Blog | Clearing ?fuddy? waters

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By Michael Lok

Michael Lok photo

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 fear, uncertainty, and doubt (FUD) that Wave 2 access points (AP) won?t add immediate value to existing Wi-Fi infrastructures. They already have.

One of the BIG benefits 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 FUD surrounding Wave 2 APs, here are some more detailed radio truths to help you in your buying decision.

1. Increased Wi-Fi Capacity with MU-MIMO

If there?s only one reason why Wave 2 makes sense now, 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.

QCA-80211ac_MU-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?

2. Better Transmit and Receive Performance

There may not be many 4×4 clients on the market this year, but adding radio chains helps improve reliability even if you have 1×1, 2×2, or 3×3 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 better ability to 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).

3. 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.

4. More Spatial Streams Help 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 4×4:4 (4 transmit and 4 receive radio chains with support for 4 spatial streams), while most Wave 1 chips were 3×3:3.

While we all wait for four-stream Wi-Fi devices, more spatial streams provide 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 connect wirelessly at true gigabit wireless speeds.

5. 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 enable 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. 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.

6. 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.

As Wave 2 of 802.11ac continues to gain momentum, deploying Wave 2 APs means having more airtime for clients and serving multiple client devices simultaneously. This improves your Wi-Fi network?s performance, enhancing speed and offering seamless connectivity ? indeed, it?s time to bid slow Wi-Fi adieu.

The author is the managing director for Southeast Asia at Ruckus Wireless

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