JP6341869B2 - Communication apparatus and communication system - Google Patents

Description

  The present invention relates to a communication device and a communication system that transmit and receive continuous signals via a packet network.

  With the spread of Ethernet (registered trademark) in recent years, various services have been developed for homes and businesses using Ethernet as an infrastructure in optical access networks. On the other hand, in wireless networks, traffic has been increasing year by year due to the explosive spread of smartphones, and it is desirable to increase the capacity and reduce the cost of wireless access networks that accommodate a large number of base stations in business offices. ing. In addition, not only a dedicated line but also a packet network such as Ethernet is adopted for the radio access network. Initially, the packet communication function and the baseband processing function were incorporated in the base station, and the carrier device installed in the carrier station and the base station were connected with IP packets having high affinity with Ethernet. In view of the effect of downsizing the base station and the like, a form in which a base station and a provider apparatus with reduced packet communication function and baseband processing function are connected by a wireless baseband signal is also being studied.

  Radio baseband signal that is a continuous signal synchronized between the network devices of the radio access network when applying a form in which the base station and the provider apparatus with reduced packet communication function and baseband processing function are connected by radio baseband signals Therefore, the network device must have a synchronization function. Further, in order to transmit and receive wireless baseband signals at a suitable timing to a plurality of base stations with different distances from the provider device, it is required to specify the transmission delay amount with high accuracy. For this reason, the network device also needs a function that makes the delay of the radio baseband signal appear to be fixed.

  As such a technique, Patent Document 1 discloses a technique for controlling a transmission delay of a broadcast signal. In the technique described in Patent Document 1, the time of a performance station and a plurality of broadcasting stations are synchronized with a GPS (Global Positioning System) reference time, and each broadcasting station measures a transmission delay from the performance station to its own device. Then, a value obtained by subtracting each transmission delay from the time stamp and the maximum delay time given to the packet at the performance hall is determined as the adjustment delay time, and the broadcast signal is delayed by the determined adjustment delay time.

Japanese Patent No. 4283655

  However, when the technique described in Patent Document 1 is applied to the above-described device that transmits and receives the wireless baseband signal, the following data loss and gaps occur when fluctuations occur in the time synchronization error. There is.

  In the transmission device corresponding to the above-mentioned performance place, the interval between two packets transmitted continuously is 10 milliseconds, and the error of the transmission device is delayed or advanced by 1 nanosecond with respect to the reference time in 10 milliseconds. As a result, the time stamp of two packets transmitted in succession and the adjustment delay time based on the time stamp will vary by 1 nanosecond. At this time, assuming that there is no change from the reference time in the time of the receiving device corresponding to the above broadcasting station, if there is a change on the delay side of 1 nanosecond in the transmitting device, the data of two packets are received in the receiving device. A gap of 1 nanosecond is generated in the radio baseband signal reproduced originally. On the other hand, when the fluctuation on the leading side occurs, the radio baseband signal reproduced by the receiving device is overlapped by 1 nanosecond. Although the transmission rate of the radio baseband signal varies, the transmission rate of the CPRI (Common Public Radio Interface) signal defined in “CPRI Specification V6.0 (2013-08-30)” which is a non-patent document Will be described. The transmission rate defined in this document is defined as 1 ×, 2 ×, 4 ×, and 5 × based on 614.4 Mbps. In the case of a doubled 1228.8 Mbps CPRI signal, since 1 bit is about 0.8 nanosecond, data loss occurs if a 1 nanosecond gap or overlap occurs. In the CPRI signal with missing data, the code break which is the 8B10B code is shifted, so that the received opposite device may detect the code violation and cut the CPRI link.

  Even if the transmission device and the reception device are devised to minimize the fluctuation of the synchronization time as much as possible and the time fluctuation width in the two packet transmission intervals can be reduced to 1/2 nanosecond or 1/4 nanosecond, the transmission rate is 1228. The same problem occurs when a transmission rate of 2 times or more of .8 Mbps, that is, a transmission rate of 4 times or more of the reference transmission rate is used. In a trend of widening the wireless bandwidth and improving the wireless communication speed, the wireless baseband signal cannot be transferred over the packet network only by improving the time synchronization accuracy according to the technique described in Patent Document 1.

  The present invention has been made in view of the above, and an object of the present invention is to provide a communication apparatus capable of preventing data from being lost when a continuous signal is transmitted / received via a packet network.

In order to solve the above-described problems and achieve the object, the present invention provides a packet receiving unit that receives a packet in which a divided continuous signal is stored, and a continuous packet that is stored in a packet that is received by the packet receiving unit. A signal holding unit that receives and holds a reception continuous signal that is a signal, and a reception continuous signal that is subsequent to the reception continuous signal that is stored in the first packet that is the packet that the packet reception unit previously received is stored When the packet receiving unit receives a packet different from the second packet that is a packet, the reception holding signal is sent to the signal holding unit at a timing determined based on a time stamp inserted in the header of the packet received this time directs the output of, if the second packet is the packet receiving unit and received, transmission duration of the divided continuous signal A transmission timing control unit for instructing the output of said received continuous signal by the signal holding unit at a timing based on a continuous signal transmitting unit that transmits the continuous signal outputted from the signal holding unit to the continuous signal transmission network, It is characterized by providing.

  According to the present invention, it is possible to prevent data from being lost when a continuous signal is transmitted / received via a packet network.

The figure which shows the structural example of the communication system concerning Embodiment 1. FIG. The figure which shows the outline | summary of the operation | movement which the communication apparatuses concerning Embodiment 1 convert a continuous signal into a packet, and transmit / receive via a packet network. The figure which shows the structural example of the packet transmitted / received between the communication apparatuses concerning Embodiment 1. FIG. FIG. 3 is a flowchart illustrating an operation example of a transmission timing control unit according to the first embodiment; The figure which shows the structural example of the communication system concerning Embodiment 2. FIG.

  Hereinafter, a communication device and a communication system according to embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram of a configuration example of a communication system according to the first embodiment of the present invention. The communication system according to the present embodiment includes communication devices 1A and 1B that convert continuous signals into packets and transmit / receive them via a packet network. The configurations of the communication device 1A and the communication device 1B are the same. Therefore, the process of transmitting a packet from the communication apparatus 1A to the communication apparatus 1B is the same as the process of transmitting a packet from the communication apparatus 1B to the communication apparatus 1A. The communication system shown in FIG. 1 is assumed to be applied to a radio access network in which a base station is accommodated in a provider station. That is, the communication system relays a continuous signal transmitted / received between the provider apparatus installed in the provider station and the base station.

  The communication devices 1A and 1B each receive a continuous signal from a network for continuous signal transmission and convert the packet into a packet. The packet converter 10 transmits the packet to the packet network; receives the packet from the packet network and converts the packet into a continuous signal; A continuous signal conversion unit 20 that transmits to a network for continuous signal transmission, a time synchronization unit 30 that adjusts a local time and synchronizes with a reference time, and a fixed delay setting unit 40 are provided.

  In the present embodiment, communication device 1A converts a continuous signal into a packet and transmits the packet to communication device 1B via a packet network. Communication device 1B receives the packet from communication device 1A via the packet network and receives a continuous signal. The operation to convert to will be described. Therefore, in FIG. 1, the description of the continuous signal conversion unit 20 that is a component related to the packet reception processing of the communication device 1A is simplified, and the packet conversion unit 10 that is a component related to the packet transmission processing of the communication device 1B is simplified. Is simplified. In communication devices 1A and 1B, packet conversion unit 10 and time synchronization unit 30 constitute a transmission device that transmits packets, and continuous signal conversion unit 20, time synchronization unit 30 and fixed delay setting unit 40 receive packets. Configure the device.

  The packet converting unit 10 includes a continuous signal receiving unit 11 that receives a continuous signal, a packetization processing unit 12 that packetizes the continuous signal received by the continuous signal receiving unit 11, and a packet generated by the packetization processing unit 12. A packet transmission unit 13 that transmits to the packet network and a time stamp generation unit 14 that generates a time stamp added to the packet generated by the packetization processing unit 12 are provided.

  The continuous signal converter 20 includes a packet receiver 21 that receives a packet from the packet network, a fixed delay processor 22 that receives the data stored in the packet received by the packet receiver 21 and outputs the data after giving a delay. A continuous signal transmission unit 23 that transmits the signal output from the fixed delay processing unit 22 as a continuous signal; a time stamp extraction unit 24 that extracts a time stamp from the header of the packet received by the packet reception unit 21; A transmission timing control unit 25 that determines a delay time, which is a time from when the fixed delay processing unit 22 receives data to when it is output, and instructs the fixed delay processing unit 22 to output data according to the determined delay time; And a clock synchronization unit 26 that provides a clock to the transmission unit 23 and the transmission timing control unit 25. .

  Here, the local time managed by the communication devices 1A and 1B constituting the communication system is assumed to be synchronized with the reference time managed by the external time master. That is, it is assumed that the times of the communication devices 1A and 1B are synchronized. Further, it is assumed that the clock output from the clock synchronization unit 26 is synchronized with a clock generated by an external clock master. Although the local time is assumed to be managed by the time synchronization unit 30, it may be managed by other than the time synchronization unit 30. For example, the time synchronization unit 30 is connected to a GPS receiver and performs time synchronization using radio waves received from GPS satellites. The clock synchronization unit 26 generates a clock to be provided to the continuous signal transmission unit 23 and the transmission timing control unit 25 using the 10 MHz clock output from the GPS receiver as a reference clock. Alternatively, the time synchronization unit 30 may realize time synchronization in accordance with the IEEE 1588 standard, which is a packet network synchronization technique. The clock synchronization unit 26 is an ITU-T G. Clock synchronization may be realized in accordance with the 826x series recommended Synchronous Ethernet (registered trademark) standard.

  Subsequently, the communication device 1A converts a continuous signal into a packet and transmits the packet to the communication device 1B via the packet network, and the communication device 1B receives the packet from the communication device 1A via the packet network and converts it into a continuous signal. explain. An outline of this operation is shown in FIG.

  As shown in FIG. 2, in the communication apparatus 1A that transmits packets to the packet network, the continuous signal receiving unit 11 receives the continuous signal, and the packet transmitting unit 13 transmits the packetized continuous signal to the packet network. . The header of the packetized continuous signal includes time stamps (“0”, “2”, “4”, “6”, “6”) indicating the time at which the continuous signal receiving unit 11 received the continuous signal stored in the packet. 8 ”,“ A ”,...). Note that a signal indicated by a black rectangle is the head signal of the continuous signal.

  In the communication apparatus 1B that receives a packet from the packet network, the packet receiving unit 21 receives the packet, and transfers the data part (hereinafter referred to as a data block) after removing the header and the like to the fixed delay processing unit 22. The fixed delay processing unit 22 as a signal holding unit holds the received data block, and each time the transmission permission pulse is output from the transmission timing control unit 25, the held data block is sequentially transmitted continuously. To the unit 23. When the continuous signal transmitting unit 23 receives the data block from the fixed delay processing unit 22, the continuous signal transmitting unit 23 transmits the data block to the continuous signal transmission network. The transmission timing control unit 25 is configured so that the signal transmitted from the continuous signal transmission unit 23 becomes a continuous signal, that is, the signals transmitted from the continuous signal transmission unit 23 partially overlap or a gap is generated between the signals. The transmission timing of the transmission permission pulse is determined so as not to occur. The output timing of the transmission permission pulse is determined based on the time stamp included in the header of each received packet or the size of the data block stored in the received packet. Note that the size of packets transmitted and received between the communication apparatuses 1A and 1B is fixed. Therefore, the size of the data block is also fixed. When determining the output timing of the transmission permission pulse based on the time stamp, the transmission timing control unit 25 outputs the transmission permission pulse at a time obtained by adding a fixed delay time to the time indicated by the time stamp. Further, when determining the output timing of the transmission permission pulse based on the size of the data block, the transmission timing control unit 25 outputs the transmission permission pulse at a constant period derived from the data block, as will be described later in detail. The fixed delay time is set by the fixed delay setting unit 40. The fixed delay time is interrupted when a continuous signal received in a state of being divided into a plurality of packets is transmitted from the continuous signal transmission unit 23 due to the influence of transmission delay in the packet network, fluctuation of delay amount, and the like. This is the time set for transmitting the signal after accumulating the continuous signal in a divided state to some extent so as not to occur. The fixed delay time is longer than the transmission delay time in the packet network. In the example shown in FIG. 2, the fixed delay time is “4”.

  Details of the operation shown in FIG. 2 will be described below. First, an operation in which the communication apparatus 1A converts a continuous signal such as a 1228.8 Mbps CPRI signal into a packet and transmits the packet to the packet network will be described. The continuous signal may be a CPRI signal other than 1228.8 Mbps.

  In the communication apparatus 1A, when the continuous signal receiving unit 11 receives the continuous signal, the continuous signal receiving unit 11 performs an operation such as physical layer processing and outputs the continuous signal to the packetization processing unit 12 when the validity of the received continuous signal is confirmed. Then, the continuous signal detection is notified to the Timestamp generation unit 14. When the continuous signal receiving unit 11 receives data of an amount of data that can be stored in one packet, the continuous signal receiving unit 11 further confirms the validity of the continuous signal, and performs continuous signal detection to the Timestamp generating unit 14 again for the next packet. Notice.

  Based on the current time notified from the time synchronization unit 30, the Timestamp generation unit 14 notifies the packetization processing unit 12 of information on the time when the notification of continuous signal detection arrives from the continuous signal reception unit 11 as a time stamp. .

  When receiving the continuous signal from the continuous signal receiving unit 11, the packetization processing unit 12 temporarily stores it. Further, when the packetization processing unit 12 detects that the data amount of the continuously stored continuous signal has reached the data amount stored in one packet, the data that is the temporarily stored continuous signal, that is, data A MAC (Media Access Control) header, an encapsulation header, and an FCS (Frame Check Sequence) are added to the block to generate a packet having the configuration shown in FIG. At this time, the time stamp received from the Timestamp generation unit 14 is embedded in the encapsulation header. When packet generation is completed, the packetization processing unit 12 transfers the generated packet to the packet transmission unit 13. The transfer rate at this time is 10 Gbps, which is faster than the continuous signal received by the continuous signal receiving unit 11.

  Here, the configuration of the packet generated by the packetization processing unit 12 will be described. As illustrated in FIG. 3, the packet is divided into a MAC header including “MAC DA (Destination Address)”, “MAC SA (Source Address)”, and “Type”, and an encapsulation header (Capsulation Header). The data block is a continuous signal and the FCS. “MAC DA” of the MAC header indicates a destination, and the MAC address of the communication device 1B is stored in this field. “MAC SA” indicates a transmission source, and the MAC address of the communication device 1A is stored in this field. “Type” indicates an upper layer protocol. The encapsulation header includes “Identifier” that is an identifier for identifying whether the reception side is a continuous signal addressed to the own apparatus, “Sequence Number” that is a sequence number for confirming the continuity of the packet, and 48 bits. “Timesamp”, which is composed of “seconds” indicated by “32” and “nanoseconds” indicated by 32 bits, and stores the time stamp received from the Timestamp generation unit 14, and “Check Code” indicating the validity of the time stamp and the header. It is configured. The size of the packet generated by the packetization processing unit 12 is fixed.

  When the packet transmission unit 13 receives a packet from the packetization processing unit 12, the packet transmission unit 13 performs operations such as physical layer processing on the received packet, and transmits the packet to the packet network. Here, the clock used for the packet transmission process may be asynchronous with the clock of the receiving communication apparatus.

  Next, an operation in which the communication device 1B receives the packet transmitted by the communication device 1A and converts it into a continuous signal will be described.

  In the communication device 1B, when receiving a packet in which a continuous signal is stored from the packet network, the packet receiving unit 21 confirms the destination and normality of the packet after performing operations such as physical layer processing. When the received packet is addressed to the own device and no abnormality such as an FCS error is detected, the MAC header, the encapsulation header, and the FCS attached by the communication device 1A on the transmitting side are removed, and then the packetized continuous signal A certain data block is output to the fixed delay processing unit 22 and the encapsulation header is output to the Timestamp extraction unit 24. The transfer rate from the packet receiving unit 21 to the fixed delay processing unit 22 is 10 Gbps, which is faster than the continuous signal received by the communication device 1A. When the received packet is addressed to another device, or when an abnormality of the packet is detected, the received packet is discarded.

  When receiving the encapsulated header from the packet receiving unit 21, the Timestamp extracting unit 24 checks the normality of the encapsulated header, and if normal, extracts the sequence number and the time stamp from the encapsulated header. The data is output to the transmission timing control unit 25. At this time, notification that the encapsulation header is normal may be performed together. On the other hand, when the encapsulation header is abnormal, the transmission timing control unit 25 is notified that the encapsulation header is abnormal.

  The transmission timing control unit 25, in addition to the above-described information output from the Timestamp extraction unit 24, specifically, a sequence number and time stamp, and a packet abnormality detection notification, is also output from the fixed delay setting unit 40. The delay time information, the current time information output from the time synchronization unit 30 and the clock output from the clock synchronization unit 26 are received, and the fixed delay processing unit 22 is controlled based on the received information. Details of the fixed delay time will be described separately. The operation of the transmission timing control unit 25 is as shown in FIG. When there is any input from the Timestamp extraction unit 24, the transmission timing control unit 25 performs the operation shown in FIG. Specifically, it is executed when a sequence number and a time stamp extracted from the encapsulation header are received or when an abnormality detection of the encapsulation header is notified.

  When there is an input from the Timestamp extraction unit 24, the transmission timing control unit 25 examines the encapsulation header of the received packet and determines whether or not the encapsulation header is normal (steps S1 and S2). When the input from the Timestamp extraction unit 24 is an encapsulation header abnormality detection notification, it is determined that the encapsulation header is abnormal. When the input from the Timestamp extraction unit 24 is a sequence number and a time stamp, it is determined that the encapsulation header is normal if the time stamp is within the normal range, and abnormal if the time stamp is not within the normal range. Specifically, when the time stamp indicates a time before the current time and the time obtained by adding the fixed delay time notified from the fixed delay setting unit 40 to the time stamp is later than the current time, it is determined as normal. Otherwise, it is determined as abnormal.

  When the encapsulation header is normal (step S2: Yes), the transmission timing control unit 25 confirms whether or not the data is continuously received, that is, whether or not the data block subsequent to the previously received data block has been received. (Step S3). In this step S3, the sequence number in the encapsulation header is confirmed, and if the sequence number of the current received packet is different from the value obtained by adding 1 to the sequence number of the previously received packet, it is determined that the data is not continuously received. (Step S3: No). Note that even in the case of a sequence number indicating that it has been received for the first time after the apparatus is activated, it is determined that the data is not continuously received. As an example where the sequence number becomes discontinuous, if the packet that should arrive first is discarded in the packet network or if the arrival order is reversed, FCS error due to transmission path error or check code error of encapsulation header Or when arriving after exceeding the above-mentioned fixed delay time. On the other hand, if the sequence number of the current received packet is equal to the value obtained by adding 1 to the sequence number of the previously received packet, it is determined that the data is continuously received (step S3: Yes).

  When it is determined that the received data is discontinuous (step S3: No), the transmission timing control unit 25 sets a fixed delay to the time stamp received from the Timestamp extraction unit 24 in consideration of the case where the granularity of the counter for counting the current time is coarse. It waits until the relationship between the time indicated by the result of adding the fixed delay time notified from the setting unit 40 (hereinafter referred to as “calculated time”) and the current time becomes “current time ≧ calculated time” (step S4). That is, it waits until the current time becomes the same as the calculated time or until the current time exceeds the calculated time. When “current time ≧ calculated time” is satisfied, a counter that counts a fixed period when a transmission permission pulse is output at a fixed period is reset (step S6), and the continuous signal stored in the current received packet is reset. Is output to the fixed delay processing unit 22 (step S7).

Here, it is assumed that the clock input from the clock synchronization unit 26 to the transmission timing control unit 25 is synchronized with the clock when the continuous signal transmission unit 23 transmits a continuous signal. Further, as already described, since the size of the data block is fixed, the number of clocks required from the start of transmission of the data block to the end thereof is also fixed. This number of clocks can be calculated in advance. Accordingly, the transmission timing control section 25, to allow them to transmit and output the transmission permission pulse in step S7, the transmission time required is the time transmission is final I until authorization data block transmission, clock synchronization It can be measured by counting the clocks input from the unit 26. When the frequency of the operation clock of the continuous signal transmission unit 23 that transmits the data block is the same as the frequency of the operation clock of the counter used by the transmission timing control unit 25 to measure the required transmission time, and the data block is transmitted with 1280 bits The counter used for measuring the required transmission time is set so as to count 0 to 1279.

  When it is determined that the received data is continuous (step S3: Yes), the transmission timing control unit 25 waits until the above-described counter expires (step S5). That is, it waits for the completion of transmission of the data block whose transmission is permitted by the transmission permission pulse output last time. When the counter expires, the counter is reset (step S6), and a transmission permission pulse is output to the fixed delay processing unit 22 (step S7).

  If it is determined in step S2 that the encapsulation header is abnormal (step S2: No), the fixed delay processing unit 22 discards the continuous signal that is the data block to which the encapsulation header determined to be abnormal is added. An instruction is given (step S8).

  The fixed delay processing unit 22 includes a buffer that can hold the data block received from the packet receiving unit 21 for a fixed delay time set for the transmission timing control unit 25 by the fixed delay setting unit 40. doing. When the fixed delay processing unit 22 receives the data block from the packet receiving unit 21, the fixed delay processing unit 22 holds the data block, and when receiving a transmission permission pulse from the transmission timing control unit 25, the fixed delay processing unit 22 converts the held data block into the continuous signal transmitting unit 23. Output to. When receiving a data block discard instruction from the transmission timing control unit 25, the stored data block is discarded.

  A continuous signal output clock is input from the clock synchronization unit 26 to the continuous signal transmission unit 23, and the continuous signal transmission unit 23 operates in synchronization with the clock input from the clock synchronization unit 26. When receiving the data block from the fixed delay processing unit 22, the continuous signal transmission unit 23 performs an operation such as physical layer processing and transmits the data block. In addition, the continuous signal transmission unit 23 transmits invalid data when no data block is received and there is no data to be transmitted. Invalid data is data that is not determined to be a valid continuous signal by the opposing device. For example, when the continuous signal is an 8B10B code, a signal indicating idle or error is transmitted. When transmitting a continuous signal with light, the optical transmission power is reduced to such an extent that it cannot be received by the opposite device.

  Here, the signal processing delay time of the continuous signal transmitter 23 is fixed. The signal processing delay time is a time required from when the continuous signal transmission unit 23 receives data from the fixed delay processing unit 22 to when data transmission is actually started. In the case of the example illustrated in FIG. 2, a transmission permission pulse is output from the transmission timing control unit 25, and the fixed delay processing unit 22 that receives this outputs the data block to the continuous signal transmission unit 23 and then starts data transmission. Is the signal processing delay time of the continuous signal transmitter 23. Signals in signal processing executed by the continuous signal transmitter 23 after the transmission permission pulse is generated after the transmission permission pulse output from the transmission timing control unit 25 is delayed by a fixed delay time from the reception time of the continuous signal Since the processing delay time is fixed, the continuous signal is delayed by the time obtained by adding the two fixed times after being received by the continuous signal receiving unit 11 of the communication apparatus 1A, that is, the fixed delay time and the signal processing. The signal is output from the continuous signal transmission unit 23 of the communication device 1B with a delay by the time added by the delay time.

  The operation when the continuous signal is packetized and transmitted from the communication device 1A to the communication device 1B has been described, but the operation when the continuous signal is packetized and transmitted from the communication device 1B to the communication device 1A is the same. is there.

  As described above, the continuous signal converter 20 uses the current time only once when transmitting a continuous signal received in a plurality of packets via a packet network, that is, when receiving a continuous signal for the first time. 4 is only used in the process of step S4 of FIG. 4 executed at the same time, the fluctuation of the time synchronization between the two devices, which is the cause of data loss and gaps, does not affect the continuous signal transmission.

  In the above description, an encapsulated header is added to a continuous signal and transferred using an Ethernet frame. However, it can also be transferred using an IP packet, TCP (Transmission Control Protocol), UDP (User Datagram Protocol), or the like. Protocols that can be transferred over the packet network can be selected.

  In the above description, the identifier of the encapsulation header is used to distinguish the packet addressed to the own device. However, the packet may be distinguished by the destination MAC address. Further, when transferring by IP, it may be identified by the destination IP address. Also, the sequence number is omitted, and the difference between the time stamp of the encapsulation header of the previously received packet and the time stamp of the currently received packet is the time corresponding to the reception time of the number of bits of the packetized continuous signal. It may be determined whether it is continuous reception or not.

  As described above, in the communication system according to the present embodiment, the communication device on the side that transmits the continuous signal to the packet network divides the continuous signal and stores it in the packet, and sets the reception time of the continuous signal stored in the packet. When the communication apparatus 1B on the side receiving the packetized continuous signal receives the packet, it extracts the continuous signal stored in the packet and temporarily holds it. At the timing determined based on the time stamp inserted in the header and a fixed delay time set in advance, the process of transmitting the retained continuous signal to the network for continuous signal transmission is started, and the transmission process is started. After the start, the held continuous signal is transferred at the timing determined based on the size of the continuous signal stored in the packet. It was decided to send to the network for connection signal transmission. Thereby, it is possible to prevent data from being lost when a continuous signal is transmitted / received via a packet network. In addition, a continuous signal such as a wireless baseband signal can be transferred with a fixed delay using a packet network that is less expensive than a dedicated line.

Embodiment 2. FIG.
FIG. 5 is a diagram illustrating a configuration example of a communication system according to the second exemplary embodiment of the present invention. In the first embodiment, a communication system in which two communication apparatuses having the same configuration transmit and receive continuous signals via a packet network has been described. However, in the present embodiment, one communication apparatus that can transmit and receive a plurality of continuous signals. A communication system configured to transmit and receive continuous signals via the packet network will be described. In FIG. 5, the same components as those included in the communication devices 1A and 1B of the first embodiment shown in FIG. A description of components having the same reference numerals as those of the communication devices 1A and 1B is omitted.

  The communication system according to the present embodiment converts a plurality of continuous signals into packets and transmits them to a plurality of opposing devices, and also converts a communication device 5 that converts packets received from a plurality of opposing devices into a plurality of continuous signals; A single continuous signal is converted into a packet and transmitted to the opposite device, and the communication devices 1a, 1b and 1c convert the packet received from the opposite device into a continuous signal. Here, the communication devices 1a, 1b, and 1c are the same communication devices as the communication devices 1A and 1B described in the first embodiment. The local time of the communication device 5 and the local time of the communication devices 1a, 1b and 1c are synchronized with the reference time managed by the external time master, like the communication devices 1A and 1B of the first embodiment. And

  The communication device 5 receives continuous signals from a continuous signal transmission network and converts them into packets, and converts the packets received via the packet network into continuous signals for continuous signal transmission. Continuous signal conversion units 20a, 20b, and 20c that transmit to the network, a time synchronization unit 30 that adjusts the local time and synchronizes with the reference time, fixed delay setting units 40a, 40b, and 40c, and packet conversion units 10a, 10b And 10c receive the packets from each of them, multiplex them and output them to the packet network, and select the output destinations of the packets received from a plurality of opposing devices from among the continuous signal converters 20a, 20b and 20c Part 60. The internal configuration of the packet conversion units 10a, 10b, and 10c is the same as that of the packet conversion unit 10 of the communication devices 1A and 1B described in the first embodiment. The internal configuration of the continuous signal conversion units 20a, 20b, and 20c is the same as that of the continuous signal conversion unit 20 of the communication devices 1A and 1B.

  Subsequently, the operation of the communication system according to the present embodiment, specifically, the communication device 5 converts a plurality of continuous signals into packets and transmits them to the communication devices 1a, 1b, and 1c via the packet network. 1a, 1b and 1c receive packets and convert them into continuous signals, and communication devices 1a, 1b and 1c convert continuous signals into packets and send them to the communication device 5 via the packet network. The operation of receiving a packet and converting it into a plurality of continuous signals will be described.

  First, an operation in which the communication device 5 converts a continuous signal into a packet and transmits the packet and the communication devices 1a, 1b, and 1c convert the packet into a continuous signal will be described.

  In communication device 5, packet converters 10 a, 10 b, and 10 c receive different continuous signals transmitted in parallel, store the received continuous signals in packets, and output them to multiplexing unit 50. The process of packetizing the continuous signal is the same as the packet conversion unit 10 of the communication apparatuses 1A and 1B described in the first embodiment. However, the identifier assigned to the encapsulation header is set to a different value so that the receiving communication apparatus can distinguish whether or not to receive the continuous signal stored in the packet. Here, 0x1A, 0x1B, and 0x1C are set. Multiplexer 50 receives the packets from packet converters 10a, 10b, and 10c and multiplexes them and transmits them to the packet network. The packet network transfers the packet transmitted by the multiplexing unit 50 to a desired destination. Here, the data is transferred to the communication device 1a, 1b or 1c. In communication devices 1a, 1b, and 1c, when receiving a packet from the packet network, continuous signal conversion unit 20 extracts a continuous signal from the received packet and transmits the packet that receives a packet from communication device 5 via the packet network. . This process is the same as the process in which the continuous signal conversion unit 20 included in the communication devices 1A and 1B according to the first embodiment converts a packet into a continuous signal. Here, the continuous signal conversion unit 20 of the communication device 1a determines that the packet whose identifier of the encapsulation header is 0x1A is addressed to the own device, and converts the packet in which this identifier is set into a continuous signal. The continuous signal conversion unit 20 of the communication device 1b determines that the packet whose identifier of the encapsulation header is 0x1B is addressed to the own device, and converts the packet in which this identifier is set into a continuous signal. The continuous signal conversion unit 20 of the communication device 1c determines that a packet whose identifier of the encapsulation header is 0x1C is addressed to its own device, and converts the packet in which this identifier is set into a continuous signal. Thereby, a continuous signal can be transferred from each of the continuous signal conversion units 20 of the communication devices 1a, 1b, and 1c with a fixed delay. The fixed delay time values set in the corresponding continuous signal conversion units 20 by the fixed delay setting units 40 of the communication devices 1a, 1b, and 1c may be different values.

  Next, an operation in which the communication devices 1a, 1b, and 1c convert a continuous signal into a packet and transmit the packet and the communication device 5 converts the packet into a continuous signal will be described.

  In the communication devices 1a, 1b, and 1c, the packet conversion unit 10 stores the received continuous signal in a packet and outputs it. The process of packetizing the continuous signal is the same as the packet conversion unit 10 of the communication apparatuses 1A and 1B described in the first embodiment. Here, the identifier that the packet converter 10 of the communication device 1a gives to the encapsulation header is 0x1D, the identifier that the packet converter 10 of the communication device 1b gives to the encapsulation header is 0x1E, and the packet converter 10 of the communication device 1c has The identifier given to the encapsulation header is 0x1F. The packet network transfers the packets transmitted by the communication devices 1a, 1b, and 1c to a desired destination. Here, the data is transferred to the communication device 5. In the communication device 5, the selection unit 60 adds a packet that receives packets from the communication devices 1 a, 1 b, and 1 c via the packet network to the destination MAC address, the destination IP address, and the encapsulation header of the received packet. Based on one of the identifiers or information obtained by combining two or more of them, the continuous signal conversion unit to which the received packet is destined is selected and transferred in the form of a packet. That is, the selection unit 6 transfers the received packet to any one of the continuous signal conversion units 20a, 20b, and 20c corresponding to the destination. Specifically, the selection unit 60 transfers the packet with the identifier assigned to the encapsulation header of 0x1D to the continuous signal conversion unit 20a, and converts the packet with the identifier assigned to the encapsulation header of 0x1E to continuous signal conversion. The packet with the identifier assigned to the encapsulation header of 0x1D is transferred to the continuous signal conversion unit 20c. When the continuous signal conversion units 20a, 20b, and 20c receive a packet from the selection unit 60, the continuous signal conversion unit 20a, 20b, and 20c extracts and transmits a continuous signal from the received packet. This process is the same as the process in which the continuous signal conversion unit 20 included in the communication devices 1A and 1B according to the first embodiment converts a packet into a continuous signal. Thereby, a continuous signal can be transferred from each of the continuous signal converters 20a, 20b and 20c with a fixed delay. In the communication apparatus 5, the values set by the fixed delay setting units 40a, 40b, and 40c in the continuous signal conversion units 20a, 20b, and 20c may be different values.

  In communication apparatus 5 of the present embodiment, it is not always necessary to match the output rate of multiplexing unit 50 with the total value of the output rates of packet converting units 10a, 10b, and 10c. If the output rate of the multiplexing unit 50 is larger than the total value, there is no problem. If each of the packet conversion units 10a, 10b, and 10c stores and transfers a continuous signal of 1228.8 Mbps in a packet, and the packet network is 10 Gigabit Ethernet, each of the packet conversion units 10a, 10b, and 10c The total output rate is less than 10 Gbps. In this case, the communication device 5 uses a packet network to transmit a plurality of multiplexed continuous signals and receive a packet after reducing the number of ports by multiplexing and transmitting a plurality of continuous signals. The communication device thus made can perform fixed delay transfer without causing data loss in the continuous signal reproduced from the continuous signal without causing data loss.

  In the communication system of the present embodiment, the communication devices 1a, 1b, and 1c on the side that receives the multiplexed packet distinguish whether the packet received from the communication device 5 is a packet addressed to itself. Although the identifier of the encapsulation header is used, it may be distinguished by the destination MAC address. Further, when transferring by IP, it may be identified by the destination IP address. Also, the sequence number is omitted, and the difference between the time stamp of the encapsulated header of the packet just received and the time stamp received this time is the time corresponding to the reception time of the number of bits of the continuous signal packetized. It may be determined whether it is continuous reception or not.

  As described above, the communication system according to the present embodiment divides a plurality of continuous signals and stores them in a packet, inserts a time stamp indicating the reception time of the continuous signal stored in the packet into the header, At the timing determined based on the time stamp inserted in the header of the packet and the preset fixed delay amount, receiving the packetized continuous signal addressed to the device itself and the communication device that multiplexes and transmits , Start the process of transmitting the continuous signal extracted from the packet to the network for continuous signal transmission, and after starting the transmission process, at the timing determined based on the size of the continuous signal stored in the packet A plurality of communication devices that transmit to a continuous signal transmission network are provided. According to the communication system according to the present embodiment, a plurality of continuous signals can be transmitted / received in parallel via a packet network, and data can be prevented from being lost when being transmitted / received via a packet network. In addition, a continuous signal such as a wireless baseband signal can be transferred with a fixed delay using a packet network that is less expensive than a dedicated line.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

  1A, 1B, 1a, 1b, 1c, 5 Communication device 10, 10a, 10b, 10c Packet conversion unit, 11 Continuous signal reception unit, 12 Packetization processing unit, 13 Packet transmission unit, 14 Timestamp generation unit, 20 and 20a , 20b, 20c Continuous signal conversion unit, 21 Packet reception unit, 22 Fixed delay processing unit, 23 Continuous signal transmission unit, 24 Timestamp extraction unit, 25 Transmission timing control unit, 26 Clock synchronization unit, 30 Time synchronization unit, 40, 40a , 40b, 40c Fixed delay setting unit, 50 multiplexing unit, 60 selection unit.

Claims (8)

A packet receiver for receiving a packet in which the divided continuous signal is stored;
A signal holding unit that receives and holds a reception continuous signal that is a continuous signal stored in a packet received by the packet reception unit;
The packet reception unit the packet receiving unit different from the packet and the second packet is a packet received continuous signal following the reception continuous signal which has been stored in the first packet is a packet received last is stored Is received based on the time stamp inserted in the header of the packet received this time, the signal holding unit is instructed to output the reception continuous signal, and the second packet is sent to the packet receiving unit. and If is it receives, the transmission timing control unit for instructing the output of said received continuous signal by the signal holding unit at a timing based on the transmission time required for the divided continuous signal,
A continuous signal transmitting unit that transmits the continuous signal output from the signal holding unit to a network for continuous signal transmission;
A communication apparatus comprising: The transmission timing control unit determines whether or not the second packet has been received based on a sequence number inserted in a header of a packet received by the packet reception unit. The communication apparatus as described in. The transmission timing control unit
When the packet receiving unit receives a packet different from the second packet, the fixed value is set to a value longer than a transmission delay time in a packet network in which the packet in which the divided continuous signal is stored is transmitted When the calculated time, which is the time obtained by adding the delay time to the time indicated by the time stamp, is the same as the current time or the current time exceeds the calculated time, the signal holding unit is instructed to output the received continuous signal And
When the packet receiving unit receives the second packet, the elapsed time from instructing the signal holding unit to output the previous received continuous signal is the same as the required transmission time of the divided continuous signal. Instructing the signal holding unit to output the continuous reception signal at the timing
The communication apparatus according to claim 1 or 2, wherein A time synchronization unit that realizes time synchronization with a communication device that is a transmission source of the packet received by the packet reception unit;
With
The time stamp is a continuous signal stored in a packet received by the packet receiver from a continuous signal transmission network different from the continuous signal transmission network by a communication device that is a transmission source of the packet. Indicates the time of reception
The communication apparatus according to claim 1, 2, or 3. A communication system comprising: a first communication device that packetizes and transmits a continuous signal received from a continuous signal transmission network; and a second communication device that receives a packet transmitted by the first communication device,
The first communication device is:
A packet converter that divides the continuous signal and stores it in a packet, inserts a time stamp indicating the reception time of the continuous signal stored in the packet into the header of the packet, and transmits the packet to the packet network;
With
The second communication device is:
A packet receiver that receives the packet transmitted by the first communication device from the packet network;
A signal holding unit that receives and holds a reception continuous signal that is a continuous signal stored in a packet received by the packet reception unit;
The packet reception unit the packet receiving unit different from the packet and the second packet is a packet received continuous signal following the reception continuous signal which has been stored in the first packet is a packet received last is stored Is received based on the time stamp inserted in the header of the packet received this time, the signal holding unit is instructed to output the reception continuous signal, and the second packet is sent to the packet receiving unit. and If is it receives, the transmission timing control unit for instructing the output of said received continuous signal by the signal holding unit at a timing based on the transmission time required for the divided continuous signal,
A continuous signal transmitting unit that transmits the continuous signal output from the signal holding unit to another continuous signal transmission network different from the continuous signal transmission network;
A communication system comprising: A communication system comprising a first communication device that packetizes and transmits a plurality of continuous signals received from a continuous signal transmission network, and a plurality of second communication devices that receive packets transmitted by the first communication device. Because
The first communication device is:
Dividing any one of the plurality of continuous signals into a packet, inserting a time stamp indicating the reception time of the continuous signal stored in the packet into the header of the packet, and outputting the packet A packet converter,
A multiplexing unit that multiplexes a packet output from each of the plurality of packet conversion units and transmits the packet to a packet network;
With
Each of the plurality of second communication devices includes:
A packet receiver that receives the packet transmitted by the first communication device from the packet network;
A signal holding unit that receives and holds a reception continuous signal that is a continuous signal stored in a packet received by the packet reception unit;
The packet reception unit the packet receiving unit different from the packet and the second packet is a packet received continuous signal following the reception continuous signal which has been stored in the first packet is a packet received last is stored Is received based on the time stamp inserted in the header of the packet received this time, the signal holding unit is instructed to output the reception continuous signal, and the second packet is sent to the packet receiving unit. and If is it receives, the transmission timing control unit for instructing the output of said received continuous signal by the signal holding unit at a timing based on the transmission time required for the divided continuous signal,
A continuous signal transmitting unit that transmits the continuous signal output from the signal holding unit to another continuous signal transmission network different from the continuous signal transmission network;
A communication system comprising: The packet converter inserts a sequence number indicating the continuity of the packet into the packet header,
The transmission timing control unit determines whether or not the second packet has been received based on the sequence number inserted in a header of a packet received by the packet reception unit. The communication system according to 5 or 6. The transmission timing control unit
When the packet receiving unit receives a packet different from the second packet, the fixed value is set to a value longer than a transmission delay time in a packet network in which the packet in which the divided continuous signal is stored is transmitted When the calculated time, which is the time obtained by adding the delay time to the time indicated by the time stamp, is the same as the current time or the current time exceeds the calculated time, the signal holding unit is instructed to output the received continuous signal And
When the packet receiving unit receives the second packet, the elapsed time from instructing the signal holding unit to output the previous received continuous signal is the same as the required transmission time of the divided continuous signal. Instructing the signal holding unit to output the continuous reception signal at the timing
The communication system according to claim 5, 6 or 7.

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