Monday, 28 May 2012

Mobility and education - High Density Wireless

The ubiquity of mobile devices is set to push mobile and wireless networks to the limit. There is no better example than the mobile devices are being carried by University students and used in lectures. Now the problem isn't each student bringing a mobile device to their lecture but each student bringing multiple devices. In fact the expectation is that soon each of them will be equipped with 3-5 devices. The mobile phone is a given, predominately smartphones - iPhones and androids being the most popular. Students need to stay in touch via their Cloud Aggregation Devices (as I like to call them) but perhaps more relevant name in the case of a student may be a Social Aggregation Device. Secondly, tablets are becoming the prevalent device of choice for the techno-savvy student. Easy to carry and instant on with good battery life they offer features that the humble notebook cannot. And that brings me to the notebook, still the most common device carried by students with numbers moving from 55% to near 90% (to lectures) in the past three years. Add in the odd Kindle, iPod touch and a myriad of other devices and your average student is lofting very substantial compute power.

So, we have numerous students carrying multiple devices to the lecture theatre. Given that up to 500 students will fit in the larger lecture theatres this is somewhat of a challenge. 1500-2500 devices trying to operate on wireless or for that matter the mobile network within the small footprint of a lecture theatre sounds like a recipe for failure. So what can we do to mitigate this frightful situation before someone gets (their data) throttled? Well your home wireless access point isn't going to cut it. We're talking some serious radiation power here, maintaining thousands of connections and providing reasonable data transfer performance. So what is up to the task?

Well, I was going to spend a whole bunch of time going through the process of investigating then telling you all about it but someone has beaten me to it - Cisco! Check out the Wireless LAN Design Guide for High Density Client Environments in Higher Education. This is a great whitepaper that has detailed information on the various phases (Plan, Design, Implement, Optimise and Operate). Naturally this is very Cisco-centric.

As above, the whitepaper discusses data throughput rates as well as client density vs. Access Point density and in detail the placement of Access Points. Interesting the whitepaper discusses controlled attenuation as a desirable trait as this allows channel reuse, which when you think about it is logical. Obviously this is most apparent in the 2.4GHz range.

Cisco naturally promotes the use of its CleanAir technology as well as ClientLink which are two great technologies. Cisco CleanAir technology uses silicon-level intelligence to create a spectrum-aware, self-healing, and self-optimizing wireless network that mitigates the impact of wireless interference and offers performance protection for 802.11n networks.
Cisco ClientLink (2.0) technology specifically focuses on mixed-client networks, optimizing overall network capacity by ensuring that 802.11a/g and 802.11n clients operate at the best possible rates, especially when they are near cell boundaries.

What would I suggest we use for the 1500-2500 client devices I started talking about? Well, we'd have to do more than a bit of diligent investigation into the exact requirements. But in the end I don't think we'd necessarily need as much kit as I initially assumed. In fact the majority of the expense would be in the determination of requirements, design and optimisation.
For more information:
Cisco Enterprise Mobility 4.1 Design Guide
Optimize the Cisco Unified Wireless Network to Support Wi-Fi Enabled Phones and Tablets

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