Qualcomm has taken the 802.11ac Wave 2 WiFi chips, which it launched precisely a year ago, and changed them radically, to offer a new ‘tri-radio’ architecture, supporting two 5 GHz connections alongside one 2.4 GHz band.
‘Tri-radio’ does not, at this stage anyway, include 60 GHz and the WiGig technology which inhabits that band. Qualcomm is working on that, and acquired Wilocity to help, but this new chip remains focused on 11ac and the traditional WiFi bands, lengthening the life of the ‘big chip’ approach to WLAN.
This approach involves improving coverage and data rates across the WiFi home by adding new radios, although many current operator RFPs are pointing in a different direction – using multiple access points meshed around the home and sharing the load intelligently, rather than pumping up a single gateway.
None of the system-on-chip solutions for home gateways – not even the eight-way Multiuser-MIMO Quantenna chips – can deliver 1Gbps speeds to all areas of the house. Initially, to reach every cranny in a home, vendors and operators increasingly turned to dual-band 5 GHz/2.4 GHz solutions. But while dual-band has become common in 802.11n and 802.11ac, no firm has previously put three radios in one SoC like Qualcomm, partly because most are concentrating on the mesh alternative.
In talking about its product plans it mentioned a mesh architecture but did not describe it, and it made no mention of a multiple-AP strategy on its roadmap. The press announcement says the chips support WiFi mesh, but although there are many proprietary mesh technologies for WiFi the official standard remains largely unused and we have not come across Atheros using one at all.
So it appears to be sticking with the multi-radio approach, though reading between the lines, this may be a chip built for a specific bid for one of the larger operators, and may or may not become a mainstream Qualcomm Atheros offering.
The new chips offer two options around the IPQ40x9 – a two-stream or a four-stream MU-MIMO radio. Qualcomm offered little explanation of why it has two radios for the 5 GHz space, but it is probably planning to target one of them at heavy lifting tasks like backhaul, extenders, or stationary devices like 4K TVs which require high volumes in real time.
Sometime during 2014 Qualcomm came out with an ingredient essential for this type of arrangement to work, which it calls Band Steering. This decides which AP a particular device should be attached to, and in order to force the connection, it weakens the signal that it is currently receiving. The radio gives up on the weaker signal and jumps on the signal that will give best system performance.
So where devices only have a 2.4 GHz radio, they automatically attach to the single 2.4 GHz band. But where they have both 5 GHz and 2.4 GHz, the system can automatically steer the client to the 5 GHz radio which has the least amount of traffic. AirTies pioneered a similar approach to optimizing WiFi experience and efficiency in the home, and Arris is also developing it. The outcome is that a 4K TV can get a stable connection in one 5 GHz channel, and anything that detracts from this can be steered away to work on either the other 5 GHz channel or the 2.4 GHz legacy channel.
One sign that this may be an operator-specific product is the questionable need for two radio channels combined with MU-MIMO. MU-MIMO was invented so that an AP could cope with 10 or 15 devices, sharing them across four separate streams. By allocating two 5 GHz channels, especially if they are 160 MHz wide, a neighbor’s home gateway will have fewer clear channels to work with and this will almost certainly create more interference. Few homes have 30 devices to support, so it seems overkill, in most scenarios, to offer two radio channels which also offer MU-MIMO.
The system can allow all three radios to appear as the same SSID, so that there is seamless attachment between each radio, and it also uses what Qualcomm calls WiFi-SON (Self Organizing Networks), which inserts a layer of security and management software. This supports smart phone management, plug-and-play installation, content prioritization, extender or node discovery and intrusion attempt reports. It also provides the intelligence for the band steering and for mesh re-routing of slow packets. Qualcomm says that WiFi-SON now supports HomePlug AV2 powerline solutions, so quite clearly it is working on offering a powerline backhaul too, but that is not yet part of this platform.
The company rolled out the same customers as last year – Amped Wireless, AsusTek, Linksys and TP-Link – to endorse this chip, with no new public design wins.
Also at Computex, Qualcomm brought out another WiFi chip specifically to support IoT applications – the QCA401x is a low power WiFi chip with support for HomeKit, Google Weave and AllJoyn. And it announced new Snapdragon processors for wearables (see separate item).
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