Embodiments herein relate to for example a method performed by a radio network node for handling a communication of a user equipment, UE, in a wireless communication network. The radio network node transmits a handover command for handing over the UE, from a source cell to a target cell, wherein a security parameter for encrypting data communicated between the radio network node and the UE is retained during the handover. Furthermore, the radio network node maintains a sequence number status for reception and/or transmission of a signalling radio bearer of the UE during the handover from the source cell to the target cell, and/or at a fallback from the target cell to the source cell, when the UE triggers the fallback to the source cell.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a source master eNodeB (MeNB) may transmit, to a target Next Generation radio access network (NG-RAN) node, a handover required message to initiate an inter-system handover from an evolved-Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN) New Radio (NR) dual connectivity (EN-DC) system associated with the source MeNB to an NR standalone (SA) system associated with the target NG-RAN node. The source MeNB may have an indirect path to the target NG-RAN node and a source secondary gNodeB (SgNB) may have a direct path to the target NG-RAN node. The source MeNB may transmit, to the target NG-RAN node and based at least in part on the handover required message, forwarded data via the indirect path between the source MeNB and the target NG-RAN node through a core network. Numerous other aspects are described.

Systems, methods, apparatuses, and computer program products for mobility failure evidence-related operations. A UE may measure, record, and report a channel access waiting (CAW) time period that elapsed from having a handover-related message in a transmission buffer until a channel for transmission of the handover-related message was obtained or until an acknowledgement or negative acknowledgement from a receiver of the handover-related message was received. The CAW time period information may be provided to a network node, and the network node may control mobility robustness optimization based on the received information.

A more efficient network can be achieved by leveraging an adaptive dejitter buffer. The dejitter buffer can be dynamically adjusted based off a network data analysis. A communication handover can be adjusted or shifted based on voice inactivity data related to a forecasted punctuation. The dejitter buffer memory/depth of a mobile device can also be adjusted in accordance with receiving a delay interruption length associated with another mobile device. Thereafter, the dejitter buffer memory can be filled with voice packet data to decrease a packet delay variation at the mobile device.

A system is proposed to provide handover in a mobile telecommunications environment, particularly applicable to 3GPP networks, which does not increase signalling overhead but minimises user data loss during handover. In the modified system, PDCP SDUs with Sequence numbers are buffered and retransmitted as necessary. At the time of handover, SDUs not received by the user device are forwarded to the target base station for forward transmission to the UE. The handover procedure is designed to minimise packet loss whilst keeping to a minimum the duplication of packet transmission over the air interface.

A data transmission method and apparatus are disclosed. The method includes: determining, by a source base station of a terminal in a handover process, first data and a radio air interface protocol sequence number of a data unit used to carry the first data, where the first data includes data that is not acknowledged by a terminal for correct reception during data transmission between the source base station and the terminal. The method further includes sending, by the source base station, the first data and the radio air interface protocol sequence number to a target base station; where the core network connected to the target base station is different from the core network connected to the source base station.

The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. According to an aspect of the embodiments of the present disclosure, a method for supporting handover is provided, comprising: receiving a message from a central unit control plane entity of a target base station; receiving a data packet from a source base station; and discarding a packet data convergence protocol (PDCP) service data unit (SDU) including the PDCP sequence number (SN) in the received data packet according to the indication of the message.

A method, apparatus, and a computer-readable storage medium are provided for forwarding of buffered user data at a target node to a re-establishment node. In an example implementation, the method may include receiving, by a first network node, a handover cancel or an Xn-User plane address indication message from a second network node, the handover cancel or the Xn-User plane address indication message including tunnel addresses for one or more data radio bearers; and forwarding, by the first network node, buffered downlink packets to a third network node or the second network node, the forwarding based at least on the tunnel addresses. In an additional example implementation, the method may include sending, by a third network node, tunnel addresses for one or more data radio bearers to a second network node upon re-establishing of a radio resource control connection; and receiving, by the third network node, buffered packets at the first network node from a second network node or the first network node. In an additional example implementation, the method may include initiating, by a user equipment, a radio resource control re-establishment procedure with a third network node, the re-establishment procedure is initiated upon a handover failure of the user equipment from a second network node to a first network node; and receiving, by user equipment, buffered packets at the first node from a third network node.

Embodiments include methods for an integrated access backhaul (IAB) node in a wireless network to migrate from a first centralized unit (CU) to a second CU. Such methods include receiving a handover command from the first CU via a source parent IAB node. The handover command includes an identifier of a target cell for the handover. Such methods include determining that the handover command is for an inter-CU migration of the IAB node to the second CU and, based on determining that the handover command is for an inter-CU migration, performing modified handling of uplink and/or downlink data buffered at the IAB node until execution of the handover command. Embodiments also include complementary methods for handling migration of a child IAB node from a first CU to a second CU, as well as IAB nodes configured to perform such methods. FIG. 17 is selected for publication.

The present application relates to devices and components including apparatus, systems, and methods for integrated access and backhaul radio link failure and handover scenarios in wireless communication systems.