3 Engineering IoT Networks
121
Profile
Service
...
Characteristic
Descriptor
...
Descriptor
Value
Properties
...
Characteristic
Descriptor
...
Descriptor
Value
Properties
Include
...
Include
Service
Characteristic
Descriptor
...
Descriptor
Value
Properties
...
Characteristic
Descriptor
...
Descriptor
Value
Properties
Include
...
Include
Fig. 3.12 GATT data hierarchy [25]
• PXP, the proximity profile. It allows a proximity monitor to detect whether a
proximity reporter is within a close range. Physical proximity can be estimated
using the radio receiver’s RSSI value, although this does not have absolute
calibration of distances. Typically, an alarm may be sounded when the distance
between the devices exceeds a set threshold.
3.3.4 IEEE 802.15.4
IEEE 802.15.4 specifies the Physical and Data Link Layer for the so-called LowRate Wireless Personal Area Networks (LR-WPANs) [27]. The main objectives of
the standard are ease of installation, reliable data transfer, short-range operation,
extremely low cost, and reasonable battery life while maintaining a flexible and