Imagination Technologies has developed a low-power configurable radio architecture for the wide range of existing and emerging protocols for the Internet of Things.
The Whisper Radio Processing Unit (RPU) from its Ensigma division uses optimized, configurable PHY and MAC blocks to support common IoT protocols such as WiFi, Bluetooth, and Zigbee with low power and a low cost. It will also support the coming 802.11ah sub-GHz version of WiFi, but will not support them all at the same time.
Richard Edgar, director of communications technology marketing at Imagination, says:
If someone wants the fully flexible version, that's the Explorer RPU that's essentially a software-defined radio. When we start moving to IoT, the power and size become more critical, so what we have done is moved to a more traditional chip architecture with hardwired PHY and MAC.
We have designed the architecture for lower-data-rate solutions on the PHY, particularly for 802.11, for example. What you can do is optimize the modems that you put in, so if you don't need a 64QAM modem, you don't need to put that in, and that allows us to go to the lower data rate. We don't see these going to much above 802.11n, and that's 72 Mbit/s. This would typically be 24 to 36 Mbit/s as a maximum, but we have … looked at this [for the future] for 11ah to make sure that the architecture is scaled to target the lower data rate.
Chakra Parvathaneni, senior director of business development for Ensigma at Imagination, says:
This is designed for lower power. Traditionally most WiFi chips were designed for performance with power gating, but here the approach is quite different. By reducing the number of bits to process, for example, by not using 64QAM, you don't need 10 bits in the data path, and that reduces the power. That's quite different to how a normal modem would be designed.