We’re a little baffled by this week’s announcements from Qualcomm Atheros about its new MU-MIMO WiFi chips, the QCA 9984 and 9994 as they seem to be very different from the chip that it has gone to market with back in Spring 2014.
We very much got the impression from speaking to Todd Antes, vice president of product management at Qualcomm Atheros, both now and in the past, that the previous generation devices the QCA9980 and 9982 were only capable of 3 multi-user streams – and yet this press announcement clearly talks about 4 streams. Antes used the three streams thrust entirely for the explanation of how these chips were 3 times faster than previous SU MIMO chips, and Broadcom’s Manny Patel, Director of WLAN Business Development, told us earlier this year there were a number of ways of doing MU-MIMO and that Broadcom’s chips would not suffer from what he described as an N minus 1 limit on streams.
What Patel meant by that was that a 4 x 4 MIMO device might only produce one stream less than 4, because that stream would be used mostly to null the other three streams in the directions they didn’t wish to go. This came out in a discussion when dealing with client devices which only had a single antenna. Almost every new mobile and tablet device now has 2 x 2 (antennas and radios) to receive with and we think that leads to being able to offer 4 multi-user concurrent streams.
But the proof of the pudding is in the contracts you can sign with it, and Qualcomm, after almost two years of boasting a MU-MIMO chip, second to market only behind the exceptional Quantenna, has supporting quotes from a number of vendors including Dell and Acer, Linksys, TP Link and Netgear, as well as Xiaomi, Numbia, Amped Wireless and Hitron. That doesn’t mean that all of these will go exclusively with Qualcomm Atheros on Wave 2 802.11ac – those which come with MU-MIMO, capability, but it suggests they will all use the chips in at least one product, and as such this must be assumed to be a thorn in the side of global WiFi market leader Broadcom. Qualcomm must have taken some market share.
It’s not as if Broadcom didn’t have enough troubles already, being mid-way through being acquired, and only a year or so after being bumped out of the cellular baseband market. It came to market with a 4 X 4 802.11 AC component at CES, at the same time that Marvell and MediaTek also joined the fight, this January and tried to tell us that the earlier launches, just Qualcomm Atheros and Quantenna, were premature and unproven.
With this number of customers prepared to trust even a minor product to the new chips, this looks very much mistaken, and some analysts have even ventured that Broadcom has lost the lead in the WiFi market virtually overnight.
That’s not an idea we can subscribe to. The new chips Qualcomm has come out with, which now talk about 4 MU-MIMO stream, not 3, are NOT the devices which are in these companies’ products, there has been no time. It will be the older chips that have been out for a while.
The spec on these chips is much more in keeping with those announced in January by Broadcom, Marvell and MediaTek, it’s just that Qualcomm has a first generation version taking any MU market share there is right now.
Qualcomm has added with these new chips the ability to target 160 MHz channels or two non-contiguous 80 MHz channels, meaning two 80 MHz channels, not even those adjacent to one another, but inside the 5 GHz WiFi bands. The QCA 9994 can also support 5 MHz bands, which is ideal for public safety applications.
That’s all very well, but when you address 160 Mhz, you have to use two antennas on each chunk of 80 MHz when you use these chips. So you can build devices which can switch between the two 4 x 4 in 80 MHz, or 2 x 2 in either 160 MHz or two separate 80 MHz networks.
The peak speed is cited as the same that Quantenna and others have been quoting for years in 4 X 4 devices – but it’s actually realistic in MU-MIMO, at 1.7 GHz. In order to actually achieve that throughput with SU MIMO, you needed a 4 X 4 receive chip, because SU-MIMO WiFi does everything sequentially. If it is talking to a 1 X 1 chip it is at best talking at 433 Mbps, because that’s all the device can receive. It then goes onto the next job. It only gets higher if all 4 radios are talking at once and being heard by 4 radios at the other end. In MU-MIMO it can talk at 433 Mbps to 4 devices at once.
Qualcomm says that its previous high speed was around 1Gbps, but doesn’t make it clear if this was its theoretical maximum or a speed that it has actually seen reached in tests. We hope it’s the latter.
Qualcomm says that the new QCA9984 is designed for home routers and the QCA9994 is for enterprise access points.
What is far more interesting than any of this is the idea of bandwidth agility. This means that the radio can move seamlessly between channel widths on a packet-by-packet basis and achieve greater spectrum efficiency and throughput. Now that’s interesting as we have not come across this before, but then again we have not seen any device reach 160 MHz before. If there is less interference and signals are in the same room, it may indeed opt to send in a single 160 GHz channel for higher speed, and if it is through a few walls, it may want to send to as many concurrent devices as it can in MU-MIMO mode.
But doing this on a packet by packet basis is tricky. It may mean jumping in an out of pre-established configurations, or it might mean looking at information on other channels and swapping to a channel it also knows has less interference on it. To do this is hard work and requires constantly updated information on the conditions of those channels, but it is key to how some video specialists use existing chips, and is already be done in software.
All the products that were mentioned in the release should be out this year, and it will be interesting to see if Broadcom can come to market with a similar number of wins. Either being over a year ahead has impressed the community, or real products that use this were only due at end of 2015, and Broadcom and the others are in plenty of time.
Mewanwhile Qualcomm has also unveiled what it calls the first hybrid wireless extender which uses HomePlug AV2 MIMO alongside its 802.11ac WiFi. This is simply a range extender that repeats the WiFi signal after going over a Homeplug AV2 powerline. It has two, one that works with a single stream over the Powerline, and one that uses MIMO and both outputting to 802.11ac devices. Range extenders have been enabled by the 1905.1 standard for interoperability between Homeplug or MoCA, and WiFi, and will soon be joined by products that are built around G.hn. Qualcomm has signed up Zinwell to build a product using this chip.