JP2009141730A - System switching apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a service according to a request when highly-reliable and high-quality one-way communication is required. <P>SOLUTION: A system switching apparatus includes: a transmission quality determining means for determining transmission quality of a system on the basis of both a bit error rate or the number thereof for a part of transmission frames containing information for synchronization as a header of a frame structure and bit error presence detection information of sub-frames constituting the transmission frame; and a means for switching the system by the unit of a sub-frame or a transmission frame to a network of a system with high transmission quality among a plurality of systems on the basis of the result of the transmission quality determining means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is used in a one-way communication network in which a data transmission source and a working and one or more backup networks are always connected. In particular, the present invention relates to a technology for switching a system from an active network to another network according to the transmission quality of the system.

  As a high-speed digital communication system, SONET (Synchronous Optical Network) or SDH (Synchronous Data Hierarchy) standards are used (for example, see Non-Patent Document 1). In this SONET or SDH, as a switching method from the active network to the standby network, a multiple section switching method (ITU-T recommendation G.783) between two devices, and an insertion / demultiplexing device (ADM: Add) The ring switching method (G.841) performed by / Drop Multiplexer is employed.

  Such a switching method is caused by failure in byte information used for bit error monitoring called BIP (Bit Interleaved Parity) described in a SONET or SDH frame overhead (section overhead: SOH), or a failure of a device or a transmission medium. This is realized by bidirectionally exchanging byte information for notifying an alarm to be performed between the own device and the opposite device.

  The SONET or SDH mainly defines the specifications of the physical layer, and another protocol is used as the data link layer protocol. For example, there is ATM (Asynchronous Transfer Mode). As switching in ATM, for example, “synchronous cell sequence number (used for identification of cell frame (described later) and synchronous cell loss detection arriving from active network and standby network)” and “cell” in a separately prepared synchronous cell “Number of cells in frame (used for detecting user cell loss in cell frame)”, “User cell error detecting code (used for detecting bit error of user cell)”, “Synchronous cell error detecting code (bit error is detected in synchronous cell) The field such as “used to prevent execution of erroneous processing when it occurs” is defined, and by using these fields, the error status of the cell is judged by the reception or system switching device or the like, and a plurality of ATM cells ( (Hereinafter referred to as a user cell to distinguish it from a synchronized cell) and a method of switching systems in units of “cell frames” consisting of synchronized cells There has been studied (see Non-Patent Document 2).

  In addition, in ATM, it is possible to perform 1-bit error correction and multi-bit error detection of a user cell header by using an HEC (Header Error Check) field in the user cell.

  That is, in ATM over SONET / SDH transmission, switching mainly based on code error monitoring in units of SONET or SDH frames, switching based on error detection in units of ATM cell frames, and an error detection mechanism for user cell headers In combination with the introduction of, high-reliability and high-quality communication between transmission and reception devices is realized.

  However, since an error detection field is not defined in each user cell payload itself, payload error detection cannot be performed on a user cell basis. If the user cell and the synchronous cell are alternately transmitted using the above method, it is possible to detect an error in the payload of the user cell and to switch the system in units of user cells, but this is considered from the viewpoint of the information rate. Is very inefficient (the information rate is half the transmission rate).

  In addition, regarding system switching, SONET or SDH equipment (relay or insertion / demultiplexing or system switching equipment) and ATM equipment (reception or system switching equipment) are operated independently, and usually at different points. Therefore, there is no method for switching to a higher quality system in cooperation between both devices.

On the other hand, Ethernet (registered trademark), which is a widely used LAN (Local Area Network) standard, has an FCS (Frame Check) in the Ethernet frame itself.
An error detection mechanism for the entire frame called “Sequence” has been introduced.

  As with ATM, Ethernet over SONET / SDH transmission is also possible, but as with ATM, SONET or SDH equipment (relay or insertion / demultiplexing or system switching equipment) and Ethernet equipment (reception or system switching) Since the devices are operated independently from each other and are usually installed at different points, there is no method for switching to a higher quality system in cooperation between the two devices.

  In the first place, when considering the use of a one-way communication network, in either case of ATM or Ethernet, since SONET or SDH adopts a switching method based on bidirectional communication, this SONET or SDH The switching method cannot be applied.

Hiroyuki Kawanishi, Kazumitsu Tsuji, Hisao Tsuji, Hiroshi Ueda, “Intuitive SDH / SONET Transmission System”, Ohm, 2001 Kazuhiro Fujiwara, Yuji Kanayama, Toshinori Tsuboi, “Realization and Evaluation of ATM Uninterrupted Transmission System for High Quality Video Transmission”, IEICE Transactions B, Vol. J84-B No. 2 pp. 157-166 February 2001

  There are various policies for switching from the active network to the standby network, but when higher quality transmission is required, a minimum configuration such as an ATM user cell or Ethernet frame (hereinafter referred to as “subframe”). It is desirable to switch to a higher quality system (with fewer bit errors etc.) in units.

  Also, if the quality of this subframe is equal, a system having a higher quality in units of a larger configuration (hereinafter referred to as “transmission frame”) including a plurality of subframes and including a synchronization header is selected. Thus, a switching method from a double (or more) viewpoint is required.

  This is because even if the quality of this subframe is the same in the active network and the backup network, it is possible to reduce the frequency of system switching if a system with a high quality in units of transmission frames is selected. It is because the nature is high. This is because the transmission frame has a longer overall length than the subframe, so that a system with high quality in units of transmission frames can be said to have higher quality for a longer time.

  However, at present, the SONET or SDH switching method based on the two-way communication mode cannot be applied to a one-way communication type network such as a broadcast-type video distribution service.

  Conventionally, switching from the active network to the backup network based on both the transmission frame quality and the subframe quality is not possible because the installation points of the devices for monitoring the quality of both are different. was there.

  The present invention has been made to solve such a problem, and is a one-way communication form such as a broadcast-type video distribution service, and it is necessary to perform highly reliable and high-quality transmission. It is an object of the present invention to provide a system switching apparatus and method that enable service development that meets the requirements.

  The present invention is applied to a network in which a data transmission source is connected to an active system and one or more standby networks, and system switching is performed to switch the system from an active network to another network according to the transmission quality of the system. In the apparatus, the transmission quality of the system is judged from both the bit error rate for a part of the transmission frame including the synchronization information as the frame structure header and the bit error presence / absence detection information of the subframe constituting the transmission frame. Transmission quality determining means, and means for switching the system in units of subframes or transmission frames in a network having a high transmission quality among a plurality of systems based on the determination result of the transmission quality determining means Features.

  This makes it possible to switch frames in units of subframes such as Ethernet frames in a one-way communication type network such as a broadcast-type video distribution service consisting of a data transmission source, an active network, and one or more backup networks. It becomes.

  Further, when the quality of subframes is equal, the system can be selected in units of larger transmission frames.

  Therefore, even when it is necessary to perform high-reliability and high-quality transmission such as a broadcast-type video distribution service, it is possible to develop a service that meets that requirement.

  Further, the transmission quality judgment means may comprise means for using a parity error rate for a part or all of the transmission frame instead of a bit error rate for a part of the transmission frame.

  Alternatively, the transmission quality judging means may comprise means for using a subframe error rate in a subframe constituting the transmission frame instead of a bit error rate for a part of the transmission frame.

  Alternatively, when a subframe used for detecting the presence or absence of a bit error in the subframe has been discarded, the transmission quality determination means includes means for inserting a specific bit pattern into a lost portion of the subframe, Means for using the bit error presence / absence detection information in the specific bit pattern may be provided instead of the bit frame presence / absence detection information.

  Further, the transmission quality judging means may comprise means for using the number of errors instead of the error rate.

  Further, when the present invention is viewed from the viewpoint as a system switching method, the present invention is applied to a network in which a data transmission source is connected to an active system and one or more standby networks, and is adapted to the transmission quality of the system. In the system switching method performed by the system switching apparatus that switches the system from the active network to another network, the transmission quality determination means includes a bit error rate for a part of the transmission frame including synchronization information as a header of the frame structure, A means for judging the transmission quality of the system from both of the detection errors of bit frames in the subframes constituting the transmission frame and switching the system is transmitted in a plurality of systems based on the judgment result of the transmission quality judging means. The system is switched to a high-quality network in units of the subframe or the transmission frame.

  Further, the transmission quality judging means may use a parity error rate for a part or all of the transmission frame instead of a bit error rate for a part of the transmission frame.

  Alternatively, the transmission quality judging means may use a subframe error rate in a subframe constituting the transmission frame instead of a bit error rate for a part of the transmission frame.

  Alternatively, if the subframe used for detecting the presence or absence of a bit error in the subframe has been discarded by the means for inserting the specific bit pattern, the specific bit pattern is inserted into the lost portion of the subframe, The transmission quality determination means may use bit error presence / absence detection information in the specific bit pattern instead of the bit frame presence / absence detection information.

  Alternatively, the transmission quality judgment means can use the number of errors instead of the error rate.

  According to the present invention, even when it is a one-way communication form such as a broadcast video distribution service and it is necessary to perform highly reliable and high-quality transmission, it is possible to develop a service that meets the demand.

(Description of overview)
In the embodiment of the present invention, for example, a LAN PHY that is one of physical layer regulations of 10 gigabit Ethernet (hereinafter referred to as 10 GbE) standardized by the IEEE 802.3 committee is used as the physical layer. However, as long as the same thing as LAN PHY can be realized, it is possible to use another rule or standard.

  In 10 GbE, the subframe referred to in the present invention corresponds to the Ethernet frame. As in a normal Ethernet frame, information (for example, CRC (Cyclic Redundancy Check) -32) that can detect the presence or absence of bit errors in the entire subframe is added to each subframe in the present invention.

In addition, in a transmission frame composed of several subframes and synchronization information necessary as a header of the frame structure, for example,
(1) The bit error rate or the number of bit errors can be measured for a partial range of the transmission frame. (2) The parity error rate or the number of parity errors can be measured for a partial range of the transmission frame or the entire range. A transmission frame header that realizes some or all of (1) to (3) such that the measurement result of the error rate or the number of errors of the subframes constituting the frame can be stored, or a special special Prepare subframes.

  In the frame switching method for high-quality transmission according to the present invention, the active network and the standby network first compare the quality in units of subframes, and transmit the subframes from the high-quality system to the system switching device and subsequent units. Or forward.

  When no error occurs in a subframe, the quality may not change between the active network and another backup network in the comparison in units of subframes. At this time, quality comparison is performed in a range larger than the subframe. Specifically, quality comparison is performed in units of transmission frames, and the system is switched based on the result. The quality comparison in units of transmission frames can be performed by using a transmission frame header satisfying some or all of the items (1) to (3) or a separate special subframe.

  On the other hand, when each subframe is compared, there is a possibility that a subframe error occurs in both the active network and the other backup network. In this case as well, a high-quality system in units of transmission frames is selected as described above. At this time, a subframe in which an error has occurred may be discarded or transmitted as it is without being discarded. . By transmitting without discarding, there is a possibility that the buffer design of the repeater and the switch on the network becomes easy.

  Normally, in an Ethernet PHY (physical layer) or MAC (data link layer) chip, an Ethernet frame in which an FCS error has occurred is discarded by the chip, but in 10 GbE, depending on the PHY or MAC chip, Even when an FCS error occurs, there is a configuration in which an Ethernet frame can be set not to be discarded by a PHY or a MAC chip only by setting a control flag.

In 10 GbE, the 2 bits of the 64B / 66B synchronization header, which is an encoding technique adopted except for some standards, is used instead of the transmission frame header satisfying (1) above or a special subframe prepared separately. May be used. In 64B / 66B, a 64-bit block of data or data and control information is scrambled (1 + X ³⁹ + X ⁵⁸ ) and then a 2-bit synchronization header is added (that is, a total of 66 bits). .

  The 2-bit synchronization header is assumed to take either “01” or “10”, and the bit error rate is estimated by counting cases other than “01” or “11”. Can be performed (in the case of random errors).

In a normal Ethernet network, since the BER (Bit Error Rate) is a very small value of the order of 10 ⁻¹² or less, an error may not be measured in units of 66 bits. In this case, a group of 66 bits is regarded as a subframe, and an Ethernet frame is regarded as a transmission frame. Bit error rate estimation in units of subframes (here, 66 bits) and parity error detection of the entire transmission frame (here, Ethernet frame) (here, It is preferable to determine the transmission quality from both sides (using CRC-32) and select a system with high quality. This is a feature of the present invention “comparison in units of subframes and comparison in units of larger transmission frames”.

  As a result, even if the quality of the subframe is the same between the active network and the standby network, a system with high quality in units of transmission frames is selected, and high-reliability and high-quality transmission is possible.

  In the bit error rate estimation, the error estimation range is a short bit string of 2 bits, and an error when changing from “01” to “10” cannot be detected, so that error detection accuracy is lacking. Further, 64B / 66B is originally used for synchronization and cancellation of a 66-bit block, and the OSI (Open Systems Interconnection) reference model hierarchy belongs to the physical layer (more precisely, the encoding sublayer). For this reason, it is necessary to devise to incorporate it into the system switching device, but this is not impossible.

(First Example)
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of a system switching device 100 according to the first embodiment. FIG. 2 is a diagram illustrating a frame structure of a transmission frame and a subframe. A frame switching method for high-quality transmission according to the first embodiment will be described with reference to FIG.

  In the present invention, a network in a one-way communication form in which a data transmission source is always connected to an active system and one or more backup networks is used, and as shown in FIG. It is assumed that there are two types of frames: a transmission frame having fixed information (fixed length or variable length) and a subframe (fixed length or variable length) constituting the transmission frame.

  In order to realize the first embodiment, bit string information for measuring the bit error rate or the number recorded in advance is stored in a transmission frame header or in a special subframe prepared separately. There is a need. Further, information (for example, CRC-32 or the like) that can detect the presence or absence of bit errors in the entire subframe is added to each subframe.

  The first embodiment is an example of a switching method for selecting a network to be adopted from information on the bit error rate or the number of bit errors for a part of a transmission frame and the presence or absence of a bit error for the entire subframe itself. .

  First, each functional block of the system switching apparatus 100 that implements the frame switching method for high-quality transmission according to the first embodiment will be described, and the overall processing flow will be described. However, the flow of the clock signal is not shown in FIG. In FIG. 1, a solid arrow represents a “data” flow, and a broken arrow represents a control information flow for realizing the present invention.

  As shown in FIG. 1, the system switching apparatus 100 according to the first embodiment includes a bit error rate or the number of parts of a transmission frame including synchronization information as a frame structure header, and the subframes constituting the transmission frame. Transmission frame bit error rate / number measurement unit 112, transmission frame bit error rate / number comparison unit 113, subframe bit error presence / absence, which are transmission quality judgment means for judging transmission quality of the system from both of the presence / absence detection information of bit errors Measuring section 115, subframe bit error presence / absence comparing section 116, and means for switching the system in units of subframes or transmission frames to a network having a high transmission quality among a plurality of systems based on the determination result of the transmission quality determining means A network switching unit 104 and a network determining unit 117.

  More specifically, the transmission frame storage unit 101 has a function of aligning the position of the first bit of the transmission frame based on the synchronization information included in the header of the transmission frame. When a sequence number is assigned to the header of each transmission frame, the transmission frame storage unit 101 stores a plurality of transmission frames, and a discharge sequence number or a discharge command from the transmission frame position management unit 111 described later. Based on this information, the transmission frame is output to the subsequent stage.

  In the subsequent transmission frame header / subframe separation unit 102, information in the transmission frame header, or by defining a specific one in the first bit string of each subframe, or the first bit of this transmission frame header or subframe is determined. The position of the first bit of this transmission frame header or subframe is determined by a method such as by using a preamble that clearly indicates, and these are separated.

  The transmission frame header / subframe accumulation unit 103 accumulates (adjusts) the same subframe so that it can be discharged in each system based on information from a transmission frame header / subframe position management unit 114 described later. More storage memory capacity is required, but even if the transmission frame header / subframe storage unit 103 causes the position of the subframe in the transmission frame to be different between the active network and the other standby network. It is possible to respond.

  The network switching unit 104 receives input of the transmission frame header or each subframe synchronized in the previous stage, and discharges the transmission frame header or subframe from the system indicated in the information from the network determination unit 117 described later. To do.

  In the first embodiment (FIG. 1), the transmission frame header and the subframe are discharged only from one system indicated by the network determination unit 117, but a plurality of transmission frames are sent from a plurality of systems. The same transmission frame header or a plurality of subframes may be discharged.

  The transmission frame generation / transmission frame header update unit 105 newly generates a transmission frame from the selected subframe and rewrites it with a transmission frame header suitable for the transmission frame. Further, when a field for measuring the bit error rate or the number of transmission frames is provided in the transmission frame header, a measurement bit string may be newly added to the transmission frame header.

  The transmission frame position management unit 111 matches the position of each transmission frame from the header information of the transmission frame, and manages so that the transmission frame synchronized with each system is discharged to the subsequent stage of the transmission frame storage unit 101 described above.

  In the transmission frame bit error rate / number measurement unit 112, bit string information for measuring the bit error rate or the number recorded in advance in the transmission frame header separated by the transmission frame header / subframe separation unit 102, or bit Based on a special subframe prepared separately for measuring the error rate or number, the bit error rate or number for the bit string information of the transmission frame from each system is measured.

  The result is notified to a transmission frame bit error rate / number comparison unit 113 described later. The information to be notified is, for example, each system information (system ID) and bit error rate or number information of transmission frames in this system.

  In the transmission frame bit error rate / number comparison unit 113, based on the information from the transmission frame bit error rate / number measurement unit 112, the bit error rate in a partial range of the transmission frame in the active system or other backup system or The number statuses are compared, for example, each system information (system ID) is arranged in ascending order of error rate or number, and notified to the network determination unit 117 described later.

  The transmission frame header / subframe position management unit 114 identifies each subframe based on position information of each subframe described in the transmission frame header or information such as a sequence number described in each subframe. Then, management is performed so that the same subframe is discharged for each system in the subsequent stage of the transmission frame header / subframe storage unit 103 described above.

  The subframe bit error presence / absence measuring unit 115 measures the presence / absence of bit errors in the entire subframes (including the transmission frame header) output by the transmission frame header / subframe storage unit 103. In order to measure the presence / absence of a bit error, information capable of detecting a bit error is added to each entire subframe (including a transmission frame header). For example, CRC-32 or the like may be added to this subframe.

  Based on the information from the subframe bit error presence / absence measurement unit 115, the subframe bit error presence / absence comparison unit 116 compares the bit error presence / absence status in the entire range of the subframe itself in the active system or other standby system, for example, The system information (system ID) is arranged for each error-free or status-existing and notified to the network determination unit 117 described later.

  The network determination unit 117 selects a subframe of which system from the active system and other standby systems based on the information from the transmission frame bit error rate / number comparison unit 113 and the subframe bit error presence / absence comparison unit 116 described above. Decide whether to do so, and notify the network switching unit 104.

  FIG. 3 shows a flowchart for determining the network in the network determining unit 117. That is, as shown in FIG. 3, if there is no error in the working subframe (No in step S1), the working system remains selected (step S7), but there is an error in the working subframe. (Yes in step S1) At this time, if there is no error in the spare subframe (No in step S2) and there is one spare subframe (No in step S5), the spare system is selected. (Step S6). If there are a plurality of spare subframes (Yes in step S5), the spare system having the smallest error rate or number of spare transmission frames (Yes in step S4) is selected (step S6).

  In addition, there is an error in the working subframe (Yes in step S1). At this time, there is also an error in the standby subframe (Yes in step S2), and the error rate or the number of transmission frames in the working system is different. If it is the minimum compared to the system (Yes in step S3), the current system remains selected (step S7).

  These selection results are notified to the network switching unit 104 (step S8).

  The basic concept in the processing of the network determination unit 117 is to give priority to the quality of the subframe, and then give priority to the currently used network. Here, the quality of this sub-frame represents the presence or absence of bit errors in this sub-frame. If this quality is the same in the active system and other backup systems, priority is given to the quality in the transmission frame comprising this sub-frame. . Similarly, the quality of this transmission frame represents here the bit error rate or number of parts of the transmission frame.

  Step S3 in FIG. 3 is “active system“ transmission frame ”error rate or number is minimum”, and step S2 is “backup system“ subframe ”error-free system” is step S5 “plurality”. Whether the network determination unit 117 itself has information such as whether or not the error rate or the number of the standby “transmission frames” is the minimum ”is determined by the network determination unit 117 itself and the transmission frame bit error rate / number comparison unit 113 and It may be derived from the information obtained from the subframe bit error presence / absence comparison unit 116, or the transmission frame bit error rate / number comparison unit 113 and the subframe bit error presence / absence comparison unit 116 that notify the network determination unit 117 of information. May be derived and notified to the network determination unit 117 together with information on each result.

  The overall processing flow has been described with each functional block. According to the present invention, in a one-way communication type network such as a broadcast-type video distribution service composed of a data transmission source, an active network, and one or more standby networks, subframe units such as an ATM user cell or an Ethernet frame Switching is possible with.

  Further, when the quality of subframes is equal, the system can be selected in units of larger transmission frames. As a result, even if it is a one-way communication form such as a broadcast-type video distribution service and it is necessary to perform highly reliable and high-quality transmission, it is possible to develop a service that meets that requirement.

(Second embodiment)
A second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a block diagram of the system switching apparatus 200 according to the second embodiment. With reference to FIG. 4, a frame switching method for high-quality transmission according to the second embodiment will be described.

  In the second embodiment, a network to be adopted is selected from information on the parity error rate or the number of parity errors for a part or all of a transmission frame and the presence / absence of a bit error for the entire subframe.

  As described in the first embodiment, the present invention uses a one-way communication type network in which a data transmission source and a working and one or more backup networks are always connected, and is required as a frame structure header. It is assumed that there are two types of frames, a transmission frame having synchronization information and a subframe constituting this transmission frame (see FIG. 2).

  In order to realize the second embodiment, it is necessary to prepare a field for measuring an even or odd parity error rate or number in a transmission frame header or in a special subframe prepared separately. is there. Further, a mechanism (for example, CRC-32 or the like) that can detect the presence or absence of bit errors in the entire subframe is added to each subframe.

  First, each functional block of the switching device 200 that implements the switching method of the second embodiment will be described, and the overall processing flow will be described. However, as in FIG. 1, the flow of the clock signal is not shown in FIG. Also in FIG. 4, solid arrows indicate the flow of data, and broken arrows indicate the flow of control information for realizing the present invention.

  As shown in FIG. 4, the system switching apparatus 200 according to the second embodiment includes a parity error rate or the number of a part of a transmission frame including synchronization information as a frame structure header, and the subframes constituting the transmission frame. Transmission frame parity error rate / number measurement section 212, transmission frame parity error rate / number comparison section 213, subframe bit error presence / absence, which are transmission quality judgment means for judging transmission quality of the system from both the presence / absence detection information of bit errors Measuring section 215, subframe bit error presence / absence comparing section 216, and means for switching the system in units of subframes or transmission frames to a network having a high transmission quality among a plurality of systems based on the determination result of the transmission quality determining means A network switching unit 204 and a network determining unit 217.

  If it demonstrates in detail, the block block diagram of 2nd Example and 1st Example is the substantially the same structure. Only the transmission frame parity error rate / number measurement unit 212 and the transmission frame parity error rate / number comparison unit 213 are different from each other in the figure, and the function block will be mainly described.

  In the transmission frame parity error rate / number measurement unit 212, the parity information recorded in advance in the transmission frame header separated by the transmission frame header / subframe separation unit 202 and the parity for a predetermined transmission frame range (for example, BIP etc.) are compared with the check results, and the parity error rate or number of transmission frames in the system is measured. The result is notified to a transmission frame parity error rate / number comparison unit 213 described later. The information to be notified is, for example, each system information (system ID) and the parity error rate or number information of transmission frames in this system.

  In the transmission frame parity error rate / number comparison unit 213, based on the information from the transmission frame parity error rate / number measurement unit 212 described above, a part of or the entire range of the transmission frame in the active system or another backup system For example, each system information (system ID) is arranged in ascending order of error rate or number, and notified to the network determination unit 217 described later.

  The network determination unit 217 determines which subframe of which system out of the active system and other standby systems from the information from the transmission frame parity error rate / number comparison unit 213 and the subframe bit error presence / absence comparison unit 216 described above. Is to be selected and notified to the network switching unit 204.

  The flowchart of the network determination in the network determination unit 217 is represented in FIG. 3 as in the first embodiment. Here, the basic idea is to give priority to the quality of the subframe, and then give priority to the currently used network. Here, the quality of a subframe represents the presence / absence of a bit error in the subframe. When this quality is the same in the active system and other backup systems, priority is given to the quality in the transmission frame comprising this subframe. Similarly, the quality of this transmission frame is different from the first embodiment here, and represents the even or odd parity error rate or the number for a part or all of the transmission frame.

  The other functions are almost the same as in the first embodiment, and instead of the bit error rate or the number of transmission frames in the first embodiment, part or all of the transmission frames as in the second embodiment. Parity error rate or number (even or odd) for a range of.

  As described above, as in the first embodiment, even if it is a one-way communication form such as a broadcast-type video distribution service and it is necessary to perform highly reliable and high-quality transmission, it is possible to develop a service that meets that requirement. Become.

(Third embodiment)
A third embodiment of the present invention will be described with reference to FIG. FIG. 5 is a block diagram of the system switching apparatus 300 according to the third embodiment. With reference to FIG. 5, a frame switching method for high-quality transmission according to the third embodiment will be described.

  In the third embodiment, a network to be employed is selected from information on the error rate of the subframes constituting the transmission frame or the number of subframe errors and the presence / absence of bit errors in the entire subframe.

  First, each functional block of the system switching apparatus 300 that implements the frame switching method for high-quality transmission according to the third embodiment will be described, and the overall processing flow will be described. However, like FIG. 1 and FIG. 4, in FIG. 5, the flow of the clock signal is not shown. Also in FIG. 5, the solid line arrows represent the flow of data, and the broken line arrows represent the flow of control information for realizing the present invention.

  As shown in FIG. 5, the system switching apparatus 300 according to the third embodiment configures the transmission frame with the subframe error rate or the number of subframes constituting the transmission frame including the synchronization information as the frame structure header. A subframe bit error presence / absence measuring unit 313, a subframe bit error presence / absence comparing unit 314, and a subframe error in a transmission frame, which are transmission quality judgment means for judging transmission quality of the system from both of the subframe bit error presence / absence detection information. A rate / number measuring unit 315, an intra-transmission frame sub-frame error rate / number comparing unit 316, and a transmission quality determining unit based on the determination result of the transmission quality determining unit, a subframe unit or transmission A network switching unit 304 and a network determination unit 31 which are means for switching systems in units of frames. Provided with a door.

  Furthermore, when a subframe used for detection of the presence / absence of a bit error in the subframe has been discarded, a means (not shown) for inserting a specific bit pattern into the lost portion of the subframe is provided, and transmission quality judgment means Can use the bit error presence / absence detection information in a specific bit pattern instead of the subframe bit error presence / absence detection information. The means for inserting a specific bit pattern may be provided in the system switching device 300 or may be provided outside the system switching device 300 as a separate device.

  More specifically, the third embodiment has a block configuration substantially similar to that of the first and second embodiments. The difference in the figure is the presence of the transmission frame subframe error rate / number measurement unit 315 and the transmission frame subframe error rate / number comparison unit 316, and the role of the subframe bit error presence / absence measurement unit 313.

  In the transmission frame subframe error rate / number measurement unit 315, the subframe bit error presence / absence measurement unit 313 notifies the subframe bit error presence / absence information of the subframe synchronized by the transmission frame header / subframe storage unit 303. Thereby, the error rate or the number of subframes in this transmission frame is measured. The result is notified to the transmission frame subframe error rate / number comparison section 316 described later. The information to be notified is, for example, each system information (system ID) and error rate or number information of subframes in this system.

  In the transmission frame subframe error rate / number comparison unit 316, based on the information from the transmission frame subframe error rate / number measurement unit 315 described above, the subframe error rate in the transmission frame in the active system or another backup system. For example, each system information (system ID) is arranged in ascending order of error rate or number, and notified to a network determination unit 317 described later.

  In the network determination unit 317, the subframe error rate / number comparison unit 316 in the transmission frame and the subframe bit error presence / absence comparison unit 314 determine which system sub-system from among the active system and other standby systems. It is determined whether a frame should be selected, and the network switching unit 304 is notified.

  A flowchart for determining a network in the network determining unit 317 is shown in FIG. 3 as in the first and second embodiments. Here, the basic idea is to give priority to the quality of the subframe, and then give priority to the currently used network. Here, the quality of this sub-frame represents the presence or absence of bit errors in this sub-frame. If this quality is the same in the active system and other backup systems, priority is given to the quality in the transmission frame comprising this sub-frame. . Similarly, the quality of this transmission frame represents the error rate or number of subframes constituting the transmission frame, unlike the first and second embodiments.

  The other functions are almost the same as those in the first and second embodiments. Instead of the bit error rate or the number of transmission frames in the first embodiment, the subframe error rate or Use the number.

  In addition, although applicable to the first and second embodiments, the subframe bit error presence / absence measuring unit 313 detects the presence / absence of a bit error using a subframe bit error detection mechanism (such as CRC-32). Although it has been determined, it may be determined by another bit string information prepared. For example, when the subframe is an Ethernet frame, the Ethernet frame may be discarded at any location due to detection of an FCS error.

  In this case, it is also possible to insert some other bit string in the Ethernet frame lost part. In such a case, the subframe bit error presence / absence measuring unit 313 uses the specially prepared bit string information to perform sub The presence or absence of a bit error in the frame (in this case, the Ethernet frame) can be determined.

  As described above, as in the first and second embodiments, even if it is a one-way communication form such as a broadcast-type video distribution service and it is necessary to perform high-reliability and high-quality transmission, a service that meets the requirements Deployment is possible.

(Example of the program)
An example of a program that, when installed in an information processing apparatus, causes the information processing apparatus to realize functions corresponding to the functions of the system switching apparatuses 100, 200, and 300 of the first to third embodiments will be described.

  By recording the program of this embodiment on a recording medium, the information processing apparatus can install the program of this embodiment using this recording medium. Alternatively, the program of the present embodiment can be directly installed on the information processing apparatus from the server holding the program of the present embodiment via the network.

  Thereby, using the information processing apparatus, the transmission frame storage units 101, 201, 301 and the transmission frame header / subframe separation units 102, 202, 302 in the system switching devices 100, 200, 300 of the first to third embodiments are used. , Transmission frame header / subframe storage units 103, 203, 303, network switching units 104, 204, 304, transmission frame generation and transmission frame header update units 105, 205, 305, transmission frame position management units 111, 211, 311, Transmission frame bit error rate / number measurement unit 112, transmission frame bit error rate / number comparison unit 113, transmission frame header / subframe position management units 114, 214, 312, subframe bit error presence / absence measurement units 115, 215, 313, Subframe bit error presence / absence comparing section 116, 16, 314, network decision units 117, 217, 317, transmission frame parity error rate / number measurement unit 212, transmission frame parity error rate / number comparison unit 213, transmission frame subframe error rate / number measurement unit 315, transmission frame A function corresponding to the function of the inner subframe error rate / number comparison unit 316 can be realized.

  The program of this embodiment includes not only a program that can be directly executed by the information processing apparatus but also a program that can be executed by being installed on a hard disk or the like. Also included are those that are compressed or encrypted.

  According to the present invention, even when it is a one-way communication form such as a broadcast-type video distribution service and it is necessary to perform high-reliability and high-quality transmission, it is possible to develop a service that meets that requirement. It can be used to improve the quality of video distribution services.

It is a block block diagram of the system switching device of the first embodiment. It is a figure which shows the frame structure of a transmission frame and a sub-frame. It is a figure which shows the flowchart of the network determination in a network determination part. It is a block block diagram of the system switching device of the second embodiment. It is a block block diagram of the system switching device of the third embodiment.

Explanation of symbols

100, 200, 300 System switching device 101, 201, 301 Transmission frame storage unit 102, 202, 302 Transmission frame header / subframe separation unit 103, 203, 303 Transmission frame header / subframe storage unit 104, 204, 304 Network switching Unit 105, 205, 305 transmission frame generation and transmission frame header update unit 111, 211, 311 transmission frame position management unit 112 transmission frame bit error rate / number measurement unit 113 transmission frame bit error rate / number comparison unit 114, 214, 312 Transmission frame header / subframe position management unit 115, 215, 313 Subframe bit error presence / absence measurement unit 116, 216, 314 Subframe bit error presence / absence comparison unit 117, 217, 317 Network determination unit 212 Transmission frame Parity error rate / number measuring section 213 transmits the frame parity error rate / number comparing section 315 transmits the frame in a sub-frame error rate / number measuring unit 316 transmission frame in a sub-frame error rate / number comparing unit

Claims (10)

In a system switching device that is applied to a network in which a data transmission source is connected to an active system and one or more standby networks, and switches the system from the active network to another network according to the transmission quality of the system,
Transmission quality judgment that judges the transmission quality of the system from both the bit error rate for a part of the transmission frame including the synchronization information as a frame structure header and the bit error presence / absence detection information of the subframes constituting this transmission frame Means,
A system switching apparatus comprising: means for switching a system in units of subframes or in units of transmission frames in a network having a high transmission quality among a plurality of systems based on a judgment result of the transmission quality judgment means .   2. The system switching apparatus according to claim 1, wherein said transmission quality judging means comprises means for using a parity error rate for part or all of said transmission frame instead of a bit error rate for said part of said transmission frame.   2. The system switching apparatus according to claim 1, wherein said transmission quality judging means comprises means for using a subframe error rate in a subframe constituting said transmission frame instead of a bit error rate for a part of said transmission frame. When a subframe used for detection of the presence or absence of a bit error in the subframe has been discarded, a means for inserting a specific bit pattern into a lost portion of the subframe,
The said transmission quality judgment means was provided with the means to use the bit error presence / absence detection information in the said specific bit pattern instead of the bit error presence / absence detection information of the said sub-frame. System switching device.   5. The system switching apparatus according to claim 1, wherein the transmission quality judgment unit includes a unit that uses the number of errors instead of the error rate. 6. A system that is applied to a network in which a data transmission source is connected to an active system and one or more standby networks, and is performed by a system switching device that switches the system from the active network to another network according to the transmission quality of the system In the switching method,
The transmission quality judgment means determines the transmission quality of the system from both the bit error rate for a part of the transmission frame including the synchronization information as the frame structure header and the bit error presence / absence detection information of the subframes constituting this transmission frame. Judging
The system switching means characterized in that the system switching means switches the system in the subframe unit or the transmission frame unit to a network having a high transmission quality among a plurality of systems based on the determination result of the transmission quality determining unit. Method.   7. The system switching method according to claim 6, wherein the transmission quality judgment means uses a parity error rate for a part or all of the transmission frame instead of a bit error rate for the part of the transmission frame.   7. The system switching method according to claim 6, wherein the transmission quality judgment means uses a subframe error rate in a subframe constituting the transmission frame instead of a bit error rate for a part of the transmission frame. When a subframe used for detecting the presence or absence of a bit error in the subframe has been discarded by the means for inserting the specific bit pattern, the specific bit pattern is inserted into the lost portion of the subframe,
The system switching method according to any one of claims 6 to 8, wherein the transmission quality determination means uses bit error presence / absence detection information in the specific bit pattern instead of bit error presence / absence detection information of the subframe. .   The system switching method according to any one of claims 6 to 9, wherein the transmission quality judgment means uses the number of errors instead of the error rate.

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