I have invested close to $700 (five Happy Bubbles BLE sensors and a half dozen BluKii beacons) and 40 hours in my attempt to use BLE for presence at home. While it is possible to use BLE as a binary presence sensor for arrival, BLE is not, because of the process latency, effective for creating departure events that will lock the house while the user is there to hear the door lock.
BLE is also not a reliable solution for locating objects inside a house. Here is the salient sentence from the conclusion of a study that I wish I had found before my investment of time and money into BLE: "The original goal of this research was to develop an improved indoor positioning system using iBeacon technologies. However, after numerous and extensive experiments, we realized that the signal variation was too high to retrieve accurate distance estimation for designing a reliable and robust localization system." This summary aligns perfectly with my R&D work. BLE may be effective for triggering advertising content in a retail sales space. However, the accuracy of BLE devices for positioning within the confines of a house is not useful.
Further, because BLE is not able to provide an accurate location, it is not possible to consistently and accurately determine the motion of an object that is "leaving" the house and "moving" to the outside.
Others may have mentioned here the problems with using a cell phone to determine presence. The first day I tuned on presence detection in my house full of iPhones, I learned the hard way that the iPhone goes routinely to sleep, which causes it to disconnect from the network. I received a text every 30 minutes through the night as iPhones woke up and reestablished their network connections.
The Android does not demonstrate the same behavior as the iPhone and is fairly reliable for determining presence. However, it is not perfect.
A summary of my discovery:
The iPhone, Android, and BLE are all able to provide an "arrival event" with differing degrees of latency. The android that my wife keeps in the glove box of her car just for presence arrival can effectively unlock the door as she arrives in the driveway. As a binary "presence" sensor, BLE and Android are pretty reliable. Note that the Android creates phantom departure events from time to time. Unless it is always moving around, the iPhone is not reliable as a persistent presence sensor because of its tendency to drop and reconnect to the network.
Because "not at home" is dependent upon the latency of the detection of a device departure from the network, none of these devices are reliable as a way to lock a house if the requirement is to hear the lock close while the user is within hearing range of the door lock.
I have arrived at the conclusion that RFID and NFC are going to be the most reliable means of "touchless" arrival and departure. I have found that the most reliable is the actual door lock. Until I roll out my esp32/RFID solution, my presence detection is an active approach using a Schlage Sense deadbolt and NodeRed sequences. Everybody in the household has a dedicated access code. There are also NodeRed sequences that capture lock and unlock events using the knob on the inside as well.
My motive in sharing here is time savings for those who are in the discovery phase. While there are some who report success using BLE and mobile phones for presence, my experience has shown that none are an effective way to lock a house if the lock use case requires hearing the lock actually lock.
Hope this helps.
