KR20170051262A - Radio-over-fiber transmission system - Google Patents

Abstract

Provided is a radio-over-fiber (RoF) system comprising: one or more baseband units (BBUs) which are connected to a core network of a service provider for a mobile internet service; an optical line terminal (OLT) which converts wireless signals, which are delivered from the BBUs, into optical signals; an optical distribution network (ODN) which includes optical fiber and an optical splitter; one or more optical network units (ONUs) which receive the optical signals converted in the OLT through the ODN, and convert the optical signals into the wireless signals; and one or more remote radio heads (RRHs) which receive the wireless signals converted in the ONUs, and output the wireless signals through a plurality of antennas. A user can use a high-speed mobile internet service by using the high-capacity ODN.

Description

RoF optical transmission system {RADIO-OVER-FIBER TRANSMISSION SYSTEM}

The present invention relates to a radio-over-fiber (RoF) optical transmission system.

Up to now, the ultra high-speed mobile communication network has been widely used as a digital optical transmission system based on CPRI (Common Public Radio Interface) / OBSAI (Open Base Station Architecture Initiative), which is divided into a digital unit (DU) and a radio unit To a cloud base station using a mobile front-hole based on the Internet. However, if the current digital-based optical transmission technology is used to build a 5G mobile communication network capable of providing ultra-wideband services, it is expected that it will be difficult to construct a commercial network due to a large network construction cost. Accordingly, there is a demand for a new type of optical communication technology for a mobile front-hall that has a simpler structure and supports the construction and operation of an economical cloud base station. A simple, cost-effective analog radio over fiber (ROF) optical transmission scheme is being considered worldwide as a potential candidate for a new form of mobile front-end optical communication technology.

The present invention proposes a RoF optical transmission system capable of providing a high-speed mobile Internet service to a user by using a high-capacity optical distribution network in providing a mobile Internet service to a user.

According to an embodiment of the present invention, there is provided a mobile communication system including at least one baseband unit (BBU) connected to a core network of a service provider for a mobile Internet service, a radio signal transmitted from the at least one baseband unit An optical line terminal (OLT) for converting an optical signal into an optical signal, an optical distribution network (ODN) including optical fibers and an optical splitter, an optical line terminal At least one optical network unit (ONU) for receiving a radio signal and converting the radio signal into a radio signal, and at least one remote radio head A Radio-over-Fiber (RoF) optical transmission system is provided which includes a Radio Head (RRH).

According to one embodiment, the optical line terminal is provided with a RoF optical transmission system connected to the at least one baseband unit through a service node interface corresponding to a first reference point.

According to one embodiment, the first reference point is provided with an RoF optical transmission system used for defining a signal type and an allowable signal delay or latency between the optical line terminal and the at least one baseband unit.

According to one embodiment, each of the at least one optical network units is connected to the at least one remote radio heads via a user node interface corresponding to a second reference point.

According to one embodiment, the second reference point is a RoF optical transmission system used to define signal types and acceptable signal delays or latencies between the at least one optical network units and the at least one remote radio heads. / RTI >

According to one embodiment, the at least one remote radio heads are provided with a RoF optical transmission system including a base station RF circuit and a frequency up / down converter.

According to one embodiment, each of the at least one remote radio heads is provided with a RoF optical transmission system including a plurality of antennas equipped with an amplifier for supporting a multi-input multi-output (MIMO) structure.

According to one embodiment, when the RoF optical transmission system is a point-to-point structure, a RoF optical transmission system is provided in which one optical network unit is connected to the optical distribution network.

According to an embodiment, when the RoF optical transmission system is a point-to-multipoint structure, a RoF optical transmission system is provided in which a plurality of optical network units are connected to the optical distribution network in star or ring topology.

According to an embodiment of the present invention, at least one baseband unit (BBU) connected to a core network of a service provider, and a service node interface corresponding to a reference point, And an optical line terminal (OLT) for converting a radio signal transmitted from the at least one baseband unit to an optical signal, wherein the optical signal converted by the optical line terminal is converted into an optical signal, Is transmitted to at least one optical network unit (ONU) connected to at least one remote radio head (RRH) through an optical distribution network (ODN) including an optical splitter A RoF optical transmission system is provided.

According to an embodiment of the present invention, an optical network unit (optical network unit) for receiving an optical signal output from an optical line terminal (OLT) through an optical distribution network (ODN) A remote radio head connected to the optical network unit via a user node interface corresponding to a reference point and outputting a radio signal transmitted from the optical network unit through a plurality of antennas, : RRH). ≪ / RTI >

Users can receive high-speed mobile Internet services using a high-capacity optical distribution network.

1 is an exemplary diagram for explaining a structure of a RoF optical transmission system according to a first embodiment of the present invention.
2 is an exemplary diagram of a RoF optical transmission system of point-to-point structure according to the first embodiment of the present invention.
3 is an exemplary diagram of a point-to-multipoint (Star type) RoF optical transmission system according to the first embodiment of the present invention.
4 is an exemplary diagram of a point-to-multipoint (ring type) RoF optical transmission system according to the first embodiment of the present invention.
5 is a diagram illustrating a structure of a single-channel RoF optical transmission system of the RFoF scheme according to the second embodiment of the present invention.
FIG. 6 is a diagram illustrating a structure of a single-channel RoF optical transmission system according to the second embodiment of the present invention.
FIG. 7 is a diagram illustrating a structure of a multi-channel RoF optical transmission system of the RFoF scheme according to the second embodiment of the present invention.
8 is a diagram illustrating a structure of a multi-channel RoF optical transmission system according to the second embodiment of the present invention.

It is to be understood that the specific structural or functional descriptions of embodiments of the present invention disclosed herein are presented for the purpose of describing embodiments only in accordance with the concepts of the present invention, May be embodied in various forms and are not limited to the embodiments described herein.

Embodiments in accordance with the concepts of the present invention are capable of various modifications and may take various forms, so that the embodiments are illustrated in the drawings and described in detail herein. However, it is not intended to limit the embodiments according to the concepts of the present invention to the specific disclosure forms, but includes changes, equivalents, or alternatives falling within the spirit and scope of the present invention.

The terms first, second, or the like may be used to describe various elements, but the elements should not be limited by the terms. The terms may be named for the purpose of distinguishing one element from another, for example without departing from the scope of the right according to the concept of the present invention, the first element being referred to as the second element, Similarly, the second component may also be referred to as the first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Expressions that describe the relationship between components, for example, "between" and "immediately" or "directly adjacent to" should be interpreted as well.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms " comprises ", or " having ", and the like, are used to specify one or more of the features, numbers, steps, operations, elements, But do not preclude the presence or addition of steps, operations, elements, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning of the context in the relevant art and, unless explicitly defined herein, are to be interpreted as ideal or overly formal Do not.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, the scope of the patent application is not limited or limited by these embodiments. Like reference symbols in the drawings denote like elements.

1 is an exemplary diagram for explaining a structure of a RoF optical transmission system according to a first embodiment of the present invention.

Referring to FIG. 1, the RoF optical transmission system according to the first embodiment may include at least one baseband unit (BBU) connected to a core network 110 of a service provider. 1, the baseband unit 130 may be coupled to the core network 110 to provide various mobile Internet services. The baseband unit 130 may generate a baseband radio signal. The baseband unit 130 may be included in a RoF optical transmission system to support a mobile communication system. The baseband unit 130 may be included in a central office (CO) in which a communication device for providing an information communication service to a subscriber is installed.

1, the RoF optical transmission system according to the first embodiment includes an optical line terminal (OLT) 130 for converting a radio signal transmitted from at least one baseband unit into an optical signal . Referring to FIG. 1, the OLT 130 may be connected to at least one baseband unit through a service node interface corresponding to a first reference point. A first reference point may be used to define the signal type and acceptable signal delay or latency between OLT 130 and at least one baseband unit. The service node interface may be set differently depending on which service is provided by the service provider.

The OLT 130 may be directly connected to at least one baseband unit. The OLT 130 may be included in the CO. The OLT 130 may be connected to one or more baseband units to maximize the transmission capacity of the RoF optical transmission system. Referring to the example of FIG. 1, the OLT 130 can utilize the RoF optical transmission system more efficiently by accommodating a total of two baseband units.

When receiving a plurality of wireless signals from at least one baseband unit, the OLT 130 may aggregate a plurality of wireless signals in order to efficiently utilize an existing optical infrastructure. Referring to FIG. 1, the baseband unit 120 may transmit a plurality of radio signals to the OLT 130. Alternatively, the OLT 130 may simultaneously receive radio signals from each of the two connected baseband units. In this case, the OLT 130 can generate a multiplexed optical signal of a plurality of received radio signals.

Referring to FIG. 1, the RoF optical transmission system according to the first embodiment may include an optical distribution network (ODN) 140 including optical fibers and an optical splitter. The ODN 140 may include optical fibers as a transmission medium. The optical splitter can distribute the signal so that the intensity of the signal distributed to the plurality of ONUs is maintained at a predetermined intensity or higher when the signal output from the OLT 130 is distributed to the plurality of ONUs. Thereby, the optical splitter can provide a plurality of connections between at least one OLT 130 and a plurality of ONUs.

1, the RoF optical transmission system according to the first embodiment includes at least one optical network unit (optical network unit) for receiving an optical signal converted in the OLT 130 through the ODN 140 and converting the optical signal into a radio signal, ONUs). The ONU 150 may be located at a remote site remote from the CO.

Referring to FIG. 1, the RoF optical transmission system according to the first embodiment includes at least one remote radio head (RRH) for receiving a radio signal converted by the ONU 150 and outputting the radio signal through a plurality of antennas can do. The ONU 150 may be connected to the remote radio head 160 via a user node interface (or user network interface) corresponding to the second reference point. A second reference point may be used to define the signal type and acceptable signal delay or latency between the ONU 150 and the at least one remote radio heads. The user node interface can be set differently depending on which service is provided by the service provider. That is, the signal type, acceptable signal delay, or acceptable latency of the service node interface or user node interface may depend on the service provided using the RoF optical transmission system.

The remote radio head 160 according to one embodiment may include a base station RF circuit and a frequency up / down converter. The remote radio head 160 according to one embodiment may include a plurality of antennas equipped with an amplifier for supporting a multi-input multi-output (MIMO) structure. The remote radio head 160 may include a high power amplifier and a low noise amplifier as the amplifiers for transmission and reception. Each of the plurality of remote radio heads connected to the ONU 150 may cover different sectors, frequency allocation (FA), antenna, and the like.

The frequency of the optical signal transmitted through the ODN 140 and the frequency of the radio signal used by the ONU 150 may be the same or different from each other. A method of setting the frequency of the optical signal transmitted through the ODN 140 to be the same as the frequency of the radio signal used in the ONU 150 and transmitting the same is referred to as RFoF (Radio Frequency-over-Fiber). The method of setting the frequency of the optical signal transmitted through the ODN 140 to a frequency other than the frequency of the radio signal used in the ONU 150 and transmitting the same is referred to as Intermediate Frequency-over-Fiber (IFoF). In this case, the frequency of the optical signal transmitted through the ODN 140 may be determined as the frequency between the frequency corresponding to the base band of the baseband unit 120 and the frequency of the radio signal of the ONU 150. The frequency of the optical signal transmitted through the ODN 140 in the IFoF scheme is referred to as an intermediate frequency.

The interface S is a point on the optical fiber immediately after the optical connection point (i.e., optical connector or optical splice) of OLT 130 (downstream) or ONU 150 (upstream). The interface R is a point on the optical fiber immediately after the optical connection point (i.e., optical connector or optical splice) of ONU 150 (downstream) or OLT 130 (upstream).

The RoF optical transmission system according to the first embodiment has been described along the downstream direction in which data is transmitted from the core network 110 to the subscribers of the ONU 150. [ Hereinafter, the RoF optical transmission system according to the first embodiment will be described along the upstream direction in which data is transmitted from the subscriber of the ONU 150 to the core network 110. [

The remote radio head 160 can receive the radio signal transmitted by the subscriber's terminal of the ONU 150 via the antenna. The received radio signal can be converted into an optical signal by the ONU 150. The ONU 150 can transmit the converted optical signal to the OLT 130 through the ODN 140. [

The OLT 130 may convert the received optical signal into a radio signal. OLT 130 can de-aggregate multiplexed optical signals received from one or more ONUs in response to aggregating a plurality of radio signals received from at least one baseband unit. Referring to FIG. 1, the ONU 150 may transmit an optical signal multiplexed using Wavelength Division Multiplexing (WDM) to the OLT 130. Alternatively, the OLT 130 may simultaneously receive optical signals from each of the two connected ONUs. In this case, the OLT 130 can demultiplex the received optical signals.

As described above, since the OLT 130 supports multiplexing / demultiplexing, the capacity of the RoF optical transmission system can be increased even if no additional optical fiber is added to the ODN 140. [ Thus, the RoF optical transmission system according to the first embodiment can efficiently utilize the optical infrastructure that has been conventionally deployed.

The OLT 130 may transmit the converted radio signal to the baseband unit 120. The data of the subscriber's terminal of the ONU 150 can be transmitted to the core network 110 by transmitting the radio signal received by the baseband unit 120 to the core network 110. [ Thus, the data of the subscriber of the mobile Internet service can be transmitted to the core network 110 quickly using the optical fiber. Similarly, in the downstream direction, data can be quickly provided to subscribers of mobile Internet services using optical fibers. Finally, the capacity and transmission rate of the mobile Internet service can be increased.

The structure of the RoF optical transmission system according to the first embodiment may depend on how the OLT 130 and the ONU 150 are connected. Hereinafter, different structures of the RoF optical transmission system will be described with reference to the drawings.

2 is an exemplary diagram of a RoF optical transmission system 200 of point-to-point structure according to the first embodiment of the present invention. Referring to FIG. 2, a RoF optical transmission system 200 having a point-to-point structure has a structure in which one ONU is connected to an ODN. The RoF optical transmission system 200 may be a structure in which one OLT and one ONU are connected through one ODN. The ODN of the RoF optical transmission system 200 may include only optical fibers except the optical splitter.

3 is an exemplary diagram of a point-to-multipoint (Star type) RoF optical transmission system 300 according to the first embodiment of the present invention. Referring to FIG. 3, a RoF optical transmission system 300 having a point-to-multipoint structure has a structure in which a plurality of ONUs are connected to an ODN. The RoF optical transmission system 300 may be a structure in which one OLT and a plurality of ONUs are connected through one ODN. The ODN of the RoF optical transmission system 300 can distribute an optical signal to a plurality of ONUs using an optical splitter of an OLT. The optical signal output by the OLT can be transmitted to all the ONUs, and only the OLT can receive the optical signal output from the ONUs.

4 is an exemplary diagram of a point-to-multipoint (ring type) RoF optical transmission system 400 according to a first embodiment of the present invention. Referring to FIG. 4, the OLT can connect with a plurality of ONUs using a network topology based on a ring structure.

The structure of the RoF optical transmission system described in Figs. 2 to 4 may be a logical link or a physical link topology of the RoF optical transmission system.

5 is a diagram illustrating a structure of a single-channel RoF optical transmission system of the RFoF scheme according to the second embodiment of the present invention. Referring to FIG. 5, the single channel RoF optical transmission system according to the second embodiment may include a baseband unit 510 and a remote radio head 520. The baseband unit 510 may be located at the CO and the remote radio head 520 may be located remotely to the CO using optical fibers.

Referring to FIG. 5, the baseband unit 510 can be divided into a portion for transmitting an optical signal in a downstream direction and a portion for receiving an optical signal in an upstream direction. The baseband unit 510 may include a baseband digital signal modulator, a digital-to-analog converter, an RF upconverter, and a RoF transmitter, in a configuration related to the downstream direction. The baseband unit 510 may include a baseband digital signal demodulator, an analog-to-digital converter, an RF downconverter, and a RoF receiver in a configuration related to the upstream direction.

Referring to FIG. 5, the remote radio head 520 can be divided into a configuration for a downstream direction and a configuration for an upstream direction. The remote radio head 520 may include a RoF receiver, a downstream RF filter, and a downstream antenna as a configuration for the downstream direction. The remote radio head 520 may comprise a RoF transmitter, an upstream RF filter, and an upstream antenna as a configuration for the upstream direction.

For the downstream direction, the baseband digital signal modulator may generate a baseband digital downlink signal that is communicated to each subscriber. The digital-to-analog converter can convert the generated digital form of the baseband downlink signal to an analog downlink signal. The RF upconverter can increase the frequency of the analog downlink signal to enable wireless transmission. The analog downlink signal output by the RF up-converter may be an electrical signal. The RoF transmitter can convert the frequency-shifted analog downlink signal into an optical signal for analog optical transmission. The baseband unit 510 may output the converted optical signal from the RoF transmission unit to the remote radio head 520.

The remote radio head 520 can convert the optical signal received through the RoF reception unit back into an electrical signal. The converted electric signal can be output to the atmosphere as a radio signal after passing through the RF filter and the antenna. Finally, the subscriber's terminal can receive a wireless signal.

For the upstream direction, the uplink signal generated by the subscriber's terminal is delivered to the antenna of the remote radio head 520. The RF filter can filter the radio signal transmitted to the antenna. The RoF transmitter can convert the radio signal into an optical signal (optical uplink signal). The optical uplink signal converted by the RoF transmission unit can be transmitted to the baseband unit 510 through the optical fiber. The baseband unit 510 may receive the optical uplink signal through the RoF receiver and then use the RoF downconverter to convert the frequency of the optical uplink signal to a frequency corresponding to the digital baseband. Finally, the digital baseband uplink signal having the frequency corresponding to the digital baseband can be demodulated by the baseband digital signal demodulator.

FIG. 6 is a diagram illustrating a structure of a single-channel RoF optical transmission system according to the second embodiment of the present invention.

6, a single intermediate frequency signal can be transmitted through the optical fiber between the baseband unit 610 and the remote radio head 620. In the downstream direction, the baseband unit 610 may further include an intermediate frequency up-converter 611 for changing the frequency of the analog down-link signal converted by the digital-analog converter to an intermediate frequency. 6, the analog downlink signal converted by the intermediate frequency up-converter 611 can be output to the remote radio head 620 through the RoF transmission unit.

In the downstream direction, the remote radio head 620 further includes an intermediate frequency-to-radio frequency converter 621 that converts the radio signal of the intermediate frequency output by the RoF receiver into a radio signal of a frequency . Referring to FIG. 6, the signal converted by the intermediate frequency-to-RF converter 621 may be transmitted to the subscriber terminal via the RF filter and the antenna.

In the upstream direction, the remote radio head 620 may further include a radio frequency-to-intermediate frequency converter 622 that converts the radio signal of the radio frequency received from the antenna into a radio signal of intermediate frequency used in the RoF transmitter. Referring to FIG. 6, the intermediate frequency radio signal converted by the RF-to-IF converter 622 can be transmitted to the RoF transmitter. Therefore, the RoF transmitter of the remote radio head 620 can convert the radio signal into the optical uplink signal according to the intermediate frequency. The converted optical uplink signal may be transmitted along the optical fiber to the baseband unit 610.

In the upstream direction, the baseband unit 610 may receive the optical uplink signal of intermediate frequency transmitted by the remote radio head 620 through the RoF receiver. The baseband unit 610 can convert the optical uplink signal of the intermediate frequency to the optical uplink signal of the frequency corresponding to the baseband through the intermediate frequency down converter 612. The intermediate frequency down-converter 612 can transmit the converted optical up-link signal to the analog-to-digital converter.

Comparing the RFoF single channel RoF optical transmission system of FIG. 5 and the IFoF single channel RoF optical transmission system of FIG. 6, the remote radio head 620 includes an intermediate frequency to radio frequency converter (621) and a radio frequency-to-intermediate frequency converter (622). Further, in the IFoF single channel RoF optical transmission system, it is necessary to synchronize the frequency in the process of converting the intermediate frequency to the radio frequency.

FIG. 7 is a diagram illustrating a structure of a multi-channel RoF optical transmission system of the RFoF scheme according to the second embodiment of the present invention. According to the second embodiment, in order to realize a high capacity RoF optical transmission system, the RoF optical transmission system can use a channel merging or multiplexing scheme.

Channel RF transmission system of the RFoF scheme and the multi-channel RoF optical transmission system of the RFoF scheme of FIG. 7 in the downstream direction, the baseband unit 710 using the multi-channel uses a plurality of baseband digital signal modulation And a channel merging unit 711 merging the digital downlink signals to which the added digital downlink signals are added. The channel merging unit 711 may combine or multiplex a plurality of digital baseband mobile signals in an electric signal domain. A plurality of merged (multiplexed) digital baseband mobile signals may be converted to analog signals (digital-to-analog converters) and then converted to frequencies allowed for radio signals (RF upconverters). The electrical signal converted to radio frequency can be converted into an optical signal and transmitted to the remote radio head 720 through the RoF transmission unit.

In response to the channel merging unit 711, the remote radio head 720 using the multi-channel may further include an electric signal separating unit 721 for dividing the merged signal received by the RoF receiving unit. The remote radio head 720 may convert the analog downlink signal received through the RoF receiver to an electrical signal. The electric signal converted by the RoF receiving unit can be distributed to a plurality of RF filters by the electric signal separating unit 721. The divided electrical signals may be filtered by an RF filter and then transmitted through an antenna and transmitted to a user terminal according to the radio frequency of each antenna.

In the upstream direction, the RFoF single channel RoF optical transmission system of FIG. 5 and the RFoF type multichannel RoF optical transmission system of FIG. 7 are compared. In the remote radio head 720 using multi channels, And an electric signal combining unit 722 for merging signals. The remote radio head 720 may receive a plurality of analog radio signals generated by a plurality of user terminals via an antenna. The analog radio signals received through the antenna may be filtered by an RF filter and then combined by an electrical signal combining unit 722. The RoF transmitter of the remote radio head 720 may convert the combined signal into a optical uplink signal.

The baseband unit 710 using multi-channels corresponding to the electrical signal combining unit 722 further includes a channel separating unit 712 for distributing the merged digital downlink signals to a plurality of baseband digital signal demodulating units . The RoF receiver of the baseband unit 710 can receive the optical uplink signal converted by the remote radio head 720. The optical uplink signal can be converted into an electrical signal by the RoF receiver. The RF downconverter can convert the frequency of the converted electric signal to a frequency corresponding to the baseband. The analog-to-digital converter can convert the analog electrical signal converted by the RF downconverter into a digital baseband signal. Finally, the channel separating unit 712 separates (demultiplexes) the digital baseband signal converted by the analog-to-digital converter, and then divides the separated digital baseband signals into a plurality of baseband digital signal demodulators. Each of the plurality of baseband digital signal demodulators can demodulate the digital baseband signal received from the channel demultiplexer 712.

8 is a diagram illustrating a structure of a multi-channel RoF optical transmission system according to the second embodiment of the present invention.

In the downstream direction, a plurality of signals multiplexed by the channel merging unit of the baseband unit 810 can be converted into analog signals by a digital-analog converter. By converting the frequency of the analog signal to the intermediate frequency by the intermediate frequency up-converter 811, the transmission efficiency of the optical signal can be improved. The operation of the digital-to-analog converter and the intermediate frequency up-converter 811 can be performed simultaneously.

The RoF transmitter of the baseband unit 810 can convert the electric signal converted to the intermediate frequency into an optical signal and transmit it to the remote radio head 821. The optical signal transmitted from the baseband unit 810 through the optical fiber to the remote radio head 821 may be an analog optical signal. The remote radio head 821 can receive the optical signal through the RoF reception unit, and the RoF reception unit can convert the received optical signal into the electric signal. The electrical signal divider may distribute the converted electrical signal to a plurality of intermediate frequency to radio frequency converters. The intermediate frequency to radio frequency converter 821 may convert the frequency of the distributed electrical signal from the intermediate frequency to the radio frequency of the antenna corresponding to the intermediate frequency to radio frequency converter 821. [ Finally, the electric signal converted into the radio frequency is filtered by the RF filter, and then transmitted to the user terminal through the antenna.

In the upstream direction, the remote radio head 820 can receive a plurality of analog radio signals generated by a plurality of subscriber terminals via a plurality of antennas. A plurality of analog radio signals received by each of the plurality of antennas may be filtered by an RF filter and then converted from a radio frequency to an intermediate frequency by a radio frequency intermediate frequency converter 822. [ The plurality of electric signals converted to the intermediate frequency may be combined by the electric signal coupling unit, and then converted into an optical signal by the RoF transmission unit and transmitted to the baseband unit 810.

The baseband unit 810 can receive the optical signal through the RoF receiver. The RoF receiver can convert the received optical signal into an electrical signal. The intermediate frequency down-converter 812 can convert the intermediate frequency of the converted electric signal to a frequency corresponding to the base band. The analog-to-digital converter can convert the baseband analog signal to a baseband digital signal. The baseband digital signal may be distributed to a plurality of baseband digital signal demodulators by a channel demultiplexer. Finally, each of the plurality of baseband digital signal demodulators can demodulate the distributed baseband digital signal.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA) , A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

110: Core network
120: Baseband unit
130: Optical line terminal
140: Optical distribution network
150: optical network unit
160: Remote radio head

Claims (11)

At least one baseband unit (BBU) connected to a core network of a service provider for mobile Internet service;
An optical line terminal (OLT) for converting a radio signal transmitted from the at least one baseband unit into an optical signal;
An optical distribution network (ODN) including optical fibers and optical splitters;
At least one optical network unit (ONU) for receiving an optical signal converted by the optical line terminal through the optical distribution network and converting the optical signal into a radio signal; And
At least one remote radio head (RRH) for receiving a converted radio signal from the optical network unit and outputting the converted radio signal through a plurality of antennas
(RoF) optical transmission system. The method according to claim 1,
The optical line terminal,
Wherein the at least one baseband unit is coupled to the at least one baseband unit via a service node interface corresponding to a first reference point. 3. The method of claim 2,
Wherein the first reference point comprises:
Wherein said RoF optical transmission system is used to define signal types and allowable signal delays or latencies between said optical line terminal and said at least one baseband unit. The method according to claim 1,
Wherein each of the at least one optical network units comprises:
Wherein the at least one remote radio head is coupled to the at least one remote radio heads via a user node interface corresponding to a second reference point. 5. The method of claim 4,
Wherein the second reference point comprises:
Wherein the RoF optical transmission system is used to define signal types and acceptable signal delays or latencies between the at least one optical network units and the at least one remote radio heads. The method according to claim 1,
The at least one remote radio heads comprising:
A RoF optical transmission system comprising a base station RF circuit and a frequency up / down converter. The method according to claim 1,
Wherein each of the at least one remote radio heads comprises:
A RoF optical transmission system comprising a plurality of antennas mounted with an amplifier to support a multi-input multi-output (MIMO) structure. The method according to claim 1,
Wherein one optical network unit is connected to the optical distribution network when the RoF optical transmission system is a point-to-point structure. The method according to claim 1,
And a plurality of optical network units are connected to the optical distribution network when the RoF optical transmission system is a point-to-multipoint structure. At least one baseband unit (BBU) connected to the core network of the service provider; And
An optical line terminal (OLT) connected to the at least one baseband unit through a service node interface corresponding to the reference point, for converting a radio signal transmitted from the at least one baseband unit into an optical signal, )
/ RTI >
The optical signal transformed by the optical line terminal,
At least one optical network unit (ONU) connected with at least one remote radio head (RRH) through an optical distribution network (ODN) including optical fibers and optical splitters The RoF optical transmission system. An optical network unit (ONU) for receiving an optical signal output from an optical line terminal (OLT) through an optical distribution network (ODN) and converting the optical signal into a radio signal; And
At least one remote radio head (RRH) connected to the optical network unit through a user node interface corresponding to the reference point and outputting a radio signal transmitted from the optical network unit through a plurality of antennas
And a RoF optical transmission system.

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