Method for beam recovery based on spatial diversity or transmission power
An apparatus including: circuitry for receiving reference signals including a plurality of channel synchronization signal blocks and/or state information reference signals on a downlink channel; circuitry for measuring received signal power and/or quality level of said reference signals; circuitry for estimating arrival directions or an arrival antenna panel for a plurality of beams associated with said reference signals; circuitry for estimating, based on at least the received signal power and/or quality level, a required transmission power for a random access channel preamble for each beam; circuitry for selecting, in response to detecting a failure of a serving beam, another of said beams according to spatial diversity and/or required transmission power; and circuitry for sending the random access channel preamble on the selected beam.
1 . An apparatus, comprising:
at least one processor; and
at least one non-transitory memory storing instructions that, when executed with the at least one processor, cause the apparatus to perform:
receiving reference signals comprising at least one of a plurality of channel synchronization signal blocks or state information reference signals on a downlink channel;
measuring at least one of received signal power or quality level of said reference signals;
estimating arrival directions or an arrival antenna panel for a plurality of beams associated with said reference signals;
estimating, based on at least one of the received signal power or quality level, a required transmission power for a random access channel preamble for the plurality of beams;
selecting, in response to detecting a failure of a serving beam, another of said plurality of beams according to at least one of spatial diversity or required transmission power; and
sending the random access channel preamble on the selected beam; and
ranking at least one beam of the plurality of beams into a preference order based on at least the arrival direction or the arrival antenna panel of the ranked beams and the required transmission power for the random access channel preamble of the ranked beams.
2 . The apparatus according to claim 1 , wherein
said plurality of beams include at least one serving beam and one or more candidate beams as a back-up for the serving beam.
3 . The apparatus according to claim 2 , wherein said instructions, when executed with the at least one processor, cause the apparatus to select one of said one or more candidate beams such that at least one of:
a selected first candidate beam has the arrival direction differing more than a first threshold value from the arrival direction of the serving beam or an arrival antenna panel different from the antenna panel of the serving beam, or
the required transmission power for the random access channel preamble is below a second threshold value.
4 . The apparatus according to claim 3 , wherein:
in response to receiving no acknowledgement to the random access channel preamble sent on said selected first candidate beam, said instructions, when executed with the at least one processor, cause the apparatus to select a second candidate beam among said candidate beams such that the second candidate beam has the arrival direction differing more than a first threshold value from the arrival direction of the selected first candidate beam or an arrival antenna panel different from the antenna panel of the selected first candidate beam.
5 . The apparatus according to claim 1 , wherein the apparatus is further caused to perform,
spatially grouping the plurality of beams into two or more groups based on the arrival direction or the arrival antenna panel of the beams;
wherein said instructions, when executed with the at least one processor, cause the apparatus to select, in response to detecting a failure of the serving beam, a candidate beam from a group different from a group including at least one of the serving beam or a previously selected candidate beam.
6 . The apparatus according to claim 1 , wherein the instructions, when executed with the at least one processor, cause the apparatus to adjust the preference order based on received beam quality.
7 . The apparatus according to claim 1 , wherein the apparatus is further caused to perform,
increasing, in response to receiving no acknowledgement to the random access channel preamble sent on the selected candidate beam, transmission power of the selected candidate beam.
8 . The apparatus according to claim 1 , wherein the instructions, when executed with the at least one processor, cause the apparatus to adjust the estimation based on one or more of:
an estimated or a measured pathloss,
an antenna or a beam gain,
desired power level at an access point,
received transmit power control command from the access point,
transmission power ramping level, or
a number of re-attempts for establishing a beam connection.
9 . The apparatus according to claim 1 , wherein the instructions, when executed with the at least one processor, cause the apparatus to adjust the selecting of the candidate beam based on at least one of a latency for random access occasion or interference among the candidate beams.
10 . The apparatus according to claim 1 , wherein the apparatus is further caused to perform estimating the arrival directions for the plurality of beams as an angle-of-arrival at an antenna panel accuracy or a beam-level accuracy.
11 . The apparatus according to claim 1 , wherein the selecting of a candidate beam is applied one or more of the following random access procedures:
contention-free random access beam failure recovery,
contention-based random access beam failure recovery,
radio link failure recovery, or
initial access.
12 . A method comprising:
receiving reference signals comprising at least one of a plurality of channel synchronization signal blocks or state information reference signals on a downlink channel;
measuring at least one of received signal power or quality level of said reference signals;
estimating arrival directions or an arrival antenna panel for a plurality of beams associated with said reference signals;
estimating, based on at least one of the received signal power or quality level, a required transmission power for a random access channel preamble for the plurality of beams;
selecting, in response to detecting a failure of a serving beam, another of said beams according to at least one of spatial diversity or required transmission power;
sending the random access channel preamble on the selected beam; and
ranking at least one beam of the plurality of beams into a preference order based on at least the arrival direction or the arrival antenna panel of the ranked beams and the required transmission power for the random access channel preamble of the ranked beams.
13 . The method according to claim 12 , wherein
said plurality of beams include at least one serving beam and one or more candidate beams as a back-up for the serving beam.
14 . The method according to claim 13 , comprising
selecting one of said candidate beams such that a selected first candidate beam has at least one of
the arrival direction differing more than a first threshold value from the arrival direction of the serving beam or an arrival antenna panel different from the antenna panel of the serving beam, or
the required transmission power for the random access channel preamble below a second threshold value.
15 . The method according to claim 14 , comprising
selecting, in response to receiving no acknowledgement to the random access channel preamble sent on said selected first candidate beam, a second candidate beam among said candidate beams such that the second candidate beam has the arrival direction differing more than a first threshold value from the arrival direction of the selected first candidate beam or an arrival antenna panel different from the antenna panel of the selected first candidate beam.
16 . The method according to claim 12 , comprising
spatially grouping the plurality of beams into two or more groups based on the arrival direction or the arrival antenna panel of the beams; and
selecting, in response to detecting a failure of the serving beam, a candidate beam from a group different from a group including at least one of the serving beam or a previously selected candidate beam.
17 . A non-transitory program storage device readable by an apparatus, tangibly embodying a program of instructions executable with the apparatus for performing operations, the operations comprising:
receiving reference signals comprising at least one of a plurality of channel synchronization signal blocks or state information reference signals on a downlink channel;
measuring at least one of received signal power or quality level of said reference signals;
estimating arrival directions or an arrival antenna panel for a plurality of beams associated with said reference signals;
estimating, based on at least one of the received signal power or quality level, a required transmission power for a random access channel preamble for the beam;
selecting, in response to detecting a failure of a serving beam, another of said beams according to at least one of spatial diversity or required transmission power;
sending the random access channel preamble on the selected beam; and
rank at least one beam of the plurality of beams into a preference order based on at least the arrival direction or the arrival antenna panel of the ranked beams and the required transmission power for the random access channel preamble of the ranked beams.