802.11ac Wave 2, MGig and Cisco’s 2800 & 3800 Series Access Points

Several weeks ago I attended a presentation on Cisco’s new 2800 and 3800 Series access points.  I’m quite impressed with some of the new capabilities these APs bring to the market.  The presenters, Mark Denny and Brian Levin, were passionate regarding the implications this has for wireless networks.  I felt I needed to take a step back to really understand why some of these enhancements and new features are so important to wireless infrastructure.  I’ll run through a few of the capabilities that I personally feel are most significant.  I’ll attempt to keep it concise.

802.11ac Wave 2

The demand for better wireless experience is always on the rise.  More people connecting with more devices equates to serious sustainability and performance concerns.  Common sense stuff right here.  To combat this, with 802.11ac Wave 2 comes more throughput and higher density, specifically in the 5-GHz band. This is achieved through a series of enhancements.  

MU-MIMO & Fourth Spatial Stream

Multiuser multiple-input multiple-output enables the capability for wireless access points to communicate downstream with multiple Wave 2 clients concurrently.  This is a leap from 802.11ac Wave 1 where access points only supported SU-MIMO, limited to single-user MIMO communication at a time.  MU-MIMO is the same multiple-input multiple-output capability, but for multiple users simultaneously.  It does have its restrictions, limited to four clients at a time (or a maximum of four spatial streams per client). Bonus enhancement: we now have a fourth spatial stream!  Previous iterations supported up to 3 receive antennas, but 802.11ac Wave 2 adds another to the mix, resulting not only in the additional client support for MU-MIMO, but also greater distances particular data rates can be sustained depending on the environment.


MU-MIMO Deep Dive at Wireless Field Day, 7 August 2014, with Cisco’s Matt Silverman: http://techfieldday.com/video/cisco-mu-mimo-deep-dive/

160-MHz channel width PLUS more 5-GHz channels

In the previous version of 802.11ac Wave 1 we had support for 20, 40 and 80 MHz channel widths, enabling speeds up to 1.3 Gbps.  With Wave 2, a wider 160 MHz channel is added, enabling speeds up to 2.3 Gbps.  Supported clients can experience high-speed transfers of large files, nearly doubling the performance capabilities of the previous iteration. To add to this, there are now about 37 separate channels in the 5-GHz frequency work wide.  This provides greater bandwidth and flexibility in instances where RF interference is detected.


With 802.11ac Wave 2 you can expect speeds up to 2.34 Gbps per radio, or theoretically 6.2Gbps (I’ve seen mixed numbers here), in 5-GHz band, meaning better support for latency-sensitive traffic like voice and video, along with efficiency improvements in high density areas.  You might be curious why 802.11ac only encompasses 5-GHz. The answer is simple. The 2.4-GHz spectrum is overcrowded, its limited in number of channels, limited in number of channels that do not overlap, and these few channels are narrow, all resulting in an insufficient spectrum.  Although access points will continue to support 2.4-GHz radios, the intention is for clients to move towards 5-GHz, and many already have.  

Cisco 2800 and 3800 Series Access Points

The newly released access point models from Cisco complete their traditional tiered model portfolio.  All models in this portfolio support 802.11ac Wave 2, and although they’re on the leading edge, simply supporting this standard is not going to set it apart from the rest of the competition.  Below are few features Cisco is supporting in this iteration of their access points that truly makes them competitive in this space.
Screenshot at Apr 21 11-31-05

Dynamic Frequency Selection

Dynamic Bandwidth Selection within the 2800/3800 access points provide the flexibility to move between channels depending on RF conditions. Having the ability to automatically switch between 20, 40, 80 and 160MHz channels is immensely helpful when combating performance problems.

Flexible Radio Assignment

Flexible Radio Assignment is a wicked capability built into the 2800/3800 Series APs. These APs are built with two radios and the capability for these radios to self-optimize depending on environment variables.  One radio could be broadcasting in 5-GHz while the other broadcasts in 2.4-GHz.  The access points are intelligent enough to understand increases in usage and will automatically switch the 2.4GHz signal to a 5-GHz, thereby improving reliability for wireless clients by running in a dual 5GHz mode.  Counter to this, the APs detect dips in wireless activity or client counts and automatically switches back to the diverse radio configuration.  A third alternative scenario can be seen when one of the radios switches to a security mode for detecting threats, interference or actually combating rogue devices. 

High-Density Experience (HDX) Special Sauce

A Wireless Service Assurance Mode can be activated on one of the radios for the sole purpose of proactive performance monitoring, which reduces cross-AP noise, optimizes AP roaming, improves downlink performance (including device battery life) via Cisco ClientLink 4.0, reduces interference and equalizes MIMO by reducing the impact of signal fade.  It’s all about seamless wireless experience in high density environments. 


Cisco’s CleanAir is not something new, but it is something worth reiterating.  CleanAir detects, classifies and mitigates wireless interference, continuously self-healing depending on the RF conditions. Via a custom ASIC, these APS are capable of simultaneous radio frequency monitoring and data transmissions, essentially being your remote analyzers and auditors without having to make any site visits yourself. 

Smart antenna connector

The Smart antenna connector is an intelligent second physical antenna connector on the 2800 and 3800 Series access points, allowing for two sets of antennas to be connected and active on a single access point. This connector provides advanced network design flexibility for high-density and large open-area environments such as auditoriums, convention centers, libraries, cafeteria, and arenas/stadiums (including the stadium panel antennas).

Cisco 2800 vs 3800

Everything mentioned above is the same on both the 2800 and 3800 Series access points.  The big differences between these two models are two enhancements specifically on the 3800 Series:

Multigigabit Ethernet

MultiGigabit Ethernet, also known as MGig or NBaseT, provides multiple gigabit uplink speeds of 2.5 Gbps and 5 Gbps in addition to 100-Mbps and 1-Gbps speeds. All speeds are supported on Category 5e cabling for an industry first, as well as 10GBASE-T cabling.  This is huge achievement which can result in significant cost savings for large campus network.  No longer are you constrained to 1Gbps, nor do you have to worry about running new cabling in order to support the new speeds.  Cisco Catalyst Multigigabit technology solves these challenges on their newer Catalyst 3850, 4500E and 3560-CX switches, with the 3800 Series access point taking full advantage of the single-wire MGig connection.  This is an incredibly important consideration for 802.11ac Wave 2 implementations, and should be reviewed before any deployment.  Peter Jones, Principle Engineer with Cisco and NBASE-T Alliance chair, gave an impressive presentation at TFDX earlier this year, detailing the technical achievements engineered to overcome this obstacle of capacity. 

Cisco mGig, NBase-T, and 802.3bz Discussion from Stephen Foskett on Vimeo.

 Expansion Module Slot

The 3800 Series AP sports a module port for future expandability.  Physical modules can be fitted for value-adds like advanced security or hyperlocation technologies.

More Information

David Varnum


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