CN111034295B

CN111034295B - Method and apparatus for radio link failure using reference signal processing system

Info

Publication number: CN111034295B
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: 2024-02-23
Anticipated expiration: 2038-08-10
Also published as: KR20190017620A; AU2018314063A1; EP3653009A4; AU2018314063B2; EP3653009A1; CN111034295A

Abstract

A communication method and system is provided that fuses a 5 th generation (5G) communication system to internet of things (IoT) technology for supporting higher data rates beyond the 4 th generation (4G) system. 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 industry, security guard services. The method comprises the following steps: receiving a Radio Resource Control (RRC) message, the RRC message including first information associated with a reference signal for Radio Link Monitoring (RLM) and second information associated with a threshold for the RLM; monitoring a 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 with the threshold; and indicating synchronization or non-synchronization to higher layers of the terminal based on the comparison result.

Description

Method and apparatus for radio link failure using reference signal processing system

Technical Field

The present disclosure relates to an event for detecting a radio link failure in a millimeter wave system.

Background

In order to meet the growing demand for wireless data services since the deployment of the 4 th generation (4G) communication systems, efforts have been made to develop improved 5 th generation (5G) or quasi-5G communication systems. Thus, a 5G or quasi 5G communication system is also referred to as a "super 4G network" or a "Long Term Evolution (LTE) after-system". A 5G communication system is considered to be implemented on a higher frequency band (millimeter wave), for example, a 60GHz frequency 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 antennas, analog beamforming, large-scale antenna techniques are discussed in 5G communication systems. In addition, in the 5G communication system, development of system network improvement is underway based on advanced small cells, cloud Radio Access Networks (RANs), super-density networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, coordinated multipoint (CoMP), receiving-end interference cancellation, and the like. In 5G systems, hybrid Frequency Shift Keying (FSK) and Quadrature Amplitude Modulation (QAM) modulation (FQAM) and Sliding Window Superposition Coding (SWSC) have been developed as Advanced Code Modulation (ACM), as well as Filter Bank Multicarrier (FBMC), non-orthogonal multiple access (NOMA) and Sparse Code Multiple Access (SCMA) as advanced access technologies.

Currently, human-based connectivity networks, the internet, where humans generate and consume information, are evolving towards the internet of things (IoT) where distributed entities (e.g., things) exchange and process information without human intervention. Internet of things (IoE), which is a combination of IoT technology and big data processing technology through connection with cloud servers, has emerged. As 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), etc. have recently been studied. Such IoT environments may provide intelligent internet technology services that create new value for human life by collecting and analyzing data generated by connected things. IoT may be applied in a variety of fields including smart homes, smart buildings, smart cities, smart vehicles or connected vehicles, smart grids, healthcare, smart instrumentation, and advanced medical services through fusion and integration between existing Information Technology (IT) and various industrial applications.

In keeping with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, techniques such as sensor networks, machine Type Communications (MTC), and machine-to-machine (M2M) communications may be implemented by beamforming, MIMO, and array antennas. The use of cloud Radio Access Network (RAN) as an example of the above-described big data processing technique may also be considered as a 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 (CRSs). The signal strength corresponding to the time-frequency location of the cell-specific reference signal is measured for a preset time and averaged for the preset time. If the average value is less than a given signal-to-interference plus noise ratio (SINR) or signal-to-noise ratio (SNR), the higher layer is informed 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 in radio link failure processing whether the state of the link of the corresponding cell is acceptable for a longer period of time, and if the link state is not acceptable, the procedure of attaching to the cell itself is retried. In general, since a procedure of reattaching to a cell requires cell search, random Access Channel (RACH), and security-related operations to be performed again, radio processing and Core Network (CN) processing are required. There is also a need to exchange data between the newly attached cell and the previous cell that caused the failure. Considering the cost of the Radio Resource Control (RRC) reestablishment 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 directionality have been considered when measuring signal strength. Thus, only the time factor (measurement duration, arithmetic mean, or moving average) will affect the measurement variation.

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

Disclosure of Invention

Technical problem

In the case of the millimeter wave system, since all terminals under the cell coverage should perform radio link measurement, reference Signals (RSs) should be transmitted through analog beams instead of omni-directional transmission. Multiple analog beams may be transmitted simultaneously, or one analog beam at a time, depending on the situation of the system. There may be RSs in the scheduled beam and there may be measurement slots containing separate measurement signals. The direction is another parameter that affects the Radio Link Failure (RLF) decision compared to the case of omni-directional radiation.

Aspects of the present disclosure address at least the problems and/or disadvantages noted above and provide at least the advantages described below. Thus, one 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 time parameter and a direction parameter indicated by a specific analog beam.

Some portions of the other aspects are set forth in the description which follows, and some portions are apparent from the description or may be learned by practice of the embodiments as set forth hereinafter.

Technical proposal

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, the RRC message including first information associated with a reference signal for Radio Link Monitoring (RLM) and second information associated with a threshold for the RLM; monitoring a 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 with the threshold; and indicating synchronization or non-synchronization to higher layers 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 the 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 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 higher layers 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, the RRC message including first information associated with a reference signal for Radio Link Monitoring (RLM) and second information associated with a threshold for the RLM; monitoring a 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 with the threshold; and indicating synchronization or non-synchronization to higher layers 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 the 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 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 higher layers of the terminal.

Technical effects

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

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 are apparent from the following description taken in conjunction with the accompanying drawings in which:

fig. 1 illustrates measurement slots according to an embodiment of the present disclosure;

fig. 2 illustrates a case where measurement values of scheduled beams are added as samples outside of measurements within a measurement slot for a given duration according to an embodiment of the present disclosure;

fig. 3 illustrates transmitting a Synchronization Signal (SS) using multiple data TX beams simultaneously in accordance with an embodiment of the present disclosure;

fig. 4 illustrates a case where a base station configures separate reference signals for data TX beams constituting a corresponding SS and transmits the reference signals 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 a distinction of 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 using xSS in accordance with an embodiment of the present disclosure;

FIG. 7 depicts a case where T_in values are 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 about 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 of providing per-RS indication or aggregate 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 an associated 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 CSI-RS is configured at a specific point in time when RLM is performed by an SS according to an embodiment of the present disclosure;

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

fig. 16 depicts a case where a base station configures a specific bandwidth fragmentation (BWP) based on capabilities and service requirements 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 RLM-RS exists in only one frequency range according to an embodiment of the present disclosure;

fig. 19 depicts RLM-RS signaling when active bandwidth fragmentation has RLM-RS or does not have RLM-RS, according to an embodiment of the disclosure;

FIG. 20 illustrates a case where RLM-RS exists in multiple 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 set differently 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 defined by the claims and their equivalents. The following description includes various specific details that facilitate understanding, but are to be considered exemplary only. Thus, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the 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 written meanings, but are used only by the inventors 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 apparent from the following detailed description, which is to be read in connection with the accompanying drawings. The description of the various embodiments does not describe every possible instance of the present disclosure. It should be apparent to those skilled in the art that the following descriptions of the various embodiments are 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 considered together. In the description, the beam measurement reference signal (BRS) differs from the 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 do not jointly cover 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: consider only the RS in the measurement slot (only SS is configured) ]

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

Referring to fig. 1, a measurement slot is shown. In a beam scanning slot, the gNB Transmits (TX) beams each containing a BRS, and simultaneously scans the beams sequentially. While the gNB is performing the TX scanning, the UE Receives (RX) a particular beam and measures the BRS. Alternatively, the UE may scan the RX beam when the gNB repeatedly Transmits (TX) a beam containing BRSs. The method is applicable to the condition of RS resource change and the condition of synchronous judgment. In either case, the deadline by which measurements can be performed on all combinations of TX and RX beams is referred to as deadline 1, and the specific time below may be multiple deadlines.

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

B. [ calculation for each combination of 1 TX beam and M RX beams ] separately counts the values in different deadlines: for each TX beam, M RX beams are first selected, and an 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. If the N best values in the average of all TX beams are less than the OOS threshold, then OOS is determined. Here, the value of M may be given or may be selected for each terminal based on a specific criterion.

C. [ calculation for each beam pair of 1 TX beam and 1 RX beam ] statistics of values in different deadlines, respectively: in the "a" case, an 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 the determination is OOS.

D. [ calculation for each combination of 1 TX beam and M RX beams ] separately counts the values in different deadlines: in the "B" case, an 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 the determination is OOS. Here, the value of M may be given or may be selected for each terminal based on a specific criterion.

E. [ calculation for each beam pair of 1 TX beam and 1 RX beam ] average in terms of lifetime: a linear combination of the measured values of all TX-RX beam pairs is calculated for each deadline within a particular time. If none of the N optimal values in the linear combination values for the deadline are 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 specific criterion.

F. [ calculation for each combination of 1 TX beam and M RX beams ] average in terms of lifetime: for each TX beam, M RX beams are first selected. A linear combination of the measured values of the M RX beams is calculated for each deadline within a particular time. If none of the N optimal values in the linear combination of deadlines 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 specific criterion.

G. [ computation for each beam pair of 1 TX beam and 1 RX beam ]: in the "E" case, a linear combination of N optimal values is calculated. If the linear combination value is less 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 specific criterion.

H. (calculated for each combination of 1 TX beam and M RX beams): in the "F" case, a linear combination of N optimal values is calculated. If the linear combination value is less 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 specific criterion.

Embodiment 2: in addition to the measurement slots, RS is also present in the scheduled analog beam (CSI-RS is 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 outside of measurements in a measurement slot for a given duration according to an embodiment of the present disclosure.

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

For example, a plurality of BRSs may be transmitted simultaneously and as Synchronization Signals (SSs). For one SS transmission, a subset of the data TX beams of the base station may be radiated simultaneously. In this case, measurements may be taken of the SS and the measurements may be used to find the 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 transmit may be the SS itself or a data TX beam constituting the SS.

Fig. 3 illustrates transmitting a Synchronization Signal (SS) using multiple data TX beams simultaneously in accordance with an embodiment of the present disclosure.

Referring to fig. 3, SSs are transmitted as composite beams using a plurality (e.g., 3) of data TX beams simultaneously. The same synchronization signals are transmitted through these beams and the terminal sees the same synchronization signals within the beam coverage. By measuring the SS transmitted through the composite beam, the terminal achieves timing synchronization with the cell. At the same time, the terminal performs measurements to find the required data TX beam among the composite beams.

Fig. 4 illustrates a case where a base station configures a separate reference signal for data TX beams 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 (at operations 421, 422, 423) and reports the measurement result (e.g., the SS having the strongest received signal strength) to the base station 410 (at operation 425). The base station 410 configures (at operation 431) a separate reference signal (referred to as an additional RS, abbreviated as "aRS") in the data TX beam forming the SS and transmits the information to the terminal 405. Upon receiving the information, the terminal 405 measures (at operations 433, 434, 435) aRS in the SS (operation 441) and reports (at operation 443) the measurement results to the base station. The base station 410 determines (at operation 451) the beam to be used for data/control transmission. When the base station 410 transmits (at operation 453) the determined beam indication to the terminal 405, the terminal identifies the DL TX beam indicated by the beam indication. The terminal 405 then receives 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 a synchronization (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 following shows the signaling of the required information when only SS is used.

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

In LTE radio link monitoring, an OOS indication is generated if none of the durations t_out (=200 ms) exceeds the q_out threshold. In this case, since the RS is generated on a symbol basis in each subframe, the reception intensity will be measured at different points in time and have different values in which the reception intensity is measured within 200 ms. Since this is a UE implementation problem with a certain value as a representative value, various options are possible, but most options will assume an average value per symbol as a representative value. In the case of synchronization, if the q_in threshold IS exceeded for the duration t_in (=100 ms), an IS indication IS generated.

If xSS is set as the target of RLM, the symbol position (time and frequency) of xSS may be known in advance or may be signaled by the network through a broadcast channel or a dedicated signal. Based on this information, the reception strength of xSS is measured for each symbol. If it is known through the network information that an xSS symbol is transmitted via one particular beam, only the symbol transmitted via the corresponding beam is considered (without unconditionally comparing the average value of the xSS symbol within t_out with a threshold value), the terminal may consider it as a synchronization decision element if its value is greater than q_in and as an out-of-synchronization decision element if its value is less than q_out.

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

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

Embodiment 2-1: SS is RLM target only ]

More specifically, the received signal strength of the xSS transmitted by one beam is referred to as "received strength of xSS per beam". Here, the reception intensity of the xSS per beam may be an average of reception intensities of the xSS transmitted by one beam, a linear combination of the reception intensities and a specific weight, or a value depending on implementation. To issue an out-of-sync (OOS) indication, the terminal determines whether the reception strength per beam xSS is greater than or less than q_out, taking into account all xSS transmitted within t_out. If the reception intensity 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 alone, and issue an OOS indication if the reception intensity per beam xSS of the N beams is less than q_out. Here, since the number of beams carrying xSS may be different in different base stations, the OOS decision must 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, a synchronization (IS) indication may be issued by using the reception strength of the xSS per beam. To issue the IS indication, the terminal determines whether the reception intensity of xSS per beam IS greater than or less than q_in, taking into account all xSS transmitted within t_in. If the reception intensity of xSS per beam of any beam transmitted within 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 alone, and issue an IS indication if the reception intensity per beam xSS of the N beams IS greater than q_in. Here, since the number of beams carrying xSS may be different in different base stations, IS determination 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 using xSS in accordance with an embodiment of the present disclosure.

Fig. 6 depicts the base station signaling parameters required for radio link monitoring with 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 SS configuration information and RLM/RLF parameters (the number of beams required for OOS and IS decisions, threshold information required for OOS and IS decisions, duration (t_out) required for generating one OOS indication, duration (t_in) required for generating one IS indication, RLF timer value, the number of consecutive OOS and IS indications required for starting and stopping 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 the RLM/RLF parameters in advance as a default value. For RLM/RLF parameters that are not configured by base station 610, terminal 605 can use the corresponding default values. The terminal 605 can use the updated parameters when the RLM/RLF parameters are newly configured.

The xSS configuration information may include beam IDs (or corresponding time, frequency and resource information) of beams carrying SSs to be measured for RLM, or SS location information about time and frequency of SS resources to be measured in corresponding beams. 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 for which the measurement is above a threshold in each beam measurement within one T out or T in. That is, in the case of OOS decision, if the measurement results of N or more beams are higher than the threshold, then it is not OOS. In the case of IS decision, if the measurement results of N or more beams are higher than a threshold, IS. The RLF timer value and the number of consecutive OOS and IS indications required to start and stop the RLF timer may also be sent as parameters. If xSS belongs to the frequency 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 xSS spans a frequency band having multiple parameter sets with respect to a cell, if a terminal can access a limited number of bandwidth fragments (BWP) at a time and BWP can have different parameter sets, the parameters described above for the active BWP assigned to terminal 605 can be transmitted via a UE-specific message. The base station 610 transmits (at operations 631, 632, 633, 634) the xSS block signal to the terminal 605.

In particular 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 the xSS block signal specified for the hypothetical PDCCH transmission 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 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 circumstances. Due to UE signaling overhead or implementation difficulty, there may be a minimum time gap between OOS/IS indications.

Embodiment 2-2: CSI-RS becomes RLM target ]

If the CSI-RS IS used for radio link monitoring, the received signal strength of the CSI-RS contained in the beam carrying the CSI-RS instead of xSS IS compared to a threshold for OOS or IS decisions. 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 periodic or aperiodic event driven. The terminal should know whether the configured CSI-RS belongs to a specific beam. If the terminal knows the mapping between beams and CSI-RS, the terminal may consider the reception strength of the per-beam CSI-RS as described previously in the case of xSS. Here, the reception intensity of the CSI-RS per beam corresponds to an average (or linear combination) of the reception signal intensities of the CSI-RS transmitted by the corresponding beam.

To issue an out-of-sync (OOS) indication, the terminal determines whether the reception strength of the per-beam CSI-RS is greater than or less than q_out in consideration of all CSI-RS transmitted within t_out. If the reception intensity of the CSI-RS per beam 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 alone, and issue an OOS indication if the reception strength of the CSI-RS per beam 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 must 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, a synchronization (IS) indication may be issued by using the reception strength of the per-beam CSI-RS. To issue the IS indication, the terminal determines whether the reception strength of the CSI-RS per beam IS greater than or less than q_in, taking into account all CSI-RS transmitted within t_in. If the reception intensity of the CSI-RS per beam of any beam transmitted within 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 alone, and issue an IS indication if the reception strength of the CSI-RS per beam 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 successive OOS and IS indications required to start and stop the RLF timer may be transmitted as parameters.

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

Referring to fig. 7, when CSI-RS IS configured, a base station 710 informs a terminal 705 of CSI-RS configuration information (ID of configured CSI-RS, or beam time-frequency information and resource location information) and RLM/RLF parameters (number of beams required for OOS and IS decisions, threshold information required for OOS and IS decisions, duration (t_out) required for generating one OOS indication, duration (t_in) required for generating one IS indication, RLF timer value, number of consecutive OOS and IS indications required for starting and stopping RLF timer). 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 the RLM/RLF parameters in advance as a default value. For RLM/RLF parameters that are not configured by base station 710, terminal 702 can use corresponding default values. The terminal 705 may use the updated parameters when the RLM/RLF parameters are newly configured. If terminal 705 has access to a limited number of bandwidth slices (BWP) at a time, the BWP may have different parameter sets and different CSI-RS settings may be given accordingly. The parameters described above for the active BWP assigned to the terminal 705 may be transmitted via the UE-specific message. That is, in fig. 7, if the CSI-RS configuration is changed in the same BWP, it may be applied at the reconfiguration time. If the CSI-RS is configured to use another BWP, the information given in fig. 7 may be carried by a message informing the corresponding 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 CSI-RS to the terminal 705 (at operations 731, 732, 733, 734).

With respect to the threshold in particular, the base station 710 may transmit a threshold (RSRP, RSRQ, SINR or RSSI) corresponding to a given BLER for the measurement result of the RS to the terminal 705 to measure the CSI-RS signal specified for the hypothetical PDCCH transmission at the physical layer. Alternatively, the target BLER for the hypothetical PDCCH transmission may be transmitted to the terminal 705. Upon receiving the value, the terminal 705 measures CSI-RS for a given BLER to generate an OOS or IS indication (at operation 740) since it knows the relationship between the CSI-RS measurement and the given BLER. In addition, the 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 the case where only aRS are used, since aRS do not occur within a uniform time period, measurements are made of aRS when downlink transmission occurs and the corresponding beam is received. Issuing an OOS indication if the time-averaged received strength over the most recent time period does not exceed the OOS threshold regardless of the number of samples; if it exceeds the IS threshold, an IS indication IS issued.

Embodiment 2 to 3: both SS and CSI-RS are used for RLM

The RLM/RLF parameters may be different for different RSs

For SS, since the OOS/IS must be determined by omni-directional beam scanning with a wide beam, the t_out/t_in time window IS greater than that of CSI-RS using a narrow beam. The CSI-RS beam is not any available narrow beam, but a small number of beams allocated to the data and control channels by the base station, 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 window may be different for SS and CSI-RS within the same time period. When the channel condition is degraded, consider an SS or CSI-RS waiting the same number of times, the RLF time value for the SS is large, and the RLF time value for the CSI-RS is small.

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

the xSS and CSI-RS may be used for radio link monitoring at the same time. In this case, RS configuration information and OOS/IS thresholds can be set for xSS and CSI-RS, respectively. The values of t_out, t_in, and N in the OOS/IS decision may be set for 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 xSS and CSI-RS, respectively. If all parameter values are set for xSS and CSI-RS, respectively, the OOS/IS indication may be generated independently of the RS. Here, when the RLF timer is active in RRC, the indication of whichever RS is identified as the same indication. In other words, if an OOS indication is first generated according to xSS and then OOS indication is generated according to CSI-RS, the RRC may consider both OOS indications to be the same type of indication and they are considered to be consecutive OOS indications, as in the case of LTE N310. Likewise, even if IS indications occur according to different settings, RRC may consider them to be the same type of indication.

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

for OOS processing, the values of t_out, t_in, and N in the OOS/IS decision may be set for xSS and CSI-RS in a consistent manner. In this case, considering the CSI-RS beam and the xSS beam received within t_out, if the reception intensity of each beam RS (here, RS may be xSS or CSI-RS) of the N beams is less than q_out, an OOS indication is generated. Here, OOS thresholds can be set for xSS and CSI-RS, respectively, and the values of N and t_out are the same regardless of which type of RS is.

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 xSS and CSI-RS. In this case, considering the CSI-RS beam and the xSS beam received within t_in, if the reception intensity of each beam RS (here, RS may be xSS or CSI-RS) of the N beams IS greater than q_in, an IS indication IS generated. Here, IS thresholds may be set for xSS and CSI-RSs, respectively, and the values of N and t_in are the same regardless of which type of RS IS.

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

If SS and aRS are used, SS samples are accumulated using the BRS OOS decision method of the present disclosure, and the aRS samples are further accumulated to an accumulated SS value when aRS is transmitted and measured. Here, for integration, the measured 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 the signaling time according to the measurement result of the RS with 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 the measurement result of another RS by referring to the measurement result of one RS. This classification scheme will be described below.

1) OOS decision priority of SS

As another way of using SS and aRS together, a hierarchical decision may be made. If the OOS is determined to be OOS based on the SS measurement only, an OOS indication is sent to the RRC and no further consideration of the aRS is required. If IS determined based on the measurement of SS only, the measurement of aRS IS 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 measured values of aRS are linearly combined with each other, and the measured values of SS are accumulated between the SS measured values, as in the first BRS OOS decision scheme of the present disclosure.

2) IS determination priority of SS

If it IS determined to be IS based on the measurement value of SS only, an IS indication IS sent to RRC and the aRS need not be considered further. If the determination is OOS based on the SS measurement alone, the aRS measurement is 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 measured values of aRS are linearly combined with each other, and the measured values of SS are accumulated between the SS measured values, as in the first BRS OOS decision scheme of the present disclosure.

3) OOS decision prioritization for CSI-RS

If the OOS is determined to be OOS based on only the measurement value of the CSI-RS, an OOS indication is sent to the RRC and no further consideration of the SS is required. If it IS determined to be IS based on only the measurement value of CSI-RS, the measurement value of SS IS further considered. That IS, if the measurement result of the SS 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 measured values of aRS are linearly combined with each other, and the measured values of SS are accumulated between the SS measured values, as in the first BRS OOS decision scheme of the present disclosure.

4) IS decision priority for CSI-RS

If it IS determined to be IS based on only the measurement value of CSI-RS, an IS indication IS sent to RRC and SS need not be considered further. If the determination is OOS based on the measurement of CSI-RS only, the measurement of SS is further considered. That IS, if the measurement result of the SS 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 measured values of aRS are linearly combined with each other, and the measured values of SS are accumulated between the measured values of SS, as in 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

Index

Results

First test

Second test

Example

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 specific RS yields the result of the indication. If the first inspection does not produce an indicated result, a second inspection is considered. If the second check yields the indicated result, the OOS indication is again generated. Otherwise, generating a complementary result of the OOS. When the base station transmits this information, the terminal determines an RLM result on the cell side based on the RLM results of the two RSs by using the received information and notifies the RRC of the RLM result on the cell side.

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

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 is an absolute value and the other threshold is an offset value.

When the base station transmits a parameter set corresponding to each RS to the terminal, the threshold value may be given as an absolute value. If the threshold value of one RS has been given, the threshold value of the other RS may be given as an offset relative to the threshold value that has been given. For example, when the aRS and SSs are used simultaneously, 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 in order to make a decision based on a specific threshold value, an offset to be added to the reception signal strength may be required. This offset may be added to the measured value of aRS to generate the received signal strength value of the SS as a consistent metric. This measure of agreement may be compared to a given threshold. For this purpose, the base station may transmit the required offset value to the terminal.

Fig. 8 depicts a case where a base station transmits information about 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, an offset value is set for a specific DL TX beam, 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 (at operation 821), and the base station 810 transmits the SSs in time or frequency order in the always-on mode (at operation 823). When the terminal measures the SS and reports the best SS to the base station 810, the base station 810 configures the aRS at DL TX beams constituting the best SS (at operation 825) and transmits the aRS location information to the terminal 805. The terminal 805 performs measurement based on this information and transmits the measurement result 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 a new beam is found (at operation 829), if a DL TX beam is changed while an aRS metric is calculated (at operation 831), the target for the aRS metric calculation should be changed from beam set 1 to beam set 2 (at operation 833) based on the corresponding indication.

An example of representing this related information is shown in table 2 below.

TABLE 2

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

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

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 the offset information transmitted via the system information in fig. 8 via an RRC dedicated message, and the terminal 905 applies this information. Since the optimal SS has been determined, an offset value of the DL TX beam corresponding to the optimal 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 related 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 (at operation 1023) the terminal 1002 of the selected DL TX beam through the PDCCH and may also transmit an offset for 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 (in operation 1027) the required offset information. See the corresponding operations in fig. 8 for operations 1021, 1025, and 1029.

As another option, fig. 11 depicts a case where related 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, the base station 1110 transmits (in operations 1123, 1127) related offset information to the terminal 1105 through a MAC CE. Upon informing the DL TX beams, an offset value associated with the number and ID of the selected DL TX beams may be informed via the MAC CE. For operations 1121, 1125, and 1129, see the corresponding operations in fig. 8.

When only one of the SS and CSI-RS is the target of 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. If a specific bandwidth fragmentation can only carry CSI-RS (no SS), a terminal operating in the bandwidth fragmentation may only need information related to CSI-RS. The CSI-RS configuration information assigned to the active bandwidth slices and the threshold information required for RLM can also be changed by different parameter sets. The bandwidth fragmentation used by the terminals may change over time. In these cases, the base station may use UE-specific signaling to send CSI-RS configuration information when the corresponding bandwidth fragmentation IS used, as well as information related to the value of N, the threshold (absolute value or offset), t_out, t_in, 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 does not change for a period of time although two RSs are configured, the RLM operation and the RLF operation may be performed by inheriting RLF parameters of the respective RSs. However, when a plurality of RSs are configured, if an RLM RS changes from a previous RS to a new RS, it is necessary to determine whether to apply the RLF parameter associated with the new RS after inheriting the state of the RLF parameter associated with the previous RS, or whether to apply the RLF parameter associated with the new RS after resetting the state of the RLF parameter associated with the previous RS.

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

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

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

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

-conditions for applying different RLF parameters

In a 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 CSI-RS IS for a terminal and an associated SS IS not IS according to an embodiment of the present disclosure.

Referring to fig. 13, while a large portion 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 intensity of the SS may be extremely low, the CSI-RS beam 1 may have no problem at all. The channel state must be checked independently for each RS. This 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 the t_is for SS IS decision will be longer than the t_is for CSI-RS IS decision. Therefore, if the number of IS indications required 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 measurement values, the network may instruct the indicating terminal to inherit the state of the existing parameters. Upon determining that the above correlation is not high and 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 point of time when RLM is performed for the SS, it may be assumed that a CSI-RS priority policy is set at the point of time.

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

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

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

Timer value

There is a timer value in the RLF parameter for each RS. When the CSI-RS is configured at a specific point of time when RLM is performed based on the SS, it may be assumed that a CSI-RS priority policy is set at the point of time. In fig. 15, for the case indicated by the numeral 1510, the terminal has started the 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 parameters are reset, the previous 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 policy of performing RLM in a CSI-RS-prioritized manner when CSI-RS is configured at a specific point of time of performing RLM by an SS according to an embodiment of the present disclosure.

Referring to fig. 15, for the case indicated by a symbol 1520, the CSI-RS IS configured, an RLF timer for the CSI-RS runs, the CSI-RS measurement generates an IS indication, and the CSI-RS IS released or not configured. In this case, the timer for CSI-RS may be reset, and the RLF timer for 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 announces the RLF if the elapsed time has exceeded the SS timer value. Otherwise, the SS timer runs until the remaining timer value expires.

-informing RLF parameter application options

For the above two parameters, static rules may be used, or the network may dynamically set the rules and inform the terminal. 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 scenario in which a base station configures a particular bandwidth fragment based on capabilities and service requirements of a terminal in accordance with an embodiment of the present disclosure.

If one type of RS is configured in the current active bandwidth segment, the terminal 1605 operates according to RLM/RLF parameters and rules for that RS. If two or more types of RSs are configured in the active bandwidth shard, the terminal 1605 determines an RS type having priority in the bandwidth shard 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.

The base station 1610 allows the use of a specific bandwidth fragment, and if an SS exists in the bandwidth fragment, it transmits SS configuration information and corresponding parameters via dedicated signaling (at operation 1621). If the CSI-RS is to be configured, the base station 1610 transmits CSI-RS configuration information and corresponding parameters. If two RSs are to be configured (i.e., CSI-RSs, in which SSs are transmitted via bandwidth fragmentation and narrowband beams are required for data transmission and reception by terminal 1605), the base station transmits the corresponding configuration information, parameters, and priority rules 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, SS-related configuration information and RLM/RLF parameter sets (option 1) may be transmitted via a broadcast channel or a shared channel that transmits system information. Alternatively, the terminal 1605 may be given initial SS-related RLM/RLF parameters and the SS-related configuration information and RLM/RLF parameter sets may be sent via dedicated signaling after RRC connection establishment by using an RRC connection reconfiguration message (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 transmits (at operation 1625) a bandwidth fragment having a parameter set matching an enhanced mobile bandwidth (emmbb), ultra-reliable low latency communication (URLLC), or large-scale machine type communication (mctc) to the terminal 1605. In addition, the base station checks whether the SS is present in the assigned bandwidth fragment, and if so, it transmits (at operation 1627) the SS-related configuration and corresponding RLM/RLF parameters.

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

When the CSI-RS is configured, the base station 1610 notifies the terminal 1605 of corresponding configuration information and parameters (in operation 1635) and notifies the RS priority index. Upon determining 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 transmits a reset indication for applying RLF parameters to the terminal 1605.

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

If there is no SS in the corresponding bandwidth fragmentation, RLM/RLF may be performed using only CSI-RS configuration information and parameter information. As another option, information about bandwidth fragmentation (frequency, cell ID, or bandwidth fragmentation ID) in which an SS exists, measurement gap information for measuring the SS, SS configuration information for bandwidth fragmentation, RLF parameter information, priority rule information, and reset instruction 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 fragmentation in a time division manner and perform RLF operation according to the priority rule and the reset instruction. 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-parity or parity, correlation between the received signal strengths of the SS and the CSI-RS may be weak. In this case, the base station 1610 may provide a reset indication for applying 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 (at operation 1729). When the above information is received before configuring the CSI-RS, the base station 1710 transmits (at operation 1733) a priority rule and an 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 set to a preset default value and an RLF parameter inheritance/reset indication.

As another option, the terminal 1705 may have a current default value for the priority rules and RLF parameter inheritance/reset indication. If the base station 1710 does not provide a specific value, the terminal 1705 may apply a preset default value.

For operations 1721 to 1735, see the corresponding operations of fig. 16.

As another embodiment, if RLF is declared due to RLM operations 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 announce RLF. If the connection is unsuccessful, the terminal may announce the RLF and search for a new cell. Here, the preset BWP may be a default BWP or another configuration BWP. Access to the preset BWP may be achieved through RACH or through 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 a radio link monitoring reference signal (RLM-RS) for the terminal. The RLM-RS may be an SS (synchronization signal), a CRS (cell-specific reference signal), an SRS (sounding reference signal), or a CSI-RS (channel state information reference signal), or a combination thereof. When RLM-RS is configured for the terminal, the base station may transmit RS information about the time-frequency resource location and code (if code is used). When a specific mode is agreed 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 RLM parameters associated with the RS, wherein the physical layer may transmit an IS (synchronization) indication or an OOS (out of synchronization) indication to higher layers.

The RLM parameters may include an IS threshold for generating an IS indication if the received power IS above the IS threshold (considering RSRP, RSRQ, RSSI or BLER if PDCCH transmission IS assumed), a number of RSs or beams that should be above the IS threshold, an OOS threshold for generating an OOS indication if the received power IS below the OOS threshold, a number of RSs or beams that should be below the OOS threshold, a time window for IS and OOS measurements, and an interval between the IS indication or OOS indication. 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 RLM-RS for the terminal, this RS may or may not be present in all designated bandwidth slices (BWP). In particular, 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 a frequency location where the RLM-RS exists and receive and measure the RLM-RS to generate the periodic indication.

In the above description, switching from the originally scheduled active BWP to the BWP with the RLM-RS is referred to as backoff. The network may provide information to the terminal such as a backoff time, a residence time in the backoff BWP, a return time to switch back to the originally scheduled active BWP, and a repetition period of the backoff mode. 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 in which the terminal does not have to monitor the scheduled active BWP. This measurement gap may be specified by information such as the start point of the gap, the duration of the gap, and the repetition period.

When a measurement gap of RLM is configured for the terminal, 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 illustrates a case where RLM-RS exists in only 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 active BWP currently monitored by the terminal.

Fig. 19 depicts RLM-RS signaling when an active BWP has RLM-RS and when the active BWP does not have RLM-RS according to an embodiment of the present disclosure.

When the active BWP is scheduled for the terminal, the base station determines (in operation 1905) whether the active BWP has the RLM-RS. If the active BWP has the RLM-RS, the base station may skip (at operation 1910) transmission of backoff information or RLM-RS measurement gap information for the separate RLM-RS BWP. In this case, the terminal performs RLM (at operation 1915) and does not need to switch to another BWP.

If the scheduled active BWP does not have the RLM-RS (in operation 1920), the base station transmits the backoff information of the RLM-RS BWP and the RLM-RS measurement gap information (in operation 1925). Upon receiving this information, the terminal may monitor active BWP, switch to RLM-RS back-off BWP, or receive and measure RLM-RS based on gap information, and return to the original active BWP (in operation 1930).

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 may be used for active BWP, and thus different types of RLM BWP may be used.

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

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

(3) As indicated in section (2), RLM-RS may be present in all BWP. In this case, the terminal does not switch to a specific BWP to measure the RLM-RS, but rather measures the RLM-RS existing in each scheduled active BWP and applies a corresponding RLM parameter to generate the 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 BWP, it does not provide RLM-RS information dedicated to active BWP. The terminal compares the location 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 a backoff or a gap measurement operation.

(4) If there is an RLM backoff BWP or an RLM measurement gap configuration, the terminal measures the RLM-RS at a designated time to generate an indication and operates the RLF timer through the application layer 3 parameter based on the indication. However, when the active BWP is scheduled (or switched) and an indication is received due to the RLM-RS being present in each active BWP as described in section (3), it is selected whether to inherit or reset the current state when applying the L3 parameter.

If the channel correlation between BWPs is not large, a reset option may be applied; if the channel correlation is large, then an inheritance option may be applied. For the number of consecutive IS or OOS indications in the L3 parameter for starting or stopping the RLF timer, the terminal relays RLF parameter states 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 states in the switched active BWP.

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

If the channel correlation between BWP is not large, a reset option may be applied. 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 switched active BWP, the terminal operates the timer accordingly.

(5) Since various RSs may be used as RLM-RSs as described in section (1), different RLF parameter sets may be set for different bwrps. When a new active BWP is scheduled, the base station may transmit at least some of the following values as RLF parameters to the terminal: an IS threshold (RSRP, RSRQ, RSSI, SINR or BLER considering the case of hypothetical PDCCH transmission) for generating an IS indication if the received power IS above the IS threshold; an OOS threshold (RSRP, RSRQ, RSSI, SINR or BLER considering the case of a hypothetical PDCCH transmission) for generating an OOS indication if the received power is below the OOS threshold; time windows for IS and OOS measurements; intervals between IS or OOS indications sent to higher layers; for generating IS indicates the number of RSs or beams that should be higher than the IS threshold; for generating OOS indicates a number of RSs or beams that should be below the OOS threshold; RLF timer value; a number of consecutive OOS indications for starting the RLF timer; and a number of consecutive IS indications for stopping 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, a base station may include a transceiver 2110, a controller 2120 (e.g., at least one processor), and a storage 2130 (e.g., memory).

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

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

The controller 2120 may control the overall operation of the base station according to embodiments of the present disclosure. For example, the controller 2120 may control the signal flow between the 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 2130 may store at least one of information transmitted or received through the transceiver 2110 and information generated by the controller 2120.

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

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

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

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

The transceiver 2210 may transmit signals to and receive signals from other network entities. For example, the 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 signal flows between 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 embodiments of the present disclosure.

The storage device 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 required for radio link monitoring according to embodiments of the present disclosure.

As described above, the RLM/RLF parameter may be differently configured according to the type of RS. The RLM/RLF parameters may also be configured differently depending on 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 an 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 according to the IS/OOS indication using RLF parameters to announce RLF. Here, the RLM parameters transmitted by the base station 2310 may include RLM-RS configuration information (RS type, RS time-frequency position, threshold to be compared with measured 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 when a preset number of consecutive IS or OOS indications are received.

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 E-UTRAN radio access bearer (E-RAB) or an IP packet of a flow, and a type of traffic 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 service with tighter 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 a VoIP service that is sensitive to faults due to characteristics of voice traffic.

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

PCelConfig or measConfig)

RLM-configuration

List of RLM-RS

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

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

Threshold information

■ Pair_BLER_ID, e.g., {0 or 1}, e.g

The list of RLM-resource-config-SS may include a list of SSB indexes 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 the newly added CSI-RS. The pair_of_bler_id indicates an ID of a Pair of hypothetical PDCCH BLER values for IS and OOS decisions in a preset Pair of target hypothetical PDCCH BLER values for the received signal of each RS. This indication may indicate the BLER to be used and the service mapped with the BLER. For example, "0" may indicate a BLER value pair used in LTE and indicate a generic 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. The RRC message or MAC CE 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 connection 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 the 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 the default service type.

For RLF parameter signaling related to a service type, 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-timersand stats signaling of the CellGroup configuration container in RRC messages, and may be configured and sent 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 as follows once.

The base station may transmit RLM configuration information when the terminal transitions from an idle state to a 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. The 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 the connected state has been changed as described above, the serving cell 2410 may transmit new BLER information via an RRC reconfiguration message or transmit new BLER information and information related to the newly configured RLM-RS.

Upon receiving the above configuration information, the terminal checks RLM-RS configuration information, measures the 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 to a representative value. For a preset number or more of RSs, if the corresponding representative value exceeds the BLER threshold, the terminal sends an IS indication to the RRC, otherwise it sends an OOS indication to the RRC. When multiple 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 preconfigured RSs to instruct the terminal to monitor only 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 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 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 preconfigured as RLM-RSs, but may transmit a command message to instruct the terminal to monitor only RSs in the RS set corresponding to the frequency range of the configured BWP or configured BWP-specific RSs as RLM-RSs when configuring the specific BWP for the terminal. 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 discover and monitor RLM-RS of BWP suitable for handover at the time of handover of BWP to generate an out-of-sync indication or a synchronization indication, and transmit it to a higher layer by using the suitable RLM-RS.

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 the available RLM-RS, list the measured values and the RS ID in performance order, and perform radio link monitoring by using the RS of the same value as the received value (e.g., generate an out-of-sync indication or a sync indication and transmit it to a higher layer).

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

In the above embodiment, 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 in the RS set corresponding to the frequency range of the configured BWP or configured BWP-specific RSs as RLM-RSs when configuring a specific BWP for the terminal. This signaling will be described in more detail. When the base station configures the RLM-RS for the terminal, an association between the RS and a bandwidth slicing (BWP) may be indicated. Based on the RS-BWP association, the terminal may use only RLM-RS 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 RLM-RS set, and each RLM-RS may indicate an RS type (SSB or CSI-RS).

Each RLM-RS may include an index of the BWP to which the RLM-RS is to be activated. If SSBs are used for RLM, the RS may be specified by an index of SSBs operated by the serving cell. If the CSI-RS is used for RLM, some of the CSI-RS configured for beam management of SpCell may be used as CSI-RS for RLM. To refer to this, a predefined CSI-RS resource ID may be used to designate the CSI-RS for RLM. The CSI-RS designation may be transmitted along with time-frequency location information and repetition information of the corresponding CSI-RS. In addition, the base station may transmit a threshold value that serves as a criterion for determining the 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 correspond the selected threshold to the RLM.

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

The RLM-RS is an IE that sets the attribute of each RLM-RS contained in the rlmrlist. Each RLM-RS may be an SSB or CSI-RS. SSBs may be specified using SSB indexes used in the corresponding cells. 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 fragmentation ID and an RS index using SSB or CSI-RS in this signaling IE. In case of CSI-RS, time-related information of the RS may also be included. For example, periodic information indicating the location of the reference subframe at the start of the repetition pattern and slot offset 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 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 monitored simultaneously by the terminal based on the capability information received from the terminal. Currently, in order to perform an RLM operation of active BWP, the minimum number of RLM-RSs may be one or more.

While the present 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 present disclosure as defined by the appended claims and their equivalents.

Claims

1. A method performed by a terminal in a wireless communication system, the method comprising:

transmitting capability information for identifying a plurality of reference signals for radio link monitoring RLM to a base station;

receiving a radio resource control, RRC, message for primary cell, PCell, configuration from the base station, the RRC message including configuration information for reference signals of the RLM and threshold information for the RLM, wherein the reference signals for the RLM are configured for each active bandwidth fragmentation, BWP, of a cell;

Monitoring a radio link quality of the reference signal in the activated BWP of the cell, wherein the radio link quality is related to a reception strength of the reference signal;

comparing the radio link quality of the reference signal with a first threshold for synchronization or a second threshold for non-synchronization, wherein the first threshold and the second threshold are identified based on the threshold information for the RLM, wherein the threshold information comprises a block error rate (BLER) threshold pair index corresponding to the first threshold for synchronization and the second threshold for non-synchronization;

indicating the synchronization to a higher layer of the terminal based on the configuration information of the reference signal for the RLM, in case the radio link quality of the reference signal is greater than the first threshold value for a first predetermined duration; and

in case the radio link quality of the reference signal for the terminal is below the second threshold for a second predetermined duration, based on the configuration information of the reference signal for the RLM, indicating the dyssynchrony to higher layers of the terminal,

Wherein the number of reference signals for the RLM that the terminal can monitor simultaneously is indicated by the capability information.

2. The method of claim 1, wherein the configuration information for the reference signal of the RLM comprises at least one of a synchronization signal block SSB index or a channel state information-reference signal CSI-RS index.

3. The method according to claim 1,

wherein the cell corresponds to the PCell,

wherein the BLER threshold pair index is 0 or 1, an

Wherein the BLER threshold pair index indicates the ID of the hypothesized BLER value pair for out-of-sync and in-sync indications.

4. The method of claim 1, wherein the configuration information for the reference signal of the RLM comprises a determination of the dyssynchrony and a number of beams required for the synchrony.

5. A method performed by a base station in a wireless communication system, the method comprising:

receiving capability information for identifying a plurality of reference signals for radio link monitoring, RLM, from a terminal;

transmitting a radio resource control, RRC, message for primary cell, PCell, configuration to the terminal, the RRC message including configuration information for reference signals of the RLM and threshold information for the RLM, wherein the reference signals for the RLM are configured for each active bandwidth fragmentation, BWP, of a cell; and

Transmitting the reference signal comprising at least one of a synchronization signal block SSB or a channel state information-reference signal CSI-RS,

wherein a first threshold for synchronization and a second threshold for non-synchronization are identified based on threshold information for the RLM, wherein the threshold information comprises a block error rate (BLER) threshold pair index corresponding to the first threshold for synchronization and the second threshold for non-synchronization,

wherein in case the radio link quality of the reference signal is greater than the first threshold value for a first predetermined duration, the synchronization is indicated to a higher layer of the terminal based on the configuration information of the reference signal for the RLM, and

wherein in case the radio link quality of the reference signal for the terminal is below the second threshold for a second predetermined duration, the dyssynchrony is indicated to higher layers of the terminal based on the configuration information of the reference signal for the RLM,

6. The method according to claim 5, wherein the method comprises,

Wherein the configuration information of the reference signal for the RLM includes at least one of an SSB index or a CSI-RS index.

7. The method according to claim 5, wherein the method comprises,

wherein the cell corresponds to the PCell,

wherein the BLER threshold pair index is 0 or 1,

8. The method according to claim 5, wherein the method comprises,

wherein the configuration information for the reference signals of the RLM includes determining the dyssynchrony and the number of beams required for the synchronization.

9. A terminal in a wireless communication system, comprising:

a transceiver; and

at least one processor configured to:

transmitting capability information identifying a plurality of reference signals for radio link monitoring, RLM, to a base station via the transceiver;

receiving, via the transceiver, a radio resource control, RRC, message for primary cell, PCell, configuration from the base station, the RRC message including configuration information for reference signals of the RLM and threshold information for the RLM, wherein the reference signals for the RLM are configured for each active bandwidth fragmentation, BWP, of a cell;

10. The terminal of claim 9, wherein the configuration information for the reference signal of the RLM comprises at least one of a synchronization signal block SSB index or a channel state information-reference signal CSI-RS index.

11. The terminal according to claim 9,

wherein the cell corresponds to the PCell,

wherein the BLER threshold pair index is 0 or 1, an

12. The terminal according to claim 9,

13. A base station in a wireless communication system, comprising:

a transceiver; and

at least one processor configured to receive capability information from the terminal via the transceiver for identifying a plurality of reference signals for radio link monitoring, RLM,

transmitting a radio resource control, RRC, message for primary cell, PCell, configuration to the terminal via the transceiver, the RRC message including configuration information of reference signals for the RLM and threshold information for the RLM, wherein the reference signals for the RLM are configured for each active bandwidth fragmentation, BWP, of a cell, and

14. The base station of claim 13,

15. The base station of claim 13,

wherein the cell corresponds to the PCell,

wherein the BLER threshold pair index is 0 or 1, an

16. The base station of claim 13,