Random access
Methods, apparatuses and systems random access in a communication network are disclosed.
1 . An apparatus comprising:
at least one processor; and
at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:
determine a serving beam;
obtain at least two sets of random access channel, RACH, configurations, wherein at least one of the at least two sets of RACH configurations is a beam-specific set of RACH configurations, wherein one or more RACH configurations of the beam-specific set of RACH configurations are beam-specific, wherein the beam-specific set of RACH configurations supports a subset of beams of a network node;
select one of the at least two sets of RACH configurations at least partially based on a selected beam;
determine a RACH occasion based on an ordered list of beams supported by at least one of the selected set of RACH configurations or the obtained at least two sets of RACH configurations, wherein the ordered list corresponds to a concatenation of a first partial ordered list of beams unsupported by any beam-specific RACH configuration of at least one of or any of the selected set of RACH configurations or at least one of or any of the obtained at least two sets of RACH configurations and a second partial ordered list of beams supported by at least one beam-specific RACH configuration of at least one of the selected set of RACH configurations or at least one of the obtained at least two sets of RACH configurations; and
transmit a random access preamble using the determined RACH occasion.
2 . The apparatus according to claim 1 , wherein
the selected beam is selected by the apparatus,
the selected beam is selected by the apparatus based on a type of services,
the selected beam is identical to the serving beam, or
the selected beam is different from the serving beam.
3 . The apparatus according to claim 1 , wherein
the random access preamble is transmitted on the serving beam,
the random access preamble is transmitted on the selected beam,
the random access preamble is transmitted on the selected beam, wherein the selected beam is different from the serving beam, or
the random access preamble is transmitted on the selected beam, wherein the selected beam is different from the serving beam, wherein the selected beam is selected by the apparatus.
4 . The apparatus according to claim 1 , wherein
at least one of the at least two sets of RACH configurations is a beam-independent set of RACH configurations, wherein one or more RACH configurations of the beam-independent set of RACH configurations are beam-independent, wherein the beam-independent set of RACH configurations supports at least one of:
all or a majority of beams of a network node, or
all beams of a network node not supported by any beam-specific RACH configuration.
5 . The apparatus according to claim 1 , wherein
at least one of the at least two sets of the RACH configurations comprises a respective indication of one or more beams supported by the respective RACH configuration.
6 . The apparatus according to claim 1 , wherein
the selection of the selected set of RACH configurations is at least partially based on a beam index of the serving beam.
7 . The apparatus according to claim 1 , wherein at least one of
the selected set of RACH configurations comprises a RACH configuration which supports the serving beam or
the selected set of RACH configurations is a beam-specific set of RACH configurations.
8 . The apparatus according to claim 1 , wherein the ordered list is ordered at least one of:
in ascending order of beam indices of beams supported by at least one RACH configuration of at least one of the selected set of RACH configurations, at least one of the obtained at least two sets of RACH configurations, at least one of the beam-specific sets of RACH configurations or at least one of the beam-independent sets of RACH configurations, or
in descending order of beam indices of beams supported by at least one RACH configuration of at least one of the selected set of RACH configurations, at least one of the obtained at least two sets of RACH configurations, at least one of the beam-specific sets of RACH configurations or at least one of the beam-independent sets of RACH configurations,
dependently on at least one at least one of the selected set of RACH configurations, at least one of the obtained at least two sets of RACH configurations, at least one of the beam-specific sets of RACH configurations or at least one beam
independent sets of RACH configurations, or-independently of at least one or any of the selected set of RACH configurations, the obtained at least two sets of RACH configurations, the beam-specific sets of RACH configurations or the beam-independent sets of RACH configurations.
9 . The apparatus according to claim 1 , wherein at least one of:
the RACH occasion is determined at least partially based on assistance information, or
the RACH occasion is determined at least partially based on assistance information, wherein the assistance information at least one of:
is obtained as system information,
is comprised by at least one RACH configuration, or
indicates a mapping between beams and RACH occasion.
10 . A system comprising a first apparatus and a second apparatus,
the first apparatus comprising:
at least one processor; and
at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to:
determine a serving beam;
obtain at least two sets of random access channel, RACH, configurations, wherein at least one of the at least two sets of RACH configurations is a beam-specific set of RACH configurations, wherein RACH configurations of the beam-specific set of RACH configurations are beam-specific, wherein the beam-specific RACH configurations support a subset of beams of a network node;
select one of the at least two sets of RACH configurations at least partially based on the serving beam;
determine a RACH occasion based on an ordered list of beams supported by at least one of the selected set of RACH configurations or the obtained at least two sets of RACH configurations, wherein the ordered list corresponds to a concatenation of a first partial ordered list of beams unsupported by any beam-specific RACH configuration of at least one of or any of the selected set of RACH configurations or at least one of or any of the obtained at least two sets of RACH configurations and a second partial ordered list of beams supported by at least one beam-specific RACH configuration of at least one of the selected set of RACH configurations or at least one of the obtained at least two sets of RACH configurations; and
transmit a random access preamble using the determined RACH occasion; and
the second apparatus comprising:
at least one processor; and
at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus at least to:
determine at least one beam-specific RACH configuration for at least one beam of the second apparatus;
determine a beam-specific set of RACH configurations comprising the at least one determined beam-specific RACH configuration;
transmit at least two sets of RACH configurations to at least one user equipment, UE, wherein the at least two sets of RACH configurations comprise at least one of the determined at least one beam-specific set of RACH configurations.