WO2025233839A1

WO2025233839A1 - Apparatus, method and computer program for logical channel selection

Info

Publication number: WO2025233839A1
Application number: PCT/IB2025/054751
Authority: WO
Inventors: Sunyoung Lee; Ling Yu; Vinh Van Phan
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2024-05-07
Filing date: 2025-05-06
Publication date: 2025-11-13
Anticipated expiration: 2026-11-07
Also published as: GB2640860A; GB202406326D0

Abstract

There is provided an apparatus comprising means for configuring a plurality of logical channels, wherein each logical channel is associated with a priority level, triggering transmission of a media access control element, MAC CE, from the apparatus to a user equipment, selecting a priority level of a logical channel from the plurality of logical channels allowed to be transmitted on a carrier, determining at least one channel busy ratio, CBR, condition for transmission of a MAC CE on the carrier based on a CBR condition associated with the selected priority, determining, based on the determined at least one CBR condition, that the MAC CE can be transmitted on the carrier and providing the MAC CE from the apparatus to the user equipment on the carrier, based on the determining that the MAC CE can be transmitted on the carrier.

Description

APPARATUS, METHOD AND COMPUTER PROGRAM FOR LOGICAL CHANNEL SELECTION

Field

The present application relates to a method, apparatus, system and computer program and in particular but not exclusively to a channel busy ratio (CBR) condition for carrier selection of media access control control elements (MAC CEs).

Background

A communication system can be seen as a facility that enables communication sessions between two or more communication devices, or provides communication devices access to a network. A mobile or wireless communication network is one example of a communication network. A communication device may be provided with a service by an application server.

Such communication networks operate in according with standards such as those provided by 3GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). Examples of standards are the so-called 4G (4th Generation), 5G (5th Generation) standards provided by 3GPP.

Summary

In a first aspect there is provided an apparatus comprising means for configuring a plurality of logical channels, wherein each logical channel is associated with a priority level, triggering transmission of a media access control element, MAC CE, from the apparatus to a user equipment, selecting a priority level of a logical channel from the plurality of logical channels allowed to be transmitted on a carrier, determining at least one channel busy ratio, CBR, condition for transmission of a MAC CE on the carrier based on a CBR condition associated with the selected priority, determining, based on the determined at least one CBR condition, that the MAC CE can be transmitted on the carrier and providing the MAC CE from the apparatus to the user equipment on the carrier, based on the determining that the MAC CE can be transmitted on the carrier. The apparatus may comprise means for receiving an indication of the priority level from the network and wherein selecting the priority level is based on the indication of the priority level.

The apparatus may comprise means for selecting a highest priority level or a lowest priority level.

The apparatus may comprise means for determining to select the highest priority or the lowest priority based on at least one of the following: time remaining on a reporting timer, a number of carriers for which failure is detected, a type of carrier aggregation operation or a quality of service requirement for data on the carrier.

Determining at least one CBR condition may comprise determining a CBR condition associated with a logical channel having the selected priority level.

The MAC CE may comprise a channel state information reporting MAC CE.

Triggering transmission of the MAC CE from the apparatus to the user equipment may comprise receiving a request at the apparatus for channel state reporting of the carrier.

The apparatus and the user equipment may communicate using sidelink.

In a second aspect there is provided a method comprising, at an apparatus, configuring a plurality of logical channels, wherein each logical channel is associated with a priority level, triggering transmission of a media access control element, MAC CE, from the apparatus to a user equipment, selecting a priority level of a logical channel from the plurality of logical channels allowed to be transmitted on a carrier, determining at least one channel busy ratio, CBR, condition for transmission of a MAC CE on the carrier based on a CBR condition associated with the selected priority, determining, based on the determined at least one CBR condition, that the MAC CE can be transmitted on the carrier and providing the MAC CE from the apparatus to the user equipment on the carrier, based on the determining that the MAC CE can be transmitted on the carrier. The method may comprise receiving an indication of the priority level from the network and wherein selecting the priority level is based on the indication of the priority level.

The method may comprise selecting a highest priority level or a lowest priority level.

The method may comprise determining to select the highest priority or the lowest priority based on at least one of the following: time remaining on a reporting timer, a number of carriers for which failure is detected, a type of carrier aggregation operation or a quality of service requirement for data on the carrier.

The MAC CE may comprise a channel state information reporting MAC CE.

The apparatus and the user equipment may communicate using sidelink.

In a third aspect there is provided an apparatus comprising at least one processor, and at least one memory storing instructions which, when executed by the processor, cause the apparatus at least to perform the method according to the second aspect.

In a fourth aspect there is provided a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the method according to the second aspect.

In a fifth aspect there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method according to the second aspect. In the above, many different embodiments have been described. It should be appreciated that further embodiments may be provided by the combination of any two or more of the embodiments described above.

Description of Figures

Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which:

Figure 1 shows a schematic diagram of an example 5GS communication system;

Figure 2 shows a schematic diagram of an example mobile communication device;

Figure 3 shows a schematic diagram of an example control apparatus;

Figure 4 shows a schematic diagram of a MAC CE;

Figure 5 shows a flowchart of a method according to an example embodiment;

Figure 6 shows a flowchart of a method according to an example embodiment;

Figure 7 shows a flowchart of a method according to an example embodiment;

Figure 8 shows a flowchart of a method according to an example embodiment.

Detailed description

Before explaining in detail the examples, certain general principles of a wireless communication system and mobile communication devices are briefly explained with reference to Figure 1, Figure 2 and Figure 3 to assist in understanding the technology underlying the described examples.

An example of a suitable communications system is the 5G or NR concept. Network architecture in NR may be similar to that of ETE- advanced. Base stations of NR systems may be known as next generation NodeBs (gNBs). Changes to the network architecture may depend on the need to support various radio technologies and finer Quality of Service (QoS) support, and some on-demand requirements for e.g. QoS levels to support Quality of Experience (QoE) for a user. Also network aware services and applications, and service and application aware networks may bring changes to the architecture. Those are related to Information Centric Network (ICN) and User-Centric Content Delivery Network (UC-CDN) approaches. NR may use Multiple Input - Multiple Output (MIMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates.

Future networks may utilise network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into “building blocks” or entities that may be operationally connected or linked together to provide services. A virtualized network function (VNF) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Deployments may be cloud-native network function (CNF) based, where network functions comprise one or more pods. Cloud computing or data storage may also be utilized. In radio communications this may mean node operations are to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of ETE or may even be non-existent.

Figure 1 shows a schematic representation of a 5G system (5GS) 100. The 5GS may comprise a user equipment (UE) 102 (which may also be referred to as a communication device or a terminal), a 5G radio access network (5GRAN) 104, a 5G core network (5GCN) 106, one or more internal or external application functions (AF) 108 and one or more data networks (DN) 110.

An example 5G core network (CN) comprises functional entities. The 5GCN 106 may comprise one or more Access and mobility Management Functions (AMF) 112, one or more session management functions (SMF) 114, an authentication server function (AUSF) 116, a Unified Data Management (UDM) 118, one or more user plane functions (UPF) 120, a Unified Data Repository (UDR) 122 and/or a Network Exposure Function (NEF) 124. The UPF is controlled by the SMF (Session Management Function) that receives policies from a PCF (Policy Control Function). The 5GCN may comprise a Eocation Management Function (LMF) 126. The LMF is responsible for receiving measurements and assistance information from a mobile device or NG-RAN and computing the position of a UE.

The CN may be connected to a UE via the Radio Access Network (RAN) or through fixed access via a non-3GPP Interworking Function (N3IWF). The 5GRAN may comprise one or more gNodeB (gNB) Distributed Unit (DU) functions connected to one or more gNodeB (gNB) Centralized Unit (CU) functions. The RAN may comprise one or more access nodes.

A User Plane Function (UPF) referred to as PDU Session Anchor (PSA) may be responsible for forwarding frames back and forth between the DN and the tunnels established over the 5G towards the UE(s) exchanging traffic with the DN.

A possible mobile communication device will now be described in more detail with reference to Figure 2 showing a schematic, partially sectioned view of a communication device 200. Such a communication device is often referred to as user equipment (UE) or terminal. An appropriate mobile communication device may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a mobile station (MS) or mobile device such as a mobile phone or what is known as a ’smart phone’, a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), personal data assistant (PDA) or a tablet provided with wireless communication capabilities, voice over IP (VoIP) phones, portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart devices, wireless customer-premises equipment (CPE), an Internet of Things (loT) device, an industrial loT device, tag device or any combinations of these or the like. A mobile communication device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services comprise two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet. Users may also be provided broadcast or multicast data. Non-limiting examples of the content comprise downloads, television and radio programs, videos, advertisements, various alerts, and other information.

A mobile device is typically provided with at least one data processing entity 201, at least one memory 202 and other possible components 203 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The data processing, storage and other relevant components can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 204. The user may control the operation of the mobile device by means of a suitable user interface such as key pad 205, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 208, a speaker and a microphone can be also provided. Furthermore, a mobile communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto.

The mobile device 200 may receive signals over an air or radio interface 207 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 2 transceiver apparatus is designated schematically by block 206. The transceiver apparatus 206 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device.

Figure 3 shows an example of a control apparatus 300 for a communication system, for example to be coupled to and/or for controlling a station of an access system, such as a RAN node, e.g. a base station, eNB or gNB, a relay node or a core network node such as an MME or Serving Gateway (S-GW) or Packet Data Network Gateway (P-GW), or a core network function such as AMF/SMF, or a server or host. The method may be implemented in a single control apparatus or across more than one control apparatus. The control apparatus may be integrated with or external to a node or module of a core network or RAN. In some embodiments, base stations comprise a separate control apparatus unit or module. In other embodiments, the control apparatus can be another network element such as a radio network controller or a spectrum controller. In some embodiments, each base station may have such a control apparatus as well as a control apparatus being provided in a radio network controller. The control apparatus 300 can be arranged to provide control on communications in the service area of the system. The control apparatus 300 comprises at least one memory 301, at least one data processing unit 302, 303 and an input/output interface 304. Via the interface the control apparatus can be coupled to a receiver and a transmitter of the base station. The receiver and/or the transmitter may be implemented as a radio front end or a remote radio head.

In 3GPP Carrier Aggregation (CA) has been supported in Sidelink (SL). When there is SL data to transmit, a UE selects a TX carrier to transmit the SL data. To satisfy a QoS requirement, a Channel Busy Ratio (CBR) condition of the carrier may be taken into account in TX carrier selection.

When the UE has a MAC CE to transmit over the SL channel, the UE selects a carrier for transmission of the SL data and multiplexes the MAC CE into the MAC PDU together with the SL data.

An example of a MAC CE which may be transmitted by a UE is a CSI reporting MAC CE. In the SL case an example MAC CE may be referred to as a SL-CSI reporting MAC CE.

For example, SL-CSI reporting may be triggered when a SL-CSI request is received at a UE on a carrier. Figure 4 illustrates a block diagram of a SL-CSI reporting MAC CE. In Figure 4, RI is a Rank Indicator filed and CQI is a Channel Quality Indication field. In a SL-CSI reporting MAC CE, there is no separate indication indicating a cell information for which the SL-CSI is reported.

Under a restriction that there is only one ongoing SL-CSI reporting procedure, a UE may be able to transmit SL-CSI report MAC CE on any carrier. Therefore, as long as there is a SL data that can be transmitted, the SL-CSI reporting MAC CE can be transmitted in a MAC PDU which includes any SL data.

However, restriction to a single ongoing SL-CSI reporting procedure may cause latency in transmission of SL-CSI reporting for multiple carriers, which is not desirable for simultaneous use of multiple carriers. Therefore, this restriction may be relaxed, i.e., there can be multiple SL-CSI reporting procedures in parallel. Due to lack of carrier information in a SL-CSI reporting MAC CE, the SL-CSI reporting MAC CE may be only sent on the carrier where the SL-CSI request is received. In clause 5.22.1.11 of TS 38.321 (vl8.1.0), the UE selects a carrier for transmission of SL data from a SL LCH by considering the CBR condition of the carrier, wherein the CBR condition is determined based on parameters such as sl-threshCBR-FreqReselection or sl-threshCBR- FreqKeeping associated with a priority of SL logical channel (LCH). sl-priorityList is an example parameter which indicates the list of sidelink logical channel priority which is associated with the configurations in sl-threshCBR-FreqReselection and in sl- threshCBR-FreqKeeping. sl-threshCBR-FreqReselection is an example parameter which indicates the CBR threshold based on which UE determines whether the carrier frequency can be (re)selected for the transmission of SL data using the NR sidelink. sZ-t/zre.s'/zCBR-FreqKeeping is an example parameter which indicates the CBR threshold based on which UE determines whether the UE can keep using the carrier which was selected for the transmission of SL data using the NR sidelink.

In SL CA operation, for a MAC CE, there is no CBR condition associated with the MAC CE that can be used in carrier selection for transmission of the MAC CE. This may still allow transmission of the MAC CE over any carrier as long as there is SL LCH data available for transmission as carrier will be selected for transmission of the SL LCH data and MAC CE can be multiplexed with the SL LCH data. For instance, SL-CSI reporting MAC CE is transmitted on any carrier if there is SL resources selected on that carrier for transmission of SL LCH data and SL-CSI reporting MAC CE can be accommodated in the same MAC PDU.

As mentioned above, restriction on only one ongoing SL-CSI reporting procedure leads to delayed transmission of SL-CSI reporting, which is harmful in use of multi-carrier simultaneously. Thus, RAN2 decided that the SL CSI reporting MAC CE is sent only on the carrier where the SL CSI request is received. However, lack of CBR condition associated with the MAC CE may still delay the transmission of MAC CE because the UE needs to wait until new SL LCH data becomes available in order to select a carrier unless there is immediate SL LCH data available for transmission. Therefore, a CBR condition should be assigned to the MAC CE as well as SL LCH data. Given that the priority of the SL MAC CE may be fixed to a relatively higher level than any SL data from STCH or SL-PRS, in order to get more chance of transmission, the CBR condition for transmitting the SL CSI reporting MAC CE may be more relaxed, i.e., CBR threshold is higher, than the CBR condition for transmitting the SL LCH data, That is, carrier which does not satisfy the CBR condition of the SL LCH data may be still possible to be used for transmission of the SL CSI reporting MAC CE.

On the other hand, a more relaxed CBR condition for SL CSI reporting MAC CE may lead to transmission of the SL CSI reporting MAC CE while the CBR is high and thus limited available resources are used for SL CSI reporting MAC CE transmission. As a result, the transmission of the SL CSI reporting MAC CE may be delayed even beyond the SL CSI reporting latency boundary.

Meanwhile, it may be resource inefficient to always select a separate carrier for transmission of SL CSI reporting MAC CE and SL LCH data. Thus, there should be some flexibility in selecting the TX carrier for SL CSI reporting MAC CE by considering the presence of SL LCH data.

If a SL MAC CE needs to be transmitted over a certain carrier, or if the SL MAC CE needs to be transmitted without being multiplexed with any other SL data, there should be a carrier selection rule defined for the SL MAC CE.

Figure 5 shows a flowchart of a method according to an example embodiment. The method may be performed at an apparatus. The apparatus may comprise a UE. The apparatus may be in SL communication with a further apparatus (e.g., a further UE).

At 501, the method comprises triggering transmission of a MAC CE from the apparatus to a user equipment.

At 502, the method comprises obtaining at least one CBR condition for transmission of the MAC CE on a carrier. At 503, the method comprises determining, based on the obtained at least one CBR condition, that the MAC CE can be transmitted on the carrier.

At 504, the method comprises providing the MAC CE from the apparatus to the user equipment on the carrier, based on the determining.

The MAC CE may comprise a CSI reporting MAC CE. Triggering transmission of the MAC CE from the apparatus to the user equipment may comprise receiving a request at the apparatus for channel state reporting of the carrier. The request may be received on the carrier or on a different carrier.

In an example embodiment, a CBR condition for a SL CSI reporting MAC CE is proposed so that the UE can determine whether or not to transmit the SL CSI reporting MAC CE on the carrier for which the SL CSI request is received even when there is no SL LCH data.

Obtaining the at least one CBR condition may comprise receiving an indication of the at least one CBR condition from a network entity.

For example, the CBR condition of the SL CSI reporting MAC CE may be configured explicitly or implicitly by means of an RRC or MAC signal.

Each of the at least one CBR condition may be associated with a given carrier. The CBR condition associated with a primary or legacy carrier may be higher than the CBR condition associated with a secondary or other carrier.

In an example embodiment, a network may explicitly indicate a CBR condition of the SL CSI reporting MAC CE including e.g., the sl-threshCBR. The network may provide different CBR condition for SL CSI reporting MAC CE depending on which carrier the SL CSI reporting MAC CE is transmitted.

For example, if a SL CSI reporting MAC CE is to be transmitted on a carrier A, which is a primary carrier or a legacy carrier, the CBR condition would be more relaxed than that to be applied for any other carrier, i.e., the SL CSI reporting MAC CE on the primary carrier would be transmitted even when the CBR is high while the SL CSI reporting MAC CE on the other carrier would be transmitted when the CBR is low.

Obtaining the at least one CBR condition may comprise selecting a priority level of a logical channel from the plurality of logical channels allowed to be transmitted on the carrier. Each logical channel may be associated with a priority level. Determining the at least one CBR condition for transmission of a MAC CE on the carrier may be based on a CBR condition associated with the selected priority. The method may comprise receiving an indication of the CBR condition associated with the priority of the logical channel. The method may comprise receiving an indication of a carrier allowed for the logical channel. Obtaining the at least one CBR condition may be based on receiving an indication of the CBR condition associated with the priority of the logical channel, and a carrier allowed for the logical channel.

The method may further comprise receiving an identifier of the logical channel and determining the at least one CBR condition further based on the identifier.

Figure 6 shows a flowchart of a method according to an example embodiment. The method may be performed at an apparatus. The apparatus may comprise a UE. The apparatus may be in SL communication with a further apparatus (e.g., a further UE).

At 601, the method comprises configuring a plurality of logical channels, wherein each logical channel is associated with a priority level.

At 602, the method comprises triggering transmission of a MAC CE from the apparatus to a user equipment.

At 603, the method comprises selecting a priority level of a logical channel from the plurality of logical channels allowed to be transmitted on a carrier.

At 604, the method comprises determining at least one channel busy ratio, CBR, condition for transmission of a MAC CE on the carrier based on a CBR condition associated with the selected priority. At 605, the method comprises determining, based on the determined at least one CBR condition, that the MAC CE can be transmitted on the carrier.

At 606, the method comprises providing the MAC CE from the apparatus to the user equipment on the carrier, based on the determining that the MAC CE can be transmitted on the carrier.

The method may comprise receiving an indication of the priority level from the network. Selecting the priority level may be based on the indication of the priority level. The network may indicate a specific priority level or indicate the highest priority level or the lowest priority level among the LCHs mapped to a carrier. The carrier may be the carrier where a corresponding CSI reporting request was received.

The highest or lowest priority among the LCHs may refer to the highest or lowest priority, respectively, among the LCHs that are mapped to the carrier by the network configuration or to the highest or lowest priority, respectively, among the LCHs that has available data for transmission and mapped to the carrier by the network configuration.

The highest priority level or highest priority (without a level attached) may correspond to the lowest priority value.

In an example embodiment, when the CBR condition is determined based on a CBR associated with a priority level, the CBR condition for a SL CSI reporting MAC CE may include only one of the sl-threshCBR-FreqReselection or the sl-threshCBR-FreqKeeping, or may include both of the the sl-threshCBR-FreqReselection or the sl-threshCBR-FreqKeeping.

In an example embodiment, if SL CSI reporting is triggered for a carrier, the CBR condition for the SL CSI reporting is determined based on the SL LCH with the highest logical channel priority level among the SL LCHs that are allowed to be transmitted on the carrier. In other words, in TX carrier selection procedure for the SL CSI reporting MAC CE, the UE uses the sl-threshCBR-FreqReselection or the sl-threshCBR-FreqKeeping which is associated with the SL LCH having the highest priority level; This option may be suitable if it is considered that the priority of SL CSI reporting MAC CE is equal to or similar to SL LCH having the highest priority level.

This allows transmission of the SL CSI reporting MAC CE with a more relaxed CBR condition, i.e., even a high CBR condition, on the carrier. One consequence of this option is that the SL CSI reporting MAC CE may not be multiplexed with a SL LCH data if a CBR of a carrier meets the CBR condition of the SL CSI reporting MAC CE but does not meet the CBR condition of a SL LCH data.

For example, if SL LCHA and SL LCHB are allowed to be transmitted on the carrierA, while the priority level of SL LCHA is higher than that of SL LCHB, the UE uses the sl-threshCBR- FreqReselection or the sl-threshCBR-FreqKeeping associated with SL LCHA to determine whether SL CSI reporting MAC CE should be transmitted on the carrier from which the SL CSI request is received.

In an example embodiment, the CBR condition for the SL CSI reporting may be determined based on the SL LCH with the lowest logical channel priority level among the SL LCHs that are allowed to be transmitted on the carrier. In other words, for the SL CSI reporting MAC CE, the UE uses the sl-threshCBR-FreqReselection or the sl-threshCBR-FreqKeeping which is associated with the SL LCH having the lowest priority level to determine whether SL CSI reporting MAC CE should be transmitted on the carrier from which the SL CSI request is received.

This option may be suitable if it is considered more important to ensure low CBR condition for transmission of data. For example, if SL LCHA and SL LCHB are allowed to be transmitted to the carrierA, while the priority level of SL LCHA is higher than that of SL LCHB, the UE uses the sl-threshCBR-FreqReselection or the sl-threshCBR-FreqKeeping associated with SL LCHB to determine whether SL CSI reporting MAC CE should be transmitted on the carrier from which the SL CSI request is received.

The network may indicate a specific LCH identifier, of which the CBR condition of the priority level of that LCH is used for the CBR condition of the MAC CE. For example, if SL LCHA and SL LCHB are allowed to be transmitted on the carrierA, and the network indicates SL LCHA should be used, then the UE uses the sl-threshCBR- FreqReselection or the sl-threshCBR-FreqKeeping associated with the priority of the SL LCHA to determine whether SL CSI reporting MAC CE should be transmitted on the carrier from which the SL CSI request is received.

In an example embodiment, the UE may select the CBR condition of SL CSI reporting MAC CE by itself among the CBR conditions associated with the priority of SL LCHs that are allowed to be transmitted on the carrier where the SL CSI reporting is triggered.

Any combination of above methods can also be considered.

The UE may select either the highest or lowest priority based on a condition or based on network configuration (e.g. network indicates whether to use the highest or lowest priority or network configures the remaining time threshold for UE to determine which option to choose). Selecting the highest priority may provide a relaxed CBR condition for transmission of SL CSI reporting MAC CE while selecting the lowest priority may provide more secure transmission opportunity by restricting the CBR condition for transmission of SL CSI reporting MAC CE.

Determining to select the highest priority or the lowest priority may be based on the time remaining on a reporting timer. For example, a UE may select either highest or lowest priority depending on how long it has been since the SL CSI reporting MAC is triggered.

In an example embodiment, if the remaining time of sl-CSI-ReportTimer is less than a certain time, the UE may select the highest priority while the UE selects the lowest priority until the remining time of sl-CSI-ReportTimer is equal to or larger than the certain time.

Determining to select the highest priority or the lowest priority may be based on a number of carriers for which failure is detected. For example, a UE may select either the highest or the lowest priority depending on the number of carriers for which carrier failure is detected or the number of carriers that can be used for transmission for the pair of Source and Destination. In an example embodiment, if the number of failed carriers exceeds a threshold, the UE selects the highest priority so that the channel state information is timely delivered. The UE may select the lowest priority if the number of carriers that can be used for transmission for the pair of Source and Destination exceeds a threshold.

Determining to select the highest priority or the lowest priority may be based on a quality of service (QoS) requirement for data on the carrier. For example, the UE may select either the highest priority or the lowest priority depending on QoS requirements of SL LCH data received on the carrier where the CSI request is received.

Determining to select the highest priority or the lowest priority may be based on a type of carrier aggregation (e.g., CA duplication or CA split operation). Requirements such as reliability, latency and data rate are directly related to whether CA is for duplication (high reliability and/or low latency) or split (high data rate). Thus, the UE may select either the highest priority or the lowest priority based on whether the carrier where the CSI request is received is used for receiving SL LCH with CA duplication or with CA split operation.

In an example embodiment, the UE may select the highest priority if the carrier where the CSI request is received is associated with an RB for which SL CA duplication is performed and/or the Packet Delay Budget (PDB) of the RB is below a threshold (corresponding to the low latency case). The UE may select the lowest priority if the carrier where the CSI request is received is associated with an RB for which SL split operation is performed and/or the PDB of the RB is equal to or above a threshold (corresponding to either the high reliability or high data rate case).

A method may comprise selecting a carrier for data transmission based on the carrier used for transmission of the channel state reporting element. For example, when the UE performs TX carrier selection for SL LCH, if there are multiple candidate carriers including the carrier selected for transmission of the SL CSI reporting MAC CE, the UE prioritizes selection of the carrier selected for transmission of the SL CSI reporting MAC CE.

After prioritizing the carrier selected for transmission of the SL CSI reporting MAC CE, the UE selects the carrier with increasing order of CBR from the lowest CBR. This may increase the possibility of multiplexing SL CSI reporting MAC CE and SL LCH data for resource efficiency.

By using the proposed CBR condition for the SL CSI reporting MAC CE, the UE performs the TX carrier (re-)selection procedure for each of the triggered SL CSI reporting. For each of the triggered SL CSI reporting, the UE determines whether the SL CSI reporting MAC CE can be transmitted on a carrier where the SL CSI request was received based on the CBR condition corresponding to the SL CSI reporting MAC CE.

After selecting carriers for all the triggered SL CSI reporting, i.e., determining whether the SL CSI reporting MAC CE can be transmitted or not on the carrier where the SL CSI request was received, the UE performs TX carrier selection for each SL LCH having data available for transmission. For each SL LCH having data available for transmission, if there are multiple candidate carriers including the carrier selected for transmission of the SL CSI reporting MAC CE, the UE first selects, i.e., prioritizes, this carrier where the SL CSI reporting MAC CE is to be transmitted. And then, if the UE further decides to select more carriers (by implementation), the UE selects the carrier with increasing order of CBR from the lowest CBR. This is to allow transmission of SL CSI reporting MAC CE by multiplexing with SL LCH data as much as possible.

When a SL CSI reporting is triggered, the UE selects a TX carrier for transmission of a SL CSI reporting MAC CE by considering a possible SL LCH data on the concerned carrier. As a result, the UE can transmit SL CSI reporting MAC CE by multiplexing with a SL LCH data while ensuring a good CBR condition for transmission of the SL CSI reporting MAC CE.

Figure 7 shows a flowchart of a method at an apparatus according to an example embodiment in which SL LCHA and SL LCHB are allowed to be transmitted on carrier A. The priority level of SL LCHA is higher than that of SL LCHB.

In step 1 , SL CSI is triggered for carrier A (the apparatus receives a request for channel state reporting of the carrier).

In step 2, the apparatus selects CBR parameters associated with the priority level of SL LCHA- This is an example of selecting a priority level of a logical channel from the plurality of logical channels allowed to be transmitted on a carrier and determining at least one CBR condition for transmission of a MAC CE on the carrier based on a CBR condition associated with the selected priority.

In step 3, the apparatus performs TX carrier selection for SL CSI reporting MAC CR by using the selected CBR parameters. This is an example of determining, based on the determined at least one CBR condition, that the MAC CE can be transmitted on the carrier and providing the MAC CE from the apparatus to the user equipment on the carrier, based on the determining that the MAC CE can be transmitted on the carrier.

Figure 8 shows a flowchart of a method according to an example embodiment in which SL LCHA is allowed to be transmitted on carrier A and SL LCHB is allowed to be transmitted on carrier A and carrier B. The priority level of SL LCHA is higher than that of SL LCHB.

In step 1 , SL CSI is triggered for carrier B (the apparatus receives a request for channel state reporting of the carrier).

In step 2, the apparatus selects CBR parameters associated with the priority level of SL LCHB. This is an example of selecting a priority level of a logical channel from the plurality of logical channels allowed to be transmitted on a carrier and determining at least one CBR condition for transmission of a MAC CE on the carrier based on a CBR condition associated with the selected priority.

An apparatus may comprise means for triggering transmission of a MAC CE from the apparatus to a user equipment, obtaining at least one CBR condition for transmission of the MAC CE on a carrier, determining, based on the obtained at least one CBR condition, that the MAC CE can be transmitted on the carrier and providing the MAC CE from the apparatus to the user equipment on the carrier, based on the determining. An apparatus may comprise means for configuring a plurality of logical channels, wherein each logical channel is associated with a priority level, triggering transmission of a MAC CE, from the apparatus to a user equipment, selecting a priority level of a logical channel from the plurality of logical channels allowed to be transmitted on a carrier, determining at least one CBR, condition for transmission of a MAC CE on the carrier based on a CBR condition associated with the selected priority, determining, based on the determined at least one CBR condition, that the MAC CE can be transmitted on the carrier and providing the MAC CE from the apparatus to the user equipment on the carrier, based on the determining that the MAC CE can be transmitted on the carrier.

The apparatus may comprise a user equipment as described with reference to Figure 2, be the UE or be comprised in the UE or a chipset for performing at least some actions of/for the UE. The UE may be capable of SL communication.

A network function refers to a device/apparatus which is configured to perform or performs at least part of functionalities of the network function or to a device/apparatus which comprises circuitry (e.g., chipset) configured to perform or performing at least part of functionalities of the network function.

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

It is noted that whilst some embodiments have been described in relation to 5G networks, similar principles can be applied in relation to other networks and communication systems such as 6G networks or 5G-Advanced networks. Therefore, although certain embodiments were described above by way of example with reference to certain example architectures for wireless networks, technologies and standards, embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein. It is also noted herein that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

As used herein, “at least one of the following: <a list of two or more elements>” and “at least one of <a list of two or more elements>” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

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

As used in this application, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable):

(i) a combination of analog and/or digital hardware circuit(s) with software/firmware and

(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

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

Further in this regard it should be noted that any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD. The physical media is a non-transitory media. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting examples. Embodiments of the disclosure may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

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

The foregoing description has provided by way of non-limiting examples a full and informative description of the exemplary embodiment of this disclosure. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of this disclosure will still fall within the scope of this invention as defined in the appended claims. Indeed, there is a further embodiment comprising a combination of one or more embodiments with any of the other embodiments previously discussed.

Claims

1. An apparatus comprising means for: configuring a plurality of logical channels, wherein each logical channel is associated with a priority level; triggering transmission of a media access control element, MAC CE, from the apparatus to a user equipment; selecting a priority level of a logical channel from the plurality of logical channels allowed to be transmitted on a carrier; determining at least one channel busy ratio, CBR, condition for transmission of a MAC CE on the carrier based on a CBR condition associated with the selected priority; determining, based on the determined at least one CBR condition, that the MAC CE can be transmitted on the carrier; and providing the MAC CE from the apparatus to the user equipment on the carrier, based on the determining that the MAC CE can be transmitted on the carrier.

2. The apparatus according to claim 1, comprising means for receiving an indication of the priority level from the network and wherein selecting the priority level is based on the indication of the priority level.

3. The apparatus according to claim 1, comprising means for selecting a highest priority level or a lowest priority level.

4. The apparatus according to claim 3, comprising means for determining to select the highest priority or the lowest priority based on at least one of the following: time remaining on a reporting timer, a number of carriers for which failure is detected, a type of carrier aggregation operation or a quality of service requirement for data on the carrier.

5. The apparatus according to any of claims 1 to 4, wherein determining at least one CBR condition comprises determining a CBR condition associated with a logical channel having the selected priority level.

6. The apparatus of any of claims 1 to 5, wherein the MAC CE comprises a channel state information reporting MAC CE.

7. The apparatus according to claim 6, wherein triggering transmission of the MAC CE from the apparatus to the user equipment comprises receiving a request at the apparatus for channel state reporting of the carrier.

8. The apparatus of any of claims 1 to 7, wherein the apparatus and the user equipment communicate using sidelink.

9. A method comprising, at an apparatus: configuring a plurality of logical channels, wherein each logical channel is associated with a priority level; triggering transmission of a media access control control element, MAC CE, from the apparatus to a user equipment; selecting a priority level of a logical channel from the plurality of logical channels allowed to be transmitted on a carrier; determining at least one channel busy ratio, CBR, condition for transmission of a MAC CE on the carrier based on a CBR condition associated with the selected priority; determining, based on the determined at least one CBR condition, that the MAC CE can be transmitted on the carrier; and providing the MAC CE from the apparatus to the user equipment on the carrier, based on the determining that the MAC CE can be transmitted on the carrier.

10. The method according to claim 9, further comprising receiving an indication of the priority level from the network and wherein selecting the priority level is based on the indication of the priority level.

11. The method according to claim 9, further comprising selecting a highest priority level or a lowest priority level.

12. The method according to claim 11, further comprising determining to select the highest priority or the lowest priority based on at least one of the following: time remaining on a reporting timer, a number of carriers for which failure is detected, a type of carrier aggregation operation or a quality of service requirement for data on the carrier.

13. The method according to any of claims 9 to 12, wherein determining at least one CBR condition comprises determining a CBR condition associated with a logical channel having the selected priority level.

14. The method of any of claims 9 to 13, wherein the MAC CE comprises a channel state information reporting MAC CE.

15. The method according to claim 14, wherein triggering transmission of the MAC CE from the apparatus to the user equipment comprises receiving a request at the apparatus for channel state reporting of the carrier.

16. The method of any of claims 9 to 15, wherein the apparatus and the user equipment communicate using sidelink.

17. An apparatus comprising at least one processor, and at least one memory storing instructions which, when executed by the processor, cause the apparatus at least to perform: configuring a plurality of logical channels, wherein each logical channel is associated with a priority level; triggering transmission of a media access control control element, MAC CE, from the apparatus to a user equipment; selecting a priority level of a logical channel from the plurality of logical channels allowed to be transmitted on a carrier; determining at least one channel busy ratio, CBR, condition for transmission of a MAC CE on the carrier based on a CBR condition associated with the selected priority; determining, based on the determined at least one CBR condition, that the MAC CE can be transmitted on the carrier; and providing the MAC CE from the apparatus to the user equipment on the carrier, based on the determining that the MAC CE can be transmitted on the carrier.

18. A computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform: configuring a plurality of logical channels, wherein each logical channel is associated with a priority level; triggering transmission of a media access control control element, MAC CE, from the apparatus to a user equipment; selecting a priority level of a logical channel from the plurality of logical channels allowed to be transmitted on a carrier; determining at least one channel busy ratio, CBR, condition for transmission of a MAC CE on the carrier based on a CBR condition associated with the selected priority; determining, based on the determined at least one CBR condition, that the MAC CE can be transmitted on the carrier; and providing the MAC CE from the apparatus to the user equipment on the carrier, based on the determining that the MAC CE can be transmitted on the carrier.