Patent Publication Number: US-9414436-B2

Title: Radio communication apparatus, radio communication system and radio communication method

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 12/621,968, filed Nov. 19, 2009, which is a continuation of International Application No. PCT/JP2007/000565, filed on May 25, 2007, now pending, both of which are herein incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a radio communication apparatus, a radio communication system and a radio communication method. 
     BACKGROUND ART 
     In the field of radio communications, communication systems using new communication formats are being constructed and radio services are being provided accompanying advances in technology. At that time, since normally numerous users do not switch to a new radio service immediately, but rather switch gradually, multiple radio services are implemented in parallel. In addition, when constructing new communication formats, although this involves the introduction of new, dedicated equipment to accommodate those formats, since existing services are still being implemented, it is necessary to secure locations for installing the dedicated equipment that is compatible with the new communication format. 
       FIG. 10  is a drawing depicting an example of the configuration of a radio base station (BTS)  200  of the prior art (see, for example, Non-Patent Document 1). The radio base station  200  is provided with a radio equipment (RE)  220  which performs out processing on radio signals such as filtering, modulation and frequency conversion, and a radio equipment controller (REC)  210  which performs processing on baseband signals. The radio equipment  220  and the radio equipment controller  210  are connected by an optic fiber in the form of an optical communication cable, and an interface in the form of a common public radio interface (CPRI) is interposed there between. 
     In addition, the following Patent Document 1 indicates an example of the prior art that uses this type of CPRI for the interface. 
     Non-Patent Document 1: CPRI Specification V2.1 
     Patent Document 1: PCT Application Publication No. WO/2008/120297 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     In order to allow a radio base station to switch to a new radio service, it is desirable that the radio base station be able to share both old and new services to enable it to be compatible both services. 
     In addition, it is possible to consider installing two radio base stations in parallel as depicted in  FIG. 10  in order to provide radio base stations capable of being compatible with two old and new services (or two different services). 
     However, it is necessary to install an optical cable for connecting the radio equipment and the radio equipment controller in order to additionally provide the radio base station. However, installing the additional optical cable leads to increased costs. Thus, it would be desirable to be able to integrate and transmit two services using an existing optical cable. 
     Moreover, a radio base station compatible with multiple services would also be desirable. 
     Therefore, with the foregoing in view, it is an object of the present invention to provide a radio communication apparatus capable of sharing two radio services so as to be able to be compatible with both services, a radio communication system, and a radio communication method. 
     In addition, it is another object of the present invention to provide a radio communication apparatus and the like capable of providing two services without increasing the number of optical cables. 
     Moreover, it is another object of the present invention is to provide a radio communication apparatus and the like that is compatible with multiple services. 
     Means for Solving the Problem 
     A radio communication apparatus for performing radio communication, including: a first interface conversion unit which extracts a first signal and a second signal multiplexed and input, and corresponding to two different formats, and combines the extracted first and second signal; and a common amplifier which is shared by the first and second signal by amplifying the combined first and second signal, wherein a signal output from the common amplifier is transmitted. 
     A radio communication system, including: a first radio communication apparatus; and a second radio communication apparatus, wherein the first radio communication apparatus includes a first interface conversion unit which processes a first signal corresponding to a first format, and the second radio communication apparatus includes: a second interface conversion unit which is directly connected with the first interface conversion unit, and which is input with the first signal from the first interface conversion unit and a second signal corresponding to a second format, multiplexes the first signal and the second signal, and outputs; a third interface conversion unit which is input with multiplexed signal from the second interface conversion unit, extracts the first and second signal, and combines the extracted first and second signal; and a common amplifier which amplifies the first and second signals combined by the third interface conversion unit. 
     A radio communication method in a radio communication apparatus for performing radio communication, the method including: extracting multiplexed input first and second signal corresponding to two different formats respectively; combining the extracted first and second signal; amplifying the combined first and second signal with a common amplifier; and transmitting signal output from the common amplifier. 
     ADVANTAGEOUS EFFECT OF THE INVENTION 
     According to the present invention, a radio communication apparatus, a radio communication system and a radio communication method can be provided that enable two services to be accommodated smoothly. In addition, a radio communication apparatus and the like can be provided that is able to provide two services without increasing the number of optical cables. Moreover, a radio communication apparatus and the like can be provided that is compatible with multiple services. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a drawing depicting an example of the configuration of a radio communication system; 
         FIG. 2  is a drawing depicting an example of the configuration of a radio base station; 
         FIG. 3  is a drawing depicting an example of a transmission frame of a CPRI; 
         FIGS. 4(A) through 4(C)  are drawings depicting examples of transmission frames of a CPRI; 
         FIG. 5  is a drawing depicting another example of the configuration of a radio communication system; 
         FIG. 6  is a drawing depicting another example of the configuration of a radio base station; 
         FIGS. 7(A) through 7(C)  are drawings depicting examples of transmission frames of a CPRI; 
         FIG. 8  is a drawing depicting another example of the configuration of a radio base station; 
         FIG. 9  is a drawing depicting another example of the configuration of a radio base station; and 
         FIG. 10  is a drawing depicting an example of the configuration of a radio base station of the prior art. 
     
    
    
     EXPLANATION OF REFERENCE NUMERALS 
       1 ,  3  first, second host apparatus 
       2 ,  4  first, second radio base station 
       21 ,  41 ,  44  first, second, third radio equipment controller (REC) 
       42 ,  43 ,  44  second, third, fourth radio equipment (RE) 
       213 ,  413 ,  421 ,  431 ,  441  first, second, third, fourth, fifth interface conversion unit 
       422  reception amplification unit 
       2131 ,  4131 ,  4134 ,  4137 ,  4312 ,  4314 ,  4415 ,  4218  first, second, third, fourth, fifth, sixth, seventh, eighth CPRI processing unit 
       2132 ,  4132 ,  4133 ,  4136 ,  4138 ,  4211 ,  4311 ,  4313 ,  4416  first, second, third, fourth, fifth, sixth, seventh, eighth, ninth conversion unit 
       4135 ,  4212  first, second service multiplex separation unit 
       4213  frequency shift unit 
       4214  IQ extraction unit 
       4222  modulation unit 
       4225  down converter 
       4411 ,  4413 ,  4417  first, second, third time-frequency conversion unit 
       4414 ,  4419 ,  4420  first, second, third frequency-time conversion unit 
     BEST MODE FOR CARRYING OUT THE INVENTION 
     The following provides an explanation of embodiments of the present invention. 
     &lt;First Embodiment&gt; 
     First, an explanation is provided of a first embodiment.  FIG. 1  is a drawing depicting an example of the configuration of a radio communication system  100 . The radio communication system  100  includes a host apparatus  1  (to be referred to as a first host apparatus) which corresponds to a radio service A, a radio base station  2  (to be referred to as a first radio base station), a host apparatus  3  (to be referred to as a second host apparatus) which corresponds to a radio service B, a radio base station  4  (to be referred to as a second radio base station), and an antenna  5 . 
     In addition, the first radio base station  2  includes a first radio equipment controller (REC)  21 . The first radio equipment controller  21  includes a first common control unit  211 , a first baseband signal processing unit  212 , and a first interface conversion unit  213 . 
     On the other hand, the second radio base station  4  includes a second radio equipment controller (REC)  41  and a second radio equipment (RE)  42 . The second radio equipment controller  41  includes a second common control unit  411 , a second baseband signal processing unit  412 , and a second interface conversion unit  413 . In addition, the second radio equipment  42  includes a third interface conversion unit  421  and a transmission and reception amplification unit  422 . 
     The two host apparatuses  1  and  3  are, for example, radio network controllers (RNC) or access gateways (aGW), and transmit and receive data corresponding to each of two radio services (communication formats). Furthermore, in the embodiments indicated to follow, the radio service A is explained as an old service, while the radio service B is explained as a new service. Namely, in the case the radio base station  2  corresponding to the radio service A provides the radio service A via radio equipment not depicted and the antenna  5 , an explanation is provided for the case in which radio services A and B are subsequently provided via the antenna  5  by installing the radio equipment controller  41  and the radio equipment  42  that are compatible with the radio service B in order to provide the new service. Furthermore, at that time, the connection line between the interface conversion unit  213  and radio equipment not depicted is used as a line for connecting the interface conversion unit  213  and the interface conversion unit  421  of the radio equipment  42 , after which this line is reconnected as a line for connecting the interface conversion units  413  and  421 , while a connection line that connects the interface conversion units  213  and  413  is newly added. 
     The first and second radio equipment controllers  211  and  411  control the radio base stations  2  and  4  by, for example, distributing synchronizing signals to each of the radio base stations  2  and  4 , set individual settings and so forth. 
     The first and second baseband signal processing units  212  and  412  convert data from the host apparatuses  1  and  3  to baseband signals composed of I (in-phase) signals and Q (quadrature phase) signals, outputs them to the first interface conversion unit  213 , and so forth. 
     The first through third interface conversion units  213 ,  413  and  421  convert to a signal format corresponding to the connection cables (such as CPRI), convert to baseband signals and so forth. The details of which are described later. 
     Although operation of the radio communication system  100  depicted in  FIG. 1  will be described later, the effects thereof are described as follows. Namely, the second interface conversion unit  413  of the second radio equipment controller  41  multiplexes (or combines) two signals, consisting of signals corresponding to the radio service A from the first interface conversion unit  213  and signals corresponding to the radio service B from the second baseband signal processing unit  412 , and outputs multiplexed signals, as an single signal, to the second radio equipment  42 . In addition, the second interface conversion unit  413  separates signals from the third interface conversion unit  421  into two signals consisting of signal corresponding to the radio service A and signal corresponding to the radio service B, and outputs the signals to the first interface conversion unit  213  and the second baseband signal processing unit  412 , respectively. Thus, the first radio base station  2  is not required to be installed the internal radio equipment (RE), and it is not necessary to additionally install an optical cable within the first radio equipment controller  21 . 
       FIG. 2  is a drawing depicting an example of the detailed configuration of the first interface conversion unit  213 , the second interface conversion unit  413 , the third interface conversion unit  421 , and the transmission and reception amplifier  422 . 
     The first interface conversion unit  213  includes a first CPRI processing unit  2131  and a first conversion unit  2132 . 
     In addition, the second interface conversion unit  413  includes a second CPRI processing unit  4131 , a second conversion unit  4132 , a third conversion unit  4133 , a third CPRI processing unit  4134 , a first service multiplex separation unit  4135 , a fourth conversion unit  4136 , a fourth CPRI processing unit  4137 , and a fifth conversion unit  4138 . 
     Moreover, the third interface conversion unit  421  includes a sixth conversion unit  4211 , a second service multiplex separation unit  4212 , a frequency shift unit  4213 , and an IQ extraction unit  4214 . 
     Moreover, the transmission and reception amplifier  422  includes a D/A conversion unit  4221 , a modulation unit  4222 , a transmission amplification unit  4223 , a reception unit  4224 , a down converter  4225 , and an A/D conversion unit  4226 . 
     The following provides an explanation of the operation of the radio base stations  2  and  4 , containing the first through third interface units  213 ,  413  and  421 , with reference to  FIG. 1 . 
     First, an explanation of the operation is provided while moving downlink (from the host apparatuses  1  and  3  towards the antenna  5 ). As depicted in  FIG. 1 , the first host apparatus  1  outputs data corresponding to the radio service A. This data is converted to baseband signal including the I signal and Q signal by the baseband signal processing unit  212  via the common control unit  211 . The converted baseband signal is input to the first CPRI processing unit  2131  depicted in  FIG. 2 . 
     The first CPRI processing unit  2131  converts the baseband signal to signal of the CPRI format (to be referred to as CPRI signal).  FIG. 3  depicts an example of a CPRI format, and the I signal and Q signal which are baseband signal are inserted into a data block region. The first conversion unit  2132  converts the CPRI signal to optical signal and transmits the optical signal to the second radio base station  4  via an optical cable. 
     The fourth conversion unit  4136  of the second interface conversion unit  413  converts optical signal from the first conversion unit  2132  to CPRI signal which is electrical signal and outputs CPRI signal. The fourth CPRI processing unit  4137  extracts I signal and Q signal on the basis of the CPRI signal from the fourth conversion unit  4136  and outputs them to the first service multiplex separation unit  4135 . 
     On the other hand, data corresponding to the radio service B is output from the second host apparatus  3  depicted in  FIG. 1 , and the baseband signal corresponding to the radio service B is output via the second common control unit  411  and the second baseband signal processing unit  412 . The baseband signal is then input to the second CPRI processing unit  4131  depicted in  FIG. 2 . 
     The second CPRI processing unit  4131  converts the baseband signal to CPRI signal (see, for example,  FIG. 3 ) and outputs CPRI signal. The second conversion unit  4132  converts the converted CPRI signal to optical signal. The third conversion unit  4133  converts the converted optical signal so as to return them to CPRI signal, and the third CPRI processing unit  4134  extracts I signal and Q signal from the CPRI signal and outputs them to the first service multiplex separation unit  4135 . 
     Here, the reason for CPRI signal being converted to optical signal by the second conversion unit  4132  is as follows. Namely, as indicated by the broken line in  FIG. 2 , the second conversion unit  4132  and the sixth conversion unit  4211  of the second radio equipment  42  can be connected by a cable such as an optical cable. As a result of this connection, the connection between the fifth conversion unit  4138  and the sixth conversion unit  4211  is severed, enabling only service corresponding to the radio service B to be provided. In other words, this connection is effective in cases in which a shared service is not to be provided. In order to realize this connection, for example, the second interface conversion unit  413  is configured so as to be able to be separated by providing the second CPRI processing unit  4131  and the second conversion unit  4132  on one board, while providing the third conversion unit  4133  to the fifth conversion unit  4138  on another board as indicated with the dotted lines. Furthermore,  4131  to  4133  can be omitted, and the input to  4131  can also be imparted to the CPRI processing unit  4134 . 
     The first service multiplex separation unit  4135  multiplexes (or combines) I signal and Q signal in the form of baseband signal from the third CPRI processing unit  4134  and baseband signal corresponding to service A from the fourth CPRI processing unit  4137 . 
       FIGS. 4(A) through 4(C)  are drawings depicting examples of multiplexing processing.  FIG. 4(A)  depicts an example of CPRI signal into which is inserted I signal and Q signal of service A as an example of signals output from the fourth conversion unit  4136 . In addition,  FIG. 4(B)  is an example of CPRI signal into which is inserted I signal and Q signal of service B as an example of signal output from the second CPRI processing unit  4131  or the third conversion unit  4133 . The first service multiplex separation unit  4135  multiplexes by inserting I signal and Q signal of services A and B extracted with the third and fourth CPRI processing units  4134  and  4137  into their respective predetermined data block region (see  FIG. 4(C) ). 
     Returning to  FIG. 2 , the fifth conversion unit  4138  converts the multiplexed CPRI signal from the first service multiplex separation unit  4135  to optical signal. The converted optical signal is output to the third interface conversion unit  421  of the second radio equipment  42  via an optical cable. 
     The sixth conversion unit  4211  of the third interface conversion unit  421  converts the optical signal to CPRI signal of electric signal format. The second service multiplex separation unit  4212  extracts baseband signal of I signal and Q signal on the basis of the converted CPRI signal. As depicted in  FIG. 4(C) , since the CPRI signal is multiplexed, I signal and Q signal corresponding to service A and I signal and Q signal corresponding to service B are extracted, and the extracted I signals and Q signals of each service are output to the frequency shift unit  4213 . 
     The frequency shift unit  4213  shifts the frequency of the respective I signals and Q signals corresponding to each service to a predetermined frequency band. At that time, the frequency bands are prevented from overlapping between services A and B. The digitally represented waveform signal for which frequency is shifted is output to the transmission and reception amplifier  422 . Furthermore, signal input to the interface conversion unit  213  is, for example, digitally represented waveform signal which is generated by spread processing and filtering processing, while signal input to the interface conversion unit  4131  is, for example, digitally represented waveform signal which is generated by IFFT processing. 
     The D/A conversion unit  4221  converts the frequency-shifted baseband signal to analog signal. The modulation unit  4222  modulates to frequencies corresponding to each service (e.g., 2 GHz) by performing quadrature modulation to I signal and Q signal converted to analog signal. 
     The transmission amplification unit  4223  amplifies the modulated signals corresponding to the two services and outputs them to the antenna  5 . The transmission amplification unit  4223  is a common amplifier capable of amplifying both signals corresponding to the two radio services A and B. 
     The antenna  5  transmits the amplified signals by radio communication to information terminal such as a mobile phone or a personal digital assistance (PDA). As a result, each radio service can be provided to user. 
     In this manner, the radio communication system  100  in this embodiment includes the second radio base station  4  as to enable the use of the transmission amplifier  4223  which is a common amplifier. Namely, the radio communication system  100  is configured so that signals corresponding to two radio services (communication formats) are time-multiplexed with the first service multiplex separation unit  4135 , signals of two different services are respectively extracted by the second service multiplex separation unit  4212 , and after being frequency-shifted by the frequency shifting unit  4213 , are input to the common amplifier. Thus, the radio communication system  100  can be in a shared state that corresponds to two radio services. In addition, it is able to provide at least two radio services, since the radio communication system  100  performs processing by multiplexing signals corresponding to two radio services. 
     Next, an explanation of the operation is provided while moving uplink (direction in which signals are transmitted from the antenna  5  to the first radio base station  2 ). 
     Signal received by the antenna  5  is converted to fixed analog signal by the reception unit  4224 , and is down-converted by the down converter  4225  to a frequency enabling input to the A/D conversion unit  4226  in a subsequent stage. The down-converted signal is converted to digital signal by the A/D conversion unit  4226  and output to the third interface conversion unit  421 . 
     The IQ extraction unit  4214  extracts I signals and Q signals corresponding to each service from the digitally converted signal and outputs those signals. 
     The second service multiplex separation unit  4212  multiplexes these baseband signals, converts to CPRI signal by adding a header, and outputs. The CPRI signal in this case is signal as depicted in  FIG. 4(C) , for example. The sixth conversion unit  4211  converts the CPRI signal to optical signal and outputs. 
     The fifth conversion unit  4138  converts optical signal from the sixth conversion unit  4211  to CPRI signal which is electrical signal, and the CPRI signal is separated into baseband signals of each service by the first service multiplex separation unit  4135 . Processing precisely corresponding to the reverse of the processing depicted in  FIGS. 4(A) to 4(C)  is performed. The baseband signal corresponding to the radio service A is output to the fourth CPRI processing unit  4137 , while the baseband signal corresponding to the radio service B is output to the third CPRI processing unit  4134 . 
     The baseband signal corresponding to the radio service A is converted to CPRI signal by the fourth CPRI processing unit  4137 , and further converted to optical signal by the fourth conversion unit  4136 . The optical signal is then converted to electrical signal by the first conversion unit  2132  connected by the cable, the electrical signal is converted to CPRI signal by the first CPRI processing unit  2131 , and the CPRI signal is output to the baseband signal processing unit  212  depicted in  FIG. 1 . The baseband signal is extracted from the CPRI signal by the first baseband signal processing unit  212 , and output to the first host apparatus  1  via the first common control unit  211 . 
     On the other hand, the baseband signal corresponding to the radio service B is converted to CPRI signal by the third CPRI processing unit  4134 , and the CPRI signal is converted to optical signal by the third conversion unit  4133 . Subsequently, the baseband signal is extracted from the CPRI signal by the second conversion unit  4132  and the second CPRI processing unit  4131 . The extracted baseband signal is output as is without performing any particular processing to the second baseband processing unit  412  depicted in  FIG. 1 , and then output to the second host apparatus  3  via the second common control unit  411 . 
     &lt;Second Embodiment&gt; 
     The following provides an explanation of a second embodiment.  FIG. 5  is a drawing depicting an example of the configuration of the radio communication system  100  in the second embodiment. The same reference numerals are used to indicate those portions of the radio communication system  100  of the second embodiment that are the same as those of the first embodiment. 
     The second radio base station  4  of the radio communication system  100  includes a third radio equipment (RE)  43 . The third radio equipment  43  is connected with the first and second interface conversion units  213  and  413  via a cable, and can process the two communication formats of the first and second radio equipment controllers (REC)  21  and  41 . 
     As depicted in  FIG. 5 , the configuration of the first radio base station  2  and the configuration of the second interface conversion unit  413  are the same as those of the first embodiment. 
     The second interface conversion unit  413  of the second radio base station  4  includes the second CPRI processing unit  4131  and the second conversion unit  4132 . 
     The third radio equipment  43  of the second radio base station  4  includes a fourth interface conversion unit  431  and the transmission and reception amplification unit  422 . In addition, the fourth interface conversion unit  431  includes a seventh conversion unit  4311 , a fifth CPRI processing unit  4312 , an eighth conversion unit  4313 , a sixth CPRI processing unit  4314 , the frequency shift unit  4213  and the IQ extraction unit  4214 . The configuration of the transmission and reception amplification unit  422  is omitted from the explanation since it is the same as that of the first embodiment. 
     The operation of the principal portions of the radio communication system  100  configured in this manner is as described below. The first conversion unit  2132  of the first interface conversion unit  213  outputs optical signal corresponding to the radio service A. In addition, the second conversion unit  4132  of the second interface conversion unit  413  outputs optical signal corresponding to the radio service B. 
     The seventh conversion unit  4311  of the fourth interface conversion unit  431  converts optical signal corresponding to the radio service A to CPRI signal which is electrical signal, and the fifth CPRI processing unit  4312  extracts I signal and Q signal which is baseband signal from the converted CPRI signal. 
     The eighth conversion unit  4313  converts optical signal corresponding to the radio service B to CPRI signal which is electrical signal, and the sixth CPRI processing unit  4314  extracts I signal and Q signal which is baseband signal from the converted CPRI signal. 
     The frequency shift unit  4213  multiplexes signals of the radio services employing two communication formats in the same manner as the first embodiment. The frequencies of the signals of the two radio services are shifted to prescribed frequency bands. At that time, the frequency bands are prevented from overlapping. An explanation of subsequent signal processing is omitted since it is the same as that of the first embodiment. 
     Operation of the uplink direction is as follows. Namely, baseband signals of each service corresponding to the two communication formats in the I/Q extraction unit  4214  are output to the fifth and sixth CPRI processing units  4312  and  4314 , and are respectively converted to each CPRI signal. The CPRI signals are then converted to optical signals by the seventh and eighth conversion units  4311  and  4313 , after which they are output to the first and second radio equipment controllers  21  and  42 , respectively. 
     As depicted in  FIG. 5 , the radio communication system  100  of the second embodiment eliminates the need for providing separate radio equipment corresponding to the first radio equipment controller  21 , thereby eliminating the need to intentionally securing space for installing the radio equipment. The radio communication system  100  effects obtained in the first embodiment since it operates in the same manner as the first embodiment with the exception of that described above. 
     &lt;Third Embodiment&gt; 
     The following provides an explanation of a third embodiment. The third embodiment is an example of implementing two communication formats in the same manner as the first embodiment by combining and separating signals corresponding to two communication formats on a frequency axis. 
       FIG. 6  is an example of the configuration of principal portions of the radio communication system  100  of the third embodiment. The same reference numerals are used to indicate those portions of the radio communication system  100  of the third embodiment that are the same as those of the first embodiment. 
     In comparison with the first embodiment, the second radio base station  4  includes a third radio equipment controller (REC)  44 , and the third radio equipment controller  44  includes a fifth interface conversion unit  441 . 
     The fifth interface conversion unit  441 , includes, in addition to the second through fourth CPRI processing units  4131 ,  4134  and  4137  and the second through fourth conversion units  4136 , a first time-frequency conversion unit  4411 , a combining unit  4412 , a second time-frequency conversion unit  4413 , a first frequency-time conversion unit  4414 , a seventh CPRI processing unit  4415 , a ninth conversion unit  4416 , a third time-frequency conversion unit  4417 , a separation unit  4418 , and second and third frequency-time conversion units  4419  and  4420 . Furthermore,  4131 ,  4132  and  4133  are the same as previously described with respect to being able to be omitted. 
     The following provides an explanation of downlink operation. Namely, signal corresponding to the radio service A is input from the first radio base station  2  to the fourth conversion unit  4136 , and converted from optical signal to CPRI signal which is electrical signal. The fourth CPRI processing unit  4137  extracts I signal and Q signal which is baseband signal from the converted CPRI signal and outputs. The first time-frequency conversion unit  4411  converts I signal and Q signal on a time axis to I signal and Q signal a frequency axis by a Fourier transform and the like and outputs. 
     On the other hand, signal corresponding to the radio service B is output to the second time-frequency conversion unit  4413  via the second CPRI processing unit  4131 , the second conversion unit  4132 , the third conversion unit  4133 , and the third CPRI processing unit  4134 . The second time-frequency conversion unit  4413  converts I signal and Q signal on the time axis to I signal and Q signal on the frequency axis by the Fourier transform and the like in the same manner as the first time-frequency conversion unit  4411 . 
     The combining unit  4412  inputs I signal and Q signal on the frequency axis corresponding to the radio services A and B, and combines signals by adding the two signals on the frequency axis on the frequency axis. 
     The first frequency-time conversion unit  4414  again converts the combined signals from the combining unit  4412  to I signal and Q signal on the time axis by a reverse Fourier transform and the like. It goes without saying that the converted signal is a signal combined from signals corresponding to the two radio services. 
     The converted I signal and Q signal on the time axis is converted to CPRI signal by the seventh CPRI processing unit  4415 .  FIG. 7(C)  is a drawing depicting an example of the format of CPRI signal following conversion. As depicted in this drawing, two signal combined on the frequency axis is inserted into the data block region. Furthermore,  FIG. 7(A)  depicts an example of the format of CPRI signal output from the fourth CPRI processing unit  4137 , while  FIG. 7(B)  depicts an example of the format of CPRI signal output from the third CPRI processing unit  4134 . 
     Subsequently, the CPRI signal is converted to optical signal by the ninth conversion unit  4416  and output to the second radio equipment  42 . 
     The sixth conversion unit  4211  of the third interface conversion unit  421  converts the optical signal to CPRI signal which is electric signal. The eighth CPRI processing unit  4218  extracts base band signal which is I signal and Q signal, from the converted CPRI signal. As depicted in  FIG. 7(C) , since the 
     CPRI signals are already combined, the I signal and Q signal with which the service A and B is combined is extracted, and the extracted I signal and Q signal are output to a frequency mapping unit  4213 . 
     The frequency mapping unit  4213  maps the extracted I signal and Q signal to a predetermined frequency band. The mapped baseband signal is then output to the transmission and reception amplification unit  422 . 
     An explanation of subsequent processing is omitted since it is the same as that of the first embodiment. 
     Operation of the uplink direction is as follows. 
     Although signal received with the antenna  5  is processed in the transmission and reception amplification unit  422 , an explanation thereof is omitted since processing in the transmission and reception amplification unit  422  is the same as that of the first embodiment. 
     The IQ extraction unit  4214  extracts I signal and Q signal from digitally converted signal and outputs. The extracted I signal and Q signal are in a state of combining the services A and B. 
     The eighth CPRI processing unit  4218  converts the baseband signal to CPRI signal by, for example, adding a header and the like thereto, and outputs the CPRI signals. The CPRI signal in this case is signal like those depicted in  FIG. 7(C) , for example. The sixth conversion unit  4211  converts the CPRI signal to optical signal and outputs. 
     Signal from the second radio equipment  42  is output to the third time-frequency conversion unit  4417  via the ninth conversion unit  4416  and the seventh CPRI processing unit  4415 . 
     The third time-frequency conversion unit  4417  converts I signal and Q signal which is baseband signal from the seventh CPRI processing unit  4415  to I signal and Q signal on the frequency axis by the Fourier transform and the like. 
     The separation unit  4418  separates I signal and Q signal on the frequency axis into I signals and Q signals of each radio service. For example, the I signal and Q signal corresponding to the radio service A are separated according to a certain predetermined frequency band, while the I signal and Q signal corresponding to the radio service B are separated according to another predetermined frequency band. The I signal and Q signal corresponding to the radio service A are output to the second frequency-time conversion unit  4419 , while the I signal and Q signal corresponding to the radio service B are output to the third frequency-time conversion unit  4420 . 
     The second frequency-time conversion unit  4419  converts the I signal and Q signal on the frequency axis to I signal and Q signal on the time axis by the Fourier transform and the like and then outputs. The converted I signal and Q signal are output to the first radio base station  2  via the fourth CPRI processing unit  4137  and the fourth conversion unit  4136 . 
     In addition, the third frequency-time conversion unit  4420  also converts the I signal and Q signal on the frequency axis to I signal and Q signal on the time axis and outputs, the signals are output from the fifth interface conversion unit  441  to the baseband signal processing unit  412  (see  FIG. 1 ). An explanation of subsequent processing is omitted since it is the same as that of the first embodiment. 
     In this third embodiment as well, since processing is performed by combining signals of two communication formats by deploying and adding the signals on the frequency axis, the radio communication system  100  can be made to be corresponded with two radio communication services in the same manner as the first embodiment. 
     Furthermore, in this embodiment as well, the second conversion unit  4132  and the sixth conversion unit  4211  can be directly connected with the cable, thereby making it possible to implement one service only. 
     &lt;Fourth Embodiment&gt; 
     Next, an explanation is provided of a fourth embodiment.  FIG. 8  is a drawing depicting an example of the configuration of the principal portions of the radio communication system  100  in the fourth embodiment. The fourth embodiment is an example in which the first radio equipment controller  21  corresponding to the radio service A and the second radio equipment  42  capable of processing two communication formats are connected directly without going through the second interface conversion unit  413  of the second radio equipment controller  41  that processes a communication format corresponding to the radio service B. 
     In this fourth embodiment, since a configuration is employed that does not go through the second radio equipment controller  41 , when switching from the old second radio equipment controller  41  to a new second radio equipment controller, the new second radio equipment controller can be smoothly installed in the second radio base station  4  while providing one of the radio services. 
     The configuration is the same as that of the first embodiment with the exception of the first conversion unit  2132  and the sixth conversion unit  4211  being connected, and the second radio equipment controller  41  no longer being required. With respect to processing, the second service multiplex separation unit  4212  does not performs multiplex processing or separation processing, but rather directly outputs input CPRI signal to the frequency shift unit  4213 , and outputs the I signal and Q signal which is input baseband signal directly to the sixth conversion unit  4211 . An explanation of subsequent processing is omitted since it is the same as that of the first embodiment. 
     &lt;Fifth Embodiment&gt; 
     The following provides an explanation of a fifth embodiment. 
       FIG. 9  is a drawing depicting an example of the configuration of principal portions of the radio communication system  100  in the fifth embodiment. The same reference numerals are used to indicate those portions of the fifth embodiment that are the same as those of the first embodiment. Although the second interface conversion unit  413  corresponding to the radio service B has multiplex and separation function in the first embodiment, the first interface conversion unit  213  corresponding to the radio service A has multiplex and separation functions in this embodiment. 
     As depicted in  FIG. 9 , the second interface conversion unit  413  included in the second radio equipment controller  41  of the second radio base station  4  includes the second CPRI processing unit  4131  and the second conversion unit  4132 . 
     On the other hand, the first interface conversion unit  213  included in the first radio equipment controller  21  of the first radio base station  2  includes the third and fourth CPRI processing units  4134  and  4137 , the third and fourth conversion units  4133  and  4136 , the first service multiplex separation unit  4135  and the fifth conversion unit  4138  in addition to the first CPRI processing unit  2131  and the first conversion unit  2132 . 
     Signal corresponding to the radio service A can be output to the first interface conversion unit  213  by connecting the fourth conversion unit  4136  and the second conversion unit  4132  with an optical cable, and the two multiplexed signals can be transmitted from the second radio equipment  42  by connecting the fifth conversion unit  4138  and the sixth conversion unit  4211 . 
     Similar to the first embodiment, CPRI signal corresponding to radio services A and B is multiplexed in the first multiplex separation unit  4135 . For example, the CPRI signal is multiplexed by mapping to the prescribed region of the data block of the CPRI format as depicted in  FIG. 4(C) . 
     In this manner, multiplex and separation functions of two radio services can be performed in not only one interface conversion unit, but also by another interface conversion unit in this embodiment. Furthermore, since processing is performed in this embodiment in the same manner as the first embodiment with the exception of multiplex and separation processing being performed by the first interface conversion unit  213 , the same effects are demonstrated as those of the first embodiment. 
     &lt;Other Embodiments&gt; 
     The following provides an explanation of other embodiments. Although connection of the first conversion unit  2132  and the fourth conversion unit  4136  with the optical cable is explained in the first and third embodiments (see  FIGS. 2 and 6 ), they may be connected with a cable other than the optical cable. In addition, the fourth conversion unit  4316  and the second conversion unit  4132  in the fifth embodiment may also be connected with a cable other than the optical cable. 
     In addition, in the fifth embodiment, processing for multiplexing and separating signal in the direction of the time axis is performed in the first service multiplex separation unit  4135  of the first interface conversion unit  213  of the first radio base station  2  corresponding to the radio service A. However, combining processing on the frequency axis as explained in the third embodiment may be performed in the first interface conversion unit  213  instead of the first service multiplex separation unit  4135 .