JP2015142229A - Slave station device, master station device and wireless base station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slave station device which can send a small amount of optical signals, when the volume of user data from a user device is small.SOLUTION: A slave station device connected with a master station device by an optical transmission line includes: a wireless reception unit for receiving wireless SC-FDMA signal of uplink from a user device; a Fourier transformation unit for transforming a digital signal in a time-domain derived from the wireless SC-FDMA signal into a frequency region signal; a data volume reduction unit for converting the frequency region signal into a reduced frequency region signal, by converting a resource block, to which the user data is not assigned, into a reduced resource block having a smaller data volume, in the frequency region signal.

Description

  The present invention relates to a slave station device, a master station device, and a radio base station that constitute a radio base station of a radio communication system.

  In a wireless communication system such as a mobile phone system, signal exchange between a user device such as a mobile phone terminal and a wireless base station is performed by wireless communication using radio waves. In a wireless communication system, a remote antenna unit (slave station apparatus, RAU) may be used to expand an area where wireless communication with a user apparatus is possible. Specifically, one or more slave station devices are connected to the baseband unit (master station device, BBU) of the radio base station, and the slave station device performs radio communication with the user device. By disposing such a slave station device in an area where radio waves of the radio base station do not reach, the service area is expanded. Typically, the slave station device is arranged in a high-rise building, an underground mall, a railway station, or the like. A slave station device (RAU) is also called an optical feeder radio device.

  In a radio base station, each slave station device and the master station device are typically connected by an optical fiber having a small signal transmission loss. For example, Patent Literature 1 discloses a wireless communication system in which each slave station device and the master station device are connected by an optical fiber. As described above, a technique of using an optical fiber for a part of a transmission path of a wireless communication system is known as a ROF (Radio over Fiber) technique.

  A radio frequency signal (RF signal) from the user apparatus is received by the antenna of the slave station apparatus and then optically transmitted to the master station apparatus via an interface such as an interface compliant with CPRI (Common Public Radio Interface).

  In LTE (Long Term Evolution) in 3GPP (Third Generation Partnership Project), SC-FDMA (Single Carrier Frequency Division Multiple Access) is used as an uplink radio access method in a radio section from a user apparatus to a radio base station. (Non-Patent Document 1).

JP 2013-183253 A

3GPP TS 36.300 V11.0.0 (2011-12), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 (Release 11), December 2011

  The amount of user data for uplink in the user equipment varies over time. That is, the load (load) of user data varies with time.

  However, in uplink SC-FDMA wireless transmission, the user equipment samples the time domain baseband signal at a constant sampling period and a constant number of quantization bits. Therefore, the amount of signal transmitted by the user apparatus in the radio section does not vary regardless of the variation in the amount of user data for uplink in the user apparatus. For this reason, in a radio base station in which a slave station device is connected to the master station device via an optical transmission line, a certain amount of signal is transmitted through the optical transmission line regardless of fluctuations in the amount of user data. In other words, even if the amount of user data in the user device is small, the bandwidth used in the optical transmission path is not reduced. Therefore, the slave station apparatus performs electro-optical conversion that requires electric power in order to transmit useless optical signals.

  Further, in a radio base station in which a plurality of slave station devices are connected to the master station device through an optical transmission line, a fixed wavelength is assigned to each slave station device. For this reason, the statistical multiplexing effect due to the interchange of wavelength resources among a plurality of slave station devices cannot be enjoyed.

  Therefore, the present invention provides a slave station device, a master station device, and a radio base station that solve at least one of the above-described problems.

  A slave station apparatus according to one aspect of the present invention is a slave station apparatus connected to the master station apparatus via an optical transmission line, and a radio receiver that receives an uplink radio SC-FDMA signal from a user apparatus; A Fourier transform unit that converts a time-domain digital signal derived from the wireless SC-FDMA signal into a frequency-domain signal, and a resource block to which no user data is allocated in the frequency-domain signal, a reduced resource with a smaller data amount A data amount reduction unit that converts the frequency domain signal into a reduced frequency domain signal by converting the block into a block, and an electro-optical converter that converts the reduced frequency domain signal into an optical signal.

  A slave station apparatus according to another aspect of the present invention is a slave station apparatus connected to the master station apparatus via an optical transmission line, and a radio receiver that receives an uplink radio SC-FDMA signal from a user apparatus A Fourier transform unit that converts a time domain digital signal derived from the wireless SC-FDMA signal into a frequency domain signal, and an inverse Fourier that transforms a frequency domain signal derived from the output from the Fourier transform unit into a time domain signal Data amount reduction for converting the time domain signal into a reduced time domain signal by converting a resource block to which user data is not allocated in the time domain signal into a reduced resource block having a smaller data quantity in the time domain signal And an electro-optical converter for converting the reduced time domain signal into an optical signal.

  A radio base station according to another aspect of the present invention includes a plurality of slave station devices connected to a master station device through an optical transmission line, and a plurality of optical signals transmitted from the plurality of slave station devices. A first wavelength division multiplexer that performs division multiplexing, wherein each of the slave station devices includes a radio reception unit that receives an uplink radio signal from a user device, and an optical signal having a different wavelength from each other. A plurality of electro-optic converters to be converted, a signal allocating section for assigning a digital signal derived from the radio signal to at least one of the plurality of electro-optic converters, and a plurality of outputs from the plurality of electro-optic converters A second wavelength division multiplexer that wavelength-division-multiplexes the optical signals of the series, the first wavelength division multiplexer from the second wavelength division multiplexer of the plurality of slave station devices Wave multiple output optical signals The electro-optic converter of the slave station device is divided and multiplexed, and the signal allocation unit of each of the plurality of slave station devices corresponds to a wavelength of the electro-optic converter that is not used in other slave station devices. The digital signal is assigned to.

  In the slave station apparatus according to one aspect of the present invention, the data amount reduction unit uses a resource block to which user data is not allocated in the frequency domain signal obtained by the Fourier transform unit as a reduced resource block with a smaller data amount. Is converted into a reduced frequency domain signal, and the electro-optic converter converts the reduced frequency domain signal into an optical signal. Therefore, when the amount of user data is small, a small amount of optical signal can be sent to the optical transmission line, and the power required for electro-optical conversion can be reduced.

  In the slave station device according to another aspect of the present invention, the data amount reduction unit has a smaller data amount for the resource block to which user data is not assigned in the time domain signal obtained by the inverse Fourier transform unit. By converting to a reduced resource block, the time domain signal is converted to a reduced time domain signal, and the electro-optic converter converts the reduced time domain signal to an optical signal. Therefore, when the amount of user data is small, a small amount of optical signal can be sent to the optical transmission line, and the power required for electro-optical conversion can be reduced.

  In the radio base station according to another aspect of the present invention, each signal allocation unit of the plurality of slave station devices corresponds to a wavelength of the electro-optic converter that is not used in the other slave station devices. The digital signal is assigned to the electro-optic converter of the slave station device. Therefore, a statistical multiplexing effect can be achieved by combining wavelength resources among a plurality of slave station devices.

It is the schematic which shows the radio | wireless communications system which concerns on various embodiment of this invention. It is a block diagram which shows the structure of the master station apparatus and slave station apparatus which concern on the 1st Embodiment of this invention. It is a figure which shows the format of the physical channel of the uplink in the radio area prescribed | regulated by LTE. It is a block diagram which shows the structure of the master station apparatus and slave station apparatus which concern on the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the master station apparatus and slave station apparatus which concern on the 3rd Embodiment of this invention. It is a block diagram which shows the structure of the main | base station apparatus and slave station apparatus which concern on the 4th Embodiment of this invention. It is a block diagram which shows the structure of the main | base station apparatus and slave station apparatus which concern on the 5th Embodiment of this invention. It is a block diagram which shows the structure of the main | base station apparatus and slave station apparatus which concern on the 6th Embodiment of this invention. It is a block diagram which shows the structure of the main | base station apparatus and slave station apparatus which concern on the 7th Embodiment of this invention. It is a block diagram which shows the structure of the main | base station apparatus and slave station apparatus which concern on the 8th Embodiment of this invention. It is a block diagram which shows the structure of the main | base station apparatus and slave station apparatus which concern on the 9th Embodiment of this invention. It is a block diagram which shows the structure of the wireless base station which concerns on the 10th Embodiment of this invention. It is a figure which shows the example of the usage condition of the wavelength channel of the some sub_station | mobile_unit apparatus in the wireless base station of FIG. It is a block diagram which shows the structure of the wireless base station which concerns on the 11th Embodiment of this invention.

Hereinafter, various embodiments according to the present invention will be described with reference to the accompanying drawings.
As shown in FIG. 1, the wireless communication system according to various embodiments of the present invention is a mobile phone system and includes a plurality of wireless base stations 1 and 3. The wireless base stations 1 and 3 can communicate with each other by wire or wirelessly. The radio communication system according to the present invention is a radio access technology system compliant with LTE. Each of the wireless base stations 1 and 3 can wirelessly communicate with a user equipment 6 that is a mobile terminal, and processes a signal transmitted from the user equipment 6 and a signal addressed to the user equipment 6.

  The radio base station 1 includes a master station device 2 (baseband unit, BBU) and a plurality of slave station devices 4 (remote antenna unit, RAU). For example, the master station device 2 may have a form of a board or a blade that can be attached to and detached from the radio base station 1. A plurality of slave station devices 4 (4a, 4b, 4c,...) Are connected to the master station device 2.

  The master station device 2 and each slave station device 4 are connected by an optical fiber, and these slave station devices 4 are remotely located from the master station device 2. The master station device 2 has a function of communicating with the slave station device 4. Each slave station device 4 can communicate with the master station device 2 via a corresponding optical fiber. In addition, the slave station device 4 has a wireless communication function, and thus can communicate with the user device 6.

  In downlink communication, the master station device 2 transmits a signal addressed to the user device 6 to all the slave station devices 4 connected to the master station device 2 via an optical fiber. The slave station device 4 transmits a signal to the user device 6 wirelessly. The user apparatus 6 demodulates and decodes a signal that can be received wirelessly from any of the slave station apparatuses 4.

  In uplink communication, a radio signal from the user apparatus 6 is received by a receivable slave station apparatus 4, and a signal received by the slave station apparatus 4 is transmitted to the master station apparatus 2 via an optical fiber. . When an uplink radio signal is received from one user apparatus 6 by a plurality of slave station apparatuses 4, the radio base station 1 selects a signal with good quality.

  Since the slave station device 4 is remotely located from the master station device 2, the service area of the radio base station 1 is expanded. The plurality of slave station devices 4 may be arranged in one building (for example, a high-rise building, an underground shopping center, or a railway station), or may be arranged in different buildings.

  As is clear from the above description, the master station device 2 and the slave station device 4 can be regarded as constituting one radio base station regardless of the distance between them.

First Embodiment FIG. 2 is a block diagram showing a configuration of a master station device 2 and a slave station device 4 according to a first embodiment. In FIG. 2, only the portion related to uplink communication is shown, and the other portions are not shown. For simplification of description, FIG. 2 shows only a single slave station device 4.

  As shown in FIG. 2, the slave station device 4 is connected to the master station device 2 through an optical fiber (optical transmission line) 5. The slave station apparatus 4 includes a reception antenna 40, a radio reception unit 42, an A / D (analog / digital) converter 44, a CP (cyclic prefix) removal unit 46, an S / P (serial / parallel) converter 48, an FFT (high speed). A Fourier transform unit 50, a P / S (parallel serial) converter 52, a data amount reduction unit 54, and an E / O (electrical light) converter 56 are provided.

  The reception antenna 40 receives an uplink radio SC-FDMA signal from the user apparatus 6. The A / D converter 44 converts the wireless SC-FDMA signal into a digital signal. The CP removal unit 46 has a benefit in the radio section between the user apparatus 6 and the slave station apparatus 4 from the digitized SC-FDMA signal, but is a CP (cyclic) that is information that does not need to be placed on the optical transmission line. (Prefix) is removed.

  The S / P converter 48 converts the time domain digital signal from which the CP is removed into a plurality of parallel signals for FFT. The FFT unit (Fourier transform unit) 50 converts these parallel signals into parallel frequency domain signals. The P / S converter 52 converts a parallel frequency domain signal into a serial signal for optical transmission to the master station device 2.

  The data amount reducing unit 54 converts the frequency domain signal output from the P / S converter 52 into a reduced resource block having a smaller data amount by converting a resource block to which user data is not allocated. Is converted to a reduced frequency domain signal. This conversion will be described later. The E / O converter 56 converts the reduced frequency domain signal into an optical signal and sends the optical signal to the optical fiber 5.

  The master station device 2 includes an O / E (photoelectric) converter 20, an RB (resource block) restoration unit 22, an S / P converter 24, a frequency equalization unit 26, and an IDFT (Inverse Discrete Fourier Transform) unit 28. Prepare.

  The O / E converter 20 converts the optical signal transmitted through the optical fiber 5 into a reduced frequency domain signal. The RB restoration unit 22 converts the reduced resource block into a frequency domain signal by converting the reduced resource block into a resource block to which user data is not allocated in the reduced frequency domain signal. Therefore, the RB restoration unit 22 restores the frequency domain signal output from the P / S converter 52 of the slave station device 4.

  The S / P converter 24 converts the serial frequency domain signal output from the RB restoration unit 22 into a parallel frequency domain signal. Therefore, the S / P converter 24 restores the parallel frequency domain signal output from the FFT unit 50 of the slave station device 4.

  The frequency equalization unit 26 performs frequency equalization of the frequency domain signal output from the S / P converter 24 and is affected by frequency selective fading in the radio section between the user apparatus 6 and the slave station apparatus 4. Suppresses noise in the received signal. The IDFT unit 28 converts the frequency domain signal output from the frequency equalizing unit 26 into a time domain baseband signal. The master station device 2 further includes a demodulator (not shown) and a decoder (not shown). The demodulator demodulates the time-domain baseband signal, and the decoder decodes the demodulated signal.

  Next, the conversion from the frequency domain signal to the reduced frequency domain signal by the data amount reduction unit 54 of the slave station device 4 will be described. FIG. 3 shows a format of an uplink physical channel in a radio section defined by LTE. The system band represented by the frequency can be divided into a plurality of resource block bands. The bandwidth of one resource block is 180 kHz.

  One radio frame (10 msec) can be divided into 10 subframes, and one subframe (1 msec) can be divided into two slots (0.5 msec). The time length of one resource block is one subframe (1 msec).

  The uplink control channel (PUCCH) for transmitting control information from the user apparatus 6 is arranged in resource blocks at both ends of the system band, and the uplink shared channel (PUSCH) for transmitting user data from the user apparatus 6 is Arranged in other resource blocks.

  The demodulation reference signal (DMRS) is used for demodulating user data transmitted from the user apparatus 6 at the radio base station 1. DMRS is also used for uplink channel estimation and other applications. DMRS is transmitted on PUCCH and PUSCH.

  The sounding reference signal (SRS) is used to measure uplink channel quality at the radio base station. SRS is transmitted on PUCCH and PUSCH. SRS is arranged in the last symbol of each subframe.

  The random access channel (PRACH) is used for the user apparatus 6 to establish a connection with the radio base station 1 for initial access or handover. PRACH is arranged in 6 resource blocks of a specific subframe determined by the radio base station 1.

  The amount of user data for uplink in the user equipment 6 varies with time. However, in uplink SC-FDMA wireless transmission, the user equipment 6 samples the time domain baseband signal at a constant sampling period and a constant number of quantization bits. Therefore, regardless of fluctuations in the amount of user data for uplink in the user apparatus 6, the amount of signals transmitted by the user apparatus 6 using PUSCH does not vary. When there is no uplink user data, the user apparatus 6 transmits an invalid signal (a signal not representing user data) using PUSCH. When there is no uplink user data, invalid signals on PUSCH may be deleted. The data amount reduction unit 54 of the slave station device 4 deletes such invalid signals. When there is no uplink user data, DMRS on PUSCH may be deleted. The data amount reduction unit 54 deletes the DMRS on the PUSCH when there is no uplink user data.

  On the other hand, the PUCCH signal, the PRACH signal, and the SRS must be transmitted from the user apparatus 6 to the radio base station 1 without fail. The data amount reduction unit 54 does not delete the PUCCH signal, the PRACH signal, and the SRS.

  As shown in the circle of FIG. 3, the resource blocks on the PUSCH (resource blocks other than the resource blocks for PRACH) have user data, DMRS, and SRS on the PUSCH. In the frequency domain signal output from the P / S converter 52, the data amount reduction unit 54 of the slave station device 4 converts a resource block to which user data is not assigned into a reduced resource block having a smaller data amount. Specifically, the reduced resource block has only SRS that should not be deleted. In other words, when the substantial user data is not included in the resource block, the data amount reduction unit 54 deletes the invalid user data equivalent part and the DMRS equivalent part in the resource block and represents only the SRS. Generate reduced resource blocks.

  In the reduced frequency domain signal output from the O / E converter 20, the RB restoration unit 22 of the master station device 2 selects a reduced resource block representing only SRS as a resource block to which no user data is assigned (invalid user data Equivalent part and DMRS equivalent part). Therefore, the RB restoration unit 22 restores the frequency domain signal (frequency domain signal before processing by the data amount reduction unit 54) output from the P / S converter 52 of the slave station device 4.

  As described above, in this embodiment, in the slave station device 4, the data amount reduction unit 54 uses the frequency domain signal obtained by the FFT unit 50 to extract a resource block to which user data has not been assigned more data amount. The frequency domain signal is converted into a reduced frequency domain signal by converting the reduced resource block into a reduced resource block, and the E / O converter 56 converts the reduced frequency domain signal into an optical signal. Therefore, when the amount of user data is small, a small amount of optical signal can be sent to the optical fiber 5, and the power required for electro-optical conversion can be reduced.

  In the master station device 2, in the reduced frequency domain signal output from the O / E converter 20 by the RB restoration unit 22, the reduced resource block is replaced with a resource block to which no user data is allocated (an invalid user data equivalent portion and a DMRS The reduced frequency domain signal is converted into a frequency domain signal. Therefore, the IDFT unit 28 can convert the frequency domain signal into a time domain baseband signal, in the same manner as the processing of a normal LTE uplink signal.

  The data amount reducing unit 54 can identify a resource block to which user data is not allocated based on uplink signal schedule information indicated in the downlink control signal transmitted from the master station device 2. Then, the data amount reducing unit 54 converts the identified resource block into a reduced resource block. Since the uplink signal schedule information indicates the resource block to which user data should be assigned for each user apparatus 6, the data amount reduction unit 54 is a resource to which no user data is assigned according to the uplink signal schedule information. A block can be specified. In the master station device 2, the RB restoration unit 22 uses a reduced resource block (a resource block to which no user data is allocated) in the reduced frequency domain signal output from the O / E converter 20 based on the uplink signal schedule information. And the identified reduced resource block can be converted into a resource block to which no user data is assigned.

Second Embodiment FIG. 4 is a block diagram showing configurations of a master station device 2 and a slave station device 4 according to a second embodiment of the present invention. In FIG. 4, only the part relevant to the uplink communication is shown, and the other parts are not shown. For simplification of explanation, FIG. 4 shows only a single slave station device 4. In FIG. 4, the same reference numerals are used to indicate the same components as those in the first embodiment (FIG. 2), and these components will not be described in detail.

  In addition to the configuration of the first embodiment, the slave station device 4 includes a received power measurement unit 58. The reception power measurement unit 58 measures the reception power of the radio SC-FDMA signal received by the radio reception unit 42.

  The data amount reduction unit 54 identifies a resource block to which user data is not allocated based on the power of the radio SC-FDMA signal received by the radio reception unit 42, and converts the identified resource block into a reduction resource block Thus, the frequency domain signal output from the P / S converter 52 is converted into a reduced frequency domain signal. Other components are the same as those in the first embodiment. The data amount reduction unit 54 can specify a resource block to which user data is not allocated by changing the power of the wireless SC-FDMA signal. In the master station device 2, the RB restoration unit 22 uses a reduced resource block (a resource block to which no user data is allocated) in the reduced frequency domain signal output from the O / E converter 20 based on the uplink signal schedule information. And the identified reduced resource block can be converted into a resource block to which user data is not allocated (including an invalid user data equivalent part and a DMRS equivalent part).

  In order to determine a resource block to which user data is not allocated, the data amount reduction unit 54 obtains an average of received power (instantaneous value) of 12 subcarriers constituting the resource block for each resource block. The average received power of the resource block may be compared with a threshold value. Alternatively, the data amount reduction unit 54 averages the received power (instantaneous value) of some subcarriers among the 12 subcarriers constituting the resource block, and compares the obtained average received power of the resource block with a threshold value. You can do it. A resource block whose average received power is lower than a threshold can be classified as a resource block to which user data is not allocated, and a resource block whose average received power is higher than a threshold can be classified as a resource block to which user data is allocated.

  Alternatively, the data amount reduction unit 54 averages the instantaneous value of the received power in each subcarrier in the range of the time length of one resource block to obtain the time average received power, and configures a resource block for each resource block The average received power of 12 subcarriers may be averaged, and the obtained average received power of the resource block may be compared with a threshold value. Alternatively, the data amount reduction unit 54 averages the time average received power of several subcarriers among the 12 subcarriers constituting the resource block, and compares the obtained average received power of the resource block with a threshold value. Good. A resource block whose average received power is lower than a threshold can be classified as a resource block to which user data is not allocated, and a resource block whose average received power is higher than a threshold can be classified as a resource block to which user data is allocated.

  Alternatively, the data amount reduction unit 54 may compare the maximum received power (which may be an instantaneous value or a time average value) of the subcarriers constituting each resource block with the threshold as the representative received power of the resource block. . A resource block whose maximum received power is lower than a threshold can be classified as a resource block to which user data is not allocated, and a resource block whose maximum received power is higher than a threshold can be classified as a resource block to which user data is allocated.

  The data amount reduction unit 54 obtains the corrected received power by multiplying or adding the received power (either the above average received power or the maximum received power) by a coefficient that changes depending on the situation, and is corrected. The received power may be compared with a threshold value.

Third Embodiment FIG. 5 is a block diagram showing configurations of a master station device 2 and a slave station device 4 according to a third embodiment of the present invention. In FIG. 5, only the portion related to uplink communication is shown, and the other portions are not shown. For simplification of explanation, FIG. 5 shows only a single slave station device 4. In FIG. 5, the same reference numerals are used to indicate the same components as those in the first embodiment (FIG. 2), and these components will not be described in detail.

  In addition to the configuration of the first embodiment, the slave station device 4 includes a reduced RB (resource block) information generation unit 60. The reduction RB information generation unit 60 generates reduction resource block information for identifying the reduction resource block actually obtained by the data amount reduction unit 54. In this embodiment, the reduced RB information generation unit 60 mixes or multiplexes the reduced resource block information with the reduced frequency domain signal output from the data amount reducing unit 54. Therefore, the E / O converter 56 transmits an optical signal including the reduced resource block information to the master station device 2.

  In the master station device 2, the RB restoration unit 22 determines the reduced resource block information from the electrical signal output from the O / E converter 20, and the RB restoration unit 22 performs the O / E conversion based on the reduced resource block information. A reduced resource block (corresponding to a resource block to which no user data is assigned) is identified in the reduced frequency domain signal output from the device 20, and the identified reduced resource block is assigned to a resource block to which no user data is assigned. (Including invalid user data equivalent part and DMRS equivalent part).

  In the first embodiment and the second embodiment, the RB restoration unit 22 of the master station device 2 identifies the reduced resource block based on the uplink signal schedule information. However, in the optical fiber 5 or the radio section, Due to this signal error, the uplink signal schedule information may not reach the slave station device 4. However, in the third embodiment, the reduced resource block information for identifying the reduced resource block actually obtained by the data amount reducing unit 54 of the slave station device 4 is transmitted from the slave station device 4 to the master station device 2. Therefore, the RB restoration unit 22 of the master station device 2 can reliably specify the reduced resource block in which the data amount is actually reduced in the slave station device 4.

  As in the first embodiment, the data amount reduction unit 54 of the slave station device 4 allocates user data based on the uplink signal schedule information indicated in the downlink control signal transmitted from the master station device 2. A resource block that is not assigned may be specified. As in the second embodiment, the data amount reduction unit 54 of the slave station device 4 is configured to use resource blocks to which user data is not allocated based on the power of the radio SC-FDMA signal received by the radio reception unit 42. May be specified.

Fourth Embodiment FIG. 6 is a block diagram showing configurations of a master station device 2 and a slave station device 4 according to a fourth embodiment of the present invention. In FIG. 6, only the portion related to uplink communication is shown, and the other portions are not shown. For simplification of description, FIG. 6 shows only a single slave station device 4. The fourth embodiment is an improvement over the third embodiment. In FIG. 6, the same reference numerals are used to indicate the same components as those in the third embodiment (FIG. 5), and these components will not be described in detail.

  In addition to the configuration of the third embodiment, the slave station device 4 includes an E / O converter (light emitting device) 56A and a WDM (wavelength division multiplexer) 62. The E / O converter 56A emits light having a wavelength different from the wavelength of the optical signal output from the E / O converter 56. The WDM 62 multiplexes a plurality of series of optical signals output from the plurality of E / O converters 56 and 56A. The optical signal output from the WDM 62 is transmitted to the master station device 2 through one optical fiber 5.

  In this embodiment, when the reduced RB information generating unit 60 generates reduced resource block information for identifying the reduced resource block actually obtained by the data amount reducing unit 54, the reduced RB information generating unit 60 generates an electric signal indicating the reduced resource block information as E / The O converter 56A is supplied. The E / O converter 56A converts this electric signal into an optical signal. Therefore, the reduced resource block information is transmitted to the master station device 2 using light having a wavelength different from the wavelength of the optical signal output from the E / O converter 56.

  In addition to the configuration of the third embodiment, the master station device 2 includes an O / E converter 20A and a WDM (wavelength demultiplexer) 29. The WDM 29 receives an optical signal from the slave station device 4, separates the optical signal into optical signals for each wavelength, and outputs two series of optical signals. The O / E converters 20 and 20A convert these two series of optical signals into electric signals. The O / E converter 20 corresponds to the E / O converter 56 of the slave station device 4 and outputs a reduced frequency domain signal. On the other hand, the O / E converter 20A corresponds to the E / O converter 56A of the slave station device 4, and outputs an electrical signal indicating the reduced resource block information.

  Based on the reduced resource block information output from the O / E converter 20A, the RB restoration unit 22 uses the reduced resource block (no user data is allocated) in the reduced frequency domain signal output from the O / E converter 20. And the identified reduced resource block can be converted into a resource block to which user data is not allocated (including an invalid user data equivalent part and a DMRS equivalent part). Thus, in this embodiment, the reduced frequency domain signal and the reduced resource block information are transmitted using two series of optical signals having different wavelengths. For this reason, in addition to the effect of the third embodiment, in this embodiment, the RB restoration unit 22 uses the reduced resource block information without the processing load of the determination of the reduced frequency domain signal and the reduced resource block information. The reduced resource block can be identified from the reduced frequency domain signal.

  As in the first embodiment, the data amount reduction unit 54 of the slave station device 4 allocates user data based on the uplink signal schedule information indicated in the downlink control signal transmitted from the master station device 2. A resource block that is not assigned may be specified. As in the second embodiment, the data amount reduction unit 54 of the slave station device 4 is configured to use resource blocks to which user data is not allocated based on the power of the radio SC-FDMA signal received by the radio reception unit 42. May be specified.

Fifth Embodiment FIG. 7 is a block diagram showing configurations of a master station device 2 and a slave station device 4 according to a fifth embodiment of the present invention. In FIG. 7, only the portion related to uplink communication is shown, and the other portions are not shown. For simplification of description, FIG. 7 shows only a single slave station device 4. In FIG. 7, the same reference numerals are used to indicate the same components as those in the first embodiment (FIG. 2), and these components will not be described in detail.

  In the first embodiment, the frequency equalization unit 26 is provided in the master station device 2. However, in the fifth embodiment, the frequency equalization unit 26 is not provided in the master station device 2. The slave station device 4 is provided with a frequency equalization unit 51. The frequency equalization unit 51 performs frequency equalization of the frequency domain signal output from the FFT unit 50, and the signal affected by the frequency selective fading in the radio section between the user apparatus 6 and the slave station apparatus 4 Suppresses noise. The P / S converter 52 converts the parallel frequency domain signal output from the frequency equalization unit 51 into a serial signal for optical transmission to the master station device 2.

  In the frequency domain signal (serial signal) output from the frequency equalization unit 51, the data amount reduction unit 54 converts a resource block to which user data is not allocated into a reduced resource block having a smaller data amount, Convert the frequency domain signal to a reduced frequency domain signal. In a manner similar to the data amount reduction unit 54 of the first embodiment, the data amount reduction unit 54 deletes invalid user data equivalent parts and DMRS equivalent parts in the resource block, and represents a reduced resource that represents only SRS The frequency domain signal is converted to a reduced frequency domain signal by generating a block.

  In the master station device 2, the reduced resource block representing only the SRS in the reduced frequency domain signal output from the O / E converter 20 by the RB restoration unit 22 is replaced with a resource block to which no user data is allocated (invalid user data The reduced frequency domain signal is converted into a frequency domain signal. The S / P converter 24 converts the serial frequency domain signal output from the RB restoration unit 22 into a parallel frequency domain signal. Therefore, the IDFT unit 28 can convert the frequency domain signal into a time domain baseband signal, in the same manner as the processing of a normal LTE uplink signal. The master station device 2 further includes a demodulator (not shown) and a decoder (not shown). The demodulator demodulates the time-domain baseband signal, and the decoder decodes the demodulated signal.

  Although the fifth embodiment is a modification of the first embodiment, the second to fourth embodiments may be similarly modified.

Sixth Embodiment FIG. 8 is a block diagram showing configurations of a master station device 2 and a slave station device 4 according to a sixth embodiment. In FIG. 8, only the portion related to uplink communication is shown, and the other portions are not shown. For simplification of description, FIG. 8 shows only a single slave station device 4.

  As shown in FIG. 8, the slave station device 4 is connected to the master station device 2 through an optical fiber 5. The slave station device 4 includes a reception antenna 140, a radio reception unit 142, an A / D converter 144, a CP removal unit 146, an S / P converter 148, an FFT unit 150, a frequency equalization unit 151, an IDFT unit 152, a data amount A reduction unit 154 and an E / O converter 156 are provided.

  The reception antenna 140 receives an uplink radio SC-FDMA signal from the user apparatus 6. The A / D converter 144 converts the wireless SC-FDMA signal into a digital signal. The CP removing unit 146 removes the CP, which is information that is beneficial in the wireless section between the user apparatus 6 and the slave station apparatus 4 but does not need to be placed on the optical transmission path, from the digitized SC-FDMA signal. .

  The S / P converter 148 converts the time domain digital signal from which the CP is removed into a plurality of parallel signals for FFT. An FFT unit (Fourier transform unit) 150 converts these parallel signals into parallel frequency domain signals.

  The frequency equalization unit 151 performs frequency equalization of the frequency domain signal output from the FFT unit 150, and outputs a signal affected by frequency selective fading in the radio section between the user apparatus 6 and the slave station apparatus 4. Suppresses noise. The IDFT unit 152 converts the frequency domain signal output from the frequency equalization unit 151 into a time domain baseband signal.

  The data amount reducing unit 154 converts the resource block to which user data is not allocated into a reduced resource block having a smaller data amount in the time domain signal output from the IDFT unit 152, thereby reducing the time domain signal to the reduced time. Convert to region signal. The E / O converter 156 converts the reduced time domain signal into an optical signal and sends the optical signal to the optical fiber 5.

  As described above with reference to FIG. 3 with respect to the first embodiment, when there is no uplink user data, an invalid signal on PUSCH (a signal not representing user data) may be deleted. DMRS on PUSCH may be deleted. On the other hand, the PUCCH signal, the PRACH signal, and the SRS must be transmitted from the user apparatus 6 to the radio base station 1 without fail. Therefore, in a method similar to the data amount reduction unit 54 of the first embodiment, the data amount reduction unit 154 deletes invalid user data equivalent parts and DMRS equivalent parts in the resource block, and represents only SRS. By generating resource blocks, the time domain signal is converted to a reduced time domain signal.

  The master station device 2 includes an O / E converter 120 and an RB restoration unit 122. The O / E converter 120 converts the optical signal transmitted through the optical fiber 5 into a reduced time domain signal. In the reduced time domain signal output from the O / E converter 20, the RB restoration unit 122 converts a reduced resource block representing only SRS into a resource block to which no user data is allocated (an invalid user data equivalent part and a DMRS equivalent part). A reduced time domain signal is converted to a time domain signal. Therefore, the RB restoration unit 122 restores the time-domain baseband signal (frequency domain signal before processing by the data amount reduction unit 154) output from the IDFT unit 152 of the slave station device 4. The master station device 2 further includes a demodulator (not shown) and a decoder (not shown). The demodulator demodulates the time-domain baseband signal, and the decoder decodes the demodulated signal.

  As described above, in this embodiment, in the slave station device 4, the data amount reduction unit 154 uses the time domain signal obtained by the IDFT unit 152 to extract a resource block to which user data has not been assigned more data amount. The time domain signal is converted into a reduced time domain signal by converting the reduced resource block into a reduced resource block, and the E / O converter 156 converts the reduced time domain signal into an optical signal. Therefore, when the amount of user data is small, a small amount of optical signal can be sent to the optical fiber 5, and the power required for electro-optical conversion can be reduced.

  In the master station device 2, the reduced resource block in the reduced time domain signal output from the O / E converter 120 by the RB restoration unit 122 is replaced with a resource block to which no user data is allocated (an invalid user data equivalent part and a DMRS). The reduced time domain signal is converted into a time domain signal. Therefore, the baseband signal in the time domain can be supplied to the demodulator in the same way as normal LTE uplink signal processing.

  In this embodiment, since the frequency equalization unit 151 and the IDFT unit 152 are arranged in the slave station device 4 that transmits a signal, a serial signal is supplied to the E / O converter 156 in the slave station device 4. Therefore, in the first embodiment (FIG. 2), the P / S converter 52 of the slave station apparatus 4 for supplying the serial signal to the E / O converter 56 can be excluded. Further, since the frequency equalization unit 151 is arranged in the slave station device 4, the S / P converter 24 of the master station device 2 can also be excluded. Therefore, the configuration of the slave station device 4 and the master station device 2 is simplified.

  The data amount reduction unit 154 can identify a resource block to which user data is not allocated based on the uplink signal schedule information indicated in the downlink control signal transmitted from the master station device 2. Then, the data amount reducing unit 154 converts the identified resource block into a reduced resource block. Since the uplink signal schedule information indicates the resource block to which user data should be allocated for each user apparatus 6, the data amount reduction unit 154 is a resource to which user data is not allocated according to the uplink signal schedule information. A block can be specified. In the master station device 2, the RB restoration unit 122 performs a reduction resource block (a resource block to which no user data is allocated) in the reduced frequency domain signal output from the O / E converter 120 based on the uplink signal schedule information. And the identified reduced resource block can be converted into a resource block to which no user data is assigned.

Seventh Embodiment FIG. 9 is a block diagram showing configurations of a master station device 2 and a slave station device 4 according to a seventh embodiment of the present invention. In FIG. 9, only the portion related to uplink communication is shown, and the other portions are not shown. For simplification of description, FIG. 9 shows only a single slave station device 4. In FIG. 9, the same reference numerals are used to indicate the same components as those in the sixth embodiment (FIG. 8), and these components will not be described in detail.

  In addition to the configuration of the sixth embodiment, the slave station device 4 includes a received power measurement unit 158. Reception power measuring section 158 measures the reception power of the radio SC-FDMA signal received by radio reception section 142.

  The data amount reduction unit 154 identifies a resource block to which user data is not allocated based on the power of the wireless SC-FDMA signal received by the wireless reception unit 142, and converts the identified resource block into a reduced resource block By doing so, the time domain signal output from the IDFT unit 152 is converted into a reduced time domain signal. Other components are the same as those in the sixth embodiment. The data amount reduction unit 154 can identify a resource block to which user data is not allocated by changing the power of the wireless SC-FDMA signal. In the master station device 2, the RB restoration unit 122 uses the reduced resource block (resource block to which no user data is allocated) in the reduced time domain signal output from the O / E converter 120 based on the uplink signal schedule information. And the identified reduced resource block can be converted into a resource block to which user data is not allocated (including an invalid user data equivalent part and a DMRS equivalent part).

  The method for discriminating resource blocks to which user data is not assigned by the data amount reducing unit 154 is the same as the method for discriminating resource blocks to which no user data is assigned by the data amount reducing unit 54 in the second embodiment. Good.

Eighth Embodiment FIG. 10 is a block diagram showing configurations of a master station device 2 and a slave station device 4 according to an eighth embodiment of the present invention. In FIG. 10, only the part related to uplink communication is shown, and the other parts are not shown. For simplification of description, FIG. 10 shows only a single slave station device 4. In FIG. 10, the same reference numerals are used to indicate the same components as those in the sixth embodiment (FIG. 8), and these components will not be described in detail.

  In addition to the configuration of the sixth embodiment, the slave station device 4 includes a reduced RB (resource block) information generation unit 160. The reduction RB information generation unit 160 generates reduction resource block information for identifying the reduction resource block actually obtained by the data amount reduction unit 154. In this embodiment, the reduced RB information generation unit 160 mixes or multiplexes the reduced resource block information with the reduced time domain signal output from the data amount reducing unit 154. Therefore, the E / O converter 56 transmits an optical signal including the reduced resource block information to the master station device 2.

  In the master station device 2, the RB restoration unit 122 determines the reduced resource block information from the electrical signal output from the O / E converter 120, and the RB restoration unit 122 performs the O / E conversion based on the reduced resource block information. A reduced resource block (corresponding to a resource block to which no user data is assigned) is identified in the reduced time domain signal output from the device 120, and the identified reduced resource block is assigned to a resource block to which no user data is assigned. (Including invalid user data equivalent part and DMRS equivalent part).

  In the sixth embodiment and the seventh embodiment, the RB restoration unit 122 of the master station device 2 identifies the reduced resource block based on the uplink signal schedule information. However, in the optical fiber 5 or the wireless section, Due to this signal error, the uplink signal schedule information may not reach the slave station device 4. However, in the eighth embodiment, the reduced resource block information for identifying the reduced resource block actually obtained by the data amount reducing unit 154 of the slave station device 4 is transmitted from the slave station device 4 to the master station device 2. Therefore, the RB restoration unit 122 of the master station device 2 can reliably specify the reduced resource block in which the data amount is actually reduced in the slave station device 4.

  As in the sixth embodiment, the data amount reduction unit 154 of the slave station device 4 allocates user data based on the uplink signal schedule information indicated in the downlink control signal transmitted from the master station device 2. A resource block that is not assigned may be specified. Similar to the seventh embodiment, the data amount reduction unit 154 of the slave station device 4 uses the power of the radio SC-FDMA signal received by the radio reception unit 42 to allocate resource blocks to which user data is not allocated. May be specified.

Ninth Embodiment FIG. 11 is a block diagram showing configurations of a master station device 2 and a slave station device 4 according to a ninth embodiment of the present invention. In FIG. 11, only the portion related to uplink communication is shown, and the other portions are not shown. For simplification of explanation, FIG. 11 shows only a single slave station device 4. The ninth embodiment is an improvement over the eighth embodiment. In FIG. 11, the same reference numerals are used to indicate the same components as those in the eighth embodiment (FIG. 10), and these components will not be described in detail.

  In addition to the configuration of the eighth embodiment, the slave station device 4 includes an E / O converter (light emitting device) 156A and a WDM (wavelength division multiplexer) 162. The E / O converter 156A emits light having a wavelength different from the wavelength of the optical signal output from the E / O converter 156. The WDM 162 multiplexes a plurality of series of optical signals output from the plurality of E / O converters 156 and 156A. The optical signal output from the WDM 162 is transmitted to the master station device 2 through one optical fiber 5.

  In this embodiment, when the reduced RB information generating unit 160 generates reduced resource block information for identifying the reduced resource block actually obtained by the data amount reducing unit 154, the reduced RB information generating unit 160 generates an electrical signal indicating the reduced resource block information as E / The O converter 156A is supplied. The E / O converter 156A converts this electric signal into an optical signal. Therefore, the reduced resource block information is transmitted to the master station device 2 using light having a wavelength different from the wavelength of the optical signal output from the E / O converter 156.

  In addition to the configuration of the eighth embodiment, the master station device 2 includes an O / E converter 120A and a WDM (wavelength demultiplexer) 129. The WDM 129 receives the optical signal from the slave station device 4, separates the optical signal into optical signals for each wavelength, and outputs two series of optical signals. The O / E converters 120 and 120A convert these two series of optical signals into electric signals. The O / E converter 120 corresponds to the E / O converter 156 of the slave station device 4 and outputs a reduced frequency domain signal. On the other hand, the O / E converter 120A corresponds to the E / O converter 156A of the slave station device 4, and outputs an electrical signal indicating the reduced resource block information.

  Based on the reduced resource block information output from the O / E converter 120A, the RB restoration unit 122 uses the reduced resource block (no user data is allocated) in the reduced frequency domain signal output from the O / E converter 120. And the identified reduced resource block can be converted into a resource block to which user data is not allocated (including an invalid user data equivalent part and a DMRS equivalent part). Thus, in this embodiment, the reduced frequency domain signal and the reduced resource block information are transmitted using two series of optical signals having different wavelengths. For this reason, in addition to the effect of the eighth embodiment, in this embodiment, the RB restoration unit 122 uses the reduced resource block information without the processing load of the determination of the reduced frequency domain signal and the reduced resource block information. The reduced resource block can be identified from the reduced frequency domain signal.

  As in the sixth embodiment, the data amount reduction unit 154 of the slave station device 4 allocates user data based on the uplink signal schedule information indicated in the downlink control signal transmitted from the master station device 2. A resource block that is not assigned may be specified. Similar to the seventh embodiment, the data amount reduction unit 154 of the slave station device 4 uses the power of the radio SC-FDMA signal received by the radio reception unit 142 to allocate resource blocks to which user data is not allocated. May be specified.

Tenth Embodiment FIG. 12 is a block diagram showing a configuration of a radio base station according to a tenth embodiment of the present invention. In FIG. 12, only the part related to uplink communication is shown, and the other parts are not shown. For simplification of explanation, FIG. 12 shows two slave station devices 4 (4a, 4b) and two master station devices 2 (2a, 2b), but the radio base station includes three or more slave station devices 4 Or one or three or more master station devices 2 may be included. In FIG. 12, the same reference numerals are used to indicate the same components as those in the first embodiment (FIG. 2), and these components will not be described in detail.

  The slave station devices 4a and 4b are connected to the master station devices 2a and 2b via a WDM (first wavelength division multiplexer) 80, one optical fiber 5, and a WDM (first wavelength demultiplexer) 90. It is connected. Each slave station device 4 includes a scheduler (signal allocation unit) 70, a WDM (second wavelength division multiplexer) 74, and a plurality of E / O converters 72a to 72d.

  The E / O converters 72a to 72d convert the digital signals into optical signals having different wavelengths. The scheduler 70 assigns the frequency domain signal (digital signal) output from the P / S converter 52 to at least one of the plurality of E / O converters 72a to 72d. The WDM 74 wavelength division multiplexes a plurality of series of optical signals with different wavelengths output from the plurality of E / O converters 72a to 72d.

  In different slave station apparatuses 4, E / O converters indicated by the same reference numerals emit optical signals having the same wavelength. For example, the wavelength of the output light of the E / O converter 72a of the slave station device 4a is the same as the wavelength of the output light of the E / O converter 72a of the slave station device 4b.

  The WDM 80 wavelength-division-multiplexes a plurality of series of optical signals transmitted from the plurality of slave station devices 4 a and 4 b and transmits them to one optical fiber 5. The WDM 90 receives an optical signal from the optical fiber 5, separates the optical signal into optical signals for each wavelength, and outputs a plurality of series of optical signals. These plural series of optical signals are supplied to the master station devices 2a and 2b.

  Each master station device 2 includes a WDM (second wavelength demultiplexer) 30, a plurality of O / E converters 31 a to 31 d, and a scheduler 32. The WDM 30 further separates the optical signal output from the WDM 90 into optical signals for each wavelength, and outputs a plurality of series of optical signals having different wavelengths. The O / E converters 31a to 31d correspond to light of different wavelengths, and correspond to the E / O converters 72a to 72d of the slave station device 4, respectively. For example, the O / E converter 31a converts the output light of the E / O converter 72a into an electric signal, and the O / E converter 31b converts the output light of the E / O converter 72b into an electric signal.

  In this embodiment, not all E / O converters 72a to 72d are always used in each slave station device 4. Any or all of the E / O converters 72a to 72d of each slave station device 4 may be deactivated. The scheduler 70 of each slave station device 4 sends a frequency domain signal (digital signal) to the E / O converter of the slave station device 4 corresponding to the wavelength of the E / O converter that is not used in the other slave station devices 4. ). For example, when the E / O converters 72a and 72b of the slave station device 4a are used, the scheduler 70 of the slave station device 4b is connected to either or both of the E / O converters 72c and 72d of the slave station device 4b. A digital signal output from the P / S converter 52 can be assigned.

  FIG. 13 shows an example of the usage status of the wavelength channels of the slave station devices 4a and 4b in the radio base station of FIG. The wavelength channel λa corresponds to the wavelength of the output light from the E / O converter 72a, the wavelength channel λb corresponds to the wavelength of the output light from the E / O converter 72b, and the wavelength channel λc corresponds to the output of the E / O converter 72c. Corresponding to the wavelength of light, the wavelength channel λd corresponds to the wavelength of the output light of the E / O converter 72d. As a result of the operation of the scheduler 70 of the slave station apparatuses 4a and 4b, the slave station apparatuses 4a and 4b use different wavelength channels at each time. For example, at time t1, the scheduler 70 of the slave station device 4a operates the E / O converters 72a and 72b of the slave station device 4a to use the wavelength channels λa and λb, and the scheduler 70 of the slave station device 4b The wavelength channels λc and λd are used by operating the E / O converters 72c and 72d of the slave station device 4b. At time t3, the scheduler 70 of the slave station device 4a operates the E / O converters 72a and 72b of the slave station device 4a to use the wavelength channels λa and λb, and the scheduler 70 of the slave station device 4b The wavelength channel λc is used by operating the E / O converter 72c of the apparatus 4b. At time t7, the scheduler 70 of the slave station device 4a operates the E / O converters 72a to 72d of the slave station device 4a to use the wavelength channels λa to λd, and the scheduler 70 of the slave station device 4b All the E / O converters 72a to 72d of the device 4b are deactivated, and any wavelength channel λ is not used.

  The schedulers 70 of the slave station devices 4a and 4b exchange scheduling results indicating the E / O converters to be operated with each other, and are used by the wavelength channel used by one slave station device 4 and the other slave station device 4. You may cooperate so that the wavelength channel used may not correspond. In this case, the scheduler 70 of each slave station device 4 preferably reports the scheduling result to each master station device 2 by optical transmission. Alternatively, by separately programming each scheduler 70, the schedulers 70 of the slave station apparatuses 4 a and 4 b do not exchange scheduling results with each other, and the E / C corresponding to the wavelength channel that is not used by the other slave station apparatuses 4. The O converter may be activated.

  The length of time for which the scheduler 70 of the slave station device 4 changes the E / O converter 72 used for optical transmission (the length of time t1, t2,... In FIG. 13) is arbitrary. The length of this time may be several seconds or several hours, for example. Further, at a time when the use of wireless communication is low (for example, at midnight), the slave station device 4 may deactivate a specific E / O converter 72 to save power consumption. For example, the slave station device 4a may operate only the E / O converter 72a and the slave station device 4b may operate only the E / O converter 72c when the wireless communication is not used.

  The scheduler (assignment signal recognition unit) 32 of each master station device 2 uses, for example, the slave station device from the electrical signals output from the O / E converters 31 a to 31 d according to the scheduling result reported from each slave station device 4. The serial frequency domain signal output from the four P / S converters 52 is restored. Alternatively, programming consistent with programming for the scheduler 70 of each slave station device 4 may be performed on the scheduler 32 of each master station device 2. In this case, according to the programming without receiving a report of the scheduling result from the slave station device 4. The scheduler 32 may restore the serial frequency domain signal output from the P / S converter 52 of the slave station device 4 from the electrical signals output from the O / E converters 31a to 31d.

  The S / P converter 24 converts the serial frequency domain signal output from the scheduler 32 into a parallel frequency domain signal. Therefore, the S / P converter 24 restores the parallel frequency domain signal output from the FFT unit 50 of the slave station device 4.

  The frequency equalization unit 26 performs frequency equalization of the frequency domain signal output from the S / P converter 24 and is affected by frequency selective fading in the radio section between the user apparatus 6 and the slave station apparatus 4. Suppresses noise in the received signal. The IDFT unit 28 converts the frequency domain signal output from the frequency equalizing unit 26 into a time domain baseband signal. The master station device 2 further includes a demodulator (not shown) and a decoder (not shown). The demodulator demodulates the time-domain baseband signal, and the decoder decodes the demodulated signal.

  As described above, in the radio base station according to this embodiment, the scheduler 70 of each of the plurality of slave station devices 4a and 4b has the wavelength of the E / O converter 72 that is not used in other slave station devices. A digital signal is assigned to the corresponding E / O converter 72 of the slave station device. Therefore, a statistical multiplexing effect can be exhibited by combining wavelength resources between the plurality of slave station apparatuses 4a and 4b.

  In this embodiment, unlike the first embodiment (see FIG. 2), each slave station device 4 does not have the data amount reduction unit 54, and each master station device 2 has the RB restoration unit 22. Not. However, as in the first embodiment, each slave station device 4 may have a data amount reduction unit 54, and each master station device 2 may have an RB restoration unit 22. In this case, each slave station device 4 and each master station device 2 may be modified similarly to the second to fifth embodiments (see FIGS. 4 to 7).

Eleventh Embodiment FIG. 14 is a block diagram showing a configuration of a radio base station according to an eleventh embodiment of the present invention. In FIG. 14, only the portion related to uplink communication is shown, and the other portions are not shown. For simplification of explanation, FIG. 14 shows two slave station apparatuses 4 (4a, 4b) and two master station apparatuses 2 (2a, 2b), but the radio base station has three or more slave station apparatuses 4 Or one or three or more master station devices 2 may be included. In FIG. 14, the same reference numerals are used to indicate the same components as those in the sixth embodiment (FIG. 8), and these components will not be described in detail.

  The slave station devices 4a and 4b are connected to the master station devices 2a and 2b via a WDM (first wavelength division multiplexer) 180, one optical fiber 5, and a WDM (first wavelength demultiplexer) 190. It is connected. Each slave station device 4 includes a scheduler (signal allocation unit) 170, a WDM (second wavelength division multiplexer) 174, and a plurality of E / O converters 172a to 172d.

  The E / O converters 172a to 172d convert the digital signals into optical signals having different wavelengths. The scheduler 170 assigns the time domain signal (digital signal) output from the IDFT unit 152 to at least one of the plurality of E / O converters 172a to 172d. The WDM 174 wavelength division multiplexes a plurality of series of optical signals having different wavelengths output from the plurality of E / O converters 172a to 172d.

  In different slave station apparatuses 4, E / O converters indicated by the same reference numerals emit optical signals having the same wavelength. For example, the wavelength of the output light of the E / O converter 172a of the slave station device 4a is the same as the wavelength of the output light of the E / O converter 172a of the slave station device 4b.

  The WDM 180 wavelength-division-multiplexes a plurality of series of optical signals transmitted from the plurality of slave station apparatuses 4 a and 4 b and transmits them to one optical fiber 5. The WDM 190 receives an optical signal from the optical fiber 5, separates the optical signal into optical signals for each wavelength, and outputs a plurality of series of optical signals. These plural series of optical signals are supplied to the master station devices 2a and 2b.

  Each master station device 2 includes a WDM (second wavelength demultiplexer) 130, a plurality of O / E converters 131 a to 131 d, and a scheduler 132. The WDM 130 further separates the optical signal output from the WDM 190 into optical signals for each wavelength, and outputs a plurality of series of optical signals having different wavelengths. The O / E converters 131a to 131d correspond to light of different wavelengths, and correspond to the E / O converters 172a to 172d of the slave station device 4, respectively. For example, the O / E converter 131a converts the output light from the E / O converter 172a into an electrical signal, and the O / E converter 131b converts the output light from the E / O converter 172b into an electrical signal.

  In this embodiment, all the E / O converters 172a to 72d are not always used in each slave station device 4. Any or all of the E / O converters 172a to 72d of each slave station device 4 may be deactivated. The scheduler 170 of each slave station device 4 sends a time domain signal (digital signal) to the E / O converter of the slave station device 4 corresponding to the wavelength of the E / O converter that is not used in the other slave station devices 4. ). For example, when the E / O converters 172a and 172b of the slave station device 4a are used, the scheduler 170 of the slave station device 4b is connected to either or both of the E / O converters 172c and 172d of the slave station device 4b. A digital signal output from the IDFT unit 152 can be assigned.

  An example of the usage status of the wavelength channels of the slave station devices 4a and 4b in the radio base station of FIG. 14 may be the same as the example described above in connection with the tenth embodiment with reference to FIG. The schedulers 170 of the slave station devices 4a and 4b exchange scheduling results indicating E / O converters to be operated with each other, and are used by the wavelength channel used by one slave station device 4 and the other slave station device 4 You may cooperate so that the wavelength channel used may not correspond. In this case, the scheduler 170 of each slave station device 4 preferably reports the scheduling result to each master station device 2 by optical transmission. Alternatively, by separately programming each scheduler 170, the schedulers 170 of the slave station apparatuses 4a and 4b do not exchange scheduling results with each other, and the E / Cs corresponding to the wavelength channels not used by other slave station apparatuses 4 can be obtained. The O converter may be activated.

  The length of time for which the scheduler 170 of the slave station device 4 changes the E / O converter 172 used for optical transmission (the length of time t1, t2,... In FIG. 13) is arbitrary. The length of this time may be several seconds or several hours, for example. Further, at a time when the use of wireless communication is low (for example, at midnight), the slave station device 4 may deactivate a specific E / O converter 172 to save power consumption. For example, the slave station device 4a may operate only the E / O converter 172a and the slave station device 4b may operate only the E / O converter 172c when the wireless communication is not used.

  The scheduler (assignment signal recognition unit) 132 of each master station apparatus 2 uses, for example, the slave station apparatus from the electrical signals output from the O / E converters 131a to 131d according to the scheduling result reported from each slave station apparatus 4. 4 restores the serial time-domain baseband signal output from the IDFT unit 152. Alternatively, programming consistent with programming for the scheduler 170 of each slave station device 4 may be performed on the scheduler 132 of each master station device 2, and in this case, according to the programming without receiving a report of the scheduling result from the slave station device 4. The scheduler 132 may restore the serial time-domain baseband signal output from the IDFT unit 152 of the slave station device 4 from the electrical signals output from the O / E converters 31a to 31d. The master station device 2 further includes a demodulator (not shown) and a decoder (not shown). The demodulator demodulates the time-domain baseband signal, and the decoder decodes the demodulated signal.

  As described above, in the radio base station according to this embodiment, the scheduler 170 of each of the plurality of slave station devices 4a and 4b has the wavelength of the E / O converter 172 that is not used in other slave station devices. A digital signal is assigned to the corresponding E / O converter 172 of the slave station device. Therefore, a statistical multiplexing effect can be exhibited by combining wavelength resources between the plurality of slave station apparatuses 4a and 4b.

  In this embodiment, unlike the sixth embodiment (FIG. 8), each slave station device 4 does not have the data amount reduction unit 154, and each master station device 2 has the RB restoration unit 122. Absent. However, as in the sixth embodiment, each slave station device 4 may have a data amount reduction unit 154, and each master station device 2 may have an RB restoration unit 122. In this case, each slave station device 4 and each master station device 2 may be modified similarly to the seventh to ninth embodiments (see FIGS. 9 to 11).

Other Modifications The above-described embodiments and modifications may be combined as long as there is no contradiction.

  In the above embodiment, FFT and DFT can be replaced. Therefore, in the first to fifth and tenth embodiments, the FFT unit 50 may be replaced with a DFT unit, and the IDFT unit 28 may be replaced with an IFFT unit. In the sixth to ninth and eleventh embodiments, the FFT unit 150 may be replaced with a DFT unit, and the IDFT unit 152 may be replaced with an IFFT unit.

1,3 Radio base stations 2, 2a, 2b Master station devices 4, 4a, 4b Slave station device 6 User device 5 Optical fiber (optical transmission line)
20, 20A, 120, 120A, 31a to 31d, 131a to 131d O / E (photoelectric) converter 22, 122 RB (resource block) restoration unit 24 S / P converter 26 Frequency equalization unit 28 IDFT (inverse discrete) (Fourier transform) section (Inverse Fourier transform section)
29,129 WDM (wavelength demultiplexer)
30,130 WDM (second wavelength demultiplexer)
32,132 Scheduler (assignment signal recognition unit)
40, 140 Reception antennas 42, 142 Wireless reception units 44, 144 A / D (analog / digital) converters 46, 146 CP (cyclic prefix) removal units 48, 148 S / P (serial parallel) converters 50, 150 FFT (Fast Fourier transform) section (Fourier transform section)
51, 151 Frequency equalization unit 52 P / S (parallel serial) converter 54, 154 Data amount reduction unit 56, 156, 72a to 72d, 172a to 172d E / O (electrical light) converter 56A, 156A E / O Converter (light emitting device)
58,158 Received power measurement unit 60,160 Reduced RB (resource block) information generation unit 62,162 WDM (wavelength division multiplexer)
152 IDFT units 70 and 170 Scheduler (signal allocation unit)
74,174 WDM (second wavelength division multiplexer)
80,180 WDM (first wavelength division multiplexer)
90,190 WDM (first wavelength demultiplexer)

Claims (11)

A slave station device connected to the master station device via an optical transmission line,
A radio reception unit for receiving an uplink radio SC-FDMA signal from a user apparatus;
A Fourier transform unit for converting a time domain digital signal derived from the wireless SC-FDMA signal into a frequency domain signal;
A data amount reduction unit that converts the frequency domain signal into a reduced frequency domain signal by converting a resource block to which no user data is allocated in the frequency domain signal into a reduced resource block having a smaller data quantity;
A slave station apparatus comprising: an electro-optical converter that converts the reduced frequency domain signal into an optical signal. A slave station device connected to the master station device via an optical transmission line,
A radio reception unit for receiving an uplink radio SC-FDMA signal from a user apparatus;
A Fourier transform unit for converting a time domain digital signal derived from the wireless SC-FDMA signal into a frequency domain signal;
An inverse Fourier transform unit for transforming a frequency domain signal derived from an output from the Fourier transform unit into a time domain signal;
In the time domain signal, a data amount reducing unit that converts the time domain signal into a reduced time domain signal by converting a resource block to which user data is not allocated into a reduced resource block having a smaller data amount;
A slave station apparatus comprising: an electro-optical converter that converts the reduced time domain signal into an optical signal. The data amount reduction unit identifies a resource block to which user data is not allocated based on uplink signal schedule information indicated in a downlink control signal transmitted from the master station device. The slave station apparatus according to claim 1 or 2. 3. The slave station apparatus according to claim 1, wherein the data amount reduction unit identifies a resource block to which user data is not allocated based on the power of the radio SC-FDMA signal. 2. The reduced resource block information generating unit that generates reduced resource block information for notifying the master station device of the reduced resource block actually obtained by the data amount reducing unit. 5. The slave station device according to any one of 4 above. It further comprises a light emitting device that emits light having a wavelength different from the wavelength of the optical signal output from the electro-optic converter for optically transmitting the reduced resource block information to the master station device. The slave station apparatus according to claim 5. A master station device connected to the slave station device according to claim 1 through an optical transmission line,
A photoelectric converter that converts the optical signal transmitted through the optical transmission path into a reduced frequency domain signal;
In the reduced frequency domain signal, a resource block restoration unit that converts the reduced frequency domain signal into a frequency domain signal by converting a reduced resource block into a resource block to which user data is not allocated, and
A master station apparatus comprising: an inverse Fourier transform unit that transforms a frequency domain signal derived from an output from the resource block restoration unit into a time domain signal. A master station device connected to the slave station device according to claim 2 through an optical transmission line,
A photoelectric converter that converts the optical signal transmitted through the optical transmission path into a reduced time domain signal;
A resource block restoration unit that converts the reduced time domain signal into a time domain signal by converting the reduced resource block into a resource block to which no user data is assigned in the reduced time domain signal; Master station device. Based on the reduced resource block information transmitted from the slave station device and identifying the reduced resource block actually obtained by the data amount reducing unit, the resource block restoration unit specifies the reduced resource block. 9. The master station apparatus according to claim 7, wherein the master station apparatus is characterized. A plurality of slave station devices according to any one of claims 1 to 6, connected to the master station device via an optical transmission line,
A first wavelength division multiplexer that wavelength-division multiplexes a plurality of optical signals transmitted from the plurality of slave station devices;
Each of the slave station devices
A plurality of electro-optic converters for converting digital signals into optical signals of different wavelengths,
A signal allocating unit that allocates a digital signal derived from the wireless SC-FDMA signal received by the wireless receiving unit to at least one of the plurality of electro-optic converters;
A second wavelength division multiplexer that wavelength-division multiplexes a plurality of series of optical signals output from the plurality of electro-optical converters;
The first wavelength division multiplexer wavelength division multiplexes a plurality of series of optical signals output from the second wavelength division multiplexer of the plurality of slave station devices,
The signal allocating unit of each of the plurality of slave station devices includes the digital signal to the electro-optic converter of the slave station device corresponding to the wavelength of the electro-optic converter that is not used in another slave station device. A radio base station characterized in that A plurality of slave station devices connected to the master station device via an optical transmission line;
A first wavelength division multiplexer that wavelength-division multiplexes a plurality of optical signals transmitted from the plurality of slave station devices;
Each of the slave station devices
A radio reception unit for receiving uplink radio signals from the user equipment;
A plurality of electro-optic converters for converting digital signals into optical signals of different wavelengths,
A signal allocation unit that allocates a digital signal derived from the radio signal to at least one of the plurality of electro-optical converters;
A second wavelength division multiplexer that wavelength-division multiplexes a plurality of series of optical signals output from the plurality of electro-optical converters;
The first wavelength division multiplexer wavelength division multiplexes a plurality of series of optical signals output from the second wavelength division multiplexer of the plurality of slave station devices,
The signal allocating unit of each of the plurality of slave station devices includes the digital signal to the electro-optic converter of the slave station device corresponding to the wavelength of the electro-optic converter that is not used in another slave station device. A radio base station characterized in that

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