5-GHz wireless LAN chip set rolls as IEEE 802 meets.
Electronic Engineering Times, July 10, 2000 p6
By Mannion, Patrick
MANHASSET, N.Y. - Just in time for the IEEE 802 plenary meeting on wireless LAN standards in La Jolla, Calif., this week, Radiata Communications has announced it will roll out an 802.11a-compliant, all-CMOS radio and modem chip set by year's end. The chip set will enable a 5-GHz wireless PC card with costs on a par with 802.11b devices-but with at least five times the throughput and in a much cleaner band, the company said.
If Radiata can deliver on its promise, many issues on the agenda in La Jolla will be called into question, particularly those involving the high-data-rate 802.11b standard (for data transmission beyond 11 Mbits/second) and the coexistence of the various wireless standards in the crowded 2.4-GHz band. But those issues represent only the tip of the iceberg that engineers will grapple with at the Hyatt Regency today through Thursday.
Those attending will hear arguments for harmonizing the HiperLAN2 and 802.11a MAC standard of the European Telecommunications Standards Institute's Broadband Radio Access Networks, and will vote on proposals to implement essential quality of service (QoS) protocols for wireless LANs (WLANs).
QoS has moved to the fore of 802.11 concerns with the arrival of voice into what was essentially a data-centric network.
The drive for end-to-end QoS is being spearheaded by companies such as AT&T, Sprint and Verizon, which are looking to push video, audio and data down the same pipe, making deterministic latency, packet classification and security essential.
Work on wireless LAN standards will share the spotlight with efforts on personal-area networks. Proposals will be heard for both low-bit-rate versions in the realm of 20 kbits/s, as well as medium- to high-bit-rate implementations that will equal and surpass current, next-generation 10-Mbit Bluetooth work by jumping right to 20 Mbits/s.
Riding a rising curve of interest, the 802 wireless working groups will attract most of the 700-plus attendees expected at the meeting-and the interest is well-founded. The market for wireless networking in the enterprise alone will rise from $771 million in 1999 to nearly $2.2 billion by 2004, Cahners In-Stat Group (Newton, Mass.) estimates.
Such growth prompts Radiata's chip set. Using 0.18-micron CMOS technology, it will allow for a wireless PC-card-based bill of materials of roughly $150 by year's end. Chris Fisher, vice president of sales and marketing at Radiata (San Jose, Calif.), said the chip set will have two effects.
Others in fray
"First, it will dispel the notion that 54-Mbit/s wireless networking is one to two years away," he said. "Second, our use of all-CMOS technology over more exotic alternatives such as BiCMOS, SiGe or GaAs will ensure a cost-entry point on a par with today's 802.11-based devices."
Radiata is not alone in its drive to 5 GHz. Atheros Communications Inc. (www.atheros.com) made related announcements but did not disclose details.
Philips Semiconductors (www.us.semiconductors.philips.com) is also working on a BiCMOS front-end solution for year-end production.
A number of factors-mainly higher data rates and cleaner spectrum-is spurring the drive to 5 GHz, which is becoming increasingly attractive as applications grow more demanding and the 2.4-GHz band gets crowded.
These points are high on the agenda for the 802 plenary meeting this week. The group will hear proposals to increase the data rate of 802.11b-from 11 Mbits/s to 22 Mbits/s and higher-from companies like Alantro Communications Inc. (www.alantro.com). Alantro was recently bought by Texas Instruments Inc., which could help Alantro's push for standards based around its technology.
With TI's backing, Alantro may stand a better chance against proposals from 3Com Corp. (www.3com.com), which will push 40-Mbit technology, and Sharp Electronics Corp. (www.sharp.com), which will also enter the fray.
Regardless of the proposal, the obstacles to acceptance lie not in technical issues but in regulatory ones. Al Petrick, vice chair of the 802.11 Working Group, said the technical elements are fairly straightforward. Determined by basic physics, they boil down to a trade-off between distance and data rate.
"Right now, we're looking to set some basic criteria on signal-to-noise over a given range, multipath-handling capability, throughput, backward compatibility, fallback, complexity and the use of the existing MAC layer," said Petrick. "However, FCC requirements will be a major factor."
With the arrival of voice in the data-centric network, those attending the meeting now bear the burden of deciding on a QoS methodology for a number of reasons. The problem starts with the higher layers, those above the MAC, assuming incorrectly that a LAN rarely loses or delays packets. In fact, WLAN-PHY error rates are three orders of magnitude greater than those of wired LANs. As a result, unlike other 802 LANs, 802.11 retransmits unacknowledged frames. In addition, retries cause unpredictable delays that often block the transmission of subsequent, queued frames. Wireless links also incur high, per-packet MAC and PHY overhead-802.11b framing, gaps and acknowledge add up to 32.6 percent (vs. 3.2 percent for 802.3).
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