Electronic device and method for beam failure recovery
Aspects of the disclosure provide an electronic device including processing circuitry and a method for beam failure recovery. The processing circuitry can determine whether beam failure occurs on at least one of a plurality of cells configured for serving an electronic device. When the beam failure is determined to occur on the at least one of the plurality of cells, the processing circuitry can send an uplink message that includes a first portion and a second portion to a network. The first portion indicating the beam failure is transmitted using a physical random access channel (PRACH) resource. The second portion indicates at least one of cell information of the at least one of the plurality of cells and new beam information of one or more new candidate beams for the at least one of the plurality of cells and is transmitted using a physical uplink shared channel (PUSCH) resource.
1. A method for beam failure recovery (BFR), comprising:
determining whether beam failure occurs on at least one of a plurality of cells configured for serving an electronic device; and
when the beam failure is determined to occur on the at least one of the plurality of cells, performing a 2-step random access procedure for BFR having a first step and a second step by
sending, in the first step, an uplink (UL) message that includes a first portion and a second portion to a network, and
receiving, in the second step, a downlink (DL) message from the network, the DL message indicating a BFR response, wherein
a first portion of the UL message indicates the beam failure and is transmitted using a physical random access channel (PRACH) resource, and
a second portion of the UL message indicates at least one of 1) cell information of the at least one of the plurality of cells and 2) new beam information of one or more new candidate beams for the at least one of the plurality of cells, and the second portion is transmitted using a physical uplink shared channel (PUSCH) resource.
2. The method according to claim 1 , wherein
the second portion includes a BFR request (BFRQ) medium access control (MAC) control element (CE); and
sending the UL message includes:
sending the first portion using a PRACH preamble on the PRACH resource; and
sending the BFRQ MAC CE on the PUSCH resource.
3. The method according to claim 2 , wherein
the cell information includes at least one cell index corresponding to the at least one of the plurality of cells;
the new beam information includes at least one new beam index of the one or more new candidate beams; and
the at least one of the plurality of cells includes an secondary cell (SCell), a primary secondary cell (PSCell), and/or a primary cell (PCell).
4. The method according to claim 2 , further comprising:
randomly selecting the PRACH resource from a set of unreserved PRACH resources for the electronic device, the PUSCH resource being associated with the PRACH resource and unreserved, wherein
the 2-step random access procedure is a contention-based (CB) random access (CBRA) procedure.
5. The method according to claim 4 , wherein
the UL message includes one or more data portions to be sent using the PUSCH resource;
the method includes determining a transmission order for the BFRQ MAC CE and the one or more data portions based on a priority rule for the UL message; and
sending the BFRQ MAC CE includes sending the BFRQ MAC CE using the PUSCH resource based on the transmission order.
6. The method according to claim 4 , wherein
the second portion includes another BFRQ MAC CE; and
the method further includes sending the other BFRQ MAC CE on the PUSCH.
7. The method according to claim 4 , wherein
the cell information includes at least one cell index corresponding to the at least one of the plurality of cells;
the new beam information includes at least one new beam index for the at least one of the plurality of cells; and
the BFRQ MAC CE further includes a device identification (ID) for the electronic device.
8. The method according to claim 2 , further comprising:
receiving, from the network, a signal indicating the PRACH resource that is reserved for the electronic device, the PUSCH resource being associated with the PRACH resource and being reserved.
9. The method according to claim 2 , wherein
the at least one of the plurality of cells includes multiple secondary cells (SCells) that share the PRACH resource and the PUSCH resource.
10. An apparatus for beam failure recovery (BFR), comprising:
processing circuitry configured to:
determine whether beam failure occurs on at least one of a plurality of cells configured for serving an electronic device; and
when the beam failure is determined to occur on the at least one of the plurality of cells, perform a 2-step random access procedure for BFR having a first step and a second step by
sending, in the first step, an uplink (UL) message that includes a first portion and a second portion to a network, and
receiving, in the second step, a downlink (DL) message from the network, the DL message indicating a BFR response, wherein
a first portion of the UL message indicates the beam failure and is transmitted using a physical random access channel (PRACH) resource, and
a second portion of the UL message indicates at least one of 1) cell information of the at least one of the plurality of cells and 2) new beam information of one or more new candidate beams for the at least one of the plurality of cells, and the second portion is transmitted using a physical uplink shared channel (PUSCH) resource.
11. The apparatus according to claim 10 , wherein
the second portion includes a BFR request (BFRQ) medium access control (MAC) control element (CE); and
the processing circuitry is configured to:
send the first portion using a PRACH preamble on the PRACH resource; and
send the BFRQ MAC CE on the PUSCH resource.
12. The apparatus according to claim 11 , wherein
the cell information includes at least one cell index corresponding to the at least one of the plurality of cells;
the new beam information includes at least one new beam index of the one or more new candidate beams; and
the at least one of the plurality of cells includes an secondary cell (SCell), a primary secondary cell (PSCell), and/or a primary cell (PCell).
13. The apparatus according to claim 11 , wherein
the 2-step random access procedure is a contention-based (CB) random access (CBRA) procedure; and
the processing circuitry is configured to:
randomly select the PRACH resource from a set of unreserved PRACH resources for the electronic device, the PUSCH resource being associated with the PRACH resource and unreserved.
14. The apparatus according to claim 13 , wherein
the UL message includes one or more data portions to be sent using the PUSCH resource; and
the processing circuitry is configured to:
determine a transmission order for the BFRQ MAC CE and the one or more data portions based on a priority rule for the UL message; and
send the BFRQ MAC CE using the PUSCH resource based on the transmission order.
15. The apparatus according to claim 13 , wherein
the second portion includes another BFRQ MAC CE; and
the processing circuitry is configured to send the other BFRQ MAC CE on the PUSCH.
16. The apparatus according to claim 13 , wherein
the cell information includes at least one cell index corresponding to the at least one of the plurality of cells;
the new beam information includes at least one new beam index for the at least one of the plurality of cells; and
the BFRQ MAC CE further includes a device identification (ID) for the electronic device.
17. The apparatus according to claim 11 , wherein the processing circuitry is configured to:
receive, from the network, a signal indicating the PRACH resource that is reserved for the electronic device, the PUSCH resource being associated with the PRACH resource and being reserved.
18. The apparatus according to claim 11 , wherein
the at least one of the plurality of cells includes multiple secondary cells (SCells) that share the PRACH resource and the PUSCH resource.