JP2000151572A - Frame synchronizing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable reducing time required for restoring into a normal synchronous state by judging that an error or erroneous synchronization of a received package signal occurs when an undefined code value is received on a reception side and starting packet synchronization processing for taking in a new packet immediately. SOLUTION: Since frame synchronizing information is not detected within a timer time of T-05, communication equipment recognizes the occurrence of abnormality at this point of time. After that, packet synchronization processing for immediately taking in a new packet is started. Packet synchronization is established, frame synchronization information in a signal 400 is detected and the frame synchronization is established by a frame packet signal 400 of a frame frequency f(100)-#1 next to a frame F#100. Thus, the frame synchronization can be recovered by a time FS-T until the frame synchronization information is detected by a frame frequency f(100)-#2 after erroneous synchronization is generated by an n-th frame frequency f(100) of the frame F#100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame synchronization method in a transmission system using a packet signal, and more particularly, to a method for transmitting a frame packet signal in which frame synchronization information for establishing frame synchronization is defined. The present invention relates to a frame synchronization method for synchronizing a frame packet signal transmitting device that transmits at periodic intervals and a frame synchronization processing device that reads frame synchronization information in the frame packet signal and performs a frame synchronization process.

[0002]

2. Description of the Related Art An example of a conventional transmission system using a packet signal will be described with reference to FIGS. FIG. 1 is a diagram showing an example of a conventional transmission system using a packet signal.
0 and the communication device 200 are connected by a transmission line 300, and perform bidirectional communication by packet signals. In this case, the communication devices 100 and 200 operate synchronously at a fixed period, that is, a frame period by the frame synchronization method.

[0003] F # 100 in FIG. 1 indicates a frame structure of a packet sent from the communication apparatus 100, and a frame packet signal 400 in which transmission control information such as frame synchronization information for establishing frame synchronization and maintenance information are defined. , And
It comprises a data packet signal 401 in which signal information and the like are defined. The frame packet signal 400 is arranged on a frame at an interval of f (100), which is the frame period of the communication device 100, and transmitted to the communication device 200. In the figure, F # 200 indicates the timing of frame synchronization in the communication device 200, and recognizes frame synchronization information defined in the frame packet signal 400 of F # 100 and establishes frame synchronization at the timing indicated by A. The synchronization is performed at f (200) which is the same frame period as the frame period f (100) of the communication device 100.

FIG. 2 is a diagram showing an example of the structure of a packet signal used in a conventional transmission system using a packet signal. FIG. 2A shows the structure of a frame packet signal 400, and FIG.
Indicates the structure of the data packet signal 401. Each of the packet signals 400 and 401 has a packet header portion h defined by information common to each packet signal, and
It is composed of a packet information section d1 or d2 defined by information specific to each packet signal.

A packet header portion h defined by information common to each packet signal includes guard time information G indicating a delimiter between packets, preamble information P for recognizing code bits (bit synchronization), and a head of the packet. It comprises delimiter information D for recognizing (packet synchronization) and type information T for recognizing the type of the packet signal. In the conventional type information T, a code value indicating a packet signal for performing transfer and control of the maintenance information of the entire transmission method and a code value indicating a packet signal for transmitting signal information and the like are set. I have. In such a conventional method, a packet signal for transferring and controlling the maintenance information is used in addition to the frame packet signal 400, and the code value of the type information T is determined by the transfer and the transfer of the frame packet signal 400 and the maintenance information. A common code value is set for other packet signals to be controlled.

[0006] In the packet information section d1 of the frame packet signal 400, frame synchronization information and maintenance control information for establishing frame synchronization are defined. Normally, such information is defined at a fixed position in the packet information section d1. Also, the packet information part d2 of the data packet signal 401
Stores a data signal.

FIG. 3 is a diagram showing an example of an algorithm of a frame synchronization establishing process on the receiving side in a conventional transmission system using a packet signal. The process starts in step S00, determines whether to establish bit synchronization in step S01, and determines whether to establish packet synchronization in step S02. If it has not been established, the judgment is made again from step S01. When the bit synchronization and the packet synchronization are established, the counting of the frame synchronization processing timer is started in step S04. In step S05, the detection of the frame synchronization information is repeatedly performed for a time corresponding to one packet signal. If the frame synchronization information is detected, the timer is stopped in step S06, and the synchronization for establishing the frame synchronization is performed in step S07. Perform protection processing. In step S08, it is determined whether or not the result of the frame synchronization protection processing in step S07 conforms to the conditions for establishing frame synchronization. Synchronization established state ST-1
Transitions to. If the result of the determination in step S08 indicates that the result of the frame synchronization protection processing does not satisfy the conditions for establishing frame synchronization, step S01 is performed until frame synchronization is established.
Is repeated.

In step S05, if the frame synchronization information cannot be detected within the time corresponding to one packet signal and the timer has counted out, the timer is stopped in step S09, and the frame synchronization protection processing in step S10 is performed until now. Is reset, and the process from step S01 is newly repeated. When the timer counts out, there is a code error in the frame synchronization information, or erroneous packet synchronization in which other information in the packet signal is erroneously determined as delimiter information D occurs, and the frame synchronization information is lost. This is the case when it cannot be detected. In the case of erroneous packet synchronization, it is necessary to immediately detect a regular packet synchronization position and perform processing to quickly restore frame synchronization.

FIG. 4 is a diagram showing an example of a case where frame synchronization is recovered from a conventional packet error synchronization. F # 100 is a downstream frame from the communication device 100 to the communication device 200, and the frame packet signal 400 is arranged and transmitted at intervals of the frame period f (100). The mark "x" indicates that the communication device 200 erroneously determined the code in the data packet signal 401 of the n-th frame period f (100)-# n of the frame F # 100 as the delimiter information D, and packet erroneous synchronization occurred. Is shown. The frame packet signal 400 is transmitted adjacently within a time corresponding to one packet signal from the packet erroneous synchronization position.

F # 200-05T indicates a timer operation in the frame synchronization information detection judgment of the frame synchronization algorithm of the communication device 200, and operates as follows, similarly to the example shown in FIG. The communication device 200 erroneously judges the code in the data packet signal 401 of the n-th frame period f (100)-# n of the frame F # 100 as delimiter information D (packet erroneous synchronization), and determines the frame synchronization information. The timer of S05 starts. However, even if the normal frame packet signal 400 exists in the next cycle f (100)-# 1, the frame packet signal 400 is not transmitted within T-05, which is the frame synchronization processing timer time corresponding to one packet signal. It cannot be recognized and frame synchronization information cannot be detected. Therefore, the timer of the frame synchronization information detection determination step S05 counts out. At this point, the communication device 200 recognizes that an abnormality has occurred.

Assuming that the condition of the frame synchronization protection process for establishing the frame synchronization is that frame synchronization information is detected twice consecutively, after the occurrence of erroneous synchronization, the next period f
If the frame packet signal 400 of (100)-# 1 can be recognized, the frame synchronization can be restored by the frame packet signal 400 of the next cycle f (100)-# 2. However,
Since the frame packet signal 400 having the period f (100)-# 1 cannot be recognized at the timing shown in FIG. 4, the frame synchronization is first established when the frame synchronization information of the frame packet signal 400 having the period f (100)-# 3 is detected. Will do. That is,
The time between the occurrence of false synchronization and the recovery of frame synchronization is 2
A recovery time FS-T exceeding the cycle will be required.

As described above, in the conventional system for transmitting a packet signal, when a packet erroneous synchronization occurs while frame synchronization is not established, a timer for detecting specific information such as frame synchronization counts out. However, there is a problem that abnormalities such as packet erroneous synchronization cannot be recognized until the error occurs. In order to remedy this, if the set value of the protection time of this timer is lengthened, the recognition of abnormalities such as erroneous packet synchronization and the reprocessing for establishing packet synchronization are delayed in proportion to the time, and the frame synchronization recovery is performed. There is a problem that affects time.

[0013]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to detect an error in a received packet signal and occurrence of packet erroneous synchronization at an early stage, and to restore a normal synchronization state. It is an object of the present invention to provide a frame synchronization method capable of shortening the time required for the frame synchronization.

[0014]

In order to achieve the above object, a frame synchronization method according to the present invention is arranged such that, in the frame synchronization method as described above, the transmitting side uses a frame packet signal transmitting device to generate a frame packet signal. A unique code value indicating the frame packet signal is set in the type information indicating the type of the defined packet signal, and the frame packet signal in which the unique code value is set is transmitted at a frame cycle interval. The synchronization processing device reads the type information of the frame packet signal, starts the frame synchronization process when a unique code value is received, and starts an error or error in the received packet signal when an undefined code value is received. Judging that synchronization has occurred, and immediately starting a packet synchronization process for pulling in a new packet.

According to another frame synchronization method of the present invention, in the frame synchronization method as described above, on the transmitting side, a frame packet signal transmitting device defines frame synchronization information at a predetermined fixed position in a frame packet signal. And
Transmitting the frame packet signal at frame period intervals;
On the receiving side, when the frame synchronization information is detected by the frame synchronization processing device within the time up to the position where the frame synchronization information of the frame packet signal is arranged,
If the frame synchronization process is started and the frame synchronization information is not detected within the time until the frame synchronization information of the frame packet signal is arranged, it is determined that an error or erroneous synchronization of the received packet signal has occurred. And immediately starts a packet synchronization process for pulling in a new packet.

According to such a frame synchronization method of the present invention, it is possible to detect an error in a received packet signal and occurrence of packet erroneous synchronization at an early stage, and to shorten the time required to restore a normal synchronization state. Can be.

[0017]

Next, embodiments of the present invention will be described.
FIG. 5 is a diagram showing an algorithm of a frame synchronization establishing process in the embodiment of the frame synchronization method of the present invention.
FIG. 8 is a diagram for explaining a frame synchronization recovery time from packet erroneous synchronization in the embodiment of the frame synchronization method of the present invention.

In FIG. 5, when a frame packet signal 400 including frame synchronization information is received from the opposite communication device, the process starts in step S00. Step S00
Steps S02 to S02 are the same as the conventional steps shown in FIG. 3. A determination is made in step S01 to establish bit synchronization, and a determination is made in step S02 to establish packet synchronization. The communication device on the opposite transmitting side uses the frame packet signal transmitting device to add, to the type information T indicating the type of the packet signal defined in the frame packet signal, a unique type indicating only the type of the frame packet signal including the frame synchronization information. A code value is set, and a frame packet signal in which the unique code value is set is transmitted at frame cycle intervals. The communication device on the receiving side determines in step S03 whether or not the type of the packet signal is a code value unique to the frame packet signal including the frame synchronization information. To start the frame synchronization processing timer.

If the value of the type information T of the packet signal is another code value such as a data packet, the process proceeds to each type. If the type information T is an undefined code value with no type information defined, It is determined that the code value cannot be detected due to the code value error of the type information or the packet erroneous synchronization, and step S
Returning to 01, the bit synchronization and packet synchronization processing of a new packet pull-in are started quickly. As described above, by defining the code value unique to the frame packet signal in the type information T of the frame packet signal and determining the normality of the packet signal received in a short cycle unit from the packet synchronization to the defined position of the type information, The frame synchronization recovery time can be reduced.

After the counting of the frame synchronization processing timer is started in step S04, detection of frame synchronization information for establishing frame synchronization is determined in step S05. The frame type information and the frame synchronization information for establishing the frame synchronization are fixedly defined at predetermined positions in the frame packet signal. As a result, the device that performs the frame synchronization process can predict the time from when the frame information is determined to be the frame packet signal based on the type information in step S03 to when the frame synchronization information is received. The processing timer time is defined, and the normality of the received packet signal and the detection and determination of the frame synchronization information can be determined in a shorter cycle than before.

If the frame synchronization information is detected in the step S05, the same processing as that of the conventional step shown in FIG. The state transits from ST-0 to the frame synchronization established state ST-1. On the other hand, if the frame synchronization information cannot be detected by the determination in step S05 and the timer has counted out, in steps S09 and S10,
The same processing as the conventional step shown in FIG. 3 is performed, and the processing from step S01 is newly repeated.

As described above, the time for performing the detection and determination of the frame synchronization information in step S05 is set as short as possible, and the normality of the received packet signal is determined. When an abnormality is detected, a new packet is immediately transmitted. By starting the packet synchronization process for pulling in, it is possible to shorten the time required for restoring the frame synchronization.

The algorithm in this embodiment has been described as a configuration that uses both the method of determining based on the type information T in step S03 and the method of setting a shorter frame synchronization processing timer time in step S05. Similar control is possible with the configuration used. In the case of the configuration using only the method of step S05, the frame synchronization processing timer time is a time corresponding to the time from when the packet synchronization is established until the frame synchronization information is defined.

FIG. 6 is a diagram for explaining an example of the frame synchronization recovery time from packet erroneous synchronization according to the present invention, and the symbols have the same meanings as in FIG. 4 for explaining the conventional example. F # 200-05T indicates a timer operation of frame synchronization information detection determination of a frame synchronization algorithm used in the communication device 200 which receives the frame packet signal 400 having frame synchronization information and performs frame synchronization processing. Here, the algorithm described with reference to FIG. 5 is used, but the type information determination in step S03 is not used. Also, the frame synchronization processing timer time T-0 in step S05.
5 is described as the time corresponding to the time from when the packet synchronization is established to when the frame synchronization information is defined.

The communication device 200 erroneously determines the code in the data packet signal 401 of the n-th frame period f (100)-# n of the frame F # 100 as delimiter information D (packet erroneous synchronization), The timer of the detection determination step S05 starts. However, since the frame synchronization information is not detected within the timer time of T-05, the frame synchronization processing timer in the frame synchronization information detection determination step S05 counts out, and the communication device 200 recognizes that an abnormality has occurred at this time. I do. Thereafter, the packet synchronization process for pulling in a new packet is immediately started.

Next frame period f (100) of frame F # 100
The packet synchronization is established by the frame packet signal 400 of-# 1, and the frame synchronization information in the frame packet signal 400 is detected. Assuming that the condition of the protection processing for establishing the frame synchronization is a case where the frame synchronization information is detected twice consecutively as in the case of FIG.
The frame synchronization is established by detecting the frame synchronization information of the frame packet signal 400 of the frame period f (100)-# 2 next to # 100. Therefore, after the erroneous synchronization occurs in the n-th frame period f (100)-# n of the frame F # 100,
The frame synchronization can be restored in the time FS-T until the frame synchronization information is detected in the frame period f (100)-# 2.

As described above, in a system for transmitting a packet signal, by setting the time from reception of a packet to detection and determination of frame synchronization information to be as short as possible, abnormality in a packet signal and detection of a packet can be performed. The packet synchronization process is executed in a short cycle, and when an abnormality is detected, the packet synchronization process of a new packet pull-in can be started immediately, and the recovery time of the frame synchronization can be shortened. A unique code value indicating a packet signal including frame synchronization information is defined in the type information T, and the same applies to the case where the type information determination step S03 is used.

FIG. 7 is a diagram showing an example of another system configuration to which the present invention can be applied. In this system,
The main device 510 includes one trunk line 531, a branching device 532, and a plurality of branch lines each having a different transmission distance.
A plurality of slave devices 520 are connected via 533. Between the main unit 510 and each slave unit 520, a signal from the communication network 530 and a signal from the slave line 534 are packetized to form a single transmission rate (single rate transmission system) or a plurality of transmission rates (multi-rate transmission). Rate transmission system).

In the downward communication from the main unit 510 to each of the slave units 520, the packet signal is split by the branching unit 532. A packet signal including frame synchronization information for establishing frame synchronization is transmitted from the main unit 510 at frame cycle intervals, and each slave unit 520 reads the frame synchronization information of the packet signal to establish and operate the frame synchronization. Conversely, in upstream communication from each slave device 520 to the main device 510, the packet signal is merged by the multiplexing / branching device 532.

FIG. 8 is a diagram showing an example of a frame synchronization abnormality detecting method to which the present invention is applied as another embodiment of the frame synchronization method of the present invention. FIG. 8 shows an algorithm of the frame synchronization abnormality detection processing. With this, when a frame packet signal including frame synchronization information is received from an opposite communication device, the frame synchronization establishment state ST. The transition from -1 to the frame synchronization unestablished state ST-0 is detected.

In FIG. 8, the setting of the timer value used in the type information determination step S03 and the frame synchronization information detection determination step S05 is used to detect an abnormality in frame synchronization. Usually, the frame packet signal is received in synchronization with the frame period f (200) recognized by the receiving communication device. Therefore, the frame synchronization processing in a state where the frame synchronization is established may be performed on the packet signal received at this timing.

If the received packet signal is determined to be synchronized in the bit synchronization establishing step S01 and the packet synchronization establishing step S02, the type information determining step S03 is performed.
Proceed to. In the type information determination step S03, the same determination as in step S03 of FIG. 5 is performed, and if it is determined that the value is the frame packet signal value, the process proceeds to the frame period determination step S11. In the frame cycle determination step S11, it is determined whether the packet signal is a packet received in synchronization with the frame cycle f (200). If synchronized with the frame period f (200), it is determined that a frame packet signal has been received,
The frame synchronization processing after step S04 is started. In the frame synchronization information detection determination step S05, the frame synchronization information detection determination is performed by setting the timer value for performing the frame synchronization information detection determination in the same manner as in FIG. If the frame synchronization information is detected, the timer stop step S
09 and the frame synchronization protection reset step S10 are executed, and the process is newly repeated from step S01.

If it is determined that the bit synchronization has not been established in the bit synchronization establishment step S01 and the packet synchronization establishment step S02, and if the type information is determined to be undefined in the type information determination step S03, the frame period is further determined in step S12.
It is determined whether or not the packet is received in synchronization with f (200). When the frame synchronization is synchronized with the frame period f (200), it is determined that a frame synchronization abnormality has occurred, and a frame synchronization protection process step S07, which is a frame synchronization process for making a transition to a state where frame synchronization is not established, is executed. If no frame synchronization information is detected in the frame synchronization information detection determination step S05, it is determined that a frame synchronization abnormality has occurred, and a timer stop step S06, which is a frame synchronization process for transitioning to a state where frame synchronization is not established, is performed. The frame synchronization protection processing step S07 is executed.

If it is determined in steps S11 and S12 that the frame signal is not synchronized with the frame period f (200), it is determined that some error or the like has occurred in the packet signal.
It returns to step S01.

In the frame synchronization establishment determining step S08,
It is determined whether or not the result of the frame synchronization protection processing in step S07 conforms to the condition of non-establishment of frame synchronization.
Transitions to. As a result of the determination in step S08, if the result of the frame synchronization protection processing does not satisfy the condition of the frame synchronization not being established, the processing for detecting the frame synchronization abnormality is performed again.

[0036]

As described above, according to the frame synchronization method of the present invention, the detection and determination of the information related to the frame synchronization is performed in a very short cycle unit, the normality of the received packet signal is determined, By quickly performing the packet re-attachment process due to a received packet error or the like, the frame synchronization recovery time can be shortened. In particular,
When starting up the power supply, when recovering from a transmission line failure, etc.
This is effective for establishing frame synchronization from an unstable state in which period information such as a frame has not been established.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a conventional transmission method using a packet signal.

FIG. 2 is a diagram illustrating an example of a structure of a packet signal used in a transmission method using a conventional packet signal.

FIG. 3 is a diagram illustrating an example of an algorithm of a frame synchronization establishing process on a receiving side in a conventional transmission method using a packet signal.

FIG. 4 is a diagram showing an example of a case where frame synchronization is recovered from erroneous packet synchronization in the related art.

FIG. 5 is a diagram showing an algorithm of a frame synchronization establishing process in the embodiment of the frame synchronization method of the present invention.

FIG. 6 is a diagram for explaining a frame synchronization recovery time from an erroneous packet synchronization in the embodiment of the frame synchronization method of the present invention.

FIG. 7 is a diagram showing an example of another system configuration to which the present invention can be applied.

FIG. 8 is a diagram illustrating an example of a frame synchronization abnormality detection method to which the present invention is applied.

[Explanation of symbols]

 100, 200 Communication device 300 Transmission line 400 Frame packet signal 401 Data packet signal 510 Main device 520 Slave device 531 Main line 532 Branching device 533 Branch line 534 Slave line

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takama Kakinuma 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo F-term in Japan Telegraph and Telephone Corporation 5K028 AA01 AA14 MM05 MM08 MM12 MM17 NN01 NN05 NN12 5K030 GA01 HA08 HB11 HB15 HB29 JA05 KA21 LA01 LA15 MA04 MB08 5K047 AA02 AA04 BB15 HH01 HH12 HH21 HH43 HH54 HH55 JJ07

Claims (2)

[Claims] 1. A frame packet signal transmitting apparatus for transmitting a frame packet signal in which frame synchronization information for establishing frame synchronization is defined at a frame cycle interval,
In a frame synchronization method for synchronizing with a frame synchronization processing device which reads frame synchronization information in the frame packet signal and performs a frame synchronization process, on the transmission side, the frame packet signal transmission device outputs A unique code value indicating the frame packet signal is set in the type information indicating the type of the defined packet signal, and the frame packet signal in which the unique code value is set is transmitted at a frame cycle interval. The synchronization processing device reads the type information of the frame packet signal, starts the frame synchronization process when a unique code value is received, and starts an error or error in the received packet signal when an undefined code value is received. Packet synchronization processing to judge that synchronization has occurred and immediately pull in a new packet Starting the frame synchronization. 2. A frame packet signal transmitting apparatus for transmitting a frame packet signal in which frame synchronization information for establishing frame synchronization is defined at a frame cycle interval,
In a frame synchronization method for synchronizing with a frame synchronization processing device that reads frame synchronization information in the frame packet signal and performs frame synchronization processing, the transmitting side converts the frame synchronization information into a frame by a frame packet signal transmission device. Defined at a predetermined fixed position in the packet signal, transmit the frame packet signal at frame period intervals, and, on the receiving side, a location where the frame synchronization information of the frame packet signal is arranged by the frame synchronization processing device. If the frame synchronization information is detected within the time until the frame synchronization process is started, and if the frame synchronization information is not detected within the time until the frame synchronization information of the frame packet signal is arranged, Judge that an error or erroneous synchronization of the received packet signal has occurred and immediately Frame synchronization method characterized by initiating a packet synchronization processing for drawing a packet.