Method for determining propagation delays

A user equipment comprising:

• a plurality of antenna panels;
• a plurality of proximity sensors comprising a proximity sensor on each antenna panel of the plurality of antenna panels, each proximity sensor comprising a dedicated radar sensor configured to measure distance to an object and to distinguish between different types of objects;
• at least one processor;
• and
• at least one memory, said at least one memory stored with computer program code thereon, the at least one memory and the computer program code configured to, with the at least one processor, cause the user equipment at least to perform:
• measure a plurality of downlink reference signals received from an access node by analyzing a power delay profile (PDP) of a synchronization signal block (SSB) on each antenna panel of the plurality of antenna panels individually;
• select a first antenna panel of the plurality of antenna panels receiving a best quality downlink reference signal, of the plurality of downlink reference signals, from a primary angular direction to be used for a connection to the access node;
• trigger a maximum permissible exposure (MPE) event in response to the proximity sensor of the first antenna panel detecting a robot;
• measure, under MPE power restrictions, the best downlink reference signal received from the access node on any antenna panel of the plurality of antenna panels from angular directions different from the primary angular direction;
• determine that under the MPE power restrictions the best quality downlink reference signal is received at a second antenna panel, of the plurality of antenna panels, at least from a secondary angular direction different from the primary angular direction;
• measure that a power level of the best quality downlink reference signal received at the second antenna panel from the secondary angular direction is higher than a power level of the best quality downlink reference signal received at the first antenna panel from the primary angular direction by a predefined threshold;
• measure a propagation delay difference between the best quality downlink reference signal received at the first antenna panel from the primary angular direction and the best quality downlink reference signal received at the second antenna panel from the secondary angular direction;
• send, upon detecting that the propagation delay difference exceeds a predetermined threshold, an indication to the access node,
• wherein said indication comprises the propagation delay difference measured as time difference of arrival (TDoA) of the downlink reference signals received from the primary angular direction and from the secondary angular direction,
• wherein said indication is in a Medium Access Control (MAC) layer Control Element (CE),
• wherein the downlink reference signals comprise a synchronization signal block (SSB), and the quality of the downlink reference signals is measured as a reference signal received power (RSRP) level;
• wherein the computer program code configured to, with the at least one processor, further cause the user equipment at least to perform:
• determine that uplink transmission beam change is needed;
• align a narrow uplink beam towards the secondary angular direction of the best quality downlink reference signal by utilizing aperiodic channel state information reference signal (CSI-RS) with repetition ‘ON’ scheduled by the access node and by using a wider uplink beam until alignment of the narrow uplink beam is completed;
• determine a difference between an RSRP of the aperiodic CSI-RS with repetition ‘ON’ on a MPE restricted narrower beam used for downlink and an RSRP of the narrow uplink beam used for uplink;
• based on the difference in RSRP exceeding a predefined threshold:
• determine that level of the CSI-RS is sufficient to keep an uplink/downlink beam split according to the aligned narrow uplink beam;
• and
• inform the access node about imbalance in propagation paths for downlink and uplink by using the MAC CE for reporting a measured propagation difference between the source uplink transmit beam and the target uplink transmit beam.