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US 11,445,549 B2Granted
Two-step random access channel (RACH) procedure to four-step RACH procedure fallback
AssigneeQUALCOMM Incorporated
InventorsSrinivas Yerramalli, Xiaoxia Zhang, Jing Sun, Seyed Ali Akbar Fakoorian, Ozcan Ozturk, Tao Luo
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Abstract
Certain aspects of the present disclosure provide techniques for random-access channel (RACH) communication. For example, certain aspects provide a method for falling back from a 2-step RACH procedure to a 4-step RACH procedure.
Claims23
A method for wireless communications by a user equipment (UE), comprising:
- receiving remaining minimum system information (RMSI) configuring the UE with one or more parameters to support selecting between a two-step random access channel (RACH) procedure and a four-step RACH procedure, wherein the one or more parameters include at least a first reference signal receive power (RSRP) threshold for the two-step RACH procedure and a second RSRP threshold for the four-step RACH procedure different from the first RSRP threshold;
- initiating, based on the first RSRP threshold, the two-step random access channel (RACH) procedure including sending a first message to a base station, the first message comprising at least a preamble portion, including a RACH preamble, and a payload portion, including a payload, wherein sending the first message includes applying a power offset to the payload portion of the first message;
- receiving a random access response (RAR) message from the base station, wherein the RAR message indicates successful reception, by the base station, of both the RACH preamble and the payload when the response message is of a first format;
- and
- transitioning to the four-step RACH procedure before successful completion of the two-step RACH procedure when the RAR message is of a second format.
2 more elements
A method for wireless communications by a network entity, comprising:
- transmitting remaining minimum system information (RMSI) configuring a user equipment (UE) with one or more parameters to support transitioning from a two-step random access channel (RACH) procedure to a four-step RACH procedure, wherein the one or more parameters include at least a first reference signal receive power (RSRP) threshold for the two-step RACH procedure and a second RSRP threshold for the four-step RACH procedure different from the first RSRP threshold;
- receiving, based on the first RSRP threshold, a first message from a user equipment (UE) as part of a two-step RACH procedure, the first message comprising at least a random access channel (RACH) preamble;
- and
- sending a random access response (RAR) message to the UE, wherein a first format of the RAR message indicates successful reception of both the RACH preamble and a payload included in a payload portion of the first message and a second format of the RAR message signals the UE to transition to a four-step RACH procedure before successful completion of the two-step RACH procedure, wherein a power offset is applied to the payload portion of the first message.
1 more element
An apparatus for wireless communications by a user equipment (UE), comprising:
- means for receiving remaining minimum system information (RMSI) configuring the UE with one or more parameters to support transitioning from a two-step random access channel (RACH) procedure to a four-step RACH procedure, wherein the one or more parameters include at least a first reference signal receive power (RSRP) threshold for the two-step RACH procedure and a second RSRP threshold for the four-step RACH procedure different from the first RSRP threshold;
- means for initiating, based on the first RSRP threshold, a two-step random access channel (RACH) procedure including sending a first message to a base station, the first message comprising at least a preamble portion, including a RACH preamble, and a payload portion, including a payload, wherein the means for initiating comprise means for applying a power offset to the payload portion of the first message of the two-step RACH procedure;
- means for receiving a random access response (RAR) message from the base station, wherein the RAR message indicates successful reception, by the base station, of both the RACH preamble and the payload when the response message is of a first format;
- and
- means for transitioning to a four-step RACH procedure before successful completion of the two-step RACH procedure when the RAR message is of a second format.
2 more elements
An apparatus for wireless communications by a network entity, comprising:
- means for transmitting remaining minimum system information (RMSI) configuring a user equipment (UE) with one or more parameters to support selecting between a two-step random access channel (RACH) procedure and a four-step RACH procedure, wherein the one or more parameters include at least a first reference signal receive power (RSRP) threshold for the two-step RACH procedure and a second RSRP threshold for the four-step RACH procedure different from the first RSRP threshold;
- means for receiving, based on the first RSRP threshold, a first message from a user equipment (UE) as part of a two-step RACH procedure, the first message comprising at least a random access channel (RACH) preamble;
- and
- means for sending a random access response (RAR) message to the UE, wherein a first format of the RAR message indicates successful reception of both the RACH preamble and a payload included in a payload portion of the first message and a second format of the RAR message signals the UE to transition to a four-step RACH procedure before successful completion of the two-step RACH procedure, wherein a power offset is applied to the payload portion of the first message.
1 more element
A non-transitory computer readable medium for wireless communication, comprising:
- instructions that, when executed by at least one processor, cause the at least one processor to:
- receive remaining minimum system information (RMSI) configuring a UE with one or more parameters to support selecting between a two-step random access channel (RACH) procedure and a four-step RACH procedure, wherein the one or more parameters include at least a first reference signal receive power (RSRP) threshold for the two-step RACH procedure and a second RSRP threshold for the four-step RACH procedure different from the first RSRP threshold;
- initiate, based on the first RSRP threshold, a two-step random access channel (RACH) procedure including sending a first message to a base station, the first message comprising at least a preamble portion, including a RACH preamble, and a payload portion, including a payload, wherein sending the first message includes applying a power offset to the payload portion of the first message;
- receive a random access response (RAR) message from the base station, wherein the RAR message indicates successful reception, by the base station, of both the RACH preamble and the payload when the response message is of a first format;
- and
- transition to a four-step RACH procedure before successful completion of the two-step RACH procedure when the RAR message is of a second format.
3 more elements
A non-transitory computer readable medium for wireless communication, comprising:
- instructions that, when executed by at least one processor, cause the at least one processor to:
- transmit remaining minimum system information (RMSI) configuring a user equipment (UE) with one or more parameters to support selecting between a two-step random access channel (RACH) procedure and a four-step RACH procedure, wherein the one or more parameters include at least a first reference signal receive power (RSRP) threshold for the two-step RACH procedure and a second RSRP threshold for the four-step RACH procedure different from the first RSRP threshold;
- receive, based on the first RSRP threshold, a first message from a user equipment (UE) as part of a two-step RACH procedure, the first message comprising at least a random access channel (RACH) preamble;
- and
- send a random access response (RAR) message to the UE, wherein a first format of the RAR message indicates successful reception of both the RACH preamble and a payload included in a payload portion of the first message and a second format of the RAR message signals the UE to transition to a four-step RACH procedure before successful completion of the two-step RACH procedure, wherein a power offset is applied to the payload portion of the first message.
2 more elements
Dependencies are inferred from the claim text.