Patent Description:
A distributed antenna system is a system composed of common nodes (e.g., headend units) and antenna nodes (e.g., remote units) that are connected to the common nodes through a transmission medium or a transmission network and are spatially separated.

Radio signals are transmitted between the common nodes and the antenna nodes of the distributed antenna system. Through this, at least one service provider device connected in a communicative manner with the headend units of the distributed antenna system may provide cellular service, Internet service, etc. to subscriber devices in a service area of the distributed antenna system.

The distributed antenna system is generally implemented in neutral host architecture for integrating and providing various wireless services. As a result, the distributed antenna system operates by statically allocating transmission resources (e.g., a transmission medium bandwidth) required for radio signal transmission between nodes of the distributed antenna system on the premise that all wireless services are supported, hardware resources, and the like.

However, in the actual operating environment of the distributed antenna system, many wireless services are not provided in many cases, so that static resource allocation and operation methods of the distributed antenna system are inefficient.

<CIT> discloses an interface having a transmission protocol providing a reference data region for transmission of digital baseband signals in a transmission frame format per transmission frame, and a transmission channel classification unit dividing the reference data region into partial transmission channels corresponding to data rates required for the transmission of the digital signals, and assigning the date rates to the digital signals.

<CIT> discloses a distributed antenna system (DAS) having a common communication infrastructure distributing data from radio-based and Internet-based sources. In the document it is described that a radio equipment (RE) of the DAS interfaces to a LAN segment, for the downlink, a gateway maps radio signal data from a radio equipment controller (REC) and data packets from a switch to mixed-data frames using a radio data interface protocol for transmission in the DAS, at the RE, the signal data and data packets are retrieved from the mixed-data frames and provided to the air interface and LAN segment, respectively, for the uplink from the RE, the radio signal data from the air interface and the data packets from the LAN segment are mapped to mixed-data frames and transmitted to the gateway, and the gateway retrieves the signal samples and data packets from the mixed-data frames for transfer to the REC and switch, respectively.

<CIT> discloses a distributed antenna system ("DAS") to interface with and manage components of facility control and monitoring systems while providing wireless communications in a cellular or public safety network. In the document it is described that a communications module is configured for receiving facility control signals from facility control and monitoring centers and associated nodes and sensors, a signal processing module is configured to convert the facility control signals a format transportable in the DAS, wherein the signal processing module is also configured to multiplex the facility control signals with mobile voice and data signals being transported in the DAS.

<CIT> discloses systems and methods for improved digital RF transport in a DAS. In the document a transceiver is described to comprise a receive path circuit including an RF reception interface coupled to an ADC, the ADC receiving a downconverted analog RF spectrum from the RF reception interface and producing a digitized RF spectrum at an input sampling rate, a logic device receiving the digitized RF spectrum and producing a first set of baseband data samples at a first sampling rate, corresponding to a first spectral region of the analog RF spectrum and a second set of baseband data samples at a second sampling rate, corresponding to a second spectral region of the analog RF spectrum, wherein the logic device maps the first set and second sets of baseband data samples to a respective first set and second set of timeslots of a serial data stream transport frame.

Provided are a distributed antenna system using a reconfigurable frame structure to efficiently use limited resources and a method of operating the distributed antenna system.

The inventive concept of the present disclosure is not limited to the above objective(s), but other objective(s) not described herein may be clearly understood by one of ordinary skilled in the art from descriptions below.

According to embodiments of the present disclosure, a frame structure for data transmission between nodes may be reconfigured in consideration of needs of a service provider, needs of a user, and the operating environment of a distributed antenna system.

Accordingly, the present disclosure has the effect of efficiently using transmission resources and the like of the distributed antenna system.

In addition, the present disclosure has the effect of improving the quality of service while reducing power consumption.

In addition, the present disclosure may facilitate integrated support of Ethernet backhaul services such as small cells and Wi-Fi.

Effects obtainable by the distributed antenna system and a method of operating the same according to the inventive concept of the present disclosure are not limited to the effect(s) described above, but other effect(s) not described herein may be clearly understood by one of ordinary skill in the art from the above descriptions.

Various embodiments and features according to the inventive concept of the present disclosure will be further described later below. It should be apparent that the teachings herein may be implemented in a wide variety of forms and any particular structure, function, or both, disclosed herein are merely exemplary, and not limiting. Based on the teachings herein, those of ordinary skill in the art will appreciate that aspects disclosed herein may be implemented independently of any other aspects, and two or more of these aspects may be combined in various ways. For example, a device or a method may be implemented by using any number of aspects set forth herein. Furthermore, the device or the method may be implemented with structures and functions of one or more of the aspects described herein, or may be implemented by using structures and functions of other aspects. For example, the method may be implemented as a part of instructions stored on a non-transitory computer-readable recording medium for execution on a system, a device, an apparatus and/or a processor, or a computer. Furthermore, one aspect may include at least one component of the claim.

Hereinafter, various embodiments of the present disclosure will be described in detail in order.

<FIG> is a conceptual block diagram of a distributed antenna system according to an embodiment.

Referring to <FIG>, a distributed antenna system (DAS) <NUM> may include a headend unit <NUM>, an expansion unit <NUM>, a plurality of remote units <NUM>-<NUM> to <NUM>-<NUM>, a system controller <NUM>, and a frame layout information generator <NUM>.

The headend unit <NUM> may be communicatively coupled to a plurality of sources Sa to Sd in a wired or wireless manner. The headend unit <NUM> may receive various radio signals from the plurality of sources Sa to Sd.

For example, one or more of the plurality of sources Sa to Sd may be a base station device providing a radio frequency (RF) signal.

For another example, any one of the sources Sa to Sd may be a base station device for providing a digitized RF signal. The digitized RF signal may include a data packet formatted according to a standardized telecommunication protocol. Non-limiting examples of the standardized telecommunication protocol may include a common public radio interface (CPRI), an Ethernet-based common public radio interface (eCRPI), an open radio equipment interface (ORI), or an open base station architecture initiative (OBSAI) protocol.

For another example, any one of the plurality of sources Sa to Sd may be an IP backhaul device for a small cell and a Wi-Fi backhaul service. The IP backhaul device may be an Internet gateway, a VPN gateway, or the like.

Hereinafter, for convenience of description, it is assumed that the sources Sa and Sb are base station devices for providing an RF signal, the source Sc is a base station device for providing a digitized RF signal, and the source Sd is an IP backhaul device.

Meanwhile, although not shown in <FIG>, a point of interface (POI) may be disposed between the sources Sa and Sb for providing the RF signal and the headend unit <NUM>. The POI may be a device for matching between the sources Sa and Sb and the headend unit <NUM>. The POI may adjust a high power level RF signal received from the sources Sa and Sb to a level suitable for the headend unit <NUM>, and may adjust an RF signal received from the headend unit <NUM> to a level suitable for the sources Sa and Sb.

The headend unit <NUM> may perform a predetermined processing on various radio signals received. For example, the headend unit <NUM> may digitally convert an RF signal, and perform resampling or the like on the digitized RF signal. The headend unit <NUM> may generate downlink transmission frames by framing data streams and Ethernet data generated as a result of the processing. Signal processing in a downlink path of the headend unit <NUM> will be described in more detail with reference to <FIG> below.

The headend unit <NUM> may distribute the downlink transmission frames to the expansion unit <NUM> and the remote units <NUM>-<NUM> to <NUM>-<NUM>. In more detail, the headend unit <NUM> may transmit the downlink transmission frames to the remote units <NUM>-<NUM> to <NUM>-<NUM> through the expansion unit <NUM>, and may further transmit the downlink transmission frames to the remote units <NUM>-<NUM> to <NUM>-<NUM>.

The headend unit <NUM> may deframe uplink transmission frames received from the expansion unit <NUM> and the remote units <NUM>-<NUM> to <NUM>-<NUM>, process data streams according to a corresponding one of the sources Sa to Sd, and transmit the data streams to a corresponding source. Signal processing in the uplink path of the headend unit <NUM> will also be described in more detail with reference to <FIG> below.

Although not shown in <FIG>, the headend unit <NUM> may be connected to other headend units and may transmit and receive the downlink transmission frames and the uplink transmission frames with other headend units.

The headend unit <NUM> may distribute or redistribute the capacity for a communication service. Here, the capacity may mean the capacity for each service. Also, the headend unit <NUM> may distribute or redistribute the capacity for each service. Here, the service may mean a carrier, frequency band, sector, service for each provider.

The expansion unit <NUM> may be communicatively coupled to the headend unit <NUM> and the remote units <NUM>-<NUM> to <NUM>-<NUM> and may expand the connection capacity of the headend unit <NUM>.

The expansion unit <NUM> may transmit the downlink transmission frames and the uplink transmission frames between the connected headend unit <NUM> and the remote units <NUM>-<NUM> to <NUM>-<NUM>. Signal processing in a downlink path and an uplink path of the expansion unit <NUM> will be described in more detail with reference to <FIG> below.

The expansion unit <NUM> may convert the format of a transmitted signal in a signal transmission process. For example, the expansion unit <NUM> may convert a digital signal received from the headend unit <NUM> into an Ethernet format and may transmit data converted into the Ethernet format to the remote units <NUM>-<NUM> to <NUM>-<NUM>. The expansion unit <NUM> may convert an Ethernet format signal received from the remote units <NUM>-<NUM> to <NUM>-<NUM> into a digital signal and transmit the digital signal to the headend unit <NUM>.

The expansion unit <NUM> may supply power to the remote units <NUM>-<NUM> to <NUM>-<NUM>. For example, the expansion unit <NUM> may supply power to the connected remote units <NUM>-<NUM> to <NUM>-<NUM> through power of Ethernet (PoE).

The expansion unit <NUM> may monitor a current for each of the remote units <NUM>-<NUM> to <NUM>-<NUM>, and may automatically turn off the power according to the monitoring.

The remote units <NUM>-<NUM> to <NUM>-<NUM> may be communicatively coupled to the headend unit <NUM>, and the remote units <NUM>-<NUM> to <NUM>-<NUM> may be communicatively coupled to the headend unit <NUM> through the expansion unit <NUM>.

The remote units <NUM>-<NUM> to <NUM>-<NUM> may deframe downlink transmission frames received from the headend unit <NUM> and the expansion unit <NUM> to generate data streams, and may restore the generated data streams to the original signals (e.g., an RF signal, a digitized RF signal, or Ethernet data). The remote units <NUM>-<NUM> to <NUM>-<NUM> may output the restored signals in the form required by a service subscriber device or the like located in the coverage.

The remote units <NUM>-<NUM> to <NUM>-<NUM> may perform certain processing on various radio signals received from the service subscriber device or the like located in the service coverage to generate an uplink transmission frame, and may transmit the uplink transmission frame to the headend unit <NUM> and the expansion unit <NUM>.

Signal processing in a downlink path and an uplink path of the remote units <NUM>-<NUM> to <NUM>-<NUM> will be described in more detail with reference to <FIG> below.

The remote units <NUM>-<NUM> to <NUM>-<NUM> may be divided into high power and low power according to an output.

Among the remote units <NUM>-<NUM> to <NUM>-<NUM>, a remote unit having a low power output may be referred to as a low power radio node, and a remote unit having a high power output may be referred to as a high power radio node.

The remote units <NUM>-<NUM> to <NUM>-<NUM> may include an integrated antenna and may be connected to an external antenna through an external antenna port.

In addition, the remote units <NUM>-<NUM> to <NUM>-<NUM> may include or be connected to a plurality of directional antennas so as to transmit a signal to a specific area or a specific sector or receive a signal from a specific area or a specific sector. For example, the remote units <NUM>-<NUM> to <NUM>-<NUM> may include at least one sector antenna or may be connected to the sector antenna. In addition, the remote units <NUM>-<NUM> to <NUM>-<NUM> may include or be connected to an omnidirectional antenna and a directional antenna. The remote units <NUM>-<NUM> to <NUM>-<NUM> may selectively operate only some of integrated antennas and external antennas.

Another remote unit, for example, an add-on remote unit, may be connected to at least some of the remote units <NUM>-<NUM> to <NUM>-<NUM>. This is to expand the capacity of the remote units <NUM>-<NUM> to <NUM>-<NUM> and may be selectively applied in multi input multi output (MIMO) service environment conditions.

The headend unit <NUM>, the expansion unit <NUM>, and the remote units <NUM>-<NUM> to <NUM>-<NUM> may be connected to each other through various transmission media. For example, the transmission medium may include an optical fiber, a coaxial cable, an Ethernet cable, or the like.

The headend unit <NUM>, the expansion unit <NUM>, and the remote units <NUM>-<NUM> to <NUM>-<NUM> may be connected to each other in various topologies.

For example, as shown in <FIG>, the headend unit <NUM> may be connected to the expansion unit <NUM> and the remote units <NUM>-<NUM> and <NUM>-<NUM> in a star structure. The expansion unit <NUM> may be connected to the remote units <NUM>-<NUM> and <NUM>-<NUM> in a star structure. The remote units <NUM>-<NUM> and <NUM>-<NUM>, the remote units <NUM>-<NUM> and <NUM>-<NUM>, the remote units <NUM>-<NUM> and <NUM>-<NUM>, and the remote units <NUM>-<NUM> and <NUM>-<NUM> may be connected to each other in a cascade structure.

However, the present disclosure is not limited thereto, and the headend unit <NUM>, the expansion unit <NUM>, and the remote units <NUM>-<NUM> to <NUM>-<NUM> may be connected to each other in various topologies such as a ring and a mesh, in addition to the above-described star and cascade structures. In addition, the number of the headend unit <NUM>, the expansion unit <NUM>, and the remote units <NUM>-<NUM> to <NUM>-<NUM> may also be changed.

The headend unit <NUM>, the expansion unit <NUM>, and the remote units <NUM>-<NUM> to <NUM>-<NUM> may be implemented to support at least one of a frequency division duplex scheme and a time division duplex scheme.

A signal processing method between the headend unit <NUM>, the expansion unit <NUM>, and the remote units <NUM>-<NUM> to <NUM>-<NUM> may be variously configured according to a designer's or user's selection.

Therefore, in the above-described embodiments, an analog processing method may be applied between some units in addition to a method of digitally processing and transmitting signals between each unit.

The system controller <NUM> may control and manage the DAS <NUM>. For example, the system controller <NUM> may monitor and control the status and operation of the headend unit <NUM>, the expansion unit <NUM>, and the remote units <NUM>-<NUM> to <NUM>-<NUM> included in the DAS <NUM>. The system controller <NUM> may be referred to as a network management system (NMS).

The system controller <NUM> may control procedures related to pseudo-dynamic changes to the structure of a transmission frame used for digital transmission of radio signals between nodes of the DAS <NUM>.

For example, the system controller <NUM> may control a frame layout change operation of the headend unit <NUM>, the expansion unit <NUM>, and the remote units <NUM>-<NUM> to <NUM>-<NUM>, as well as a handshaking operation for initiating a frame layout change.

In more detail, the system controller <NUM> exchanges protocol messages for starting the frame layout change with the headend unit <NUM>, and with the expansion unit <NUM> and the remote units <NUM>-<NUM> to <NUM>-<NUM> through the head end unit <NUM>. Through this, the DAS <NUM> may determine in advance whether a problem occurs on the service due to a frame layout change procedure, and the frame layout change procedure may be performed in a range that does not interfere with the service. The system controller <NUM> may use a Control & Management (C&M) channel when transmitting and receiving the messages.

When it is confirmed that preparation of the frame layout change is completed, the system controller <NUM> may transmit frame layout information received from the frame layout information generator <NUM> to the DAS <NUM>. The system controller <NUM> may also transmit the frame layout information to the headend unit <NUM> using the C&M channel. According to an embodiment, the frame layout information may also be transmitted from the system controller <NUM> to units of the DAS <NUM> in the above-described handshaking operation.

The units of the DAS <NUM> may change a predetermined frame layout based on the received frame layout information. The units of the DAS <NUM> frame data streams based on the changed frame layout.

In the above, the frame layout change procedure by the system controller <NUM> has been described as an example, but an initial setting procedure of a frame structure by the system controller <NUM> may be substantially the same.

The frame layout information generator <NUM> may generate frame layout information regarding the layout of an initial transmission frame according to the needs of a service provider, a DAS user, or the like, or by reconfiguring the layout of a predetermined transmission frame.

For example, the frame layout information generator <NUM> may generate frame layout information defining an initial structure of a transmission frame in response to a request of a service provider or the like at an initial facility stage of the DAS.

For another example, the frame layout information generator <NUM> may generate frame layout information in which the structure of a predetermined transmission frame is changed according to the request of a service provider when the demand for some of bands being served in a facility area of the DAS is lowered and the service is to be stopped or when a new band is added for the service.

For another example, the frame layout information generator <NUM> may generate frame layout information in which the structure of a predetermined transmission frame is changed based on the request of a service provider or a self-analysis result when the actual operating environment of the DAS is monitored through the system controller <NUM>, and it is determined that the provision of specific service bands is unnecessary for a long time.

As such, the DAS <NUM> according to embodiments may pseudo-dynamically change a frame structure to implement digital transmission of radio signals, thereby effectively using limited resources. This will be described in more detail with reference to the drawings later below.

In <FIG>, the frame layout information generator <NUM> is illustrated as a separate configuration from the system controller <NUM>, but is not limited thereto. The frame layout information generator <NUM> may be included in the system controller <NUM> or may be implemented independently of the system controller <NUM> and may be integrated with the system controller <NUM>.

<FIG> is an exemplary view of a structure of a transmission frame used in the distributed antenna system of <FIG>.

Referring to <FIG>, the transmission frame may be a frame for data transmitted between the headend unit <NUM>, the expansion unit <NUM>, and the remote units <NUM>-<NUM> to <NUM>-<NUM> of the DAS <NUM>.

The transmission frame may include a control field F1, a C&M field F2, and a data field F3.

The control field F1 may be a portion for controlling a connection device and transmitting information. The control field F1 may be a portion used for linking, time synchronization information transmission, a reset request, link reception quality transmission, redundancy status transmission, and the like of the connection device.

According to an embodiment, the control field F1 may be a concept including a portion related to vendor specific information. The vendor specific information is information that may be additionally set by a system administrator and may include information for identifying information of a vendor.

The C&M field F2 may be a portion used for monitoring and controlling the headend unit <NUM>, the expansion unit <NUM>, and the remote units <NUM>-<NUM> to <NUM>-<NUM>. Alternatively, the C&M field F2 may be used to perform software upgrade of the headend unit <NUM>, the expansion unit <NUM>, and the remote units <NUM>-<NUM> to <NUM>-<NUM>.

Network control information and performance monitoring information may be transmitted together with a predetermined control signal through the C&M field F2.

In some embodiments, frame layout information may be transmitted through the C&M field F2. The frame layout information is not transmitted every cycle. The frame layout information may be transmitted through the C&M field F2 when an initial setting or a change of a frame layout is required due to a change in the operating environment or the like during initial installation of the DAS <NUM>. The frame layout information may be transmitted through the C&M field F2 under the control of the system controller <NUM> (and the frame layout information generator <NUM>).

The frame layout information may include a start point offset and a length value of data streams (or I/Q data streams) corresponding to radio signals from the sources Sa to Sc. For example, the frame layout information may include a start point offset OA1 and a length LA1 of first data streams corresponding to band A1 among radio signals, a start point offset OB1 and a length LB1 of second data streams corresponding to band B1 among the radio signals, and a start point offset OC1 and a length LC1 of third data streams corresponding to band C1. The frame layout information may include a start point offset and a length value of Ethernet data from the source Sd. According to the start point offset and the length of each of the data streams included in the frame layout information, each of the data streams may be mapped to resource blocks of the data field F3 described later below.

The data field F3 may be a portion including actual data to be transmitted. For example, the data field F3 may include data streams for radio signals from the sources Sa to Sc. Alternatively, the data field F3 may include Ethernet data from the source Sd.

As illustrated by enlarging a portion PDF of the data field F3, the data streams may be sequentially mapped to the resource blocks, respectively, in a predetermined mapping sequence. For example, the first data stream, the second data stream, and the third data stream are mapped to resource blocks A1, B1, and C1, respectively. A case in which a frame layout is changed will be described in more detail with reference to <FIG> below.

<FIG> is an exemplary block diagram for describing the headend unit <NUM> of <FIG> in more detail.

Referring to <FIG>, the headend unit <NUM> may include an HEU control plane <NUM> and an HEU data plane <NUM>.

The HEU control plane <NUM> may process control information required to process a signal input to the headend unit <NUM> and transmit the signal to other units. In addition, the HEU control plane <NUM> may receive information necessary to change the structure of a transmission frame required for transmission of signals from the system controller <NUM>, and may transmit the information to other lower units.

The HEU control plane <NUM> may include an HEU controller <NUM> and an HEU C&M processor <NUM>.

The HEU controller <NUM> may process various operations related to the overall operation of the headend unit <NUM>, and may execute instructions related to the function of the headend unit <NUM>. For example, the HEU controller <NUM> may be a central processing unit (CPU).

The HEU C&M processor <NUM> is a component for transmitting and receiving C&M data such as status monitoring and control information with other units and the system controller <NUM>. For example, the HEU C&M processor <NUM> may be an Ethernet switch. The HEU C&M processor <NUM> may be communicatively coupled to the controller <NUM>, and may be controlled whether the C&M data is processed under the control of the controller <NUM>.

The controller <NUM> and the HEU C&M processor <NUM> of the HEU control plane <NUM> may perform handshaking (see <FIG>) for initiating a frame structure change operation, and may control a frame structure change operation of the HEU data plane <NUM> (see <FIG>).

The HEU data plane <NUM> may perform a forwarding function through interfacing, digitization, framing and/or routing of signals input to the headend unit <NUM>.

The HEU data plane <NUM> may include an RF interface <NUM>, a digital interface <NUM>, an Ethernet interface <NUM>, HEU processing circuitry <NUM>, and a plurality of PHYs <NUM>, <NUM>, and <NUM>.

The RF interface <NUM> may receive RF signals from the sources Sa and Sb and digitally convert the same, and may output data streams generated as a result of the digital conversion to a processing circuitry.

The RF interface <NUM> may analogize uplink signals and transmit them to the sources Sa and Sb.

The RF interface <NUM> may include an analog-to-digital converter (ADC) and a digital-to-analog converter (DAC) for RF-to-digital conversion processing for each of the sources Sa and Sb. Meanwhile, the RF interface <NUM> may be implemented as unit modules for each band of RF signals.

The digital interface <NUM> may receive digitized RF signals from the source Sc. The digitized RF signals may include a data packet formatted according to a standardized telecommunication protocol such as CPRI, OBSAI, and the like. In this case, in order to reduce high overheads of the CPRI and OBSAI, the digital interface <NUM> may include a resampler for adjusting a sampling rate. The digital interface <NUM> may output data streams to the processing circuit <NUM> after processing such as resampling of the digitized RF signals. In this case, the digitized RF signals may be digitized RF signals transmitted over Ethernet as defined in Ethernet based Common Public Radio Interface (eCPRI) and IEEE <NUM>. In this case, the digital interface <NUM> may include a converting module for format conversion.

The digital interface <NUM> may process uplink data streams output from the processing circuit <NUM> to conform to the original format and then transmit the uplink data streams to the source Sc.

Meanwhile, the digital interface <NUM> may interface with a centralized radio access network (C-RAN), a radio access exchange (RAX), an integrated BTS (all-in-one BTS), or the like to receive the digitized RF signals.

The Ethernet interface <NUM> may transmit and receive Ethernet data for the backhaul service from the source Sd. For example, the Ethernet interface <NUM> may be an Ethernet router, an Ethernet switch, or the like.

The HEU processing circuitry <NUM> may perform processing for forwarding data streams received from the RF interface <NUM>, the digital interface <NUM>, and the Ethernet interface <NUM> to other units based on a downlink path.

The HEU processing circuitry <NUM> may perform processing for forwarding data streams received from the plurality of PHYs <NUM> to <NUM> to the sources Sa to Sd based on an uplink path.

The HEU processing circuitry <NUM> may include a data stream processing logic circuit <NUM>, a control field processing logic circuit <NUM>, and a frame processing logic circuit <NUM>.

The data stream processing logic circuit <NUM> may perform resampling, aggregation processing, and the like on data streams based on the downlink path. The data stream processing logic circuit <NUM> may output the processed data streams to the frame processing logic circuit <NUM>.

The data stream processing logic circuit <NUM> may perform summation on data streams output from the frame processing logic circuit <NUM> based on the uplink path, and may transmit the processed data streams to the RF interface <NUM> or the like.

The control field processing logic circuit <NUM> may generate and process time synchronization information, a reset request, link reception quality information, and the like, and output the same to the frame processing logic circuit <NUM>, and may process information received from another unit output from the frame processing logic circuit <NUM> and output the processed information to the controller <NUM>.

Hereinafter, the frame processing logic circuit <NUM> will be described with reference to <FIG> and <FIG>.

First, referring further to <FIG>, the frame processing logic circuit <NUM> may frame data streams received from the data stream processing logic circuit <NUM> and control information received from the control field processing logic circuit <NUM> or deframe transmission frames received from the PHYs <NUM> to <NUM>, and may transmit the data streams and the control information to the data stream processing logic circuit <NUM> and the control field processing logic circuit <NUM>, respectively.

The frame processing logic circuit <NUM> may include a memory <NUM> and a processor <NUM>.

The memory <NUM> may include a non-transitory computer-readable medium (e.g., one or more non-volatile memory elements such as EPROM, EEPROM, flash memory, hard drive, etc.) capable of storing at least the following software (SW) modules.

The memory <NUM> may include a pre-mapper software module <NUM>-<NUM> that enables buffering of input data streams and aggregation and scheduling of the buffered data streams based on a downlink path, and output of deframed data streams to various ports based on an uplink path.

The memory <NUM> may include a pseudo-dynamic mapper software module <NUM>-<NUM> that enables data streams collected based on the downlink path to be framed according to a reconfigurable transmission frame structure and enables the data streams to be deframed based on the uplink path.

The memory <NUM> may include a post-mapper software module <NUM>-<NUM> that enables at least one of scrambling, encoding, and serialization on data framed based on the downlink path and enables at least one of parallelism, decoding, and descrambling based on the uplink path.

Meanwhile, the memory <NUM> may store frame layout information received from the system controller <NUM>.

Each of the software modules, when being executed by the processor <NUM>, includes instructions that cause the frame processing logic circuit <NUM> to perform corresponding functions. Thus, the non-transitory computer-readable medium of the memory <NUM> includes instructions for performing some or all of the above-described operations.

The processor <NUM> may be one or more suitable processors capable of executing instructions or scripts of one or more software programs stored in the memory <NUM>.

Next, a framing process of the frame processing logic circuit <NUM> will be described in more detail with reference to <FIG>.

The frame processing logic circuit <NUM> frames input data streams according to a layout of a predetermined transmission frame (or an initial transmission frame).

As described above with reference to <FIG>, a data field in the initially set transmission frame has a layout in which frequency band data streams, in the DAS <NUM>, are sequentially mapped to resource blocks in a predetermined mapping sequence.

In the initially set transmission frame, the mapping sequence pre-defines the mapping sequence for the resource blocks on the assumption that all data streams for each frequency band that the DAS <NUM> may support are mapped to the resource blocks. In addition, the mapping sequence has a fixed value for the purpose of improving data processing speed and reducing computational complexity.

However, even if all frequency bands are not serviced in the DAS <NUM>, the fixing of the mapping sequence causes a mapping position of data streams of a service frequency band to be fixed to spaced resource blocks, thereby causing a problem that pre-allocated resource blocks for a non-service frequency band are wasted.

For example, as shown in <FIG>, when the DAS <NUM> provides a service only to the frequency band A1, data streams corresponding to the frequency band A1 are mapped to resource blocks distributed far from each other due to the fixed mapping sequence. As a result, the resource blocks for the non-service frequency band are transmitted in an empty state (or with filled bit sequences indicating not to use the corresponding resource block).

In order to solve this problem, the DAS <NUM> according to embodiments does not use a frame layout of a transmission frame fixedly, but changes the frame layout according to the operating environment of the DAS <NUM>.

Based on the changed frame layout, the frame processing logic circuit <NUM> frames data streams into a transmission frame having a changed frame layout.

For example, as shown in <FIG>, when only the frequency band A1 is serviced by the DAS <NUM>, the frame layout information generator <NUM> generates information about a frame layout in which a mapping position of data streams corresponding to the frequency band A1 is changed.

The generated frame layout information may be information obtained by changing the mapping position of the data streams such that the data streams corresponding to the frequency band A1 are mapped to contiguous resource blocks. In the generated frame layout information, the mapping position may be changed by changing the mapping sequence. The contiguous resource blocks may be contiguous in a time domain. Further, resource blocks to which data streams are not allocated (unallocated resource blocks) are not interposed between the contiguous resource blocks, and all resource blocks may be adjacent to each other.

The frame processing logic circuit <NUM> reconfigures a predetermined initial frame layout based on the generated frame layout information, and frames data streams based on the reconfigured frame layout.

According to the embodiments, unlike the general DAS that uses a fixed frame structure, limited transmission resources may be efficiently used.

In addition, according to the embodiments, unallocated resource blocks may not be framed and transmitted, thereby reducing power consumption and improving the quality of service by lowering a bit error rate (BER).

Further, according to the embodiments, the unallocated resource blocks may be used as resources for Ethernet data or other heterogeneous services for a backhaul service, thereby facilitating integrating heterogeneous services through the DAS <NUM> even under limited resources.

Referring again to <FIG>, the headend unit <NUM> may include the plurality of PHYs <NUM>, <NUM>, and <NUM>.

The PHYs <NUM>, <NUM>, and <NUM> may convert transmission frames output from the processing circuit <NUM> according to a transmission medium, and may transmit the converted transmission frames to the expansion unit <NUM> and the remote units <NUM>-<NUM> and <NUM>-<NUM> connected through the transmission medium.

<FIG> is an exemplary block diagram for describing the expansion unit of <FIG> in more detail.

Referring to <FIG> and <FIG>, the expansion unit <NUM> may include an EU control plane <NUM> and an EU data plane <NUM>. Components included in each of the EU control plane <NUM> and the EU data plane <NUM> may perform substantially the same or similar functions as those of the components having the same names in the headend unit <NUM> of <FIG>.

However, unlike the HEU data plane <NUM> of <FIG>, the EU data plane <NUM> may not include the RF interface <NUM> and the digital interface <NUM>. This is because the expansion unit <NUM> transmits a transmission frame between the headend unit <NUM> and the remote units <NUM>-<NUM> to <NUM>-<NUM> without directly receiving an RF signal or a digitized RF signal. To this end, the expansion unit <NUM> may include a PHY <NUM> for connection with the headend unit <NUM> and the transmission of the transmission frame.

Meanwhile, since the expansion unit <NUM> may be connected to a heterogeneous application device for an Ethernet service, the expansion unit <NUM> may include an Ethernet interface <NUM>. For example, the heterogeneous application device may be small cell equipment, a Wi-Fi AP, or the like.

<FIG> is an exemplary block diagram for describing the remote unit of <FIG> in more detail.

Referring to <FIG>, the headend unit <NUM>-<NUM> may include an RU control plane <NUM> and an RU data plane <NUM>.

Components included in each of the EU control plane <NUM> and the EU data plane <NUM> may perform substantially the same or similar functions as those of the components having the same names of <FIG>.

Similar to the HEU data plane <NUM> of the headend unit <NUM> of <FIG>, the RU data plane <NUM> may include a digital interface <NUM> and an Ethernet interface <NUM>. Base station devices may be connected to each other through the digital interface <NUM>, and thus the DAS <NUM> may serve as an extension device among the base station devices. In addition, the Ethernet interface <NUM> may provide an Ethernet service to heterogeneous application devices, for example, a small cell, a Wi-Fi AP, or the like.

The RU data plane <NUM> may include a PHY <NUM> for a communicative connection with the headend unit <NUM>, and a PHY <NUM> for a communicative connection with another remote unit <NUM>-<NUM>.

The RU data plane <NUM> may include an RF conversion module <NUM> for transmitting and receiving an RF signal or a digitized RF signal due to the characteristics of the remote unit <NUM>-<NUM> that provides services to subscriber devices in coverage. The RF conversion module <NUM> may include an analog to digital converter (ADC), a digital to analog converter (DAC), an amplifier, and the like. In addition, although <FIG> illustrates the RF conversion module <NUM> as one module, the present disclosure is not limited thereto, and may include modules for each frequency band.

Meanwhile, although the remote unit <NUM>-<NUM> is exemplarily illustrated in <FIG>, the other remote units <NUM>-<NUM> to <NUM>-<NUM> may also be implemented to have substantially the same structure and function as the remote unit <NUM>-<NUM>.

<FIG> and <FIG> are flowcharts for describing a reconfiguration operation of a frame structure of the distributed antenna system of <FIG>.

<FIG> is a flowchart for describing a handshaking procedure for initiating a change of a frame structure in the DAS <NUM>, and <FIG> is a flowchart for describing a frame structure changing procedure in each unit after completion of the handshaking procedure. In the description of <FIG> and <FIG>, the same or corresponding reference numerals as those in <FIG> denote the same or corresponding elements, and therefore, repeated descriptions thereof will not be given herein and only differences will be mainly described.

First, referring to <FIG>, in operation S801, the system controller <NUM> transmits a frame layout change request message to the headend unit <NUM> according to new frame layout information and a change request received from the frame layout information generator <NUM>. The frame layout change request message may include new frame layout information. The frame layout information generator <NUM> may generate the new frame layout information according to a request of a service provider or a DAS user.

In operation S802, the headend unit <NUM> determines whether to change a frame in response to the received frame layout change request message. The headend unit <NUM> may check the integrity of a new frame layout, a use state of transmission resources, and the change in resource usage according to the new frame layout, and may determine whether to change a frame structure based on a result of the checking.

In operation S803, the headend unit <NUM> transmits the received frame layout change request message to the expansion unit <NUM>.

In operation S804, the expansion unit <NUM> may check an operation state or the like similarly to the headend unit <NUM>, and may determine whether to change the frame structure based on a result of the checking.

In operation S805, the expansion unit <NUM> transmits a confirmation message to the headend unit <NUM> if the determination result is a change in the frame structure.

In operation S806, the headend unit <NUM> transmits the received frame layout change request message to the remote units <NUM>-<NUM> to <NUM>-<NUM>.

In operation S807, the remote units <NUM>-<NUM> to <NUM>-<NUM> may check an operation state or the like similarly to the headend unit <NUM> and the expansion unit <NUM>, and may determine whether to change the frame structure based on a result of the checking.

In operation S808, the remote units <NUM>-<NUM> to <NUM>-<NUM> transmit a confirmation message to the headend unit <NUM> if the determination result is a change in the frame structure.

In operation S809, when receiving the confirmation message from the expansion unit <NUM> and the remote units <NUM>-<NUM> to <NUM>-<NUM>, the headend unit <NUM> transmits the confirmation message to the system controller <NUM>. Accordingly, the system controller <NUM> may recognize that a frame change procedure start condition of all units of the DAS <NUM> is completed.

In operation S810, the system controller <NUM> transmits a frame layout change start request message to the headend unit <NUM> in response to the confirmation message received from the headend unit <NUM>.

In operation S811 and operation S812, the headend unit <NUM> may transmit a frame layout change start message to the expansion unit <NUM> and the remote units <NUM>-<NUM> to <NUM>-<NUM>, respectively.

In operation S813, operation S814, and operation S815, each of the headend unit <NUM>, the expansion unit <NUM>, and the remote units <NUM>-<NUM> to <NUM>-<NUM> may start a frame layout change procedure based on the frame layout change start message.

Further referring to <FIG>, in operation S910, each of the headend unit <NUM>, the expansion unit <NUM>, and the remote units <NUM>-<NUM> to <NUM>-<NUM> changes a predetermined frame layout based on the new frame layout information.

In operation S930, each of the headend unit <NUM>, the expansion unit <NUM>, the remote units <NUM>-<NUM> to <NUM>-<NUM> frames data streams based on the changed frame layout.

As described above, according to embodiments, when service providers or DAS users requests a frame layout change, it is possible to secure the continuity and stability of service by changing a frame layout after provisioning for comprehensively determining a service state of a DAS without changing the frame layout immediately.

In <FIG> and <FIG>, the procedures assume the frame layout change procedure, but are not limited thereto. The above-described procedures may be substantially applied in initial setting of the frame layout.

Although not specified in <FIG> and <FIG>, the procedures illustrated in <FIG> and <FIG> may be separately performed when structures of a downlink transmission frame and an uplink transmission frame are changed. However, the present disclosure is not limited thereto, and a structure change procedure of the downlink transmission frame and the uplink transmission frame may be performed at the same time.

The term "determine" includes a wide variety of actions. For example, the term "determine" may include computing, processing, deriving, examining, looking up (e.g., looking up in a table, database, or other data structure), identifying, and the like. The term "determine" may also include receiving (e.g., receiving information), accessing (accessing data in a memory), and the like. The term "determine" may also include resolving, selecting, choosing, establishing, and the like.

Further, the methods described with reference to <FIG> and <FIG> include one or more operations or actions for achieving the methods. The operations and/or actions for achieving the methods may be interchanged with one another without departing from the scope of the claims. In other words, the order and/or use of specific operations and/or actions may be modified without departing from the scope of the claims, unless a certain order for the operations and/or actions is specified.

In addition, various operations of the methods described above may be performed by any suitable means capable of performing corresponding functions. The means includes, but is not limited to, various hardware and/or software components and/or modules such as an application specific integrated circuit (ASIC) or a processor. In general, when there are operations corresponding to the drawings, these operations may have a corresponding counterpart and functional components having the same number as the number of the counterpart.

<FIG> are views for describing an application form of a variable operation of a frame structure according to embodiments.

<FIG> is a view for describing a variable operation example of a frame layout for each transmission period in a distributed antenna system, and <FIG> is a view for describing a variable operation example of a frame layout for each of an uplink and a downlink in the distributed antenna system. <FIG> is a view for describing an example of variable operation of a frame layout for each branch (routing path) in the distributed antenna system.

In <FIG>, each embodiment will be described on the assumption of an operating environment in which although frequency bands that the distributed antenna system may provide are A to E, actual service frequency bands are frequency band A serviced by the remote units <NUM>-<NUM> and <NUM>-<NUM> and frequency band B serviced by the remote unit <NUM>-<NUM>.

First, referring to <FIG>, a layout of an identical initial transmission frame may be changed to different layouts in a transmission period T1 between the expansion unit <NUM> and the remote units <NUM>-<NUM> and <NUM>-<NUM> directly connected to the headend unit <NUM>, and a transmission period T2 between the expansion unit <NUM> and the remote unit <NUM>-<NUM>.

Due to aggregation, duplication, and distribution functions of the service frequency bands of the headend unit <NUM>, only resource blocks for the frequency bands A and B are required in the transmission period T1. Accordingly, in the transmission period T1, the layout of the initial transmission frame may be changed such that only the frequency bands A and B are mapped to contiguous resource blocks (Frame Layout #<NUM>).

Meanwhile, since only resource blocks for the frequency band B are required in the transmission period T2, the layout of the initial transmission frame may be changed such that only the frequency band B is mapped to the contiguous resource blocks (Frame Layout #<NUM>).

As described above, in an operating environment in which a transmission target frequency band is different for each level of transmission topology, a different frame layout may be applied between the levels of the transmission topology, that is, for each transmission period.

Referring to <FIG>, only resource blocks for the frequency band A are required in an uplink path from the remote units <NUM>-<NUM> and <NUM>-<NUM> to the headend unit <NUM>. Accordingly, in the transmission period T1 between the headend unit <NUM> and the remote units <NUM>-<NUM> and <NUM>-<NUM>, the layout of the initial transmission frame may be changed to allocate only the resource blocks for the frequency A to a transmission frame of the uplink path (Frame Layout #<NUM>).

Meanwhile, only resource blocks for the frequency band B are required in an uplink path from the remote unit <NUM>-<NUM> to the expansion unit <NUM> and the headend unit <NUM>. Accordingly, in the transmission periods T1 and T2 between the headend unit <NUM>, the expansion unit <NUM>, and the remote unit <NUM>-<NUM>, the layout of the initial transmission frame may be changed to allocate only the resource blocks for the frequency B to the transmission frames of the uplink path (Frame Layout #<NUM>).

As such, the distributed antenna system may be operated by applying a different frame layout according to a service state of each of the downlink path and the uplink path.

Referring to <FIG>, when the headend unit <NUM> is capable of selective collection of service frequency bands, in the transmission period T1 of <FIG>, a different frame layout may also be applied between the headend unit <NUM> and the remote units <NUM>-<NUM> and <NUM>-<NUM> and between the headend unit <NUM> and the expansion unit <NUM>.

Accordingly, the layout of the initial transmission frame may be changed between the headend unit <NUM> and each of the remote units <NUM>-<NUM> and <NUM>-<NUM> such that only the frequency band A is mapped to the contiguous resource blocks (Frame Layout # <NUM>). In addition, the layout of the initial transmission frame may be changed between the headend unit <NUM>, the expansion unit <NUM>, and the remote unit <NUM>-<NUM> such that only the frequency band B is mapped to the contiguous resource blocks (Frame Layout # <NUM>).

As such, the distributed antenna system may operate by applying a different frame layout for each branch (routing path).

The various illustrative logic blocks, components, or circuits described in connection with the present disclosure may be implemented or performed by a general-purpose processor designed to perform the functions disclosed herein, a digital signal processor (DSP), an ASIC, a field-programmable gate array (FPGA) or other programmable logic device (PLD), a discrete gate or transistor logic device, discrete hardware components, or any combination thereof. The general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. The processor may also be implemented in a combination of computing devices, for example, a combination of the DSP and the microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

Numerous modifications and adaptations will be readily apparent to one of ordinary skill in the art without departing from the scope of the present disclosure.

Claim 1:
A method of processing a data stream in a node unit (<NUM>, <NUM>, <NUM>) included in a distributed antenna system (<NUM>), the method comprising:
receiving frame layout information obtained by reconfiguring a frame layout of a predetermined transmission frame corresponding to a plurality of frequency bands supported by the distributed antenna system (<NUM>) based on at least one service frequency band, wherein the predetermined transmission frame is a frame for transmitting data streams between the node unit and other node units of the distributed antenna system (<NUM>);
changing the frame layout of the predetermined transmission frame based on the received frame layout information; and
framing a plurality of data streams, associated with the at least one service frequency band, based on the changed frame layout.