Methods and apparatus for beamforming and initial access

A wireless transmit/receive unit (WTRU) for determining resources, the WTRU comprising:

• a processor, operatively coupled to a transceiver, the processor and the transceiver configured to measure a plurality of beam reference signals transmitted from a base station;
• the processor configured to select a beam reference signal from among the plurality of measured beam references signals;
• the transceiver configured to receive a configuration message, wherein the configuration message is at least one of a broadcast message or a radio resource control (RRC) message, from the base station that includes correspondence information regarding the plurality of measured beam reference signals, wherein the correspondence information includes information regarding designation of at least one set of Physical Random Access Channel (PRACH) resources for each of the plurality of measured beam reference signals;
• the processor configured to determine a set of PRACH resources for the selected beam reference signal based on the information regarding designation of at least one set of PRACH resources for each of the plurality of measured beam reference signals included in the received correspondence information;
• and
• the processor and the transceiver configured to transmit a PRACH transmission using at least one PRACH resource of the determined set of PRACH resources.

A method for use in a wireless transmit/receive unit (WTRU) for determining resources, the method comprising:

• measuring, by the WTRU, a plurality of beam reference signals transmitted from a base station;
• selecting, by the WTRU, a beam reference signal from among the plurality of measured beam references signals;
• receiving, by the WTRU, a configuration message, wherein the configuration message is at least one of a broadcast message or a radio resource control (RRC) message, from the base station that includes correspondence information regarding the plurality of measured beam reference signals, wherein the correspondence information includes information regarding designation of at least one set of Physical Random Access Channel (PRACH) preambles, wherein the at least one set of PRACH preambles includes one or more PRACH preambles, for each of the plurality of measured beam reference signals;
• determining, by the WTRU, a set of PRACH preambles for the selected beam reference signal based on the information regarding designation of at least one set of PRACH resources for each of the plurality of measured beam reference signals included in the received correspondence information;
• and
• transmitting, by the WTRU, a PRACH preamble of the determined set of PRACH preambles.