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Enhancing HDX: Introducing Dynamic Bandwidth Selection – Automatically Choosing the “Best” Channel Width

Cisco Systems is announcing a new set of features that enhance its HDX (High Density Experience) suite. This blog is the first in a series that explains the new features that comprise the enhancements to HDX.

Every advancement in Wi-Fi technology comes with corresponding complexities and tradeoffs.  You just don’t get something for nothing.

For example, much of the speed improvements in the evolution from 11b to 11g/a to 11n to 11ac are achieved by simply doubling the RF channel width. Increasing channel width from 20 MHz to 40 MHz effectively enables doubling “over the air” speed. Increasing channel width from 40 MHz to 80 MHz doubles that speed again.

Of course, wider channels are more susceptible to interference (since a wider channel can “hear” more). Furthermore, with wider channels, the number of available so called “non-overlapping” channels decreases making mutual interference an increasing problem. Being able to send data over the air faster is very important, but if the devices in your WLAN are waiting more often to send data because the wider channel is more likely to be busy, then disappointment and unrealized expectations will occur. Keep in mind that because “air is shared” for Wi-Fi that it uses a “listen before talk” protocol.

Also, in a real world WLAN, it is highly unlikely to have homogeneous device types. The client mix will include legacy devices that simply can’t operate at 80 MHz (or 40 MHz). This means that spectrum could be wasted if the network is configured for a greater channel width than most of its devices can handle. This has far more consequences at 5 GHz than at 2.4 GHz since 40 MHz channels are unlikely to be usable at 2.4 GHz and 80 MHz channels cannot be used at 2.4 GHz.

Interestingly, 802.11ac does include a feature called RTS/CTS with bandwidth indication that is intended to address dynamic channel width (read more about this in 802.11ac: The Fifth Generation of Wi-Fi” section 2.3.4). The challenge is that this feature is not often used and cannot be used by either 11a or 11n clients.

Last, but far from least, no two wireless networks are the same – every wireless network is different. Even parts of the same wireless network will be different. Thus, there really is no “one size fits all” static configuration that helps offer optimization. The Wi-Fi network needs to adapt as conditions change. Read More »

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The shift in Education towards Mobile Learning

Technology is important to children in terms of how they learn and how they live. A challenge for many school districts is the ability to offer a mobile learning by putting digital resources in a student’s hands with constrained funding for education.

mobile learning

Katy Independent School District located in Katy TX needed a wireless infrastructure that would support this vision. With over 62,000 students, Katy ISD needed to move from a wireless network that was built for coverage to a network that is built for density. By providing 802.11ac-based Wi-Fi access points in classrooms and outdoor locations and centralized management, the school district is supporting more than 40,000 concurrent Wi-Fi users and empowering faculty, students and staff. Read More »

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What is 802.11r? Why is this Important?

In this short series of blogs, we’re spending some time looking at the lesser known but undeservedly underappreciated amendments to 802.11 and the features/benefits they provide.

The first blog explained the basics of 802.11k “WLAN Radio Measurements” and specifically zoomed in on the Neighbor Request/Report.

This blog will focus on the 802.11r amendment.

Fast BSS Transition (802.11r)

Fast BSS Transition (often abbreviated to Fast Transition or FT) describes mechanisms by which a mobile device can reestablish existing security and/or QoS parameters prior to reassociating to a new AP. These mechanisms are referred to as “fast” because they seek to significantly reduce the length of time that connectivity is interrupted between a mobile device and Wi-Fi infrastructure when that mobile device is connecting to a new AP. Please note that the process of disconnecting from one AP and connecting to another AP is formally designated as a “BSS transition”. Therefore, the protocols established by FT apply to mobile device transitions between APs only within the same mobility domain and within the same ESS (ESS transition is out of scope for FT). Since both reassociation and reauthentication are time critical processes, removing time consuming message exchanges between the mobile device and the infrastructure help reduce interruption to high value services (e.g., voice and/or video) when transitioning from one AP to another especially in a strongly secure WLAN (i.e, one using 802.1x and EAP methods for authentication).

Because Fast BSS Transition reestablishes existing parameters, the protocols require that information be exchanged during the initial association (or at a subsequent reassociation) between the mobile device (formally referred to as the FT Originator (FTO)) and an AP. The initial exchange is referred to as the FT initial mobility domain association. Subsequent reassociations to APs within the same mobility domain are expected to utilize the FT protocols.

Two basic FT protocols are described:

  1. FT Protocol. This protocol is performed when a mobile devices transitions from one AP to another AP but does not require a resource request prior to its transition. The AP selected by the mobile device for reassociation is referred to as the “target AP”.
  2. FT Resource Request Protocol. This protocol is performed when a mobile device requires a resource request prior to its transition.

For a mobile device to transition from the AP it is currently associated with to a target AP, the FT protocol message exchanges are performed using one of two methods:

  1. Over-the-Air. The mobile device communicates directly with the target AP using IEEE 802.11 authentication with the FT authentication algorithm.
  2. Over-the-DS. The mobile device communicates with the target AP via the current AP. Communications between the mobile device and the target AP are encapsulated within FT Action frames between the mobile device and the current AP. Communications between the current AP and the target AP, occurs via a different encapsulation method. The current AP converts between the two encapsulation methods.

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Over the Air message exchange (excerpted from IEEE 802.11-2012)

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Over the DS message exchange (excerpted from IEEE 802.11-2012) Read More »

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Creating a new guest Wi-Fi experience with CMX Connect

Guest Wi-Fi has become a must-have, not a nice-to-have requirement for our customers.  Today, let’s talk about building customer engagement through guest Wi-Fi and how CMX Connect creates a new guest Wi-Fi experience. We also have a special offer to share if you’re interested in trying out CMX (Connected Mobile Experiences) Connect.

Offering Guest Wi-Fi is a No-Brainer

Have you ever found yourself constantly checking emails on your phone, whether you are in the supermarket, a sport stadium or your doctor’s office? We live in a connected world so when people lose their Internet connectivity, they feel as uncomfortable as if they are walking in the dark. According to a Cisco report [1], one in every three college students and young professionals believes the Internet is as important as air, water, food, and shelter. At college games, fans often leave at half time if they cannot connect to the Internet to post photos or tweet comments [2]. Offering guest Wi-Fi has become a must, not an option, for most of our customers across all verticals such as retail, healthcare, sports and entertainments, and education.

Guest Wi-Fi is an opportunity to engage and delight your visitors

So you’ve decided to offer guest Wi-Fi at your venue, but how do you make the most of it from a business standpoint? According to a Hotels.com 2013 survey, the first thing hotel guests try is the quality of guest Wi-Fi, before the quality breakfast or even the comfortable bed [3]. So guest Wi-Fi is a perfect opportunity for you to engage your visitors and increase customer satisfaction and loyalty. With a seamless one-click mobile-first onboarding experience, visitors can check-in on your business Facebook page, or provide email information for future promotional campaign. Since you also know the context and location of your visitors, you can offer personalized and relevant information to visitors. For example, first-time parents connect to the hospital’s guest Wi-Fi in the Maternity ward can be served a video on changing a newborn’s diaper .

CMX Connect is built to address these use cases

We have made significant improvements in the CMX 10.1 release and will continue to partner with our customers in this journey. So how does CMX Connect help you improve your business?

  1. We have a modern and intuitive user interface so IT managers can work with the marketing team to create guest portals, collect visitors’ information, and customize promotional offers by location. You don’t need a user guide or need to write any code to create guest portals. Figure 1 shows an example of the simplicity in building a portal page. Figure 2 provides examples of guest portals built by our tool.

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Figure 1. Example of the portal builder tool.

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Figure 2. Example of custom guest portals Read More »

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Why the 802.11k and Neighbor Report are Important?

A lot of air time (pun intended) has been provided for the PHYsical layer amendments to the 802.11 standard. These would include 802.11n, 802.11ac, 802.11ad, and others. These amendments tend to get a lot of publicity because they have increased the speed/throughput of 802.11 over the years (from 1-2 Mbps in 1997 for the original 802.11 spec to “gigabit” in 2013 with the 11ac and 11ad amendments).

But what about those amendments that simply aren’t as “sexy” and provide only MAC layer enhancements? Aren’t these important too?

The answer is YES and in this short series of blogs, we’ll spend some time looking at the lesser known but undeservedly underappreciated amendments to 802.11, especially 802.11k, 802.11r, and 802.11v and the features/benefits they provide.

This first blog will explain the basics of 802.11k “WLAN Radio Measurements” and will specifically zoom in on the Neighbor Request/Report.

Wireless LAN Radio Measurements (802.11k)

Wireless Local Area Network (WLAN) Radio Measurements can enable any device, AP or client, with the capability to better understand the environment in which it is operating. A variety of requests can be generated for which the device receiving a request can respond with a report.

As one example, an AP could ask a client “how well are you hearing me?” using a Link Measurement request. The client would respond with a Link Measurement report (conversely, a client could ask an AP “how well are you hearing me?”).

Since the ability to measure and collect information is provided, a device submitting a request can make a better informed decision as to its “next steps” in adapting to/compensating for the dynamics of the WLAN environment.

Information obtained from a measurement and/or report can be made available to upper layers of the measuring and/or requesting device where it may be used for a range of applications. Such applications may be engaged in attempting to preserve the QoE (Quality of Experience) for the end user.

As one example, in order to preserve the QoE for applications such as VoIP and video streaming, WLAN Radio Measurements may be used by client device to collect information from the AP prior to that client device disassociating from one AP and reassociating to a new AP. This can dramatically speed up reconnecting from one AP to another AP in the same WLAN.

802.11k describes the following measurements: Read More »

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