JP2015156551A - base station system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely transmit/receive in-channel information even when a failure occurs between a center apparatus and remote apparatus of a base station.

SOLUTION: A base station system for transmitting/receiving a baseband signal obtained by performing wavelength multiplexing on optical signals of a plurality of channels includes: a center apparatus; and a remote apparatus. The center apparatus includes: a first optical communication unit for transmitting/receiving a baseband signal to be processed by a radio control unit to/from the remote apparatus by using the optical signals of the plurality of channels; and a first control unit for transmitting a predetermined synchronous signal and control information for controlling a radio unit that are added, for each channel, to the optical signals transmitted by the first optical communication unit, to the remote apparatus. The remote apparatus includes: a second optical communication unit for transmitting/receiving a baseband signal to be transmitted/received by the radio unit to/from the center apparatus by using the optical signals of the plurality of channels; and a second control unit for extracting synchronous signals from the optical signals received from the center apparatus, determining whether or not synchronization of the synchronous signals are established, and selecting control information in a channel whose synchronization is established to control the radio unit.

COPYRIGHT: (C)2015,JPO&INPIT

Description

  The present invention relates to a base station system.

  In recent years, various mobile wireless terminals such as mobile phones and smartphones have been used. Since mobile wireless terminals are connected to outdoor or indoor wireless base stations to perform calls and communications, wireless communication companies are required to install a large number of wireless base stations in various places. Therefore, in order to reduce the installation cost, the radio base station is separated into a radio part (RRH: Remote Radio Header) and a baseband part (BDE: Base station Digital processing Equipment), and the RRH is separated from the BDE. Installation technology is used. For example, when one BED and a plurality of RRHs are connected, the center device on the BDE side converts the baseband signal corresponding to each RRH into an optical signal and multiplexes it, and the RRH side with one optical fiber Send to. Then, the remote device on the RRH side converts baseband signals of a plurality of lines received from the center apparatus into radio signals and transmits them from the RRH antenna corresponding to each line (for example, refer to Non-Patent Documents 1 and 2). . For example, baseband signals corresponding to six sectors are converted into optical signals, multiplexed, and transmitted to the RRH side using a single optical fiber. Thereby, it is not necessary to wire from BDE to RRH for each sector, and the installation cost is reduced. As described above, CPRI (Common Public Radio Interface) is known as an interface standard for connecting BDE and RRH with an optical fiber. Further, in-channel information (for example, a monitoring control signal for monitoring a carrier state or the like) is transmitted and received between the center device and the remote device for connecting the BDE and the RRH.

http://www.nttdocomo.co.jp/binary/pdf/corporate/technology/rd/technical_journal/bn/vol18_1/vol18_1_033jp.pdf, NTT DOCOMO Technical Journal Vol.18 No.1, p.33-37 ( 2010) http://img.jp.fujitsu.com/downloads/jp/jmag/vol62-4/paper07.pdf, FUJITSU.62,4, p. 388-393 (07, 2011)

  On the other hand, an LSI (Large Scale Integration) for CPRI has a function of bundling, for example, three baseband signals and communicating between a center device and a remote device. When transmitting a 6-sector baseband signal to the RRH, the BDE uses two CPRI LSIs to convert the optical signals into two channels having different wavelengths, and uses WDM (Wavelength Division Multiplexing). Multiplex transmission.

  However, a control signal (referred to as in-channel information) for controlling RRH from the center apparatus side is multiplexed and communicated with an optical signal of one channel. For this reason, when a failure occurs in an LSI or a communication path of a channel that transmits / receives in-channel information, it becomes difficult to control RRH of a channel that does not transmit / receive in-channel information. As a result, although the baseband signal of the channel that does not transmit / receive in-channel information is normally transmitted from the BDE to the RRH, it is difficult to transmit / receive in-channel information, so that all RRHs do not operate.

  In this way, when the center device and the remote device are connected in multiple channels, if a failure occurs in the channel that transmits / receives the in-channel information, the communication of the channel that does not transmit / receive the in-channel information is also disconnected. There was a problem.

  An object of the base station system disclosed herein is to provide a technique for reliably transmitting and receiving in-channel information between a center apparatus and a remote apparatus.

  According to one aspect, a base station system includes a center device and a remote device that perform wavelength-division multiplexing of optical signals of a plurality of channels, and a wireless device that is connected to the center device and processes a baseband signal for wireless communication. In a base station system having a control unit and a plurality of radio units that are connected to a remote device and convert a baseband signal processed by the radio control unit into a radio frequency and transmit / receive to / from a radio terminal, Control information for controlling a first optical communication unit that transmits / receives a baseband signal processed by the radio control unit using a plurality of channels of optical signals to / from a remote device, and a predetermined synchronization signal and radio unit And a first control unit that adds to the optical signal transmitted by the first optical communication unit for each channel and transmits the optical signal to the remote device. The remote device uses optical signals of a plurality of channels. A synchronization signal is extracted from an optical signal received from the center device and a second optical communication unit that transmits / receives a baseband signal transmitted / received by the wireless unit to / from the center device, and synchronization of the synchronization signal is established. And a second control unit that controls the radio unit by selecting control information of a channel with which synchronization is established.

  The base station system disclosed herein can reliably transmit and receive in-channel information between the center device and the remote device.

It is a figure which shows an example of a base station system. It is a figure which shows an example of a center apparatus. It is a figure which shows an example of an in-channel information transmission part. It is a figure which shows an example of a transmission frame. It is a figure which shows an example of an optical signal format. It is a figure which shows an example which adds a synchronizing signal. It is a figure which shows an example of a remote device. It is a figure which shows an example of an in-channel information receiving part.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 shows an example of the base station system 100. In FIG. 1, the base station system 100 includes a base station 101 and an extended station 102. The base station 101 and the extended station 102 are connected by a single optical fiber 103. In addition, the base station 101 is connected to the base station control apparatus 105 via the core network 104. The base station control apparatus 105 manages and controls a plurality of base stations 101 including other base stations 101 and manages connections of wireless terminals 106 that communicate with the respective base stations 101. For example, the base station control apparatus 105 controls authentication and accounting of the wireless terminal 106 or switching of the base station 101 accompanying movement of the wireless terminal 106.

  The base station 101 includes a base station digital processing unit (hereinafter referred to as BDE) 201 and a center device 202. Here, the base station 101 performs processing for excluding the wireless portion, and the extended station 102 described later performs processing for the wireless portion.

  The BDE 201 performs baseband processing, monitoring control processing of the base station 101 and the extension station 102, and the like. For example, the BDE 201 modulates data received by the wireless terminal 106 from a server on the Internet via the base station controller 105 into a baseband signal for each line. Alternatively, the BDE 201 transmits data of each line obtained by demodulating the baseband signal received from the wireless terminal 106 to a server on the Internet via the base station control device 105. The base station control device 105 performs connection of the wireless terminal 106 in the communication business, management of the base station 101, and the like, and connection to an external network such as the Internet is performed via a gateway.

  The center device 202 converts a baseband signal of a line inputted / outputted to / from the BDE 201 connected by an interface conforming to the CPRI standard into an optical signal, and transmits / receives it to / from the extension station 102 via the optical fiber 103. . The center device 202 will be described in detail later.

  On the other hand, the extension station 102 includes a remote device 203 and six radio units (RRH) 204a, 204b, 204c, 204d, 204e, and 204f that convert baseband signals for each line into radio frequencies and transmit / receive them. Each of the radio units 204a, 204b, 204c, 204d, 204e, and 204f has one antenna 205a, 205b, 205c, 205d, 205e, and 205f, and transmits and receives radio waves converted to radio frequencies. Here, when referring to a specific wireless unit among the plurality of wireless units 204a, 204b, 204c, 204d, 204e, and 204f, an alphabet is added to the code, and the notation is expressed as, for example, the wireless unit 204a. Further, when the contents common to the plurality of wireless units 204a, 204b, 204c, 204d, 204e, and 204f are described, the alphabet is omitted and the wireless unit 204 is described. Also, the antenna 205 is described in the same manner as the wireless unit 204.

  The base station system 100 according to the present embodiment shown in FIG. 1 radiates radio waves from the antennas 205 of the six RRHs 204 and uses it as, for example, a six-sector antenna, but the number may not be six. Then, the base station system 100 according to this embodiment provides two channels by bundling three lines of baseband signals of six lines corresponding to the six RRHs 204, and performs communication between the center apparatus 202 and the remote apparatus 203. To do. For this reason, the baseband signal of each channel is converted into an optical signal having a different wavelength, and is communicated through one optical fiber 103 by WDM.

  The remote device 203 converts a baseband signal of each line inputted / outputted to / from the RRH 204 connected by an interface conforming to the CPRI standard into an optical signal, and transmitted / received to / from the center device 202 via the optical fiber 103. To do. The remote device 203 will be described in detail later.

  The RRH 204 converts a baseband signal input from the BDE 201 via the center device 202 and the remote device 203 into a predetermined radio frequency and radiates it from the antenna 205 to the radio terminal 106. Alternatively, the RRH 204 receives the radio wave radiated from the wireless terminal 106 by the antenna 205, converts it into a baseband signal, and outputs it to the BDE 201 via the remote device 203 and the center device 202.

  As described above, in the base station system 100 according to the present embodiment, the base station 101 that processes the baseband signal and the extension station 102 that processes the radio signal are installed apart from each other, and the optical fiber 103 is connected by the CPRI standard interface. Connected with.

  FIG. 2 shows an example of the center device 202. In FIG. 2, the center apparatus 202 includes electrical / optical (E / O) converters 301 a, 301 b, 301 c, which convert baseband signals of six lines input / output from / to the BDE 201 into optical signals. 301d, 301e, and 301f. Furthermore, the center apparatus 202 includes a 10GMUX / DEMUX 302a, a 10GMUX / DEMUX 302b, a MUX / DEMUX 303, a control unit 304, and an in-channel information transmission unit 305. Here, 10G represents a communication speed of 10 Gbps, MUX represents MMultipleXer, and DEMUX represents DEMMultipleXer.

  Here, the E / O conversion units 301a, 301b, 301c, 301d, 301e, and 301f are described with alphabets in the same manner as the RRH 204 and the antenna 205. Similarly, 10GMUX / DEMUX302a and 10GMUX / DEMUX302b are described with alphabets.

  In FIG. 2, the center apparatus 202 divides the six lines into two channels of E / O converters 301a, 301b, and 301c and E / O converters 301d, 301e, and 301f and transmits them to the remote apparatus 203. For this purpose, the E / O conversion units 301a, 301b, and 301c are integrated into the 10GMUX / DEMUX 302a, and the E / O conversion units 301d, 301e, and 301f are integrated into the 10GMUX / DEMUX 302b.

  The E / O converter 301 converts the baseband signal of each line input from the BDE 201 into an optical signal. Alternatively, the E / O conversion unit 301 converts an optical signal received from the extended station 102 side into a baseband signal of each line and outputs it to the BDE 201.

  The 10GMUX / DEMUX 302a and the 10GMUX / DEMUX 302b convert the baseband signals of the three lines input from each E / O converter 301 into optical signals having different wavelengths for each bundled channel, and output the optical signals to the MUX / DEMUX 303. Alternatively, the 10GMUX / DEMUX 302a and the 10GMUX / DEMUX 302b convert the optical signals of different wavelengths received from the MUX / DEMUX 303 into the baseband signals of the three lines of the respective channels and output them to the respective E / O conversion units 301. . The 10GMUX / DEMUX 302a and the 10GMUX / DEMUX 302b transmit and receive optical signals having a communication speed of 10 Gbps. Further, the 10GMUX / DEMUX 302a and the 10GMUX / DEMUX 302b add in-channel information and a synchronization signal output from an in-channel information transmission unit 305, which will be described later, to the optical signal of each channel and output to the MUX / DEMUX 303.

  The MUX / DEMUX 303 multiplexes optical signals having different wavelengths output from the 10GMUX / DEMUX 302a and the 10GMUX / DEMUX 302b and outputs the multiplexed optical signals to the optical fiber 103. Alternatively, the MUX / DEMUX 303 separates the optical signal input from the optical fiber 103 for each wavelength and outputs it to the 10GMUX / DEMUX 302a and the 10GMUX / DEMUX 302b.

  The control unit 304 controls the operation of the entire center device 202. In addition, the control unit 304 also controls the remote device 203 and the RRH 204 of the extension station 102 installed at a location separated by the optical fiber 103 according to a command from the BDE 201.

  The in-channel information transmission unit 305 transmits a control signal for the control unit 304 to control the remote device 203 and the RRH 204 of the extension station 102 to the extension station 102 side as in-channel information. The in-channel information is output to both the 10GMUX / DEMUX 302a and the 10GMUX / DEMUX 302b, and transmitted to the extension station 102 side as optical signals having different wavelengths. The in-channel information transmission unit 305 outputs a predetermined synchronization signal to both the 10GMUX / DEMUX 302a and the 10GMUX / DEMUX 302b, and the output synchronization signal is multiplexed with optical signals of different wavelengths and is on the overhanging station 102 side. Sent to.

  As described above, the center apparatus 202 according to the present embodiment converts optical signals having different wavelengths for each channel in which baseband signals of a plurality of lines are bundled, and transmits / receives the signal to / from the remote apparatus 203. Then, the center device 202 adds in-channel information and a synchronization signal to each channel of optical signals having different wavelengths and transmits the added information to the remote device 203 side. As a result, even when a failure occurs in one channel, in-channel information can be transmitted / received through the remaining channels. Therefore, the base station system 100 according to the present embodiment performs communication over a line that transmits / receives through a channel in which no failure has occurred. Can continue. On the other hand, when in-channel information is transmitted / received on one channel, if a failure occurs in the channel transmitting / receiving in-channel information, it becomes difficult for the BDE 201 to control the RRH 204. The base station system 100 according to the present embodiment transmits and receives in-channel information and a synchronization signal through two channels, but may be wavelength division multiplexed through three or more channels. When wavelength division multiplexing is performed using three or more channels, the base station system 100 can achieve redundancy by adding in-channel information and a synchronization signal to each channel, and effects similar to those of the present embodiment can be achieved. can get.

  FIG. 3 shows an example of the in-channel information transmission unit 305. In FIG. 3, the in-channel information transmission unit 305 includes an in-channel information generation unit 351 and a synchronization signal generation unit 352.

  The in-channel information generation unit 351 generates in-channel information for controlling the remote device 203 and the RRH 204 according to a command from the control unit 304. The in-channel information generated by the in-channel information generation unit 351 is output to both the 10GMUX / DEMUX 302a and the 10GMUX / DEMUX 302b.

  The synchronization signal generation unit 352 generates a predetermined synchronization signal according to a command from the control unit 304. Then, the synchronization signal generated by the synchronization signal generation unit 352 is output to both the 10GMUX / DEMUX 302a and the 10GMUX / DEMUX 302b.

  In this way, the in-channel information transmission unit 305 generates in-channel information and a synchronization signal, adds the in-channel information and the synchronization signal to the optical signals of channels having different wavelengths, and transmits them to the extension station 102 side.

  FIG. 4 shows an example of a transmission frame. 4A illustrates an example of a transmission frame on the 10GMUX / DEMUX 302a side illustrated in FIG. 2, and FIG. 4B illustrates an example of a transmission frame on the 10GMUX / DEMUX 302b side illustrated in FIG. In the example of FIG. 4A, the 10GMUX / DEMUX 302a includes a baseband signal 501 of the line (1), a baseband signal 502 of the line (2), and a baseband signal 503 of the line (3). A signal is transmitted to the remote device 203. Further, the 10GMUX / DEMUX 302a transmits the in-channel information 504 and the synchronization signal 505 to the remote device 203 as overhead (OH). On the other hand, in the example of FIG. 4B, the 10GMUX / DEMUX 302b has three lines: a baseband signal 506 of the line (4), a baseband signal 507 of the line (5), and a baseband signal 508 of the line (6). A baseband signal is transmitted to the remote device 203. Further, the 10GMUX / DEMUX 302b transmits the same in-channel information 504 and the synchronization signal 505 as in FIG. 4A to the remote device 203 as overhead (OH).

  Thus, the same in-channel information 504 and the synchronization signal 505 are transmitted by WDM as optical signals of different wavelengths from both the 10GMUX / DEMUX 302a and the 10GMUX / DEMUX 302b to the remote device 203. For example, the 10GMUX / DEMUX 302a converts to an optical signal with a wavelength λ1, and the 10GMUX / DEMUX 302b converts to an optical signal with a wavelength λ2. The optical signals having the wavelengths λ1 and λ2 are multiplexed by the MUX / DEMUX 303 and output to the optical fiber 103.

  FIG. 5 shows an example of the format of an optical signal. In the format shown in FIG. 5A, ten time slots from TS (Time Slot) 1 to TS10 are used as units (blocks), and TS1 to TS10 are repeated. 4 is converted into an optical signal, stored in each time slot of FIG. 5A, and transmitted.

  Here, the base station system 100 according to the present embodiment periodically transmits a synchronization signal in a predetermined time slot. The format shown in FIG. 5B shows an example in which a synchronization signal is stored in TS3. Here, the synchronization signal may be a signal in which a specific pattern is continuous. For example, an optical signal such as “101010...” Is turned on (corresponding to “1”) and off (corresponding to “0”). Use repeating patterns. Alternatively, a code of a PN sequence (Pseudo random Noise sequences) may be used as the synchronization signal. The in-channel information may be transmitted in the same time slot as the synchronization signal, or may be transmitted in another time slot together with the baseband signal.

  FIG. 6 shows an example of adding a synchronization signal. In FIG. 6, B1, B2, and B3 indicate blocks of time slots from TS1 to TS10 described in FIG. For example, the block B1 has 10 time slots from TS1 to TS10, and the synchronization signal S1 is added to the position of TS3. Similarly, the block B2 and the block B3 have 10 time slots from TS1 to TS10, and synchronization signals S2 and S3 are added to the position of TS3. Here, the determination of whether synchronization of the synchronization signal is established may be performed in one block or a plurality of blocks. For example, in the case of FIG. 6, the remote device 203 determines that synchronization is established when the three synchronization signals S1, S2 and S3 of the blocks B1, B2 and B3 are synchronized. Alternatively, the remote device 203 may determine that synchronization is established when the synchronization signal S1 of the block B1 is synchronized.

  As described above, the base station system 100 according to this embodiment stores the synchronization signal in a time slot at a predetermined position and transmits the synchronization signal. The optical signal in the time slot described with reference to FIGS. 5 and 6 is transmitted from both 10GMUX / DEMUX 302a and 10GMUX / DEMUX 302b in FIG. Here, the lines transmitted by 10GMUX / DEMUX 302a are the lines (1), (2) and (3) shown in FIG. 2, and the lines transmitted by 10GMUX / DEMUX 302b are the lines shown in FIG. 4), line (5) and line (6). However, the in-channel information and the synchronization signal transmitted by the 10GMUX / DEMUX 302a are the same as the in-channel information and the synchronization signal transmitted by the 10GMUX / DEMUX 302b.

  FIG. 7 shows an example of the remote device 203. In FIG. 7, the remote device 203 includes a MUX / DEMUX 401, a 10GMUX / DEMUX 402a, and a 10GMUX / DEMUX 402b. Further, the 10GMUX / DEMUX 402a is an optical / electrical (O / O) that converts optical signals of three lines (line (1), line (2), and line (3)) input / output to / from the RRH 204 into baseband signals. E: Optical / Electrical) conversion units 403a, 403b, and 403c. Similarly, the 10GMUX / DEMUX 402b is an O / E conversion unit that converts optical signals of three lines (line (4), line (5), and line (6)) input / output to / from the RRH 204 into baseband signals. 403d, 403e, and 403f. The remote device 203 includes a control unit 404 and an in-channel information receiving unit 405.

  Here, the O / E converters 403 a, 403 b, 403 c, 403 d, 403 e, and 403 f are described with alphabets in the same manner as the RRH 204 and the antenna 205. Similarly, 10 GMUX / DEMUX 402a and 10GMUX / DEMUX 402b are written with alphabets.

  The MUX / DEMUX 401 separates the optical signals of two channels having different wavelengths input from the optical fiber 103 for each wavelength, and outputs them to the 10GMUX / DEMUX 402a and the 10GMUX / DEMUX 402b, respectively. Alternatively, the MUX / DEMUX 401 multiplexes optical signals of two channels having different wavelengths input from the 10GMUX / DEMUX 402a and the 10GMUX / DEMUX 402b and outputs the multiplexed signals to the optical fiber 103.

  The 10GMUX / DEMUX 402a and the 10GMUX / DEMUX 402b output optical signals input from the MUX / DEMUX 401 to the O / E conversion unit 403 for each line.

  For example, in FIG. 7, the 10GMUX / DEMUX 402a transmits the optical signal of the line (1) to the O / E converter 403a, the optical signal of the line (2) to the O / E converter 403b, and the optical signal of the line (3) to the O / E. Each is output to the E conversion unit 403c. Alternatively, the 10GMUX / DEMUX 402a bundles the optical signals of the three lines input from the respective O / E conversion units 403 and outputs the bundled signals to the MUX / DEMUX 401. Similarly, the 10GMUX / DEMUX 402b converts the optical signal on the line (4) into an O / E converter 403d, converts the optical signal on the line (5) into an O / E converter 403e, and converts the optical signal on the line (6) into O / E. Output to the unit 403f. Alternatively, the 10GMUX / DEMUX 402a bundles the optical signals of the three lines input from the respective O / E conversion units 403 and outputs the bundled signals to the MUX / DEMUX 401. Furthermore, 10GMUX / DEMUX 402a and 10GMUX / DEMUX 402b extract the in-channel information and the synchronization signal, respectively, and output them to the in-channel information receiving unit 405 as described with reference to FIGS. Note that the 10GMUX / DEMUX 402a and the 10GMUX / DEMUX 402b transmit and receive optical signals having a communication speed of 10 Gbps, for example.

  The O / E conversion unit 403 converts the optical signal input from the 10GMUX / DEMUX 402a and the 10GMUX / DEMUX 402b into a baseband signal of each line and outputs the converted signal to the RRH 204. Alternatively, the baseband signal of each line input from the RRH 204 is converted into an optical signal.

  The control unit 404 controls the overall operation of the remote device 203. The control unit 404 controls the remote device 203 and the RRH 204 based on the in-channel information received from the BDE 201.

  The in-channel information receiving unit 405 extracts the in-channel information received from the BDE 201 and outputs it to the control unit 404. The in-channel information and the synchronization signal are input from both the 10GMUX / DEMUX 402a and the 10GMUX / DEMUX 402b, and the control unit 404 selects the in-channel information for which the synchronization signal synchronization is established.

  As described above, the remote device 203 in the present embodiment converts the optical signal having a different wavelength for each channel obtained by bundling the baseband signals of a plurality of lines, and transmits / receives the signal to / from the center device 202. Then, the remote device 203 receives the in-channel information and the synchronization signal added for each channel of optical signals having different wavelengths from the center device 202 side. As a result, even when a failure occurs in one channel, in-channel information can be transmitted / received through the remaining channels. Therefore, the base station system 100 according to the present embodiment performs communication over a line that transmits / receives through a channel in which no failure has occurred. Can continue. As described above, the base station system 100 according to the present embodiment transmits and receives in-channel information and a synchronization signal through two channels, but may be wavelength division multiplexed through three or more channels.

  FIG. 8 shows an example of the in-channel information receiving unit 405. In FIG. 8, the in-channel information reception unit 405 includes a synchronization signal detection unit 451 and an in-channel information selection unit 452.

  As described above with reference to FIG. 6, the synchronization signal detection unit 451 detects a synchronization signal periodically received in a predetermined time slot. The synchronization signal detection unit 451 detects a synchronization signal by performing correlation processing on a predetermined pattern code, and determines that synchronization is established, for example, when the correlation value is equal to or greater than a preset threshold value. Here, as described with reference to FIG. 6, the synchronization signal is transmitted in a predetermined time slot of a block to be repeatedly transmitted. The synchronization signal detection unit 451 may determine the establishment of synchronization in one block, or may determine that synchronization is finally established when the establishment of synchronization is detected continuously in a plurality of blocks. Good.

  The in-channel information selection unit 452 selects the in-channel information of the channel for which the synchronization signal detection unit 451 detects the establishment of synchronization of the synchronization signal, and outputs the selected in-channel information to the control unit 404. For example, when detecting establishment of synchronization of the synchronization signal of 10GMUX / DEMUX 402a, the in-channel information selection unit 452 selects in-channel information received by 10GMUX / DEMUX 402a. Conversely, the in-channel information selection unit 452 selects the in-channel information received by the 10GMUX / DEMUX 402b when detecting establishment of synchronization of the synchronization signal of the 10GMUX / DEMUX 402b. If the establishment of synchronization of both synchronization signals is detected, the in-channel information selection unit 452 selects in-channel information of a predetermined default channel. If the establishment of synchronization between both synchronization signals is not detected, the in-channel information selection unit 452 outputs a synchronization error to the control unit 404.

  In this way, the in-channel information receiving unit 405 selects the in-channel information of the channel whose synchronization signal has been established, and outputs the selected in-channel information to the control unit 404. Thereby, the base station system 100 according to the present embodiment can transmit and receive in-channel information on the remaining channels even when a communication failure occurs on one channel. Then, the remote device 203 can operate the RRH 204 of the one-side channel that has received the in-channel information. For example, in the case of FIG. 7, when a failure occurs in the communication of the 10GMUX / DEMUX 402a, the in-channel information receiving unit 405 can receive the in-channel information from the 10GMUX / DEMUX 402b. As a result, the control unit 404 can operate the O / E conversion units 403d, 403e, and 403f to communicate with the wireless terminal 106 using the RRH 204d, the RRH 204e, and the RRH 204f.

  From the above detailed description, features and advantages of the embodiments will become apparent. This is intended to cover the features and advantages of the embodiments described above without departing from the spirit and scope of the claims. Also, any improvement and modification should be readily conceivable by those having ordinary knowledge in the art. Therefore, there is no intention to limit the scope of the inventive embodiments to those described above, and appropriate modifications and equivalents included in the scope disclosed in the embodiments can be used.

DESCRIPTION OF SYMBOLS 100 ... Base station system; 101 ... Base station; 102 ... Overhang station; 103 ... Optical fiber; 104 ... Core network; 105 ... Base station control apparatus; 201; BDE; 202 ... center device; 203 ... remote device; 204, 204a, 204b, 204c, 204d, 204e, 204f ... RRH; 205, 205a, 205b, 205c, 205d, 205e, 205f ... antenna; 301, 301a, 301b, 301c, 301d, 301e, 301f ... E / O conversion unit; 302, 302a, 302b ... 10GMUX / DEMUX; 303 ... MUX / DEMUX; 304: control unit; 305 ... in-channel information transmission unit; 351: in-channel information raw 352... Synchronization signal generator; 401... MUX / DEMUX; 402, 402a, 402b... 10GMUX / DEMUX; 403, 403a, 403b, 403c, 403d, 403e, 403f. Conversion unit; 404 ... control unit; 405 ... in-channel information reception unit; 451 ... synchronization signal detection unit; 452 ... in-channel information selection unit

Claims (4)

A center device and a remote device that perform wavelength-multiplexing of optical signals of a plurality of channels and communicate with each other, a wireless control unit that is connected to the center device and processes a baseband signal for wireless communication, and is connected to the remote device, In a base station system having a plurality of radio units that convert baseband signals processed by the radio control unit into radio frequencies and transmit / receive to / from radio terminals,
The center device is
A first optical communication unit that transmits and receives a baseband signal processed by the wireless control unit using the optical signals of the plurality of channels to and from the remote device;
A first control unit that adds a predetermined synchronization signal and control information for controlling the wireless unit to the optical signal transmitted by the first optical communication unit for each channel and transmits the same to the remote device And
The remote device is
A second optical communication unit that transmits / receives a baseband signal transmitted / received by the wireless unit using the optical signals of the plurality of channels to / from the center device;
Extracting the synchronization signal from the optical signal received from the center device, determining whether synchronization of the synchronization signal is established, selecting the control information of the channel for which synchronization is established, and selecting the radio unit A second control unit that controls the base station system. The base station system according to claim 1,
The base station system, wherein the center device and the remote device are connected to the radio control unit and the radio unit through a CPRI standard interface. In the base station system according to claim 2,
In the case of having a plurality of the wireless units and performing wavelength-division multiplexing of optical signals of two channels between the center device and the remote device to communicate with each other,
The center device divides a plurality of the radio units into two channels, bundles baseband signals for each channel and converts them into optical signals, adds the synchronization signal and the control information for each channel, and adds the remote signal To the device,
The remote device extracts the synchronization signal for each channel from the optical signal of each channel received from the center device, further determines for each channel whether synchronization of the synchronization signal is established, and the synchronization signal A base station system, wherein the control information of a channel for which synchronization is established is selected and the radio unit corresponding to the channel is controlled. In the base station system according to claim 3,
The base station system, wherein the optical signal for each channel has different baseband signals, the same synchronization signal, and the control information.

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