Qualcomm fires shot at Broadcom in digital home, with 4x4 MIMO 11n chip

Qualcomm has taken some time obviously to cash in on its acquisition of Wi-Fi/MIMO pioneer Airgo in late 2006, but some of that start-up’s innovations


Published: 3 June, 2009

Qualcomm has taken some time obviously to cash in on its acquisition of Wi-Fi/MIMO pioneer Airgo in late 2006, but some of that start-up’s innovations are likely to have found their way into the CDMA giant’s new Wi-Fi digital home products – the first from a major vendor to feature 4x4 MIMO antenna arrays, and a powerful shot across the bows of antagonist Broadcom.

Qualcomm and Broadcom may have signed a truce after their patent wars, but the two fabless chip firms are increasingly clashing in their key markets, as Broadcom tries to gain a share of the cellphone sector, and Qualcomm looks to diversify its business into areas, such as the digital home, where its rival has been highly successful.

If Qualcomm were to have the kind of impact that it had in the HSDPA device market, where from a standing start it took more than 50% share by staying ahead of the performance curve, it could potentially decimate Broadcom’s future Wi-Fi revenue base. At the Computex show in Taiwan, it showed off two Wi-Fi products. One is targeted at dual-mode Wi-Fi/cellular handsets, a sector where both Qualcomm and Broadcom shine because of their skills in integration. But the second is far more radical – the N-Stream Wireless Lan WCN13, which delivers 600Mbps of raw data performance with four radios, dual-band support and a four-antenna MIMO array (the only other vendor to sample a 4x4 802.11n product has been start-up Quantenna, which has not gone commercial yet, but claims its product can be configured in a pair, to deliver up to 1Gbps).

This is the first time that Qualcomm has made a run at the digital home market – a business which has been in turmoil for the past decade, with every other chip business on the planet shooting at the problem of how to move high definition video streams around a home. There are wired systems such as MoCA, HPNA and HDMI, all good for different parts of the equation – and all about to be potentially superseded by newer cable technologies and faster and faster wireless systems.

Most UltraWideBand (UWB) approaches have either failed or been discredited by association, and 60GHz wireless options such as WiGig and WirelessHD appear to be on the remote horizon, which leaves us with Wi-Fi. The big problemswith Wi-Fi is that, in its traditional form, it drops about 15% of its packets. Also, unless there is a return path to request packet resends, and special software (such as Ruckus Wireless has) to chart and redirect traffic onto channels which have better performance, then it’s tough to support video reliably. Ruckus products are significantly more expensive than traditional Wi-Fi.

One approach, which Qualcomm is now endorsing, has been to push towards MIMO and in 2007 Apple was one of the first to deliver a product built around the pioneering work of wi-Fi chip specialist Atheros, which has many patents in this area. The Apple Airport Extreme used Atheros chips which preceded the 802.11n standard, and included patent pending Signal-Sustain technology. It operated in dual-concurrent 2.4GHz and 5GHz spectrum. These chips featured 2x2, 2x3 or 3x3 MIMO arrays and Atheros claimed, even then, that the top of the range products would hit 600Mbps and offer real world video throughput up to 180Mbps. Today Atheros has still to reach those heights in the real world, however, though it still maintains that it makes little sense to go beyond 3x3 arrays. This is because of cost and power considerations and because each transmit or receive antenna in a MIMO set-up requires a lot of circuitry to be placed on a chip, so the gain from sending more signals is often outweighed by the loss from extra circuitry, and a step level increase in complexity.

Qualcomm’s N-Stream chip claims to have solved these problems and created a throughput of around 600Mbps for distributing multiple simultaneous HDTV streams throughout the home. “Qualcomm’s advanced 4x4 MIMO technology sets a new performance milestone for home media streaming devices,” said Mike Concannon, senior VP of connectivity and wireless modules for Qualcomm CDMA Technologies.

Of course 600 Mbps can only compete with compressed formats for video – a typical compressed 1080p HD stream might require 8Mbps these day, though it is a pretty moveable feast and 18 Mbps is not unheard-of. So moving two or three of these around should be child’s play for an advanced MIMO 802.11n system. However 2-3 Gbps is needed to handle the same video uncompressed and many efforts in this market are aiming at decompressing video at the home gateway and distributing uncompressed (mostly wired) video traffic around the home.

The WiGig specification, which should emerge by late 2009, is a blueprint for building Wi-Fi-like chips which can transmit 1.5Gbps, but since it uses 60 GHz spectrum, it will not be able to get through a single wall and so is confined to a room. There are also two wired technologies of interest - one out of China called DiiVA, which supports 13.5Gbps of bandwidth dedicated to video plus a hybrid bidirectional channel; and another out of Israel from Valens Semiconductor, which has 20Gbps on its cable roadmap using Ethernet protocols over coax. But most of these technologies have trouble with whole home distances (though Valens claims it can deal with this) and the entire world seems to be looking to Wi-Fi to solve this problem – at least for now - and 600Mbps Wi-Fi might just do the trick.

Qualcomm says it has developed sophisticated algorithms which take advantage of the multiple transmitters and receivers to increase data throughput, extend range and overcome interference – but the company as yet has given out no technical details about how this is possible, except to say that the chip is built in a 65nm CMOS process and is 12x12 mm in size, combining an embedded applications processor, MAC, digital baseband, RF transceiver and system power management. NXP says it has been working with Qualcomm and this chip on set-tops, while Applied Micro has worked with it on access points, network attached storage and home gateways. Qualcomm will need many more friends than that to dominate this sector.

However, it does boast the kind of early stage adoption of cutting edge technologies and performance levels which has helped Qualcomm gain such success in HSPA. The chip is ready to sample during this quarter and is part of a new range that also takes in low power 802.11n in the WCN1312 chip for handsets and other mobile devices. This mobile Wi-Fi chip supports data rates up to 72Mbps, all aimed to improve the experience on a handset used for watching streaming video or surfing the internet.

To date, Qualcomm has mainly invested in Wi-Fi to integrate into systems-on-chip for multimode handsets – as a support for its key handset business – rather than as a platform in its own right. But as the Snapdragon platform shows, the chip giant is looking to spread its wings more widely, as the CDMA technology that it controls starts on its slow but sure downward path and as margins get squeezed even in W-CDMA. Qualcomm really showed its hand in advanced WLan technologies and IPR when it acquired Airgo, a heavily backed start-up whose advanced MIMO smart antenna technology had been the basis of many products that appeared mid-decade, pre-empting the draft 802.11n standard.

Nokia-funded Airgo looked set to provide the key MIMO technology for that IEEE standard, until it was wrongfooted in mid-2004 by Intel and Broadcom, which got behind a rival approach from Atheros that included the option to use wide 40MHz channels. But it still fit all the criteria for a Qualcomm acquisition, bringing strong technology to take it into new markets; powerful IPR potential; and the chance to accelerate the then-nascent Snapdragon platform, while disrupting the plans of a key competitor (Broadcom, and to a lesser extent Atheros and Marvell).