WO2025241076A1

WO2025241076A1 - Low importance data discard

Info

Publication number: WO2025241076A1
Application number: PCT/CN2024/094312
Authority: WO
Inventors: Chunli Wu; Benoist Pierre Sebire; Sunyoung Lee; Claudio Rosa; Henri Markus Koskinen
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy; Nokia Technologies Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy; Nokia Technologies Oy
Priority date: 2024-05-20
Filing date: 2024-05-20
Publication date: 2025-11-27
Anticipated expiration: 2026-11-20

Abstract

Example embodiments of the present disclosure are directed to methods, devices, apparatuses and computer readable storage medium for low importance data discard. In a method, a first apparatus, in accordance with a determination that a discarding condition is met, identifies a first data unit that arrived in a buffer before a second data unit and is associated with a first discarding timer that is running. The first data unit is of a first importance and the second data unit is of a second importance higher than the first importance. The first apparatus then discards the first data unit from the buffer before the first discarding timer expires.

Description

LOW IMPORTANCE DATA DISCARD

FIELD

Various example embodiments of the present disclosure generally relate to the field of telecommunication and in particular, to methods, devices, apparatuses and computer readable storage medium for low importance data discard.

BACKGROUND

With developments in 5G network technologies, a new approach has been introduced to achieve advancements in eXtended Reality (XR) and network traffic management, and the need to prioritize critical data leads to the exploration of selective data discard strategies. With Delay Status Report (DSR) and Protocol Data Unit (PDU) Set Importance (PSI) based discard approaches, resources can be efficiently managed by identifying and discarding low-importance data. Therefore, it is worth studying DSR and PSI-based discard approaches to enhance network efficiency and XR application performance, and improve the overall management of network traffic and resource allocation.

SUMMARY

In a first aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: in accordance with a determination that a discarding condition is met, identify a first data unit arrived in a buffer before a second data unit and associated with a first discarding timer that is running, wherein the first data unit is of a first importance and the second data unit is of a second importance higher than the first importance; and discard the first data unit from the buffer before the first discarding timer expires.

In a second aspect of the present disclosure, there is provided a second apparatus. The second apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus at least to: transmit, to a first apparatus, configuration information indicating whether discarding of a data unit of a first importance is enabled, wherein the data unit is in a buffer at least comprising a first data unit arrived before a second data unit and associated with a first discarding timer that is running, wherein the first data unit is of the first importance and the second data unit is of a second importance.

In a third aspect of the present disclosure, there is provided a method. The method comprises: in accordance with a determination that a discarding condition is met, identifying a first data unit arrived in a buffer before a second data unit and associated with a first discarding timer that is running, wherein the first data unit is of a first importance and the second data unit is of a second importance higher than the first importance; discarding the first data unit from the buffer before the first discarding timer expires.

In a fourth aspect of the present disclosure, there is provided a method. The method comprises: transmitting, to a first apparatus, configuration information indicating whether discarding of a data unit of a first importance is enabled, wherein the data unit is in a buffer at least comprising a first data unit arrived before a second data unit and associated with a first discarding timer that is running, wherein the first data unit is of the first importance and the second data unit is of a second importance.

In a fifth aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises means for in accordance with a determination that a discarding condition is met, identifying a first data unit arrived in a buffer before a second data unit and associated with a first discarding timer that is running, wherein the first data unit is of a first importance and the second data unit is of a second importance higher than the first importance; means for discarding the first data unit from the buffer before the first discarding timer expires.

In a sixth aspect of the present disclosure, there is provided a second apparatus. The second apparatus comprises means for transmitting, to a first apparatus, configuration information indicating whether discarding of a data unit of a first importance is enabled, wherein the data unit is in a buffer at least comprising a first data unit arrived before a second data unit and associated with a first discarding timer that is running, wherein the first data unit is of the first importance and the second data unit is of a second importance.

In a seventh aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the third aspect.

In an eighth aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the fourth aspect.

It is to be understood that the Summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Some example embodiments will now be described with reference to the accompanying drawings, where:

FIG. 1 illustrates an example communication environment in which example embodiments of the present disclosure can be implemented;

FIG. 2 illustrates a schematic diagram of a problem with low-importance non-delay critical data ahead of delay-critical data;

FIG. 3 illustrates a signaling flow of communication between a first apparatus and second apparatus in accordance with some example embodiments of the present disclosure;

FIG. 4 illustrates a schematic diagram of comparing time duration of different data units in accordance with some example embodiments of the present disclosure;

FIG. 5 illustrates a flowchart of a communication method implemented at a first apparatus in accordance with some example embodiments of the present disclosure;

FIG. 6 illustrates a flowchart of a communication method implemented at a second apparatus in accordance with some example embodiments of the present disclosure;

FIG. 7 illustrates a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure; and

FIG. 8 illustrates a block diagram of an example computer readable medium in accordance with some example embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principles of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. Embodiments described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

References in the present disclosure to “one embodiment, ” “an embodiment, ” “an example embodiment, ” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that although the terms “first, ” “second, ” …, etc. in front of noun (s) and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another and they do not limit the order of the noun (s) . For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

As used herein, “at least one of the following: <a list of two or more elements>” and “at least one of <a list of two or more elements>” and similar wording, where the list of two or more elements are joined by “and” or “or” , mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

As used herein, unless stated explicitly, performing a step “in response to A” does not indicate that the step is performed immediately after “A” occurs and one or more intervening steps may be included.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.

As used in this application, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable) :

(i) a combination of analog and/or digital hardware circuit (s) with software/firmware and

(ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

As used herein, the term “communication network” refers to a network following any suitable communication standards, such as New Radio (NR) , Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) , 5.5G, the sixth generation (6G) communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP) , for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , an NR NB (also referred to as a gNB) , a Remote Radio Unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a relay, an Integrated Access and Backhaul (IAB) node, a low power node such as a femto, a pico, a non-terrestrial network (NTN) or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, an aircraft network device, and so forth, depending on the applied terminology and technology. In some example embodiments, radio access network (RAN) split architecture comprises a Centralized Unit (CU) and a Distributed Unit (DU) at an IAB donor node. An IAB node comprises a Mobile Terminal (IAB-MT) part that behaves like a UE toward the parent node, and a DU part of an IAB node behaves like a base station toward the next-hop IAB node.

The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE) , a Subscriber Station (SS) , a Portable Subscriber Station, a Mobile Station (MS) , or an Access Terminal (AT) . The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA) , portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , USB dongles, smart devices, wireless customer-premises equipment (CPE) , an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD) , a vehicle, a drone, a medical device and applications (e.g., remote surgery) , an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts) , a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. The terminal device may also correspond to a Mobile Termination (MT) part of an IAB node (e.g., a relay node) . In the following description, the terms “terminal device” , “communication device” , “terminal” , “user equipment” and “UE” may be used interchangeably.

As used herein, the term “resource, ” “transmission resource, ” “resource block, ” “physical resource block” (PRB) , “uplink resource, ” or “downlink resource” may refer to any resource for performing a communication, for example, a communication between a terminal device and a network device, such as a resource in time domain, a resource in frequency domain, a resource in space domain, a resource in code domain, or any other combination of the time, frequency, space and/or code domain resource enabling a communication, and the like. In the following, unless explicitly stated, a resource in both frequency domain and time domain will be used as an example of a transmission resource for describing some example embodiments of the present disclosure. It is noted that example embodiments of the present disclosure are equally applicable to other resources in other domains.

As used herein, the term "XR" refers to eXtended Reality, a broad category encompassing several immersive technologies including Virtual Reality (VR) , Augmented Reality (AR) , and Mixed Reality (MR) . XR technologies integrate digital content with the physical world in a way that creates a new environment where physical and digital objects co-exist and interact in real time.

As used herein, the term "DSR" refers to Delay Status Report, a mechanism in telecommunications used to manage data traffic more effectively by reporting the delay urgency of different data packets within a network. This tool is particularly useful in networks where timely data delivery is crucial, such as in video streaming, gaming, and extended reality (XR) applications.

As used herein, the term "PSI-based discard" refers to a mechanism in telecommunication networks that involves discarding packets based on PDU-Set Importance (PSI) . It is particularly relevant in environments where network resources are constrained and managing traffic efficiently is critical.

As used herein, the term "Logical Channel (LCH) " may refer to a type of channel in cellular networks that deals with the transfer of data between the network and the user equipment (UE) . Logical channels are distinct from physical channels, and Logical channels describe what type of data is being transmitted, rather than the specific radio frequencies or time slots used for the transmission.

As used herein, the term "DRB" refers to Data Radio Bearers, which are essential components in cellular network architectures such as LTE and 5G NR (New Radio) . DRBs are used for the transfer of user plane data between the user equipment (UE) and the network.

As used herein, the term "MAC" refers to Medium Access Control, a sublayer of the data link layer in the network protocol stack. The MAC layer is responsible for managing how data packets are transmitted between devices over a shared communication medium.

As used herein, the term "PDU" refers to Protocol Data Unit, which is a generic term in telecommunications and networking that describes a unit of data specified in a protocol of a given layer. PDUs represent data that includes both the payload and the control information that are required to deliver the payload.

FIG. 1 illustrates an example communication environment 100 in which example embodiments of the present disclosure can be implemented. In the communication environment 100, a plurality of communication devices, including a first apparatus 110 and a second apparatus 120, can communicate with each other. In the example of FIG. 1, the first apparatus 110 may be a UE and the second apparatus 120 may be a base station serving the UE. The serving area of the network device 120 may be called a cell 102.

It is to be understood that the number of devices and their connections shown in FIG. 1 are only for the purpose of illustration without suggesting any limitation. The communication environment 100 may include any suitable number of devices configured to implementing example embodiments of the present disclosure. Although not shown, it would be appreciated that one or more additional devices may be located in the cell 102, and one or more additional cells may be deployed in the communication environment 100. It is noted that although illustrated as a network device, the network device 120 may be another device than a network device. Although illustrated as a terminal device, the first network device 110 may be another device than a terminal device.

In the following, for the purpose of illustration, some example embodiments are described with the first network device 110 operating as a UE and the network device 120 operating as a base station. However, in some example embodiments, operations described in connection with a terminal device may be implemented at a network device or other device, and operations described in connection with a network device may be implemented at a terminal device or other device.

In some example embodiments, a link from the second apparatus 120 to the first apparatus 110 is referred to as a downlink (DL) , while a link from the first apparatus 110 to the second apparatus 120 is referred to as an uplink (UL) . In DL, the second apparatus 120 is a transmitting (TX) device (or a transmitter) and the first apparatus 110 is a receiving (RX) device (or a receiver) . In UL, the first apparatus 110 is a TX device (or a transmitter) and the second apparatus 120 is a RX device (or a receiver) .

Communications in the communication environment 100 may be implemented according to any proper communication protocol (s) , comprising, but not limited to, cellular communication protocols of the first generation (1G) , the second generation (2G) , the third generation (3G) , the fourth generation (4G) , the fifth generation (5G) , 5.5G, the sixth generation (6G) , and the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and/or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA) , Frequency Division Multiple Access (FDMA) , Time Division Multiple Access (TDMA) , Frequency Division Duplex (FDD) , Time Division Duplex (TDD) , Multiple-Input Multiple-Output (MIMO) , Orthogonal Frequency Division Multiple (OFDM) , Discrete Fourier Transform spread OFDM (DFT-s-OFDM) and/or any other technologies currently known or to be developed in the future.

EXtended Reality (XR) applications are characterized by high data rate requirements and relatively small packet delay budget (PDB) . Therefore, low-latency communication is critical for XR applications. Some standardization work such as a release 19 (Rel-19) work item on XR for new radio (NR) agreed the objective of specifying enhancements for scheduling. Delay or deadline information is used in specifying enhancements for the UL, in order to enable high XR capacity for support of UL scheduling while meeting delay requirements or avoiding too late Protocol Data Units (PDUs) . It is noted that Logical Channel Prioritization (LCP) implementation complexity needs to be taken into account when evaluating solutions. In the predefined standard, the focus is on using delay information in UL scheduling, and two potential areas of enhancements have been identified: LCP enhancements and Delay Status Report (DSR) enhancements.

Delay status reporting is configured per Logical Channel Group (LCG) . When DSR reporting is configured, the LCG is configured with a threshold (remainingTimeThreshold-r18) which is used to trigger a DSR, as well to determine the value of the buffer size field in the DSR Medium Access Control Control Element (MAC CE) . Related content in Radio Resource Control (RRC) , MAC and Packet Data Convergence Protocol (PDCP) are reported as the following Tables 1 to 3.

Table 1

Table 2

Table 3

PDU Set Importance (PSI) -based discarding is configured per Data Radio Bearer (DRB) by configuring the parameter DiscardTimerForLowImportance-r18 in the corresponding PDCP configuration (PDCP-Config) . However, discardTimerForLowImportance for a PDCP Service Data Unit (SDU) arriving in the transmission buffer of a DRB with PSI-based discarding configured is only started if PSI-based discarding is also activated. Otherwise, legacy discardTimer is started. Related content in Radio Resource Control (RRC) , MAC and Packet Data Convergence Protocol (PDCP) are reported as the following Tables 4 and 5.

Table 4

Table 5

Therefore, when DiscardTimerForLowImportance-r18 is configured and PSI-based SDU discarding is activated, discardTimer is not started for a PDCP SDU belonging to a low-importance PDU Set. DSR triggering as well as determination of remaining time and buffer size fields in DSR are only based on the value of discardTimer with respect to remainingTimeThreshold-r18. With the exception of RLC AM data PDUs that are pending for retransmission, PDCP SDUs with discardTimerForLowImportance running are neither reported in DSR nor are considered for DSR triggering.

Specifically, FIG. 2 illustrates a schematic diagram of a problem with low-importance non-delay critical data ahead of delay-critical data. As shown, when PSI-based discard is activated, the UE may have low-importance PDUs 204 in front of or ahead of high-importance delay-critical PDUs 202 in the transmission buffer. On the other hand, a DSR only includes information such as buffer size 210 of data for which discardTimer was started, with the exception of RLC AM data PDUs that are pending for retransmission. If the gNB schedules resources 220 to transmit data units reported in the DSR, the resources of the scheduled Transport Block (TB) size 220 may not allow the UE to transmit all high-importance delay-critical data 202.

Only if the durations of discardTimerForLowImportance and discardTimer have a difference which is less than remainingTimeThreshold, e.g. discardTimerForLowImportance being shorter than discardTimer by remainingTimeThreshold or less than remainingTimeThreshold, a PDU for which discardTimerForLowImportance was started can remain non-discarded but ahead of a high-importance delay-critical PDU in the transmission buffer. In some solutions, a way to avoid the problem is to configure parameters discardTimer, remainingTimeThreshold-r18, and DiscardTimerForLowImportance-r18 such that discardTimerForLowImportance and discardTimer have a difference which is greater than remainingTimeThreshold. But this solution may impose unnecessary restrictions to the configured value for DiscardTimerForLowImportance-r18.

The discardTimer is configured to manage and control data units in transmission buffer, and remainingTimeThreshold-r18 is a specific threshold setting for the discardTimer, which represents the remaining time limit below which a data unit is considered delay-critical. The discardTimerForLowImportance is configured to handle data units that are considered low importance, in order to prioritize high-importance data while managing low-importance data differently.

In accordance with some example embodiments of the present disclosure, some of the DSR enhancements for better support of UL delay-aware scheduling are provided. Compared with some conventional solutions, the present disclosure is to discard data units instead of reporting them to reduce resource consumption in case of congestion. If there is no DSR triggered, low importance data is not unnecessarily discarded, or the low importance data is behind the high importance data in buffer so that low importance data still has chance to be transmitted. In addition, the present disclosure is not limited to the case of upon PSI-based activation MAC CE reception. It is also not limited to when the durations of discardTimerForLowImportance and discardTimer have a difference which is greater than remainingTimeThreshold. The present disclosure may potentially improve the overall management of network traffic and resource allocation.

Example embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

FIG. 3 illustrates a signaling flow 300 of communication between a first apparatus and second apparatus in accordance with some example embodiments of the present disclosure. For the purposes of discussion, the signaling flow 300 will be discussed with reference to FIG. 1. The signaling flow 300 involves a first apparatus 110 and a second apparatus 120. For the purpose of illustration, some example embodiments may be described with the first apparatus 110 operating as a terminal device (for example, a UE) and the second apparatus 120 operating as a network device (for example, a gNB) .

In the signaling flow 300, if a discarding condition is met, the first apparatus 110 identifies (3015) a first data unit that has arrived in a buffer before a second data unit and is associated with a first discarding timer that is running, for example, a PDCP SDU with discardTimerForLowImportance running, where the first data unit is of a first importance and the second data unit is of a second importance higher than the first importance. Then the first apparatus 110 discards (3020) the first data unit from the buffer before the first discarding timer expires. In some example embodiments, the first data unit may be discarded from the buffer before the first discarding timer expires, or the first data unit may be discarded in response to that first discarding timer is considered as expired.

In an embodiment, the first apparatus transmits the second data unit in uplink. Thanks to the discarding, the second data unit may thus be transmitted earlier.

In some example embodiments, the first importance may be low importance and the second importance is high importance. In this case, the first data unit may be of low importance and may be called as low importance data or low importance data unit, and the second data unit may be of high importance and may be called as high importance data or high importance data unit. In some cases, the low-importance data may be non-delay critical data. Alternatively, in some cases, it is possible to report it in DSR as delay critical data as well. The importance may be associated with certain quality-of-service criteria, such a latency requirement. The latency requirement may be stricter for the high importance data than for the low importance data. Other communication characteristics may be different for low importance data than for the high importance data.

Optionally, in some example embodiments, at the beginning of the signaling flow 300, the second apparatus 120 transmits (3005) configuration information to the first apparatus 110. The configuration information indicates whether discarding of a data unit of a first importance from a buffer is enabled. In some example embodiments, the configuration information may be transmitted via an uplink grant or a RRC message, or in other suitable ways.

Upon receiving the configuration information, the first apparatus 110 may determine whether discarding of a data unit of the first importance is enabled. According to the determination, for example, if yes, the first apparatus 110 may, in accordance with a determination that a discarding condition is met, proceed with identifying (3015) the first data unit that has arrived in a buffer before the second data unit and is associated with a first discarding timer that is running. Then, the first apparatus 110 may discard (3020) the first data unit before the expiry of the first discarding timer. Such early discarding will move the second data unit towards the front of the buffer which enables faster transmission of the second data unit.

In some example embodiments, the second data unit may be a delay critical data unit. This means that the second data unit is a high importance data unit, and the remaining time of a second discarding timer for the second data unit is shorter than a time threshold. The second discarding timer may be, for example, discardTimer as discussed above, e.g., in Table 5.

In some example embodiments, the first importance may be low importance and the second importance may be high importance. For instance, the first data unit may be a low importance data unit, which is also referred to as low importance data. The second data unit may be a high importance data unit, which is also referred to as high importance data. A data unit may be a PDU, a SDU, or other suitable data block or unit. In some example implementations, the PDU may be a PDCP PDU or a RLC PDU, while the SDU may be a PDCP SDU or a RLC SDU.

In some example embodiments, the discarding condition may be implemented in various ways. For example, one discarding condition may be a condition that a DSR for a Logical Channel (LCH) or a Data Radio Bearer (DRB) is triggered. The LCH/DRB may be the LCH/DRB of the first data unit and/or second data unit. For example, when DSR is triggered or reported for the LCH, the low importance data ahead of delay critical data in the buffer may be discarded early (before the respective timer expires) for the LCH.

Alternatively, or in addition, in some example embodiments, a discarding condition may be defined as a condition that a DSR is pending for a LCH or a DRB. In some examples, if there is a DSR pending for a LCH or a DRB, the low importance data may be discarded.

Alternatively, or in addition, in some example embodiments, another discarding condition may be defined as a condition that a data unit of the second importance in the buffer whose remaining time until expiry of a corresponding discarding timer may become shorter than a time threshold. For example, when a PDCP SDU becomes a delay-critical SDU, the first apparatus 110 may determine that the first data unit discussed above is to be discarded.

As a further alternative, or additionally, in some other example embodiments, the discarding condition may be defined as receiving an uplink (UL) grant from a second apparatus. For example, the first apparatus 110 may receive the uplink grant from the second apparatus 120 and may determine to discard the first data unit based on the uplink grant. For example, when such an UL grant is received, the low importance data ahead of delay critical data in the buffer may be discarded. In this case, the DSR may merely report the high importance data without the low importance data. As an alternative, if there are enough resources, it is possible for the DSR to report the low importance data together with high importance data. As a further alternative, the DSR may report the low importance data and high importance data separately.

In some example embodiments, the uplink grant may comprise a discarding indication. The discarding indication may be an explicit indication indicating that the first data unit is to be discarded. For example, whether the first apparatus 110 is to discard the low importance data may be indicated in the UL grant. If yes, the first apparatus 110 will know that the uplink grant will be used only for high importance data.

In an implementation, if the discarding indication is defined in the UL grant (in downlink control information (DCI) ) , for example, if a bit is set, then the first apparatus 110 may discard the low importance data before delay critical high importance data in the buffer. In addition, the indication may be generalized to work independent of DSR trigger or reporting as well to enable second apparatus 120 to request low importance data discarding.

In some example embodiments, if the uplink grant allows data from a Logical Channel (LCH) to be transmitted, the first apparatus 110 may determine that the first data unit is to be discarded. For example, if the uplink grant allows data from the LCH to be sent, the early discard may occur.

Alternatively, if a resource scheduled by the uplink grant is insufficient for transmitting the first data unit and the second data unit, the first apparatus 110 may determine that the first data unit is to be discarded. In some example embodiments, if the uplink grant size is not large enough to include some or all of the high importance delay critical data, low importance data ahead in the buffer may be discarded early. For example, a threshold may be defined such that some high importance delay critical data is always included. As a result, low importance data ahead in the buffer may be discarded early to allow transmission of at least a minimum amount of high importance data as defined by the threshold .

In some other example embodiments, if an amount of a second data unit that fits in a Medium Access Control (MAC) Protocol Data Unit (PDU) scheduled by the uplink grant is to be reduced by the first unit, the first apparatus 110 may determine that the first data unit is to be discarded. In some examples, if the amount of high importance delay critical data that fits in the MAC PDU scheduled by the grant is to be reduced by low importance data ahead in the buffer, the low importance data is discarded early.

In some example embodiments, the first data unit (s) may exclude a data unit considered for retransmission. In other words, only data units that are first transmissions of respective data PDUs qualify as the first data unit. For example, RLC AM data PDUs considered for retransmission may be reported in DSR regardless of importance. In this case, the early discarding may also include low-importance RLC AM data PDUs that are pending for retransmission, in order to minimize the amount of data that needs to be reported in DSR. In some examples, if low-importance RLC AM data PDUs considered for retransmission have been reported in DSR, for example, if the previous timing option is not adopted, the low-importance data subject to the proposed early discarding may exclude such RLC PDUs.

In some example embodiments, the first apparatus 110 may receive (3010) , from the second apparatus 120, configuration information indicating whether discarding of a data unit of the first importance is enabled. In some example embodiments, a Protocol Data Unit (PDU) Set Importance (PSI) based discard is activated for a Logical Channel (LCH) or a Data Radio Bearer (DRB) . For example, when PSI-based discard is activated, low importance data with low importance discard timer running may be not considered as delay critical data thus not included in the DSR, it is assumed that such data should not consume the resource indicated for the delay critical data either when the second apparatus 120 schedules the first apparatus 110 based on DSR reception.

In some example embodiments, if the first data unit has a sequence number lower than a sequence number (SN) of the second data unit, the first apparatus 110 may determine that the first data unit arrived in the buffer before a second data unit. For example, the determination is based on comparing the SN, such as PDCP SN, RLC SN or PDCP COUNT of the low importance data and high importance data with remaining time below threshold.

Alternatively, in some other example embodiments, if a data arrival time of a first data unit is earlier than a data arrival time of the second data unit, the first apparatus 110 may determine that the first data unit arrived in the buffer before a second data unit. In some examples, the determination is based on the data arrival time in the buffer.

In an embodiment, there may be multiple data units corresponding to the first data unit before the second data unit in the buffer, and the multiple (first) data units may all be subjected to the discarding according to the principles described herein. Applying the discarding to multiple data units with low importance may further expedite transmission of the high importance second data unit. In an embodiment, as shown in FIG. 2, there may be multiple data units corresponding to the second data unit in the buffer.

As a further alternative, if a first time duration in which a first data unit is in the buffer is longer than a second time duration in which the second data unit is in the buffer, the first apparatus 110 may determine that the first data unit arrived in the buffer before the second data unit. The first time duration may be determined based on the first discarding timer and a remaining time of the first discarding timer, and the second time duration may be determined based on the second discarding timer and the remaining time of the second discarding timer. More details related to this embodiment is further discussed with reference to FIG. 4, which illustrates a schematic diagram of comparing time duration of different data units.

As shown in FIG. 4, the first discarding timer 421 is associated with the first data unit 420, and the second discarding timer 411 is associated with the second data unit 410. If a first time duration 422 in which the first data unit 420 is in the buffer is longer than a second time duration 412 in which the second data unit 410 is in the buffer, the first apparatus 110 may determine that the first data unit 420 arrived in the buffer before a second data unit 410.

In an implementation, the first time duration 422 may be determined based on the first discarding timer 427 and a remaining time of the first discarding timer 425, where the first discarding timer 427 is the sum of the remaining time of the first discarding timer 425 and the first time duration 422. Likewise, the second time duration 412 may be determined based on the second discarding timer 417 and a remaining time of the second discarding timer 415, where the second discarding timer 417 is the sum of the remaining time of the second discarding timer 415 and the second time duration 412. In some example embodiments, the determination is based on comparing the remaining time of the low importance data and remaining time of the high importance data with remaining time below threshold.

In addition to the above, the first apparatus 110 may cause transmission of the second data unit. In some example embodiments, the first apparatus 110 may transmit (3025) a DSR indicating at least the second data unit and not indicating the first data unit to the second apparatus 120. Correspondingly, the second apparatus 120 may receive (3030) the DSR from the first apparatus 110.

In view of the above, low-priority data, such as low importance data or the first data unit, may be early discarded (that is, discarded before the expiry of its associated discarding timer) . This early discarding of the low-priority data improves efficient utilization of memory resources of the first apparatus. It may also reduce the amount of required processing because the discarding is made before the expiry of the associated timer. With respect to the embodiments where the DSR is sent and where the second data unit is transmitted, further advantages include expedited transmission of the second data unit that has the higher importance. In this way, it can be ensured that the high importance data will get delivered in a timely manner.

In some example implementations, there may be some options for PDCP, as shown in Table 6 below.

Table 6

From one perspective, the early discarding may logically be understood such that the discardTimerForLowImportance of SDUs is considered as expired when a DSR is triggered and there are delay critical SDUs whose SN are higher and, based on the consideration, the first data unit gets discarded. The considering as expired thus means taking the same actions as when the timer actually expires, , even though the timer has not yet expired.

FIG. 5 shows a flowchart of an example method 500 implemented at a first apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 500 will be described from the perspective of the first apparatus 110 in FIG. 1.

At block 510, in accordance with a determination that a discarding condition is met, the first apparatus 110 identifies a first data unit arrived in a buffer before a second data unit and associated with a first discarding timer that is running, wherein the first data unit is of a first importance and the second data unit is of a second importance higher than the first importance.

At block 520, the first apparatus 110 discards the first data unit from the buffer before the first discarding timer expires.

In some example embodiments, the discarding condition comprises at least one of: a Delay Status Report (DSR) for a Logical Channel (LCH) or a Data Radio Bearer (DRB) is triggered, a DSR is pending for a LCH or a DRB, a remaining time until expiry of a corresponding discarding timer becomes shorter than a time threshold for a data unit of the second importance in the buffer, or an uplink grant is received from a second apparatus.

In some example embodiments, the LCH is a LCH of at least one of the first data unit or the second data unit, and the DRB is a DRB of at least one of the first data unit or the second data unit.

In some example embodiments, the method 500 further comprises: determining to discard the first data unit based on the uplink grant.

In some example embodiments, the method 500 further comprises: in accordance with a determination that the uplink grant allows data from a Logical Channel (LCH) to be transmitted, determining that the first data unit is to be discarded; or in accordance with a determination that a resource scheduled by the uplink grant is insufficient for transmitting the first data unit and the second data unit, determining that the first data unit is to be discarded; or in accordance with a determination that an amount of a second data unit that fits in a Medium Access Control (MAC) Protocol Data Unit (PDU) scheduled by the uplink grant is to be reduced by the first data unit, determining that the first data unit is to be discarded.

In some example embodiments, the first data unit excludes a data unit considered for retransmission.

In some example embodiments, the method 500 further comprises: receiving, from a second apparatus, configuration information indicating whether discarding of a data unit of the first importance is enabled.

In some example embodiments, a Protocol Data Unit (PDU) Set Importance (PSI) based discard is activated for a Logical Channel (LCH) or a Data Radio Bearer (DRB) . In some example embodiments, the LCH is a LCH of at least one of the first data unit or the second data unit, and the DRB is a DRB of at least one of the first data unit or the second data unit.

In some example embodiments, the method 500 further comprises: in accordance with a determination that the first data unit has a sequence number lower than a sequence number of the second data unit, determining that the first data unit arrived in the buffer before a second data unit; or in accordance with a determination that a data arrival time of a first data unit is earlier than a data arrival time of the second data unit, determining that the first data unit arrived in the buffer before the second data unit; or in accordance with a determination that a first time duration in which a first data unit is in the buffer is longer than a second time duration in which the second data unit is in the buffer, determining that the first data unit arrived in the buffer before the second data unit, wherein the first time duration is determined based on the first discarding timer and a remaining time of the first discarding timer, and the second time duration is determined based on the second discarding timer and the remaining time of the second discarding timer.

In some example embodiments, the first apparatus 110 may cause transmission of the second data unit.

In some example embodiments, the method 500 further comprises: transmitting, to a second apparatus, a Delay Status Report (DSR) indicating at least the second data unit and not indicating the first data unit.

In some example embodiments, the first data unit is of low importance, and the second data unit is of high importance.

In some example embodiments, the first data unit is to be discarded at least in response to expiration of the first discarding timer and the second data unit is to be discarded in response to expiration of the second discarding timer, and wherein the second discarding timer is configured to count a longer time than the first discarding timer.

In some example embodiments, a remaining time of a second discarding timer for the second data unit is shorter than a time threshold.

In some example embodiments, the first importance is low importance and the second importance is high importance.

In some example embodiments, the first apparatus comprises a terminal device, and the second apparatus comprises a network device.

FIG. 6 shows a flowchart of an example method 600 implemented at a second apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 600 will be described from the perspective of the second apparatus 120 in FIG. 1.

At block 610, the second apparatus 120 transmits, to a first apparatus, configuration information indicating whether discarding of a data unit of a first importance is enabled, wherein the data unit is in a buffer at least comprising a first data unit that arrived before a second data unit and is associated with a first discarding timer that is running, wherein the first data unit is of the first importance and the second data unit is of a second importance.

In some example embodiments, the discarding is triggered by a discarding condition comprising at least one of: a Delay Status Report (DSR) for a Logical Channel (LCH) or a Data Radio Bearer (DRB) is triggered, a DSR is pending for a LCH or a DRB, a remaining time until expiry of a corresponding discarding timer becomes shorter than a time threshold for a data unit of the second importance in the buffer, or an uplink grant is received from a second apparatus.

In some example embodiments, the method 600 further comprises: transmitting, to the first apparatus, an uplink grant comprising a discarding indication indicating the first data unit is to be discarded.

In some example embodiments, the method 600 further comprises: receiving, from the first apparatus, a Delay Status Report (DSR) indicating at least the second data unit and not indicating the first data unit.

In some example embodiments, a first apparatus capable of performing any of the method 500 (for example, the first apparatus 110 in FIG. 1) may comprise means for performing the respective operations of the method 500. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The first apparatus may be implemented as or included in the first apparatus 110 in FIG. 1.

In some example embodiments, the first apparatus comprises means for in accordance with a determination that a discarding condition is met, identifying a first data unit arrived in a buffer before a second data unit and associated with a first discarding timer that is running, wherein the first data unit is of a first importance and the second data unit is of a second importance higher than the first importance; means for discarding the first data unit from the buffer before the first discarding timer expires.

In some example embodiments, the first apparatus further comprises: means for determining to discard the first data unit based on the uplink grant.

In some example embodiments, the first apparatus further comprises: means for in accordance with a determination that the uplink grant allows data from a Logical Channel (LCH) to be transmitted, determining that the first data unit is to be discarded; or means for in accordance with a determination that a resource scheduled by the uplink grant is insufficient for transmitting the first data unit and the second data unit, determining that the first data unit is to be discarded; or means for in accordance with a determination that an amount of a second data unit that fits in a Medium Access Control (MAC) Protocol Data Unit (PDU) scheduled by the uplink grant is to be reduced by the first data unit, determining that the first data unit is to be discarded.

In some example embodiments, the first apparatus further comprises: means for receiving, from a second apparatus, configuration information indicating whether discarding of a data unit of the first importance is enabled.

In some example embodiments, the first apparatus further comprises: means for in accordance with a determination that the first data unit has a sequence number lower than a sequence number of the second data unit, determining that the first data unit arrived in the buffer before a second data unit; or means for in accordance with a determination that a data arrival time of a first data unit is earlier than a data arrival time of the second data unit, determining that the first data unit arrived in the buffer before the second data unit; or means for in accordance with a determination that a first time duration in which a first data unit is in the buffer is longer than a second time duration in which the second data unit is in the buffer, determining that the first data unit arrived in the buffer before the second data unit, wherein the first time duration is determined based on the first discarding timer and a remaining time of the first discarding timer, and the second time duration is determined based on the second discarding timer and the remaining time of the second discarding timer.

In some example embodiments, the first apparatus further comprises: means for transmitting, to a second apparatus, a Delay Status Report (DSR) indicating at least the second data unit and not indicating the first data unit.

In some example embodiments, a second apparatus capable of performing any of the method 600 (for example, the second apparatus 120 in FIG. 1) may comprise means for performing the respective operations of the method 600. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The second apparatus may be implemented as or included in the second apparatus 120 in FIG. 1.

In some example embodiments, the second apparatus comprises means for transmitting, to a first apparatus, configuration information indicating whether discarding of a data unit of a first importance is enabled, wherein the data unit is in a buffer at least comprising a first data unit arrived before a second data unit and associated with a first discarding timer that is running, wherein the first data unit is of the first importance and the second data unit is of a second importance.

In some example embodiments, the discarding is triggered by a discarding condition comprises at least one of: a Delay Status Report (DSR) for a Logical Channel (LCH) or a Data Radio Bearer (DRB) is triggered, a DSR is pending for a LCH or a DRB, a remaining time until expiry of a corresponding discarding timer becomes shorter than a time threshold for a data unit of the second importance in the buffer, or an uplink grant is received from a second apparatus.

In some example embodiments, the second apparatus further comprises: means for transmitting, to the first apparatus, an uplink grant comprising a discarding indication indicating the first data unit is to be discarded.

In some example embodiments, the second apparatus further comprises: means for receiving, from the first apparatus, a Delay Status Report (DSR) indicating at least the second data unit and not indicating the first data unit. In some example embodiments, the first data unit is of low importance, and the second data unit is of high importance.

FIG. 7 is a simplified block diagram of a device 700 that is suitable for implementing example embodiments of the present disclosure. The device 700 may be provided to implement a communication device, for example, the first apparatus 110 or the second apparatus 120 as shown in FIG. 1. As shown, the device 700 includes one or more processors 710, one or more memories 720 coupled to the processor 710, and one or more communication modules 740 coupled to the processor 710.

The communication module 740 is for bidirectional communications. The communication module 740 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interfaces may represent any interface that is necessary for communication with other network elements. In some example embodiments, the communication module 740 may include at least one antenna.

The processor 710 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 700 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

The memory 720 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 724, an electrically programmable read only memory (EPROM) , a flash memory, a hard disk, a compact disc (CD) , a digital video disk (DVD) , an optical disk, a laser disk, and other magnetic storage and/or optical storage. Examples of the volatile memories include, but are not limited to, a random-access memory (RAM) 722 and other volatile memories that will not last in the power-down duration.

A computer program 730 includes computer executable instructions that are executed by the associated processor 710. The instructions of the program 730 may include instructions for performing operations/acts of some example embodiments of the present disclosure. The program 730 may be stored in the memory, e.g., the ROM 724. The processor 710 may perform any suitable actions and processing by loading the program 730 into the RAM 722.

The example embodiments of the present disclosure may be implemented by means of the program 730 so that the device 700 may perform any process of the disclosure as discussed with reference to FIG. 3 to FIG. 6. The example embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

In some example embodiments, the program 730 may be tangibly contained in a computer readable medium which may be included in the device 700 (such as in the memory 720) or other storage devices that are accessible by the device 700. The device 700 may load the program 730 from the computer readable medium to the RAM 722 for execution. In some example embodiments, the computer readable medium may include any types of non-transitory storage medium, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. The term “non-transitory, ” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM) .

FIG. 8 shows an example of the computer readable medium 800 which may be in form of CD, DVD or other optical storage disk. The computer readable medium 800 has the program 730 stored thereon.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, and other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. Although various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

Some example embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer readable medium, such as a non-transitory computer readable medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target physical or virtual processor, to carry out any of the methods as described above. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. The program code may be provided to a processor or controller of a general-purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program code, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

In the context of the present disclosure, the computer program code or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random-access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, although operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, although several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Unless explicitly stated, certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, unless explicitly stated, various features that are described in the context of a single embodiment may also be implemented in a plurality of embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in languages specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

A first apparatus comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to:

in accordance with a determination that a discarding condition is met, identify a first data unit arrived in a buffer before a second data unit and associated with a first discarding timer that is running, wherein the first data unit is of a first importance and the second data unit is of a second importance higher than the first importance; and

discard the first data unit from the buffer before the first discarding timer expires.
The first apparatus of claim 1, wherein the discarding condition comprises at least one of:

a Delay Status Report (DSR) for a Logical Channel (LCH) or a Data Radio Bearer (DRB) is triggered,

a DSR is pending for a LCH or a DRB,

a remaining time until expiry of a corresponding discarding timer becomes shorter than a time threshold for a data unit of the second importance in the buffer, or

an uplink grant is received from a second apparatus.
The first apparatus of claim 1 or 2, wherein the discarding condition is reception of an uplink grant from the second apparatus; and wherein the first apparatus is caused to:

determine to discard the first data unit based on the uplink grant.
The first apparatus of claim 3, wherein the uplink grant comprises a discarding indication, and the first apparatus is caused to:

in accordance with a determination that the uplink grant allows data from a Logical Channel (LCH) to be transmitted, determine that the first data unit is to be discarded; or

in accordance with a determination that a resource scheduled by the uplink grant is insufficient for transmitting the first data unit and the second data unit, determine that the first data unit is to be discarded; or

in accordance with a determination that an amount of a second data unit that fits in a Medium Access Control (MAC) Protocol Data Unit (PDU) scheduled by the uplink grant is to be reduced by the first unit, determine that the first data unit is to be discarded.
The first apparatus of any of claims 1 to 4, wherein the first data unit excludes a data unit considered for retransmission.
The first apparatus of any of claims 1 to 5, wherein the first apparatus is caused to:receive, from a second apparatus, configuration information indicating whether discarding of a data unit of the first importance is enabled.
The first apparatus of any of claims 1 to 6, wherein a Protocol Data Unit (PDU) Set Importance (PSI) based discard is activated for a Logical Channel (LCH) or a Data Radio Bearer (DRB) .
The first apparatus of claim 2 or 7, wherein the LCH is a LCH of at least one of the first data unit or the second data unit, and the DRB is a DRB of at least one of the first data unit or the second data unit.
The first apparatus of any of claims 1 to 8, wherein the first apparatus is caused to:

in accordance with a determination that the first data unit has a sequence number lower than a sequence number of the second data unit, determine that the first data unit arrived in the buffer before a second data unit; or

in accordance with a determination that a data arrival time of a first data unit is earlier than a data arrival time of the second data unit, determine that the first data unit arrived in the buffer before the second data unit; or

in accordance with a determination that a first time duration in which a first data unit is in the buffer is longer than a second time duration in which the second data unit is in the buffer, determine that the first data unit arrived in the buffer before the second data unit, wherein the first time duration is determined based on the first discarding timer and a remaining time of the first discarding timer, and the second time duration is determined based on the second discarding timer and the remaining time of the second discarding timer.
The first apparatus of any of claims 1 to 9, wherein the first apparatus is caused to:

transmit, to a second apparatus, a Delay Status Report (DSR) indicating at least the second data unit and not indicating the first data unit.
The first apparatus of any of claims 1 to 10, wherein the first data unit is of low importance, and the second data unit is of high importance.
The first apparatus of any of claims 1 to 11, wherein the first data unit is to be discarded at least in response to expiration of the first discarding timer and the second data unit is to be discarded in response to expiration of the second discarding timer, and wherein the second discarding timer is configured to count a longer time than the first discarding timer.
The first apparatus of any of claims 1 to 12, wherein a remaining time of a second discarding timer for the second data unit is shorter than a time threshold.
The first apparatus of any of claims 1 to 13, wherein the first importance is low importance and the second importance is high importance.
The first apparatus of any of claims 1 to 14, wherein the first apparatus comprises a terminal device, and the second apparatus comprises a network device.
A second apparatus comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus at least to:

transmit, to a first apparatus, configuration information indicating whether discarding of a data unit of a first importance is enabled,

wherein the data unit is in a buffer at least comprising a first data unit arrived before a second data unit and associated with a first discarding timer that is running, wherein the first data unit is of the first importance and the second data unit is of a second importance.
The second apparatus of claim 16, wherein discarding of the first data unit is triggered by a discarding condition comprises at least one of:

a Delay Status Report (DSR) for a Logical Channel (LCH) or a Data Radio Bearer (DRB) is triggered,

a DSR is pending for a LCH or a DRB,

a remaining time until expiry of a corresponding discarding timer becomes shorter than a time threshold for a data unit of the second importance in the buffer, or

an uplink grant is received from a second apparatus.
The second apparatus of claim 16 or 17, wherein the second apparatus is caused to:

transmit, to the first apparatus, an uplink grant comprising a discarding indication indicating the first data unit is to be discarded.
The second apparatus of any of claims 16 to 18, wherein the first data unit excludes a data unit considered for retransmission.
The second apparatus of any of claims 16 to 19, wherein a Protocol Data Unit (PDU) Set Importance (PSI) based discard is activated for a Logical Channel (LCH) or a Data Radio Bearer (DRB) .
The second apparatus of claim 17 or 20, wherein the LCH is a LCH of at least one of the first data unit or the second data unit, and the DRB is a DRB of at least one of the first data unit or the second data unit.
The second apparatus of any of claims 16 to 21, wherein the second apparatus is caused to:

receive, from the first apparatus, a Delay Status Report (DSR) indicating at least the second data unit and not indicating the first data unit.
The second apparatus of any of claims 16 to 22, wherein the first data unit is of low importance, and the second data unit is of high importance.
The second apparatus of any of claims 16 to 23, wherein the first data unit is to be discarded at least in response to expiration of the first discarding timer and the second data unit is to be discarded in response to expiration of the second discarding timer, and wherein the second discarding timer is configured to count a longer time than the first discarding timer.
The second apparatus of any of claims 16 to 24, wherein a remaining time of a second discarding timer for the second data unit is shorter than a time threshold.
The second apparatus of any of claims 16 to 25, wherein the first importance is low importance and the second importance is high importance.
The second apparatus of any of claims 16 to 26, wherein the first apparatus comprises a terminal device, and the second apparatus comprises a network device.
A method comprising:

in accordance with a determination that a discarding condition is met, identifying a first data unit arrived in a buffer before a second data unit and associated with a first discarding timer that is running, wherein the first data unit is of a first importance and the second data unit is of a second importance higher than the first importance; and

discarding the first data unit from the buffer before the first discarding timer expires.
A method comprising:

transmitting, to a first apparatus, configuration information indicating whether discarding of a data unit of a first importance is enabled,

wherein the data unit is in a buffer at least comprising a first data unit arrived before a second data unit and associated with a first discarding timer that is running, wherein the first data unit is of the first importance and the second data unit is of a second importance.
A first apparatus comprising:

means for in accordance with a determination that a discarding condition is met, identifying a first data unit arrived in a buffer before a second data unit and associated with a first discarding timer that is running, wherein the first data unit is of a first importance and the second data unit is of a second importance higher than the first importance; and

means for discarding the first data unit from the buffer before the first discarding timer expires.
A second apparatus comprising:

means for transmitting, to a first apparatus, configuration information indicating whether discarding of a data unit of a first importance is enabled,

wherein the data unit is in a buffer at least comprising a first data unit arrived before a second data unit and associated with a first discarding timer that is running, wherein the first data unit is of the first importance and the second data unit is of a second importance.
A computer readable medium comprising instructions stored thereon for causing an apparatus at least to perform the method of claim 28 or the method of claim 29.