WO2020035132A1

WO2020035132A1 - Network access node and client device for activation or deactivation of control channel configuration parts

Info

Publication number: WO2020035132A1
Application number: PCT/EP2018/072032
Authority: WO
Inventors: Gustaf Claeson; Bengt Lindoff; Wenquan HU; Thorsten Schier
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2018-08-14
Filing date: 2018-08-14
Publication date: 2020-02-20

Abstract

The invention relates to a network access node and a client device for activation or deactivation of control channel configuration parts. The network access node (100) configures a client device (300) with a set of control channel configuration parts associated with a single bandwidth part and determines an activation or a deactivation of a first set of control channel configuration parts among the set of control channel configuration parts. A first configuration message (502) is transmitted to the client device (300), wherein the first configuration message (502) indicates the activation or the deactivation of the first set of control channel configuration parts. Upon reception of the first configuration message (502) the client device (300) activates or deactivates the first set of control channel configuration parts according to the first configuration message (502). Thereby, among other things different types of services with different requirements can be supported. Furthermore, the invention also relates to corresponding methods and a computer program.

Description

NETWORK ACCESS NODE AND CLIENT DEVICE FOR ACTIVATION OR DEACTIVATION OF CONTROL CHANNEL CONFIGURATION PARTS

Technical Field

The invention relates to a network access node and a client device for activation or deactivation of control channel configuration parts. Furthermore, the invention also relates to corresponding methods and a computer program.

Background

In new radio (NR), also known as 5G, a user equipment (UE) performs blind decoding of a predefined set of physical downlink control channel (PDCCH) candidates. The set of PDCCH candidates for the UE to monitor is defined in terms of PDCCH search space sets. A search space set can be a common search space set for a plurality of UEs or a UE-specific search space set for a specific UE. The UE monitors a set of PDCCH candidates in one or more control resource sets (CORESET) on an active downlink (DL) bandwidth part (BWP) on each activated serving cell according to corresponding search space sets. Monitoring in this context implies decoding each PDCCH candidate according to monitored downlink control information (DCI) formats. The PDCCH contains a DCI message which exists in multiple different predefined formats and corresponding bit sizes. The UE executes blind decoding of DCI message bit sizes according to the current active services and transmission modes. There is a defined limitation, in the 3GPP specification, for the number of blind decoding attempts during a defined time period. The reason is to have control over the computational complexity requirement for the UE with regards to the PDCCH blind decoding.

Furthermore, the UE can be configured with multiple number of search space sets, where each search space set includes a CORESET and an aggregation level (AL) with a predefined number of PDCCH candidates. A CORESET consists of

resource blocks in the frequency domain given by a higher-layer parameter CORESET-freq-dom, and w_Symb ^ESET e {1,2,3} symbols in the time domain. The PDCCH candidates have an aggregation level which corresponds to a number of aggregated control channel elements (CCEs), wherein each CCE consists of 6 resource-element groups (REGs). A resource-element group equals one resource block (RB) during one OFDM symbol. Moreover, a requirement of NR is to support ultra reliable and low latency communication (URLLC) services, where latency is expressed in the time required for transmitting a data packet through the network. The requirement, one way over the radio access network (RAN), for URLLC have been set to a latency of 1 ms combined with a packet error rate (PER) of 10e- 5. On the other hand, in long term evolution (LTE) the reliability requirement for the downlink (DL) control channel is 1 % BLER, which is a result from the fact that the block error rate (BLER) of the corresponding DL data is 10%. Hence, the requirements of URLLC services in combination with legacy services, such as enhanced mobile broadband (eMBB) services, will put new challenges to the requirements of the NR control channel.

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

configure a client device with a set of control channel configuration parts associated with a single bandwidth part;

determine an activation or a deactivation of a first set of control channel configuration parts among the set of control channel configuration parts;

transmit a first configuration message to the client device, wherein the first configuration message indicates the activation or the deactivation of the first set of control channel configuration parts.

A control channel configuration part herein can be understood to mean an independent part of a control channel configuration which together can make up the complete control channel configuration for a client device.

The first set of control channel configuration parts can be equal to the set of control channel configuration parts associated with a single bandwidth part. However, the first set of control channel configuration parts can also be a subset of the set of control channel configuration parts, i.e. comprises a fewer number of control channel configuration parts than the set of control channel configuration parts. An advantage of the network access node according to the first aspect is that the support for different service types, such as eMBB and URLLC, can be met by having dynamic activation and deactivation of control channel configuration parts related to such services. Further, the computational complexity of blind decoding of control channel candidates can be reduced since the dynamic activation and deactivation of control channel configuration parts can be adapted to factors having an impact on the need of number of active control channel configuration parts, such as changes in channel quality and in data traffic types associated with different QoS requirements. Also, the present dynamic activation and deactivation mechanism can be efficiently signalled in respect of the number of bits needed which means low overhead in the system.

In an implementation form of a network access node according to the first aspect, the first configuration message further indicates a first time instance for the activation or the deactivation of the first set of control channel configuration parts.

The first time instance can be explicitly indicated in the first configuration message as an absolute time in a suitable time format. In other examples the first time instance can be given in time units of the system, such as slots, subframes, etc.

An advantage with this implementation form is that it allows both dynamic and semi-static reconfiguration of control channel parts. Further, the problem of out of service/ambiguous time period of conventional solutions is eliminated. Also, with explicit indication RRC signalling of mentioned indication is possible.

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

determine an activation or a deactivation of a second set of control channel configuration parts among the set of control channel configuration parts;

transmit a second configuration message to the client device, wherein the second configuration message indicates the activation or the deactivation of the second set of control channel configuration parts.

The second set of control channel configuration parts can be equal to the set of control channel configuration parts associated with a single bandwidth part. However, the second set of control channel configuration parts can be a subset of the set of control channel configuration parts, i.e. comprises a fewer number of control channel configuration parts than the set of control channel configuration parts.

An advantage with this implementation form is that an updating mechanism is provided. Hence, the active channel configuration parts for a client device can be dynamically adapted to different factors, such as changes in channel quality and in data traffic types associated with different QoS requirements.

In an implementation form of a network access node according to the first aspect, the second configuration message further indicates a second time instance for deactivation of the first set of control channel configuration parts and activation of the second set of control channel configuration parts.

The first set of control channel configuration parts and the second set of control channel configuration parts are different sets of control channel configuration parts and can partially overlap.

An advantage with this implementation form is that the reconfiguration of the number of control channel configuration parts can be held small since many control channel configuration parts can be used in both the first set of control channel configuration parts and the second set of control channel configuration parts.

determine the activation or the deactivation of at least one of the first set of control channel configuration parts and the second set of control channel configuration parts in dependence on an event detected by the network access node or indicated in an event message from the client device.

An advantage with this implementation form is that the determination of the activation or the deactivation is in dependence on a triggering event which will have an impact on the activation or deactivation of the control channel configuration parts.

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

a downlink radio channel signal quality passing a threshold value,

a change in a position of the client device, a change in Doppler frequency at the client device,

a number of blind decoding downlink control channel candidates exceeding a predefined maximum number, and

a change in the number of client devices connected to the network access node, wherein each client device is configured with services requiring low latency and high reliability services.

An advantage with this implementation form is that any of the above events will provide relevant information for determining the activation or deactivation of control channel configuration parts thereby improving the determination of the activation or deactivation of control channel configuration parts for the client device.

In an implementation form of a network access node according to the first aspect, the set of control channel configuration parts comprises at least one of:

a search space set,

a search space, and

a control resource set.

In an implementation form of a network access node according to the first aspect, at least one of the first configuration message and the second configuration message is any of:

a downlink radio resource control, RRC, message,

a downlink control information, DCI, and

a downlink medium access control, MAC, control element.

An advantage with this implementation form is that convenient methods for signalling the first and second configuration messages is provided.

receive an acknowledge message from the client device in response to the transmission of at least one of the first configuration message and the second configuration message, wherein the acknowledge message indicates safe reception of any of the first configuration message and the second configuration message.

With this implementation form a handshaking mechanism is provided with respect to the activation or deactivation of the control channel configuration parts. The network access node can receive the acknowledge message in any of an uplink radio resource control message, an uplink control information and an uplink MAC control element.

In an implementation form of a network access node according to the first aspect, at least one of the first time instance and the second time instance is derivable from any of

a time instance for the transmission of the first control message,

a time instance for the transmission of the second control message,

a time instance for the reception of the acknowledge message, and

a time instance for the reception of the event message.

This implies that the first time instance and the second time instance can be determined in dependence on any of the above mentioned time instances. Thereby, the first time instance and the second time instance do not have to be explicitly signalled to the client device which means reduced overhead in the system.

An advantage with this implementation form is that no explicit time instance has to be transmitted. Instead the client device can derive any of the first time instance and the second time instance implicitly. This means e.g. reduced control signalling.

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 by a network access node with a set of control channel configuration parts associated with a single bandwidth part, and further configured to

receive a first configuration message from the network access node, wherein the first configuration message indicates an activation or a deactivation of a first set of control channel configuration parts among the set of control channel configuration parts;

activate or deactivate the first set of control channel configuration parts according to the first configuration message.

In one non-limiting example, the client device is configured to monitor a set of downlink control channel candidates based on activated control channel configuration parts. The monitoring implies blind decoding of each downlink control channel candidate.

The active control channel configuration parts at a certain time instance can be the sum of all control channel configuration parts that have been activated by previous control messages and have not been deactivated since their activation. An advantage of the client device according to the second aspect is that the support for different service types, such as eMBB and URLLC, can be met by having dynamic activation and deactivation of control channel configuration parts related to such services. Further, the computational complexity of blind decoding of control channel candidates can be reduced since the dynamic activation and deactivation of control channel configuration parts can be adapted to factors having an impact on the need of number of active control channel configuration parts, such as changes in channel quality and in data traffic types associated with different QoS requirements. Also, the present dynamic activation and deactivation mechanism can be efficiently signalled in respect of the number of bits needed which means low overhead in the system.

In an implementation form of a client device according to the second aspect, wherein the first configuration message further indicates a first time instance for the activation or the deactivation of the first set of control channel configuration parts, and configured to

activate or deactivate the first set of control channel configuration parts at the first time instance.

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

receive a second configuration message from the network access node, wherein the second configuration message indicates an activation or a deactivation of a second set of control channel configuration parts among the set of control channel configuration parts; activate or deactivate the second set of control channel configuration parts according to the second configuration message.

In an implementation form of a client device according to the second aspect, the second configuration message further indicates a second time instance for deactivation of the first set of control channel configuration parts and activation of the second set of control channel configuration parts, and configured to

deactivate the first set of control channel configuration parts and activate the second set of control channel configuration parts at the second time instance.

detect an event associated with at least one of the first set of control channel configuration parts and the second set of control channel configuration parts;

transmit an event message to the network access node, wherein the event message indicates the detected event.

An advantage with this implementation form is that the determination of the activation or the deactivation at the network access node can be made in dependence on a triggering event which will have an impact on the activation or deactivation of the control channel configuration parts.

In an implementation form of a client device according to the second aspect, wherein the event is any of

a downlink radio channel signal quality passing a threshold value,

a change in a position of the client device,

a change in Doppler frequency at the client device, and

a number of blind decoding downlink control channel candidates exceeding a predefined maximum number.

An advantage with this implementation form is that any of the above events will provide relevant information for the network access node to determine the activation or deactivation of control channel configuration parts thereby improving the determination of the activation or deactivation of control channel configuration parts for the client device.

In an implementation form of a client device according to the second aspect, the set of control channel configuration parts comprises at least one of:

a search space set,

a search space, and

a control resource set.

In an implementation form of a client device according to the second aspect, at least one of the first configuration message and the second configuration message is any of:

a downlink radio resource control, RRC, message,

a downlink control information, DCI, and

a downlink medium access control, MAC, control element.

transmit an acknowledge message to the network access node in response to the reception of at least one of the first configuration message and the second configuration message, wherein the acknowledge message indicates safe reception of any of the first configuration message and the second configuration message.

The acknowledge message can be transmitted in any of an uplink radio resource control message, an uplink control information, and an uplink MAC control element.

An advantage with this implementation form is that convenient methods for signalling the acknowledge message is provided.

In an implementation form of a client device according to the second aspect, at least one of the first time instance and the second instance is derivable from any of

a time instance for the transmission of the first control message,

a time instance for the transmission of the second control message,

a time instance for the reception of the acknowledge message, and

a time instance for the reception of the event message. An advantage with this implementation form is that no explicit time instance has to be transmitted. Instead the client device can derive any of the first time instance and the second time instance implicitly. This means e.g. reduced control signalling in the system.

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

configuring a client device with a set of control channel configuration parts associated with a single bandwidth part;

determining an activation or a deactivation of a first set of control channel configuration parts among the set of control channel configuration parts;

transmitting a first configuration message to the client device, wherein the first configuration message indicates the activation or the deactivation of the first set of control channel configuration parts.

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 being configured by a network access node with a set of control channel configuration parts associated with a single bandwidth part, the method comprising

receiving a first configuration message from the network access node, wherein the first configuration message indicates an activation or a deactivation of a first set of control channel configuration parts among the set of control channel configuration parts;

activating or deactivating the first set of control channel configuration parts according to the first configuration message.

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/example 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;

- Figs. 6a-c illustrates activation and deactivation of control channel configuration parts according to embodiments of the invention; and

- Fig. 7 shows a signalling diagram according to an embodiment of the invention.

Detailed Description

To meet the requirement of new services, such as URLLC services, different solutions have been proposed to improve the reliability of the control channel for NR. However, the inventors have concluded that such proposed solutions may not meet the requirements in NR. Therefore, the inventors have been working on general improvements in respect of the control channel in a wireless communication system. Especially, in NR it has been recognized by the inventors that there is a need for URLLC services to have a new range of reliability and alternatives of PDCCH candidates compared to legacy enhanced mobile broadband (eMBB) services. This insight has implications on the control channel configuration parts used for the PDCCH candidates.

Furthermore, it has been concluded by the inventors that there is a general need to change the control channel configuration depending on e.g. the channel conditions of the UE. Configure all options for different search space sets in parallel is not a good option since it will increase blind decoding in the UE which increases computational complexity. Currently there is a restriction in the NR standard of how many candidates a UE is required to blind decode in order to limit the UE decoding complexity. Also, it has been identified by the inventors that in NR the L3 reconfiguration does not include an exact activation time, instead the L3 reconfiguration includes a maximum allowed time for the reconfiguration. The UE may change its configuration within the maximum time but the next generation NodeB (gNB) cannot assume that the UE listens to the new configuration prior to the allowed time for reconfiguration. This causes a time period of ambiguity during the specified max reconfiguration time period in which the gNB does not know which control channels the UE is actually decoding. This is especially problematic for services with very low latency, such as URLLC, since this will cause the URLLC users to be“out-of-service” during the reconfiguration period.

In NR the PDCCH configuration is part of the radio resource control (RRC) IE PDCCH-Config which in turn is part of the bandwidth part (BWP) dedicated configuration. The PDCCH configuration includes for example CORSET configurations and search space set configurations. With a RRC reconfiguration message a search space set could either be added, modified or released. Any configured search space set is per default activated and hence all configured search space sets sums up to the total number of blind decoding attempts.

The current PDCCH candidate selection in NR is based on algorithm functions defined in the standard specifications together with input control parameters, control semi-statically RRC signalling to add/modify/remove PDCCH configuration. The PDCCH candidates are semi- statically defined and should fit into all services types, such as eMBB and URLLC, and the varying channel conditions. A basic problem of this is that the current structure for PDCCH selection was created for eMBB and is not suitable for URLLC since URLLC requires another range of PDCCH candidates with higher reliability. Already today there are issues with current solution for PDCCH decoding, computational complexity is at a limit and different potential workarounds are discussed, such as PDCCH dropping. With PDCCH dropping it is meant that some candidates are dropped, hence no blind decoding is performed for that PDCCH candidate. The basic issue when adding another service with such a difference in reliability range is that it cannot come for free in terms of number of blind decoding attempts, hence increased computational complexity in the UE will be the result.

For the above reasons the inventors therefore propose a network access node and a client device for activation or deactivation of control channel configuration parts for the client device. Thereby, an activation and deactivation mechanism for a wireless communication system is provided which mitigates and/or solves the drawbacks of conventional solutions, such as the previously mentioned time period of ambiguity. Further, with the addition of new service types, such as URLLC, the need for additional control channel alternatives is identified by the inventors since else blind decoding complexity will be increased. Also, this problem is solved by embodiments of the invention.

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 should 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 configure a client device 300 with a set of control channel configuration parts associated with a single bandwidth part. The client device 300 can be configured with the set of control channel configuration parts using standardized control signalling and pre-defined procedures. For example, in NR the client device 300 is configured by means of broadcast system information and dedicated RRC signalling, e.g. in a connection set up procedure with the network. The network access node 100 thereafter determines an activation or a deactivation of a first set of control channel configuration parts among the set of control channel configuration parts. Finally, the network access node 100 transmits a first configuration message to the client device 300. The first configuration message 502 indicates the activation or the deactivation of the first set of control channel configuration parts. 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 configuring 202 a client device 300 with a set of control channel configuration parts associated with a single bandwidth part. The method 200 comprises determining 204 an activation or a deactivation of a first set of control channel configuration parts among the set of control channel configuration parts. The method 200 comprises transmitting 206 a first configuration message 502 to the client device 300. The first configuration message 502 indicates the activation or the deactivation of the first set of control channel configuration parts.

The network access node 100 interworks with a client device and hence 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 should 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 being configured by a network access node 100 with a set of control channel configuration parts associated with a single bandwidth part. This configuration can as previously described be performed according pre-defined procedure, e.g. at a connection set procedure in NR.

After having been configured with a set of control channel configuration parts, the client device 300 is further configured to receive a first configuration message 502 from the network access node 100. The first configuration message 502 indicates an activation or a deactivation of a first set of control channel configuration parts among the set of control channel configuration parts. After reception of the first configuration message 502 the client device 300 activates or deactivates the first set of control channel configuration parts according to the first configuration message 502.

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. As previously mentioned the client device 300 is configured by the network access node 100 with a set of control channel configuration parts associated with a single bandwidth part. The method 400 comprises receiving 402 a first configuration message 502 from the network access node 100. The first configuration message 502 indicates an activation or a deactivation of a first set of control channel configuration parts among the set of control channel configuration parts. The method 400 comprises activating or deactivating 404 the first set of control channel configuration parts according to the first configuration message 502.

Fig. 5 illustrates the interworking between a network access node 100 and a client device 300 in a wireless communication system 500 according to an embodiment of the invention. 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. As shown in Fig. 5 beam forming may be employed in the wireless communication system 500 which implies that the client device 300 is served by the network access node 100 in one or more serving beams or beam pair links.

In the wireless communication system 500 as shown in Fig. 5, a first control message 502 indicating an activation or a deactivation of a first set of control channel configuration parts according to the invention is transmitted from the network access node 100 to the client device 300. According to the invention the client device 300 upon reception of the first control message 502 activates or deactivates the first set of control channel configuration parts based on the first control message 502. The client device 300 can use the activated control channel configuration parts for blind decoding of control channel candidates, which will be explained in more detailed in the following disclosure.

In embodiments of the invention the set of control channel configuration parts comprises at least one of: a search space set, a search space, and a control resource set (CORESET). Hence the set of control channel configuration parts can be a combination of search space(s) (set) and CORSET(s). It is to be noted that in current NR 3GPP specification there is a mismatch between L1 and L3 specifications with regards to the definition of search space. In the L1 specification both the terms search space and search space set are used, and in the L3 specification only the term search space (without the word“set”) is used but with the meaning of a search space set. In this disclosure both search space and search space set are considered to have the same meaning. Figs. 6a-6c illustrate non-limiting examples of different control channel parts which can be activated and deactivated according to embodiments of the invention. The control channel parts can be dynamically or semi-statically configured, and independently and dynamically controlled by the network access node 100. The search space sets and the CORESETs are indexed from 1 to N and from 1 to M, respectively, in Figs. 6a-6c. As shown in Fig. 6a each search space set (SSS) and CORESET can be activated or deactivated by the network access node 100. In Fig. 6b SSS 1 and CORESET M are activated. In Fig, 6c SSS N and CORESET 1 have also been activated and hence SSS 1 , SSS N, CORESET 1 and CORESET M are activated in Fig. 6c.

In principle the CORESET does not need explicit control for activation and deactivation since one CORESET identity is referenced from a search space set. One CORESET may be included in multiple search space sets. If no active search space set points to a specific CORESET that CORESET is in practice deactivated.

Fig. 7 shows a signalling diagram for dynamic activation or deactivation of control channel configuration parts in a wireless communication system 500 according to embodiments of the invention. In Fig. 7 a network access node 100 interworks with a client device 300 and it is assumed that initially the client device 300 previous to step I has been configured with a plurality of control channel configuration parts for a single BWP. The different control channel configuration parts may cover different range of reliability, e.g. one range for eMBB services and another range for URLLC services. In this example it is further assumed that the control channel configuration parts are associated with a single bandwidth part. However, the solution presented herein can be applied to each single BWP allocated for a client device 300.

At step I in Fig. 7, the network access node 100 determines the activation or deactivation of a first set of control channel configuration parts. The first set of control channel configuration parts belongs to the set of control channel configuration parts and can be equal to or a subset of the set of control channel configuration parts. The network access node 100 generates a first control message 502 indicating the determined activation or deactivation of the first set of control channel configuration parts. The first control message 502 is thereafter transmitted from the network access node 100 to the client device 300 as shown in Fig. 7. For example, if the first set of control channel configuration parts is a subset of the set of control channel configuration parts one or more search space sets and one or more CORESETs can be determined to be activated or deactivated.

In an embodiment of the invention the first configuration message 502 further indicates a first time instance T1 for the activation or the deactivation of the first set of control channel configuration parts as also illustrated in Fig. 7. The first time instance T1 hence gives the explicit time instance at which the activation or the deactivation of the first set of control channel configuration parts is valid. Thereby, an explicit time indication is given so as to solve the ambiguity problem of conventional solutions as described previously.

At step II in Fig. 7, the client device 300 transmits an acknowledgement message 508 for safe reception of the first control message 502 to the network access node 100, i.e. a hand shaking procedure is provided herein so at to improve the robustness of the present solution.

At step III in Fig. 7, the network access node 100 uses the active control channel parts of the first set of control channel configuration parts for scheduling and transmitting first control channel candidates CCH CANDI s as shown in Fig. 7. For example, in NR the control channel candidates would correspond to PDCCH candidates.

At step IV in Fig. 7, the client device 300 performs blind decoding of the received first control channel candidates CCH CANDs in the active control channel configuration parts according to the first control message 502.

At step V in Fig. 7, the network access node 100 monitors for detecting an event connected the choice of applicable reliability of control channel configuration parts. The event may be internal to the network access node 100 or reported by the client device 300 in suitable signalling.

In the former case the event detected by the network access node can be a change in the number of client devices connected to the network access node 100 since this may require the network access node 100 to rearrange the control channel resources for the client devices served by the network access node 100 so as to adapt to the change in the number of served client devices.

In the latter case the client device 300 continuously monitors after trigger events and performs blind decoding of candidates of the active control channel configuration parts. If such an event is detected the client device 300 reports the event to the network access node 100 in an event message 508 as illustrated at VI in Fig. 7.

The event detected by the client device 300 can in an embodiment of the invention be any of the non-limiting events: a downlink radio channel signal quality passing a threshold value, a change in a position of the client device 300, a change in Doppler frequency at the client device 300, and a number of blind decoding downlink control channel candidates exceeding a predefined maximum number.

The client device 300 can monitor the radio channel signal quality by continuously measuring DL reference signals (e.g. PDCCH or DMRS for the PDCCH) transmitted by the network access node 100. Upon the radio channel signal quality passing a threshold value the client device 300 transmit an event message 508 to the network access node 100 e.g. in the form of a SNIR arrow. The threshold value can e.g. be pre-defined in a standard.

The change in position of the client device 300 and the change in Doppler frequency at the client device 300 can be measured and determined by the client device 300. Also, in these cases threshold values can be used for deciding if an event message 508 is to be sent to the network access node 100, e.g. a position threshold value and a Doppler frequency threshold value. Regarding the number of blind decoding of downlink control channel candidates, the client device can count the number of blind decoding attempts and transmit an event message 508 to the network access node 100 when the number of blind decoding attempts has reached a critical value.

Further, the network access node 100 can optionally transmit an acknowledgement message to the client device 300 in response to the reception of the event message 508 from the client device 300. This type of acknowledgement message is however not shown in Fig. 7.

At step VII in Fig. 7, the network access node 100 detects the event, internally or through signalling form the client device 300, which triggers a dynamic update of the control channel configuration parts for the client device 300 which is performed at step VIII in Fig. 7.

Therefore, at step VIII in Fig. 7, the network access node 100 determines activation or deactivation of a second set of control channel configuration parts. Thereafter, the network access node 100 generates a second control message 504 indicating the activation or deactivation of the second set of control channel configuration parts. The network access node 100 transmit the second control message 504 to the client device 300 to reconfigure the client device 300 with a new set of control channel configuration parts. Hence, the second control message 504 can be seen as a reconfiguration message so as to reconfigure the active control channel configuration parts to be used for transmission of control channel candidates. This process of reconfiguration continuous so that the network access node 100 continuous to reconfigure the client device 300 if needed as long as the client device 300 is served by the network access node 100.

In an embodiment of the invention, the second configuration message 504 further indicates a second time instance T2 for deactivation of the first set of control channel configuration parts and activation of the second set of control channel configuration parts. Hence, the activation and deactivation procedure due to the second configuration message 504 include a method to allow a synchronized explicit reconfiguration point, referred herein as second time instance T2. The client device 300 can therefore use a previous control channel configuration from an explicit first time instance T1 up until the second time instance T2, and starting from and including the reconfiguration slot, the client device 300 uses a new control channel configuration at the second time instance T2.

Regarding the signalling of the control channel configuration parts to the client device 300 different signalling schemes, protocols and formats can be employed by the network access node 100 in this respect. For example, the first configuration message 502 and the second configuration message 504 can be any of: a downlink RRC message, a downlink control information (DCI) in PDCCH, and a downlink MAC CE. Therefore, different signalling methods can be used for transmission of the first configuration message 502 and the second configuration message 504. For example, with RRC message the control channel configuration parts are semi-statically reconfigured. On the other hand, by using MAC CE or physical layer control information fast reconfiguration of the control channel configuration parts is possible and can be fully dynamic.

At step IX in Fig. 7, the client device 300 receives the second control message 504. The client device 300 transmits an acknowledgement message 506 for safe reception of the second control message 504 to the network access node 100. The acknowledgement message 506 can in embodiments be received by the network access node 100 in any of an uplink RRC message, an uplink control information (UCI), and an uplink MAC CE.

At step X in Fig. 7, the network access node 100 schedules second control channel candidates CCH CAND2s using the new control channel configuration, i.e. the control channel candidates are transmitted in the active control channel configuration parts after adaptation to the content of the second control message 504.

At step XI in Fig. 7, the client device 300 performs blind decoding of control channel candidates according to the activated control channel configuration parts of the second set of control channel configuration parts after adaptation to the content of the second control message 504. According to embodiments of the invention the first time instance T1 and/or the second instance T2 is derivable from previous time instances related to the transmission of different message types mentioned previously. Hence, the first time instance T1 and/or the second instance T2 is derivable from any of a time instance for the transmission of the first control message 502, a time instance for the transmission of the second control message 504, a time instance for the reception of the acknowledge message 506, and a time instance for the reception of the event message 508. This is an alternative to explicit signalling of the first T1 and second T2 time instances. Since the client device 300 can derive mentioned first T1 and second T2 time instances implicitly from one or any combination of the above stated time instances no control signalling is needed in this respect and hence the overhead in the system can be reduced.

An example of such a determination in NR is a combination of the above mentioned time instance and a preconfigured offset value. The following non-limiting formulas can be used for deriving the first T 1 and/or the second T2 time instances:

• T1/T2 = time instance for the transmission of the first control message 502 + offset value;

• T1/T2 = time instance for the transmission of the second control message 504 + offset value;

• T1/T2 = time instance for the reception of the acknowledge message 506 + offset value;

• T1 /T2 = time instance for the reception of the event message 508 + offset value. However, also other combinations of the above time instances can be used for deriving the T 1 or the second T2 time instances.

Further, the time instances for any of messages 502, 504, 506, and 508 can be given in absolut time, in slots, in subframes or in any other time unit used in the wireless communication system 500. The offset value may in embodiments be in the order of milliseconds and can be dependent on capabilities of the client device 300 or given by a pre-defined rule in a standard. Also, the offset value can be given in absolut time, in slots or in subframes. Usually, the offset value is given in the same time unit as the time instances for any of messages 502, 504, 506, and 508.

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 client device may also be understood as a chip or integrated circuit included in the above devices.

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

configure a client device (300) with a set of control channel configuration parts associated with a single bandwidth part;

transmit a first configuration message (502) to the client device (300), wherein the first configuration message (502) indicates the activation or the deactivation of the first set of control channel configuration parts.

2. The network access node (100) according to claim 1 , wherein the first configuration message (502) further indicates a first time instance (T1 ) for the activation or the deactivation of the first set of control channel configuration parts.

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

transmit a second configuration message (504) to the client device (300), wherein the second configuration message (504) indicates the activation or the deactivation of the second set of control channel configuration parts.

4. The network access node (100) according to claim 3, wherein the second configuration message (504) further indicates a second time instance (T2) for deactivation of the first set of control channel configuration parts and activation of the second set of control channel configuration parts.

5. The network access node (100) according to any of the preceding claims, configured to determine the activation or the deactivation of at least one of the first set of control channel configuration parts and the second set of control channel configuration parts in dependence on an event detected by the network access node (100) or indicated in an event message (508) from the client device (300).

6. The network access node (100) according to claim 5, wherein the event is any of

a downlink radio channel signal quality passing a threshold value,

a change in a position of the client device (300), a change in Doppler frequency at the client device (300),

a change in the number of client devices connected to the network access node (100), wherein each client device is configured with services requiring low latency and high reliability services.

7. The network access node (100) according to any of the preceding claims, wherein the set of control channel configuration parts comprises at least one of:

a search space set,

a search space, and

a control resource set.

8. The network access node (100) according to any of the preceding claims, wherein at least one of the first configuration message (502) and the second configuration message (504) is any of:

a downlink radio resource control, RRC, message,

a downlink control information, DCI, and

a downlink medium access control, MAC, control element.

9. The network access node (100) according to any of the preceding claims, configured to receive an acknowledge message (506) from the client device (300) in response to the transmission of at least one of the first configuration message (502) and the second configuration message (504), wherein the acknowledge message (506) indicates safe reception of any of the first configuration message (502) and the second configuration message (504).

10. The network access node (100) according to any of claims 2 to 9, wherein at least one of the first time instance (T1 ) and the second time instance (T2) is derivable from any of

a time instance for the transmission of the first control message (502),

a time instance for the transmission of the second control message (504),

a time instance for the reception of the acknowledge message (506), and

a time instance for the reception of the event message (508).

1 1. A client device (300) for a wireless communication system (500), the client device (300) being configured by a network access node (100) with a set of control channel configuration parts associated with a single bandwidth part, and further configured to receive a first configuration message (502) from the network access node (100), wherein the first configuration message (502) indicates an activation or a deactivation of a first set of control channel configuration parts among the set of control channel configuration parts; activate or deactivate the first set of control channel configuration parts according to the first configuration message (502).

12. The client device (300) according to claim 1 1 , wherein the first configuration message (502) further indicates a first time instance (T 1 ) for the activation or the deactivation of the first set of control channel configuration parts, and configured to

activate or deactivate the first set of control channel configuration parts at the first time instance (T1 ).

13. The client device (300) according to claim 1 1 or 12, configured to

receive a second configuration message (504) from the network access node (100), wherein the second configuration message (504) indicates an activation or a deactivation of a second set of control channel configuration parts among the set of control channel configuration parts;

activate or deactivate the second set of control channel configuration parts according to the second configuration message (504).

14. The client device (300) according to claim 13, wherein the second configuration message (504) further indicates a second time instance (T2) for deactivation of the first set of control channel configuration parts and activation of the second set of control channel configuration parts, and configured to

deactivate the first set of control channel configuration parts and activate the second set of control channel configuration parts at the second time instance (T2).

15. The client device (300) according to any of claims 1 1 to 14, configured to

transmit an event message (508) to the network access node (100), wherein the event message (508) indicates the detected event.

16. The client device (300) according to claim 15, wherein the event is any of

a downlink radio channel signal quality passing a threshold value,

a change in a position of the client device (300),

a change in Doppler frequency at the client device (300), and a number of blind decoding downlink control channel candidates exceeding a predefined maximum number.

17. The client device (300) according to any of claims 1 1 to 16, wherein the set of control channel configuration parts comprises at least one of:

a search space set,

a search space, and

a control resource set.

18. The client device (300) according to any of claims 1 1 to 17, wherein at least one of the first configuration message (502) and the second configuration message (504) is any of:

a downlink radio resource control, RRC, message,

a downlink control information, DCI, and

a downlink medium access control, MAC, control element.

19. The client device (300) according to any of claims 1 1 to 18, configured to

transmit an acknowledge message (506) to the network access node (100) in response to the reception of at least one of the first configuration message (502) and the second configuration message (504), wherein the acknowledge message (506) indicates safe reception of any of the first configuration message (502) and the second configuration message (504).

20. The client device (300) according to any of claims 12 to 19, wherein at least one of the first time instance (T1 ) and the second instance (T2) is derivable from any of

a time instance for the transmission of the first control message (502),

a time instance for the transmission of the second control message (504),

a time instance for the reception of the acknowledge message (506), and

a time instance for the reception of the event message (508).

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

configuring (202) a client device (300) with a set of control channel configuration parts associated with a single bandwidth part;

determining (204) an activation or a deactivation of a first set of control channel configuration parts among the set of control channel configuration parts;

transmitting (206) a first configuration message (502) to the client device (300), wherein the first configuration message (502) indicates the activation or the deactivation of the first set of control channel configuration parts.

22. A method (400) for a client device (300) being configured by a network access node (100) with a set of control channel configuration parts associated with a single bandwidth part, the method (400) comprising

receiving (402) a first configuration message (502) from the network access node (100), wherein the first configuration message (502) indicates an activation or a deactivation of a first set of control channel configuration parts among the set of control channel configuration parts; activating or deactivating (404) the first set of control channel configuration parts according to the first configuration message (502).

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