may be upgradeable in the future, but today's high price tag may be prohibitive.
The cost of many 802.11b/802.11b+ access points has dropped to the $100-$130 range, which makes this technology very affordable. A search for 802.11b access point on Pricegrabber.com reveals very attractive prices. You can expect to pay a premium for an 802.11a access point. If you've got a large office or home network to wirelessly enable and need a mixture of 802.11b and 802.11a, you may find that purchasing two separate access points is the most economical route. Non-upgradeable, dual-band 802.11a/802.11b access points are also starting to appear on vendor Web sites, and pricing is only starting to become competitive. You'll need to compare prices again when you decide to purchase equipment.
What is the best way to set up a mixed wired and wireless network from scratch? The selection of 802.11b wireless routers is quite large, and the cost is only slightly more than a stand-alone wireless access point. Vendors have not produced 802.11a wireless routers yet. Therefore you will need a router to serve private IP addresses to 802.11a clients, unless you purchase multiple public IP addresses from your ISP. If you're setting up a mixed network, you can plug an 802.11a access point into an available port on an 802.11b wireless router.
Currently, client wireless adapters offer 802.11a only, 802.11b only, or 802.11b/802.11b+. While equipment from multiple vendors may be compatible within the wireless standard offered, security configuration can become complex due to differing schemes (HEX, ASCII, pass phrase) for WEP keys. Initial wireless network setup and on-going maintenance (changing WEP keys) is usually easier if equipment is selected from the same vendor.
Most of the current generation of wireless adapters ship with drivers that support Wireless Zero Configuration for Windows XP, but you may encounter a third party driver installation that actually turns off that service. This tip, Restore the Wireless LAN Tab in Network Properties, tells you how to enable the Wireless Zero Configuration Service again.
Suggestions for Future Columns
If you use Windows XP at home and have a topic you'd like to see covered in a future column, feel free to write me at: barb@mvps.org. I'll be glad to receive ideas and suggestions. Please understand that I can't answer individual e-mail messages or respond to them.
Barb Bowman enjoys sharing her own experiences and insights into today's leading edge technologies. She is a product development manager for AT&T Broadband Internet Services, but her views here are strictly personal.
