This diagram illustrates how the voice service works with Alexa devices to control smart home devices (e.g., smart bulb, thermostat, etc.). To control a smart device, a user can speak a voice command to an Alexa device after waking it up with voice “Alexa”. The Alexa then sends the sounds of that voice command to a remote voice processing cloud via its connected WiFi network. Once the cloud recognizes the sounds as a valid command, it is forwarded to a server, called smart home skill adapter, which is maintained by Amazon to enable the cooperation with thirdparty service providers. Afterwards, that command is sent to another cloud which can control the corresponding smart device remotely. Note that in addition to the control of smart devices, some functions (e.g., checking the weather, placing orders on Amazon.com, etc.) provided by Alexa devices can also be accessed by voice commands.
The Insecurity of Home Digital Voice Assistants
LUIS (Language Understanding Intelligence service)
LUIS is used to create natural language into apps and IoT devices, which is related to voice assistants as a third party. Alexa devices does not use this LUIS, but they have their own service Alexa Voice Service (AVS).
Making Amazon Alexa smarter with Microsoft Cognitive Services
MIS Senior Project 