JP2014123844A - Lower-level device, communication system and communication control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve system redundancy with a simple structure.SOLUTION: A lower-level device 101 for communicating with an upper-level device includes: a port switchover control unit 32 capable of setting one of a first port and a second port, which inputs and outputs communication signals between with another device, to be a master port, and setting another port to be a slave port; and a communication control unit 31 for performing processing to establish a communication connection with the other device through the first and second ports. When the communication connection with the upper-level device or another lower-level device 101 cannot be established through the slave port, the port switchover control unit 32 performs switchover processing between the master port and the slave port. On completion of the switchover processing by the port switchover control unit 32, the communication control unit 31 performs processing to establish a communication connection with the upper-level device or the other lower-level device 101 through the slave port after the switchover.

Description

  The present invention relates to a lower level apparatus, a communication system, and a communication control method, and more particularly, to a lower level apparatus, a communication system, and a communication control method for realizing system redundancy.

  In order to keep the radio communication service with high quality, the arrangement of the radio base station apparatus is an important factor. In recent years, a remote radio head (RRH), which is a small outdoor type radio unit in which a radio signal transmission / reception part is independent from the radio base station apparatus, has been developed so that the radio base station apparatus can be flexibly arranged. Yes.

  In such a radio base station apparatus divided by a remote radio head, the base station body and the remote radio head are connected by an optical fiber cable, and the remote radio head is within a range of several tens of kilometers from the vicinity of the base station body. It can be installed in a place.

  Also, CPRI (Common Public Radio Interface) has been standardized as a communication interface between the base station main body and the remote radio head (for example, Non-Patent Document 1 ("CPRI Specification V4.2", [online], 2010). September 29, see <http://www.cpri.info/downloads/CPRI_v_4_2_2010-09-29.pdf>)).

  By the way, in a network service such as a cellular phone network, in order to provide a highly reliable system, it is essential to make the system redundant, that is, redundant. In the redundant system, a redundant configuration is adopted in which each of the devices, components, and network has an active system and a standby system as required. When a failure occurs in a part of the operating system, it is possible to make the system stop time due to the failure as short as possible by performing redundant switching from the active system to the standby system.

  Even if a failure has not become apparent, there is a case where the device or the like is replaced proactively in consideration of the deterioration tendency of characteristics and the life of parts. If the system has a redundant configuration, the system stop time due to such maintenance work can be shortened as much as possible.

"CPRI Specification V4.2", [online], September 29, 2010, <http://www.cpri.info/downloads/CPRI_v_4_2_2010-09-29.pdf>

  For example, when a plurality of remote radio heads, which are lower devices, are provided for one base station main body, which is a host device, each remote radio head is cascaded to reduce the number of input / output ports in the base station body. A method of connecting is conceivable. In this case, the base station body may be provided with one input / output port, and the remote radio head is provided with two input / output ports.

  In order to realize redundancy in such a system, at least two input / output ports of the base station main body are required for the active system and the standby system, and at least two input / output ports of the remote radio head are required. And at least two optical fibers are required between the devices. In a system that realizes such redundancy, when one remote radio head is provided for one base station body and both devices are connected one-to-one, each input / output in the remote radio head is performed. Half of the ports are unused.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a low-level device, a communication system, and a communication control method capable of realizing system redundancy with a simple configuration. is there.

  (1) A subordinate apparatus according to an aspect of the present invention is a subordinate apparatus for communicating with a host apparatus, and a first port and a second port through which a communication signal is input / output with another apparatus A port switching control unit capable of setting one of the first port and the second port as a master port and the other as a slave port, via the first port and via the second port A communication control unit for performing processing for establishing a communication connection with another device, and the port switching control unit is configured to communicate with the upper device or the other lower device via the slave port. When the establishment cannot be established, the master port and the slave port are switched, and the communication control unit performs the switching process by the port switching control unit. Via the slave port after switching performs processing of establishing a communication connection between the host device or the other lower-level device.

  With this configuration, in order to realize system redundancy, for example, when providing one standby system, it is only necessary to provide two ports in the lower-level device, and a communication path between the devices is also provided for one system. It will be better. Further, since a pair of slave ports and a master port need only be provided in the lower level device, for example, a pair of slave port circuits and a master port circuit may be provided by using a switch circuit or the like. When one lower apparatus is provided for one upper apparatus and both apparatuses are connected in a one-to-one relationship, unused ports are eliminated and the use efficiency of apparatus resources can be improved. Accordingly, system redundancy can be realized with a simple configuration. Furthermore, the lower-level device can autonomously perform the redundancy switching process without the higher-level device controlling the lower-level device. In addition, with the configuration in which whether or not a communication connection with a higher-level device or another lower-level device can be established is used as a determination criterion for redundant switching execution, existing processing is diverted without newly setting a determination criterion for redundant switching execution. Thus, it is possible to determine whether to perform redundancy switching.

  (2) Preferably, the lower device further includes a PLD (Programmable Logic Device), and the port switching control unit changes the circuit configuration of the PLD and transmits / receives a communication signal via the slave port. The master port and the slave port are switched by switching the port associated with the slave circuit used for the switching between the first port and the second port.

  With such a configuration, the master port and slave port switching process can be performed only by changing the circuit configuration in the PLD without separately providing a circuit such as a switch for switching the master port and the slave port.

  (3) Preferably, the port switching control unit cannot establish the communication connection with another device via one of the first port and the second port set as a slave port. In this case, the one port is set as a master port, and the communication control unit performs processing for establishing a communication connection with the other device via the one port set as the master port.

  With such a configuration, it is possible to establish communication connection with another device on the slave port side after switching, and establish communication connection with another device on the master port side after switching.

  (4) More preferably, the slave circuit is a circuit for generating a reference timing signal based on data received from a master port of the higher order device or a master port of another lower order device.

  With such a configuration, it is possible to prevent unnecessary provision of a clock recovery circuit including expensive components such as an oscillator, and to reduce costs.

  (5) A subordinate apparatus according to another aspect of the present invention is a subordinate apparatus for communicating with a superordinate apparatus, and includes a first port and a second port through which communication signals with other apparatuses are input / output. A port switching control unit capable of setting the first port and the second port as slave ports, and the upper port via at least one of the first port and the second port. A communication control unit for performing processing for establishing a communication connection with the apparatus or the lower apparatus according to claim 1.

  Even with such a configuration, it is possible to improve the use efficiency of apparatus resources as a whole communication system and realize system redundancy with a simple configuration.

  (6) A communication system according to an aspect of the present invention is a communication system including a host device and a plurality of lower devices, wherein the host device and the plurality of lower devices are connected in a ring, and the host device is Including two ports through which communication signals to and from other devices are input / output, and the two ports of the self are used when establishing a communication connection with the lower-level device via the slave port of the lower-level device The master device is set as a master port, and the lower device includes two ports through which communication signals to and from other devices are input / output, and one of the two ports is passed through the slave port of the other lower device. To set the master port used when establishing a communication connection with the other lower device, and the other via the master port of the higher device or the other lower device. Is set as a slave port to be used for establishing a communication connection with the lower apparatus, the lower apparatus, it is possible to perform the switching process of the master port and the slave port.

  With this configuration, in order to realize system redundancy, for example, when providing one standby system, it is only necessary to provide two ports in the lower-level device, and a communication path between the devices is also provided for one system. It will be better. Further, since a pair of slave ports and a master port need only be provided in the lower level device, for example, a pair of slave port circuits and a master port circuit may be provided by using a switch circuit or the like. When one lower apparatus is provided for one upper apparatus and both apparatuses are connected in a one-to-one relationship, unused ports are eliminated and the use efficiency of apparatus resources can be improved. Accordingly, system redundancy can be realized with a simple configuration. Furthermore, the lower-level device can autonomously perform the redundancy switching process without the higher-level device controlling the lower-level device. In addition, with the configuration in which whether or not a communication connection with a higher-level device or another lower-level device can be established is used as a determination criterion for redundant switching execution, existing processing is diverted without newly setting a determination criterion for redundant switching execution. Thus, it is possible to determine whether to perform redundancy switching.

  (7) Preferably, the lower-level device which is the lower-level device in which the master port of the higher-level device and its own master port are connected and the master port of the other lower-level device and its own slave port are connected is When the communication connection with the other lower device is disconnected, the master port and the slave port are switched, and the communication connection with the host device via the slave port after the switching is established. Then, a process of establishing a communication connection with the other lower-order device via the master port after switching is performed.

  With such a configuration, in a communication system in which a host device and a plurality of lower devices are connected in a ring, when communication connection between the lowest device and other lower devices is disconnected, the lower device can be Communication can be restored.

  (8) More preferably, the other lower device is a connection destination via the upper port connected to the lower device other than the lowest device or the higher device among the two ports of its own. When the communication connection with the device is disconnected, the upper port is set as the master port, the lower port connected with the lowest device is set as the slave port, and the highest port via the lower port is set. A process of establishing a communication connection with a lower apparatus and a process of establishing a communication connection with the connection destination apparatus via the upper port are performed.

  With such a configuration, in a communication system in which a higher-level device and a plurality of lower-level devices are connected in a ring, when communication connection between the lowest-level device and other lower-level devices is disconnected, other than the lowest-level device in an appropriate procedure Communication of other lower-level devices can also be restored.

  (9) A communication system according to another aspect of the present invention is a communication system including a host device and a plurality of lower devices, wherein the host device and the plurality of lower devices are connected in a ring, and the host device The device includes two ports through which communication signals to and from other devices are input and output, and when establishing a communication connection with the lower device via the slave port of the lower device via the two ports of the device. The subordinate device includes two ports through which communication signals to and from other devices are input / output, and one of the two ports is set as a slave of the other subordinate device. Set as a master port used when establishing a communication connection with the other lower-level device via the port, and the other device via the master port of the higher-level device or another lower-level device. It can be set as a slave port used when establishing a communication connection with another lower-level device, and can perform switching processing between the master port and the slave port. The above two ports can be set as slave ports.

  Even with such a configuration, it is possible to improve the use efficiency of apparatus resources as a whole communication system and realize system redundancy with a simple configuration.

  (10) A communication control method according to an aspect of the present invention is a communication control method in a communication system including a host device and a plurality of lower devices, wherein the host device and the plurality of lower devices are connected in a ring shape. The master port used when the host device establishes a communication connection with the lower device via the slave port of the lower device using its own two ports through which communication signals with other devices are input / output And the subordinate apparatus sets one of its two ports through which communication signals to / from another apparatus are input / output to the other subordinate apparatus via the slave port of the other subordinate apparatus. Set as a master port used when establishing a communication connection, and the other is connected to the upper apparatus or the other lower apparatus via the master port of the upper apparatus or another lower apparatus. And setting the slave port is used when establishing a communication connection, the lower device, and a step of performing a switching process of the master port and the slave port.

  With this configuration, in order to realize system redundancy, for example, when providing one standby system, it is only necessary to provide two ports in the lower-level device, and a communication path between the devices is also provided for one system. It will be better. Further, since a pair of slave ports and a master port need only be provided in the lower level device, for example, a pair of slave port circuits and a master port circuit may be provided by using a switch circuit or the like. When one lower apparatus is provided for one upper apparatus and both apparatuses are connected in a one-to-one relationship, unused ports are eliminated and the use efficiency of apparatus resources can be improved. Accordingly, system redundancy can be realized with a simple configuration. Furthermore, the lower-level device can autonomously perform the redundancy switching process without the higher-level device controlling the lower-level device. In addition, with the configuration in which whether or not a communication connection with a higher-level device or another lower-level device can be established is used as a determination criterion for redundant switching execution, existing processing is diverted without newly setting a determination criterion for redundant switching execution. Thus, it is possible to determine whether to perform redundancy switching.

  According to the present invention, system redundancy can be realized with a simple configuration.

It is a figure which shows the structure of the communication system which concerns on embodiment of this invention. It is a functional block diagram of the remote radio head concerning an embodiment of the invention. It is a figure which shows the structure of the synchronous process part in the remote radio head which concerns on embodiment of this invention. It is a figure which shows the redundant switching operation | movement by the comparative example of the communication system which concerns on embodiment of this invention. It is a figure which shows the redundant switching operation | movement by the comparative example of the communication system which concerns on embodiment of this invention. It is a figure which shows the structure for performing the port switching process in the remote radio head which concerns on embodiment of this invention. It is a figure which shows the structure for performing the port switching process in the remote radio head which concerns on embodiment of this invention. It is the flowchart which defined the operation | movement procedure at the time of the low-order apparatus in the communication system which concerns on embodiment of this invention setting a port classification. It is a figure which shows the redundant switching operation | movement by the communication system which concerns on embodiment of this invention. It is a figure which shows the redundant switching operation | movement by the communication system which concerns on embodiment of this invention. It is a figure which shows the redundant switching operation | movement by the communication system which concerns on embodiment of this invention. It is a figure which shows the operation | movement at the time of the failure generation by the modification of the communication system which concerns on embodiment of this invention. It is a figure which shows the redundant switching operation | movement by the modification of the communication system which concerns on embodiment of this invention. It is a figure which shows the redundant switching operation | movement by the modification of the communication system which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a diagram showing a configuration of a communication system according to an embodiment of the present invention.

  With reference to FIG. 1, the communication system 201 includes lower devices 101 </ b> A, 101 </ b> B, and 101 </ b> C and a higher device 102. Hereinafter, each of the lower devices 101A, 101B, and 101C may be referred to as a lower device 101.

  The communication system 201 is, for example, a radio base station device. That is, the lower apparatus 101 is, for example, a remote radio head (RRH), and the upper apparatus 102 is, for example, a main apparatus, that is, a base station main body. Hereinafter, a system configuration in which the radio base station apparatus 201 includes the remote radio head 101 and the main body apparatus 102 will be described as an example. However, the present invention is not limited to this, and the communication system 201 includes an upper apparatus and one or more lower apparatuses. Any communication system provided with a device may be used. Hereinafter, each of the remote radio heads 101A, 101B, and 101C may be referred to as a remote radio head 101.

  The radio base station apparatus 201 is provided in, for example, a WiMAX (Worldwide Interoperability for Microwave Access) system. In WiMAX according to the IEEE 802.16 standard, a TDD (Time Division Duplex) method is adopted. That is, in the WiMAX system, an uplink transmission period for transmitting communication data from the radio terminal apparatus to the radio base station apparatus and a downlink transmission period for transmitting communication data from the radio base station apparatus to the radio terminal apparatus are switched. Are repeated alternately.

  Specifically, the radio base station apparatus 201 performs transmission and reception of communication data with the radio terminal apparatus 301 by switching over time. Here, the communication data generated in each of the radio base station apparatus 201 and the radio terminal apparatus 301 is subjected to various signal processing by the radio base station apparatus 201 and the radio terminal apparatus 301 in accordance with the WiMAX standard, and finally the radio data. After being converted to a signal, it is transmitted to radio terminal apparatus 301 and radio base station apparatus 201, respectively.

  The remote radio head 101 is attached to an antenna pole 104 installed on the roof of a building. An antenna 103 is attached to the antenna pole 104.

  The remote radio head 101 converts a wireless signal received from the wireless terminal device 301 via the antenna 103 into a digital signal and outputs the digital signal to the main device 102 via the optical fiber 105. Further, the remote radio head 101 converts a digital signal received from the main body apparatus 102 via the optical fiber 105 into a radio signal and transmits the radio signal to the radio terminal apparatus 301 via the antenna 103.

  The main unit 102 and the remote radio heads 101A, 101B, 101C are connected in a ring shape. The remote radio heads 101 </ b> A, 101 </ b> B, and 101 </ b> C can relay signals transmitted / received between the main device 102 and other remote radio heads 101.

  FIG. 2 is a functional block diagram of the remote radio head according to the embodiment of the present invention.

  Referring to FIG. 2, the remote radio head 101 includes a control unit 61, a signal processing unit 81, a wireless transmission unit 71, a wireless reception unit 72, and a transmission / reception changeover switch 86. The wireless transmission unit 71 includes a digital / analog converter (DAC) 82, a modulator 83, a driver amplifier 84, a power amplifier 85, and an oscillator 87. The wireless reception unit 72 includes reception amplifiers 89 and 90, a mixer 91, a BPF (Band Pass Filter) 92, an analog / digital converter (ADC) 93, and an oscillator 94. The signal processing unit 81 includes a synchronization processing unit 51.

  The control unit 61 controls each unit such as the signal processing unit 81 in the remote radio head 101.

  The signal processing unit 81 performs signal processing on the digital signal received from the main body device 102 via the port # 0 or the port # 1, and outputs the signal to the wireless transmission unit 71. In the embodiment of the present invention, the “port” may be physical such as a connector, or may be logical.

  In the signal processing unit 81, the synchronization processing unit 51 determines that its own remote radio head 101 is connected to the main unit 102 and other remote radios based on reception data that is a digital signal received from the main unit 102 or other remote radio head 101. A reference timing signal for operating in synchronization with the head 101 is generated.

  The radio transmission unit 71 converts the digital signal received from the signal processing unit 81 into an analog signal, converts the converted analog signal into a radio signal, that is, an RF (Radio Frequency) band signal, and transmits the radio signal to the radio terminal device 301.

  The wireless reception unit 72 receives a wireless signal from the wireless terminal device 301, converts it into an IF (Intermediate Frequency) signal, converts the converted IF signal into a digital signal, and outputs the digital signal to the signal processing unit 81.

  The signal processing unit 81 performs various signal processing on the digital signal received from the wireless reception unit 72 and outputs the digital signal to the main body device 102 via the optical fiber 105.

  More specifically, the digital / analog converter 82 converts the digital signal received from the signal processing unit 81 into an analog signal and outputs the analog signal to the modulator 83.

  The oscillator 87 generates a local oscillation signal and outputs it to the modulator 83. Modulator 83 multiplies the baseband analog signal received from digital / analog converter 82 by the local oscillation signal received from oscillator 87, for example, to orthogonally modulate the analog signal received from digital / analog converter 82. Then, it is converted into a radio signal and output to the driver amplifier 84.

  Driver amplifier 84 amplifies the radio signal received from modulator 83 and outputs the amplified signal to power amplifier 85.

  Power amplifier 85 further amplifies the radio signal received from driver amplifier 84. The wireless signal amplified by the power amplifier 85 is transmitted to the wireless terminal device 301 via the transmission / reception selector switch 86 and the antenna 103.

  The reception amplifier 89 is, for example, an LNA (Low Noise Amplifier), receives a radio signal from the wireless terminal device 301 via the antenna 103 and the transmission / reception selector switch 86, amplifies the received radio signal, and outputs the amplified signal to the reception amplifier 90. .

  Receiving amplifier 90 is, for example, an LNA, and further amplifies the radio signal received from receiving amplifier 89 and outputs the amplified signal to mixer 91.

  The oscillator 94 generates a local oscillation signal and outputs it to the mixer 91. Mixer 91 multiplies the radio signal received from reception amplifier 90 by the local oscillation signal received from oscillator 94, thereby converting the radio signal received from reception amplifier 90 into an IF signal and outputs the IF signal to bandpass filter 92. .

  The bandpass filter 92 outputs a signal obtained by attenuating a component outside a predetermined frequency band among the frequency components of the IF signal received from the mixer 91 to the analog / digital converter 93.

  The analog / digital converter 93 converts the IF signal received from the bandpass filter 92 into a digital signal and outputs the digital signal to the signal processing unit 81.

  The signal processing unit 81 performs, for example, quadrature demodulation on the IF band digital signal received from the analog / digital converter 93 to convert it into a baseband digital signal, and outputs the baseband digital signal to the main unit 102 via the port # 0 or the port # 1. . The signal processing unit 81 relays a digital signal transmitted / received between the main device 102 and another remote radio head 101 via the port # 0 and the port # 1.

  The transmission / reception selector switch 86 outputs a radio signal received from the power amplifier 85 to the antenna 103 based on a control signal (not shown) received from the signal processing unit 81 or outputs a radio signal received from the antenna 103 to the reception amplifier 89. Switch what to do.

  FIG. 3 is a diagram showing a configuration of a synchronization processing unit in the remote radio head according to the embodiment of the present invention.

  The remote radio head 101 needs to operate in synchronization with the main device 102. For this reason, the remote radio head 101 generates a reference timing signal, for example, a reference clock, based on some signal transmitted from the main device 102, for example. In order to generate such a timing signal, the remote radio head 101 is provided with, for example, a PLL (Phase Locked Loop) circuit.

  Specifically, referring to FIG. 3, synchronization processing unit 51 includes a CDR (Clock and Data Recovery) unit 11 and a PLL unit 12. The CDR unit 11 includes a retiming unit 21 and a timing signal generation unit 22. The PLL unit 12 includes a phase comparator 23, a loop filter 24, and a VCXO (Voltage Controlled Crystal Oscillator) 25.

  The CDR unit 11 reshapes the received data received from the main device 102 or another remote radio head 101 and extracts the timing from the received data. Specifically, the CDR unit 11 generates and outputs a reproduction timing signal from received data that is a digital signal received from the main device 102 or another remote radio head 101.

  More specifically, in the CDR unit 11, the timing signal generation unit 22 generates a reproduction timing signal that is, for example, a clock, based on reception data received from the main device 102 or another remote radio head 101. The timing signal generation unit 22 extracts the timing, for example, by monitoring the rising and falling edges of the digital signal received from the main device 102 or another remote radio head 101.

  Further, the retiming unit 21 uses the reference timing signal whose jitter is suppressed by the PLL unit 12 to retime the received data from the main device 102 or another remote radio head 101, thereby re-receiving the received data. Shape it. That is, the retiming unit 21 holds and outputs received data in response to the reference timing signal generated by the PLL unit 12. The reshaped received data is processed in its own remote radio head 101, or is output to the main apparatus 102 or another remote radio head 101 via port # 0 or port # 1.

  The PLL unit 12 controls the VCXO 25 based on the timing extracted by the CDR unit 11. More specifically, the PLL unit 12 includes a VCXO 25, generates the control voltage VC based on the reproduction timing signal generated by the timing signal generation unit 22, and supplies the control voltage VC to the VCXO 25. As a result, the PLL unit 12 generates a reference timing signal having a frequency component in which a component equal to or higher than a predetermined frequency is attenuated among the frequency components of the reproduction timing signal and synchronized with the reproduction timing signal.

  Specifically, the PLL unit 12 constitutes a PLL circuit. That is, in the PLL unit 12, the phase comparator 23 compares the phase of the reproduction timing signal received from the timing signal generation unit 22 with the phase of the reference timing signal received from the VCXO 25, and loops a phase difference signal indicating the comparison result. Output to the filter 24.

  The followability of the PLL circuit is set by the time constant of the loop filter 24. Specifically, the time constant of the loop filter 24 is set so that the PLL circuit does not follow noise having high frequency components such as harmonics.

  The VCXO 25 generates an oscillation signal and outputs it as a reference timing signal. The VCXO 25 receives the phase difference signal that has passed through the loop filter 24 as the control voltage VC, and changes the frequency of the oscillation signal in accordance with the control voltage VC. The oscillation signal output from the VCXO 25 is output to each circuit in the retiming unit 21, the phase comparator 23, and the remote radio head 101, for example, a digital signal transmission circuit to the main body device 102 or another remote radio head 101. .

[Redundant switching process of comparative example]
First, the redundancy switching process by the comparative example of the communication system which concerns on embodiment of this invention is demonstrated.

  FIG. 4 is a diagram showing a redundant switching operation according to a comparative example of the communication system according to the embodiment of the present invention. FIG. 4 shows a case where one upper device and one lower device are provided in the communication system. A solid line between the apparatuses indicates an active communication path, a broken line indicates a standby communication path, and a cross indicates disconnection of the communication connection.

  With reference to FIG. 4, the communication system includes a lower device 111 and a higher device 112.

  The host device 112 has port # 0 and port # 1, and port # 0 and port # 1 are set as master ports.

  The subordinate device 111 has a port # 0 and a port # 1, and the port # 0 and the port # 1 are set as slave ports.

  Here, the slave port generates a reference timing signal for the lower device 111 to operate in synchronization with the upper device 112 based on the digital signal transmitted from the master port of the upper device 112 as shown in FIG. A synchronous processing unit is connected.

  The upper device 112 and the lower device 111 transmit / receive communication signals to / from each other via each port # 0 using each port # 0 as an active system and each port # 1 as a standby system.

  For such a normal state, for example, a failure occurs in the communication path between port # 0 of the higher-level device 112 and port # 0 of the lower-level device 111, and the communication connection between the higher-level device 112 and the lower-level device 111 is established. Suppose that it is disconnected.

  Then, the upper device 112 and the lower device 111 use each port # 1 as an active system, each port # 0 as a standby system, and transmit / receive communication signals to / from each other via each port # 1. For example, the lower level device 111 does not actively determine the redundancy switching, and the higher level device 112 detects the disconnection of the communication connection with the lower level device 111 and establishes the communication connection with the lower level device 111 via the port # 1. The process to start is started. As a result, port # 1 of the lower level device 111 becomes the active system.

  FIG. 5 is a diagram showing a redundant switching operation according to a comparative example of the communication system according to the embodiment of the present invention. FIG. 5 shows a case where one upper apparatus and three lower apparatuses are provided in the communication system, and each apparatus is cascade-connected. The way of viewing the figure is the same as in FIG.

  Referring to FIG. 5, the communication system includes lower devices 111A, 111B, 111C and a higher device 112.

  The host device 112 has port # 0 and port # 1, and port # 0 and port # 1 are set as master ports.

  The subordinate device 111 has ports # 0 to # 3, the port # 0 and the port # 2 are set as slave ports, and the port # 1 and the port # 3 are set as master ports.

  The host device 112 uses the port # 0 as the active system, the port # 1 as the standby system, the subordinate device 111 sets the port # 0 and the port # 1 as the active system, and the ports # 2 and the port # 3 as the standby system. And

  The upper device 112 and the lower device 111A transmit and receive communication signals to and from each other via each port # 0. The lower device 111A and the lower device 111B transmit and receive communication signals to and from each other via port # 1 and port # 0, respectively. The lower device 111B and the lower device 111C transmit and receive communication signals to and from each other via port # 1 and port # 0, respectively.

  For such a normal state, for example, a failure occurs in the communication path between port # 1 of the lower device 111A and port # 0 of the lower device 111B, and communication connection between the lower device 111A and the lower device 111B is established. Suppose that it is disconnected.

  Then, the upper device 112 sets the port # 1 as the active system, the port # 0 as the standby system, the lower device 111 sets the port # 2 and the port # 3 as the active system, and the port # 0 and the port # 1 as the standby system. And That is, the upper device 112 and the lower device 111A transmit and receive communication signals to and from each other via the port # 1 and the port # 2, respectively. The lower device 111A and the lower device 111B transmit and receive communication signals to and from each other via port # 3 and port # 2, respectively. The lower device 111B and the lower device 111C transmit and receive communication signals to and from each other via port # 3 and port # 2, respectively.

  More specifically, for example, the lower level device 111 does not actively determine the redundancy switching, and the higher level device 112 detects the disconnection of the communication connection with the lower level device 111 and communicates with the lower level device 111 via the port # 1. The process of establishing the communication connection of is started. As a result, port # 2 and port # 3 of the lower-level device 111 become active.

  In the communication system as described with reference to FIGS. 4 and 5, four ports and two synchronization processing units are required for the active system and the standby system, particularly in the lower apparatus 111, and two optical fibers are connected between the apparatuses. Minutes are needed. As shown in FIG. 4, when one lower device 111 is provided for one upper device 112 and the two devices are connected in a one-to-one relationship, the lower device 111 capable of cascade connection as shown in FIG. If, for example, port # 1 and port # 3 and one synchronization processing unit 51 in the lower-level device 111 are not used, a lot of waste occurs.

  Thus, the communication system according to the embodiment of the present invention solves such problems by the following configuration and operation.

Detailed configuration
6 and 7 are diagrams showing a configuration for executing port switching processing in the remote radio head according to the embodiment of the present invention.

  Referring to FIGS. 6 and 7, remote radio head 101 further includes a ROM (Read Only Memory) 33. The control unit 61 includes a communication control unit 31 and a port switching control unit 32. The signal processing unit 81 further includes a PLD (Programmable Logic Device) 52. The PLD 52 is, for example, an FPGA (Field Programmable Gate Array) or a CPLD (Complex Programmable Logic Device).

  Communication signals with other devices are input / output via port # 0 and port # 1. The port switching control unit 32 can set one of the port # 0 and the port # 1 as a master port and the other as a slave port.

  The communication control unit 31 performs processing for establishing a communication connection with another apparatus via the port # 0 and the port # 1.

  The port switching control unit 32 performs a master port / slave port switching process when the communication control unit 31 cannot establish a communication connection with the upper level device 102 or another lower level device 101 via the slave port.

  Then, when the switching process by the port switching control unit 32 is performed, the communication control unit 31 performs a process of establishing a communication connection with the higher level device 102 or the other lower level device 101 via the slave port after switching.

  Further, for example, when the port switching control unit 32 cannot establish a communication connection with another device via one of the ports # 0 and # 1, which is set as the slave port, the one port Is set as the master port.

  And the communication control part 31 performs the process which establishes a communication connection with the said other apparatus via the said one port set to the master port.

  Further, for example, the port switching control unit 32 changes the circuit configuration of the PLD 52 so that the port associated with the slave circuit used when transmitting / receiving the communication signal via the slave port is between the port # 0 and the port # 1. By switching, master port and slave port switching processing is performed.

  Here, the slave circuit is, for example, a circuit for generating a reference timing signal based on data received from the master port of the higher-level device 102 or the master port of another lower-level device 101, that is, the synchronization processing unit 51.

  Specifically, the communication control unit 31 notifies the port switching control unit 32 of information on the communication state with other devices via the port # 0 and the port # 1.

  The ROM 33 stores configuration data for the PLD 52. More specifically, the ROM 33 has a circuit configuration in which the synchronization processing unit 51 is connected to the port # 0 as shown in FIG. 6, that is, a circuit configuration A in which the port # 0 is a slave port and the port # 1 is a master port. Store the data. Further, the ROM 33 stores the data of the circuit configuration B in which the synchronization processing unit 51 is connected to the port # 1, as shown in FIG. 7, that is, the circuit configuration B in which the port # 1 is the slave port and the port # 0 is the master port. To do.

  The port switching control unit 32 selects one of the circuit configurations A and B based on the information notified from the communication control unit 31, reads the data of the selected circuit configuration from the ROM 33, and loads it into the PLD 52.

  The PLD 52 changes the circuit configuration according to the data loaded by the port switching control unit 32.

  Note that the remote radio head 101 may not include the PLD 52. In this case, the port switching control unit 32 can switch the port associated with the slave circuit between the port # 0 and the port # 1 by using a switch circuit or the like.

  The slave circuit is not limited to the synchronization processing unit 51, and may be any circuit that is necessary when using a slave port.

[Operation]
Next, the operation when the communication system according to the embodiment of the present invention performs redundant switching will be described with reference to the drawings.

  FIG. 8 is a flowchart defining an operation procedure when the lower-level device in the communication system according to the embodiment of the present invention sets the port type.

  Referring to FIG. 8, first, when the own lower apparatus 101 is activated or the communication connection between the main apparatus 102 or another lower apparatus 101 and the own lower apparatus 101 is disconnected, the port switching control unit 32 confirms whether or not the primary port and the synchronization processing unit 51 which is a slave circuit are connected. Here, in the lower apparatus 101, for example, port # 0 is set in advance as a primary port (step S1).

  When the primary port and the slave circuit are not connected (YES in step S1), the port switching control unit 32 changes the circuit configuration of the PLD 52 and connects the primary port to the slave circuit (step S2). .

  Next, the communication control unit 31 performs rate negotiation processing using the slave port. More specifically, the communication control unit 31 sequentially selects a communication speed from a plurality of predetermined communication speeds, and transmits / receives predetermined information to / from the main device 102 or another lower-level device 101, thereby making its own lower-level device. A communication speed that enables communication between the main apparatus 101 and the main apparatus 102 or another lower apparatus 101 is searched (step S3).

  On the other hand, when the primary port and the slave circuit are connected (NO in step S1), the port switching control unit 32 performs rate negotiation processing using the slave port without changing the circuit configuration of the PLD 52. Perform (step S3).

  Next, the communication control unit 31 is a case where the communication connection between the lower apparatus 101 and the main apparatus 102 or another lower apparatus 101 is not established even if the link establishment process is performed (NO in step S4). If the own lower apparatus 101 does not have a redundant configuration (NO in step S7), the rate is set until a communication connection is established between the own lower apparatus 101 and the main apparatus 102 or another lower apparatus 101. The negotiation process is repeated (step S3).

  On the other hand, the communication control unit 31 changes the circuit configuration of the PLD 52 to change the primary configuration when the subordinate device 101 has a redundant configuration, that is, a secondary port (YES in step S7). For example, the port is connected to the master circuit, and the secondary port is connected to the slave circuit. Here, in the lower apparatus 101, for example, port # 1 is set in advance as a secondary port (step S8).

  Next, the communication control unit 31 performs a rate negotiation process using the newly set slave port, that is, the secondary port (step S9).

  Next, the communication control unit 31 does not establish a communication connection between the lower apparatus 101 and the main apparatus 102 or another lower apparatus 101 even after performing the link establishment process (NO in step S10). The circuit configuration of the PLD 52 is changed to connect the primary port to the slave circuit (step S2), and the rate negotiation process using the newly set slave port, that is, the primary port is performed (step S3).

  On the other hand, when the communication control unit 31 performs a link establishment process and establishes a communication connection between the lower apparatus 101 and the main apparatus 102 or another lower apparatus 101 (YES in step S4 or YES in step S10). It is confirmed whether another lower level device 101 is connected to its own master port (step S13).

  If there is no other lower-level device 101 connected to its own master port (NO in step S13), the communication control unit 31 ends the process.

  On the other hand, if there is another lower level device 101 connected to its own master port (YES in step S13), the communication control unit 31 sets the master port under the communication speed selected by the other lower level device 101. The link establishment process using is performed.

  When the communication connection between the other lower device 101 and the own lower device 101 is established at the communication speed selected by the other lower device 101 (YES in step S15), the communication control unit 31 ends the process. .

  On the other hand, when the communication connection between the other lower device 101 and its own lower device 101 is not established at the communication speed selected by the other lower device 101 (NO in step S15), The link establishment process using the master port is performed under the communication speed newly selected by the other lower-level device 101 (step S14).

[Redundancy switching processing of communication system according to embodiment of present invention]
In the communication system according to the embodiment of the present invention, the host device 102 includes two ports through which communication signals to and from other devices are input and output, and the own two ports are set as slave ports of the lower device 101. To the master port used when establishing a communication connection with the lower level device 101 via

  The lower device 101 includes two ports through which communication signals with other devices are input / output. One of the two ports is connected to the other lower device 101 via the slave port of the other lower device 101. Set to the master port used when establishing a communication connection with. Further, the lower apparatus 101 uses the other of its two ports when establishing a communication connection with the upper apparatus 102 or the other lower apparatus 101 via the master port of the upper apparatus 102 or another lower apparatus 101. Set to slave port.

  Then, the lower level device 101 can perform a switching process between the master port and the slave port.

  FIG. 9 is a diagram showing a redundant switching operation by the communication system according to the embodiment of the present invention. FIG. 9 shows a case where one host apparatus 102 and one lower apparatus 101 are provided in the communication system 201. The underlined slave port and master port indicate ports after the switching process. A solid line between the apparatuses indicates an active communication path, a broken line indicates a standby communication path, and a cross indicates disconnection of the communication connection.

  Referring to FIG. 9, the communication system 201 includes a lower device 101 and a higher device 102.

  The host device 102 has port # 0 and port # 1, and sets port # 0 and port # 1 as master ports.

  The lower level device 101 has a port # 0 and a port # 1, and normally sets the port # 0 as a slave port and sets the port # 1 as a master port.

  The upper device 102 and the lower device 101 use each port # 0 as an active system, each port # 1 as a standby system, and transmit / receive communication signals to / from each other via each port # 0.

  For such a normal state (step S41), for example, a failure occurs in the communication path between port # 0 of the higher-level device 102 and port # 0 of the lower-level device 101, and between the higher-level device 102 and the lower-level device 101. Suppose that the communication connection is disconnected.

  Then, the lower level apparatus 101 performs a process of switching between the master port and the slave port, for example, by the operation shown in FIG. Specifically, the lower level apparatus 101 sets port # 0 as a master port and sets port # 1 as a slave port.

  As a result, each port # 1 of the higher level device 102 and the lower level device 101 becomes the active system, and each port # 0 becomes the standby system, and the higher level device 102 and the lower level device 101 send the communication signal via each port # 1. Data are transmitted and received with each other (step S42).

  10 and 11 are diagrams showing a redundant switching operation by the communication system according to the embodiment of the present invention. FIG. 10 and FIG. 11 show a case where one upper apparatus and three lower apparatuses are provided in the communication system, and each apparatus is cascade-connected and connected in a ring shape. The way of viewing the figure is the same as in FIG.

  With reference to FIGS. 10 and 11, the communication system 201 includes lower-level devices 101 </ b> A, 101 </ b> B, and 101 </ b> C and a higher-level device 102.

  The host device 102 has port # 0 and port # 1, and sets port # 0 and port # 1 as master ports.

  The lower level device 101 has a port # 0 and a port # 1, and normally sets the port # 0 as a slave port and sets the port # 1 as a master port.

  The host apparatus 102 sets the port # 0 as the active system and the port # 1 as the standby system. In the lower devices 101A, 101B, and 101C, port # 1 of the lower device 101C is set as a standby system, and all other ports are set as active systems.

  The upper device 102 and the lower device 101A transmit and receive communication signals to and from each other via each port # 0. The lower apparatus 101A and the lower apparatus 101B transmit and receive communication signals to and from each other via port # 1 and port # 0, respectively. The lower device 101B and the lower device 101C transmit and receive communication signals to and from each other via port # 1 and port # 0, respectively.

  For such a normal state (step S21), for example, a failure occurs in the communication path between port # 1 of the lower apparatus 101A and port # 0 of the lower apparatus 101B, and the lower apparatus 101A and the lower apparatus 101B are connected. Is disconnected (step S22).

  Next, with the disconnection of the communication connection between the lower apparatus 101A and the lower apparatus 101B, the communication connection between the lower apparatus 101B and the lower apparatus 101C is disconnected (step S23).

  Next, the lower order apparatus 101C sets port # 0 as a master port and sets port # 1 as a slave port, for example, by the operation shown in FIG. As a result, port # 1 of the higher-level device 102 becomes the active system, port # 1 of the lower-level device 101C becomes the active system, and the higher-level device 102 is the master and the lower-level device 101C is the slave. A communication connection is established. That is, the upper apparatus 102 and the lower apparatus 101C transmit and receive communication signals to and from each other via each port # 1 (step S24).

  Next, the lower level apparatus 101B sets port # 0 as a master port and sets port # 1 as a slave port, for example, by the operation shown in FIG. As a result, a communication connection is established between the lower apparatus 101C and the lower apparatus 101B using the lower apparatus 101C as a master and the lower apparatus 101B as a slave. That is, the lower order device 101C and the lower order device 101B transmit and receive communication signals to and from each other via port # 0 and port # 1, respectively. Also, port # 1 of the lower level device 101A and port # 0 of the lower level device 101B become standby systems (step S25).

  In the communication system 201, the lowest level device is connected to the master port of the higher level device 102 and its own master port, and the master port of the other lower level device 101 is connected to its own slave port. This is the low-order apparatus 101C at the normal time.

  When the communication connection with the other lower-level device 101B is disconnected, the lowest-level device 101C performs the switching process of the master port and the slave port, and establishes the communication connection with the higher-level device 102 via the slave port after switching. And a process for establishing a communication connection with the other lower-level device 101B via the master port after switching.

  In addition, the other lower device 101B is a device connected to the lower device other than the lowest device 101 or the upper device connected to the upper device 102 among its two ports, for example, in FIG. When the communication connection with the lower apparatus 101A is disconnected, the upper port is set as a master port, and the lower port connected with the lowest apparatus 101C is set as a slave port. Then, the other lower device 101B performs a process of establishing a communication connection with the lowest device 101C via the lower port and a process of establishing a communication connection with the connection destination device 101A via the upper port. Do.

[Modification]
The subordinate apparatus according to the embodiment of the present invention is configured to set one of port # 0 and port # 1 as a master port and the other as a slave port. However, the present invention is not limited to this. Absent. The lower level device 101 may be configured to set both port # 0 and port # 1 as slave ports.

  That is, in this lower level device 101, the port switching control unit 32 can set the port # 0 and the port # 1 as slave ports. Then, the communication control unit 31 performs processing for establishing a communication connection with the upper apparatus 102 or another lower apparatus 101 via at least one of the port # 0 and the port # 1.

  FIG. 12 is a diagram illustrating an operation when a failure occurs according to a modification of the communication system according to the embodiment of the present invention. FIG. 12 shows a case where one host apparatus 102 and one lower apparatus 101 are provided in the communication system 201. A solid line between the apparatuses indicates an active communication path, a broken line indicates a standby communication path, and a cross indicates disconnection of the communication connection.

  Referring to FIG. 12, the communication system 201 includes a lower device 101 and a higher device 102.

  The host device 102 has port # 0 and port # 1, and sets port # 0 and port # 1 as master ports.

  The lower level device 101 has port # 0 and port # 1, and sets port # 0 and port # 1 as slave ports.

  The upper device 102 and the lower device 101 use each port # 0 as an active system, each port # 1 as a standby system, and transmit / receive communication signals to / from each other via each port # 0.

  For such a normal state (step S51), for example, a failure occurs in the communication path between port # 0 of the higher-level device 102 and port # 0 of the lower-level device 101, and between the higher-level device 102 and the lower-level device 101. Suppose that the communication connection is disconnected.

  Then, each port # 1 of the upper apparatus 102 and the lower apparatus 101 becomes an active system, each port # 0 becomes a standby system, and the upper apparatus 102 and the lower apparatus 101 exchange communication signals with each other via each port # 1. Transmission / reception is performed (step S52).

  13 and 14 are diagrams showing a redundant switching operation according to a modification of the communication system according to the embodiment of the present invention. FIG. 13 and FIG. 14 show a case where one upper apparatus and three lower apparatuses are provided in the communication system, and each apparatus is cascade-connected. The underlined slave port and master port indicate ports after the switching process. Other views are the same as in FIG.

  With reference to FIG. 13 and FIG. 14, the communication system 201 includes lower-level devices 101A, 101B, and 101C and a higher-level device 102.

  The host device 102 has port # 0 and port # 1, and sets port # 0 and port # 1 as master ports.

  The lower devices 101A and 101B have port # 0 and port # 1, and normally set port # 0 as a slave port and port # 1 as a master port. The lower device 101C has port # 0 and port # 1, and normally sets port # 0 and port # 1 as slave ports.

  The host apparatus 102 sets the port # 0 as the active system and the port # 1 as the standby system. In the lower devices 101A, 101B, and 101C, port # 1 of the lower device 101C is set as a standby system, and all other ports are set as active systems.

  The upper device 102 and the lower device 101A transmit and receive communication signals to and from each other via each port # 0. The lower apparatus 101A and the lower apparatus 101B transmit and receive communication signals to and from each other via port # 1 and port # 0, respectively. The lower device 101B and the lower device 101C transmit and receive communication signals to and from each other via port # 1 and port # 0, respectively.

  For such a normal state (step S31), for example, a failure occurs in the communication path between the port # 1 of the lower level device 101A and the port # 0 of the lower level device 101B, and the lower level device 101A and the lower level device 101B are connected. Is disconnected (step S32).

  Next, with the disconnection of the communication connection between the lower apparatus 101A and the lower apparatus 101B, the communication connection between the lower apparatus 101B and the lower apparatus 101C is disconnected (step S33).

  Next, the lower order apparatus 101C sets port # 0 as a master port and sets port # 1 as a slave port. As a result, port # 1 of the higher-level device 102 becomes the active system, port # 1 of the lower-level device 101C becomes the active system, and the higher-level device 102 is the master and the lower-level device 101C is the slave. A communication connection is established. In other words, the upper device 102 and the lower device 101C transmit and receive communication signals to and from each other via each port # 1 (step S34).

  Next, the lower order apparatus 101B sets port # 0 and port # 1 as slave ports. As a result, a communication connection is established between the lower apparatus 101C and the lower apparatus 101B using the lower apparatus 101C as a master and the lower apparatus 101B as a slave. That is, the lower order device 101C and the lower order device 101B transmit and receive communication signals to and from each other via port # 0 and port # 1, respectively. Further, the port # 1 of the lower level apparatus 101A and the port # 0 of the lower level apparatus 101B become standby systems (step S35).

  By the way, in order to realize redundancy in a communication system in which each remote radio head is cascade-connected, at least two input / output ports of the base station main body are required for the active system and the standby system. At least two output ports are required, and at least two optical fibers are required between the devices. In a system that realizes such redundancy, when one remote radio head is provided for one base station body and both devices are connected one-to-one, each input / output in the remote radio head is performed. Half of the ports are unused.

  On the other hand, in the subordinate apparatus according to the embodiment of the present invention, the port switching control unit 32 can set one of the port # 0 and the port # 1 as a master port and the other as a slave port. . The communication control unit 31 performs processing for establishing a communication connection with another apparatus via the port # 0 and the port # 1. The port switching control unit 32 performs a master port / slave port switching process when a communication connection with the host device 102 or another lower device 101 via the slave port cannot be established. Then, when the switching process by the port switching control unit 32 is performed, the communication control unit 31 performs a process of establishing a communication connection with the higher level device 102 or the other lower level device 101 via the slave port after switching.

  With this configuration, in order to realize system redundancy, for example, when providing one standby system, it is only necessary to provide two ports in the lower level device 101, and also provide a communication path for one system between the devices. It will be better. Further, since a pair of slave ports and master ports need only be provided in the lower level device 101, for example, a pair of slave port circuits and master port circuits may be provided by using a switch circuit or the like. When one lower apparatus 101 is provided for one upper apparatus 102 and both apparatuses are connected in a one-to-one relationship, unused ports are eliminated and the use efficiency of apparatus resources can be improved. Therefore, in the subordinate apparatus according to the embodiment of the present invention, system redundancy can be realized with a simple configuration.

  Further, the lower apparatus 101 can autonomously perform the redundancy switching process without the upper apparatus 102 controlling the lower apparatus 101. In addition, with the configuration in which whether or not a communication connection with the higher-level device 102 or another lower-level device 101 can be established is used as a determination criterion for redundant switching execution, existing processing can be performed without newly setting a determination criterion for redundant switching execution. It is possible to make a decision to execute redundancy switching.

  Further, the subordinate apparatus according to the embodiment of the present invention further includes a PLD 52. Then, the port switching control unit 32 changes the circuit configuration of the PLD 52 and switches the port associated with the slave circuit used when transmitting / receiving the communication signal via the slave port between the port # 0 and the port # 1. Thus, the master port and the slave port are switched.

  With such a configuration, the master port and slave port switching process can be performed only by changing the circuit configuration in the PLD without separately providing a circuit such as a switch for switching the master port and the slave port.

  In the lower level device according to the embodiment of the present invention, the port switching control unit 32 communicates with another device via one of the ports # 0 and # 1 set as the slave port. If the port cannot be established, set that port as the master port. And the communication control part 31 performs the process which establishes a communication connection with the said other apparatus via the said one port set to the master port.

  With such a configuration, it is possible to establish communication connection with another device on the slave port side after switching, and establish communication connection with another device on the master port side after switching.

  In the subordinate apparatus according to the embodiment of the present invention, the slave circuit generates a reference timing signal based on data received from the master port of the upper apparatus 102 or the master port of another subordinate apparatus 101. It is.

  With such a configuration, it is possible to prevent unnecessary provision of a clock recovery circuit including expensive components such as an oscillator, and to reduce costs.

  Further, in the communication system according to the embodiment of the present invention, the lower-level device 101 can further set its two ports as slave ports. That is, in the subordinate apparatus according to the embodiment of the present invention, the port switching control unit 32 can set the port # 0 and the port # 1 as slave ports. Then, the communication control unit 31 performs processing for establishing a communication connection with the upper apparatus 102 or another lower apparatus 101 via at least one of the port # 0 and the port # 1.

  Even with such a configuration, it is possible to improve the use efficiency of apparatus resources as a whole communication system and realize system redundancy with a simple configuration.

  Further, in the communication system according to the embodiment of the present invention, the upper device 102 and the plurality of lower devices 101 are connected in a ring shape. The host device 102 includes two ports through which communication signals with other devices are input and output, and establishes a communication connection with the lower device 101 via its own two ports via the slave port of the lower device 101 Set to the master port used when The lower device 101 includes two ports through which communication signals with other devices are input / output. One of the two ports is connected to the other lower device 101 via the slave port of the other lower device 101. Set to the master port used when establishing a communication connection with. Further, the lower apparatus 101 uses the other of its two ports when establishing a communication connection with the upper apparatus 102 or the other lower apparatus 101 via the master port of the upper apparatus 102 or another lower apparatus 101. Set to slave port. Then, the lower level device 101 can perform a switching process between the master port and the slave port.

  With this configuration, in order to realize system redundancy, for example, when providing one standby system, it is only necessary to provide two ports in the lower level device 101, and also provide a communication path for one system between the devices. It will be better. Further, since a pair of slave ports and master ports need only be provided in the lower level device 101, for example, a pair of slave port circuits and master port circuits may be provided by using a switch circuit or the like. When one lower apparatus 101 is provided for one upper apparatus 102 and both apparatuses are connected in a one-to-one relationship, unused ports are eliminated and the use efficiency of apparatus resources can be improved. Therefore, in the communication system according to the embodiment of the present invention, system redundancy can be realized with a simple configuration.

  Further, the lower apparatus 101 can autonomously perform the redundancy switching process without the upper apparatus 102 controlling the lower apparatus 101. In addition, with the configuration in which whether or not a communication connection with the higher-level device 102 or another lower-level device 101 can be established is used as a determination criterion for redundant switching execution, existing processing can be performed without newly setting a determination criterion for redundant switching execution. It is possible to make a decision to execute redundancy switching.

  In the communication system according to the embodiment of the present invention, the lowest level device is connected to the master port of the higher level device 102 and its own master port, and the master port of the other lower level device 101 and its own slave port. Is the lower apparatus 101 connected. When the communication connection with the other lower-level device 101 is disconnected, this lowest-level device performs the switching process of the master port and the slave port, and establishes the communication connection with the higher-level device 102 via the slave port after switching. Processing and processing for establishing a communication connection with the other lower-level device 101 via the master port after switching are performed.

  With such a configuration, in a communication system in which the upper level device 102 and the plurality of lower level devices 101 are connected in a ring, when the communication connection between the lowest level device and another lower level device is disconnected, the lowest level is performed in an appropriate procedure. Device communication can be restored.

  In the communication system according to the embodiment of the present invention, the other lower device 101 is connected to the lower device 101 other than the lowest device or the higher device 102 among its two ports. When the communication connection with the connection destination device via the port is disconnected, the upper port is set as the master port, and the lower port connected to the lowest device is set as the slave port. Then, the other lower device 101 performs a process of establishing a communication connection with the lowest device via the lower port and a process of establishing a communication connection with the connection destination device via the upper port.

  With such a configuration, in a communication system in which the upper level device 102 and the plurality of lower level devices 101 are connected in a ring, when the communication connection between the lowest level device and another lower level device is disconnected, the lowest level is performed in an appropriate procedure. Communication of lower level devices other than the device can also be restored.

  The above embodiment should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

11 CDR unit 12 PLL unit 21 Retiming unit 22 Timing signal generating unit 23 Phase comparator 24 Loop filter 25 VCXO
31 Communication control unit 32 Port switching control unit 33 ROM
51 Synchronization processing unit 52 PLD
61 Control Unit 71 Wireless Transmission Unit 72 Wireless Reception Unit 81 Signal Processing Unit 82 Digital / Analog Converter 83 Modulator 84 Driver Amplifier 85 Power Amplifier 86 Transmission / Reception Switch 87 Oscillator 89, 90 Reception Amplifier 91 Mixer 92 BPF
93 Analog / digital converter 94 Oscillator 101, 101A, 101B, 101C Subordinate device (remote radio head)
102 Host device (main unit)
201 Communication system (radio base station apparatus)

Claims (10)

A lower-level device for communicating with a higher-level device,
A first port and a second port through which communication signals to and from other devices are input and output;
A port switching control unit capable of setting one of the first port and the second port as a master port and setting the other as a slave port;
A communication control unit for performing a process of establishing a communication connection with another device via the first port and via the second port;
The port switching control unit performs a switching process of the master port and the slave port when a communication connection with the higher-level device or other lower-level device via the slave port cannot be established,
When the switching process by the port switching control unit is performed, the communication control unit performs a process of establishing a communication connection with the higher-level device or the other lower-level device via the slave port after switching. . The subordinate device further includes:
Equipped with PLD (Programmable Logic Device)
The port switching control unit changes the circuit configuration of the PLD so that a port associated with a slave circuit used when transmitting / receiving a communication signal via the slave port is the first port and the second port. The subordinate apparatus according to claim 1, wherein the master port and the slave port are switched by switching between them. The port switching control unit, when the communication connection with another device cannot be established via one of the first port and the second port set as a slave port, Set the port as the master port,
The subordinate apparatus according to claim 1, wherein the communication control unit performs a process of establishing a communication connection with the other apparatus via the one port set as a master port.   3. The lower level device according to claim 2, wherein the slave circuit is a circuit for generating a reference timing signal based on data received from a master port of the higher level device or a master port of another lower level device. A lower-level device for communicating with a higher-level device,
A first port and a second port through which communication signals to and from other devices are input and output;
A port switching control unit capable of setting the first port and the second port as slave ports;
The communication control part for performing the process which establishes a communication connection with the said high-order apparatus or the low-order apparatus of Claim 1 via at least any one port of the said 1st port and the said 2nd port , Subordinate device. A host device;
A communication system comprising a plurality of subordinate devices,
The upper device and the plurality of lower devices are connected in a ring shape,
The host device includes two ports through which communication signals to and from other devices are input / output, and establishes a communication connection with the lower device via the slave port of the lower device via the two ports of the host device. Set to the master port used when
The lower-level device includes two ports through which communication signals to and from other devices are input and output, and one of the two ports is connected to the other lower-level device via a slave port of the other lower-level device. When establishing a communication connection with the higher-level device or the other lower-level device via the master port of the higher-level device or the other lower-level device and setting the other as the master port used when establishing a communication connection with Set to the slave port used for
The lower-level device is a communication system in which the master port and the slave port can be switched.   The lower-level device, which is the lower-level device to which the master port of the higher-level device and its own master port are connected, and the master port of the other lower-level device and its own slave port are connected, is the other lower-level device. When the communication connection with the master port and the slave port is disconnected, a process for establishing a communication connection with the host device via the slave port after the switching, and the master after the switching The communication system according to claim 6, wherein processing for establishing a communication connection with the other lower-level device via a port is performed.   The other lower device has a communication connection with a connection destination device via the upper port connected to the lower device other than the lowest device or the higher device among the two ports of its own. When disconnected, the upper port is set as a master port, the lower port connected to the lowest device is set as a slave port, and the communication connection with the lowest device via the lower port is established. The communication system according to claim 7, wherein processing for establishing and processing for establishing a communication connection with the connection destination device via the higher-order port are performed. A host device;
A communication system comprising a plurality of subordinate devices,
The upper device and the plurality of lower devices are connected in a ring shape,
The host device includes two ports through which communication signals to and from other devices are input / output, and establishes a communication connection with the lower device via the slave port of the lower device via the two ports of the host device. Set to the master port used when
The lower-level device includes two ports through which communication signals to and from other devices are input and output, and one of the two ports is connected to the other lower-level device via a slave port of the other lower-level device. When establishing a communication connection with the higher-level device or the other lower-level device via the master port of the higher-level device or the other lower-level device and setting the other as the master port used when establishing a communication connection with Can be set to the slave port used for, it is possible to perform the switching process of the master port and the slave port,
The subordinate device can further set its two ports as slave ports.
Communications system. A communication control method in a communication system comprising an upper device and a plurality of lower devices,
The upper device and the plurality of lower devices are connected in a ring shape,
The host device uses its own two ports through which communication signals with other devices are input / output as master ports used when establishing communication connection with the lower device via the slave port of the lower device. Steps to set,
The subordinate device establishes a communication connection with the other subordinate device via one of its two ports through which communication signals to / from other devices are input / output via the slave port of the other subordinate device. Set as a master port to be used at the same time, and set the other as a slave port to be used when establishing a communication connection with the higher-level device or the other lower-level device via the master port of the higher-level device or another lower-level device Steps,
A communication control method, comprising: a step of switching the master port and the slave port by the lower-level device.

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