Marvell takes 802.11n to 450Mbit/s

Silicon-maker Marvell has announced a Wi-Fi chip that will work at a raw speed of 450Mbit/s, as the first salvo in this year's fast Wi-Fi wars.

Devices made using Marvell's TopDog 11n-450 chip will carry data at something less than 450Mbit/s due to overheads, but should comfortably exceed Fast Ethernet at close range, and give better range than existing Wi-Fi equipment. The chip is intended for routers, PCs and consumer devices, and uses 3x3 MIMO antennas (three sending and three receiving) as defined in the IEEE 802.11n standard, to produce three separate streams of data between nodes.

Though it won't ship till the second quarter of this year, the chip will be shown at the Consumer Electronics Show in Las Vegas - where competition around the IEEE 802.11n fast Wi-Fi standard is expected to be strong.

"The 802.11n spec requires at least two spatial streams - two unique paths through space that reuse frequencies," said Glenn Fleishman of Wi-Fi Net News, "but three or four are also possible. Fleishman expects to see products with four streams, with a raw 600Mbit/s rate by the year's end, and more announcements at CES.

Marvell's rival Atheros has had a 3x3 Wi-Fi chip for some years, but this only handles two spatial streams, with an extra antenna for redundancy. According to Unstrung both Atheros and Broadcom are casting doubt on the reliability of three-stream solutions and intend to focus on bringing the prices of two-stream solutions down.

Marvell's promise of 450Mbit/s could look good on the packaging of consumer devices, but the price may be a drawback. The enterprise is less sensitive to price, although it is a much smaller sector; here Marvell is already providing silicon for Cisco's 802.11n access point, and will be hoping to keep that contract - and the big shipments as users start to adopt 802.11n - with a powerful upgrade.

Although the chip complies with 802.11n, it does also include proprietary Marvell technologies, such as Special Time Block Coding (STBC), that it says will help to keep the higher speeds up at longer distances.