JP5719249B2 - Transmission system, transmission method, and baseband processing apparatus in separable radio base station - Google Patents

Description

  The present invention relates to a transmission system and transmission method, a baseband processing apparatus, and a radio apparatus in a separate radio base station.

  In recent years, as a base station architecture, a separation-type wireless base station that separates a baseband processing device and a wireless device and connects them with an optical fiber has become common, and an interface such as a CPRI (Common Public Radio Interface) is used. Is standardized (for example, Patent Document 1). FIG. 10 shows a typical configuration example of a separation-type radio base station. By making the baseband processing device (BBE) 8 and the radio device (RFE) 9 separate as shown in FIG. 10, the RF processing function can be installed at a location several kilometers away from the baseband processing function. It becomes possible to install a base station with a higher degree of freedom. Further, as shown in FIG. 10, wireless devices can be connected by cascade connection as in RFE 10, and a base station covering a wider area can be installed.

  FIG. 11 is a block diagram showing the configuration of a conventional separation-type radio base station. The conventional BBE 8 passes the transmission data from the network processing unit 81 to the physical layer 84 via the RLC unit 82 and the MAC unit 83, and the channel coding unit 841d and the resource mapper 842d process the signal for the downlink signal. To do. The IFFT unit 843d converts the processed signal from the frequency domain to the time domain, and transmits the converted signal to the RFE 9 via the interface 85.

  In the RFE 9, the interface 91 receives a signal, and the signal is transmitted from the transmission antenna 95 d to each terminal device communicating with the RFE 9 via the DFE unit 92, the DAC 93 d, and the RF unit 94. In the case of an uplink received signal, a signal received by the receiving antenna 95u is transmitted to the BBE 8 via the interface 91 via the RF unit 94, ADC 93u, and DFE unit 92. Then, the FFT unit 843u converts from the time domain to the frequency domain, and passes to the network processing unit 81 via the resource demapper 842u, the channel decoding unit 841u, the MAC unit 83, and the RLC unit 82.

  Also, examples of resource configurations allocated to RFE9 and RFE10 by the scheduler of BBE8 are shown in FIGS. 12 (a) and 12 (b), respectively. An example of assignment of the CPRI transmission format is shown in FIG. As shown in FIGS. 12 (a) and 12 (b), the BBE 8 allocates communication resources having a predetermined bandwidth to each terminal device within the system bandwidth range for n subcarriers, and belongs to each wireless device. Wireless communication with the terminal device is realized.

JP 2007-31185 A

  However, the conventional separation-type radio base station converts the data of the number of effective subcarriers into the time domain using the IFFT and FFT processing, and transmits the data between the baseband device and the radio device using the time domain signal. As a result, the transmission capacity increases compared to the required transmission information capacity. Specifically, for example, when transmitting data for 600 effective subcarriers in a system band of 10 MHz, if IFFT processing is performed, only the size of 2 n units can be processed, and thus transmission is performed using a signal in the time domain. In this case, it is necessary to transmit a data amount equivalent to the data for 1024 subcarriers, and the transmission capacity has increased by about 1.7 times.

  Further, the conventional separation type radio base station has a problem in radio transmission quality. In other words, a conventional separation-type radio base station is connected to a baseband processing device and a wireless device using a plurality of cables. If the transmission capacity of the baseband processing device and the wireless device has to be reduced due to reasons such as adding a wireless device in a cascade connection to the baseband processing device, resources allocated to all the terminal devices Had to be reduced so the system bandwidth had to be reduced. Specifically, when it is necessary to halve the transmission band between the baseband processing device and the wireless device for the above reason, in the conventional configuration, in order to maintain the number of connected terminals, FIG. As shown in (b), the system bandwidth had to be halved to n / 2 carriers. When the system bandwidth is halved, the choice of subcarriers for allocating resources decreases, so the effects of frequency selective fading and the like increase, resulting in problems of wireless transmission quality and wireless transmission capacity reduction. . Alternatively, when there are a plurality of cascaded wireless devices, all of the communication of one wireless device has to be interrupted.

  Accordingly, an object of the present invention made in view of the above problems is to provide a separation type capable of transmission between a baseband device and a wireless device without increasing the transmission capacity compared to the capacity of necessary transmission information. An object of the present invention is to provide a transmission system and a transmission method in a radio base station.

In order to solve the above problems, a transmission system according to the present invention provides:
A transmission system in a separate radio base station comprising a baseband processing device and a radio device,
The baseband processing device transmits control information necessary for FFT processing and IFFT processing to the wireless device,
The wireless device performs FFT processing and IFFT processing based on the control information,
The baseband processing device and the wireless device transmit signals in the frequency domain ,
The baseband processing device allocates a communication resource having a predetermined frequency bandwidth within a system bandwidth to a terminal device belonging to the wireless device;
When the transmission capacity in communication between the baseband processing device and the wireless device is insufficient, the baseband processing device reduces the total allocated amount of the communication resources without changing the system band.

The transmission system according to the present invention further includes:
The baseband processing apparatus allocates communication resources in a frequency band having higher radio communication quality among the system bands to terminal apparatuses belonging to the radio apparatus.

Moreover, the transmission method according to the present invention includes:
A transmission method in a separate radio base station comprising a baseband processing device and a radio device,
The baseband processing device transmitting control information necessary for FFT processing and IFFT processing to the wireless device;
The wireless device performs an FFT process and an IFFT process based on the control information;
The baseband processing device and the wireless device transmitting signals in a frequency domain;
The baseband processing device assigning a communication resource having a predetermined frequency bandwidth within a system bandwidth to a terminal device belonging to the wireless device;
When the transmission capacity in communication between the baseband processing device and the wireless device is insufficient, the baseband processing device reduces the total allocated amount of the communication resources without changing the system band;
It is characterized by including.

Moreover, the transmission method according to the present invention includes:
Allocating the communication resource to the terminal device further
The baseband processing device performs control so as to allocate communication resources in a frequency band having higher radio communication quality among the system bands to terminal devices belonging to the radio device.

Moreover, the baseband processing apparatus according to the present invention includes:
A baseband processing device connected to a wireless device in a separation-type wireless base station,
A wireless monitoring controller that generates control information necessary for IFFT processing and FFT processing;
An interface that transmits the control information to the wireless device and transmits the wireless device using a frequency domain signal ;
The wireless monitoring control unit allocates communication resources having a predetermined frequency bandwidth within a system bandwidth to a terminal device belonging to the wireless device, and a transmission capacity is insufficient in communication between the baseband processing device and the wireless device In this case, the baseband processing device reduces the total allocated amount of the communication resources without changing the system band .

  According to the transmission system and the transmission method of the present invention, transmission between the baseband apparatus and the radio apparatus can be performed in the separation-type radio base station without increasing the transmission capacity as compared with the capacity of necessary transmission information.

It is a block diagram showing the structure of the separation | isolation type | mold radio base station which concerns on one Embodiment of this invention. It is a flowchart which shows operation | movement of the isolation | separation type radio base station which concerns on one Embodiment of this invention. It is a figure which shows the connection structure of the separation-type wireless base station which concerns on Example 1 of this invention. It is a figure which shows the example of resource allocation of the isolation | separation type radio base station which concerns on Example 1 of this invention. It is a figure which shows the resource allocation example of the isolation | separation type radio base station when the transmission capacity which concerns on Example 1 of this invention is insufficient. It is a figure which shows the modification of the resource allocation of the isolation | separation type | mold radio base station when the transmission capacity based on Example 1 of this invention is insufficient. It is a figure which shows the connection structure of the isolation | separation type radio base station which concerns on Example 2 of this invention. It is a figure which shows the example of resource allocation of the isolation | separation type | mold radio base station which concerns on Example 2 of this invention. It is a figure which shows the resource allocation example of the isolation | separation type radio base station when the transmission capacity which concerns on Example 2 of this invention is insufficient. It is a figure which shows the connection structure of the conventional separation | isolation type | mold radio base station. It is a block diagram showing the structure of the conventional separation | isolation type | mold radio base station. It is a figure showing the example of resource allocation of the conventional separation type | mold radio base station. It is a figure showing the example of resource allocation when the transmission capacity of the conventional separation | isolation type | mold radio | wireless base station runs short.

  Embodiments of the present invention will be described below.

(Embodiment)
FIG. 1 is a block diagram of a transmission system in a separation type radio base station according to an embodiment of the present invention. The transmission system in the separation-type radio base station according to Embodiment 1 of the present invention includes a baseband processing device (BBE) 1 and a radio device (RFE) 2. BBE1 and RFE2 are connected by an optical fiber cable.

  The BBE 1 includes a network processing unit 11, a radio link control (RLC) unit 12, a media access control (MAC) unit 13, a physical layer 14, an interface 15, and a monitoring control unit 16.

  The network processing unit 11 performs various processes related to the network of the BBE 1, and specifically performs various processes of data transmitted on the downlink and data received on the uplink.

  The RLC unit 12 performs radio link control, and the MAC unit 13 performs media access control such as radio resource allocation control and passes data to the channel coding unit 141d. The MAC unit 13 includes a scheduler 131. The scheduler 131 instructs the resource mapper 142d to allocate a radio resource based on an instruction from the monitoring control unit 16 described later.

  The physical layer 14 performs physical layer processing. Here, the physical layer processing performed in the BBE1 in the present invention is processing from resource mapping in the downlink processing, and processing from resource demapping in the uplink processing, and does not include IFFT processing and FFT processing. The physical layer 14 includes a channel encoding unit 141d, a channel decoding unit 141u, a resource mapper 142d, and a resource demapper 142u.

  The channel encoding unit 141d performs channel encoding of the data received from the MAC unit. In channel coding, coding is performed by a coding method with a coding rate according to data, and the coded signal is passed to the resource mapper 142d.

  The channel decoding unit 141u performs channel decoding of the signal received from the resource demapper 142u and passes the data to the MAC unit 13.

  The resource mapper 142d performs resource allocation, that is, resource mapping, on the encoded signal for each subcarrier. The resource allocation is performed based on an instruction from the scheduler 131. The resource mapper 142d passes the resource assigned signal to the interface 15.

  The resource demapper 142u performs resource demapping for extracting a desired signal from the signals to which resources are allocated, and passes the extracted signal to the channel decoding unit 141u.

  The interface 15 transmits the signal received from the resource mapper 142d, the control signal, and the reference timing signal to the RFE2. The signal received from the resource mapper 142d is a frequency domain signal because IFFT processing has not been performed. That is, the interface 15 transmits a frequency domain signal to the RFE 2. The interface 15 preferably transmits each signal by the CPRI protocol. Only the number of effective subcarriers is transmitted. Since the number of subcarriers differs for each system band, transmission data is adjusted as appropriate.

  Specifically, the control signal includes information necessary for IFFT and FFT processing, control information such as a CP (Cyclic Prefix) type, a symbol number, a slot number, an IQ type, a system band, and a reception timing adjustment value. The control signal is preferably transmitted using an empty channel such as Vendor Specific in the CPRI.

  Of the control information related to the control signal, control information that does not change during system operation need only be transmitted in advance only when the apparatus is started up. The transmission order of transmission data may be determined in advance to reduce the information. For example, when two antennas are used, it is determined in advance that the signals are transmitted in the order of the symbol A of the antenna A, the symbol a of the antenna B, the symbol b of the antenna A, and the symbol b of the antenna B. Reduction is possible as appropriate.

  The reference timing signal is a signal for synchronizing the reference timings of BBE1 and RFE2, and is generated by the monitoring control unit 16. The reference timing signal is transmitted after correcting the transmission timing in consideration of a transmission delay caused by an optical cable between BBE1 and RFE2. In other words, the reference timing signal transmitted from BBE1 at the early start has the same timing on the time axis as the reference timing signal in BBE1 when received by RFE2. Note that the transmission delay of an optical cable or the like is measured using a method described in the CPRI specification. These signals are preferably performed using an empty channel such as Vendor Specific or a BFN (Node B Frame Number) in the CPRI.

  The monitoring control unit 16 generates a control signal and a reference timing signal. In addition, when the transmission capacity between the BBE1 and the RFE2 is insufficient for the connected wireless device, the monitoring control unit 16 causes the MAC unit 13 to communicate with the wireless device according to the insufficient capacity. An instruction is given to reduce the resource allocation of the terminal device that is being used.

  The RFE 2 includes an interface 21, a memory 22d, a memory 22u, an IFFT unit 23d, an FFT unit 23u, a timing adjustment unit 24, a timing control unit 25, a digital front end (DFE) unit 26, and a digital analog conversion. Device (DAC) 27d, analog-digital converter (ADC) 27u, RF unit 28, transmission antenna 29d, and reception antenna 29u.

  The interface 21 receives a frequency domain signal, a control signal, and a reference timing signal, and stores the received frequency domain signal in the memory 22d. Further, the reception timing adjustment value included in the received reference timing signal and control signal is passed to the timing adjustment unit 25. Further, control information necessary for IFFT processing and FFT processing among the control signals is passed to the IFFT unit 23d and the FFT unit 23u, respectively.

  The memory 22d stores a frequency domain signal received by the interface 21. The memory 22u stores the frequency domain signal generated by the FFT unit 23u.

  The IFFT unit 23d performs IFFT processing on the frequency domain signal extracted from the memory 22d. That is, the IFFT unit 23 d converts the frequency domain signal into a time domain signal, and passes the converted signal to the timing adjustment unit 24. Information necessary for IFFT processing is performed based on the control signal received from BBE1. For example, in the CP addition process, the CP type in the control signal is used.

  The FFT unit 23u receives a signal from the timing adjustment unit 24 at a predetermined timing, and performs an FFT process. That is, the FFT unit 23u converts a time-domain signal into a frequency-domain signal and stores it in the memory 22u. Information necessary for the FFT processing is performed based on the control signal received from BBE1. For example, in the CP deletion process, the CP type in the control signal is used.

  The timing adjustment unit 24 adjusts transmission timing and reception timing in the antenna 29d and the antenna 29u of the RFE2. Specifically, in the case of downlink, the timing adjustment unit 24 transmits transmission data according to the timing signal received from the timing control unit 25. Note that the transmission timing may be adjusted by BBE1 and not adjusted by the wireless device. In this case, BBE1 or RFE2 has information on the IFFT processing delay time to be processed by the wireless device taking into account the system bandwidth, CP type, etc. (in this case, information is provided from the wireless device to the baseband processing device). Transmit transmission data in consideration of delay time. In the case of uplink, the received data is temporarily stored in a memory (not shown), and is read from the FFT unit 23u as appropriate.

  The timing control unit 25 performs control for synchronizing the processing timings of BBE1 and RFE2. Specifically, the timing control unit 25 synchronizes the reference timing of RFE2 based on the reference timing signal transmitted from BBE1, and supplies the timing signal to the timing adjustment unit 24. In the case of the downlink, the timing signal supplied to the timing adjustment unit 24 takes into account the delay time from the DFE 26 to the transmission antenna 29d with respect to the reference timing synchronized with the baseband processing apparatus, and the timing advanced by that delay time. Generate with In the case of uplink, the timing signal provided to the FFT unit 23u is generated in consideration of the delay time from the reception antenna 29u to the DFE 26, the reception timing adjustment value transmitted from the baseband processing device, and the like.

  The DFE unit 26 performs signal up-conversion, down-conversion, and filtering processing for uplink and downlink signals. The DAC 27d converts the transmission signal from a digital signal to an analog signal. The ADC 27u converts the received signal from an analog signal to a digital signal.

  The RF unit 28 transmits the analog signal received from the DAC 27d through the transmission antenna 29d. Further, the analog signal received by the receiving antenna 29u is passed to the ADC 27u.

  Next, the operation of the transmission system according to the embodiment of the present invention will be described with reference to the flowchart shown in FIG. In the flowchart shown in FIG. 2, the downlink operation (step S11 to step S18) and the uplink operation (step S19 to step S26) are combined, and the downlink and uplink transmissions operate continuously. Although an example is shown, the present invention is not limited to this, and uplink and downlink operations may be performed independently.

  First, when the RLC unit 12 receives uplink transmission data from the network processing unit 11, the RLC unit 12 performs radio link control (step S11). Subsequently, the MAC unit 13 performs media access control such as radio resource allocation control and passes data to the channel encoding unit 141d (step S12). The MAC unit 13 includes a scheduler 131. The scheduler 131 instructs the resource mapper 142d to allocate a radio resource based on an instruction from the monitoring control unit 16.

  Subsequently, the channel encoding unit 141d performs channel encoding of the data received from the MAC unit (step S13). In channel coding, coding is performed by a coding method with a coding rate according to data, and the coded signal is passed to the resource mapper 142d.

  Subsequently, the resource mapper 142d allocates the encoded signal to each subcarrier (step S14). The resource allocation is performed based on an instruction from the scheduler 131. The resource mapper 142d passes the resource assigned signal to the interface 15.

  Subsequently, the interface 15 transmits the signal received from the resource mapper 142d, the control signal, and the reference timing signal to the RFE 2 connected by the optical cable (step S15). The signal received from the resource mapper 142d is a frequency domain signal because IFFT processing has not been performed. That is, the interface 15 transmits a frequency domain signal to the RFE 2. The interface 15 preferably transmits each signal by the CPRI protocol. Only the number of effective subcarriers is transmitted. Since the number of subcarriers differs for each system band, transmission data is adjusted as appropriate.

  Subsequently, the interface 21 of the RFE2 receives the frequency domain signal, the control signal, and the reference timing signal (step S16). The interface 21 stores the received frequency domain signal in the memory 22d. The received reference timing signal and reception timing adjustment value are passed to the timing adjustment unit 25. Further, control information necessary for IFFT processing and FFT processing among the control signals is passed to the IFFT unit 23d and the FFT unit 23u, respectively.

  Subsequently, the IFFT unit 23d performs IFFT processing on the frequency domain signal extracted from the memory 22d, converts the frequency domain signal into a time domain signal, and passes the converted signal to the timing adjustment unit 24 (step S17). Information necessary for IFFT processing is performed based on the control signal received from BBE1. For example, in the CP addition process, the CP type in the control signal is used.

  Subsequently, RFE2 transmits a signal to the terminal devices belonging to RFE2. (Step S18). Specifically, the timing adjustment unit 24 passes a signal to be transmitted to the DFE 26 based on the timing signal received from the timing control unit 25. Subsequently, the DFE 26 upconverts the transmission signal and performs predetermined filtering. Subsequently, the DAC 27d converts the digital signal into an analog signal, and the RF unit 28 transmits the analog signal through the transmission antenna 29d.

  Next, the downlink operation will be described. First, RFE2 receives a downlink signal from a terminal device belonging to RFE2 (step S19). Specifically, the RF unit 28 receives an analog signal from the terminal device through the reception antenna 29u, and the ADC 27u converts the analog signal into a digital signal. Subsequently, the DFE 26 down-converts the signal, performs predetermined filtering, and passes the signal to the timing adjustment unit 24.

  Subsequently, the FFT unit 23u receives a signal from the timing adjustment unit 24 at a predetermined timing, performs an FFT process, converts the time domain signal into a frequency domain signal, and stores the signal in the memory 22u (step S20). The timing is appropriately adjusted based on the timing signal received from the timing control unit 25 by the timing adjustment unit 24. Information necessary for the FFT processing is performed based on the control signal received from BBE1. For example, in the CP deletion process, the CP type in the control signal is used.

  Subsequently, the interface 21 extracts a frequency domain signal from the memory 22u, and transmits the frequency domain signal to the BBE 1 (step S21). Only the number of effective subcarriers is transmitted. BBE1 receives the signal in the frequency domain (step S22).

  Subsequently, the resource demapper 142u extracts a desired signal from the signals to which resources are allocated, and passes the extracted signal to the channel decoding unit 141u (step S23).

  Subsequently, the channel decoding unit 141u performs channel decoding of the signal received from the resource demapper 142u and passes the data to the MAC unit 13 (step S24).

  Subsequently, the MAC unit 13 performs media access control (step S25), the RLC unit 12 performs radio link control (step S26), the downlink data is passed to the network processing unit 11, and the process ends.

  As described above, according to the present invention, since BBE1 and RFE2 perform transmission in the frequency domain, baseband processing can be performed without increasing the transmission capacity compared to the required transmission information capacity in the separation-type radio base station. Transmission between the device and the wireless device is possible.

  Specifically, for example, when transmitting data for 600 effective subcarriers in a system band of 10 MHz, when transmitting by frequency domain signals, it is only necessary to transmit data for 600 subcarriers, which increases the transmission capacity. do not do. Therefore, the transmission capacity is about 0.6 times that of the conventional technology for transmission in the time domain, and the interface can be slowed down. Thus, there are advantages such as low power consumption and circuit cost reduction. Further, as the transmission capacity increases due to the recent widening of the bandwidth, high-speed transmission of the interface is required, but this is effective when development of a device capable of high-speed transmission cannot be followed. In addition, since it is possible to increase the number of wireless devices that are cascade-connected to the baseband processing device, it is possible to reduce the installation cost and cost of the cable facility, and the installation period.

Example 1
Next, an example (Example 1) of the transmission system according to the present embodiment is shown in FIGS.

  FIG. 3 shows an example of a configuration in which two radio devices RFE2a and RFE2b are cascade-connected to BBE1. In the figure, the two wireless devices are represented as “RFE1” and “RFE2”, and in the CPRI format in FIGS. 4 and 5, the assignment of each wireless device is described using the notation. Note that the configurations of RFE2a and RFE2b are the same as those of RFE2 shown in FIG. The RFE 2a communicates with the terminal devices “UE11” to “UE16”, and the RFE 2b communicates with the terminal devices “UE21” to “UE26”. Also, in RFE 2a and RFE 2b, resource configuration examples allocated by each scheduler 131 are shown in FIGS. 4 (a) and 4 (b), respectively. An example of assignment of the CPRI transmission format is shown in FIG. As described above, the BBE 1 allocates communication resources having a predetermined frequency bandwidth to the terminal devices belonging to the RFE 2a and the RFE 2b within the range of the system band for n subcarriers.

  Here, a description will be given of processing when a link error occurs in communication between BBE1 and RFE2a for some reason, and the transmission rate is halved from the originally assumed rate. In CPRI communication, the transmission speed is negotiated and set when a link is established. The main set speeds include 614.4 Mbit / s, 1228.8 Mbit / s, 2457.6 Mbit / s, etc. Here, it is assumed that the original transmission speed 2457.6 Mbit / s is reduced to half the transmission speed 1228.8 Mbit / s. explain.

  When the monitoring controller 16 knows that the CPRI link error and transmission rate have been halved, the scheduler 131 of the MAC unit 13 halves the total amount of resources allocated to the terminal devices connected to the RFE 2a and RFE 2b, The condition of the band remains unchanged (the range of the assigned subcarrier is not changed) is instructed. Except for the above conditions, resources are allocated to each terminal apparatus by a conventional scheduler method. The resource configuration example at this time is shown in FIGS. 5A and 5B for RFE2a and RFE2b, respectively. An example of assignment of the CPRI transmission format is shown in FIG. Since communication between BBE1 and RFE2a is transmitted in the frequency domain, the system band can be left as it is.

  In the allocation shown in FIG. 5, the bandwidth of resources allocated to each terminal apparatus is halved and the total allocation of radio resources is halved. However, even when the subcarrier resource allocation is changed due to the influence of frequency selective fading or the like, Since the carrier options are the same as before the CPRI transmission rate is halved, the wireless transmission quality and the wireless transmission capacity do not decrease. For example, FIG. 6 (a) and FIG. 6 (b) show resource allocation change examples when the radio communication quality of a certain subcarrier deteriorates for RFE 2a and RFE 2b, respectively. In order to avoid subcarriers with degraded radio communication quality, the subcarrier bands allocated to “UE12”, “UE15”, etc. in FIG. 6A, and “UE25”, “UE26”, etc. in FIG. It has changed.

  As described above, according to the present invention, when the transmission capacity between the BBE 1 and each wireless device (RFE2a and RFE2b) is reduced for some reason, the allocated resource is reduced, but the signal is transmitted in the frequency domain, so the system band is changed. Therefore, the subcarrier selection range does not change, and it is possible to prevent a decrease in radio transmission quality and radio transmission capacity due to influences such as frequency selective fading.

(Example 2)
Next, an example (Example 2) of the transmission system according to the present embodiment is shown in FIGS.

  FIG. 7 shows that two radio devices RFE2a and RFE2b are connected by cascade connection to the baseband processing device BBE1a, and two radio devices RFE2c and RFE2d are cascaded to the baseband processing device BBE1b. It is the structural example connected by these. RFE2b and RFE2d are connected by an optical cable. In the figure, two baseband processing devices are represented as “BBE1”, “BBE2”, and four wireless devices are represented as “RFE1”, “RFE2”, “RFE3”, “RFE4”, and the CPRI format in FIGS. Shows the assignment of each wireless device using this notation. The configurations of BBE1a and BBE1b are the same as the configuration of BBE1 in FIG. 1, and the configurations of RFE2a, RFE2b, RFE2c, and RFE2d are the same as the configuration of RFE2 shown in FIG.

  At this time, in RFE 2a and RFE 2b, the configuration examples assigned by each scheduler 131 are FIG. 4A and FIG. 4B, respectively, and the CPRI transmission format assignment example is FIG. 4C. On the other hand, configuration examples assigned by the respective schedulers 131 in the RFE 2c and RFE 2d are FIG. 8A and FIG. 8B, respectively, and an assignment example of the CPRI transmission format is FIG. 8C. In this way, the BBE 1a and the BBE 1b allocate communication resources having a predetermined frequency bandwidth within the range of the system band for n subcarriers to terminal devices belonging to the RFE 2a and RFE 2b, the RFE 2c, and the RFE 2d, respectively.

  Here, processing when the RBE 2b and the RFE 2b are cascade-connected to the BBE 1a by an optical cable between the RFE 2d and the RFE 2b when communication between the BBE 1b and the RFE 2c becomes impossible for some reason will be described.

  First, the connection between the BBE 1a and the RFE 2c and RFE 2d is validated. Here, when increasing the number of wireless devices connected to the BBE 1a, the monitoring controller 16 is notified from the center station that the number of wireless devices has increased via the network. In addition, the terminal device connected to RFE2c and RFE2d performs connection processing again.

  The supervisory control unit 16 causes the scheduler 131 of the MAC unit 13 to halve the total amount of allocated resources of the terminal devices connected to the already connected wireless devices FRE2a and RFE2b and to leave the system bandwidth unchanged (assigned subcarriers). The range of (No change) is indicated. Except for the above conditions, resources are allocated to each terminal apparatus by a conventional scheduler method. Examples of allocated resource configurations are shown in FIGS. 5A and 5B for RFE2a and RFE2b, respectively, and in FIGS. 9A and 9B for RFE2c and RFE2d, respectively. An example of assignment of the CPRI transmission format is shown in FIG. Since communication between BBE 1a and RFE 2a is transmitted in the frequency domain, the system band can be left as it is.

  As described above, according to the present invention, when the transmission capacity of the BBE 1 and each wireless device (RFE2a, RFE2b, RFE2c, and RFE2d) is reduced, the allocated resources are allocated without changing the system band in order to transmit the signal in the frequency domain. Since the system band is not changed, the subcarrier selection range does not change, and it is possible to prevent a decrease in radio transmission quality and radio transmission capacity due to the influence of frequency selective fading.

  The network processing unit 11, RLC unit 12, MAC unit 13, physical layer 14, and monitoring control unit 16 in the BBE 1 may be provided in parallel and perform baseband processing by parallel processing. In this case, the baseband processing can be speeded up.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, the functions included in each member, each means, each step, etc. can be rearranged so as not to be logically contradictory, and a plurality of means, steps, etc. can be combined into one or divided. Is possible.

1, 1a, 1b Baseband processing device 11 Network processing unit 12 RLC unit 13 MAC unit 131 Scheduler 14 Physical layer 141d Channel encoding unit 141u Channel decoding unit 142d Resource mapper 142u Resource demapper 15 Interface 16 Control monitoring unit 2, 2a, 2b, 2c, 2d Wireless device 21 Interface 22d, 2du Memory 23d IFFT unit 23u FFT unit 24 Timing adjustment unit 25 Timing control unit 26 DFE
27d DAC
27u ADC
28 RF unit 29d Transmitting antenna 29u Reception antenna 8 Baseband processing device 9, 10 Wireless device 81 Network processing unit 82 RLC unit 83 MAC unit 84 Physical layer 841d Channel encoding unit 841u Channel decoding unit 842d Resource mapper 842u Resource demapper 843d IFFT Part 844u FFT part 85 interface 91 interface 92 DFE
93d DAC
93u ADC
94 RF unit 95d Transmission antenna 95u Reception antenna

Claims (5)

A transmission system in a separate radio base station comprising a baseband processing device and a radio device,
The baseband processing device transmits control information necessary for FFT processing and IFFT processing to the wireless device,
The wireless device performs FFT processing and IFFT processing based on the control information,
The baseband processing device and the wireless device transmit signals in the frequency domain ,
The baseband processing device allocates a communication resource having a predetermined frequency bandwidth within a system bandwidth to a terminal device belonging to the wireless device;
When the transmission capacity in communication between the baseband processing device and the wireless device is insufficient, the baseband processing device reduces the total allocated amount of the communication resources without changing the system band. system. The transmission system further includes:
Transmission system according to claim 1 wherein the baseband processing device of the system band, which is characterized by allocating communication resources in a higher frequency band radio communication quality to a terminal device belonging to the wireless device. A transmission method in a separate radio base station comprising a baseband processing device and a radio device,
The baseband processing device transmitting control information necessary for FFT processing and IFFT processing to the wireless device;
The wireless device performs an FFT process and an IFFT process based on the control information;
The baseband processing device and the wireless device transmitting signals in a frequency domain;
The baseband processing device assigning a communication resource having a predetermined frequency bandwidth within a system bandwidth to a terminal device belonging to the wireless device;
When the transmission capacity in communication between the baseband processing device and the wireless device is insufficient, the baseband processing device reduces the total allocated amount of the communication resources without changing the system band;
The transmission method characterized by including. The step of allocating the communication resource to the terminal device further includes
The transmission according to claim 3 , wherein the baseband processing device performs control so as to allocate communication resources in a frequency band having higher radio communication quality among the system bands to terminal devices belonging to the radio device. Method. A baseband processing device connected to a wireless device in a separation-type wireless base station,
A wireless monitoring controller that generates control information necessary for IFFT processing and FFT processing;
An interface that transmits the control information to the wireless device and transmits the wireless device using a frequency domain signal ;
The wireless monitoring control unit allocates communication resources having a predetermined frequency bandwidth within a system bandwidth to a terminal device belonging to the wireless device, and a transmission capacity is insufficient in communication between the baseband processing device and the wireless device In this case, the baseband processing device reduces the total allocated amount of the communication resources without changing the system band .

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