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Beamforming: 802.11ac promises great Wi-Fi enhancements, but you can get a jump today
- — 29 February, 2012 03:35
This vendor-written tech primer has been edited by Network World to eliminate product promotion, but readers should note it will likely favor the submitter's approach.
During the past year, various members of the wireless ecosystem -- from industry advocacy groups to standards bodies to suppliers -- have been working tirelessly on new standards that will define Wi-Fi for the better part of the next decade. Now, with nearly unanimous buy-in to both 11ac and the 60GHz standard, the industry is well on its way to a quantum leap in Wi-Fi performance.
Of course, like any standard, these technology advances will take several quarters to make their way to market. Unfortunately, the uses that necessitated these new standards, such as the exponential growth of tablets and smartphones and uncompressed streaming video, will not stagnate as enterprises wait to upgrade their infrastructure.
MOBILE WORLD CONGRESS: Speedy 802.11ac Wi-Fi set for fast, wide rollout
In the meantime, there is an existing technology solution -- beamforming -- already available in access points and end devices that dramatically improves Wi-Fi performance, smoothing the path to 11ac and beyond. Beamforming, a non-proprietary technology, is not only compatible with the emerging 11ac products, but also part of the new standard's specification, meaning any immediate investments in technology will not be nullified as 60GHz and 11ac infiltrate the enterprise.
Beamforming is a non-proprietary wireless technology that can be integrated across a range of devices, from access points to laptops to smartphones. It greatly improves wireless performance, providing a 2X-3X improvement over previous wireless solutions.
Beamforming enables this performance with an innovative approach to how wireless devices connect. In previous generations, wireless was like a lightbulb, with a hotspot or access point "radiating" wireless indiscriminately in a set area. Beamforming is like a laser -- the hub recognizes the device that needs wireless and focuses the wireless directly where it's needed -- whether it's one device or 20. Because of this novel approach, wireless can also beam around corners and through walls, eliminating previous performance obstacles encountered in large enterprise spaces.
In an enterprise environment, not all devices on the network need beamforming to reap the benefits of the technology. An access point with implicit beamforming technology can still directly "beamform" to an end device without it, enabling better performance. Inversely, a tablet with beamforming technology can better leverage the wireless signal from an access point that does not have beamforming.
Devices leveraging beamforming, from access points to end devices, have been shipping in volume since November 2010. As enterprise IT departments upgrade their infrastructure and invest in new equipment for employees, it will be beneficial to work with technology suppliers to ensure new investments boast beamforming technology.
Users can identify that beamforming is supported by their product if the vendor touts the technology as a differentiating feature. For example, Cisco brands beamforming as ClientLink/ClientLink 2.0 on its enterprise access point products.
Beamforming is a technique implemented in digital signal processing (DSP) logic to improve range and data rate for a given client. In a basic system (single stream), it works on the principle that signals sent on separate antennas can be coordinated to combine constructively at the receive antenna.
Specifically, the phases of the transmit signals are manipulated to improve directivity. Transmit beamforming is specified in the IEEE 802.11n specification and takes advantage of the multiple transmit antennas available in a multiple-input multiple-output (MIMO) system. Efficient steering of individual streams in such a system provides overall gain. This can be achieved through knowledge of the channel between the transmitter and receiver. Thus, it can be viewed as a form of transmit diversity with a known channel.
Beamforming enables higher data rates and reduced number of retries, which increases the overall capacity of the system, leading to more efficient use of the spectrum. For example, in the case of a four transmit antenna system beamforming to a one receive antenna system, the gain improvement can be up to 12 decibel and range improvement can be up to twice over a system without beamforming.
Additionally, beamforming provides up to 12db of perceptible gain in over-the-air tests in home and enterprise environments, and increases the rate at range of HD video streaming applications by about two times their current range with the same bandwidth.
As part of the 11ac wireless specification, beamforming is expected to become standard on wireless device beginning in 2013. Enterprises, however, can begin to take advantage of the technology now to improve performance while ensuring their technology investments will not be nullified with the next generation of wireless solutions.
Giordano is director, wireless marketing at Marvell Semiconductor. He worked for six years at Cisco Systems, where he was a senior engineer focused on the implementation of advanced security technologies for virtual private network (VPN) routers and switches. Currently, he is responsible for product definition, technical marketing and business development across Marvell's complimentary wireless product line.
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