Fast user equipment handover between base stations

Abstract

This disclosure provides systems, methods, and apparatus for wireless communications that support fast user equipment (UE) handover between base stations. A UE may receive, from a source base station, a configuration for reference signal transmission at a set of uplink transmit power levels. The UE may transmit multiple uplink reference signal repetitions based on the configuration. The source base station may transmit a request message to a target base station to measure the multiple uplink reference signal repetitions. The target base station may select an uplink reference signal and measure a transmit power correction. The target base station may transmit an indication to the source base station of the selection and transmit power correction. The source base station may evaluate the indications and select the target base station. The source base station may forward to the indicated contents, and the UE may switch and synchronize with the target base station.

What is claimed is: 
     
         1 . (canceled) 
     
     
         2 . A user equipment (UE), comprising:
 a transceiver;   one or more processors; and   one or more memories coupled with the one or more processors and storing processor-executable code that, when executed by the one or more processors, is configured to cause the UE to:
 receive, via the transceiver, an indication of a set of uplink transmit power levels and a set of time-frequency resources; 
 transmit, via the transceiver and using the set of time-frequency resources, a plurality of uplink reference signals, said transmission being performed in accordance with the set of uplink transmit power levels; and 
 receive, via the transceiver, an instruction to perform a handover from a first network entity to a second network entity, the instruction indicating a power parameter that is based at least in part on an uplink reference signal of the plurality of uplink reference signals. 
   
     
     
         3 . The UE of  claim 2 , wherein the processor-executable code is further configured to cause the UE to:
 transmit, via the transceiver, a measurement report based at least in part on a measurement event, wherein the set of uplink transmit power levels is based at least in part on the measurement report.   
     
     
         4 . The UE of  claim 2 , wherein the processor-executable code is further configured to cause the UE to:
 receive, via the transceiver, an indication that the second network entity is a handover target for the UE based at least in part on the plurality of uplink reference signals.   
     
     
         5 . The UE of  claim 2 , wherein the power parameter comprises a power correction value. 
     
     
         6 . The UE of  claim 2 , wherein the instruction further comprises at least one of a timing advance value or an uplink grant. 
     
     
         7 . The UE of  claim 2 , wherein the plurality of uplink reference signals comprise sounding reference signal repetitions. 
     
     
         8 . The UE of  claim 2 , wherein the processor-executable code is further configured to cause the UE to:
 communicate, via the transceiver and using an uplink transmit power, with the second network entity, wherein the uplink transmit power is based at least in part on the power parameter indicated by the instruction.   
     
     
         9 . The UE of  claim 8 , wherein, to communicate with the second network entity, the processor-executable code is further configured to cause the UE to:
 transmit, via the transceiver and using the uplink transmit power, a handover complete message to the second network entity.   
     
     
         10 . The UE of  claim 8 , wherein the processor-executable code is further configured to cause the UE to:
 transmit, via the transceiver and using the uplink transmit power, a first random access message of a random access procedure.   
     
     
         11 . The UE of  claim 10 , wherein the processor-executable code is further configured to cause the UE to:
 transmit, via the transceiver and using a second uplink transmit power, a second random access message of the random access procedure, said second uplink transmit power being higher than the uplink transmit power, the second random access message comprising a retransmission of the first random access message.   
     
     
         12 . The UE of  claim 2 , wherein the processor-executable code is further configured to cause the UE to:
 perform the handover from the first network entity to the second network entity in accordance with the instruction and based at least in part on the power parameter.   
     
     
         13 . The UE of  claim 2 , wherein the processor-executable code is further configured to cause the UE to:
 transmit, via the transceiver using the power parameter, one or more signals to the second network entity, said transmission being part of the handover from the first network entity to the second network entity.   
     
     
         14 . A method for wireless communication at a user equipment (UE), comprising:
 receiving an indication of a set of uplink transmit power levels and a set of time-frequency resources;   transmitting, via the set of time-frequency resources, a plurality of uplink reference signals, said transmission being performed in accordance with the set of uplink transmit power levels; and   receiving an instruction to perform a handover from a first network entity to a second network entity, the instruction indicating a power parameter that is based at least in part on an uplink reference signal of the plurality of uplink reference signals.   
     
     
         15 . The method of  claim 14 , further comprising:
 transmitting a measurement report based at least in part on a measurement event, wherein the set of uplink transmit power levels is based at least in part on the measurement report.   
     
     
         16 . The method of  claim 14 , further comprising:
 receiving an indication that the second network entity is a handover target for the UE based at least in part on the plurality of uplink reference signals.   
     
     
         17 . The method of  claim 14 , wherein the power parameter comprises a power correction value. 
     
     
         18 . The method of  claim 14 , wherein the instruction further comprises at least one of a timing advance value or an uplink grant. 
     
     
         19 . The method of  claim 14 , wherein the plurality of uplink reference signals comprise sounding reference signal repetitions. 
     
     
         20 . The method of  claim 14 , further comprising:
 communicating, using an uplink transmit power, with the second network entity, wherein the uplink transmit power is based at least in part on the power parameter indicated by the instruction.   
     
     
         21 . An apparatus, comprising:
 means for receiving an indication of a set of uplink transmit power levels and a set of time-frequency resources;   means for transmitting, via the set of time-frequency resources, a plurality of uplink reference signals, said transmission being performed in accordance with the set of uplink transmit power levels; and   means for receiving an instruction to perform a handover from a first network entity to a second network entity, the instruction indicating a power parameter that is based at least in part on an uplink reference signal of the plurality of uplink reference signals.