Patent Publication Number: US-10334663-B2

Title: Signal processing device for distributed antenna system

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a Continuation of U.S. application Ser. No. 15/395,720, filed on Dec. 30, 2016, which is a Continuation-in-Part of International Application No. PCT/KR2015/005130, filed May 22, 2015, the contents of which are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND 
     1. Field 
     The inventive concept relates to a signal processing device. More specifically, the inventive concept relates to a signal processing device that can improve the convenience of management by integrating a power amplifier, a duplexer, and a linearizer as a module and improve flexibility and extensibility so as to be transformable corresponding to a change in system development concept. 
     2. Description of Related Art 
     Mobile communication usage of users has been rapidly increased due to development of mobile communication and the users want to stably receive a communication service without the constraints of time and space. However, it is difficult for an operator to smoothly provide the communication service to the users while a shadow area is generated due to a limited output of a base station and a constraint such as the position or a peripheral geographical feature of the base station, and as a scheme for resolving such a problem, a distributed antenna system (DAS) is used. 
     The DAS is installed in an area in which a radio wave is not received or weakly received, such as the inside of a building, a basement of the building, a subway, a tunnel, an apartment complex of a residential area, a stadium, or the like, to provide the communication service up to the shadow area where a signal of the base station is difficult to reach and extend coverage of the base station, and consists of a headend apparatus that that is communicatively connected with the base station and a plurality of remote apparatus that is connected to the headend apparatus through a optical transport medium and is communicatively connected to a user terminal to process a signal. 
     In the plurality of remote apparatus of the DAS according to the related art, there are a lot of cases in which a deployment state of a power amplifier, a duplexer, and a linearizer or whether the power amplifier, the duplexer, and the linearizer are provided is decided according to a development concept of the system, and as a result, the system cannot be united and it is thus difficult to manage the plurality of remote apparatus and it is also difficult to efficiently cope with a change in operational environment of the system. 
     SUMMARY 
     The inventive concept relates a signal processing device that can improve the convenience of management by integrating a power amplifier, a duplexer, and a linearizer as a module and can also improve flexibility and extensibility so as to be transformable corresponding to a change in system development concept. 
     According to an exemplary embodiment of the inventive concept, there is provided a signal processing device including: a base module including a power amplifier; a first module coupled to the base module and selectively including an RF processing unit for processing an RF signal; a circuit substrate detachably coupled to the first module and including a linearizer correcting a distortion signal; and a second module covering the first module and including a duplexer separating a transmitted or received RF signal. 
     An accommodating groove accommodating the circuit substrate may be formed on one surface of the first module. 
     A first connector transferring a signal processed and introduced by the RF processing unit to the linearizer, and a second connector transferring the signal processed through the linearizer to the power amplifier may be provided on one surface of the first module. 
     The linearizer may include a pre-distortion device. 
     The signal processing device may further include a sensing unit provided in the first module to sense whether the circuit substrate is mounted or detached. 
     The signal processing device may further include a switch unit switching the signal processed by the RF processing unit to be processed by the linearizer and thereafter, transferred to the power amplifier at the time of mounting the circuit substrate according to a detection of whether the circuit substrate is mounted or detached by the sensing unit. 
     The switch unit may switch the signal introduced into the signal processing device to be bypassed to the power amplifier at the time of separating the circuit substrate according to a detection of whether the circuit substrate is mounted or detached by the sensing unit. 
     A signal processing device according to an exemplary embodiment of the inventive concept can improve the inconvenience of management by integrating a power amplifier, a duplexer, and a linearizer as a module and easily replacing or separating parts as necessary, and also can improve flexibility and extensibility so as to be transformable corresponding to a change in system development concept. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
       The above and other aspects, features and advantages of certain exemplary embodiments of the inventive concept will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is an exploded perspective view of a signal processing device according to an exemplary embodiment of the inventive concept; 
         FIG. 2  is a perspective view of the signal processing device according to the exemplary embodiment of the inventive concept; 
         FIG. 3  is a diagram schematically illustrating a first module of the signal processing device according to the exemplary embodiment of the inventive concept; and 
         FIGS. 4 to 6  are usage state diagrams to which the signal processing device according to the exemplary embodiment of the inventive concept is applied. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The inventive concept may have various modifications and various exemplary embodiments and specific exemplary embodiments will be illustrated in the drawings and described in detail through the detailed description. However, this is not intended to limit the inventive concept to the specific exemplary embodiments, and it should be understood that the inventive concept covers all the modifications, equivalents and replacements included in the spirit and technical scope of the inventive concept. 
     In describing the inventive concept, when it is determined that the detailed description of the publicly known art related to the inventive concept may unnecessarily obscure the gist of the inventive concept, the detailed description thereof will be omitted. Further, numerical figures (for example, first, second, and the like) used during describing the specification are just identification symbols for differentiating one component from other components. 
     Further, in the specification, when it is mentioned that one element is “connected with” or “accesses” the other element, the one element may be directly connected with or directly accesses the other element, but if there is a not particularly contrary description, it should be appreciated that both elements may be connected with or accesses each other with another element intervening therebetween. 
     In addition, a term “˜part (unit)”, ˜er”, “˜or”, “˜module”, or the like, described in the specification means a unit of processing at least one function or operation and may be implemented by hardware or software or a combination of hardware and software. 
     In addition, it will be apparent that in the specification, components are just classified for each main function which each component takes charge of. That is, two or more components to be described below may be provided to be combined into one component or one component may be provided to be separated into two or more for each of more subdivided functions. In addition, each of the components to be described below may additionally perform some or all functions among functions which other components take charge of in addition to the main function which each component takes charge of, and some functions among the main functions which the respective components take charge of may be exclusively charged and performed by other components, of course. 
     A distributed antenna system means a coverage system for an in-building service that transfers voice communication and data communication with high quality for seamlessly accessing and means a system for servicing an analog and digital telephone system which is serviced in multiple bands through at least one antenna. Further, the distributed antenna system may enhance a poor radio wave environment in building and enhance a poor received signal strength indication (RSSI) and chip energy/others interference (Ec/Io) which is total receiving sensitivity of a mobile terminal. 
     Meanwhile, a distributed antenna system using a signal processing device according to an exemplary embodiment may support a mobile communication standard which is used worldwide. For example, the distributed antenna system may support frequencies such as a very high frequency (VHF), an ultra high frequency (UHF), 700 MHz, 800 MHz, 850 MHz, 900 MHz, 1900 MHz, 2100 MHz band, 2600 MHz band, and the like, and an FDD-scheme service and a TDD-scheme service. In addition, the distributed antenna system may support an advanced mobile phone service (AMPS) which is a representative of analog and multiple mobile communication standards such as Time-Division Multiplexing Access (TDMA), Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), High Speed Downlink Packet Access (HSDPA), Long Term Evolution (LTE), Long Term Evolution Advanced (LTE-A), and the like of digital. 
     Hereinafter, exemplary embodiments of the inventive concept will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is an exploded perspective view of a signal processing device according to an exemplary embodiment of the inventive concept.  FIG. 2  is a perspective view of the signal processing device according to the exemplary embodiment of the inventive concept.  FIG. 3  is a diagram schematically illustrating a first module of the signal processing device according to the exemplary embodiment of the inventive concept.  FIGS. 4 to 6  are usage state diagrams to which the signal processing device according to the exemplary embodiment of the inventive concept is applied. 
     In  FIGS. 1 to 6 , a base module  10 , a power amplifier  11 , a first terminal  15 , a first module  20 , an RF processing unit  21 , a accommodating groove  23 , a first connector  25 , a second connector  27 , a switch unit  29 , a circuit substrate  30 , a linearizer  31 , a second module  40 , a duplexer  41 , a handle  43 , a second terminal  45 , a connection line  47 , a low-noise amplifier  51 , and a gain control unit  53  are illustrated. 
     Referring to  FIG. 1 , the signal processing device according to the exemplary embodiment includes: a base module  10  including the power amplifier  11 ; a first module  20  coupled to the base module  10  and selectively including the RF processing unit  21  for processing an RF signal; a circuit substrate  30  detachably coupled to the first module  20  and including the linearizer  31  compensating a distortion signal; and a second module  40  covering the first module  20  and including the duplexer  41  separating a transmitted or received RF signal to improve the convenience of management by integrating the power amplifier  11 , the duplexer  41 , and the linearizer  31  as a module and to improve flexibility and extensibility so as to be transformable corresponding to a change in system development concept. 
     A distributed antenna system (DAS) may include a headend apparatus (not illustrated), which is communicatively coupled to a base station and constitutes a headend node, and a hub apparatus serving as an extension node, and a plurality of remote apparatus respectively disposed at remote service location. The distributed antenna system (DAS) may be implemented as an analog distributed antenna system. However, the technical spirit of the inventive concept is not limited thereto. The distributed antenna system (DAS) may be implemented as a digital distributed antenna system and in some cases, implemented as a mixed type (for example, some nodes perform analog processing and residual nodes perform digital processing) thereof. The signal processing device according to an exemplary embodiment of the inventive concept may be mounted in at least one of the remote apparatus for processing a signal having a predetermined frequency band. According to one or more implementations, if the distributed antenna system (DAS) has employed a neutral host architecture to integrally support various services (e.g., multi-band services, multi-carrier services, etc.) or services of a plurality of providers, a plurality of the signal processing device may be mounted in the remote apparatus for a predetermined frequency band. 
     The signal processing device according to the exemplary embodiment may include a base module  10 , the first module  20 , the circuit substrate  30 , and the second module  40 . 
     The base module  10  may be coupled to the first module  20  to be described below and may include the power amplifier  11 . The power amplifier  11  may amplify a transmission signal to transmit the amplified transmission signal to the duplexer  41  to be described below. 
     The first module  20  may be coupled to the base module  10  and may selectively include the RF processing unit  21 . The first module  20  may be coupled to the top of the base module  10  and may selectively include the RF processing unit  21  for processing a radio frequency (RF) signal. In the exemplary embodiment, it is described that the base module  10  and the first module  20  are configured as separate parts, respectively and the first module  20  is coupled to the top of the base module  10 , but the base module  10  and the first module  20  are formed as one component, and as a result, the power amplifier  11  and the RF processing unit  21  may be provided therein. 
     The RF processing unit  21  may be selectively provided in the first module  20 . That is, when it is determined that the RF processing unit  21  is required according to a system development concept, the RF processing unit  21  may be provided in the first module  20  and, when the RF processing unit  21  is not required or a separate RF processing unit  21  is provided outside the signal processing device, the RF processing unit  21  may not be provided in the first module  20 . The RF processing unit  21  which is used to process a transmitted RF signal may be an RF-IF conversion device that converts the RF signal into an intermediate frequency (IF) signal. In general, since the RF signal transmitted from the base station is a high-power signal, the RF signal is converted into a signal having appropriate power through the RF processing unit  21 . However, when the RF processing unit  21  is a component that may process the RF signal, the RF processing unit  21  may be configured in various schemes. 
     Meanwhile, the low-noise amplifier (LNA)  51  and the gain control unit (gain block)  53  used in a reverse-direction link may be provided in the first module  20 . Noise of a signal transferred through the duplexer  41  may be removed and power of the signal may be controlled while passing through the low-noise amplifier  51  and the gain control unit  53  to be output to the outside of the signal processing device (see  FIGS. 4 to 6 ). 
     The circuit substrate  30  may be detachably coupled to the first module  20  and may include the linearizer  31  that compensates a distortion signal. The circuit substrate  30  may be detachably coupled to the top of the first module  20  and mounted on the signal processing device as necessary. The linearizer  31  may be provided in the circuit substrate  30  to correct and linearize the distortion signal. The linearizer  31  may include a pre-distortion device. In this case, the pre-distortion device may be an analog pre-distortion (APD) device or a digital pre-distortion (DPD) device. 
     In detail, when the circuit substrate  30  is mounted on the signal processing device, the signal processed by the RF processing unit  21  is transmitted to the linearizer  31  of the circuit substrate  30  and the transmitted signal is compensated by the linearizer  31  and transmitted to the power amplifier  11 . On the contrary, when the linearizer  31  is not required and the circuit substrate  30  including the linearizer  31  is not mounted on the signal processing device according to the system concept, the signal introduced into the signal processing device is transmitted to the power amplifier  11 . Further, since an external input signal is an IF signal, when a separate RF-IF conversion device is not required in the signal processing device, the RF processing unit  21  may not be provided in the first module  20 . As such, in the signal processing device according to the exemplary embodiment, since the circuit substrate  30  including the linearizer  31  may be mounted/detached according to the system development concept, flexibility and extensibility may be improved as the signal processing device. 
     The second module  40  may cover the first module  20  and the second module  40  may include the duplexer  41  that separates the transmitted or received RF signal. The handle  43  is provided on the top of the second module  40  to facilitate transportation or installation of the integrated signal processing device. Meanwhile, a first terminal  15  may be formed at one side of the base module  10  and a second terminal  45  may be formed at one side of the second module  40 , and the first terminal  15  and the second terminal  45  may be connected by the connection line  47 . 
     As such, the power amplifier  11 , the duplexer  41 , the linearizer  31 , and the RF processing unit  21  may be integrated as the module, and parts may easily be replaced and detached as necessary to improve the convenience of management. 
     The accommodating groove  23  accommodating the circuit substrate  30  may be formed on one surface of the first module  20 . The accommodating groove  23  may be formed on the top of the first module  20  so as to correspond to the circuit substrate  30 , and the circuit substrate  30  may be inserted into the accommodating groove  23  to be provided in the signal processing device integrally with the first module  20 . 
     In this case, a first connector  25  and a second connector  27  may be formed on one surface of the first module  20 . 
     Referring to  FIG. 3 , the first connector  25  is formed on one surface of the first module  20 , and as a result, the signal processed and introduced by the RF processing unit  21  is transferred to the linearizer  31 . The second connector  27  is formed on one surface of the first module  20  to be separated from the first connector  25  to transfer the signal processed through the linearizer  31  to the power amplifier  11 . 
     Meanwhile, the signal processing device according to the exemplary embodiment may further include a sensing unit provided in the first module  20  to sense whether the circuit substrate  30  is detachable. The sensing unit may determine whether the circuit substrate  30  is mounted or detached according to whether the circuit substrate  30  contacts the first module  20 . The sensing unit is provided in the first module  20  and actuates the switch unit  29  to be described below by detecting whether the circuit substrate  30  is mounted or detached to control the signal introduced into the first module  20 . 
     The switch unit  29  may switch the signal processed by the RF processing unit  21  to be processed by the linearizer  31  and thereafter, transferred to the power amplifier  11  at the time of mounting the circuit substrate  30  according to a detection of whether the circuit substrate  30  is mounted or detached. Further, the switch unit  29  may switch the signal introduced into the signal processing device to be bypassed to the power amplifier  11  at the time of separating the circuit substrate  30  according to a detection of whether the circuit substrate  30  is mounted or detached. In detail, when the circuit substrate  30  is mounted, the signal processed by the RF processing unit  21  is introduced into the linearizer  31  of the circuit substrate  30  through the first connector  25  and the signal processed by the linearizer  31  is transferred to the power amplifier  11  through the second connector  27 . Meanwhile, when the sensing unit senses that the circuit substrate  30  is detached from the first module  20 , the switch unit  29  operates to bypass the input signal introduced into the signal processing device and transfer the bypassed input signal to the power amplifier  11 . 
       FIGS. 4 to 6  are usage state diagrams to which the signal processing device according to the exemplary embodiment of the inventive concept is applied. 
     Referring to  FIG. 4 , the exemplary embodiment shows a case in which the RF processing unit  21  and the linearizer  31  are required in the signal processing device according to the system concept, the RF processing unit  21  is provided in the first module  20 , and the circuit substrate  30  including the linearizer  31  is mounted on the top of the first module  20 . The signal introduced into the RF processing unit  21  is subjected to signal processing such as frequency conversion by the RF processing unit  21  to be transferred to the linearizer  31 . The signal transferred to the linearizer  31  is compensated by the linearizer  31  and transferred to the power amplifier  11 . The signal transferred to the power amplifier  11  is amplified by the power amplifier  11  and thereafter, transferred to an antenna (not illustrated) through the duplexer  41 . In this case, the RF processing unit  21  may be an RF-IF conversion device for converting the RF signal into the IF signal and the linearizer  31  may be a linearizer including the pre-distortion device for correcting the converted IF signal. 
     Referring to  FIG. 5 , the exemplary embodiment shows a case in which the linearizer  31  not including the pre-distortion device is required in the signal processing device according to the system concept, and the RF processing unit  21  is not provided in the first module  20  and the circuit substrate  30  including the linearizer  31  is mounted on the top of the first module  20 . The input signal is transferred to the linearizer  31  and the signal transferred to the linearizer  31  is corrected and transferred to the power amplifier  11 . The signal transferred to the power amplifier  11  is amplified by the power amplifier  11  and thereafter, transferred to an antenna (not illustrated) through the duplexer  41 . 
     Referring to  FIG. 6 , an exemplary embodiment shows a case in which the linearizer  31  is not required in the signal processing device according to the system concept and the RF processing unit  21  is not provided in the first module  20  and the linearizer  31  is not also provided. The sensing unit determines whether the circuit substrate  30  is separated from the first module  20  according to whether the circuit substrate  30  contacts the first module  20  and the switch unit  29  switches the signal to bypass the input signal introduced into the signal processing device to the power amplifier  11 . 
     As described above, the signal processing device according to the exemplary embodiment may integrate the power amplifier  11 , the duplexer  41 , and the linearizer  31  as the module to improve the convenience of the management and improve the flexibility and extensibility so as to be transformable corresponding to the change in system development concept. 
     Hereinabove, the inventive concept has been described in detail with reference to the preferred embodiment, but the inventive concept is not limited to the embodiment and various modifications and changes may be made by those skilled in the art within the technical spirit and scope of the inventive concept.