Wake-up signals at a ue

Abstract

A first low-power wake-up signal, LP-WUS, is received at a low power radio of a user equipment, UE, of a mobile communication system from a network node of the mobile communication system, the first LP-WUS having a first payload Operation of a main radio of the UE is triggered in response to the first LP-WUS. Monitoring for an additional LP-WUS in a defined slot dependent on capability information of the UE is carried out. An additional LP-WUS is received at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload.

Description

[0001] WAKE-UP SIGNALS

[0002] Field

[0003] Example embodiments may relate to devices, methods and computer programs relating to wake-up signals, WUSs, that are received at a low power radio of a user equipment, UE, and used to trigger operation of a main radio of the UE.

[0004] Background

[0005] Wake-up signals (WUS), sometimes referred to as low-power WUSs, LP-WUSs, are used in radio access technologies (RATs) for energy-saving purposes. A WUS may, for example, be transmitted by a network node to a user device to wake-up the user device from a relatively low power state, for example when data is ready to be transmitted by the network node to the user device. The remains a need for further developments in this field.

[0006] Summary

[0007] The scope of protection sought for various embodiments of the invention 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 invention.

[0008] In a first aspect, this specification describes a user equipment, UE, of a mobile communication system, the UE comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE at least to: receive a first low-power wake-up signal, LP-WUS, at a low power radio of the UE, the first LP-WUS having a first payload; trigger operation of a main radio (e.g. changing from a sleep or idle state to an active mode or state) of the UE in response to the first LP-WUS; monitor for an additional LP-WUS in a defined slot, wherein the defined slot is in a period before an expected wake-up time of the main radio in response to said trigger; and receive said additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload.

[0009] The second payload may convey information relating to subsequent Connected Mode operations. Alternatively, or in addition, the second payload may provide information limiting PDCCH candidates for the main radio of the UE. Alternatively, or in addition, thesecond payload may restrict serving cells for use for carrier aggregation.

[0010] In some example embodiments, the instructions, when executed by the at least one processor, further cause the UE at least to receive LP-WUS configuration information (e.g. as part of R.R.C reconfiguration) from a network node of the mobile communication system, wherein the LP-WUS configuration information defines parameters for monitoring for the additional LP-WUS.

[0011] The defined slot may be one of a plurality of Connected Mode Monitoring Occasions of the mobile communication system, said Monitoring Occasions having a periodicity and an offset (e.g. as configured by R.R.C).

[0012] The first LP-WUS may be received at a Connected Mode Monitoring Occasion preceding the defined slot.

[0013] The first LP-WUS and the additional LP-WUS may be received using the same time and frequency resource types. Alternatively, the first LP-WUS and the additional LP-WUS may be received using different time and frequency resource types.

[0014] Some embodiments further comprise providing an acknowledgement of successful reception of the additional LP-WUS.

[0015] In some example embodiments, the instructions, when executed by the at least one processor, further cause the UE at least to: monitor for a second additional LP-WUS in a second defined slot, wherein the second defined slot is in a period when the main radio is ramping up in response to said trigger; and receive said second additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a third payload different to the first and second payloads.

[0016] In a second aspect, this specification describes a user equipment, UE, of a mobile communication system, the UE comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE at least to: receive a first low-power wake-up signal, LP-WUS, at a low power radio of the UE, the first LP-WUS having a first payload; trigger operation of a main radio (e.g. changing from a sleep or idle state to an active mode or state) of the UE inresponse to the first LP-WUS; monitor for an additional LP-WUS in a defined slot, wherein the defined slot is in a period when the main radio is ramping up in response to said trigger; and receive said additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload.

[0017] The second payload may convey information relating to subsequent Connected Mode operations. Alternatively, or in addition, the second payload may provide information limiting PDCCH candidates for the main radio of the UE. Alternatively, or in addition, the second payload may restrict serving cells for use for carrier aggregation.

[0018] In some embodiments the instructions, when executed by the at least one processor, further cause the UE at least to receive LP-WUS configuration information (e.g. as part of R.R.C reconfiguration) from a network node of the mobile communication system, wherein the LP-WUS configuration information defines parameters for monitoring for the additional LP-WUS.

[0019] The defined slot may be one of a plurality of Connected Mode Monitoring Occasions of the mobile communication system, said Monitoring Occasions having a periodicity and an offset (e.g. as configured by R.R.C).

[0020] The first LP-WUS may be received at a Connected Mode Monitoring Occasion preceding the defined slot.

[0021] The first LP-WUS and the additional LP-WUS may be received using the same time and frequency resource types. Alternatively, the first LP-WUS and the additional LP-WUS may be received using different time and frequency resource types.

[0022] In some example embodiments, the instructions, when executed by the at least one processor, further cause the UE at least to provide an acknowledgement of successful reception of the additional LP-WUS.

[0023] In a third aspect, this specification describes a user equipment, UE, of a mobile communication system, the UE comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, causethe UE at least to: receive, from a network node of the mobile communication system, a first low-power wake-up signal, LP-WUS, at a low power radio of the UE, the first LP-WUS having a first payload; trigger operation of a main radio (e.g. changing from a sleep or idle state to an active mode or state) of the UE in response to the first LP-WUS; monitor for an additional LP-WUS in a defined slot dependent on capability information of the UE; and receive, from the network node, an additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload. In some example embodiments, the instructions, when executed by the at least one processor, further cause the UE at least to provide the capability information of the UE to the network node.

[0024] The capability information of the UE may comprise an indication of an ability of the UE to receive an additional LP-WUS. Alternatively, or in addition, the capability information of the UE may comprise an indication of an ability of the UE to receive an additional LP-WUS in a period before an expected wake-up time of the main radio in response to said trigger. Alternatively, or in addition, the capability information of the UE may comprise an indication of an ability of the UE to receive an additional LP-WUS in a period when the main radio is ramping up in response to said trigger. Alternatively, or in addition, the capability information of the UE may comprise an indication of an ability of the UE to receive multiple instances of LP-WUS. Alternatively, or in addition, the capability information of the UE may comprise an indication of an ability of the UE to receive an additional LP-WUS on the same resources as the first LP-WUS. Alternatively, or in addition, the capability information of the UE may comprise an indication of an ability of the UE to receive an additional LP-WUS in different resources as the first LP-WUS. The skilled person will be aware of other possible capability information that may be relevant to some example embodiments.

[0025] The defined slot may be in a period before an expected wake-up time of the main radio in response to said trigger. Alternatively, or in addition, the defined slot may be in a period when the main radio is ramping up in response to said trigger.

[0026] The second payload may convey information relating to subsequent Connected Mode operations.

[0027] In some example embodiments the instructions, when executed by the at least one processor, further cause the UE at least to receive LP-WUS configuration information(e.g. as part of RRC reconfiguration) from a network node of the mobile communication system, wherein the LP-WUS configuration information defines parameters for monitoring for the additional LP-WUS.

[0028] The defined slot may be one of a plurality of Connected Mode Monitoring Occasions of the mobile communication system, said Monitoring Occasions having a periodicity and an offset (e.g. as configured by RRC).

[0029] The first LP-WUS may be received at a Connected Mode Monitoring Occasion preceding the defined slot.

[0030] The first LP-WUS and the additional LP-WUS may be received using the same time and frequency resource types. Alternatively, the first LP-WUS and the additional LP-WUS may be received using different time and frequency resource types.

[0031] In some example embodiments, the instructions, when executed by the at least one processor, further cause the UE at least to provide an acknowledgement of successful reception of the additional LP-WUS.

[0032] In some example embodiments, the instructions, when executed by the at least one processor, further cause the UE at least to: monitor for a second additional LP-WUS in a second defined slot; and receive said second additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a third payload different to the first and second payloads.

[0033] In a fourth aspect, this specification describes network node of a mobile communication system, the network node comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network node at least to: transmit a first low-power wake-up signal, LP-WUS, to a low power radio of a UE of the mobile communication system, the first LP-WUS having a first payload; and transmit an additional LP-WUS to the low power radio of said UE, the additional LP-WUS having a second payload different to the first payload, wherein the additional LP-WUS is sent in a defined slot before an expected wake-up time of the main radio in response to the first LP-WUS.In some example embodiments the instructions, when executed by the at least one processor, further cause the network node at least to provide LP-WUS configuration information to the UE (e.g. as part of R.R.C reconfiguration), wherein the LP-WUS configuration information defines parameters for monitoring for the additional LP-WUS.

[0034] In some example embodiments the instructions, when executed by the at least one processor, further cause the network node at least to receive an acknowledgement of successful reception of the additional LP-WUS at the UE.

[0035] The second payload may convey information relating to subsequent Connected Mode operations. Alternatively, or in addition, the second payload may provide information limiting PDCCH candidates for the main radio of the UE. Alternatively, or in addition, the second payload may restrict serving cells for use for carrier aggregation.

[0036] The defined slot may be one of a plurality of Connected Mode Monitoring Occasions of the mobile communication system, said Monitoring Occasions having a periodicity and an offset (e.g. as configured by R.R.C).

[0037] In some example embodiments, the instructions, when executed by the at least one processor, further cause the network node at least to transmit a second additional LP-WUS to the low power radio of the UE, wherein said additional LP-WUS includes a third payload different to the first and second payloads.

[0038] In a fifth aspect, this specification describes a network node of a mobile communication system, the network node comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the network node at least to: transmit a first low-power wake-up signal, LP-WUS, to a low power radio of a UE of the mobile communication system, the first LP-WUS having a first payload; and transmit an additional LP-WUS to the low power radio of said UE, the additional LP-WUS having a second payload different to the first payload, wherein the additional LP-WUS is sent in a defined slot when the main radio is ramping up in response to said first LP-WUS.

[0039] In some example embodiments, the instructions, when executed by the at least oneprocessor, further cause the network node at least to: provide LP-WUS configuration information to the UE (e.g. as part of R.R.C reconfiguration), wherein the LP-WUS configuration information defines parameters for monitoring for the additional LP-WUS.

[0040] In some example embodiments, the instructions, when executed by the at least one processor, further cause the network node at least to: receive an acknowledgement of successful reception of the additional LP-WUS at the UE.

[0041] The second payload may convey information relating to subsequent Connected Mode operations. Alternatively, or in addition, the second payload may provide information limiting PDCCH candidates for the main radio of the UE. Alternatively, or in addition, the second payload may restrict serving cells for use for carrier aggregation.

[0042] The defined slot may be one of a plurality of Connected Mode Monitoring Occasions of the mobile communication system, said Monitoring Occasions having a periodicity and an offset (e.g. as configured by R.R.C).

[0043] In a sixth aspect, this specification describes network node of a mobile communication system, the network node comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE at least to: transmit a first low-power wake-up signal, LP-WUS, to a UE operating in a low power mode, the first LP-WUS having a first payload; and transmit an additional LP-WUS to the UE in a defined slot dependent on capability information of the UE, the additional LP-WUS having a payload different to the first payload. In some example embodiments, the instructions, when executed by the at least one processor, further cause the network node at least to receive said capability information of the UE from said UE.

[0044] The capability information of the UE may comprise an indication of an ability of the UE to receive an additional LP-WUS. Alternatively, or in addition, the capability information of the UE may comprise an indication of an ability of the UE to receive an additional LP-WUS in a period before an expected wake-up time of the main radio in response to said trigger. Alternatively, or in addition, the capability information of the UE may comprise an indication of an ability of the UE to receive an additional LP-WUS in a period when the main radio is ramping up in response to said trigger. Alternatively, or in addition, the capability information of the UE may comprise an indication of an ability of the UE to receive multiple instances of LP-WUS. Alternatively, or in addition, the capabilityinformation of the UE may comprise an indication of an ability of the UE to receive an additional LP-WUS on the same resources as the first LP-WUS. Alternatively, or in addition, the capability information of the UE may comprise an indication of an ability of the UE to receive an additional LP-WUS in different resources as the first LP-WUS. The skilled person will be aware of other possible capability information that may be relevant to some example embodiments.

[0045] In some example embodiments, the instructions, when executed by the at least one processor, further cause the network node at least to monitor for an acknowledgement from the UE in response to the additional LP-WUS.

[0046] The defined slot may be in a period before an expected wake-up time of the main radio in response to said trigger. Alternatively, or in addition, the defined slot may be in a period when the main radio is ramping up in response to said trigger.

[0047] The second payload may convey information relating to subsequent Connected Mode operations.

[0048] In some example embodiments the instructions, when executed by the at least one processor, further cause the network node at least to provide LP-WUS configuration information (e.g. as part of R.R.C reconfiguration) to the UE, wherein the LP-WUS configuration information defines parameters for monitoring for the additional LP-WUS.

[0049] In some example embodiments, the instructions, when executed by the at least one processor, further cause the UE at least to: provide a second additional LP-WUS in a second defined slot, wherein said additional LP-WUS includes a third payload different to the first and second payloads.

[0050] In a seventh aspect, this specification describes a method comprising: receiving a first low-power wake-up signal, LP-WUS, at a low power radio of a user equipment, UE, of a mobile communication system, the first LP-WUS having a first payload; triggering operation of a main radio (e.g. changing from a sleep or idle state to an active mode or state) of the UE in response to the first LP-WUS; monitoring for an additional LP-WUS in a defined slot, wherein the defined slot is in a period before an expected wake-up time of the main radio in response to said trigger; and receiving said additional LP-WUS at thelow power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload.

[0051] The second payload may convey information relating to subsequent Connected Mode operations. Alternatively, or in addition, the second payload may provide information limiting PDCCH candidates for the main radio of the UE. Alternatively, or in addition, the second payload may restrict serving cells for use for carrier aggregation.

[0052] The method may further comprise receiving LP-WUS configuration information (e.g. as part of R.R.C reconfiguration) from a network node of the mobile communication system, wherein the LP-WUS configuration information defines parameters for monitoring for the additional LP-WUS.

[0053] The method may further comprise providing an acknowledgement of successful reception of the additional LP-WUS.

[0054] The method may further comprise monitoring for a second additional LP-WUS in a second defined slot, wherein the second defined slot is in a period when the main radio is ramping up in response to said trigger; and receiving said second additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a third payload different to the first and second payloads.

[0055] In an eighth aspect, this specification describes a method comprising: transmitting a first low-power wake-up signal, LP-WUS, to a low power radio of a UE of the mobile communication system, the first LP-WUS having a first payload; and transmitting an additional LP-WUS to the low power radio of said UE, the additional LP-WUS having a second payload different to the first payload, wherein the additional LP-WUS is sent in a defined slot before an expected wake-up time of the main radio in response to the first LP-WUS. The method may further comprise providing LP-WUS configuration information to the UE (e.g. as part of R.R.C reconfiguration), wherein the LP-WUS configuration information defines parameters for monitoring for the additional LP-WUS. The method may further comprise receiving an acknowledgement of successful reception of the additional LP-WUS at the UE. The method may further comprise transmitting a second additional LP-WUS to the low power radio of the UE, wherein said additional LP-WUS includes a third payload different to the first and second payloads.In a ninth aspect, this specification describes a method comprising: receiving a first low-power wake-up signal, LP-WUS, at a low power radio of a UE of a mobile communication system, the first LP-WUS having a first payload; triggering operation of a main radio (e.g. changing from a sleep or idle state to an active mode or state) of the UE in response to the first LP-WUS; monitoring for an additional LP-WUS in a defined slot, wherein the defined slot is in a period when the main radio is ramping up in response to said trigger; and receiving said additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload. The second payload may convey information relating to subsequent Connected Mode operations. Alternatively, or in addition, the second payload may provide information limiting PDCCH candidates for the main radio of the UE.

[0056] Alternatively, or in addition, the second payload may restrict serving cells for use for carrier aggregation. The method may comprise receiving LP-WUS configuration information (e.g. as part of R.R.C reconfiguration) from a network node of the mobile communication system, wherein the LP-WUS configuration information defines parameters for monitoring for the additional LP-WUS. The method may further comprise providing an acknowledgement of successful reception of the additional LP-WUS.

[0057] In a tenth aspect, this specification describes a method comprising: transmitting a first low-power wake-up signal, LP-WUS, to a low power radio of a UE of a mobile communication system, the first LP-WUS having a first payload; and transmitting an additional LP-WUS to the low power radio of said UE, the additional LP-WUS having a second payload different to the first payload, wherein the additional LP-WUS is sent in a defined slot when the main radio is ramping up in response to said first LP-WUS. The method may further comprise providing LP-WUS configuration information to the UE (e.g. as part of R.R.C reconfiguration), wherein the LP-WUS configuration information defines parameters for monitoring for the additional LP-WUS. The method may further comprise receiving an acknowledgement of successful reception of the additional LP-WUS at the UE.

[0058] In an eleventh aspect, this specification describes a method comprising: receiving, from a network node of the mobile communication system, a first low-power wake-up signal, LP-WUS, at a low power radio of a UE of the mobile communication system, the first LP-WUS having a first payload; triggering operation of a main radio (e.g. changing from a sleep or idle state to an active mode or state) of the UE in response to the first LP-WUS; monitoring for an additional LP-WUS in a defined slot dependent on capabilityinformation of the UE; and receiving, from the network node, an additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload. The defined slot may be in a period before an expected wake-up time of the main radio in response to said trigger. Alternatively, or in addition, the defined slot may be in a period when the main radio is ramping up in response to said trigger. The method may further comprise receiving LP-WUS configuration information (e.g. as part of R.R.C reconfiguration) from a network node of the mobile communication system, wherein the LP-WUS configuration information defines parameters for monitoring for the additional LP-WUS. The method may further comprise providing an acknowledgement of successful reception of the additional LP-WUS. The method may further comprise: monitoring for a second additional LP-WUS in a second defined slot; and receiving said second additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a third payload different to the first and second payloads.

[0059] In a twelfth aspect, this specification describes a method comprising: transmitting a first low-power wake-up signal, LP-WUS, to a UE operating in a low power mode, the first LP-WUS having a first payload; and transmitting an additional LP-WUS to the UE in a defined slot dependent on capability information of the UE, the additional LP-WUS having a payload different to the first payload. The method may further comprise receiving said capability information of the UE from said UE. The defined slot may be in a period before an expected wake-up time of the main radio in response to said trigger. Alternatively, or in addition, the defined slot may be in a period when the main radio is ramping up in response to said trigger. The method may further comprise monitoring for an acknowledgement from the UE in response to the additional LP-WUS. The method may further comprise providing a second additional LP-WUS in a second defined slot, wherein said additional LP-WUS includes a third payload different to the first and second payloads.

[0060] In the eleventh and twelfth aspects, the capability information of the UE may comprise an indication of an ability of the UE to receive an additional LP-WUS. Alternatively, or in addition, the capability information of the UE may comprise an indication of an ability of the UE to receive an additional LP-WUS in a period before an expected wake-up time of the main radio in response to said trigger. Alternatively, or in addition, the capability information of the UE may comprise an indication of an ability of the UE to receive an additional LP-WUS in a period when the main radio is ramping up in response to said trigger. Alternatively, or in addition, the capability information of the UE may comprise anindication of an ability of the UE to receive multiple instances of LP-WUS. Alternatively, or in addition, the capability information of the UE may comprise an indication of an ability of the UE to receive an additional LP-WUS on the same resources as the first LP-WUS. Alternatively, or in addition, the capability information of the UE may comprise an indication of an ability of the UE to receive an additional LP-WUS in different resources as the first LP-WUS. The skilled person will be aware of other possible capability information that may be relevant to some example embodiments.

[0061] In a thirteenth aspect, this specification describes computer program product comprising program instructions which, when executed by a computing apparatus, cause the computing apparatus to: receive a first low-power wake-up signal, LP-WUS, at a low power radio of a user equipment, UE, of a mobile communication system, the first LP-WUS having a first payload; trigger operation of a main radio of the UE in response to the first LP-WUS; monitor for an additional LP-WUS in a defined slot, wherein the defined slot is in a period before an expected wake-up time of the main radio in response to said trigger; and receive said additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload.

[0062] In a fourteenth aspect, this specification describes a computer program product comprising program instructions which, when executed by a computing apparatus, cause the computing apparatus to: transmit a first low-power wake-up signal, LP-WUS, to a low power radio of a UE of the mobile communication system, the first LP-WUS having a first payload; and transmit an additional LP-WUS to the low power radio of said UE, the additional LP-WUS having a second payload different to the first payload, wherein the additional LP-WUS is sent in a defined slot before an expected wake-up time of the main radio in response to the first LP-WUS.

[0063] In a fifteenth aspect, this specification describes a computer program product comprising program instructions which, when executed by a computing apparatus, cause the computing apparatus to: receive a first low-power wake-up signal, LP-WUS, at a low power radio of a UE of a mobile communication system, the first LP-WUS having a first payload; trigger operation of a main radio of the UE in response to the first LP-WUS; monitor for an additional LP-WUS in a defined slot, wherein the defined slot is in a period when the main radio is ramping up in response to said trigger; and receive said additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload.In a sixteenth aspect, this specification describes computer program product comprising program instructions which, when executed by a computing apparatus, cause the computing apparatus to: transmit a first low-power wake-up signal, LP-WUS, to a low power radio of a UE of a mobile communication system, the first LP-WUS having a first payload; and transmit an additional LP-WUS to the low power radio of said UE, the additional LP-WUS having a second payload different to the first payload, wherein the additional LP-WUS is sent in a defined slot when the main radio is ramping up in response to said first LP-WUS.

[0064] In a seventeenth aspect, this specification describes a computer program product comprising program instructions which, when executed by a computing apparatus, cause the computing apparatus to: receive, from a network node of a mobile communication system, a first low-power wake-up signal, LP-WUS, at a low power radio of a UE of the mobile communication system, the first LP-WUS having a first payload; trigger operation of a main radio of the UE in response to the first LP-WUS; monitor for an additional LP-WUS in a defined slot dependent on capability information of the UE; and receive, from the network node, an additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload.

[0065] In an eighteenth aspect, this specification describes a computer program product comprising program instructions which, when executed by a computing apparatus, cause the computing apparatus to: transmit a first low-power wake-up signal, LP-WUS, to a UE operating in a low power mode, the first LP-WUS having a first payload; and transmit an additional LP-WUS to the UE in a defined slot dependent on capability information of the UE, the additional LP-WUS having a payload different to the first payload. The method may further comprise receiving said capability information of the UE from said UE. The defined slot may be in a period before an expected wake-up time of the main radio in response to said trigger. Alternatively, or in addition, the defined slot may be in a period when the main radio is ramping up in response to said trigger.

[0066] In a nineteenth aspect, this specification describes computer-readable instructions which, when executed by a computing apparatus, cause the computing apparatus to perform (at least) any method as described herein (including the methods of the seventh to twelfth aspects described above).In a twentieth aspect, this specification describes a computer-readable medium (such as a non-transitory computer-readable medium) comprising program instructions stored thereon for performing (at least) any method as described herein (including the methods of the seventh to twelfth aspects described above).

[0067] In a twenty-first aspect, this specification describes a computer program product comprising program instructions which, when the program is executed by an apparatus, cause the apparatus to perform (at least) any method as described herein (including the methods of the seventh to twelfth aspects described above).

[0068] In a twenty-second aspect, this specification describes an apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, causes the apparatus to perform (at least) any method as described herein (including the methods of the seventh to twelfth aspects described above).

[0069] Brief Description of the Drawings

[0070] Example embodiments will now be described by way of non-limiting example, with reference to the accompanying drawings, in which:

[0071] FIG. 1 is a block diagram of an example system;

[0072] FIG. 2 is a block diagram of an example UE;

[0073] FIG. 3 is a flow diagram of operations showing an example use of the UE of FIG. 2;

[0074] FIG. 4 is a plot showing signals generated in an example implementation of the flow diagram of FIG. 3;

[0075] FIG. 5 is a flow diagram of operations in accordance with an example embodiment;

[0076] FIG. 6 is a flow diagram of operations in accordance with an example embodiment;

[0077] FIG. 7 is a plot showing signals generated in an example implementation of the flow diagrams of FIGS. 5 and 6 in accordance with an example embodiment;

[0078] FIG. 8 is a flow diagram of operations in accordance with an example embodiment;

[0079] FIG. 9 is a flow diagram of operations in accordance with an example embodiment;

[0080] FIG. 10 is a plot showing signals generated in an example implementation of the flow diagrams of FIGS. 8 and 9 in accordance with an example embodiment;

[0081] FIG. 11 is a signal flow diagram in accordance with an example embodiment;

[0082] FIG. 12 is a flow diagram of operations in accordance with an example embodiment;

[0083] FIG. 13 is a flow diagram of operations in accordance with an example embodiment;FIG. 14 is a plot showing signals generated in an example implementation of the flow diagrams of FIGS. 12 and 13 in accordance with an example embodiment;

[0084] FIG. 15 is a signal flow diagram in accordance with an example embodiment;

[0085] FIG. 16 illustrates an example of an apparatus; and

[0086] FIG. 17 illustrates an example of non-transitory media.

[0087] Detailed Description

[0088] Wake-up signals (WUS) are used in radio access technologies (RATs) for energy savingpurposes. Applicable RATs include, but are not limited to, long term evolution (LTE), LTE-Advanced, 5G (also called new radio (NR)) or any future RAT, such as 6G and beyond. A WUS may, for example, be transmitted by a network node to a user device (generally referred to herein as a user equipment) to wake-up the user device from a relatively low-power state (or when powered off) to a relatively high-power state. In the context of a user device which uses so-called discontinuous reception (DRX), the relatively low-power and high-power states may be referred to as the sleep and active states (or sleep and active modes) respectively. Example embodiments are applicable to alternative definitions of relatively low-power and high-power states, including sleep and awake states, or similar. The WUS may be transmitted in an event-driven manner, for example when data is ready to be transmitted by the network node to the user device, although this is not essential to all example embodiments.

[0089] FIG. 1 is a block diagram of an example system indicated generally by the reference numeral 10. The system 10 comprises a network node 12 (alternatively referred to as a network device) such as a transmission-reception point, TRP, an access point, a base station, a gNB or some similar node. The system 10 also comprises a user equipment, UE, 14 (or some other mobile communication device or terminal device). The network node 12 may (e.g. upon detection of a network-side event) transmit, over a radio access link 15, a WUS that the UE 14 is configured to detect, for example based on a WUS configuration or similar. The WUS configuration may indicate time, frequency and / or code resources over which the, or possibly multiple different, WUS(s) is or are to be received. A WUS is transmitted to wake up a main radio / terminal device of the UE 14 so that UE can be fully powered up into a state in which it can, for example, receive the physical downlink control channel (PDCCH). The WUS may be a low power WUS, LP-WUS.

[0090] FIG. 2 is a block diagram of an example UE 20 (which may be the UE 14 described above). The UE 20 comprises a low-power wake-up receiver 22 (sometimes referred to as a wake-up radio) and a main radio 24. The wake-up receiver 24 may be in analways-on state but operating with significantly less power than the main radio 26 (when the main radio is operational). The wake-up receiver 24 may, for example, use dedicated hardware for determining whether a low power wake-up signal, LP-WUS, is received at an input of the wake-up receiver 22.

[0091] FIG. 3 is a flow diagram, indicated generally by the reference numeral 30, of operations showing an example use of the UE of FIG. 2.

[0092] The flow diagram 30 starts at operation 32, where the wake-up receiver 22 monitors for a LP-WUS at the input of the wake-up receiver. At operation 34, a LP-WUS is detected by the wake-up receiver. Finally, at operation 36, the main radio 24 is triggered (in response to the detection of the LP-WUS). The operation 36 may involve the wake-up receiver 22 activating or waking-up the main radio 24 so that the main radio transitions to the relatively high-power state, e.g. from the sleep state to the active state referred to above. The main radio 24 can then communicate with the network node 12.

[0093] The LP-WUS signal detected in operation 34 is typically applicable to all serving cells such that main radio PDCCH monitoring typically occurs on all serving cells. This can result in significant power consumption, which may be unnecessary or wasteful.

[0094] Implementing alternative approaches is difficult given that the size of the LP-WUS payload is limited, as discussed further below.

[0095] FIG. 4 is a plot, indicated generally by the reference numeral 40, showing signals generated in an example implementation of the flow diagram 30 described above. The plot 40 shows LP-WUS signals 42, a power level 44 of the wake-up receiver 22 and a power level 46 of the main radio 24 over time.

[0096] The LP-WUS signal for detection in operation 34 of the flow diagram 30 may occur at any one of a plurality of Monitoring Occasions (MOs) indicated by the dotted blocks in the LP-WUS signals 42. The MOs have a periodicity that may be defined in a configuration process (e.g. defined in Radio Resource Control, RRC, signals in a manner known in the art).

[0097] In the example plot 40, a LP-WUS 43 is shown in the second of the plurality of MOs shown.

[0098] The power level 44 of the wake-up radio includes an active phase 45b that is timed to coincide with the MOs in order to monitor for an LP-WUS (thereby implementing operation 32 described above). The active phase 45b is preceded by a ramp-up phase 45a and followed by a ramp-down phase 45c. The active phase 45b shown in the plot 40 can beused to detect the LP-WUS 43, thereby implementing operation 34 described above. In response, the main radio is triggered (operation 36).

[0099] As shown in the plot 40, the triggering of the main radio results in the power level 46 of the main radio increasing to an active phase 47b. In a similar manner to the wake-up radio, the active phase 47b of the main radio is preceded by a ramp-up phase 47a and followed by a ramp-down phase 47c. During the active phase 47b, the main radio is able to communicate with the network node 12 and may, for example, monitor a physical downlink control channel, PDCCH.

[0100] The ramp-up phase 47a of the main radio may be limited by a minimum time gap allowed for the main radio to ramp up from a low power mode after a LP-WUS has been detected. The minimum time gap may be of the order of a few milliseconds.

[0101] The plot 40 may be considered to have the following states:

[0102] • State 0 in which the wake-up radio and the main radio are both off.

[0103] • State 1 in which the wake-up radio is ramping up (e.g. during ramp-up phase 45a) and the main radio is off.

[0104] • State 2 in which the wake-up radio is on and is able to detect the LP-WUS (e.g. during the active phase 45b).

[0105] • State 3 in which the main radio is ramping up (e.g. during the ramp-up phase 47a) in response to a wake-up signal from the wake-up radio.

[0106] • State 4 in which the main radio is on (e.g. during the active phase 47b).

[0107] • State 5 in which the main radio is ramping down (e.g. during phase 47c).

[0108] The process shown in the plot 40 can be repeated with the wake-up radio ramping up in time for a further MO (during which a LP-WUS may be transmitted).

[0109] The process by which the main radio 24 transitions to a high power / active state can consume significant resources (particularly power). For example, in some implementations, the LP-WUS may activate all serving cells, which may be unnecessary. The LP-WUS payload is extremely limited (e.g. 8 bits or 16 bits, although fewer or more bits could be available in some example embodiments), such that configuration information for the main radio activation process is extremely limited. Legacy solutions are available for reducing the number of serving cells to be considered (e.g. as part of carrier aggregation), but alternative solutions to manage power consumption and cell activation may be advantageous.FIG. 5 is a flow diagram showing operations 50 that may be performed by one or more example embodiments. The operations 50 may be performed by hardware, software, firmware or a combination thereof. The operations 50 may be performed by one, or respective, means, a means being any suitable means such as one or more processors or controllers in combination with computer-readable instructions provided on one or more memories. The operations 50 may be performed at the network node 12, or some similar apparatus.

[0110] A first operation 52 may comprise transmitting (from a network node) a first low-power wake-up signal, LP-WUS, to a low power radio of a UE of a mobile communication system, the first LP-WUS having a first payload.

[0111] A second operation 54 may comprise transmitting (from the network node) an additional LP-WUS to the low power radio of said UE, the additional LP-WUS having a second payload different to the first payload, wherein the additional LP-WUS is sent in a defined slot (e.g. a MO) before an expected wake-up time of the main radio in response to the first LP-WUS (as discussed in detail below). In this way, an additional (e.g. a second) LP-WUS can be sent that includes additional information not included in the payload of the first LP-WUS. The additional information can be used, for example, when switching to a active mode (e.g. to reduce power consumption).

[0112] FIG. 6 is a flow diagram showing operations 60 that may be performed by one or more example embodiments. The operations 60 may be performed by hardware, software, firmware or a combination thereof. The operations 60 may be performed by one, or respective, means, a means being any suitable means such as one or more processors or controllers in combination with computer-readable instructions provided on one or more memories. The operations 60 may be performed by the wake-up receiver 22, or some similar apparatus.

[0113] A first operation 62 may comprise receiving (at a wake-up receiver of a UE) a first low-power wake-up signal, LP-WUS, at a low power radio of the UE, the first LP-WUS having a first payload. The first LP-WUS may be transmitted in the operation 52 described above.

[0114] A second operation 64 may comprise triggering operation of a main radio of the UE (e.g. the main radio 24) in response to the first LP-WUS. The first and second operations 62, 64 may be similar to the operations 34 and 36 described above.A third operation 66 may comprise monitoring for an additional LP-WUS in a defined slot, wherein the defined slot is in a period before an expected wake-up time of the main radio in response to said trigger (i.e. before the main radio is operational).

[0115] A fourth operation 68 may comprise receiving said additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload. The additional LP-WUS may be transmitted in the operation 54 described above.

[0116] The change in the state of the main radio triggered in operation 64 (e.g. from a sleep state to an active state) may be completed after the fourth operation 68 (i.e. after the additional LP-WUS has been received).

[0117] An acknowledgement (not shown in FIG. 6) may be sent to the network after the receipt of the additional LP-WUS, for example once the main radio is fully active.

[0118] In some example embodiments, the first LP-WUS and the additional LP-WUS are received using the same time and frequency resource types. Alternatively, the first LP-WUS and the additional LP-WUS are received using different time and frequency resource types (e.g. orthogonal reception).

[0119] The second payload (transmitted in operation 54 and received in operation 68) may convey information relating to subsequent Connected Mode operations. By way of example, the second payload may provide information limiting PDCCH candidates for the main radio of the UE and / or may restrict serving cells for use for carrier aggregation.

[0120] Thus, the operations shown in the flow diagrams 50 and 60 can be used to exploit regions in time between when the receipt of a first LP-WUS and when the main radio is fully ramped up and operational, in order to send an additional WUS conveying additional information to simplify and save power with subsequent Connected Mode operations (e.g. for pruning of serving cells used for carrier aggregation, CA).

[0121] FIG. 7 is a plot, indicated generally by the reference numeral 70, showing signals generated in an example implementation of the flow diagrams of FIGS. 5 and 6 in accordance with anexample embodiment. The plot 70 shows LP-WUS 72 (similar to the LP-WUS 42 described above), a power level 74 of the wake-up receiver 22 and a power level 76 of the main radio 24 over time (similar to the power levels 44 and 46 described above respectively).

[0122] As described above, LP-WUS signals for detection by the wake-up receiver 22 may occur at any one of a plurality of Monitoring Occasions (MOs) indicated by the dotted blocks in the LP-WUS signals 72. In the example plot 70, a first LP-WUS 73a is shown in the second of the plurality of MOs shown and an additional LP-WUS 73b is shown in the third of the plurality of MOs shown. Thus, in the example shown, the first LP-WUS occurs at a Connected Mode MO preceding the MO that in which the additional LP-WUS occurs.

[0123] The power level 74 of the wake-up radio includes an active phase 75b that is timed to coincide with the second MO shown first LP-WUS 73a and an additional active phase 75c that is timed to coincide with the additional LP-WUS 73b MOs so that both the first LP-WUS and the additional LP-WUS can be received (thereby implementing operations 62 and 68 described above). The active phases 75b, 75c are preceded by a ramp-up phase 75a and followed by a ramp-down phase 75d.

[0124] As shown in the plot 70, the triggering of the main radio results in the power level 76 of the main radio increasing to an active phase 77b, with the active phase being preceded by a ramp-up phase 77a and followed by a ramp-down phase 77c. During the active phase 47b, the main radio is able to communicate with the network node 12 and may, for example, monitor a physical downlink control channel, PDCCH.

[0125] As shown in FIG. 7, the active phases 75b and 75c of the wake-up radio both occur before the start of the ramp-up phase 77a of the main radio. This may be implemented by simply continuing to monitor for LP-WUS rather than stopping monitoring at the end of operation 75b.

[0126] The plot 70 may be considered to have the following states:

[0127] • State 0 in which the wake-up radio and the main radio are both off.

[0128] • State 1 in which the wake-up radio is ramping up (e.g. during ramp-up phase 75a) and the main radio is off.

[0129] • State 2 in which the wake-up radio is on and is able to detect the first LP-WUS (e.g.

[0130] during the active phase 75b).

[0131] • State 2a in which the wake-up radio is on and is able to detect the additional LP-WUS (e.g. during the active phase 75c).• State 3 in which the main radio is ramping up (e.g. during the ramp-up phase 77a) in response to a wake-up signal from the wake-up radio.

[0132] • State 4 in which the main radio is on (e.g. during the active phase 77b).

[0133] • State 5 in which the main radio is ramping down (e.g. during phase 77c).

[0134] The process shown in the plot 70 can be repeated with the wake-up radio ramping up in time for a further MO (during which a LP-WUS may be transmitted).

[0135] FIG. 8 is a flow diagram showing operations 80 that may be performed by one or more example embodiments. The operations 80 may be performed by hardware, software, firmware or a combination thereof. The operations 80 may be performed by one, or respective, means, a means being any suitable means such as one or more processors or controllers in combination with computer-readable instructions provided on one or more memories. The operations 80 may be performed by the network node 12, or some similar apparatus.

[0136] A first operation 82 may comprise transmitting a first low-power wake-up signal, LP-WUS, to a low power radio of a UE of the mobile communication system, the first LP-WUS having a first payload.

[0137] A second operation 84 may comprise transmitting an additional LP-WUS to the low power radio of said UE, the additional LP-WUS having a second payload different to the first payload, wherein the additional LP-WUS is sent in a defined slot when the main radio is ramping up in response to said first LP-WUS. In this way, an additional (e.g. a second) LP-WUS is sent that can include additional information not included in the payload of the first LP-WUS. The additional information can be used, for example, when switching to a Connected mode (e.g. to save power).

[0138] FIG. 9 is a flow diagram showing operations 90 that may be performed by one or more example embodiments. The operations 90 may be performed by hardware, software, firmware or a combination thereof. The operations 90 may be performed by one, or respective, means, a means being any suitable means such as one or more processors or controllers in combination with computer-readable instructions provided on one or more memories. The operations 90 may be performed by the wake-up receiver 22, or some similar apparatus.11

[0139] A first operation 92 may comprise receiving (at a wake-up receiver of a UE) a first low-power wake-up signal, LP-WUS, at a low power radio of the UE, the first LP-WUS having a first payload. The first LP-WUS may be transmitted in the operation 82 described above.

[0140] A second operation 94 may comprise triggering operation of a main radio of the UE (e.g. the main radio 24) in response to the first LP-WUS. Note that the trigger operation may occur later in some example embodiments.

[0141] A third operation 96 may comprise monitoring for an additional LP-WUS in a defined slot, wherein the defined slot is in a period when the main radio is ramping up in response to said trigger.

[0142] A fourth operation 98 may comprise receiving said additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload. The additional LP-WUS may be transmitted in the operation 84 described above.

[0143] The change in the state of the main radio triggered in operation 94 (e.g. from a sleep state to an active state) may be completed after the fourth operation 98 (i.e. after the additional LP-WUS has been received).

[0144] An acknowledgement (not shown in FIG. 9) may be sent to the network after the receipt of the additional LP-WUS, for example once the main radio is fully active.

[0145] In some example embodiments, the first LP-WUS and the additional LP-WUS are received using the same time and frequency resource types. Alternatively, the first LP-WUS and the additional LP-WUS are received using different time and frequency resource types (e.g. orthogonal reception).

[0146] As discussed in detail above, the second payload (transmitted in operation 84 and received in operation 98) may convey information relating to subsequent Connected Mode operations. By way of example, the second payload may provide information limiting PDCCH candidates for the main radio of the UE and / or may restrict serving cellsfor use for carrier aggregation.

[0147] Thus, the operations shown in the flow diagrams 80 and 90 can be used to exploit regions in time between when the receipt of a first LP-WUS and when the main radio is ramping up, but not yet fully ramped up and operational, in order to send an additional WUS conveying additional information to simplify and save power with subsequent Connected Mode operations (e.g. for pruning of serving cells used for carrier aggregation, CA).

[0148] FIG. 10 is a plot, indicated generally by the reference numeral 100, showing signals generated in an example implementation of the flow diagrams of FIGS. 8 and 9 in accordance with an example embodiment. The plot 100 shows LP-WUS 102 (similar to the LP-WUS 42 and 72 described above), a power level 104 of the wake-up receiver 22 and a power level 106 of the main radio 24 over time (similar to the wake-up receiver power levels 44, 74 and the main radio power levels 46, 76 described above).

[0149] As described above, LP-WUS signals for detection by the wake-up receiver 22 may occur at any one of a plurality of Monitoring Occasions (MOs) indicated by the dotted blocks in the LP-WUS signals 102. In the example plot 100, a first LP-WUS 103a is shown in the second of the plurality of MOs shown and an additional LP-WUS 73b is shown in the fourth of the plurality of MOs shown. Thus, in the example shown, the first LP-WUS is received at a Connected Mode MO before (but not immediately preceding) the MO that in which the additional LP-WUS is received.

[0150] The power level 104 of the wake-up radio includes an active phase 105b that is timed to coincide with the second MO shown first LP-WUS 103a and an additional active phase 105c that is timed to coincide with the additional LP-WUS 103b MOs so that both the first LP-WUS and the additional LP-WUS can be received (thereby implementing operations 92 and 98 described above). The active phases 105b, 105c are preceded by a ramp-up phase 105a and followed by a ramp-down phase 105c.

[0151] During the period between the active phase 105b and the additional active phase 105c, the power level 104 of the wake-up radio may remain high. This is not essential to all example embodiments; for example, the wake-up radio may ramp down and back up again between the active phases 105b and 105c.As shown in the plot 100, the triggering of the main radio results in the power level 106 of the main radio increasing to an active phase 107b, with the active phase being preceded by a ramp-up phase 107a and followed by a ramp-down phase 107c. During the active phase 107b, the main radio is able to communicate with the network node 12 and may, for example, monitor a physical downlink control channel, PDCCH.

[0152] The plot 100 may be considered to have the following states:

[0153] • State 0 in which the wake-up radio and the main radio are both off.

[0154] • State 1 in which the wake-up radio is ramping up (e.g. during ramp-up phase 105a) and the main radio is off.

[0155] • State 2 in which the wake-up radio is on and is able to detect the first LP-WUS (e.g.

[0156] during the active phase 105b).

[0157] • State 3 in which the main radio is ramping up (e.g. during the ramp-up phase 107a) in response to a wake-up signal from the wake-up radio and in which the wake-up radio is able to detect the additional LP-WUS.

[0158] • State 4 in which the main radio is on (e.g. during the active phase 107b).

[0159] • State 5 in which the main radio is ramping down (e.g. during phase 107c).

[0160] The process shown in the plot 100 can be repeated with the wake-up radio ramping up in time for a further MO (during which a LP-WUS may be transmitted).

[0161] FIG. 11 is a signal flow diagram, indicated generally by the reference numeral 110, in accordance with an example embodiment. The signal flow diagram 110 shows messages transferred between, and actions taken at, a network node 111 and a UE 112 (such as the network node 12 and the UE 14 described above). The UE 112 includes a wake-up receiver and a main radio, as discussed in detail above.

[0162] The flow diagram 110 may start with configuration information 114 being shared between the network node 111 and the UE 112 (e.g. as part of an R.R.C reconfiguration process). For example, the UE 112 may receive configuration information from a RAN regarding the use of additional LP-WUS in accordance with the example embodiments described herein. The configuration information may define parameters for monitoring for the additional LP-WUS (such as an indication of slots in which LP-WUSs may be sent).

[0163] The network node 111 transmits a first LP-WUS 115 to the UE 112, the first LP-WUS having a first payload. In response to the first LP-WUS, the UE 122 triggers 116 the main radio of the UE.The network node 111 transmits one of more additional LP-WUS 117 (each having a further payload) to the UE 112. Slots in which the additional LP-WUS(s) are transmitted may be defined in the configuration information 114. Example slots in which the additional LP-WUS(s) may be sent to the UE 112 are discussed elsewhere in this document; each of those embodiments may be used in the flow diagram 110. The UE may be change from a sleep state to an active state in response to the trigger; that change of state may be completed (and possibly started) after the receipt of the one or more additional LP-WUS 117.

[0164] The main radio of the UE may be configured 118 based, at least in part on the information provided in the payloads (e.g. a second payload). As discussed above, the second payload may convey information relating to subsequent Connected Mode operations of the main radio. By way of example, the second payload may provide information limiting PDCCH candidates for the main radio of the UE and / or may restrict serving cells for use for carrier aggregation.

[0165] The UE 112 may provide feedback (e.g. an acknowledgement) to the network node 111 to indicate successful reception of the or each additional LP-WUS (e.g. in an active state), as indicated schematically by the message 119. The acknowledgement message 119 may be sent after the main radio is fully operational (although there may, in some example embodiments, be a mechanism to send an acknowledgement earlier, e.g. on receipt of the respective additional LP-WUS).

[0166] FIG. 12 is a flow diagram showing operations 120 that may be performed by one or more example embodiments. The operations 120 may be performed by hardware, software, firmware or a combination thereof. The operations 120 may be performed by one, or respective, means, a means being any suitable means such as one or more processors or controllers in combination with computer-readable instructions provided on one or more memories. The operations 120 may be performed by the network node 12, or some similar apparatus.

[0167] A first operation 122 may comprise transmitting a first low-power wake-up signal, LP-WUS, to a low power radio of a UE of the mobile communication system, the first LP-WUS having a first payload.

[0168] A second operation 124 may comprise transmitting (from the network node) a first additional LP-WUS to the low power radio of said UE, the first additional LP-WUS having a second payload different to the first payload, wherein the additional LP-WUS is sent ina defined slot (e.g. a MO) before an expected wake-up time of the main radio in response to the first LP-WUS.

[0169] A third operation 126 may comprise transmitting a second additional LP-WUS to the low power radio of said UE, the second additional LP-WUS having a third payload different to the first and second payloads, wherein the second additional LP-WUS is sent in a defined slot when the main radio is ramping up in response to said first LP-WUS.

[0170] In this way, the additional LP-WUSs can include additional information not included in the payload of the first LP-WUS. The additional information can be used, for example, when switching from a sleep state to an active state (e.g. to save power).

[0171] FIG. 13 is a flow diagram showing operations 130 that may be performed by one or more example embodiments. The operations 130 may be performed by hardware, software, firmware or a combination thereof. The operations 130 may be performed by one, or respective, means, a means being any suitable means such as one or more processors or controllers in combination with computer-readable instructions provided on one or more memories. The operations 130 may be performed by the wake-up receiver 22, or some similar apparatus.

[0172] A first operation 131 may comprise receiving (at a wake-up receiver or a UE) a first low-power wake-up signal, LP-WUS, at a low power radio of the UE, the first LP-WUS having a first payload. The first LP-WUS may be transmitted in the operation 122 described above.

[0173] A second operation 132 may comprise triggering operation of a main radio of the UE (e.g. the main radio 24) in response to the first LP-WUS. Note that, in some example embodiments, the triggering of the main radio may occur later (e.g. after receipt of one or more additional LP-WUSs).

[0174] A third operation 133 may comprise monitoring for a first additional LP-WUS in a defined slot, wherein the defined slot is in a period before an expected wake-up time of the main radio in response to said trigger (i.e. before the main radio is operational).

[0175] A fourth operation 134 may comprise receiving the first additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload. The additional LP-WUS may be transmittedin the operation 124 described above.

[0176] A fifth operation 135 may comprise monitoring for a second additional LP-WUS in a defined slot, wherein the defined slot is in a period when the main radio is ramping up in response to said trigger.

[0177] A sixth operation 136 may comprise receiving said second additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a third payload different to the first and second payloads. The second additional LP-WUS may be transmitted in the operation 126 described above.

[0178] The change in the state of the main radio triggered in operation 132 (e.g. from a sleep state to an active state) may be completed after the sixth operation 136 (i.e. after the second additional LP-WUS has been received).

[0179] An acknowledgement (not shown in FIG. 13) may be sent to the network after the receipt of the second additional LP-WUS, for example once the main radio is fully active.

[0180] In some example embodiments, the first LP-WUS and the first and second additional LP-WUSs are received using the same time and frequency resource types. Alternatively, one or more the LP-WUSs may be received using different time and frequency resource types (e.g. orthogonal reception).

[0181] The second and third payloads may convey information relating to subsequent Connected Mode operations. By way of example, the second and third payload may provide information limiting PDCCH candidates for the main radio of the UE and / or may restrict serving cells for use for carrier aggregation.

[0182] The second and third payloads may convey information relating to subsequent Connected Mode operations. By way of example, the second and third payload may provide information limiting PDCCH candidates for the main radio of the UE and / or may restrict serving cells for use for carrier aggregation.

[0183] Thus, the operations shown in the flow diagrams 120 and 130 can be used to exploit regions in time between when the receipt of a first LP-WUS and when the main radioramped-up and operational, in order to send multiple additional WUS conveying additional information to simplify and save power with subsequent Connected Mode operations (e.g. for pruning of serving cells used for carrier aggregation, CA).

[0184] It should be noted that whilst two additional LP-WUSs are described with reference to the flow diagrams 120 and 130, the principles described herein may be extended to apply to further additional LP-WUSs (i.e. more than two).

[0185] FIG. 14 is a plot, indicated generally by the reference numeral 140, showing signals generated in an example implementation of the flow diagrams of FIGS. 12 and 13 in accordance with an example embodiment. The plot 140 shows LP-WUS 142 (similar to the LP-WUS 42, 72 and 102 described above), a power level 144 of the wake-up receiver 22 and a power level 146 of the main radio 24 over time (similar to the wake-up receiver power levels 44, 74 and 104 and the main radio power levels 46, 76 and 106 described above).

[0186] As described above, LP-WUS signals for detection by the wake-up receiver 22 may occur at any one of a plurality of Monitoring Occasions (MOs) indicated by the dotted blocks in the LP-WUS signals 102. In the example plot 140, a first LP-WUS 143a is shown in the second of the plurality of MOs shown, a first additional LP-WUS 143b is shown in the third of the plurality of MOs shown and a second additional LP-WUS 143c is shown in the fourth of the plurality of MOs shown. Thus, in the example shown, the first LP-WUS is received at a Connected Mode MO preceding the MOs in which the first and second additional LP-WUS are received. The LP-WUSs 143a to 143c are shown in succeeding Mos, but this this is not essential to all example embodiments as there may be one or more unused MOs inbetween.

[0187] The power level 144 of the wake-up radio includes an active phase 145b that is timed to coincide with the second MO shown first LP-WUS 143a, a first additional active phase 145c that is timed to coincide with the first additional LP-WUS 143b MOs, and a second additional active phase 145d that is timed to coincide with the second additional LP-WUS 143c MOs, so that the first LP-WUS and the first and second additional LP-WUSs can be received (thereby implementing operations 131, 134 and 136 described above). The active phases 145b, 145c and 145d are preceded by a ramp-up phase 145a and followed by a ramp-down phase 145e. It should be noted that whilst the active phases 145b, 145c and 145d are shown as contiguous active phase, this is not essential to all exampleembodiments; for example one or more gaps between the active phases may be provided in some example embodiments.

[0188] As shown in the plot 140, the triggering of the main radio results in the power level 146 of the main radio increasing to an active phase 147b, with the active phase being preceded by a ramp-up phase 147a and followed by a ramp-down phase 147c. During the active phase 147b, the main radio is able to communicate with the network node 12 and may, for example, monitor a physical downlink control channel, PDCCH.

[0189] The plot 140 may be considered to have the following states:

[0190] • State 0 in which the wake-up radio and the main radio are both off.

[0191] • State 1 in which the wake-up radio is ramping up (e.g. during ramp-up phase 145a) and the main radio is off.

[0192] • State 2 in which the wake-up radio is on and is able to detect the first LP-WUS (e.g.

[0193] during the active phase 145b).

[0194] • State 2a in which the wake-up radio is on and is able to detect the first additional LP- WUS (e.g. during the active phase 145c).

[0195] • State 3 in which the main radio is ramping up (e.g. during the ramp-up phase 147a) in response to a wake-up signal from the wake-up radio and in which the wake-up radio is able to detect the second additional LP-WUS.

[0196] • State 4 in which the main radio is on (e.g. during the active phase 147b).

[0197] • State 5 in which the main radio is ramping down (e.g. during phase 147c).

[0198] The process shown in the plot 140 can be repeated with the wake-up radio ramping up in time for a further MO (during which a LP-WUS may be transmitted).

[0199] FIG. 15 is a signal flow diagram, indicated generally by the reference numeral 150, in accordance with an example embodiment. The signal flow diagram shows messages transferred between, and actions taken at, a network node 151 (such as the network node 12 or 111 described above) and a UE 152 (such as the UE 14 or 112 described above). The UE 152 includes a wake-up receiver and a main radio, as discussed in detail above.

[0200] The flow diagram 150 may start with UE capability information 153 being provided by the UE 152 to the network 151. As discussed below, LP-WUS may be provided to the UE dependent, at least in part, on capability information of the UE 152.The UE capability information (which may be provided to the network node 151 with the UE capability information 153 or may be made available to the network node 151 in some other way) may include one of more of the following :

[0201] • An ability of the UE to receive an additional LP-WUS;

[0202] • An ability of the UE to receive an additional LP-WUS in a period before an expected wake-up time of the main radio in response to a trigger (e.g. as discussed above with reference to FIGS. 5-7);

[0203] • An ability of the UE to receive an additional LP-WUS in a period when the main radio is ramping up in response to a trigger (e.g. as discussed above with reference to FIGS 8-10);

[0204] • An ability of the UE to receive multiple instances of LP-WUS (e.g. as described above with reference to FIGS 12-14);

[0205] • An ability of the UE to receive an additional LP-WUS on the same resources (e.g.

[0206] the same frequency, carrier or bandwidth) as a first LP-WUS;

[0207] • An ability of the UE to receive an additional LP-WUS in different resources (e.g. different frequency, carrier or bandwidth) as a first LP-WUS.

[0208] The network node 151 may provide configuration information 154 to the UE 152 (e.g. as part of an R.R.C reconfiguration process). For example, the UE 152 may receive configuration information from a RAN regarding the use of additional LP-WUS in accordance with the example embodiments described herein. The configuration information may define parameters for monitoring for the additional LP-WUS (e.g. defining slots in which LP-WUSs may be provided). The configuration information 154 may be generated (e.g. at the network node 151) based, at least in part, on the UE capability information. By way of example, the network node 151 may decide which of the available UE capability information to make use of when providing LP-WUS(s) to the UE 152.

[0209] The network node 151 may transmit a first LP-WUS 155 to the UE 152, the first LP-WUS having a first payload. In response to the first LP-WUS, the UE 122 triggers 156 the main radio of the UE. Note that, in some example embodiments, the triggering of the main radio may occur later (e.g. after receipt of one or more additional LP-WUSs).

[0210] The network node 151 may transmit one of more additional LP-WUS 157 (each having a further payload different to the first payload). The further payload(s) may convey information relating to subsequent Connected mode operations, as discussed in detail above. The UE may be change from a sleep state to an active state in response to the trigger; that change of state may be completed (and possibly started) after the receipt of the one or more additional LP-WUS 157.The or each additional LP-WUS is transmitted in a defined slot that may be set depending on capability information of the UE. Thus, the UE 152 monitors for an additional LP-WUS in a defined slot(s). The defined slot(s) may be communicated in the configuration information 154.

[0211] As discussed above, the defined slot may be in a period before an expected wake-up time of the main radio in response to said trigger or in a period when the main radio is ramping up in response to said trigger.

[0212] The defined slot may be one of a plurality of Connected Mode Monitoring Occasions of the mobile communication system, said Monitoring Occasions having a periodicity and an offset. For example, the first LP-WUS 155 may be received at a Connected Mode Monitoring Occasion preceding the defined slot. The first and additional LP-WUSs may be received on MOs that are orthogonal.

[0213] The main radio of the UE may be configured 158 based, at least in part on the information provided in the payloads (e.g. a second payload). As discussed above, the second payload may convey information relating to subsequent Connected Mode operations of the main radio. By way of example, the second payload may provide information limiting PDCCH candidates for the main radio of the UE and / or may restrict serving cells for use for carrier aggregation.

[0214] The UE 152 may provide feedback (e.g. an acknowledgement) to the network node 151 to indicated successful reception of the or each additional LP-WUS (e.g. in an active state), as indicated schematically by the message 159. The network node may be configured to monitor for an acknowledgement from the UE in response to an additional LP-WUS.

[0215] The UE may be change from a sleep state to an active state in response to the trigger; that change of state may be completed (and possibly started) after the receipt of the one or more additional LP-WUS 157.

[0216] In the various embodiments described herein, additional LP-WUSs may be used to support power saving (e.g. in connected mode) in a variety of ways. These may include one or more of:• Identifying specific PDCCH I SSSG monitoring occasions. If missed, the UE may assume a worse case configuration, e.g. monitoring all PDCCH occasions.

[0217] • Limiting the PDCCH candidates that the main radio monitors for. For example, every second candidate, every third candidate, or some other combination of candidates could be considered, thereby reducing the power consumed when considering every candidate.

[0218] • Providing SCell Dormancy indication information (e.g. identifying specific cells to be used). If missed, the UE may assume a worse case configuration, e.g. monitoring all SCells.

[0219] • Limiting PDCCH skipping operations

[0220] • Shortening or lengthening an inactivity timer

[0221] • Identifying narrower bandwidth or simpler search space for UE to use

[0222] • Identifying specific subsets of serving cells for carrier aggregation usage

[0223] • Modifying aspects of the WUS for the next time the WUS is used, e.g. the modulation or resources used.

[0224] • Providing BWP switching information. Early BWP switching (e.g. before DCI / RRC indication) to narrow BWP (when appropriate) could improve MR performance.

[0225] The skilled person will be aware of other potential uses of the LP-WUSs.

[0226] Example Apparatus

[0227] FIG. 16 shows an apparatus according to some example embodiments. The apparatus may be configured to perform the operations described herein, for example operations described with reference to any disclosed process. The apparatus comprises at least one processor 312 and at least one memory 314 directly or closely connected to the processor. The memory 314 includes at least one random access memory (RAM) and at least one read-only memory (ROM). Computer program code (software) is stored in the memory 314 (typically in ROM). The apparatus may be connected to a transmitter (TX) and a receiver (RX). The apparatus may, optionally, be connected with a user interface (UI) 318 for instructing the apparatus and / or for outputting data. The at least one processor 312, with the at least one memory 314 and the computer program code instruction 315 are arranged to cause the apparatus to at least perform at least the method according to any preceding process, for example as disclosed in relation to the flow diagrams and message sequences of FIGs. 3, 5, 6, 8, 9, 11, 12, 13 and 15 and related features thereof.

[0228] FIG. 17 shows a non-transitory media 365 according to some embodiments. The non-transitory media 254 is a computer readable storage medium. It may be e.g. a CD, aDVD, a USB stick, a blue ray disk, etc. The non-transitory media 365 stores computer program code, causing an apparatus to perform the method of any preceding process for example as disclosed in relation to the flow diagrams and related features thereof.

[0229] Names of network elements, protocols, and methods are based on current standards. In other versions or other technologies, the names of these network elements and / or protocols and / or methods may be different, as long as they provide a corresponding functionality. For example, embodiments may be deployed in 2G / 3G / 4G / 5G networks and further generations of 3GPP but also in non-3GPP radio networks such as WiFi.

[0230] A memory may be volatile or non-volatile. It may be e.g. a RAM, a SRAM, a flash memory, a FPGA block ram, a DCD, a CD, a USB stick, and a blue ray disk.

[0231] If not otherwise stated or otherwise made clear from the context, the statement that two entities are different means that they perform different functions. It does not necessarily mean that they are based on different hardware. That is, each of the entities described in the present description may be based on a different hardware, or some or all of the entities may be based on the same hardware. It does not necessarily mean that they are based on different software. That is, each of the entities described in the present description may be based on different software, or some or all of the entities may be based on the same software. Each of the entities described in the present description may be embodied in the cloud.

[0232] Implementations of any of the above described blocks, apparatuses, systems, techniques or methods include, as non-limiting examples, implementations as hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. Some embodiments may be implemented in the cloud.

[0233] It is to be understood that what is described above is what is presently considered the preferred embodiments. However, it should be noted that the description of the preferred embodiments is given by way of example only and that various modifications may be made without departing from the scope as defined by the appended claims.

Claims

34CLAIMS1. A user equipment, UE, of a mobile communication system, the UE comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the UE at least to:receive, from a network node of the mobile communication system, a first low-power wake-up signal, LP-WUS, at a low power radio of the UE, the first LP-WUS having a first payload;trigger operation of a main radio of the UE in response to the first LP-WUS; monitor for an additional LP-WUS in a defined slot dependent on capability information of the UE; andreceive, from the network node, an additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload.

2. A UE as claimed in claim 1, wherein the instructions, when executed by the at least one processor, further cause the UE at least to:provide the capability information of the UE to the network node.

3. A UE as claimed in claim 1 or claim 2, wherein the capability information of the UE comprises one or more of:an indication of an ability of the UE to receive an additional LP-WUS;an indication of an ability of the UE to receive an additional LP-WUS in a period before an expected wake-up time of the main radio in response to said trigger;an indication of an ability of the UE to receive an additional LP-WUS in a period when the main radio is ramping up in response to said trigger;an indication of an ability of the UE to receive multiple instances of LP-WUS; an indication of an ability of the UE to receive an additional LP-WUS on the same resources as the first LP-WUS; and35an indication of an ability of the UE to receive an additional LP-WUS in different resources as the first LP-WUS.

4. A UE as claimed in any one of claims 1 to 3, wherein the defined slot is in a period before an expected wake-up time of the main radio in response to said trigger.

5. A UE as claimed in any one of claims 1 to 3, wherein the defined slot is in a period when the main radio is ramping up in response to said trigger.

6. A UE as claimed in any one of the preceding claims, wherein the second payload conveys information relating to subsequent Connected Mode operations.

7. A UE as claimed in any one of the preceding claims, wherein the instructions, when executed by the at least one processor, further cause the UE at least to:receive LP-WUS configuration information from a network node of the mobile communication system, wherein the LP-WUS configuration information defines parameters for monitoring for the additional LP-WUS.

8. A UE as claimed in any one of the preceding claims, wherein the defined slot is one of a plurality of Connected Mode Monitoring Occasions of the mobile communication system, said Monitoring Occasions having a periodicity and an offset.

9. A UE as claimed in any one of the preceding claims, wherein the first LP-WUS is received at a Connected Mode Monitoring Occasion preceding the defined slot.

10. A UE as claimed in any one of the preceding claims, wherein the first LP-WUS and the additional LP-WUS are received using the same time and frequency resource types.

11. A UE as claimed in any one of claims 1 to 9, wherein the first LP-WUS and the additional LP-WUS are received using different time and frequency resource types.

12. A UE as claimed in any one of the preceding claims, wherein the instructions, when executed by the at least one processor, further cause the UE at least to:provide an acknowledgement of successful reception of the additional LP-WUS.

13. A UE as claimed in any one of the preceding claims, wherein the instructions, when executed by the at least one processor, further cause the UE at least to:monitor for a second additional LP-WUS in a second defined slot; andreceive said second additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a third payload different to the first and second payloads.

14. A method comprising:receiving, from a network node of the mobile communication system, a first low-power wake-up signal, LP-WUS, at a low power radio of a UE of the mobile communication system, the first LP-WUS having a first payload;triggering operation of a main radio of the UE in response to the first LP-WUS; monitoring for an additional LP-WUS in a defined slot dependent on capability information of the UE; andreceiving, from the network node, an additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload.

15. A method as claimed in claim 14, further comprising:providing the capability information of the UE to the network node.

16. A method comprising:transmitting a first low-power wake-up signal, LP-WUS, to a UE operating in a low power mode, the first LP-WUS having a first payload; andtransmitting an additional LP-WUS to the UE in a defined slot dependent on capability information of the UE, the additional LP-WUS having a payload different to the first payload.

17. A method as claimed in any one of claims 14 to 16, wherein the capability information of the UE comprises one or more of:an indication of an ability of the UE to receive an additional LP-WUS;an indication of an ability of the UE to receive an additional LP-WUS in a period before an expected wake-up time of the main radio in response to said trigger;an indication of an ability of the UE to receive an additional LP-WUS in a period when the main radio is ramping up in response to said trigger;an indication of an ability of the UE to receive multiple instances of LP-WUS; an indication of an ability of the UE to receive an additional LP-WUS on the same resources as the first LP-WUS; andan indication of an ability of the UE to receive an additional LP-WUS in different resources as the first LP-WUS.

18. A computer program product comprising program instructions which, when executed by a computing apparatus, cause the computing apparatus to:receive, from a network node of a mobile communication system, a first low-power wake-up signal, LP-WUS, at a low power radio of a UE of the mobile communication system, the first LP-WUS having a first payload;trigger operation of a main radio of the UE in response to the first LP-WUS; monitor for an additional LP-WUS in a defined slot dependent on capability information of the UE; andreceive, from the network node, an additional LP-WUS at the low power radio of the UE in the defined slot, wherein said additional LP-WUS includes a second payload different to the first payload.

Images