WO2025210484A1

WO2025210484A1 - Method, apparatus and computer program relating to identifying expired data units to a receiver

Info

Publication number: WO2025210484A1
Application number: PCT/IB2025/053374
Authority: WO
Inventors: Abolfazl AMIRI; Benoist Pierre Sebire; Henri Markus Koskinen
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2024-04-04
Filing date: 2025-03-31
Publication date: 2025-10-09
Anticipated expiration: 2026-10-04
Also published as: GB2640198A

Abstract

An apparatus comprising: means for processing transmission of a plurality of data units in accord with a packet data convergence protocol, PDCP; means for creating a report for the plurality of data units, said report providing a sequence number of each data unit of the plurality which has an expiry time shorter than a pre-configured time value; and means for sending the report to a receiver to which the data units are processed to be sent.

Description

METHOD, APPARATUS AND COMPUTER PROGRAM RELATING TO IDENTIFYING EXPIRED DATA UNITS TO A RECEIVER

TECHNICAL FIELD

Various example embodiments of this disclosure relate to a method, apparatus and computer program and in particular but not exclusively to identifying expired data units to a receiver.

BACKGROUND

A communication system can be seen as a facility that enables communication sessions between two or more entities such as communication devices, base stations and/or other nodes by providing carriers between the various entities involved in the communications path.

The communication system and associated entities typically operate in accordance with a given standard or specification which sets out what the associated entities are permitted to do and how that should be achieved. Communication protocols and/or parameters that shall be used for the connection are also typically defined. Examples of standard include the so-called 5G standards.

SUMMARY

Some example embodiments of this disclosure will be described with respect to certain aspects. These aspects are not intended to indicate key or essential features of the various example embodiments of this disclosure, nor are they intended to be used to limit the scope of thereof. Other features, aspects, and elements will be readily apparent to a person skilled in the art in view of this disclosure.

In an aspect there is provided an apparatus comprising: means for processing data units for transmission in accord with a packet data convergence protocol, PDCP; means for creating a report comprising information providing a sequence number of at least one data unit, and a time period associated with the at least one data unit of the set; and means for sending the report to a receiver to which the data units are scheduled to be sent.

The data unit may be at least one data unit of a set.

The apparatus may further comprise means for determining a data unit within the set having a shortest expiry time, wherein the means for creating the report provides the sequence number and expiry time of the determined data unit in the report.

The means for creating the report may provide only the sequence number and expiry time of the determined data unit in the report. The means for creating the report may provide one sequence number and one expiry time for each of multiple sets of data.

The means for creating the report may provide the sequence number of all data units in the set in the report, and the expiry time determined to be the shortest.

The means for creating the report may provide the sequence numbers and an expiry time for each of multiple sets of data.

The time period may be a time-to-live expiry time value after which the time period has expired.

The time period may be a time-to-live expiry time value equal to a remaining time before a discard timer for relatively low-importance data expires.

The time period may correspond to a pre-configured time value and the report may comprise information providing the sequence number of one or more data units, each of which data unit is associated with a remaining time, after which the respective data units are to be discarded, each discard time being less than the pre-configured time value.

The report may comprise the sequence number of all data units in the set having a discard time of less than the pre-configured time.

The report may include the sequence numbers and associated pre-configured time for multiple sets of data.

The means for creating the report may be configured to create the report periodically.

The apparatus may further comprise means for determining if a data unit has been sent, wherein the means for creating the report is configured to create the report based on an assessment only of data units which have been sent.

The apparatus may further comprise means for determining discarding of a data unit at the transmitter, wherein the means for creating the report is configured to create the report based on an assessment of data units which have not been discarded.

A user equipment may comprise the apparatus, and further comprise means for receiving configuration data from a network for configuring the report. A user equipment or base station may include the apparatus.

Processing may comprises buffering and/or scheduling.

The apparatus may comprise means for implementing the method.

The apparatus may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform any of the methods discussed in relation to the second aspect. In an aspect there is provided an apparatus comprising: means for receiving data units and for receiving a report comprising information providing a sequence number for at least one data unit; means for initiating a timer based on a time value, responsive to receipt of the report; means for determining that the timer indicates that the time value has expired without the at least one data unit being received; and means for, responsive to said determination, updating a lowest sequence number among data units expected to be received to a value greater than the sequence number of the data unit for which the time value has expired.

The report may be for a set of data units and identifies the sequence number of one data unit in the set having the shortest time value.

The report may be for a set of data units, and identifies the sequence number of each data unit in the set , and the shortest time value associated with the data units of the set, the means for configuring the receiver to receive the data unit associated with a sequence number greater than the highest sequence number in that set.

The report may comprise information providing the sequence number of one or more data units each of which is associated with a discard time, after which the respective data units are discarded, each discard time being less than the time value, wherein the timer is initiated based on the time value.

The means for receiving the set of data units may be configured to operate a reception window, the receiver further comprising means for adjusting the reception window in a way to exclude the sequence numbers of data units associated with an expired time period.

Processing may comprises buffering and/or scheduling.

The apparatus may comprise means for implementing the method.

The apparatus may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform any of the methods discussed in relation to the second aspect.

In an aspect there is provided a method comprising: processing data units for transmission in accord with a packet data convergence protocol, PDCP; creating a report comprising information providing a sequence number of at least one data unit, and a time period associated with the at least one data unit of the set; and sending the report to a receiver to which the data units are scheduled to be sent.

The data unit of the method may be at least one data unit of a set.

The method may further comprise determining a data unit within the set having the shortest expiry time, wherein creating the report provides the sequence number and expiry time of the determined data unit in the report. Creating the report may provide only the sequence number and expiry time of the determined data unit in the report.

Creating the report may provide one sequence number and one expiry time for each of multiple sets of data.

Creating the report may provide the sequence number of all data units in the set in the report, and the expiry time determined to be the shortest.

Creating the report may provide the sequence numbers and an expiry time for each of multiple sets of data.

The expiry time of the method may be a time-to-live value equal to a remaining time before a discard timer expires.

The expiry time of the method may be a time-to-live value equal to a remaining time before a discard timer for relatively low-importance data expires.

The time period of the method may correspond to a pre-configured time value and the report may comprise information providing the sequence number of one or more data units, each of which data unit is associated with a remaining time, after which the respective data units are to be discarded, each discard time being less than the pre-configured time value.

The report of the method may comprise the sequence number of all data units in the set having a discard time of less than the pre-configured time.

The report of the method may include the sequence numbers and associated preconfigured time for multiple sets of data.

Creating the report may be configured to create the report periodically.

The method may further comprise determining if a data unit has been sent, wherein creating the report is based on an assessment only of data units which have been sent.

The method may further comprise determining discarding of a data unit at the transmitter, wherein creating the report is based on an assessment of data units which have not been discarded.

A user equipment may utilise the method, and further receiver configuration data from a network for configuring the report.

The method may be performed by an apparatus.

In an aspect there is provided a method comprising: receiving data units and for receiving a report comprising information providing a sequence number for at least one data unit, and a time value associated with the at least one data unit; initiating a timer based on the time value identified in the report, responsive to receipt of the report; determining that the timer indicates that the time value has expired without the at least one data unit being received; and, responsive to said determination, configuring the apparatus to update a lowest sequence number among data units expected to be received to a value greater than the sequence number of the data unit for which the time value has expired.

The report of the method may be for a set of data units and identifies the sequence number of one data unit in the set having the shortest time value.

The report of the method may be for a set of data units, and identifies the sequence number of each data unit in the set , and the shortest time value associated with the data units of the set, the means for configuring the receiver to receive the data unit associated with a sequence number greater than the highest sequence number in that set.

The report of the method may comprise information providing the sequence number of one or more data units each of which is associated with a discard time, after which the respective data units are discarded, each discard time being less than the time value, wherein the timer is initiated based on the time value.

Receiving the set of data units may operate a reception window, the receiver adjusting the reception window in a way to exclude the sequence numbers of data units associated with an expired time period.

A user equipment or base station may utilise the method.

The method may be performed by an apparatus.

In an aspect there is provided an apparatus comprising: means for processing transmission of a plurality of data units in accord with a packet data convergence protocol, PDCP; means for creating a report for at least one of the plurality of data units, said report providing a sequence number of the at least one data unit, and an expiry time for the at least one data unit; and means for sending the report to a receiver to which the data units are processed to be sent.

The plurality of data packets may be each allocated to one of a plurality of sets.

The apparatus may further comprise means for determining the data unit of a set associated with the shortest expiry time, wherein the means for creating the report provides the sequence number of that data unit and the expiry time for that data unit.

The apparatus may further comprise means for determining the shortest expiry time for a data unit in a set, wherein the means for creating the report provides the sequence number of all data units in that set and the shortest expiry time within the set.

The means for creating the report may be responsive to means for indicating the set of data is for an application requiring all data units of the set. The expiry time may be a time-to-live value equal to a remaining time before a discard timer expires.

The expiry time may be a time-to-live value equal to a remaining time before a discard timer for relatively low-importance data expires.

The means for sending the report may be enabled to send the report for the set responsive to one data unit of the set being submitted to a lower layer for transmission.

Processing may comprises buffering and/or scheduling.

The data unit may be submitted to an RLC layer.

The data unit may be a protocol data unit, PDU.

A base station may comprise the apparatus. A UE may comprise the apparatus.

The apparatus may comprise means for implementing the method.

In an aspect there is provided an apparatus comprising: means for receiving a report comprising information providing a sequence number for a data unit to be transmitted to the receiver, and an expiry time for the data unit; means for initiating a timer based on the expiry time identified in the received report, responsive to receipt of the report; means for determining that the timer indicates that the expiry time has expired without the data unit being received; and responsive to said determination, the means for receiving is configured update a lowest sequence number among data units expected to be received to a value greater than the sequence number of the data unit for which the time value has expired.

The data unit may be associated with a set of data units, the report providing the sequence numbers of all data units in the set, wherein responsive to said determination, the means for receiving is configured to receive a data unit with a sequence number greater than the highest sequence number in the set.

The data unit may be associated with a sequence number greater than the highest sequence number of the set for which the expiry time has elapsed.

The means for receiving may be configured to adapt a reception window.

The means for receiving may be configured to receive a data unit other than a sequence number associated with an expired expiry time in any subsequent operation.

A base station may include the apparatus. A UE may include the apparatus.

The apparatus may comprise means for implementing the method. The apparatus may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform any of the methods discussed in relation to the second aspect.

In an aspect there is provided a method comprising: processing transmission of a plurality of data units in accord with a packet data convergence protocol, PDCP; creating a report for at least one of the plurality of data units, said report providing a sequence number of the at least one data unit, and an expiry time for the at least one data unit; and sending the report to a receiver to which the data units are processed to be sent.

The plurality of data packets in the method may be each allocated to one of a plurality of sets.

The method may further comprise determining the data unit of a set associated with the shortest expiry time, wherein creating the report provides the sequence number of that data unit and the expiry time for that data unit.

The method may further comprise determining the shortest expiry time for a data unit in a set, wherein creating the report provides the sequence number of all data units in that set and the shortest expiry time within the set.

Creating the report may be responsive to means for indicating the set of data is for an application requiring all data units of the set.

Sending the report may be enabled to send the report for the set responsive to one data unit of the set being submitted to a lower layer for transmission.

The data unit of the method may be submitted to an RLC layer. The data unit of the method may be a packet data unit, PDU.

A base station may utilise the method. A UE may utilise the method.

The method may be performed by an apparatus.

In an aspect there is provided a method comprising: receiving a report comprising information providing a sequence number for a data unit processed to be transmitted to the receiver, and an expiry time for the data unit; initiating a timer based on the expiry time identified in the received report, responsive to receipt of the report; determining that the timer indicates that the expiry time has expired without the data unit being received; and responsive to said determination, updating a lowest sequence number among data units expected to be received to a value greater than the sequence number of the data unit for which the time value has expired.

The data unit of the method may be associated with a set of data units, the report providing the sequence numbers of all data units in the set, wherein responsive to said determination, the method comprises receiving a data unit with a sequence number greater than the highest sequence number in the set.

The data unit of the method may be associated with a sequence number greater than the highest sequence number of the set for which the expiry time has elapsed.

Receiving may be comprise adapting a reception window.

Receiving may comprise receiving a data unit other than a sequence number associated with an expired expiry time in any subsequent operation.

A base station may utilise the method. A UE may utilise the method.

The data unit of the method may be associated with a set of data units, the report providing only the sequence number of the data unit in the set having the shortest expiry time and that shortest expiry time, or the report providing the sequence number of all data units in the set and that shortest expiry time, wherein on expiry of the expiry time, the receiving is configured to receive a data unit with a sequence number, respectively, either higher than the sequence number of that data unit, or higher than the last sequence number in the set.

The method may be performed by an apparatus.

An aspect provides an apparatus comprising: means for processing transmission of a plurality of data units in accord with a packet data convergence protocol, PDCP; means for creating a report for the plurality of data units, said report providing a sequence number of each data unit of the plurality which has an expiry time shorter than a pre-configured time value; and means for sending the report to a receiver to which the data units are processed to be sent.

The pre-configured time value may be a threshold.

The means for creating a report may create a report for more than one set of a plurality of data units.

The report may include the sequence number of all of the plurality of data units in a set.

The report may include the pre-configured time value.

The apparatus may further include means for determining the data units of the set being associated with an expiry time less than or equal to the pre-configured time value.

The expiry time of at least one data unit may be a time-to-live value equal to a remaining time before a discard timer expires. The expiry time of at least one data unit may be a time-to-live value equal to a remaining time before a discard timer for relatively low-importance data expires.

The data unit may be submitted to an RLC layer.

The data unit may be a protocol data unit, PDU.

A base station may comprise the apparatus.

A UE may comprise the apparatus.

The apparatus may comprise means for implementing the method.

An aspect provides an apparatus comprising: means for receiving a report comprising information providing a sequence number for a data unit to be received means for receiving a pre-configured time value; means for initiating a timer based on the pre-configured time value, responsive to receipt of the report; means for determining that the timer indicates that the preconfigured time value has expired without the data unit being received; and responsive to said determination, the means for receiving is configured to update a lowest sequence number among data units expected to be received to a value greater than the sequence number of the data unit for which the pre-configured time value has expired.

The apparatus may be associated with a plurality of data units, the report providing the sequence numbers of all data units in the plurality having an expiry time corresponding to the pre-configured time value, wherein responsive to said determination, the means for receiving is configured to receive a data unit with a sequence number greater than the sequence number of any of the plurality.

The means for receiving may be configured to adapt a reception window.

A base station may include the apparatus.

A UE may include the apparatus.

The apparatus may comprise means for implementing the method.

The apparatus may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform any of the methods discussed in relation to the second aspect. An aspect provides a method comprising: processing transmission of a plurality of data units in accord with a packet data convergence protocol, PDCP; creating a report for the plurality of data units, said report providing a sequence number of each data unit of the plurality which has an expiry time shorter than a pre-configured time value; and sending the report to a receiver to which the data units are processed to be sent.

The pre-configured time value of the method may be a threshold.

Creating a report may create a report for more than one set of a plurality of data units.

The report of the method may include the sequence number of all of the plurality of data units in a set.

The report of the method may include the pre-configured time value.

The method may further include means for determining the data units of the set being associated with an expiry time less than or equal to the pre-configured time value.

The expiry time of at least one data unit according to the method may be a time-to-live value equal to a remaining time before a discard timer expires.

The expiry time of at least one data unit according to the method may be a time-to-live value equal to a remaining time before a discard timer for relatively low-importance data expires.

Sending the report may be enabled responsive to one data unit of the set being submitted to a lower layer for transmission.

The data unit of the method may be submitted to an RLC layer.

The data unit of the method may be a protocol data unit, PDU.

The method may be utilised in a base station.

The method may be utilised in a UE.

The method may be performed by an apparatus.

An aspect provides a method comprising: receiving a report comprising information providing a sequence number for a data unit to be received; receiving a pre-configured time value; initiating a timer based on the pre-configured time value, responsive to receipt of the report; means for determining that the timer indicates that the pre-configured time value has expired without the data unit being received; and responsive to said determination, updating a lowest sequence number among data units expected to be received to a value greater than the sequence number of the data unit for which the pre-configured time value has expired.

The method may be associated with a plurality of data units, the report providing the sequence numbers of all data units in the plurality having an expiry time corresponding to the pre-configured time value, wherein responsive to said determination, the means for receiving is configured to receive a data unit with a sequence number greater than the sequence number of any of the plurality.

Receiving may comprise adapting a reception window.

Receiving may be configured to receive a data unit other than a sequence number associated with an expired expiry time in any The method may be utilised in a base station.

The method may be utilised in a UE.

The method may be performed by an apparatus.

According to an aspect, there is provided a computer readable medium comprising program instructions stored thereon for performing at least one of the above methods.

According to an aspect, there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing at least one of the above methods.

According to an aspect, there is provided a non-volatile tangible memory medium comprising program instructions stored thereon for performing at least one of the above methods.

In the above, many different aspects have been described. It should be appreciated that further aspects may be provided by the combination of any two or more of the aspects described above.

Various other aspects are also described in the following detailed description and in the attached claims.

BRIEF DESCRIPTION OF THE FIGURES

Some example embodiments will now be described, by way of non-limiting and illustrative example only, with reference to the accompanying drawings in which:

Fig. 1 shows a representation of an example of a communication system;

Fig. 2 shows a representation of an example of apparatus for implementing one or more network functions of the communication system;

Fig. 3 shows a representation of an example of user equipment according to some example embodiments;

Fig. 4 shows a representation of an example of operations at transmitting and receiving entities according to some example embodiments;

Fig. 5 shows a first method of some example embodiments;

Fig. 6 shows a second method of some example embodiments;

Fig. 7 shows a third method of some example embodiments; Fig. 8 shows a fourth method of some example embodiments;

Fig. 9 shows a fifth method of some example embodiments; and

Fig. 10 shows a sixth method of some example embodiments.

DETAILED DESCRIPTION

In the following, various example embodiments are explained for the example of a user equipment operating according to a 3GPP 5^th generation (5G) communication protocol, but the example embodiments may also be applicable to user equipments operating according to other communication protocols.

Fig. 1 shows a schematic representation of a 5G communication system (5GS). The 5GS may comprise a user equipment (UE), an access network such as a 5G radio access network (5G-RAN) or next generation radio access network (NG-RAN), a 5G core network (5GC), and one or more application functions. The 5GS connects the UE to a data network the access network and the 5GC (e.g., a UPF of the 5GC).

The 5G-RAN may comprise one or more radio access nodes, such as gNodeB (GNB). A gNB may be a stand-alone entity or may be provided by a distributed architecture. The distributed architecture comprises one or more gNodeB (GNB) distributed units (gNB- DU) connected to gNodeB centralized unit control plane and user plane entities (gNB-CU-CP and gNB-CU-UP). Additionally one or more radio units RU (not shown) may be provided as part of the distributed architecture. One CU may serve a plurality of DUs. A DU may serve a plurality RUs. A RU may comprise the physical layer, and a RF (radio frequency) front end. The DU may make scheduling decisions. Embodiments use the PDCP protocol, and may use the gNB-CU-UP.

The interface between the gNB-CU-CP entity and the gNB-CU-UP entity is referred to as El interface. The interface between the gNB-CU-CP entity and the gNB-DU(s) is referred to as Fl-C interface. The interface between the gNB-CU-UP entity and the gNB-DU(s) is referred to as Fl-U interface.

The 5GC may comprise the following network functions: Network Slice Selection Function (NSSF); Network Exposure Function; Network Repository Function (NRF); Policy Control Function (PCF); Unified Data Management (UDM); Application Function (AF); Authentication Server Function (AUSF); an Access and Mobility Management Function (AMF); and Session Management Function (SMF), and a user plane function (UPF). Fig. 1 also shows the various interfaces (Nl, N2 etc.) that may be implemented between the various elements of the system. Fig. 2 illustrates an example of at least a part 200 of the base station. The part 200 may have at least one processor and at least one memory storing instructions of the base station that, when executed by at least one of the at least one processor cause operations or actions of the base station to be performed. The at least a part of the base station may be a base station or part of the base station such as a DU in an architecture where a base station function is provided by CU, DU and RU architecture. The scheduling may be controlled by the DU.

The base station may comprise at least one random access memory (RAM) 211a, at least one read only memory (ROM) 211b, at least one processor 212, 213 and an input/output interface 214. The at least one processor 212, 213 may be coupled to the RAM 211a and the ROM 211b. The at least one processor 212, 213 may be configured to execute an appropriate software code 215. The software code 215 may include software code that allows, enables, or otherwise facilitates the apparatus to perform one or more operations of the base station.

The software code 215 may be stored in the ROM 211b.

Fig. 3 illustrates an example of a communication device 300, such as the user equipment (UE) illustrated in Fig. 1 and mentioned in the description of example embodiments below. The communication device 300 may be provided by any device capable of sending and receiving radio signals. Non-limiting examples of a communication device 300 comprise a user equipment, a mobile station (MS) or mobile device such as a mobile phone or what is known as a ’smart phone’, a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), a personal data assistant (PDA) or a tablet provided with wireless communication capabilities, a machine-type communications (MTC) device, an Internet of things (loT) type communication device or any combinations of these or the like. The communication device may be an XR (extended reality) device such as a headset or may be capable of supporting an XR application (e.g., capable of executing or running an XR application). The headset may be a VR headset. The communication device may be or part of a vehicle. The communication device 300 may comprise a transceiver for transmitting and/or receiving, for example, wireless signals carrying communications, for example radio signals. The communications may be one or more of voice, electronic mail (email), text messages, multimedia data, machine data and so on.

The communication device 300 may receive wireless signals (e.g., radio signals) over an air or radio interface 307 via appropriate apparatus for receiving and may transmit wireless signals via appropriate apparatus for transmitting radio signals. In Fig. 3 transceiver is designated schematically by block 306. The transceiver 306 may comprise, for example, a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device and may comprise one or more antenna elements. The antenna arrangement may be a multi-input multi output (MIMO) antenna.

The communication device 300 may be provided with at least one processor 301, at least one memory ROM 302a, at least one RAM 302b and other possible components 303 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access networks (e.g., the 5G-RAN or NG-RAN illustrated in Fig. 1) and other communication devices. The at least one processor 301 is coupled to the RAM 302b and the ROM 302a. The at least one processor 301 may be configured to execute an appropriate software code 308. The software code 308 may for example allow to perform one or more operations of the communication device. The software code 308 may be stored in the ROM 302a.

The processor, the ROM, and the RAM, the transceiver and other circuitry of the communication device (e.g., a modem) can be provided on a circuit board, in chipsets, or in a system on chip. The circuit board, chipsets or system on chip is denoted by reference 304. The communication device 300 may optionally have a user interface such as key pad 305, touch sensitive screen or pad, combinations thereof or the like. Optionally one or more of a display, a speaker and a microphone may be provided depending on the type of communication device.

It should be understood that the apparatuses may comprise or be coupled to other units or modules etc., such as radio parts or radio heads, used in or for transmission and/or reception. Although the apparatuses have been described as one entity, different modules and memory may be implemented in one or more physical or logical entities.

The UE may support XR (extended reality) applications. An application function may support an XR application.

XR is an umbrella term and may include at least the following types of reality:

Augmented Reality (AR) where virtual objects are added to a real -world environment;

Virtual Reality (VR) where visual and audio scenes are combined with a real-world location; and

Mixed Reality (MR) where haptics and interactions are added to a real-world environment.

The UE may be be an XR (extended reality) device such as a headset or may be capable of supporting an XR application (e.g., capable of executing or running an XR application). The headset may be a VR headset. In this document, the term UE or user equipment is used. This term encompasses any of the example of communication device 300 previously discussed and/or any other communication device.

For the example of uplink transmissions, the receiving (RX) entity may be a gNB; and the transmitting (TX) entity may be a user equipment (UE). As mentioned above, the gNB may comprise a collection of entities e.g. gNB-DU, gNB-CU-CP and gNB-CU-UP.

For the example of downlink transmissions, the RX entity may be a UE and the TX entity may be a gNB. As mentioned above, the gNB may comprise a collection of entities e.g. gNB-DU, gNB-CU-CP and gNB-CU-UP.

The RX entity receives data units transmitted by the TX entity. The data units have respective data unit number values. For the example of RLC, the data unit values may be referred to as sequence number values by which the RX entity can monitor the reception of data units and provide feedback to the TX entity. Unless specifically specified otherwise, receiving a data unit refers to correctly receiving a data unit (receiving a data unit without error).

According to one example, the data units are lower layer data units having respective lower layer DU# carrying higher layer data units having respective higher layer DU#. For the example of PDCP, the higher layer data unit number values may be referred to as Count values. The least significant bits of the PDCP Count values, referred to as PDCP sequence number (SN), may be indicated as part of a PDCP data unit. According to one example, the data units are radio link control (RLC) data units having respective RLC sequence number values# and carrying packet data convergence protocol (PDCP) data units having respective PDCP Count values.

Similarly, the RX entity maintains one or more RX windows indicating the range of DU# for data units whose payload can be delivered to a higher layer.

Time-to-live (TTL) or hop limit - which may more generally be referred to as expiry time - is a mechanism which limits the lifespan or lifetime of data in a computer or network. TTL may be implemented as a counter or timestamp attached to or embedded in the data. Once the prescribed event count or timespan has elapsed, data is discarded/destroyed or revalidated.

A current solution for indication of missing data units in accord with packet data convergence protocol (PDCP) is to send a PDCP control protocol data unit (PDU) indication. This indication carries information of the sequence numbers (SNs) - or other identity - of discarded data units. In PDCP, the data units are PDUs. However, this indication report is only made based on the currently discarded PDUs, and there can be cases where multiple reports are generated because of consecutive discard of PDUs. PDCP discards can be an indicator of congestion, successful transmission of many discard indication reports becomes even more challenging.

There is proposed a technique to enhance reporting of discard indication, and to avoid creating multiple discard reports, especially in congestion scenarios.

Data units are buffered at the transmitter for scheduling to be transmitted to the receiver. A status report is generated for the data units, which includes information providing or identifying a sequence number of a data unit, and an expiry time or time period associated with that data unit. This report is then sent from the transmitter to the receiver.

The data units may be discarded at the transmitter before they are transmitted to the receiver. For a PDCP transmitter, legacy discard mechanisms may be used, and these may be PDU set based or PSI based. A PDU set is a set of PDUs carrying the payload of one unit of information generated at the application level (e.g. a frame or video slice for XR Services).

The status report will let the receiver know that after the duration associated with the expiry time or time period at the latest, and optionally taking into account the delivery delay time associated with the report, the identified data unit will be discarded at the transmitter, and the receiver entity should no longer expect to receive the data packet.

Embodiments will now be described further with respect to operation at the transmitter. The embodiments will be described in the context of a transmitter for transmitting packets in accordance with the packet data convergence protocol, PDCP. Data units are received at the transmitter from a higher layer, for scheduling transmission to a receiving entity. More particularly, service data units (SDUs) are received from a higher layer for transmissions as PDUs.

A timer may be started at the transmitter, which is used to discard data units after a certain amount of time, corresponding to an expiry time associated with data units. Each data unit may be associated with an expiry time. Each PDU maybe part of a set of PDUs, multiple sets of PDUs being scheduled for transmission.

A report is prepared for buffered data units which are scheduled for transmission. The buffered data units are preferably buffered in sets, with each set comprising multiple data units. The buffered data units may also be scheduled for transmission individually.

In an embodiment, the time period is an expiry time associated with the data packet, also referred to as a TTL for each data packet.

The TTL of the buffered data can be inserted in the report in different ways. In an embodiment, one TTL value is reported per PDU set. In this arrangement, the transmitter is configured to determine the SDU within each set associated with the shortest TTL, and to include the TTL of that SDU, and the sequence number of that SDU, in the report.

The TTL could be equal to the remaining time before the PDCP discard timer (or any other discard timer such as a discard timer for low importance data) is expired.

One sequence number, being the sequence number of the data unit having the chosen TTL, may be included in the report.

In an implementation, all SNs of PDUs within the set may be included in the report, even if only the one TTL is included in the report. This may be appropriate, for example, in implementations where all PDUs of a sequence are required at the receiver. If one PDU is discarded then the remaining SDUs are not required. The SN values of all buffered PDUs in the PDU set may therefore be included in the report, to indicate to the receiver know all the SNs which may be discarded after expiry of the reported TTL without receipt of the data packet.

When all the PDUs within a PDU set are required for the PDU set to be usable at the application, such information may be available at the gNB via the PDU set integrity handling indicator (PSIHI) from the session management function (SMF)When this condition is true for a quality of service (QoS) flow, the gNB knows that the application at the receiver requires all the PDUs within the PDU set, and as soon as one PDU of the PDU set is known to be lost the remaining PDUs of that PDU set can be considered as no longer needed by the application at the receiver, and may be subject to discard operation at the transmitter to free up radio resources. In general, the transmitter may generate a report containing all SNs of the set based on knowledge that the full set is needed at the receiver. In an implementation, the transmitter is a base station and the receiver is a UE.

At the UE, the discard of all PDUs of a PDU set as soon as one PDU is discarded is controlled per radio bearer by the setting of pdu-SetDiscard by RRC from the gNB.

In an implementation, the transmitter may only send such a report if at least a part of one SDU from the PDU set has been sent, for example by submission to a lower layer, more specifically submitted to the RLC layer.

In an embodiment, the time period is a pre-configured time value, T, associated with the data unit. The pre-configured time value, T, may be a threshold value.

In this embodiment, the SN of all the SDUs having a TTL shorter than the preconfigured time value T are included in the report. Regardless of any the PDU set information, and whether or not the SDUs belong to a set, the transmitter will report the SN of all data units having a TTL of less than the value T, where T is a value in seconds or milliseconds. For these data units, they will be discarded on or by expiry of time T. Time T may be considered a threshold.

In embodiments based on including the TTL or T in the report, the transmitter may be expected not to reuse the reported SNs for other SDUs in the future. An exception may arise when a shorter discard timer is used, for instance when PSI discard is activated.

In one implementation, the transmitter may only report the SN of the PDUs submitted to the RLC (because those SNs cannot be re-assigned).

In some implementations, the transmitter may be prohibited from reporting the discard indication for the reported SNs in the TTL report after their actual discard.

In case a configured grant (CG) is used, the time period may be reported in number of CG occasions. For instance, if the time period, such as the TTL, is 16ms and a CG with a periodicity of 4ms is configured, the TTL may be reported as 4. In this example, this determination is specific to the way in which time is measured at the receiver, and the receiver measures the expired time in terms of the number of cycles expired, with each cycle having a fixed time.

In case several different encoding types are possible, an indication of which one is being used in the report could be included. This is to signal the unit of time for the TTL field, for example to indicate whether it is in milliseconds or in CG occasions/cycles.

Embodiments will now be described further with respect to operation at the receiver.

Upon reception of the report the receiver may start a timer.

Where the transmitter has transmitted a report including a TTL value, the timer will be started based on the TTL value.

Where the transmitter has transmitted a report based on a pre-configured time value, the time will be configured to have that pre-configured time value.

Upon or after expiry of this timer, and not receiving all the indicated SNs, the processor of the receiver determines that those associated PDUs have been discarded, and should no longer be expected to be received.

This can be implemented via moving or adjusting, i.e. progressing, or otherwise modifying, the reception window in a way to exclude the SNs identified in the report. The lower edge of the PDCP reception window is defined by the maintained state variable RX DELIV: “This state variable indicates the COUNT value of the first PDCP SDU not delivered to the upper layers, but still waited for.” The progressing of the window requires incrementing RX DELIV if the timer for the SDU with COUNT equal to the current RX DELIV has expired. Individual edges of the window may thus be adjusted. If out-of-order delivery is not configured, delivering to upper layers the SDUs whose PDCP COUNT value is not greater than the COUNT of any SDU whose reception is still waited for. On the receiver side, if RX DELIV is updated (due to a timer expiry) past the COUNT values of any SDUs already received and stored (stored for the purpose of delivery to upper layers in increasing order of COUNT values once missing SDUs with lower COUNTS are also received), those stored SDUs are delivered to upper layers. The exception is when PDCP is configured with out-of-order delivery, in which case any SDU is immediately delivered to upper layer upon reception from lower layers.

Fig. 4 shows a representation of an example of operations at a transmitting entity and transmitting data units, and a receiving entity and receiving data units, according to some example embodiments.

Both the transmitter and receiver are configured for operation of embodiments of the technique. The transmitter is configured for creation and transmission of the report, including the generation of time values. The receiver is configured for receiving a report, and monitoring a time operation based on expiry of a timer.

Thereafter, the transmitter is configured to generate the report, including the time period (such as the TTL in embodiments) and one or more SNs. The report is generated based on configurations, such as the mode of operation and whether a TTL or a threshold T is to be used.

The report, including the time period and one or more associated SNs, is transmitted from the transmitter to the receiver.

The receiver is configured to receive the report, and to process the report.

The receiver is configured to start one or more timers based on the time period or periods included in the report, which states the TTL or threshold value.

Data transmissions, including transmission of data packets, proceed from the transmitter to the receiver.

The receiver is configured, if the timer expires without the data packet associated with the SN being received, to move the reception window to exclude those associated SNs.

Reference is made to Figs. 5-to 10 which show methods of some example embodiments.

Each method may be performed by an apparatus.

The apparatus of Figs. 5, 7 or 9 may comprise or implement a transmitter, which may be implemented at a base station or a UE.

The apparatus of Figs. 6, 8 or 10 may comprise or implement a receiver, which may be implemented at a base station or a UE.

The apparatus may comprise suitable means, such as circuitry for providing the method. Alternatively or additionally, the apparatus may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor cause the apparatus at least to provide the method below.

Alternatively or additionally, the apparatus may be such as discussed in relation to Fig. 4.

Each method may be provided by computer program code or computer executable instructions.

Referring to Fig. 5:

The method may comprise as referenced Al, processing data units for transmission in accord with a packet data convergence protocol, PDCP. The method may comprise as referenced A2, creating a report comprising information providing a sequence number of at least one data unit, and a time period associated with the at least one data unit of the set. The method may comprise as referenced A3, sending the report to a receiver to which the data units are processed to be sent.

Referring to Fig. 6:

The method may comprise as referenced Bl, receiving data units and for receiving a report comprising information providing a sequence number for at least one data unit, and a time value associated with the at least one data unit. The method may comprise as referenced B2, initiating a timer based on the time value identified in the report, responsive to receipt of the report. The method may comprise as referenced B3, determining that the timer indicates that the time value has expired without the at least one data unit being received. The method may comprise as referenced B4, responsive to said determination, configuring the receiving to update a lowest sequence number among data units expected to be received to a value greater than the sequence number of the data unit for which the time value has expired.

Referring to Fig. 7:

The method may comprise as referenced Cl, processing transmission of a plurality of data units in accord with a packet data convergence protocol, PDCP. The method may comprise as referenced C2, creating a report for at least one of the plurality of data units, said report providing a sequence number of the at least one data unit, and an expiry time for the at least one data unit. The method may comprise as referenced C3, sending the report to a receiver to which the data units are processed to be sent.

Referring to Fig. 8: The method may comprise as referenced DI, receiving a report comprising information providing a sequence number for a data unit to be transmitted to the receiver, and an expiry time for the data unit. The method may comprise as referenced D2, initiating a timer based on the expiry time identified in the received report, responsive to receipt of the report. The method may comprise as referenced D3, determining that the timer indicates that the expiry time has expired without the data unit being received. The method may comprise as referenced D4, responsive to said determination, receiving is configured to update a lowest sequence number among data units expected to be received to a value greater than the sequence number of the data unit for which the time value has expired.

Referring to Fig. 9:

The method may comprise as referenced El, processing transmission of a plurality of data units in accord with a packet data convergence protocol, PDCP. The method may comprise as referenced E2, creating a report for the plurality of data units, said report providing a sequence number of each data unit of the plurality which has an expiry time shorter than a preconfigured time value. The method may comprise as referenced E3, sending the report to a receiver to which the data units are processed to be sent.

Referring to Fig. 10:

The method may comprise as referenced Fl, receiving a report comprising information providing a sequence number for a data unit to be received. The method may comprises as reference F2, receiving a pre-configured time value. The method may comprise as referenced F3, initiating a timer based on the pre-configured time value, responsive to receipt of the report. The method may comprise as referenced F4, determining that the timer indicates that the preconfigured time value has expired without the data unit being received. The method may comprise as referenced F5, responsive to said determination, updating a lowest sequence number among data units expected to be received to a value greater than the sequence number of the data unit for which the pre-configured time value has expired.

The above example embodiments provide relatively simple techniques for avoiding retransmitting data that is out-dated from an application layer QoS-requirements point of view. Avoiding the re-transmission of out-dated data can be particularly useful for applications with short packet-delay budgets such as extended Reality (XR) applications.

Therefore, although certain example embodiments were described above, by way of non-limiting and illustrative example, and with reference to certain example architectures for communication systems operated by mobile network operators, technologies and standards, further example embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein. For example, some example embodiments have been described in relation to a 5G communication system (5GS). It should be appreciated that other example embodiments may be provided in any other suitable communication system(s) or in any suitable combination with a 5GS.

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, the expression “and/or” includes any and all combinations of the listed terms, including at least any one of the elements, or at least any two or more of the elements, or at least all of the elements.

As used herein, the term “or” refers to a non-exclusive “or” unless otherwise indicated (e.g., use of “or else” or “or in the alternative”).

As used herein, unless stated explicitly, performing a respective feature, step, or functionality “in response to A” does not indicate that the respective feature, step, or functionality is performed immediately after “A” occurs as one or more intervening features, steps, or functionalities may be performed (at least in part) between an occurrence of the respective feature, step, or function and “A”. Analogously, performing a respective feature, step, or functionality “based on A” does not indicate that the respective feature, step, or functionality is performed solely based on “A” as the respective feature, step, or functionality may be further based on one or more other features, steps, or functionalities in addition to “A”.

In general, the various example embodiments of this disclosure may be implemented in hardware or special purpose circuitry, software, logic or any combination thereof. Some aspects of this disclosure may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto. While various aspects of this disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting and illustrative examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

As used herein, 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 herein , including in any claims. As a further example, as used here, 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, an integrated circuit such as a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, and/or other computing or network device.

The various example embodiments of this disclosure may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware. Computer software or program, also called program product, including software routines, applets and/or macros, may be stored in any apparatus-readable data storage medium and they comprise program instructions to perform particular tasks. A computer program product may comprise one or more computerexecutable components which, when the program is run, are configured to carry out the various example embodiments of this disclosure. The one or more computer-executable components may include software code or any portion(s ) thereof.

Further in this regard it should be noted that any blocks of the logic flow as in the Figs, may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on physical media such as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media ( for example DVD and the data variants thereof, CD). The physical media is a non-transitory media.

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).

The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may comprise one or more of general-purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting and illustrative examples.

The various example embodiments of the disclosure may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

The foregoing description has provided, by way of non-limiting and illustrative examples, a full and informative description of the various example embodiments of this disclosure. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the drawings and the claims. Indeed, there are further example embodiments comprising a combination of one or more example embodiments with any of the other example embodiments described herein. The scope of protection sought for some of the various example embodiments of this disclosure is set out by the claims. The various example embodiments in addition to its respective aspects and features thereof described herein that do not fall under the scope of the claims (if any) are to be interpreted as examples useful for understanding the various example embodiments of this disclosure. It should be noted that different claims with differing claim scope may be pursued in related applications, such as divisional or continuation applications.

Claims

1. An apparatus comprising: means for processing transmission of a plurality of data units in accord with a packet data convergence protocol, PDCP; means for creating a report for the plurality of data units, said report providing a sequence number of each data unit of the plurality which has an expiry time shorter than a preconfigured time value; and means for sending the report to a receiver to which the data units are processed to be sent.

2. The apparatus of claim 1 wherein the pre-configured time value is a threshold.

3. The apparatus of claim 1 or claim 2 wherein the means for creating a report creates a report for more than one set of a plurality of data units.

4. The apparatus of any one of claims 1 to 3 wherein the report includes the sequence number of all of the plurality of data units in a set.

5. The apparatus of any one of claims 1 to 4 wherein the report includes the pre-configured time value.

6. The apparatus of any one of claims 1 to 5 further including means for determining the data units of the set being associated with an expiry time less than or equal to the pre-configured time value.

7. The apparatus of any one of claims 1 to 6 wherein the expiry time of at least one data unit is a time-to-live value equal to a remaining time before a discard timer expires.

8. The apparatus of any one of claims 1 to 7 wherein the expiry time of at least one data unit is a time-to-live value equal to a remaining time before a discard timer for relatively low- importance data expires.

9. The apparatus of any one of claims 1 to 8 wherein the means for sending the report is enabled to send the report for the set responsive to one data unit of the set being submitted to a lower layer for transmission.

10. The apparatus of claim 9 wherein the data unit is submitted to an RLC layer.

11. The apparatus of any one of claims 1 to 10 wherein the data unit is a protocol data unit, PDU.

12. A base station comprising the apparatus of any one of claims 1 to 11.

13. A UE comprising the apparatus of any one of claims 1 to 11.

14. An apparatus comprising: means for receiving a report comprising information providing a sequence number for a data unit to be received; means for receiving a pre-configured time value; means for initiating a timer based on the pre-configured time value, responsive to receipt of the report; means for determining that the timer indicates that the pre-configured time value has expired without the data unit being received; and responsive to said determination, the means for receiving is configured to update a lowest sequence number among data units expected to be received to a value greater than the sequence number of the data unit for which the pre-configured time value has expired.

15. The apparatus of claim 14 wherein the data unit is associated with a plurality of data units, the report providing the sequence numbers of all data units in the plurality having an expiry time corresponding to the pre-configured time value, wherein responsive to said determination, the means for receiving is configured to receive a data unit with a sequence number greater than the sequence number of any of the plurality.

16. The apparatus of claim 14 or 15 wherein the means for receiving is configured to adapt a reception window.

17. The apparatus of any one of claims 14 to 16 wherein the means for receiving is configured to receive a data unit other than a sequence number associated with an expired expiry time in any subsequent operation.

18. A base station including the apparatus of any one of claims 14 to 17.

19. A UE including the apparatus of any one of claims 14 to 17.

20. A method comprising: processing transmission of a plurality of data units in accord with a packet data convergence protocol, PDCP; creating a report for the plurality of data units, said report providing a sequence number of each data unit of the plurality which has an expiry time shorter than a pre-configured time value; and sending the report to a receiver to which the data units are processed to be sent.

21. A method comprising: receiving a report comprising information providing a sequence number for a data unit to be received; receiving a pre-configured time value; initiating a timer based on the pre-configured time value, responsive to receipt of the report; determining that the timer indicates that the pre-configured time value has expired without the data unit being received; and responsive to said determination, updating a lowest sequence number among data units expected to be received to a value greater than the sequence number of the data unit for which the pre-configured time value has expired.