WO2020011375A1

WO2020011375A1 - Client device, network access node and methods for updating a discard timer

Info

Publication number: WO2020011375A1
Application number: PCT/EP2018/069155
Authority: WO
Inventors: Rama Kumar MOPIDEVI
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2018-07-13
Filing date: 2018-07-13
Publication date: 2020-01-16

Abstract

The invention relates to updating of a discard timer for a data radio bearer using a medium access control, MAC, control element, CE. A data radio bearer is established between a client device (100) and a network access node (300) and configured with a discard timer. At least one Quality-of-Service, QoS, flow is mapped onto the data radio bearer. The network access node (300) updates the discard timer by transmitting a MAC CE comprising an update instruction for updating a value of the discard timer to the client device (100). Based on the update instruction, the client device (100) update the value of the discard timer. Thereby, the discard timer can be dynamically updated. The update of the discard timer may e.g. be triggered by a change in the QoS flows mapped onto the radio bearer. Furthermore, the invention also relates to corresponding methods and a computer program.

Description

CLIENT DEVICE, NETWORK ACCESS NODE AND METHODS FOR UPDATING A DISCARD TIMER

Technical Field

The invention relates to a client device and a network access node for updating a discard timer. Furthermore, the invention also relates to corresponding methods and a computer program.

Background

The Quality of Service (QoS) architecture in 5G ensures QoS such as e.g. reliability and target delay by mapping data packets to appropriate QoS flows and data radio bearers (DRBs). The 5G core (5GC) establishes one or more protocol data unit (PDU) sessions for each user equipment (UE). A PDU session is an association between the UE and a data network that provides exchange of PDUs. The next generation radio access network (NG-RAN) establishes one or more DRBs per PDU session. At non-access stratum (NAS) level, NAS packet filters in the UE and in the 5GC associate uplink and downlink data packets with QoS flows. At access stratum (AS) level, AS mapping rules in the UE and in the NG-RAN associate uplink and downlink QoS flows with DRBs, respectively. Hence, there is a two-step mapping in the 5G QoS model, first from IP-flows to QoS flows (NAS) and then from QoS flows to DRBs (AS).

At AS level, the DRB defines the data packet treatment on the radio interface. A DRB serves data packets with the same packet forwarding treatment. The QoS flow to DRB mapping by the NG-RAN is based on QoS flow ID (QFI) and the associated QoS profiles, i.e. QoS parameters and QoS characteristics. Separate DRBs may be established for QoS flows requiring different packet forwarding treatment, or several QoS flows belonging to the same PDU session can be multiplexed onto the same DRB. Within each PDU session, it is up to the NG-RAN how to map QoS flows onto DRBs. The NG-RAN may map a guaranteed bit rate (GBR) flow and a non-GBR flow, or more than one GBR flow to the same DRB.

Summary

An objective of embodiments of the invention is to provide a solution which mitigates or solves the drawbacks and problems of conventional solutions.

The above and further objectives are solved by the subject matter of the independent claims. Further advantageous embodiments of the invention can be found in the dependent claims. According to a first aspect of the invention, the above mentioned and other objectives are achieved with a client device for a wireless communication system, the client device being configured to

establish a data radio bearer with a network access node, wherein at least one Quality- of-Service, QoS, flow is mapped onto the data radio bearer and wherein the data radio bearer is configured with a discard timer;

receive a medium access control, MAC, control element, CE, from the network access node, wherein the MAC CE comprises an update instruction for updating a value of the discard timer;

update the value of the discard timer based on the update instruction.

A discard timer can in this disclosure be understood to mean a timer associated with discarding of data packets, e.g. a timer controlling for how long a data packet is buffered before the data packet is discarded. The value of the discard timer can e.g. be set based on a packet delay budget of a QoS flow.

An advantage of the client device according to the first aspect is that the value of the discard timer used by the client device for the data radio bearer can be updated by the network access node using layer 2 signalling. Thereby, a dynamic and fast update of the value of the discard timer can be achieved.

In an implementation form of a client device according to the first aspect, the update instruction indicates an update value for the discard timer.

An advantage with this implementation form is that the client device obtains the update value for the discard timer directly from the update instruction.

In an implementation form of a client device according to the first aspect, at least two QoS flows are mapped onto the data radio bearer.

The at least two QoS flows can have different QoS requirements.

An advantage with this implementation form is that it offers the flexibility to the network access node to map several QoS flows, where the QoS flows can have different QoS requirements, onto one data radio bearer. In an implementation form of a client device according to the first aspect, the client device is further configured to

receive the MAC CE from the network access node upon a QoS flow mapped onto the data radio bearer being added or removed by the network access node.

An advantage with this implementation form is that a change in QoS flows mapped onto the data radio bearer can trigger an update of the value of the discard timer. Thereby, the discard behaviour of the data radio bearer in the client device can be adapted to the QoS flows currently mapped onto the data radio bearer.

In an implementation form of a client device according to the first aspect, the MAC CE further comprises a packet duplication instruction for activating or deactivating packet duplication for the data radio bearer, and the client device is further configured to

activate or deactivate packet duplication for the data radio bearer based on the packet duplication instruction.

Hence, in this implementation form the same MAC CE comprises both the update instruction for updating a value of the discard timer and the packet duplication instruction for activating or deactivating packet duplication for the data radio bearer.

An advantage with this implementation form is that, when packet duplication is configured for the data radio bearer, a single MAC CE can be used to update the value of the discard timer value and to activate or deactivate packet duplication. Thereby, the signalling overhead can be minimized.

In an implementation form of a client device according to the first aspect, the client device is further configured to

obtain a data packet to be transmitted over the data radio bearer to the network access node;

start the discard timer with the updated value upon obtaining the data packet; and discard the data packet if the discard timer expires before the data packet has been transmitted over the data radio bearer to the network access node.

An advantage with this implementation form is that data packets experiencing buffering delay exceeding the discard timer may be discarded, which in turn saves radio resources and also reduces end to end delay for other data packets in the buffer. In an implementation form of a client device according to the first aspect, the client device is further configured to receive the data packet at a packet data convergence protocol, PDCP, layer and the data packet is a PDCP service data unit, SDU.

The PDCP layer can receive the data packet from a higher layer such as e.g. a service data adaptation protocol, SDAP, layer or an application layer.

An advantage with this implementation form is that it complies with the standardized behaviour specified in 3GPP standards.

receive a data radio bearer configuration message from the network access node, wherein the data radio bearer configuration message comprises a discard timer configuration; establish the data radio bearer with the network access node based on the data radio bearer configuration message; and

configure the data radio bearer with the discard timer based on the discard timer configuration.

In an implementation form of a client device according to the first aspect, the data radio bearer configuration message is a radio resource control, RRC, message.

According to a second aspect of the invention, the above mentioned and other objectives are achieved with a network access node for a wireless communication system, the network access node being configured to

establish a data radio bearer with a client device, wherein at least one Quality-of-Service, QoS, flow is mapped onto the data radio bearer and wherein the data radio bearer is configured with a discard timer;

transmit a medium access control, MAC, control element, CE, to the client device, wherein the MAC CE comprises an update instruction for updating a value of the discard timer. An advantage of the network access node according to the second aspect is that the network access node can update the value of the discard timer used by the client device for the data radio bearer using layer 2 signalling. Thereby, a dynamic and fast update of the value of the discard timer can be achieved.

In an implementation form of a network access node according to the second aspect, the update instruction indicates an update value for the discard timer.

An advantage with this implementation form is that the network access node can update the value of the discard timer for the data radio bearer to the update value.

In an implementation form of a network access node according to the second aspect, at least two QoS flows are mapped onto the data radio bearer.

The at least two QoS flows can have different QoS requirements.

An advantage with this implementation form is that it offers the flexibility to the network access node to map several QoS flows, where the QoS flows can have different QoS requirements, onto one data radio bearer.

In an implementation form of a network access node according to the second aspect, the network access node further configured to

add or remove a QoS flow mapped onto the data radio bearer;

transmit the MAC CE to the client device upon adding or removing the QoS flow mapped onto the data radio bearer.

An advantage with this implementation form is that a change in QoS flows mapped onto the data radio bearer can trigger an update of the value of the discard timer. Thereby, the network access node can adapt the discard behaviour of the data radio bearer in the client device to the QoS flows currently mapped onto the data radio bearer.

In an implementation form of a network access node according to the second aspect, the MAC CE further comprises a packet duplication instruction for activating or deactivating packet duplication for the data radio bearer.

transmit a data radio bearer configuration message to the client device, wherein the data radio bearer configuration message comprises a discard timer configuration;

establish the data radio bearer with the client device based on the data radio bearer configuration message.

In an implementation form of a network access node according to the second aspect, the data radio bearer configuration message is a radio resource control, RRC, message.

According to a third aspect of the invention, the above mentioned and other objectives are achieved with a method for a client device, the method comprises

establishing a data radio bearer with a network access node, wherein at least one Quality-of-Service, QoS, flow is mapped onto the data radio bearer and wherein the data radio bearer is configured with a discard timer;

receiving a medium access control, MAC, control element, CE, from the network access node, wherein the MAC CE comprises an update instruction for updating a value of the discard timer;

updating the value of the discard timer based on the update instruction.

The method according to the third aspect can be extended into implementation forms corresponding to the implementation forms of the client device according to the first aspect. Hence, an implementation form of the method comprises the feature(s) of the corresponding implementation form of the client device.

The advantages of the methods according to the third aspect are the same as those for the corresponding implementation forms of the client device according to the first aspect. According to a fourth aspect of the invention, the above mentioned and other objectives are achieved with a method for a network access node, the method comprises

establishing a data radio bearer with a client device, wherein at least one Quality-of- Service, QoS, flow is mapped onto the data radio bearer and wherein the data radio bearer is configured with a discard timer;

transmitting a medium access control, MAC, control element, CE, to the client device, wherein the MAC CE comprises an update instruction for updating a value of the discard timer.

The method according to the fourth aspect can be extended into implementation forms corresponding to the implementation forms of the network access node according to the second aspect. Hence, an implementation form of the method comprises the feature(s) of the corresponding implementation form of the network access node.

The advantages of the methods according to the fourth aspect are the same as those for the corresponding implementation forms of the network access node according to the second aspect.

The invention also relates to a computer program, characterized in program code, which when run by at least one processor causes said at least one processor to execute any method according to embodiments of the invention. Further, the invention also relates to a computer program product comprising a computer readable medium and said mentioned computer program, wherein said computer program is included in the computer readable medium, and comprises of one or more from the group: ROM (Read-Only Memory), PROM (Programmable ROM), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically EPROM) and hard disk drive.

Further applications and advantages of the embodiments of the invention will be apparent from the following detailed description.

Brief Description of the Drawings

The appended drawings are intended to clarify and explain different embodiments of the invention, in which:

- Fig. 1 shows a client device according to an embodiment of the invention;

- Fig. 2 shows a method for a client device according to an embodiment of the invention;

- Fig. 3 shows a network access node according to an embodiment of the invention;

- Fig. 4 shows a method for a network access node according to an embodiment of the invention; - Fig. 5 shows a wireless communication system according to an embodiment of the invention;

- Fig. 6 shows a format of a MAC CE comprising update instructions according to embodiments of the invention;

- Fig. 7 shows the format of a duplication activation/deactivation MAC CE;

- Fig. 8 shows a format of a MAC CE comprising update instructions and packet duplication instructions according to embodiments of the invention.

Detailed Description

One of the main requirements for new radio (NR) also known as 5G is to support a wide range of services with completely diverging requirements. For example, services requiring extremely low latency and high reliability such as ultra reliable low latency (URLLC) services, as well as services requiring high throughput such as enhanced mobile broadband (eMBB) services. To support extreme requirements on latency and reliability for URLLC type services, packet duplication in NR multi-connectivity scenarios can be used. The duplication of data transmissions can increase reliability at the cost of double radio resource consumption. It has been agreed to support packet duplication for both user plane and control plane in packet data convergence protocol (PDCP). Thus, the PDCP function in the transmitter supports packet duplication at the transmitter and the PDCP function in the receiver supports duplicate packet removal.

A UE may be configured to support more than one URLLC service along with other non URLLC services, e.g. eMBB. In uplink, service data adaptation protocol (SDAP) provides the mapping between QoS flows and DRBs. The SDAP also marks each data packet with a QoS flow ID and submits the data packets to PDCP. When the PDCP receives a data packet, the PDCP starts a timer called“discardTimer” for the data packet if configured. The discardTimer reflects the packet delay budget of the QoS flow and is configured by the network per DRB. The discardTimer has values ranging from 10 ms to infinity according to the standard, see Section 6.3.2 in 3GPP 38.331 v15.1 .0. Note, that values less than 10ms may also be supported. If the discardTimer expires for a data packet, PDCP discards the data packet.

The discardTimer can be configured with radio resource control (RRC) signaling and the value of the discardTimer can only be modified by RRC signaling in NR. Hence, the value of the discardTimer stays the same during the lifetime of the DRB unless the discardTimer is reconfigured by the network with RRC signaling. The inventors have identified that this may cause problems in certain scenarios, e.g. when several QoS flows with different QoS requirements are mapped to a single DRB configured with a discardTimer. To have a single, fixed value of the discardTimer may lead to data packets being discarded too fast for some QoS flows and/or too large buffering delay for some QoS flows, resulting in bad quality of experience for the end user.

Consider e.g. the following use case: a DRB serving several QoS flows with different traffic pattern. Assume that at least one QoS flow generates traffic periodically and at least one generates bursty traffic. Having a single, fixed discardTimer for the DRB serving both types may not provide optimal quality of experience for the end user.

A single, fixed value of the discardTimer may further cause problems for a DRB serving several QoS flows and configured with packet duplication. Once packet duplication is configured for a DRB, packet duplication can be activated and de-activated by means of a medium access control (MAC) control element (CE). As described earlier, packet duplication was introduced to increase reliability of URLLC services. If packet duplication is deactivated, then a different discardTimer value may be appropriate for the other QoS flows than the URLLC QoS flows.

Changing discardTimer with RRC signaling is not quick enough and increases RRC signaling load in the network. Therefore, the invention provides a mechanism by which the network can update the discardTimer for a DRB dynamically using a new MAC CE.

Fig. 1 shows a client device 100 according to an embodiment of the invention. In the embodiment shown in Fig. 1 , the client device 100 comprises a processor 102, a transceiver 104 and a memory 106. The processor 102 is coupled to the transceiver 104 and the memory 106 by communication means 108 known in the art. The client device 100 further comprises an antenna or antenna array 1 10 coupled to the transceiver 104, which means that the client device 100 is configured for wireless communications in a wireless communication system.

That the client device 100 is configured to perform certain actions should in this disclosure be understood to mean that the client device 100 comprises suitable means, such as e.g. the processor 102 and the transceiver 104, configured to perform said actions.

According to embodiments of the invention the client device 100 is configured to establish a data radio bearer with a network access node 300 (shown in Fig. 3). At least one QoS flow is mapped onto the data radio bearer and the data radio bearer is configured with a discard timer. The client device 100 is further configured to receive a MAC CE from the network access node 300. The MAC CE comprises an update instruction for updating a value of the discard timer. Based on the update instruction the client device 100 is configured to update the value of the discard timer for the data radio bearer.

Fig. 2 shows a flow chart of a corresponding method 200 which may be executed in a client device 100, such as the one shown in Fig. 1 . The method 200 comprises establishing 202 a data radio bearer with a network access node 300. At least one QoS flow is mapped onto the data radio bearer and the data radio bearer is configured with a discard timer. The method 200 further comprises receiving 204 a MAC CE comprising an update instruction for updating a value of the discard timer from the network access node 300 and updating 206 the value of the discard timer based on the update instruction.

Fig. 3 shows a network access node 300 according to an embodiment of the invention. In the embodiment shown in Fig. 3, the network access node 300 comprises a processor 302, a transceiver 304 and a memory 306. The processor 302 is coupled to the transceiver 304 and the memory 306 by communication means 308 known in the art. The network access node 300 may be configured for both wireless and wired communications in wireless and wired communication systems, respectively. The wireless communication capability is provided with an antenna or antenna array 310 coupled to the transceiver 304, while the wired communication capability is provided with a wired communication interface 312 coupled to the transceiver 304.

That the network access node 300 is configured to perform certain actions should in this disclosure be understood to mean that the network access node 300 comprises suitable means, such as e.g. the processor 302 and the transceiver 304, configured to perform said actions.

According to embodiments of the invention the network access node 300 is configured to establish a data radio bearer with a client device 100. At least one QoS flow is mapped onto the data radio bearer and the data radio bearer is configured with a discard timer. The network access node 300 is configured to transmit a MAC CE to the client device 100, where the MAC CE comprises an update instruction for updating a value of the discard timer.

Fig. 4 shows a flow chart of a corresponding method 400 which may be executed in a network access node 300, such as the one shown in Fig. 3. The method 400 comprises establishing 402 a data radio bearer with a client device 100. At least one QoS flow is mapped onto the data radio bearer and the data radio bearer is configured with a discard timer. The method 400 further comprises transmitting 404 a MAC CE to the client device 100, where the MAC CE comprises an update instruction for updating a value of the discard timer.

Fig. 5 shows a wireless communication system 500 according to an implementation. The wireless communication system 500 comprises a client device 100 and a network access node 300 configured to operate in the wireless communication system 500. For simplicity, the wireless communication system 500 shown in Fig. 5 only comprises one client device 100 and one network access node 300. However, the wireless communication system 500 may comprise any number of client devices 100 and any number of network access nodes 300 without deviating from the scope of the invention.

In the embodiment shown in Fig. 5, a data radio bearer DRB is established between the client device 100 and the network access node 300 based on a data radio bearer configuration message 502. The network access node 300 transmits the data radio bearer configuration message 502 to the client device 100 and establishes the data radio bearer DRB with the client device 100 based on the data radio bearer configuration message 502. The data radio bearer configuration message 502 may be a RRC message such as e.g. a conventional RRC message used for establishing data radio bearers.

The data radio bearer configuration message 502 transmitted by the network access node 300 may comprise information for configuring the data radio bearer DRB and for setting the packet forwarding behaviour of the data radio bearer DRB. In embodiments, the data radio bearer configuration message 502 may comprises a discard timer configuration. In this case, the client device 100 receives the data radio bearer configuration message 502 from the network access node 300, where the data radio bearer configuration message 502 comprises a discard timer configuration and establishes the data radio bearer DRB with the network access node 300 based on the data radio bearer configuration message 502. Based on the discard timer configuration from the data radio bearer configuration message 502, the client device 100 configures the data radio bearer DRB with the discard timer.

The discard timer determines the discard behaviour of a data radio bearer in the client device 100 for data packets from the client device 100 to the network access node 300, i.e. uplink data packets. The client device 100 obtains a data packet to be transmitted over the data radio bearer to the network access node 300. Upon obtaining the data packet, the client device 100 starts the discard timer. The discard timer is started with a value of the discard timer configured for the data radio bearer. The value of the discard timer may be the value given in the discard timer configuration or an updated value as will be described further below. If the discard timer expires before the data packet has been transmitted over the data radio bearer to the network access node 300, the client device 100 discards the data packet. In other words, the discard timer determines the time the obtained data packet is stored in a buffer associated with the data radio bearer.

According to embodiments of the invention the obtaining of the data packet by the client device 100, may comprise the client device 100 receiving the data packet at a packet data convergence protocol layer (PDCP), where the data packet is a PDCP service data unit (SDU). The PDCP layer may receive the PDCP SDU from a higher layer such as e.g. a SDAP layer or an application layer of the client device 100.

One or more QoS flows may be mapped onto the data radio bearer established between the client device 100 and the network access node 300. Depending on the QoS requirements of the QoS flows mapped onto the data radio bearer the discard behaviour of the data radio bearer may need to be adapted. According to embodiments of the invention the discard timer configured for the data radio bearer can therefore be updated using a MAC CE comprising an update instruction for updating the value of the discard timer. The MAC CE may be transmitted by the network access node 300 and received by the client device 100. Upon receiving a MAC CE comprising an update instruction for updating the value of the discard timer, the client device 100 updates the value of the discard timer based on the update instruction. In embodiments, the update instruction indicates an update value for the discard timer. In this case, the client device 100 updates or sets the value of the discard timer to the update value indicated in the update instruction.

In embodiments, at least two QoS flows are mapped onto the data radio bearer. The at least two QoS flows may have different QoS requirements. For example, one or more QoS flows may be GBR flows, while one or more QoS flows are non-GBR flows. Hence, the network access node 300 may have the flexibility to map several QoS flows to one data radio bearer, where one or more of the QoS flows mapped onto the data radio bearer have QoS requirements which differs from the rest of the QoS flows mapped onto the data radio bearer.

When the QoS flows mapped onto the data radio bearer are updated, it might be desirable to change the discard behavior of the data radio bearer. An update of the QoS flows mapped onto the data radio bearer may comprise the network access node 300 adding or removing a QoS flow mapped onto the data radio bearer. Upon adding or removing the QoS flow mapped onto the data radio bearer, the network access node 300 may transmit a MAC CE comprising an update instruction for updating a value of the discard timer to the client device 100. Thus, the client device 100 may receive the MAC CE from the network access node 300 upon a QoS flow mapped onto the data radio bearer being added or removed by the network access node 300. As already described, the MAC CE comprises an update instruction for updating a value of the discard timer. However, the MAC CE may in embodiments further comprise a packet duplication instruction for activating or deactivating packet duplication for the data radio bearer. In other words, the same MAC CE may comprise both an update instruction for updating a value of the discard timer and a packet duplication instruction for activating or deactivating packet duplication for the data radio bearer. When the client device 100 receives such a MAC CE, the client device 100 updates the value of the discard timer based on the update instruction and activates or deactivates packet duplication for the data radio bearer based on the packet duplication instruction. Thereby, a single MAC CE can be used to activate/deactivate packet duplication and to change the value of the discard timer when packet duplication is configured for a data radio bearer.

The MAC CE according to embodiments of the invention may be identified based on a pre defined logical channel ID (LCID). According to the NR standard, a MAC CE is identified by a MAC PDU subheader with a LCID value. The LCID values and their use are specified in Table 1 .

Table 1

A LCID from the reserved LCID values may be used to identify the MAC CE comprising an update instruction, e.g. LCID 10001 1. The MAC CE comprising an update instruction may be of variable size and comprise update instructions for more than one data radio bearer. An example format for such a MAC CE is shown in Fig. 6. In the format shown in Fig. 6, the DRB fields indicates a data radio bearer. Each DRB field is followed by a discardTimerlndex field associated with the data radio bearer indicated in the DRB field. The reserved fields are included to make the values byte aligned. The length of the fields in the format shown in Fig. 6 are examples and any number of bits can be used for the respective fields. Each discardTimerlndex may be mapped to a value of the discard timer. Table 2 shows one example of the mapping between discardTimerlndex and the value of the discard timer, when 1 byte is used for the discardTimerlndex field. Note that the shown values are example and can be set to any value by the network access node 300.

Table 2

When the MAC CE according to embodiments of the invention comprise an update instruction and a packet duplication instruction a different LCID from the reserved LCID values may be used to identify the MAC CE, e.g. LCID 100010. The format of the MAC CE comprising an update instruction and a packet duplication instruction may be based on the format of the conventional duplication activation/deactivation MAC CE with LCID 1 1 1000, see Table 1 . The format of the conventional duplication activation/deactivation MAC CE is specified in 3GGP 38.321 v15.1 .0 and has a fixed size of 1 byte containing 8 D-fields. Fig. 7 shows the format of the conventional duplication activation/deactivation MAC CE. The D, field indicates the activation/deactivation status of PDCP duplication of the i:th data radio bearer, where i is the ascending order of data radio bearer IDs configured with duplication. The D, field is set to one to indicate that PDCP duplication of the i:th data radio bearer shall be activated. The D, field is set to zero to indicate that PDCP duplication of the i:th data radio bearer shall be deactivated.

Fig. 8 show the format of the MAC CE according to embodiments of the invention comprise an update instruction and a packet duplication instruction, i.e. a new duplication activation/deactivation MAC CE further comprising values of the discard timer for each data radio bearer. The discardTimerlndexi field indicates the value of the discard timer of the i:th data radio bearer where i is the ascending order of data radio bearer IDs configured with duplication. In the format shown in Fig. 8, one byte is used for the discardTimerlndex field. However, any number of bits can be used for the discardTimerlndex field. The mapping between discardTimerlndex and the value of the discard timer may be the same as for the MAC CE only comprising an update instruction, i.e. the mapping shown in Table 2 may be used.

The client device 100 herein, may be denoted as a user device, a User Equipment (UE), a mobile station, an internet of things (loT) device, a sensor device, a wireless terminal and/or a mobile terminal, is enabled to communicate wirelessly in a wireless communication system, sometimes also referred to as a cellular radio system. The UEs may further be referred to as mobile telephones, cellular telephones, computer tablets or laptops with wireless capability. The UEs in this context may be, for example, portable, pocket-storable, hand-held, computer- comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data, via the radio access network, with another entity, such as another receiver or a server. The UE can be a Station (STA), which is any device that contains an IEEE 802.1 1 -conformant Media Access Control (MAC) and Physical Layer (PHY) interface to the Wireless Medium (WM). The UE may also be configured for communication in 3GPP related LTE and LTE-Advanced, in WiMAX and its evolution, and in fifth generation wireless technologies, such as New Radio.

The network access node 300 herein may also be denoted as a radio network access node, an access network access node, an access point, or a base station, e.g. a Radio Base Station (RBS), which in some networks may be referred to as transmitter,“gNB”,“gNodeB”,“eNB”, “eNodeB”,“NodeB” or“B node”, depending on the technology and terminology used. The radio network access nodes may be of different classes such as e.g. macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. The radio network access node can be a Station (STA), which is any device that contains an IEEE 802.1 1 -conformant Media Access Control (MAC) and Physical Layer (PHY) interface to the Wireless Medium (WM). The radio network access node may also be a base station corresponding to the fifth generation (5G) wireless systems.

Furthermore, any method according to embodiments of the invention may be implemented in a computer program, having code means, which when run by processing means causes the processing means to execute the steps of the method. The computer program is included in a computer readable medium of a computer program product. The computer readable medium may comprise essentially any memory, such as a ROM (Read-Only Memory), a PROM (Programmable Read-Only Memory), an EPROM (Erasable PROM), a Flash memory, an EEPROM (Electrically Erasable PROM), or a hard disk drive.

Moreover, it is realized by the skilled person that embodiments of the client device 100 and the network access node 300 comprises the necessary communication capabilities in the form of e.g., functions, means, units, elements, etc., for performing the solution. Examples of other such means, units, elements and functions are: processors, memory, buffers, control logic, encoders, decoders, rate matchers, de-rate matchers, mapping units, multipliers, decision units, selecting units, switches, interleavers, de-interleavers, modulators, demodulators, inputs, outputs, antennas, amplifiers, receiver units, transmitter units, DSPs, MSDs, TCM encoder, TCM decoder, power supply units, power feeders, communication interfaces, communication protocols, etc. which are suitably arranged together for performing the solution.

Especially, the processor(s) of the client device 100 and the network access node 300 may comprise, e.g., one or more instances of a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The expression“processor” may thus represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above. The processing circuitry may further perform data processing functions for inputting, outputting, and processing of data comprising data buffering and device control functions, such as call processing control, user interface control, or the like.

Finally, it should be understood that the invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims.

Claims

1 . A client device (100) for a wireless communication system (500), the client device (100) being configured to

establish a data radio bearer with a network access node (300), wherein at least one Quality-of-Service, QoS, flow is mapped onto the data radio bearer and wherein the data radio bearer is configured with a discard timer;

receive a medium access control, MAC, control element, CE, from the network access node (300), wherein the MAC CE comprises an update instruction for updating a value of the discard timer;

update the value of the discard timer based on the update instruction.

2. The client device (100) according to claim 1 , wherein the update instruction indicates an update value for the discard timer.

3. The client device (100) according to claim 1 or 2, wherein at least two QoS flows are mapped onto the data radio bearer.

4. The client device (100) according to any of the preceding claims, configured to

receive the MAC CE from the network access node (300) upon a QoS flow mapped onto the data radio bearer being added or removed.

5. The client device (100) according to any of the preceding claims, wherein the MAC CE further comprises a packet duplication instruction for activating or deactivating packet duplication for the data radio bearer, and configured to

6. The client device (100) according to any of the preceding claims, configured to

obtain a data packet to be transmitted over the data radio bearer;

start the discard timer with the updated value upon obtaining the data packet; and discard the data packet if the discard timer expires before the data packet has been transmitted over the data radio bearer.

7. The client device (100) according to claim 6, wherein obtain the data packet comprises receive the data packet at a packet data convergence protocol, PDCP, layer and wherein the data packet is a PDCP service data unit, SDU.

8. The client device (100) according to any of the preceding claims, configured to receive a data radio bearer configuration message (502) from the network access node (300), wherein the data radio bearer configuration message (502) comprises a discard timer configuration;

establish the data radio bearer with the network access node (300) based on the data radio bearer configuration message (502); and

9. The client device (100) according to 8, wherein the data radio bearer configuration message (502) is a radio resource control, RRC, message.

10. A network access node (300) for a wireless communication system (500), the network access node (300) being configured to

establish a data radio bearer with a client device (100), wherein at least one Quality-of- Service, QoS, flow is mapped onto the data radio bearer and wherein the data radio bearer is configured with a discard timer;

transmit a medium access control, MAC, control element, CE, to the client device (100), wherein the MAC CE comprises an update instruction for updating a value of the discard timer.

1 1 . The network access node (300) according to claim 10, wherein the update instruction indicates an update value for the discard timer.

12. The network access node (300) according to claim 10 or 1 1 , wherein at least two QoS flows are mapped onto the data radio bearer.

13. The network access node (300) according to any of claim 10 to 12, configured to

add or remove a QoS flow mapped onto the data radio bearer;

transmit the MAC CE to the client device (100) upon adding or removing the QoS flow mapped onto the data radio bearer.

14. The network access node (300) according to any of claim 10 to 13, wherein the MAC CE further comprises a packet duplication instruction for activating or deactivating packet duplication for the data radio bearer.

15. The network access node (300) according to any of claim 10 to 14, configured to transmit a data radio bearer configuration message (502) to the client device (100), wherein the data radio bearer configuration message (502) comprises a discard timer configuration;

establish the data radio bearer with the client device (100) based on the data radio bearer configuration message (502).

16. The network access node (300) according to 15, wherein the data radio bearer configuration message (502) is a radio resource control, RRC, message.

17. A method (200) for a client device (100), the method (200) comprises

establishing (202) a data radio bearer with a network access node (300), wherein at least one Quality-of-Service, QoS, flow is mapped onto the data radio bearer and wherein the data radio bearer is configured with a discard timer;

receiving (204) a medium access control, MAC, control element, CE, from the network access node (300), wherein the MAC CE comprises an update instruction for updating a value of the discard timer;

updating (206) the value of the discard timer based on the update instruction.

18. A method (400) for a network access node (300), the method (400) comprises

establishing (402) a data radio bearer with a client device (100), wherein at least one Quality-of-Service, QoS, flow is mapped onto the data radio bearer and wherein the data radio bearer is configured with a discard timer;

transmitting (404) a medium access control, MAC, control element, CE, to the client device (100), wherein the MAC CE comprises an update instruction for updating a value of the discard timer.

19. A computer program with a program code for performing a method according to claim 17 or 18 when the computer program runs on a computer.