WO2020038556A1

WO2020038556A1 - Network access node and client device for quality of service management

Info

Publication number: WO2020038556A1
Application number: PCT/EP2018/072489
Authority: WO
Inventors: Vishnu PREMAN; Rama Kumar Mopidevi
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2018-08-21
Filing date: 2018-08-21
Publication date: 2020-02-27

Abstract

The invention relates to quality of service (QoS) management in a wireless communication system (500). A network access node (100) notifies a client device (300) about the status of a QoS flow between the network access node (100) and the client device (300). In this respect the network access node (100) transmits a first notification (N1) to the client device (300) when a QoS requirement of the QoS flow cannot be fulfilled. The network access node (100) thereafter transmits a second notification (N2) to the client device (300) when the QoS requirement of the QoS flow can be fulfilled again. Thereby, the client device (300) is dynamically updated about the status of the QoS flow and can adapt its transmission based on the current status of the QoS flow for improved performance. Furthermore, the invention also relates to corresponding methods and a computer program.

Description

NETWORK ACCESS NODE AND CLIENT DEVICE FOR QUALITY OF SERVICE MANAGEMENT

Technical Field

The invention relates to a network access node and a client device for efficient quality of service management. Furthermore, the invention also relates to corresponding methods and a computer program.

Background

In 5G new radio (NR), a quality of service (QoS) model supports a QoS flow based framework. The QoS flow is the finest granularity of QoS differentiation in a protocol data unit (PDU) session. The PDU session is an association between a user equipment (UE) and a data network that provides exchange of PDUs. QoS flows that are needed initially by the UE are activated when a PDU session is established.

A QoS flow is identified by a QoS Flow ID (QFI). The characteristics describing the packet forwarding treatment that a QoS flow receives edge to edge between the UE and the user plane function (UPF) are e.g.: resource type, e.g. guaranteed bitrate (GBR), delay critical GBR or non-GBR); priority level; packet delay budget; packet error rate; averaging window; and maximum data burst value.

The resource type determines if dedicated network resources related to maintaining a guaranteed flow bit rate (GFBR) value are permanently allocated. GBR QoS flows have stricter demands than non-GBR QoS flows.

An IP flow (or IP packet flow) from the application is sent to the network using QoS flows, as QoS flow is the smallest granularity in 5G. QoS flows utilize data radio bearers (DRBs) for the transmission of packets to the radio access network (RAN). For every IP packet there are two levels of mapping needed, firstly mapping of IP packets to QoS flows and secondly mapping of QoS flows to DRBs. These mappings are provided and updated by the network.

Reflective QoS is a functionality that is introduced in 5G to change these mappings without the need of explicit signalling. This is achieved by informing the UE about the change in mapping for a QoS flow using the header field of a newly introduced module called service data adaptation protocol (SDAP). The SDAP header contains the QFI to which the IP packet belongs, 1 bit to indicate if reflective QoS is activated and 1 bit to indicate if the reflective mapping of QoS flow to DRB has changed. For example, if the reflective QoS indicator (RQI) bit is set to 1 and the reflective DRB mapping indicator (RDI) is also set to 1 , this means that the QoS flow which is received in a particular DRB has a change in mapping information. Based on the header information of the downlink packet, the uplink packet filter is derived and will be mapped to the new QFI. Similarly, the QFI will be mapped to the DRB through which the downlink packet was received.

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 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 first Quality-of- Service, QoS, flow is mapped onto the data radio bearer;

transmit a first notification to the client device upon determining that a QoS requirement of the first QoS flow cannot be fulfilled, wherein the first notification indicates that the QoS requirement of the first QoS flow cannot (currently) be fulfilled.

The QoS requirement can e.g. be a requirement on bit rate, packet delay, packet error rate, etc. of the first QoS flow. Whether the QoS requirement of the first QoS flow can be fulfilled or not can vary during the lifetime of the fist QoS flow. Any time the network access node determines that the QoS requirement of the first QoS flow cannot be fulfilled, the network access node transmits a first notification, i.e. the first notification is transmitted dynamically during the lifetime of the first QoS flow.

An advantage of the network access node according to the first aspect is that the client device by reception of the first notification can adapt its transmissions due to the non-fulfilment of the QoS requirement of the first QoS flow as indicated by the first notification. Thereby, the transmission performance, such as the packet loss and user experience, is improved. The transmissions can relate to uplink transmissions to the network access node using the data radio bearer. In an implementation form of a network access node according to the first aspect, the network access node is further configured to

transmit a second notification to the client device upon determining that the QoS requirement of the first QoS flow can be fulfilled again, wherein the second notification indicates that the QoS requirement of the first QoS flow can be fulfilled again.

Also, the second notification can be transmitted dynamically during the lifetime of the first QoS flow.

An advantage with this implementation form is that the client device is informed through the reception of the second notification that the QoS requirement of the first QoS flow can be fulfilled again which means that the transmissions can be adapted accordingly. Thereby, the transmission performance of the client device is improved.

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

transmit the first notification and the second notification in a first service data adaptation protocol, SDAP, header associated with the first QoS flow.

An advantage with this implementation form is that a conventional SDAP header format also can be used for transmitting the first and second notifications. Further, in the case that the first SDAP header only comprises 1 byte said first SDAP header comprises the QoS flow identity (QFI) of the first QoS flow thereby allowing the client device to easily distinguish which QoS flow has been impacted with the change in QoS as indicated by the first and second notifications.

transmit the first notification and the second notification in (using) a common (single) bit of the first SDAP header.

An advantage with this implementation form is that the first and second indications are transmitted using 1 single common bit which implies effective signalling with low overhead since only 1 bit is used in this respect. In an implementation form of a network access node according to the first aspect, a first value of the common (single) bit indicates the first notification and a second value of the common (single) bit indicates the second notification.

In an implementation form of a network access node according to the first aspect, the first QoS flow is a guaranteed bit rate QoS flow, and the network access node is configured to

transmit the first notification and the second notification in a bit of the first SDAP header which is dedicated for a reflective QoS indicator of a second SDAP header associated with a second QoS flow mapped onto the data radio bearer, wherein the second QoS flow is non- guaranteed bit rate QoS flow.

This implementation form can also be stated as that the network access node according to the first aspect is configured to

map a second (non-GBR) QoS flow to the data radio bearer, wherein the second data flow supports a non-access stratum reflective QoS and wherein the first SDAP header is of a first SDAP header type;

provide a non-access stratum reflective QoS status indication in a second SDAP header of a second SDAP header type associated with the second QoS flow and carrying an identity of the second QoS flow, wherein the non-access stratum reflective QoS status indication occupies at least the same bit position in the second SDAP header as the bit used for the first indication and the second indication in the first SDAP header.

An advantage with this implementation form is that the first and the second notifications are transmitted in a bit of the first SDAP header which is dedicated for non-access stratum reflective QoS indicator (RQI) for a non-GBR QoS flow of the second SDAP header. Since this bit would not be used for a GBR QoS flow SDAP header this bit can be used for the first notification and second notification for GBR QoS flows. Thereby efficient signalling is provided with minimized impact on SDAP header coding.

In an implementation form of a network access node according to the first aspect, the first SDAP header comprises a first byte and a second byte, wherein the first byte comprises a reflective data radio bearer mapping indicator bit and a reflective QoS indicator bit, and the network access node is further configured to

transmit the first notification and the second notification in a bit of the second byte. An advantage with this implementation form is that the client device does not need to differentiate between GBR and non-GBR flows as the first and second notifications are transmitted in bits entirely dedicated for their use.

In an implementation form of a network access node according to the first aspect, the first SDAP header indicates an identity of the first QoS flow.

An advantage with this implementation form is that the client device can derive the identity of the first QoS flow and hence easily distinguish which QoS flow is affected by the change in QoS as indicated by the first and second notifications.

According to a second 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 first QoS flow is mapped onto the data radio bearer;

receive a first notification from the network access node, wherein the first notification indicates that a QoS requirement of the first QoS flow cannot be fulfilled;

adapt transmission of the first QoS flow in dependence on the first notification.

An advantage of the client device according to the second aspect is that the client device by reception of the first notification can adapt its transmissions due to the non-fulfilment of the QoS requirement of the first QoS flow as indicated by the first notification. Thereby, the transmission performance of the client device is improved.

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

receive a second notification from the network access node, wherein the second notification indicates that the QoS requirement of the first QoS flow can be fulfilled again; adapt the transmission of the first QoS flow in dependence on the second notification.

An advantage with this implementation form is that the client device is informed through the reception of the second notification that the QoS requirement of the first QoS flow can be fulfilled again which means that the transmissions can be adapted accordingly. Thereby, the transmission performance of the client device is improved. In an implementation form of a client device according to the second aspect, the client device is further configured to

receive a first SDAP header associated with the first QoS flow from the network access node;

derive the first notification and the second notification from the first SDAP header.

derive the first notification and the second notification from a common (single) bit of the first SDAP header.

An advantage with this implementation form is that the first and second indications are transmitted using 1 single common bit which implies effective signalling with low overhead since only 1 bit is used in this respect.

derive the first notification from a first value of the common (single) bit and the second notification from a second value of the common (single) bit.

In an implementation form of a client device according to the second aspect, the first QoS flow is a guaranteed bit rate QoS flow, and wherein the client device is configured to

derive the first notification and the second notification from a bit of the first SDAP header which is dedicated for a reflective QoS indicator of a second SDAP header associated with a second QoS flow mapped onto the data radio bearer, wherein the second QoS flow is non- guaranteed bit rate QoS flow.

An advantage with this implementation form is that the first and the second notifications are transmitted in a bit of the first SDAP header which is dedicated for non-access stratum reflective QoS indicator (RQI) for a non-GBR QoS flow of the second SDAP header. Since this bit will not be used for a GBR QoS flow SDAP header efficient signalling is provided with minimized impact on SDAP header coding.

In an implementation form of a client device according to the second aspect, the first SDAP header comprises a first byte and a second byte, the first byte comprises a reflective data radio bearer mapping indicator bit and a reflective QoS indicator bit, and the client device is further configured to

derive the first notification and the second notification from a bit of the second byte.

An advantage with this implementation form is that the client device does not need to differentiate between GBR and non-GBR flows as the first and second notifications are transmitted in a bit entirely dedicated for their use.

In an implementation form of a client device according to the second aspect, the first SDAP header indicates an identity of the first QoS flow, and the client device is further configured to determine the identity of the first QoS flow based on the indicated identity of first the SDAP header.

In an implementation form of a client device according to the second aspect, adapt the transmission of the first QoS flow comprises

adapt the data rate of the first QoS flow.

An advantage with this implementation form is that the performance such as packet loss ratio can be reduced by adapting the packet rate of the first QoS flow based on the first and the second notifications.

In an implementation form of a client device according to the second aspect, adapt the data rate of the first QoS flow comprises at least one of

decrease the data rate in dependence on the first notification; and

increase the data rate in dependence on the second notification.

In an implementation form of a client device according to the second aspect, adapt the transmission of the first QoS flow comprises adapt the data rate of the first QoS flow in an application layer of the client device.

According to a third 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 first QoS flow is mapped onto the data radio bearer;

transmitting a first notification to the client device upon determining that a QoS requirement of the first QoS flow cannot be fulfilled, wherein the first notification indicates that the QoS requirement of the first QoS flow cannot (currently) be fulfilled.

The method according to the third aspect can be extended into implementation forms corresponding to the implementation forms of the network access node according to the first 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 third aspect are the same as those for the corresponding implementation forms of the network access node 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 client device, the method comprises

establishing a data radio bearer with a network access node, wherein at least one first QoS flow is mapped onto the data radio bearer;

receiving a first notification from the network access node, wherein the first notification indicates that a QoS requirement of the first QoS flow cannot (currently) be fulfilled;

adapting transmission of the first QoS flow in dependence on the first notification.

The method according to the fourth aspect can be extended into implementation forms corresponding to the implementation forms of the client device according to the second 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 fourth aspect are the same as those for the corresponding implementation forms of the client device 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 network access node according to an embodiment of the invention;

- Fig. 2 shows a method for a network access node according to an embodiment of the invention;

- Fig. 3 shows a client device according to an embodiment of the invention;

- Fig. 4 shows a method for a client device 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 SDAP header for reflective QoS for non-guaranteed bit rate QoS flows;

- Fig. 7 shows SDAP headers according to an embodiment of the invention;

- Fig. 8 shows SDAP headers according to an embodiment of the invention; and

- Fig. 9 shows a two-byte SDAP header according to an embodiment of the invention.

Detailed Description

Enforcement of QoS characteristics is the responsibility of the RAN, i.e. the next generation RAN (NG-RAN) in 5G. If the QoS cannot be fulfilled by the RAN, and if the RAN informs the UE about this, then the application or the application layer in the UE can take appropriate actions to control the data rate or codec to minimize the packet loss or bad user experience. If the resource type of a QoS flow is GBR, then the RAN needs to ensure that the GFBR is met for the QoS flow. In 5G, there is a notification control mechanism in the NG-RAN to inform the 5G core (5GC) if the GFBR cannot be fulfilled. If, for a given GBR QoS flow, notification control is enabled and the NG-RAN determines that the GFBR cannot be fulfilled, the NG-RAN shall send a notification towards the session management function (SMF). The NG-RAN keeps the QoS flow, while the NG-RAN is not delivering the requested GFBR for this QoS flow, unless specific conditions at the NG-RAN require the release of the NG-RAN resources for this GBR QoS flow, e.g. due to radio link failure (RLF) or RAN internal congestion. Upon receiving a notification from the NG-RAN that the GFBR cannot be fulfilled, the 5GC may through the access and mobility management function (AMF) initiate signalling to modify or remove the QoS flow. When applicable, the NG-RAN sends a new notification, informing SMF that the GFBR can be fulfilled again. After a configured time, the NG-RAN may send a subsequent notification that the GFBR cannot be fulfilled.

The described notification control mechanism informs the 5GC about the failure to fulfil QoS and expect the 5GC to take appropriate actions. However, the UE is not aware that the QoS is not met. Hence, the application in the UE is unaware of the problem and keeps operating assuming that the QoS is fulfilled. This can lead to missing packets and/or bad user experience. Especially, for services requiring extremely low latency and high reliability such as ultra reliable low latency (URLLC) services, this could cause major problems.

Therefore, it is herein presented a solution introducing dynamic notifications to the UE indicating whether the QoS can be fulfilled or not. Thereby enabling the UE to adapt its transmissions to the current QoS condition.

Fig. 1 shows a network access node 100 according to an embodiment of the invention. In the embodiment shown in Fig. 1 , the network access node 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 network access node 100 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 1 10 coupled to the transceiver 104, while the wired communication capability is provided with a wired communication interface 1 12 coupled to the transceiver 104. That the network access node 100 is configured to perform certain actions can in this disclosure be understood to mean that the network access node 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 network access node 100 is configured to establish a data radio bearer with a client device 300 (see Fig. 5). At least one first QoS flow is mapped onto the data radio bearer. The network access node 100 is further configured to transmit a first notification N1 to the client device 300 upon determining that a QoS requirement of the first QoS flow cannot currently be fulfilled. Hence, the first notification N1 indicates that the QoS requirement of the first QoS flow cannot be fulfilled. Fig. 2 shows a flow chart of a corresponding method 200 which may be executed in a network access node 100, such as the one shown in Fig. 1 . The method 200 comprises establishing 202 a data radio bearer with a client device 300, where at least one first QoS flow is mapped onto the data radio bearer. The method 200 further comprises transmitting 204 a first notification N1 to the client device 300 upon determining that a QoS requirement of the first QoS flow cannot currently be fulfilled, where the first notification N1 indicates that the QoS requirement of the first QoS flow cannot be fulfilled.

Fig. 3 shows a client device 300 according to an embodiment of the invention. In the embodiment shown in Fig. 3, the client device 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 client device 300 further comprises an antenna or antenna array 310 coupled to the transceiver 304, which means that the client device 300 is configured for wireless communications in a wireless communication system. That the client device 300 is configured to perform certain actions can in this disclosure be understood to mean that the client device 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 client device 300 is configured to establish a data radio bearer with a network access node 100, where at least one first QoS flow is mapped onto the data radio bearer. The client device 300 is further configured to receive a first notification N1 from the network access node 100, where the first notification N1 indicates that a QoS requirement of the first QoS flow cannot be fulfilled. In dependence on the first notification N1 , the client device 300 is configured to adapt transmission of the first QoS flow.

Fig. 4 shows a flow chart of a corresponding method 400 which may be executed in a client device 300, such as the one shown in Fig. 3. The method 400 comprises establishing 402 a data radio bearer with a network access node 100, where at least one first QoS flow is mapped onto the data radio bearer. The method 400 further comprises receiving 404 a first notification N1 from the network access node 100, where the first notification N1 indicates that a QoS requirement of the first QoS flow cannot be fulfilled. Furthermore, the method 400 comprises adapting 406 transmission of the first QoS flow in dependence on the first notification N1 .

Fig. 5 shows a wireless communication system 500 according to an embodiment of the invention. The wireless communication system 500 comprises a network access node 100 and a client device 300 configured to operate in the wireless communication system 500. For simplicity, the wireless communication system 500 shown in Fig. 5 only comprises one network access node 100 and one client device 300. However, the wireless communication system 500 may comprise any number of network access nodes 100 and any number of client devices 300 without deviating from the scope of the invention. In the example in Fig. 5 the network access node 100 is part of a RAN, such as a NG-RAN in 5G.

In the wireless communication system 500, a data radio bearer is established between the network access node 100 and the client device 300. The establishment of the data radio bearer can be performed according to any predefined procedure of different standards, such as e.g. LTE and 5G. The data radio bearer is used to transmit data between the network access node 100 and the client device 300 and therefore at least one first QoS flow is mapped onto the data radio bearer. The network access node 100 is responsible for enforcing QoS for the first QoS flows mapped onto the data radio bearer and can determine whether a QoS requirement of the first QoS flow can be fulfilled or not based on measurements related to e.g. packet delay and data loss.

According to embodiments of the invention the network access node 100 informs the client device 300 about the determined status of the first QoS flow mapped onto the data radio bearer by transmitting notifications to the client device 300. As shown in Fig. 5, the network access node 100 may transmit a first notification N1 and/or a second notification N2 to the client device 300. The first notification N1 indicates that the QoS requirement of the first QoS flow cannot be fulfilled, while the second notification N2 indicates that the QoS requirement of the first QoS flow can be fulfilled again. Hence, when the network access node 100 determines that the QoS requirement of the first QoS flow cannot be fulfilled, the network access node 100 transmits the first notification N1 indicating that the QoS requirement of the first QoS flow cannot be fulfilled to the client device 300. Furthermore, upon determining that the QoS requirement of the first QoS flow can be fulfilled again, the network access node 100 transmits the second notification N2, indicating that the QoS requirement of the first QoS flow can be fulfilled again, to the client device 300.

Thereby, a dynamic updating mechanism is herein provided such that the client device 300 is continuously informed about the QoS fulfilment for a QoS flow during the lifetime of the QoS flow. With this information the client device 300 can adapt its transmissions accordingly. Hence, when the client device 300 receives the first notification N1 from the network access node 100, the client device 300 (or the application layer in the client device 300) adapts its transmission of the first QoS flow in dependence on the first notification N1 . Furthermore, when the client device 300 receives the second notification N2 from the network access node 100, the client device 300 (or the application layer in the client device 300) adapts its transmission of the first QoS flow in dependence on the second notification N2. In this way, the client device 300 can adapt the transmission of the first QoS flow to changing QoS of the first QoS flow.

That the client device 300 adapts the transmission of the first QoS flow may e.g. mean that the client device 300 adapts the data rate of the first QoS flow. The client device 300 may e.g. decrease the data rate in dependence on the first notification N1 and increase the data rate in dependence on the second notification N2. By decreasing the data rate, the client device 300 can reduce the packet loss. It is also possible for the client device that upon receiving the first notification N1 to use a better codec or compression algorithm to temporarily adjust to the non- fulfilment of QoS, and thereby not compromising the end user experience at the client device 300. However, more processing power is needed in the client device 300 in such a case. Upon receiving the second notification N2, the client device 300 can go back to the codec or compression algorithm used when the QoS is fulfilled. This requires less processing power in the client device 300.

Furthermore, the client device 300 may adapt the data rate of the first QoS flow in an application layer of the client device 300. For example, an application layer in the client device 300 using the first QoS flow may in dependence on the first notification N1 , indicating that the QoS requirement of the first QoS flow cannot be fulfilled, adapt the data rate of the first QoS flow. As previously described, the data rate adaptation may e.g. include decreasing the data rate. However, the data rate adaptation may in embodiments instead include changing to a better codec which compresses the data more but instead requires more processing power in the client device 300. Hence, a more robust data transfer is achieved at the cost of a higher power consumption. This may be acceptable to improve the user experience, as the drop in QoS may be temporary. As soon as the QoS is back to normal, i.e. a second notification N2 is received by the client device 300, the application layer can go back to the normal functioning mode with its data rate. Also, other methods for adapting the data rate can be employed by the client device 300.

That the QoS requirement of the first QoS flow cannot be fulfilled may in embodiments correspond to that a guaranteed flow bit rate (GFBR) for a guaranteed bit rate QoS flow is not met. In this case, the QoS requirement of the first QoS flow is considered to be fulfilled again when the GFBR for the guaranteed bit rate QoS flow is met again. However, the invention is not limited to this scenario. Instead, any QoS requirement requested by an application may be used to determine whether the QoS requirement of the first QoS flow can be fulfilled or not. In other words, when the network access node 100 determines that it is not able to fulfil a QoS requested by an application, the network access node 100 determines that the QoS requirement of the first QoS flow cannot be fulfilled and notifies the client device 300.

According to embodiments of the invention the first notification N1 and the second notification N2 are transmitted or comprised in a SDAP header associated with the first QoS flow. In other words, the network access node 100 may transmit the first notification N1 and the second notification N2 in a first SDAP header associated with the first QoS flow. The client device 300 may hence receive the first SDAP header associated with the first QoS flow from the network access node 100 and derive the first notification N1 and the second notification N2 from the first SDAP header associated with the first QoS flow. For example, a SDAP protocol module in the client device 300 may extract the first notification N1 and the second notification N2 from the first SDAP header associated with the first QoS flow and send it to the application layer of the client device 300 which can adapt the transmission to the change in QoS of the first QoS flow.

In embodiments of the invention, the network access node 100 may transmit the first notification N1 and the second notification N2 in a common single bit of a first SDAP header and the client device 300 may derive the first notification N1 and the second notification N2 from the common single bit of the first SDAP header. Hence, by changing a value of the common single bit the client device 300 may be notified about changes in QoS for the first QoS flow. When a common single bit of the first SDAP header is used, a first value of the common single bit may indicate the first notification N1 and a second value of the common single bit may indicate the second notification N2. Thus, the client device 300 may derive the first notification N1 from the first value of the common single bit and the second notification N2 from the second value of the common single bit. For example, the first value may be Ό’ and the second value may be Ί’, or vice versa. When the common single bit is set to O’, the first SDAP header indicates that the QoS requirement of the first QoS flow cannot be fulfilled. When the value of the common single bit is changed to‘T, the first SDAP header indicates that the QoS requirement of the first QoS flow can be fulfilled again. Toggling the value of the common single bit back to Ό’ indicates that QoS cannot be fulfilled and so on.

According to embodiments of the invention a second SDAP header used to indicate reflective QoS for non-guaranteed bit rate QoS flows may be used to indicate the first notification N1 and the second notification N2 for a guaranteed bit rate QoS flow. Fig. 6 shows a second SDAP header used to indicate reflective QoS for non-guaranteed bit rate QoS flows. The second SDAP header is a 1 -byte header and comprises 1 bit used for a reflective DRB mapping indicator (RDI), 1 bit used for a reflective QoS indicator (RQI), and 6 bits used for a QoS Flow ID (QFI). The QFI bits are used to indicate the identity of the QoS flow of the packet. The RDI bit is used to indicate if an access stratum (AS) level reflective QoS is activated and the RQI bit is used to indicate if a non-access stratum (NAS) level reflective QoS is activated. The RDI bit and the RQI bit is set to one (“1”) when reflective QoS is supported and zero (“0”) when reflective QoS is not supported by the client device 300 or the network access node 100.

The second SDAP header shown in Fig. 6 is configured per data radio bearer to carry reflective QoS information for non-guaranteed bit rate QoS flows. As reflective QoS information is not supported for guaranteed bit rate QoS flows, all bits in the first SDAP header will be set to zero for guaranteed bit rate QoS flows. Thus, the first SDAP header is empty for a guaranteed bit rate QoS flow and may therefore in embodiments be used for the first notification N1 and the second notification N2.

Therefore, according to embodiments of the invention the bit dedicated for the RQI when the first QoS flow is a non-guaranteed bit rate QoS flow is used to transmit and receive the first notification N1 and the second notification N2 when the first QoS flow is a guaranteed bit rate QoS flow. In other words, for a first QoS flow which is a guaranteed bit rate QoS flow, the network access node 100 is configured to transmit the first notification N1 and the second notification N2 in a bit of a first SDAP header which is dedicated for a reflective QoS indicator of a second SDAP header associated with a second QoS flow mapped onto the data radio bearer, which is a non-guaranteed bit rate QoS flow.

Fig. 7 shows a first SDAP header for a guaranteed bit rate QoS where the RQI bit is used for the first notification N1 and the second notification N2. Assume a case where a non-guaranteed bit rate QoS flow and a guaranteed bit rate QoS flow is mapped onto the same data radio bearer. Furthermore, the RQI bit is used to transmit the first notification N1 and the second notification N2 for the guaranteed bit rate QoS flow. The client device 300 may in this case interpret the RQI bit as will now be described with reference to Fig. 8. Fig. 8 shows a SDAP header of a first PDU for a non-guaranteed bit rate QoS flow with QFI=X and a SDAP header for a second PDU for a guaranteed bit rate QoS flow with QFI=Y. When the client device 300 receives the two SDAP headers shown in Fig. 8, the information derived from the two SDAP headers may be forwarded to the NAS layer in the client device 300. The NAS layer checks, for first PDU, the QFI which is X and finds out that the QFI belongs to a non-guaranteed bit rate QoS flow. Therefore, the NAS layer interprets the bit 6 = 1 as RQI, i.e. NAS reflective QoS information, and acts accordingly. For the second PDU, the NAS layer checks the QFI which is Y and finds out that it is a guaranteed bit rate QoS flow. Therefore, the NAS layer reads and interprets the 6th bit (indexed from the rightmost bit) as indicating the first notification N1 or the second notification N2 depending on the bit value“1” or“0” of said bit and acts accordingly.

According to embodiments of the invention the size of a SDAP header used in embodiments of the invention may also be increased from one byte to two bytes, which means that the additional second byte can be used to indicate the first notification N1 and the second notification N2. In other words, the first SDAP header may in embodiments comprise a first byte and a second byte, where the first byte comprises a RDI bit and a RQI bit, and the network access node 100 transmits the first notification N1 and the second notification N2 in a common bit or in separate bits of the second byte. The client device 300 may hence derive the first notification N1 and the second notification N2 from the bit/bits of the second byte.

Fig. 9 shows a SDAP header according to such an embodiment of the invention. The first notification N1 and the second notification N2 are in this example comprised in a common single bit, as previously described. Note, that the bit of the second byte used for the first notification N1 and the second notification N2 in Fig. 9 is a non-limiting example, and any bit of the second byte may comprise the first notification N1 and the second notification N2. Hence, separate bits of the second byte may be used the first notification N1 and the second notification N2, such that one bit is used to transmit the first notification N1 and another bit of the second byte is used to transmit the second notification N2. As also shown in Fig. 9, the first SDAP header indicates an identity of the first QoS flow. The client device 300 identifies the identity of the first QoS flow based on the indicated identity of the first SDAP header. The identity of the first QoS flow are derived from the 6 QFI bits of the first byte in Fig. 9.

The client device 300 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 100 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 node 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 network access node 100 and the client device 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 network access node 100 and the client device 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 network access node (100) for a wireless communication system (500), the network access node (100) being configured to

establish a data radio bearer with a client device (300), wherein at least one first Quality- of-Service, QoS, flow is mapped onto the data radio bearer;

transmit a first notification (N1 ) to the client device (300) upon determining that a QoS requirement of the first QoS flow cannot be fulfilled, wherein the first notification (N1 ) indicates that the QoS requirement of the first QoS flow cannot be fulfilled.

2. The network access node (100) according to claim 1 , configured to

transmit a second notification (N2) to the client device (300) upon determining that the QoS requirement of the first QoS flow can be fulfilled again, wherein the second notification (N2) indicates that the QoS requirement of the first QoS flow can be fulfilled again.

3. The network access node (100) according to claim 1 or 2, configured to

transmit the first notification (N1 ) and the second notification (N2) in a first service data adaptation protocol, SDAP, header associated with the first QoS flow.

4. The network access node (100) according to claim 3, configured to

transmit the first notification (N1 ) and the second notification (N2) in a common bit of the first SDAP header.

5. The network access node (100) according to claim 4, wherein a first value of the common bit indicates the first notification (N1 ) and a second value of the common bit indicates the second notification (N2).

6. The network access node (100) according to any of claims 3 to 5, wherein the first QoS flow is a guaranteed bit rate QoS flow, and the network access node (100) being configured to transmit the first notification (N1 ) and the second notification (N2) in a bit of the first SDAP header which is dedicated for a reflective QoS indicator of a second SDAP header associated with a second QoS flow mapped onto the data radio bearer, wherein the second QoS flow is non-guaranteed bit rate QoS flow.

7. The network access node (100) according to any of claims 3 to 6, wherein the first SDAP header comprises a first byte and a second byte, wherein the first byte comprises a reflective data radio bearer mapping indicator bit and a reflective QoS indicator bit, and wherein the network access node (100) is configured to

transmit the first notification (N1 ) and the second notification (N2) in a bit of the second byte.

8. The network access node (100) according to claim 7, wherein the first SDAP header indicates an identity of the first QoS flow.

9. A client device (300) for a wireless communication system (500), the client device (300) being configured to

establish a data radio bearer with a network access node (100), wherein at least one first QoS flow is mapped onto the data radio bearer;

receive a first notification (N1 ) from the network access node (100), wherein the first notification (N1 ) indicates that a QoS requirement of the first QoS flow cannot be fulfilled; adapt transmission of the first QoS flow in dependence on the first notification (N1 ).

10. The client device (300) according to claim 9, configured to

receive a second notification (N2) from the network access node (100), wherein the second notification (N2) indicates that the QoS requirement of the first QoS flow can be fulfilled again;

adapt the transmission of the first QoS flow in dependence on the second notification

(N2).

1 1 . The client device (300) according to claim 9 or 10, configured to

receive a first SDAP header associated with the first QoS flow from the network access node (100);

derive the first notification (N1 ) and the second notification (N2) from the first SDAP header.

12. The client device (300) according to any of claim 1 1 , configured to

derive the first notification (N1 ) and the second notification (N2) from a common bit of the first SDAP header.

13. The client device (300) according to claim 12, configured to

derive the first notification (N1 ) from a first value of the common bit and the second notification (N2) from a second value of the common bit.

14. The client device (300) according to any of claims 1 1 to 13, wherein the first QoS flow is a guaranteed bit rate QoS flow, and wherein the client device (300) is configured to

derive the first notification (N1 ) and the second notification (N2) from a bit of the first SDAP header which is dedicated for a reflective QoS indicator of a second SDAP header associated with a second QoS flow mapped onto the data radio bearer, wherein the second QoS flow is non-guaranteed bit rate QoS flow.

15. The client device (300) according to any of claims 1 1 to 14, wherein the first SDAP header comprises a first byte and a second byte, wherein the first byte comprises a reflective data radio bearer mapping indicator bit and a reflective QoS indicator bit, and wherein the client device (300) is configured to

derive the first notification (N1 ) and the second notification (N2) from a bit of the second byte.

16. The client device (300) according to claim 15, wherein the first SDAP header indicates an identity of the QoS flow, and wherein the client device (300) is configured to

determine the identity of the QoS flow based on the indicated identity of the first SDAP header.

17. The client device (300) according to any of claims 9 to 16, wherein adapt the transmission of the first QoS flow comprises

adapt the data rate of the first QoS flow.

18. The client device (300) according to claim 17, wherein adapt the data rate of the first QoS flow comprises at least one of

decrease the data rate in dependence on the first notification (N1 ); and

increase the data rate in dependence on the second notification (N2).

19. The client device (300) according to claim 17 or 18, wherein adapt the transmission of the first QoS flow comprises

adapt the data rate of the first QoS flow in an application layer of the client device (300).

20. A method for a network access node (100), the method (200) comprising

establishing (202) a data radio bearer with a client device (300), wherein at least one first Quality-of-Service, QoS, flow is mapped onto the data radio bearer; transmitting (204) a first notification (N1 ) to the client device (300) upon determining that a QoS requirement of the first QoS flow cannot be fulfilled, wherein the first notification (N1 ) indicates that the QoS requirement of the first QoS flow cannot be fulfilled.

21. A method for a client device (300), the method (400) comprising

establishing (402) a data radio bearer with a network access node (100), wherein at least one first QoS flow is mapped onto the data radio bearer;

receiving (404) a first notification (N1 ) from the network access node (100), wherein the first notification (N1 ) indicates that a QoS requirement of the first QoS flow cannot be fulfilled; adapting (406) transmission of the first QoS flow in dependence on the first notification

(N1 ).

22. A computer program with a program code for performing a method according to claim 20 or 21 when the computer program runs on a computer.