Cell handover in a radio cellular system

Abstract

When user equipment (UE) is to be handed over, the network and/or the UE determines a best beam for the UE's interactions with the target cell before the handover is completed. One or more additional next best beams may also be determined. The network (e.g., the target cell) allocates one or more uplink (UL) grants that corresponds to the best beam. Via a current cell, the UE receives the one or more UL grants from the network pertaining to communications between the UE and the target cell. The UE determines whether any beams of the one or more UL grants satisfy beam criteria. The beam criteria may include 1) an allocated beam being the current best beam or 2) an allocated beam being within a strength threshold of the current best beam. If the criteria is not satisfied, the UE initiates another handover type (e.g., a RACH-based handover).

What is claimed is: 
     
         1 . An electronic device, comprising:
 a network interface configured to interface with a cellular network;   a memory storing instructions; and   a processor configured to execute the instructions, wherein, when the instructions are executed, are configured to cause the processor to
 receive, from user equipment, an indication that the user equipment is to be handed over from a current cell to a target cell, 
 receive, from the user equipment, a measurement report associated with the target cell to which the user equipment is to be handed over, the measurement report comprising a measurement of a plurality of beams of the target cell, 
 determine a beam of the plurality of beams of the target cell of the cellular network, and 
 send, based on the measurement report, an uplink (UL) grant corresponding to the beam to the user equipment, wherein the UL grant is sent as part of a handover from the current cell to the target cell. 
   
     
     
         2 . The electronic device of  claim 1 , wherein sending the UL grant corresponding to a granted best beam to the user equipment causes the electronic device or another node of the cellular network to:
 perform the handover from the current cell to the target cell without using a random access channel (RACH) procedure; and   in response to a determination that the granted best beam does not satisfy a criteria for a best beam of the target cell, performing a RACH-based handover to update the target cell best beam for communications between the user equipment and the target cell.   
     
     
         3 . The electronic device of  claim 2 , wherein, when no new best beam exists, the instructions are configured to cause the electronic device to cause the user equipment to continue using the granted best beam to communicate with the target cell when the criteria has been satisfied by the granted best beam, wherein the granted best beam is a current best beam. 
     
     
         4 . The electronic device of  claim 1 , wherein the indication comprises a strength-of-signal for communications between the user equipment and the current cell falling beneath a strength-of-signal threshold. 
     
     
         5 . The electronic device of  claim 1 , wherein the indication comprises a likelihood that a strength-of-signal for communications between the user equipment and the target cell will exceed a strength-of-signal threshold. 
     
     
         6 . The electronic device of  claim 5 , wherein the likelihood that the strength-of-signal for communications between the user equipment and the target cell will exceed the strength-of-signal threshold is determined based on a location of the user equipment in relation to the electronic device. 
     
     
         7 . The electronic device of  claim 1 , wherein the measurement report associated with the target cell is based on a synchronization signal block used to estimate channel quality and report channel quality information. 
     
     
         8 . The electronic device of  claim 1 , wherein the measurement report associated with the target cell is based on channel state information reference signals that are used to estimate channel quality and report channel quality information. 
     
     
         9 . The electronic device of  claim 1 , wherein the cellular network comprises a 5 th  Generation New Radio FR2 network. 
     
     
         10 . The electronic device of  claim 1 , wherein the cellular network comprises a frequency range of 7 gigahertz to 24 gigahertz. 
     
     
         11 . A method, comprising:
 receiving, at a target cell base station, an indication that user equipment is to be handed over from a current cell to a target cell of a cellular network;   receiving, from a current cell base station and at the target cell base station, a measurement report associated with the target cell to which the user equipment is to be handed over, the measurement report comprising a measurement of a plurality of beams of the target cell;   determining a best beam of the plurality of beams for communications between the user equipment and the target cell;   allocating a plurality of uplink grants, wherein the plurality of uplink grants correspond to the best beam and one or more next best beams; and   sending the plurality of uplink grants to be sent to the user equipment via the current cell.   
     
     
         12 . The method of  claim 11 , wherein sending the plurality of uplink grants corresponding to a granted best beam to the user equipment causes the target cell base station, the current cell base station, or another node of the cellular network to:
 perform a handover to the target cell using the best beam without using a random access channel (RACH) procedure; and   in response to a determination that the granted best beam does not satisfy a criteria for a best beam of the target cell, perform a RACH-based handover to update the target cell best beam for the communications between the user equipment and the target cell.   
     
     
         13 . The method of  claim 12 , comprising, after the handover, receiving a measurement of the target cell to obtain a post-handover target cell best beam. 
     
     
         14 . The method of  claim 12 , comprising determining the granted best beam based at least in part on measurements of the current cell. 
     
     
         15 . The method of  claim 14 , wherein the measurements of the current cell are based at least in part on a synchronization signal block. 
     
     
         16 . The method of  claim 12 , wherein the measurement of the current cell are based at least in part on a wherein the measurements of the current cell are based at least in part on channel state information reference signals. 
     
     
         17 . The method of  claim 11 , wherein the cellular network comprises a 5 th  Generation New Radio FR2 network. 
     
     
         18 . Tangible, non-transitory, and computer-readable medium having stored thereon instructions, that when executed, are configured to cause one or more processors to:
 receive an indication that user equipment (UE) is to be handed over from a current cell to a target cell of a cellular network;   before completing a handover, determine a best beam for communications between the UE and the target cell;   allocate a plurality of uplink (UL) grants, the UL grants corresponding to the best beam and one or more next best beams; and   cause the plurality of UL grants to be sent to the UE via the current cell.   
     
     
         19 . The tangible, non-transitory, and computer-readable medium of  claim 18 , wherein sending the UL grant corresponding to the best beam to the user equipment causes a base station of the cellular network to:
 perform the handover from the current cell to the target cell without using a random access channel (RACH) procedure; and   in response to a determination that the granted best beam does not satisfy a criteria for a best beam of the target cell, initiate a RACH-based handover to update the target cell best beam for the communications between the user equipment and the target cell.   
     
     
         20 . The tangible, non-transitory, and computer-readable medium of  claim 19 , wherein the instructions, when executed, are configured to cause the one or more processors to cause a base station of the cellular network to cause the user equipment to continue using the granted best beam to communicate with the target cell when the criteria has been satisfied by the granted best beam, wherein the granted best beam is a current best beam.