Demystifying Beamforming

Demystifying
Beamforming
Ruckus Wireless | White Paper Beamforming is the newest Wi-Fi
innovation to extend range and
improve reliability. Learn why.
Introduction: Why Wi-Fi Must Do More What is Beamforming?Wireless local area networks (WLANs) are quickly progressing Beamforming is a specialized method of radio-frequency (RF) beyond serving as "spot" solutions for data-centric, vertical transmission most often used in Wi-Fi access points (APs). APs applications such as retail barcode scanning and warehouse that support beamforming focus the RF energy they radiate inventory picking. With the Ethernet-like throughput potential directly at a receiving Wi-Fi client device. The purpose is to of the 802.11n Wi-Fi networks, WLANs are strong contenders improve signal reception at the client and, as a result, increase for becoming businesses' mainstream, primary LAN access throughput.method. Beamforming can do more than improve average throughput In addition, because of the trend toward uni? ed communica- rates. It can be implemented in a way that delivers predictable tions, collaborative network applications and IPTV, WLANs throughput at a given range-performance that is sustained will soon be expected to regularly transport application traf? c even when the client device is in motion. Having both ample types that require predictable network throughput. Among this bandwidth and consistent bandwidth available at all times traf? c is real-time voice and high-de? nition video. These mul- means users can enjoy a far more satisfying experience with timedia transmissions can't tolerate ? aky network connections Wi-Fi than has traditionally been possible. Stable connections that incur signi? cant packet loss, delays and jitter. Such condi- are particularly important when users are engaged in voice tions can result in a phone call being dropped, an audio stream and video sessions, which are far less tolerant of ? uctuations in being interrupted, or a video screen breaking up. network performance than data applications.
In short, WLANs must be enhanced to deliver predictable Another valuable bene? t of beamforming is its positive effect throughput rates and to reject interference so that they behave, on "radio fog." By focusing transmissions toward receiving consistently, in an Ethernet-like manner. Beamforming is neces- clients, beamforming avoids wasted energy and doesn't create sary to bring those attributes to Wi-Fi. unnecessary RF interference in other directions.Page 2
Demystifying Beamforming
Today, there are two popular methods of beamforming (see Each beamforming approach uses a fundamentally different Figure 1): chip-based and antenna-based. And a third method technique. However, both chip- and antenna-level beamform-will ultimately combine the two. ing provide bene? ts by calculating a best path to a client device within the RF environment. Chip-based and antenna-Chip-based transmit beamforming (often abbreviated as TxBF) based beamforming can be used independently or in combi-is currently an option to the emerging IEEE 802.11n standard. nation to provide cumulative bene? ts. The section, "Chip- and Within the chip-level implementation, there are three alterna- Antenna-Level Options: A Closer Look," delves further into tive methods: legacy, implicit, and explicit beamforming. These the details of how the two different types and subtypes of methods vary by how much, if any, feedback information from beamforming operate. the client is necessary for them to work.
Antenna-based beamforming is implemented in ? rmware that What Problems Does Beamforming Solve?sits above 802.11's PHY and MAC layers. Also called smart an- By focusing energy the way a ? ashlight concentrates light, beam-tenna technology and required on the AP side only, it works with forming can extend Wi-Fi signal coverage by two to four times. all 802.11 clients (a, b, g, n) and operates in a dynamic mode to However, the improved range is really a side bene? t to two funda-adapt to changing environmental conditions and client loca- mental problems in wireless LANs that beamforming solves: tions. Currently, implementations are based on individual ven-dors' intellectual property. Ruckus Wireless is one vendor that 1) I t makes what has traditionally been inconsistent perfor-supports smart antenna-based beamforming with its patented mance predictable and stable.BeamFlex te... [download for more]