Abstract:
A base station system supporting multi-sector/multi-FA in which, when a board goes out of order, a redundant board is automatically switched on, so as to prevent the call from being cut off and the entire capacity of the system from being influenced, thereby enabling the system to maintain normal operation and to be perfectly managed. In the base station system, signal transmitting and receiving paths of up- and down-converters are separated from each other, each board contains all FAs, and redundant boards are utilized, so that the system can normally operate in soft/hard-redundancy modes without cut-off of the call, even when a problem occurs in the paths.

Description:
PRIORITY  
         [0001]    This application claims priority to applications entitled “Base Station System Supporting Multi-Sector/multi-FA For Seamless Call Service” filed in the Korean Industrial Property Office on Sep. 11, 2001 and Dec. 29, 2001, and assigned Serial Nos. 2001-55840 and 2001-88389, respectively. The contents of these applications are hereby incorporated by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a base station of a mobile communication system, and more particularly to a base station system supporting multi-sector/multi-frequency assignment.  
           [0004]    2. Description of the Related Art  
           [0005]    In general, a base station of a mobile communication system such as a Universal Mobile Telecommunication System (UMTS) has a construction capable of supporting multi-sector and multi-frequency assignment (hereinafter, referred to as FA), so as to increase a user capacity and efficiently utilize the frequency.  
           [0006]    [0006]FIG. 1 is a block diagram illustrating a construction of a conventional base station system of a mobile communication system, which can support multi-sector/multi-FA and provide an antenna diversity effect. In this case, it is assumed that the base station system supports six sectors/four FAs, although FIG. 1 shows only one sector and four FAs supported by the base station system, for convenience of description.  
           [0007]    Referring to FIG. 1, a signal received by a first receiving antenna Rx Ant.  1  is band pass-filtered by a band pass filter (BPF)  11 . A low noise amplifier (LNA)  13  amplifies the signal which has been band pass-filtered by the band pass filter  11 . A divider  15  divides the signal amplified by the low noise amplifier  13  into signals for each of the four FAs. That is, the signals divided by the divider  15  are applied to an up/down-converter board  21  for FA 1 , an up/down-converter board  22  for FA 2 , an up/down-converter board  23  for FA 3 , and an up/down-converter board  24  for FA 4 , respectively.  
           [0008]    A signal received by a second receiving antenna Rx Ant.  2  is band pass-filtered by a band pass filter  12 . A low noise amplifier  14  amplifies the signal which has been band pass-filtered by the band pass filter  12 . A divider  16  divides the signal amplified by the low noise amplifier  14  into signals for each of the four FAs. That is, the signals divided by the divider  16  are applied to an up/down-converter board  21  for FA 1 , an up/down-converter board  22  for FA 2 , an up/down-converter board  23  for FA 3 , and an up/down-converter board  24  for FA 4 , respectively.  
           [0009]    The four up/down-converter boards  21  to  24  for the four FAs constitute an up/down-converter  20 . Each board includes first down-converters  21   a,    22   a,    23   a,  and  24   a  for downwardly converting frequencies of signals processed after being received through the first receiving antenna Rx Ant.  1 , second down-converters  21   b,    22   b,    23   b,  and  24   b  for downwardly converting frequencies of signals processed after being received through the second receiving antenna Rx Ant.  2 , and up-converters  21   c,    22   c,    23   c,  and  24   c  for upwardly converting frequencies of signals to be transmitted.  
           [0010]    A combiner  31  receives and combines the four signals with the upwardly-converted frequencies from the four up/down-converter boards  21  to  24  of the up/down-converter  20 , and outputs the combined signal. A divider  32  divides again the signal combined by the combiner  31  into four signals, which can be inputted to four power amplifiers (PA)  33  to  36 . The four power amplifiers  33  to  36  correspond to the four FAs, respectively. A combiner  37  combines the four signals from the power amplifiers  33  to  36  and outputs a combined signal. The band pass filter  38  band pass-filters the combined signal and outputs it through a transmission antenna Tx Ant.  
           [0011]    In the base station system as illustrated in FIG. 1 (which is called “Node B” in the UMTS), the power amplifiers  33  to  36  and the four up/down-converter boards  21  to  24  are elements which require automatic switching when the boards are abnormal. The base station system having the construction described above employs a hard-redundancy mode, utilizing extra boards when it has a small number of sectors and FAs. When the base station has an increased number of sectors and FAs, only the power amplifier employs a soft-redundancy mode utilizing load sharing, due to the problem of the number of the boards. In this case, when one of the four up/down-converter boards  21  to  24  is out of order, an FA of a sector corresponding to the out-of-order board cannot be used. That is, in the conventional base station system, one FA becomes useless when a board is out of order, since transmitting and receiving paths according to the FAs are formed in one up/down converter.  
           [0012]    In the conventional base station system as described above, although each board independently operates in order to support the multi-sector/multi-FA, when one of the boards is out of order, the call is cut off, thereby having a detrimental effect on the entire capacity of the system.  
         SUMMARY OF THE INVENTION  
         [0013]    Accordingly, the present invention has been designed to solve the above-mentioned problems occurring in the prior art, and one object of the present invention is to provide signal-transmitting/receiving systems, which prevent a call from being cut off even when any one board goes out of order in a base station system supporting multi-sector/multi-FA.  
           [0014]    It is another object of the present invention to provide signal-transmitting/receiving systems, which prevent an entire capacity of a system from being influenced by any one board, which has gone out of order in a base station system supporting multi-sector/multi-FA.  
           [0015]    In order to accomplish the above and other objects, there is provided a base station system supporting multi-sector/multi-FA according to the present invention, in which when a board goes out of order, a redundant board is automatically switched on, so as to prevent a call from being cut off and an entire capacity of the system from being influenced, thereby enabling the system to maintain normal operation and to be perfectly managed. In the base station system according to the present invention, signal transmitting and receiving paths of up- and down-converters are separated from each other, each board contains all FAs, and redundant boards are utilized, so that the system can normally operate in soft/hard-redundancy modes without cut-off of the call, even when any problem occurs in the paths.  
           [0016]    A signal-receiving system according to the present invention comprises at least one signal-receiving section. In the signal-receiving system, a down-converter includes at least one down-converter board and at least one redundant down-converter board. One board selected from among the at least one down-converter board and the at least one redundant down-converter board downwardly converts a frequency of a signal inputted through the signal-receiving section, the down-converter board corresponding to the signal-receiving section. A switching section is connected between the signal-receiving section and the down-converter. The switching section is switched to connect the at least one down-converter board with the signal-receiving section when the at least one down-converter board is normal, and as to connect the at least one redundant down-converter board with the signal-receiving section when the at least one down-converter board is abnormal.  
           [0017]    A signal-transmitting system according to the present invention comprises an up-converter. The up-converter includes at least one up-converter board and at least one redundant up-converter board. One board selected from among the at least one up-converter board and the at least one redundant up-converter board and downwardly converts a frequency of a transmitting signal which is to be transmitted. A switching section is switched to supply said transmitting signal to the at least one up-converter board when the at least one up-converter board is normal, and as to supply said transmitting signal to the at least one redundant up-converter board when the at least one up-converter board is abnormal. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    The above and other objects, features, and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:  
         [0019]    [0019]FIG. 1 is a block diagram illustrating a construction of a conventional base station system;  
         [0020]    [0020]FIG. 2 is a block diagram illustrating a construction of a base station system of a mobile communication system according to a preferred embodiment of the present invention;  
         [0021]    [0021]FIG. 3 is a block diagram illustrating the construction of the down-converter illustrated in FIG. 2 in more detail;  
         [0022]    [0022]FIG. 4 is a block diagram illustrating the construction of the up-converter illustrated in FIG. 2 in more detail;  
         [0023]    [0023]FIG. 5 is a diagram illustrating in more detail the switching control operation on the receiving paths of the base station system according to the preferred embodiment of the present invention; and  
         [0024]    [0024]FIG. 6 is a diagram illustrating in more detail the switching control operation on the transmitting paths of the base station system according to the preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]    Preferred embodiments of the present invention will be described herein below with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.  
         [0026]    [0026]FIG. 2 is a block diagram illustrating a construction of a base station system of a mobile communication system according to a preferred embodiment of the present invention, which can support multi-sector/multi-FA and provide an antenna diversity effect. Although FIG. 2 illustrates only one sector supported by the base station system for convenience of description, the base station system supports six sectors/four FAs, and each sector includes four FAs, each of which forms two receiving paths and one transmitting path so as to obtain an antenna diversity effect. In each of the transmitting and receiving paths, in order to enable the paths to operate normally even when one of the boards operates abnormally, power amplifiers employ a soft-redundancy mode while up/down-converter boards employ a hard-redundancy mode.  
         [0027]    First, a construction of a receiving path according to a preferred embodiment of the present invention will be described hereinafter with reference to FIG. 2.  
         [0028]    A signal received by a first receiving antenna Rx Ant.  1  is band pass-filtered by a band pass filter  11 . A low noise amplifier (LNA)  13  amplifies the signal which has been band pass-filtered by the band pass filter  11 . A signal received by a second receiving antenna Rx Ant.  2  is band pass-filtered by a band pass filter  12 . A low noise amplifier  14  amplifies the signal which has been band pass-filtered by the band pass filter  12 . The first receiving antenna Rx Ant.  1 , the band pass filter  11 , and the low noise amplifier  13  constitute a first signal-receiving section, and the second receiving antenna Rx Ant.  2 , the band pass filter  12 , and the low noise amplifier  14  constitute a second signal-receiving section.  
         [0029]    A switching section  100  is connected between a down-converter  200  and the low noise amplifiers  13  and  14 . The switching section  100  receives a signal from the LNA  13 , which is transmitted through the first receiving path or the first signal-receiving section, and a signal from the LNA  14 , which is transmitted through the second receiving path or the second signal-receiving section.  
         [0030]    The down-converter  200  includes down-converter boards  210 ,  220 , and  230 , the number of which is one more than that of the receiving paths. The down-converter board  210  corresponds to the first receiving path Rx 1 , the down-converter board  220  corresponds to the second receiving path Rx 2 , and the down-converter board  230  is a redundancy board. Each of the down-converter boards  210 ,  220 , and  230  includes one divider and four converters for performing downward conversion for four FAs. For example, the down-converter  210  includes one divider  202  and four converters  211  to  214  for four FAs.  
         [0031]    That is, the switching section  100  receives the signals transmitted through the first and second receiving paths, and outputs the received signals to the boards of the down-converter  200  corresponding to the first and second receiving paths, respectively. During normal operation, the switching section  100  outputs the signal from the LNA  13 , which is transmitted through the first receiving path, to the down-converter board  210 , while outputting the signal from the LNA  14 , which is transmitted through the second receiving path, to the down-converter board  220 . However, when one of the down-converter boards is out of order (abnormal), the corresponding signal is transmitted to the redundant down-converter board  230  instead of the out-of-order board.  
         [0032]    Next, a construction of a transmitting path according to a preferred embodiment of the present invention will be described hereinafter with reference to FIG. 2.  
         [0033]    An up-converter  300  includes one up-converter board  310  and one redundant up-converter board  320 . When the up-converter board  310  is out of order, the redundant up-converter board  320  takes the place of the up-converter board  310 , thereby enabling the up-converter to continue normal operation. Each of the up-converter boards includes four converters for upwardly converting frequencies of signals, and one 4:1 combiner for combining output signals from the four converters and outputting the combined signal. For example, the up-converter board  310  includes four converters  311  to  314  and one 4:1 combiner  302 .  
         [0034]    A switching section  400  operates as a switch and is connected between the up-converter boards  310  and  320  and a divider  32 . In a normally operating state, the switching section  400  is so switched as to output a signal transmitted from the up-converter board  310  to the divider  32 . In contrast, when the up-converter board  310  is out of order, the switching section  400  is so switched as to output a signal transmitted from the up-converter board  320  to the divider  32 .  
         [0035]    The divider  32  divides the signal from the switching section  400  into four signals, so that the four signals can be inputted to four power amplifiers  33  to  36 , respectively. The power amplifiers  33  to  36  correspond to the four FAs, respectively. The combiner  37  combines signals outputted from the power amplifiers  33  to  36 , and outputs a combined signal. A band pass filter  38  band pass-filters the signal combined by the combiner  37  and outputs it through a transmitting antenna Tx Ant.  
         [0036]    [0036]FIG. 3 is a block diagram illustrating a construction of the down-converter  200  illustrated in FIG. 2 in more detail. Referring to FIG. 3, the down-converter  200  includes a first down-converter board  210 , a second down-converter board  220 , and a third or redundant down-converter board  230 . The switching section  100  is connected between the LNAs  13  and  14  and the down-converter boards  210 ,  220 , and  230 . The switching section  100  is switched to supply a signal received from the LNA  13  to the first down-converter board  210  or the redundant down-converter board  230 , and to supply a signal received from the LNA  14  to the second down-converter board  220  or the redundant down-converter board  230 . The construction and operation of the switching section  100  will be described later in more detail with reference to FIG. 5.  
         [0037]    The first down-converter board  210  includes a divider  202  and four converters  211  to  214 . The divider  202  divides a signal from the switching section  100  into four signals respectively for four FAs, and outputs the four signals. The first converter  211  is arranged for FA 1  and downwardly converts a frequency of a signal from the divider  202 . The second converter  212  is arranged for FA 2  and downwardly converts a frequency of a signal from the divider  202 . The third converter  213  is arranged for FA 3  and downwardly converts a frequency of a signal from the divider  202 . The fourth converter  214  is arranged for FA 4  and downwardly converts a frequency of a signal from the divider  202 .  
         [0038]    The second down-converter board  220  includes a divider  204  and four converters  221  to  224 . As in divider  202 , divider  204  divides a signal from the switching section  100  into four signals respectively for four FAs, and outputs the four signals. Again, the first converter  221  is arranged for FA 1  and downwardly converts a frequency of a signal from the divider  204 , the second converter  222  is arranged for FA 2  and downwardly converts a frequency of a signal from the divider  204 , the third converter  223  is arranged for FA 3  and downwardly converts a frequency of a signal from the divider  204 , and the fourth converter  224  is arranged for FA 4  and downwardly converts a frequency of a signal from the divider  204 .  
         [0039]    The third (or redundant) down-converter board  230  includes a divider  206  and four converters  231  to  234 , and operates in the same manner as the first and second down-converters  210  and  220 , described above.  
         [0040]    [0040]FIG. 4 is a block diagram illustrating a construction of the up-converter  300  illustrated in FIG. 2 in more detail. Referring to FIG. 4, the up-converter  300  includes an up-converter board  310  and a redundant up-converter board  320 . The switching section  400  is connected between the up-converter boards  310  and  320  and the divider  32 . The switching section  400  is switched to supply a signal that has been upwardly converted by one of the up-converter boards  310  and  320  to the divider  32 . When the up-converter  310  normally operates, the switching section  400  is switched to supply the signal from the up-converter board  310  to the divider  32 . When the up-converter board  310  does not normally operate, the switching section  400  is switched to supply the signal from the redundant up-converter board  320  to the divider  32 . The construction and operation of the switching section  400  will be described later in more detail with reference to FIG. 6.  
         [0041]    The up-converter board  310  includes converters  311  to  314  for upwardly converting transmission signals for four FAs, respectively, and a combiner  302  for combining output signals of the converters  311  to  314  and outputting a combined signal. The converter  311  is arranged for upwardly converting a transmitting signal for FA 1 , the converter  312  is arranged for upwardly converting a transmitting signal for FA 2 , the converter  313  is arranged for upwardly converting a transmitting signal for FA 3 , and the converter  314  is arranged for upwardly converting a transmitting signal for FA 4 .  
         [0042]    The redundant up-converter board  320  includes converters  321  to  324  for upwardly converting transmission signals for four FAs, respectively, and a combiner  304  for combining output signals of the converters  321  to  324  and outputting a combined signal. The converter  321  is arranged for upwardly converting a transmitting signal for FA 1 , the converter  322  is arranged for upwardly converting a transmitting signal for FA 2 , the converter  323  is arranged for upwardly converting a transmitting signal for FA 3 , and the converter  324  is arranged for upwardly converting a transmitting signal for FA 4 .  
         [0043]    [0043]FIG. 5 is a diagram illustrating in more detail the switching control operation on the receiving paths of the base station system according to the preferred embodiment of the present invention. Referring to FIG. 5, a first switch  110 , a second switch  120 , and an OR gate  130  are elements constituting the switching section  100 . The switches  110  and  120  are Single-Pole Double-Throw (SPDT) switches, each of which has one input terminal and two output terminals. An input terminal of the first switch  110  is connected with an output terminal of the LNA  13 . A first output terminal L of the first switch  110  is connected with an input terminal of the divider  202 , which is an input terminal of the down-converter board  210 . A second output terminal H of the first switch  110  is connected with an input terminal of the divider  206 , which is an input terminal of the redundant down-converter board  230 . A first output terminal L of the second switch  120  is connected with an input terminal of the divider  204 , which is an input terminal of the down-converter board  220 . A second output terminal H of the second switch  120  is connected with an input terminal of the divider  206 , which is an input terminal of the redundant down-converter board  230 .  
         [0044]    The operations of the first and second switches  110  and  120  are controlled by diagnostic monitoring (DM) signals for the down-converter boards  210  and  220 , respectively. The DM signal is a signal for diagnosing the state of each board, and has different levels according to whether a corresponding board is normal or abnormal. As an example of generating a DM signal for each board and performing a process according to the generated DM signal, lighting of light-emitting diodes provided at a front panel of the base station system may be controlled according to DM signals generated from corresponding boards. Such generation of and process according to the generation of a DM signal is well known to those related in the art, so detailed description about that will be omitted here.  
         [0045]    In response to a DM signal of “L” level that represents that the down-converter board  210  is normal, the input terminal and the first output terminal L of the first switch  110  are connected with each other. Then, a receiving path is formed between the LNA  13  and the down-converter board  210 . In response to a DM signal of “H” level that represents that the down-converter board  210  is abnormal, the input terminal and the second output terminal H of the first switch  110  are connected with each other. Then, a receiving path is formed between the LNA  13  and the redundant down-converter board  230 . In response to a DM signal of “L” level that represents that the down-converter board  220  is normal, the input terminal and the first output terminal L of the second switch  120  are connected with each other. Then, a receiving path is formed between the LNA  14  and the down-converter board  220 . In response to a DM signal of “H” level that represents that the down-converter board  220  is abnormal, the input terminal and the second output terminal H of the second switch  120  are connected with each other. Then, a receiving path is formed between the LNA  14  and the redundant down-converter board  230 .  
         [0046]    The OR gate  130  includes a first input terminal, a second input terminal, and an output terminal. A DM signal for the down-converter  210  can be inputted through the first input terminal of the OR gate  130 , and a DM signal for the down-converter  220  can be inputted through the second input terminal of the OR gate  130 . When a DM signal of “H” level which represents that at least one of the down-converter boards  210  and  220  is abnormal is applied, the OR gate  130  outputs an enable signal of “H” level, thereby activating the redundant down-converter board  230 . That is, when it is diagnosed that at least one of the down-converter boards  210  and  220  is abnormal, the OR gate  130  enables the redundant down-converter board  230  to take the place of the abnormal board.  
         [0047]    A switching section  240  is connected between a channel card (not shown) and the down-converter board and redundant down-converter board  210  and  230 , and a switching section  250  is connected between a channel card (not shown) and the down-converter board and redundant down-converter board  220  and  230 . In this case, the channel card is a known element of a base station provided with a plurality of channels, which performs modulation and demodulation of signals of each channel. Therefore, a detailed description about the channel card will be omitted here.  
         [0048]    Each of the switching sections  240  and  250  includes Double-Pole Single-Throw (DPST) switches, each of which has two input terminals and one output terminal. Input terminals of the DPST switches of the switching sections  240  and  250  are connected with output terminals of corresponding FAs of the down-converter board  210  and redundant down-converter board  230 , and output terminals of the DPST switches of the switching sections  240  and  250  are connected with the channel cards. The switching operations of the DPST switches of the switching sections  240  and  250  are controlled by the DM signals for the down-converter boards  210  and  220 , respectively.  
         [0049]    In response to a DM signal of “L” level, which represents that the down-converter board  210  is normal, a first input terminal and an output terminal of each DPST switch of the switching section  240  are connected with each other. Then, a receiving path is formed between the down-converter board  210  and the channel card. In response to a DM signal of “H” level, which represents that the down-converter board  210  is abnormal, a second input terminal and the output terminal of each DPST switch of the switching section  240  are connected with each other. Then, a receiving path is formed between the redundant down-converter board  230  and the channel card. In response to a DM signal of “L” level, which represents that the down-converter board  220  is normal, a first input terminal and an output terminal of each DPST switch of the switching section  250  are connected with each other. Then, a receiving path is formed between the down-converter board  220  and the channel card. In response to a DM signal of “H” level, which represents that the down-converter board  220  is abnormal, a second input terminal and the output terminal of each DPST switch of the switching section  250  are connected with each other. Then, a receiving path is formed between the redundant down-converter board  230  and the channel card.  
         [0050]    [0050]FIG. 6 is a diagram illustrating in more detail the switching control operation on the transmitting paths of the base station system according to the preferred embodiment of the present invention. Referring to FIG. 6, a switching section  410  is connected between a channel card (not shown) and the up-converter board  310  and redundant up-converter board  320 . The switching section  410  includes SPDT switches, each of which has one input terminal and two output terminals, and the number of which corresponds to the number of FAs. Input terminals of the SPDT switches of the switching section  410  are connected with the channel card, and output terminals of the SPDT switches of the switching section  410  are connected with output terminals of corresponding FAs of the up-converter board  310  and the redundant up-converter board  320 . The switching operation of each SPDT switch of the switching section  410  is controlled by DM signals for the up-converter board  310 . The redundant up-converter board  320  is controlled by DM signals, which represent whether the up-converter board  310  is normal or not. In other words, the redundant up-converter board  320  is activated in response to a DM signal of “H” level, which represents that the up-converter board  310  is abnormal. The DM signal of “H” level is an enable signal for activating the redundant up-converter board  320 .  
         [0051]    In response to a DM signal of “L” level, which represents that the up-converter board  310  is normal, an input terminal and a first output terminal of each SPDT switch of the switching section  410  are connected with each other. Then, a transmitting path is formed between the channel card and a corresponding FA of the up-converter board  310 . In response to a DM signal of “H” level, which represents that the up-converter board  310  is abnormal, an input terminal and a second output terminal of each SPDT switch of the switching section  410  are connected with each other. Then, a transmitting path is formed between the channel card and a corresponding FA of the up-converter board  320 .  
         [0052]    The switching section  400  is connected between the up-converter board  310  and the redundant up-converter board  320  and the divider  32  connected to the power amplifiers  33  to  36 . The switching section  400  is realized as a DPST switch including two input terminals and one output terminal. A first input terminal of the switching section  400  is connected with an output terminal of the combiner  302  of the up-converter board  310 , and a second input terminal of the switching section  400  is connected with an output terminal of the combiner  304  of the up-converter board  320 .  
         [0053]    The switching operation of the switching section  400  is controlled by DM signals for the up-converter board  310 . In response to the DM signal of “L” level, which represents that the up-converter board  310  is normal, a first input terminal L and an output terminal of the switching section  400  are connected with each other. Then, a transmitting path is formed between the up-converter board  310  and the power amplifiers  33  to  36 . In response to the DM signal of “H” level, which represents that the up-converter board  310  is abnormal, a second input terminal H and the output terminal of the switching section  400  are connected with each other. Then, a transmitting path is formed between the redundant up-converter board  320  and the power amplifiers  33  to  36 .  
         [0054]    As described above, on the two receiving paths of the base station, signals received by two receiving antennas transmitted through the band pass filters  11  and  12 , and the LNAs  13  and  14 , to the 2:3 switching section  100  connected to the three down-converter boards (including one redundant down-converter board)  210 ,  220 , and  230 . In each of the down-converter boards  210 ,  220 , and  230 , the 1:4 divider divides the received signals according to the FAs.  
         [0055]    In the meantime, on the transmitting path of the base station, signals are sent from the two up-converter boards (including one redundant up-converter board)  310  and  320  to the 2:1 switching section  400 . In this case, in each of the up-converter boards, the 4:1 combiner combines the transmitted signals for FAs and outputs a combined signal. The combined signal transmitted in the hard-redundancy mode is transmitted through the 1:4 divider  32 , and then the divided signals are amplified by the linear amplifiers  33  to  36  of the soft-redundancy mode utilizing load sharing. Then, they are combined by the 4:1 combiner  37 , and the combined signal is transmitted through the band pass filter  38  and the antenna. This construction enables the base station to perform a seamless normal operation even when any board in the transmitting and receiving paths is abnormal.  
         [0056]    As described above, the base station of the mobile communication system according to the preferred embodiment of the present invention has a simple mechanical construction and provides effective communication service. In the base station according to the present invention, even when one of the boards goes out of order and cuts off the call, thereby having a bad influence on the entire capacity of the system, a redundant board is automatically switched on and operated normally, so that the base station according to the present invention is more efficiently maintained in comparison with the conventional base station.  
         [0057]    Referring to the prior art illustrated in FIG. 1, the up/down-converter  20  is divided according to FAs without a separate redundant board. Therefore, not only that one FA cannot be used when a board is abnormal, but also every FA has a bad performance even when every other FA operates normally, because two receiving paths and one transmitting path are mixed in each FA. The present invention not only overcomes this problem, but also much simplifies the mechanical construction of the system by installing a divider or combiner in each down- or up-converter board.  
         [0058]    While the invention has been shown and described with reference to a certain preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein. For example, although the above-mentioned preferred embodiment is an example employed in a base station system designed to support multi-sector/multi-FA, the present invention can be employed in a base system supporting one sector/one FA, not multi-sector/multi-FA. That is, the above-described operation according to the present invention can be also applied to a base station system having a down- or up-converter including down- or up-converter boards and a redundant down- or up-converter board, the number of which corresponds to the number of receiving or transmitting paths. Therefore, the scope of the invention should not be limited by the described embodiment, but should be defined by the appended claims and equivalents thereof.