KR20160089702A - Method and Apparatus for Carrier Aggregation in Heterogeneous Network System - Google Patents

Abstract

The present invention relates to a method and an apparatus for efficiently performing carrier aggregation (CA) in consideration of a kind of the cell of license bandwidth and non-license bandwidth and load quality, with an effective selection method of a secondary cell for multiband CA and cell classification according to a kind of the frequency of the license bandwidth and the non-license bandwidth, in heterogeneous network (HetNet) wireless network where the license frequency bandwidth coexists with the non-license frequency bandwidth. The apparatus includes a measurement managing part and a frequency determining part.

Description

TECHNICAL FIELD The present invention relates to a CA method and apparatus for a heterogeneous network system,

The present invention relates to a CA (Carrier Aggregation) method and apparatus in a mobile communication network, and more particularly, to a method and apparatus for receiving a license in a HetNet (heterogeneous network) system in which a license frequency band and a license- The present invention relates to a method and apparatus for performing an efficient CA in consideration of both the band and the license-exempt band.

In order to accommodate the increasing wireless traffic capacity, a macrocell of a licensed band with a large coverage of high power by a Macro base station has unlicensed access with small coverage of small power by the femto base station / Heterogeneous network (Heterogeneous network) multi-band wireless network in which a small cell of a band coexist is spreading. That is, since it is difficult to satisfy the demand for the mobile service which is explosively increasing only in the band of the licensed frequency band allocated for the mobile communication service according to the LTE etc., LTE / 5G access networks using license-free frequency bands such as millimeter-wave and ISM will be introduced and spread.

However, in the existing mobile communication system, frequency merging is considered for a radio network composed only of a license band, optimal frequency merging according to frequency types is not supported, and a cell load of a traffic load due to a dense small- Frequency merging control considering deviation and dispersion is insufficient, utilization of multi-frequency possessed by a provider is inferior, and user quality improvement is limited. Therefore, efficient frequency merging technology is needed in HetNet wireless network.

As related prior art documents, Korean Patent Laid-Open No. 10-2012-0115986 (published on October 19, 2012), Japanese Laid-open Patent Application No. 2014-500685 (published on April 19, 2014), and the like can be referred to.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a HetNet (Heterogeneous network) wireless network in which a license frequency band and a license-exempt frequency band coexist, The present invention is to provide a method and an apparatus for efficiently performing a CA in consideration of a cell type and a load quality of a license band and a license-exempt band, as an effective selection method of a secondary cell for cell classification and multi-band CAs.

A CA (Carrier Aggregation) method in a heterogeneous network system according to an aspect of the present invention for achieving the above object is characterized in that a user terminal is connected to a macro cell base station at a primary frequency Receiving a mobile communication service; Periodically measuring the received signal strength between the at least one small cell base station and the at least one small cell base station installed in the vicinity of the macro cell base station and the load of the at least one small cell base station, And determining a frequency of a license band or a license-exempt band used by the at least one small cell base station as a secondary frequency to be additionally used by the user terminal in the mobile communication service.

The received signal strength may be a reference signal received power (RSRP), a reference signal received quality (RSRQ), or a signal-to-interference ratio (SINR). The load may be a usage amount of radio resources.

Wherein the managing comprises: selecting a first candidate group of the at least one small cell base station in which the received signal strength is greater than a first threshold at the user terminal; And selecting the final candidate group in which the load is smaller than the second threshold among the at least one small cell base station in the first candidate group.

The determining step includes determining one or more of the secondary frequencies according to a predetermined number of CA possible frequencies.

Wherein the determining step comprises the step of determining whether any of the frequencies used by the plurality of small cell base stations whose difference in the received signal strength is smaller than the threshold value (for example, the frequency of the license band) To the secondary frequency.

Wherein the determining step comprises the step of, when the predetermined number of CA frequencies is equal to or greater than 3, determining whether any of the frequencies used by the plurality of small cell base stations whose difference in received signal strength is smaller than the threshold (e.g., Determining one of the secondary frequencies; And determining the remainder of the secondary frequency according to a magnitude of the received signal strength among frequencies other than the determined frequency among the frequencies used by the plurality of small cell base stations.

In addition, a CA (Carrier Aggregation) management apparatus for supporting a heterogeneous network system according to another aspect of the present invention is characterized in that, while a user terminal receives a mobile communication service through a macro cell base station at a primary frequency, A measurement manager for periodically measuring a received signal strength between the at least one small cell base station and the user terminals and the load of the at least one small cell base station and managing the measured signal intensity in a database; And a frequency determiner for determining a frequency of a license band or a license-exempt band used by the at least one small cell base station as a secondary frequency to be additionally used by the user terminal in the mobile communication service.

The received signal strength may be a reference signal received power (RSRP), a reference signal received quality (RSRQ), or a signal-to-interference ratio (SINR). The load may be a usage amount of radio resources.

Wherein the measurement management unit selects a first candidate group of the at least one small cell base station in which the received signal strength is greater than a first threshold at the user terminal and selects the second candidate group among the at least one small cell base station in the first candidate group, Select a final candidate that is smaller than the threshold.

The frequency determining unit may determine one or a plurality of the secondary frequencies according to a predetermined number of CA possible frequencies.

The frequency determining unit may determine a frequency (for example, a frequency of a license band) among frequencies used by a plurality of small cell base stations whose difference in received signal strength is smaller than a threshold value when the predetermined number of CA possible frequencies is 2 The secondary frequency can be determined.

The frequency determining unit may determine a frequency (for example, a frequency of a license band) among frequencies used by a plurality of small cell base stations whose difference in the received signal strength is smaller than a threshold value, when the predetermined number of CA- It is possible to determine the remaining of the secondary frequency according to the magnitude of the received signal strength among the frequencies other than the determined frequency among the frequencies used by the plurality of small cell base stations.

According to the CA method and apparatus in the heterogeneous network system environment according to the present invention, the cell type according to the frequency band of the license band and the license-exempted band, and the cell type of the license band and the license- By implementing efficient CA considering load quality, it is possible to provide cheap and high quality mobile communication service by making it easy to construct and operate a broadband unlicensed frequency-based small cell, and to provide an optimal CA in a cell environment in which macro cells and small cells overlap The speed and quality of the mobile communication service can be improved for the user terminal.

1 is a view for explaining a heterogeneous network system environment according to an embodiment of the present invention.
2 is a block diagram of a CA (Carrier Aggregation) management apparatus for supporting heterogeneous network systems according to an embodiment of the present invention.
3 is a flowchart illustrating a CA (Carrier Aggregation) method in a heterogeneous network system according to an embodiment of the present invention.
4 is an example of a database for explaining a list of the secondary cell (SCell) candidates in the description of FIG.
5 is an example of a secondary cell (SCell) selected in the example of FIG.
6 is a diagram for explaining an example of a method for implementing a CA management apparatus in a heterogeneous network system according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same components are denoted by the same reference symbols as possible. In addition, detailed descriptions of known functions and / or configurations are omitted. The following description will focus on the parts necessary for understanding the operation according to various embodiments, and a description of elements that may obscure the gist of the description will be omitted. Also, some of the elements of the drawings may be exaggerated, omitted, or schematically illustrated. The size of each component does not entirely reflect the actual size, and therefore the contents described herein are not limited by the relative sizes or spacings of the components drawn in the respective drawings.

1 is a view for explaining a heterogeneous network system environment according to an embodiment of the present invention.

Referring to FIG. 1, a system for providing a mobile communication service according to an embodiment of the present invention includes a macro cell (hereinafter, referred to as " macro cell ") that provides a service to a user terminal using a frequency of a licensed band such as Long Term Evolution The cell coverage 11 of the base station 10 includes a femto (or pico) base station providing services to the user terminal in each small cell coverage 21, 31 and 41, a small cell base station 20, 40).

The digital device DU of the macro cell base station 10 relays the user terminal in the cell coverage 11 of the macro cell base station 10 to access the server of the macro network (wireless core network) to receive the service. The user terminal may be a mobile terminal such as a smart phone, a tablet PC, an iPad, a PDA, and a PMP, or may be a wired or wireless Internet (e.g., wired Internet, WiFi, WiBro, And may be various electronic devices capable of receiving a digital multimedia contents service through a mobile communication network (e.g., WCDMA, LTE, etc.).

The small cell base stations 20, 30 and 40 may relay the user terminal to the macro cell base station 10 in each small cell coverage 21, 31 and 41, Or regional) based services. The small cell base stations 20, 30 and 40 can support connection with a user terminal by using a frequency of a unlicensed band such as a short distance communication type (e.g., Zigbee, Bluetooth) or WiFi, And may support connection with a user terminal using a frequency. For example, in FIG. 1, the small cell base station 20 uses the first frequency of the license band, the small cell base station 30 uses the second frequency of the license band, and the small cell base station 40 uses the third frequency of the license- Can be used. Here, the first to third frequencies used by the small cell base stations 20, 30 and 40 are different from the frequency (primary frequency) of the license band used by the macro cell base station 10 for communication with the user terminal . Unlike the WiFi in the 2.6GHz band and the 5GHz band, unlicensed band frequencies are not allocated to specific operators, unlike LTE licensed band frequencies (eg, 900MHz and 1.8GHz). It is possible. Broadband frequency depletion is expected to increase the use of higher bandwidth (eg, 30 GHz millimeter waveband) for license-exempt small cells.

Herein, three small cell basestations 20, 30, and 40 are illustrated for convenience of explanation. However, in the cell coverage 11 of the macrocell base station 10, the connection relay between the user terminal and the macrocell base station 10 , The CA method of the present invention can be applied to all cases in which one or more small cell base stations using frequencies in the license band or the license-exempt band are installed.

In the HetNet (Heterogeneous network) wireless network in which the license band and the license-exempted band are coexisted, the present invention can be applied to the classification of a small cell according to the frequency band of the license band and the license- In order to be effective, it is possible to perform an efficient CA considering the cell type and load quality of licensed and license-exempted bands.

2 is a block diagram of a CA management apparatus 100 for supporting heterogeneous network systems according to an embodiment of the present invention.

2, a CA management apparatus 100 on a network according to an embodiment of the present invention may include a measurement management unit 110, a database 120, and a frequency determination unit 130. [ Each of the components of the CA management apparatus 100 may be implemented by hardware (e.g., a semiconductor processor), software, or a combination thereof. The CA management apparatus 100 may be included in the digital device DU of the macro cell base station 10 on the network or may be included in a base station controller (not shown) on a network that is responsible for overall control of a plurality of distributed macro cell base stations . As described below, in order to perform CA in a heterogeneous network system according to an embodiment of the present invention, necessary information (e.g., signal strength measurement information of user terminal, load of small cell base station Information, etc.) can be exchanged.

First, functions of components of the CA management apparatus 100 will be briefly described.

The database 120 stores attribute information such as a use frequency, a license band, or a cell attribute for use of the license-exempt band, which is constructed in the network environment and is used by one or more small cell base stations installed in the coverage area of the macro cell base station .

The measurement management unit 110 may include a user management unit 110 for managing a user with one or more small cell base stations in a macro cell base station coverage area installed around a macro cell base station while a user terminal receives a mobile communication service through a macro cell base station at a primary frequency, (E.g., RSRP, RSRQ, SINR, etc.) and the load of one or more small cell base stations (e.g., the usage amount of radio resources) between terminals can be periodically measured and managed in the database 120 as shown in FIG. . A reference signal received power (RSRP), a reference signal received quality (RSRQ), or a signal-to-interference ratio (SINR) indicates a size of received power or quality of a received signal with respect to a predetermined reference signal, Value, which is well described in the general communication theory, so that detailed description is omitted.

The frequency determining unit 130 may determine the frequency of the license band or the license-exempt band used by the at least one small cell base station as a secondary frequency to be additionally used by the user terminal in the mobile communication service. In particular, since the small cell base station using the frequency of the license-exempt band is relatively difficult to guarantee the quality of service due to frequency sharing or interference with the WiFi network or the unlicensed small cell base station of another mobile communication provider, (secondary cell) to be used as a secondary cell.

In order to determine such a secondary frequency, the measurement management unit 110 determines whether or not the first-order candidate group of the at least one small-cell base station, which is greater than the first threshold (e.g., RSRP -90 dBm) And a final candidate group (refer to FIG. 4) in which the above load is smaller than the second threshold (50% of the radio resource usage) among the one or more small cell base stations in the primary candidate group can be selected.

The frequency determining unit 130 compares the received signal strength difference of the small cell base stations of the final candidate group with the number of CA possible frequencies in the final candidate group (see FIG. 4) as described above, the secondary frequency can be determined.

Hereinafter, a CA (Carrier Aggregation) management method through the CA management apparatus 100 in a heterogeneous network system according to an embodiment of the present invention will be described in detail with reference to the flowchart of FIG.

First, the database 120 stores attribute information (see FIG. 4) such as a use frequency used by one or more small cell base stations installed in the coverage area corresponding to the macro cell base station on the network, (S10).

The measurement management unit 110 may include a user management unit 110 for managing a user with one or more small cell base stations in a macro cell base station coverage area installed around a macro cell base station while a user terminal receives a mobile communication service through a macro cell base station at a primary frequency, (E.g., RSRP, RSRQ, SINR, etc.) and the load of one or more small cell base stations (e.g., the usage amount of radio resources) between terminals can be periodically measured and managed in the database 120 as shown in FIG. (S20).

For this purpose, the measurement management unit 110 may periodically request the user terminal to report the strength of the received signal strength (e.g., RSRP, RSRQ, SINR, etc.) It is possible to measure the signal strength (e.g., RSRP, RSRQ, SINR, etc.) and report it to the CA management apparatus 100 such as the digital device DU of the macro cell base station or the base station controller on the network. In addition, the measurement management unit 110 may periodically request a load (e.g., a usage amount of radio resources) to one or more surrounding small-cell base stations, and the corresponding small-cell base station (s) ) To the CA management apparatus 100 such as the digital device DU or the base station controller of the macro cell base station 10 on the network.

(E.g., RSRP, RSRQ, SINR, etc.) between the user terminal and at least one small cell base station and the load (e.g., usage amount of radio resources) of the at least one small cell base station During the periodic measurement and management, as shown in FIG. 4, the first candidate group of one or more small cell base stations (the small group of FIG. 4 in FIG. 4) in which the received signal strength is larger than the first threshold (for example, RSRP- (The cells 1, 2, 3, and 4) are selected, and the final candidate group (the small cell of FIG. 4) in which the above load is smaller than the second threshold 1, 3, 4) can be selected (S30).

Accordingly, the frequency determining unit 130 may determine the frequency of the license band or the license-exempt band used by the at least one small cell base station as a secondary frequency to be additionally used by the user terminal in the mobile communication service (S40). That is, the frequency determining unit 130 compares the difference in received signal strength of the small cell base stations of the final candidate group according to the number of CA possible frequencies in the final candidate group (see the small cells 1, 3, and 4 in FIG. 4) To determine one or more secondary frequencies.

For example, when the predetermined number of CA possible frequencies is 2, the frequency determining unit 130 determines whether the difference in the received signal strengths (e.g., RSRP, RSRQ, SINR, etc.) between the small cells in the above- (E.g., the frequency of the small cell 3 in the license band in FIG. 4) among the frequencies used by the plurality of small cell base stations (see the small cells 1, 3 and 4 in FIG. 4) ) Can be determined as the secondary frequency (see Fig. 5). It is preferable to select the small cell frequency of the license band as the secondary frequency since the small cell base station using the frequency of the license-exempt band is relatively difficult to guarantee the quality of service due to frequency sharing or interference with the WiFi network. If the frequency band used by the small cell base station does not have a license band, the frequency of the license-exempt band can be selected as a secondary frequency for the auxiliary cell.

For example, when the number of predetermined CA possible frequencies is 3 or more (when two or more secondary frequencies are determined), the frequency determining unit 130 determines the smallest inter-cell received signal strength (for example, RSRP Of the frequencies used by a plurality of small cell base stations (refer to the small cells 1, 3, and 4 of FIG. 4) in which the difference between the RSRP, RSRQ, SINR, (See FIG. 5), and the frequencies used by a plurality of small cell base stations (see small cells 1, 3 and 4 in FIG. 4) can be determined as one of the secondary frequencies The remaining frequency of the secondary frequency (e.g., the frequency of the small cell 1 in the license band in FIG. 4) can be determined according to the magnitude of the received signal strength among the frequencies other than the frequency determined as the secondary frequency.

(See small cells 1, 3 and 4 in Fig. 4) in which the difference in the received signal strength (e.g., RSRP, RSRQ, SINR, etc.) in the final candidate group is smaller than a threshold value (e.g., RSRP 10 dBm or the like) Is to avoid determining the frequency of an inaccurate small cell base station as a secondary frequency due to shaded areas, traffic congestion areas, and the like.

As the frequency determining unit 130 determines the secondary frequency, the user terminal can receive the mobile communication service at the primary frequency according to the predetermined CA policy, and can also receive the mobile communication service through the secondary frequency, The service can be provided (S50).

According to a predetermined CA policy, a digital device DU of a macro cell base station on a network, a base station controller, or the like, can transmit / receive data to / from a user terminal through scheduling for allocating radio resources to a user terminal using a secondary frequency combined with a primary frequency It is possible to improve the speed and quality of the mobile communication service in a heterogeneous network system environment in which a macro cell and a small cell are overlapped.

As described above, the CA management in the heterogeneous network system environment according to the present invention can be applied to the cell 100 according to the frequency band of the licensed band and the license-exempted band, and the effective selection method of the secondary cell for the multi- By implementing an efficient CA in consideration of cell types and load quality of the band and the license-exempted band, it is possible to easily construct and operate a broadband unlicensed frequency-based small cell, thereby providing an inexpensive and high quality mobile communication service.

In the heterogeneous network system according to an embodiment of the present invention, the above-described components of the CA method, the functions thereof, and the like can be implemented by hardware, software, or a combination thereof. Furthermore, the above-described elements, functions, and the like according to an exemplary embodiment of the present invention may be embodied as computer-readable codes on a computer- or processor-readable recording medium when executed by one or more computers or processors. It is possible to do. The processor-readable recording medium includes all kinds of recording apparatuses in which data that can be read by the processor is stored. Examples of the recording medium readable by the processor include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and also a carrier wave such as transmission over the Internet. In addition, the processor readable recording medium may be distributed over networked computer systems so that code readable by the processor in a distributed manner can be stored and executed.

6 is a view for explaining an example of a method of implementing the CA management apparatus 100 in a heterogeneous network system according to an embodiment of the present invention. The components of the CA management apparatus 100 according to an embodiment of the present invention may be hardware, software, or a combination thereof, and may be implemented in the computing system 1000 as shown in FIG.

The computing system 1000 includes at least one processor 1100, a memory 1300, a user interface input device 1400, a user interface output device 1500, a storage 1600, And an interface 1700. The processor 1100 may be a central processing unit (CPU) or a memory device 1300 and / or a semiconductor device that performs processing for instructions stored in the storage 1600. Memory 1300 and storage 1600 may include various types of volatile or non-volatile storage media. For example, the memory 1300 may include a ROM (Read Only Memory) and a RAM (Random Access Memory).

Thus, the steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by processor 1100, or in a combination of the two. The software module may reside in a storage medium (i.e., memory 1300 and / or storage 1600) such as a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, You may. An exemplary storage medium is coupled to the processor 1100, which can read information from, and write information to, the storage medium. Alternatively, the storage medium may be integral to the processor 1100. [ The processor and the storage medium may reside within an application specific integrated circuit (ASIC). The ASIC may reside within the user terminal. Alternatively, the processor and the storage medium may reside as discrete components in a user terminal.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and specific embodiments and drawings. However, it should be understood that the present invention is not limited to the above- Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the essential characteristics of the invention. Therefore, the spirit of the present invention should not be construed as being limited to the embodiments described, and all technical ideas which are equivalent to or equivalent to the claims of the present invention are included in the scope of the present invention .

The measurement management unit 110,
In the database 120,
Frequency determining unit 130,

Claims (18)

In a CA (Carrier Aggregation) method in a heterogeneous network system,
Receiving a mobile communication service through a macro cell base station at a primary frequency;
Periodically measuring the received signal strength between the at least one small cell base station and the at least one small cell base station installed in the vicinity of the macro cell base station and the load of the at least one small cell base station, And
Determining a frequency of a license band or a license-exempt band used by the at least one small cell base station as a secondary frequency to be additionally used by the user terminal in the mobile communication service;
≪ / RTI > The method according to claim 1,
Wherein the received signal strength is a Reference Signal Received Power (RSRP), a Reference Signal Received Quality (RSRQ), or a Signal-to-Interference Ratio (SINR). The method according to claim 1,
Wherein the load is a usage amount of radio resources. The method according to claim 1,
Wherein the managing comprises:
Selecting a first candidate group of the at least one small cell base station in which the received signal strength is greater than a first threshold at the user terminal; And
Selecting a final candidate group in which the load is smaller than a second threshold among the at least one small cell base station in the first candidate group
≪ / RTI > The method according to claim 1,
Wherein the determining comprises:
Determining one or more of the secondary frequencies according to a predetermined number of CA frequencies;
≪ / RTI > The method according to claim 1,
Wherein the determining comprises:
Determining one of the frequencies used by the plurality of small cell base stations whose difference in the received signal strength is smaller than the threshold as the secondary frequency when the predetermined number of CA possible frequencies is 2
≪ / RTI > The method according to claim 6,
Wherein the one of the frequencies is a frequency of the license band. The method according to claim 1,
Wherein the determining comprises:
Determining one of the frequencies used by the plurality of small cell base stations whose difference in received signal strength is smaller than a threshold as one of the secondary frequencies when the predetermined number of CA possible frequencies is 3 or more; And
Determining a rest of the secondary frequency according to a magnitude of the received signal strength among frequencies other than the determined frequency among frequencies used by the plurality of small cell base stations
≪ / RTI > 9. The method of claim 8,
Wherein the one of the frequencies is a frequency of the license band. A CA (Carrier Aggregation) management apparatus for supporting heterogeneous network systems,
The method of claim 1, wherein, while the user terminal is receiving the mobile communication service through the macro cell base station at the primary frequency, the receiving signal strength between the at least one small cell base station and the at least one small cell base station A measurement management unit periodically measuring and managing the database; And
A frequency determining unit that determines a frequency of a license band or a license-exempt band used by the at least one small cell base station as a secondary frequency to be additionally used by the user terminal in the mobile communication service,
The CA management apparatus comprising: 11. The method of claim 10,
Wherein the received signal strength is a Reference Signal Received Power (RSRP), a Reference Signal Received Quality (RSRQ), or a Signal-to-Interference Ratio (SINR). 11. The method of claim 10,
Wherein the load is a usage amount of radio resources. 11. The method of claim 10,
The measurement management unit,
The mobile terminal selects a first candidate group of the at least one small cell base station in which the received signal strength is greater than a first threshold, and selects, from among the at least one small cell base stations in the first candidate group, The CA management apparatus comprising: 11. The method of claim 10,
Wherein the frequency determining unit comprises:
And determines one or a plurality of said secondary frequencies according to a predetermined number of CA possible frequencies. 11. The method of claim 10,
Wherein the frequency determining unit comprises:
Wherein the secondary frequency determining unit determines one of the frequencies used by the plurality of small cell base stations whose difference in the received signal strength is smaller than the threshold value as the secondary frequency when the predetermined number of CA possible frequencies is 2, . 16. The method of claim 15,
Wherein the one of the frequencies is a frequency of the license band. 11. The method of claim 10,
Wherein the frequency determining unit comprises:
Wherein the frequency determining unit determines one of the frequencies used by the plurality of small cell base stations having the difference of the received signal strengths smaller than the threshold as one of the secondary frequencies when the predetermined number of CA possible frequencies is 3 or more, Wherein the remaining frequency of the secondary frequency is determined according to a magnitude of the received signal strength among frequencies other than the determined frequency among the frequencies used by the base station. 18. The method of claim 17,
Wherein the one of the frequencies is a frequency of the license band.

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