WO2025101103A1

WO2025101103A1 - Method and apparatus for reference signal transmission

Info

Publication number: WO2025101103A1
Application number: PCT/SE2024/050931
Authority: WO
Inventors: Ali Nader; Pål FRENGER; Andres Reial; Jonas Bengtsson; Ryan PADERNA; Xu Zhu; Zhixun Tang; Helka-Liina MÄÄTTÄNEN
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2023-11-10
Filing date: 2024-11-01
Publication date: 2025-05-15
Anticipated expiration: 2026-05-10

Abstract

Various embodiments of the present disclosure provide a method for reference signal transmission. The method which may be performed by a terminal device comprises: receiving a first set of reference signals for a first type of operation transmitted by a network node at a first transmission rate, and a second set of reference signals for a second type of operation transmitted by the network node at a second transmission rate higher than the first transmission rata. In accordance with an exemplary embodiment, the method further comprises decoding the first reference signal and the second reference signal.

Description

METHOD AND APPARATUS FOR REFERENCE SIGNAL TRANSMISSION

FIELD OF THE INVENTION

[0001] The present disclosure generally relates to communication networks, and more specifically, to a method and apparatus for reference signal transmission.

BACKGROUND

[0002] This section introduces aspects that may facilitate a better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

[0003] With the rapid development of networking and communication technologies, wireless communication networks such as long-term evolution (LTE)/fourth generation (4G) network and new radio (NR)/fifth generation (5G) network are expected to achieve high traffic capacity and energy efficiency. In order to connect to a communication network to obtain a specific service, a terminal device such as a user equipment (UE) may need to receive some system information (SI) and reference signals (e.g., synchronization signals, etc.) as well as control information indicating the related radio resource configuration from a network node. Considering the diversity of network deployments and application scenarios, scheduling and transmission configurations of reference signals for various operation modes (e.g., IDLE/INACTIVE mode, CONNECTED mode, etc.) may become more challenging.

SUMMARY

[0004] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0005] Current network deployments typically configure a fixed transmission rate for reference signals (e.g., synchronization signal and physical broadcast channel blocks, also known as SS/PBCH blocks or SSBs for short) irrespective of UEs’ states or operations. For example, according to the existing solutions, all SSBs are constantly provided at the same transmission rate (e.g., every 20ms) to satisfy the most demanding scenario (e.g., for CONNECTED mode UEs, etc.). As the number of SSB transmissions increases, the SSB transmissions at such a high rate will increase power consumption and introduce excessive interference. Therefore, it may be desirable to implement reference signal transmission in a more efficient way.

[0006] Various exemplary embodiments of the present disclosure propose a solution for reference signal transmission, which may enable reference signals (e.g., synchronization signals such as SSBs, etc.) to be provided at a low transmission rate (e.g., every 160ms, 320ms, ..., 960ms, etc.), e.g., for the least demanding scenario such as for IDLE/INACTIVE mode UEs, while providing extra reference signals when necessary, e.g., for the more demanding scenario such as for CONNECTED mode UEs.

[0007] According to a first aspect of the present disclosure, there is provided a method performed by a terminal device. The method comprises: receiving a first reference signal for a first type of operations transmitted by a network node at a first transmission rate lower than a threshold, and/or a second reference signal for a second type of operations transmitted, in response to one or more triggers, by the network node at a second transmission rate. In accordance with an exemplary embodiment, the method further comprises: decoding the first reference signal and/or the second reference signal.

[0008] In accordance with an exemplary embodiment, the threshold may be configurable based at least in part on operation demands and/or network deployments. In an embodiment, the threshold may be equal to or less than a reference signal transmission rate (e.g., every 20ms, etc.) configured for the most demanding scenario and/or operations in connected mode.

[0009] In accordance with an exemplary embodiment, the first reference signal may be an SSB signal. In accordance with another exemplary embodiment, the second reference signal may be an SSB based signal.

[0010] In accordance with an exemplary embodiment, the first reference signal may include information indicating that a first set of reference signals for the first type of operations are transmitted by the network node at the first transmission rate. The first reference signal may be one of the first set of the reference signals.

[0011] In accordance with an exemplary embodiment, the second reference signal may be different from the first reference signal by one or more of: a signal transmission rate, a signal provision period, a signal periodicity, an SSB measurement timing configuration (SMTC) periodicity, a resource configuration, a scheduling configuration, a signal format, and signal contents.

[0012] In accordance with an exemplary embodiment, the second reference signal may have a periodicity based at least in part on a discontinuous reception (DRX) cycle.

[0013] In accordance with an exemplary embodiment, the second reference signal may include an indicator which instructs a specified type of terminal devices not to camp on a cell served by the network node.

[0014] In accordance with an exemplary embodiment, the second reference signal may be one of a second set of reference signals for the second type of operations which may be transmitted by the network node at the second transmission rate. In accordance with another exemplary embodiment, the second transmission rate may be configurable based at least in part on types, services, mobility patterns and/or link quality of one or more terminal devices served by the network node.

[0015] In accordance with an exemplary embodiment, the method according to the first aspect of the present disclosure may further comprise: receiving, from the network node and/or one or more other network nodes, information indicating whether the second set of the reference signals are transmitted by the network node.

[0016] In accordance with an exemplary embodiment, the second set of the reference signals may have different characteristics, respectively. In an embodiment, the different characteristics may comprise one or more of: scheduling configurations, resource configurations, signal contents, and signal types.

[0017] In accordance with an exemplary embodiment, a number and/or a type of the second set of the reference signals may be configurable based at least in part on the number of the one or more triggers.

[0018] In accordance with an exemplary embodiment, the one or more triggers may comprise one or more of: a presence of at least one terminal device in a coverage area of the network node, where the at least one terminal device may be performing or to perform one or more operations of the second type of operations; establishing a connection for the at least one terminal device; requesting or initiating a service for the at least one terminal device; a change of movement pattern of the at least one terminal device; a request for the second reference signal from the at least one terminal device or at least another network node; a timing trigger of the second reference signal during a predefined time period; and a number of failed connection attempts of the at least one terminal device being equal to or higher than a predefined value.

[0019] In accordance with an exemplary embodiment, the method according to the first aspect of the present disclosure may further comprise: transmitting a request for the second reference signal to the network node.

[0020] In accordance with an exemplary embodiment, the first type of operations may include one or more of the following idle mode operations: serving cell evaluation, cell selection, cell re-selection, and paging.

[0021] In accordance with an exemplary embodiment, the second type of operations may include one or more of the following operations: an operation for connected mode mobility, an operation for connected mode link maintenance, an operation for fast secondary cell activation in connected mode, an operation for idle mode mobility at a speed higher than a predefined value, and an operation for an idle mode service involving broadcast or multi-cast transmissions.

[0022] In accordance with an exemplary embodiment, the method according to the first aspect of the present disclosure may further comprise obtaining configuration information. In an embodiment, the configuration information may indicate: whether different sets of reference signals for different types of operations are transmitted by the network node and/or one or more other network nodes, and/or whether a set of reference signals are transmitted by the network node and/or the one or more other network nodes at a lower transmission rate than the threshold. In an embodiment, the configuration information may be preconfigured for the terminal device. Alternatively or additionally, the configuration information may be received from the network node or at least another network node.

[0023] In accordance with an exemplary embodiment, the configuration information may further indicate transmission rates and/or signal characteristics of the different sets of reference signals.

[0024] According to a second aspect of the present disclosure, there is provided an apparatus which may be implemented as a terminal device. The apparatus may comprise one or more processors and one or more memories storing computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the first aspect of the present disclosure.

[0025] According to a third aspect of the present disclosure, there is provided a computer-readable medium having computer program codes embodied thereon which, when executed on a computer, cause the computer to perform any step of the method according to the first aspect of the present disclosure.

[0026] According to a fourth aspect of the present disclosure, there is provided an apparatus which may be implemented as a terminal device. The apparatus may comprise a receiving unit and a decoding unit. In accordance with some exemplary embodiments, the receiving unit may be operable to carry out at least the receiving step of the method according to the first aspect of the present disclosure. The decoding unit may be operable to carry out at least the decoding step of the method according to the first aspect of the present disclosure.

[0027] According to a fifth aspect of the present disclosure, there is provided a method performed by a network node. The method comprises: determining whether to transmit a first reference signal for a first type of operations at a first transmission rate lower than a threshold, and/or transmit, in response to one or more triggers, a second reference signal for a second type of operations at a second transmission rate. In accordance with an exemplary embodiment, the method further comprises: transmitting the first reference signal and/or the second reference signal to one or more terminal devices, according to a result of the determination.

[0028] In accordance with an exemplary embodiment, the first reference signal according to the fifth aspect of the present disclosure may correspond to the first reference signal according to the first aspect of the present disclosure. Thus, the first reference signal according to the first and fifth aspects of the present disclosure may have the same or similar contents and/or feature elements. In an embodiment, the first reference signal may be one of a first set of reference signals for the first type of operations which may be transmitted by the network node at the first transmission rate. Correspondingly, the first set of the reference signals according to the first and fifth aspects of the present disclosure may have the same or similar contents and/or feature elements.

[0029] In accordance with an exemplary embodiment, the second reference signal according to the fifth aspect of the present disclosure may correspond to the second reference signal according to the first aspect of the present disclosure. Thus, the second reference signal according to the first and fifth aspects of the present disclosure may have the same or similar contents and/or feature elements. In an embodiment, the second reference signal may be one of a second set of reference signals for the second type of operations which may be transmitted by the network node at the second transmission rate. Correspondingly, the second set of the reference signals according to the first and fifth aspects of the present disclosure may have the same or similar contents and/or feature elements. [0030] In accordance with an exemplary embodiment, the method according to the fifth aspect of the present disclosure may further comprise: transmitting, to the one or more terminal devices, information indicating whether the second set of the reference signals are transmitted by the network node.

[0031] In accordance with an exemplary embodiment, the method according to the fifth aspect of the present disclosure may further comprise: receiving a request for the second reference signal from at least one terminal device and/or at least another network node.

[0032] In accordance with an exemplary embodiment, the method according to the fifth aspect of the present disclosure may further comprise: transmitting configuration information to the one or more terminal devices. In an embodiment, the configuration information may indicate: whether different sets of reference signals for different types of operations are transmitted by the network node and/or one or more other network nodes, and/or whether a set of reference signals are transmitted by the network node and/or the one or more other network nodes at a lower transmission rate than the threshold.

[0033] In accordance with an exemplary embodiment, the configuration information may further indicate transmission rates and/or signal characteristics of the different sets of reference signals.

[0034] According to a sixth aspect of the present disclosure, there is provided an apparatus which may be implemented as a network node. The apparatus may comprise one or more processors and one or more memories storing computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the fifth aspect of the present disclosure. [0035] According to a seventh aspect of the present disclosure, there is provided a computer-readable medium having computer program codes embodied thereon which, when executed on a computer, cause the computer to perform any step of the method according to the fifth aspect of the present disclosure.

[0036] According to an eighth aspect of the present disclosure, there is provided an apparatus which may be implemented as a network node. The apparatus may comprise a determining unit and a transmitting unit. In accordance with some exemplary embodiments, the determining unit may be operable to carry out at least the determining step of the method according to the fifth aspect of the present disclosure. The transmitting unit may be operable to carry out at least the transmitting step of the method according to the fifth aspect of the present disclosure.

[0037] According to various exemplary embodiments, a first reference signal (e.g., a synchronization signal such as an SSB signal, etc.) for a first type of operations (e.g., IDLE/INACTIVE mode operations, etc.) may be provided by a network node at a lower transmission rate, and in addition or alternative to the first reference signal, a second reference signal (e.g., another synchronization signal such as an SSB or SSB-like signal, etc.) for a second type of operations (e.g., CONNECTED mode operations, etc.) may be dynamically provided by the network node in response to one or more triggers. This can improve energy efficiency and enhance resource utilization while achieving flexibility of reference signal transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The disclosure itself, the preferable mode of use and further objectives are best understood by reference to the following detailed description of the embodiments when read in conjunction with the accompanying drawings, in which: [0039] Fig.l is a flowchart illustrating a method according to an embodiment of the present disclosure;

[0040] Fig.2 is a flowchart illustrating another method according to an embodiment of the present disclosure;

[0041] Fig.3 is a flowchart illustrating yet another method according to an embodiment of the present disclosure;

[0042] Fig.4 is a flowchart illustrating a further method according to an embodiment of the present disclosure;

[0043] Fig.5 is a block diagram illustrating an apparatus according to an embodiment of the present disclosure;

[0044] Figs.6A-6B are block diagrams illustrating various apparatuses according to some embodiments of the present disclosure;

[0045] Fig.7 shows an example of a communication system 700 in accordance with some embodiments.

DETAILED DESCRIPTION

[0046] The embodiments of the present disclosure are described in detail with reference to the accompanying drawings. It should be understood that these embodiments are discussed only for the purpose of enabling those skilled persons in the art to better understand and thus implement the present disclosure, rather than suggesting any limitations on the scope of the present disclosure. Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present disclosure should be or are in any single embodiment of the disclosure. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Furthermore, the described features, advantages, and characteristics of the disclosure may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the disclosure may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the disclosure.

[0047] As used herein, the term “communication network” refers to a network following any suitable communication standards, such as new radio (NR), long term evolution (LTE), LTE-Advanced, wideband code division multiple access (WCDMA), high-speed packet access (HSPA), and so on. Furthermore, the communications between a terminal device and a network node in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G), the second generation (2G), 2.5G, 2.75G, the third generation (3G), 4G, 4.5G, 5G communication protocols, and/or any other protocols either currently known or to be developed in the future.

[0048] The term “network node” refers to a network device in a communication network via which a terminal device accesses to the network and receives services therefrom. The network node may refer to a base station (BS), an access point (AP), a multi-cell/multicast coordination entity (MCE), a controller or any other suitable device in a wireless communication network. The BS may be, for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a next generation NodeB (gNodeB or gNB), a remote radio unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, a low power node such as a femto, a pico, and so forth. [0049] Yet further examples of the network node comprise multi- standard radio (MSR) radio equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, positioning nodes and/or the like. More generally, however, the network node may represent any suitable device (or group of devices) capable, configured, arranged, and/or operable to enable and/or provide a terminal device access to a wireless communication network or to provide some service to a terminal device that has accessed to the wireless communication network.

[0050] The term “terminal device” refers to any end device that can access a communication network and receive services therefrom. By way of example and not limitation, the terminal device may refer to a mobile terminal, a user equipment (UE), or other suitable devices. The UE may be, for example, a subscriber station, a portable subscriber station, a mobile station (MS) or an access terminal (AT). The terminal device may include, but not limited to, portable computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, a mobile phone, a cellular phone, a smart phone, a tablet, a wearable device, a personal digital assistant (PDA), a vehicle, and the like.

[0051] As yet another specific example, in an Internet of things (loT) scenario, a terminal device may also be called an loT device and represent a machine or other device that performs monitoring, sensing and/or measurements etc., and transmits the results of such monitoring, sensing and/or measurements etc. to another terminal device and/or a network equipment. The terminal device may in this case be a machine-to-machine (M2M) device, which may in a 3rd generation partnership project (3 GPP) context be referred to as a machine-type communication (MTC) device. [0052] As one particular example, the terminal device may be a UE implementing the 3GPP narrow band Internet of things (NB-IoT) standard. Particular examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances, e.g., refrigerators, televisions, personal wearables such as watches etc. In other scenarios, a terminal device may represent a vehicle or other equipment, for example, a medical instrument that is capable of monitoring, sensing and/or reporting etc. on its operational status or other functions associated with its operation.

[0053] As used herein, the terms “first”, “second” and so forth refer to different elements. The singular forms “a” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises”, “comprising”, “has”, “having”, “includes” and/or “including” as used herein, specify the presence of stated features, elements, and/or components and the like, but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof. The term “based on” is to be read as “based at least in part on”. The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment”. The term “another embodiment” is to be read as “at least one other embodiment”. Other definitions, explicit and implicit, may be included below.

[0054] Network (NW) energy consumption in NR increases with respect to LTE due to more complex hardware (HW), e.g., a higher bandwidth (BW) and a larger number of transceivers. This is particularly more evident when the NW operates in higher frequencies. Hence it is important for the NW to turn ON/OFF unused HW modules during inactivity times. For example, in frequency range 2 (FR2), an NR gNB can be configured with up to 64 beams and transmit up to 64 SSBs. This implies 64 ports with many transceiver chains involved. Such SSBs are transmitted every 20ms in during 5ms windows for the sake of providing coverage to potential UEs even if there actually are no UEs present in a cell.

[0055] An NR gNB can be configured with up to 64 SSBs. The configured SSBs in a cell have all the same periodicity and output power. The gNB can provide information to UEs about how many/which SSBs are active (present) within the serving cell and neighboring cells. The gNB can further provide information about the rate/periodicity at which these SSBs are provided on cell level. For the serving cell, the parameter ssb-PositionsInBurst indicates which of the SSBs that are active, and the parameter ssb-PeriodicityServingCell specifies their rate/periodicity. Furthermore, the UEs are informed about the SSBs output power via the common parameter ss-PBCH-BlockPower. When a UE comes to neighbor cells, the gNB can specify the neighboring active (present) SSBs via the parameter ssb-ToMeasure and the associated rate/periodicity via the SSB measurement timing configuration (SMTC) which defines the time window during which the UE measures the SSBs belonging to these neighboring cells. The UEs are configured with the above SSB presence and timing/rate information either in RRC IDLE/INACTIVE mode via broadcast system information or in RRC CONNECTED mode via dedicated RRC messages.

[0056] Typically, the SSBs transmission rate is configured for the most demanding scenario. For example, most deployments use 20ms period for SSB transmission, especially on the global synchronization channel number (GSCN), to ensure optimal performance in UE cell search time, and also to have high enough provision rate for RRC CONNECTED mode operations. As mentioned above, the increasing number of SSB transmissions in NR particularly at higher frequencies can increase the NW power consumption and contribute to excessive noise/interference for neighboring cells. In certain deployments, e.g., in presence of overlapping coverage cells, it is not necessary for all gNBs to provide SSBs that often. Although SSBs can also be configured with up to 160ms period, once the UE establishes a connection, a higher rate may be required for high performance. In order to be able to achieve really good power savings, both higher periods (e.g., higher than 160ms) and also dynamics for providing higher rates only when necessary may be desired.

[0057] Various exemplary embodiments of the present disclosure propose solutions for reference signal transmission, which can enable low-rate cell-defining SSB transmission and/or dynamic provision of auxiliary SSBs. In accordance with exemplary embodiments, a network node such as a gNB may operate in a relaxed mode such that it can provide one or more reference signals (e.g., cell-defining SSBs) for IDLE/INACTIVE UEs’ operations at a reduced rate. As such, the gNB can enjoy various sleep states during the gaps in-between the transmissions. Upon various triggers, e.g., when UEs enter CONNECTED state, the gNB can transmit additional reference signals (e.g., SSBs or SSB-like signals with different contents) which may be different from the ones provided in the relaxed mode. The additional reference signals may be only transmitted while there is a need for higher performance operations, such as CONNECTED mode operations, high-speed mobility, fast secondary cell (Scell) activation, etc.

[0058] Fig.l is a flowchart illustrating a method 100 according to an embodiment of the present disclosure. The method 100 illustrated in Fig.l may be performed in a network node (e.g., a gNB, etc.) for synchronization signal provision. As shown in block 102, the network node may provide one or more first synchronization signals (which may be cell defining synchronization signals) used for basic operations (e.g., idle mode UEs’ basic operations such as cell (re-)selection, paging, etc.) at a low rate. Optionally, when/while a triggering condition is satisfied, as shown in block 104, the network node may additionally provide one or more second synchronization signals (which may be temporary synchronization signals) for more demanding UE operations. In an embodiment, said more demanding UE operations may include, but not limited to, one or more of the following operations:

1) connected mode mobility; 2) connected mode link maintenance;

3) fast SCell activation for connected mode UEs;

4) idle mode mobility at higher speeds (e.g., with high-speed trains) than regular UEs (e.g., UEs carried by pedestrians, cars at moderate speeds, etc.); and

5) certain idle mode services involving broadcast/multi-cast transmissions.

[0059] In accordance with an exemplary embodiment, the triggering condition may comprise a presence of one or more UEs in the gNB’s coverage area whose operating scenario includes one or more of the above operations 1) ~ 5).

[0060] In accordance with an exemplary embodiment, the first synchronization signal may be a cell-defining SSB signal. In accordance with another exemplary embodiment, the second synchronization signal may be an SSB or SSB-like signal which may be or may not be cell-defining. The SSB-like signal may comprise a signal containing a subset of SSB fields (e.g., secondary synchronization signal (SSS)/primary synchronization signal (PSS) fields, etc.), containing all SSB fields but in one or more fields information contents may be changed compared to the SSB, etc. In an embodiment, when the second synchronization signal is a cell-defining SSB signal, it may include information (e.g., a barring flag, etc.) such that a legacy UE (e.g., a UE which is not compatible with the proposed solutions for low-rate reference signal transmission and/or dynamic provision of auxiliary reference signals according to the present disclosure), when decoding the second synchronization signal, may treat the cell served by the network node as barred and leave the cell.

[0061] In accordance with an exemplary embodiment, the second synchronization signal provision period may be shorter than the first synchronization signal period. In accordance with another exemplary embodiment, the second synchronization signal provision period may be the same as or longer than the first synchronization signal provision period. The network node can decide when and/or how to transmit the first synchronization signal and/or the second synchronization signal. For example, the network node may decide to transmit either a first set of SSBs or a second set of SSBs, or both of them. Optionally, when both the first set of SSBs and the second set of SSBs are transmitted by the network node, a UE may have in total more SSBs available for its operations.

[0062] In accordance with an exemplary embodiment, the second synchronization signal periodicity may be a function of connected UE- or NW- DRX cycle configured by the NW. As an example, the second synchronization signal periodicity may be equal to the DRX cycle. In another example, the second synchronization signal periodicity may be equal to min(N*160, DRX cycle), where N is a scaling factor, such as 2, 4, 8, etc. In another example, at least one SSB may be transmitted in each DRX cycle. The second synchronization signal periodicity may be any candidate value in a first synchronization signal periodicity set which is less than the configured DRX cycle. In an embodiment, the offset of the first synchronization signal occasion may be Xms before the DRX ON duration, where X may be a value less than a predefined threshold.

[0063] In accordance with an exemplary embodiment, the SMTC periodicity of the first synchronization signal may be larger than the SMTC periodicity of the second synchronization signal. In accordance with another exemplary embodiment, the SMTC periodicity of the second synchronization signal may be the same as or longer than the SMTC periodicity of the first synchronization signal.

[0064] In accordance with an exemplary embodiment, a frequency span or amount of other physical resources of the second synchronization signal may be similar to that configured for the first synchronization signal.

[0065] In accordance with an exemplary embodiment, the first synchronization signal such as an SSB may include information or characteristics such that a UE compatible with the proposed solutions for reference signal transmission according to the present disclosure can understand, upon decoding it, that the current cell is providing SSBs at a low rate. Such information/characteristics can be a new information element (IE) introduced, e.g., an indicator consisting of one or more bits. Alternatively or additionally, such information/characteristics can be a specific value, or a combination of values in an existing IE of an SSB, e.g., using/repurposing one of the reserved/spare values in a master information block (MIB) of the SSB. For example, one or more of ssb-SubcarrierOffset,pdcch-ConfigSIBl, spare in the MIB.

[0066] In accordance with an exemplary embodiment, the second synchronization signal such as an SSB may include information or characteristics such that a UE compatible with the proposed solutions for low-rate reference signal transmission and/or dynamic provision of auxiliary reference signals according to the present disclosure can understand, upon decoding it, that the second synchronization signal is an SSB, potentially temporarily, provided at a different transmission rate or different schedule than the first synchronization signal. Such information/characteristics can be a new IE introduced, e.g., an indicator consisting of one or more bits. Alternatively or additionally, such information/characteristics can be a specific value, or a combination of values in an existing IE of an SSB, e.g., using/repurposing one of the reserved/spare values in an MIB of the SSB. For example, one or more of ssb-SubcarrierOffset, pdcch-ConfigSIB 1 , spare in the MIB. Alternatively or additionally, such information/characteristics can be a specific characteristic, e.g., the SSB is not cell defining but is still provided on a frequency resource (e.g., on GSCN) intended for cell-defining SSBs. Alternatively or additionally, such information/characteristics can be a specific characteristic, e.g., the SSB does not contain an MIB, or its structure is otherwise modified compared to a conventional SSB.

[0067] In accordance with an exemplary embodiment, the second synchronization signal may be a group of reference signals with different features, e.g., periodicities, contents or characteristics, etc. This group of reference signals may be transmitted by different beams, e.g., one kind of the reference signals is transmitted by a partial of all beams and others are transmitted by other beams.

[0068] In accordance with an exemplary embodiment, the network node may additionally include information in one or more of the broadcast system information blocks (SIBs) that the present cell is operating according to the proposed solutions for reference signal transmission. Optionally, the SIB(s) may additionally include information about the rate and/or characteristics of the first and second synchronization signals from the present cell. In accordance with another exemplary embodiment, the network node may additionally include information in one or more of the broadcast SIBs that one or more neighboring cells are operating according to the proposed solutions for reference signal transmission. Optionally, the SIB(s) may additionally include information about the rate and/or characteristics of the first and second synchronization signals from the one or more neighboring cells.

[0069] In accordance with an exemplary embodiment, the second synchronization signal may not be provided at all during certain times/ scenarios when the network node does not see a need for its transmission. As such, the network node can save transmission power. In accordance with another exemplary embodiment, the network node may utilize the transmission gaps and enter various sleep states dependent on the transmission gap lengths.

[0070] In accordance with an exemplary embodiment, the network node may (re)start transmitting the second synchronization signal when the triggering condition is satisfied, for example, when a UE establishes a connection or after the connection establishment depending on the type of a service provided to the UE, or depending on a movement pattern of the UE. [0071] In accordance with an exemplary embodiment, the network node may (re)start transmitting the second synchronization signal when it is triggered by another network node, for example, imminent to handover of a UE from said another network node. Or for example, when said another network node detects a fast-moving UE on its way towards the network node.

[0072] In accordance with an exemplary embodiment, the network node may (re)start transmitting the second synchronization signal when it is triggered by a UE, for example, via a radio resource control (RRC) message such as UE assistance information (UAI), or a specific preamble, etc.

[0073] In accordance with an exemplary embodiment, the network node may (re)start transmitting a partial of all types of the second synchronization signals when they are triggered by a UE, if the number of triggers received is below a certain number. In accordance with another exemplary embodiment, the network node may (re)start transmitting all types of the second synchronization signals if the number of triggers received is over a certain number.

[0074] In accordance with an exemplary embodiment, the network node may (re)start transmitting the second synchronization signal during specific hours of the day that are considered as rush hour. This may be important for places such as train stations, airports, etc. The periodicity of the second synchronization signal may depend on the demand on the place and time.

[0075] In accordance with an exemplary embodiment, the network node may (re)start transmitting the second synchronization signal after knowing several failed attempts to connect in the first synchronization signal. The number of failed attempts such as physical random access channel (PRACH) attempts from a UE or several UEs in the first synchronization signal may be some sort of demand indicator. [0076] In accordance with an exemplary embodiment, the transmission rate of the second synchronization signal(s) may be different depending on type of service, mobility pattern of the UE, and/or radio link quality, etc.

[0077] In accordance with an exemplary embodiment, the network node may inform the UE about absence/presence of the second synchronization signal, e.g., via one or more of broadcast, dedicated, group-common, physical layer (i.e., LI, e.g., downlink control information (DCI), etc.), medium access control (MAC) layer (i.e., L2, e.g., medium access control-control element (MAC-CE), etc.), RRC signaling, etc.

[0078] Fig.2 is a flowchart illustrating another method 200 according to an embodiment of the present disclosure. The method 200 illustrated in Fig.2 may be performed in a UE for synchronization signal reception. As shown in block 202, the UE may receive one or more synchronization signals transmitted by a network node. The one or more synchronization signals may comprise e.g., a first synchronization signal (e.g., the first synchronization signal as described with respect to Fig.1) which may be transmitted at a low rate by the network node, and/or a second synchronization signal (e.g., the second synchronization signal as described with respect to Fig.1) which may be additionally provided or alternatively switched by the network node. The UE may perform different types of operations based at least in part on the one or more received synchronization signals, as shown in block 204. For example, the UE may mainly rely on the first synchronization signal (e.g., a cell defining SSB) for the basic idle mode operations such as serving cell evaluation, cell (re-)selection, paging, etc. Optionally, the UE may rely on one or more second synchronization signals (e.g., auxiliary SSBs), in addition or alternative to the first synchronization signal, for more demanding type of operations (e.g., connected mode operations, idle mode mobility at high-speed, etc.). [0079] In accordance with an exemplary embodiment, the UE may apply the relax mode cell (re-)selection measurement requirement, such as not-at-cell edge, and/or low mobility, when the UE detects the low-rate synchronization signal such as the first synchronization signal in the serving cell from the network node. In accordance with another exemplary embodiment, the UE may use one or more instances of the second synchronization signal provided by the network node.

[0080] In accordance with an exemplary embodiment, the UE may not treat the cell served by the network node as barred (as the legacy UEs would have done), when the UE receives the second synchronization signal such as an S SB with one or more of the following contents/characteristics: a newly introduced IE (e.g., an indicator consisting of one or more bits); a specific value or a combination of values in an existing IE of an SSB (e.g., using/repurposing one of the reserved/spare values in an MIB of the SSB, such as one or more of ssb-SubcarrierOffset, pdcch-ConfigSIBl , spare in the MIB); a specific characteristic such as that the SSB is not cell defining but is still provided on a frequency resource (e.g., on GSCN) intended for cell-defining SSBs; a specific characteristic such as that the SSB does not contain an MIB; a specific characteristic such as periodicity or listing ON/OFF time instances few minutes or hours ago (e.g., the UE may have an idea whether the second synchronization signal is frequently transmitted or not); and etc. Alternatively or additionally, the UE may not treat the cell served by the network node as barred (as the legacy UEs would have done), when the UE receives one or more SIBs including information indicating that the present cell or a neighboring cell is operating according to the proposed solutions for low-rate reference signal transmission and/or dynamic provision of auxiliary reference signals.

[0081] In accordance with an exemplary embodiment, the UE may trigger provision of the second synchronization signal either via explicit signaling/request/UAI message/ small data transmission or implicitly by establishing a connection, starting a specific service, etc.

[0082] In accordance with an exemplary embodiment, the UE may trigger more provision of the second synchronization signal, e.g., higher density of the second synchronization signals, if the second synchronization signal is provided by the network node gradually and the better synchronization accuracy is needed.

[0083] It can be appreciated that the UE configured to perform the method 200 of Fig.2 may correspond to the UE configured to receive synchronization signals and/or signaling messages from the network node as described with respect to the method 100 of Fig.l . Accordingly, various exemplary embodiments for synchronization signal transmission as described in connection with the method 100 of Fig.l may also be correspondingly applicable to the synchronization signal reception as described in connection with method 200 of Fig.2.

[0084] Many advantages may be achieved by applying the proposed solutions. For example, rather that constantly providing SSBs at a high rate (e.g., every 20ms) to cater for the most demanding scenario (e.g., for CONNECTED mode UEs, etc.), the proposed solutions can enable a gNB to only transmit SSBs for the least demanding scenario (e.g., for IDLE mode UEs in low/moderate mobility, etc.) and only provide extra reference signals such as additional SSBs when necessary, without sacrificing the NW performance such as a UE’s initial access to the gNB. As such, there may be longer gaps between the signal transmissions. During these longer gaps, the gNB can enjoy deeper sleep states than the existing implementations, leading to lower energy consumption in the radio access network (RAN). The proposed solutions will be described in more detail below in connection with various exemplary embodiments.

[0085] In accordance with an exemplary embodiment, SSBs to be transmitted by a gNB may be separated into a first set of SSBs for basic RRC IDLE/INACTIVE operations (such as cell (re-)selection, paging, etc.) and optionally a second set of SSBs which may be used during more demanding operations such as RRC CONNECTED mode and potentially also for operations in RRC IDLE/INACTIVE mode that may require higher rate of SSBs, such as broadcast/multi-cast services, or when UEs are moving at high speed. In an embodiment, the second set of SSBs may be used during the time of the day where the demand is high on some specific places. In the case of the first set of SSBs, e.g., for RRC IDLE/INACTIVE basic operations, cell-defining SSBs may be used. The first set of SSBs may be transmitted at low rates far beyond the typical 20ms transmission rate, e.g., every 160ms, ..., 960ms. Upon receiving the first set of SSBs, which may typically be transmitted on GSCN, UEs compatible with the proposed solution for low-rate reference signal transmission according to the present disclosure can understand that a cell is found and can be used for camping. These UEs may spend longer time on each carrier during cell (re-)selection as they can either assume that there could be a low-rate IDLE/INACTIVE SSB transmission, or they can have received configuration information indicating that this cell may use low-rate SSB transmission. For example, such configuration information may be received by a UE from a neighbor cell either via dedicated or broadcast signaling, or the UE may have been preconfigured by any other means (e.g., information on subscriber identity module (SIM) or embedded subscriber identity module eSIM, etc.). Additionally, this UE may, e.g., based on information received from the current cell, also understand that the current cell is operating with a low-rate SSB transmission for basic mode operations.

[0086] Depending on the transmission rate of the SSBs, a legacy UE may not be able to camp on such cell. For example, the legacy UE may not be able to operate on a cell on which SSBs are transmitted more seldom than 160ms. As such, the gNB may set the content of the SSB such that the legacy UE does not camp on it, e.g., by setting the cellBarred flag in an MIB or any other information element so that the legacy UE does not camp on it. The legacy UE may then continue to search for other cells in that area, potentially overlapping.

[0087] In accordance with an exemplary embodiment, when necessary for more demanding operations, the gNB can additionally during the course of the operations transmit the second set of SSBs. The second set of SSBs may be or may not be cell-defining SSBs. In an embodiment, the second set of SSBs may typically have a higher transmission rate than the first set of SSBs. In another embodiment, the second set of SSBs may have the same as or even lower transmission rate than the first set of SSBs. More importantly, when both the first set of SSBs and the second set of SSBs are transmitted, the UE has in total more SSBs available for its operations. In an embodiment, the number of the second set of SSBs transmitted by the gNB may be adapted to the type and/or service and/or mobility (e.g., high/low speed) and/or link quality of the UE. For example, if a critical service is in use for the UE, or if the UE is at high speed, or if the UE is in poor coverage, more SSBs may be provided for better performance.

[0088] In the case when both the first set of SSBs and the second set of SSBs are transmitted, both the first and second sets of SSBs may have identical beams, e.g., the same set of SSB indices for simplicity. In an embodiment, the first and second sets of SSBs may have different sets of beams, resulting for a wider coverage especially during high demands. In another embodiment, for some time the gNB can determine which beams for both the first and second sets of SSBs are mostly demanded. Those beams that are mostly demanded may be used for the second set of SSBs while other beams can be used for the first set of SSBs, or vice versa depending on application.

[0089] In accordance with an exemplary embodiment, only one type of the second set of SSBs may be transmitted by one network node. The transmitted second set of SSBs may only exist in a portion of all beams of one network node. In another embodiment, multiple types of the second set of SSBs may be transmitted by one network node. In this case, the second set of SSBs may be transmitted by the same beam or by different beams. A group of different synchronization signals can be transmitted between neighbor network nodes, and if these signals have different periodicities or different structures, interference can be avoided.

[0090] In accordance with an exemplary embodiment, all types of the second set of SSBs can be triggered all together by the NW or UEs. In accordance with another exemplary embodiment, different types of the second set of SSBs can be triggered gradually. In one example, if below a certain number of triggers received, the second set of SSBs with relative low periodicities may be triggered first. And if more triggers received (e.g., being triggered by more UEs), then more types of the second set of SSBs may be triggered. In another example, if the triggered second set of SSBs do not fulfill the demands of a service in terms of quality, the UE or the NW may initiate more triggers so that the network node can (re)start transmitting more types of second set of SSBs even though the number of triggers received is still below a threshold.

[0091] In accordance with an exemplary embodiment, the gNB may use different means for informing the UE about presence/absence and schedule of the second set of SSBs, for example, via any/combination of broadcast, dedicated, group-common, LI (e.g., DCI, etc.), L2 (e.g., MAC-CE, etc.) signaling, information from the first set of SSBs, etc.

[0092] In accordance with an exemplary embodiment, the NW may use different triggers for activation of the second set of SSBs. For example, the gNB may be triggered by another network node (e.g., in a neighbor cell) to start providing the second set of SSBs for the sake of handover preparation, or Scell activation, or when there is a high-speed moving UE in vicinity. Other examples of triggers may include when multiple failed atempts to connect from the first set of SSBs are observed from several UEs, resulting to activate the second set of SSBs to lessen the failed attempts. Other examples of triggers may include when a UE establishes a connection, or when a specific service is requested by the UE or is set up by the NW, or when the NW is about to initiate a broadcast/multicast service, or based on UE assistance either via an RRC message such as UAI or via lower layer indications such as transmitting a specific preamble, etc.

[0093] In accordance with an exemplary embodiment, the NW may indicate a second field configured by IE ssb-ToMeasure in system information in IE MeasIdleConfig of SIB11, IE intraFreqCellReselectionlnfo of SIB2, IE InterFreqCarrierFreqlnfo of SIB4 and/or in RRCreconfiguration with a synchronization message for handover preparations. The SSBToMeasure may also be accompanied with SMTC information.

[0094] As an example, the RRCrelease message which currently gives UE information is shown below by IE MeasIdleConfigDedicated.

MeasIdleConfigDedicated-rl6 ::= SEQUENCE { measIdleCarrierListNR-rl6 SEQUENCE (SIZE (l..maxFreqIdle-rl6)) OF

MeasIdleCarrierNR-rl6 OPTIONAL, -- Need N measIdleCarrierListEUTRA-rl6 SEQUENCE (SIZE (L.maxFreqIdle-rl6)) OF

MeasIdleCarrierEUTRA-rl6 OPTIONAL, - Need N measIdleDuration-rl6 ENUMERATED {sec 10, sec30, sec60, secl20, secl80, sec240, sec300, spare}, validity AreaList-rl 6 Validity AreaList-r 16

OPTIONAL, - Need N

}

[0095] In accordance with an exemplary embodiment, the second SSBToMeasure (and possibly SMTC) information may be added within IE MeasIdleCarrierNR. The UE may use the configured SSB information if the UE has information on which SSB is applied on the cell to be measured, or the UE may prepare measurements based on both and apply the better reference signal received power (RSRP) results. In this way, even if the UE does not know what the cell applies, it may be possible to access the cell, or allow cell search.

[0096] The RRC signaling can be accompted by MAC CE or DCI for at least the connected mode UEs to give them more accurate information on SSBs, e.g., when each SSB pattern is to be considered. For example, if two or more patterns, e.g., SSB-ToMeasure and SMTC (or other combination of parameters), are given, the preferred pattern or patterns can be indicated by MAC CE or DCI.

[0097] As one alternative set of embodiments, the SSB patterns can coincide such that a second pattern gives additional SSBs to measure for the UE to what a first pattern gives. This may be within an SSB burst or a periodicity of the SSB burst. For example, the first pattern may give 4 out of 8 nominal SSB locations within a burst by SSB-ToMeasure 1 and the second pattern may give 2 additional SSB beams for the burst by SSB-ToMeasure2. In this case, the UE can be instructed to consider SSB-ToMeasure 1 and SSB-ToMeasure2 to determine which SSB beams are present in a burst. As an alternative, the UE may consider one pattern or the other pattern and this choice may be signaled via RRC signaling, DCI or MAC CE.

[0098] As another alternative set of embodiments, the parameter SMTC1 can give the UE a periodicity of 160ms for a SSB burst and the parameter SMTC2 can give the UE a periodicity of 160ms for a SSB burst but with another offset such that if the UE considers these together, the SSB burst periodicity is 80ms. Other ways may also be considered to build the final set. Also, if the parameter SMTC2 is valid only certain times, the UE may use that information and when filtering the measurements pick up all bursts as instructed by SMTC1 and SMTC2 plus timing information. The timing information can be given by RRC signaling using coordinated universal time (UTC) or it can be activation/deactivation based using DCI/MAC CE.

[0099] It is noted that some embodiments of the present disclosure are mainly described in relation to 5G/NR specifications being used as non-limiting examples for certain exemplary network configurations and system deployments. As such, the description of exemplary embodiments given herein specifically refers to terminology which is directly related thereto. Such terminology is only used in the context of the presented non-limiting examples and embodiments, and does naturally not limit the present disclosure in any way. Rather, any other system configuration or radio technologies may equally be utilized as long as exemplary embodiments described herein are applicable.

[00100] Fig.3 is a flowchart illustrating a method 300 according to some embodiments of the present disclosure. The method 300 illustrated in Fig.3 may be performed by a terminal device or an apparatus communicatively coupled to the terminal device. In accordance with an exemplary embodiment, the terminal device may be configured to receive reference signals such as synchronization signals from a network node, e.g., according to different scheduling and/or transmission configurations.

[00101] According to the exemplary method 300 illustrated in Fig.3, the terminal device may receive a first reference signal for a first type of operations transmitted by a network node at a first transmission rate (e.g., every 160ms, ... , 960ms, etc.) lower than a threshold (e.g., every 20ms, 160ms, etc.), and/or a second reference signal for a second type of operations transmitted, in response to one or more triggers, by the network node at a second transmission rate (which may be the same as or different from the first transmission rate), as shown in block 302. In accordance with an exemplary embodiment, the terminal device may decode the first reference signal and/or the second reference signal, as shown in block 304.

[00102] In accordance with an exemplary embodiment, the threshold may be configurable based at least in part on operation demands and/or network deployments. In an embodiment, the threshold may be equal to or less than a reference signal transmission rate (e.g., every 20ms, etc.) which may be typically configured for the most demanding scenario and/or operations in connected mode.

[00103] In accordance with an exemplary embodiment, the first type of operations may include one or more of the following idle mode operations: serving cell evaluation, cell selection, cell re-selection, and paging.

[00104] In accordance with an exemplary embodiment, the second type of operations may include one or more of the following operations: an operation for connected mode mobility, an operation for connected mode link maintenance, an operation for fast secondary cell activation in connected mode, an operation for idle mode mobility at a speed higher than a predefined value, and an operation for an idle mode service involving broadcast or multi-cast transmissions.

[00105] In accordance with an exemplary embodiment, the first reference signal may be an S SB signal or any other types of synchronization signals. In accordance with another exemplary embodiment, the second reference signal may be an SSB based signal or any other types of synchronization signals.

[00106] In accordance with an exemplary embodiment, the first reference signal may include information indicating that a first set of reference signals (e.g., a first set of SSBs, etc.) for the first type of operations are transmitted by the network node at the first transmission rate. The first reference signal may be one of the first set of the reference signals.

[00107] In accordance with an exemplary embodiment, the second reference signal may be different from the first reference signal by one or more of: a signal transmission rate, a signal provision period, a signal periodicity, an SMTC periodicity, a resource configuration, a scheduling configuration, a signal format, and signal contents. In an embodiment, the second reference signal may have a periodicity based at least in part on a DRX cycle.

[00108] In accordance with an exemplary embodiment, the second reference signal may include an indicator (e.g., a barring flag, etc.) which instructs a specified type of terminal devices (e.g., legacy UEs, etc.) not to camp on a cell served by the network node.

[00109] In accordance with an exemplary embodiment, the second reference signal may be one of a second set of reference signals (e.g., a second set of SSBs, etc.) for the second type of operations which may be transmitted by the network node at the second transmission rate. In accordance with another exemplary embodiment, the second transmission rate may be configurable based at least in part on types, services, mobility patterns and/or link quality of one or more terminal devices served by the network node.

[00110] In accordance with an exemplary embodiment, the terminal device may receive, from the network node and/or one or more other network nodes, information indicating whether the second set of the reference signals are transmitted by the network node. In an embodiment, the second set of the reference signals may have different characteristics, respectively. For example, the different characteristics may comprise one or more of: scheduling configurations, resource configurations, signal contents, and signal types.

[00111] In accordance with an exemplary embodiment, a number and/or a type of the second set of the reference signals may be configurable based at least in part on the number of the one or more triggers. In an embodiment, the one or more triggers for the second reference signal may comprise one or more of: a presence of at least one terminal device in a coverage area of the network node, where the at least one terminal device may be performing or to perform one or more operations of the second type of operations; establishing a connection for the at least one terminal device; requesting or initiating a service for the at least one terminal device; a change of movement pattern of the at least one terminal device; a request for the second reference signal from the at least one terminal device or at least another network node; a timing trigger of the second reference signal during a predefined time period; and a number of failed connection attempts of the at least one terminal device being equal to or higher than a predefined value.

[00112] In accordance with an exemplary embodiment, the terminal device may transmit a request for the second reference signal to the network node.

[00113] In accordance with an exemplary embodiment, the terminal device may obtain configuration information, which may indicate: whether different sets of reference signals for different types of operations are transmitted by the network node and/or one or more other network nodes, and/or whether a set of reference signals are transmitted by the network node and/or the one or more other network nodes at a lower transmission rate than the threshold. In an embodiment, the configuration information may be preconfigured for the terminal device. Alternatively or additionally, the configuration information may be received from the network node or at least another network node. In an embodiment, the configuration information may further indicate transmission rates and/or signal characteristics of the different sets of reference signals.

[00114] Fig.4 is a flowchart illustrating a method 400 according to some embodiments of the present disclosure. The method 400 illustrated in Fig.4 may be performed by a network node or an apparatus communicatively coupled to the network node. In accordance with an exemplary embodiment, the network node may be configured to provide reference signals such as synchronization signals to one or more terminal devices, e.g., according to different scheduling and/or transmission configurations.

[00115] According to the exemplary method 400 illustrated in Fig.4, the network node may determine whether to transmit a first reference signal for a first type of operations at a first transmission rate lower than a threshold, and/or transmit, in response to one or more triggers, a second reference signal for a second type of operations at a second transmission rate, as shown in block 402. In accordance with an exemplary embodiment, the network node may transmit the first reference signal and/or the second reference signal to one or more terminal devices (e.g., the terminal device as described with respect to Fig.3), according to a result of the determination, as shown in block 404. In an embodiment, the determination of whether to transmit the first reference signal and/or the second reference signal may be performed by the network node based at least in part on service types, performance requirements, operation demands, device capabilities, device mobility, and/or network configurations, etc.

[00116] In accordance with an exemplary embodiment, the first reference signal according to the method 400 may correspond to the first reference signal according to the method 300. Thus, the first reference signal as described with respect to Fig.3 and Fig.4 may have the same or similar contents and/or feature elements. In an embodiment, the first reference signal may be one of a first set of reference signals for the first type of operations which may be transmitted by the network node at the first transmission rate. Correspondingly, the first set of the reference signals as described with respect to Fig.3 and Fig.4 may have the same or similar contents and/or feature elements.

[00117] In accordance with an exemplary embodiment, the second reference signal according to the method 400 may correspond to the second reference signal according to the method 300. Thus, the second reference signal as described with respect to Fig.3 and Fig.4 may have the same or similar contents and/or feature elements. In an embodiment, the second reference signal may be one of a second set of reference signals for the second type of operations which may be transmitted by the network node at the second transmission rate. Correspondingly, the second set of the reference signals as described with respect to Fig.3 and Fig.4 may have the same or similar contents and/or feature elements.

[00118] In accordance with an exemplary embodiment, the network node may transmit, to the one or more terminal devices, information indicating whether the second set of the reference signals are transmitted by the network node.

[00119] In accordance with an exemplary embodiment, the network node may receive a request for the second reference signal from at least one terminal device and/or at least another network node.

[00120] In accordance with an exemplary embodiment, the network node may transmit configuration information to the one or more terminal devices. In an embodiment, the configuration information may indicate: whether different sets of reference signals for different types of operations are transmitted by the network node and/or one or more other network nodes, and/or whether a set of reference signals are transmitted by the network node and/or the one or more other network nodes at a lower transmission rate than the threshold. In another embodiment, the configuration information may further indicate transmission rates and/or signal characteristics of the different sets of reference signals.

[00121] The various blocks shown in Figs.1-4 may be viewed as method steps, and/or as operations that result from operation of computer program code, and/or as a plurality of coupled logic circuit elements constructed to carry out the associated function(s). The schematic flow chart diagrams described above are generally set forth as logical flow chart diagrams. As such, the depicted order and labeled steps are indicative of specific embodiments of the presented methods. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the illustrated methods. Additionally, the order in which a particular method occurs may or may not strictly adhere to the order of the corresponding steps shown.

[00122] Fig.5 is a block diagram illustrating an apparatus 500 according to various embodiments of the present disclosure. As shown in Fig.5, the apparatus 500 may comprise one or more processors such as processor 501 and one or more memories such as memory 502 storing computer program codes 503. The memory 502 may be non-transitory machine/processor/computer readable storage medium. In accordance with some exemplary embodiments, the apparatus 500 may be implemented as an integrated circuit chip or module that can be plugged or installed into a terminal device as described with respect to Fig.2 or Fig.3, or a network node as described with respect to Fig.l or Fig.4. In such cases, the apparatus 500 may be implemented as a terminal device as described with respect to Fig.2 or Fig.3, or a network node as described with respect to Fig.l or Fig.4.

[00123] In some implementations, the one or more memories 502 and the computer program codes 503 may be configured to, with the one or more processors 501, cause the apparatus 500 at least to perform any operation of the method as described in connection with Fig.l. In other implementations, the one or more memories 502 and the computer program codes 503 may be configured to, with the one or more processors 501, cause the apparatus 500 at least to perform any operation of the method as described in connection with Fig.2. In other implementations, the one or more memories 502 and the computer program codes 503 may be configured to, with the one or more processors 501, cause the apparatus 500 at least to perform any operation of the method as described in connection with Fig.3. In other implementations, the one or more memories 502 and the computer program codes 503 may be configured to, with the one or more processors 501, cause the apparatus 500 at least to perform any operation of the method as described in connection with Fig.4. Alternatively or additionally, the one or more memories 502 and the computer program codes 503 may be configured to, with the one or more processors 501, cause the apparatus 500 at least to perform more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

[00124] Fig.6A is a block diagram illustrating an apparatus 610 according to some embodiments of the present disclosure. As shown in Fig.6A, the apparatus 610 may comprise a receiving unit 611 and a decoding unit 612. In an exemplary embodiment, the apparatus 610 may be implemented in a terminal device such as a UE. The receiving unit 611 may be operable to carry out the operation in block 302, and the decoding unit 612 may be operable to carry out the operation in block 304. Optionally, the receiving unit 611 and/or the decoding unit 612 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure. In an embodiment, the apparatus 610 may further comprise a transmitting unit (not shown in Fig.6A) which may be operable to transmit information to one or more other devices (e.g., a network node, another terminal device, etc.). [00125] Fig.6B is a block diagram illustrating an apparatus 620 according to some embodiments of the present disclosure. As shown in Fig.6B, the apparatus 620 may comprise a determining unit 621 and a transmitting unit 622. In an exemplary embodiment, the apparatus 620 may be implemented in a network node such as a base station. The determining unit 621 may be operable to carry out the operation in block 402, and the transmitting unit 622 may be operable to carry out the operation in block 404. Optionally, the determining unit 621 and/or the transmitting unit 622 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure. In an embodiment, the apparatus 620 may further comprise a receiving unit (not shown in Fig.6B) which may be operable to receive information from one or more other devices (e.g., a terminal device, another network node, etc.).

[00126] Fig.7 shows an example of a communication system 700 in accordance with some embodiments.

[00127] In the example, the communication system 700 includes a telecommunication network 702 that includes an access network 704, such as a radio access network (RAN), and a core network 706, which includes one or more core network nodes 708. The access network 704 includes one or more access network nodes, such as network nodes 710A and 710B (one or more of which may be generally referred to as network nodes 710), or any other similar 3rd Generation Partnership Project (3 GPP) access node or non-3GPP access point. The network nodes 710 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 712A, 712B, 712C, and 712D (one or more of which may be generally referred to as UEs 712) to the core network 706 over one or more wireless connections.

[00128] Example wireless communications over a wireless connection include transmitting and/or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and/or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 700 may include any number of wired or wireless networks, network nodes, UEs, and/or any other components or systems that may facilitate or participate in the communication of data and/or signals whether via wired or wireless connections. The communication system 700 may include and/or interface with any type of communication, telecommunication, data, cellular, radio network, and/or other similar type of system.

[00129] The UEs 712 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and/or operable to communicate wirelessly with the network nodes 710 and other communication devices. Similarly, the network nodes 710 are arranged, capable, configured, and/or operable to communicate directly or indirectly with the UEs 712 and/or with other network nodes or equipment in the telecommunication network 702 to enable and/or provide network access, such as wireless network access, and/or to perform other functions, such as administration in the telecommunication network 702.

[00130] In the depicted example, the core network 706 connects the network nodes 710 to one or more hosts, such as host 716. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 706 includes one more core network nodes (e.g., core network node 708) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and/or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 708. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and/or a User Plane Function (UPF).

[00131] The host 716 may be under the ownership or control of a service provider other than an operator or provider of the access network 704 and/or the telecommunication network 702, and may be operated by the service provider or on behalf of the service provider. The host 716 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio/video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[00132] As a whole, the communication system 700 of Fig.7 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and/or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and/or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and/or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox. [00133] In some examples, the telecommunication network 702 is a cellular network that implements 3 GPP standardized features. Accordingly, the telecommunications network 702 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 702. For example, the telecommunications network 702 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and/or Massive Machine Type Communication (mMTC)/Massive loT services to yet further UEs.

[00134] In some examples, the UEs 712 are configured to transmit and/or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 704 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 704. Additionally, a UE may be configured for operating in single- or multi-RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC).

[00135] In the example, the hub 714 communicates with the access network 704 to facilitate indirect communication between one or more UEs (e.g., UE 712C and/or 712D) and network nodes (e.g., network node 710B). In some examples, the hub 714 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 714 may be a broadband router enabling access to the core network 706 for the UEs. As another example, the hub 714 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 710, or by executable code, script, process, or other instructions in the hub 714. As another example, the hub 714 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 714 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub 714 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 714 then provides to the UE either directly, after performing local processing, and/or after adding additional local content. In still another example, the hub 714 acts as a proxy server or orchestrator for the UEs, in particular in if one or more of the UEs are low energy loT devices.

[00136] The hub 714 may have a constant/persistent or intermittent connection to the network node 71 OB. The hub 714 may also allow for a different communication scheme and/or schedule between the hub 714 and UEs (e.g., UE 712C and/or 712D), and between the hub 714 and the core network 706. In other examples, the hub 714 is connected to the core network 706 and/or one or more UEs via a wired connection. Moreover, the hub 714 may be configured to connect to an M2M service provider over the access network 704 and/or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 710 while still connected via the hub 714 via a wired or wireless connection. In some embodiments, the hub 714 may be a dedicated hub - that is, a hub whose primary function is to route communications to/from the UEs from/to the network node 710B. In other embodiments, the hub 714 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 710B, but which is additionally capable of operating as a communication start and/or end point for certain data channels.

[00137] In general, the various exemplary embodiments may be implemented in hardware or special purpose chips, circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto. While various aspects of the exemplary embodiments of this disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[00138] As such, it should be appreciated that at least some aspects of the exemplary embodiments of the disclosure may be practiced in various components such as integrated circuit chips and modules. It should thus be appreciated that the exemplary embodiments of this disclosure may be realized in an apparatus that is embodied as an integrated circuit, where the integrated circuit may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor, a digital signal processor, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this disclosure.

[00139] It should be appreciated that at least some aspects of the exemplary embodiments of the disclosure may be embodied in computer-executable instructions, such as in one or more program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types when executed by a processor in a computer or other device. The computer executable instructions may be stored on a computer readable medium such as a hard disk, optical disk, removable storage media, solid state memory, random access memory (RAM), etc. As will be appreciated by one of skill in the art, the function of the program modules may be combined or distributed as desired in various embodiments. In addition, the function may be embodied in whole or partly in firmware or hardware equivalents such as integrated circuits, field programmable gate arrays (FPGA), and the like.

[00140] The present disclosure includes any novel feature or combination of features disclosed herein either explicitly or any generalization thereof. Various modifications and adaptations to the foregoing exemplary embodiments of this disclosure may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, any and all modifications will still fall within the scope of the non-limiting and exemplary embodiments of this disclosure.

Claims

1. A method (300) performed by a terminal device, comprising: receiving a first set of reference signals for a first type of operation transmitted by a network node at a first transmission rate , wherein the first set of reference signals are synchronization signal block, SSB, signals; and receiving a second set of reference signals for a second type of operation transmitted by the network node at a second transmission rate, wherein the second transmission rate is higher than the first transmission rate; and decoding (304) the first and second sets of reference signals.

2. The method according to claim 1, wherein at least one of the first set of reference signals is received during the receiving of the second set of reference signals.

3. The method according to claim 1, wherein the receiving of the first set of reference signals is not overlapped in time with the receiving of the second set of reference signals.

4. The method according to claim 1, wherein the second reference signal is an SSB based signal, or a cell defining synchronization signal.

5. The method according to any of claims 1-4, further comprising: receiving an RRC message comprising configuration information for the second set of reference signals, wherein the configuration information comprises at least one of: a signal transmission rate; a signal provision period; a signal periodicity; an SSB measurement timing configuration, SMTC, periodicity; a resource configuration; a scheduling configuration; a signal format; and signal contents.

6. The method according to claim 5, wherein the RRC message further comprising: an indication of presence/absence of the second set of reference signals.

7. The method according to any of claims 1-5, further comprising: receiving, from the network node or another network node, an indication of presence/absence of the second set of reference signals.

8. The method according to claim 7, wherein the indication is comprised in a DCI or MAC-CE message.

9. The method according to claim 5 or 6, wherein the configuration information of the second set of reference signals is associated with the second type of operation, wherein the second type of operation includes one or more of: an operation for connected mode mobility; an operation for connected mode link maintenance; an operation for secondary cell activation; an operation for idle mode mobility at a speed higher than a predefined value; and an operation for an idle mode service involving broadcast or multi-cast transmissions.

10. A terminal device (500), comprising: one or more processors (501); and one or more memories (502) comprising computer program codes (503), the one or more memories (502) and the computer program codes (503) configured to, with the one or more processors (501), cause the terminal device (500) to perform the method according to any one of claims 1-9.

11. A method (400) performed by a network node, comprising: transmitting a first set of reference signals for a first type of operation to one or more terminal devices at a first transmission rate, wherein the first set of reference signals are SSB signals; transmitting a second set of reference signals for a second type of operation to one or more terminal devices at a second transmission rate, wherein the second transmission rate is higher than the first transmission rate.

12. The method according to claim 11, wherein the transmitting of the second set of reference signals is in addition to the transmitting of the first set of reference signals.

13. The method according to claim 11, wherein after transmitting the second set of reference signals, switching to transmitting the first set of reference signals.

14. The method according to any of claims 11-13, further comprising: configuring the one or more terminal devices with configuration information for the second set of reference signals, wherein the configuration information comprises at least one of: a signal transmission rate; a signal provision period; a signal periodicity; an SSB measurement timing configuration, SMTC, periodicity; a resource configuration; a scheduling configuration; a signal format; and signal contents.

15. The method according to claim 14, wherein the configuration information for the second set of reference signals is comprised in a RRC message, wherein the RRC message further comprises an indication of presence/absence of the second set of reference signals.

16. The method according to any of claims 11-14, further comprising: transmitting an indication of presence/absence of the second set of reference signals to at least one of the one or more terminal devices, via a DCI or MAC-CE message.

17. The method according to claims 15 or 16, prior to transmitting the indication of presence/absence of the second set of reference signals, determining that one or more triggering conditions are satisfied.

18. The method according to claim 17, wherein the one or more trigger conditions comprise one or more of: a presence of at least one terminal device in a coverage area of the network node, wherein the at least one terminal device is performing or to perform one or more operations of the second type of operations; establishing a connection for the at least one terminal device; requesting or initiating a service for the at least one terminal device; a change of movement pattern of the at least one terminal device; a request for the second reference signal from the at least one terminal device or at least another network node; a timing trigger of the second reference signal during a predefined time period; and a number of failed connection attempts of the at least one terminal device being equal to or higher than a predefined value.

19. The method according to any of claims 14-18, wherein the configuration information of the second set of reference signals is associated with the second type of operation, wherein the second type of operation includes one or more of: an operation for connected mode mobility; an operation for connected mode link maintenance; an operation for secondary cell activation; an operation for idle mode mobility at a speed higher than a predefined value; and an operation for an idle mode service involving broadcast or multi-cast transmissions.

20. A network node (500), comprising: one or more processors (501); and one or more memories (502) comprising computer program codes (503), the one or more memories (502) and the computer program codes (503) configured to, with the one or more processors (501), cause the network node (500) perform the method according to any one of claims 11-19.