Radios beat a path to new channels for IoT devices
The emerging 802.11ah specification for running low-power WiFi over 900MHz at distances up to a kilometer is one of the most promising new radios. "We believe this new standard is a very strong candidate for IoT applications in smart homes and buildings where a Wi-Fi router is nearby," says Kathleen Philips, who heads an ultra-low-power wireless research program at the Holst Center, a partner with Imec in the Netherlands.
Home and building automation has been a fragmented market served by a host of incompatible wireless protocols including EnOcean, 6LowPAN, WirelessHART, ANT, and RF4CE—most requiring their own gateways. "The definition of this Wi-Fi extension can be a major catalyst for these markets, because it will communicate with already available infrastructure, resolving interoperability issues," Philips told EE Times.
Her group is designing an 11ah chip now that aims to send 100kbit/s distances of up to a kilometer with a peak transmit power consumption of 12mWs and 5mW for the receiver. "Since this is expected to be one of the new mass markets, vendors will differentiate on cost, battery life, robustness, and distance," she says.
Holst also is researching far-field RF wireless charging over a distance of 5m to 10m as an alternative to inductive approaches that require close alignment of coils. The approach is geared for IoT devices that cannot be easily moved to align with an inductive technique and do not have access to other energy sources.
"With a 3W EIRP source transmitting at 915MHz, we can harvest 30µW on a continuous basis from up to five meters away from the source," Phillips says, describing her group's current work.
In other efforts, the Holst team is developing a radio for personal area networks that consumes 5.1mW, has a -95dBm sensitivity and supports Bluetooth 4.0, IEEE 802.15.4, and Zigbee protocols. It is also working on a radio for smart buildings that consumes 4mW in receive mode, has a -120dBm sensitivity, and supports multiple protocols.
Riding millimeter waves
At the high end of the spectrum, Imec is among a growing set of researchers that see many mass-market applications emerging in the millimeter wave spectrum from 60GHz to 90GHz, spanning automotive radar to 5G cellular links.
Imec reported earlier this year on its work on a 79GHz radar transceiver in 28nm CMOS that has more than 10 per cent efficiency. It is now measuring results of its work, aiming to integrate the transceiver into a cm2 SoC with a phased array antenna.
Researchers see a broad set of high-volume apps emerging for millimeter wave radios.
Such millimeter wave designs will benefit from emerging work in massive MIMO antennas, says Liesbet Van der Perre, a group science director in wireless research at Imec. She predicts 2020 base stations could use the technique to deliver backhaul connections at 1.17Gbit/s at power consumption levels of 90W. That's up from 270Mbit/s for today's base stations consuming 700W, she said.
Imec is leading a research collaboration in the European Union that aims to develop core technology for algorithms, DSPs and radios for massive MIMO. "It's not classic MIMO, it's a new scheme and very disruptive," she told us.
Separately, Van der Perre discussed early work on a reconfigurable 10Gbit/s radio module for 5G, targeting the 16nm node. It would integrate past work in base bands, transceivers, and frequency-flexible front-end modules.
The group's work is focused on CMOS, which she claims is catching up to the millimeter wave capabilities of silicon germanium at the 20nm node.
CMOS will catch up with SiGe's millimeter wave capabilities at 20nm, Imec believes.
- Rick Merritt
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