Wireless vendors try defining MIMO

Two developments last week illustrate the growing frenzy of interest in adopting a radio technology that promises to boost wireless LAN throughput from about 20M bit/sec today to at least 100M bit/sec.

First, a second industry group has filed a proposal, based on Wi-Fi technology called Multiple Input Multiple Output (MIMO), with the IEEE task group charged with creating a 100M bit/sec WLAN standard.

Not waiting for that standard, wireless vendor Belkin unveiled what are likely to be the first available MIMO-based WLAN products, with throughput of 40M to nearly 100M bit/sec.

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Two developments last week illustrate the growing frenzy of interest in adopting a radio technology that promises to boost wireless LAN throughput from about 20M bit/sec today to at least 100M bit/sec.

First, a second industry group has filed a proposal, based on Wi-Fi technology called Multiple Input Multiple Output (MIMO), with the IEEE task group charged with creating a 100M bit/sec WLAN standard.

Not waiting for that standard, wireless vendor Belkin unveiled what are likely to be the first available MIMO-based WLAN products, with throughput of 40M to nearly 100M bit/sec.

Last Friday was the deadline for proposals to the IEEE 802.11n group charged with defining the physical layer standard that will make the high-throughput WLAN possible. Sixty-two "intent to present" notices were filed, although some of those were for multiple proposals from the same vendors.

Some observers expect a first draft by mid-2005, with a final standard in late 2006 or early 2007. Products likely would emerge soon thereafter.

MIMO has emerged as the most likely way to dramatically boost WLAN throughput. It uses two or more antennas to transmit and receive data that is sent over multiple pathways on a single channel, multiplying the channel's data capacity.

Last week, World-Wide Spectrum Efficiency (WWISE) outlined a MIMO plan it submitted to the IEEE. The vendor group proposes, as the mandatory part of an 802.11n standard, using the existing 20-MHz channel structure that is almost universally adopted, two MIMO antennas on either end of the link and media access control layer changes to boost the throughput on a single channel to 135M bit/sec.

WWISE members are silicon vendors, including Airgo, Bermai, Broadcom, Conexant Systems, STMicroelectronics and Texas Instruments. Airgo is the only vendor to ship a MIMO chipset.

Last month, another vendor group, TgnSync, with Agere, Atheros, Intel, Sony and several others, unveiled their own 802.11n proposal.

Belkin decided not to wait for the 802.11n standard to be finalized. Last week, the vendor announced it will ship in October the Wireless Pre-N Router and the Wireless Pre-N Notebook Network Card, both based on Airgo's MIMO chipset and aimed at consumer and small-business markets.

Belkin says its tests show the new products deliver much higher throughput at longer distances compared with 802.11g access points. At 30 feet, the 802.11g access points delivered 15M to just less than 20M bit/sec. The Belkin MIMO router showed nearly 40M bit/sec, the company says. At about 130 feet, the 802.11g products dropped to 1M to 6M bit/sec, most at less than 5M bit/sec. The MIMO router dropped also, but to about 27M bit/sec, Belkin says.

Prices will be more expensive than Belkin's current 802.11g products, a Belkin spokeswoman says. The price for the MIMO router will be $179, and the notebook adapter will be priced at $129. By contrast, the Belkin 802.11g Wireless DSL/Cable Gateway Router costs $90.

Read more about wireless & mobile in Network World's Wireless & Mobile section.