FROM EDN EUROPE: "Pre-n" WiFi chip set implements full MIMO proposal

Observers of the technologies that will underpin the wideband domestic environment of the near future largely agree that there will be a need for some form of broadband backbone for the home. Opinions vary on whether it will be wired or wireless, and on which standards will prevail. Israeli silicon supplier Metalink believes that the solution will be Ethernet-based, specifically the 802.11n variant of the WiFi standard. 802.11n is still some way from being a ratified standard; Metalink is one supplier to the emerging "pre-n" market of equipment (Picture). Companies participating in this sector bring product to market ahead of ratification of the standard, using their own estimates of what the final version will contain. At the same time, Metalink's chip set retains backward compatibility with existing WiFi standards such as -b and -g.

The company offers a chip set for the MIMO (multiple-input, multiple-output) technology that transmits multiple carriers with separate encoded data streams over the same RF channel to increase channel capacity. MIMO relies on multipath propagation between transmitter and receiver to add differentiation to the two (or more) signal streams. This enables the receiver to separate the original data, albeit with considerable baseband processing. Barry Volinskey, Metalink's Associate Vice President, strikes a note of realism about "on-the-box" WiFi data rates. The typical -g product might quote 60 Mbps, while actually achieving perhaps 20 Mbps over short distances. Metalink's implementation of early-n technology achieves, he claims, a true rate of 60 Mbps at 20m range—sufficient for two HDTV bit streams. Metalink's chip set comprises an RF chip, already sampling, and a baseband part, due out in September. The Mtw8150 RF part integrates two transmit/receive paths on a single chip and can be used with, or separately from, the forthcoming baseband part. It requires an external power amplifier, but no separate low noise amplifiers, filters or other functions. Metalink's designers employed silicon-germanium technology to achieve the required performance at 5 GHz, the band that Metalink has chosen to employ. It is, the company says, the only product so far announced that combines MIMO with the use of 40-MHz channel width (through "bonding" of 20 MHz channels).

The baseband part (8170) will be in 0.13-micron CMOS, supporting 2×2 or 2×3 MIMO schemes, and presenting a complete access point. It will support raw PHY bit rates of 243 Mbps with 40 MHz channel bonding, or 135 Mbps using 20 MHz channels.

Metalink, +972 9 960 5555, www.metalinkBB.com.