Abstract:
The present invention discloses a base station, the size of which is reduced and which is to be adopted in a mobile communication system. The disclosed small base station includes: a polyhedral housing; an antenna unit disposed on the widest surface of the outer surface of the housing; a first board arranged on any outer surface of the housing; and two or more boards which are arranged in an upright state with the first board and which are arranged to face three or more outer side surfaces of the housing, respectively.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/KR2013/007063 filed on Aug. 6, 2013, which claims priority to Korean Application No. 10-2012-0086155 filed on Aug. 7, 2012 and Korean Application No. 10-2012-0108217 filed on Sep. 27, 2012, which applications are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a base station of a mobile communication system, and more particularly to a small base station installed in a building or a house. 
     BACKGROUND ART 
     A base station of a mobile communication system refers to a system for relaying electric waves of a portable terminal in a cell. The base station is generally installed on a roof of a building to relay electric waves of a portable terminal. Accordingly, base stations are present in units of cells, and the base stations controls transmission of signals, designation of a communication channel, and monitoring of a communication channel in units of cells, as well as an interface function between the portable terminal and a switch center. 
     The antennas employed in the base station are distributed due to presence of many control antennas which may be vertically or horizontally beam-tilted. 
     In addition, a small base station for improving communication quality while reducing frequency load is installed as a system for covering an area which is still smaller than the radius of the current existing mobile communication service. The base station is used to accommodate data traffic intensively generated in a small area. As a small base station can be installed in a building or a house, a shading area can be solved and a higher network and a convergence service can be realized. 
     However, because the small base station employed in the existing mobile communication system is configured such that main components mounted to the interior of the base station, for example, a main board, a power supply unit, an antenna, and a power amplifier are vertically stacked, there is a limit in reducing the entire size of the base station. 
     In particular, because the small base station according to the related art is configured such that a main board, a power supply unit and the like are installed on one board, the overall size of the main board become larger and heat emission of the power amplifier becomes problematic. 
     SUMMARY 
     Accordingly, the present invention provides a small base station of a mobile communication system which can advantageously realize a small size by three-dimensionally disposing main elements at proper places with respect to a box. 
     The present invention also provides a small base station of a mobile communication system which can minimize a heat emission problem by disposing a plurality of power amplifiers such that they are spaced apart from each other by the farthest distance. 
     In accordance with an aspect of the present invention, there is provided a base station of a mobile communication system, including: a polyhedral box; an antenna unit installed on the widest one of outer surfaces of the box; a first board disposed on one of the outer surfaces of the box; and at least two boards disposed in an upright position from the first board, and disposed to face at least three outer surfaces of the box. 
     The box includes: first and second outer surfaces which face each other; and third and fourth outer surfaces disposed between the first and second outer surfaces while facing each other. At least three inner walls are provided inside a surface of the box on which the antenna is installed. 
     The board includes: second and third boards disposed in parallel to the first and second outer surfaces to face the first and second outer surfaces, respectively; and a fourth board disposed in parallel to the third outer surface while facing the third outer surface. 
     The first board is a digital interface module, the second and third boards are first and second power amplifiers, and the fourth board is an up/down converter. 
     The power supply unit is disposed on the fourth outer surface, and is disposed to be perpendicular to the first board. 
     The antenna unit includes an antenna and an antenna transmission/reception module stacked on the antenna. 
     The inner wall acts as a reflective plate of the antenna unit. 
     The box is a filter unit. 
     The filter unit has at least two filters coupled to face each other. 
     The first to fourth boards and the power supply unit are disposed to surround all the outer surfaces of the box. 
     As described above, the digital interface module and the antenna unit are stacked in the Z axis direction, but the first and second power amplifiers, the up/down converter, and the power supply unit are disposed along the X and Y axes such that the base station can be made small. In particular, according to the present invention, a plurality of boards are not vertically stacked but are three-dimensionally disposed along the outer surfaces of the box in consideration of heat emission, so that the boards can be efficiently mounted in a limited space. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing an external appearance of a small base station according to the present invention; 
         FIG. 2  is an exploded perspective view showing a configuration of the small base station according to the present invention; 
         FIG. 3  is a perspective view showing a box to which an antenna unit of the small base station according to the present invention is mounted, and is a view showing a state in which an antenna is removed from the antenna unit; 
         FIG. 4  is a sectional view showing the box to which the antenna unit of the small base station according to the present invention is mounted; 
         FIG. 5  is a plan view showing the box to which the antenna unit of the small base station according to the present invention is mounted, and is a view showing a state in which the antenna is removed from the antenna unit; and 
         FIG. 6  is a perspective view showing the antenna of the small base station according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention includes: a polyhedral box; an antenna unit installed on the widest one of outer surfaces of the box; a first board disposed on any one of the outer surfaces of the box; and a least two boards disposed in an upright position from the first board, and disposed to face at least three outer surfaces of the box. 
     Hereinafter, the present invention will be described with reference to the accompanying drawings. The same reference numerals denote the same elements. 
     In the description of the small base station according to the present invention, the Cartesian coordinate system shown in  FIGS. 1 and 2  is used, in which the X axis denotes a transverse direction, the Y axis denotes a longitudinal direction, and the Z axis denotes a perpendicular direction. The base station  10  according to the present invention is small-sized in a transverse direction, a longitudinal direction, and a perpendicular direction thereof as compared with the related art, but maintains a performance of an existing base station despite the small size. That is, the small size means that the entire size of the base station is small long the three axes as compared with the related art. 
       FIG. 1  shows an external appearance of the small base station  10  (hereinafter, simply referred to as a base station) according to the present invention.  FIG. 1  shows an assembled state of the base station  10 , and shows an external appearance of the base station  10  in which an outer cover  11  and a heat sink  12  are coupled to each other. The heat sink  12  is disposed on the bottom of the base station to support main elements mounted on the heat sink  12 , and the outer cover  11  is coupled to the heat sink in the Z axis direction to protect main internal elements. 
       FIG. 2  is an exploded perspective view showing a configuration of the base station  10  according to the present invention. As shown in  FIG. 2 , an antenna unit  15 , at least three boards B 1  to B 4  (printed circuit boards), a power supply unit (PSU)  14 , and a heat sink  12 , including a box  13 , are three-dimensionally disposed at proper locations of the base station  10 . The three-dimensional disposition of the plurality of boards does mean that the boards are not stacked along one axis but the main elements are disposed in consideration of the three axes including the X, Y, and Z axes, and in particular means that a plurality of boards are disposed in a reference board in an upright position along the X and Y axes and the remaining main elements are disposed along the Z axis, which three-dimensional disposition is advantageous in the small-size of the base station. In addition, the base station  10  according to the present invention considers a heat emission problem as well as the three-dimensional disposition of the main elements. 
     The box  13  has a polyhedral shape, for example, a rectangular parallelepiped shape, and includes a plurality of outer surfaces and a plurality of inner walls and the antenna unit  15  is accommodated in the interior space. In particular, the box  13  has an open-topped box shape, and has at least three inner walls  136 , at least three outer surfaces  131  to  134 , and a bottom surface  135 . The outer surfaces of the box include at least three outer surfaces  131  to  134 , and a bottom surface  135 . The inner walls include at least three inner walls.  FIGS. 2 and 3  show four inner walls  136 , and four outer surfaces  131  to  134 . The outer surfaces and the inner walls have the same shapes and the same sizes. 
     The plurality of outer surfaces include first and second outer surfaces  131  and  132  facing each other, and third and fourth outer surfaces  133  and  134  disposed between the first and second outer surfaces  131  and  132  while facing the first and second outer surfaces  131  and  132 , respectively. The first and second outer surfaces  131  and  132  are parallel to each other, and the third and fourth outer surfaces  133  and  134  are parallel to each other. The first outer surfaces  131  is perpendicular to the third and fourth surfaces  133  and  134 , and the second outer surface  132  is perpendicular to the third and fourth surfaces  133  and  134 . In addition, the first to fourth outer surfaces  131  to  134  are flat. Because the box has a rectangular parallelepiped shape, the first to fourth outer surfaces  131  to  134  have a rectangular shape. 
     The box  13  has a plurality of outer surfaces, in which in the aspect of the shapes of the outer surfaces, the first outer surface  131  and the second outer surface  132  may have the same rectangular or square shape, the third outer surface  133  and the fourth outer surface  134  may have the same rectangular or square shape, and the bottom surface  135  also may have a rectangular or square shape. 
     In the aspect of the sizes (areas) of the outer surfaces of the box, the first and second outer surfaces  131  and  132  and the third and fourth outer surfaces  133  and  134  of the box may have a rectangular shape of the same size, may have rectangular shapes of different sizes, or may have a square shape of the same size. 
     The bottom surface  135  of the outer surfaces, which is located at the bottom of the box, may have a rectangular or square shape, or may have a shape larger than, smaller than, or the same as those of the first and second outer surfaces  131  and  132  and the third and fourth outer surfaces  133  and  134 . It is preferable that the box  13  according to the present invention has a bottom surface  135  which is wider than the first and second outer surfaces  131  and  132  and the third and fourth outer surfaces  133  and  134 .  FIG. 2  shows that the box  2  has a bottom surface  135  which is wider than the first and second outer surfaces  131  and  132  and the third and fourth outer surfaces  133  and  134 . It is preferable that the bottom surface  135  has the widest area such that the antenna unit  15  is disposed on the bottom surface  135 . 
     In detail, the disposition of the boards mounted to the outer surfaces of the box  13  will be described. 
     A plurality of boards B 1  to B 4 , and the power supply unit  14  are disposed on the outer surfaces of the box  13 . The plurality of boards includes first and fourth boards B 1  to B 4 . The first board B 1  is disposed on the bottom surface  135  of the box  13 . The second and third boards B 2  and B 3  are disposed on the first and second outer surfaces  131  and  132  of the box  13 . The fourth board B 4  is disposed on the third outer surface  133 . The power supply unit  14  is disposed on the fourth outer surface  134 . 
     The first board B 1  is a digital interface module, and is disposed in parallel to the bottom surface of the box  135  while facing the bottom surface of the box  135 . The second board B 2  is a first power amplifier PAM, and is disposed in parallel to the first outer surface  131  while facing the first outer surface  131 . The third board B 3  is a second power amplifier PAM, and is disposed in parallel to the second outer surface  132  while facing the second outer surface  132 . The fourth board B 4  is an up/down converter, and is disposed in parallel to the third outer surface  133  while facing the third outer surface  133 . The power supply unit  14  is disposed in parallel to the fourth outer surface  134  while facing the fourth outer surface  134 . 
     As mentioned above, the first to fourth boards B 1  to B 4 , and the power supply unit  14  substantially have plate shapes, and may be disposed on the outer surface of the box, in detail, the first to fourth outer surfaces  131  to  134  and the bottom surface  135  are flat so as to have apertures or to be adhered to each other. The first and second power amplifiers B 2  and B 3  are disposed in parallel to each other while facing each other. The up/down converter B 4  and the power supply unit  14  are disposed in parallel to each other while being spaced apart from each other. 
     The first and second power amplifiers B 2  and B 3  are disposed to be spaced apart from each other with respect to the box  13 , in consideration of heat emission efficiency. That is, the first and second power amplifiers B 2  and B 3  have power amplifying elements (not shown), in consideration of a heat emission problem. That is, when a plurality of power amplifiers B 2  and B 3  are provided, it is most effective in heat emission to dispose the power amplifiers B 2  and B 3  such that they are spaced apart from each other at the longest distance possible. It is preferable to dispose the power amplifiers such that they face each other when the box  13  has a rectangular parallelepiped shape as shown in the drawings, and it is most preferable that the power amplifiers are separated by the largest distance possible when the box  13  has various shapes. 
     It will be appreciated by those skilled in the art that the power amplifiers may be disposed in two boards rather than in one board in consideration of the heat emission problem. 
     Although it has been exemplified that the first and second power amplifiers B 2  and B 3  are disposed on the first and second outer surfaces  131  and  132 , they may be disposed on the third and fourth outer surfaces  133  and  134 . The up/down converter B 4  and the power supply unit  14  are disposed on the third and fourth outer surfaces  133  and  134 , and may be disposed on the first and second outer surfaces  131  and  132  when the first and second power amplifiers B 2  and B 3  are disposed on the third and fourth outer surfaces  133  and  134 . The up/down converter B 4  and the power supply unit  14  face each other while being spaced apart from each other. The first power amplifier B 2  is perpendicular to the digital interface module B 1 , the up/down converter B 4 , and the power supply unit  14 , and the second power amplifier B 3  is perpendicular to the digital interface module B 1 , the up/down converter B 4 , and the power supply unit  14 . 
     In the disposition of the plurality of boards of the base station, the second to fourth boards are disposed in upright positions along a peripheral circumference of the first board. 
     Referring to  FIGS. 3 to 6 , the antenna unit  15  is disposed in the interior of the box  13 . The antenna unit  15  includes an antenna  150 , an antenna transmission/reception module, a reflective plate  151 , a ground plate  152 , and a plurality of radiation elements  153 . The ground plate  152  and the radiation elements  153  are electrically connected to each other to transmit a radiation signal. A plurality of radiation elements  153  is provided to have radiation patterns, respectively. The radiation patterns may be realized by a tetragonal shape, a circular shape, a tetragonal ring shape, and the like. 
     As shown in  FIG. 4 , if the antenna unit  15  is disposed in the interior of the box  13 , the four inner walls  136  of the box act as reflective plates of the antenna. 
     The box  13  corresponds to a filter unit of the base station apparatus, and although it is exemplified in the embodiment that the filter has a cavity of a rectangular parallelepiped shape, the present invention is not limited thereto. The filter unit has at least two filters coupled to face each other. 
     When the box  13  has a rectangular parallelepiped shape, it is preferable that the antenna unit  15  is disposed on the widest of the six outer surfaces. That is, the reflective plate  151  of the antenna unit  15  becomes more helpful in improving RF characteristics as the areas of the reflective plate  151  become wider, and thus it is preferable that the reflective plate  151  is installed on the widest surface as shown in the drawings. 
     In the description of the disposition state of the main internal elements of the base station according to the present invention, electrical connections or a connection structure between the main internal elements are omitted. The electrical connections may be, for example, cables, and the connection structure may be, for example, a connector or a connection terminal. 
     According to the present invention, the digital interface module and the antenna unit are stacked in the Z axis direction, but the first and second power amplifiers, the up/down converter, and the power supply unit are disposed along the X and Y axes such that the base station can be made small. In particular, according to the present invention, a plurality of boards are not vertically stacked but are three-dimensionally disposed along the outer surfaces of the box in consideration of heat emission, so that the boards can be efficiently mounted in a limited space.