High-Density Wi-Fi Design Part 3 - WLAN Configuration Best Practices

In this video, I explain the best practices for configuring a Wi-Fi network for high-density environments. These include:

• Proper encryption required to use 802.11n high throughput data rates
• Proper use of Quality of Service (QoS) through Wi-Fi Multimedia (WMM)
• Disabling lower data rates to maintain high performance
• Prioritizing key business applications over recreational applications
• Client rate-limiting to prevent "greedy" clients from hogging bandwidth
• The important role that bi-directional band steering plays in optimizing spectral use
• Load balancing clients based on airtime utilization on different channels to serve users where the most capacity exists
• Using airtime fairness to adequately handle a mixed-client environment
• Proper consideration of wired network resources, including switch port bandwidth, power over Ethernet, and Internet/WAN bandwidth
• Appropriately sizing IP subnets to account for device density and user mobility

These principles are covered in more depth in the Aerohive High-Density Wi-Fi Design and Configuration Guide.

Read the Entire High-Density Wi-Fi Design Series:
Design Your WLAN for High Capacity
Video Blog: High-Density Wi-Fi Design Part 1 - Forecasting AP Capacity
Video Blog: High-Density Wi-Fi Design Part 2 - RF Planning
Video Blog: High-Density Wi-Fi Design Part 3 - WLAN Configuration Best Practices

Cheers,
Andrew

Ekahau Site Survey™ 6.0 Incorporates 802.11ac Channel and Capacity Planning

Ekahau has announced that Ekahau Site Survey™ 6.0 now includes planning capabilities for 802.11ac wireless networks, including support for 802.11ac enhancements such as wider channels, primary and secondary channels (at various channel widths), more spatial streams, MU-MIMO, beamforming, and higher modulation rates. They have also released a companion white paper on planning for 802.11ac adoption.

White Paper: Planning for 802.11ac Adoption with Ekahau Site Survey™ 6.0

In the paper, Ekahau makes some of the very same points that I have made in prior posts about the need for careful channel planning with 802.11ac due to the likelihood co-channel interference at larger 80 MHz and 160 MHz channel widths by ensuring non-overlapping 40 MHz and 20 MHz primary channels.

Wide 80MHz and 160MHz channels improve throughput but only when full channel bandwidth is free from interfering transmissions. In dense network deployments, careful channel planning is critical to ensure interference-free operation. Channels cannot be selected arbitrarily but primary channels must always be selected so that access points within radio range can fall back to use lower non-overlapping channel for simultaneous transmissions. For example, APs on an 80MHz channel can fall back to use 40MHz or 20MHz channel bandwidths as described in Figure 1.

Here is Figure 1 from the guide:

ESS™ 6.0 also offers channel planning capabilities to help WLAN administrators ensure they provide non-overlapping channels to allow simultaneous transmissions.

For 802.11ac, the user can configure the utilized channel bandwidth as well as the allowed channels. The planning algorithm selects frequency channels using the selected bandwidth, including selection of the center channel as well as the primary channel. Channels are selected in such a way, that interference and channel overlap in the network is minimized. The primary channel selection algorithm is optimized for a mixed 802.11ac/802.11n client base and supports parallel non-overlapping 80MHz, 40MHz, and/or 20MHz bandwidth transmissions when full bandwidth is not available.

Here is a screenshot of an automatic channel plan for 802.11ac 80 MHz channels derived by the tool:

Ekahau Site Survey™ 6.0 Provides Automated 802.11ac Channel Planning

One question that I still have, and hope to uncover once I get my hands on the tool, is if ESS™ 6.0 can automatically plan for non-overlapping 40 MHz channels while simultaneously assigning neighboring APs channels such that the likelihood of simultaneous 80 MHz transmissions are maximized? Here is my figure, depicting non-overlapping 40 MHz and 20 MHz primary channels while still allowing 80 MHz channel use on a best-effort basis:

802.11ac Non-Overlapping 40 MHz and 20 MHz Channels

I also really like how Ekahau Site Survey™ incorporates capacity planning into their site survey tool, rather than relying on RF coverage alone. This is a point that I focused on when writing the Aerohive High-Density Wi-Fi Design and Configuration Guide. Today's Wi-Fi networks are growing in size and client density, which requires adequate focus on capacity planning by understanding client and application requirements coupled with traditional RF coverage and channel planning.

The goal of network analysis is to understand network capacity. The ESS capacity estimation algorithm allows user to accurately estimate the capacity of the planned network with a different set of client devices and traffic patterns. ESS models the key parameters of 802.11ac including the MIMO configurations, channel bandwidths, new QAM256 modulation, and frame aggregation just to name few. To support analysis of your own device, ESS includes predefined templates of AP and client devices and allows estimation of network capacity with a user-configurable set of client devices and their applications. This allows estimation of how network capacity differs, for example, between first and second generation 802.11ac devices.

Ekahau will be hosting live webinars on April 15th and April 19th to cover 802.11ac and ESS 6.0™ features. I'm planning on attending to hear about how this tool can help WLAN administrators adequately prepare for 802.11ac and high-density networks.

I have been a user of Ekahau Site Survey™ 5.5, but admittedly I have only used it on rare occasions since I have not invested the time to learn it properly. I'll have to upgrade to version 6.0 and invest more time and effort (perhaps training?), since it appears to take the right approach to WLAN planning that other tools historically have not.

Cheers,
Andrew

I have no formal affiliation with Ekahau and was not compensated in any fashion for writing this article.


Other posts you might be interested in:

802.11ac Gigabit Wi-Fi Series:

• The Impact of 802.11ac Gigabit Wi-Fi on Enterprise Networks
• 802.11ac Channel Planning
• Safely Using 80 MHz Channels with 802.11ac
• First Look - 802.11ac Gigabit Wi-Fi Speed

High-Density Wi-Fi Design Series:

• Design Your WLAN for High Capacity
• Video Blog: High-Density Wi-Fi Design Part 1 - Forecasting AP Capacity
• Video Blog: High-Density Wi-Fi Design Part 2 - RF Design
• Video Blog: High-Density Wi-Fi Design Part 3 - WLAN Configuration Best Practices

Video Blog: High-Density Wi-Fi Design Part 2 – RF Planning

In this video, I explain the key RF principles that you should consider when designing a high-density Wi-Fi network. These include:

• Leveraging the 5 GHz bands to reduce co-channel interference and increase network capacity
• Appropriate use of 20 MHz versus 40 MHz channel width
• Using non-adjacent channels to minimize adjacent channel interference
• Always performing a pre-deployment site survey
• Appropriate cell sizing to maintain high data rates for clients while minimizing co-channel interference
• Ensuring a high quality bi-directional link with clients
• Leveraging facility obstructions for channel re-use
• Co-locating APs to increase capacity
• Alternative AP mounting methods and appropriate use of antennas to achieve desired coverage while minimizing co-channel interference

These principles are covered in more depth in the Aerohive High-Density Wi-Fi Design and Configuration Guide.

Read the Entire High-Density Wi-Fi Design Series:

Design Your WLAN for High Capacity

Video Blog: High-Density Wi-Fi Design Part 1 - Forecasting AP Capacity

Video Blog: High-Density Wi-Fi Design Part 2 - RF Planning

Video Blog: High-Density Wi-Fi Design Part 3 - WLAN Configuration Best Practices

Cheers,

Andrew


Full Disclosure - This video was created in cooperation with Aerohive Networks, my current employer. 

Video Blog: High-Density Wi-Fi Design Part 1 - Forecasting AP Capacity

In my previous post, Design your WLAN for High Capacity, I outlined the increasing demands being placed on modern enterprise WLANs caused by the growth in the number of Wi-Fi connected devices, the proliferation of mobile devices and BYOD, and the increasing reliance on the WLAN as the primary network for users in the enterprise. As described in the Aerohive High-Density Wi-Fi Design and Configuration Guide, the key to supporting this increased demand is to design the WLAN for capacity rather than simply coverage.

The first step in designing a WLAN to meet capacity demands is to perform adequate requirements gathering. This starts with a proper understanding of client device capabilities. Because RF is a shared environment, the capacity is determined by the capabilities of the AP infrastructure and the client devices, application bandwidth requirements, and the resulting airtime utilization that results from their unique combination.

In this first of three videos on high-density Wi-Fi design, I describe how these variables interact and can be used to derive a preliminary forecast of the required AP capacity to support the intended network load. I also walk through a few examples to highlight how to apply this method to both homogenous and heterogeneous client environments.

The resulting AP capacity forecast is a starting point to aid the RF design and site survey process. The value in deriving the AP capacity forecast is to ensure that capacity needs are properly accounted for in the site survey process. For example, even though one AP may provide adequate coverage in a university lecture hall, several more APs may be required for capacity. Historically, RF site surveys have only focused on providing adequate RF coverage for the physical area, which may provide sufficient signal in all desired locations but lack AP and channel capacity to successfully support the client and application load.




Once you’ve watched the examples in the video, walk through a few of your own scenarios using the requirements gathering worksheets in the appendix of the Aerohive High-Density Wi-Fi Design and Configuration Guide.

Stay tuned for the remaining two videos in this series, where I’ll cover key RF design and network configuration principles for high-density networks.

Read the Entire High-Density Wi-Fi Design Series:

Design Your WLAN for High Capacity

Video Blog: High-Density Wi-Fi Design Part 1 - Forecasting AP Capacity

Video Blog: High-Density Wi-Fi Design Part 2 - RF Planning

Video Blog: High-Density Wi-Fi Design Part 3 - WLAN Configuration Best Practices

Cheers,
Andrew



Full Disclosure - This video was created in cooperation with Aerohive Networks, my current employer. 

Wi-Fi May Get A Capacity Boost, Thanks to the FCC

Have you heard the news? Wi-Fi stands to be the glorious recipient of much more capacity. However, this is not set in stone; far from it. It depends on spectrum policy decisions the FCC is weighing right now, with the help of Congress and the NTIA (a federal agency that advises the President on telecommunications and information policy issues) .

If Wi-Fi is the lucky recipient of more unlicensed spectrum, what would it look like?

Proposed New 5 GHz Wi-Fi Channels

What does this mean for Wi-Fi networks?

1. More channels, and MUCH more capacity! When we exclude channels 120, 124, and 128 which can't be used due to TDWR restrictions, we get:
• 20 MHz - 12 additional channels, 54% more than we have today (22 channels) = 34 total channels!
• 40 MHz - 6 additional channels, 60% more than we have today (10 channels) = 16 total channels!
• 80 MHz - 3 additional channels, 60% more than we have today (5 channels) = 8 total channels!
• 160 MHz - 2 additional channels, 200% more than we have today (1 channel) = 3 total channels!
2. Realistic use of 80 MHz and 160 MHz channel width in multi-AP enterprise environments. As I previously stated, the sparse amount of channels available at 80 MHz and 160 MHz channel widths make them impractical for use in enterprise environments due to inadequate channel spacing and co-channel interference. With this additional spectral capacity, sufficient channels will be available to allow the use of 80 MHz channels in most environments, and 160 MHz channel use in many office environments. The only likely holdout where these larger channel widths would not be appropriate are in very high density deployments. (Further reading: The Impact of 802.11ac Gigabit Wi-Fi on Enterprise WLANs).

Here's a breakdown of how this U.S. spectrum policy initiative got started and what remains to be done (Further reading: The Need for a Balanced U.S. Spectrum Policy):

• Feb 2012 - Congress passed the Middle Class Tax Relief Act of 2012, which includes stipulations to investigate the use of 195 MHz of additional 5 GHz spectrum for unlicensed use, among other frequency bands.
  
• Jul 2012 - The President's Council of Advisors on Science and Technology (PCAST) released a report supporting immediate methods to begin realizing the full potential of federal held spectrum to spur economic growth, largely through spectrum sharing techniques.
  
• Jan 2013 - FCC Chairman Genachowski announced the effort to open more spectrum for unlicensed use at CES. (Further reading: Spectrum: The Gift that Gives You Faster 802.11ac).
  
• Jan 2013 - NTIA released their initial study on spectrum sharing in these 5 GHz bands with existing primary users, mostly federal radar systems, and the risk of interference. (Further reading: NTIA weighs in on FCC's 195 MHz spectrum announcement).
  
• Feb 2013 - The FCC Notice of Proposed Rulemaking (NPRM) is due on 20-Feb and will outline the proposed spectrum policy. It will detail what bands are allowed for unlicensed use and what spectrum sharing and interference mitigation techniques are required to protect existing primary users. This NPRM will be crucial to understanding how much capacity Wi-Fi will gain, whether or not existing equipment will be compatible with a firmware upgrade, if new hardware is required, and the technical requirements that will dictate the feasible timeline for implementation and use.

Update - The FCC released the 5 GHz NPRM as expected on Feb 20th. Matthew Gast over at Aerohive Networks provided a good analysis of the NPRM. It looks like further in-depth study on the spectrum sharing and interference mitigation techniques will take until late 2014, and we could possibly get approval to use the new spectrum by early 2015.

It's worth noting that the European Commission is considering a similar course of promoting unlicensed spectrum policy [Full PDF, EESC Opinion Feb 2013].

This rulemaking is no small matter. The FCC spectrum policy defined over the course of 2013 will influence Wi-Fi network design and performance for the next decade (or more)! Just take a look at how the initial FCC rulemaking allowing unlicensed spectrum use in 1985 has influenced wireless networks to date, over a quarter-century later.

Here's to hoping 2013 brings a new infusion of unlicensed spectrum for the masses!

Cheers,
Andrew

Design your WLAN for High Capacity

High-Density Wi-Fi Design Series:

• Design Your WLAN for High Capacity
• Video Blog: High-Density Wi-Fi Design Part 1 - Forecasting AP Capacity
• Video Blog: High-Density Wi-Fi Design Part 2 - RF Design
• Video Blog: High-Density Wi-Fi Design Part 3 - WLAN Configuration Best Practices

The demand for high-capacity Wi-Fi networks continues to grow at an astonishing rate. The migration to 802.11n has taken Wi-Fi networking within the enterprise from an overlay to existing wired networks and made it the primary network connectivity method. And the upcoming 802.11ac standard promises to boost demand for Wi-Fi even higher. Users are increasingly adopting mobile devices that solely rely on Wi-Fi for connectivity to the network (when was the last time you left your desk without your laptop, tablet, or smartphone?). They are also carrying an average of 2-3 devices each, to work in the manner that suits them best depending on the situation.

This has spawned initiatives for consumerization of IT (corporate issued mobile devices) and BYOD (personally owned laptop and mobile devices) in many organizations. While the focus has shifted largely to supporting these devices on enterprise networks and securing the network and corporate data, organizations must also be aware of the need to re-assess Wi-Fi network performance.

But there’s a problem. Many Wi-Fi networks were never designed to handle the amount of clients or the traffic load that we see on our networks today. Instead, they were designed in an era not so long ago where simply providing adequate signal strength and coverage was sufficient.  Many organizations are quickly realizing that their existing WLAN deployments designed for basic coverage are no longer adequate to meet these growing demands and that simply adding more access points is usually ineffective, often necessitating new network planning and design. These increasing demands have brought with them new requirements to effectively design and deploy high-capacity wireless networks. But where do you start?

Aerohive’s new High-Density Wi-Fi Design and Configuration Guide provides resources for engineers working with any vendor’s equipment to understand the factors that influence WLAN deployment success, and to begin designing WLAN networks that meet the demands placed upon them.

Aerohive High-Density Wi-Fi Design and Configuration Guide
(Click to download the PDF)

The design guide covers the following topics:

• Requirements Gathering – These steps are critical to understanding the load and demand that will be placed on the network. We must know what our goal is before we can design to meet and exceed it! This includes requirements for the infrastructure, clients, applications, and forecasting the number of APs required to service the client population.
• Network Planning and Design – This section details the factors that influence Wi-Fi network capacity, including spectrum capacity, channel planning, minimizing co-channel interference, working with unique facility characteristics, collocating APs to achieve higher capacity, and site surveying. A discussion of critical wired network design variables such as switch port bandwidth, PoE, subnet allocation, DHCP, and Internet bandwidth are also included.
• Aerohive Network Configuration – Provides detailed recommendations for configuring an Aerohive Wi-Fi network for high capacity, including SSIDs, RADIUS integration, QoS, security, and radio settings.
• Network Monitoring and Optimization – Managing a high performing wireless network does not stop once it is deployed. Ongoing maintenance and network optimization will ensure that the network continues to exceed performance expectations. This section details monitoring an Aerohive Wi-Fi network through the tools provided within HiveManager to tune network performance as needs change.
• Appendix – The appendix contains useful worksheets to aid in the process of requirements gathering and forecasting capacity demands, as well as a configuration checklist for deploying the network.

One of the heavily stressed points in the document is the need for proper planning. Wi-Fi can be deceiving, because signal strength no longer guarantees a successful network. Proper Wi-Fi network design must take into account both the client and the infrastructure because airtime is a shared resource. The capabilities of your client population will directly impact the capacity and performance of your wireless network. Only by understanding your client population (or at minimum, making some educated assumptions) can your network be successful.

I put in some long hours and gave my blood, sweat, and tears to this document. I hope it proves valuable for anyone reading it, and translates into successful WLAN deployments.

Cheers,

Andrew

This post originally appeared on the Aerohive Blogs website.