Distributed antenna system and operating method thereof

Abstract

A distributed antenna system according to an aspect of the technical idea of the present disclosure comprises: a main unit; at least one hub unit selectively connected to the main unit; and a plurality of remote units each connected to the main unit or the at least one hub unit, wherein the distributed antenna system does not include a point of interest (POI) so that the main unit is directly connected to a distributed unit (DU) of a base station system through a cable.

Description

Distributed antenna system and its operating method

[0001] The technical idea of ​​the present disclosure relates to a distributed antenna system and a method of operating the same.

[0002]

[0003] A distributed antenna system is an antenna system that is used to solve the problem of high traffic capacity in indoor environments or a fixed area by spatially distributing multiple antennas.

[0004] Distributed antenna systems are connected to base transceiver stations (BSs) and are installed inside buildings, tunnels, subways, etc. to provide communication services even in shadow areas where base station signals have difficulty reaching. They are also used to provide smooth service in stadiums, large facilities, and places with high service demand.

[0005] Meanwhile, the Open Radio Access Network (O-RAN), an open network standard currently under discussion, is discussing the standardization of interfaces connecting the centralized unit (CU), distributed unit (DU), and remote unit (RU) of a base station, as well as the structure of the base station and the connection type of each unit. In this case, the structure and operation of the distributed antenna system also need to be appropriately changed to correspond to the structure and type of the base station.

[0006]

[0007] The problem to be solved by the present invention is to propose a variety of changeable structures for a base station and thereby provide a distributed antenna system capable of reducing power consumption.

[0008] The problem to be solved by the present invention is to provide a delay setting method for synchronizing a distributed antenna system through linkage with a base station.

[0009] The problem that the present invention seeks to solve is to provide a method for resolving signal quality deterioration that occurs in the process of merging and processing signals from various operators.

[0010] The problem to be solved by the present invention is to provide a distributed antenna system that enables communication services through additional installation of heterogeneous communication nodes such as mmWave.

[0011]

[0012] In order to achieve the above object, a distributed antenna system (DAS) according to an aspect of the technical idea of ​​the present disclosure includes a main unit, at least one hub unit selectively connected to the main unit, and a plurality of remote units each connected to the main unit or the at least one hub unit, wherein the DAS does not include a point of interest (POI) so that the main unit is directly connected to a distributed unit (DU) of a base station system via a cable.

[0013] A method of operating a DAS according to one aspect of the technical idea of ​​the present disclosure includes: a step of measuring a delay between each of remote units included in the DAS and the main unit; a step of transmitting a DAS delay corresponding to a maximum value among the measured delays to the DU; a step of receiving a determination result on whether to apply the DAS delay from the DU; and a step of setting a delay time of each of the remote units based on the received determination result.

[0014] According to one embodiment, the step of receiving the judgment result may include the step of receiving a first judgment result corresponding to applying the DAS delay when the DAS delay is less than a preset threshold; and the step of receiving a second judgment result corresponding to not applying the DAS delay when the DAS delay exceeds the threshold.

[0015] According to one embodiment, the step of setting the delay time may include the step of setting the delay time of each of the remote units so that the delay of each of the remote units corresponds to the DAS delay, based on receiving the first judgment result.

[0016] According to one embodiment, the step of setting the delay time may include the step of analyzing whether each of the remote units interferes with an adjacent cell based on receiving the second judgment result; and the step of setting the delay time of each of the remote units based on the analysis result.

[0017] According to one embodiment, the step of analyzing whether there is interference with the adjacent cell may include the step of analyzing whether there is interference with the adjacent cell based on at least one of location information of each of the remote units and an uplink signal of each of the remote units.

[0018] According to one embodiment, the step of setting a delay time for each of the remote units based on the analysis results may include a step of setting a delay time for a remote unit in which there is no interference with the adjacent cell such that the delay corresponds to the DAS delay.

[0019] According to one embodiment, the method may further include, when a remote unit is added to the distributed antenna system, a step of measuring a delay between the added remote unit and the main unit; and, when the measured delay is smaller than the DAS delay, a step of setting a delay time of the added remote unit so that the delay of the added remote unit corresponds to the DAS delay.

[0020] According to one embodiment, the method may further include the steps of: changing the DAS delay to the measured delay and transmitting the changed DAS delay to the DU when the measured delay is greater than the DAS delay; receiving a determination result from the DU as to whether to apply the changed DAS delay; and setting a delay time of each of the remote units based on the received determination result.

[0021]

[0022] According to one embodiment of the present disclosure, a structure is implemented in which some units constituting a base station are shared by operators, thereby improving the efficiency and cost-effectiveness of the base station configuration. In addition, the efficiency and cost-effectiveness of a distributed antenna system can also be improved by reducing or eliminating the number of base station interface units depending on the configuration of the base station. In addition, since the signal amplification process of the base station and the signal attenuation process of the distributed antenna system can be omitted, the power consumed during the signal amplification and attenuation processes can be reduced.

[0023] According to one embodiment of the present disclosure, a distributed antenna system provides information about the delay of the distributed antenna system to a base station, thereby allowing the base station to perform settings such as timing advance that take the delay of the distributed antenna system into account. Accordingly, it is possible to effectively prevent degradation of communication quality and speed due to delay of the distributed antenna system, such as poor synchronization, interference between downlink and uplink, or insufficient time for switching between downlink and uplink.

[0024] According to one embodiment of the present disclosure, a distributed antenna system can improve signal quality by adjusting the time offset or phase offset of some of the subcarriers, thereby avoiding overlapping of peak levels and suppressing an increase in PAPR.

[0025] According to one embodiment of the present disclosure, a distributed antenna system supports heterogeneous communication services based on the connection of base stations and remote units providing the heterogeneous communication services, thereby enabling efficient service establishment without the installation of separate lines or devices. Furthermore, the distributed antenna system automatically recognizes the connection of base stations and remote units providing the heterogeneous communication services, allocates dedicated channels, and provides services by utilizing the spare resources of the distributed antenna system, thereby improving ease of installation and enabling stable and economical services.

[0026] The effects according to the technical idea of ​​the present disclosure are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0027]

[0028] To more fully understand the drawings cited in this disclosure, a brief description of each drawing is provided.

[0029] FIGS. 1 to 4 are drawings showing a communication system including a connection structure of a base station and a distributed antenna system implemented corresponding thereto according to various embodiments of the present disclosure.

[0030] FIGS. 5 and 6 are flowcharts for explaining a delay setting and management method of a communication system according to an embodiment of the present disclosure.

[0031] FIG. 7 is a flowchart illustrating an operation method for improving PAPR of a distributed antenna system according to an embodiment of the present disclosure.

[0032] Figure 8 is an example diagram related to the operating method of Figure 7.

[0033] FIG. 9 is a diagram for explaining the operation of a distributed antenna system according to an embodiment of the present disclosure providing a service to heterogeneous communication nodes.

[0034]

[0035] The exemplary embodiments according to the technical idea of ​​the present disclosure are provided to more completely explain the technical idea of ​​the present disclosure to those of ordinary skill in the art. The embodiments below may be modified in various different forms, and the scope of the technical idea of ​​the present disclosure is not limited to the embodiments below. Rather, these embodiments are provided to more faithfully and completely convey the technical idea of ​​the present disclosure to those skilled in the art.

[0036] Although terms such as first, second, etc. are used in this disclosure to describe various members, regions, layers, portions, and / or components, it is to be understood that these members, parts, regions, layers, portions, and / or components should not be limited by these terms. These terms do not imply a specific order, hierarchy, or order, and are only used to distinguish one member, region, portion, or component from another member, region, portion, or component. Accordingly, a first member, region, portion, or component described below may refer to a second member, region, portion, or component without departing from the teachings of the technical spirit of this disclosure. For example, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component, without departing from the scope of the present disclosure.

[0037] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by those of ordinary skill in the art to which the concepts of this disclosure pertain. Furthermore, commonly used terms, as defined in dictionaries, should be interpreted to have a meaning consistent with their meaning within the context of the relevant technology, and should not be interpreted in an overly formal sense unless explicitly defined herein.

[0038] In some embodiments, where the implementation is otherwise feasible, a particular process sequence may be performed in a different order than described. For example, two processes described in succession may be performed substantially simultaneously, or in a reverse order from the described order.

[0039] In the attached drawings, variations in the shapes depicted may be expected, for example, depending on manufacturing techniques and / or tolerances. Therefore, embodiments according to the technical concepts of the present disclosure should not be construed as being limited to the specific shapes of the regions depicted in the present disclosure, and should include, for example, changes in shapes resulting from the manufacturing process. Identical components in the drawings are designated by the same reference numerals, and redundant descriptions thereof are omitted.

[0040] The term 'and / or' as used herein includes each and every combination of one or more of the mentioned absences.

[0041] Hereinafter, embodiments according to the technical idea of ​​the present disclosure will be described in detail with reference to the attached drawings.

[0042] FIGS. 1 to 4 are drawings showing a communication system including a connection structure of a base station and a distributed antenna system implemented corresponding thereto according to various embodiments of the present disclosure.

[0043] Referring to FIGS. 1 to 4, a communication system according to an embodiment of the present disclosure may include a base station system implemented for each frequency channel, and a distributed antenna system connected to the base station system.

[0044] Although not illustrated, conventional base stations have been implemented in a form in which a centralized unit (CU), a distributed unit (DU), and a remote unit (RU) are installed together at a cell site, and operators have individually configured and operated base stations. According to this base station form, a distributed antenna system is configured to include multiple points of interest (POIs) and multiple RF signal processing units (RFUs) corresponding to multiple base stations for each channel. The POI performs signal processing operations such as attenuating high-power base station signals transmitted from the base station. However, the base station signal attenuated by the POI is a signal that has been amplified from the base station for transmission to the distributed antenna system, and thus, it ends up consuming a certain amount of power to attenuate the amplified signal again, resulting in unnecessary power consumption.

[0045] Meanwhile, recently, in order to overcome the problems caused by the integrated implementation of the base station, a C-RAN (cloud radio access network) structure that physically separates the DU and RU has been implemented, and in the open network standard O-RAN (open radio access network), the specifications for the interface between separated base station units are being discussed.

[0046] Based on this, referring to FIGS. 1 to 4, the present disclosure proposes base station system structures in which some units are integrated and shared between operators based on the fact that communication nodes (CU, DU, and RU) constituting the base station can be physically separated from each other, and structures of a distributed antenna system based on this.

[0047] Referring to the embodiment of FIG. 1, the base station system (1_1 to 1_m) may be configured to include CUs (111_1 to 111_n) and DUs (113_1 to 113_n) implemented for each of a plurality of operators (11_1 to 11_n, n is a natural number), and RUs (115) connected to the DUs (113_1 to 113_n) of each of the operators, so that one RU (115) is shared by a plurality of operators (11_1 to 11_n).

[0048] Each communication node (CU, DU, and RU) may be implemented as at least one device, and each device may include hardware and software for transmitting and receiving communication signals (frames). The hardware may include components such as a processor, memory, communication chips, or circuits.

[0049] According to an embodiment, CUs (111_1 to 111_n) and DUs (113_1 to 113_n) can process RRC, PDCP, High-RLC, Low-RLC, High-MAC, Low-MAC, and High-PHY layers separately. CU (111_1) can be directly connected to the core network and interface between the core network and the base station system.

[0050] The RU (115) is connected to the DU (113_1 to 113_n) of each of the operators (11_1 to 11_n) and can transmit and receive communication signals for each of the operators with the distributed antenna system (7) (or user terminal). To this end, the RU (115) can support the frequency bands of each of the operators (11_1 to 11_n).

[0051] In the uplink path, the RU (115) can divide the communication signal provided from the distributed antenna system (7) according to the frequency bands of the operators (11_1 to 11_n) and transmit the divided signals to the DU of the corresponding operator.

[0052] A plurality of DUs (113_1 to 113_n) and RUs (115) can be connected through various communication media such as optical cables, high-speed cables, or microwave cables.

[0053] According to an embodiment, the plurality of DUs (113_1 to 113_n) and the RU (115) may comply with various fronthaul communication standards. For example, the plurality of DUs (113_1 to 113_n) and the RU (115) may transmit and receive communication frames via the Common Public Radio Interface (CPRI) or the Ethernet-based Common Public Radio Interface (eCPRI).

[0054] The distributed antenna system (7) may include a plurality of base station interface units (71_1 to 71_m) connected to each of frequency channels (71_1 to 71_m), a main unit (main unit (MU) or headend unit; 73) connected to the plurality of base station interface units (71_1 to 71_m), at least one hub unit (hub unit (HU) or expansion unit; 75_1 to 75_p; p is a natural number) connected to the main unit (73), and a plurality of remote units (77_1 to 77_q; q is a natural number of 2 or more) connected to the main unit (73) or the hub unit (75_1 to 75_p).

[0055] Each of the plurality of base station interface units (71_1 to 71_m) may include a POI (711_1) and an RFU (713_1), and may interface between the base station system (1_1 to 1_m) and the main unit (73). In the downlink path, the POI (711_1) may adjust (attenuate) the power level of a high-power base station signal, and the RFU (713_1) may transmit the base station signal with the adjusted power level to the main unit (73). In the uplink path, the RFU (713_1) may receive a user terminal signal from the main unit (73), and the POI (711_1) may adjust (amplify) the power level of the user terminal signal and transmit it to the base station system (1_1). Meanwhile, the base station signal and the user terminal signal may be digitized RF signals, but are not limited thereto.

[0056] Compared to a conventional base station interface unit including multiple POIs and RFUs, each of which is connected to a RU of each operator, according to an embodiment of the present disclosure, since the RU (115) is shared by multiple operators (11_1 to 11_n), each of the base station interface units (71_1 to 71_m) can be implemented including only one POI (711_1) and RFU (713_1), thereby enabling implementation of a simplified base station interface unit.

[0057] These base station interface units (71_1 to 71_m) can be connected to the RU (115) via a coaxial cable, but are not limited thereto.

[0058] In the downlink path, the main unit (73) can receive base station signals with adjusted power levels from the base station interface units (71_1 to 71_m). For example, the main unit (73) can be connected to the base station interface units (71_1 to 71_m) via an optical cable, but is not limited thereto, and can be connected via various communication media such as a high-speed cable or a microwave cable.

[0059] The main unit (73) can generate downlink transmission frames through predetermined processing (digital conversion, resampling, framing, etc.) on received base station signals. The main unit (73) can distribute the generated downlink transmission frames to hub units (75_1 to 75_p). Although not shown, remote units can be connected to the main unit (73), and in this case, the main unit (73) can distribute the downlink transmission frames to the connected remote units.

[0060] In the uplink path, the main unit (73) can deframe uplink transmission frames transmitted from the hub units (75_1 to 75_p) and / or remote units, process data streams generated as a result of the deframing according to a corresponding base station system and operator among a plurality of base station systems (1_1 to 1_m) and a plurality of operators (11_1 to 11_n), and then transmit the data streams to the base station via the base station interface unit (71_1 to 71_m).

[0061] Meanwhile, the main unit (73) can distribute or redistribute capacity for communication services. Here, capacity may refer to capacity by service. Furthermore, the main unit (73) can distribute or redistribute capacity by service. Here, services may refer to carriers, frequency bands, sectors, and service providers.

[0062] The hub units (75_1 to 75_p) can expand the connection capacity of the main unit (73). For example, the hub units (75_1 to 75_p) can be connected between the main unit (73) and remote units (77_1 to 77_q) to expand the connection capacity of the main unit (73). The hub units (75_1 to 75_p) can transmit and receive downlink transmission frames and uplink transmission frames between the main unit (73) and the connected remote units among the remote units (77_1 to 77_q). These hub units (75_1 to 75_p) can be connected between the main unit (73) and the remote units via an optical cable or the like.

[0063] According to an embodiment, the hub units (75_1 to 75_p) can convert the format of a signal transmitted during a signal transmission process. For example, the hub units (75_1 to 75_p) can convert a digital signal transmitted from the main unit (73) into an Ethernet format and transmit data converted into the Ethernet format to connected remote units. In addition, the hub units (75_1 to 75_p) can convert a signal in an Ethernet format transmitted from connected remote units into a digital signal and transmit the digital signal to the main unit (73).

[0064] Depending on the embodiment, the main unit (73) or hub unit (75_1 to 75_p) may also supply power to the connected remote units (77_1 to 77_q) via PoE (Power of Ethernet), etc.

[0065] The remote units (77_1 to 77_q) can be communicatively connected to the main unit (73) via a connected hub unit. Depending on the embodiment, the remote units (77_1 to 77_q) can also be communicatively connected directly to the main unit (73).

[0066] The remote units (77_1 to 77_q) can generate data streams by deframing downlink transmission frames transmitted from a connected hub unit, and can restore the generated data streams to original signals (e.g., RF signals, digitized RF signals). The remote units (77_1 to 77_q) can output the restored signals in a required form to user terminals, etc. located within the coverage area.

[0067] In addition, the remote units (77_1 to 77_q) can generate uplink transmission frames through predetermined processing for various wireless signals received from user terminals, etc. located within the service coverage, and transmit the generated uplink transmission frames to a connected expansion unit (or main unit).

[0068] Referring to FIG. 2, the distributed antenna system is substantially the same as the distributed antenna system (7) of FIG. 1, and thus, the description and illustration thereof are omitted.

[0069] In the embodiment of FIG. 2, the base station system (2_1) can be configured in a form in which DU (213) and RU (215) are shared by multiple operators (21_1 to 21_n).

[0070] DU (213) is connected to each CU (211_1 to 211_n) of the operators (21_1 to 21_n) and can transmit and receive communication signals for each operator with RU (215). In this case, DU (213) can support the frequency band of each operator (21_1 to 21_n).

[0071] In the uplink path, the DU (213) can divide the communication signal provided from the RU (215) according to the frequency band of the operators (21_1 to 21_n) and transmit the divided signals to the CU (211_1 to 211_n) of the corresponding operator.

[0072] The plurality of CUs (211_1 to 211_n) and the DU (213) can be connected via various communication media such as optical cables, high-speed cables, or microwave cables. The plurality of CUs (211_1 to 211_n) and the DU (213) can comply with various midhaul communication standards. For example, the plurality of CUs (211_1 to 211_n) and the DU (213) can transmit and receive communication frames via CPRI or eCPRI.

[0073] RU (215) is connected to DU (213) and can transmit and receive communication signals of operators (21_1 to 21_n) with the distributed antenna system (7) (or user terminal). To this end, similar to the embodiment of FIG. 1, RU (215) can support the frequency bands of each of the operators (21_1 to 21_n).

[0074] Referring to the embodiments of FIGS. 3 and 4, a structure in which a part of the configuration of the base station system (RU) is integrated into the distributed antenna system (8) may be considered.

[0075] In the case of FIG. 3, the base station system (3_1 to 3_m) may be configured to include CUs (311_1 to 311_n) and DUs (313_1 to 313_n) implemented for each of multiple operators (31_1 to 31_n). In this case, the DUs (313_1 to 313_n) of the operators may be connected to the main unit (83) of the distributed antenna system (8).

[0076] The distributed antenna system (8) may include a main unit (83) in which an RU is integrated, at least one hub unit (85_1 to 85_p), and a plurality of remote units (87_1 to 87_q) connected to the main unit (83) or the hub units (85_1 to 85_p). As the main unit (83) and the RU are integrated, the distributed antenna system (8) may not include the base station interface units (71_1 to 71_m) illustrated in FIG. 1. In addition, since the signal amplification process at the base station side and the signal attenuation process at the POI are eliminated, unnecessary power consumption of the communication system can be prevented.

[0077] MU (83) can be connected to multiple DUs (313_1 to 313_n) through various communication media such as optical cables, high-speed cables, or microwave cables, and can transmit and receive communication frames through fronthaul communication standards such as CPRI or eCPRI.

[0078] Referring to FIG. 4, the base station system (4_1) can be configured in a form in which the RU is integrated into the MU (83), as in the embodiment of FIG. 3, and the DU (413) is shared by multiple operators (41_1 to 41_n). The DU (413) is connected to the CU (411_1 to 411_n) of each of the operators (41_1 to 41_n), and can transmit and receive communication signals for each of the operators with the distributed antenna system (8). In this case, the DU (413) can support the frequency bands of each of the operators (41_1 to 41_n).

[0079] In the uplink path, the DU (413) can divide the communication signal provided from the MU (83) according to the frequency band of the operators (41_1 to 41_n) and transmit the divided signals to the CU (411_1 to 411_n) of the corresponding operator.

[0080] The plurality of CUs (411_1 to 411_n) and the DU (413) can be connected via various communication media such as optical cables, high-speed cables, or microwave cables. The plurality of CUs (411_1 to 411_n) and the DU (413) can comply with various midhaul communication standards. For example, the plurality of CUs (411_1 to 411_n) and the DU (413) can transmit and receive communication frames via CPRI or eCPRI.

[0081] According to the embodiments of FIGS. 1 to 4, the efficiency and economy of the base station can be improved as the base station system is implemented in a form in which operators share some components (RU and / or DU) of the base station.

[0082] Distributed antenna systems also improve efficiency and economy as the number of base station interface units is reduced or eliminated depending on the configuration of the base station system, and the reduction in volume can effectively reduce the installation area and resolve installation location restrictions.

[0083] FIGS. 5 and 6 are flowcharts for explaining a delay setting and management method of a communication system according to an embodiment of the present disclosure.

[0084] For the convenience of the following explanation, the embodiments of FIGS. 5 to 6 are described using a communication system having the structure of FIG. 4, but the structure of the communication system to which this embodiment is applied may include the structure of FIG. 3, etc., as well as FIG. 4.

[0085] Referring to FIGS. 5 and 6, the distributed antenna system (8) can measure the delay between each of the remote units (87_1 to 87_q) and the main unit (83) (S500).

[0086] The above delay can be measured by the main unit (83) of the distributed antenna system (8), but is not limited thereto. For example, the above delay is a delay of a downlink path, and the main unit (83) can measure the delay by transmitting an arbitrary signal to each of the remote units (87_1 to 87_q) and then using a reception confirmation signal (e.g., an ACK signal, etc.) received from each remote unit.

[0087] The delay between each of the remote units (87_1 to 87_q) and the main unit (83) may vary depending on the location or distance of each of the remote units (87_1 to 87_q), whether there is interference, etc.

[0088] Depending on the embodiment, the distributed antenna system (8) may also measure delay by frequency band or by carrier.

[0089] The distributed antenna system (8) can define the maximum value among the measured delays as the distributed antenna system (DAS) delay and transmit the DAS delay to the DU (413) of the base station system (S510).

[0090] Remote units (87_1 to 87_q) must be synchronized to output identical signals at the same time to minimize interference between adjacent cells, support smooth handover, and improve quality and performance. In order for all remote units (87_1 to 87_q) to output identical signals at the same time, the output of other remote units must be delayed to match the remote unit with the longest measured delay.

[0091] Accordingly, the main unit (83) can set the delay time of the remote units (87_1 to 87_q) by providing delay time setting information to each of the remote units (87_1 to 87_q) so that all remote units (87_1 to 87_q) can output signals at the same time according to the maximum value among the measured delays. The remote units (87_1 to 87_q) can align the delays by individually delaying and outputting signals based on the received information. The maximum value is defined as the distributed antenna system (DAS) delay.

[0092] Meanwhile, a communication signal generated from a base station system (3_1) and transmitted to a distributed antenna system (8) may include a guard interval in addition to a payload. The base station system (3_1) may set the length of the guard interval by considering a multipath environment, channel bandwidth, signal delay, interval between symbols, etc., and for example, the guard interval may correspond to a CP (cyclic prefix) interval. The CP may be divided into two types, short CP (normal CP) and long CP (extended CP), depending on the length, but is not limited thereto.

[0093] In the conventional case, since there is no connection for transmitting and receiving information such as delay between the base station system (3_1) and the distributed antenna system (8), the base station system (3_1) sets a guard interval without considering the delay on the distributed antenna system (8) side. In this case, since the guard interval is not sufficiently secured due to the delay on the distributed antenna system (8) side, synchronization may not be smoothly performed, interference may occur between the downlink and uplink, or sufficient time may not be secured for switching between the downlink and uplink, which may result in a deterioration in communication quality and speed.

[0094] According to an embodiment of the present disclosure, the main unit (83) is connected to the DU (413) for communication, and interworking rules, etc. can be defined according to standards such as O-RAN. Accordingly, the main unit (83) can transmit the DAS delay to the DU (413), and the DU (413) can minimize the above-described problem by appropriately setting the timing advance for user terminals based on the received DAS delay.

[0095] Continuing with reference to FIG. 5, the base station system (3_1) can determine whether to apply the received DAS delay (S520).

[0096] For example, DU (413) can determine whether to apply DAS delay based on whether the DAS delay exceeds a preset threshold. The preset threshold can be set based on the maximum delay time that the base station system (3_1) can process, the connection delay time between DU (413) and MU (83), and the connection delay time between RU (87) and user terminal that occurs according to the service range (radius) of RU (87). For example, the threshold (TH) can be set according to the following mathematical expression 1.

[0097]

[0098]

[0099]

[0100] Here, Z refers to the maximum delay time that the base station system (3_1) can handle, A refers to the connection delay time between the DU (413) and the MU (83), and S may refer to the connection delay time between the RU (87) and the user terminal according to the service range.

[0101] DU (413) may determine to apply DAS delay if the DAS delay is below a threshold, and may determine not to apply DAS delay if it exceeds the threshold. DU (413) may transmit the result of the determination on whether to apply DAS delay to MU (83).

[0102] According to an embodiment, the DU (413) may set a timing advance value for each user terminal by reflecting the received DAS delay. Specifically, the DU (413) may set the timing advance value by reflecting the DAS delay together so that the signals output from each user terminal reach each of the remote units (87_1 to 87_q) of the distributed antenna system (8) at the same time.

[0103] If it is determined that DAS delay is to be applied (YES of S520), the distributed antenna system (8) can align the delay of the remote units (87_1 to 87_q) based on the DAS delay (S530).

[0104] As described above, the main unit (83) can set the delay time of the remote units (87_1 to 87_q) by providing information about the DAS delay to the remote units (87_1 to 87_q) so that all remote units (87_1 to 87_q) can output signals at the same time according to the DAS delay. The remote units (87_1 to 87_q) can individually delay and output signals based on the received information, thereby matching the delay to the DAS delay.

[0105] In an embodiment, when the DAS delay is defined from a delay measured by frequency band or subcarrier, the main unit (83) can perform delay alignment based on the DAS delay by frequency band or subcarrier.

[0106] According to an embodiment, the main unit (83) can enable service by reducing the service range (radius) for a remote unit among the remote units whose measured delay exceeds a threshold.

[0107] According to an embodiment, when a new remote unit is added to the distributed antenna system (8), the distributed antenna system (8) can measure the delay between the main unit (83) and the added remote unit (S540).

[0108] If the measured delay is smaller than the DAS delay (YES of S550), the distributed antenna system (8) can match the delay of the added remote unit with other remote units based on the DAS delay (S530).

[0109] On the other hand, if the measured delay is greater than the DAS delay (NO of S550), the distributed antenna system (8) can change the DAS delay to the measured delay and transmit the changed DAS delay to the DU (413) (S560). The DU (413) can determine whether to apply the changed DAS delay (S520), and the distributed antenna system (8) can perform step S530 or step S570 depending on the determination result.

[0110] Meanwhile, if it is determined that DAS delay is not to be applied (NO of S520), the distributed antenna system (8) can set the delay based on the location and interference of each of the remote units (87_1 to 87_q) (S570).

[0111] Referring to FIG. 6 in connection with step S570, the distributed antenna system (8) (e.g., main unit (83)) can analyze, for each of the connected remote units (87_1 to 87_q), whether there is interference with adjacent cells (S571).

[0112] The main unit (83) can analyze whether interference with adjacent cells exists based on the location information and / or uplink signals of each of the remote units (87_1 to 87_q). Specifically, the main unit (83) can determine, based on the location information of each of the remote units (87_1 to 87_q), that interference exists for remote units whose distances between each other are less than a reference distance. In addition, the main unit (83) can receive an uplink signal of a predefined form from each of the remote units (87_1 to 87_q), and determine whether interference exists based on a difference between the form of the received uplink signal and the predefined form.

[0113] For remote units for which the analysis results determine that interference does not exist (NO in S572), the distributed antenna system (8) can align the delay by independently applying the DAS delay to each of the remote units regardless of whether the DAS delay from the DU (413) is applied (S573). According to an embodiment, when remote units are added, the distributed antenna system (8) can independently apply the DAS delay to the added remote units regardless of whether the DAS delay from the DU (413) is applied, thereby aligning the delay.

[0114] On the other hand, if the analysis result determines that interference exists (YES in S572), the distributed antenna system (8) can determine whether DAS delay can be applied (S574). For example, the MU (83) can determine whether DAS delay can be applied by analyzing whether interference occurs when DAS delay is applied to remote units (87_1 to 87_q) or by analyzing whether communication service can be provided when DAS delay is applied.

[0115] If the judgment result indicates that the application of the DAS delay is possible (YES in S575), the distributed antenna system (8) can align the delay by applying the DAS delay to each of the remote units (87_1 to 87_q) (S573). Alternatively, the distributed antenna system (8) can align the delay by applying the DAS delay to the added remote units.

[0116] On the other hand, if application of DAS delay is not possible (NO of S575), the distributed antenna system (8) can complete delay setting without delay alignment (S576).

[0117] FIG. 7 is a flowchart illustrating an operating method for improving PAPR of a distributed antenna system according to an embodiment of the present disclosure. FIG. 8 is an exemplary diagram related to the operating method of FIG. 7.

[0118] When operating a distributed antenna system, each remote unit adds, amplifies, and outputs signals from multiple subcarriers. During this process of combining signals from multiple carriers, the signal's peak-to-average power ratio (PAPR) increases compared to a typical signal. When PAPR increases, the signal's dynamic range increases, making ADC and DAC design difficult. Furthermore, this can degrade amplifier characteristics in the amplifier section, increasing spurious signals. To improve this, clipping (such as CFR processing) can be performed to lower the PAPR below the design value. However, clipping can also degrade signal quality.

[0119] The method of operating a distributed antenna system according to an embodiment of the present disclosure for resolving the above-described problem will be described below with reference to FIGS. 7 and 8.

[0120] Referring to FIGS. 7 and 8, the distributed antenna system (8) can set a threshold for the peak level of a signal for each frequency band (band) (S700).

[0121] The above threshold is a value set by an administrator, etc., and may be changed depending on the communication environment, etc. The above threshold may be set to the same or different values ​​for each frequency band.

[0122] When subcarriers are merged by frequency band in the distributed antenna system (8), the peak level of the merged subcarrier signal can be compared with the threshold.

[0123] If the above peak level exceeds the preset threshold (YES of S710), the distributed antenna system (8) can adjust the time offset and / or phase offset of some of the subcarriers of the corresponding frequency band (S720).

[0124] The peak level of the merged subcarrier signal can be significantly increased when the peak levels of each subcarrier have the same time point (or phase). That is, if the peak level exceeds the preset threshold, it may mean that there are subcarriers with similar peak level times or phases. Therefore, in order to reduce the peak level of the merged subcarrier signal, the distributed antenna system (8) can adjust the time offset and / or phase offset of some of the subcarriers of the corresponding frequency band (e.g., adjust by a preset value).

[0125] Until the adjustment limit for the time offset and / or phase offset is not exceeded (NO of S730), the distributed antenna system (8) merges the offset-adjusted subcarriers, and if the peak level of the merged subcarrier signal exceeds the threshold, it can repeatedly adjust the time offset and / or phase offset of some of the subcarriers.

[0126] The above adjustment limit may be set to a value within the TAE (Timing Alignment Error) defined in standards such as 3GPP, but is not limited thereto.

[0127] Meanwhile, if the peak level is less than the preset threshold (NO of S710), the distributed antenna system (8) can fix the time offset and phase offset of the subcarriers of the corresponding frequency band (S740).

[0128] Referring to the example diagram of FIG. 8, if the peak levels of the first subcarrier and another subcarrier (e.g., the second subcarrier) are located at the same time, when the first subcarrier and the second subcarrier are merged, the peak level may increase and exceed the threshold. Accordingly, the distributed antenna system (8) (main unit (83)) may shift the second subcarrier by the time offset along the time axis by adjusting the time offset of some of the subcarriers (the second subcarriers). Accordingly, since the peak levels of the first subcarrier and the second subcarrier are not located at the same time, the peak level of the signal in which the first subcarrier and the second subcarrier are merged is lowered, so that the PAPR can be improved.

[0129] FIG. 9 is a diagram for explaining the operation of a distributed antenna system according to an embodiment of the present disclosure providing a service to heterogeneous communication nodes.

[0130] While a distributed antenna system is installed and operated in a building or other location, if the number of users increases or shadow areas are discovered, and service becomes unstable, new remote units can be added to address this issue. Typically, the remote units added to a distributed antenna system can provide communication services with the base station to which the distributed antenna system is currently connected.

[0131] However, if a building with a distributed antenna system needs to provide communication services utilizing different types or frequency bands, it may be more efficient to support these services through the existing distributed antenna system rather than installing separate lines or relay devices. Therefore, an implementation method that allows distributed antenna systems to provide both existing and heterogeneous communication services may be necessary.

[0132] Based on this, referring to FIG. 9, the distributed antenna system may include a base station interface unit (91_1), a main unit (93), hub units (95_1 to 95_p), and remote units (97_1 to 97_q) connected to a base station system (5_1). In FIG. 9, for convenience of explanation, a conventional base station interface unit having a POI (911_1 to 911_m) and an RFU (913_1 to 913_m) for each operator is illustrated, but the base station system (5_1) and the distributed antenna system may also be implemented in a form similar to the embodiments of FIGS. 1 to 4.

[0133] When providing mmWave service to a building (or area, etc.) where a distributed antenna system is installed, a base station (6, e.g., CU or DU) providing mmWave service may be connected to a main unit (93). In addition, remote units (99_1, 99_2) supporting mmWave service may be connected to a hub unit (95_p) and a remote unit (97_q). Although not shown, a remote unit supporting mmWave service may also be connected to the main unit (93). In Fig. 9, mmWave is shown as an example of heterogeneous communication, but the type of heterogeneous communication may be changed in various ways.

[0134] When the main unit (93) recognizes that a base station (6) is connected through a specific port, it analyzes the channel information of the recognized port and, based on the analysis result, can determine whether the base station (6) provides the same communication service as the existing connected base stations or provides a different communication service.

[0135] If the verification result is a base station (6) providing a heterogeneous communication service (mmWave service), the main unit (93) can check whether a remote unit (99_1, 99_2) supporting the heterogeneous communication service is connected to the distributed antenna system. For example, the main unit (93) can check whether a remote unit (99_1, 99_2) supporting the heterogeneous communication service is connected based on the communication protocol of each of the currently connected remote units, but the method for checking whether or not it is connected can be implemented in various forms.

[0136] The main unit (93) can allocate a dedicated channel between the base station (6) supporting the heterogeneous communication service and the remote units (99_1, 99_2). In this case, the communication signal transmitted from the base station (6) can be transmitted to the remote units (99_1, 99_2) via the hub unit (95_1, 95_p) and / or the remote unit (97_q) connected between the main unit (93) and the remote units (99_1, 99_2). In addition, the main unit (93) can support the heterogeneous communication service by transmitting the communication signal transmitted from the remote units (99_1, 99_2) to the base station (6).

[0137] According to the embodiment of FIG. 9, the distributed antenna system supports heterogeneous communication services based on the connection of base stations and remote units providing the heterogeneous communication services, thereby enabling efficient service establishment without the installation of separate lines or devices. Furthermore, the distributed antenna system automatically recognizes the connection of base stations and remote units providing the heterogeneous communication services, allocates dedicated channels, and provides services by utilizing the spare resources of the distributed antenna system, thereby improving ease of installation and enabling stable and economical services.

[0138] The description of the above embodiments is merely an example with reference to the drawings for a more thorough understanding of the present disclosure, and should not be construed as limiting the technical idea of ​​the present disclosure.

[0139] In addition, it will be apparent to a person skilled in the art to which the present disclosure pertains that various changes and modifications are possible within a scope that does not depart from the basic principles of the present disclosure.

Claims

1. In the method of operating a distributed antenna system (DAS) in which a main unit is connected to a distributed unit (DU) of a base station system via a cable, A step of measuring the delay between each of the remote units included in the DAS and the main unit; A step of transmitting the DAS delay corresponding to the maximum value among the measured delays to the DU; A step of receiving a judgment result on whether to apply the DAS delay from the DU; and A step of setting a delay time for each of the remote units based on the received judgment result, method.

2. In paragraph 1, The step of receiving the above judgment result is: A step of receiving a first judgment result corresponding to applying the DAS delay when the DAS delay is less than a preset threshold; and Including a step of receiving a second judgment result corresponding to not applying the DAS delay when the DAS delay exceeds the threshold. method.

3. In paragraph 2, The step of setting the above delay time is: Based on receiving the first judgment result, a step of setting a delay time of each of the remote units so that the delay of each of the remote units corresponds to the DAS delay is included. method.

4. In paragraph 2, The step of setting the above delay time is: A step of analyzing whether there is interference with an adjacent cell for each of the remote units based on receiving the second judgment result; and A step of setting a delay time for each of the remote units based on the analysis results, method.

5. In paragraph 4, The step of analyzing whether there is interference with the adjacent cells is as follows: Comprising a step of analyzing whether there is interference with the adjacent cell based on location information of each of the remote units and at least one of the uplink signals of each of the remote units, method.

6. In paragraph 4, The step of setting the delay time of each of the remote units based on the above analysis results is: For a remote unit in which there is no interference with the adjacent cell, a step of setting a delay time such that the delay corresponds to the DAS delay is included. method.

7. In paragraph 1, When a remote unit is added to the distributed antenna system, a step of measuring the delay between the added remote unit and the main unit; and If the measured delay is smaller than the DAS delay, further comprising a step of setting the delay time of the expanded remote unit so that the delay of the expanded remote unit corresponds to the DAS delay. method.

8. In paragraph 7, A step of changing the DAS delay to the measured delay and transmitting the changed DAS delay to the DU when the measured delay is greater than the DAS delay; A step of receiving a judgment result on whether to apply the changed DAS delay from the DU; and Further comprising a step of setting a delay time for each of the remote units based on the received judgment result. method.

9. Main unit; At least one hub unit optionally connected to the main unit; and Each of the plurality of remote units is connected to the main unit or at least one hub unit, By not including a POI (point of interest), the main unit is directly connected to the distributed unit (DU) of the base station system via a cable. Distributed antenna system.

10. In paragraph 9, The above main unit is, Measure the delay between each of the plurality of remote units and the main unit, The DAS delay corresponding to the maximum value among the measured delays is transmitted to the DU, Receive the result of the judgment on whether to apply the DAS delay from the above DU, Setting the delay time of each of the plurality of remote units based on the received judgment result, Distributed antenna system.

11. In paragraph 10, The above judgment result is, One of a first judgment result corresponding to applying the DAS delay when the DAS delay is less than a preset threshold, and a second judgment result corresponding to not applying the DAS delay when the DAS delay exceeds the threshold. Distributed antenna system.

12. In paragraph 11, The above main unit is, In response to receiving the first judgment result, delay time setting information for setting the delay of each of the plurality of remote units to correspond to the DAS delay is transmitted to each of the plurality of remote units. Distributed antenna system.

13. In paragraph 11, The above main unit is, In response to receiving the second judgment result, analyze whether there is interference with an adjacent cell for each of the plurality of remote units, Setting the delay time of each of the plurality of remote units based on the analysis results, Distributed antenna system.

14. In paragraph 13, The above main unit is, Analyzing whether there is interference with an adjacent cell based on location information of each of the plurality of remote units and at least one of the uplink signals of each of the plurality of remote units, Distributed antenna system.

15. In paragraph 13, The above main unit is, For a remote unit where there is no interference with an adjacent cell, delay time setting information is transmitted to set the delay to correspond to the DAS delay. Distributed antenna system.

16. In paragraph 10, When a remote unit is added to the above distributed antenna system, the main unit, Measure the delay between the above-mentioned expanded remote unit and the above-mentioned main unit, If the measured delay is smaller than the DAS delay, delay time setting information for setting the delay of the expanded remote unit to correspond to the DAS delay is transmitted to the expanded remote unit. Distributed antenna system.

17. In paragraph 16, The above main unit is, If the measured delay is greater than the DAS delay, the DAS delay is changed to the measured delay, and the changed DAS delay is transmitted to the DU. Receive the result of the judgment on whether to apply the changed DAS delay from the above DU, Setting the delay time of each of the plurality of remote units based on the received judgment result, Distributed antenna system.

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