WO2021028040A1

WO2021028040A1 - User plane packet delay measurement

Info

Publication number: WO2021028040A1
Application number: PCT/EP2019/071828
Authority: WO
Inventors: Richard Waldhauser; Guillaume DECARREAU
Original assignee: Nokia Technologies Oy
Priority date: 2019-08-14
Filing date: 2019-08-14
Publication date: 2021-02-18

Abstract

Devices, methods and computer programs for user plane packet delay measurement are disclosed. Sequence numbers of data packets for which user plane packet delay is to be measured, are determined by a control plane network node. The control plane network node causes transmission of delay measurement information comprising an indication of the determined sequence numbers to user plane network nodes. In response to receiving at the control plane network node transmission times and reception times at measurement points for the data packets from the user plane network nodes, the control plane network node calculates the user plane packet delays for the data packets by subtracting the received transmission times from the corresponding received reception times.

Description

USER PLANE PACKET DELAY MEASUREMENT

TECHNICAL FIELD

The present application generally relates to the field of wireless communications. In particular, the present applica tion relates to a control plane network node and a user plane network node, and related methods and computer programs.

BACKGROUND

The fifth generation (5G) or so called new radio (NR) wireless networks allow providing new wireless communication services that require low latency. One such service is known as ultra-reliable low-latency communication (URLLC). For communi cations requiring low latency, delay measurements are needed to prove that various requirements (such as those stemming from standards and/or service level agreements) are fulfilled by the 5G system (5GS).

The 5G networks also allow providing integration with time sensitive networks (TSN) via bridges and/or links. For proper integration of 5GS and TSN, a control instance of the TSN needs to be informed about the delay of the 5GS -bridge/link.

SUMMARY

The scope of protection sought for various example em bodiments of the invention is set out by the independent claims. The example embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various example embodiments of the invention.

An example embodiment of a control plane network node comprises at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the control plane network node to at least perform: determining sequence numbers of one or more data packets for which user plane packet delay is to be measured, per data radio bearer; providing delay measurement information comprising an indication of the determined sequence numbers to one or more user plane network nodes; and in response to obtaining transmission times and reception times at predetermined measurement points for the one or more data packets from the one or more user plane network nodes, calculating the user plane packet delays for the one or more data packets by subtracting the obtained transmission times from the corresponding obtained reception times.

In an example embodiment, alternatively or in addition to the above-described example embodiments, the delay measurement information further comprises an indication of a delay measurement direction.

In an example embodiment, alternatively or in addition to the above-described example embodiments, the control plane network node comprises a central unit of a first radio access network node, a central unit control plane entity of a second radio access network node, or a third radio access network node.

In an example embodiment, alternatively or in addition to the above-described example embodiments, the user plane network node comprises a client device, a central unit of a first radio access network node, a central unit user plane entity of a second radio access network node, or a third radio access network node.

In an example embodiment, alternatively or in addition to the above-described example embodiments, the sequence numbers comprise packet data convergence protocol sequence numbers or radio link control sequence numbers.

In an example embodiment, alternatively or in addition to the above-described example embodiments, the measurement point for the transmission time comprises a service access point subsequent to a service data adaptation protocol layer, and the measurement point for the reception time comprises a service access point prior to the service data adaptation protocol layer.

In an example embodiment, alternatively or in addition to the above-described example embodiments, the indication of the determined sequence numbers comprises a list of sequence numbers, a range of sequence numbers, or a formula defining sequence numbers.

An example embodiment of a control plane network node comprises means for performing: determining sequence numbers of one or more data packets for which user plane packet delay is to be measured, per data radio bearer; providing delay measurement information comprising an indication of the determined sequence numbers to one or more user plane network nodes; and in response to obtaining transmission times and reception times at predetermined measurement points for the one or more data packets from the one or more user plane network nodes, calculating the user plane packet delays for the one or more data packets by subtracting the obtained transmission times from the corresponding obtained reception times.

An example embodiment of a user plane network node comprises at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the user plane network node to at least perform: obtaining, from a control plane network node, delay measurement information comprising an indication of sequence numbers of one or more data packets for which user plane packet delay is to be measured, per data radio bearer; measuring at least one of transmission times or reception times at predetermined measurement points for the one or more data packets from a user data packet stream including the one or more data packets with the indicated sequence numbers; and providing the measured at least one of transmission times or reception times to the control plane network node.

In an example embodiment, alternatively or in addition to the above-described example embodiments, the user data packet stream comprises a packet data convergence protocol user data packet stream.

An example embodiment of a user plane network node comprises means for performing: obtaining, from a control plane network node, delay measurement information comprising an indication of sequence numbers of one or more data packets for which user plane packet delay is to be measured, per data radio bearer; measuring at least one of transmission times or reception times at predetermined measurement points for the one or more data packets from a user data packet stream including the one or more data packets with the indicated sequence numbers; and providing the measured at least one of transmission times or reception times to the control plane network node.

An example embodiment of a method of user plane packet delay measurement comprises: determining, by a control plane network node, sequence numbers of one or more data packets for which user plane packet delay is to be measured, per data radio bearer; providing, by the control plane network node, delay measurement information comprising an indication of the determined sequence numbers to one or more user plane network nodes; and in response to obtaining at the control plane network node transmission times and reception times at predetermined measurement points for the one or more data packets from the one or more user plane network nodes, calculating, by the control plane network node, the user plane packet delays for the one or more data packets by subtracting the obtained transmission times from the corresponding obtainedreception times.

An example embodiment of a computer program product comprises program code configured to perform the method accord ing to any of the above control plane network node related ex ample embodiments, when the computer program product is executed on a computer.

An example embodiment of a method of user plane packet delay measurement comprises: obtaining at a user plane network node from a control plane network node, delay measurement information comprising an indication of sequence numbers of one or more data packets for which user plane packet delay is to be measured, per data radio bearer; measuring, by the user plane network node, at least one of transmission times or reception times at predetermined measurement points for the one or more data packets from a user data packet stream including the one or more data packets with the indicated sequence numbers; and providing, by the user plane network node, the measured at least one of transmission times or reception times to the control plane network node.

In an example embodiment, alternatively or in addition to the above-described example embodiments, the user plane network node comprises a client device, a central unit of a first radio access network node, a central unit user plane entity of a second radio access network node, or a third radio access network node. In an example embodiment, alternatively or in addition to the above-described example embodiments, the control plane network node comprises a central unit of a first radio access network node, a central unit control plane entity of a second radio access network node, or a third radio access network node.

An example embodiment of a computer program product comprises program code configured to perform the method accord ing to any of the above user plane network node related example embodiments, when the computer program product is executed on a computer.

DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to pro vide a further understanding of the embodiments and constitute a part of this specification, illustrate embodiments and to gether with the description help to explain the principles of the embodiments. In the drawings: FIG. 1A shows an example embodiment of the subject mat ter described herein illustrating an example system, where var ious example embodiments of the present disclosure may be im plemented;

FIG. IB shows an example embodiment of a radio access network node logically split into a central unit (further split into a control plane entity and a user plane entity), and distributed units;

FIG. 2A shows an example embodiment of the subject mat ter described herein illustrating a user plane network node;

FIG. 2B shows an example embodiment of the subject mat ter described herein illustrating a control plane network node;

FIG. 3 shows an example embodiment of the subject matter described herein illustrating a method of user plane packet delay measurement;

FIG. 4 shows an example embodiment of the subject matter described herein further illustrating delay measurement for downlink;

FIG. 5 shows an example embodiment of the subject matter described herein illustrating a method of user plane packet delay measurement in uplink direction; and

FIG. 6 shows an example embodiment of the subject matter described herein illustrating a method of user plane packet delay measurement in downlink direction.

Like reference numerals are used to designate like parts in the accompanying drawings.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. The detailed description provided below in connection with the appended drawings is intended as a description of the present examples and is not intended to represent the only forms in which the present example may be constructed or utilized. The descrip tion sets forth the functions of the example and the sequence of steps for constructing and operating the example. However, the same or equivalent functions and sequences may be accomplished by different examples. FIG. 1A illustrates an example fifth generation system (5GS) 100, where various embodiments of the present disclosure may be implemented. The system 100 may comprise e.g. a fifth generation core network (5GC) 110, a next generation radio access network (NG-RAN) 120, and a user equipment (UE) 170. The NG-RAN 120 may comprise e.g. a base station or gNB 130 that is flat or non-split, i.e. without a CU-DU split. The non-split gNB 130 may comprise e.g. an enhanced fourth generation (4G) base station (ng-eNB). Alternatively/additionally the NG-RAN 120 may comprise e.g. a 5G base station or gNB 140A that is split into a gNB- central unit (gNB-CU) 141A and one or more gNB-distributed units (gNB-DU) 142Ai, 142A₂. The 5G gNB 140A may provide 5G user plane (UP) and control plane (CP) protocol termination towards the UE 170, and the enhanced 4G gNB (or ng-eNB) 130 may provide LTE (long term evolution) UP and CP protocol termination towards the UE 170.

UP may be used to carry user traffic, such as voice, and Internet traffic, whereas CP may be used to carry e.g. con trol messages used for signaling in the 5GS 100.

NG interfaces 150i, 150₂ may be used e.g. to provision such functions as handover and bearer management. Xn-C interface 160 may be used e.g. to provision such functions as handover between gNBs and dual connectivity between different radio tech nologies. FI interfaces 143Ai, 143A₂ may be used e.g. to carry up in GPRS (general packet radio service) tunneling protocol for user data (GTP-U). Also, CP may be carried on the FI interfaces 143Ai, 143A₂ for UE context management, and/or bearer management to setup, modify and/or release bearers.

A 5G capable user equipment (UE) 170 may be connected over a 5G air interface with a gNB or a DU, or it may be connected over a 4G interface with a ng-eNB. In both cases, the UE 170 gets connected by the NG-RAN 120 with the 5GC 110.

The UE 170 may include e.g. a mobile phone, a smartphone, a tablet computer, a smart watch, or any suitable hand-held or portable device. The UE 170 may also be referred to as a client device.

The gNB-CU 141A is a logical node that may host higher layer protocols, such as radio resource control (RRC), service data adaptation protocol (SDAP), and packet data convergence protocol (PDCP). The gNB-DUs 142Ai, 142A₂ are logical nodes that may host e.g. radio link control (RLC), medium access control (MAC), and physical (PHY) layers.

As shown in Fig. IB, it is also possible to deploy a gNB-CU by splitting it into a control plane part or entity (gNB- CU-CP) 141Bi and one or more user plane parts or entities (gNB- CU-UP) 141B₂. In other words, gNB 140B of Fig. IB is an alter native implementation of gNB 140A of Fig. 1A. In an example, the gNB-CU-UP 141B₂ may be deployed in a cloud. In another example, the gNB-CU-UP 141B₂ may be collocated with the gNB-DUs 142Bi and/or 142B₂. Otherwise, the functionalities of gNB-CU and gNB- DUs in Fig. IB may correspond with their counterparts in Fig 1A so they are not repeated here.

El interface 145B may be used e.g. to provide exchange of signaling information between the gNB-CU-CP 141Bi and the gNB- CU-UP 141B₂. Fl-C interface 143B may be used e.g. to provide control plane inter-connection of the gNB-CUs (gNB-CU-CP 141Bi, gNB-CU-UP I4IB₂) and a gNB-DU (e.g. supplied by different manu facturers), whereas Fl-U interface 144B may be used e.g. to provide user plane inter-connection of the gNB-CUs (gNB-CU-CP 141Bi, gNB-CU-UP I4IB₂) and a gNB-DU (e.g. supplied by different manufacturers) .

The 5GS 100 may also be integrated with one or more external networks, such as a time sensitive network (TSN).

FIG. 2B is a block diagram of a control plane network node 210, in accordance with an example embodiment. For example, the control plane network node 210 may comprise a central unit of a first radio access network node, such as the 5G base station (or any such device suitable for providing an air interface for client devices to connect to the wireless 5G network via wireless transmissions) or gNB 140A of Fig. 1A. In another example, the control plane network node 210 may comprise a central unit control plane entity or part (such as the gNB-CU-CP 141Bi of Fig. IB) of a second, radio access network node (such as the 5G base station or gNB 140B of Fig. IB). In another example, the control plane network node 210 may comprise a third radio access network node, such as gNB 130 of Fig. 1A.

Herein, the term "first radio access network node" is used to refer to a 5G capable radio access network node that is split into a central unit (CU) and a distributed unit (DU), but wherein the central unit is not further split into a central unit control plane entity (CU-CP) and a central unit user plane entity (CU-UP). The term "second radio access network node" is used to refer to a 5G capable radio access network node that is split into a central unit and a distributed unit, and wherein the central unit is further split into a central unit control plane entity and a central unit user plane entity. The term "third radio access network node" is used to refer to a 5G capable radio access network node that is not split into a central unit and a distributed unit (and thus a central unit is not further split into a central unit control plane entity and a central unit user plane entity either).

The control plane network node 210 comprises one or more processors 212, and one or more memories 214 that comprise computer program code. The control plane network node 210 may also include a transceiver 215, as well as other elements, such as an input/output module (not shown in FIG. 2B), and/or a com munication interface (not shown in FIG. 2B).

Although the control plane network node 210 is depicted to include only one processor 212, the control plane network node 210 may include more processors. In an embodiment, the memory 214 is capable of storing instructions, such as an oper ating system and/or various applications.

Furthermore, the processor 212 is capable of executing the stored instructions. In an embodiment, the processor 212 may be embodied as a multi-core processor, a single core processor, or a combination of one or more multi-core processors and one or more single core processors. For example, the processor 212 may be embodied as one or more of various processing devices, such as a coprocessor, a microprocessor, a controller, a digital sig nal processor (DSP), a processing circuitry with or without an accompanying DSP, or various other processing devices including integrated circuits such as, for example, an application spe cific integrated circuit (ASIC), a field programmable gate array (FPGA), a microcontroller unit (MCU), a hardware accelerator, a special-purpose computer chip, or the like. In an embodiment, the processor 212 may be configured to execute hard-coded func tionality. In an embodiment, the processor 212 is embodied as an executor of software instructions, wherein the instructions may specifically configure the processor 212 to perform the algo rithms and/or operations described herein when the instructions are executed.

The memory 214 may be embodied as one or more volatile memory devices, one or more non-volatile memory devices, and/or a combination of one or more volatile memory devices and non volatile memory devices. For example, the memory 214 may be embodied as semiconductor memories (such as mask ROM, PROM (pro grammable ROM), EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.).

The at least one memory 214 and the computer program code are configured to, with the at least one processor 212, cause the control plane network node 210 to perform determining sequence numbers (SN) of one or more data packets for which user plane packet delay is to be measured, per data radio bearer (DRB).

For example, the sequence numbers may comprise packet data convergence protocol (PDCP) sequence numbers or radio link control (RLC) sequence numbers. The indication of the determined sequence numbers may comprise a list of sequence numbers, a range of sequence numbers, and/or a formula/equation that defines sequence numbers. An example comprises one optional repetition- offset value, one or more ranges defined by a PDCP-SN-first and an optional PDCP-SN-last value. If the PDCP-SN-last value is missing or the PDCP SN values of a range have identical values, then the range consists of one PDCP-SN value. The presence of the repetition-offset value indicates a periodic measurement because the measurement is repeated by incrementing the first/last values repeatedly by the repetition-offset value. The measuring points may send periodic Delay Measurment Results until the measurement is stopped by the gNB/CU using a Delay Measurement Stop message or automatically, e.g. in case of maximal number of repetions, or automatically by providing a maximum-measurement-duration-time value or a maximum-number-of- repetions value in the measurement configuration.

The at least one memory 214 and the computer program code are further configured to, with the at least one processor 212, cause the control plane network node 210 to perform providing (e.g. transmitting via transceiver 215, delivering and/or arranging for retrieval) delay measurement information to one or more user plane network nodes 200 (described in more detail below in connection with Fig. 2A). The delay measurement information comprises an indication of the determined sequence numbers. The delay measurement information may further comprise e.g. an indication of a delay measurement direction, such as downlink direction or uplink direction. Alternatively, the indication of a delay measurement direction may comprise information about the role (such as sender or receiver of the user data packet stream containing the data packets for which user plane packet delay is to be measured) of the respective user plane network node in the delay measurement. The delay measurement information may further comprise identifier(s) for the measurement (e.g. Measurement-ID or GNB-CU-CP-UE-E1AP-ID/UE- ID, Bearer/DRB-ID).

In other words, the control plane network node 210 (comprising e.g. gNB 140A or gNB-CU-CP 141Bi) responsible for the delay measurement in the RAN may determine the sequence numbers (e.g. PDCP-SNs) of packets to be measured per DRB and inform the corresponding one or more user plane network nodes 200 (comprising e.g. gNB-CU-UP 141B₂ and/or UE 170) of the PDCP termination points about these SNs and whether they are the sending or the receiving PDCP termination point of the packet(s). Alternatively, instead of configuring the role of the measure ment point explicitly, it may be indicated whether the measure ment is for the uplink direction or the downlink direction. The SNs may be e.g. a list of dedicated SNs, one or more ranges of SNs, or formulas (e.g. modulo which allows the use of periodic SN) determining the SNs or SN ranges to be measured.

In response to obtaining (e.g. receiving via transceiver 215 and/or retrieving) transmission times and reception times at predetermined measurement points for the one or more data packets from the one or more user plane network nodes 200, the at least one memory 214 and the computer program code are further configured to, with the at least one processor 212, cause the control plane network node 210 to perform calculating the user plane packet delays for the one or more data packets by subtracting the obtained transmission times from the corresponding obtained reception times. The control plane network node 210 may also generate averages or histograms for the calculated packet delays.

For example, the measurement point for the transmission time (Tl) may comprise a service access point (SAP) subsequent to a service data adaptation protocol (SDAP) layer. The measurement point for the reception time (T2) may comprise a service access point prior to the SDAP layer. FIG. 4 illustrates an example of measurement points for a downlink (DL) measurement case. In this example, sender 410 corresponds with e.g. the gNB- CU-UP 141E>₂ and receiver 420 corresponds with e.g. the UE 170. As can be seen from Fig. 4, here the measurement point for the transmission time Tl comprises the SAP after the SDAP layer and before the PDCP layer in the sender 410, and the measurement point for the reception time T2 comprises the SAP after the PDCP layer and before the SDAP layer in the receiver 420. In other words, the times Tl and T2 may indicate the point in time when a packet to be measured (determined e.g. by its PDCP-SN) crosses the respective measurement point, e.g. the respective SAP between SDAP and PDCP layer.

Delay measurements related communication between a gNB and UE may be performed using RRC. For a gNB split in CU and DU, additional communication over the FI interface may be performed. For a CU split in CU-CP/CU-UP, additional communication over the El interfaces may be performed.

FIG. 2A is a block diagram of a user plane network node 200, in accordance with an example embodiment. For example, the user plane network node 200 may comprise a client device, such as the UE 170 of Fig. 1A. A client device may be any of various types of devices used directly by an end user entity and capable of communication in a wireless 5G network. Such devices include but are not limited to smartphones, tablet computers, smart watches, lap top computers, Internet-of-Things (IoT) devices, etc. Additionally/alternatively, the user plane network node 200 may comprise a central unit of a first radio access network node such as the 5G base station (or any such device suitable for providing an air interface for client devices to connect to the wireless 5G network via wireless transmissions) or gNB 140A of Fig. 1A. Additionally/alternatively, the user plane network node 200 may comprise a central unit user plane entity or part (such as the gNB-CU-UP 141E>₂ of Fig. IB) of a second radio access network node (such as the 5G base station or gNB 140B of Fig. IB). Additionally/alternatively, the user plane network node 200 may comprise a a third radio access network node, such as gNB 130 of Fig. 1A.

The user plane network node 200 comprises one or more processors 202, and one or more memories 204 that comprise com puter program code. The user plane network node 200 may also include a transceiver 205, as well as other elements, such as an input/output module (not shown in FIG. 2A), and/or a communica tion interface (not shown in FIG. 2A).

Although the user plane network node 200 is depicted to include only one processor 202, the user plane network node 200 may include more processors. In an embodiment, the memory 204 is capable of storing instructions, such as an operating system and/or various applications.

Furthermore, the processor 202 is capable of executing the stored instructions. In an embodiment, the processor 202 may be embodied as a multi-core processor, a single core processor, or a combination of one or more multi-core processors and one or more single core processors. For example, the processor 202 may be embodied as one or more of various processing devices, such as a coprocessor, a microprocessor, a controller, a digital sig nal processor (DSP), a processing circuitry with or without an accompanying DSP, or various other processing devices including integrated circuits such as, for example, an application spe cific integrated circuit (ASIC), a field programmable gate array (FPGA), a microcontroller unit (MCU), a hardware accelerator, a special-purpose computer chip, or the like. In an embodiment, the processor 202 may be configured to execute hard-coded func tionality. In an embodiment, the processor 202 is embodied as an executor of software instructions, wherein the instructions may specifically configure the processor 202 to perform the algo rithms and/or operations described herein when the instructions are executed.

The memory 204 may be embodied as one or more volatile memory devices, one or more non-volatile memory devices, and/or a combination of one or more volatile memory devices and non- volatile memory devices. For example, the memory 204 may be embodied as semiconductor memories (such as mask ROM, PROM (pro grammable ROM), EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.).

The at least one memory 204 and the computer program code are configured to, with the at least one processor 202, cause the user plane network node 200 to perform obtaining (e.g. receiving via transceiver 205, and/or retrieving), from the control plane network node 210, delay measurement information comprising an indication of sequence numbers of one or more data packets for which user plane packet delay is to be measured, per data radio bearer.

The at least one memory 204 and the computer program code are further configured to, with the at least one processor 202, cause the user plane network node 200 to perform measuring transmission times and/or reception times at predetermined measurement points for the one or more data packets from a user data packet stream including the one or more data packets with the indicated sequence numbers. For example, the user data packet stream may comprise a packet data convergence protocol (PDCP) user data packet stream.

The at least one memory 204 and the computer program code are further configured to, with the at least one processor 202, cause the user plane network node 200 to perform providing (e.g. transmitting via transceiver 205, delivering and/or arranging for retrieval) the measured transmission times and/or reception times to the control plane network node 210. In addition to the measured time value (s), the associated identifier (s) of the measurement and/or the associated PDCP- SN(s) may be transmitted from the user plane network node 200 to the control plane network node 210.

In other words, the sending user plane network node 200 may inform its control plane network node 210 about the time of arrival (Tl) of a measured PDCP SDU at the SAP from a client layer (e.g. SDAP) for the sender of the packet, and the receiving user plane network node 200 may inform its control plane network node 210 about the time of delivery (T2) of a measured PDCP SDU at the SAP to the client layer for the receiver of the packet. Further features (such as those related to the sequence numbers and their indications, delay measurement information, measurement points, delay measurement directions) of the user plane network node 200 directly result from the functionalities and parameters of the control plane network node 210 and thus are not repeated here.

In an example embodiment, the control plane network node 210 comprises a central unit (such as the gNB-CU 141A of Fig. 1A) of a first radio access network node (such as the gNB 140A of Fig. 1A). The user plane network nodes 200 comprise a client device (such as the UE 170 of Fig. 1A) and the central unit (such as the gNB-CU 141A of Fig. 1A) of the first radio access network node (such as the gNB 140A of Fig. 1A). The client device receives the delay measurement information from the central unit, measures either the transmission times or the reception times, and transmits the measured times to the central unit. The central unit (or more specifically, its processes/components or the like responsible for the measurements) measures either the reception transmission times or the transmission times, respectively, based on the delay measurement information previously provided by the central unit itself, and then arranges the measured times for internal retrieval for the delay calculation (e.g. by its processes/components or the like responsible for the delay calculation).

In another example embodiment, the control plane network node 210 comprises a central unit control plane entity or part (such as the gNB-CU-CP 141Bi of Fig. IB) of a second radio access network node (such as the gNB 140B of Fig. IB). The user plane network nodes 200 comprise a client device (such as the UE 170 of Fig. 1A) and a central unit user plane entity or part (such as the gNB-CU-UP 141B₂ of Fig. IB) of the second radio access network node (such as the gNB 140B of Fig. IB). The client device receives the delay measurement information from the central unit control plane entity, measures either the transmission times or the reception times, and transmits the measured times to the central unit control plane entity. The central unit user plane entity receives or retrives the delay measurement information from the central unit control plane entity, measures either the reception times or the transmission times, respectively, and transmits the measured times to the central unit control plane entity (or arranges them for retrieval by the central unit control plane entity).

In yet another example embodiment, the control plane network node 210 comprises a (non-split) third radio access network node (such as the gNB 130 of Fig. 1A). The user plane network nodes 200 comprise a client device (such as the UE 170 of Fig. 1A) and the third radio access network node (such as the gNB 130 of Fig. 1A). The client device receives the delay measurement information from the third radio access network node, measures either the transmission times or the reception times, and transmits the measured times to the third radio access network node. The third radio access network node (or more specifically, its processes/components or the like responsible for the measurements) measures either the reception transmission times or the transmission times, respectively, based on the delay measurement information previously provided by the third radio access network node itself, and then arranges the measured times for internal retrieval (e.g. by its processes/components or the like responsible for the delay calculation).

In the above example embodiments, the control plane network node 210 may comprise a SON (self-organization network) function, and it may be responsible for providing the delay measurements in the NG-RAN. The control plane network node 210 determines which PDCP SN(s) per DRB are the subjects of the delay measurement, it configures the time measurement with the in volved entities, it receives the results for the determined PDCP- SN(s) from the involved entities, and it calculates the delay as requested by a client function of the SON function.

Further in the above example embodiments, the time ref erence (or clock) used to measure the delay may be the same in the involved entities. It may be e.g. the time given by a GPS (global positioning system) receiver, or the time given by a SIB (system information block) 9 (time info), or the time with ref erence to a SFN (system frame number) of the cell.

Stringent time synchronization requirements are ex pected for TSN, e.g. for industrial automation. The required synchronization precision is usually given as the maximum abso lute value of the time difference between sync master and any device in the synchronization domain (time domain or clock do main). A common example is a synchronization precision of <= lys. In case of 5GS/TSN integration, the gNB and the UEs con nected to it may be a part of a so-called "global time domain". Clock synchronization in the global time domain may apply to all UEs within the industrial facility in industrial automation. That is, a global time domain may cover the industrial facility.

As discussed above and as illustrated in the following examples of Fig. 5 and Fig. 6, the control plane (CP) communi cation between UE and gNB may use the RRC protocol. In case of CU/DU and CP/UP split, the RRC protocol may be used between UE and CU-CP. Between DU and CU-CP, the transfer of RRC messages may be performed by FlAPiRRC Message Transfer Function (MTF). In case of CP/CU split, the communication between CU-CP and CU-UP may be performed by using E1AP.

FIG. 5 shows an example embodiment of the subject matter described herein illustrating a method 500 of user plane packet delay measurement in uplink (UL) direction.

In this UL measurement, UE 170 informs the gNB-CU-CP 141Bi about Tl, and the gNB-CU-UP 141B₂ informs the gNB-CU-CP 141Bi about T2. Here, the UE 170 has the role of sender, and the gNB-CU-UP 141B₂ has the role of receiver.

At step 501, the gNB-CU-CP 141Bi configures a first involved UP PDCP termination point (gNB-CU-UP I4IB₂) for the delay measurement, as detailed above. Similarly, at step 502, the gNB-CU-CP 141Bi configures a second involved UP PDCP termi nation point (UE 170) for the delay measurement.

At steps 501 and 502, the gNB-CU-CP 141Bi sends the Delay Measurement Setup messages to each of the gNB-CU-UP 141B₂ and UE 170 in order to inform the delay measurement information. The delay measurement information includes a Configuration in formation element (IE). The Configuration IE includes a UE-ID, a role field indicating a role of the delay measurement (i.e., Receiver or Sender of user data) and an object field including a list of DRBs and a list of PDCP-CNs and/or SN-formula to be used for the delay measurement. At step 503, the gNB-CU-UP 141E>₂ prepares itself for the delay measurement based on the delay measurement information received at step 501. At step 504, the UE 170 prepares itself for the delay measurement based on the delay measurement infor mation received at step 502. Both the gNB-CU-UP 141B₂ and the UE 170 send acknowledgements to the gNB-CU-CP 141Bi after completing their delay measurement preparations, steps 505, 506.

At step 507, a packet data convergence protocol (PDCP) user data packet stream is being transferred in UL direction. This PDCP user data packet stream contains the packets to be measured. For example, the PDCP user data packet strem includes the packets indicated by the delay measurement information at step 502.

The UE 170 measures T1 and sends it to the gNB-CU-CP 141Bi, step 508. The gNB-CU-UP 141B₂ measures T2 and sends it to the gNB-CU-CP 141Bi, step 509.

At steps 508 and 509, each of the UE 170 and the gNB- CU-UP 141B₂ transmits the Delay Measurement Result message to the gNB-CU-CP 141Bi. The Delay Measurement result message in cludes the Results information element (IE). The Results IE includes the Role field indicating the UE is a sender or the gNB-CU-UP 141B₂ is a receiver. In addition, the Result IE also includes the List of PDCP-SNs and their measured send time or receive time (i.e., T1 or T2) according to who transmits the message.

Then, the gNB-CU-CP 141Bi calculates the packet delay per DRB as T2-T1, step 510.

The method 500 may be performed by the control plane network node 210 of Fig. 2B and one or more user plane network nodes 200 of Fig. 2A. Further features of the method 500 directly result from the functionalities and parameters of the control plane network node 210 and the user plane network node 200 and thus are not repeated here. The method 500 can be performed by computer program (s).

FIG. 6 shows an example embodiment of the subject matter described herein illustrating a method 600 of user plane packet delay measurement in downlink (DL) direction.

In this DL measurement, UE 170 informs the gNB-CU-CP 141Bi about T2, and the gNB-CU-UP 141B₂ informs the gNB-CU-CP 141Bi about Tl. Here, the UE 170 has the role of receiver, and the gNB-CU-UP 141B₂ has the role of sender.

At step 601, the gNB-CU-CP 141Bi configures a first involved UP PDCP termination point (gNB-CU-UP I4IB₂) for the delay measurement, as detailed previously. Similarly, at step 602, the gNB-CU-CP 141Bi configures a second involved UP PDCP termination point (UE 170) for the delay measurement.

At steps 601 and 602, the same type messages of the steps 501 and 502 are used but the role is different because of a direction of transmission data (i.e., downlink direction). So, the sender is set to the gNB-CU-UP 141B₂ and the receiver is set to the UE 170.

At step 603, the gNB-CU-UP 141B₂ prepares itself for the delay measurement based on the delay measurement information received at step 601. At step 604, the UE 170 prepares itself for the delay measurement based on the delay measurement infor mation received at step 602. Both the gNB-CU-UP 141B₂ and the UE 170 send acknowledgements to the gNB-CU-CP 141Bi after completing their delay measurement preparations, steps 605, 606.

At step 607, a packet data convergence protocol (PDCP) user data packet stream is being transferred in DL direction. This PDCP user data packet stream contains the packets to be measured.

The gNB-CU-UP 141B₂ measures Tl and sends it to the gNB- CU-CP 141Bi, step 608. The UE 170 measures T2 and sends it to the gNB-CU-CP 141Bi, step 609.

At steps 608 and 609, the same messages with the steps 508 and 509 are used but the setting of the role field is dif ferent according to the direction of the data. So, the UE 170 transmits the T2 via the Delay Measurement Result message and the gNB-CU-UP 141B2 transmits the Tl via the Delay Measurement Result message.

Then, the gNB-CU-CP 141Bi calculates the packet delay per DRB as T2-T1, step 610.

The method 600 may be performed by the control plane network node 210 of Fig. 2B and one or more user plane network nodes 200 of Fig. 2A. Further features of the method 600 directly result from the functionalities and parameters of the control plane network node 210 and the user plane network node 200 and thus are not repeated here. The method 600 can be performed by computer program (s).

In the various example embodiments described herein, the messages reporting about the measured points in time (T1/T2) may be sent when all the packets to be monitored according to the measurement configuration have arrived, or periodically in case a periodic delay measurement has been configured. This con figuration may be done explicitly (by parameter) or implicitly (by formula).

In the various example embodiments described herein, the CP entity communication for the configuration of the meas urement may occur early enough to allow the sending/receiving side to be ready to recognize and associate the time T1/T2 with the sequence number of the measured packet when these are ar riving from or delivered to the measurement point (e.g. SAP). For example, the gNB / gNB-CU-CP may have information about typical delays for the CP communication (e.g. average of sending a message to the UE until the awaited acknowledgement is re ceived, or QoS requirements) that has been received for the bearer to be measured. With this information, the gNB / gNB-CU- CP may estimate the PDCP-SNs that will arrive soon after the measurement points receive the measurement configuration mes sages.

FIG. 3 illustrates an example signaling diagram of a method 300 of user plane packet delay measurement, in accordance with an example embodiment.

In operation 301, the control plane network node 210 determines sequence numbers of one or more data packets for which user plane packet delay is to be measured, per data radio bearer.

In operation 302, the control plane network node 210 provides delay measurement information comprising an indication of the determined sequence numbers to the user plane network node (s) 200.

In operation 303, the user plane network node(s) 200 obtains the delay measurement information from the control plane network node 210.

In operation 304, the user plane network node(s) 200 measures at least one of transmission times or reception times at predetermined measurement points for the one or more data packets from a user data packet stream that includes the one or more data packets with the indicated sequence numbers.

In operation 305, the user plane network node(s) 200 provides the measured at least one of transmission times or reception times to the control plane network node 210.

In operation 306, the control plane network node 210 obtains the transmission times and reception times from the user plane network node(s) 200.

In operation 307, the control plane network node 210 calculates the user plane packet delays for the one or more data packets by subtracting the obtained transmission times from the corresponding obtained reception times.

The method 300 may be performed by the control plane network node 210 of Fig. 2B and one or more user plane network nodes 200 of Fig. 2A. Further features of the method 300 directly result from the functionalities and parameters of the control plane network node 210 and the user plane network node 200 and thus are not repeated here. The method 300 can be performed by computer program (s).

At least some of the embodiments described herein may allow user plane packet delay measurement. At least some of the embodiments may allow user plane packet delay measurement without having to modify the user plane for performing the measurement. In other words, at least some of the embodiments may allow user plane packet delay measurement without injection of special packets or time stamps into headers. At least some of the embodiments may allow user plane packet delay measurement without additional packet inspection.

Accordingly, at least some of the embodiments may allow user plane packet delay measurement without increasing the user plane processing load, without higher over-the-air overhead, and therefore without impacting performance, including reliability, I.e. at least some of the embodiments may allow user plane packet delay measurement without downgrading the peak data rate.

Furthermore, at least some of the embodiments may allow user plane packet delay measurement without becoming a bottleneck for URLLC which requires user plane latency that is as short as 0.5 ms. The functionality described herein can be performed, at least in part, by one or more computer program product com ponents such as software components. According to an embodiment, the client device 200 and/or control plane network node 210 comprise a processor configured by the program code when executed to execute the embodiments of the operations and functionality described. Alternatively, or in addition, the functionality de scribed herein can be performed, at least in part, by one or more hardware logic components. For example, and without limi tation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), Program- specific Integrated Circuits (ASICs), Program-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Pro grammable Logic Devices (CPLDs), and Graphics Processing Units (GPUs).

Any range or device value given herein may be extended or altered without losing the effect sought. Also any embodiment may be combined with another embodiment unless explicitly dis allowed.

Although the subject matter has been described in lan guage specific to structural features and/or acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts de scribed above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims.

It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It will further be understood that reference to 'an' item may refer to one or more of those items.

The steps of the methods described herein may be car ried out in any suitable order, or simultaneously where appro priate. Additionally, individual blocks may be deleted from any of the methods without departing from the spirit and scope of the subject matter described herein. Aspects of any of the em bodiments described above may be combined with aspects of any of the other embodiments described to form further embodiments without losing the effect sought. The term 'comprising' is used herein to mean including the method, blocks or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements.

It will be understood that the above description is given by way of example only and that various modifications may be made by those skilled in the art. The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments. Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the dis closed embodiments without departing from the spirit or scope of this specification.

Claims

CLAIMS :

1. A control plane network node (210), comprising: at least one processor (212); and at least one memory (214) including computer program code; the at least one memory (214) and the computer program code configured to, with the at least one processor (212), cause the control plane network node (210) to at least perform: determining sequence numbers of one or more data packets for which user plane packet delay is to be measured, per data radio bearer; providing delay measurement information comprising an indication of the determined sequence numbers to one or more user plane network nodes (200); and in response to obtaining transmission times and reception times at predetermined measurement points for the one or more data packets from the one or more user plane network nodes (200), calculating the user plane packet delays for the one or more data packets by subtracting the obtained transmission times from the corresponding obtained reception times.

2. The control plane network node (210) according to claim 1, wherein the delay measurement information further comprises an indication of a delay measurement direction.

3. The control plane network node (210) according to claim 1 or 2, wherein the control plane network node (210) comprises a central unit (141A) of a first radio access network node (140A), a central unit control plane entity (141Bi) of a second radio access network node (140B), or a third radio access network node (130).

4. The control plane network node (210) according to any of claims 1 to 3, wherein the sequence numbers comprise packet data convergence protocol sequence numbers or radio link control sequence numbers.

5. The control plane network node (210) according to any of claims 1 to 4, wherein the measurement point for the transmission time comprises a service access point subsequent to a service data adaptation protocol layer, and the measurement point for the reception time comprises a service access point prior to the service data adaptation protocol layer.

6. The control plane network node (210) according to any of claims 1 to 5, wherein the indication of the determined sequence numbers comprises a list of sequence numbers, a range of sequence numbers, or a formula defining sequence numbers.

7. A user plane network node (200), comprising: at least one processor (202); and at least one memory (204) including computer program code; the at least one memory (204) and the computer program code configured to, with the at least one processor (202), cause the user plane network node (200) to at least perform: obtaining, from a control plane network node (210), delay measurement information comprising an indication of sequence numbers of one or more data packets for which user plane packet delay is to be measured, per data radio bearer; measuring at least one of transmission times or reception times at predetermined measurement points for the one or more data packets from a user data packet stream including the one or more data packets with the indicated sequence numbers; and providing the measured at least one of transmission times or reception times to the control plane network node (210).

8. The user plane network node (200) according to claim 7, wherein the delay measurement information further comprises an indication of a delay measurement direction.

9. The user plane network node (200) according to claim 7 or 8, wherein the user plane network node (200) comprises a user equipment (170), a central unit (141A) of a first radio access network node (140A), a central unit user plane entity (I4IB₂) of a second radio access network node (140B), or a third radio access network node (130).

10. The user plane network node (200) according to any of claims 7 to 9, wherein the user data packet stream comprises a packet data convergence protocol user data packet stream.

11. The user plane network node (200) according to any of claims 7 to 10, wherein the measurement point for the transmission time comprises a service access point subsequent to a service data adaptation protocol layer, and the measurement point for the reception time comprises a service access point prior to the service data adaptation protocol layer.

12. A method of user plane packet delay measurement, comprising: determining (301), by a control plane network node, sequence numbers of one or more data packets for which user plane packet delay is to be measured, per data radio bearer; providing (302), by the control plane network node, delay measurement information comprising an indication of the determined sequence numbers to one or more user plane network nodes; and in response to obtaining (306) at the control plane network node transmission times and reception times at predetermined measurement points for said one or more data packets from the one or more user plane network nodes, calculating (307), by the control plane network node, the user plane packet delays for the one or more data packets by subtracting the obtained transmission times from the corresponding obtained reception times.

13. A computer program product comprising program code configured to perform the method according to claim 12, when the computer program product is executed on a computer.

14. A method of user plane packet delay measurement, comprising: obtaining (303) at a user plane network node from a control plane network node, delay measurement information comprising an indication of sequence numbers of one or more data packets for which user plane packet delay is to be measured, per data radio bearer; measuring (304), by the user plane network node, at least one of transmission times or reception times at predetermined measurement points for the one or more data packets from a user data packet stream including the one or more data packets with the indicated sequence numbers; and providing (305), by the user plane network node, the measured at least one of transmission times or reception times to the control plane network node.

15. A computer program product comprising program code configured to perform the method according to claim 14, when the computer program product is executed on a computer.