Communication Protocal

Google's IoT platform uses the following protocol for communication and connection:-

1. HTTP is a standard publish/subscribe protocol that is frequently used and supported by embedded devices, and is also common in machine-to-machine interactions.
2. MQTT (Message Queue Telemetry Transport) is a "connectionless" protocol: with the HTTP bridge, devices do not maintain a connection to Cloud IoT Core. Instead, they send requests and receive responses. Cloud IoT Core supports HTTP 1.1 only (not 2.0).

Other IoT communication technologies:-

1. Sigfox Sigfox is a narrowband (or ultra-narrowband) technology. It uses a standard radio transmission method called binary phase-shift keying (BPSK), and it takes very narrow chunks of spectrum and changes the phase of the carrier radio wave to encode the data. This allows the receiver to only listen in a tiny slice of spectrum, which mitigates the effect of noise. It requires an inexpensive endpoint radio and a more sophisticated basestation to manage the network.

References

1. https://cloud.google.com/iot/docs/concepts/protocols
2. https://www.sigfox.com/en/sigfox-iot-technology-overview
3. http://www.iot.qa/2017/12/which-are-communication-protocol-used.html