JP5905813B2 - Distributed radio communication base station system, signal processing apparatus and signal processing method - Google Patents

Description

  The present invention relates to a distributed radio communication base station system, a signal processing apparatus, and a signal processing method, in which the function of a radio communication base station is divided into a signal processing unit and a radio communication unit and physically separated.

  In a cellular system, in order to improve the degree of freedom of cell configuration, a base station function is physically separated by dividing it into a signal processing unit (BBU: Base Band Unit) and an RF unit (RRU: Remote Radio Unit). It is considered to do. At this time, the radio signal is transmitted through the optical fiber between the BBU and the RRU by the RoF (Radio over Fiber) technique. RoF technology can be broadly divided into analog RoF technology and digital RoF technology, but in recent years, digital RoF technology with excellent transmission quality has been actively studied, and the use formulation under the standard organizations such as CPRI (Common Public Radio Interface) (For example, refer nonpatent literature 1).

  Hereinafter, the digital RoF transmission technology between BBU and RRU is referred to as related technology. Also, a digital signal (IQ data) for each I-axis and Q-axis of the radio signal created by BBU is converted into an optical signal and transmitted to the RRU, and the optical signal received by the RRU is converted into a radio signal and sent to the terminal. The link to transmit is called a downlink. On the other hand, a link that receives a radio modulated signal transmitted from a terminal by RRU, converts the received radio signal to an optical signal and transmits it to the BBU, converts the optical signal received by the BBU to IQ data, and demodulates the signal Is called uplink.

  One BBU can also accommodate a plurality of RRUs. As a result, the BBUs required for each RRU can be consolidated into one, and the operation / installation cost can be reduced. As an example of such a form, as shown in FIG. 1, a form in which BBU2 and RRU1-1, 1-2,..., 1-N are connected by PON (Passive Optical Network) has been proposed. Yes. In this system, the bandwidth of the optical fiber 6 between the OLT (Optical Line Terminal) 4 and the optical splitter 7 is constant, but the optical splitter 7 and the ONU (Optical Network Unit) 3-1, 3-2,.・ ・ The band of optical fiber 5-1, 5-2,..., 5-N between 3-N is the required band of ONU 3-1, 3-2,. It can be changed together. As a PON signal multiplexing method, TDM, WDM, FDM, or the like can be adopted.

  The bandwidth for uplink in the PON section can be dynamically allocated to each RRU 1 by dynamic bandwidth allocation (DBA: Dynamic Bandwidth Allocation). In the DBA, each ONU 3 transmits a transmission buffer amount to the OLT 4, calculates the data transmission time and time of each ONU 3 from the buffer amount collected by the OLT 4, notifies the calculated information to each ONU 3, and each ONU 3 is designated. Data is transmitted using the time zone specified for the time. As a result, the bandwidth allocated between BBU2 and each RRU1 with less communication traffic can be reduced, the bandwidth allocated between BBU2 with each communication traffic and each RRU1 can be increased, and the bandwidth of the optical access section can be used effectively. it can.

CPRI, “CPRI Specification V5.0”, Sep. , 2011, http: // www. cpri. info / spec. html

  FIG. 2 shows the configuration of a related RRU. The RRU 1 includes an antenna 101 and a transmission / reception switching unit 102 in common with the uplink and the downlink. The antenna 101 transmits / receives a radio signal. The transmission / reception switching unit 102 switches between transmission / reception. The transmission / reception switching unit 102 can handle any of TDM, WDM, and FDM.

  Further, the RRU 1 includes an amplifier 103U, a down-conversion unit 104U, an A / D conversion unit 105U, a baseband filter unit 106U, a frame conversion unit 107U, and an E / O conversion unit 108U for uplink.

  The amplifier 103U amplifies the signal power of the received radio signal to a level that allows signal processing. The down-conversion unit 104U down-converts the radio signal. The A / D conversion unit 105U converts the down-converted analog signal into IQ data. The baseband filter unit 106U performs a filtering process on the IQ data. The frame conversion unit 107U multiplexes IQ data and a control signal. The E / O converter 108U converts the electrical signal into an optical signal and transmits it.

  On the other hand, RRU1 has an O / E conversion unit 108D, a frame conversion unit 107D, a baseband filter unit 106D, a D / A conversion unit 105D, an up-conversion unit 104D, and an amplifier 103D for downlink.

  The O / E conversion unit 108D converts the optical signal received from the BBU 2 into an electrical signal. The frame conversion unit 107D extracts a control signal and IQ data from the received signal. The baseband filter unit 106D performs a filtering process on the IQ data. The D / A converter 105D converts the IQ data into an analog signal. The up-conversion unit 104D up-converts the analog signal. The amplifier 103D amplifies the power up to a predetermined transmission power.

  The configuration of the related art BBU is shown in FIG. The BBU 2 includes a radio band allocation / coding rate / modulation scheme determination unit 201 in common with uplink and downlink signal processing. The radio band allocation / coding rate / modulation method determination unit 201 sends the information to each terminal based on the channel quality information estimated by the channel quality information extraction unit 208 described later in FIG. Scheduling to allocate a radio band with good channel quality and determining a modulation scheme / coding rate so that each terminal satisfies the required reception quality.

  Further, the BBU 2 includes an FEC encoding unit 202D, a primary modulation unit 203D, a mapping unit 204D, a secondary modulation unit 205D, a frame conversion unit 206D, and an E / O conversion unit 207D for downlink signal processing.

  The FEC encoding unit 202D performs FEC encoding on user data and control information based on the determined encoding rate. Primary modulation section 203D modulates the bit sequence of user data and control information based on the determined modulation scheme. The mapping unit 204D maps the output of the primary modulation unit 203D to a predetermined radio band. The secondary modulation unit 205D performs secondary modulation on the primary modulation signal. The frame conversion unit 206D multiplexes the IQ data output from the secondary modulation unit 205D and the control signal between the BBU2 and each RRU1. The E / O conversion unit 207D converts the electrical signal into an optical signal and transmits it.

  Here, the primary modulation is symbol mapping such as QPSK and 16QAM, and the secondary modulation can be considered as spreading for CDMA modulation and IFFT for OFDM modulation. Further, there may be a case where only the primary modulation exists without the secondary modulation.

  On the other hand, the BBU2 performs O / E conversion unit 207U, frame conversion unit 206U, secondary demodulation unit 205U, demapping unit 204U, primary demodulation unit 203U, FEC decoding unit 202U and channel quality information for uplink signal processing. An extraction unit 208 is included.

  The O / E conversion unit 207U converts an optical signal into an electrical signal. The frame conversion unit 206U extracts a control signal and IQ data between the BBU2 and each RRU1 from the received signal. The secondary demodulation unit 205U performs secondary demodulation on the IQ data. The demapping unit 204U extracts a signal from a predetermined radio band of the secondary demodulated signal. The primary demodulation unit 203U performs primary demodulation on the demapped signal. The FEC decoding unit 202U performs FEC decoding on the primary demodulated signal. The channel quality information extraction unit 208 extracts channel quality information from a part of the demapped signal.

  Here, secondary demodulation refers to FFT processing when the secondary modulation unit 205D performs IFFT processing, and refers to despreading processing when the secondary modulation unit 205D performs spreading processing. The primary demodulation refers to a process of performing hard / soft decision on symbols such as QPSK and 16QAM that have undergone primary modulation. Further, when the secondary modulation unit 205D does not exist, the secondary demodulation unit 205U does not exist.

  In a cellular system such as LTE (Long Term Evolution) and WiMAX (Worldwide Interoperability for Microwave Access), a terminal needs a communication channel (wireless band) unique to the terminal. This allocation of the radio band is performed by the base station.

  Taking the LTE system as an example, as shown in FIG. 4, the base station performs scheduling with a minimum 1 ms period and allocates a radio band to each terminal. The radio band allocation is performed in resource block (RB) units, and 1 RB is configured by a frequency region of 180 kHz and a time region of 0.5 ms. That is, when the system bandwidth is 20 MHz, 110 RBs exist on the frequency axis. In addition, 7 symbols (1 symbol 71.4 μs including a cyclic prefix) are inserted into 1 RB assuming a normal cyclic prefix.

  On the other hand, the signal transmitted from the base station to the terminal includes not only user data for each terminal, but also control information (scheduling information, ACK / NACK determination results, etc.), and a reference signal for the terminal to perform channel estimation (all Cell-specific reference signals transmitted to terminals, UE-specific reference signals transmitted to individual terminals, and the like, and synchronization signals for each terminal to synchronize with a base station.

  Taking the case of transmitting an LTE signal by CPRI as an example, a sampling frequency of 30.72 MHz is used for a system with a system bandwidth of 20 MHz. In digital sampling for each of the I axis and Q axis, A quantization bit number of 4 to 20 bits and 8 to 20 bits is applied to downstream signals. In frame conversion, a control signal is inserted into 1/16 of the entire frame, and the signal is further transmitted after being 8B / 10B encoded.

  By the way, in the system described above with reference to FIG. 1, even if the bandwidth of the PON section is set to be smaller than the total value of the maximum required bandwidth between BBU2 and each RRU1, the bandwidth does not run out in most time. However, traffic between BBU2 and each RRU1 may increase instantaneously, and the total value of required bands between BBU2 and each RRU1 may exceed the bandwidth of the PON section.

  At this time, some data cannot be transmitted. This means that some downlink radio signals do not reach the wireless terminal, or some uplink radio signals do not reach the base station, and a retransmission request occurs, increasing the delay and transmission efficiency. It leads to decline.

  Therefore, in order to solve the above-described problem, the present invention provides a distributed wireless communication base station system in which the functions of the wireless communication base station are divided into BBUs and RRUs and physically separated from each other, between the BBU and each RRU. The object is to suppress the total value of the required bandwidth between the BBU and each RRU from exceeding the bandwidth of the PON section due to the instantaneous increase in traffic.

  In order to achieve the above object, the BBU determines the number of quantization bits used for transmission between the BBU and each RRU so that the total required bandwidth between the BBU and each RRU is equal to or less than the bandwidth of the PON section. It was decided to reduce from the number of quantization bits in A / D conversion or D / A conversion.

  However, every time the number of quantization bits is reduced by 1 bit, reception SNR (Signal to Noise Ratio) deteriorates by 6 dB due to quantization noise, so that there is a possibility that demodulation is not possible even if a radio signal is received. Therefore, BBU decides to lower the modulation scheme or lower the coding rate so that the radio signal satisfies the required quality.

  Specifically, according to the present invention, a base station function of transmitting and receiving an analog wireless signal to and from a wireless terminal has one signal processing device (BBU: Base Band Unit) and a plurality of wireless devices (RRU: Remote Radio Unit). The BBU and the plurality of RRUs are connected using an optical subscriber communication network (PON: Passive Optical Network) that transmits a digital optical signal, The BBU is connected to an optical subscriber line terminal (OLT) in the PON, and each RRU is connected to an optical network unit (ONU) in the PON. , The BBU A wireless bandwidth allocating unit that assigns a wireless bandwidth to communication between each RRU, a required bandwidth in communication between the own device and each RRU, and a total value of the required bandwidths for the plurality of RRUs The required bandwidth calculation unit, and the total value of the required bandwidths calculated by the required bandwidth calculation unit so as not to exceed the upper limit value of the bandwidth in communication between the OLT and the optical splitter in the PON. Quantization bit number determination unit for determining the number of quantization bits for communication between the RRUs, and the quantization bit number in communication between the own apparatus determined by the quantization bit number determination unit and the RRUs Quantization bit number notifying unit for notifying each RRU, and the quantization bit number applied to the downlink data from its own device to each RRU, the digital / analog in each RRU. A BBU side quantization bit number conversion unit that converts the quantization bit number in the log conversion into a quantization bit number in downlink communication from the own device determined by the quantization bit number determination unit to the RRU, and Each RRU includes a quantization bit number acquisition unit that acquires, from the BBU, a quantization bit number in communication between the BBU notified by the quantization bit number notification unit and its own device. Type wireless communication base station system.

  Further, according to the present invention, each RRU has a quantization bit number applied to downlink data from the BBU to the own device, and the downlink bit from the BBU acquired by the quantization bit number obtaining unit to the own device. A distributed wireless communication base station system, further comprising: an RRU side quantization bit number restoration unit that restores a quantization bit number in communication to a quantization bit number in digital / analog conversion in the device itself .

  Further, according to the present invention, the function of a base station that transmits and receives an analog wireless signal to and from a wireless terminal is divided into one signal processing device (BBU: Base Band Unit) and a plurality of wireless devices (RRU: Remote Radio Unit). The BBU and the plurality of RRUs are connected using an optical subscriber communication network (PON) that transmits digital optical signals, and the BBU is connected to the BBU. The RPON is connected to an optical subscriber line terminal (OLT), and each RRU is connected to an optical network unit (ONU) of the PON, and the BBU is connected to the optical network unit (ONU). The own device and said Requirement for calculating a required bandwidth in the communication between the RRU and a wireless bandwidth allocating unit that allocates a wireless bandwidth for communication between RRUs, and the RRU, and calculating a total value of the required bandwidths for the plurality of RRUs The total value of the required bandwidth calculated by the bandwidth calculating unit and the required bandwidth calculating unit does not exceed the upper limit value of the bandwidth in communication between the OLT and the optical splitter in the PON. Quantization bit number determination unit that determines the quantization bit number for communication between RRUs, and the quantization bit number in communication between the own apparatus and the RRUs determined by the quantization bit number determination unit A quantization bit number notifying unit that notifies each RRU, and each RRU is a quantization bit in communication between the BBU and the own device notified by the quantization bit number notification unit. A quantization bit number acquisition unit for acquiring a number from the BBU, and a quantization bit number applied to uplink data from the own device to the BBU, based on the quantization bit number in the analog / digital conversion in the own device A RRU-side quantization bit number conversion unit that converts the quantization bit number in the uplink communication from the own device acquired by the quantization bit number acquisition unit to the BBU. Station system.

  Further, according to the present invention, the BBU transmits the number of quantization bits to be applied to the uplink data from each RRU to the own device from each RRU determined by the quantization bit number determination unit to the own device. A distributed wireless communication base station system, further comprising: a BBU-side quantized bit number restoring unit that restores a quantized bit number in analog / digital conversion in each RRU from a quantized bit number in uplink communication It is.

  In addition, the present invention is a signal processing apparatus that shares the function of a base station that transmits and receives an analog radio signal with a radio terminal with a plurality of radio equipment (RRU), and is an optical subscriber that transmits a digital optical signal. Is allocated to an optical subscriber line terminal (OLT) in a subscriber communication network (PON: Passive Optical Network), and allocates a radio band to communication between the own apparatus and each RRU. A required bandwidth in communication between the communication device and the own device and each RRU, a required bandwidth calculating unit that calculates a total value of the required bandwidths for the plurality of RRUs, and the required bandwidth calculated by the required bandwidth calculating unit The total value of the band is the communication between the OLT and the optical splitter in the PON. In order to avoid exceeding the upper limit value of the bandwidth in the network, a quantization bit number determination unit that determines the number of quantization bits for communication between the own device and each RRU, and downlink data from the own device to each RRU The quantization bit number applied to the RRU is quantized in the downlink communication from the own apparatus determined by the quantization bit number determination unit to the RRU from the quantization bit number in the digital / analog conversion in each RRU. A signal processing device comprising: a self-device side quantization bit number conversion unit that converts the number of bits into a bit number.

  In addition, the present invention is a signal processing apparatus that shares the function of a base station that transmits and receives an analog radio signal with a radio terminal with a plurality of radio equipment (RRU), and is an optical subscriber that transmits a digital optical signal. Is allocated to an optical subscriber line terminal (OLT) in a subscriber communication network (PON: Passive Optical Network), and allocates a radio band to communication between the own apparatus and each RRU. A required bandwidth in communication between the communication device and the own device and each RRU, a required bandwidth calculating unit that calculates a total value of the required bandwidths for the plurality of RRUs, and the required bandwidth calculated by the required bandwidth calculating unit The total value of the band is the communication between the OLT and the optical splitter in the PON. A quantization bit number determination unit that determines the number of quantization bits for communication between the own device and each RRU so as not to exceed the upper limit value of the bandwidth in the signal processing apparatus. is there.

  In addition, the present invention provides a quantization bit number applied to uplink data from each RRU to its own device, in the uplink communication from each RRU to its own device determined by the quantization bit number determining unit. The signal processing apparatus further comprises a self-device side quantized bit number restoring unit that restores the number of quantized bits to the quantized bit number in the analog / digital conversion in each RRU.

  In addition, the present invention provides a signal in one signal processing device (BBU: Base Band Unit) that shares the function of a base station that transmits and receives an analog radio signal with a wireless terminal, with a plurality of wireless devices (RRU: Remote Radio Unit). In the processing method, the own device is connected to an optical subscriber line terminal device (OLT) in an optical subscriber communication network (PON) that transmits a digital optical signal. And a required bandwidth in communication between the own apparatus and each RRU is calculated based on a radio band allocated for communication between the RRUs, and a total value of the required bandwidths is calculated for the plurality of RRUs. Required bandwidth calculation step and the required bandwidth calculation step The number of quantization bits for the communication between the own device and each RRU so that the total value of the required bands does not exceed the upper limit value of the band in the communication between the OLT and the optical splitter in the PON. A quantization bit number determination step for determining the number of quantization bits applied to downlink data from the own apparatus to each RRU, from the number of quantization bits in the digital / analog conversion in each RRU, A self-device-side quantized bit number conversion step for converting into a quantized bit number in downlink communication from the self-device determined in the quantized bit number determining step to each RRU; is there.

  In addition, the present invention provides a signal in one signal processing device (BBU: Base Band Unit) that shares the function of a base station that transmits and receives an analog radio signal with a wireless terminal, with a plurality of wireless devices (RRU: Remote Radio Unit). In the processing method, the own device is connected to an optical subscriber line terminal device (OLT) in an optical subscriber communication network (PON) that transmits a digital optical signal. And a required bandwidth in communication between the own apparatus and each RRU is calculated based on a radio band allocated for communication between the RRUs, and a total value of the required bandwidths is calculated for the plurality of RRUs. Required bandwidth calculation step and the required bandwidth calculation step The number of quantization bits for the communication between the own device and each RRU so that the total value of the required bands does not exceed the upper limit value of the band in the communication between the OLT and the optical splitter in the PON. A quantization bit number determining step for determining

  In the present invention, the number of quantization bits applied to the uplink data from each RRU to the own device is determined in the quantization in uplink communication from each RRU determined to the quantization bit number determining step to the own device. A signal further comprising: a quantization bit number restoration step on the own apparatus side that restores the quantization bit number in the analog / digital conversion in each RRU from the quantization bit number after the quantization bit number determination step It is a processing method.

  According to this configuration, the BBU reduces the number of quantization bits used for transmission between the BBU and each RRU so that the total value of the required bands between the BBU and each RRU is equal to or less than the bandwidth of the PON section. It is possible to prevent the total value of the required bandwidth between the BBU and each RRU from exceeding the bandwidth of the PON section due to the instantaneous increase in traffic between the BBU and each RRU.

  Further, according to the present invention, the BBU communicates between the own apparatus and each RRU based on the number of quantization bits in the communication between the own apparatus and each RRU determined by the quantization bit number determination unit. A modulation scheme / coding rate determination unit that determines at least one of a modulation scheme and a coding rate for communication between the own apparatus and each RRU so that the communication quality in the network satisfies a predetermined quality This is a distributed wireless communication base station system.

  Further, according to the present invention, communication quality in communication between the own apparatus and each RRU is determined based on the number of quantization bits in communication between the own apparatus and each RRU determined by the quantization bit number determination unit. A modulation scheme / coding rate determination unit that determines at least one of a modulation scheme and a coding rate for communication between the device and each RRU so as to satisfy a predetermined quality; It is a signal processing device.

  Further, according to the present invention, communication quality in communication between the own apparatus and each RRU is determined based on the number of quantization bits in communication between the own apparatus and each RRU determined in the quantization bit number determination step. A modulation scheme / coding rate determination step for determining at least one of a modulation scheme and a coding rate for communication between the own apparatus and each RRU so as to satisfy a predetermined quality. It is the signal processing method characterized by further providing after a step.

  According to this configuration, the BBU receives a radio signal by reducing the number of quantization bits in order to lower the modulation scheme or lower the coding rate so that the radio signal satisfies the required quality. The possibility of being unable to demodulate can also be suppressed.

  Also, in the present invention, in the BBU, the radio band allocating unit includes at least one of a modulation scheme and a coding rate in communication between the own apparatus determined by the modulation scheme / coding rate determining unit and each RRU. A wireless band is allocated to the communication between the own device and each RRU so that the transmission rate in the communication between the own device and each RRU satisfies the requested rate. Type wireless communication base station system.

  Further, according to the present invention, the radio band allocating unit is based on at least one of a modulation scheme and a coding rate in communication between the own apparatus determined by the modulation scheme / coding rate determining unit and each RRU. In addition, the signal processing apparatus is characterized in that a radio band is allocated to communication between the own apparatus and each RRU so that a transmission speed in communication between the own apparatus and each RRU satisfies a requested speed. .

  Further, according to the present invention, the required band calculation step is based on at least one of a modulation scheme and a coding rate in communication between the own apparatus and each RRU determined in the modulation scheme / coding rate determination step. In addition, a signal processing method is characterized in that a radio band is allocated to communication between the own apparatus and each RRU so that a transmission speed in communication between the own apparatus and each RRU satisfies a requested speed. .

  According to this configuration, since the BBU reallocates the radio band so that the transmission rate satisfies the required rate, the transmission rate does not satisfy the required rate by lowering the modulation scheme or reducing the coding rate. The possibility can be suppressed.

  Further, according to the present invention, the BBU uses a sampling frequency for communication between the own apparatus and each RRU based on a required band in communication between the own apparatus and each RRU calculated by the required band calculation unit. A sampling frequency determining unit for determining the sampling frequency, a sampling frequency notifying unit for notifying each RRU of a sampling frequency in communication between the own device determined by the sampling frequency determining unit and each RRU, and the own device to each RRU The sampling frequency applied to the downlink data is converted from the sampling frequency in the digital / analog conversion in each RRU to the sampling frequency in the downlink communication from the own apparatus determined by the sampling frequency determination unit to each RRU. A BBU-side sampling frequency converter that Each RRU is applied to the sampling frequency acquisition unit that acquires from the BBU the sampling frequency in communication between the BBU notified by the sampling frequency notification unit and the own device, and applied to the downlink data from the BBU to the own device. An RRU-side sampling frequency restoring unit that restores the sampling frequency to be a sampling frequency in digital / analog conversion in each RRU from a sampling frequency in downlink communication from the BBU to the own device acquired by the sampling frequency acquisition unit, And a distributed radio communication base station system.

  Further, according to the present invention, the BBU uses a sampling frequency for communication between the own apparatus and each RRU based on a required band in communication between the own apparatus and each RRU calculated by the required band calculation unit. A sampling frequency determining unit that determines the sampling frequency, a sampling frequency notifying unit that notifies the RRU of the sampling frequency in communication between the own device and the RRU determined by the sampling frequency determining unit, and the RRU to the own device The sampling frequency applied to the upstream data is restored from the sampling frequency in the upstream communication from each RRU determined by the sampling frequency determination unit to the own apparatus to the sampling frequency in the analog / digital conversion in each RRU. A BBU side sampling frequency restoring unit that performs, Each RRU is applied to the sampling frequency acquisition unit that acquires the sampling frequency in the communication between the BBU notified by the sampling frequency notification unit and the own device from the BBU, and the uplink data from the own device to the BBU. An RRU-side sampling frequency conversion unit that converts the sampling frequency to be converted from the sampling frequency in the analog / digital conversion in each RRU into the sampling frequency in the uplink communication from the own device acquired by the sampling frequency acquisition unit to the BBU; And a distributed radio communication base station system.

  Further, the present invention provides a sampling for determining a sampling frequency for communication between the own apparatus and each RRU based on the required band in communication between the own apparatus and each RRU calculated by the required band calculation unit. From the frequency determination unit and the own device determined by the sampling frequency determination unit, the sampling frequency applied to the downlink data from the own device to each RRU is determined from the sampling frequency in the digital / analog conversion in each RRU. The signal processing apparatus further comprises: a local apparatus side sampling frequency conversion unit that converts the sampling frequency into a sampling frequency in downlink communication to each RRU.

  Further, the present invention provides a sampling for determining a sampling frequency for communication between the own apparatus and each RRU based on the required band in communication between the own apparatus and each RRU calculated by the required band calculation unit. The sampling frequency applied to the uplink data from each RRU to the own device from the frequency determining unit, the sampling frequency in the uplink communication from each RRU to the own device determined by the sampling frequency determining unit, The signal processing apparatus further includes a self-device-side sampling frequency restoration unit that restores the sampling frequency in analog / digital conversion in the RRU.

  Further, the present invention provides sampling for determining a sampling frequency for communication between the own device and each RRU based on the required bandwidth in communication between the own device and each RRU calculated in the required bandwidth calculation step. A frequency determination step further in parallel with the quantization bit number determination step, and a sampling frequency applied to downlink data from the own apparatus to each RRU is sampled in digital / analog conversion in each RRU In parallel with the self-device-side quantization bit number conversion step, a self-device-side sampling frequency conversion step for converting from a frequency to a sampling frequency in downlink communication from the self-device determined in the sampling frequency determination step to each RRU It is a signal processing method characterized by further providing.

  Further, the present invention provides sampling for determining a sampling frequency for communication between the own device and each RRU based on the required bandwidth in communication between the own device and each RRU calculated in the required bandwidth calculation step. A frequency determination step further in parallel with the quantization bit number determination step, and each RRU determined in the sampling frequency determination step is a sampling frequency applied to uplink data from each RRU to its own device. A self-device-side sampling frequency restoration step for restoring from the sampling frequency in uplink communication from the device to the own device to the sampling frequency in the analog / digital conversion in each RRU is further provided after the quantization bit number determining step. Is a signal processing method.

  According to this configuration, since the BBU reduces the sampling frequency according to the radio band, the total value of the required bands between the BBU and each RRU is instantiated by instantaneously increasing the traffic between the BBU and each RRU. It is possible to suppress exceeding the band of the section.

  In the distributed wireless communication base station system in which the functions of the wireless communication base station are divided into BBU and RRU and physically separated, the traffic between the BBU and each RRU increases instantaneously. It is possible to prevent the total value of the required bandwidth between BBU and each RRU from exceeding the bandwidth of the PON section.

It is a figure which shows the structure of a distributed radio | wireless communication base station system. It is a figure which shows the structure of RRU of related technology. It is a figure which shows the structure of BBU of related technology. It is a figure which shows the process of a distributed radio | wireless communication base station system. It is a figure which shows the structure of RRU of 1st-3rd embodiment. It is a figure which shows the structure of BBU of 1st-3rd embodiment. It is a figure which shows the reduction process of the quantization bit number of 1st Embodiment. It is a figure which shows the reduction process of the quantization bit number of 2nd Embodiment. It is a figure which shows the determination process of the modulation system / coding rate of 2nd Embodiment. It is a figure which shows the reduction process of the quantization bit number of 3rd Embodiment. It is a figure which shows the structure of RRU of 4th Embodiment. It is a figure which shows the structure of BBU of 4th Embodiment.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(First embodiment)
The configuration and processing of the distributed wireless communication base station system are the same as those shown in FIGS. That is, in the distributed radio communication base station system, the function of the base station that transmits and receives analog radio signals to and from the radio terminal is one BBU2, a plurality of RRU1-1, 1-2,..., 1-N, It is divided into And BBU2 and several RRU1-1, 1-2, ..., 1-N are connected using PON which transmits a digital optical signal. Here, BBU2 is connected to OLT4 in the PON, and each RRU1 is connected to each ONU3 in the PON.

  The configuration of the RRU of the first embodiment is shown in FIG. The RRU 1 of the first embodiment includes the quantization bit number information extraction unit 109U and the quantization bit number conversion unit 110U for the uplink in addition to the RRU 1 of the related technology, and the quantization bit number information extraction for the downlink. Part 109D and quantization bit number restoration part 110D.

  First, uplink will be described. The quantization bit number information extraction unit 109U acquires the quantization bit number in the uplink from the own apparatus 1 to the BBU 2 notified from the frame conversion unit 206D described later from the BBU 2. Specifically, the frame conversion unit 107D extracts a control signal, IQ data, and quantization bit number information from the received signal. Then, the quantized bit number information extracting unit 109U acquires the quantized bit number information from the frame converting unit 107D. The quantization bit number information extraction unit 109U corresponds to a quantization bit number acquisition unit.

  The quantization bit number conversion unit 110U determines the quantization bit number applied to the uplink data from the own device 1 to the BBU 2 from the quantization bit number in the A / D conversion unit 105U of the own device 1. The number information extraction unit 109U converts the acquired number of quantization bits in the uplink from the own device 1 to the BBU2. The quantization bit number conversion unit 110U corresponds to the RRU side quantization bit number conversion unit. Here, the number of quantization bits can be increased or decreased within a range where the required bandwidth of the PON uplink is not too large compared to the upper limit bandwidth of the PON. However, in the first embodiment, the number of quantization bits is reduced. A form to be performed will be described.

  Next, the downlink will be described. The quantization bit number information extraction unit 109D acquires the quantization bit number in the downlink from the BBU 2 to the own apparatus 1 notified from the frame conversion unit 206D described later from the BBU 2. Specifically, the frame conversion unit 107D extracts a control signal, IQ data, and quantization bit number information from the received signal. Then, the quantization bit number information extraction unit 109D acquires quantization bit number information from the frame conversion unit 107D. The quantization bit number information extraction unit 109D corresponds to a quantization bit number acquisition unit.

  The quantization bit number restoration unit 110D transmits the quantization bit number applied to the downlink data from the BBU 2 to the own device 1, and the downlink from the BBU 2 acquired by the quantization bit number information extraction unit 109D to the own device 1. Is restored to the number of quantization bits in the D / A conversion unit 105D of the device 1. The quantization bit number restoration unit 110D corresponds to the RRU side quantization bit number restoration unit. Here, the number of quantization bits can be increased or decreased within a range where the required bandwidth of the PON downlink is not too large compared to the upper limit bandwidth of the PON. In the first embodiment, the number of quantization bits is reduced. A form to be performed will be described.

  FIG. 6 shows the configuration of the BBU of the first embodiment. The BBU 2 of the first embodiment includes a required bandwidth calculation unit 209 and a quantization bit number determination unit 210 that are common to the downlink and the uplink in addition to the BBU 2 of the related technology. A number conversion unit 211D and a quantization bit number restoration unit 211U for the uplink.

  First, the downlink will be described. The required bandwidth calculation unit 209 calculates the required bandwidth in the downlink from the own device 2 to each RRU 1 and calculates the total value of the required bandwidths for a plurality of RRUs 1. Specifically, the required band calculation unit 209 determines the own apparatus 2 based on the radio band assigned to the downlink from the own apparatus 2 to each RRU 1 by the radio band allocation / coding rate / modulation method determination unit 201. To calculate the required bandwidth in the downlink to each RRU1.

  The quantization bit number determination unit 210 is configured so that the total value of the required bandwidths calculated by the required bandwidth calculation unit 209 does not exceed the upper limit value of the bandwidth in the downlink from the OLT 4 to the optical splitter 7 in the PON. To determine the number of quantization bits for the downlink from each RRU1. Specifically, the quantization bit number determination unit 210 performs processing described later in FIG.

  The quantization bit number conversion unit 211D determines the quantization bit number to be applied to the downlink data from the own device 2 to each RRU1, based on the quantization bit number in the D / A conversion unit 105D of each RRU1. The number determination unit 210 converts the number of quantization bits in the downlink from the own device 2 to each RRU 1 determined. The quantization bit number conversion unit 211D corresponds to the BBU side quantization bit number conversion unit. Here, the number of quantization bits can be increased or decreased within a range where the required bandwidth of the PON downlink is not too large compared to the upper limit bandwidth of the PON. In the first embodiment, the number of quantization bits is reduced. A form to be performed will be described.

  The frame conversion unit 206D notifies each RRU 1 of the number of quantization bits in the downlink from the device 2 to each RRU 1 determined by the quantization bit number determination unit 210. Specifically, the frame conversion unit 206D multiplexes IQ data, a control signal, and quantization bit number information. The frame conversion unit 206D corresponds to a quantization bit number notification unit.

  Next, uplink will be described. The required bandwidth calculation unit 209 calculates the required bandwidth in the uplink from each RRU 1 to the own device 2 and calculates the total value of the required bandwidth for a plurality of RRUs 1. Specifically, the required bandwidth calculation unit 209 determines whether the required bandwidth calculation unit 209 determines from each RRU 1 based on the wireless bandwidth allocated to the uplink from each RRU 1 to the own device 2 by the wireless bandwidth allocation / coding rate / modulation method determination unit 201. The required bandwidth in the uplink to the own device 2 is calculated. Alternatively, the required bandwidth calculation unit 209 may calculate the required bandwidth in the uplink from each RRU 1 to the own device 2 based on the bandwidth request transmitted from each ONU 3 to the OLT 4.

  The quantization bit number determination unit 210 determines whether the total value of the required bandwidth calculated by the required bandwidth calculation unit 209 does not exceed the upper limit value of the bandwidth in the uplink from the optical splitter 7 to the OLT 4 in the PON. The number of quantization bits is determined for the uplink to the own device 2. Specifically, the quantization bit number determination unit 210 performs processing described later in FIG.

  The quantization bit number restoration unit 211U determines the number of quantization bits to be applied to the uplink data from each RRU 1 to the own device 2 from each RRU 1 determined by the quantization bit number determination unit 210 to the own device 2. The number of quantization bits in the link is restored to the number of quantization bits in the A / D conversion unit 105U of each RRU1. The quantization bit number restoration unit 211U corresponds to the BBU side quantization bit number restoration unit. Here, the number of quantization bits can be increased or decreased within a range where the required bandwidth of the PON uplink is not too large compared to the upper limit bandwidth of the PON. However, in the first embodiment, the number of quantization bits is reduced. A form to be performed will be described.

  The frame conversion unit 206D notifies each RRU 1 of the number of quantization bits in the uplink from each RRU 1 to its own device 2 determined by the quantization bit number determination unit 210. Specifically, the frame conversion unit 206D multiplexes IQ data, a control signal, and quantization bit number information. The frame conversion unit 206D corresponds to a quantization bit number notification unit.

  FIG. 7 shows a quantization bit number reduction process according to the first embodiment. The quantization bit number reduction process is almost common in the uplink and downlink.

  The required bandwidth calculation unit 209 calculates the required bandwidth in communication between the own device 2 and each RRU 1 for each of the uplink and the downlink, and calculates the total value of the required bandwidth for a plurality of RRUs 1 (step S1).

  For each of the uplink and downlink, the quantization bit number determination unit 210 determines that the total required bandwidth calculated by the required bandwidth calculation unit 209 is the upper limit value of the bandwidth in communication between the OLT 4 and the optical splitter 7 in the PON. It is determined whether it is below (step S2).

  A description will be given of the case where the total value of the required bandwidths calculated by the required bandwidth calculation unit 209 for each of the uplink and the downlink is equal to or less than the upper limit value of the bandwidth in communication between the OLT 4 and the optical splitter 7 in the PON (step) YES in S2.

  For each of the uplink and the downlink, the quantization bit number determination unit 210 determines the quantization bit number between the BBU2 and each RRU1, and the quantization bit in the A / D conversion unit 105U and the D / A conversion unit 105D of each RRU1. The number is maintained and the process is terminated.

  For each of the uplink and the downlink, the case where the total value of the required bandwidths calculated by the required bandwidth calculation unit 209 exceeds the upper limit value of the bandwidth in the communication between the OLT 4 and the optical splitter 7 in the PON will be described (step S2). NO).

  For each of the uplink and the downlink, the quantization bit number determination unit 210 determines the quantization bit number between the BBU2 and each RRU1, and the quantization bit in the A / D conversion unit 105U and the D / A conversion unit 105D of each RRU1. The number is reduced by p (p = 1, 2, 3,...) Bits (step S3). Then, BBU2 repeats steps S1 and S2.

  For any communication between BBU2 and each RRU1, it is possible to arbitrarily select whether to reduce the number of quantization bits. For example, communication between BBU2 and each RRU1 may be selected at random, communication without high priority information may be selected, or may be selected depending on whether or not diversity is used in the wireless section. Good.

  As described above, BBU2 determines the number of quantization bits used for transmission between BBU2 and each RRU1 so that the total value of the required bandwidth between BBU2 and each RRU1 is equal to or less than the bandwidth of the PON section. Reduced from the number of quantization bits in / D conversion or D / A conversion.

  For the downlink, the BBU 2 reduces the number of quantization bits from the number of quantization bits in the D / A conversion to the number of quantization bits determined by the own device 2. Each RRU 1 restores the number of quantization bits to the number of quantization bits in the D / A conversion from the number of quantization bits determined by the BBU 2 and notified to the own device 1. The D / A conversion unit 105D and the baseband filter unit 106D may be configured to support both the number of quantization bits and the original number of quantization bits in the downlink from BBU2 to RRU1. The quantization bit number restoration unit 110D may be omitted, and the D / A conversion unit 105D and the baseband filter unit 106D are notified of quantization bit number information from the BBU2 via the frame conversion unit 107D. You may make it. That is, the D / A conversion unit 105D and the baseband filter unit 106D may perform restoration of the number of quantization bits.

  For the uplink, each RRU 1 reduces the number of quantization bits from the number of quantization bits in the A / D conversion to the number of quantization bits determined by the BBU 2 and notified to the own apparatus 1. Then, the BBU 2 restores the quantization bit number from the quantization bit number determined by the device 2 to the quantization bit number in the A / D conversion. The secondary demodulation unit 205U may be configured to support both the number of quantization bits and the original number of quantization bits in the uplink from RRU1 to BBU2. The quantization bit number restoration unit 211U may be omitted, and the secondary demodulation unit 205U may be notified of quantization bit number information from the quantization bit number determination unit 210. That is, the secondary demodulation unit 205U may perform the restoration of the number of quantization bits.

  In this way, in the distributed radio communication base station system in which the function of the radio communication base station is divided into BBU2 and RRU1 and physically separated, the traffic between BBU2 and each RRU1 increases instantaneously. It can suppress that the total value of the required band between BBU2-each RRU1 exceeds the band of a PON area.

(Second Embodiment)
The configuration and processing of the distributed wireless communication base station system are the same as those shown in FIGS. The configuration of RRU1 is the same as in FIG. The configuration of BBU2 is almost the same as that in FIG.

  In the first embodiment, every time the number of quantization bits is reduced by 1 bit, the reception SNR is deteriorated by 6 dB due to quantization noise. Therefore, even if a radio signal is received, demodulation may not be possible. Therefore, in the second embodiment, in addition to the first embodiment, the BBU 2 lowers the modulation scheme or lowers the coding rate so that the radio signal satisfies the required quality.

  The radio band allocation / coding rate / modulation method determining unit 201 determines the own device 2 and each of the own device 2 based on the number of quantization bits in communication between the own device 2 and each RRU 1 determined by the quantization bit number determining unit 210. At least one of the modulation scheme and the coding rate is determined for the communication between the own apparatus 1 and each RRU 2 so that the communication quality in the communication between the RRUs 1 satisfies the predetermined quality.

  FIG. 8 shows the quantization bit number reduction process of the second embodiment. The quantization bit number reduction process is almost common in the uplink and downlink. Steps S11, S12, and S13 are the same as steps S1, S2, and S3, respectively.

  For each of the uplink and the downlink, the total number of required bands calculated by the required band calculating unit 209 is reduced between the OLT 4 and the optical splitter 7 in the PON by reducing the number of quantization bits (step S13). When the communication bandwidth is equal to or lower than the upper limit of the bandwidth (YES in step S12), the following processing is performed.

  As shown in FIG. 9, radio band allocation / coding rate / modulation scheme determination section 201 takes into account that the received SNR has deteriorated due to the reduction in the number of quantization bits, and performs a new process based on channel quality information. Then, the received SNR is re-predicted, and the modulation scheme is lowered or the coding rate is lowered so that the radio signal satisfies the required quality (for example, error rate) (step S14).

  In this way, BBU2 demodulates even if a radio signal is received by reducing the number of quantization bits in order to lower the modulation scheme or lower the coding rate so that the radio signal satisfies the required quality. The possibility of not being able to be suppressed can be suppressed.

(Third embodiment)
The configuration and processing of the distributed wireless communication base station system are the same as those shown in FIGS. The configuration of RRU1 is the same as in FIG. The configuration of BBU2 is almost the same as that in FIG.

  In the second embodiment, by reducing the modulation scheme or lowering the coding rate, the frequency utilization efficiency (number of bits / 1 symbol) is degraded as shown in FIG. May not be satisfied. Therefore, in the third embodiment, in addition to the second embodiment, the BBU 2 reassigns the radio band so that the transmission rate satisfies the required rate.

  FIG. 10 shows a quantization bit number reduction process according to the third embodiment. The quantization bit number reduction process is almost common in the uplink and downlink. Steps S22, S23, S24, and S25 are the same as steps S11, S12, S13, and S14, respectively.

  The wireless band allocation / coding rate / modulation method determination unit 201 determines the own device 2 based on at least one of the modulation method and the coding rate in communication between the own device 2 and each RRU 1 determined in step S25. Then, the radio band is reassigned to the communication between the own apparatus 2 and each RRU 1 so that the transmission rate in the communication between each RRU 1 satisfies the requested rate (step S28). Then, BBU2 repeats steps S22 to S25 and S28.

However, since the above repeated operations may not converge, it is necessary to determine the maximum number of times j _th (j _th = 1, 2, 3,...) (Steps S21, S26). , S27). That is, step S28 is repeated only j _th times.

  In this way, since BBU2 reallocates the radio band so that the transmission rate satisfies the required rate, there is a possibility that the transmission rate may not satisfy the required rate by lowering the modulation scheme or lowering the coding rate. Can be suppressed.

(Fourth embodiment)
The configuration and processing of the distributed wireless communication base station system are the same as those shown in FIGS. In the first to third embodiments, the number of quantization bits is reduced. In the fourth embodiment, in addition to the first to third embodiments, the sampling frequency is reduced.

  The configuration of the RRU of the fourth embodiment is shown in FIG. The RRU 1 of the fourth embodiment includes a compression information extraction unit 111U and a compression unit 112U for the uplink in addition to the RRU 1 of the first to third embodiments, and an extension information extraction unit 111D and an extension unit for the downlink. 112D.

  First, uplink will be described. The compressed information extraction unit 111U acquires the sampling frequency in the uplink from the own device 1 to the BBU2 notified by the frame conversion unit 206D from the BBU2. Specifically, the frame conversion unit 107D extracts a control signal, IQ data, quantization bit number information, and sampling frequency information from the received signal. Then, the compressed information extraction unit 111U acquires sampling frequency information from the frame conversion unit 107D. The compressed information extraction unit 111U corresponds to a sampling frequency acquisition unit.

  The compression unit 112U obtains the sampling frequency applied to the uplink data from the own device 1 to the BBU 2 from the sampling frequency in the A / D conversion unit 105U of the own device 1 by the compressed information extraction unit 111U. To the sampling frequency in the uplink from BBU2. The compression unit 112U corresponds to the RRU side sampling frequency conversion unit. Here, the sampling frequency can be increased or decreased within a range in which the required bandwidth of the PON uplink is not too large compared to the upper limit bandwidth of the PON. In the fourth embodiment, a mode for reducing the sampling frequency will be described. To do.

  Next, the downlink will be described. The decompression information extraction unit 111D acquires the sampling frequency in the downlink from the BBU 2 to the own device 1 notified from the frame conversion unit 206D from the BBU 2. Specifically, the frame conversion unit 107D extracts a control signal, IQ data, quantization bit number information, and sampling frequency information from the received signal. Then, the decompression information extraction unit 111D acquires sampling frequency information from the frame conversion unit 107D. The decompression information extraction unit 111D corresponds to a sampling frequency acquisition unit.

  The decompression unit 112D determines the sampling frequency applied to the downlink data from the BBU 2 to the own device 1 based on the sampling frequency in the downlink from the BBU 2 to the own device 1 acquired by the decompression information extraction unit 111D. The sampling frequency in the D / A conversion unit 105D is restored. The decompression unit 112D corresponds to the RRU side sampling frequency restoration unit. Here, the sampling frequency can be increased or decreased within a range in which the required bandwidth of the PON downlink is not too large compared to the upper limit bandwidth of the PON. In the fourth embodiment, a mode for reducing the sampling frequency will be described. To do.

  The configuration of the BBU of the fourth embodiment is shown in FIG. BBU2 of 4th Embodiment has compression / decompression control part 212 in common with a downlink and an uplink in addition to BBU2 of 1st-3rd embodiment, and has compression part 213D about a downlink. For the uplink, the expansion unit 213U is provided.

  First, the downlink will be described. The compression / decompression control unit 212 determines the sampling frequency for the downlink from the own device 2 to each RRU 1 based on the required bandwidth in the downlink from the own device 2 to each RRU 1 calculated by the required bandwidth calculation unit 209. To do. The compression / decompression control unit 212 corresponds to a sampling frequency determination unit.

  The compression unit 213D determines the sampling frequency applied to the downlink data from the own device 2 to each RRU 1 based on the sampling frequency in the D / A conversion unit 105D of each RRU 1 by the compression / decompression control unit 212. 2 to the sampling frequency in the downlink from each RRU1. The compression unit 213D corresponds to the BBU side sampling frequency conversion unit. Here, the sampling frequency can be increased or decreased within a range in which the required bandwidth of the PON downlink is not too large compared to the upper limit bandwidth of the PON. In the fourth embodiment, a mode for reducing the sampling frequency will be described. To do.

  The frame conversion unit 206D notifies each RRU 1 of the downlink sampling frequency determined by the compression / decompression control unit 212 from the own device 2 to each RRU 1. Specifically, the frame conversion unit 206D multiplexes IQ data, a control signal, quantization bit number information, and sampling frequency information. The frame conversion unit 206D corresponds to a sampling frequency notification unit.

  Next, uplink will be described. The compression / decompression control unit 212 determines the sampling frequency for the uplink from each RRU 1 to the own device 2 based on the required bandwidth in the uplink from each RRU 1 to the own device 2 calculated by the required bandwidth calculation unit 209. To do. The compression / decompression control unit 212 corresponds to a sampling frequency determination unit.

  The decompression unit 213U determines the sampling frequency applied to the uplink data from each RRU 1 to the own device 2 from the sampling frequency in the uplink from each RRU 1 to the own device 2 determined by the compression / decompression control unit 212. The sampling frequency in the A / D conversion unit 105U of RRU1 is restored. The decompression unit 213U corresponds to the BBU side sampling frequency restoration unit. Here, the sampling frequency can be increased or decreased within a range in which the required bandwidth of the PON uplink is not too large compared to the upper limit bandwidth of the PON. In the fourth embodiment, a mode for reducing the sampling frequency will be described. To do.

  The frame conversion unit 206D notifies each RRU 1 of the sampling frequency in the uplink from each RRU 1 to the own device 2 determined by the compression / decompression control unit 212. Specifically, the frame conversion unit 206D multiplexes IQ data, a control signal, quantization bit number information, and sampling frequency information. The frame conversion unit 206D corresponds to a sampling frequency notification unit.

  First, as a compression process, consider the case where transmission is stopped, that is, the case where the sampling frequency is determined to be zero. When there is no radio band assigned to the wireless terminal, the compression / decompression control unit 212 issues a transmission stop command for the communication between the BBU2 and RRU1, that is, determines the sampling frequency to be 0. The compression unit 213D and the decompression unit 213U do not perform signal transmission for the communication between the BBU2 and RRU1.

  Next, consider a case where the sampling frequency is reduced as compression processing. The compression / decompression control unit 212 calculates how much the sampling frequency can be reduced based on the wireless band allocation information, and issues a command to the compression unit 213D and the expansion unit 213U. The compression unit 213D reduces the sampling frequency from the sampling frequency in the D / A conversion to the sampling frequency for which the command is issued. The decompressing unit 213U restores the sampling frequency to the sampling frequency in the A / D conversion from the sampling frequency for which the command has been issued.

  However, aliasing components are generated due to the reduction of the sampling frequency. Therefore, in each RRU1, the baseband filter units 106D and 106U need to acquire sampling frequency information from the decompression information extraction unit 111D and the compression information extraction unit 111U, change the filter coefficient, and remove the aliasing component, respectively. is there.

  In this way, since the BBU 2 reduces the sampling frequency according to the radio band, the total value of the required bands between the BBU 2 and each RRU 1 due to the instantaneous increase in traffic between the BBU 2 and each RRU 1 is the PON interval. Exceeding the bandwidth can be suppressed.

  The distributed wireless communication base station system, signal processing apparatus, and signal processing method according to the present invention are based on the fact that traffic between a BBU and each RRU increases instantaneously when an LTE signal is transmitted according to the CPRI standard. -It can apply in order to suppress that the total value of the required band between each RRU exceeds the band of a PON area.

1, 1-1, 1-2, 1-N: RRU
2: BBU
3, 3-1, 3-2, 3-N: ONU
4: OLT
5, 5-1, 5-2, 5-N: optical fiber 6: optical fiber 7: optical splitter 101: antenna 102: transmission / reception switching unit 103U: amplifier 104U: down-conversion unit 105U: A / D conversion unit 106U: base Band filter unit 107U: Frame conversion unit 108U: E / O conversion unit 109U: Quantization bit number information extraction unit 110U: Quantization bit number conversion unit 111U: Compression information extraction unit 112U: Compression unit 103D: Amplifier 104D: Up-conversion unit 105D: D / A conversion unit 106D: baseband filter unit 107D: frame conversion unit 108D: O / E conversion unit 109D: quantization bit number information extraction unit 110D: quantization bit number restoration unit 111D: decompression information extraction unit 112D: Decompression unit 201: Radio band allocation / coding rate / modulation method determination unit 202D: FEC coding 203D: Primary modulation unit 204D: Mapping unit 205D: Secondary modulation unit 206D: Frame conversion unit 207D: E / O conversion unit 202U: FEC decoding unit 203U: Primary demodulation unit 204U: Demapping unit 205U: Secondary demodulation unit 206U : Frame conversion unit 207U: O / E conversion unit 208: channel quality information extraction unit 209: required bandwidth calculation unit 210: quantization bit number determination unit 211D: quantization bit number conversion unit 211U: quantization bit number restoration unit 212: Compression / decompression control unit 213D: compression unit 213U: decompression unit

Claims (9)

A distributed radio in which the function of a base station that transmits and receives an analog radio signal to and from a radio terminal is divided into one signal processing device (BBU: Base Band Unit) and a plurality of radio devices (RRU: Remote Radio Unit). A communication base station system,
The BBU and the plurality of RRUs are connected using an optical subscriber communication network (PON: Passive Optical Network) that transmits a digital optical signal,
The BBU is connected to an optical subscriber line terminal (OLT) in the PON, and each RRU is connected to an optical network unit (ONU) in the PON. ,
The BBU is
A radio band allocating unit that allocates a radio band for communication between the own apparatus and each RRU;
A required bandwidth calculating unit that calculates a required bandwidth in communication between the own device and each of the RRUs, and calculates a total value of the required bandwidths for the plurality of RRUs;
Communication between the own apparatus and each RRU so that the total value of the required bands calculated by the required band calculation unit does not exceed the upper limit value of the band in communication between the OLT and the optical splitter in the PON. A quantization bit number determination unit that determines the quantization bit number for
A quantization bit number notifying unit for notifying each RRU of a quantization bit number in communication between the own apparatus determined by the quantization bit number determining unit and each RRU;
The own apparatus in which the quantization bit number determining unit determines the quantization bit number applied to the downlink data from the own apparatus to each RRU from the quantization bit number in the digital / analog conversion in each RRU. BBU side quantized bit number conversion unit for converting to a quantized bit number in downlink communication from each to the RRU,
Based on the number of quantization bits in communication between the own device and each RRU determined by the quantization bit number determination unit, the communication quality in communication between the own device and each RRU satisfies a predetermined quality. A modulation scheme / coding rate determination unit that determines at least one of a modulation scheme and a coding rate for communication between the own apparatus and each RRU ;
Each RRU is
A distributed wireless communication base station, comprising: a quantization bit number acquisition unit that acquires a quantization bit number in communication between the BBU notified by the quantization bit number notification unit and the device itself from the BBU. system. A distributed radio in which the function of a base station that transmits and receives an analog radio signal to and from a radio terminal is divided into one signal processing device (BBU: Base Band Unit) and a plurality of radio devices (RRU: Remote Radio Unit). A communication base station system,
The BBU and the plurality of RRUs are connected using an optical subscriber communication network (PON: Passive Optical Network) that transmits a digital optical signal,
The BBU is connected to an optical subscriber line terminal (OLT) in the PON, and each RRU is connected to an optical network unit (ONU) in the PON. ,
The BBU is
A radio band allocating unit that allocates a radio band for communication between the own apparatus and each RRU;
A required bandwidth calculating unit that calculates a required bandwidth in communication between the own device and each of the RRUs, and calculates a total value of the required bandwidths for the plurality of RRUs;
Communication between the own apparatus and each RRU so that the total value of the required bands calculated by the required band calculation unit does not exceed the upper limit value of the band in communication between the OLT and the optical splitter in the PON. A quantization bit number determination unit that determines the quantization bit number for
A quantization bit number notifying unit for notifying each RRU of a quantization bit number in communication between the own apparatus determined by the quantization bit number determining unit and each RRU;
Based on the number of quantization bits in communication between the own device and each RRU determined by the quantization bit number determination unit, the communication quality in communication between the own device and each RRU satisfies a predetermined quality. A modulation scheme / coding rate determination unit that determines at least one of a modulation scheme and a coding rate for communication between the own apparatus and each RRU ;
Each RRU is
A quantization bit number acquisition unit that acquires, from the BBU, a quantization bit number in communication between the BBU notified by the quantization bit number notification unit and the device itself;
The quantization bit number applied to the uplink data from the own device to the BBU is obtained from the own device obtained by the quantization bit number obtaining unit from the quantization bit number in the analog / digital conversion in the own device. A distributed radio communication base station system, comprising: an RRU side quantization bit number conversion unit that converts the number of quantization bits in uplink communication to BBU. In the BBU,
The radio band allocating unit is configured to use the own device and the coding method based on at least one of a modulation method and a coding rate in communication between the own device determined by the modulation method / coding rate determining unit and each RRU. 3. The distributed radio according to claim 1, wherein a radio band is allocated to communication between the RRU and the RRU so that a transmission rate in communication between the RRUs satisfies a requested rate. Communication base station system. A signal processing device that shares the function of a base station that transmits and receives an analog wireless signal with a wireless terminal, with a plurality of wireless devices (RRU).
Of the optical subscriber communication network (PON: Passive Optical Network) for transmitting digital optical signals, connected to an optical subscriber line terminating device (OLT: Optical Line Terminal),
A radio band allocating unit that allocates a radio band for communication between the own apparatus and each RRU;
A required bandwidth calculating unit that calculates a required bandwidth in communication between the own device and each of the RRUs, and calculates a total value of the required bandwidths for the plurality of RRUs;
Communication between the own apparatus and each RRU so that the total value of the required bands calculated by the required band calculation unit does not exceed the upper limit value of the band in communication between the OLT and the optical splitter in the PON. A quantization bit number determination unit that determines the quantization bit number for
The own apparatus in which the quantization bit number determining unit determines the quantization bit number applied to the downlink data from the own apparatus to each RRU from the quantization bit number in the digital / analog conversion in each RRU. A self-device-side quantized bit number conversion unit for converting to a quantized bit number in downlink communication from the RRU to each RRU;
Based on the number of quantization bits in communication between the own device and each RRU determined by the quantization bit number determination unit, the communication quality in communication between the own device and each RRU satisfies a predetermined quality. A modulation scheme / coding rate determination unit that determines at least one of a modulation scheme and a coding rate for communication between the own apparatus and each RRU;
A signal processing apparatus comprising: A signal processing device that shares the function of a base station that transmits and receives an analog wireless signal with a wireless terminal, with a plurality of wireless devices (RRU).
Of the optical subscriber communication network (PON: Passive Optical Network) for transmitting digital optical signals, connected to an optical subscriber line terminating device (OLT: Optical Line Terminal),
A radio band allocating unit that allocates a radio band for communication between the own apparatus and each RRU;
A required bandwidth calculating unit that calculates a required bandwidth in communication between the own device and each of the RRUs, and calculates a total value of the required bandwidths for the plurality of RRUs;
Communication between the own apparatus and each RRU so that the total value of the required bands calculated by the required band calculation unit does not exceed the upper limit value of the band in communication between the OLT and the optical splitter in the PON. A quantization bit number determination unit that determines the quantization bit number for
Based on the number of quantization bits in communication between the own device and each RRU determined by the quantization bit number determination unit, the communication quality in communication between the own device and each RRU satisfies a predetermined quality. A modulation scheme / coding rate determination unit that determines at least one of a modulation scheme and a coding rate for communication between the own apparatus and each RRU;
A signal processing apparatus comprising: The radio band allocating unit is configured to use the own device and the coding method based on at least one of a modulation method and a coding rate in communication between the own device determined by the modulation method / coding rate determining unit and each RRU. 6. The signal processing device according to claim 4, wherein a radio band is allocated to communication between the RRU and the RRU so that a transmission rate in communication between the RRUs satisfies a requested rate. . A signal processing method in one signal processing device (BBU: Base Band Unit) sharing the function of a base station that transmits and receives an analog wireless signal with a wireless terminal, with a plurality of wireless devices (RRU).
The own apparatus is connected to an optical subscriber line terminating device (OLT) in an optical subscriber communication network (PON: Passive Optical Network) that transmits a digital optical signal,
Based on a radio band assigned to communication between the own apparatus and each RRU, a required band in communication between the own apparatus and each RRU is calculated, and a total value of the required bands for the plurality of RRUs A required bandwidth calculating step for calculating
Communication between the own apparatus and each RRU so that the total value of the required bands calculated in the required band calculating step does not exceed the upper limit value of the band in the communication between the OLT and the optical splitter in the PON. A quantization bit number determination step for determining the quantization bit number for
Based on the number of quantization bits in communication between the own device and each RRU determined in the quantization bit number determination step, the communication quality in communication between the own device and each RRU satisfies a predetermined quality. A modulation scheme / coding rate determination step for determining at least one of a modulation scheme and a coding rate for communication between the own apparatus and each RRU;
The own apparatus which determined the quantization bit number applied to the downlink data from the own apparatus to each RRU from the quantization bit number in the digital / analog conversion in each RRU in the quantization bit number determination step A self-device-side quantization bit number conversion step for converting into a quantization bit number in downlink communication from each to the RRU;
In order. A signal processing method in one signal processing device (BBU: Base Band Unit) sharing the function of a base station that transmits and receives an analog wireless signal with a wireless terminal, with a plurality of wireless devices (RRU).
The own apparatus is connected to an optical subscriber line terminating device (OLT) in an optical subscriber communication network (PON: Passive Optical Network) that transmits a digital optical signal,
Based on a radio band assigned to communication between the own apparatus and each RRU, a required band in communication between the own apparatus and each RRU is calculated, and a total value of the required bands for the plurality of RRUs A required bandwidth calculating step for calculating
Communication between the own apparatus and each RRU so that the total value of the required bands calculated in the required band calculating step does not exceed the upper limit value of the band in the communication between the OLT and the optical splitter in the PON. A quantization bit number determination step for determining the quantization bit number for
Based on the number of quantization bits in communication between the own device and each RRU determined in the quantization bit number determination step, the communication quality in communication between the own device and each RRU satisfies a predetermined quality. A modulation scheme / coding rate determination step for determining at least one of a modulation scheme and a coding rate for communication between the own apparatus and each RRU;
In order. The required band calculation step includes the own device and the coding device based on at least one of a modulation method and a coding rate in communication between the own device determined in the modulation method / coding rate determination step and each RRU. 9. The signal processing method according to claim 7, wherein a radio band is allocated to communication between the RRU and the RRU so that a transmission rate in communication between the RRUs satisfies a requested rate. .

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