Random access procedure for beam based cell-less operation in 5G RAT

Baseband circuitry of a user equipment (UE) for obtaining timing advance values and beams from multiple access points, the baseband circuitry configured to:

• determine, at the user equipment (UE), a preamble transmission power, a preamble format, and a transmit timing jointly for respective ones of one or more physical random access channel (PRACH) preamble transmissions;
• generate, by the UE using the determined preamble transmission powers, preamble formats, and transmit timing, multiple PRACH preamble transmissions each to transmit to a target access points (APs);
• and
• process, by the UE based on the transmitted PRACH preamble transmissions, at least one received random access response (RAR) message with an indication of timing advance (TA) values and beams of each target AP, wherein the preamble transmission power is determined based on the UE transmit beamforming gain and path loss estimates for a set of serving beams that are generated by the sunset of the Aps, and uplink power limitations configured at the subset of the target APs.

A user equipment (YE) comprising:

• baseband circuity configured to:
• determine, at the user equipment (UF), a preamble transmission power, a preamble format, and a transmit timing jointly for respective ones of one or more physical random access channel (PRACH) preamble transmissions;
• generate, by the UE using the determined preamble transmission powers, preamble formats, and transmit timing, multiple PRACH preamble transmissions each to transmit to a. target access points (APs);
• and
• process, by the UP based on the transmitted PRACH preamble transmissions, at least one received random access response (RAR) message with an indication of timing advance (TA) values and beams of each target AP;
• and
• radio frequency circuitry with a receive signal path coupled to the baseband circuitry and to an antenna to send the preamble transmissions and to receive the random access response message), wherein the preamble transmission power is determined based on the UE transmit beamforming gain, path loss estimates for a set of serving beams that are generated by a subset of the target Aps and uplink power limitation configured at the subset of the target Aps.