Patent Description:
In the <NUM> system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.

In case that a terminal transmits or receives a signal by using resources on different frequency bands from each other via carrier aggregation or dual or multi-connectivity, a terminal internal interference signal due to harmonic interference, inter-modulation distortion (IMD), and the like occurs at a specific frequency band reception end of the terminal, and thus the downlink signal receiving performance of the terminal may be deteriorated. Accordingly, a method for controlling such a terminal internal interference signal is needed.

<NPL>, provides a discussion on LTE-NR uplink sharing from UE perspective. <NPL> discusses high priority scenarios for Rel-<NUM> NR. <CIT> discloses supporting dual connection in a new radio access technology (NR).

Accordingly, an aspect of the disclosure is to provide a method by which resources of different frequency bands from each other are scheduled to prevent harmonic interference, inter-modulation distortion, or the like from occurring therebetween, so as to prevent deterioration in the downlink reception performance of a terminal, and then a possible unused resource of each of the frequency bands is utilized, wherein efficiency of resource utilization is enhanced.

According to the disclosure, deterioration in the reception performance of a terminal caused by harmonic interference and inter-modulation distortion which may occur in a mobile communication system supporting a carrier aggregation technology, a dual connectivity/multi-connectivity technology, or the like which simultaneously uses a plurality of resources is prevented, and wasted resources are minimized at the time of such interference control, such that the transmission/reception performance of a terminal and a base station may be enhanced.

Further, based on determinations by those skilled in the art, the particular embodiments of the disclosure may be applied to other communication systems with similar technical backgrounds and channel types through some modifications without significantly departing from the scope of the disclosure.

As used herein, the "unit" refers to a software element or a hardware element, such as a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC), which performs a predetermined function. However, the "unit" does not always have a meaning limited to software or hardware. The "unit" may be constructed either to be stored in an addressable storage medium or to execute one or more processors. Therefore, the "unit" includes, for example, software elements, object-oriented software elements, class elements or task elements, processes, functions, properties, procedures, sub-routines, segments of a program code, drivers, firmware, micro-codes, circuits, data, database, data structures, tables, arrays, and parameters. The elements and functions provided by the "unit" may be either combined into a smaller number of elements, or a "unit", or divided into a larger number of elements, or a "unit". Moreover, the elements and "units" or may be implemented to reproduce one or more CPUs within a device or a security multimedia card.

The disclosure relates to a scheduling method for interference control in a mobile communication system supporting a carrier aggregation technology, a dual connectivity or multi-connectivity technology, or the like which simultaneously uses a plurality of frequency resources, and an apparatus for performing same.

A carrier aggregation (CA) technology is a technology of coupling a plurality of component carriers and enabling one terminal to simultaneously use the plurality of component carriers to transmit or receive a signal, so as to enhance frequency usage efficiency from the viewpoint of a terminal or a base station. Specifically, according to a CA technology, a terminal and a base station may transmit or receive a signal via a wideband by using a plurality of component carriers in each of an uplink (UL) and a downlink (DL), wherein each of the component carriers is positioned in different frequency bands from each other. Hereinafter, an uplink refers to a communication link through which a terminal transmits a signal to a base station, and a downlink refers to a communication link through which a base station transmits a signal to a terminal. At this time, the number of uplink component carriers and the number of downlink component carriers may be different from each other.

A dual connectivity or multi-connectivity technology is a technology of enabling one terminal to be connected to a plurality of different base stations from each other and to transmit or receive a signal by simultaneously using frequency resources which are in each of the plurality of base stations and are positioned in different frequency bands from each other, so as to enhance frequency usage efficiency from the viewpoint of a terminal or a base station. The terminal may be simultaneously connected to a first base station (as an example, the first base station may be a base station which provides a service by using a long term evolution (LTE) technology or a 4th generation mobile communication technology) and a second base station (as an example, the second base station may be a base station which provides a service by using a new radio (NR) technology or a 5th generation mobile communication technology), wherein frequency resources used by the base stations may be positioned in different bands from each other, respectively. In this case, the terminal may perform RRC access through the first base station and receive a serviced function (as an example, connectivity management, mobility management, or the like) provided in a control plane, and additional wireless resources for transmitting or receiving data through the second base station may be provided. At this time, in such a dual connectivity technology, dual connectivity in which a first base station uses an LTE communication system and a second base station uses dual connectivity using an NR communication system may be referred to as evolved universal terrestrial radio access (E-UTRA) - NR dual connectivity (EN-DC). A communication system to which the disclosure is applied is not limited to the EN-DC, and the disclosure may be applied to all of various types of multi-connectivity including a communication system (NE-DC: NR - E-UTRA dual connectivity) in which a first base station uses an NR technology and a second base station uses an LTE technology, a communication system in which a first base station and a second base station use an LTE technology, and a communication system in which a first base station and a second base station use an NR technology. In addition, the disclosure may be applied in case of carrier aggregation. Moreover, the disclosure may also be applied in case that a first system using a first communication technology and a second system using a second communication technology are implemented in one device or in case that a first base station and a second base station are positioned in the same geographic position, wherein the first communication technology and the second communication technology may be one of an LTE system and an NR system.

The carrier aggregation technology and the dual connectivity or multi-connectivity technology have various technical advantages, and thus various studies have been actively conducted in the academic world, the industrial world, and the like since the carrier aggregation technology and the dual connectivity or multi-connectivity technology were introduced by the 3GPP standard.

The carrier aggregation technology and the dual connectivity or multi-connectivity technology have similarities in that one terminal transmits or receives a signal by simultaneously using a plurality of frequency resources positioned in different frequency bands from each other. However, in case that one terminal transmits or receives a signal by simultaneously using a plurality of frequency resources positioned in different frequency bands from each other, an internal interference signal such as harmonic interference and inter-modulation distortion (IMD) may be caused to a specific frequency band reception end of the terminal according to frequency combination and terminal hardware and implementation characteristics, and thus the reception performance of the terminal may be deteriorated. Hereinafter, for convenience, a description will be made based on a system to which a dual connectivity technology is applied. However, the disclosure is not limited thereto, and the disclosure may also be applied to a system to which a carrier aggregation technology and a multi-connectivity technology are applied.

<FIG> illustrates a system in which IMD interference occurs according to an embodiment of the disclosure.

Referring to <FIG>, inter-modulation distortion (IMD) may occur in a system composed of a plurality of base stations <NUM> and <NUM> which support one or more serving cells or cell groups, and a terminal <NUM> which transmits or receives a signal by simultaneously using a plurality of frequency resources positioned in different frequency bands from each other, the frequency bands being supported by the plurality of base stations. The plurality of base stations <NUM> and <NUM> may support serving cells or cell groups of different frequency bands from each other. <FIG> illustrates, as an example, a situation in which, from among the plurality of base stations <NUM> and <NUM>, a first base station <NUM> supports a master cell group (MCG) <NUM>, and a second base station <NUM> supports a secondary cell group (SCG) <NUM>, but the disclosure is not limited thereto. In addition, hereinafter, it is disclosed as an example in the disclosure that an MCG supported by the first base station <NUM> is operated based on frequency division duplexing (FDD) and that an SCG supported by the second base station <NUM> is operated based on time division duplexing (TDD), but the disclosure is not limited thereto. Moreover, hereinafter, the disclosure will describe, as an example, EN-DC in which the first base station <NUM> controlling an MCG uses an LTE communication system, and the second base station <NUM> controlling an SCG uses an NR communication system. However, the disclosure is not limited thereto, and the disclosure may be applied to an arbitrary system composed of a terminal and base stations for operating different frequency bands from each other. In this case, a base station for operating a low frequency band from among different frequency bands from each other may correspond to the first base station <NUM>, and a base station for operating a high frequency band may correspond to the second base station <NUM>. Hereinafter, an LTE communication system and an NR communication system disclosed according to the description of EN-DC as an example may be understood as being replaced by an arbitrary communication system operated by the first base station <NUM> for operating a low frequency band and an arbitrary communication system operated by the second base station <NUM> for operating a high frequency band, respectively. In addition, the disclosure is not limited to a situation in which the first base station <NUM> and the second base station <NUM> are implemented as separate base stations, and the disclosure may be applied to a case where a plurality of cell groups of different frequency bands are operated by one base station.

As illustrated in <FIG>, in case of a system in which transmission or reception of a signal between a plurality of base stations <NUM> and <NUM> and a terminal <NUM> is simultaneously performed in different frequency bands, due to inter-modulation distortion caused by harmonic components of uplink signals of the different frequency bands from each other, the reception performance of receiving a downlink in a low frequency from a first base station <NUM> may be deteriorated.

<FIG> illustrates wireless resources in which IMD interference occurs in EN-DC according to an embodiment of the disclosure.

Referring to <FIG>, a terminal <NUM> may transmit or receive a downlink (DL) signal <NUM> and an uplink (UL) signal <NUM> in an LTE FDD-based MCG supported by a first base station <NUM>, and may simultaneously transmit or receive a downlink (DL) signal <NUM> and an uplink (UL) signal <NUM> in an NR TDD-based SCG supported by a second base station <NUM>. At this time, in case of a slot <NUM> in which the terminal <NUM> simultaneously performs LTE FDD UL transmission <NUM> to the first base station <NUM> and NR TDD UL transmission <NUM> to the second base station <NUM>, the performance of LTE FDD DL reception <NUM> from the first base station <NUM> may be deteriorated due to IMD interference. Accordingly, a method for preventing deterioration in the DL reception performance of a terminal <NUM> due to such IMD interference is needed.

<FIG> illustrates a resource operation for IMD interference avoidance according to an embodiment of the disclosure.

In the 3rd generation partnership project (3GPP) release <NUM> standard, a single uplink operation (SUO) technology was introduced as a solution using a base station operation for IMD interference occurring in EN-DC. An SUO is a technology of avoiding IMD interference with a time division multiplexing-based (TDM-based) scheduling control scheme. According to the SUO technology, a base station designates, by using uplink-downlink configuration (UL-DL configuration) and HARQ subframe offset which are applied to a LTE TDD system, a subframe <NUM> to which a terminal may transmit a UL signal in an LTE FDD system, such that one terminal simultaneously transmits an LTE frequency division duplexing (FDD) UL signal and an NR time division duplexing (TDD) UL signal to the same subframe so as not to cause IMD interference in an LTE FDD DL signal. A terminal may perform LTE FDD UL signal transmission only in a designated subframe, and thus IMD interference may be avoided by preventing NR UL and LTE UL signals from being simultaneously transmitted. However, in case of a method based on an SUO illustrated in <FIG>, a terminal does not transmit a UL signal in a subframe <NUM> other than a designated LTE FDD UL subframe, and thus efficiency of resource utilization may be deteriorated.

<FIG> illustrates a method for configuring, as an unused subframe, a part of uplink or downlink subframes in an LTE FDD system. Referring to <FIG>, a base station or a scheduler may selectively configure, as an unused subframe, a subframe <NUM> and <NUM> overlapping an NR TDD UL slot <NUM> from among LTE FDD UL subframes or LTE FDD DL subframes. That is, a part of subframes <NUM> overlapping an NR TDD UL slot <NUM> from among the LTE FDD UL subframes may be configured as an unused subframe, or a part of subframes <NUM> overlapping the NR TDD UL slot <NUM> from among the LTE FDD DL subframes may be configured as an unused subframe. The position of an unused subframe illustrated in <FIG> is merely for exemplification and may be arbitrarily configured. Via such a method, NR TDD UL transmission and LTE FDD UL transmission are prevented from being simultaneously performed, or LTE FDD DL reception is prevented from being performed in a subframe in which NR TDD UL transmission and LTE FDD UL transmission are simultaneously performed, such that deterioration in LTE FDD DL reception performance may be prevented. However, identically in case of the method illustrated in <FIG>, a terminal <NUM> does not use a part of LTE DL subframes and a part of LTE UL subframes, and thus efficiency of resource utilization may be deteriorated.

The disclosure proposes a method for enhancing efficiency of wireless resource utilization while preventing deterioration in the reception performance of a terminal due to IMD interference by using, as a supplementary uplink (SUL) carrier or as LTE-NR coexistence, an unused LTE subframe which may occur when a method for IMD interference avoidance is applied as in <FIG> and <FIG>.

<FIG> illustrates a resource operation based on a supplementary uplink (SUL) according to an embodiment of the disclosure.

In a mobile communication system, service areas of an uplink and a downlink may not match due to differences in channel characteristics between the uplink and the downlink or differences in maximum transmission power, antenna structures, or the like between a terminal and a base station, and a downlink service area may be generally wider than an uplink service area. Accordingly, in order to support a wider uplink service area, a base station may utilize, as a supplementary uplink (SUL) band, a frequency band lower than a frequency band supported by the base station order. As an example, a <NUM> NR communication system usually uses a higher frequency band compared to an LTE communication system, and in this case, a base station for operating the <NUM> NR communication system may receive an uplink signal from a terminal by utilizing, as an SUL, a frequency band of the LTE communication system, which is a relatively low frequency band. A terminal <NUM> may receive configuration for both an NR uplink frequency and an SUL frequency. In this case, uplink transmission by the terminal <NUM> may be performed only in one of the NR uplink frequency and the SUL frequency at one time point.

In case of an SUO-based IMD avoidance method, LTE uplink transmission is allowed to be performed only in a part of LTE UL subframe <NUM> designated for a terminal such that an LTE FDD UL to a first base station <NUM> and an NR FDD UL to a second base station <NUM> do not simultaneously occur, and in this case, an undesignated subframe may correspond to an unused subframe <NUM>. <FIG> shows a method for using such an unused LTE UL subframe <NUM> as an NR SUL subframe <NUM>.

According to an embodiment, an unused LTE UL subframe <NUM> may be used as an SUL of an NR serving cell or an NR cell group other than an MCG <NUM> and an SCG <NUM> configured by a first base station <NUM> and a second base station <NUM>, respectively. At this time, the SUL of the other NR serving cell or NR cell group may correspond to an SUL of an NR carrier, in which no IMD occurs, and the SCG <NUM> operated by the second base station <NUM>.

According to the method illustrated in <FIG>, LTE FDD UL signal transmission and NR TDD UL signal transmission are not allowed to be simultaneously performed, and a unused LTE UL subframe may be utilized as an SUL of an NR carrier in which IMD does not occur, so as to prevent the occurrence of IMD interference and minimize waste of wireless resources.

<FIG> is a flowchart showing a resource method of a base station, based on a supplementary uplink (SUL), according to an embodiment of the disclosure.

In operation <NUM>, a base station may identify whether frequency bands of a first cell group and a second cell group configured for a terminal correspond to a frequency combination in which IMD interference may occur. In case of a frequency combination in which IMD interference does not occur (operation <NUM>, No), a signal may be transmitted or received according to a general method without performing operations disclosed by the disclosure. In case of a frequency combination in which IMD interference occurs (operation <NUM>, Yes), a base station may proceed to operation <NUM> to identify an LTE UL subframe configured as an unused resource. In operation <NUM>, a base station may configure, as an SUL, an LTE UL subframe configured as an unused resource, and may transmit or receive, based thereon, a signal in operation <NUM>. A method for configuring, as an SUL, an LTE UL subframe configured as an unused resource in operation <NUM> may follow the method described with reference to <FIG>.

A part or all of respective steps illustrated in <FIG> may be performed by a first base station <NUM>, a second base station <NUM>, or an arbitrary operator not illustrated, according to implementation, and information produced as a result of operations may be transmitted to and shared with another base station or operator as necessary.

<FIG> and <FIG> illustrate a resource operation based on LTE-NR coexistence illustrates according to various embodiments of the disclosure.

IMD interference which occurs as LTE UL transmission and NR UL transmission are simultaneously performed may affect the reception performance of an LTE DL operated in a low frequency band. Accordingly, such deterioration in the reception performance of an LTE DL may be prevented by using a part of LTE DL subframes as an NR DL resource which is less affected by IMD interference.

<FIG> illustrates a method for operating an LTE FDD resource as LTE-NR coexistence in the SUO-based IMD interference avoidance method described based on <FIG>. Referring to <FIG>, a second base station <NUM> for operating an NR communication system may operate an LTE band as LTE-NR coexistence by using a part of LTE FDD DL subframes <NUM> as a resource for an NR DL <NUM> and using a part of LTE FDD UL subframes <NUM> as a resource for an NR UL <NUM>. According to an embodiment, an LTE DL subframe <NUM> used as a resource for an NR DL <NUM> may be determined based on MBSFN configuration. According to MBSFN configuration configured for a terminal <NUM>, a part of LTE subframe may be configured as an MBSFN subframe, and at this time, a second base station <NUM> may use, as a resource for NR DL <NUM>, a part of subframes configured as MBSFN subframes.

<FIG> illustrates MBSFN subframe configuration according to an embodiment of the disclosure.

<FIG> illustrates that subframe indexes #<NUM>, #<NUM>, #<NUM>, #<NUM>, #<NUM>, and #<NUM> are configured as MBSFN subframes <NUM>. However, this is merely for exemplification, and the disclosure is not limited thereto. Re-referring to <FIG>, a second base station <NUM> may use, as resources for an NR DL, subframes corresponding to subframe indexes #<NUM> and #<NUM> configured as MBSFN subframes from among LTE DL subframes. According to an embodiment, an LTE UL subframe <NUM> used as a resource for an NR UL <NUM> may be determined as an LTE UL subframe overlapping a slot for UL transmission on an NR SCG configured by a second base station <NUM>. According to an embodiment, an NR UL resource <NUM> operated as LTE-NR coexistence in an LTE band may be used as a resource for transmitting an HARQ-ACK signal for a received signal to an NR DL resource operated as LTE-NR coexistence in the LTE band.

<FIG> illustrates a method for utilizing an LTE FDD resource as LTE-NR coexistence in the IMD interference avoidance method described based on <FIG>. Referring to <FIG>, a second base station <NUM> for operating an NR communication system may operate an LTE band as LTE-NR coexistence by using a part of LTE FDD DL subframes <NUM> as a resource for an NR DL <NUM> and using a part of LTE FDD UL subframes <NUM> as a resource for an NR UL <NUM>. According to an embodiment, in operating LTE-NR coexistence, an LTE DL subframe <NUM> used as a resource for an NR DL <NUM> and an LTE UL subframe <NUM> used as a resource for an NR UL <NUM> may be determined based on an LTE DL subframe configured as an unused subframe and an LTE UL subframe configured as an unused subframe, in describing <FIG> proposed a method for configuring, as an unused subframe, a part of LTE FDD DL subframes and LTE FDD UL subframes so as to prevent NR TDD UL transmission and LTE FDD UL transmission from being simultaneously performed or prevent LTE FDD DL reception from being performed in a subframe in which NR TDD UL transmission and LTE FDD UL transmission are simultaneously performed, and in the disclosure, a part of LTE DL and LTE UL subframes configured as an unused subframe may be used as an NR DL or NR UL resource based on LTE-NR coexistence. According to an embodiment, an NR UL resource operated as LTE-NR coexistence in an LTE band may be used as a resource for transmitting an HARQ-ACK signal for a received signal to an NR DL resource operated as LTE-NR coexistence in the LTE band.

<FIG> is a flowchart illustrating a resource method of a base station, based on NR-LTE coexistence, according to an embodiment of the disclosure.

Referring to <FIG>, in operation <NUM>, a base station may identify whether frequency bands of a first cell group and a second cell group configured for a terminal correspond to a frequency combination in which IMD interference may occur. In case of a frequency combination in which IMD interference does not occur (operation <NUM>, No), separate interference control is not required, and thus a signal may be transmitted or received according to a general method without performing operations disclosed by the disclosure. In case of a frequency combination in which IMD interference occurs (operation <NUM>, Yes), a base station may proceed to operation <NUM> to identify an LTE DL subframe and an LTE UL subframe configured as unused resources. In operation <NUM>, a base station may configure, as an NR DL resource, an LTE DL subframe configured as an unused resource, may configure an LTE UL subframe as an NR UL resource, and may transmit or receive, based thereon, a signal in operation <NUM>. A method for configuring, as an NR DL resource and an NR UL resource, an LTE DL subframe and an LTE UL subframe configured as unused resources in operation <NUM> may follow the methods described with reference to <FIG>.

A scheduling method for efficiency use of resources and interference control in a situation wherein IMD interference exists has been described, and hereinafter, a scheduling method in a situation where harmonic interference (HI) exists will be described.

<FIG> illustrates a system in which harmonic interference (HI) occurs according to an embodiment of the disclosure.

Referring to <FIG>, harmonic interference (HI) may occur in a system composed of a plurality of base stations <NUM> and <NUM> which support one or more serving cells or cell groups, and a terminal <NUM> which transmits or receives a signal by simultaneously using a plurality of frequency resources positioned in different frequency bands from each other, the frequency bands being supported by the plurality of base stations. The plurality of base stations <NUM> and <NUM> may support serving cells or cell groups of different frequency bands from each other. <FIG> illustrates, as an example, a situation in which, from among the plurality of base stations <NUM> and <NUM>, the first base station <NUM> supports a master cell group (MCG) <NUM>, and the second base station <NUM> supports a secondary cell group (SCG) <NUM>, but the disclosure is not limited thereto. In addition, hereinafter, it is disclosed as an example in the disclosure that an MCG is operated based on frequency division duplexing (FDD) and that an SCG is operated based on time division duplexing (TDD), but the disclosure is not limited thereto. Moreover, hereinafter, the disclosure will describe, as an example, EN-DC in which the first base station <NUM> controlling an MCG uses an LTE communication system, and the second base station <NUM> controlling an SCG uses an NR communication system. However, the disclosure is not limited thereto, and the disclosure may be applied to an arbitrary system composed of a terminal and base stations for operating different frequency bands from each other. In this case, a base station for operating a low frequency band from among different frequency bands from each other may correspond to the first base station <NUM>, and a base station for operating a high frequency band may correspond to the second base station <NUM>. Hereinafter, an LTE communication system and an NR communication system disclosed according to the description of EN-DC as an example may be understood as being replaced by an arbitrary communication system operated by the first base station <NUM> for operating a low frequency band and an arbitrary communication system operated by the second base station <NUM> for operating a high frequency band, respectively. In addition, the disclosure is not limited to a situation in which the first base station <NUM> and the second base station <NUM> are implemented as separate base stations, and the disclosure may be applied to a case where a plurality of cell groups of different frequency bands are operated by one base station. In case of such a system in which transmission or reception of a signal is simultaneously performed in different frequency bands from each other, the reception performance of a DL signal in a high frequency band may be deteriorated due to a harmonic component of a UL signal of a low frequency band.

<FIG> illustrates wireless resources in which harmonic interference (HI) occurs in EN-DC according to an embodiment of the disclosure.

Referring to <FIG>, a terminal <NUM> may transmit or receive an uplink (UL) signal <NUM> in an LTE FDD-based MCG supported by a first base station <NUM>, and may simultaneously transmit or receive a downlink (DL) signal <NUM> and an uplink (UL) signal <NUM> in an NR TDD-based SCG supported by a second base station <NUM>. At this time, in case that the terminal <NUM> transmits an LTE FDD UL signal <NUM> to the first base station <NUM> and simultaneously receives an NR DL signal <NUM> from the second base station <NUM>, the performance of receiving the NR DL signal <NUM> from the second base station <NUM> may be deteriorated due to harmonic interference. Accordingly, a method for preventing deterioration in the DL reception performance of a terminal due to such harmonic interference is needed.

<FIG> illustrates a resource operation for harmonic interference avoidance according to an embodiment of the disclosure.

Referring to <FIG>, a resource operation for harmonic interference avoidance in a situation (hereinafter, a partial LTE UL) in which, for IMD interference avoidance described above, a part of LTE UL subframe is configured as an unused subframe. That is, <FIG> shows an example of a resource operation for avoiding IMD interference and harmonic interference in case that both IMD interference and harmonic interference exist. Referring to <FIG>, in case of an NR DL signal received in a slot <NUM> corresponding to a part of LTE UL subframe (a subframe to which an LTE UL signal is not transmitted) <NUM> which is configured as an unused subframe to avoid IMD interference from among NR DL signals, deterioration in reception performance due to harmonic interference may not occur. However, in case of an NR DL signal received in a slot <NUM> corresponding to an LTE UL subframe (a subframe to which an LTE UL signal is transmitted) <NUM> which is not configured as an unused subframe from among NR DL signals, deterioration in reception performance due to harmonic interference may occur. In this case, a second base station <NUM> may avoid harmonic interference by not using a part or all of frequency bands of an NR DL slot <NUM> in which deterioration in reception performance occurs. However, in this case, since a part of LTE UL subframe <NUM> is not used for IMD interference avoidance and a part or all of frequency bands of a part of NR DL slot <NUM> is/are not used for harmonic interference avoidance, efficiency of resource utilization may be deteriorated.

Referring to <FIG>, a resource operation for harmonic interference avoidance in a situation in which IMD interference avoidance described above is not considered, that is, a situation (hereinafter, a full LTE UL) in which it is assumed that only harmonic interference exists. Likewise, in case that IMD interference avoidance is not considered, an LTE UL signal may be transmitted in all LTE UL subframes in contrast to the case described in <FIG>, and thus deterioration in the reception performance due to harmonic interference may occur in all slots <NUM> in which an NR DL signal is received. Accordingly, a second base station <NUM> may not use a part or all of frequency bands <NUM> of an NR DL slot <NUM> in which deterioration in reception performance occurs. In this case, since a part or all of NR DL slots is/are not used for harmonic interference avoidance, efficiency of resource utilization may be deteriorated.

The disclosure proposes a method for enhancing efficiency of wireless resource utilization while preventing deterioration in the reception performance of a terminal due to harmonic interference by using, as a resource for an NR SUL or a stand-alone (SA) NR cell, an unused LTE UL subframe or NR DL slot according to the harmonic interference avoidance methods described based on <FIG> and <FIG>.

<FIG> illustrates a resource method in a partial LTE UL according to an embodiment of the disclosure.

Referring <FIG>, in a partial LTE UL situation in which both IMD interference and harmonic interference exist, a part of LTE UL subframe <NUM> may be configured as an unused resource to avoid IMD interference, and a part or all of frequency bands of a part of NR DL slot <NUM> may be configured as an unused resource to avoid harmonic interference. <FIG> shows a method in which, from among resources configured as unused resources, a part of unused LTE UL subframes <NUM> is used as an NR SUL <NUM> of an NR carrier in which harmonic interference does not occur, and a part of unused NR DL slots <NUM> is used as a DL resource <NUM> of a stand-alone (SA) NR cell group. The use of an LTE UL subframe as an NR SUL was described above with reference to <FIG>, and thus a detailed description thereof will be omitted here. The IMD interference and harmonic interference described above occur by a frequency combination of an MCG <NUM> controlled by a first base station <NUM> and an SCG <NUM> controlled by a second base station <NUM> in a dual connectivity (DC) situation, and to avoid this, a part of unused NR DL slots <NUM> may be configured as a DL slot (hereinafter, an SA DL slot) <NUM> of an SA NR cell group rather than a DL slot of the SCG <NUM>. <FIG> illustrates that all of unused DL slot frequency bands are used as SA DLs. However, as described above, only a part of NR DL slot frequency bands may be configured as an unused resource, and in this case, only a part of frequency bands of an unused DL slot may be used as an SA DL resource. According to an embodiment, a part or all of frequency bands of at least one of NR UL slots <NUM> may be configured as an UL slot (hereinafter, an SA UL slot) <NUM> of an SA NR cell group. Such an SA UL slot <NUM> may be configured regardless of whether an NR UL resource is configured as an unused resource, and may be used to transmit an HARQ-ACK signal for a signal transmitted or received through the SA DL slot <NUM>.

<FIG> illustrates a resource method in a full LTE UL according to an embodiment of the disclosure.

Referring to <FIG>, in a full LTE UL situation in which IMD interference is not considered, a part or all of frequency bands of all NR DL slots may be configured as (an) unused resource(s) to avoid harmonic interference. <FIG> shows a method for using a part of unused NR DL slots <NUM> as a DL resource <NUM> of a stand-alone (SA) NR cell group. The IMD interference and harmonic interference described above occur by a frequency combination of an MCG <NUM> controlled by a first base station <NUM> and an SCG <NUM> controlled by a second base station <NUM> in a dual connectivity (DC) situation, and to avoid this, a part of unused NR DL slots <NUM> may be configured as a DL slot (hereinafter, an SA DL slot) <NUM> of an SA NR cell group rather than a DL slot of the SCG <NUM>. As illustrated in <FIG>, in case that only a part of NR DL slot <NUM> frequency bands is configured as an unused resource, only a part of frequency bands of an unused DL slot <NUM> may be used as an SA DL resource <NUM>. According to an embodiment, a part or all of frequency bands of at least one of NR UL slots <NUM> may be configured as a UL slot (hereinafter, an SA UL slot) <NUM> of an SA NR cell group. Such an SA UL slot <NUM> may be configured regardless of whether an NR UL resource is configured as an unused resource, and may be used to transmit an HARQ-ACK signal for a signal transmitted or received through the SA DL slot.

<FIG> is a flowchart illustrating a resource method of a base station for harmonic interference avoidance according to an embodiment of the disclosure.

Referring to <FIG>, in operation <NUM>, a base station may identify whether frequency bands of a first cell group and a second cell group configured for a terminal correspond to a frequency combination in which harmonic interference may occur. In case of a frequency combination in which harmonic interference does not occur (operation <NUM>, No), a signal may be transmitted or received according to a general method without performing operations disclosed by the disclosure. In case of a frequency combination in which harmonic interference occurs (operation <NUM>, Yes), a base station may proceed to operation <NUM> to identify whether an LTE UL resource corresponding to a first cell group is a partial LTE UL or a full LTE UL. At this time, a partial LTE UL may represent a situation in which a part of LTE UL subframes is configured as an unused resource as IMD interference exists, and a full LTE UL may represent a situation in which all LTE UL subframes are used regardless of IMD interference. In case that an LTE UL resource corresponding to a first cell group corresponds to a partial LTE UL (operation <NUM>, partial LTE UL), a base station may identify an LTE UL subframe and an NR DL slot configured as unused resources in operation <NUM>. In operation <NUM>, a base station may configure, as an SUL, an LTE UL subframe configured as an unused resource, may configure, as an SA DL, an NR DL slot configured as an unused resource, may configure, as an SA UL, a part of NR UL slot, and may transmit or receive, based thereon, a signal in operation <NUM>. In case that an LTE UL resource corresponding to a first cell group corresponds to a full LTE UL (operation <NUM>, full LTE UL), a base station may identify an NR DL slot configured as an unused resource in operation <NUM>. In operation <NUM>, a base station may configure, as an SA DL, an NR DL slot configured as an unused resource, may configure, as an SA UL, a part of NR UL slot, and may transmit or receive, based thereon, a signal in operation <NUM>.

<FIG> is a flowchart illustrating an operation of a base station for IMD interference or harmonic interference avoidance according to an embodiment of the disclosure.

Referring to <FIG>, in operation <NUM>, a base station may identify whether frequency bands of a first cell group and a second cell group configured for a terminal correspond to a frequency combination in which IMD interference or harmonic interference may occur. In case of a frequency combination in which IMD interference or harmonic interference does not occur (operation <NUM>, No), a signal may be transmitted or received according to a general method without performing operations disclosed by the disclosure. In contrast, in case that IMD interference or harmonic interference occurs (operation <NUM>, Yes), a base station may proceed to operation <NUM> to identify a resource configured as an unused resource from among resources of a first cell group and a second cell group. In operation <NUM>, a base station may schedule a resource configured as an unused resource, so as to prevent the occurrence of IMD interference or harmonic interference, and may transmit or receive, based thereon, a signal in operation <NUM>. A specific method for preventing the occurrence of IMD interference or harmonic interference from a resource configured as an unused resource in operation <NUM> may follow the methods described with reference to <FIG>.

A part or all of respective steps illustrated in <FIG> may be performed by a first base station <NUM> or <NUM>, a second base station <NUM> or <NUM>, or an arbitrary operator not illustrated, according to implementation, and information produced as a result of operations may be transmitted to and shared with another base station or operator as necessary.

<FIG> is a block diagram illustrating a base station device which may carry out the disclosure according to an embodiment of the disclosure.

Referring to <FIG>, a base station <NUM> may include a transceiver <NUM>, a controller <NUM>, a storage <NUM>, and a backhaul connector <NUM>. The transceiver may transmit or receive a signal to or from a terminal. To this end, the transceiver <NUM> may include an RF transmitter which up-converts and amplifies the frequency of a transmitted signal, an RF receiver which performs low-noise amplification on a received signal and down-converts the frequency thereof, and the like. In addition, the transceiver <NUM> may receive a signal through a wireless channel and output the signal to the controller <NUM>, and may transmit, through a wireless channel, a signal output from the controller <NUM>. The backhaul connector <NUM> may transmit or receive a signal to or from a core network and another base station which controls another cell group.

The controller <NUM> controls the transceiver <NUM> and the backhaul connector <NUM> to carry out embodiments described in the disclosure.

<FIG> is a block diagram illustrating a terminal device which may carry out the disclosure according to an embodiment of the disclosure.

Referring to <FIG>, a terminal <NUM> may include a transceiver <NUM>, a controller <NUM>, and a storage <NUM>. The transceiver may transmit or receive a signal to or from a base station. To this end, the transceiver <NUM> may include an RF transmitter which up-converts and amplifies the frequency of a transmitted signal, an RF receiver which performs low-noise amplification on a received signal and down-converts the frequency thereof, and the like. In addition, the transceiver <NUM> may receive a signal through a wireless channel and output the signal to the controller <NUM>, and may transmit, through a wireless channel, a signal output from the controller <NUM>. The transceiver <NUM> receives a resource allocation signal from a base station, and the resource allocation signal may be information indicating UL grant, DL allocation, and other signal transmission resources. The controller <NUM> transmits or receives UL and DL signals according to the resource allocation signal.

According to the above-described embodiments, the reception performance of a terminal caused by harmonic interference and inter-modulation distortion which may occur in a mobile communication system supporting a carrier aggregation technology, a dual connectivity/multi-connectivity technology, or the like which simultaneously uses a plurality of frequency resources is prevented from being deteriorated, and wasted resources are minimized via interference control, such that the transmission/reception performance of a terminal and a base station may be enhanced.

Claim 1:
A method performed by a first base station in a communication system, the method comprising:
identifying that a first frequency band associated with a first cell and a second frequency band associated with a second cell are a frequency combination in which inter-modulation distortion, IMD, interference or harmonic interference occurs;
identifying resource assignment information allocating resources for a terminal, wherein a resource not used by a first cell is allocated as a resource for a cell other than a first cell;
transmitting the resource assignment information to a terminal; and
transmitting or receiving a signal based on the resource assignment information,
wherein, in case that the first frequency band associated with the first cell and the second frequency band associated with the second cell are a frequency combination in which IMD interference occurs, a downlink, DL, resource not used by the first cell is allocated as a DL resource for the second cell, and an uplink, UL, resource not used by the first cell is allocated as an UL resource for the second cell.