Method and apparatus for performing random access procedure for beam failure recovery

Patent metadata

Field	Value
Publication number	US-2021126698-A1
Application number	US-202017073995-A
Country	US
Kind code	A1
Filing date	Oct 19, 2020
Priority date	Oct 25, 2019
Publication date	Apr 29, 2021
Grant date	—

Abstract

A method performed by a User Equipment (UE) for Beam Failure Recovery (BFR) is provided. The method includes the UE detecting a beam failure event on a serving cell, and initiating a Random Access (RA) procedure for BFR on a Bandwidth Part (BWP) of the serving cell. The RA procedure for BFR includes performing an RA type selection after determining that the UE is not configured with any Contention-Free RA (CFRA) resource for BFR, the RA type selection including determining a 2-step RA type or a 4-step RA type as an RA type of the RA procedure for BFR based on a Reference Signal Received Power (RSRP) value of a Downlink (DL) pathloss reference, skipping performing the RA type selection after determining that the UE is configured with a CFRA resource for BFR, and determining the RA type as the 4-step RA type after skipping the RA type selection.

First claim

What is claimed is:

1 . A method performed by a User Equipment (UE) for Beam Failure Recovery (BFR), the method comprising:
detecting a beam failure event on a serving cell; and initiating a Random Access (RA) procedure for BFR on a Bandwidth Part (BWP) of the serving cell, the RA procedure for BFR including: performing an RA type selection after determining that the UE is not configured with any Contention-Free RA (CFRA) resource for BFR, the RA type selection including determining one of a 2-step RA type and a 4-step RA type as an RA type of the RA procedure for BFR based on a Reference Signal Received Power (RSRP) value of a Downlink (DL) pathloss reference; skipping performing the RA type selection after determining that the UE is configured with a CFRA resource for BFR; and determining the RA type as the 4-step RA type after skipping performing the RA type selection.

2 . The method of claim 1 , further comprising:
determining the RA type as the 2-step RA type in the RA type selection in a case that the BWP is not configured with any 4-step RA type RA resource and is configured with at least one 2-step RA type RA resource.

3 . The method of claim 1 , further comprising:
determining the RA type as the 2-step RA type in the RA type selection in a case that the RSRP value is larger than a threshold, the threshold configured by a 2-step RA configuration.

4 . The method of claim 1 , wherein the CFRA resource for BFR is a 4-step RA type RA resource.

5 . The method of claim 1 , wherein the UE is not configured with any CFRA resource for BFR, and the RA procedure for BFR further includes:
transmitting an RA preamble via a Contention-Based RA (CBRA) resource after performing the RA type selection.

6 . The method of claim 1 , wherein the UE is configured with the CFRA resource for BFR, and the RA procedure for BFR further includes:
transmitting an RA preamble via one of a Contention-Based RA (CBRA) resource and the CFRA resource after skipping performing the RA type selection.

7 . The method of claim 1 , wherein the UE is not allowed to select the 2-step RA type as the RA type of the RA procedure in a case that the UE skips performing the RA type selection.

8 . The method of claim 1 , wherein the RA procedure for BFR further includes:
selecting a carrier before performing the RA type selection, the carrier being a Normal Uplink (NUL) or a Supplementary UL (SUL).

9 . The method of claim 1 , wherein the RA type selection is performed in an initialization phase of the RA procedure for BFR.

10 . The method of claim 1 , wherein the serving cell is a Special Cell (SpCell).

11 . A User Equipment (UE) for Beam Failure Recovery (BFR), the UE comprising:
a memory; and at least one processor coupled to the memory, the at least one processor being configured to: detect a beam failure event on a serving cell; and initiate a Random Access (RA) procedure for BFR on a Bandwidth Part (BWP) of the serving cell, the RA procedure for BFR including:
performing an RA type selection after determining that the UE is not configured with any Contention-Free RA (CFRA) resource for BFR, the RA type selection including determining one of a 2-step RA type and a 4-step RA type as an RA type of the RA procedure for BFR based on a Reference Signal Received Power (RSRP) value of a Downlink (DL) pathloss reference;
skipping performing the RA type selection after determining that the UE is configured with a CFRA resource for BFR; and
determining the RA type as the 4-step RA type after skipping performing the RA type selection.

12 . The UE of claim 11 , wherein the at least one processor is further configured to:
determine the RA type as the 2-step RA type in the RA type selection in a case that the BWP is not configured with any 4-step RA type RA resource and is configured with at least one 2-step RA type RA resource.

13 . The UE of claim 11 , wherein the at least one processor is further configured to:
determine the RA type as the 2-step RA type in the RA type selection in a case that the RSRP value is larger than a threshold, the threshold configured by a 2-step RA configuration.

14 . The UE of claim 11 , wherein the CFRA resource for BFR is a 4-step RA type RA resource.

15 . The UE of claim 11 , wherein the UE is not configured with any CFRA resource for BFR, and the at least one processor is further configured to:
transmit an RA preamble via a Contention-Based RA (CBRA) resource after performing the RA type selection.

16 . The UE of claim 11 , wherein the UE is configured with the CFRA resource for BFR, and the at least one processor is further configured to:
transmit an RA preamble via one of a Contention-Based RA (CBRA) resource and the CFRA resource after skipping performing the RA type selection.

17 . The UE of claim 11 , wherein the UE is not allowed to select the 2-step RA type as the RA type of the RA procedure in a case that the UE skips performing the RA type selection.

18 . The UE of claim 11 , wherein the at least one processor is further configured to:
select a carrier before performing the RA type selection, the carrier being a Normal Uplink (NUL) or a Supplementary UL (SUL).

19 . The UE of claim 11 , wherein the RA type selection is performed in an initialization phase of the RA procedure for BFR.

20 . The UE of claim 11 , wherein the serving cell is a Special Cell (SpCell).

Assignees

• Fg innovation co ltd

Inventors

• Tsai Hsin-Hsi

Classifications

• H04B17/328

  Reference signal received power [RSRP]; Reference signal received quality [RSRQ] · CPC title

• H04B7/06964

  Re-selection of one or more beams after beam failure · CPC title

• H04W74/0836

  with 2-step access · CPC title

• H04W74/0838

  using contention-free random access [CFRA] · CPC title

• H04W74/0833 Primary

  Random access procedures, e.g. with 4-step access · CPC title