Final chapter: beamforming, virtual cell and DAS
The Wi-Fi client environment is growing chock-full of devices of varying output levels and receive sensitivities. The consensus seems to be that it’s up to the enterprise-class Wi-Fi infrastructure vendors to tame the airwaves, while consumer client device makers focus on the slick and the cool.
The last newsletter mentioned a recent move by Aerohive to introduce high-powered radios with discrete components that can deliver a 5dB improvement in receive sensitivity.
Other vendors take different approaches.
ANALYSIS: Wi-Fi client surge forcing fresh wireless LAN thinking
Ruckus Wireless’ smart antennas, for example, support zillions of over-the-air paths so that APs can automatically focus the RF energy they radiate directly at a receiving Wi-Fi client device to improve its signal reception.
Meanwhile, Meru Networks has long put control of AP-to-client associations in the hands of its WLAN controllers, rather than allowing the client to make AP association decisions as in traditional architectures. The company also associates one AP with one channel only in a single-channel, “virtual” cell architecture. The setup aims to eliminate co-channel interference and roaming and thus maintain QoS.
Some distributed antenna systems (DASs) mimic the Meru setup for indoor cellular connections and “layer” different traffic types onto different channels for QoS. DAS vendors tend to fully traffic engineer the wireless environment for the poorest-performing client, because cellular long has been a comparatively low-bandwidth environment serving devices with low battery power.
Some DAS vendors, such as InnerWireless, allow you to piggyback your Wi-Fi onto the structured systems for the performance and QoS benefit of that engineering. You still run your APs (models with external antenna connections which instead plug into the coaxial DAS system) and your WLAN controller (if using a controller-based system).
DASs can be expensive — in part for the traffic engineering that goes into their setup — but could be worth it if a) you already have one installed for your in-building cellular connections anyway and b) if you’re a healthcare, financial or other institution running mission-critical applications over Wi-Fi and feel you can justify the expense of a fully engineered environment.
