Patent Application
20090190595
The present invention relates to the block coding technology in communication transmission, and in particular, to a method, system, and device for transmitting overhead information.
In a data communication network, block coding is generally used to determine the border of data processing, namely, the border of the bytes required for CPU processing, and differentiate the user load information from the control information. For example, the frame structures of a PDH signal, ATM signal, and packet-switching packets count as block frames. The frame of the E1 signal is a 32-byte block frame composed of 1 row and 32 columns, and an ATM signal is a block frame composed of 53 bytes.
The 64B/66B is a block coding mechanism widely applied to the high-speed data transmission process. The objectives are to determine the border of the data block, and provide control codes in the data stream. Currently, the 64B/66B is primarily applied in the 10G Ethernet, and is also applicable to the 100G Ethernet.
However, in the high-speed data transmission system with a rate such as 10 Gbps or even 100 Gbps, it is necessary to implement performance monitoring for the physical-layer information and transfer the fault information in the case of fault. An optional solution is to insert OAM information in the coding process for providing performance statistics and fault notification on the physical layer. When the OAM information on the physical layer is transmitted in the current high-speed data communication system, the physical-layer coding efficiency is reduced, the OAM information bandwidth is instable, and the detection functions implemented by the OAM information are limited.
Accordingly, a method for transmitting overhead information is provided in disclosed embodiments to improve the transmission performance of OAM information on the physical layer.
An overhead information transmission system and device are also provided in the disclosed embodiments to improve the transmission performance of OAM information on the physical layer.
In order to fulfill the foregoing objectives, the following technical solution is applied.
A method for sending overhead information includes:
encoding customer information composed of user information and user control information into a 64B/66B customer information code block;
encoding configured overhead information into a 64B/66B code block, and marking the code block as an overhead code block; and
sending the customer information code block and the overhead code block, where M of every N sent code blocks are overhead code blocks and M and N are positive integers and M is smaller than N.
An overhead information receiving method includes:
receiving 64B/66B code blocks;
identifying an overhead code block according to an identifier of the overhead code block, and extracting overhead information from the overhead code block; and
decoding customer information code blocks other than the overhead code blocks to obtain customer information.
An overhead information transmission system includes:
a sending device, adapted to: encode the customer information composed of user information and user control information into a 64B/66B customer information code block; encode configured overhead information into a 64B/66B code block, and mark the code block as an overhead code block; send the customer information code block and the overhead code block to a receiving device, where M of every N sent code blocks are overhead code blocks and M and N are positive integers and M is smaller than N; and
a receiving device, adapted to: receive the 64B/66B code block from the sending device; identify the overhead code block according to the identifier of the overhead code block and extract the overhead information from the overhead code block; and decode the customer information code blocks other than the overhead code blocks and obtain the customer information.
An overhead information sending device includes:
an overhead coding unit, adapted to: encode the configured overhead information into a 64B/66B code block, mark the code block as an overhead code block, and send the overhead code block to the sending unit;
a customer information coding unit, adapted to: encode the received customer information composed of user information and user control information into a 64B/66B customer information code block, and send the customer information code block to a sending unit; and
a sending unit, adapted to: receive the overhead code blocks of the overhead coding unit and the customer information code blocks of the customer information coding unit, and send the code blocks out, where M of every N sent 64B/66B code blocks are overhead code blocks and M and N are positive integers and M is smaller than N.
An overhead information receiving device includes:
a receiving unit, adapted to: receive a 64B/66B code block, and send the received code block to a code block type identifying unit;
a code block type identifying unit, adapted to: identify an overhead code block according to the identifier of the overhead code block, send the identified overhead code block to the overhead information extracting unit, and send customer information code blocks to the customer information decoding unit;
an overhead information extracting unit, adapted to: receive the overhead code block from the code block type identifying unit, and extract the overhead information from the overhead code block; and
a customer information decoding unit, adapted to decode the customer information code block received from the code block type identifying unit.
An overhead information transmission device includes:
a sending module, adapted to: encode the customer information composed of user information and user control information into a 64B/66B customer information code block; encode configured overhead information into a 64B/66B code block, and mark the code block as an overhead code block; send out the customer information code block and the overhead code block, where M of every N sent 64B/66B code blocks are overhead code blocks (M and N are positive integers and M is smaller than N); and
a receiving device, adapted to: receive the external 64B/66B code block; identify the overhead code block according to the identifier of the overhead code block and extract the overhead information from the overhead code block; and decode the customer information code blocks other than the overhead code blocks and obtain the customer information.
It can be seen from the above technical solution that, in the embodiments of the present disclosure, the configured overhead information is encoded into a 64B/66B code block, and the code block is marked as an overhead code block, at the time of sending overhead information. Through this marking mode, the receiver can identify the overhead code block in the code stream after receiving the code block, the overhead code blocks are sent together with the 64B/66B code blocks which carry customer information, where one of every N code blocks is an overhead code block. At the time of receiving overhead information, the overhead code blocks are identified according to the identifier of the overhead code block in the received code stream, and the overhead information is extracted. The customer information code blocks are decoded based on the 64B/66B, and the customer information is transmitted to the application layer for resolving.
In the disclosed embodiments, the capability of transferring the overhead information (including OAM information) is provided by inserting overhead blocks fixedly. By multiplexing the data and inserted overhead information (including OAM information) periodically, the insertion of the OAM information on the physical layer may be determined. Therefore, the data or OAM information may be identifiable on the physical layer through the timing relation, certain time and location relations can be obtained, and stable bandwidth of the overhead code blocks (including OAM information) may be provided. Moreover, because the size of the overhead code blocks is fixed, the performance detection function which is based on measuring information with a fixed length can also be performed normally, and the detection performance enabled by OAM information is not restricted. Because the lowest-layer code block carries the overhead information, the link detection data on the physical layer can be extracted without participation of the customer layer.
Furthermore, the value of N is flexibly adjustable so that the bandwidth occupied by the OAM information can be adjusted conveniently.
In order to make the technical solution, objectives and merits of the present invention clearer, a detailed description of the present invention is given below with reference to accompanying drawings and preferred embodiments.
Currently, OAM information is inserted into a high-speed data transmission system in three modes. Through thorough research, the inventor finds the following defects of the three modes:
Mode 1: A solution similar to the SDH is applied, the fixed overhead information is inserted into the transmission information with a fixed length, and the inserted overhead information is differentiated through the reserved 10B control code. However, the OAM information is carried in the modes based on the 8B/10B coding mechanism. Therefore, 10 bits are consumed for transferring every 8 bits of user data. Consequently, the coding efficiency is reduced and the bandwidth waste radio is up to 20%.
Mode 2: Some fields in the preamble of the Ethernet frame are changed to make the fields carry OAM information. As shown in
Mode 3: Part of the IFG (also known as Inter-Packet Gap, IPG) of the Ethernet frames carries the OAM information. As shown in
Besides, under the Ethernet asynchronous communication technology based on the statistic time division multiplexing, if the IFG or preamble is used as a substitute to transmit OAM information, especially, if the IFG is used as a substitute, the transmitted OAM information inherits the randomness of arrival of Ethernet frames. As a result, the insertion of OAM information on the physical layer is random, no certain timing or location relation exists between customer data, and the data and OAM information cannot be differentiated through the timing relation on the physical layer. Therefore, neither mode 2 nor mode 3 supports the OAM functions which require a timing relation between the OAM and the customer data.
In view of the foregoing problems, the embodiments of the present disclosure provide a method, system and device for transmitting overhead information.
Step 501: The customer information composed of user information and user control information is encoded into a 64B/66B code block. The configured overhead information is encoded into a 64B/66B code block, and this code block is marked as an overhead code block.
Step 502: The 64B/66B code blocks are sent, where M of N 64B/66B code blocks sent are overhead code blocks.
In this step, M and N are positive integers, and M is smaller than N. Accordingly,
Step 601: The 64B/66B code blocks are received.
Step 602: The overhead code blocks are identified according to the identifier of each overhead code block, overhead information is extracted from the overhead code blocks, and the customer information code blocks other than the overhead code blocks are decoded to obtain the customer information.
In the foregoing method for sending overhead information, the code blocks that carry the overhead information (namely, overhead code blocks) are marked in different modes: marking the overhead code blocks through a specified field, marking the overhead code blocks through integrity processing for the overhead information in the overhead code blocks, and marking the overhead code blocks through the location of each overhead code block in the code stream. Accordingly, the received overhead information is identified according to the specific identification mode of each overhead code block: identifying the overhead code block according to the contents of the specified field in the overhead code block, identifying the overhead code block by checking integrity of the information in the code block, and identifying the overhead code block according to the location of the overhead code block in the code stream.
Through the foregoing method for sending and receiving overhead information, the overhead information may be carried in the code blocks. The carried overhead information includes OAM information. In this way, a stable bandwidth utilization ratio of the OAM information is ensured, and the OAM information is obtained to implement performance detection of the physical-layer link without participation of the customer layer.
Embodiments of the present disclosure are elaborated below, where different identification modes are applied.
In this embodiment, an overhead code block is marked through a specified field in the code block.
Step 701: The customer information composed of user information and user control information are encoded into a 64B/66B code block, which is called “customer information code block”.
In this step, the mode of encoding the customer information into a code block is based on a 64B/66B coding mode.
Step 702: Overhead information is configured, and the generated overhead information is encoded to a 64B/66B code block, which is marked as an overhead code block.
In this step, the overhead code block is in a control block format, and a specified field in the control block format is used to mark the overhead code block. In this embodiment, a value of the specified block type field is used to indicate the overhead code block, for example, the value of the specified block type is 0x00 (Block Type Field=0x00). That is, in this embodiment, an overhead code block is marked by setting the block type field in the overhead code block to a specified value.
The specific overhead information is input to a location next to the block type field in the code block payload. There are a total of 56 bits for carrying overhead information. Table 1 shows the specific coding rules, which cover the overhead code blocks and customer information code blocks, with the block type field of the overhead code block being set to 0x00. Alternatively, another value may be selected to mark the overhead code block only if the selected value is different from the value of the block type field of the user information. The overhead code block may further include other information such as Error Check Code (ECC) of the overhead information.
Step 703: The code blocks are sent, where M of every N sent code blocks are overhead code blocks, and M is smaller than N.
In this step, the values of M and N may be selected as required only if M is smaller than N. Because M of every N sent code blocks are overhead code blocks, the bandwidth occupied by the overhead code blocks is M/N. Once M and N are determined, the bandwidth occupied by the overhead information remains stable and unchanged. By adjusting M and N, the bandwidth occupied by the overhead code blocks may be adjusted conveniently.
Now the process of inserting overhead information in this embodiment ends. In the foregoing process, step 701 and step 702 are not sequence-sensitive. That is, step 702 may also be performed before step 701 or the two steps are performed concurrently.
In the foregoing step 702, if the overhead information block is marked through a specified field, the block is marked by specifying a value of the block type field. In this mode, there are a total of 56 bits for carrying overhead information. Because the check on the overhead information generally requires an additional error code, the available fields are relatively few. In order to improve the use efficiency, the block type field may be changed in this way: In the 8-bit block type field, the bit closest to the 2-bit synchronization code may be used to distinguish the overhead code block from the customer information code block. If this bit is 0, the block is an overhead code block; if this bit is 1, the block is a customer information code block. That is, the first bit of the block type field is used to mark the overhead information block. In this case, according to 64B/66B coding rules, the block type field of such customer information code blocks may be re-defined if the first bit in the block type field of some customer information code blocks is 0. For example, the coding format shown in Table 2 may apply.
Once the overhead code block is marked by the first bit in the block type field, all the 63 bits starting from the second bit in the block type field of the code block are used to carry overhead information. Therefore, more content information and ECCs may be carried.
Corresponding to the mode of sending overhead code blocks in this embodiment,
Step 801: The 64B/66B code block streams are received.
Step 802: The overhead code block in the code stream is identified, and the overhead information is extracted from the overhead code block.
Corresponding to the mode of marking the overhead code block in step 702 in
Specifically, if the mode of marking the overhead code block is that a specified field in the control block format whose synchronization code is 10 is used to mark the overhead code block, the mode of identifying the overhead code blocks in this step is: If the synchronization code is 10 (namely, the code block is in the control block format) and the value of the block type field is a specific value indicative of an overhead code block, the code block is determined as an overhead code block. For example, at the time of sending overhead information, if the block type field in the overhead code block is 0x00, the control code block with a block type field set to 0x00 in this step is determined as an overhead code block. The mode of extracting overhead information is: The contents carried in the 56 bits subsequent to the block type field are extracted as overhead information.
Alternatively, if the overhead code block is marked through a control block format with a synchronization code “10”, and the “0” value of the first bit after the synchronization code represents overhead code blocks, the mode of identifying the overhead code block is: If the synchronization code is “10”, and the first bit of the block type field is “0”, the code block is determined as an overhead code block. In this case, the mode of extracting overhead information is: The contents carried in the 63 bits starting from the second bit of the block type field are extracted as overhead information.
If the overhead code block includes other information such as ECC, after the overhead information is extracted, the extracted overhead information may further undergo an error check to ensure reliability of the overhead information.
Step 803: The customer information code blocks in the code stream are decoded to obtain customer information.
Now the process of extracting overhead information ends. The extracted overhead information may be sent to the corresponding overhead function processing unit for processing, so as to know the performance information of the physical layer and implement performance statistics and fault notification of the physical layer. The decoded customer information may be sent to the upper-layer customer information processing unit for processing.
The sending device 910 represents the overhead information sending device provided in this embodiment.
The receiving device 920 represents the overhead information receiving device provided in this embodiment.
The sending device 910 includes: an overhead coding unit 911, a customer information coding unit 912, and a sending unit 913.
The receiving device 920 includes: a receiving unit 921, a code block type identifying unit 922, an overhead information extracting unit 923, and a customer information decoding unit 924.
In this system, the overhead coding unit 911 in the sending device 910 is adapted to: encode the configured overhead information into a 64B/66B code block, mark the code block as an overhead code block, and send the overhead code block to the sending unit 913.
The customer information coding unit 912 in the sending device 910 is adapted to: encode the received user information and user control information into a 64B/66B code block which is called “customer information code block”, and send the customer information code block to the sending unit 913.
The sending unit 913 in the sending device 910 is adapted to: receive the overhead code blocks of the overhead coding unit 911 and the customer information code blocks of the customer information coding unit 912, and send the code blocks to the receiving unit 921 in the receiving device 920, where M of every N sent 64B/66B code blocks are overhead code blocks (M and N are positive integers and M is smaller than N).
The receiving unit 921 in the receiving device 920 is adapted to: receive the 64B/66B code block sent by the sending unit 911 in the sending device 910, and send the received code block to the code block type identifying unit 922.
The code block type identifying unit 922 is adapted to: identify the overhead code block according to the identifier of the overhead code block, send the identified overhead code block to the overhead information extracting unit 923, and send customer information code blocks to the customer information decoding unit 924.
The overhead information extracting unit 923 is adapted to: receive the overhead code block from the code block type identifying unit 922, and extract the overhead information from the overhead code block.
The customer information decoding unit 924 is adapted to decode the customer information code block received from the code block type identifying unit 922.
In the foregoing overhead information transmission system, the sending device may generate an overhead code block, insert the overhead code block into the 64B/66B code stream, and send it to the receiving device through the network. The receiving device identifies the overhead code block in the corresponding mode, and extracts the overhead information. In the overhead information transmission system, device B in the system performs the function of receiving the overhead information once a device at any side of the system sends or receives the overhead information. For example, device A in the system performs the function of sending the overhead information. In this way, the transmission of the generated overhead information in the transmission system is unidirectional. That is, the transmission is from device A to device B.
After the device at either side in the system incorporates the function of the peer, the function of sending and receiving overhead information can be performed between both sides of the system. For example, device A may send overhead information to device B, and may also receive overhead information from device B and extract the overhead information. Likewise, device B may receive overhead information from device A and extract the overhead information, and may also send overhead information to device A.
The overhead information transmission device for implementing the foregoing function is also provided in this embodiment. The device includes a sending module and a receiving module, and implements both sending and receiving of overhead information.
In this device, the sending module is adapted to: encode the customer information composed of user information and user control information into a 64B/66B customer information code block; encode configured overhead information into a 64B/66B code block, and mark the code block as an overhead code block; and send out the customer information code block and the overhead code block, where M of every N sent 64B/66B code blocks are overhead code blocks (M and N are positive integers and M is smaller than N).
The receiving device is adapted to: receive the external 64B/66B code block; identify the overhead code block according to the identifier of the overhead code block and extract the overhead information from the overhead code block; and decode the customer information code blocks other than the overhead code blocks and obtain the customer information.
Specifically, the structures of the sending module and receiving module may have similar internal structures of the sending module and receiving module in the foregoing transmission overhead information system.
Some differences in the structures may include, for example, that the sending unit in the sending module sends the generated customer information code blocks and overhead code blocks to the outside, whereas the receiving unit in the receiving module receives customer information code blocks and overhead code blocks from the outside, as not detailed here any further.
After the foregoing transmission overhead information devices constitute the devices at both sides, the overhead information in the system can be transmitted in both directions.
In this embodiment, an overhead code block is marked through integrity processing in the overhead code block.
The operation procedure in this embodiment is the same as the operation procedure shown in
Table 3 shows the coding rules in this embodiment. As shown in Table 3, the synchronization code of the overhead code block is “10” in order to reduce the probability of algorithm conflict. The overhead information and other optional information occupy 48 bits, and the remaining 16 bits are calculated out according to the CRC16 algorithm. The data in other code blocks is random, and the probability that the data exactly meets the integrity processing requirement is very low.
Nevertheless, the value of the synchronization code in the overhead code block may also be the same as the value of the data code block, namely, “01”. The value of the code block payload in the data code block is completely random, the probability of meeting the integrity algorithm is high, and the transmission amount of the data code block may be high, so the aggregate which meets the integrity algorithm is greater. Therefore, may not be desirable to set the synchronization code of the overhead code block to “01”.
Described above is a method for inserting overhead information in this embodiment. Corresponding to the above method embodiment, the general operation procedure in the case of extracting overhead information is the same as the operation procedure shown in
In the foregoing mode, the mode of encoding the customer information code block is not changed. In order to further reduce the probability of conflict, two values may be defined for each block type. If the combination of the block type selected first and the subsequent user information meets the integrity algorithm exactly, the second block type may be selected.
Correspondingly, the receiver identifies the overhead code block still by checking whether the code block complies with the integrity algorithm, and the code block which complies with the integrity algorithm is an overhead code block. The user information is decoded according to the rules about the block type field in Table 4.
The system, sending device, receiving device, and overhead information transmission device in the first embodiment are also applicable to the overhead information transmission system for implementing the method in the second embodiment.
As regards the coding mode of code blocks in this embodiment, because integrity check is added, the transmission reliability of the overhead code block may be more certain, and the link performance and fault indication reflected by the overhead code block may be more credible.
In this embodiment, an overhead code block is marked through the location of the overhead code block in the code stream.
Step 1001: Customer information is encoded into a 64B/66B code block, and a customer information code block is generated.
Step 1002: Overhead information is configured, and the generated overhead information is encoded into a 64B/66B code block.
In this step, the overhead code block does not necessarily have a synchronization code, and all 66 bits are used to indicate the overhead information. If permitted, a check bit and other information may be added.
Step 1003: M overhead code blocks and (N−M) customer information code blocks are combined into a major block, the overhead code block is set into a fixed location of the major block, and integrity information is added into the major block and sending it out.
In this step, the overhead code block may be identified in this way: M overhead code blocks and (N−M) customer information code blocks are combined into a major block, and the overhead code block is identified through the fixed location in the major block, where M and N are positive integers and M is smaller than N. That is, the overhead code block may be in the fixed location in the major block, and may be the first, intermediate, or last code block.
The integrity information added into the major block may be Forward Error Correction (FEC) information. Meanwhile, depending on the specific integrity algorithm, the calculated integrity information may be distributed in the whole major block, or appended as a whole to the major block.
Now the process of inserting overhead information in this embodiment ends. Step 1001 and step 1002 may be performed concurrently, or step 1002 is performed before step 1001. Corresponding to the method for sending overhead information in
Step 1101: The major block carried in the received code stream is delimited through an integrity algorithm.
Step 1102: The code block in the specified location in each major block is determined as an overhead code block, and the overhead information is extracted.
Corresponding to the mode of marking the overhead code block in
Step 1103: Other code blocks in the major block are decoded to obtain customer information.
Now the process of extracting overhead information in this embodiment ends. Step 1102 and step 1103 may be performed concurrently, or step 1103 is performed before step 1102.
Through the method in this embodiment, an overhead code block may use all the 66 bits to carry overhead information so that more overhead information contents can be carried in a code block. By adding check information into the overhead code block, the transmission reliability of overhead information is further ensured. Likewise, the method in this embodiment may be implemented in the overhead information transmission system and overhead information transmission device in the first embodiment.
Through the foregoing description about the method, system and device for transmitting overhead information in the embodiments of the present disclosure, it can be seen that, because the data and inserted overhead information (including OAM information) are multiplexed periodically, the data or OAM information is surely identifiable on the physical layer through the timing relation, and certain time and location relations can be obtained. Moreover, stable bandwidth of the overhead code block (including OAM information) is ensured, and the performance detection function which needs measuring of the information with a fixed length can also be performed normally, and the detection performance enabled by OAM information is not restricted. In a word, the transmission performance of the OAM information is improved.
Although the invention has been described through several preferred embodiments, the invention is not limited to such embodiments. It is apparent that those skilled in the art can make various modifications and variations to the invention without departing from the spirit and scope of the invention. The invention is intended to cover the modifications and variations provided that they fall in the scope of protection defined by the following claims or their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200710000244.X | Jan 2007 | CN | national |
This application is a continuation of international application number PCT/CN2008/070080, filed on Jan. 10, 2008, which claims the benefit of priority from the Chinese Patent Application No. 200710000244.X, filed with the Chinese Patent Office on Jan. 16, 2007, both of which are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2008/070080 | Jan 2008 | US |
| Child | 12417867 | US |
