Evolving Technology

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The potential of Wi-Fi is limited only by our imaginations. But one of the biggest roadblock for WLAN services had been the relatively small number of devices that were Wi-Fi-compliant. That impediment has been overcome-the marketplace is overflowing with Wi-Fi-enabled devices. Manufacturers are rushing to put wireless-enabled devices on store shelves so users can surf, email, send and receive large data files, view quality video, and listen to ear popping audio-all while on the go-using new and better smart phones, Pocket PC phones, PDAs, notebooks/laptops, tablet PCs, MP3 players, and other devices-devices that are now only a glimmer in the designer's mind.

Companies are also racing to come up with all kinds of innovative applications and products that can take advantage of Wi-Fi's capabilities: antennae that extend Wi-Fi's range, chip designs and signal processing algorithms that can mitigate the loss of speed over long distances, methods to carry voice as well as data traffic on Wi-Fi networks, devices, and applications that can do just about, well, anything.

The Wi-Fi market has grown quickly from a very small piece of the overall communications sector with only a few vertically integrated manufacturers and vendors, to today's quickly evolving marketplace. It seems that the entire communications industry is itching to get in on the action and integrate Wi-Fi into their product lines.

Chip Manufacturers

Intersil Corp., Broadcom Corp. and Agere Systems Inc. were the manufacturers in the forefront of the Wi-Fi phenomenon; at least as far as specialty chipsets were concerned. These manufacturers now face growing competition in the Wi-Fi market, not only from their counterparts in Asia but also from Intel, and others. In fact, Intel could quickly take the lead due to the introduction of its new collection of chips (under the name of "Centrino") that are designed to transform laptops and tablet PCs into portable offices.

Along with the trend toward Wi-Fi specific chipsets, there are sub-specialties that are helping Wi-Fi to gain worldwide acceptance. Within these sub-categories there are:

• Chips that help reduce power needs.

• Dual-band and multi-standard chips (802.11a/b, 802.11b/g and 802.11 a/b/g).

• Chips that can provide lower cost solutions.

• Chips that provide added security enhancements.

With chip manufacturers jumping headfirst into the red hot embedded Wi-Fi market, seamless wireless functionality is being upgraded and enhanced in everything from PDAs, cell phones and laptops to antenna technology, network cards, and more.

The reader might ask, why are chip manufacturers so important to Wi-Fi? The primary reason is power-Wi-Fi is a power hog. The transmission and receipt of voice or data is the single most power-hungry mode of any wireless device, and Wi-Fi is no exception. The processing power necessary for end-users to use a Wi-Fi-enabled device to send and receive data drains the small batteries that are commonplace in most mobile computing devices. In the past, this, and the size of the average chipset, made Wi-Fi impractical for small devices such as PDAs and cell phones.

Chip manufacturers, however, have made it to first base-they have found ways to reduce the size of their chips (although more needs to be done). Some are expected to round second, in the near future, with newly designed chipsets that should help to put a lid on Wi-Fi's power gobbling ways.

The chipset industry, while not hitting a home run, is at least on base. Many of the latest-generation Wi-Fi chipset designs do cut power needs by introducing performance enhancement techniques into the design of the chipset, for example:

• Texas Instruments's revised version of the ACX100 WLAN chip consumes only a tenth as much power in standby mode as its predecessor.

• Advanced Micro Devices (AMD)'s Alchemy Solutions Am 1772 wireless LAN chipset and mini-PCI card for notebooks is designed to be ultra-efficient and ultra-compact.

• Intel's Calexico, which is similar to the Alchemy chipset except it is a hybrid 802.11a/b combo, has been deployed as part of the company's Centrino line.

With the proliferation of Wi-Fi specifications (i.e. 802.1la, b and g), device manufacturers are also clamoring for multi-standard chipsets. Again, the chip manufacturers have stepped up to the plate, as in the following examples:

• Broadcom has launched a simultaneous dual-band 802.1la/b chipset using an all-CMOS design. It is a three-chip design that comprises the BCM4309 baseband/MAC chip, which supports the 802.11b and 802.1la protocols as well as IEEE-802.1X security, the BCM2050 2.4 GHz radio interface chip, and the BCM2060 5 GHz radio chip. The BCM4309 dynamically selects the best performance available at either 2.4 or 5 GHz. This enables end-users to make a network connection and an ad hoc user connection simultaneously, among other things.

• Intersil's PRISM Duette, a dual-band 802.11a and 802.11g wireless LAN solution that is capable of transmitting high-speed video, voice, and data. It is fully backward compatible with the installed base of over 15 million 802.11b systems worldwide.

• AMD is expected to introduce its next-generation of Wi-Fi chips with a multi-standard design, i.e. a hybrid 802.11b/a/g chip.

There's lots more that could be said about how the chip manufacturers have embraced Wi-Fi but... suffice it to say that these guys have exceeded expectations and through their efforts, Wi-Fi has taken a giant step forward.

Shipments of chipsets for Wi-Fi grew to 23 - 25 million for the year 2002 versus less than 8 million in 2001, at least according to a year-end 2002 report from the market research group Allied Business Intelligence Inc. (ABI). The ABI report, entitled, "Wi-Fi Integrated Circuits: Industry Dynamics, Market Segmentation and Vendor Analysis for 802.11a/b/g," indicates the following:

• By 2004 revenue from dual-band chip sets will exceed that of 802.1 la, b or g.

• Chipsets will be targeted for embedded implementations particularly in battery-constrained devices such as PDAs and mobile handsets.

• 802.11g chips will have a significant impact in the SoHo/retail market and will comprise 18 percent of chipsets shipped in 2003.

The emergence of multiple 802.11 variants (a, b and g) and constant innovations in chip design are creating an extremely dynamic Wi-Fi integrated circuit market.

Extending the Range

This section shows the reader the latest innovations in extending the range of a Wi-Fi network, in providing dual-mode networking, and in transmission security. It doesn't cover typical range extender antennae such as those offered by HP/Compaq, Avaya and others. There is a general discussion of antennae in Chapter 19.

What's New?

Wi-Fi's limited range of transmission causes some concern in the marketplace. Again, many individuals and companies are working to resolve the problem. Let's look at some of the more interesting and promising antenna solutions. (It's interesting to note that most of the companies working on this issue are start-ups.)

EtherLinx: Reminiscent of the early PC days, EtherLinx Communications, a small start-up working out of a garage in Campbell, California, has come up with a way to extend Wi-Fi's range from a mere few hundred feet to up to 50 miles (80.4 kilometers) and still maintain incredibly high data transmission speeds. The data transfer rate over a long distance has been successfully tested at 10 Mbps, but when it reaches the market EtherLinx will offer only 2 Mbps (which is still faster than a T-1 line or most DSL services) to ensure that they provide their customers with consistent quality of service.

The key to EtherLinx's success is a single, small antenna that transmits data faster than either Cable Modem or DSL service to a tiny $150 receiver mounted to the side of the end-user's premises. Then that receiver is hardwired to a PC using standard CAT 5 wiring. Individual repeater devices can retransmit signals, so non-line-of-site signal paths can be handled by deploying repeaters in a mesh or other topology away from the base site.

The company says its technology even addresses two of the other most notable challenges for Wi-Fi networks-security and privacy. That is because transmitted data can be received only by the company's equipment, and each receiver has a unique address. This makes it relatively easy to detect, and then track, anyone who's trying to gain unauthorized access.

During 2002, EtherLinx operated a small, for-pay trial in Oakland, CA and is currently slated to begin covering the small city of Campbell, CA (an area in which DSL service is not available) in the near future. Interestingly, Congressman Mike Honda, DCA, met with the company's founders, after which he scheduled a demo and presentation in Washington, D.C. Honda says he wants to see how quickly this technology can be deployed elsewhere in the nation.

Other companies-Nokia, Iospan Wireless, and Navini Networks-are trying to duplicate EtherLinx's achievements; but to date none has met with EtherLinx's success.

Vivato: This startup company has introduced two FCC-approved switches that can increase the range and capacity of Wi-Fi antenna systems. Instead of providing service to only several dozen people situated within a few hundred feet of the transmitter, the Vivato switches enable an antenna to be accessible to legions of users from long distances. In an open environment, the outdoor switch can transmit to a client four miles (6.4 kilometers) away, while the indoor switch has a range of approximately 2000 feet (609.5 meters).

The switches, which are about 3.5 feet by 1.5 feet by 2 inches (1.06 meters x 45.72 centimeters x 5.08 centimeters), create directional beams rather than radiating energy "isotropically" (in all directions). This makes it possible to greatly extend the range of the system at low power and reach more users. At the same time, the switches can maintain an average transmission speed of between 6 and 11 Mbps and provide security using state-of-the-art encryption, the latest authentication methods, and virtual private networking. The company also thinks that the sensitivity of their technology makes the system ideal for detecting potential intruders.

The technology Vivato uses actually stems from 1950s research on a phased-array antenna for the military. That technology makes it possible to electronically "steer" numerous radio beams from a single point. The multi-element antenna array is assembled using ordinary antenna elements. Special circuitry and algorithms perform the digital signal processing required to implement the digital beam steering operations, which consist of applying the array spatial signal processing algorithms to form the digital antenna array pattern from the multiple antenna inputs.

When beams are focused properly, the signal strength is increased, and when you use a large number of them, you can greatly increase an antenna's traffic capacity. In practice, the switches will determine each authorized Wi-Fi-enabled device's location so the system can send a high-powered signal straight to that specific device. This is contrary to the conventional Wi-Fi transmission technology where a single, low-powered signal is transmitted in all directions and only some of it is gathered by the receiver's antenna.

A Vivato spokesperson says that the company expects their technology to be especially suited to office buildings and campus environments (e.g. universities and hospitals) because it enables so many people to use a single 'Wi-Fi Internet connection simultaneously. Ken Beba, the company's chairman and CEO, is very enthusiastic about the new switch. He predicts that the product "will change the way people think about the physics of Wi-Fi."

Vivato's indoor switch is designed for placement in, say, the corner of a large office where it can provide wireless service throughout a building. This centralized approach of transmitting a series of beams is in sharp contrast to other companies that try to extend the range of Wi-Fi by creating meshes of overlapping access points.

Note 

Even though France has yet to certify Vivato's technology, the 2003 Cannes Film Festival had wireless broadband access, thanks to Vivato, Intel Corporation and France's KAST Telecom. This group created one of the world's largest Wi-Fi HotSpots using the Vivato Wi-Fi switch, enabling anyone with a Wi-Fi-compatible computing device to gain wireless high-speed Internet access as they strolled along the Croisette and the Bay of Cannes.

Moreover, although Vivato's initial audience is corporate buyers, extending the geographic range of wireless Internet networks could help open the market to WISPs and even traditional ISPs looking for alternatives to high-speed Cable Modem and DSL connections.

Mesh technology: Vivato is only one of several start-ups working to extend the range and performance of Wi-Fi networks. As many as two dozen other companies have appeared with alternative approaches, many of which involve mesh networking technology, which uses multiple antennae to pass data around like a bucket brigade.

Typical of these innovators is MeshNetworks, Inc., a company founded in 2000 to commercialize technology originally developed for military application. Soon after receiving the FCC's regulatory approval of its Mesh Enabled Architecture (MEA) and MeshLAN Multi-Hopping 802.11 network products, the company began shipping its products to customers.

Wi-Fi networks use access points to create wireless zones with a radius of about 300 feet (91.4 meters) around each access point. MeshNetworks uses a technique called "hopping" to extend the range of a Wi-Fi network. Users of the company's MEA and Mesh-LAN products send and receive networking signals that "hop" from one mobile computing device to another until they find one hooked up to an access point. According to the company, this technique can extend a network's range to about 1500 feet (457.2 meters), which is enough to cover an office building using only a single Mesh-Networks access point.

MeshNetworks' target market is the very large enterprise, especially companies converting a campus or office building from a wired to a wireless setup. Gemma Paolo, a wireless analyst with In-Stat/MDR, extrapolates that that market is ripe for MeshLAN technology. But, at the same time, Paolo suggests that currently such a network would have to be a really big deployment to make economic sense. Paolo opines that "with the cost of access points coming down so low," the MeshLAN method might not be worth it. Of course, MeshNetworks disagrees. Rick Rotondo, its vice president of technical marketing, says that the company's product improves overall performance and cuts costs, too. He points out that MeshLAN modems don't just find an access point to use; they find the one currently subject to the least traffic.

Other companies are also working on mesh network technology. For instance, another start-up company, SkyPilot Network, is making equipment and providing mesh networking service for the residential and small business market. Nokia, an industry giant, is also scouting the mesh networking market.

Smart antenna technology: California Amplifier's adaptive digital beamforming technology, which it calls "RASTER," has great potential for driving broader implementation of Wi-Fi products in enterprise, HotSpot, and campus environments. RASTER uses multiple antennae and powerful digital signal processing to dynamically form an antenna pattern optimized to a desired client (e.g. computing device) at any given instant, based on interference and other wireless channel conditions. RASTER technology is integrated with 802.11's Physical Layer and Media Access Control (MAC) processing, allowing an access point to form, transmit and receive beams; cancel interference; and better utilize high multipath, non-line-of-sight channels, thus serving to significantly enhance a network's coverage and data throughput, particularly in areas where poor signal quality is an issue.

Note 

California Amplifier is better known for its broad line of integrated microwave solutions used primarily in conjunction with satellite television and terrestrial broadband wireless applications, than for smart antenna technology that can enhance Wi-Fi's performance.

In a typical Wi-Fi system, an access point acts as a hub-coordinating communications between many client stations. RASTER resides at the access point; thus, unlike other approaches to increase throughput and coverage, products based on RASTER technology will not require any changes to the 802.11 standards, and is expected to work with commercially available NIC cards.

However, development of RASTER-enhanced products that are cost-competitive with standard access points requires integration into a next generation 802.11 chip. To that end, California Amplifier is currently discussing licensing agreement terms with 802.11 integrated circuit developers. Keep your eyes peeled for announcements concerning RASTER chipsets.

Multi-mode Antennae

Wi-Fi and cellular seem to have the makings of a perfect partnership. However, this partnership requires multi-mode antenna technology. In other words, an antenna that can receive signals from both a cellular network and a Wi-Fi network. At least one company has come up with a solution. In a breakthrough that indicates the shape of things to come, SkyCross Inc., a trailblazer of next-generation antenna technology, has announced that it has developed a single embedded antenna that supports cellular, GPS, Wi-Fi and Bluetooth applications. The company claims that its antenna performs as well or better than antennae that support only single functions. Not only does the SkyCross antenna allow multi-mode mobile devices, but its small footprint encourages device manufacturers to create smaller, more compact equipment.

Many Wi-Fi networks operate in dual-mode, 802.11b and 802.11a (and 802.11g is expected to be included in the near future). Antennae that can send signals over both sets of frequencies (2.4 GHz and 5 GHz) are needed. Orinoco, an established vendor offering various Wi-Fi gear, has an antenna with the necessary flexibility. Its AP-2000 5 GHz Kit consists of a radio card and a special multi-mode antenna that mounts directly on the access point and supports all three flavors of 802.11-a, b and g.

Boosting Wi-Fi's Security Quotient via Antenna Technology

An "optical antenna" is like a standard electronic antenna in that both collect electromagnetic energy (light or radio waves) from a volume of space and channel it through to a receiving element, or, conversely, transmit energy originating from a small source over a large area. Thanks to a carefully designed, geometrically-shaped lens component, optical antennae can be compact and yet can be used to direct radio frequency (RF) energy along beam-like paths, thus enhancing a Wi-Fi network's security quotient. This is the type of optical antenna developed by researchers in the U.K. at the University of Warwick's engineering department. It consists of a combination of precise curvatures on the lens and a multi-layered filter. Although optical antennae are already on the market, the University of Warwick design brings such precision to the technology that it can detect a signal on a single electromagnetic wavelength.

Note 

This research effort has also led to the development of a new compact RF antenna for 2G GSM and 3G UMTS cellular telephones.

Ultimately, such advanced optical antennae can provide particular strategic advantages in areas, such as Wi-Fi networks, where large amounts of information need to be sent quickly and securely. Because of the way Wi-fi networks are set up and the way that ordinary half-wave and quarter-wave dipole antennae radiate electromagnetic waves in all directions, it is possible for just about anyone to tap into a network without the knowledge or permission of the network administrators. (There are even terms to describe such activity: "warwalking" and "wardriving") However, in the case of an optical antenna that transmits and receives infrared signals (i.e. the invisible portion of the electromagnetic spectrum that lies between visible light and radio waves), the beams can be more tightly controlled.

Unlike typical radio frequencies, which can pass right through walls, infrared energy makes a network more secure because it is contained within a room and doesn't easily leak out through the walls and windows (it is even possible to coat windows so they fully reflect infrared energy). It's also possible to create a precise beam between one point and another, which doesn't diverge (spread out) much in comparison to a conventional radio frequency beam. Concentrating the signal energy in a beam this way makes it possible to transfer Wi-Fi network data over distances of up to three miles. Moreover, since optical technology provides greater bandwidth over greater distance than lower frequency radio technology, more information can be transferred during a measured time interval.

The University of Warwick's optical antenna has been licensed to Optical Antenna Solutions, a company based in England. One of the first ideas under development is for credit card payment systems, e.g., equip credit cards with infrared links for use at gas pumps and supermarkets.

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