Among other issues raised in a bring-your-own-device environment, throughput capacity and the associated cabling backhaul must be considered.
by Patrick McLaughlin
The bring-your-own-device (BYOD) wave is not just cresting. It already has crashed on many end-user organizations whose individual users are connecting to networks via their own personal wireless devices. The administration implications, including security measures, are significant for the user organization, whether it is a corporation, educational institution or any other environment.
From the strict standpoint of data throughput and the capacity to handle the amount of traffic generated by a BYOD implementation, the considerations are significant. In a recently published white paper, Meru Networks (www.merunetworks.com) senior marketing manager Rich Watson explains, "The personal mobile device has become such a part of the landscape that we are now seeing a BYOD trend in the enterprise. Many of the new smartphones and tablets are dual-mode--supporting both cellular and WiFi services--and have the ability to attach to an 802.11 wireless corporate network and fulfill many of the computing needs of an individual's workday responsibilities."
In the most recent Cisco Visual Networking Index (VNI), published in February 2013, Cisco Systems (www.cisco.com) compares popular mobile devices to basic-feature phones in terms of the amount of traffic each device generates. "The proliferation of high-end handsets, tablets and laptops on mobile networks is a major generator of traffic, because these devices offer the consumer content and applications not supported by previous generations of mobile devices," the VNI explains. "A smartphone can generate as much traffic as 50 basic-feature phones; a tablet as much traffic as 120 basic-feature phones; and a single laptop can generate as much traffic as 368 basic-feature phones."
Meru's Watson adds, "As the number of mobile applications has grown, the increased use of smartphones/tablets has resulted in a meteoric rise in bandwidth demand. This demand is driven, to a great extent, by the popularity of streaming video on Apple iPhones or iPads. For cellular providers, this increased demand has taxed their network capacity, catching them off guard, and most are now abandoning their ‘all-you-can-eat' data plans and implementing metered data plans instead.
"This increased demand is mirrored in the corporate BYOD context because users expect that, ‘If it works from home, why not at work?' This new demand will also tax a WiFi network to supply sufficient bandwidth, especially with newer and more powerful mobile devices coming on the market every day…Providing ample wireless bandwidth for enterprise users is a challenge with the current commercially available WiFi solutions."
In a white paper separate from its VNI, Cisco, like Meru's Watson does in his paper, explains how and why the forthcoming 802.11ac wireless standard from the Institute of Electrical and Electronics Engineers (IEEE; www.ieee.org) is a step toward solving the BYOD-created capacity challenges for enterprise environments. In a paper titled "802.11ac: The fifth generation of WiFi," Cisco cites "high-density environments with scores of clients per AP [access point]," as one of the drivers for 802.11ac. It adds that these high-density situations "are exacerbated by the BYOD trend such that one employee might carry two or even three 802.11 devices and have them consuming network resources all at once."
So what is 802.11ac, and how realistic is it to think the wireless-transmission technology will adequately address the throughput crunch many are experiencing? "802.11ac is an evolution improvement to 802.11n," Cisco's paper explains. "One of the goals of 802.11ac is to deliver higher levels of performance that are commensurate with Gigabit Ethernet networking." Among those performance levels are "seemingly ‘instantaneous' data transfer experience," and "a pipe fat enough that delivering high quality of experience is straightforward," Cisco says.
From a technological standpoint, the speed increase promised by 802.11ac is accomplished primarily through three means. As Cisco explains they are: 1) more channel bonding, increased from the maximum of 40 MHz in 802.11n to 80 or even 160 MHz; 2) denser modulation, with 802.11ac using 256 quadrature amplitude modulation (QAM), which is up from 802.11n's 64 QAM; and 3) more multiple-input, multiple-output (MIMO), to the tune of eight streams as opposed to 802.11n's four MIMO streams.
It is expected that 802.11ac products will arrive on the market in two waves. The second wave is expected to introduce a new technology called multiuser MIMO (MU-MIMO), Cisco further explains. It elaborates: "Whereas 802.11n is like an Ethernet hub that can only transfer a single frame at a time to all its ports, MU-MIMO allows an AP to send multiple frames to multiple clients at the same time over the same frequency spectrum."
Watson of Meru further notes, "Like many exciting new technologies, 802.11ac will be adopted first in the consumer space. Wireless multimedia streaming is the initial use case envisioning 802.11ac and the speed and quality improvements of 802.11ac will enable multiple streams of high-definition video on home WiFi networks. Next, a new wave of tablets will leverage 802.11ac as part of their support for higher-definition video. Smartphones will then be redesigned to support WiFi in the 5-GHz band, based on the new 802.11ac chipsets."
What about cabling?
802.11ac will be a 5-GHz-only technology, unlike previous-generation WiFi, including 802.11n, which uses both the 2.4-GHz and 5-GHz bands. The general expectation is that 802.11ac will not displace 802.11n, but rather enterprise adopters of 802.11ac will maintain their 802.11n networks. Watson notes, "One way to view 802.11ac is as a superset of 802.11n, operating in the 5-GHz band. WiFi clients with 802.11ac technology will operate seamlessly in 802.11n infrastructures and will perform as well as the best 802.11n clients at 5 GHz. Conversely, 802.11ac infrastructures will support 5-GHz 802.11n clients at full performance and with the best possible coverage."
Cisco adds, "802.11ac is a 5-GHz-only technology, so dual-band APs and clients will continue to use 802.11n at 2.4 GHz. However, 802.11ac clients operate in the less-crowded 5-GHz band."
Scott Thompson, president of Oberon Inc. (www.oberonwireless.com) is authoring an article titled "New Gigabit wireless to support global mobile data growth." We intend to publish that article in its entirety in a future issue. It covers significant ground on 802.11ac, in addition to discussing the also-in-development 802.11ad set of specifications. Thompson addresses the cabling considerations of 802.11ac. He says, "As 802.11n wireless networks were deployed, it was demonstrated that cabling for 1 Gigabit Ethernet was required, because MAC [media access control] throughput could exceed 100 Mbits/sec. What will 802.11ac require? That depends on what wave of technology is being deployed.
"802.11ac silicon will be rolled out in two waves…Because the second-wave silicon is able to process much wider bandwidth waveforms, it has a significant impact on data throughput. With the emergence of the second wave of silicon, the uplink may need to be enhanced, either by an upgrade to 10 Gigabit, or with two, 1-Gigabit connections. This assumes the AP will provide you with two, 1-Gigabit jacks."
As BYOD becomes a way of life not just in corporate environments but in facilities like schools, hospitals and even government buildings, many aspects of wireless networking must accommodate. Looking strictly at throughput speeds, the anticipated capacity of second-generation 802.11ac technology is likely to give rise to the need for new or upgraded cabling to act as a backhaul. ::
Patrick McLaughlin is our chief editor.
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