Future wireless networks will intermingle devices that depend on a wide variety of protocols. Home PCs, PDAs, TVs, stereos, cordless phones, peripherals, garage door openers, and security systems will all network with such diverse standards as HomeRF, Bluetooth, 802.11, HiperLAN/2, DECT, ultra-wideband, and Zigbee since each protocol has advantages for different applications and environments.
Many of these standards use the same license-free ISM bands (at 2.4 GHz or 5 GHz) and can interfere with each other’s operation, so Wireless Wars have developed, and analysts try to predict winners and losers. Even though the benefits of wireless mobility are compelling, the big loser in a Wireless War is the consumer since this â€œTower of Babelâ€ causes confusion and stalls market growth.
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Consumers don’t care about the underlying technologies. They just want products that work, and work anywhere â€“ at home, school, the office, a hotel, the airport, in the car, etc. With mobile devices, they will move between different types of networks â€“ between WANs, LANs and PANs, data networks and voice networks, and even networks based on different international standards. Multi-mode products based on new chip technologies will automatically sense and adapt to available wireless networks and bridge between different network standards.
Software Defined Radios
Software-defined radios (SDRs) can alter operating parameters of frequency, modulation, or output power by simply making changes in software instead of replacing hardware components. The earliest examples were mobile phones that connect to digital networks when possible and fallback to analog mode when necessary. They use multi-mode baseband technology to understand different protocols such as TDMA and CDMA, and use multi-band radio technology to operate in different frequency bands.
Semiconductor companies are now bringing the multi-protocol concept to wireless LAN markets. These companies include Atheros, Embedded Wireless Devices, Envara, Intersil, Mobilian, Proxim, nBand, Silicon Wave, and others.
For example, Embedded Wireless Devices (EWD) has introduced its Valhalla family of multiprotocol chips that support the 54-Mbit/sec IEEE 802.11a standard and the European HiperLAN/2 standard, each operating at 5.7 GHz. The chips also support 2.4 GHz wireless protocols such as 802.11b, Bluetooth, and HomeRF. And they support 2.4 GHz and 5 GHz operating simultaneously, thus enabling bridging between multiple standards.
EWD’s chips integrate the company’s own 32-bit CPU, DSP, and eMOS multitasking operating system, which handles fast context switching and interrupt servicing to allow moving between one protocol and another for voice and data communications. The processors interface with either separate radio chips for 2.4 GHz and 5 GHz or to a single chip containing both. They listen to the RF signals and then establish a link using a recognized protocol.
Drivers of the Multi-protocol Market
1. Different Regions â€“ Spectrum allocation in the 2.4 GHz ISM band is fairly consistent worldwide, but allocation in the 5 GHz band varies by region, so the ability to adjust on demand is a welcomed feature by both OEMs and consumers. SDRs allow OEMs to work with a single chipset for different countries and different standards, enable faster development, and make it easier to adapt to change.
2. Different Standards â€“ Design tradeoffs among various wireless standards result in sweet spots that target different markets, environments, applications, and regions. Since these tradeoffs include things like power consumption, range, infrastructure complexity, bandwidth, security encryption, cost, and size; it’s not possible to have a single standard that serves all needs. SDRs allow products to work with different network protocols that can be optimized for each application or environment, rather than force-fitting a popular standard into a space where it’s not well suited. In enterprise offices, SDRs will support an easier transition from 802.11b at 2.4 GHz to 802.11a at 5 GHz. And in homes, SDRs will support bridging between HomeRF (for convergence of voice, data and most entertainment applications) and 802.11a (for the high bandwidth needs of HDTV video streaming).
3. Mobile Roaming â€“ With one plug-in card, mobile users will be able to connect to different networks they encounter, whether it is 802.11a in the office, 802.11b at Starbucks, HomeRF at home, Bluetooth in their mobile phone, or HiperLAN/2 when traveling in Europe. The use of unlicensed spectrum in public hotspots generated lots of interest recently, but the slower WAN solutions still offer the widest coverage. SDRs will allow users to have â€œalways onâ€ WAN connections that then shift to higher-speed WLAN connections when within range of a hotspot. And for telephone applications, SDRs will allow mobile phones to act as cordless phones when they come home.
4. Remote Upgrades â€“ As standards evolve, equipment can be upgraded in the field instead of requiring replacement, and this will help the wireless market to progress more rapidly while offering a sense of investment protection. As QoS and security enhancements come out of the 802.11e and 802.11i task groups, SDRs will make it easier to get these upgrades deployed. This assumes that existing cards have the remote upgrade capability, which they don’t today. Many enterprise access points are already upgradeable, but most PC adapters are not. As upgradeable adapters come to market, they will carry a price premium but give consumers a choice over the lowest cost or most flexibility. As prices fall, I expect all adapters to use SDRs for upgradeability.
5. Regulatory Approval â€“ In September 2001, the FCC announced plans to permit the use of SDR technology in ISM bands to make it easier to change frequency, modulation, and power parameters without requiring new equipment certification. The commission hopes this action will enable development of products supporting multi-mode, multi-band, multi-standard, and multi-service.
6. Steerable Antennas â€“ Directional antennas can greatly extend the range of wireless networks by focusing higher power levels in a manner that avoids interference with other devices. For gateways, access points, and wireless repeaters, SDRs can also help extend the range through the intelligent steering of electronic directional antennas.
Innovative semiconductor companies are introducing software-defined radios for wireless LANs this Year, and we already see examples of multi-mode in mobile phones and enterprise wireless access points. I expect to see multi-mode PC adapters in 2002 that help move the industry away from the confusing Wireless Wars to a more cordial Wireless Wedding. Consumers and industry will both benefit from this new direction.