JP6297293B2 - Radio apparatus, radio control apparatus, and communication control method - Google Patents

Description

  The present invention relates to a radio apparatus, radio control apparatus, and communication control method in a next-generation mobile communication system.

  In LTE (Long Term Evolution), a radio control device (for example, BBU: BaseBand Unit) that performs baseband processing and a radio device (for example, RAU: Radio Antenna Unit) that transmits and receives radio signals by an antenna are separated. An installed base station system has been studied (for example, Non-Patent Document 1).

  In this base station system, a radio network controller (BBU) and a radio device (RAU) are connected by an optical transmission line (optical cable). Specifically, a signal from the radio control apparatus (BBU) is optically transmitted to the radio apparatus (RAU) via an interface such as CPRI (Common Public Radio Interface). A radio apparatus (RAU) converts a signal from a radio control apparatus (BBU) into a radio frequency (RF) and transmits it from an antenna. This radio unit (RAU) is also called an optical feeder radio unit.

  Also, in this base station system, a radio control unit (BBU) generates an OFDM (Orthogonal Frequency Division Multiplexing) signal and transmits it to the radio unit (RAU) via an optical transmission line. The radio unit (RAU) transmits the OFDM signal transmitted from the radio control unit (BBU) to the user terminal via the radio link.

3GPP TS 36.300 “Evolved UTRA and Evolved UTRAN Overall description”

  By the way, the load (load) of the user data with respect to the user terminal varies with time. Along with this, the amount of signal input to the radio network controller (BBU) also dynamically changes. However, in the above-described base station system, a fixed amount of OFDM signal is transmitted through the optical transmission path regardless of fluctuations in the signal amount input to the radio network controller (BBU). For this reason, even when the amount of signal input to the radio network controller (BBU) is small, the band used in the optical transmission path cannot be reduced, and the utilization efficiency of the optical transmission path may be reduced.

  The present invention has been made in view of the above points, and in a base station system in which a radio control apparatus and a radio apparatus are connected by an optical transmission path, the radio apparatus and radio control capable of improving the utilization efficiency of the optical transmission path An object is to provide a device and a communication control method.

The communication control method of the present invention is a communication control method in a base station system including a radio apparatus and a radio control apparatus connected to the radio apparatus via an optical transmission line. In the radio control apparatus, the communication control method A step of transmitting to the wireless device a frequency domain signal whose signal amount varies in response, and empty resource information indicating a wireless resource having a predetermined time length and a predetermined bandwidth to which user data is not allocated, and In the radio apparatus, based on the empty resource information, the frequency domain signal is mapped to a frequency resource, at least one of a control signal and a reference signal is mapped to a frequency resource corresponding to the radio resource, and the mapped signal is , the user end and the step, the time-domain signal into a time domain signal signal amount does not vary in response to the input signal amount And a step of transmitting a.

  ADVANTAGE OF THE INVENTION According to this invention, in the base station system with which a radio | wireless control apparatus and a radio | wireless apparatus are connected by an optical transmission line, the utilization efficiency of an optical transmission line can be improved.

It is explanatory drawing of an example of a base station system. It is explanatory drawing of the base station system which concerns on 1st Embodiment. It is explanatory drawing of the empty resource information for every resource block which concerns on 1st Embodiment. It is a detailed explanatory view of a resource block according to the first embodiment. It is explanatory drawing of the empty resource information for every subcarrier which concerns on 1st Embodiment. It is explanatory drawing of the transmission data of the optical transmission line which concerns on 1st Embodiment. It is explanatory drawing of the zone | band used with the optical transmission line which concerns on 1st Embodiment. It is explanatory drawing of the base station system which concerns on 2nd Embodiment. It is explanatory drawing of the wavelength used with the optical transmission line which concerns on 2nd Embodiment.

  FIG. 1 is an explanatory diagram of an example of a base station system. As illustrated in FIG. 1, the base station system includes a BBU 100, an RAU 200, and an optical transmission path (optical cable) 300 that connects the BBU 100 and the RAU 200. In FIG. 1, the BBU 100 and the RAU 200 may have other configurations not shown.

  FIG. 1A shows an example of generating an OFDM signal when the input signal to the BBU 100 for a certain time is full load. As shown in FIG. 1A, when the signal sequence “01011011” is input to the S / P converter 11 within a predetermined time, the S / P converter 11 converts the signal sequence into eight parallel signal sequences. And output to the constellation mapping unit 12. The constellation mapping unit 12 maps the eight parallel signal sequences on the I / Q plane by a predetermined modulation scheme (here, BPSK: Binary Phase Shift Keying), and outputs the result to the subcarrier mapping unit 13.

  The subcarrier mapping unit 13 maps the eight signals on the I / Q plane to the subcarriers, and outputs the eight frequency domain signals to the IFFT unit 14. The IFFT unit 14 converts each of the eight frequency domain signals into time domain signals. The eight parallel time domain signals output from the IFFT unit 14 are converted into serial time domain signals by the P / S conversion unit 15, subjected to electro-optical conversion by the E / O conversion unit 16, and are transmitted to the optical transmission line 300. Is output.

  On the other hand, FIG. 1B shows a case where the input signal to the BBU 100 for a certain time is not full load. As shown in FIG. 1B, when the signal sequence “0101” is input to the S / P converter 11 within a predetermined time, the S / P converter 11 converts the signal sequence into four parallel signal sequences. And output to the constellation mapping unit 12. The constellation mapping unit 12 maps four parallel signal sequences on the I / Q plane by a predetermined modulation scheme (here, BPSK), and outputs the result to the subcarrier mapping unit 13.

  The subcarrier mapping unit 13 maps four signals on the I / Q plane to subcarriers, and outputs four frequency domain signals to the IFFT unit 14. The IFFT unit 14 converts each of the four frequency domain signals into a time domain signal, and generates eight time domain signals. For this reason, even when only four frequency domain signals are input to the IFFT unit 14, as in the case of inputting eight frequency domain signals (FIG. 1A), the IFFT unit 14 A time domain signal is output.

  Thus, the time domain signal output from the IFFT unit 14 is a constant amount regardless of the amount of the frequency domain signal input to the IFFT unit 14. For this reason, even when the amount of signals input to the BBU 100 is small, the band used in the optical transmission line 300 cannot be reduced, and the utilization efficiency of the optical transmission line 300 may be reduced.

  Therefore, in the base station system in which the wireless control device and the wireless device are connected by an optical transmission path, the present inventors have replaced the wireless control device with a time domain signal that is a constant amount regardless of the input signal amount. The present invention has been achieved with the idea of improving the utilization efficiency of an optical transmission line by optically transmitting a frequency domain signal whose signal amount varies in conjunction with the input signal amount to a wireless device.

  Specifically, in the communication control method of the present invention, the radio control device transmits a frequency domain signal whose signal amount varies according to the input signal amount and empty resource information to the radio device. The radio apparatus converts the frequency domain signal into a time domain signal whose signal amount does not vary according to the input signal amount, based on empty resource information indicating radio resources to which user data is not allocated. The wireless device transmits the converted time domain signal to the user terminal.

  Hereinafter, the base station system according to the present embodiment will be described in detail. In the following, a case where the radio control apparatus and radio apparatus included in the base station system according to the present embodiment are BBU and RAU, respectively, will be described, but the present invention is not limited to this. The radio control device may be BDE (Base station Digital processing Equipment), REC (Radio Equipment Control), or the like. The radio apparatus may be RRE (Remote Radio Equipment), RRH (Remote Radio Head), RE (Radio Equipment), or the like.

(First embodiment)
A base station system according to the first embodiment will be described with reference to FIGS. FIG. 2 is an explanatory diagram of the base station system according to the first embodiment. As illustrated in FIG. 2, the base station system according to the first embodiment includes a BBU 10 (radio control device), an RAU 20 (radio device), and an optical transmission line 30 that connects the BBU 10 and the RAU 20. Note that the base station system may include a plurality of BBUs 10 and a plurality of RAUs 20.

  In the base station system according to the first embodiment, the BBU 10 generates a blank resource that generates a frequency domain signal whose signal amount varies according to the input signal amount and a blank resource information indicating a radio resource to which no user data is allocated. Information is transmitted to the RAU 20. The RAU 20 converts the frequency domain signal into a time domain signal whose signal amount does not vary according to the input signal amount, based on the empty resource information. The RAU 20 transmits a time domain signal to the user terminal.

(BBU)
The BBU 10 according to the first embodiment will be described in detail with reference to FIG. As shown in FIG. 2, the BBU 10 includes a constellation mapping unit 101, an empty resource information acquisition unit 102, a multiplexing (MUX) unit 103, and a lightning (E / O) conversion unit 104.

  The constellation mapping unit 101 maps an input signal sequence to an I / Q plane using various modulation methods to generate a frequency domain signal. As a modulation method, for example, BPSK, QPSK (Quadrature Phase Shift Keying), 8PSK (8 Phase Shift Keying), 16QAM (16 Quadrature Amplitude Modulation), 64QAM (64 Quadrature Amplitude Modulation), or the like can be used.

  The empty resource information acquisition unit 102 acquires empty resource information and outputs it to the MUX unit 103. Specifically, the empty resource information acquisition unit 102 may acquire empty resource information generated by a function unit (not shown) (for example, a scheduling unit).

  Here, the empty resource information is information indicating radio resources (for example, resource blocks, subcarriers, etc.) to which user data is not allocated. The empty resource information may be generated for each resource block, or may be generated for each subcarrier. Hereinafter, the empty resource information will be described in detail with reference to FIGS.

  FIG. 3 is an explanatory diagram of empty resource information for each resource block. As shown in FIG. 3, the empty resource information may be bit information indicating whether or not user data is allocated for each resource block. In FIG. 3, a resource block to which user data is allocated is indicated by “1”, and a resource block to which user data is not allocated (hereinafter referred to as an empty resource block) is indicated by “0”.

  FIG. 4 is a detailed explanatory diagram of the resource block. As shown in FIG. 4, the system band allocated to a user terminal (UE: User Equipment) is composed of a plurality of resource blocks. Each resource block is configured with 180 kHz (12 subcarriers) in the frequency direction and 1 ms (14 OFDM symbols) in the time direction. A radio resource region composed of one subcarrier and one OFDM symbol is called a resource element (RE).

  The resource block may be called a physical resource block (PRB), a PRB pair, or the like. Further, the length in the time direction (1 ms) of each resource block may be referred to as a subframe (SF). Also, subframes # 0 to # 9 (10 ms) in FIG. 4 may be referred to as radio frames.

  As shown in FIG. 4, the maximum 3 OFDM symbols at the beginning of each subframe include downlink control channels (PDCCH: Physical Downlink Control Channel, PHICH: Physical Hybrid-ARQ Indicator Channel, PCFICH: Physical Control Format) over the entire system band. Indicator Channel) is arranged. In addition, in a subframe having a predetermined cycle, a synchronization signal (SS) and a broadcast channel (PBCH: Physical Broadcast Channel) are arranged in a part of the system band.

  Also, reference signals (for example, CRS: Cell-Specific Reference Signal, CSI-RS: Channel State Information Reference Signal, etc.) are arranged in predetermined resource elements of each resource block. A downlink shared channel (PDSCH: Physical Downlink Shared Channel) for transmitting user data is mapped to resource elements in which the above downlink control channel, synchronization signal, broadcast channel, reference signal, and the like are not arranged.

  Therefore, control signals such as a downlink control channel, a control signal, a synchronization signal, and a broadcast channel are also arranged in an empty resource block to which user data (PDSCH) of FIG. 3 is not allocated, as shown in FIG. These control signals are mapped to the I / Q plane in the constellation mapping unit 101 and output as frequency domain signals.

  FIG. 5 is an explanatory diagram of empty resource information for each subcarrier. As shown in FIG. 5, the empty resource information may be generated for each subcarrier instead of for each resource block (FIG. 3). Specifically, as shown in FIG. 5, when the system bandwidth of the user terminal is composed of 25 resource blocks, 300 (= 25 × 12) subcarriers and 32 (= 16 × 2) sides And a lobe.

  In the case shown in FIG. 5, the empty resource information may be bit information indicating whether or not user data is allocated for each resource block in the frequency direction in subcarrier units and in the time direction in subframe units. That is, the empty resource information in FIG. 5 is different from the empty resource information in FIG. 3 in which the frequency direction is in units of resource blocks including 12 subcarriers in that the frequency direction is in subcarrier units.

  Also, as described in FIG. 4, control signals such as a downlink control channel, a control signal, a synchronization signal, and a broadcast channel are assigned to predetermined resource elements even in empty subcarriers to which user data (PDSCH) is not assigned in FIG. Is placed. These control signals are mapped to the I / Q plane in the constellation mapping unit 101 and output as frequency domain signals.

  The MUX unit 103 in FIG. 2 multiplexes the frequency domain signal input from the constellation mapping unit 101 and the empty resource information input from the empty resource information acquisition unit 102, and outputs the multiplexed signal to the E / O conversion unit 104. .

  With reference to FIG. 6, the empty resource information and frequency domain signal multiplexed by the MUX unit 103 will be described. In addition, although FIG. 6A demonstrates the case where the system band (refer FIG. 4) of a user terminal is comprised by 25 resource blocks (RB), it is not restricted to this. Moreover, although FIG. 6A demonstrates the case where empty resource information is for each resource block, it may be for each subcarrier.

  In the empty resource information of FIG. 6A, bits are allocated to each of resource blocks # 1 to # 25 in a specific subframe. Whether the bit is “1” or “0” indicates whether user data is allocated to the resource block corresponding to the bit. For example, in FIG. 6A, the bit of resource block # 1 is “0” indicating an empty resource block, and the bit of resource block # 2 is “1” indicating that user data is allocated.

  Further, the frequency domain signal of FIG. 6A includes information mapped to each resource element of resource blocks # 1 to # 25. For example, in the empty resource block # 1, when the downlink control channel (PDCCH / PCFICH / PHICH) and the reference signal are arranged as shown in FIG. 6B, the frequency domain signal of the resource block # 1 is 36 RE (= maximum) 3 OFDM symbols × 12 subcarriers).

  Since the configuration of the reference signal (particularly CRS) is constant, once the configuration information of the reference signal is transmitted to the RAU 20, the frequency domain signal of the empty resource block # 1 does not include the reference signal bit. Good. Here, the reference signal configuration information may be a signal sequence of a reference signal (for example, CRS) corresponding to a cell ID (PCI: Physical Cell Identifier), CSI-RS configuration information, or the like.

  On the other hand, user data (PDSCH) is allocated in resource block # 2. Therefore, 168RE (= 14 OFDM symbols × 12 subcarriers) is included in the frequency domain signal of resource block # 2. Thus, when transmitting a frequency domain signal, the transmission amount can be reduced according to whether user data is allocated or not.

  The E / O conversion unit 104 converts the multiplexed signal input from the MUX unit 103 from an electric signal to an optical signal. The E / O conversion unit 104 transmits the converted optical signal to the RAU 20 via the optical transmission line 30. The multiplexed signal may be transmitted using a wavelength channel that is dynamically assigned.

  Note that the empty resource information from the empty resource information acquisition unit 102 and the frequency domain signal input from the constellation mapping unit 101 may be transmitted without being multiplexed. For example, the empty resource information may be transmitted using a dedicated wavelength channel, and the frequency domain signal may be transmitted using a dynamically assigned wavelength channel.

  Further, in the optical transmission line 30, the configuration information of the reference signal, the system band information indicating the system band of the user terminal, the transmission period of the synchronization signal and the broadcast channel, and the like may be transmitted to the RAU 20. Such information, once transmitted to the RAU 20, may not be transmitted every time a frequency domain signal is transmitted.

(RAU)
Next, the RAU 20 according to the first embodiment will be described in detail with reference to FIG. As shown in FIG. 2, the RAU 20 includes an O / E conversion unit 201, a demultiplexing (DEMUX) unit 202, a serial / parallel (S / P) conversion unit 203, an empty resource information decoding unit 204, and a null bit adjustment unit. 205 (detection unit), subcarrier mapping unit 206, IFFT unit 207, parallel / serial (P / S) conversion unit 208, CP addition unit 209, D / A conversion unit 210, and RF function unit 211 And an antenna element 212.

  The O / E conversion unit 201 converts an optical signal transmitted from the BBU 10 via the optical transmission path 30 into an electrical signal. The DEMUX unit 202 separates the input signal from the O / E conversion unit 201 into a frequency domain signal and empty resource information. The DEMUX unit 202 outputs the frequency domain signal to the S / P conversion unit 203 and outputs the empty resource information to the empty resource information decoding unit 204.

  The S / P conversion unit 203 converts the serial frequency domain signal into a predetermined number (for example, 4 in FIG. 2) of parallel frequency domain signals, and outputs the parallel frequency domain signal to the null bit adjustment unit 205.

  The empty resource information decoding unit 204 decodes the empty resource information input from the DEMUX unit 202 and outputs it to the null bit adjustment unit 205.

  Based on the empty resource information input from the empty resource information decoding unit 204, the null bit adjustment unit 205 detects the position of an empty resource block (or an empty subcarrier) in the system band for each subframe period, and outputs a detection result. Based on this, a frequency domain signal is output to subcarrier mapping section 206 for each OFDM symbol.

  For example, in FIG. 6A, the null bit adjustment unit 205 detects that resource blocks # 1 and # 25 are empty resource blocks based on the empty resource information. 6A is configured as shown in FIG. 6B, the subcarrier mapping unit 206 determines the position of the null bit (PDSCH is not allocated based on the configuration information of the reference signal). Subcarrier) is detected for each OFDM symbol, and the frequency domain signal (reference signal and downlink control channel in FIG. 6B) input for each OFDM symbol is adjusted to an appropriate position and output to subcarrier mapping section 206. . The null bit may be detected based on a synchronization signal, a broadcast channel transmission period, or the like.

  Subcarrier mapping section 206 maps the frequency domain signals input from null bit adjustment section 205 to subcarriers, and outputs them to IFFT section 207. Note that the position of the null bit in the empty resource block may be detected by the subcarrier mapping unit 206 instead of the null bit adjustment unit 205. In this case, the subcarrier mapping unit 206 maps the frequency domain signal to an appropriate subcarrier based on the null bit position.

  IFFT section 207 performs inverse fast Fourier transform on the frequency domain signal input from subcarrier mapping section 206 to generate n (n = 8 in FIG. 2) time domain signals. The IFFT unit 207 outputs the generated n time domain signals to the P / S conversion unit 208.

  The P / S conversion unit 208 converts the parallel time domain signal input from the IFFT unit 207 into a serial time domain signal and outputs the serial time domain signal to the CP adding unit 209. CP adding section 209 adds a cyclic prefix (guard interval) to the time domain signal input from P / S conversion section 208 and outputs the result to D / A conversion section 210.

  The D / A conversion unit 210 converts the time domain signal input from the CP addition unit 209 from a digital signal to an analog signal and outputs the analog signal to the RF function unit 211. The RF function unit 211 converts the input signal from the D / A conversion unit 210 into a radio frequency (RF) band, and transmits it from the antenna element 212.

  According to the base station system according to the first embodiment, the amount is linked to the presence / absence of user data instead of the time domain signal which is a constant amount regardless of the presence / absence of user data (the amount of input signal to the BBU 10). A fluctuating frequency domain signal is transmitted from the BBU 10 to the RAU 20. As a result, the bandwidth required for the optical transmission line 30 varies according to the amount of input signal to the BBU 10, as shown in FIG. Therefore, the utilization efficiency of the optical transmission line 30 can be improved.

(Second Embodiment)
Next, a base station system according to the second embodiment will be described with reference to FIGS. In the second embodiment, a case will be described in which a plurality of BBUs 10 and a plurality of RAUs 20 are provided in the base station system according to the first embodiment.

  For example, in the base station system according to the first embodiment, when a plurality of BBUs 10 and a plurality of RAUs 20 are connected by an optical transmission line 30, a wavelength channel λ is fixedly assigned to the pair of BBUs 10 and the RAUs 20, It is assumed that wavelength division multiplexing is performed.

  However, when the wavelength channel λ is fixedly assigned to the pair of BBU 10 and RAU 20, the amount of user data transmitted between the specific BBU 10 and RAU 20 is small, and there is room in the wavelength channel (wavelength resource). Even so, user data cannot be transmitted between the other BBU 10 and the RAU 20 using the wavelength resource. For this reason, there is a possibility that the effect of improving the utilization efficiency of the optical transmission line 30 by the transmission of the frequency domain signal cannot be sufficiently obtained.

  Therefore, in the base station system according to the second embodiment, the wavelength channel λ is dynamically allocated between the plurality of BBUs 10 and the plurality of RAUs 20 to improve the wavelength utilization efficiency. Thereby, it is possible to further enhance the effect of improving the utilization efficiency of the optical transmission line 30 by transmitting the frequency domain signal instead of the time domain signal.

  FIG. 8 is an explanatory diagram of the base station system according to the second embodiment. As shown in FIG. 2, the base station system according to the second embodiment includes a plurality of BBUs 10 (wireless control devices), a plurality of RAUs 20 (wireless devices), an optical transmission line 30, and light from the plurality of BBUs 10. A multiplexing (MUX) unit 40 that multiplexes signals and a demultiplexing (DEMUX) unit 50 that classifies multiplexed signals from the optical transmission line 30 are provided.

Although not shown in FIG. 8, the BBUs 10 may be connected to each other. In FIG. 8, three BBUs 10 ₁ -10 ₃ and three RAUs 20 ₁ -20 ₃ are shown, but the number of BBUs 10 and RAUs 20 is not limited to this. Below, it demonstrates centering around difference with the base station system which concerns on 1st Embodiment.

(BBU)
The BBU 10 according to the second embodiment will be described in detail with reference to FIG. As shown in FIG. 8, each BBU 10 is different from the BBU 10 of FIG. 2 in that each BBU 10 further includes a wavelength / time scheduling control unit 105, a wavelength / time scheduling unit 106, and a wavelength division multiplexing (WDM filter) unit 107. Each BBU 10 also differs from the BBU 10 in FIG. 2 in that each BBU 10 includes an E / O converter 104 for each wavelength channel λ.

  The wavelength / time scheduling control unit 105 exchanges wavelength / time scheduling results with other BBUs 10. The wavelength / time scheduling control unit 105 controls the wavelength / time scheduling unit 106 based on the wavelength / time scheduling result in the other BBU 10.

  In accordance with an instruction from the wavelength / time scheduling control unit 105, the wavelength / time scheduling unit 106 sets at least one of wavelength and time for the multiplexed signal of the frequency domain signal and the empty resource information input from the MUX unit 103. assign. More specifically, the wavelength / time scheduling unit 106 determines which wavelength is used and which information is transmitted for each scheduling period. The wavelength / time scheduling unit 106 outputs the multiplexed signal to the E / O conversion unit 104 corresponding to the allocated wavelength.

FIG. 9 is an explanatory diagram of wavelength / time scheduling. In FIG. 9, the four wavelength channels λ ₁ -λ ₄ are wavelength division multiplexed, but the number of wavelengths is not limited to this. Note that time allocation is performed, for example, in units of subframes, but is not limited thereto.

As shown in FIG. 9A, the wavelength / time scheduling unit 106 assigns the wavelength channel λ so that the total bandwidth in the optical transmission line 30 is minimized. For example, the wavelength / time scheduling unit 106 of the BBU 10 ₃ can use the two-wavelength channels λ ₃ and λ ₄ at the times t 1 and t 2, but assigns a transmission signal for the RAU 20 ₃ only to the wavelength channel λ ₃ . For this reason, it is possible to improve the wavelength utilization efficiency and to save power by sleeping the transmitter of the wavelength channel λ ₄ .

Further, as shown in FIG. 9B, the wavelength-time scheduling unit 106, aggregates the transmission signal to a plurality of RAU20 ₁ -20 ₃ to the specific wavelength, time division multiplexed transmission signal to the plurality of RAU20 ₁ -20 ₃ May be. For example, in FIG. 9B, at time t2 and t5, transmission signals for a plurality of RAUs 20 _{1 to} 20 ₃ are time-division multiplexed on the wavelength channel λ ₁ . Thereby, the wavelength utilization efficiency can be further improved, and further power saving can be achieved by the sleep of the transmitter of the wavelength channel λ _2-4 .

  Each E / O conversion unit 104 in FIG. 8 converts the electrical signal input from the wavelength / time scheduling unit 106 as described above into an optical signal and outputs the optical signal to the WDM filter unit 107. The WDM filter unit 107 wavelength-division-multiplexes the optical signal input from each E / O conversion unit 104 and outputs it to the MUX unit 40.

  The MUX unit 40 multiplexes the wavelength division multiplexed signals from the respective BBUs 10 and outputs the multiplexed signals to the optical transmission line 30. The DEMUX unit 50 separates the multiplexed signal from the optical transmission line 30 into wavelength division multiplexed signals to each RAU 20 and inputs the separated signals to each RAU 20.

(RAU)
With reference to FIG. 8, the RAU 20 according to the second embodiment will be described in detail. As shown in FIG. 8, each RAU 20 includes a wavelength separation (WDM filter) unit 213, a wavelength tunable filter (Tunable Filter) 214 for each wavelength channel λ, a wavelength / time scheduling control unit 215, and a wavelength / time scheduling unit. 2 further differs from the RAU 20 of FIG. Further, each RAU 20 is different from the RAU 20 of FIG. 2 in that an O / E conversion unit 201 is provided for each wavelength channel λ.

The WDM filter 213 separates the wavelength division multiplexed signal input from the DEMUX unit 50 for each wavelength channel λ. Although FIG. 8 shows the case where the wavelength division multiplexed signal is separated into four wavelength channels λ ₁ -λ ₄ , the number of wavelengths is not limited to this. The WDM filter 213 outputs the separated optical signal of each wavelength channel λ to the corresponding wavelength variable filter 214.

  Each tunable filter 214 transmits only the optical signal of a specific wavelength channel λ and outputs it to the corresponding O / E converter 201. Each O / E converter 201 converts the optical signal input from the wavelength tunable filter 214 into an electrical signal, and outputs the electrical signal to the wavelength / time scheduling unit 216.

  The wavelength / time scheduling control unit 215 controls the wavelength variable filter 214 and the wavelength / time scheduling unit 216.

  The wavelength / time scheduling unit 216 schedules the electrical signal output from each O / E conversion unit 201 for each wavelength / time, restores the output signal from the MUX unit 103 in the BBU 10, and outputs the output signal to the DEMUX unit 202. .

  Note that the DEMUX unit 202, S / P conversion unit 203, empty resource information decoding unit 204, null bit adjustment unit 205, subcarrier mapping unit 206, IFFT unit 207, and P / S conversion unit 208 in FIG. The CP adding unit 209, the D / A conversion unit 210, the RF function unit 211, and the antenna element 212 are the same as those in FIG.

  According to the base station system according to the second embodiment, frequency domain signals from a plurality of BBUs 10 are transmitted to a plurality of RAUs 20 using wavelength channels to which dynamic allocation is performed. For this reason, it is possible to further enhance the effect of improving the utilization efficiency of the optical transmission line 30 by optically transmitting a frequency domain signal whose signal amount varies in conjunction with the presence or absence of user data.

  In addition, according to the base station system of the second embodiment, it is possible to sleep the wavelength channel transmission function that has become unused as a result of dynamic wavelength channel assignment. For this reason, power saving of the BBU 10 can be achieved.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

10, 100 ... BBU
20, 200 ... RAU
30, 300 ... Optical transmission line 40 ... MUX unit 50 ... DEMUX unit 11 ... S / P conversion unit 12 ... Constellation mapping unit 13 ... Subcarrier mapping unit 14 ... IFFT unit 15 ... P / S conversion unit 16 ... E / O Conversion unit 101 ... Constellation mapping unit 102 ... Empty resource information acquisition unit 103 ... MUX unit 104 ... E / O conversion unit 105 ... Wavelength / time scheduling control unit 106 ... Wavelength / time scheduling unit 107 ... WDM filter units 201, 21 ... O / E conversion unit 202 ... DEMUX unit 203 ... S / P conversion unit 204 ... empty resource information decoding unit 205 ... null bit adjustment unit 206 ... subcarrier mapping unit 207 ... IFFT unit 208 ... P / S conversion unit 209 ... CP addition unit 210, 22 ... D / A converter 211, 23 ... RF function unit 212 ... antenna element 213 ... WDM filter 214 ... tunable filter 215 ... wavelength-time scheduling control unit 216 ... wavelength-time scheduling unit

Claims (9)

A wireless device connected to the wireless control device via an optical transmission line,
A frequency domain signal whose signal amount varies according to an input signal amount to the radio control device, and empty resource information indicating a radio resource having a predetermined time length and a predetermined bandwidth to which no user data is allocated. A receiving unit for receiving from the radio network controller;
Based on the empty resource information, the frequency domain signal is mapped to a frequency resource, at least one of a control signal and a reference signal is mapped to a frequency resource corresponding to the radio resource, and the mapped signal is converted to the input signal. A radio apparatus comprising: a conversion unit that converts a signal amount into a time domain signal that does not vary according to the amount; and a transmission unit that transmits the time domain signal to a user terminal.   The conversion unit includes a detection unit that detects the radio resource based on the empty resource information, a subcarrier mapping unit that maps the frequency domain signal to a subcarrier based on a detection result by the detection unit, and the subcarrier The radio apparatus according to claim 1, further comprising: an inverse Fourier transform unit that transforms a frequency domain signal mapped to the time domain signal into the time domain signal.   The radio apparatus according to claim 1 or 2, wherein the empty resource information indicates a radio resource to which the user data is not allocated in a resource block unit or a subcarrier unit.   4. The radio apparatus according to claim 1, wherein the reception unit receives the frequency domain signal and the empty resource information using a wavelength channel that is dynamically assigned. 5.   4. The receiver according to claim 1, wherein the receiving unit receives the frequency domain signal and the free resource information that are time-division multiplexed with other wireless devices in a single wavelength channel. A wireless device according to 1.   The reception unit receives the frequency domain signal using a dynamically assigned wavelength channel and receives the empty resource information using a dedicated wavelength channel. A wireless device according to any one of the above.   The said receiving part receives the system bandwidth information which shows the changed system bandwidth from the said radio | wireless control apparatus, when the system bandwidth for the said user terminals is changed, The said control part is characterized by the above-mentioned. The wireless device according to any one of the above. A wireless control device connected to the wireless device via an optical transmission line,
A frequency domain signal generation unit that generates a frequency domain signal in which the signal amount varies according to the input signal amount;
And generate unit that generates an empty resource information indicating a radio resource having a predetermined time length and a predetermined bandwidth which the user data is not assigned,
A transmitter that transmits the frequency domain signal and the empty resource information to the wireless device ;
In the radio apparatus, the frequency domain signal is mapped to a frequency resource based on the empty resource information, and at least one of a control signal and a reference signal is mapped to a frequency resource corresponding to the radio resource, and the mapped signal is The radio control device is characterized in that it is converted into a time domain signal in which the signal amount does not vary according to the input signal amount . A communication control method in a base station system including a wireless device and a wireless control device connected to the wireless device via an optical transmission path,
In the radio control apparatus, a frequency domain signal whose signal amount varies according to an input signal amount, and empty resource information indicating a radio resource having a predetermined time length and a predetermined bandwidth to which no user data is allocated. Transmitting to the wireless device;
In the radio apparatus, the frequency domain signal is mapped to a frequency resource based on the empty resource information, and at least one of a control signal and a reference signal is mapped to a frequency resource corresponding to the radio resource, and the mapped signal and a step of converting the time domain signal signal amount does not vary in response to the input signal amount, a communication control method characterized by having the steps of transmitting the time domain signal to the user terminal.

Images