4.2.5.1 Proximity Profile

In the context of Bluetooth Low Energy (BLE), “proximity” generally refers to the physical closeness between two BLE devices. The BLE Proximity profile is a standardized BLE profile that enables a device to alert a user when another device is near or far away from it.

The Proximity profile defines the behavior when a device moves away from a peer device so that the connection is dropped or the path loss increases above a preset level, causing an immediate alert. This alert can be used to notify the user that the devices have become separated.

The BLE Proximity profile typically involves two roles:

1. **Proximity Reporter (Server)**: This is the device that is being tracked, such as a key fob, a , or any other device that you want to monitor the proximity of.

2. **Proximity Monitor (Client)**: This is the device that tracks the proximity of the reporter, usually a smartphone/tablet/device that the user carries with them.

The Proximity profile uses the RSSI (Received Signal Strength Indicator) to determine the approximate distance between the monitor and the reporter.

Role/Service Relationships

The following figure shows the relationship between services and the two profile roles. The dotted line indicates that the service within this line is optional.

Proximity Reporter Requirements

The Proximity Reporter must have one instance of the Link Loss service and may have instances of both the Immediate Alert service and the Tx Power service. Next, we will discuss these services in detail.