If you are looking for a networking niche with growth potential, check out wireless networks. No, not a cellular telephone on steroids, but an extension of the conventional LAN to the far reaches of the office. Imagine a conference in a meeting room where participants have their own laptops and can exchange information with each other immediately. Don't send it later. Send it now!
What used to be an expensive, vertical market solution is growing toward a more general networking solution that is applicable to companies where laptops are becoming the prime PC for many workers. Wireless networking means more than just eliminating the wires needed for conventional networking. Specialized computing devices, such as two-way pagers, bar code scanners, and thin network client tablets, are just some of the interesting tools available for wireless networks.
RECENT CHANGES
Although wireless networking has existed for years, a few things have changed recently. First, prices are dropping. This is true across the industry, but look at what happened to the networking market when 10BaseT Ethernet adapters and hubs became commodities. Some Ethernet adapters are cheaper than modems. Wireless network adapters still are more expensive than wired network adapters, but the cost is low enough that the difference between wireless and wired adapters can be offset by other costs such as wiring.
Second, standards-both conventional and de facto-are providing interoperability, more supplier choices, and specialized solutions that can be integrated into an existing wireless network. Third, wireless software is maturing. For example, roaming, the ability to switch automatically and transparently between wireless access points, is a standard feature. Also maturing is the process of conducting site surveys, which are used to determine coverage by access points-the link between wired and wireless networks.
Wireless solutions are not just for mobile PCs. In many environments, running network cables is either impractical or impossible, so wireless solutions work well. They also provide quick, temporary networking solutions. For example, relief and military organizations use wireless networks for instant networking environments.
Bandwidth and range are the main limitations to wireless solutions. They pale in comparison to 10OBaseT Fast Ethernet, but RadioLAN's (Sunnyvale, CA) products match 1OBaseT Ethernet speeds. Unfortunately, the wireless network's trade-off is between speed and range, but with RadioLAN's products this is less of a trade-off, compared with other wireless solutions.
Covering all the bases for wireless LANs is difficult and impractical for most VARs and network managers, which is why a spectrum of available solutions is presented here. Like most networking solutions, it is best to concentrate on one or two that meet most needs.
WIRELESS ADVANTAGES, ISSUES, AND ANSWERS
The advantage of wireless networking is obvious: There are no cables to limit movement, and no network jacks or associated wiring are needed. How these advantages are used depends on the type of wireless device. For example, wireless handheld PCs and tablet PCs allow real-time mobility because users can move and work at
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Figure 1: Peer-to-Peer networks are handy in conference rooms and even small offices, eliminating the need for an expensive access point. Without bridging capabilities, only workstations that are directly connected can communicate. By adding wireless bridging, each of these workstations (laptops with wireless NICs) can communicate by transmitting data via other workstations. |
Wireless networks can be built with or without access points. Figure
1 shows how a peer-to-peer wireless network operates. A distance limitation
is imposed on the group, and each wireless workstation must be within
range of all others in the group. To move beyond that distance limitation,
you need to select a wireless product that provides bridging at each
workstation. With bridging, two workstations out of range from each
other can still communicate if they both are within range of other
workstations with wireless adapters that can relay information between
the two stations. In Figure 1, workstation 1 communicates with workstation
4 via direct communication links with workstations 6 and 3.
The peer-to-peer configuration works well for temporary or ad hoc
environments that occur in conference rooms and, literally, out in
the field. This is also a lower cost solution for fixed installations
where all workstations are close together. You can even have a wireless
server, eliminating the requirement for peer-to-peer networking software.
ACCESS POINTS
Figure 2 shows a more common configuration with a wired network tying
together multiple access points. All workstations-wired and wireless-are
on the same
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| Figure 2: Roaming is a standard feature that allows moble systmes in range of more than one access point to automatically use the access point with the best signal. |
Still, broadcasts that might use 10 percent of a wired network will saturate a wireless network if they are not filtered out. Broadcasts normally are unnecessary for wireless workstations whose applications typically work with a server or directly with another workstation.
The roaming feature allows a wireless workstation to maintain a connection to the network while moving from one location to another. The access points and wireless network adapter work together to determine vhich access point the adapter will use.
SITE SURVEYS
Access point site coverage does not need to be all-inclusive. For example, it makes little sense to have an access point that covers the broom closet. Determining access point placement is one area in which a VAR's expertise can come into play. Site survey programs are standard fare with wireless network products and are used to determine site coverage. A preliminary visual exanunation of a site provides a VAR with an initial estimate of the number of access points needed to cover the designated areas.
The visual examination can be followed up with a site survey using a laptop and two or three access points. The only requirement for access point placement during this test is the availability of a power outlet for the access point. No additional wiring is necessary until the access points are finally installed. If the customer wants the roaming capability, you need to determine the coverage overlap and place additional access points in those areas.
After completing the survey, you have a map that includes access point positioning and areas covered by each access point. Areas that are not supported should be highlighted. For example, the reception area might have a wired PC for the receptionist, but wireless support in that area may be unnecessary or unwanted.
The site survey also provides a VAR with firsthand knowledge of wireless bandwidth requirements based on the number of workstations to be supported in a particular area. Figure 3 shows why this might be important. If you have a cluster of machines in a given area, a single access point might be insufficient. To improve performance, add another access point, and assign each workstation to an access point. All workstations will be connected, but they won't be vying for a single access point.
Some products, such as Netwave's (Pleasanton, CA) AirSurfer, allow multiple access points to operate in the same area without conflicts. Using different frequencies or frequency sequencing, each access point can support an independent group of wireless workstations. Each access point provides the same amount of bandwidth to the group, so two access points essentially double the total available bandwidth within an area.
THE 802.11 STANDARD
Dozens of wireless solutions are available from a variety of vendors. Some are interoperable. Currently, two wireless standards-one de facto and one conventional exist. The de facto standard is OpenAir, fostered by the Wireless LAN Interoperability Forum (WLIF,www.wlif.com). OpenAir is essentially what Proxim
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| Figure 3: Some wireless systems allow multiple access points in the same area with each serving a unique group of workstations, thereby increasing the aggregate throughput for the total group. |
(Mountain View, CA) implements in its RangeLAN/2 product; this technology
has been licensed by a number of companies. WLIF provides interoperability
testing through XXCAL Testing Laboratories, an independent testing
organization. OpenAir uses FrequencyHopping Spread-Spectnun (FHSS)
on the 2.4GHz band with a data bandwidth of 1.6Mbps.
The 802.11 standard was recently finalized, but some details, such
as access point management and roaming support, are still being worked
out. The 802.11 standard potentially provides a mechanism for interoperability,
but some problems still arise. Wireless products are interoperable
only if they implement the same part of the standard. FHSS, Direct-Sequence
Spread-Spec(DSSS), and Diffuse Infra-Red (DFIR) all comply with the
standard, but they are incompatible. This has led to a split between
products, some using FHSS and others implementing DSSS. Unlike the
OpenAir standard, 802.11 also lacks an authorized testing organization.
The 802.11 radio implementations utilize the 2.4GHz band with a data
bandwidth of lmbps to 2Mbps.
Almost every wireless vendor has shipped or announced an 802.1 1 -compliant
product. Symbol Technologies (Holtsville, NY), CyberLAN (Walnut, CA),
and Lucent Technologies (Murray Hill, NJ) are shipping the 802.11
DSSS products, Spectrum 24, LANEscape, and WaveLAN, respectively.
Symbol also sells specialized wireless equipment, such as pagers,
plus its own proprietary wireless product called Spectrum 1. Proxim's
802.11 entry will use FHSS. Prices for 802.11 PC card products fall
in the $500 to $700 range, with access points in the $1,500 to $2,000
range.
OTHER STANDARDS
Proxim is just one of the companies providing OpenAir-compatible products.
Its PC card adapter runs for $695, and the ISA version costs $595.
Access points start at $1,895. Compatibility among OpenAir products
is guaranteed, which is a major advantage over 802.11 products. Differences
in range and bandwidth, compared with 802.11 products, are negligible,
but not usually a factor in choosing a product.
A more limited de facto standard uses Netwave's AirSurfer technology.
Only a few companies utilize the technology, and, because the basic
designs come from one company, interoperability testing is much easier.
AirSurfer also utilizes the 2.4GHz band, and offers data bandwidth
rates of lMbps. Netwave takes wireless pricing to new lows. Wireless
PC cards cost just $250; access points only cost $800. The tradeoff
for the low cost is range, which is AirSurfer's main limitation, compared
with other products. As a result, an AirSurfer implementation requires
more access points to cover the same area as, say, an 802.11 product.
Because the AirSurfer access points are cheaper, the costs are comparable,
however. Netwave plans to make its AirSurfer Plus compatible with
802.11.
RadioLAN goes its own way in the wireless arena. It uses the 5.8GHz
band, but its bandwidth matches 1OBaseT Ethernet! RadioLAN utilizes
proprietary, narrowband microwave transmission, which limits separation
to about 150 feet, but some of its ISA card adapters can double as
access points. Because RadioLAN products can relay information between
access points, the idea of a total wireless network is feasible in
many circumstances. RadioLAN supports up to 128 workstations. PC card
adapters run $499; conventional ISA adapters cost $349, but the ISA
adapter/ access point costs $799. Compared with other solutions, RadioLAN
products utilize large, external antennas. The external unit actually
incorporates two antennas for improved performance; these double antennas
eliminate the impact of localized dead areas caused by signal reflection.
COMPARING COSTS
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| Figure 4: Thin wireless clients (PCs) can make use of an application server such as Citrix WinFrame. All data and programs are storied on the server, and no information is retained in the client. This reduces client costs and increases security. |
Calculating and comparing complete wireless costs with wired costs is important when wired alternatives might be the accepted solution. The key is to be sure that the solutions are comparable. Wired solutions often ignore wiring, relocation, and other related costs. In some instances, a wireless solution will be less expensive than a wired solution, especially when special work is required for cabling.
Wireless hardware pricing needs to be addressed as well. Discounts for VARs can be significant, especially for large installations. List prices should not be the determining factor, although most experienced wireless VARs already know the real costs. Check with your wireless network provider for details. Competition is steadily driving down the prices.
LIMITED BANDWIDTH FUNCTIONALITY
Educating users on wireless bandwidth is a major task for VARs. Wireless networks are slower than wired LANs, but they can be used effectively. The same holds true for remotely accessing a network with a low-bandwidth modem; it's slower, but still useful. Users simply need to be aware of the difference, so their expectations are realistic.
Wireless products have a significant speed advantage over modems, however. Wireless systems are great for low-bandwidth applications. Loading a small document, like a letter, using a wireless connection takes almost as long as loading it from a wired workstation. Large files and applications are another matter. It is best to install applications on the wireless workstation or limit users to small applications.
Another bandwidth-saving alternative, covered in the section on Special Cases, requires running the applications on the server and simply moving screen updates and input information between the wireless workstation and the wired network.
GOOD CANDIDATES
Client-server applications are also good candidates for wireless operation. Client applications are typically smaller than server applications, and the information exchanged between client and server is small. Still, testing applications using a wireless connection is warranted because good performance nught require that high-speed bursts be available on a wired network. Testing and demonstrations will help make user expectations realistic.
Minimizing all kinds of traffic on a wireless network is key to good application performance. The importance of eliminating broadcast messages has already been mentioned. Disabling or eliminating applications that generate similar types of network traffic is useful as well. Webcasting applications would fall in this category.
SPECIAL CASES
This article concentrates on wireless PC support, where the wireless network affects most users. However, a number of special cases exist where wireless solutions are more transparent, but equally useful. The most common is wireless routers. In this case, a pair of access points connects two network segments together, routing appropriate traffic across the wireless link.
ireless routers do away with many of the disadvantages of using wireless clients. First, the routers have an essentially unlimited source of power, allowing more powerful transmitters to be used with more sensitive receivers. Second, directional antennas can be used because the routers are typically fixed. Directional antennas increase the transmission range often from a few hundred feet to one or two miles. Thus, wireless routers can connect networks in two buildings or across a large open office area. Third, bandwidth often can be increased by using powerful transmitters or by multiplexing multiple transmitters and receivers. Finally, wireless routers can be very cost-effective because wired alternatives may be very costly or impossible.
Another special case is the thin wireless client implementation, which can reduce overall client costs and improve security. The thin client scenario depicted in Figure 4, based on Motorola's (Schaumburg, IL) thin client, is the SitePad Wireless Windows Terminal. Using Cruise Technologies' (Arlington Heights, IL) CruiseConnect technology, the SitePad connects to a Citrix (Fort Lauderdale, FL) WinFrame server. The SitePad is less expensive than a wireless laptop because the SitePad lacks peripherals, such as disks and CD-ROM drives. The lack of peripherals forces information to be kept on the server where it is more secure and more likely to be backed up.
The SitePad acts as the display and input device for Windows applications running on the WinFrame server. Pen-based input procedures make selecting forms and entering data easy. An on-screen keyboard allows users to enter small amounts of text, such as a name, without a keyboard or handwriting-recognition software. The SitePad is just one implementation of CruiseConnect. Other companies, such as Wyse (San Jose, CA), also have licensed CruiseConnect.
Other special cases include devices such as wireless pagers. Symbolics offers a two-way pager that looks and acts like its cellular brethren, but uses wireless access points instead of the cellular telephone compa- nies' access points. The pager operates when it is within range of an access point. Messages can be sent from any PC on the network. A person can be paged if a client is waiting in the reception area or if a net- work server is having problems. This type of local paging system has no incremental costs and is private. The system also applies to other single-function devices, such as bar code readers that are used for inventory control.
Wireless products allow for direct data entry and immediate data access. They reduce transcription errors and provide immediate feedback to wireless users.
FUTURE DIRECTIONS
Access points might contain some interesting features in the near future. More sensitive receivers, combined with more powerful transmitters, will extend the range of access points. This will reduce the number of access points needed to cover a given area, which, in turn, will reduce overall costs. Also in the future, look for access points with two wireless transceivers instead of the conventional wireless transceiver plus Ethernet connection. The dual-transceiver units might use different signaling techniques. For example, one transceiver might provide access to wireless workstations while the other transceiver connects the access points to each other. This will allow resellers to create a completely wireless, large network. It also will allow you to easily set up wireless networks where conventional network wiring is not available.
The second transceiver can use a directional antenna to increase the distance between its companion access point because both will remain in fixed locations. Additional bandwidth could be used so a large set of these access points could be linked together. Another reason to use a different kind of transceiver to connect two access points is the power limitations normally associated with PC card wireless transceivers. A device plugged into a wall outlet can pull additional power if necessary; a wireless device can't. In addition, more wireless Token Ring adapters will enter the scene. Although Token Ring support is rare, Proxim has a wireless Token Ring access point. Other vendors might follow suit as the number of wireless ad uncts to wired corporate networks grows. An 802.11 Token Ring access point eventually will see the light of day.
SUMMARY
Wireless networking solutions are now applicable across the networking spectrum. You are able to connect small workgroups and homes as well as corporatewide intranets. If you are not already using them, the time for investigating wireless products is now.
