Method for data dropping for time-critical communications during handover - Patents.com

Abstract

According to one aspect, a source network node configured to communicate with a wireless device (WD) and a target network node is described. The source network node is configured to obtain timing information associated with Packet Data Convergence Protocol (PDCP) resources. The PDCP resources correspond to packets scheduled for downlink transmission from the source network node or uplink transmission from the WD. The source network node is further configured to transmit the timing information associated with the PDCP resources to the target network node after a handover request is transmitted by the source network node, so that the target network node determines, based on the timing information, whether to discard the PDCP resources or packets or have the WD discard them.

Description

[Technical Field]

[0001] TECHNICAL FIELD The present disclosure relates to wireless communications, and more particularly to techniques for data dropping for time-sensitive communications during handover. [Background technology]

[0002] The 3rd Generation Partnership Project (3GPP) has developed and is developing standards for fourth-generation (4G) (also known as Long Term Evolution (LTE)) and fifth-generation (5G) (also known as New Radio (NR)) wireless communication systems. Such systems provide, among other features, broadband communication between network nodes (NNs), such as base stations, and mobile wireless devices (WDs), as well as communication between network nodes and between WDs. 3GPP is also developing standards for sixth-generation (6G) wireless communication networks.

[0003] XR services Extended reality (XR) is an important 5G media application currently being considered in the industry. XR is an umbrella term for different types of "reality" and can generally refer to any kind of combined real and virtual environment and human-machine interaction generated by computer technology and wearables. XR encompasses representative forms such as augmented reality (AR), mixed reality (MR), and virtual reality (VR), as well as the areas that interpolate between them.

[0004] Figure 1 is a graphical depiction of the challenges in balancing various attributes for XR with respect to reliability, latency constraints, and bitrate. -5Compared to Ultra-Reliable Low-Latency Communications (URLLC) type services, which come with stringent requirements for reliability, edge-based XR often has relaxed latency requirements, ranging from as little as 5ms to as many as tens of ms of latency, and as little as 10ms. -4 However, codec inefficiencies, for example, can require XR services to require much higher byte rates at larger file sizes of 10KB to 100KB.

[0005] Another traffic characteristic of XR is that it can be more dynamic, for example, due to gaze / viewport tracking. Traffic may appear periodic, but file sizes vary, as shown in the example timing diagram of Figure 2, which shows an example typical XR traffic profile.

[0006] When an application packet (which may be periodic but variable in size) enters the Internet, the initial packet may be transmitted within a single protocol data unit (PDU) in the network or may be segmented into several PDUs. This means that one application packet may correspond, for example, to one or several Internet Protocol (IP) packets. The IP packets reach the Radio Access Network (RAN) Packet Data Convergence Protocol (PDCP) layer, i.e., PDCP Service Data Units (SDUs), which then create PDCP PDUs and deliver them to lower layers. For each SDU, the PDCP layer starts a PDCP discard timer upon receiving the SDU from the upper layer. When this timer expires, PDCP discards the PDCP SDU and the corresponding PDCP data PDU. When the PDCP PDU is delivered to the lower layer, PDCP indicates discard to the lower layer. The lower layer, e.g., RLC, discards the PDCP PDU (RLC SDU) if these RLC SDUs or any segments of the RLC SDUs have not yet been transmitted to the lower layer.

[0007] XR application PDUs may have time constraints. One or a set of application PDUs may need to arrive at the receiver within a certain time period, i.e., with a limited latency. If the application PDUs are not received by this time, they will not be used and may be discarded. Another property is that when one application PDU that should have been delivered within a certain latency bound is delayed, the later application PDUs will no longer be needed, since they will depend on the earlier application PDUs for video decoding. In that case, the corresponding PDCP SDU / PDU should not be transmitted, as this would result in wasted resources.

[0008] For example, in an XR application service, there are several types of video frames. For example, an independent frame (I-frame) is a frame that a decoder can decode without the assistance of other previously received frames. On the other hand, for a B-frame or P-frame, decoding may depend on the successful reception of the independent frame and possibly other dependent frames, i.e., B-frames or P-frames.

[0009] The existing independent discard timers between PDCP SDUs may not be adequate to handle this particular situation of XR traffic, i.e., they allow longer residence of PDCP SDUs in the buffer even though this is no longer required from an application point of view. Example reasons for this include: An XR application may generate one or more application PDUs that must be delivered within a latency budget. The application or a layer below the application may segment / concatenate these application PDUs. PDCP receives IP PDUs (if IP is used) from higher layers, but PDCP has no knowledge of how to map these PDCP SDUs (IP PDUs) to application PDUs that need to be delivered within the same latency budget. · Existing PDCP discard timers for single PDCP SDUs may not be efficient enough to handle the situations outlined in the list items above.

[0010] URLLC and survival time In a 5G Quality of Service (QoS) framework, a QoS flow can be established in a 5G system and mapped to a Data Radio Bearer (DRB). The QoS flow is associated with a QoS parameter, i.e., a 5Q QoS indicator (5QI), such as a Packet Delay Budget (PDB). 5G RAN scheduling packets of this QoS flow (mapped to a DRB in the 5G RAN) can deliver packets within this PDB. Another metric related to the PDB and discussed in the context of industrial automation communications is the so-called survival time. According to 3GPP TS22.261v18.4.0 / TS22.104v18.2.0, for example, in some existing systems, survival time is defined as the time an application using a communication service can continue without an expected message. A message is expected at the end of the PDB, and survival time is the maximum additional time a message is expected after the PDB.

[0011] For Time Sensitive Communication (TSC) traffic types in existing systems (typical in industrial automation communications), for example, 3GPP TS23.501v17.2.0 specifies TSC Assistance Information (TSCAI) signaling that can provide further information about QoS flow traffic from the 5G core network to the RAN. Knowledge of TSC traffic patterns is useful to enable the 5G-AN (access network) to more efficiently schedule periodic, deterministic traffic flows, either via configured grants, semi-persistent scheduling, or dynamic grants. Time to live can be provided in terms of either a maximum number of messages (a message corresponds to a burst) or time units. A single burst can be expected within a single time period, called a period, as described, for example, in the following example table excerpted from 3GPP TS23.501v17.2.0: TIFF2025537534000002.tif57170

[0012] In some existing systems, when a survival time (ST) period begins (also referred to as entering survival mode), RAN implementations may schedule radio resources more robustly to ensure that any subsequent messages can be successfully delivered before the survival time is violated. If the message is successfully delivered, the robust resource allocation may be replaced with a "normal" resource allocation. This is shown in the example timing diagram of FIG. 3, which illustrates an example survival time configuration in the RAN. As shown in FIG. 3, at a first time, a "normal" allocation (i.e., an unincreased allocation) of PRBs is configured for a first message until the PDB is exhausted. The first message is determined to be lost, and the survival timer starts, at which point the network node / gNB allocates more resources for a second message. The second message arrives at a second time while the survival timer is still running, and more PRBs are allocated for the second message. The second message is successfully delivered before the expiration of the PDB and survival timer. The third message arrives a third time and uses the normal allocation of PRBs.

[0013] An increased resource allocation (i.e., a robust allocation larger than the "normal" allocation typically used) may only be needed if the previous message was not successfully delivered, while in all other cases the normal resource allocation may be used. Note that message failure rates are already an extremely rare event in some existing systems. For example, the standard 5QI value for delay-constrained GBR QoS flows (82 to 86) in 3GPP TS23.501v17.2.0 is 10 -4 or 10 -5 The time-to-live mechanism may be implemented to achieve higher communication service availability targets (e.g., 10 -9 ) can be one way to ensure

[0014] Therefore, a scheduling mechanism by the network that always allocates more radio resources for every data transmission is required when the survival requirement (e.g., communication service availability, calculated as the probability that the communication service will not be interrupted) is, for example, 10 -9 Opportunistic radio resource allocation may be more efficient for meeting communication service requirements while keeping radio resource allocation within a reasonable amount.

[0015] However, such radio resource configurations may not be configured to efficiently trigger resource allocation shifts. In the case of periodic traffic, for example, the network node / gNB may be aware of packet arrivals at either the wireless device or the network node (e.g., by using TSCAI parameters) and may then observe whenever a packet is not delivered within the packet delay budget. Upon observing this, the network node may schedule subsequent packets with greater reliability to help ensure that the time to live is not violated, such as by sending a (re)activation command for the uplink (UL) CG, or a dynamic uplink grant with a more robust modulation coding scheme (MCS), or even activating PDCP replication.

[0016] In existing systems, user-plane data transmission is typically interrupted during handover of a wireless device from a source Next-Generation RAN (NG-RAN) to a target NG-RAN. If one UL packet is still in transmission during handover (e.g., waiting for hybrid automatic repeat request (HARQ) retransmission or radio link control (RLC) retransmission), this packet may be retransmitted in the target cell and not meet the packet delay budget. For example, the handover interruption time may actually be between 43 and 160 milliseconds (ms) in various cases. If the handover is via a core network, the handover interruption time is even longer. Although the Dual Active Protocol Stack (DAPS) is specified in 3GPP Rel-16 to support a 0-ms interruption, it calculates the interruption time only in terms of the connection, not individual packets. A DAPS handover is a handover process that maintains the source network node / gNB connection after receiving the Radio Resource Control (RRC) message for handover and until releasing the source cell after successful random access to the target network node / gNB. DAPS has some further limitations, such as not applying to FR2 to FR2 handovers.

[0017] For example, for time-sensitive communications, including XR services and industrial automation, which involve time-to-live, one notable difference from mobile broadband services is that packets have deadlines associated with them. If the delivery of these packets has already exceeded their deadlines, it is beneficial to drop them so that radio resources are not wasted on non-useful transmissions (e.g., so that subsequent packets that also have deadlines are not delayed due to these non-useful transmissions).

[0018] Because handover interruption times can be large and variable, after a handover, the wireless device and / or network node may still be transmitting unused data. This may occur in the following cases: 1. The packet is past its expiration date, 2. The packet cannot meet its deadline due to additional data transmission scheduling delays at the target, assuming the packet remains at the source for some time, and / or 3. If there is a time-to-live associated with the service, the service may be effective in intentionally discarding the preceding packet, which may remain in the buffer for some time and have a shorter time to expiration than the newly arriving packet. The target NG-RAN can then allocate all resources for the subsequent packet.

[0019] The handover process should ideally attempt to avoid data loss. However, existing systems are not configured to properly discard delayed (and unusable) packets (including PDCP SDUs, RLC SDUs, and RLC PDUs) during handover. One existing solution is to set a PDCP discard timer in the wireless device (which continues to run during handover), but this may be usable for case 1 above when a packet exceeds its deadline (when there is a change in PDCP anchoring point on the network side), rather than for DL ​​traffic during handover. Also, existing solutions cannot address XR services, which have interdependencies between successive application PDUs.

[0020] Therefore, existing systems lack a mechanism for dropping data for time-sensitive communications during handover. Summary of the Invention

[0021] Some embodiments advantageously provide a method, system, and apparatus for data dropping for time-sensitive communications during handover.

[0022] In some embodiments, the WD and target network nodes discard PDCP SDUs and PDUs that are no longer in use (eg, have missed their latency deadlines).

[0023] In some embodiments, for downlink (DL) traffic, the source network node is configured to forward to the handover target network node timing information for forwarded PDCP SDUs and / or PDUs, such as a timestamp of when the PDCP SDUs become available for transmission (e.g., an implementation-specific discard / active queue management (AQM) timer start time or expiration time). After the handover abort time, the target network node determines based on this forwarded timing information / timestamp whether the PDCP SDUs and / or PDUs can be discarded instead of being transmitted / retransmitted, and in some embodiments, discards them if the deadline has passed. When data PDUs are associated, for example, by ADUs, the source RAN may calculate and / or transmit a reference time for the target RAN to understand that without acknowledgment of receipt of a "critical" data PDU (e.g., an I-frame), the remaining data PDUs can be discarded.

[0024] In some embodiments, for UL traffic, the network node indicates to the WD to discard PDCP SDUs and / or PDCP PDUs that should not be transmitted to the target network node. This includes discarding potential PDCP PDU retransmissions in PDCP after the handover abort. In some embodiments, a PDCP SN gap may not be introduced with this discard, i.e., the PDCP PDU following this discard may have the next sequence number of the PDCP PDU before this discard.

[0025] Thus, in some embodiments, only useful PDCP SDUs / PDUs may be transmitted after handover, allowing the target network node to schedule radio resources more efficiently and achieving lower latency and higher reliability compared to existing solutions. In other words, non-useful PDCP SDUs / PDUs are not transmitted, allowing the network node to transmit follow-up SDUs that are important for higher layer applications.

[0026] According to one aspect, a source network node configured to communicate with a wireless device (WD) and a target network node is described. The source network node is configured to obtain timing information associated with Packet Data Convergence Protocol (PDCP) resources. The PDCP resources correspond to packets scheduled for downlink transmission from the source network node or uplink transmission from the WD. The source network node is further configured to transmit the timing information associated with the PDCP resources to the target network node after a handover request is transmitted by the source network node, so that the target network node determines, based on the timing information, whether to discard the PDCP resources or packets or have the WD discard them.

[0027] In some embodiments, the timing information associated with the PDCP resource includes one or more of: (A) when the PDCP resource becomes available for transmission at the source network node; (B) when a discard timer for the PDCP resource times out; (C) when an active queue management (AQM) process triggers a drop of the PDCP resource; (D) when the source network node anticipates subsequent uplink PDCP resources; (E) PDCP protocol data unit (PDU) time information in data forwarding and offloading information associated with information elements in the handover request; (F) a PDCP PDU timestamp; (G) a PDCP discard timer; and (H) PDCP PDU time information included in a report list.

[0028] In some embodiments, the source network node is further configured to determine whether to perform a handover of the WD from the source network node to the target network node based on the measurement report.

[0029] In some other embodiments, the source network node is further configured to send a handover request to the target network node or WD.

[0030] In some embodiments, the source network node is further configured to transmit PDCP resources to the target network node.

[0031] In some other embodiments, the timing information is included in the handover request.

[0032] In some embodiments, the source network node is further configured to determine that a timing condition cannot be met when the source network node or WD transmits a PDCP resource or packet. The timing condition is associated with the timing information.

[0033] In some other embodiments, the source network node is further configured to transmit at least the timing information in response to determining that the timing condition cannot be met.

[0034] In some embodiments, the PDCP resource is one or both of a PDCP PDU and a PDCP service data unit (SDU).

[0035] In some other embodiments, the packets include DL data or UL data.

[0036] According to another aspect, a method in a source network node configured to communicate with a wireless device (WD) and a target network node is described. The method includes obtaining timing information associated with Packet Data Convergence Protocol (PDCP) resources. The PDCP resources correspond to packets scheduled for downlink transmission from the source network node or uplink transmission from the WD. The method also includes, after a handover request is transmitted by the source network node, transmitting the timing information associated with the PDCP resources to the target network node, so that the target network node determines, based on the timing information, whether to discard the PDCP resources or the packets or have the WD discard them.

[0037] In some embodiments, the timing information associated with the PDCP resource includes one or more of: (A) when the PDCP resource becomes available for transmission at the source network node; (B) when a discard timer for the PDCP resource times out; (C) when an active queue management (AQM) process triggers a drop of the PDCP resource; (D) when the source network node anticipates subsequent uplink PDCP resources; (E) PDCP protocol data unit (PDU) time information in data forwarding and offloading information associated with information elements in the handover request; (F) a PDCP PDU timestamp; (G) a PDCP discard timer; and (H) PDCP PDU time information included in a report list.

[0038] In some other embodiments, the method further includes determining whether to perform a handover of the WD from the source network node to the target network node based on the measurement report.

[0039] In some embodiments, the method further includes transmitting a handover request to the target network node or WD.

[0040] In some other embodiments, the method further includes transmitting the PDCP resource to the target network node.

[0041] In some embodiments, the timing information is included in the handover request.

[0042] In some other embodiments, the method further includes determining that a timing condition cannot be met when the source network node or WD transmits the PDCP resource or packet. The timing condition is associated with the timing information.

[0043] In some embodiments, the method further includes transmitting at least the timing information in response to determining that the timing condition cannot be met.

[0044] In some other embodiments, the PDCP resource is one or both of a PDCP PDU and a PDCP service data unit (SDU).

[0045] In some embodiments, the packets include DL data or UL data.

[0046] According to one aspect, a target network node configured to communicate with a wireless device (WD) and a source network node is described. The target network node is configured to receive, from the source network node, timing information associated with Packet Data Convergence Protocol (PDCP) resources. The PDCP resources correspond to packets scheduled for downlink transmission from the source network node or uplink transmission from the WD. The target network node is further configured to: after a handover request is transmitted by the source network node, determine, based on the timing information, whether to discard the PDCP resources or packets or have the WD discard them; and, based on the determination, to either discard the PDCP resources or packets or have the WD discard them.

[0047] In some embodiments, the timing information associated with the PDCP resource includes one or more of: (A) when the PDCP resource becomes available for transmission at the source network node; (B) when a discard timer for the PDCP resource times out; (C) when an active queue management (AQM) process triggers a drop of the PDCP resource; (D) when the source network node anticipates subsequent uplink PDCP resources; (E) PDCP protocol data unit (PDU) time information in data forwarding and offloading information associated with information elements in the handover request; (F) a PDCP PDU timestamp; (G) a PDCP discard timer; and (H) PDCP PDU time information included in a report list.

[0048] In some other embodiments, the target network node is further configured to one of transmit or cause the WD to transmit the PDCP resource or packet based on the determination.

[0049] In some embodiments, the target network node is further configured to receive a handover request from the source network node.

[0050] In some other embodiments, the timing information is included in the handover request.

[0051] In some embodiments, the target network node is further configured to determine that a timing condition cannot be met when the target network node or WD transmits a PDCP resource or packet. The timing condition is associated with the timing information.

[0052] In some other embodiments, the target network node is further configured to determine whether to discard, or cause the WD to discard, the PDCP resource or packet further based on the determination that the timing condition cannot be met.

[0053] In some embodiments, causing the WD to discard includes sending an indication to the WD to discard the PDCP resource or packet.

[0054] In some other embodiments, the PDCP resource is one or both of a PDCP PDU and a PDCP service data unit (SDU).

[0055] In some embodiments, the packets include DL data or UL data.

[0056] According to another aspect, a method in a wireless device (WD) and a target network node configured to communicate with a source network node is described. The method includes receiving, from the source network node, timing information associated with Packet Data Convergence Protocol (PDCP) resources. The PDCP resources correspond to packets scheduled for downlink transmission from the source network node or uplink transmission from the WD. After a handover request is transmitted by the source network node, the method further includes determining, based on the timing information, whether to discard the PDCP resources or packets or have the WD discard them, and, based on the determination, one of discarding the PDCP resources or packets or having the WD discard them.

[0057] In some embodiments, the timing information associated with the PDCP resource includes one or more of: (A) when the PDCP resource becomes available for transmission at the source network node; (B) when a discard timer for the PDCP resource times out; (C) when an active queue management (AQM) process triggers a drop of the PDCP resource; (D) when the source network node anticipates subsequent uplink PDCP resources; (E) PDCP protocol data unit (PDU) time information in data forwarding and offloading information associated with information elements in the handover request; (F) a PDCP PDU timestamp; (G) a PDCP discard timer; and (H) PDCP PDU time information included in a report list.

[0058] In some other embodiments, the method further includes one of transmitting or causing the WD to transmit the PDCP resource or packet based on the determination.

[0059] In some embodiments, the method further comprises receiving a handover request from the source network node.

[0060] In some other embodiments, the timing information is included in the handover request.

[0061] In some embodiments, the method further includes determining that a timing condition cannot be met when the target network node or WD transmits the PDCP resource or packet. The timing condition is associated with the timing information.

[0062] In some other embodiments, the method further includes determining whether to discard, or have the WD discard, the PDCP resource or packet further based on the determination that the timing condition cannot be met.

[0063] In some embodiments, causing the WD to discard includes sending an indication to the WD to discard the PDCP resource or packet.

[0064] In some other embodiments, the PDCP resource is one or both of a PDCP PDU and a PDCP service data unit (SDU).

[0065] In some embodiments, the packets include DL data or UL data.

[0066] According to one aspect, a wireless device (WD) configured to communicate with a source network node and a target network node is described. The WD is configured to perform a handover of the WD from the source network node to the target network node. The target network node has received timing information associated with Packet Data Convergence Protocol (PDCP) resources from the source network node. The PDCP resources correspond to packets scheduled for downlink transmission from the source network node or uplink transmission from the WD. The WD is further configured to receive an indication from the target network node to discard the PDCP resources or packets, the indication being sent based on the timing information, and to discard the PDCP resources or packets based on the indication.

[0067] In some embodiments, the indication includes a sequence number (SN), and the WD is further configured to discard PDCP resources or packets based on the SN.

[0068] In some other embodiments, revoking PDCP resources based on the SN includes revoking other PDCP resources up to that SN.

[0069] In some embodiments, the WD is further configured to stop pre-processing of PDCP resources during handover based on the indication.

[0070] In some other embodiments, the WD is further configured to send a first message indicating that radio resource control (RRC) configuration is complete, and to receive a second message from the target network node in response to the first message, the second message being an RRC message and including the indication.

[0071] In some embodiments, the PDCP resource is one or both of a PDCP PDU and a PDCP service data unit (SDU).

[0072] In some other embodiments, the packets include DL data or UL data.

[0073] According to another aspect, a method in a wireless device (WD) configured to communicate with a source network node and a target network node is described. The method includes performing a handover of the WD from the source network node to the target network node. The target network node receives timing information associated with Packet Data Convergence Protocol (PDCP) resources from the source network node. The PDCP resources correspond to packets scheduled for downlink transmission from the source network node or uplink transmission from the WD. The method also includes receiving, from the target network node, an indication to discard the PDCP resources or packets, the indication being sent based on the timing information, and discarding the PDCP resources or packets based on the indication.

[0074] In some embodiments, the indication includes a sequence number (SN), and the method further includes discarding the PDCP resource or packet based on the SN.

[0075] In some other embodiments, revoking PDCP resources based on the SN includes revoking other PDCP resources up to that SN.

[0076] In some embodiments, the method further includes stopping pre-processing of PDCP resources during the handover based on the indication.

[0077] In some other embodiments, the method further includes transmitting a first message indicating that the radio resource control (RRC) configuration is complete, and receiving a second message from the target network node in response to the first message, the second message being an RRC message and including the indication.

[0078] In some embodiments, the PDCP resource is one or both of a PDCP PDU and a PDCP service data unit (SDU).

[0079] In some other embodiments, the packets include DL data or UL data.

[0080] A more complete understanding of the present embodiments, together with their attendant advantages and features, will be more readily appreciated by reference to the following detailed description when considered in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0081] [Figure 1] A graphical depiction of the challenges in balancing various attributes for XR with regards to reliability, latency constraints, and bitrate. [Figure 2] FIG. 1 is a timing diagram illustrating an exemplary normal XR traffic profile. [Figure 3] FIG. 1 is a timing diagram illustrating an exemplary time-to-live setting in the RAN. [Figure 4]1 is a schematic diagram of an exemplary network architecture illustrating a communication system connected to a host computer through an intermediate network in accordance with the principles of the present disclosure; [Figure 5] FIG. 1 is a block diagram of a host computer that communicates with a wireless device through a network node at least partially over a wireless connection, in accordance with some embodiments of the present disclosure. [Figure 6] 1 is a flowchart illustrating an exemplary method implemented in a communication system including a host computer, a network node, and a wireless device for executing a client application on a wireless device, according to some embodiments of the present disclosure. [Figure 7] 1 is a flowchart illustrating an exemplary method implemented in a communication system including a host computer, a network node, and a wireless device for receiving user data at a wireless device, in accordance with some embodiments of the present disclosure. [Figure 8] 1 is a flowchart illustrating an exemplary method implemented in a communication system including a host computer, a network node, and a wireless device for receiving user data at a host computer from a wireless device, in accordance with some embodiments of the present disclosure. [Figure 9] 1 is a flowchart illustrating an exemplary method implemented in a communication system including a host computer, a network node, and a wireless device for receiving user data at a host computer, in accordance with some embodiments of the present disclosure. [Figure 10] 1 is a flowchart of an example process in a network node for data dropping for time-sensitive communications during handover, in accordance with some embodiments of the present disclosure. [Figure 11] 1 is a flowchart of an example process in a wireless device for data dropping for time-sensitive communications during handover, in accordance with some embodiments of the present disclosure. [Figure 12] 10 is a flowchart of another example process in a network node for data dropping for time-sensitive communications during handover, in accordance with some embodiments of the present disclosure. [Figure 13] 10 is a flowchart of another example process at another network node for data dropping for time-sensitive communications during handover, in accordance with some embodiments of the present disclosure. [Figure 14] 1 is a flowchart of an example process in a wireless device for data dropping for time-sensitive communications during handover, in accordance with some embodiments of the present disclosure. [Figure 15] 10A-10C illustrate an example flowchart and signaling diagram for DL ​​data discarding in accordance with some embodiments of the present disclosure. [Figure 16] 1A-1C are a flowchart and signaling diagram for UL data discarding according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0082] Before describing the exemplary embodiments in detail, it should be noted that the embodiments reside primarily in a combination of device components and processing steps related to data dropping for time-sensitive communications during handover. Accordingly, components have been represented by conventional numerals in the drawings, where appropriate, and only specific details relevant to understanding the embodiments are shown so as not to obscure the present disclosure with details that will be readily apparent to those skilled in the art having the benefit of the description herein. Like numbers refer to like elements throughout the description.

[0083] As used herein, relational terms such as “first” and “second,” “upper,” and “lower,” etc., may be used only to distinguish one entity or element from another and do not necessarily require or imply any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the concepts described herein. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly dictates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and / or “including,” as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0084] In the embodiments described herein, coupling terms such as "in communication with" may be used to indicate electrical or data communication, which may be achieved, for example, by physical contact, induction, electromagnetic radiation, radio signals, infrared signals, or optical signals. Those skilled in the art will understand that multiple components may interoperate and that modifications and variations are possible to achieve electrical and data communication.

[0085] In some embodiments described herein, terms such as "coupled," "connected," and the like may be used herein to indicate a connection, although not necessarily a direct one, and may include a wired and / or wireless connection.

[0086] The term "network node" as used herein may refer to any type of network node provided in a wireless network, which may further comprise any of a base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), gNodeB (gNB), evolved NodeB (eNB or eNodeB), NodeB, multi-standard radio (MSR) radio node such as MSR BS, multi-cell / multicast coordination entity (MCE), integrated access and backhaul (IAB) node, relay node, donor node controlling relay, wireless access point (AP), transmission point, transmitting node, remote radio unit (RRU), remote radio head (RRH), core network node (e.g., mobile management entity (MME), self-organizing network (SON) node, coordination node, positioning node, MDT node, etc.), external node (e.g., third-party node, node outside the current network), node in a distributed antenna system (DAS), spectrum access system (SAS) node, element management system (EMS), etc. A network node may also comprise test equipment. As used herein, the term "wireless node" may also be used to refer to a wireless device (WD) such as a wireless device (WD) or a wireless network node.

[0087] In some embodiments, the non-limiting terms wireless device (WD) or user equipment (UE) are used interchangeably. A WD in this specification can be any type of wireless device capable of communicating with a network node or another WD via radio signals, such as a wireless device (WD). A WD can also be a wireless communication device, a target device, a device-to-device (D2D) WD, a machine-type WD or a WD capable of machine-to-machine communication (M2M), a low-cost and / or low-complexity WD, a sensor equipped with a WD, a tablet, a mobile terminal, a smartphone, a laptop embedded equipped (LEE), a laptop mounted equipment (LME), a USB dongle, a customer premises equipment (CPE), an Internet of Things (IoT) device, or a narrowband IoT (NB-IoT) device, etc.

[0088] Also, in some embodiments, the generic term "radio network node" is used, which can be any type of radio network node, which can comprise a base station, radio base station, base transceiver station, base station controller, network controller, RNC, evolved Node B (eNB), Node B, gNB, multi-cell / multicast coordination entity (MCE), IAB node, relay node, access point, radio access point, remote radio unit (RRU), or remote radio head (RRH).

[0089] It should be noted that, while terminology from one particular wireless system, such as 3GPP LTE and / or New Radio (NR), may be used in this disclosure, this should not be considered to limit the scope of this disclosure to only the aforementioned systems. Other wireless systems, including, but not limited to, Wideband Code Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB), and Global System for Mobile Communications (GSM), may also benefit from utilizing the ideas covered within this disclosure.

[0090] It should be further noted that functionality described herein as being performed by a wireless device or network node may be distributed across multiple wireless devices and / or network nodes. In other words, it is contemplated that the functionality of the network nodes and wireless devices described herein is not limited to being performed by a single physical device, but may in fact be distributed among several physical devices.

[0091] In some embodiments, the term PDCP resource is used and may refer to any resource associated with PDCP, such as a PDU, an SDU, data, or a portion of a packet.

[0092] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Terms used herein should be interpreted as having a meaning consistent with their meaning in the context of the present specification and related art, and will not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0093] Some embodiments provide techniques for data dropping for time-sensitive communications during handover.

[0094] Referring again to the drawings, in which like elements are designated by like reference numerals, FIG. 4 shows a schematic diagram of a communication system 10 according to one embodiment, such as a 3GPP-type cellular network that may support standards such as LTE and / or NR (5G), comprising an access network 12, such as a radio access network, and a core network 14. The access network 12 comprises multiple network nodes 16a, 16b, 16c (collectively referred to as network nodes 16), such as NBs, eNBs, gNBs, or other types of wireless access points, each defining a corresponding coverage area 18a, 18b, 18c (collectively referred to as coverage area 18). Each network node 16a, 16b, 16c is connectable to the core network 14 via a wired or wireless connection 20. A first wireless device (WD) 22a located within the coverage area 18a wirelessly connects to or is configured to be paged by the corresponding network node 16a. A second WD 22b within coverage area 18b can wirelessly connect to corresponding network node 16b. While multiple WDs 22a, 22b (collectively referred to as wireless devices 22) are shown in this example, the disclosed embodiments are equally applicable to situations where only one WD is within a coverage area or where only one WD connects to a corresponding network node 16. For convenience, while only two WDs 22 and three network nodes 16 are shown, it should be noted that a communication system may include many more WDs 22 and network nodes 16.

[0095] The cell currently used by WD 22 may be referred to as the source cell (e.g., served by the source network node 16a), and the cell to which WD 22 is handed over (e.g., as a result of a handoff / handover process) may be referred to as the target cell (served by the target network node 16b). Although both the source cell and the target cell may be provided by the same network node 16, for simplicity herein it may be assumed that the source cell is associated with the source network node 16a and the target cell is associated with the (different) target network node 16b.

[0096] It is also contemplated that the WD 22 may simultaneously communicate with and / or be configured to separately communicate with more than one network node 16 and more than one type of network node 16. For example, the WD 22 may have dual connectivity with a network node 16 that supports LTE and the same or different network node 16 that supports NR. As an example, the WD 22 may communicate with an eNB for LTE / E-UTRAN and a gNB for NR / NG-RAN.

[0097] The communication system 10 may itself be connected to a host computer 24, which may be embodied in hardware and / or software of a standalone server, a cloud-implemented server, a distributed server, or as a processing resource within a server farm. The host computer 24 may be under the ownership or control of a service provider, or may be operated by or on behalf of the service provider. The connection 26, 28 between the communication system 10 and the host computer 24 may extend directly from the core network 14 to the host computer 24 or may extend through an optional intermediate network 30. The intermediate network 30 may be one of a public network, a private network, or a host network, or a combination of two or more thereof. The intermediate network 30, if present, may be a backbone network or the Internet. In some embodiments, the intermediate network 30 may include two or more subnetworks (not shown).

[0098] The communication system of FIG. 4 as a whole enables a connection between one of the connected WDs 22a, 22b and the host computer 24. The connection may be described as an over-the-top (OTT) connection. The host computer 24 and the connected WDs 22a, 22b are configured to communicate data and / or signaling over the OTT connection using the access network 12, the core network 14, any intermediate networks 30, and possibly further infrastructure (not shown) as intermediaries. The OTT connection may be transparent in the sense that at least some of the participating communication devices through which the OTT connection passes are unaware of the routing of the uplink and downlink communications. For example, the network node 16 may not, and need not, be informed about the past routing of incoming downlink communications having data originating from the host computer 24 that is forwarded (e.g., handed over) to the connected WD 22a. Similarly, the network node 16 need not be aware of the future routing of outgoing uplink communications originating from the WD 22a toward the host computer 24.

[0099] The network node 16 is configured to include an NN management unit 32 configured to perform data dropping for time-critical communications during handover. The wireless device 22 is configured to include a WD management unit 34 configured to perform data dropping for time-critical communications during handover.

[0100] An exemplary implementation of the WD 22, network node 16, and host computer 24 discussed in the previous paragraph, according to one embodiment, will now be described with reference to FIG. 5. In communication system 10, host computer 24 comprises hardware (HW) 38 including a communication interface 40 configured to set up and maintain wired or wireless connections with interfaces of different communication devices of communication system 10. Host computer 24 further comprises processing circuitry 42, which may have storage and / or processing capabilities. Processing circuitry 42 may include a processor 44 and memory 46. In particular, in addition to or instead of a processor and memory, such as a central processing unit, processing circuitry 42 may include integrated circuits for processing and / or control, e.g., one or more processors and / or processor cores and / or FPGAs (field programmable gate arrays) and / or ASICs (application-specific integrated circuits) adapted to execute instructions. The processor 44 may be configured to access (e.g., write and / or read) the memory 46, which may include any type of volatile and / or non-volatile memory, for example, cache and / or buffer memory and / or RAM (random access memory) and / or ROM (read only memory) and / or optical memory and / or EPROM (erasable programmable read only memory).

[0101] Processing circuitry 42 may be configured to control any of the methods and / or processes described herein and / or to cause such methods and / or processes to be performed by, for example, host computer 24. Processor 44 corresponds to one or more processors 44 for performing the functions of host computer 24 described herein. Host computer 24 includes memory 46 configured to store data, program software code, and / or other information described herein. In some embodiments, software 48 and / or host application 50 may include instructions that, when executed by processor 44 and / or processing circuitry 42, cause processor 44 and / or processing circuitry 42 to perform the processes described herein with respect to host computer 24. The instructions may be software associated with host computer 24.

[0102] Software 48 may be executable by processing circuitry 42. Software 48 includes a host application 50. Host application 50 may be operable to provide services to remote users, such as WD 22, connecting via an OTT connection 52 that terminates at WD 22 and host computer 24. In providing services to remote users, host application 50 may provide user data transmitted using OTT connection 52. "User data" may be data and information described herein as implementing described functionality. In one embodiment, host computer 24 may be configured to provide control and functionality to a service provider and may be operated by or on behalf of the service provider. Processing circuitry 42 of host computer 24 may enable host computer 24 to observe, monitor, control, send to, and / or receive from network node 16 and / or wireless device 22.

[0103] The communication system 10 further includes a network node 16 including hardware 58 provided within the communication system 10 to enable communication with the host computer 24 and the WD 22. The hardware 58 may include a communication interface 60 for setting up and maintaining wired or wireless connections with interfaces of different communication devices of the communication system 10, and a radio interface 62 for setting up and maintaining at least a wireless connection 64 with a WD 22 located within the coverage area 18 served by the network node 16. The radio interface 62 may be formed as or include, for example, one or more RF transmitters, one or more RF receivers, and / or one or more RF transceivers. The communication interface 60 may be configured to facilitate a connection 66 to the host computer 24. The connection 66 may be direct or may pass through the core network 14 of the communication system 10 and / or one or more intermediate networks 30 external to the communication system 10.

[0104] In the illustrated embodiment, hardware 58 of network node 16 further includes processing circuitry 68. Processing circuitry 68 may include a processor 70 and memory 72. In particular, in addition to or instead of a processor and memory such as a central processing unit, processing circuitry 68 may include integrated circuits for processing and / or control, e.g., one or more processors and / or processor cores and / or FPGAs (field programmable gate arrays) and / or ASICs (application-specific integrated circuits) adapted to execute instructions. Processor 70 may be configured to access (e.g., write and / or read) memory 72, which may include any type of volatile and / or non-volatile memory, e.g., cache and / or buffer memory and / or RAM (random access memory) and / or ROM (read-only memory) and / or optical memory and / or EPROM (erasable programmable read-only memory).

[0105] Thus, network node 16 further has software 74 stored, for example, internally in memory 72 or stored in external memory (e.g., a database, storage array, network storage device, etc.) accessible by network node 16 via an external connection. Software 74 may be executable by processing circuitry 68. Processing circuitry 68 may be configured to control any of the methods and / or processes described herein and / or to cause such methods and / or processes to be performed, for example, by network node 16. Processor 70 corresponds to one or more processors 70 for performing the functions of network node 16 described herein. Memory 72 is configured to store data, program software code, and / or other information described herein. In some embodiments, software 74 may include instructions that, when executed by processor 70 and / or processing circuitry 68, cause processor 70 and / or processing circuitry 68 to perform the processes described herein with respect to network node 16. For example, the processing circuitry 68 of the network node 16 may include an NN management unit 32 configured to perform data dropping for time-sensitive communications during handover.

[0106] In some embodiments, the hardware and / or software of the source network node 16a and the target network node 16b are similar, and therefore the network node 16 shown in FIG. 5 may refer to either the source network node 16a or the target network node 16b.

[0107] The communication system 10 further includes the previously mentioned WD 22. The WD 22 may have hardware 80 that may include a radio interface 82 configured to set up and maintain a wireless connection 64 with a network node 16 that serves the coverage area 18 in which the WD 22 is currently located. The radio interface 82 may be formed as or include, for example, one or more RF transmitters, one or more RF receivers, and / or one or more RF transceivers.

[0108] The hardware 80 of the WD 22 further includes processing circuitry 84. The processing circuitry 84 may include a processor 86 and memory 88. In particular, in addition to or instead of a processor and memory, such as a central processing unit, the processing circuitry 84 may include integrated circuits for processing and / or control, e.g., one or more processors and / or processor cores and / or FPGAs (field programmable gate arrays) and / or ASICs (application-specific integrated circuits) adapted to execute instructions. The processor 86 may be configured to access (e.g., write and / or read) the memory 88, which may include any type of volatile and / or non-volatile memory, e.g., cache and / or buffer memory and / or RAM (random access memory) and / or ROM (read-only memory) and / or optical memory and / or EPROM (erasable programmable read-only memory).

[0109] Thus, the WD 22 may further comprise software 90, for example, stored in the memory 88 of the WD 22 or in an external memory accessible by the WD 22 (e.g., a database, a storage array, a network storage device, etc.). The software 90 may be executable by the processing circuitry 84. The software 90 may include a client application 92. The client application 92 may be operable to provide services to a human or non-human user via the WD 22 with the support of the host computer 24. A host application 50 running on the host computer 24 may communicate with the running client application 92 via an OTT connection 52 terminating at the WD 22 and the host computer 24. In providing services to the user, the client application 92 may receive request data from the host application 50 and provide user data in response to the request data. The OTT connection 52 may transfer both the request data and the user data. The client application 92 may interact with the user to generate the user data that it provides.

[0110] The processing circuitry 84 may be configured to control any of the methods and / or processes described herein and / or to cause such methods and / or processes to be performed, for example, by the WD 22. The processor 86 corresponds to one or more processors 86 for performing the functions of the WD 22 described herein. The WD 22 includes a memory 88 configured to store data, program software code, and / or other information described herein. In some embodiments, the software 90 and / or client application 92 may include instructions that, when executed by the processor 86 and / or processing circuitry 84, cause the processor 86 and / or processing circuitry 84 to perform the processes described herein with respect to the WD 22. For example, the processing circuitry 84 of the wireless device 22 may include a WD management unit 34 configured to perform data dropping for time-sensitive communications during handover.

[0111] In some embodiments, the internal operation of network node 16, WD 22, and host computer 24 may be as shown in FIG. 5, and alternatively, the surrounding network topology may be that of FIG.

[0112] 5, OTT connection 52 is depicted abstractly to illustrate communication between host computer 24 and wireless device 22 via network nodes 16, without explicit reference to any intermediate devices and the precise routing of messages through those devices. The network infrastructure may make routing decisions that may be configured to be hidden from WD 22, from the service provider operating host computer 24, or both. While OTT connection 52 is active, the network infrastructure may further make decisions to dynamically change the routing (e.g., based on network load balancing considerations or reconfiguration).

[0113] The wireless connection 64 between the WD 22 and the network node 16 follows the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of the OTT service provided to the WD 22 using the OTT connection 52, of which the wireless connection 64 may form the final segment. More precisely, the teachings of some of these embodiments may improve data rate, latency, and / or power consumption, thereby providing benefits such as reduced user latency, relaxed limits on file sizes, better responsiveness, extended battery life, etc.

[0114] In some embodiments, measurement procedures may be provided for the purpose of monitoring data rates, latency, and other factors that one or more embodiments improve. Additionally, there may be optional network functionality for reconfiguring the OTT connection 52 between the host computer 24 and the WD 22 in response to changes in the measurement results. The measurement procedures and / or network functionality for reconfiguring the OTT connection 52 may be implemented in the software 48 of the host computer 24, in the software 90 of the WD 22, or both. In embodiments, sensors (not shown) may be deployed in or associated with the communication devices through which the OTT connection 52 passes, and the sensors may participate in the measurement procedures by providing values ​​of the monitored quantities exemplified above or other physical quantities from which the software 48, 90 may calculate or estimate the monitored quantities. The reconfiguration of the OTT connection 52 may include changes in message formats, retransmission settings, preferred routing, etc., and the reconfiguration need not affect the network node 16 and may not be known or recognized by the network node 16. Some such procedures and functions are known in the art and may be implemented. In some embodiments, measurements may involve dedicated WD signaling that facilitates the host computer 24 measuring throughput, propagation time, latency, etc. In some embodiments, measurements may be performed by causing the software 48, 90 to send messages, particularly empty or "dummy" messages, using the OTT connection 52 while monitoring propagation time, errors, etc.

[0115] Thus, in some embodiments, host computer 24 includes processing circuitry 42 configured to provide user data and a communications interface 40 configured to forward the user data to a cellular network for transmission to WD 22. In some embodiments, the cellular network also includes network node 16 having a wireless interface 62. In some embodiments, network node 16 is configured, and / or processing circuitry 68 of network node 16 is configured, to perform the functions and / or methods described herein for preparing / initiating / maintaining / supporting / terminating transmissions to WD 22 and / or for preparing / terminating / maintaining / supporting / terminating upon receipt of a transmission from WD 22.

[0116] In some embodiments, host computer 24 includes processing circuitry 42 and a communications interface 40 configured to receive user data from transmissions from WD 22 to network node 16. In some embodiments, WD 22 is configured with a wireless interface 82 and / or processing circuitry 84 configured to perform the functions and / or methods described herein for preparing / initiating / maintaining / supporting / terminating transmissions to network node 16 and / or for preparing / terminating / maintaining / supporting / terminating in reception of transmissions from network node 16.

[0117] 4 and 5 depict various "units," such as NN management unit 32 and WD management unit 34, as being within respective processors, it is contemplated that these units may be implemented such that portions of the units are stored in corresponding memories within the processing circuitry. In other words, the units may be implemented in hardware or a combination of hardware and software within the processing circuitry.

[0118] 6 is a flowchart illustrating an exemplary method implemented in a communication system, such as the communication systems of FIGS. 4 and 5, according to one embodiment. The communication system may include a host computer 24, a network node 16, and a WD 22, which may be as described with reference to FIG. 5. In a first step of the method, the host computer 24 provides user data (block S100). In an optional sub-step of the first step, the host computer 24 provides the user data by executing a host application, such as host application 50 (block S102). In a second step, the host computer 24 initiates a transmission carrying the user data to the WD 22 (block S104). In an optional third step, the network node 16 transmits the user data carried in the transmission initiated by the host computer 24 to the WD 22 (block S106), in accordance with the teachings of the embodiments described throughout this disclosure. In an optional fourth step, the WD 22 executes a client application, such as client application 92, associated with the host application 50 executed by the host computer 24 (block S108).

[0119] 7 is a flowchart illustrating an exemplary method implemented in a communication system, such as the communication system of FIG. 4, according to one embodiment. The communication system may include a host computer 24, a network node 16, and a WD 22, which may be as described with reference to FIGS. 4 and 5. In a first step of the method, the host computer 24 provides user data (block S110). In an optional substep (not shown), the host computer 24 provides the user data by executing a host application, such as host application 50. In a second step, the host computer 24 initiates a transmission carrying the user data to the WD 22 (block S112). The transmission may pass through the network node 16 in accordance with the teachings of the embodiments described throughout this disclosure. In an optional third step, the WD 22 receives the user data carried in the transmission (block S114).

[0120] 8 is a flowchart illustrating an exemplary method implemented in a communication system, such as the communication system of FIG. 4, according to one embodiment. The communication system may include a host computer 24, a network node 16, and a WD 22, which may be as described with reference to FIGS. 4 and 5. In an optional first step of the method, the WD 22 receives input data provided by the host computer 24 (block S116). In an optional sub-step of the first step, the WD 22 executes a client application 92, which provides user data in response to the received input data provided by the host computer 24 (block S118). Additionally or alternatively, in an optional second step, the WD 22 provides the user data (block S120). In an optional sub-step of the second step, the WD provides the user data by executing a client application, such as the client application 92 (block S122). In providing the user data, the executed client application 92 may further take into account user input received from a user. Regardless of the particular manner in which the user data was provided, in an optional third substep, WD 22 may begin transmitting the user data to host computer 24 (block S124). In a fourth step of the method, host computer 24 receives the transmitted user data from WD 22 (block S126) in accordance with the teachings of the embodiments described throughout this disclosure.

[0121] 9 is a flowchart illustrating an exemplary method implemented in a communication system, such as the communication system of FIG. 4, according to one embodiment. The communication system may include a host computer 24, a network node 16, and a WD 22, which may be as described with reference to FIGS. 4 and 5. In an optional first step of the method, the network node 16 receives user data from the WD 22 (block S128), in accordance with the teachings of embodiments described throughout this disclosure. In an optional second step, the network node 16 initiates transmission of the received user data to the host computer 24 (block S130). In a third step, the host computer 24 receives the user data carried in a transmission initiated by the network node 16 (block S132).

[0122] 10 is a flowchart of an example process in a network node 16 (e.g., target network node 16b) for data dropping for time-sensitive communications during handover. One or more blocks described herein may be performed by one or more elements of the network node 16, such as one or more of the processing circuitry 68 (including the NN management unit 32), the processor 70, the radio interface 62, and / or the communication interface 60. The target network node 16b is configured to receive a handover request from the source network node 16a (block S134) that includes Packet Data Convergence Protocol (PDCP) timing information associated with at least one PDCP packet. The target network node 16b is configured to receive at least one PDCP packet from the source network node 16a (block S136). The target network node 16b is configured to determine at least one action for the PDCP packet based on the PDCP timing information (block S138). The target network node 16b is optionally configured to send a handover request acknowledgement to the source network node 16a in response to the received handover request (block S140).

[0123] In one or more embodiments, the PDCP timing information includes at least one of a first time when the PDCP packet becomes available for transmission at the source network node 16a, a second time when a discard timer for the PDCP packet expires, and / or a third time when an active queue management (AQM) mechanism triggers the dropping of the PDCP packet.

[0124] In one or more embodiments, the at least one action on the PDCP packet includes forwarding the PDCP packet to the wireless device or discarding the PDCP packet.

[0125] In one or more embodiments, discarding a PDCP packet is based on the expiration of a discard timer for the PDCP packet.

[0126] In one or more embodiments, discarding the PDCP packet includes determining an importance metric associated with the PDCP packet and discarding at least one additional PDCP packet based on the importance metric exceeding a threshold.

[0127] In one or more embodiments, determining at least one action for the PDCP packet is further based on at least one of a fourth time when the target network node 16b is expected to start transmitting the PDCP packet and a fifth time when the target network node is expected to finish transmitting the PDCP packet.

[0128] 11 is a flowchart of an example process in a wireless device 22 according to some embodiments of the present disclosure for data dropping for time-sensitive communications during handover. One or more blocks described herein may be performed by one or more elements of the wireless device 22, such as one or more of the processing circuitry 84 (including the WD management unit 34), the processor 86, the air interface 82, and / or the communication interface 60. The wireless device 22 is configured to perform handover processing from the source network node 16a to the target network node 16b (block S142), e.g., via the processing circuitry 84 and / or the processor 86 and / or the air interface 82, where the target network node 16b is configured with PDCP timing information by the source network node 16a. The wireless device 22 is configured to receive from the target network node 16b an indication to discard at least one PDCP packet based on the PDCP timing information (block S144). The wireless device 22 is optionally configured to drop at least one PDCP packet based on the indication (block S146).

[0129] In one or more embodiments, the indication to discard the at least one PDCP packet includes an indicated sequence number (SN). Discarding the at least one PDCP packet includes discarding a first PDCP packet and discarding at least one subsequent PDCP packet based on the indicated SN being greater than or equal to a subsequent SN of the at least one subsequent PDCP packet.

[0130] In one or more embodiments, WD22 is further configured to assign a new SN to at least one non-dropped PDCP packet following at least one subsequent PDCP packet, the new SN being consecutive with a previous SN of a previous PDCP packet received before the first PDCP packet.

[0131] 12 is a flowchart of an example process in a network node 16 (e.g., source network node 16a). One or more blocks described herein may be executed by one or more elements of the network node 16, such as one or more of the processing circuitry 68 (including the NN management unit 32), the processor 70, the radio interface 62, and / or the communication interface 60. The source network node 16a is configured to obtain timing information associated with Packet Data Convergence Protocol (PDCP) resources (block S148). The PDCP resources correspond to packets scheduled for downlink transmission from the source network node 16a or uplink transmission from the WD 22. The source network node 16a is further configured to transmit the timing information associated with the PDCP resources to the target network node 16b (block S150) after the handover request is transmitted by the source network node 16a, so that the target network node 16b determines whether to discard or have the WD 22 discard the PDCP resources or packets based on the timing information.

[0132] In some embodiments, the timing information associated with the PDCP resource includes one or more of: (A) when the PDCP resource becomes available for transmission at the source network node 16a; (B) when a discard timer for the PDCP resource times out; (C) when an active queue management (AQM) process triggers a drop of the PDCP resource; (D) when the source network node 16a anticipates subsequent uplink PDCP resources; (E) PDCP protocol data unit (PDU) time information in data forwarding and offloading information associated with information elements in the handover request; (F) a PDCP PDU timestamp; (G) a PDCP discard timer; and (H) PDCP PDU time information included in a report list.

[0133] In some other embodiments, the method further includes determining whether to perform a handover of the WD 22 from the source network node 16a to the target network node 16b based on the measurement report.

[0134] In some embodiments, the method further includes transmitting a handover request to the target network node 16b or WD 22.

[0135] In some other embodiments, the method further includes transmitting the PDCP resources to the target network node 16b.

[0136] In some embodiments, the timing information is included in the handover request.

[0137] In some other embodiments, the method further includes determining that a timing condition cannot be met when the source network node 16a or WD 22 transmits the PDCP resource or packet. The timing condition is associated with the timing information.

[0138] In some embodiments, the method further includes transmitting at least the timing information in response to determining that the timing condition cannot be met.

[0139] In some other embodiments, the PDCP resource is one or both of a PDCP PDU and a PDCP service data unit (SDU).

[0140] In some embodiments, the packets include DL data or UL data.

[0141] FIG. 13 is a flowchart of an example process in a network node 16 (e.g., target network node 16b). One or more blocks described herein may be executed by one or more elements of the network node 16, such as one or more of the processing circuitry 68 (including the NN management unit 32), the processor 70, the radio interface 62, and / or the communication interface 60. The target network node 16b is configured to receive timing information associated with Packet Data Convergence Protocol (PDCP) resources from the source network node 16a (block S152). The PDCP resources correspond to packets scheduled for downlink transmission from the source network node 16a or uplink transmission from the WD 22. The target network node 16b is further configured to, after a handover request is transmitted by the source network node 16a, determine whether to discard or have the WD 22 discard the PDCP resources or packets based on the timing information (block S154), and, based on the decision, to either discard or have the WD 22 discard the PDCP resources or packets (block S156).

[0142] In some embodiments, the timing information associated with the PDCP resource includes one or more of: (A) when the PDCP resource becomes available for transmission at the source network node 16a; (B) when a discard timer for the PDCP resource times out; (C) when an active queue management (AQM) process triggers a drop for the PDCP resource; (D) when the source network node 16a anticipates subsequent uplink PDCP resources; (E) PDCP protocol data unit (PDU) time information in data forwarding and offloading information associated with information elements in the handover request; (F) a PDCP PDU timestamp; (G) a PDCP discard timer; and (H) PDCP PDU time information included in a report list.

[0143] In some other embodiments, the method further includes one of transmitting or causing the WD22 to transmit the PDCP resource or packet based on the determination.

[0144] In some embodiments, the method further includes receiving a handover request from the source network node 16a.

[0145] In some other embodiments, the timing information is included in the handover request.

[0146] In some embodiments, the method further includes determining that a timing condition cannot be met when the target network node 16b or WD 22 transmits the PDCP resource or packet. The timing condition is associated with the timing information.

[0147] In some other embodiments, the method further includes determining whether to discard, or have WD22 discard, the PDCP resource or packet further based on the determination that the timing condition cannot be met.

[0148] In some embodiments, causing the WD 22 to discard includes sending an indication to the WD 22 to discard the PDCP resource or packet.

[0149] In some other embodiments, the PDCP resource is one or both of a PDCP PDU and a PDCP service data unit (SDU).

[0150] In some embodiments, the packets include DL data or UL data.

[0151] 14 is a flowchart of an example process in a wireless device 22 according to some embodiments of the present disclosure for data dropping for time-sensitive communications during handover. One or more blocks described herein may be performed by one or more elements of the wireless device 22, such as one or more of the processing circuitry 84 (including the WD management unit 34), the processor 86, the air interface 82, and / or the communication interface 60. The wireless device 22 is configured to perform a handover of the WD 22 from the source network node 16a to the target network node 16b (block S158), such as via the processing circuitry 84 and / or the processor 86 and / or the air interface 82. The target network node 16b has received timing information associated with Packet Data Convergence Protocol (PDCP) resources from the source network node 16a. The PDCP resources correspond to packets scheduled for downlink transmission from the source network node 16a or uplink transmission from the WD 22. The WD22 is further configured to receive an indication from the target network node 16b to discard the PDCP resource or packet, the indication being sent based on timing information (block S160), and to discard the PDCP resource or packet based on the indication (block S162).

[0152] In some embodiments, the indication includes a sequence number (SN), and the method further includes discarding the PDCP resource or packet based on the SN.

[0153] In some other embodiments, revoking PDCP resources based on the SN includes revoking other PDCP resources up to that SN.

[0154] In some embodiments, the method further includes stopping pre-processing of PDCP resources during the handover based on the indication.

[0155] In some other embodiments, the method further includes transmitting a first message indicating that the radio resource control (RRC) configuration is complete and receiving a second message from the target network node 16b in response to the first message, the second message being an RRC message and including the indication.

[0156] In some embodiments, the PDCP resource is one or both of a PDCP PDU and a PDCP service data unit (SDU).

[0157] In some other embodiments, the packets include DL data or UL data.

[0158] Having described the general process flow of the configuration of the present disclosure and provided example hardware and software configurations for implementing the processes and features of the present disclosure, the following sections provide configuration details and examples for data dropping for time-sensitive communications during handover.

[0159] Downlink data discarded In the downlink, timing-related information for discarding a PDCP SDU needs to be evaluated at both the source NG-RAN node and the target NG-RAN node. In one embodiment of the present disclosure, for example, the source network node 16a "remembers" (i.e., stores / records in memory 72) timing-related information about the PDCP SDU, such as when the PDCP SDU becomes available for transmission in the source NG-RAN network, when the PDCP SDU's discard timer expires, when the AQM mechanism triggers a drop for this PDCP SDU, etc. The source network node 16a may forward this information (e.g., a timestamp) along with the PDCP SDU to the target network node 16b, i.e., when the PDCP SDU is undergoing forwarding processing during handover between network nodes 16a and 16b, or when the PDCP SDU is forwarded for retransmission at the target network node 16b.

[0160] In some embodiments, the source network node 16 a and the target network node 16 b may maintain a common reference time, e.g., GNSS time or GPS time, and / or they may be assumed to be synchronized to a local clock. This common reference time may be used as a reference for time stamping.

[0161] The target network node 16b may utilize this timing information when evaluating to discard a PDCP SDU instead of (re)transmitting it.

[0162] In one or more embodiments, for example, the target NG-RAN node (network node 16b) does not pre-process PDCP PDUs from the PDCP SDU until the handover abort time has elapsed, and then evaluates whether the PDCP SDU should be discarded based on the elapsed time instead of being transmitted or retransmitted. This may also avoid discarding certain PDCP PDUs already generated based on SDUs that create gaps in the SN sequence. This may further prevent any RLC PDUs from this PDCP PDU from being submitted to lower layers for transmission (e.g., due to an early UL grant from the target network node 16b) and therefore cannot be discarded as needed.

[0163] In one exemplary embodiment of the evaluation at the target network node 16b, the target network node 16b considers the congestion state of its radio resources. If there are many wireless devices 22 to be served, it is unlikely that an incoming PDCP SDU will be transmitted immediately. Furthermore, it may take some time for the target network node 16b to successfully transmit the SDU to the wireless device 22, for example, using HARQ / RLC retransmission. In other words, the target network node 16b considers the expected time to start transmitting this PDCP SDU and the expected time for successful transmission of this PDCP SDU.

[0164] In another implementation example of evaluation at the target network node 16b, if a data PDU (e.g., a PDCP SDU) is associated, for example, by an application data unit (ADU), the source RAN (source network node 16a) may calculate or transmit a reference time and this information to the target network node 16b. The target network node 16b can use this information to decide to discard the PDCP SDU. In one exemplary embodiment, if one important data PDU (e.g., an I-frame in a video) is discarded by the target network node 16b due to an inability to deliver it on time, the target network node 16b also discards other data PDUs (e.g., B-frames and / or P-frames). In yet another example, if the target network node 16b is faced with a choice of being able to deliver only one of three frames, it selects the I-frame instead of the B-frame or P-frame.

[0165] In some embodiments, after evaluation, the target network node 16b may need to discard all PDCP SDUs forwarded from the source network node 16a, which means that receiving downlink data makes little sense, and the target network node 16b may decide to reject the downlink data forwarding tunnel from the source network node 16a.

[0166] The sequence of the above embodiment is shown in FIG. 15, which illustrates an example flowchart and signaling diagram for DL ​​data discarding in some embodiments of the present disclosure. In step S200, the wireless device 22 transmits a measurement report to the source network node 16a (serving NG-RAN). In step S202, the source network node 16a decides to perform a handover and collects information about PDCP SDUs that need to be forwarded. In step S204, the source network node 16a transmits a handover request (including PDCP SDU timing information, such as a timestamp and a configured discard time) to the target network node 16b (target NG-RAN). In step S206, the target network node 16b stores the PDCP SDU timing information and uses it when determining how to handle data forwarding and discards PDCP resources (e.g., PDCP SDUs, PDCP PDUs, etc.). In step S208, the target network node 16b (target NG-RAN) sends a handover request acknowledgement to the source network node 16a (serving NG-RAN).

[0167] A similar approach can be applied to QoS flow offload when a service needs to be offloaded to another network node 16, for example, another gNB-DU.

[0168] In the case of signaling between network nodes 16, in embodiments of the present disclosure, the signaling may be performed via a control plane (eg, XnAP, F1AP) and / or a user plane.

[0169] An example of a control plane solution is shown in exemplary Table 2 below, which is an example of introducing PDCP PDU time information into the data forwarding / offload information from the source NG-RAN node IE in the handover request message. TIFF2025537534000003.tif240170

[0170] Forwarding and offloading information from the source NG-RAN node information element (IE) in the handover request message

[0171] An exemplary embodiment of PDCP SDU timer information is shown in Table 3 below. TIFF2025537534000004.tif138170

[0172] In some embodiments, the "PDCP SDU time" related information may be included in other messages, such as in the "DRB List to State Transfer" IE in the "SN State Transfer" message. The target NG-RAN node (network node 16b) may rely on the timer information, if included in the handover request message, to decide whether or not it needs to set up a data forwarding tunnel. In some cases, it may be beneficial to ensure that the target NG-RAN node (network node 16b) processes only outstanding downlink data.

[0173] An example of a user plane solution is shown in Table 4 below. TIFF2025537534000005.tif195170

[0174] Uplink data discarded In some embodiments, wireless device 22 receives an indication from the network up to which PDCP sequence numbers (SNs) wireless device 22 may discard PDCP SDUs and PDCP PDUs. The sequence numbers may include those assigned by wireless device 22 and PDCP PDUs submitted for transmission at lower layers at source network node 16a.

[0175] For example, in some embodiments, if wireless device 22 is assigned sequence number X and receives an indication to discard PDCP SDUs up to sequence number X+5, wireless device 22 may discard SDUs with sequence number X and / or discard future arriving PDCP SDUs from higher layers with SNs typically assigned as X+1, X+2, X+3, X+4, X+5.

[0176] In one variant, wireless device 22 may discard PDCP SDU X and future arriving PDCP SDUs X+1..X+5. However, for the next arriving PDCP SDU, wireless device 22 does not introduce a PDCP SN gap. In other words, no PDCP SN gap may be introduced with this discard, i.e., the PDCP PDU following this discard shall have the next sequence number of the PDCP PDU before this discard.

[0177] In one exemplary scenario, the embodiment assumes that wireless device 22 is configured with a discard timer for each PDCP SDU that is in operation during handover. What network node 16a and / or network node 16b indicate to wireless device 22 is any additional information regarding SDU discard that is not covered by the PDCP discard timer.

[0178] In one exemplary embodiment, the indication may be sent from the target network node 16b along with a PDCP control PDU, for example, including a PDCP status report, indicating that the network (i.e., the target network node 16b) has received the PDCP SDU up to the above SN.

[0179] In one related embodiment, the source network node 16a includes information regarding when to expect the subsequent UL PDCP SDU, for example: At time t_x, SN=X At time t_x1, SN=X+1 · At time t_x2, SN = X + 2

[0180] The information may be included in a handover request message from the source network node 16a to the target network node 16b. Based on the timing information, the target network node 16b determines which PDCP SDUs should be discarded. For example, if the current time at the target network node 16b is t_y and t_x < t_y < t_x1, the target network node 16b indicates to the wireless device 22 to discard the PDCP SDU with SN = X. The target network node 16b may also indicate to the wireless device 22 to discard the PDCP SDU with SN = X + 1 if t_y is very close to t_x1 and thus the target network node 16b cannot allocate sufficient resources for the wireless device 22 to deliver the PDCP SDU.

[0181] Based on the time when the target network node 16b receives the RRC RRCReconfigurationComplete message, the target network node 16b knows which PDCP SDUs can be discarded (i.e., are not useful).

[0182] In one embodiment for the implementation of the wireless device 22, the wireless device 22 does not preprocess the PDCP SDUs into PDCP PDUs during handover, i.e., as described above, it waits until the handover interruption time has passed, based on the indication provided by the network (e.g., network node 16a and / or network node 16b). By waiting for potential discarding after handover, the wireless device 22 can avoid the need to wastefully preprocess the PDCP PDUs again to avoid SN gaps due to discarding.

[0183] In an exemplary embodiment, the implementation of network node 16a (or network node 16b) ensures that RLC SDUs / PDUs are not submitted for transmission at lower layers (to avoid data from being discarded). In one example, network node 16a and / or network node 16b may avoid allocating an UL grant for transmission until a PDCP status report is successfully received by wireless device 22.

[0184] The sequence of the above embodiments is shown in FIG. 16, which illustrates a flowchart and signaling diagram for UL data discarding according to some embodiments of the present disclosure. In step S300, the source network node 16a performs handover by transmitting information regarding UL PDCP SDU SN / time to the target network node 16b. In step S302, the source network node 16a transmits a handover command over RRC to the wireless device 22. In step S304, the wireless device 22 performs random access signaling (e.g., message exchange) with the target network node 16b. In step S306, the wireless device 22 transmits an RRC message, RRCReconfigurationComplete, to the target network node 16b. In step S308, the target network node 16b calculates which UL PDCP SDUs to discard. In step S310, the target network node 16b indicates to the wireless device 22 to discard the PDCP SDUs.

[0185] In some exemplary embodiments, the indication (i.e., an indication of up to which PDCP sequence numbers (SNs) the wireless device 22 will discard PDCP SDUs and PDCP PDUs) is transmitted from the source network node 16a and is included, for example, in an RRCReconfiguration message that includes a handover command or a PDCP status report prior to the handover command. The source network node 16a may take into account the expected handover latency from the source network node 16a to the target network node 16b when indicating which SNs to discard.

[0186] The expected handover latency may be estimated in advance, for example, by network node 16a, network node 16b, etc. In some embodiments, the indication (i.e., an indication of up to which PDCP sequence number (SN) wireless device 22 will discard PDCP SDUs and PDCP PDUs) may be included in an RRC message sent from target network node 16b after wireless device 22 sends an RRCConfigurationComplete message to target network node 16b.

[0187] The following is a non-limiting list of exemplary embodiments:

[0188] Embodiment A1: a wireless device (WD) and a target network node configured to communicate with the source network node, the target network node comprising: receiving a handover request from a source network node, the handover request including Packet Data Convergence Protocol (PDCP) timing information associated with at least one PDCP packet; receiving at least one PDCP packet from a source network node; determining at least one action for the PDCP packet based on the PDCP timing information; Optionally, in response to the received handover request, sending a handover request acknowledgement to the source network node. a target network node configured to perform the above and / or comprising a wireless interface and / or processing circuitry configured to perform the above.

[0189] Embodiment A2: PDCP timing information is the first time a PDCP packet becomes available for transmission at the source network node; a second time when the PDCP packet discard timer expires, and / or The third time the Active Queue Management (AQM) mechanism triggers the dropping of PDCP packets The target network node of embodiment A1, including at least one of:

[0190] Embodiment A3: At least one action for the PDCP packet is forwarding the PDCP packets to the wireless device; and Discarding PDCP packets The target network node of embodiment A2, including one of:

[0191] Embodiment A4: The target network node of embodiment A3, wherein discarding the PDCP packet is based on expiration of a discard timer for the PDCP packet.

[0192] Embodiment A5: PDCP packet discarding determining an importance metric associated with the PDCP packet; discarding at least one additional PDCP packet based on the importance metric exceeding a threshold; The target network node of embodiment A3 or A4, comprising:

[0193] Embodiment A6: Determining at least one action for the PDCP packet includes: a fourth time when the target network node is expected to begin transmitting PDCP packets; and The fifth time when the target network node is expected to finish transmitting the PDCP packet. The target network node of any one of embodiments A1 to A5, further based on at least one of:

[0194] Embodiment B1: 1. A method implemented in a target network node, the method comprising: receiving a handover request from a source network node, the handover request including Packet Data Convergence Protocol (PDCP) timing information associated with at least one PDCP packet; receiving at least one PDCP packet from a source network node; determining at least one action for the PDCP packet based on the PDCP timing information; Optionally, in response to the received handover request, sending a handover request acknowledgement to the source network node. A method comprising:

[0195] Embodiment B2: PDCP timing information is the first time a PDCP packet becomes available for transmission at the source network node; a second time when the PDCP packet discard timer expires, and / or The third time the Active Queue Management (AQM) mechanism triggers the dropping of PDCP packets The method of embodiment B1, comprising at least one of:

[0196] Embodiment B3: At least one action for the PDCP packet is forwarding the PDCP packets to the wireless device; and Discarding PDCP packets The method of embodiment B2, comprising one of:

[0197] Embodiment B4: The method of embodiment B3, wherein discarding the PDCP packet is based on expiration of a discard timer for the PDCP packet.

[0198] Embodiment B5: PDCP packet discarding determining an importance metric associated with the PDCP packet; discarding at least one additional PDCP packet based on the importance metric exceeding a threshold; The method of embodiment B3 or B4, comprising:

[0199] Embodiment B6: Determining at least one action for the PDCP packet includes: a fourth time when the target network node is expected to begin transmitting PDCP packets; and The fifth time when the target network node is expected to finish transmitting the PDCP packet. The method of any one of embodiments B1 to B5, further based on at least one of:

[0200] Embodiment C1: A wireless device (WD) configured to communicate with a source network node and a target network node, the WD comprising: performing a handover procedure from a source network node to a target network node, the target network node being configured by the source network node using PDCP timing information; receiving an indication from the target network node to discard at least one PDCP packet based on the PDCP timing information; optionally, discarding at least one PDCP packet based on the indication; A wireless device (WD) configured to perform and / or comprising a radio interface and / or processing circuitry configured to perform.

[0201] Embodiment C2: the indication to discard at least one PDCP packet includes an indicated sequence number (SN); Discarding at least one PDCP packet discarding the first PDCP packet; The WD of embodiment C1, including discarding at least one subsequent PDCP packet based on the indicated SN being greater than or equal to a subsequent SN of the at least one subsequent PDCP packet.

[0202] Embodiment C3: The WD of embodiment C2, wherein the WD is further configured to assign a new SN to at least one non-dropped PDCP packet following at least one subsequent PDCP packet, the new SN being contiguous with a previous SN of a previous PDCP packet received before the first PDCP packet.

[0203] Embodiment D1: 1. A method implemented in a wireless device (WD), the method comprising: performing a handover procedure from a source network node to a target network node, the target network node being configured by the source network node using PDCP timing information; receiving an indication from the target network node to discard at least one PDCP packet based on the PDCP timing information; optionally, discarding at least one PDCP packet based on the indication; A method comprising:

[0204] Embodiment D2: the indication to discard at least one PDCP packet includes an indicated sequence number (SN); Discarding at least one PDCP packet Discarding the first PDCP packet; The method of embodiment D1, including discarding the at least one subsequent PDCP packet based on the indicated SN being greater than or equal to a subsequent SN of the at least one subsequent PDCP packet.

[0205] Embodiment D3: The method of embodiment D2, further comprising assigning a new SN to at least one non-dropped PDCP packet following the at least one subsequent PDCP packet, the new SN being contiguous with a previous SN of a previous PDCP packet received before the first PDCP packet.

[0206] As will be appreciated by those skilled in the art, the concepts described herein may be embodied as methods, data processing systems, computer program products, and / or computer storage media storing executable computer programs. Accordingly, the concepts described herein may take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects, all of which are generally referred to herein as “circuits” or “modules.” Any process, step, action, and / or function described herein may be performed by and / or associated with a corresponding module, which may be implemented in software and / or firmware and / or hardware. Furthermore, the present disclosure may take the form of a computer program product on a tangible computer-usable storage medium having computer program code embodied in the medium that can be executed by a computer. Any suitable tangible computer-readable medium may be utilized, including a hard disk, a CD-ROM, an electronic storage device, an optical storage device, or a magnetic storage device.

[0207] Some embodiments are described herein with reference to flowchart illustrations and / or block diagrams of methods, systems, and computer program products. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general-purpose computer (to thereby create a special-purpose computer), a special-purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via a processor of the computer or other programmable data processing apparatus, create means for performing the functions / acts specified in one or more blocks of the flowchart illustrations and / or block diagrams.

[0208] These computer program instructions may also be stored in a computer-readable memory or storage medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture that includes instruction means that implement the functions / acts specified in one or more blocks of the flowcharts and / or block diagrams.

[0209] Computer program instructions may also be loaded into a computer or other programmable data processing apparatus and cause a series of operational steps to be executed on the computer or other programmable apparatus, creating a computer-implemented process, such that the instructions executing on the computer or other programmable apparatus provide steps for implementing the functions / operations specified in one or more blocks of the flowcharts and / or block diagrams.

[0210] It should be understood that the functions / acts noted in the blocks may occur in a different order than that noted in the operational diagrams. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending on the functions / acts involved. While some of the figures include arrows on communication paths to indicate the primary direction of communication, it should be understood that communication may occur in a direction opposite to that of the depicted arrow.

[0211] Computer program code for carrying out operations of the concepts described herein may be written in an object-oriented programming language such as Python, Java, or C++. However, computer program code for carrying out operations of the present disclosure may also be written in conventional procedural programming languages ​​such as the "C" programming language. The program code may run entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer. In the latter scenario, the remote computer may be connected to the user's computer via a local area network (LAN) or wide area network (WAN), or a connection to an external computer may be made (e.g., via the Internet using an Internet Service Provider).

[0212] Many different embodiments have been disclosed herein in connection with the above description and drawings. It is understood that literally describing and illustrating every combination and subcombination of these embodiments would be overly repetitive and confusing. Accordingly, all embodiments can be combined in any manner and / or combination, and the specification, including the drawings, shall be construed as constituting a complete written description of every combination and subcombination of the embodiments described herein, and of the methods and processes for making and using them, and shall support claims to any such combination or subcombination.

[0213] Abbreviations that may be used in the foregoing description include the following: xR Extended Reality VR Virtual Reality AR Augmented Reality MR Mixed Reality TTI Transmission Time Interval Fps Frames per second PDU Protocol Data Unit QFI QoS Flow ID QoS Quality of Service SMF Session Management Facility PDR Packet Detection Rule PDU Protocol Data Unit SDU Service Data Unit PDCP Packet Data Convergence Protocol RLC Radio Link Control

[0214] Those skilled in the art will appreciate that the present invention is not limited to what has been particularly shown and described hereinabove. Further, unless stated to the contrary, it should be noted that all of the accompanying drawings are not to scale. Various modifications and variations are possible in light of the above teachings without departing from the scope and spirit of the present invention, which is limited only by the following claims.

Claims

1. A source network node (16a) configured to communicate with a wireless device (WD) (22) and a target network node (16b), said source network node (16a) comprising: obtaining timing information associated with Packet Data Convergence Protocol (PDCP) resources, the PDCP resources corresponding to packets scheduled for downlink transmission from the source network node (16a) or uplink transmission from the WD (22); After a handover request is sent by the source network node (16a), sending the timing information associated with the PDCP resource to the target network node (16b), so that the target network node (16b) determines whether to discard the PDCP resource or the packet based on the timing information, or have the WD (22) discard the PDCP resource or the packet; a source network node (16a) configured to:

2. The timing information associated with the PDCP resource includes: When the PDCP resources become available for transmission at the source network node (16a), When the discard timer of the PDCP resource times out, When an active queue management (AQM) process triggers the dropping of the PDCP resource, When the source network node (16a) anticipates subsequent uplink PDCCP resources, PDCP Protocol Data Unit (PDU) time information in data forwarding and offloading information associated with an information element in the handover request; PDCP PDU timestamp, PDCP discard timer, and The PDCP PDU time information included in the report list 2. The source network node (16a) of claim 1, comprising one or more of:

3. The source network node (16a) The source network node (16a) of claim 1 or 2, further configured to decide whether to perform a handover of the WD (22) from the source network node (16a) to the target network node (16b) based on a measurement report.

4. The source network node (16a) The source network node (16a) of any one of claims 1 to 3, further configured to send the handover request to the target network node (16b) or the WD (22).

5. The source network node (16a) The source network node (16a) of any one of claims 1 to 4, further configured to transmit the PDCP resources to the target network node (16b).

6. The source network node (16a) according to any one of claims 1 to 5, wherein said timing information is included in said handover request.

7. The source network node (16a) 7. The source network node (16a) of claim 1, further configured to determine that when the source network node (16a) or the WD (22) transmits the PDCP resource or the packet, it is unable to meet a timing condition associated with the timing information.

8. The source network node (16a) 8. The source network node (16a) of claim 7, further configured to transmit at least the timing information in response to the determination that the timing condition cannot be met.

9. 9. The source network node (16a) of claim 1, wherein the PDCP resources are one or both of a PDCP PDU and a PDCP Service Data Unit (SDU).

10. The source network node (16a) of any one of claims 1 to 9, wherein the packets comprise DL or UL data.

11. 1. A method in a source network node (16a) configured to communicate with a wireless device (WD) (22) and a target network node (16b), said method comprising: Obtaining timing information associated with Packet Data Convergence Protocol (PDCP) resources, the PDCP resources corresponding to packets scheduled for downlink transmission from the source network node (16a) or uplink transmission from the WD (22) (S148); After a handover request is sent by the source network node (16a), the target network node (16b) sends the timing information associated with the PDCP resource to the target network node (16b), so that the target network node (16b) determines whether to discard the PDCP resource or the packet based on the timing information, or have the WD (22) discard the PDCP resource or the packet (S150); A method comprising:

12. The timing information associated with the PDCP resource includes: When the PDCP resources become available for transmission at the source network node (16a), When the discard timer of the PDCP resource times out, When an active queue management (AQM) process triggers the dropping of the PDCP resource, When the source network node (16a) anticipates subsequent uplink PDCCP resources, PDCP Protocol Data Unit (PDU) time information in data forwarding and offloading information associated with an information element in the handover request; PDCP PDU timestamp, PDCP discard timer, and The PDCP PDU time information included in the report list The method of claim 11 , comprising one or more of:

13. The method comprises:

13. The method of claim 11 or 12, further comprising: determining whether to perform a handover of the WD (22) from the source network node (16a) to the target network node (16b) based on a measurement report.

14. The method comprises: The method of any one of claims 11 to 13, further comprising transmitting the handover request to the target network node (16b) or the WD (22).

15. The method comprises:

15. The method of any one of claims 11 to 14, further comprising transmitting the PDCP resources to the target network node (16b).

16. The method of claim 11 , wherein the timing information is included in the handover request.

17. The method comprises:

17. The method of claim 11, further comprising determining that a timing condition associated with the timing information cannot be met when the source network node (16a) or the WD (22) transmits the PDCP resource or the packet.

18. The method comprises:

18. The method of claim 17, further comprising transmitting at least the timing information in response to the determination that the timing condition cannot be met.

19. 19. The method of claim 11, wherein the PDCP resource is one or both of a PDCP PDU and a PDCP Service Data Unit (SDU).

20. 20. The method of claim 11, wherein the packets include DL or UL data.

21. a wireless device WD (22) and a target network node (16b) configured to communicate with a source network node (16a), said target network node (16b) comprising: receiving, from the source network node (16a), timing information associated with Packet Data Convergence Protocol (PDCP) resources, the PDCP resources corresponding to packets scheduled for downlink transmission from the source network node (16a) or uplink transmission from the WD (22); After a handover request is sent by the source network node (16a), determining whether to discard or have the WD (22) discard the PDCP resource or the packet based on the timing information; Based on the determination, one of discarding the PDCP resource or the packet, or having the WD (22) discard the PDCP resource or the packet; a target network node (16b) configured to:

22. The timing information associated with the PDCP resource includes: When the PDCP resources become available for transmission at the source network node (16a), When the discard timer of the PDCP resource times out, When an active queue management (AQM) process triggers the dropping of the PDCP resource, When the source network node (16a) anticipates subsequent uplink PDCCP resources, PDCP Protocol Data Unit (PDU) time information in data forwarding and offloading information associated with an information element in the handover request; PDCP PDU timestamp, PDCP discard timer, and The PDCP PDU time information included in the report list 22. The target network node (16b) of claim 21, comprising one or more of:

23. The target network node (16b) 23. The target network node (16b) of claim 21 or 22, further configured to: transmit the PDCP resource or the packet or cause the WD (22) to transmit based on the determination.

24. The target network node (16b) 24. The target network node (16b) of any one of claims 21 to 23, further configured to receive the handover request from the source network node (16a).

25. The target network node (16b) according to any one of claims 21 to 24, wherein said timing information is included in said handover request.

26. The target network node (16b) 26. The target network node (16b) of any one of claims 21 to 25, further configured to determine that when the target network node (16b) or the WD (22) transmits the PDCP resource or the packet, it is not possible to meet a timing condition associated with the timing information.

27. The target network node (16b) 27. The target network node (16b) of claim 26, further configured to determine whether to discard, or have the WD (22) discard, the PDCP resource or the packet further based on the determination that the timing condition cannot be met.

28. The WD (22) discards the 28. The target network node (16b) of any one of claims 21 to 27, comprising sending an indication to the WD (22) to discard the PDCP resource or the packet.

29. 29. The target network node (16b) of any one of claims 21 to 28, wherein the PDCP resources are one or both of PDCP PDUs and PDCP Service Data Units (SDUs).

30. 30. The target network node (16b) of any one of claims 21 to 29, wherein the packets comprise DL or UL data.

31. 1. A method in a wireless device WD (22) and a target network node (16b) configured to communicate with a source network node (16a), said method comprising: receiving timing information associated with Packet Data Convergence Protocol (PDCP) resources from the source network node (16a), the PDCP resources corresponding to packets scheduled for downlink transmission from the source network node (16a) or uplink transmission from the WD (22); After a handover request is sent by the source network node (16a), determining whether to discard the PDCP resource or the packet or to have the WD (22) discard the PDCP resource or the packet based on the timing information (S154); Based on the determination, one of discarding the PDCP resource or the packet or having the WD (22) discard the PDCP resource or the packet (S156); A method comprising:

32. The timing information associated with the PDCP resource includes: When the PDCP resources become available for transmission at the source network node (16a), When the discard timer of the PDCP resource times out, When an active queue management (AQM) process triggers the dropping of the PDCP resource, When the source network node (16a) anticipates subsequent uplink PDCCP resources, PDCP Protocol Data Unit (PDU) time information in data forwarding and offloading information associated with an information element in the handover request; PDCP PDU timestamp, PDCP discard timer, and The PDCP PDU time information included in the report list 32. The method of claim 31 , comprising one or more of:

33. The method comprises:

33. The method of claim 31 or 32, further comprising one of transmitting or causing the WD (22) to transmit the PDCP resource or the packet based on the determination.

34. The method comprises:

34. The method of any one of claims 31 to 33, further comprising receiving the handover request from the source network node (16a).

35. 35. The method of any one of claims 31 to 34, wherein the timing information is included in the handover request.

36. The method comprises:

36. The method of claim 31, further comprising determining that the target network node (16b) or the WD (22) cannot meet a timing condition associated with the timing information when transmitting the PDCP resource or the packet.

37. The method comprises:

37. The method of claim 36, further comprising: determining whether to discard, or have the WD (22) discard, the PDCP resource or the packet further based on the determination that the timing condition cannot be met.

38. The WD (22) discards the 38. The method of any one of claims 31 to 37, comprising sending an indication to the WD (22) to discard the PDCP resource or the packet.

39. 39. The method of any one of claims 31 to 38, wherein the PDCP resource is one or both of a PDCP PDU and a PDCP service data unit (SDU).

40. 40. The method of any one of claims 31 to 39, wherein the packets include DL or UL data.

41. A wireless device WD (22) configured to communicate with a source network node (16a) and a target network node (16b), said WD (22) comprising: performing a handover of the WD (22) from the source network node (16a) to the target network node (16b), wherein the target network node (16b) has received timing information from the source network node (16a) associated with Packet Data Convergence Protocol (PDCP) resources, the PDCP resources corresponding to packets scheduled for downlink transmission from the source network node (16a) or uplink transmission from the WD (22); receiving an indication from the target network node (16b) to discard the PDCP resource or the packet, the indication being sent based on the timing information; discarding the PDCP resource or the packet based on the indication; The wireless device WD (22) is configured to perform the following:

42. The indication includes a sequence number (SN), and the WD (22) is 42. The WD (22) of claim 41, further configured to discard the PDCP resource or the packet based on the SN.

43. Revoke the PDCP resource based on the SN, 43. The WD (22) of claim 42, comprising discarding other PDCP resources up to the SN.

44. The WD (22) is 44. The WD (22) of any one of claims 41 to 43, further configured to stop pre-processing of PDCP resources during the handover based on said indication.

45. The WD (22) is transmitting a first message indicating that radio resource control (RRC) configuration is complete; receiving a second message from the target network node (16b) in response to the first message, the second message being an RRC message and including the indication; 45. The WD (22) of any one of claims 41 to 44, further configured to:

46. 46. ​​The WD (22) of any one of claims 41 to 45, wherein the PDCP resource is one or both of a PDCP PDU and a PDCP Service Data Unit (SDU).

47. 47. The WD (22) of any one of claims 41 to 46, wherein the packets include DL data or UL data.

48. 1. A method in a wireless device WD (22) configured to communicate with a source network node (16a) and a target network node (16b), said method comprising: performing a handover of the WD (22) from the source network node (16a) to the target network node (16b), wherein the target network node (16b) has received timing information associated with Packet Data Convergence Protocol (PDCP) resources from the source network node (16a), the PDCP resources corresponding to packets scheduled for downlink transmission from the source network node (16a) or uplink transmission from the WD (22); and performing the handover (S158). receiving (S160) an indication from the target network node (16b) to discard the PDCP resource or the packet, the indication being sent based on the timing information; Discarding the PDCP resource or the packet based on the indication (S162); A method comprising:

49. The indication includes a sequence number (SN), and the method further comprises:

49. The method of claim 48, further comprising discarding the PDCP resource or the packet based on the SN.

50. Revoke the PDCP resource based on the SN, 50. The method of claim 49, comprising discarding other PDCP resources up to the SN.

51. The method comprises:

51. The method of any one of claims 48 to 50, further comprising: stopping pre-processing of PDCP resources during the handover based on the indication.

52. The method comprises: transmitting a first message indicating that radio resource control (RRC) configuration is complete; receiving a second message from the target network node (16b) in response to the first message, the second message being an RRC message and including the indication; 52. The method of any one of claims 48 to 51, further comprising:

53. 53. The method of any one of claims 48 to 52, wherein the PDCP resource is one or both of a PDCP PDU and a PDCP Service Data Unit (SDU).

54. 54. The method of any one of claims 48 to 53, wherein the packets include DL or UL data.

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