Communication device with passive proximity detection

A communication device comprising:

• at least one antenna that receives and transmits signals;
• a frontend communicatively coupled to the at least one antenna and that converts downlink signals to downlink baseband signals and uplink baseband signals to uplink signals;
• a memory containing a passive proximity detection module and a baseline threshold value;
• and
• a controller communicatively coupled to the frontend and the memory, and that executes the passive proximity detection module to enable the communication device to:
• receive via the one or more antennas a downlink reference signal from a radio access network (RAN);
• determine, by the frontend, a downlink characteristic of the downlink reference signal;
• compare the downlink characteristic to the baseline threshold value;
• determine whether a person is in proximity to the one or more antennas based on the downlink characteristic being indicative of a proximity to the person;
• and
• limit transmit power level of the frontend in response to determining that the downlink characteristic is indicative of the proximity to the person.

A computer program product comprising:

• a computer readable storage device;
• and
• program code on the computer readable storage device that when executed by a processor associated with a communication device having one or more antennas coupled to a front end, the program code enables the communication device to provide the functionality of:
• receiving, by the one or more antennas, a downlink reference signal from a radio access network (RAN);
• determining, by the frontend, a downlink characteristic comprising a selected one or more of received power and received quality of the downlink reference signal;
• comparing, by a controller of the communication device, the downlink characteristic to a baseline threshold value;
• determining whether a person is in proximity to the one or more antennas based on the downlink characteristic being indicative of a proximity to the person;
• and
• limiting transmit power level of the frontend in response to determining that the downlink characteristic is indicative of the proximity to the person.