GB2608683A - Improvements in and relating to Secondary Cell Group configuration - Google Patents

Abstract

A User Equipment (UE) may use assistance information (UEAssistanceInformation) messages to a Master Node (MN) or a Secondary Node (SN) to indicate that it wishes a Secondary Cell Group (SCG) to be deactivated. This provides an efficient means for the UE to deactivate the SCG, rather than releasing it and subsequently adding it again. It does not require excessive UE activity (and power consumption) while the SCG is not used in order to be able to quickly reactivate the SCG.

Description

Improvements in and relating to Secondary Cell Group Configuration The present invention relates to the configuration of a Secondary Cell Group, SCG, in a telecommunication system and, more particularly to it selective deactivation. It finds particular, but not exclusive use in a Fifth Generation, 5G, system.

As part of Release 17 of the 5G specification, there is a plan to introduce an option to deactivate the Secondary Cell Group, SCG, thereby aiming to resume SCG quicker as compared to when releasing and subsequently adding the SCG.

One drawback in this plan is that the UE will need to perform certain activities while the SCG is not used, merely to facilitate quick re-activation. In other words, there is a trade-off between latency at activation and power saving while the SCG is not used (or deactivated). Details are still being decided.

However, in the specification stages, it was decided: "The UE can indicate to the Master Node, MN, that the UE would like the SCG to be deactivated. For Future Study: on the details (e.g. reusing Unified Air Interface, UAI, or existing messages, information included, etc.). Network can configure whether UE is allowed to do the indication." Some further background information is provided In this section to provide an overview of the UE assistance available in current standards, that may serve a similar purpose as the SCG deactivation request now agreed for SCG deactivation.

In the case of overheating, there are several techniques which may be used to assist. In a first approach in Evolved-Universal Terrestrial Radio Access-New Radio Dual Connectivity, EN-DC, SCG content in a container is sent via Signaling Radio Bearer 1, SRB1, that the MN can forward transparently. In other cases, the MN receives all information and decides SCG configuration accordingly.

Also in the case of EN-DC, the UE provides NR OverheatingAssistance IE that can include a preference of Bandwidth, BW, of 0 size for both Frequency Ranges 1 and 2, FR1 and FR2. As such, there is a way to indicate a preference to have no SCG, that the MN can use as a trigger for deactivation. However, standards only allow this option for FR1. Moreover, the cause is somewhat different.

In other cases, there is no such indication i.e. there is simply a preference per FR, but not per SCG (assuming no limitations anymore regarding use of FR for SCG).

In the case of power preference, for NR SCG, configuration and reporting is separate per cell group, using SRB1 with embedding or SRB3 (both for configuration and report). This is supported for NR-DC and (NG)EN-DC. The UE can indicate 'no SCG' preference by indicating value 0 for Component Carriers, #CCs. The preference regarding BW and Multiple-input/multiple-out, MIMO, layers can again be provided per FR, while (only) for BW, value 0 is supported.

In summary, for EN-DC, the UE could indicate to the MN by means of overheating assistance that it prefers to have no SCG (by setting BW size to 0 for FR2. i.e. when FR1 is not configured, as this option is prohibited for FR1).

The SN can configure power preference assistance for the SCG, by which means the UE can indicate a preference for 'no SCG' by value 0 for #CCs. However, this information is provided to the SN rather than the MN.

However, it has been agreed that the UE assistance information is sent to the MN, which is the node that generates the RRC message including the SCG deactivation instruction.

It is an aim of embodiments of the present invention to indicate that it wishes to deactivate the SCG. Additionally, it is desirable to be able to do this without unduly complicating UE and/or system design and to minimise the impact on other features of the specification.

According to the present invention there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent

claims, and the description which follows.

According to a first aspect of the present invention, there is provided a method of operating a User Equipment, UE, in a telecommunication network wherein the UE provides assistance information to a Master Node, MN, or a Secondary Node, SN, of the telecommunication that the UE wishes a Secondary Cell Group, SCG, to be deactivated.

In an embodiment, in the case where the UE provides assistance information to the MN, then a message, UEAssistancelnformation, is provided with a field, deactivateSCG, to indicate that it prefers SCG deactivation.

In an embodiment, a prohibit timer is used that defines a minimum time in-between UE assistance concerning SCG deactivation.

In an embodiment, the UE is configured to provide different types of assistance information simultaneously.

In an embodiment, options for simultaneous configuration of multiple UE assistance information features concerning SCG preferences include defining conditions specifying in which cases the UE triggers certain UE assistance.

In an embodiment, a first such condition is a rule defining in which case the UE triggers different UE assistance, such as defining in which condition it prefers deactivation of SCG and in which case it prefers release of SCG.

In an embodiment, a second such condition involves the network configuring a time interval which the UE observes between different SCG-related assistance indications.

In an embodiment, the assistance information includes an option to cancel a previous UE preference, including SCG deactivation.

According to a second aspect of the present invention, there is provided a User Equipment arranged to perform the method of the first aspect.

Although a few preferred embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims.

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example only, to the accompanying diagrammatic drawings in which: Figure 1 shows a message flow according to an embodiment of the present invention.

In a first embodiment, the UE provides assistance for SCG deactivation to SN. It should be noted that it has not been explicitly excluded that deactivation by MAC CE may be sent via the SCG leg. Such an option may be possible in case all RBs using SCG resource are SN terminated, as in such cases, the SN can coordinate SCG deactivation by itself. In such a scenario, it would be preferable if the UE indicates to the SN that it prefers to have noSCG'. Such an approach is possible according to existing standards, as indicated above.

For SCG deactivation, the existing UAI defined for power preference is re-used to indicate to the SN that it prefers to have no SCG. This option may be used, for instance, in case all RBs using SCG resources are SN terminated and/or the network can use a MAC CE sent via SCG leg to deactivate the SCG.

In a second embodiment, UE assistance for SCG deactivation is provided to the MN. As indicated previously, it has been agreed that the UE provides the assistance for SCG deactivation to MN. To do this, the UEAssistancelnformation is extended with a field by which the UE can indicate that it prefers SCG deactivation e.g. deactivateSCG.

In a third embodiment, options for when the UE may trigger sending the UEAssistancelnformation to indicate that it prefers SCG deactivation include the following: a) No conditions are specified i.e. it is entirely left up to UE implementation b) A prohibit timer is used that defines the minimum time in-between UE assistance concerning SCG deactivation (interval applies to both the time between on and off and between off and on) c) A unidirectional prohibit timer i.e. the minimum time only applies for the time between on and off (to avoid latency at activation) d) The time the UE was not using SCG resources for UL data transfer (possibly taking int account existing rules defined regarding which leg to use for a split RBs) e) Combinations of the above The UE may further be configured to provide different types of UE assistance at the same time. In particular the following UE assistance: UE in EN-DC: Overheating assistance; and/or UE in NR-DC: Power preference for SCG.

In a fourth embodiment, options for simultaneous configuration of multiple UE assistance information features concerning SCG preferences, include the following: a) Simultaneous configuration of multiple of such UE assistance features is not supported b) Simultaneous configuration of multiple of such UE assistance features is supported, with the following 1) Conditions are specified defining in which cases UE triggers certain UE assistance. E.g.

i. A rule is defined defining in which case UE triggers the different UE assistance e.g. defining in which condition it prefers deactivation of SCG and in which case it prefers release of SCG ii. The network can configure a time interval which the UE shall observe between the different SCG related UE assistance indications 2) It is left up to UE implementation when the UE triggers the different SCG related UE assistance indications UE assistance includes the option to cancel a previous UE preference. This also applies for the SCG deactivation. However, it is presently not clear how this relates to SCG activation, i.e. whether the UE assistance to cancel SCG deactivation preference is the same as UE assistance for SCG activation request. This matter may therefore we be left to UE implementation or may require further study.

In a fifth embodiment, options for simultaneous configuration of other UE assistance information concerning SCG preferences include when the UE may trigger sending the UEAssistancelnformation to indicate that it prefers SCG deactivation and may include the following: a) Support cancellation of UE assistance indication SCG deactivation preference b) Alongside support UE assistance for indicating SCG activation preference c) Options for use of these UE assistances to indicate preference to activate a deactivated SCG include the following 1) UE can either provide assistance indicating cancellation of the SCG deactivation preference or provide assistance indicating SCG activation preference. This option may apply only in specific cases e.g. when UE provided assistance indicating preference to deactivate 2) UE can only provide assistance indicating SCG activation preference. This may apply only in specific cases e.g. when UE did not provide assistance indicating SCG deactivation preference Figure 1 shows a message sequence for an example illustrating some aspects related to various embodiments of the present invention. The figure shows message exchanges between UE 100, MN 110 and SN 120.

In more detail, the steps in Figure 1 are described below.

S11. UE indicates a preference to deactivate the SCG S12. SN indicates that SCG is inactive/ requests SCG deactivation Note that the two messages 311, S12 may appear in a different order 15 S13. MN initiates to SN that SCG should be deactivated S14. In response, the SN may provide SCG configuration information S15. The MN indicates the SCG deactivation to the UE and may include any SCG reconfiguration provided by SN e.g. CFRA resources to be used at activation S16. Upon receiving Reconfiguration complete from the UE, the MN confirms successful deactivation to SN Embodiments of the present invention include options for the UE to provide assistance regarding SCG deactivation, taking into account the currently defined framework. It provides different alternatives, balancing simplicity and flexibility. For instance, more signalling changes may result in more network control and/or additional flexibility, such as better control of which information the UE should signal to the network.

At least some of the example embodiments described herein may be constructed, partially or wholly, using dedicated special-purpose hardware. Terms such as 'component, 'module' or unit used herein may include, but are not limited to, a hardware device, such as circuitry in the form of discrete or integrated components, a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), which performs certain tasks or provides the associated functionality. In some embodiments, the described elements may be configured to reside on a tangible, persistent, addressable storage medium and may be configured to execute on one or more processors. These functional elements may in some embodiments include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. Although the example embodiments have been described with reference to the components, modules and units discussed herein, such functional elements may be combined into fewer elements or separated into additional elements. Various combinations of optional features have been described herein, and it will be appreciated that described features may be combined in any suitable combination. In particular, the features of any one example embodiment may be combined with features of any other embodiment, as appropriate, except where such combinations are mutually exclusive. Throughout this specification, the term "comprising" or "comprises" means including the component(s) specified but not to the exclusion of the presence of others.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims (9)

1. CLAIMS1. A method of operating a User Equipment, UE, in a telecommunication network wherein the UE provides assistance information to a Master Node, MN, or a Secondary Node, SN, of the telecommunication that the UE wishes a Secondary Cell Group, SCG, to be deactivated.
2. 2. The method of claim 1 wherein in the case where the UE provides assistance information to the MN, then a message, UEAssistancelnformation, is provided with a field, deactivateSCG, to indicate that it prefers SCG deactivation.
3. 3. The method of claim 1 or 2 wherein a prohibit timer is used that defines a minimum time in-between UE assistance concerning SCG deactivation.
4. 4. The method of any preceding claim wherein the UE is configured to provide different types of assistance information simultaneously.
5. 5. The method of claim 4 wherein options for simultaneous configuration of multiple UE assistance information features concerning SCG preferences include defining conditions specifying in which cases the UE triggers certain UE assistance.
6. 6. The method of claim 5 wherein a first such condition is a rule defining in which case the UE triggers different UE assistance, such as defining in which condition it prefers deactivation of SCG and in which case it prefers release of SCG.
7. 7. The method of claim 5 or 6 wherein a second such condition involves the network configuring a time interval which the UE observes between different SCG-related assistance indications.
8. 8. The method of any previous claim wherein the assistance information includes an option to cancel a previous UE preference, including SCG deactivation.
9. 9. A User Equipment arranged to perform the method of any preceding claim.