Beamflex and TxBF - Certainly not mutually exclusive

At the core of current speculation (that adaptive antenna switching is doomed with 802.11ac) is the notion that transmit beamforming (TxBF) with 11ac replaces the need for Smart Wi-Fi.

This is due to the common misconception that smart, adaptive antennas-as proprietary Ruckus BeamFlex technology-and transmit beamforming-as a standards-based technology-are one-and-the-same. They are not. Without going into a brain numbingly deep void of detailed analysis, this blog will aim to shed some light on the on the differences between Beamflex and Transmit Beamforming.

BeamFlex and TxBF are not Mutually Exclusive

BeamFlex is truly adaptive antenna technology by which an access point (AP) selects an optimal transmit path out of many possible options. It is fundamentally an antenna technology, combining special hardware and sophisticated software, that sits on top of all radio foundations (in a protocol-agnostic way).

TxBF, on the other hand, is a digital signal processing technique that occurs within the transmitting radio, and is heavily protocol dependent. It attempts to send multiple copies of the same data so as to create constructive combinations at the receiving radio. The beauty of this is that BeamFlex (antenna technology) and TxBF (radio technology) can be best friends. Ruckus can support both of these techniques at the same time (on some products) to deliver a collective benefit to signal quality.

BeamFlex works for all clients

Because it is an antenna technique-and not a radio technique-BeamFlex works equally well for all clients of all capabilities. This means 802.11a/b/g/n/ac clients all benefit, and there are no special requirements for support. Single-stream, two-, three- and four-stream clients all benefit, and there is no tradeoff as the number of streams increases.

No transmit beamforming and Spatial Multiplexing at the Same Time

Because it is a radio technique, effective TxBF DOES require client support (something a lot of people fail to understand). Consequently, 802.11a/b/g/n clients miss out on the perks. And some 11ac clients do not support TxBF. Looking at the pervasive adoption of 11n, we should not expect all (or even most) clients to support TxBF even by the end of 2016.

TxBF must also tradeoff with spatial multiplexing. The same transmitters cannot be used for both. In order to be effective, TxBF systems should have double the number of transmit antennas as spatial streams.

1x1 clients (this means one transmit and one receive radio chain, in Wi-Fi parlance) will be happy with even a 2x2 AP, but for a 2x2 MIMO client to benefit (in any appreciable way) from an AP’s use of TxBF, a 4x4 AP is desired. This also means that a 3x3 client sees miniscule (if any) benefit from an AP that is anything less than 6x6 (yes this means 6 transmitters and 6 receivers, can you even imagine what that looks like?).