Author
Ruckus Networks
Categories
Technology/Trends
Wave goodbye to slow Wi-Fi.
Wave 2 of 802.11ac is here and now, adding new capabilities that improve overall Wi-Fi system performance and capacity.
So don’t be put off by naysayers spewing FUD that Wave 2 APs won’t add immediate value to existing Wi-Fi infrastructures. They already have.
Wave 2 802.11ac-capable access points make more efficient use of the RF spectrum by getting clients on and off the medium faster, leaving more airtime for clients, even those that don't support Wave 2 capabilities. Because Wi-Fi is a shared medium, reducing the time to serve even some clients will benefit all clients.
And as multi-user MIMO clients hit Wi-Fi networks this year, Wave 2 is capable of serving those clients simultaneously—allowing others the opportunity to access the RF spectrum sooner. It’s carpooling. If you can get people to carpool, even those who don’t carpool benefit because there are fewer cars on the road.
Having more spatial streams available to use also provides incremental value in the form of spatial diversity, regardless if the clients have one, two, or three spatial streams. More antennas improve MIMO by increasing reliability and signal quality, pushing data throughput closer to data rates.
The other obvious and BIG benefit that wave 2 provides is simple: investment protection. Customers are tired of having to architect and re-architect their Wi-Fi networks every couple years to accommodate the barrage of new devices with new features and functions that can’t benefit from their existing networks. Wave 2 effectively mitigates this risk, extending Wi-Fi refresh cycles.
But, maybe you’re still hearing the same tired message when companies want you to buy Wave 1 instead of Wave 2 saying: “Wave 1 is good enough; no need for Wave 2.” To help demystify a lot of the fear, uncertainty and doubt (FUD) that vendors are belching, here are some more detailed radio truths to help you in your buying decision.
Increased Wi-Fi Capacity with MU-MIMO
Looking closer, if there’s only one reason why Wave 2 makes sense now (and there’s much more) it’s this: MU-MIMO allows an AP to send downlink frames to multiple stations at the same time. This increases capacity compared with single user MIMO.
Historically, Wi-Fi was only capable of serving clients one-at-a-time. Slow devices consume extra airtime, and all devices served by that AP suffer as a result. This is especially true in mobile-rich deployments. And what networks aren’t packed with smart mobile devices today?
Better Transmit and Receive Performance
There may not be many 4x4 clients on the market this year, but adding radio chains helps improve reliability even if you have 1x1, 2x2, or 3x3 clients.
Adding more transmit radio chains improves downlink performance, especially for MU-MIMO. That extra transmitter provides more signal steering control and higher data rates with less interference.
Adding more receive radio chains also improves uplink performance. Using maximal ratio combining (MRC), the AP has the ability better hear signals on multiple antennas and in different polarizations (if the AP supports dual polarization), combining those signals to ensure better reception. This is especially useful for single- or dual-stream clients with small antennas and weak transmit power (e.g. smart phones).
Legacy Clients Benefit
If you’re having a hard time seeing the benefit of MU-MIMO because some portion of your client devices won’t support MU, realize that every MU-capable client in your network ultimately benefits legacy clients (single-user, or non-MU) as well.
With 2-3x greater efficiency from MU, every extra bit of productivity gained is added to the airtime pool for other clients (especially legacy clients that need the boost) to utilize.
More Spatial Streams Helps Everyone
The number of spatial streams and the transmission bandwidth together indicate potential throughput performance and number of devices supported. Initial Wave 2 radio chips are 4x4:4 (4 transmit and 4 receive radio chains with support for 4 spatial streams), while most Wave 1 chips were 3x3:3.
While we all wait for four- stream Wi-Fi devices, more spatial streams provides unique benefits, particularly for wireless meshing. Wi-Fi meshing has always suffered from multi-hop throughput loss. With additional, higher bandwidth streams, APs should now be able to connected wirelessly at true gigabit wireless speeds.
Investment Protection
MU-MIMO client support is happening this year. In fact, MU-capable clients are already on the market. Many of the mobile device chipsets in devices used today are actually “multi-user ready” with a firmware upgrade. So, don’t be surprised if software upgrades this year enables widespread MU support with no need to buy new devices. And yes, MU-MIMO does require client support, so not all 11ac clients can use it. But MU-MIMO support in clients is a near-term reality.
MU-MIMO is a long-term investment – it’s simple myopia to defer Wave 2 because “no MU clients exist today.” And even a short-term AP investment spans 3 years, so why would we focus on client support in the market RIGHT NOW instead of forecasting client feature support 6 months from now? With that perspective, MU-ready APs make even a 4 or 5-year AP investment plan very reasonable.
MU-MIMO also adds margin for imperfect designs – a small contingency of Wi-Fi consultants and administrators are true experts at maximizing spectral efficiency (proper channel reuse, AP location, Tx power, antenna choice, etc). Given the budget, time, building layout, and business requirement, they can fine-tune until Wi-Fi Zen is reached. For the rest of us, all performance features that offer margin to offset “best effort” designs are a huge help for maximizing investment—and making network admins look like experts, even if they aren’t.
Newer Chipsets Bring Efficiency and Performance Gains
Every new generation of Wi-Fi chips comes with efficiency and performance improvements. Every new AP hardware revision is an opportunity to improve radio components, fine-tune the layout, enhance antenna subsystems, and generally improve performance. If you remember back when the first 11ac APs were coming out, the industry as a whole saw a marked performance increase even for 11n clients (specs didn’t change, but performance did). For all clients, expect new APs to enhance speed.
Impressive Power Efficiency
Unfortunately, when you add more radio chains, APs require more power.
With Wave 2, The Ruckus R710 is designed to provide full GHz 802.11ac functionality on 802.3at power, while offering a pretty sweet deal on 802.3af “efficiency mode.” We simply reduce 2.4 GHz radio output power to 25 dBm and disable the USB and second Ethernet port. That’s it.
And you won’t have to think about it. The new ZoneFlex R710 is smart enough to detect how it’s being powered. Whether by DC, 802.3at PoE, or 802.3af PoE, it automatically makes the necessary adjustments to maximize 802.11ac performance.
Other Considerations
Wave 2 will be slightly more expensive than current Wave 1 APs, so you can still buy Wave 1 if you are budget conscious. IT JUST may not take you as far.
And if you’re waiting around for Wave 2 because of the data rates promised by 160 MHz channels, don’t be fooled. Wide channels are the enemy of spectral efficiency in the enterprise. Most client devices won’t support 160 MHz, so there’s really no reason to want it…other than for suspect marketing claims like “fastest AP ever.”
And if you’re worrying about 802.11ac stabbing you in the backhaul, don’t.
For an AP to require more than Gbps the situation would need to be highly unusual, if not completely unlikely. This would mean a 4 spatial stream 802.11ac WiFi client running 80 MHz channels and an 802.11n 3 spatial stream client (on a 40Mhz wide channel) all using the AP at the same time, Keep in mind there currently doesn't exist 4 spatial stream WiFi clients (but they ARE coming), and given the limited channels available, you'd never want to set the 2.4GHz radio to 40 MHz wide channels So given the real world device and traffic mix, you’ll rarely need more than 1 Gbps uplinks for Wave 2 APs. Even if you do, link aggregation is there to help.
The Net-Net of it All
If we knew that we’d be really late to market, we’d probably be saying things like “wait on Wave 2 until clients are ready.” What we’d really mean is “please don’t buy Wave 2 from our competitors…we will be late to market.” But we didn’t say that. Instead we just thought we’d cause another Ruckus. Mission accomplished with much more to come.
