Abstract:
A sector-based base station includes at least one of a shared transmission RF local oscillator TX_LO, a shared receiving RF local oscillator RX_LO, a shared digital signal processing unit, and a shared transmission feedback unit. A technical solution of sharing an intermediate RF unit circuit in the sector-based base station is adopted, so as to reduce the number of elements used in the circuit without sacrificing the communication capacity of the base station. As such, the reliability index of a single board is improved, and the system reliability is also enhanced. Meanwhile, the material cost and the time required for debugging are both reduced; thus, lowering the cost of the base station.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Patent Application No. PCT/CN2008/070975, filed May 15, 2008, which claims priority to Chinese Patent Application No. 200710099398.9, filed May 18, 2007, both of which are hereby incorporated by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to the field of electronic communication technology, and, more particularly, to a sector-based base station. 
       BACKGROUND OF THE INVENTION 
       [0003]    Currently, the mobile communication technology has been widely used in various aspects of daily life and work. Mobile communication is defined as a kind of communication in which the information is transmitted while at least one or both parties in communication are in a mobile state. The two parties in a mobile communication are a base station and a terminal. 
         [0004]    A base station, as a form of the radio station, is a radio transceiver station for transmitting information with mobile phone terminals through a mobile switching center in a particular radio coverage area. A base station is mainly constituted by a transceiver, a clock unit, and a baseband processing unit. The transceiver includes an intermediate radio frequency (RF) unit adapted to perform conversion between a baseband signal and a RF signal. After receiving a RF signal from a terminal, the base station converts the received RF signal into a baseband signal through the RF unit of the transceiver, and converts a baseband signal to be sent into a RF signal and sends the RF signal. 
         [0005]    The networking modes of different base stations may employ different solutions about the intermediate RF units, and generally the following two solutions are adopted. 
         [0006]    First, an omni-directional base station is implemented by a concentric circle mode. That is, the electric wave coverage of a single sector (i.e. one circle) is achieved through a single base station. The whole base station only has one set of intermediate RF unit, so the communication capacity of the base station is rather small. 
         [0007]    Secondly, in order to increase the communication capacity of the base station, a multi-sector base station is implemented by a cellular networking mode. That is, one base station covers multiple sectors (as shown in  FIG. 1 , one base station covers  3  sectors marked with F 1 ). Generally, several sets of antennas pointing to different directions are adapted to form several mobile communication sectors. Each sector is corresponding to a different intermediate RF unit, and the intermediate RF units are independent from each other. 
         [0008]      FIG. 2  is a structural block diagram of an intermediate RF unit in an omni-directional base station, which aims at illustrating the processing of receiving signals and transmitting signals by the intermediate RF unit in the base station. In the structural block diagram shown in  FIG. 2 , the intermediate RF unit is in a typical form with two inputs and one output (i.e., two receiving units plus one transmitting unit). Currently, the specific implementation modes of the intermediate RF unit also include one input and one output (i.e., one receiving unit plus one transmitting unit) and multiple-input multiple-output (MIMO) (i.e., multiple receiving units plus multiple transmitting units). It is understandable that, the signal processing carried out by each unit is similar to that in the typical two-input one-output form of  FIG. 2 , so that the signal processing carried out by the intermediate RF unit in the typical two-input one-output form will be illustrated in detail below. 
         [0009]    The intermediate RF unit processes a receiving master signal from a transmitting/receiving antenna through a RF signal receiving unit built therein. The detailed process includes the following steps. First, the receiving master signal from the transmitting/receiving antenna is isolated and filtered from a transmitting signal by a filter unit (for example, a duplexer filter (DUP) in  FIG. 2 ). Next, the signal is amplified by an amplifier unit (for example, a low noise amplifier (LNA) in  FIG. 2 ) and filtered by a filter unit (for example, a RF filter in  FIG. 2 ) and processed by a mixer unit (for example, a mixer in  FIG. 2 ) to obtain a lower frequency, and then the signal is further amplified by an amplifier unit (for example, an amplifier (AMP) in  FIG. 2 ), and filtered by a filter unit (for example, an intermediate frequency filter in  FIG. 2 ). Afterwards, an analog-to-digital conversion is performed on the signal by an analog-to-digital converter unit (for example, an analog-to-digital converter (ADC) in  FIG. 2 ), and then a digital signal processing is performed on the signal in a digital signal processing unit including a digital signal processor (DSP) &amp; field-programmable gate array (FPGA). Finally, the signal is sent out for the baseband signal processing. 
         [0010]    The intermediate RF unit processes a receiving diversity signal obtained from a diversity antenna through the RF signal receiving unit built therein. The detailed process includes the following steps. First, the receiving diversity signal is processed by a filter unit (for example, a receiving filter (RX Filter) in  FIG. 2 ), and then the subsequent processing is similar to that of the receiving master signal. 
         [0011]    The intermediate RF unit processes a transmitting baseband signal through a RF signal transmitting unit built therein. The detailed process includes the following steps. First, the transmitting baseband signal is processed by a digital signal processing unit including a DSP &amp; FPGA, and then sent to a digital-to-analog converter unit (for example, a digital-to-analog converter (DAC) in  FIG. 2 ) to finish a digital-to-analog conversion. Afterwards, the signal is modulated by a modulation unit (for example, a modulator (MOD) in  FIG. 2 ) to a RF frequency. Then, the signal is amplified by an amplifier unit (for example, the AMP in  FIG. 2 ), and then, the power of the signal is amplified by a power amplifier unit (for example, a power amplifier (PA) in  FIG. 2 ). Finally, the signal is transmitted to a filter unit (for example, the DUP in  FIG. 2 ), and sent out by an antenna (ANT). 
         [0012]    The intermediate RF unit processes a transmitting feedback signal through a transmission feedback unit built therein. The detailed process includes the following steps. First, a part of the power of the transmitting signal is coupled by a coupler and down-converted into a lower frequency by a mixer unit (for example, the mixer in  FIG. 2 ). Then, the signal is processed by an amplifier unit (for example, the AMP in  FIG. 2 ) and a filter unit (for example, the filter in  FIG. 2 ) and then sent to an analog-to-digital converter unit. Finally, the signal is sent to a digital signal processing unit, including a DSP &amp; FPGA to be processed, so as to serve as a feedback input of a power-amplification digital predistortion signal. The power-amplification digital predistortion technology is a way of improving the power amplification linearity. 
         [0013]    In a multi-sector base station implemented in a cellular networking mode, the base station generally covers two or more than two sectors, each sector employs an independent intermediate RF unit, and each intermediate RF unit is designed in a different module. The intermediate RF unit in each sector includes all the parts of the intermediate RF unit in the omni-directional base station of  FIG. 2 . In the multi-sector base station, the intermediate RF unit of each sector works independently. 
         [0014]    During the research, the inventor found that, in the multi-sector base station, each sector has an intermediate RF unit, and the intermediate RF unit of each sector is independent from each other. As a result, the circuit design is rather complicated. Moreover, as the circuit unit has a poor adaptability, the cost is rather high. 
         [0015]    Therefore, until now, there is no sector-based base station with a simpler circuit design and a lower cost. 
       SUMMARY OF THE INVENTION 
       [0016]    Accordingly, in an embodiment, the present invention is directed to a sector-based base station, which is capable of sharing an intermediate radio frequency (RF) unit among different sectors. 
         [0017]    The embodiment of the present invention is implemented in the following technical solution. 
         [0018]    In an embodiment of the present invention, a sector-based base station including at least two sets of RF signal transmitting units and RF signal receiving units is provided. Each of the RF signal transmitting units is provided with a modulation unit or a mixer unit and a digital-to-analog converter unit. Each of the RF signal receiving units is provided with a mixer unit and an analog-to-digital converter unit. The base station includes at least one of a shared transmission RF local oscillator TX_LO, a shared receiving RF local oscillator RX_LO, a shared digital signal processing unit, and a shared transmission feedback unit. 
         [0019]    The shared TX_LO is connected to the modulation unit or the mixer unit in each of the RF signal transmitting units, and serves as a transmission RF local oscillator for all sectors in the base station. 
         [0020]    The shared RX_LO is connected to the mixer unit in each of the RF signal receiving units, and serves as a receiving RF local oscillator for all the sectors in the base station. 
         [0021]    The shared digital signal processing unit is connected to the digital-to-analog converter unit and/or the analog-to-digital converter unit, and adapted to process digital signals of all the sectors in the base station. 
         [0022]    The shared transmission feedback unit is connected to the RF signal transmitting unit that requires a transmission feedback, and adapted to perform a feedback processing on transmitting signals of all the sectors in the base station. 
         [0023]    As seen from the above embodiment of the present invention, the technical solution of sharing the intermediate RF unit circuit in the sector-based base station is adopted to reduce the number of elements used in the circuit while ensuring the communication capacity of the base station. As such, the reliability index of a single board is improved, and the system reliability is also enhanced. Meanwhile, the material cost and the time required for debugging are both reduced; thus, lowering the cost of the base station. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The present invention will become more fully understood from the detailed description given herein below for illustration only, which thus is not limitative to the present invention. 
           [0025]      FIG. 1  is a schematic view of a cellular networking sector coverage; 
           [0026]      FIG. 2  is a structural block diagram of an intermediate RF unit of an omni-directional base station; 
           [0027]      FIG. 3  is a structural view of an intermediate RF unit, according to an embodiment of the present invention; and 
           [0028]      FIG. 4  is a structural view of an intermediate RF unit in a 3-sector base station, according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0029]    In the embodiment of the present invention, through the design of sharing an intermediate RF unit in the sector-based base station, an intermediate RF circuit for a multi-sector base station is configured in one module, so as to achieve a large communication capacity with a low cost. When the base station covers N (N≧2) sectors, the intermediate RF unit includes N sets of RF signal transmitting units and RF signal receiving units. Each of the RF signal transmitting units is provided with a modulation unit or a mixer unit and a digital-to-analog converter unit. Each of the RF signal receiving units is provided with a mixer unit and an analog-to-digital converter unit. 
         [0030]    The design of sharing an intermediate RF unit includes at least one of the following circumstances: completely or partially sharing the transmission feedback unit of each sector, sharing the transmission RF local oscillator of each sector, sharing the receiving RF local oscillator of each sector, and sharing the digital signal processing unit (for example, DSP &amp; FPGA, or other digital signal processing elements) of each sector. In particular, the following four sharing circumstances are included. 
         [0031]    Circumstance 1: sharing the transmission feedback unit, the transmission RF local oscillator, the receiving RF local oscillator, and the digital signal processing unit of each sector; 
         [0032]    Circumstance 2: sharing one unit selected from the transmission feedback unit, the transmission RF local oscillator, the receiving RF local oscillator, and the digital signal processing unit of each sector; 
         [0033]    Circumstance 3: sharing any two units selected from the transmission feedback unit, the transmission RF local oscillator, the receiving RF local oscillator, and the digital signal processing unit of each sector; and 
         [0034]    Circumstance 4: sharing any three units selected from the transmission feedback unit, the transmission RF local oscillator, the receiving RF local oscillator, and the digital signal processing unit of each sector. 
         [0035]    The above units after being shared may respectively serve as a shared transmission feedback unit, a shared transmission RF local oscillator, a shared receiving RF local oscillator, and a shared digital signal processing unit. 
         [0036]    Moreover, in the above four circumstances, if the transmission feedback unit of each sector is shared, the following circumstances may exist. 
         [0037]    Circumstance 1: sharing the mixer unit, a feedback RF local oscillator, an amplifier unit, a filter unit, and an analog-to-digital converter unit in the transmission feedback unit of each sector; 
         [0038]    Circumstance 2: sharing one unit selected from the mixer unit, the feedback RF local oscillator, the amplifier unit, the filter unit, and the analog-to-digital converter unit in the transmission feedback unit of each sector; 
         [0039]    Circumstance 3: sharing any two units selected from the mixer unit, the feedback RF local oscillator, the amplifier unit, the filter unit, and the analog-to-digital converter unit in the transmission feedback unit of each sector; 
         [0040]    Circumstance 4: sharing any three units selected from the mixer unit, the feedback RF local oscillator, the amplifier unit, the filter unit, and the analog-to-digital converter unit in the transmission feedback unit of each sector; and 
         [0041]    Circumstance 5: sharing any four units selected from the mixer unit, the feedback RF local oscillator, the amplifier unit, the filter unit, and the analog-to-digital converter unit in the transmission feedback unit of each sector. 
         [0042]    Circumstances 2 to 5 illustrate the situations of partially sharing the transmission feedback unit. It is understandable that, when the mixer unit is shared, the feedback RF local oscillator is also shared. However, when the feedback RF local oscillator shared is shared, the mixer unit may be shared or may not be shared. Moreover, when any of the mixer unit, the feedback RF local oscillator, the amplifier unit, the filter unit, and the analog-to-digital converter unit in the transmission feedback unit is shared, the above units may be completely or partially shared. For example, when the base station covers N (N≧3) sectors, if the amplifier units are shared, the amplifier units may be completely shared, i.e. the transmission feedback unit only has one shared amplifier unit without any amplifier unit, or the amplifier units may be partially shared, i.e. the transmission feedback unit has n shared amplifier units and m amplifier units, i.e. 1&lt;(n+m)≦(N−1). 
         [0043]    The above units after being shared may respectively serve as a shared mixer unit, a shared feedback RF local oscillator, a shared amplifier unit, a shared filter unit, and a shared analog-to-digital converter unit. 
         [0044]      FIG. 3  is a structural view of an intermediate RF unit, according to a first embodiment of the present invention. 
         [0045]    The intermediate RF unit includes at least one of a shared transmission RF local oscillator TX_LO, a shared receiving RF local oscillator RX_LO, a shared digital signal processing unit, and a shared transmission feedback unit. That is, in this embodiment of the present invention, the intermediate RF unit may include the shared transmission RF local oscillator TX_LO, the shared receiving RF local oscillator RX_LO, the shared digital signal processing unit, and the shared transmission feedback unit; or one unit selected from the shared transmission RF local oscillator TX_LO, the shared receiving RF local oscillator RX_LO, the shared digital signal processing unit, and the shared transmission feedback unit; or any two units selected from the shared transmission RF local oscillator TX_LO, the shared receiving RF local oscillator RX_LO, the shared digital signal processing unit, and the shared transmission feedback unit; or any three units selected from the shared transmission RF local oscillator TX_LO, the shared receiving RF local oscillator RX_LO, the shared digital signal processing unit, and the shared transmission feedback unit. 
         [0046]    The shared TX_LO is connected to the modulation unit in each RF signal transmitting unit (for example, the RF signal transmitting units  1  to N in  FIG. 3 ), and serves as a transmission RF local oscillator for all the sectors in the base station. The modulation unit is adapted to perform a quadrature modulation on signals. If the quadrature modulation portion of the modulation unit is disposed in the shared digital signal processing unit, the modulation unit is substituted by the mixer unit in each RF signal transmitting unit. In this case, the shared TX_LO is connected to the mixer unit in each RF signal transmitting unit, and serves as a transmission RF local oscillator for all the sectors in the base station. 
         [0047]    The shared RX_LO is connected to the mixer unit in each RF signal receiving unit (for example, the RF signal receiving units  1  to N in  FIG. 3 ), and serves as a receiving RF local oscillator for all the sectors in the base station. 
         [0048]    The shared digital signal processing unit is connected to the digital-to-analog converter unit and/or the analog-to-digital converter unit, and is adapted to process digital signals of all the sectors in the base station. 
         [0049]    The shared transmission feedback unit is connected to the RF signal transmitting unit that requires a transmission feedback in each sector, so as to perform a feedback processing on the transmitting signals of all the sectors in the base station, in which the connection process may be implemented through, for example, a coupling manner. 
         [0050]    In addition to the shared transmission feedback unit, the base station further includes a switch. 
         [0051]    The switch is connected to the shared transmission feedback unit and the RF signal transmitting unit that requires a transmission feedback, and may be a single-pole multi-throw switch or other switches with selective functions. 
         [0052]    When the shared transmission feedback unit is partially shared, the shared transmission feedback unit specifically includes at least one of a shared mixer unit, a shared feedback RF local oscillator TXF_LO, a shared amplifier unit, a shared filter unit, and a shared analog-to-digital converter unit. That is, in this embodiment of the present invention, the shared transmission feedback unit may include the shared mixer unit, the shared feedback RF local oscillator TXF_LO, the shared amplifier unit, the shared filter unit, and the shared analog-to-digital converter unit; or one unit selected from the shared mixer unit, the shared feedback RF local oscillator TXF_LO, the shared amplifier unit, the shared filter unit, and the shared analog-to-digital converter unit; or any two units selected from the shared mixer unit, the shared feedback RF local oscillator TXF_LO, the shared amplifier unit, the shared filter unit, and the shared analog-to-digital converter unit; or any three units selected from the shared mixer unit, the shared feedback RF local oscillator TXF_LO, the shared amplifier unit, the shared filter unit, and the shared analog-to-digital converter unit; or any four units selected from the shared mixer unit, the shared feedback RF local oscillator TXF_LO, the shared amplifier unit, the shared filter unit, and the shared analog-to-digital converter unit. Moreover, in any of the above circumstances, the shared transmission feedback unit may include at least one of a mixer unit, a feedback RF local oscillator TXF_LO, an amplifier unit, a filter unit, and an analog-to-digital converter unit. 
         [0053]    The shared mixer unit is connected to the amplifier unit and/or the shared amplifier unit in the shared transmission feedback unit, and is adapted to perform a mixing processing on all feedback signals during a feedback processing on the transmitting signals of all the sectors in the base station. 
         [0054]    The shared TXF_LO is connected to the mixer unit and/or the shared mixer unit in the shared transmission feedback unit, and serves as a feedback RF local oscillator for all the feedback signals during the feedback processing on the transmitting signals of all the sectors in the base station. 
         [0055]    The shared amplifier unit is connected to the mixer unit and/or the shared mixer unit in the shared transmission feedback unit and the filter unit or the shared filter unit in the shared transmission feedback unit, and is adapted to perform an amplification processing on all the feedback signals during the feedback processing on the transmitting signals of all the sectors in the base station. 
         [0056]    The shared filter unit is connected to the amplifier unit and/or the shared amplifier unit in the shared transmission feedback unit and the analog-to-digital converter unit or the shared analog-to-digital converter unit in the shared transmission feedback unit, and is adapted to perform a filter processing on all the feedback signals during the feedback processing on the transmitting signals of all the sectors in the base station. 
         [0057]    The shared analog-to-digital converter unit is connected to the filter unit and/or the shared filter unit in the shared transmission feedback unit and the shared digital signal processing unit and/or the DSP, and is adapted to perform an analog-to-digital conversion processing on all the feedback signals during the feedback processing on the transmitting signals of all the sectors in the base station. 
         [0058]    When the shared transmission feedback unit is completely shared, the switch is located between the RF signal transmitting unit and the shared transmission feedback unit. When the shared transmission feedback unit is partially shared, the switch is used to connect the RF signal transmitting unit to the shared units in the shared transmission feedback unit. That is, depending upon different circumstances of the shared units, one or more switches are required (for example, if only the shared amplifier unit exists, two sets of switches are required, one is used to connect the RF signal transmitting unit to the shared amplifier unit, and the other is disposed between the shared amplifier unit and the filter unit, so as to connect the shared amplifier unit to the filter unit in the shared transmission feedback unit). 
         [0059]    A 3-sector base station is taken as a second embodiment below to demonstrate the specific implementation of the device of the present invention. 
         [0060]      FIG. 4  is a structural view of an intermediate RF unit in a 3-sector base station, according to an embodiment of the present invention. The structural view of  FIG. 4  includes the following circumstances of sharing the transmission feedback unit of each sector, sharing the RF local oscillator of each sector, and sharing the DSP &amp; FPGA in the intermediate frequency signal processing portion of each sector. In particular, the shared intermediate RF unit includes a transmission feedback unit, two RF local oscillators, a DSP &amp; FPGA processing portion, three receiving master channels, three receiving diversity channels, and three transmitting channels. 
         [0061]    The transmission feedback unit is adapted to realize a function of sharing the transmission feedback unit of each sector. Generally, the function of transmission feedback unit is to provide a feedback input of digital predistortion, and the total power of transmitting signals of each sector is relatively stable. However, after the feedback input disappears, the intermediate frequency signal processing portion still maintains an original state. Therefore, a single-pole three-throw switch can be adopted to take turns to select a power-amplification feedback signal of each sector at different time divisions. In this manner, the three transmission feedback units in the 3-sector base station can be integrated into one unit to share the whole transmission feedback unit among multiple sectors, so that the number of the RF local oscillators TXF_LO in the feedback unit is reduced to one. 
         [0062]    The two RF local oscillators include a shared TX_LO adapted to serve as the transmission RF local oscillator of each sector and a shared RX_LO adapted to serve as the receiving RF local oscillator of each sector. That is, the RF signal receiving units and the RF signal transmitting units, respectively, adopt one local oscillator. Therefore, as for a base station covering N sectors, the number of the receiving/transmission RF local oscillators can be reduced by 2(N−1). 
         [0063]    The DSP &amp; FPGA processing portion is adapted to share the DSP &amp; FPGA in the digital signal processing portion of each sector, so as to form the DSP &amp; FPGA in the intermediate frequency signal processing portion into a resource pool for sharing. 
         [0064]    The three receiving master channels are adapted to receive master signals. 
         [0065]    The three receiving diversity channels are adapted to receive diversity signals. 
         [0066]    The three transmitting channels are adapted to transmit baseband signals. 
         [0067]    The third embodiment of the present invention is an improvement on the basis of the second embodiment of the present invention. That is, the sharing of a transmission feedback channel of each sector is set as the partial sharing of the transmission feedback channel of each sector, while the sharing of the RF local oscillators of each sector and the sharing of the DSP &amp; FPGA in the intermediate frequency signal processing portion of each sector remain unchanged. 
         [0068]    The partial sharing of the transmission feedback channel of each sector is implemented as follows. The single-pole three-throw switch in the feedback channel of the second embodiment of the present invention is moved backwards. Thus, only the part of the circuit behind the switch can be shared, and the part in front of the switch cannot be shared. In this case, three groups of circuits are still needed before the switch. For example, if the single-pole three-throw switch is disposed between the AMP and Filter, three groups of the Mixer, TXF_LO, and AMP circuits and one group of the Filter and ADC circuits are required. 
         [0069]    In the second embodiment of the present invention, the receiving and transmission of RF signals and baseband signals implemented by the intermediate RF unit in the sector-based base station are described below. 
         [0070]    The intermediate RF unit processes a receiving master signal from the transmitting/receiving antenna in the following manner. First, the receiving master signal from the transmitting/receiving antenna is isolated from a transmitting signal by a DUP, and then amplified by a LNA, filtered by a Filter, and processed by a Mixer to obtain a lower frequency. Afterwards, the signal is again amplified by an AMP, filtered by a Filter, and processed through an analog-to-digital conversion by an ADC. Finally, the signal finishes the digital signal processing in a DSP &amp; FPGA, and then sent out for a baseband signal processing. During the above process, the three receiving master signals share the same RX_LO when being processed by the Mixer to obtain a lower frequency, respectively, and share the same DSP &amp; FPGA during the DSP &amp; FPGA processing. 
         [0071]    The intermediate RF unit processes a receiving diversity signal from the diversity antenna in the following manner. First, the receiving diversity signal first passes through a RX Filter, and the subsequent processing thereof is similar to that of the receiving master signal. During the above process, the three receiving diversity signals share the same RX_LO when being processed by the Mixer to obtain a lower frequency, and share the same DSP &amp; FPGA during the DSP &amp; FPGA processing. 
         [0072]    The intermediate RF unit processes a transmitting baseband signal in the following manner. First, the transmitting baseband signal is processed by the DSP &amp; FPGA, then sent to a DAC for digital-to-analog conversion, and then modulated by a MOD into a RF frequency. Afterwards, the signal is amplified by an AMP, and the power thereof is amplified by a PA. Finally, the signal is sent to a DUP and transmitted by an ANT. During the above process, the three baseband signals share the same DSP &amp; FPGA during the digital signal processing, and share the same TX_LO when being modulated by the MOD, respectively. 
         [0073]    The intermediate RF unit processes a transmitting feedback signal in the following manner. First, a part of the power of the transmitting signal is coupled by a Coupler and down-converted into a lower frequency by a Mixer. Then, the signal is processed by the AMP and Filter and then sent to an analog-to-digital converter unit, and is finally sent to a DSP &amp; FPGA to be processed, so as to serve as a feedback input of a power-amplification digital predistortion signal. The power-amplification digital predistortion technology is a way of improving the power amplification linearity. During the processing of the transmission feedback signal, the single-pole three-throw switch is set at the current position to achieve the feedback of the transmitting channel  1 , and similarly, the single-pole three-throw switch can be moved leftwards by one or two channels to achieve the feedback of the transmitting channel  2  or  3 , respectively. 
         [0074]    Likewise, if the multi-sector base station covers N sectors (N is a natural number), the embodiment of the present invention can be adopted to achieve the sharing of the intermediate RF unit in the base station. That is, as for the base station covering N sectors, in a desired circumstance, (N−1) feedback channels, (N−1) DSP &amp; FPGA processing portions, and 2(N−1) receiving/transmission RF local oscillators can be saved. 
         [0075]    It is understandable that, the intermediate RF units in different base stations have different structures, which may result in variations of the processing of transmitting and receiving signals by the intermediate RF units. However, the method of sharing at least one selected from the RX_LO, the TX_LO, the digital signal processing unit, and the transmission feedback unit in the embodiment of the present invention still can be adopted to process the signals. Moreover, the shared transmission feedback unit can be partially shared. 
         [0076]    It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.