US 12,133,065 B2
Apparatus, method and computer program for handover
Jedrzej Stanczak, Wroclaw (PL); Tero Henttonen, Espoo (FI); and Ahmad Awada, Munich (DE)
Assigned to NOKIA TECHNOLOGIES OY, Espoo (FI)
Appl. No. 17/621,771
Filed by Nokia Technologies Oy, Espoo (FI)
PCT Filed Jul. 30, 2019, PCT No. PCT/FI2019/050571
§ 371(c)(1), (2) Date Dec. 22, 2021,
PCT Pub. No. WO2021/019125, PCT Pub. Date Feb. 4, 2021.
Prior Publication US 2022/0361062 A1, Nov. 10, 2022
Int. Cl. H04W 36/00 (2009.01)
CPC H04W 36/0058 (2018.08) [H04W 36/00725 (2023.05); H04W 36/0077 (2013.01)] 1 Claim
OG exemplary drawing
 
1. An apparatus, comprising at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to:
receive a handover command from a first cell, the handover command comprising an uplink resource grant of a number of uplink resources grants and a condition to be met before handover is performed to a second cell, wherein the uplink resource grant indicates a set of uplink resources for uplink data transmission in the second cell without random access, wherein the first cell is a source cell, and wherein the second cell is a target cell of a handover procedure;
determine validity of the uplink resource grant based on further configuration parameters, the further configuration parameters comprising a timer, an indication of a time resource number, and a threshold for signal strength and signal quality of a reference signal associated with the set of uplink resources,
wherein the reference signal is a Channel State Information-Reference Signal (CSI-RS),
wherein determining validity of the uplink resource grant further includes in a case where it is determined that the uplink resource grant is invalid in response to expiry of the timer and the indicated time resource number being reached, and in response to the condition being met, perform a random access based handover to the second cell based on the invalidity of the uplink resource grant;
reduce the number of uplink resource grants that are valid at a specific radio frame, subframe, or slot number;
receive the further configuration parameter in the handover command or an additional message from the first cell;
detect signal strength and signal quality for a reference signal associated with an uplink resource other than those indicated in the uplink resource grant;
provide a measurement report to the first cell, in response to the detected signal strength and signal quality exceeding a reference level, wherein the reference level is defined based on a signal strength and signal quality for a reference signal associated with the uplink resource grant;
provide an indication to the first cell if the signal strength and signal quality of the reference signal is below the threshold, or discard at least a subset of the set of uplink resources in response to at least one of expiry of the timer or the indicated time resource number being reached;
determine which subset of the set of uplink resources to discard based on whether the reference signal associated with the uplink resource is below the threshold;
provide an indication to the first cell that the subset of the set of uplink resources has been discarded;
receive an updated uplink resource grant from the first cell in response to the indication that the signal strength and signal quality of the reference signal is below the threshold; and
in response to the condition being met, perform the handover based on the validity of the updated uplink resource grant.