During this past year, wireless local-area networking, specifically 802.11 Wi-Fi, experienced unprecedented growth during a crippling downturn. According to Mike Wagner, director of marketing at major WLAN hardware supplier Linksys, unit growth exceeded 100% in the SOHO market from 2001 to 2002. It's no wonder Cisco recently bought Linksys (Fig. 1). What started out as a wireless technology to extend enterprise Ethernet local-area networks (LANs) has become the number one home-networking technology. Now it's paving the way to making mobile Internet access ubiquitous, as a huge number of public access points becomes available. This technology is developing as fast as the IEEE standards groups can meet and hammer out final standards and as quickly as the chip vendors can design and field competitive products. New products, companies, business arrangements, and technology updates now take place hourly.
Wireless LANs (WLANs) owe their success primarily to continuing standards and certifications efforts. New standards continue to flow out of an extensive IEEE 802.11 Task Group headed by Philips Semiconductors' Stuart Kerry. Today, a number of standards efforts are under way (see "IEEE 802.11 Wireless Ethernet Standards Summary, p. 50"). While the core defining standards 802.11b and 802.11a remain sound, the newer 802.11g standard awaits ratification. The new g standard promises to be the big winner. Semiconductor companies eager to get a jump on the competition are already producing chips to the g draft standard before its ratification, expected this month or next. For a standards update, see www.grouper.ieee.org/groups/802/11/.
Despite the standards, the industry experienced early interoperability problems. The Wireless Ethernet Compatibility Alliance was formed to address the problems. Now called the Wi-Fi Alliance, this nonprofit group promotes WLANs and manages a product certification testing program developed to validate new products. Products that pass the rigid testing receive Wi-Fi (wireless fidelity) certification. While all certification efforts to date center on 802.11b products, a program for 802.11a products has begun, and a testing program for 802.11g products is in place. Check out Wi-Fi at www.wi-fi.org. (Also see electronic design, "Approving A Standard Is Anything But Standard," April 14, p. 51, ED Online 3152.)
THE SECURITY ISSUE Perhaps WLAN's most controversial feature is its vulnerability to eavesdropping. Anyone with a sensitive 802.11 radio and a directional antenna can listen in on company traffic from a nearby location. The 802.11b standard's Wireless Equivalency Protocol (WEP) security feature implements an encryption system to protect sensitive data and traffic. WEP is initially disabled, so the user must turn it on. Few used this feature, but those who did found that it could be cracked. The problem isn't the capable RC4 encryption algorithm, but the way that WEP handles the keys. A new key must be manually entered for each session. The IEEE 802.11i task group is hard at work on a bulletproof security portfolio that should finally fix the problem.Meanwhile, secure communications are possible if users turn on WEP and change the keys regularly. WLAN product vendors are now implementing their own brands of security that are superior to WEP. The Wi-Fi Alliance has deployed the Wireless Protected Access (WPA), which can be licensed by silicon and/or equipment vendors to ensure improved security. The 802.11i standard will ultimately fix the problem, but immediate solutions exist if it's a major issue.
HOT SPOTS ARE HOT A hot spot is just another name for a public access point for WLAN connectivity. Access points cover a wide area (max radius of about 300 feet) in public places like convention centers. They connect to a wireless Internet service provider (WISP), where service is offered on a cost-per-connection or subscription basis. The first hot spots showed up in airports. A high percentage of Starbucks coffee shops have hot spots. Even McDonald's is giving it a try. Several thousand hot spots are available right now, but that number should grow exponentially as hotels, shopping centers, college campuses, and other public areas respond to the growing demand. Some are predicting over 20,000 hot spots to be in place by the end of 2004.Hot spots have become so hot, they've finally attracted the attention of big business as well as early startups like Wayport and Boingo. Cell-phone carriers like T-Mobile are emerging as a major force as they hedge their bets against a major threat by 802.11 to their cell-phone data business. New companies are vying for what may become a major new wireless service. Cometa Networks, a joint venture of AT&T, IBM, and Intel, expects to implement thousands of hot spots in the U.S. in the coming years.
But the big question remains: Do many laptop or PDA users want, need, or have the ability to pay for all of this service? Some say that widespread hot spots will kill the 3G cell-phone effort. While 802.11 probably won't kill 3G entirely, it certainly has delayed 3G's "splash" and ultimately decreased its desirability. Cell-phone carriers haven't had great success with data services anyway. Currently, 2.5G systems such as GSM/GPRS and cdma 2000 1xRTT are adequately providing data services. Upgrades to near-3G standards, like EDGE and faster cdma2000, are easier and less expensive to implement than any wideband CDMA 3G system. So will 3G occur? It probably will happen after a delay of several more years. If robust 802.11 hot spots are as successful and widespread as everyone hopes, there may not be a driving need for 3G.
With such massive growth during a protracted economic downturn, it's no surprise to see so many semiconductor companies addressing this opportunity. This arena has become brutally competitive, as companies seek ways to differentiate themselves and gain some advantage.
Agere is one of the original players in the 802.11 market. The company's latest, the WaveLAN multimode chip set, covers 802.11a/b/g. The WL54040 RF transceiver is made with biCMOS. It uses a low IF for the OFDM in the "a" and "g" modes and a zero IF in the "b" mode.
Consisting of CMOS, the WL60040 multimode media-access-controller (MAC) chip supports 802.11 a and b operation and the g draft standard. This MAC also handles the draft standards for "e" (QoS), "h" (power control for a), and "i" (security). Its security features the basic WEP, support for WPA, and advanced encryption standard (AES) capability.
The WL64040 baseband chip also is made with CMOS. It handles all DSP for the OFDM and CCK modulation. Its patented antenna diversity circuit provides enhanced data throughput and improved signal coverage.
Fourth in the product line is the WL54240 dual band silicon-germanium (SiGe) power amplifier. Its separate 2.4- and 5-GHz amplifiers have power control and a power detector on-chip. Samples will be available this quarter.
Two years ago, Atheros became the first vendor with an 802.11a chip set. The company's latest, the AR5001X Combo LAN a/b solution, draws on its experience with OFDM. The three-chip set includes the AR2111 2.4-GHz radio-on-a-chip (RoC), the AR5111 RoC, and the AR5211 multiprotocol MAC/baseband processor. All three modes—a/b/g—are supported, plus e, f, h, and i standards.
A leading vendor of 802.11 chips, Broadcom is the first to market with a combined a/b/g chip set. Millions of its 54g chip set have sold. This set also is already found in Linksys products and some Dell laptops. Broadcom's OneDriver software updates the chip set if changes in the g draft occur.
Another chip-set option for engineers designing 802.11 solutions, Envara's WiND502, supports the a and b modes. It consists of the EN202 MAC/Baseband and the EN303 RF chip. The chip set meets all major 802.11 standards, consumes extremely low power (300 mW), and provides superior receiver sensitivity. The 5-GHz circuitry covers the European WLAN bands as well as those proposed 5-GHz segments specific to Japan. Envara supplies reference designs, host driver software, and chip-set firmware to help designers reduce development time and cost. The forthcoming WiND512 chip set also covers g mode operations.
IceFyre Semiconductor of Ontario, Canada, is betting on the 802.11a mode. Its ICE5350 5-GHz OFDM physical-layer (PHY) chip includes not only the full baseband processor but also the complete RF transceiver. Several patented innovations implemented in this device enable it to deliver 80 mW of transmit power at very low power consumption. High power efficiency and performance is achieved through innovative Peak-to-Average Power Ratio reduction algorithms, a unique RF architecture, and integration of both the baseband and RF sections with 0.18-µm CMOS. This single-chip design significantly reduces the bill-of-materials cost as well.
One of the longest-running suppliers of 802.11 products is Intersil. Its PRISM line of chip sets and interface cards appears in a host of designs. The company is currently sampling a WLAN chip set that supports the 802.11g draft standard. Called the PRISM GT, this design's zero IF architecture integrates the filters as well as the synthesizer and transceiver on one chip. Intersil also recently updated its software to include the Wi-Fi Protected Access (WPA) security feature.
If any doubt lingered on whether laptop makers were serious about including 802.11, it was overcome by Intel's recent announcement of the Centrino Mobile Technology. Centrino is the brand name of the Intel Pentium M Processor, 855 chip set, and the PRO/Wireless network connection that PC manufacturers can use to implement 802.11b-based laptops. The Pentium M is a super-low-power, 1.6-GHz version that extends battery life by as much as 40% in some designs. While Centrino's wireless segment only covers 802.11b, future versions should incorporate a and g capability.
Network chipmaker Marvell Semiconductor also joined the WLAN chip-set brigade with its Libertas family of client and access point devices for the 802.11g standard. Its 88W8310 Baseband/MAC chip contains an ARM processor and supports both WEP and the forthcoming 802.11i AES encryption standard. Support for PCI, miniPCI, and Cardbus interfaces is provided. The 88W8010 RF transceiver eliminates the need for SAW filters and includes highly linear on-chip power amplifiers with 23- and 20-dBm output, respectively, for 802.11b and 802.11g modulation schemes.
Another participant is Maxim Integrated Products and its 802.11b radio. The MAX2820 is a zero IF transceiver made with SiGe. Its 7- by 7-mm package is one of the smallest footprints, if not the smallest footprint, in the industry. Receiver sensitivity is 85 dBm at 11 Mbits/s, which is estimated to be 2 to 3 dB better than competing direct conversion designs. That translates to 26% more indoor range.
Also entering the fray with 802.11 chips is Philips Semiconductors. The widely used biCMOS SA2400 zero-IF radio works with most other baseband chips, such as those from Texas Instruments (TI).
SiGe Semiconductor's latest 802.11 part is the RangeCharger SE2529L, a multimode external power amplifier for 2.4-GHz WLAN systems. It complies with 802.11b and g draft standards. Other available versions include the SE2520L, which is part of Broadcom's 802.11b reference design.
A chip company new to the WLAN area is Silicon Integrated Systems (SiS). Its SiS160 MAC for 802.11b systems is made with 0.18-µm CMOS chips, which are based on SiS's extensive ASIC experience. The chip has power-saving features and a full complement of security solutions.
Another newcomer to WLAN products is Synad Technologies Ltd. of the U.K. This fabless semiconductor company's Mercury5G a two-chip set delivers connectivity and interoperability for 802.11a, b, and g (Fig. 2). Kevin Mapplebeck, Synad vice president of marketing and business development, indicates that current WLAN equipment vendors lust for some way to differentiate themselves from the overwhelming competition.
Product differentiation isn't easy with products that are driven, defined, and limited by strict standards. Synad's goal is to make a chip set that will allow any laptop or other 802.11-enabled device to move seamlessly from one access point to another and automatically seek out and connect to any access point present with minimal user involvement. Known as Agile RF, this Synad innovation not only greatly accelerates channel switching, it also regularly samples the RF environment to see what's going on. With this ability, laptops can connect to both 802.11a and 802.11b/g networks concurrently.
Longtime 802.11 chip supplier TI brought out the TNETW1130 MAC/Baseband processor, which covers 802.11a/b/g modes. Using TI's Auto-Band technology, it delivers seamless interoperability between the three different physical-layer standards. Users can roam with a continuous connection from one network to another without manually readjusting any network settings. The ability to roam from one WLAN to the next has become key among users.
The TNETW1130 also supports the new AES encryption standard for use in the upcoming 802.11i standard, as well as the legacy WEP and WPA. This chip's quality-of-service (QoS) engine supports the enhanced distributed coordination function (EDCF) and hybrid coordination function (HCF) as specified in the 802.11e draft standard. This will help facilitate quality-sensitive applications such as voice over WLAN.
Another significant TI announcement is WANDA (Wireless Any-Network Digital Assistant). This combination 802.11b-GSM/GPRS cell-phone/Bluetooth-PDA concept design lets users roam from one type of network to another (Fig. 3). It contains TI's TNETW1100B 802.11b chip set, the BRS6100 single-chip Bluetooth transceiver, the TCS2100 GSM/GPRS cell-phone circuits, and the OMAP 1510 applications processor made up of an ARM925 and a TI 320C55x DSP. The WANDA reference design can be adapted to pocket PCs, smart phones, laptops, or other products that require maximum connectivity.
| Task Group | Status |
| a | The original high-speed standard; 54 Mbits/s using OFDM in the 5 GHz; ratified. |
| b | The initial and primary defining standard; 11 Mbits/s using DSSS in the 2.4-GHz band; ratified; used in most (90%+) WLAN products and activities. |
| e | Goal is to improve the MAC and improve and manage QoS, provide classes of service, and enhance security and authentication. It should facilitate applications such as VoIP over wireless. Ratification expected in the third quarter of this year. |
| f | Inter-Access Point Protocol (IAPP) development; permits access points to communicate with one another to facilitate roaming, LAN-to-LAN handoffs, and links to other systems; essential as the number of access points grows; a work in progress. |
| g | High-speed extension of the 802.11b standard; implements speeds to 54 Mbits/s in the same 2.4-GHz bandwith backward compatibility with 802.11b products; ratification expected in June/July 2003. |
| h | Modifications to the 802.11a standard to implement changes that will permit its use in Europe; MAC and HY changes to implement spectrum and power-management features compatible with European standards; ratification expected later in 2003. |
| i | Project to enhance security of transmission in a/b/g radios; improves encryption by using the AES with 64- and 128-bit keys and authentication methods over the original Wireless Equivalent Protocol originally built into the a and b standards; ratification expected in 2004. |
| j | Modification to 802.11a standard to add 4.9- to 5-GHz channel-selection capability so that the system is usable in Japan. |
| k | Project to define Radio Resource Measurement enhancements to provide interfaces to higher layers for radio and network measurements; adds load balancing, roaming, and co-existence, plus other management and measurement features. |
| m | An ongoing maintenance-related task group to watch over, update, and correct the main a, b, and g PHY and MAC standards. |
| n | The High Throughput Study Group tasked to speed up the MAC to permit future faster, next-generation options. |
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Airshare www.airshare.org Agere Systems (800) 372-2447 www.agere.com Atheros Communications (408) 773-5344 www.atheros.com Broadcom Corp. (408) 543-3311 www.broadcom.com Envara +972-9-776-6211 www.envara.com Hyperlink Technologies Inc. (561) 995-2256 www.hyperlinktech.com IceFyre Semiconductor Corp. (613) 599-3000 www.IceFyre.com Intel Corp. (800) 538-3373 www.intel Intersil Corp. (480) 607-4840 wwwintersil.com |
Linksys Group Inc. (800) 546-5797 www.linksys.com Marvell Semiconductor Corp. (408) 222-2500 www.marvell.com Maxim Integrated Product (800) 998-8800 www.maxim-ic.com Philips Semiconductors (800) 234-7381 www.semiconductors.philips.com SiGe Semiconductors (613) 820-9244 www.sige.com Silicon Integrated Systems +886-2-8913-1168 www.sis.com Synad Technologies +44(0)118-929-8029 www.synad.com Texas Instruments Inc. (214) 480-7963 www.ti.com/wla |