Today's legacy 802.11n (or older) enterprise networks are running out of capacity fast. The number of wireless devices is exploding in the enterprise with on average 3 devices per person. And these devices and the applications running on them are pushing past the limits of your network.
802.11ac offers relief, but like 802.11n when it was introduced, the features will come in multiple waves. Currently there are Wave 1 products available and most of the industry is expecting Wave 2 products to start showing up in 2015.
What is 802.11ac Wave 1?
Wave 1 refers to the current generation of 802.11ac products that is currently in production and being certified by the Wi-Fi Alliance and supports data rates up to 1.3 Gbps with 3 spatial streams.
The following features beyond the prior 802.11n standard are implemented by leading vendors such as Aruba Networks:
- 256-QAM
This is a new quadrature amplitude modulation mode that was added as an optional, but widely implemented, component of 802.11ac and increases performance by roughly 30% when utilized.
- 80 MHz Channels
The channel width has been doubled to allow for up to 80 MHz channels with the ability to fall back to narrower channels when there are interfering devices. With this becoming a mandatory component of the certification program, this will double the throughput that a client can achieve.
- Explicit Transmit Beamforming
While several 802.11n products implemented beamforming, it was not widely adopted due to the number of variables/options available in the 802.11n standard. 802.11ac has settled on a single standards-based explicit beamforming method to drive wider adoption. Products such as the AP-224/225 that implement Tx Beamforming and are certified for interoperability by the Wi-Fi Alliance will deliver maximized data rates at a given range.
What is 802.11ac Wave 2?
Wave 2 is a term used to describe the second generation of 802.11ac products. The current generation of products in production is based on 802.11ac Wave 1. The Wi-Fi Alliance standardization of Wave 1 products began in June 2013 with the Aruba Networks AP-225 being the first enterprise-class product to be certified and it is now a mature and proven product.
While there is no firm date on when chipset manufacturers will start releasing Wave 2 components, it is expected that this will occur by early 2015 (if there are no production delays) with enterprise-grade Access Points and client products containing these chipsets likely to begin shipping in mid-late 2015.
It is likely that the following features will be included in the Wave 2 certification requirements:
- 4 spatial streams (4SS)
This has the potential to increase performance by up to 33% beyond today's products that incorporate 3 spatial streams by adding an additional fourth antenna to both the AP and clients. However just like with Wave 1 where most clients only implemented one or two spatial streams in order to save on power and space, the same is likely with Wave 2. Most devices will not be able to take advantage of the 4 spatial stream rates.
- 160 MHz channels
This feature enables the AP and client to double the channel width from Wave 1 and therefore increase throughput when the channel is clear. Where this will benefit users is the home environment where there is a single AP. Most enterprises are not likely to deploy 160 MHz channels because there are only two channels available when DFS-frequencies are included. With only two channels available it is highly likely that there will always be someone transmitting over the air and hence the APs will have to fall back to 80 MHz or 40 MHz operation due to the congestion such that clients will not be able to take advantage of the 160 MHz rates. Therefore it is quite likely that enterprise APs will not implement or certify for 160 MHz operation. It will probably take governments opening up additional frequencies in the future in the 5GHz band before one can truly leverage these wider channels.
Figure 1: 802.11ac channels available (US)
- Downlink Multi User MIMO (MU-MIMO)
This is the most interesting feature expected in Wave 2 as it will enable APs to simultaneously transmit to multiple clients by leveraging multiple instances of beamforming. For example, an AP could transmit 1SS to a smartphone while transmitting 2SS to a laptop. The one catch with MU-MIMO is that it will require new client hardware since both the AP and client need to be designed with the MU-MIMO capability. Therefore it will take until 2016, after the Wave 2 chipsets appear, for clients to become pervasive and be able to leverage the benefits of MU-MIMO.
Figure 2: MU-MIMO transmission to 2SS laptop and 1SS smartphone
Why not just wait for Wave 2 products in late 2015?
The simple answer – Wave 1 solves a huge problem, today.
1) 3x Performance Boost
Wave 1 802.11ac is able to meet the performance and density demands of today's mobile environment and the foreseeable future. With achievable speeds reaching 750Mbps of TCP to a single 3 stream client and up to 250Mbps to a single stream client like a smartphone, it is able to deliver a 3X performance boost to your network without demanding a large price premium. Since Wi-Fi is a shared medium, the speed that each client communicates with has a direct relationship to the number of clients that your network can support.
As you look at rolling out a new network or adding capacity in certain areas of the network, you should be selecting the best performing products available today. Delaying your rollout will mean increased downtime for your employees as they spend more time waiting for file transfers.
2) Over 100 devices are 11ac and it's ramping fast
With over 100 Wi-Fi Alliance certified 802.11ac Wave 1 products shipping today, incorporating the Wi-Fi Alliance certified Wave 1 AP's into your network architecture enables you to deliver high performance for these #11ac clients while maintaining backwards compatibility with the existing 802.11n devices. In fact Samsung alone has shipped over 40 million 802.11ac clients with their Galaxy S4 smartphone and all new Mac computers now come equipped with 802.11ac with many PC manufacturers following closely.
3) It even speeds up 802.11n clients
Leveraging the enhanced RF designs and faster CPUs in today's 802.11ac products, even your legacy 802.11n devices will see better range and performance from an 802.11ac AP.
4) You don't have to upgrade your wired network
802.11ac Wave 1 is really the last generation of Wi-Fi that allows you to leverage your existing switching infrastructure without requiring major upgrades. With future Wave 2 speeds likely to reach 2 Gbps over the air, the uplink performance requirements will exceed the existing GigE ports and will require the use of either multiple GigE ports to the AP or even 10GigE.
5) Some 11ac APs play better with cellular
Some products, such as the AP-225 are also built with innovative technology that mitigates interference from Cellular networks (LTE and TD-LTE channels 7, 38, 40, 41 sidebands overlap with 2.4GHz) to get the best performance out of your 802.11n devices.
What should you do?
As we have seen in the past time and time again, innovation will continue with Wi-Fi since the demands for throughput and density will continue to push the networks.
As you look at your network, you can leverage tools such as Aruba Networks' AirWave management software in order to identify which AP's in your network are the most heavily loaded and migrate these to the latest 802.11 technologies. This allows you to maximize the benefit from your investment and rightsize your network.
