Low power IoT device: How use "deep sleep" mode without impacting user phone app experience

[Berry_iot]

I’m working on a low-power (battery operated) IoT device using ESP32, and it will have a corresponding phone app. The device will be idle most of the time, so I’d like to put it in “deep sleep” mode to minimize power. The dilemma is that the user needs the ability to open the phone app and interact with the IoT device at any time. However, if the device is in "deep sleep" mode, WiFi connectivity is off. If I put it in the other low-power modes that keep the Wifi connection, power consumption will be much higher.

What is the best way to achieve this? I’m sure this is not an uncommon scenario, how to people typically handle this?

One thought is to put the device in “deep sleep mode” but have it wake up every 1 minute to check if there’s a request from the phone app. However, this means that the user will have to wait up to a minute after opening the app before they can interact with the IoT device. This will impact the user experience and frustrate/annoy users. There’s got to be a better way. Thanks!

NOTE: Adding a hardware-based wakeup source (button, etc..) is not possible for this application as the device will not be very accessible.