CN111034295A

CN111034295A - Method and apparatus for radio link failure in a system using multiple reference signals

Info

Publication number: CN111034295A
Application number: CN201880050932.3A
Authority: CN
Inventors: 黄�俊; 姜贤贞; 文廷敃; 朴承勳; 郑柄薰
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2017-08-10
Filing date: 2018-08-10
Publication date: 2020-04-17
Anticipated expiration: 2038-08-10
Also published as: KR20190017620A; AU2018314063B2; CN111034295B; EP3653009A1; AU2018314063A1; EP3653009A4

Abstract

A communication method and system are provided that merges a 5 th generation (5G) communication system for supporting higher data rates beyond a 4 th generation (4G) system with internet of things (IoT) technology. The present disclosure may be applied to smart services based on 5G communication technology and IoT related technology, such as smart homes, smart buildings, smart cities, smart vehicles, connected vehicles, healthcare, digital education, smart retail, security services. The method comprises the following steps: receiving a Radio Resource Control (RRC) message including first information associated with a reference signal for Radio Link Monitoring (RLM) and second information associated with a threshold value for the RLM; monitoring radio link quality of at least one reference signal indicated by the first information; comparing the radio link quality of the at least one reference signal to the threshold; and indicating synchronization or non-synchronization to a higher layer of the terminal based on the comparison result.

Description

Method and apparatus for radio link failure in a system using multiple reference signals

Technical Field

The present disclosure relates to detecting events of radio link failure in millimeter wave systems.

Background

In order to meet the increasing demand for wireless data services since the deployment of 4 th generation (4G) communication systems, efforts are being made to develop improved 5 th generation (5G) or quasi-5G communication systems. Accordingly, the 5G or quasi-5G communication system is also referred to as a "super 4G network" or a "Long Term Evolution (LTE) system". The 5G communication system is considered to be implemented on a higher frequency band (millimeter wave), for example, a 60GHz band, to achieve a higher data rate. In order to reduce propagation loss of radio waves and increase transmission distance, beamforming, massive Multiple Input Multiple Output (MIMO), full-dimensional MIMO (FD-MIMO), array antenna, analog beamforming, large antenna technology are discussed in the 5G communication system. In addition, in the 5G communication system, development of system network improvement is underway based on advanced small cells, cloud Radio Access Network (RAN), ultra-dense network, device-to-device (D2D) communication, wireless backhaul, mobile network, cooperative communication, coordinated multipoint (CoMP), reception side interference cancellation, and the like. In the 5G system, hybrid Frequency Shift Keying (FSK) and Quadrature Amplitude Modulation (QAM) modulation (FQAM) and Sliding Window Superposition Coding (SWSC) have been developed as Advanced Coding Modulation (ACM), and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and Sparse Code Multiple Access (SCMA) as advanced access technologies.

Currently, the human-oriented connectivity network, the internet, where humans generate and consume information is evolving towards the internet of things (IoT), where distributed entities (e.g., things) exchange and process information without human intervention. Internet of everything (IoE), which is a combination of IoT technology and big data processing technology through connection with a cloud server, has emerged. Since technical elements such as "sensing technology", "wired/wireless communication and network architecture", "service interface technology", and "security technology" are required for IoT implementation, sensor networks, machine-to-machine (M2M) communication, Machine Type Communication (MTC), and the like have been recently studied. Such an IoT environment can provide intelligent internet technology services that create new value for human life by collecting and analyzing data generated by connected things. IoT can be applied to various fields including smart homes, smart buildings, smart cities, smart vehicles or connected vehicles, smart grids, health care, smart instruments, and advanced medical services through fusion and integration between existing Information Technology (IT) and various industrial applications.

In line with this, various attempts are made to apply the 5G communication system to the IoT network. For example, technologies such as sensor networks, Machine Type Communication (MTC), and machine-to-machine (M2M) communication may be implemented through beamforming, MIMO, and array antennas. Applying a cloud Radio Access Network (RAN) as the big data processing technology described above may also be considered as an example of the convergence between 5G technology and IoT technology.

Meanwhile, the following Radio Link Failure (RLF) may be found. In the case of LTE, Downlink (DL) signals are monitored based on cell-specific reference signals (CRS). The signal strength corresponding to the time-frequency location of the reference signal of a particular cell is measured over a preset time and averaged over the preset time. If the average is less than a given signal-to-interference-plus-noise ratio (SINR) or signal-to-noise ratio (SNR), higher layers are notified that a DL radio link problem has occurred.

Unlike Radio Resource Management (RRM) beam management for scheduling fast beam tracking and cell mobility, it is determined whether the state of a link of a corresponding cell is acceptable for a longer period of time in radio link failure processing, and if the link state is not acceptable, a procedure of attaching to the cell itself is retried. Generally, radio processing and Core Network (CN) processing are required since the process of re-attaching to a cell requires cell search, Random Access Channel (RACH) and security related operations to be performed again. There is also a need to exchange data between the newly attached cell and the previous cell causing the failure. Considering the cost of the Radio Resource Control (RRC) re-establishment procedure, it is common practice to give as long a monitoring time as possible.

In the case of omni-directional radiation, multipath effects are taken into account when measuring the strength of the time-frequency resources of the CRS. Factors affecting directivity have been considered when measuring signal strength. Thus, only time factors (measurement duration, arithmetic mean, or moving average) will affect the measurement variation.

The above information is merely given as background information to aid in understanding the present disclosure. No determination or assertion is made as to whether any of the above is applicable as prior art to the present disclosure.

Disclosure of Invention

Technical problem

In the case of the millimeter wave system, since all terminals under cell coverage should perform radio link measurement, a Reference Signal (RS) should be transmitted through an analog beam, not omni-directionally. Depending on the system scenario, multiple analog beams may be transmitted simultaneously, or one analog beam at a time. There may be RSs in the scheduled beams and there may be measurement slots containing separate measurement signals. Direction is another parameter that affects Radio Link Failure (RLF) decisions compared to the case of omni-directional radiation.

Aspects of the present disclosure are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Thus, an aspect of the present disclosure is to newly define an event for notifying a higher layer of a radio link problem through a combination of a direction parameter indicated by a specific analog beam and a time parameter.

Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the embodiments presented.

Technical scheme

According to an aspect of the present disclosure, there is provided a method performed by a terminal. The method comprises the following steps: receiving a Radio Resource Control (RRC) message including first information associated with a reference signal for Radio Link Monitoring (RLM) and second information associated with a threshold value for the RLM; monitoring radio link quality of at least one reference signal indicated by the first information; comparing the radio link quality of the at least one reference signal to the threshold; and indicating synchronization or non-synchronization to a higher layer of the terminal based on the comparison result.

According to another aspect of the present disclosure, another method performed by a base station is provided. The method comprises the following steps: transmitting a Radio Resource Control (RRC) message to a terminal, wherein the RRC message includes first information associated with a reference signal for Radio Link Monitoring (RLM) and second information associated with a threshold value for the RLM; and transmitting at least one of a Synchronization Signal Block (SSB) or a channel state information-reference signal (CSI-RS), wherein the first information is used to indicate at least one of the SSB or the CSI-RS of a radio link quality to be monitored, and wherein the second information is used to compare the radio link quality with the threshold to indicate synchronization or non-synchronization to a higher layer of the terminal.

According to another aspect of the present disclosure, a terminal is provided. The terminal includes a transceiver configured to transmit and receive signals and at least one processor configured to: receiving a Radio Resource Control (RRC) message including first information associated with a reference signal for Radio Link Monitoring (RLM) and second information associated with a threshold value for the RLM; monitoring radio link quality of at least one reference signal indicated by the first information; comparing the radio link quality of the at least one reference signal to the threshold; and indicating synchronization or non-synchronization to a higher layer of the terminal based on the comparison result.

According to another aspect of the present disclosure, a base station is provided. The base station includes a transceiver configured to transmit and receive signals and at least one processor configured to: transmitting a Radio Resource Control (RRC) message to a terminal, wherein the RRC message includes first information associated with a reference signal for Radio Link Monitoring (RLM) and second information associated with a threshold value for the RLM; and transmitting at least one of a Synchronization Signal Block (SSB) or a channel state information-reference signal (CSI-RS), wherein the first information is used to indicate at least one of the SSB or the CSI-RS of a radio link quality to be monitored, and wherein the second information is used to compare the radio link quality with the threshold to indicate synchronization or non-synchronization to a higher layer of the terminal.

Technical effects

In features of the present disclosure, an event of a radio link problem may be defined to be notified by using a scheme of out-of-sync and in-sync decision based on a Reference Signal (RS).

Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the disclosure.

Drawings

The above and other aspects, features and advantages of certain embodiments of the present disclosure will become apparent from the following description taken in conjunction with the accompanying drawings, in which:

fig. 1 illustrates a measurement time slot according to an embodiment of the present disclosure;

fig. 2 illustrates the case of adding as samples, measurements of a scheduled beam in addition to measurements within a measurement time slot in a given duration according to an embodiment of the present disclosure;

fig. 3 illustrates the simultaneous use of multiple data TX beams to transmit a Synchronization Signal (SS) in accordance with an embodiment of the present disclosure;

fig. 4 illustrates a case where a base station configures a separate reference signal for a data TX beam constituting a corresponding SS and transmits the reference signal to a terminal together with configuration information in order to report continuous SS measurement results according to an embodiment of the present disclosure;

fig. 5 illustrates the difference in Radio Link Monitoring (RLM) operation between a Long Term Evolution (LTE) operating beam and a New Radio (NR) operating beam in accordance with an embodiment of the present disclosure;

fig. 6 depicts signaling between a terminal and a base station for radio link monitoring with an xSS according to an embodiment of the disclosure;

fig. 7 depicts a case where a T _ in value is adaptively managed according to the number of operating beams according to an embodiment of the present disclosure;

fig. 8 depicts a case where a base station transmits information on offset values set for a specific DL TX beam as system information and a terminal uses this information whenever a DL TX beam set is configured according to an embodiment of the present disclosure;

fig. 9 depicts a case where beam offset information is transmitted through a Radio Resource Control (RRC) dedicated message according to an embodiment of the present disclosure;

fig. 10 depicts a case where related offset information is transmitted through a physical layer control channel according to an embodiment of the present disclosure;

fig. 11 depicts a case where related offset information is transmitted through a Medium Access Control (MAC) Control Element (CE) according to an embodiment of the present disclosure;

fig. 12 illustrates a scheme for providing an indication per RS or an aggregation indication to a higher layer (RRC) by a physical layer according to an embodiment of the present disclosure;

fig. 13 illustrates a case where a channel state information-reference signal (CSI-RS) IS Synchronized (IS) to a terminal and a related SS IS unsynchronized according to an embodiment of the present disclosure;

fig. 14 illustrates a strategy for performing RLM in a CSI-RS prioritized manner when a CSI-RS is configured at a specific time point when RLM is performed by an SS according to an embodiment of the present disclosure;

fig. 15 illustrates one strategy for performing RLM with CSI-RS prioritized when CSI-RS is configured at a specific time for performing RLM by SS according to an embodiment of the present disclosure;

fig. 16 depicts a case where a base station configures a specific bandwidth shard (BWP) based on the capability and service requirement of a terminal according to an embodiment of the present disclosure;

fig. 17 depicts a case where capability information related to User Equipment (UE) beamforming, information related to a requested service, and preferred bandwidth fragmentation information are respectively transmitted via separate RRC messages after connection setup according to an embodiment of the present disclosure;

fig. 18 illustrates a case where an RLM-RS exists only in one frequency range according to an embodiment of the present disclosure;

fig. 19 depicts RLM-RS signaling when an active bandwidth slice has RLM-RS or does not have RLM-RS, in accordance with an embodiment of the disclosure;

fig. 20 illustrates a case where RLM-RS exists in a plurality of frequency ranges according to an embodiment of the present disclosure;

fig. 21 is a block diagram of a base station according to an embodiment of the present disclosure;

fig. 22 is a block diagram of a terminal according to an embodiment of the present disclosure;

fig. 23 depicts a case where RLM/RLF parameters are differently set according to the type of service received by a terminal according to an embodiment of the present disclosure; and

fig. 24 depicts a handover scenario in which a target cell receives service information of a terminal from a serving cell and accordingly transmits configuration information, block error rate (BLER), and RLF parameters related to RLM RS to the serving cell according to an embodiment of the present disclosure.

It should be noted that in the drawings, like reference numerals are used to depict the same or similar elements, features and structures.

Detailed Description

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the disclosure as defined by the claims and their equivalents. The following description includes various specific details to aid understanding, but such details are to be regarded as illustrative only. Thus, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are not limited to the written meaning, but are used only by the inventor to allow a clear and concise understanding of the disclosure. Thus, it should be apparent to those skilled in the art that the following descriptions of the various embodiments of the present disclosure are provided for illustration only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents.

It will be understood that the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes one or more such surfaces.

Aspects, features and advantages of certain embodiments of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. The description of the various embodiments does not describe every possible example of the disclosure. It should be apparent to those skilled in the art that the following description of the various embodiments is provided for illustration only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents. Like reference numerals refer to like parts throughout the specification.

In the following description, the terms "base station," "enhanced node b (enb)," and "g node b (gnb)", may be used interchangeably. The terms "terminal" and "User Equipment (UE)" may be used interchangeably.

As a measurement source, an RS in a measurement slot may be measured, a Reference Signal (RS) of a scheduling beam is measured, and a demodulation reference signal (DMRS) on a Physical Downlink Control Channel (PDCCH) is measured. These measurements may be taken together. In the description, a beam measurement reference signal (BRS) is distinguished from a cell-specific reference signal (CRS) in that: it is a measurement RS carried by an analog beam and is used when two or more analog beams non-jointly cover the cell coverage to serve one cell. BRSs may be carried by such beams and may be used to measure Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), or Received Signal Strength Indication (RSSI).

Embodiment 1: considering only the RS in the measurement slot (SS configured only) ]

Fig. 1 illustrates a measurement time slot according to an embodiment of the present disclosure.

Referring to fig. 1, a measurement time slot is shown. In a beam scanning slot, the gNB TX transmits beams each containing a BRS, and simultaneously scans the beams in sequence. While the gNB is performing TX scanning, the RX receives a specific beam and measures BRS. Alternatively, the UE may scan the RX beam when the gNBTX repeatedly transmits a beam containing the BRS. The method is suitable for the situation of RS resource change and the situation of synchronization judgment. In either case, a term during which the measurement can be performed on all combinations of the TX beam and the RX beam is referred to as term 1, and the following specific time may be a plurality of terms.

[ calculation for each beam pair of 1 TX beam and 1 RX beam ] counts the values in different time periods, respectively: out-of-sync (OOS) is determined when N-best measurement values among measurement values of all TX-RX beam pairs measured within a specific time are less than a preset threshold. Here, the measurement values in term 1 for a TX-RX beam pair and the measurement values in term 2 for the same TX-RX beam pair are considered to be different, and the measurement values in all terms for each beam pair are processed separately. If the N best measurements are less than an out-of-synch (OOS) threshold, then the determination is OOS.

B. [ calculation for each combination of 1 TX beam and M RX beams ] count the values in different time periods respectively: for each TX beam, first M RX beams are selected, and the average (or linear combination) of the measurements of the M RX beams is calculated for a particular time. Here, the average value (or linear combination value) in term 1 for a TX beam and the average value in term 2 for the same TX beam are considered to be different. OOS is determined if the N-best of the average of all TX beams is less than the OOS threshold. Here, the value of M may be given or may be selected for each terminal based on a certain criterion.

[ calculation for each beam pair of 1 TX beam and 1 RX beam ] count values in different time periods, respectively: in the "a" case, the average (or linear combination) of the measurements of the N selected beams is calculated. If the average (or linear combination value) is less than the OOS threshold, then it is determined to be OOS.

[ calculation for each combination of 1 TX beam and M RX beams ] separately count values in different time periods: in the "B" case, the average (or linear combination) of the N selected values is calculated. If the average (or linear combination value) is less than the OOS threshold, then it is determined to be OOS. Here, the value of M may be given or may be selected for each terminal based on a certain criterion.

Average in terms of lifetime [ calculation for each beam pair of 1 TX beam and 1 RX beam ]: a linear combination of the measured values of all TX-RX beam pairs is calculated for each epoch within a particular time. If none of the N-best values of the linear combination values in terms of deadline is greater than the OOS threshold, then the determination is OOS. Here, the value of M may be given or may be selected for each terminal based on a certain criterion.

Average in terms of lifetime [ calculation for each combination of 1 TX beam and M RX beams ]: for each TX beam, M RX beams are first selected. A linear combination of the measurements of the M RX beams is calculated for each time frame within a particular time. If none of the N best values in the linear combination in terms of deadline is greater than the OOS threshold, then the determination is OOS. Here, the value of M may be given or may be selected for each terminal based on a certain criterion.

G. [ calculation for each beam pair of 1 TX beam and 1 RX beam ]: in the "E" case, a linear combination of the N best values is calculated. If the linear combination value is less than the OOS threshold, it is determined to be OOS. Here, the value of M may be given or may be selected for each terminal based on a certain criterion.

[ calculation for each combination of 1 TX beam and M RX beams ]: in the "F" case, a linear combination of the N best values is calculated. If the linear combination value is less than the OOS threshold, it is determined to be OOS. Here, the value of M may be given or may be selected for each terminal based on a certain criterion.

Embodiment 2: RS present in the scheduled analog beam in addition to the measurement slot (CSI-RS configured) ]

In this case, information on the RS resource location at the scheduled TX beam should be shared in advance.

Fig. 2 illustrates a case where measurement values for a scheduled beam are added as samples in addition to measurements in a measurement time slot within a given duration according to an embodiment of the present disclosure.

Referring to fig. 2, for a given time, the measurement values for the scheduled beams are added as samples in addition to the measurements in the existing measurement slots. The above cases (a to H) described in the first embodiment are directly applied to the rest. The measurements of the scheduled TX beam and the associated RX beam and the measurement results of the BRS are added to the case of the first embodiment. When performing the calculation, the measurement values of the added beam pairs of the TX beam and the RX beam are added to the previous calculation result.

For example, multiple BRSs may be transmitted simultaneously and as a Synchronization Signal (SS). A subset of the base station's data TX beams may be radiated simultaneously for one SS transmission. In this case, measurements may be made on the SS and the measurements may be used to find a refined TX beam, and control and data may be sent via the refined TX beam. Here, the reference signal indicating that the PDCCH is supposed to be transmitted may be the SS itself or a data TX beam constituting the SS.

Fig. 3 illustrates the simultaneous use of multiple data TX beams to transmit a Synchronization Signal (SS) in accordance with an embodiment of the present disclosure.

Referring to fig. 3, an SS is transmitted as a composite beam using multiple (e.g., 3) data TX beams simultaneously. The same synchronization signal is transmitted through the beams and the terminal sees the same synchronization signal within the beam coverage. The terminal achieves timing synchronization with the cell by measuring the SSs transmitted through the synthesized beam. At the same time, the terminal performs measurements to find the desired data TX beam in the synthesized beam.

Fig. 4 illustrates a case where a base station configures a separate reference signal for a data TX beam constituting a corresponding SS and transmits the reference signal to a terminal together with configuration information in order to continuously report SS measurement results according to an embodiment of the present disclosure.

Referring to fig. 4, the terminal 405 sequentially measures SSs (in

operations

421, 422, 423) and reports the measurement results (e.g., the SS having the strongest received signal strength) to the base station 410 (in operation 425). The base station 410 configures (at operation 431) a separate reference signal (referred to as an additional RS, abbreviated as "aRS") in a data TX beam forming the SS and transmits the information to the terminal 405. Upon receiving the information, the terminal 405 measures (in

operations

433, 434, 435) the aRS in the SS (operation 441) and reports (in operation 443) the measurement result to the base station. The base station 410 determines (at operation 451) a beam for data/control transmission. When the base station 410 transmits (at operation 453) the determined beam indication to the terminal 405, the terminal identifies a DLTX beam indicated by the beam indication. The terminal 405 then receives the data/control information via the identified beam. In this process, one or both of SS and aRS may be used as a reference signal for an in-sync (IS)/out-of-sync (OOS) decision. In the description, the terms "aRS" and "CSI-RS" may be used interchangeably.

If only the SS is configured, the SS may be used in place of the BRS in the OOS determination in the first embodiment of the present disclosure. The signaling of the required information when only the SS is used is shown below.

The measurement of each beam is described next from another perspective.

In LTE radio link monitoring, an OOS indication is generated if the Q _ out threshold is not exceeded for the duration T _ out (═ 200 ms). In this case, since the RS is generated on a symbol basis in each subframe, the reception intensity will be measured at different time points and have different values for measuring the reception intensity within 200 ms. Since this is a UE implementation problem with a certain value as a representative value, various options are possible, but most of the options will assume that the average value of each symbol is the representative value. In the case of synchronization, if the Q _ in threshold IS exceeded for a duration T _ in (═ 100ms), an IS indication IS generated.

If the xSS is set as a target of the RLM, the symbol position (time and frequency) of the xSS may be known in advance or may be notified by the network through a broadcast channel or a dedicated signal. Based on this information, the receive strength of the xSS is measured for each symbol. If it is known through network information that the xSS symbol is transmitted via one particular beam, only the symbols transmitted via the corresponding beam are considered (without unconditionally comparing the average value of the xSS symbols within T _ out with a threshold), the terminal can regard it as a synchronous decision element if its value is greater than Q _ in and as an asynchronous decision element if its value is less than Q _ out.

Fig. 5 illustrates the difference in Radio Link Monitoring (RLM) operation between an LTE operating beam and an NR (new radio) operating beam according to an embodiment of the present disclosure.

Referring to fig. 5, the difference in RLM operation between LTE and NR operating beams is shown. Reference numeral 510 denotes an OOS decision in LTE, and reference numeral 520 denotes an OOS decision in NR. It is checked whether the terminal is able to identify the beam carrying the xSS. If the terminal cannot recognize such a beam, the base station should provide necessary information to enable the terminal to recognize the beam. Here, an xSS transmitted by one xSS block or one set of xSS blocks may be referred to as "per beam xSS".

[ embodiment mode 2-1: SS is the RLM target only

More specifically, the received signal strength of an xSS transmitted by one beam is referred to as "received strength per beam xSS". Here, the reception strength of each beam xSS may be an average of reception strengths of xsss transmitted by one beam, a linear combination of the reception strength with a specific weight, or a value depending on implementation. To issue an out-of-sync (OOS) indication, the terminal determines whether the received strength of each beam xSS is greater or less than Q out, taking into account all xSS transmitted within T out. If the reception strength per beam xSS of all beams transmitted within T _ out is less than Q _ out, the terminal issues an OOS indication to a higher layer. As another example, the network may set the value of N individually, issuing an OOS indication if the received strength of each of the N beams xSS is less than Q _ out. Here, since the number of beams carrying the xSS may be different in different base stations, OOS decision has to be performed more flexibly. In this regard, the base station may adaptively determine the value of T _ out for the number of operating beams.

Likewise, an in-sync (IS) indication may be issued by using the received strength of each beam xSS. To issue the IS indication, the terminal determines whether the received strength of each beam xSS IS greater or less than Q _ in, taking into account all xsss transmitted within T _ in. If the receiving intensity of each beam xSS of any beam transmitted in T _ in IS greater than Q _ in, the terminal issues an IS indication to a higher layer. As another example, the network may set the value of N individually, issuing an IS indication if the received strength of each of the N beams xSS IS greater than Q _ in. Here, since the number of beams carrying the xSS may be different in different base stations, the IS decision must be performed more flexibly. In this regard, the base station may adaptively determine the value of T _ in for the number of operating beams.

Fig. 6 depicts signaling between a terminal and a base station for radio link monitoring with an xSS according to an embodiment of the disclosure.

Fig. 6 depicts a base station signaling parameters needed for radio link monitoring with an xSS.

In operation 620, the base station 610 may transmit parameters required for RLM to the terminal 605. The base station 610 may inform the terminal 605 of the SS configuration information and RLM/RLF parameters (the number of beams required for OOS and IS decisions, the threshold information required for OOS and IS decisions, the duration (T _ out) required for generating one OOS indication, the duration (T _ in) required for generating one IS indication, the RLF timer value, the number of consecutive OOS and IS indications required to start and stop the RLF timer). The base station 610 may inform the terminal 605 of the RLM/RLF parameters through system information, broadcast signaling, or UE-specific signaling. The terminal 605 may have at least one of RLM/RLF parameters as a default value in advance. For RLM/RLF parameters that are not configured by the base station 610, the terminal 605 can use corresponding default values. When the RLM/RLF parameters are newly configured, the terminal 605 can use the updated parameters.

The xSS configuration information may include a beam ID (or corresponding time, frequency, and resource information) of a beam carrying an SS to be measured for the RLM, or time and frequency dependent SS location information of the SS resource to be measured in the corresponding beam. T _ out or T _ in IS the duration required for generating an OOS or IS indication. N is used to specify the number of beams in a per beam measurement within one T out or T in for which the measurement is above a threshold. That is, in the case of OOS determination, if the measurement results of N or more beams are higher than a threshold, it is not OOS. In the case of an IS decision, if the measurement results of N or more beams are above a threshold, it IS. The RLF timer value and the number of consecutive OOS and IS indications needed to start and stop the RLF timer may also be sent as parameters. If the xSS belongs to the band of one parameter set, the necessary information can be immediately transmitted without additional configuration in the connected state, as shown in fig. 6. When the xSS spans a band with multiple parameter sets for a cell, the parameters described above for the active bandwidth slice (BWP) assigned to the terminal 605 may be sent via UE-specific messages if the terminal has access to a limited number of BWPs at a time and the BWPs may have different parameter sets. The base station 610 transmits (at

operations

631, 632, 633, 634) the xSS block signal to the terminal 605.

Especially for the threshold, the base station may transmit a threshold (RSRP, RSRQ, signal-to-interference-plus-noise ratio (SINR), or RSSI) corresponding to a given BLER for the measurement result of the RS to the terminal to measure that the specified xSS block signal is transmitted for the hypothetical PDCCH at the physical layer. Alternatively, the target BLER for the hypothetical PDCCH transmission may be transmitted to the terminal. Upon receiving this value, the terminal measures (at operation 640) the xSS block for the given BLER to generate an OOS or IS indication since the terminal knows the relationship between the xSS block signal measurement value and the given BLER. In addition, the base station may transmit a randomly selected threshold or BLER value, or may transmit a value selected from a predefined set of threshold or BLER values.

In this case, the OOS indication and the IS indication can be independently generated according to the situation. Due to UE signaling overhead or implementation difficulty, there may be a minimum time gap between OOS/IS indications.

[ embodiment modes 2 to 2: CSI-RS Change to RLM target

If the CSI-RS IS used for radio link monitoring, the received signal strength of the CSI-RS contained in a beam carrying the CSI-RS instead of the xSS IS compared with a threshold value for OOS or IS decision. Here, the CSI-RS may be terminal-specific or cell-specific. In any case, the base station must transmit CSI-RS configuration information to the terminal. The CSI-RS configuration may be event driven, periodic or aperiodic. The terminal should know whether the configured CSI-RS belongs to a specific beam. If the terminal knows the mapping between the beams and the CSI-RS, the terminal may consider the reception strength of the CSI-RS per beam as described previously in the case of xSS. Here, the reception strength of the CSI-RS per beam corresponds to an average (or linear combination) of the reception signal strengths of the CSI-RSs transmitted by the respective beams.

To issue an out-of-sync (OOS) indication, the terminal determines whether the reception strength of the per-beam CSI-RS is greater or less than Q _ out, considering all CSI-RSs transmitted within T _ out. And if the receiving strength of each beam CSI-RS of all beams transmitted in the T _ out is less than Q _ out, the terminal issues an OOS indication to a higher layer. As another example, the network may set the value of N separately, issuing an OOS indication if the received strength of the per-beam CSI-RS of the N beams is less than Q _ out. Here, since the number of beams carrying CSI-RS may be different in different base stations, OOS decision has to be performed more flexibly. In this regard, the base station may adaptively determine the value of T out for the number of operating beams.

Also, an in-sync (IS) indication may be issued by using the reception strength of the per-beam CSI-RS. To issue the IS indication, it IS determined whether the reception strength of the CSI-RS per beam IS greater or less than Q _ in, considering all CSI-RSs transmitted within T _ in. And if the receiving strength of each beam CSI-RS of any beam transmitted in the T _ in IS greater than Q _ in, the terminal issues an IS indication to a higher layer. As another example, the network may set the value of N separately, issuing an IS indication if the reception strength of the per-beam CSI-RS of the N beams IS greater than Q _ in. Here, since the number of beams carrying CSI-RS may be different in different base stations, it IS necessary to perform IS decision more flexibly. In this regard, the base station may adaptively determine the value of T _ in for the number of operating beams, as shown in fig. 7. To this end, the RLF timer value and information about the continuous OOS and IS indications needed to start and stop the RLF timer may be transmitted as parameters.

Fig. 7 depicts a case where a T _ in value is adaptively managed according to the number of operating beams according to an embodiment of the present disclosure. Specifically, the base station may inform RLM-related parameters together with CSI-RS configuration information whenever UE-specific CSI-RS is newly configured. In operation 720, the base station 710 may transmit parameters required for RLM to the terminal 705.

Referring to fig. 7, when the CSI-RS IS configured, the base station 710 notifies CSI-RS configuration information (an ID of the configured CSI-RS, or beam time-frequency information and resource location information) and RLM/RLF parameters (the number of beams required for OOS and IS decision, threshold information required for OOS and IS decision, a duration (T _ out) required for generating one OOS indication, a duration (T _ in) required for generating one IS indication, an RLF timer value, and the number of consecutive OOS and IS indications required for starting and stopping an RLF timer) to the terminal 705. The base station 710 may inform the terminal 705 of the RLM/RLF parameters through system information, broadcast signaling, or UE-specific signaling. The terminal 705 may have at least one of RLM/RLF parameters as a default value in advance. For RLM/RLF parameters that are not configured by base station 710, terminal 702 can use corresponding default values. When the RLM/RLF parameters are newly configured, the terminal 705 may use the updated parameters. If the terminal 705 has access to a limited number of Bandwidth Slices (BWPs) at one time, the BWPs may have different sets of parameters and different CSI-RS settings may be given accordingly. The parameters described above for the active BWP assigned to the terminal 705 may be sent via UE-specific messages. That is, in fig. 7, if the CSI-RS configuration changes in the same BWP, it may be applied at the reconfiguration time. The information given in fig. 7 may be carried by a message informing a corresponding BWP if the CSI-RS is configured to use another BWP. Alternatively, if the CSI-RS is configured to use another BWP, the information given in fig. 7 may be carried by a dedicated message after the terminal accesses the corresponding BWP. The base station 710 transmits (in

operations

731, 732, 733, 734) the CSI-RS to the terminal 705.

Especially for the threshold, the base station 710 may send a threshold (RSRP, RSRQ, SINR or RSSI) corresponding to a given BLER for measurement results of the RS to the terminal 705 to measure that a prescribed CSI-RS signal is sent for the hypothetical PDCCH at the physical layer. Alternatively, the target BLER for the hypothetical PDCCH transmission may be sent to the terminal 705. Upon receiving this value, since the terminal 705 knows the relationship between the CSI-RS measurement value and the given BLER, the terminal measures the CSI-RS for the given BLER to generate an OOS or IS indication (740). In addition, base station 710 may transmit a randomly selected threshold or BLER value, or may transmit a value selected from a predefined set of threshold or BLER values.

In case only aRS is used, since aRS does not occur within a consistent time period, the aRS is measured when downlink transmission occurs and a corresponding beam is received. Regardless of the number of samples, issuing an OOS indication if the time-averaged received strength over the most recent time period does not exceed the OOS threshold; if it exceeds the IS threshold, an IS indication IS issued.

[ embodiment modes 2 to 2: both SS and CSI-RS for RLM

The RLM/RLF parameters may be different for different RSs

For SS, the T _ out/T _ in time window IS larger than that of CSI-RS using narrow beams, since OOS/IS must be determined by omni-directional beam scanning with wide beams. The CSI-RS beams are not any narrow beams available but a small number of beams allocated by the base station to data and control channels, so T out/T in is typically small depending on the number of beams. As an opportunity to check whether the current situation is synchronous or asynchronous, the T out/T in time windows may be different for SS and CSI-RS within the same time period. When the channel condition becomes worse, considering waiting for the SS or CSI-RS the same number of times, the RLF time value for the SS is larger and the RLF time value for the CSI-RS is smaller.

When both RSs issue the same indication to RRC (i.e. only consider N between RSs of the same type):

the xSS and CSI-RS may be used simultaneously for radio link monitoring. In this case, RS configuration information and OOS/IS threshold values can be set for the xSS and CSI-RS, respectively. The values of T _ out, T _ in, and N in the OOS/IS determination may be set for the xSS and CSI-RS, respectively, or the same value may be set for them. The timer value or the number of consecutive indications may also be set for the xSS and the CSI-RS, respectively. The OOS/IS indication may be generated independently of the RS if all parameter values are set for the xSS and CSI-RS, respectively. Here, when the RLF timer is active in RRC, the indication of whichever RS is identified as the same indication. In other words, if the OOS indication is first generated from the xSS and then from the CSI-RS, the RRC may consider the two OOS indications to be the same type of indication and consider them to be consecutive OOS indications, as is the case with LTE N310. Likewise, even if IS indications occur according to different settings, RRC may consider them to be the same type of indication.

When both RSs issue a unified indication to the RRC (i.e. from the perspective of a unified RS):

for the OOS processing, the values of T _ out, T _ in, and N in the OOS/IS determination may be set in a consistent manner for the xSS and CSI-RS. In this case, considering CSI-RS beams and xSS beams received within T _ out, if the reception strength of each beam RS of the N beams (here, the RS may be xSS or CSI-RS) is less than Q _ out, an OOS indication is generated. Here, OOS thresholds can be set for the xSS and CSI-RS, respectively, and the values of N and T _ out are the same for whichever type of RS.

For IS processing, the values of T _ out, T _ in, and N in the OOS/IS decision may be set in a consistent manner for the xSS and CSI-RS. In this case, considering CSI-RS beams and xSS beams received within T _ in, if the reception strength of each beam RS of the N beams (here, the RS may be xSS or CSI-RS) IS greater than Q _ in, an IS indication IS generated. Here, the IS threshold may be set for the xSS and CSI-RS, respectively, and the values of N and T _ in are the same for any type of RS.

a. Averaging measurements of two RSs prior to OOS/IS decision

If SS and aRS are used, SS samples are accumulated using the BRS OOS decision method of the present disclosure, and as aRS is transmitted and measured, aRS samples are further accumulated to an accumulated SS value. Here, for the integration, the measurement value of aRS is linearly combined with the integrated value of SS.

Priority setting when multiple RSs are configured simultaneously

If two RSs are configured for RLM, the network can signal which RS has priority. The OOS or IS indication may then be sent to the RRC at signaling time according to the measurement result for the RS having priority. Alternatively, in case that a specific RS IS not given priority, an OOS or IS indication may be transmitted to the RRC according to a measurement result of another RS by referring to a measurement result of one RS. This classification scheme will be described below.

1) OOS decision priority of SS

As another way to use SS and aRS together, a hierarchical decision can be made. If it is determined to be OOS only on the basis of the measurement values of the SS, an OOS indication is sent to the RRC and no further consideration of aRS is required. If IS determined on the basis of the measurement values of SS only, the measurement values of aRS are further considered. That IS, if the measurement result of the aRS IS less than or equal to a given threshold, the OOS indication IS transmitted to the RRC, otherwise the IS indication IS transmitted to the RRC. In this case, the measurement values of the aRS are linearly combined with each other, and the measurement values of the SS are accumulated between the SS measurement values, like the first BRS OOS decision scheme of the present disclosure.

2) IS decision priority of SS

If IS determined only on the basis of the measured values of SS, an IS indication IS sent to RRC and no further consideration of aRS IS needed. If it is determined to be OOS only on the basis of the measurement values of SS, the measurement values of aRS are further considered. That IS, if the measured value of aRS IS less than or equal to a given threshold, the OOS indication IS sent to the RRC, otherwise the IS indication IS sent to the RRC. In this case, the measurement values of aRS are linearly combined with each other, and the measurement values of SS are accumulated between the SS measurement values, like the first BRS OOS decision scheme of the present disclosure.

3) OOS decision prioritization for CSI-RS

If it is determined to be OOS only on the basis of the measurements of CSI-RS, an OOS indication is sent to RRC and no further consideration of SS is required. If it IS determined to be IS only on the basis of the measurement values of CSI-RS, the measurement values of SS are further considered. That IS, the OOS indication IS transmitted to the RRC if the measurement result of the SS IS less than or equal to a given threshold, and the IS indication IS transmitted to the RRC otherwise. In this case, the measurement values of aRS are linearly combined with each other, and the measurement values of SS are accumulated between the SS measurement values, like the first BRS OOS decision scheme of the present disclosure.

4) IS decision prioritization for CSI-RS

If it IS determined to be IS only based on the measurement values of CSI-RS, an IS indication IS sent to RRC and no further consideration of SS IS required. If it is determined to be OOS only on the basis of the measurement values of CSI-RS, the measurement values of SS are further considered. That IS, the OOS indication IS transmitted to the RRC if the measurement result of the SS IS less than or equal to a given threshold, and the IS indication IS transmitted to the RRC otherwise. In this case, the measured values of aRS are linearly combined with each other, and the measured values of SS are accumulated between the measured values of SS, like the first BRS OOS decision scheme of the present disclosure.

5) Indexing scheme

For the hierarchical approach described above, an index may be assigned to each combination in advance and the network may specify the corresponding rule. An example of this is shown in table 1 below.

[ Table 1]

Indexing

Results

First time examination

Second inspection

Examples of the invention

1

OOS

SS OOS

CSI-RS OOS

5-1

2

IS

SS IS

CSI-RS IS

5-2

An OOS indication is unconditionally generated if the first check on a particular RS yields the result of the indication. If the first check does not yield an indicated result, the second check is considered. If the second check yields the result of the indication, the OOS indication is generated again. Otherwise, a complementary result is generated as the OOS. When the base station transmits this information, the terminal determines a cell-wise RLM result based on the RLM results of the two RSs by using the received information, and notifies the RRC of the cell-wise RLM result.

6) Transmitting an offset as a threshold when two RSs are simultaneously configured

When two RSs are used simultaneously, the threshold value of each RS may be an absolute value. However, it is also possible that one threshold value is an absolute value and the other threshold value is an offset value.

When the base station transmits the parameter set corresponding to each RS to the terminal, the threshold value may be given as an absolute value. If a threshold value for one RS has been given, a threshold value for another RS can be given as an offset from the threshold value that has been given. For example, when the aRS and the SS are simultaneously used, they are different in beam width and the number of member beams. Therefore, in order to add the measurement value of the aRS reception beam to the measurement value of the SS reception beam, or to make a decision based on a specific threshold, an offset to be added to the reception signal strength may be required. This offset may be added to the measurement value of the aRS to generate a received signal strength value of the SS as a consistency metric. This measure of agreement may be compared to a given threshold. To this end, the base station may transmit a required offset value to the terminal.

Fig. 8 depicts a case where a base station transmits information on offset values set for a specific DL TX beam as system information and a terminal uses this information whenever a DL TX beam set is configured according to an embodiment of the present disclosure.

Referring to fig. 8, offset values are set for specific DL TX beams, a base station 810 transmits offset information as system information, and a terminal 805 applies this information whenever a DL TX beam set is configured. The base station 810 transmits the offset value as system information to the terminal 805 (in operation 821), and the base station 810 transmits SSs in time or frequency order in an always-on mode (in operation 823). When the terminal measures the SS and reports the best SS to the base station 810, the base station 810 configures an aRS at a DLTX beam constituting the best SS and transmits aRS location information to the terminal 805 (at operation 825). The terminal 805 performs measurements based on this information and sends the measurement results to the base station 810. The base station then selects (at operation 827) a DL TX beam. Here, when the number of beams selected for DL transmission and the corresponding beam IDs are known, an offset value to be applied when a specific beam is measured can be identified. After finding (in operation 829) a new beam, if the DL TX beam is changed (in operation 831) while calculating the aRS metric, the target for the aRS metric calculation should be changed from beam set 1 to beam set 2 (in operation 833) based on the corresponding indication.

Table 2 below shows an example of representing this relevant information.

[ Table 2]

When two DL TX beams (beam 1 and beam 2) are selected, the value obtained by adding-5 dBM to the measurement values of beam 1 and beam 2 can be linearly combined with the measurement value of the SS.

As another example of signaling, the above information may be transmitted through RRC dedicated messages.

Fig. 9 depicts a case where beam offset information is transmitted through an RRC dedicated message according to an embodiment of the present disclosure.

The base station 910 may transmit offset information transmitted via system information in fig. 8 via an RRC dedicated message, and the terminal 905 applies this information. Since the best SS has been determined, the offset value of the DL TX beam corresponding to the best SS may be transmitted. For example, if SS1 is selected and reported as the best SS, the base station may provide an offset value for the DL TX beam corresponding to SS1, as shown in table 3 below. For operations 921 to 931 other than operation 925, see the corresponding operations in fig. 8.

[ Table 3]

Fig. 10 depicts a case where the correlation offset information is transmitted through a physical layer control channel according to an embodiment of the present disclosure.

Referring to fig. 10, the present embodiment can transmit offset information faster than other layers. For example, the base station 1010 may inform the terminal 1002 of the selected DL TX beam through the PDCCH (at operation 1023), and may also transmit an offset of each beam. In this case, since the base station can know the selected DL TX beam, it does not have to transmit an offset through downlink transmission related to other SSs. In addition, if the DL TX beam set is changed, the base station may quickly transmit (at operation 1027) the required offset information. For

operations

1021, 1025, and 1029, see corresponding operations in FIG. 8.

As another option, fig. 11 depicts a case where the relevant offset information is transmitted through a MAC (medium access control) CE (control element) according to an embodiment of the present disclosure.

Referring to fig. 11, a base station 1110 transmits (in operations 1123, 1127) relevant offset information to a terminal 1105 through a MAC CE. In notifying the DL TX beams, offset values associated with the number and ID of the selected DL TX beams may be notified via the MAC CE. For

operations

1121, 1125, and 1129, see corresponding operations in FIG. 8.

When only one of the SS and the CSI-RS is a target of the RLM, the parameter set of each RS may be transmitted through system information or through dedicated signaling. When most terminals can perform RLM using CSI-RS and SS and their terminal capabilities can support two RSs, information transmission overhead can be reduced by using system information.

However, a specific terminal may report the measurement result of only one of the two RSs. A terminal operating on a particular bandwidth slice may only need information related to CSI-RS if the bandwidth slice can carry only CSI-RS (no SS). The CSI-RS configuration information and the threshold information required for RLM assigned to the active bandwidth slices can also be changed by different sets of parameters. The bandwidth fragmentation used by the terminal may change over time. In these cases, the base station may transmit CSI-RS configuration information using UE-specific signaling when the corresponding bandwidth slice IS used, as well as information related to the value of N, the threshold (absolute value or offset), T _ out, T _ in, the RLF timer value, and the number of consecutive indications in the OOS/IS decision.

7) Applying RLF parameters when multiple RSs are configured simultaneously

The RLF timer may be started or stopped when a continuous OOS or IS indication IS sent from the physical layer (PHY) to the RRC. If only one RS is configured, or only one RS has priority and has no change for a period of time although two RSs are configured, the RLM operation and the RLF operation may be performed by inheriting the RLF parameters of the respective RSs. However, when a plurality of RSs are configured, if the RLM RS is changed from a previous RS to a new RS, it is necessary to determine whether to apply the RLF parameters associated with the new RS after inheriting the state of the RLF parameters associated with the previous RS or whether to apply the RLF parameters associated with the new RS after resetting the state of the RLF parameters associated with the previous RS.

For this reason, the RRC needs to know the RS that caused the OOS or IS indication. As an option, the PHY may send an OOS or IS indication with an RS flag. That IS, the PHY may send an SS OOS or IS indication to the RRC, and when the CSI-RS IS configured, it may send a CSI-RS OOS or IS indication to the RRC. As another option, without the RS flag, the RRC may identify an OOS or IS indication as being associated with the RS having priority, where the OOS or IS indication IS received from the PHY after the RS having priority IS configured according to a preset priority rule.

Fig. 12 illustrates a scheme in which a physical layer provides a per RS indication or an aggregation indication to a higher layer (RRC) according to an embodiment of the present disclosure.

Referring to fig. 12, a physical layer may provide a per RS indication or an aggregation indication to a higher layer (RRC). When the per-RS indication is used, the PHY performs RLM for all RSs regardless of priority and transmits each indication with an RS flag to a higher layer, and the RRC checks the RS flag and applies RLF parameters associated with the RS with priority. When the aggregated indication is used, the PHY performs RLM only for the prioritized RS, and the RRC may recognize the indication received after the prioritized RS is configured and apply RLF parameters associated with the prioritized RS.

If the RRC distinguishes the indication in the above method, the corresponding RLF parameter may be applied as follows.

-applying conditions of different RLF parameters

In the terminal, there may be a case where the CSI-RS IS and the associated SS IS not always IS.

Fig. 13 illustrates a case where a CSI-RS pair terminal IS and a related SS IS not an IS according to an embodiment of the present disclosure.

Referring to fig. 13, although a majority of wide beam 1305 carrying an SS is blocked by building 1320, one narrow beam 1310 of the wide beam may not be blocked by building 1320. In this case, although the reception strength of the SS may be extremely low, the CSI-RS beam 1 may not be at all problematic. The channel status must be checked independently for each RS. This situation will be solved by resetting the parameters between RSs.

On the other hand, the remaining CSI-RS beams share the same channel state (OOS) with the SS, and T _ IS used for SS IS decision will be longer than T _ IS used for CSI-RS IS decision. Therefore, if the required number of IS indications IS met, it makes sense to make a synchronization decision. Upon determining that the correlation between the received signal strengths of the SS beam and the CSI-RS beam is high based on the existing beam measurements, the network may indicate a state indicating that the terminal inherits the existing parameters. Upon determining that the above correlation is not high and that the service is not delay sensitive, the network may instruct the terminal to reset the state of the existing parameters.

-number of consecutive indications

There is a number of consecutive indications in the RLF parameter for each RS. When the CSI-RS is configured at a specific time point when RLM is performed for the SS, it may be assumed that a policy of CSI-RS precedence is set at the time point.

Fig. 14 illustrates a strategy for performing RLM in a CSI-RS prioritized manner when a CSI-RS is configured at a specific time point when RLM is performed by an SS according to an embodiment of the present disclosure.

Referring to fig. 14, for the scenario indicated by reference 1410, assume that 3 consecutive OOS indications for the SS are needed to start the RLF timer and 2 consecutive OOS indications for the CSI-RS are needed to start the RLF timer. Assume that 2 consecutive OOS indications for an SS are generated before the CSI-RS is configured. When the RLM status (cumulative number of existing indications) is inherited, even if only one OOS indication for the CSI-RS occurs after the CSI-RS configuration, the RRC knows that the cumulative number of OOS indications is 3 and starts the RLF timer. When the RLM status is reset, the RRC starts an RLF timer when 2 consecutive OOS indications for the CSI-RS are received after the CSI-RS configuration.

For the case indicated by reference 1420 in fig. 14, the RLF timer may be started after the CSI-RS IS configured, and in the case where the CSI-RS IS released when the IS indicates that the CSI-RS IS generated based on the CSI-RS, the RLM may be performed again based on the SS. To stop the RLF timer, the RLM status (cumulative number of existing indications) may be inherited or reset. When inherited, the number of existing IS indications for CSI-RS IS maintained, and when SS indications for SS are present, the RLF timer IS stopped according to the cumulative number of consecutive IS indications regardless of RS type. When reset, the number of existing IS indications for the CSI-RS IS ignored and the number of consecutive IS indications IS counted for the SS to stop the RLF timer.

-timer value

The RLF parameter for each RS has a timer value. When the CSI-RS is configured at a specific time point at which the RLM is performed based on the SS, it may be assumed that a policy of CSI-RS precedence is set at the time point. In fig. 15, for the scenario indicated by reference numeral 1510, the terminal has started an RLF timer according to the OOS indication for the SS. Then, when the CSI-RS is configured, the RLM state (timer value) may be inherited or reset. When the timer value IS inherited, the RLF timer runs until the CSI-RS generates a given number of IS indications by continuously applying the SS RLF timer value or until the timer value expires.

In another embodiment, when the CSI-RS is configured, only the timer value for the CSI-RS is changed, and the past timer value may be inherited as it is. When the parameter is reset, the preamble timer is reset when the CSI-RS is configured. The timer IS stopped if the CSI-RS measurement generates an IS indication and started if the CSI-RS measurement generates a preset number of consecutive OOS indications.

Fig. 15 illustrates a strategy for performing RLM in a CSI-RS prioritized manner when a CSI-RS is configured at a specific time point at which RLM is performed by an SS according to an embodiment of the present disclosure.

Referring to fig. 15, for the case indicated by reference 1520, the CSI-RS IS configured, the RLF timer for the CSI-RS IS running, the CSI-RS measurement generates an IS indication, and the CSI-RS IS released or not configured. In this case, the timer for the CSI-RS may be reset and the RLF timer for the SS may be newly applied. Alternatively, the CSI-RS timer value may be inherited, and the SS timer may run until the SS measurement generates a preset number of consecutive IS indications or the timer value expires. Alternatively, the past timer values may be inherited, and the remaining timer values may be used for the SS timer. When the SS timer value is used, the SS timer immediately stops and the RLF is declared if the elapsed time has exceeded the SS timer value. Otherwise, the SS timer runs until the remaining timer value expires.

-informing RLF parameters application options

For the above two parameters, static rules may be used, or the network may dynamically set the rules and inform the terminal of them. In this case, the network may attach a reset/inherit indication to each of the two parameters and send this configuration information via, for example, an RRC connection reconfiguration message.

Fig. 16 depicts a case where a base station configures specific bandwidth fragmentation based on the capabilities and service requirements of a terminal according to an embodiment of the present disclosure.

If a type of RS is configured in the current active bandwidth slice, the terminal 1605 operates according to the RLM/RLF parameters and rules for that RS. If two or more types of RSs are configured in the active bandwidth slice, the terminal 1605 determines an RS type having priority in the bandwidth slice according to priority information between RS types set in advance or configured by the base station 1610, and operates according to RLM/RLF parameters and rules for the determined RS type.

Base station 1610 allows use of a particular bandwidth slice, and if an SS exists in the bandwidth slice, it transmits SS configuration information and corresponding parameters via dedicated signaling (at operation 1621). The base station 1610 transmits CSI-RS configuration information and corresponding parameters if the CSI-RS is to be configured. If two RSs are to be configured (i.e., the SS is transmitted via bandwidth slices and the CSI-RS transmitted via narrowband beams is required for data transmission and reception by the terminal 1605), the base station transmits corresponding configuration information, parameters, and a priority rule for RLM. In addition, the base station may attach an inheritance/reset indication to the parameters whose values are counted at the time of RLF parameter handover.

Referring to fig. 16, the configuration information related to the SS and the RLM/RLF parameter set may be transmitted via a broadcast channel or a shared channel transmitting system information (option 1). Alternatively, the terminal 1605 is given the initial SS-related RLM/RLF parameters, and the SS-related configuration information and the RLM/RLF parameter set may be transmitted via dedicated signaling by using an RRC connection reconfiguration message after RRC connection setup (option 2).

The terminal 1605 transmits (at operation 1623) its capability information (beamforming, preferred bandwidth and frequency) and service information (delay sensitivity) to the base station 1610. Based on the service information, the base station 1610 sends (at operation 1625) a bandwidth slice to the terminal 1605 with a set of parameters matching enhanced mobile bandwidth (eMBB), ultra-reliable low latency communication (URLLC), or large scale machine type communication (mtc). In addition, the base station checks whether the SS exists in the assigned bandwidth slice, and if so, it sends (at operation 1627) the SS-related configuration and corresponding RLM/RLF parameters.

The terminal 1605 then measures (at operation 1629) the SSs in the assigned bandwidth slice and feeds back (at operation 1631) the measurement results to the base station 1610. The base station 1610 may configure (at operation 1633) the CSI-RS. If there is no SS in the assigned bandwidth slice, the terminal may measure the SS in the cell or bandwidth slice associated with the initial RRC connection and send the measurement information to the base station. Alternatively, the base station can configure the CSI-RS without reference to the SS configuration feedback. This CSI-RS will be used in the assigned bandwidth slice.

When the CSI-RS is configured, the base station 1610 notifies (in operation 1635) the terminal 1605 of the corresponding configuration information and parameters and notifies the RS priority index. When it is determined that the correlation between the received signal strengths of the CSI-RS beam and the SS beam is strong based on the service information received from the terminal 1605 and the beam feedback received from other terminals, the base station 1610 transmits an inheritance indication for applying the RLF parameter to the terminal 1605. Otherwise, the base station 1610 sends a reset indication for applying the RLF parameters to the terminal 1605.

Upon receiving the above information, the terminal 1605 communicates via the assigned bandwidth slice and performs RLM (at operation 1637) according to a given priority rule.

RLM/RLF may be performed using only CSI-RS configuration information and parameter information if there is no SS in the corresponding bandwidth slice. As another option, information (frequency, cell ID, or bandwidth fragment ID) on a bandwidth fragment where an SS exists, measurement gap information for measuring the SS, SS configuration information of the bandwidth fragment, RLF parameter information, priority rule information, and reset indication information may be transmitted to the terminal 1605, and the terminal 1605 may be able to measure the SS and CSI-RS while observing 2 bandwidth fragments and perform an RLF operation according to the priority rule and the reset indication in a time division manner. The correlation between the received signal strengths of the SS and the CSI-RS may be weak if the bandwidth fragmentation in which the SS exists and the bandwidth fragmentation in which only the CSI-RS exists are physically separated rather than quasi-co-location or co-location. In this case, the base station 1610 may provide a reset indication for applying the RLF parameters.

Fig. 17 depicts a case where UE beamforming related capability information, requested service related information, and preferred bandwidth fragmentation information are transmitted via separate RRC messages after connection setup according to an embodiment of the present disclosure.

Referring to fig. 17, the terminal 1705 may transmit beamforming capability information, required service-related information, and preferred bandwidth fragmentation information to the base station 1710 via a separate RRC message instead of via an RRC connection setup message after connection setup (in operation 1729). When the above information is received before configuring the CSI-RS, the base station 1710 transmits (in operation 1733) the priority rule and the RLF parameter inheritance/reset indication to the terminal 1705 based on the received information.

If the beamforming capability information, the required service related information, and the preferred bandwidth fragmentation information are received after the CSI-RS is configured, the base station 1710 transmits a priority rule and an RLF parameter inherit/reset indication set to preset default values.

As another option, the terminal 1705 may have current default values for the precedence rule and RLF parameter inheritance/reset indication. The terminal 1705 may apply a preset default value if the base station 1710 does not provide a specific value.

For operations 1721-1735, see corresponding operations of FIG. 16.

As another embodiment, if RLF is declared due to an RLM operation performed for each active bandwidth fragmentation (BWP) or other reasons, the terminal switches itself to a preset BWP and attempts to access the preset BWP. If the connection is successful, the terminal does not declare RLF. If the connection is unsuccessful, the terminal may announce RLF and search for a new cell. Here, the preset BWP may be a default BWP or another configured BWP. Accessing the preset BWP may be achieved through the RACH or through a Physical Uplink Control Channel (PUCCH) using a dedicated preamble such as a reconnection indication or a scheduling request.

Specifically, when the terminal performs handover based on BWP, the following embodiments may be added with respect to RLM/RLF operation.

(1) The network may configure the terminal with a radio link monitoring reference signal (RLM-RS). The RLM-RS may be SS (synchronization signal), CRS (cell-specific reference signal), SRS (sounding reference signal), or CSI-RS (channel state information reference signal), or a combination thereof. When the terminal is configured with the RLM-RS, the base station can transmit RS information regarding the time-frequency resource location and the code (if the code is used). When a specific mode is promised between the terminal and the network, mode information may be transmitted. Upon receiving this configuration information, the terminal refers to the time-frequency resources of the RLM-RS and applies the RLM parameters associated with the RS, wherein the physical layer may send an IS (in-sync) indication or an OOS (out-of-sync) indication to higher layers.

The RLM parameters may include an IS threshold (considering RSRP, RSRQ, RSSI, or BLER assuming PDCCH transmission) for generating an IS indication if the received power IS higher than the IS threshold, the number of RSs or beams that should be higher than the IS threshold, an OOS threshold for generating an OOS indication if the received power IS lower than the OOS threshold, the number of RSs or beams that should be lower than the OOS threshold, a time window for IS and OOS measurements, and an interval between IS or OOS indications. This parameter information may be notified by dedicated signaling when, for example, the SS or CSI-RS is configured, or may be notified by using system information via broadcast signaling.

(2) When the network configures the terminal with an RLM-RS, this RS may or may not exist in all the specified Bandwidth Slices (BWPs). Specifically, when the terminal uses a scheduled BWP (active BWP), if there is no RLM-RS in the BWP, the terminal may temporarily switch to the BWP including the frequency location where the RLM-RS exists and receive and measure the RLM-RS to generate the periodicity indication.

Gap to fallback to RLM-RS BWP or active BWP in the above description, switching from originally scheduled active BWP to BWP with RLM-RS is called fallback. The network may provide information such as a backoff time, a dwell time at a backoff BWP, a return time to switch back to the originally scheduled active BWP, and a repetition period of the backoff mode to the terminal. When the configured BWP scheduled by the network based on the time information of the RLM-RS does not include the RLM-RS of the terminal, the network may configure a measurement gap of the RLM within which the terminal does not have to monitor the scheduled active BWP. This measurement gap may be specified by information such as the starting point of the gap, the duration of the gap, and the repetition period.

When a terminal is configured with a measurement gap of RLM, the terminal monitors the currently scheduled active BWP, switches to the RLM-RS configured BWP at the start time of the interval, receives the RLM-RS for the duration of the gap, and switches back to the original active BWP to perform communication.

Fig. 18 shows a case where RLM-RS exists only in one frequency range according to an embodiment of the present disclosure.

Referring to fig. 18, if there is only one RLM-RS, the base station can provide the terminal with RLM-RS configuration (i.e., absolute RLM-RS information) independent of the active BWP currently monitored by the terminal. When an active BWP is scheduled for the terminal, the base station determines (in operation 1905) whether the active BWP has an RLM-RS. If the active BWP has RLM-RS, the base station may skip transmitting backoff information or RLM-RS measurement gap information for the RLM-RS BWP alone (at operation 1910). In this case, the terminal performs RLM (in operation 1915) and does not need to switch to another BWP.

If the scheduled active BWP has no RLM-RS (at operation 1920), the base station transmits backoff information and RLM-RS measurement gap information of the RLM-RS BWP (at operation 1925). Upon receiving this information, the terminal may monitor (at operation 1930) the active BWP, switch to RLM-RS fallback BWP, or receive and measure RLM-RS based on the gap information and return to the original active BWP.

Fig. 19 depicts RLM-RS signaling when an active BWP has RLM-RS and when the active BWP does not have RLM-RS, in accordance with an embodiment of the present disclosure.

Fig. 20 illustrates a case where RLM-RS exists in a plurality of frequency ranges according to an embodiment of the present disclosure.

Referring to fig. 20, if there are a plurality of RLM-RSs, different types of RLM-RSs can be used for an active BWP, and thus different types of RLM BWPs can be used.

For example, RLM-RSs that are close to an active BWP in the frequency domain may be selected and used. In the case of option 2 of fig. 19, instead of the initially configured RLM-RS, a new RLM-RS may be configured based on the active BWP. In addition, the RLM fallback BWP may be configured based on the newly configured RLM-RS. The base station may selectively inform the terminal of this information when active BWP is configured.

For example, if the active BWP is BWP3, the RLM-RS at this time may be the RLM-RS present in BWP4, and the RLM fallback BWP may be BWP 4. This configuration may be set such that the active BWP is BWP1, the fallback BWP is BWP0 and the RLM-RS is the new configuration of RLM-RS present in BWP 0. In fig. 19, it is represented as "RLM-RS configuration" and "RLM fallback BWP based on scheduled BWP". The RLM-RS configuration (second signaling in fig. 19) may refer to all information regarding RLM-RS existing in a corresponding cell. The configuration of the RLM-RS after the active BWP is determined is limited to information about the RLM-RS to be used when the active BWP is used. The latter information takes precedence over the former information.

(3) As indicated in subsection (2), RLM-RS may be present in all BWPs. In this case, instead of switching to a particular BWP to measure RLM-RS, the terminal measures the RLM-RS present in each scheduled active BWP and applies the corresponding RLM parameters to generate an OOS/IS indication.

In the first diagram of fig. 19, when all RLM-RS information is given, since the base station knows that RLM-RS exists in all BWPs, it does not provide RLM-RS information dedicated to active BWPs. The terminal compares the position information of the RLM-RS with frequency information of the active BWP, recognizes that the RLM-RS exists in the active BWP, and performs an RLM operation in the active BWP without performing an operation of a backoff or a measurement gap.

(4) If there is an RLM fallback BWP or RLM measurement gap configuration, the terminal measures RLM-RS at a specified time to generate an indication and operates an RLF timer with application layer 3 parameters based on the indication. However, when active BWPs are scheduled (or switched) and an indication is received due to the presence of RLM-RS in each active BWP as described in section (3), it is chosen whether to inherit or reset the current state when applying the L3 parameters.

If the channel correlation between BWPs is not large, a reset option may be applied; if the channel correlation is large, the inheritance option can be applied. For the number of consecutive IS or OOS indications in the L3 parameters used to start or stop the RLF timer, the terminal inherits the RLF parameter state of the previous active BWP (the number of consecutive IS indications generated in the previous active BWP and the number of consecutive OOS indications generated in the previous active BWP) and uses the same RLF parameter state in the active BWP of the handover.

When the RLF timer has been started in the previous active BWP, the terminal stops the timer if a preset number of consecutive IS indications (including inherited IS indications) are generated from the active BWP of the handover. The terminal keeps the timer running if a preset number of consecutive OOS indications (including inherited OOS indications) are generated from the active BWP of the handover.

The reset option may be applied if the channel correlation between BWPs is not large. In this case, when the active BWP IS switched (or scheduled) to another BWP, the terminal resets the number of consecutive IS indications generated in the previous active BWP to 0 and resets the number of consecutive OOS indications generated in the previous active BWP to 0. If the RLF timer has been started in the previous active BWP, the terminal resets the timer value to an initial value and stops the timer. Then, if a preset number of consecutive IS or OOS indications are generated from the active BWP of the handover, the terminal operates the timer accordingly.

(5) Since various RSs can be used as the RLM-RS as described in section (1), different sets of RLF parameters can be set for different BWPs. When a new active BWP is scheduled, the base station may send at least some of the following values to the terminal as RLF parameters: an IS threshold (considering RSRP, RSRQ, RSSI, SINR, or BLER assuming PDCCH transmission) for generating an IS indication if the received power IS higher than the IS threshold; an OOS threshold (considering RSRP, RSRQ, RSSI, SINR or BLER assuming PDCCH transmission) for generating an OOS indication if the received power is below the OOS threshold; time windows for IS and OOS measurements; interval between IS or OOS indications sent to higher layers; indicating a number of RSs or beams that should be higher than an IS threshold for generating IS; indicate a number of RSs or beams that should be below an OOS threshold for generating OOS; an RLF timer value; a number of consecutive OOS indications to start the RLF timer; and the number of consecutive IS indications to stop running the RLF timer.

Fig. 21 is a block diagram of a base station according to an embodiment of the present disclosure.

Referring to fig. 21, the base station may include a transceiver 2110, a controller 2120 (e.g., at least one processor), and a storage device 2130 (e.g., memory).

In the present disclosure, the controller 2120 may be a circuit, an application specific integrated circuit, or at least one processor.

The transceiver 2120 may transmit and receive signals to and from other network entities. For example, the transceiver 2110 may transmit system information, a synchronization signal, or a reference signal to the terminal.

The controller 2120 may control the overall operation of the base station according to an embodiment of the present disclosure. For example, the controller 2120 may control the flow of signals between blocks to perform the operations described in the flowcharts described above.

In particular, the controller 2120 may control the proposed operations to report radio link problems to higher layers according to embodiments of the present disclosure.

The storage device 2130 may store at least one of information transmitted or received by the transceiver 2110 and information generated by the controller 2120.

For example, the storage 2130 may store information related to events defined to report radio link problems.

Fig. 22 is a block diagram of a terminal according to an embodiment of the present disclosure.

Referring to fig. 22, the terminal may include a transceiver 2210, a controller 2220 (e.g., at least one processor), and a storage 2230 (e.g., memory).

In the present disclosure, the controller 2220 may be a circuit, an application specific integrated circuit, or at least one processor.

Transceiver 2210 may transmit signals to and receive signals from other network entities. For example, transceiver 2210 may receive system information, synchronization signals, or reference signals from a base station.

The controller 2220 may control the overall operation of the terminal according to an embodiment of the present disclosure. For example, the controller 2220 may control the flow of signals between the blocks to perform the operations described in the flowcharts described above.

In particular, the controller 2220 may control the operation of the measurement SS, BRS, etc. related to the radio link according to the embodiment of the present disclosure.

The storage 2230 may store at least one of information transmitted or received through the transceiver 2210 and information generated by the controller 2220.

For example, the storage 2230 may store information needed for radio link monitoring according to embodiments of the disclosure.

As described above, the RLM/RLF parameter may be configured differently according to the type of the RS. The RLM/RLF parameters may also be configured differently according to the type of service.

Fig. 23 depicts a case where RLM/RLF parameters are differently set according to the type of service received by a terminal according to an embodiment of the present disclosure. When the base station 2310 knows the service desired by the terminal 2305, it configures the RLM-RS appropriate for the service and configures RLM/RLF parameters associated with the RLM-RS. Upon receiving the configuration information, the terminal 2305 may perform RLM based on this information and operate a timer to announce RLF according to IS/OOS indications using RLF parameters. Here, the RLM parameters transmitted by the base station 2310 may include RLM-RS configuration information (RS type, RS time-frequency location, threshold to be compared with measurement value of each RS), RLF parameters (RLF timer value, number of consecutive IS indications, number of consecutive OOS indications). Upon receiving this information, the terminal 2305 may identify the location of the corresponding RS and send periodic IS or OOS indications to the RRC based on the given RLM parameters. The RRC layer may stop or start the RLF timer upon receiving a preset number of consecutive IS or OOS indications.

The base station may identify the service type of the terminal in various ways. When a bearer is set for a terminal, an IP address and a port of a corresponding server can be known from a five-tuple of an IP packet of an E-UTRAN radio access bearer (E-RAB) or a flow, and a type of service can be identified from quality of service (QoS) flow information. The base station may know the service type of each bearer from the identified traffic type. If the terminal has multiple bearers for different types of services, the base station may configure the RLM/RLF configuration based on the services with stricter constraints. For example, when a voice over internet protocol (VoIP) service and a general eMBB data service coexist in a terminal, a base station may provide an RLM/RLF configuration based on the VoIP service that is susceptible to a failure due to characteristics of voice traffic.

The following embodiments can be considered as structures that can be included in asn.1 of RRC. Since the Pcell or Pscell performs RLM/RLF operations, the following IEs may be carried by the container used for Pcell/Pscell configuration in RRC messages. The following IE may also be carried by a measConfig IE with RS configuration for mobility.

PCellConfig or measConfig >

RLM-configuration

List of RLM-RSs

■ RLM-resource-config-SS list, e.g. { SSB1, SSB2, SSB5}

■ RLM-resource-config-CSIRS, e.g., {1-2 (for level 2) or 1-1-3 (for level 3), etc. }

-threshold information

■ Pair _ BLER _ ID, e.g., {0 or 1}

The list of RLM-resource-config-SSs may include a list of SSB indices for RLM-RS, time-frequency location information, or repeated pattern information. The list of RLM-resource-config-CSIRS may include a list of pointers to CSIRS resources corresponding to some or all of the CSI-RS currently configured in the Pcell or Pscell, or a list of resources (time-frequency location information, repeated pattern information) of newly added CSI-RS. Pair _ of _ BLER _ ID indicates the ID of a Pair of assumed PDCCH BLER values for IS and OOS decision in a preset Pair of target assumed PDCCH BLER values for the received signal of each RS. This indication may indicate the BLER to be used and the service mapped to the BLER. For example, "0" may indicate a BLER value pair used in LTE and indicate a general service. A "1" may indicate an eMBB or VoIP service and a preset BLER value pair associated with the service. The threshold (or BLER value) information for this particular service may be provided by the base station to the terminal via dedicated signaling. This threshold information may be specified for each service (rather than for each terminal) in this specification. RRC messages or MAC CEs may be used to transmit threshold information specified for each terminal. In another embodiment, if the BLER value is not set, a preset default BLER value may be applied. For example, when the default BLER is LTE BLER, if a terminal in a connected service receives an RS configuration through RLM-config but does not receive a Pair _ of _ BLER _ ID configuration, it may apply LTE BLER by default. If a Pair of BLER ID configuration is provided later, it can be used to override the default BLER. Here, the terminal may consider the service type associated with the default BLER as a default service type.

For RLF parameter signaling related to service types, RLF parameters may be configured for each service type identified by the system, such as the number of consecutive IS or OOS indications for timer operation, timer values, RS measurement time windows (or intervals) for OOS decisions, and RS measurement time windows for IS decisions. These parameters may be transmitted via RLF-timersandstatuses signaling of the CellGroup configuration container in the RRC message, and may be configured and transmitted for each service. Among the parameter values configured for each service, the terminal may select and use an RLF parameter corresponding to a service type mapped with a BLER value selected according to a value indicated by the Pair _ of _ BLER _ ID of RLM-config.

For example, RLF parameters corresponding to normal service and VoIP may be transmitted at once as follows.

The base station may transmit the RLM configuration information when the terminal transitions from the idle state to the connected state or when the terminal makes an initial RRC connection. In case of handover to another cell as shown in fig. 24, the target cell 2415 receives service information of a corresponding terminal from the serving cell 2410, and transmits RLM-RS configuration, BLER setting information, and RLF parameters to the serving cell 2410 based on the received service information. Serving cell 2410 may forward this information via an RRC message. In addition, when the serving cell 2410 recognizes that the service type of the terminal 2405 in a connected state has changed as described above, the serving cell 2410 may transmit new BLER information via an RRC reconfiguration message, or transmit the new BLER information together with information related to the newly configured RLM-RS.

Upon receiving the above configuration information, the terminal checks the RLM-RS configuration information, measures a received signal strength (RSRQ, RSRP, or SINR) of each RS for a specific time period to generate a preset number of samples, and converts the samples into a representative value. For a preset number or more of RSs, the terminal transmits an IS indication to the RRC if the corresponding representative value exceeds the BLER threshold, and otherwise it transmits an OOS indication to the RRC. When a plurality of consecutive IS or OOS indications indicated by the RLF parameter are received from the physical layer, the RRC starts or stops the RLF timer indicated by the RLF parameter.

In another embodiment, the base station may transmit a command message indicating a subset of the preconfigured RSs to instruct the terminal to monitor only the RLM-RSs contained in the subset. Here, the command message may be an RRC message, a MAC-CE message, or a Downlink Control Information (DCI) message. The command message may also include a preconfigured absolute or relative indicator of the RS.

The command message may instruct the terminal to perform radio link monitoring by using the RLM-RS indicated by the command message. In this case, although the terminal may measure and monitor the indicated RLM-RS and other RSs, the terminal may perform radio link monitoring using only the RLM-RS indicated by the command message (e.g., generate and transmit an out-of-sync indication or a sync indication to a higher layer).

In another embodiment, the base station does not have to monitor all RSs pre-configured to RLM-RSs, but may transmit a command message to instruct the terminal to monitor only RSs corresponding to the frequency range of the configured BWP or RSs specific to the configured BWP in the RS set as RLM-RSs when the terminal is configured with a specific BWP. Here, the command message may be an RRC message, a MAC-CE message, or a DCI message. The command message may also include an absolute or relative indicator of the preconfigured RS.

The command message may instruct the terminal to perform radio link monitoring by using the RLM-RS indicated by the command message. In this case, although the terminal may measure and monitor the indicated RLM-RS and other RSs, the terminal may perform radio link monitoring (e.g., generate and transmit an out-of-sync indication or a sync indication to a higher layer) using only the RLM-RS indicated by the command message.

The command message may instruct the terminal to discover and monitor RLM-RSs suitable for the switched BWP when switching the BWP to generate an out-of-sync indication or an in-sync indication and transmit it to higher layers by using the appropriate RLM-RSs.

In another embodiment, the base station may send a command message containing a value to instruct the terminal to perform RLM. Here, the command message may be an RRC message, a MAC-CE message, or a DCI message. Upon receiving the command message, the terminal may measure available RLM-RSs, list the measurement values and RS IDs in performance order, and perform radio link monitoring (e.g., generate and transmit an out-of-sync indication or a sync indication to higher layers) by using RSs of the same value as the received values.

In the above embodiment, when the RLF timer corresponding to a specific service and the constant of each threshold are informed, the base station may configure the timer and the constant of each service threshold and transmit them to the terminal via the ue-time and connections IE or RLF-time and connections IE. Then, when the base station detects a change in service type and sends only an indication of a changed BLER threshold pair for IS/OOS decision, it may not send the RLF timer and constant value along with the threshold pair indication signaling. In this case, since the base station does not have to transmit all the variation values of the other RLF parameters again according to the service type variation, signaling overhead is reduced. The above described constant configuration of the timer and each threshold may be applied to all timers affected by a service change. For example, it applies to T301, T310, T313, T311, N310, N311, N313, and N314.

In the above embodiments, the base station does not have to monitor all RSs configured as RLM-RSs, but may transmit a command message to instruct the terminal to monitor only RSs corresponding to the frequency range of the configured BWP or RSs specific to the configured BWP in the RS set as RLM-RSs when the terminal is configured with a specific BWP. This signaling will be described in more detail. When the base station configures the RLM-RS for the terminal, association between the RS and a bandwidth fragmentation (BWP) may be indicated. Based on the RS-BWP association, the terminal may use only RLM-RSs associated with the currently active BWP for RLM operation. The asn.1 level signaling for this is as follows. The RLM-RS list created by the base station is a set of RLM-RS, and each RLM-RS may indicate an RS type (SSB or CSI-RS).

Each RLM-RS may include an index of the BWP in which the RLM-RS is to be activated. If the SSB is used for RLM, the RS may be specified by an index of the SSB operated by the serving cell. If the CSI-RS is used for RLM, some of the CSI-RSs configured for beam management of the SpCell may be used as CSI-RSs for RLM. To refer to this, a predefined CSI-RS resource ID may be used to specify the CSI-RS for RLM. The CSI-RS designation may be transmitted together with time-frequency location information and repetition information of the corresponding CSI-RS. In addition, the base station may transmit a threshold value serving as a criterion for determining a reception intensity level of the RS for IS or OOS indication. In this case, the threshold pair index associated with the preset threshold may be transmitted instead of transmitting the threshold itself. Based on the threshold pair index, the terminal may select one of the threshold pairs predefined in the criteria and apply the selected threshold pair to the RLM.

These parameters may be transmitted via RRC messages, MAC CEs, or DCI. The following shows the case where the parameters are included in the SpCell configuration of the RRC message.

SpCcllConfig：：＝SEQUENCE{

--Parameters for the synchronous reconfiguration to the targetSpCell：

reconfigurationWithSync SEQUENCE{

spCellConfigCommon ServingCellConfigCommon，

newUE-Identity RNTI-Value，

t304 ENUMERATED{ms50，ms100，ms150，ms200，ms500，ms1000，ms2000，ms10000-v1310}，

rach-ConfigDedicated RACH-ConfigDedicated OPTIONAL--Need M

}OPTIONAL，--Cond SpCellChange

rlm-config RLM-RSConfig OPTIONAL，--Need M

spCellConfigDedicated ServingCellConfigDedicated OPTIONAL--Need M

}

SCellToReleaseList：：＝SEQUENCE(SIZE(1..maxNrofSCells))OF SCellIndex

SCellToAddModList：：＝SEQUENCE(SIZE(1..maxNrofSCells))OF SCellConfig

SCellConfig：：＝SEQUENCE{

sCellIndex SCellIndex，

sCellConfigCommon ServingCellConfigCommon OPTIONAL，--Cond SCellAdd

sCellConfigDedicated ServingCellConfigDedicated OPTIONAL--Cond

SCellAddMod

}

RLM-RSConfig：：＝SEQUENCE{

rlmInSyncOutOfSyncThrehold INTEGER(0..1)OPTIONAL，--Need M

rlmRSList SEQUENCE(SIZE(1..8))OF RLM-RS

}

RLM-RS：：＝CHOICE{

RLM-SSB INTEGER(0..63)

RLM-CSIRS INTEGER(0..NZP-CSI-RS-ResourceMax-1)

}

The RLM-RS is an IE that sets the attributes of the respective RLM-RS contained in the rlmRSList. Each RLM-RS may be an SSB or a CSI-RS. The SSB may be specified using an SSB index used in a corresponding cell. The CSI-RS may be specified using a CSI-RS resource index set for beam management or RRM in the corresponding cell. In this case, each SSB or CSI-RS may also include information about which RSs are assigned to which BWPs. For example, the base station may include a bandwidth slice ID and an RS index using SSB or CSI-RS in this signaling IE. In case of the CSI-RS, time-related information of the RS may also be included. For example, periodicity information and slot offset indicating the position of the reference subframe at which the repetition pattern starts may also be included.

The network may assign a maximum number of RLM-RSs and a minimum number of RLM-RSs for each configured BWP, and the terminal may monitor only the RLM-RSs assigned to the currently active BWP. Here, the maximum number of RLM-RSs and the minimum number of RLM-RSs may be specified by a standard specification or by a base station. The base station may identify the number of RSs that can be simultaneously monitored by the terminal based on the capability information received from the terminal. Currently, in order to perform RLM operation of active BWP, the minimum number of RLM-RSs may be one or more.

While the disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents.

Claims

1. A method performed by a terminal, the method comprising:

receiving a Radio Resource Control (RRC) message including first information associated with a reference signal for Radio Link Monitoring (RLM) and second information associated with a threshold value for the RLM;

monitoring radio link quality of at least one reference signal indicated by the first information;

comparing the radio link quality of the at least one reference signal to the threshold; and

indicating synchronization or non-synchronization to a higher layer of the terminal based on the comparison result.

2. The method of claim 1, wherein the first information comprises at least one of a Synchronization Signal Block (SSB) index or a channel state information-reference signal (CSI-RS) index.

3. The method of claim 1, wherein the second information comprises a block error rate (BLER) threshold pair index,

wherein the BLER threshold value pair index corresponds to a first threshold value for the synchronization and a second threshold value for the non-synchronization,

wherein the synchronization is indicated to the higher layer of the terminal if at least one radio link quality of the at least one reference signal is greater than the first threshold, an

Wherein the out-of-sync is indicated to the higher layer of the terminal if all radio link qualities of the at least one reference signal are below the second threshold.

4. The method of claim 1, wherein the radio link quality is monitored in bandwidth fragmentation (BWP) on a primary cell (PCell), and

wherein the first information is configured for each bandwidth slicing (BWP) configuration.

5. A method performed by a base station, the method comprising:

transmitting a Radio Resource Control (RRC) message to a terminal, wherein the RRC message includes first information associated with a reference signal for Radio Link Monitoring (RLM) and second information associated with a threshold value for the RLM; and

transmitting at least one of a Synchronization Signal Block (SSB) or a channel state information-reference signal (CSI-RS),

wherein the first information is used to indicate at least one of the SSB or the CSI-RS of a radio link quality to be monitored, an

Wherein the second information is used to compare the radio link quality with the threshold to indicate synchronization or non-synchronization to a higher layer of the terminal.

6. The method of claim 5, wherein the first and second light sources are selected from the group consisting of a red light source, a green light source, and a blue light source,

wherein the first information includes at least one of an SSB index or a CSI-RS index,

wherein the second information comprises a block error rate (BLER) threshold pair index,

wherein the synchronization is indicated to the higher layer of the terminal if at least one radio link quality of the at least one reference signal is above the first threshold, and

7. The method of claim 5, wherein the first and second light sources are selected from the group consisting of a red light source, a green light source, and a blue light source,

wherein the radio link quality is monitored in bandwidth fragmentation (BWP) on a primary cell (PCell), and

wherein the first information is configured for each BWP configuration.

8. A terminal, comprising:

a transceiver configured to transmit and receive signals; and

at least one processor configured to:

9. The terminal of claim 8, wherein the first information comprises at least one of a Synchronization Signal Block (SSB) index or a channel state information-reference signal (CSI-RS) index.

10. The terminal of claim 8, wherein the second information comprises a block error rate (BLER) threshold pair index.

11. The terminal of claim 10, wherein the BLER threshold value pair index corresponds to a first threshold value for the synchronization and a second threshold value for the non-synchronization,

12. The terminal of claim 8, wherein the radio link quality is monitored in bandwidth fragmentation (BWP) on a primary cell (PCell), and

13. A base station, comprising:

a transceiver configured to transmit and receive signals; and

at least one processor configured to

14. The base station of claim 13, wherein the base station is further configured to,

15. The base station of claim 13, wherein the base station is further configured to,

wherein the radio link quality is monitored in bandwidth fragmentation (BWP) on a primary cell (PCell), an

Wherein the first information is configured for each BWP configuration.