Title of Invention

METHOD, DEVICE AND APPLICATION EQUIPMENT FOR TRANSMITTING DYNAMIC SYNCHRONOUS TRANSFER MODE ON OPTICAL TRANSMISSION NET

Abstract

The present invention relates to the technical field of an optical transport network (OTN), and discloses a method for transmitting a dynamic synchronous transfer mode (DTM) on an OTN. Firstly, a client signal adapted to a time-slot rate of a specified DTM is mapped to a corresponding time-slot position in an intermediate data frame, and a signal in a format of the intermediate data frame is generated. The intermediate data frame has a repetition period identical to that of a DTM frame, and a rate identical to that of a payload area in an OTN frame. Next, the signal in a format of the intermediate data frame is mapped to the OTN frame. Further, the present invention also discloses a device; for transmitting a DTM on an OTN, an optical cross-connect (OXC) equipment, and an optical add/drop multiplexer (OADM) adopting the above mapping device. The method of mapping a DTM to an OTN provided by the present invention saves the cost compared with a conventional method for mapping a DTM to an OTN through an intermediate data frame.

Full Text

This application claims priority to Chinese Patent Application No. 200610059336.0 entitled "Method and Device for Mapping DTM to OTN" and filed on March 3, 2006 with the State Intellectual Property Office of the PRC, the disclosure of which is incorporated herein by reference in its entirety. FIELD OF THE INVENTION The present invention relates to an optical transmission net (OTN) technology, and more particularly, to a method, device, and application equipment for transmitting a dynamic synchronous transfer mode (DTM) on an OTN. BACKGROUND The next generation network requires high-efficient transmission and performance monitoring capability as well as optimal availability and survivability. Synchronous optical network/synchronous digital hierarchy (SONET/SDH) has its own advantages in time division multiplexing (TDM)-based services, and plays an important role in metropolitan area networks (MANs). However, due to various limitations, it is difficult for SONET/SDH to satisfy the requirements of a current metropolitan OTN along with the continuous development of the Internet and data services. Therefore, a new network solution is needed to satisfy the requirements of network expandability and manageability. An International Telecommunications Union-Telecommunications Standardization Section (ITU-T) G709-based OTN emerges as required. G709 is focused on digital wrapper. The digital wrapper constructs a particular frame format to wrap a client signal into a payload unit of a frame, and provides overhead (OH) bytes for operation, administration, maintenance, and provisioning (OAM&P) at the frame header, and forward error correction (FEC) bytes at the frame frailer. The digital wrapper may support OH of an optical channel layer of a client signal, take regeneration requirements of the optical channel into full consideration, and support the transmission of channel-associated OH as well as the convenience of the access of various services, so that the problem of monitoring performance in the OTN is easily solved. In addition, the introduction of the FEC technology may effectively improve the performance of error rate of the client signal, reduce the demand of an optical network on photoelecfric conversion, and further significantly lower the network construction cost. Figure 1 is a structural diagram of a format of an OTN standard frame. It can be seen that the OTN standard frame is in a format of 4 rows and 4080 columns. The 16 columns at the header are OH bytes, the 255 columns at the trailer are FEC check bytes, and the middle 3808 columns are payload. Among the OH bytes at the header, the 1st to 7th columns of the first row are frame alignment signals (FAS). The 8th to 14th bytes are OH bytes of an optical channel transport unit-K (OTUK), in which different values of K are corresponding to transmission modes of different rates. The lst to 14th columns of the 2nd to 4th rows are OH bytes of an optical channel data unit-K (ODUK). The 15th to 16th columns are OH bytes of an optical channel payload unit-K (OPUK). The 7th byte of the FAS is a multi-frame alignment signal (MFAS) configured to indicate OH allocation when multiple user service signals are carried by means of TDM. The OTUK OH bytes provide a function for monitoring signal transmission states between Reamplification, Reshaping, and Retiming (3R) regeneration nodes in the OTN, including three parts, namely, OH bytes of section monitoring (SM), OH bytes of communication channels between general communication channel-0 (GCCO) terminals, and bytes reserved for future international standardization (RES). The ODUK OH provides cascade connection monitoring, end-to-end channel monitoring, and client signal adaptation through OPUK. The ODUK provides abundant OH bytes (the 1st to 14th columns of the 2nd to 4th rows) to fulfill the above functions, including path monitoring (PM) OH, tandem connection monitoring (TCM) OH, general communication channel (GCC) bytes GCCl and GCC2 OH, auto-protection switching & protection control channel (APS/PCC) OH bytes, fault type fault location (FTFL) information, and experiment (EXP) OH bytes. The OPUK is composed of payload (OPU) mapped by the client signal and the specific overhead (OPU OH) of the OPUK. The OH bytes include payload structure identifier (PSI), adjustment bytes, and mapping specific overhead. The PSI is respectively corresponding to 0-255 probable values under the MFAS instruction, in which the 0* byte is a client signal payload type (PT), and the others are reserved (RES) bytes for fiiture expansion. Currently, a client signal can be mapped into the OTN in the following three modes: (1) constant bit rate (CBR) like CBR2G5, CBR10G, and CBR40G by which signals are mapped into the OPUK; (2) asynchronous transfer mode (ATM) by which signals are mapped into the OPUK (ATM cells are multiplexed into a constant bit stream matching the payload capacity of the OPUK, so as to be mapped into the OPUK, and during the multiplexing, the rate is adjusted by inserting idle cells or discarding cells); and (3) general framing procedure (GFP) by which frame signals are mapped into the OPUK (the mapping of GFP frames achieves a continuous bit stream matching the OPUK by inserting idle frames in the packaging stage). In addition, other signals, such as client signals, test signals, and bit stream signals of common clients, may also be mapped into the OPUK. However, for some special services, such as dynamic synchronous transfer mode (DTM) services, the OTN is unable to map and transparently transmit the DTM services at present. The DTM service is a transmission technology of ETSI standard capable of providing high-quality transmission. Combining the TDM exchange technology and the PACKET exchange technology, the DTM service overcomes the disadvantages that a PACKET network needs a large buffer and cannot guarantee the quality of service (QoS) of real-time services, and possesses the QoS capability of the TDM and the dynamic bandwidth allocation capability of the PACKET network. Meanwhile, the DTM service supports the transmission of real-time broadband services, various data services, video services, and TDM services, provides multicast capability, and achieves maximal transmission capacity while requiring little OH. The DTM can compete with Ethernet transport network (ETN) in function and performance. In addition to the dynamic bandwidth capability like the ETN, the DTM can further transmit real-time services such as TDM with high quality. The DTM combines simple and non-blocking attributes and capability of supporting real-time communication in the circuit switching technology with dynamic resource processing attributes in the PACKET exchange technology, so as to construct a high-capacity transport network with dynamic resource allocation by integrating advantages of synchronous and asynchronous medium access modes. Substantially, the DTM is a circuit switching method of the TDM. Therefore, the network may match the change in flow and allocate bandwidth between two nodes upon requirements. The DTM adopts a frame structure similar to SDH/SONET, and expands the resource dynamic reallocation to the DTM. Compared to SDH/SONET, the DTM may establish circuits or channels of various rates according to requirements, and the channel capacity may vary with the flow characteristic in operation. As the resource allocation between nodes in an annular or bus structure is changeable, unused resources will be allocated to nodes with higher requirements, thus forming an autonomous and highly efficient dynamic infrastructure. In addition, the DTM, just like the ATM, has an important characteristic of providing multi-channel interfaces. The DTM is based on TDM technology. Therefore, the transmission capacity of any fiber channel is divided into minute time units. The total channel capacity is divided into frames with a fixed size of 125 μs, and each frame is subdivided into time-slots of 64 bits. Each frame has a specific number of time-slots depending on the bit rate (bit stream). For example, as for a bit stream of 2 Gbps, each frame has about 3900 (2xl09xl25x10-6/64) time-slots. If a frame length of 125 μs and a time-slot of 64 bits are adopted, the transmission of digital audio and plesiochronous digital hierarchy can be simply adjusted. The time-slots in each frame may be classified into digital slots and control slots. At any time point, a time-slot is either a digital slot or a control slot. If necessary, a digital slot may be converted into a control slot. Privileges of writing the digital slots and control slots are distributed on each node of the channel. The DTM frame structure is different from the frame structure in a conventional TDM system. Referring to Figure 2, a schematic diagram of a DTM frame structure is shown. The DTM frame has a start-of-frame identifier (SOF ID) followed by digital time-slots, and intervals composed of some filling patterns at the end of the frame, so as to ensure the receiving terminal to achieve clock recovery successfully. The frame length is 125 μs, and the repetition frequency is 8 KHz. ndata represents the number of the time-slots, and felow and fehigh respectively indicate the upper and lower limit of errors of the frame. At present, the DTM has plenty of standards issued by ETSI, including physical layer protocols, and standards of mapping the DTM frame to the SDH virtual container (VC), the SDH to the DTM and mapping the MPLS to the DTM. However, details about the mapping between the DTM and OTN have not been released. In the prior art, in order to realize the mapping from the DTM to OTN, the DTM must be firstly mapped OVER to the SDH VC and then to the OTN. It is a standard already established by the ETSI to map the DTM to the SDH. Figure 3 is a schematic diagram of DTM allocation in a VC4/VC4-XC according to the prior art. It can be seen from FIG 3 that, the first part is an OH area, the second part is a fixed insertion area, and the third part is a DTM time-slot area. As for one VC4, there are 32x9 288 DTM time-slots. Figure 4 is a schematic diagram of mapping a DTM time-slot to an SDH VC4 according to the prior art. As shown in Figure. 4, a time-slot of the DTM in VC4 is 65 bits. S bit is a specific identification bit. When the S bit is 0, data is transmitted, and when the S bit is 1, other status information, such as alarm indication signal (AIS), IDLE, and performmice monitoring information is transmitted. Since a time-slot is composed of 65 bits, the S bit aligns with the start position of the byte after every 8 time-slots. As for the synchronization of the DTM time-slots, the first data byte in each row of the VC is a synchronous starting point. The conventional method of mapping the DTM to SDH and then to the OTN comprises the following steps. 1) Dividing VC4 time-slots, and adopting 65BIT as a digital time-slot. 64BIT is a digital bit, and 1 bit is a control bit. Each row has 32 time-slots in total. 2) Receiving a tributary DTM data stream, removing 8B/10B line coding, and restoring a DTM frame. 3) Respectively mapping the restored DTM data time-slots to the DTM time-slots divided by the VC4, then mapping the 64 bits of the data time-slots to the corresponding 64BIT data positions in the DTM time-slots, and setting and writing each S bit into the corresponding S bit position. 4) Setting the first column in the pay load area of the VC4 as fixed insertion bytes. 5) Distinguishing the time-slot boundary by realizing synchronization with the first data byte in each row, finding the starting point of the first data time-slot, and sequentially setting each 65BIT as a DTM time-slot position. 6) Forming a complete synchronous transport module-n (STM-N) signal and mapping the STM -N to the OTN. Figure 5 is a structural diagram of mapping the DTM to a trans-multiplexing (TMUX) device in the OTN through an SDH layer according to the prior art. The client signal, for example, a gigabit Ethernet (GE)/fast Ethernet (FE)/enterprise system connection (ESCON), or TDM, is adapted to an SDH VC through an adaptation protocol. The SDH VC is then multiplexed to an STM-N format, and the STM-N further maps the ODUK and OTUK in the OTN to be transmitted on the OTN. The prior art of mapping the DTM to the SDH and then to the OTN has the following disadvantages. 1) The bandwidth utilization ratio is not high. In order to be transmitted on the OTN, the DTM needs to be mapped to the SDH and then to the OTN, so that each layer occupies too much OH. 2) An SDH layer is added, and the process on the SDH is relatively complicated. Thereby, it is difficult to realize the whole design, and the hardware cost is high. 3) The advantage that the DTM may make full use of the fiber bandwidth cannot be accomplished. In view of the above, since the prior art of mapping the DTM to SDH and then to the OTN is high in cost and low in bandwidth utilization ratio, those skilled in the art are eager to put forward a technology of mapping the DTM to OTN at a low cost and with a high bandwidth utilization ratio. However, the DTM frame structure is a frame structure with 125 μs as a period, and the number of the time-slots is associated with a line rate. The OTN frame structure, for example, the ODUK (including ODU OH and OPUK), is a 3824x4 modularized frame structure independent of the line rate. The period of ODUK at different levels varies with the level. For example, the frame period of the ODUl is four times longer than that of the 0DU2, but the structure thereof still has 3824x4 bytes. Therefore, the time-slots of the DTM cannot be directly mapped to the time-slots or bytes of the ODUK, and the technology of mapping the DTM to the SDH cannot be applied to the OTN. SUMMARY Accordingly, the present invention is directed to a method, a mapping device, and an application equipment for transmitting a dynamic synchronous transfer mode (DTM) on an optical fransport network (OTN), so as to achieve the mapping from the DTM to the OTN while saving the cost. In an embodiment of the present invention, a method for transmitting a DTM on an OTN is provided. The method includes the following steps. A client signal adapted to a time-slot rate of a specified DTM is mapped to a corresponding time-slot position in an intermediate data frame, and a signal in a format of the intennediate data frame is generated. The intermediate data frame has a repetition period identical to that of a DTM frame, and a rate identical to that of a payload area in an OTN frame. Afterward, the signal in the format of the intermediate data frame is mapped to the OTN frame. In another embodiment of the present invention, a device for transmitting a DTM on an OTN is provided, including an adaptation module, an intermediate data frame module, and an OTN line processing module. The adaptation module is configured to mlapt a client signal to a specified DTM time-slot rate. The intermediate data frame module is configured to map the client signal adapted by the adaptation module to a corresponding time-slot position in the intermediate data frame so as to generate a signal in a format of the intermediate data frame. The intermediate data frame has a repetition period identical to that of a DTM frame, and a rate identical to that of a payload area in an OTN frame. The OTN line processing module is configured to map the signal in the format of the intermediate data frame to the OTN frame. In another embodiment of the present invention, an optical cross-connect (OXC) equipment is provided. The OXC equipment includes a wavelength multiplexer, a wavelength demultiplexer, and a device coupled to the wavelength multiplexer and the wavelength demultiplexer for transmitting a DTM on an OTN. An output signal of the device is an input signal of the wavelength multiplexer, and an output signal of the wavelength demultiplexer is an input signal of the mapping device. In another embodiment of the present invention, an optical add/drop multiplexer (OADM) is provided. The OADM includes a wavelength multiplexing/demultiplexing module and an OADM module coupled to each other, and a device coupled to the wavelength multiplexing/demultiplexing module for transmitting a DTM on an OTN. An output signal of the device is an input signal of the wavelength multiplexing/demultiplexing module, and a reverse output signal of the wavelength multiplexing/demultiplexing module is a reverse input signal of the device. According to the aforementioned technical solutions, in the embodiments of the present invention, a DTM is mapped to an OTN by adopting an intermediate data frame having a repetition period identical to that of a DTM frame and a rate identical to that of a payload area in an OTN frame as a mapping medium. The intermediate data frame is simpler than the conventional SDH VC frame both in structure and physical realization, thus saving the cost. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic diagram of an OTN frame structure according to the prior art; Figure 2 is a schematic diagram of a DTM frame structure according to the prior art; Figure 3 is a schematic diagram of DTM allocation in a VC4/VC4-XC according to the prior art; Figure 4 is a schematic diagram of mapping a DTM time-slot to an SDH VC4 according to the prior art; Figure 5 is a schematic diagram of the structure of a TMUX device according to the prior art; Figure 6 is a schematic diagram of a frame structure in a row of an OPTUK according to an embodiment of the present invention; Figure 7 is a schematic diagram of a modularized frame structure of an OPTUl according to an embodiment of the present invention; Figure 8 is a schematic structural diagram of mapping a DTM to a TMUX of an OTN according to an embodiment of the present invention; Figure 9 is a schematic structural diagram of mapping a DTM to an OXC device of an OTN according to another embodiment of the present invention; and Figure 10 is a schematic structural diagram of mapping a DTM to an OADM device of an OTN according to another embodiment of the present invention. DETAILED DESCRIPTION Embodiments of the present invention are illustrated in detail below with reference to the accompanied drawings. Since the ODUK frame structure and the DTM frame structure are two different frame structures, the prior art cannot directly map a DTM time-slot to an ODUK time-slot or byte. The present invention solves the above problem that two frame formats cannot directly match each other by an intermediate data frame structure (or an intermediate sub-layer) of a modularized frame structure with a DTM format different from the OTN. Thereby, an ODUK is adopted as a line rate of the DTM to realize a direct mapping from the DTM to the OTN. Embodiment 1 Firstly, a method for transmitting a DTM on an OTN provided by the present invention is described in this embodiment. The intermediate data frame structure in this embodiment of the present invention is an optical channel payload tributary unit-K (OPTUK) frame structure. The OPTUK frame structure needs a repetition period of 125 μs (the same as the repetition period of the DTM frame), i.e., a repetition frequency is 8 KHz. The OPTUK frame structure has a rate identical to that of an optical channel payload unit (OPUK). Different K values are corresponding to varied nominal bit rates. For example, the nominal bit rate of an OPTUl is the rate of STM-16, the nominal bit rate of an 0PTU2 is the rate of STM-64, and the nominal bit rate of an OPTUS is the rate of STM-256. Figure 6 is a diagram of a frame structure in one row of the OPTUK in this embodiment, and Figure 7 is a schematic diagram of a modularized frame structure of the OPTUl according to the present invention. The modularized frame structure in Figure 7 includes 9 rows of the frame shown in Figure 6. As shown in the figure, the OPTUK data frame structure includes a frame alignment identifier and a payload area, and the time-slot is divided by a unit of 64 bits (i.e., the size of the time-slot of the DTM). For example, the OPTUl data frame has 9 rows and 270x16 columns with a size of 16x270x9 bytes and at a rate of 16*270x9x8x8 kBIT/s=2488.32 MBIT/S. The OPTUl has all-together (16x270x9x8)/64=4860 DTM time-slots corresponding to 4860/9 540 time-slots in each row. In the 4860 time-slots, N time-slots are designated as OH time-slots, one time-slot among the N time-slots functions for frame synchronization, the bits of N-1 time-slots serve as control bits, and the total bit number of the N-I frame slots is larger than or equal to the number of 4860-N time-slots. These control bits are configured to indicate the state of each time-slot, for example, whether a time-slot is a data time-slot or a control time-slot. The control time-slots further include idle time-slots, performance monitoring time-slots, and AIS time-slots. This embodiment is different from the DTM mapping to VC in that the DTM time-slot in the VC has 65 bits, and the S bit is a control bit; while in this solution, the control bit is concentrated in N-1 OH time-slots, and the time-slot has 64 bits, so that it is unnecessary to search for the time-slot position when the bytes are synchronous. In this embodiment, the method for transmitting a DTM on an OTN includes the following steps. a. Constructing an intermediate adaptation entity OPTUK. The adaptation entity has 9 lines and 270 columns, and has a size of Xx270x9 bytes (X represents a nominal bit rate of the OPTUK). The entity further has a period of 125 μs, and a repetition frequency of 8 KBIT/S. When K=l, the rate of the OPTUl is the nominal bit rate of the STM-16, and the volume of the entity is 16x270x9 bytes; likewise, the rate of the OPTU2 is the nominal bit rate of the STM-64, and the volume of the entity is 64x270x9 bytes. b. Dividing the time-slots for the OPTUK by a unit of 64 bits. For example, 4860 time-slots are divided for the OPTUl, and the rate of each time-slot is 512 KBIT/S. c. Mapping the received data frame to the corresponding time-slot. The data frames may be Ethernet frames, MPLS frames, or TDM frames. Since the DTM time-slots are allocated according to the original rate of the client signal, the total rate related to the number of the DTM time-slots is larger than the rate of the corresponding client signal. d. Setting OH time-slots, including frame synchronous time-slots and control time-slots. The frame synchronous time-slots may also be frame alignment bytes with a fixed format, for example, the same as the bytes of F6 and 28, or indication bytes and check bytes, for example, in the same synchronous mode as the GFP. e. Transparently mapping the OPTUK frame to the ODUK at the same level. For example, mapping the OPTUl to the ODUl, or mapping the OPTU2 to the 0DU2, and then adapting the ODUK to the OTUK so as to be transmitted on the line. The line may be a single-wavelength line or a multi-wavelength line. The process of the above embodiment can be concluded as follows. First, the client signal adapted to a specified DTM time-slot rate is mapped to the corresponding time-slot position of an OPTUK frame (an intermediate data frame). The OPTUK frame has a repetition period identical to that of the DTM frame, and has a rate identical to that of a payload area in the OTN frame. Secondly, a signal in a format of the OPTUK frame is mapped to the OTN frame. More specifically, the signal in the format of the OPTUK is mapped to the ODUK, so as to generate an ODUK signal, and the ODUK signal is packaged into the signal in the OTUK format. Thereby, the mapping from the DTM to the OTN is completed. It should be noted that the time-slots in the OPTUK frame may not only be divided by a unit completely the same (for example, 64 bits) as the time-slots in the DTM frame, but also may be slightly larger than the time-slot division unit in the DTM frame. For example, in the OPTUK frame, the time-slots are divided by a unit of 65 bits. Compared with the conventional method for mapping to the OTN throgh the SDH layer, the present invention replaces the SDH layer with the OPTUK layer in a DTM format, thereby not only saving the cost and enhancing the broadband utilization ratio, but also discarding the complicated process of the SDH layer, to the prior art, the VC only has several fixed rates, such as VC12 for the transmission of 2 M and VC4 for the transmission of 140 M. to this manner, even if the DTM is OVER to the VC, it is still limited by the VC specific rates. When the transmitted client rate is larger than one VC, the process becomes complicated. In an embodiment of the present invention, since the rate of the OPTUK frame is high (for example, several G), and the particle is small (the size of one DTM time-slot is about 512 Kbps), this embodiment is applicable to signal transmission at wider client rates, for example, 200 M and 1.5 G/2 G (as the DTM time-slots are directly divided at the rate of close to the STM-N). The aforementioned method solves the technical problem that the DTM cannot be directly adopted in the OPUK of the common OTN. Thereby, through such an intermediate sub-layer, the method may not only be well applicable to various services, but also conveniently adapt for the OPUK. In this way, the application raige of the OTN is expanded, and the bandwidth utilization and client access of the OTN become more flexible. The above embodiment of the method of the present invention may be implemented through different devices, and examples of the devices of mapping the DTM to the OTN according to the present invention are illustrated as follows. Embodiment 2 Figure 8 is a schematic structural diagram of mapping a DTM to a TMUX of an OTN according to an embodiment of the present invention. It is a transparent DTM TMUX structure for realizing all services being transmitted transparently. No matter data services, video service, or conventional TDM services all can be transmitted transparently. Both MAC transparency and bit transparency may be realized for the data services. As shown in Figure 8, the TMUX includes an adaptation module, an OPTUK module, and an OTN line processing module. The adaptation module is configured to finish the processing of a physical layer of the client signal in a transmitting direction, and adapt the client signal to a DTM time-slot rate with a specified capacity. Various data services, after the processing of the physical layer and the adaptation of the GFP or other adaptation protocols, obtain a rate equal to that of a specified number of DTM time-slots. For example, GE services achieve a rate of about 1 G after the GEP adaptation, and may satisfy the MAC transparent transmission of GE by specifying about 2000 DTM time-slots. Or, after the rate adjustment, each TDM service has a rate equal to a specified number of the DTM time-slots. For example, the STM-1 signal may designate 305 DTM time-slots for transmission. The TDM rate adjustment may employ one DTM time-slot for management, and this time-slot is an adjustment control time-slot, including positive adjustment control, negative adjustment control, and negative adjustment opportunity. Definitely, under special circumstances, if the data services also require bit transparency, the processing mode is the same as the TDM service. The adaptation module implements functions in a receiving direction opposite to those of the transmitting direction, so as to restore the format signal packaged by the adaptation protocol to the original format of the client signal. The OPTUK module is configured to map all the signals adapted by the adaptation module to a specified DTM time-slot position of the OPTUK. The DTM time-slot is multiplexed by mapping the adapted signals to the specified time-slots. For example, the GE, after adapted by the GFP, occupies about 2000 DTM time-slots, an ESCON signal, after adapted by the GFP, occupies 400 DTM time-slots, and all other client signals after adaptation take up the rest DTM time-slots. The DTM time-slots occupy the whole space of the OPTUK, thus realizing the DTM multiplexing function of each client signal. After the multiplexing, the signal in the OPTUK format is transmitted to an ODUK terminal module. The OPTUK implements the opposite function in the receiving direction, and parses the data stream of each time-slot from the signal in the OPTUK format, and transmits the data stream to the adaptation module to further parse an original signal. The OTN line processing module has OPUK, ODUK, and OTUK framing functions in the OTN. In this embodiment, the OTN line processing module includes an ODUK module and an OTUK module. In the transmitting direction, the ODUK module is configured to finish mapping the OPTUK signal to the OPUK payload area, generate the ODUK OH, and transmit the OH to the OTUK module. In the receiving direction, the ODUK module terminates the ODUK OH, parses the signal in the OPTUK format from the OPUK payload area, and transmits the signal to the OPTUK module. The OTUK module finishes packaging the ODUK signal into the signal in the OTUK format in the transmitting direction. The process includes generating an OTUK OH, generating an FEC signal, and sending the signal in the OTUK to a line to be transmitted after electro-optic conversion. Further, the OTUK module finishes terminating the OTUK OH and the FEC in the receiving direction. The device as shown in Figure 8 is mainly different from the prior art (Figure 5) in that, the OPTUK module replaces the complicated function of the SDH VC layer, so as to allocate bandwidth in a format close to the line rate and finish the multiplexing of the DTM. Thereby, the device is applicable to the transmission and multiplexing of wider irregular client rates. Meanwhile, without the limitations of the complicated pointer processing and fixed rate levels of the SDH layer, the circuit realization becomes simpler and the processing cost thereof is lowered. The aforementioned device solves the technical problem that the DTM cannot be used in the OPUK of the common OTN. Thereby, owing to such an intermediate sub-layer, the device may not only be well applicable to various services, but also conveniently adapt for the OPUK. In this way, the application range of the OTN is expanded, and the bandwidth utilization and client access of the OTN become more flexible. Embodiment 3 Figure 9 shows an optical cross-connect (OXC) device with a built-in DTM scheduling function provided by the present invention. As shown in Figure 9, the OXC device includes an adaptation module, an OPTUK module, a DTM cross-connect module, an OTN line processing module, and two or more pairs of wavelength multiplexers and wavelength demultiplexers. 1) The adaptation module is configured to adapt each client signal to a signal rate of specified DTM time-slots through an adaptation protocol in a transmitting direction. For example, GE signals are adapted to a rate represented by 2000 DTM time-slots through the GFP protocol, 140 M TDM signals are adapted to a rate represented by 300 DTM time-slots by means of bit or byte insertion. In a receiving direction, the adaptation module completes the deadaptation process and parses an original client signal format from a data stream having an adaptation protocol format. 2) The OPTUK module is configured to map all the signals adapted by the adaptation module to a specified DTM time-slot position of the OPTUK in a transmitting direction. The DTM time-slot is multiplexed by mapping the adapted signals to the specified time-slots. For example, the GE, after adapted by the GFP, occupies about 2000 DTM time-slots, an ESCON signal, after adapted by the GFP, occupies 400 DTM time-slots, and all other client signals after adaptation take up the rest DTM time-slots. The DTM time-slots occupy the whole space of the OPTUK, thus realizing the DTM multiplexing function of each client signal. After the multiplexing, the signal in the OPTUK format is transmitted to the DTM cross-connect module. The OPTUK implements the opposite function in the receiving direction, parses the data stream of each time-slot with an adaptation format from the signal in the OPTUK format. and transmits the data stream to the adaptation module to further parse an original signal. 3) The DTM cross-connect module is configured to realize the cross-connection of 512 K of particles. The OPTUK signals respectively from the line and the tributary (the local mapping direction) are input into the DTM cross-connect module. Each OPTUK signal is in a synchronous state. The phase difference between the OPTUKs is adjusted by a simple frame adjustment circuit so as to achieve the synchronous cross-connection. 4) The OTN line processing module includes OPUK, ODUK, and OTUK framing functions in the OTN line. In a transmitting direction, the OPTUK signals obtained from the cross-connection of the DTM are mapped to the OPUK signals at the same rate so as to generate the ODUK OH for realizing the end-to-end management. A low-order ODUK signal is multiplexed to a high-order ODUK signal so as to generate a high-order OTUK OH including FEC. A colorful wavelength with a fixed frequency is achieved by electro-optic conversion. A mapping and de-mapping from the DTM to the OTN are also realized. Further, in a receiving direction, the optoelectronic conversion is fulfilled, the OTUK and ODUK OHs are terminated, and the signal in the OPTUK format is parsed and transmitted to the DTM cross-connect network. 5) Two or more pairs of wavelength multiplexers and wavelength demultiplexers are provided. The wavelength multiplexer is adapted to perform a wavelength-division multiplexing (WDM) on different colorful wavelengths transmitted from an optical line module. Upon requirements, the multiplexed signal may have its power amplified by a line amplifier; The wavelength demultiplexer is adapted to demultiplex the wavelength of the multiplexed signal received from the line, and output a single wavelength to the optical line unit to be processed. The result and function of this part are not described in detail herein for being the prior art. This embodiment may realize the same effect as the aforementioned embodiment. Meanwhile, since the channel of the OTN is refined by adopting 512 k of particles of the DTM, the line bandwidth utilization ratio is significantly enhanced. Embodiment 4 Figure 10 shows the structure of an optical add/drop multiplexer (OADM) with a built-in DTM scheduling function provided by the present invention. As shown in FIG 10, the OADM structure includes an adaptation module, an OPTUK module, a DTM cross-connect module, an OTN line processing module, a wavelength multiplexing/demultiplexing module, and an OADM module. 1) The adaptation module is configured to adapt each client signal to a signal rate of specified DTM time-slots through an adaptation protocol in a transmitting direction. For example, GE signals are adapted to a rate represented by 2000 DTM time-slots through the GFP protocol, 140 M TDM signals are adapted to a rate represented by 300 DTM time-slots by means of bit or byte insertion. In a receiving direction, the adaptation module completes the deadaptation process and parses an original client signal format from a data stream having an adaptation protocol format. 2) The OPTUK module is configured to map all the signals adapted by the adaptation module to a specified DTM time-slot position of the OPTUK in a transmitting direction. The DTM time-slot is multiplexed by mapping the adapted signals to the specified time-slots. For example, the GE, after adapted by the GFP, occupies about 2000 DTM time-slots, an ESCON signal, after adapted by the GFP, occupies 400 DTM time-slots, and all other client signals after adaptation take up the rest DTM time-slots. The DTM time-slots occupy the whole space of the OPTUK, thus realizing the DTM multiplexing function of each client signal. After the multiplexing, the signal in the OPTUK fonnat is transmitted to the DTM cross-connect module. The OPTUK implements the opposite function in the receiving direction, the OPTUK module parses the data stream of each time-slot with an adaptation format from the signal in the OPTUK format, and transmits the data stream to the adaptation module to further parse an original signal. 3) The DTM cross-connect module is configured to realize the cross-connection of 512 K of particles. The OPTUK signals respectively from the line and the tributary (the local mapping direction) are input into the DTM cross-connect module. Each OPTUK signal is in a synchronous state. The phase difference between the OPTUKs is adjusted by a simple frame adjustment circuit so as to achieve the synchronous cross-connection. 4) The OTN line processing module includes OPUK, ODUK, and OTUK framing functions in the OTN line. In a transmitting direction, the OPTUK signals obtained from the cross-connection of the DTM are mapped to the OPUK signals at the same rate so as to generate the ODUK OH for realizing the end-to-end management. A low-order ODUK signal is multiplexed to a high-order ODUK signal, so as to generate a high-order OTUK OH including FEC. A colorful wavelength with a fixed frequency is achieved by electro-optic conversion. A mapping and de-mapping from the DTM to the OTN are also realized. Further, in a receiving direction, the optoelectronic conversion is fulfilled, the OTUK and ODUK OHs are terminated, and the signal in the OPTUK format is parsed and transmitted to the DTM cross-connect network. 5) The wavelength multiplexing/demultiplexing module is configured to fulfill the demultiplexing of a band to a single wavelength, or the multiplexing of a local wavelength into a band. 6) The OADM module includes at least a pre-amplifier, a power amplifier, and a wavelength block (WB) module. A required wavelength is emitted to the wavelength multiplexing/demultiplexing module through the WB module. Meanwhile, an uplink band of the multiplexing module is multiplexed to the line. This embodiment may also achieve the same effect as the above embodiment. In view of the above, the embodiments of the device and method for transmitting a DTM on an OTN provided by the present invention have the following effectives. 1) The mapping problem that the DTM cannot be directly OVER to the OTN is solved. Since 512 k of particles of the DTM are adopted to refine the OTN channel, the line bandwidth utilization ratio is significantly enhanced. This technology may be adapted to improve the conventional TMUX and applied to the DWDM and OTN products, and may realize the transparent transmission of any service at any sub-rate. Besides, this technology apparently saves more bandwidth than the method of mapping from the DTM to VC then to STM-N and further to the OTN, and does not need additional complicated OH and pointer processing of the SDH layer, thus reducing the process cost. 2) The present invention is applicable to various services and has strong service adaptability. Meanwhile, the present invention achieves high QoS real-time transmission for various data services, video services, and TDM services, expands the adaptable ranges of services and sub-rates for the OTN, and realizes stepless adaptation at any rate. 3) The device of the present invention is built in an OXC or OADM to replace the conventional TDM exchange plane, or simulate the function of a data plene. Thereby, the capability of unified plane scheduling is indeed realized, and the device cost and difficulties in management are both reduced. Though illustration and description of the present invention have been given by reference to exemplary embodiments of the invention, it should be appreciated by persons of ordinary skills in the art that various changes in forms and details can be made without deviation from the spirit and scope of this disclosure, which are defined by the appended claims. WE CLAIM: 1. A method for transmitting a dynamic synchronous transfer mode on an optical transmission net, comprising: mapping a client signal adapted to a time-slot rate of a specified dynamic synchronous transfer mode to a corresponding time-slot position in an intermediate data frame, and generating a signal in a format of the intermediate data frame, wherein the intermediate data frame has a repetition period identical to the repetition period of a dynamic synchronous transfer mode frame and a rate identical to the rate of a payload area in an optical transmission net frame; and mapping the signal in the format of the intermediate data frame to the optical transmission net frame. 2. The method for transmitting a dynamic synchronous transfer mode on an optical transmission net according to claim I, wherein the mapping the signal in the format of the intermediate data frame to the optical transmission net frame comprises: mapping the signal in the format of the intermediate data frame to an optical channel data unit and generating an optical channel data unit-K signal; and packaging the optical channel data unit signal into a signal in a format of an optical channel transport unit-K. 3. The method for transmitting a dynamic synchronous transfer mode on an optical transmission net according to claim 1, wherein a time-slot division unit in the intermediate data frame structure is equal to or larger than a dynamic synchronous transfer mode time-slot division unit in a DTM frame structure. 4. The method for transmitting a dynamic synchronous transfer mode on an optical transmission net according to claim 3, wherein the time-slot division unit in the intermediate data frame structure is 64 bits. 5. The method of transmitting a dynamic synchronous transfer mode on an optical transmission net according to claim 1, wherein the intermediate data frame structure comprises an overhead time-slot portion and a data time-slot portion, and the overhead time-slot portion comprises a frame synchronous time-slot and a control time-slot. 6. The method for transmitting a dynamic synchronous transfer mode on an optical transmission net according to claim 1, wherein an original rate of the client signal comprises fast Ethernet, gigabit Ethernet, enterprise system connection, synchronous digital hierarchy, or plesiochronous digital hierarchy. 7. The method for transmitting a dynamic synchronous transfer mode on an optical transmission net according to any one of claims 1 to 6, wherein the intermediate data frame is an optical channel payload tributary unit-K frame, where different K values are corresponding to different rate levels, and the optical transmission net frame is substantially an optical transmission net frame at the same rate level as the optical channel payload fributary unit-K. 8. The method for transmitting a dynamic synchronous transfer mode on an optical transmission net according to claim 7, wherein the optical channel payload tributary unit-K frame has a size of X*270*9 bytes, X represents a rate level of the optical channel payload tributary unit-K, and when K=l, X=16, when K=2, X=64, and when K=3, X=256. 9. A device for fransmitting a dynamic synchronous transfer mode on an optical fransmission net, comprising: an adaptation module, configured to adapt a client signal to a specified dynamic synchronous transfer mode time-slot rate; an intermediate data frame module, configured to map the client signal adapted by the adaptation module to a corresponding time-slot position in a intermediate data frame so as to generate a signal in a format of the intermediate data frame, wherein the intermediate data frame has a repetition period identical to the repetition period of a dynamic synchronous transfer mode frame, and a rate identical to the rate of a payload area in an optical transmission net frame; and an optical fransmission net line processing module, configured to map the signal in the format of the intermediate data frame to the optical transmission net frame. 10. The device according to claim 9, wherein a time-slot division unit in the intermediate data frame structure is equal to or larger than a dynamic synchronous transfer mode time-slot division unit in the dynamic synchronous transfer mode frame structure. 11. The device according to claim 9, wherein the intermediate data frame comprises an overhead time-slot portion and a data time-slot portion, and the overhead time-slot portion comprises a frame synchronous time-slot and a control time-slot. 12. The device according to claim 9, wherein the optical transmission net line processing module comprises: an optical channel data unit-K sub-module, configured to map the signal in the format of the intermediate data frame to an optical channel payload unit-K so as to generate an optical channel data unit-K signal; and an optical channel transport unit-K sub-module, configured to package the optical channel data unit-K signal into an optical channel transport unit-K format signal. 13. The device according to any one of claims 9 to 12, wherein the intermediate data frame is an optical channel payload tributary unit-K frame, where different K values are corresponding to different rate levels, and the optical transmission net frame is substantially an optical transmission net frame at the same rate level as the optical channel payload tributary unit-K. 14. The device according to any one of claims 9 to 12, further comprising a dynamic synchronous transfer mode cross-connect module coupled between the intermediate data frame module and the optical transmission net line processing module, and configured to perform synchronous cross-connection on the signal in the format of the intermediate data frame. 15. An optical cross-connect equipment, comprising a wavelength multiplexer and a wavelength demultiplexer, wherein the optical cross-connect equipment further comprises a device for transmitting a dynamic synchronous transfer mode on an optical transmission net as claimed in any one of claims 9 to 12 coupled to the wavelength multiplexer and the wavelength demultiplexer, an output signal of the device is an input signal of the wavelength multiplexer, and an output signal of the wavelength demultiplexer is an input signal of the device. 16. The optical cross-connect equipment according to claim 15, wherein the device further comprises a dynamic synchronous transfer mode cross-connect module coupled between the intermediate data frame module and the optical transmission net line processing module, and configured to perform synchronous cross-connection on the signal in the format of the intermediate data frame. 17. An optical add/drop multiplexer, comprising a wavelength multiplexing/demultiplexing module and an optical add/drop multiplexing module coupled to each other, wherein the optical add/drop multiplexer further comprises a device for transmitting a dynamic synchronous transfer mode on an optical transmission net as claimed in any one of claims 9 to 12 coupled to the wavelength multiplexing/demultiplexing module, an output signal of the device is an input signal of the wavelength multiplexing/demultiplexing module, and a reverse output signal of the wavelength multiplexing/demultiplexing module is a reverse input signal of the device. 18. The optical add/drop multiplexer according to claim 17, wherein the device further comprises a dynamic synchronous transfer mode cross-connect module coupled between the intermediate data frame module and the optical transmission net line processing module, and configured to perform synchronous cross-connection on the signal in the format of the intermediate data frame. Dated this 25th day of September 2008 The present invention relates to the technical field of an optical transport network (OTN), and discloses a method for transmitting a dynamic synchronous transfer mode (DTM) on an OTN. Firstly, a client signal adapted to a time-slot rate of a specified DTM is mapped to a corresponding time-slot position in an intermediate data frame, and a signal in a format of the intermediate data frame is generated. The intermediate data frame has a repetition period identical to that of a DTM frame, and a rate identical to that of a payload area in an OTN frame. Next, the signal in a format of the intermediate data frame is mapped to the OTN frame. Further, the present invention also discloses a device; for transmitting a DTM on an OTN, an optical cross-connect (OXC) equipment, and an optical add/drop multiplexer (OADM) adopting the above mapping device. The method of mapping a DTM to an OTN provided by the present invention saves the cost compared with a conventional method for mapping a DTM to an OTN through an intermediate data frame.

Documents:

3898-KOLNP-2008-(02-01-2014)-CORRESPONDENCE.pdf

3898-KOLNP-2008-(14-03-2014)-ABSTRACT.pdf

3898-KOLNP-2008-(14-03-2014)-ANNEXURE TO FORM 3.pdf

3898-KOLNP-2008-(14-03-2014)-CLAIMS.pdf

3898-KOLNP-2008-(14-03-2014)-CORRESPONDENCE.pdf

3898-KOLNP-2008-(14-03-2014)-DESCRIPTION (COMPLETE).pdf

3898-KOLNP-2008-(14-03-2014)-DRAWINGS.pdf

3898-KOLNP-2008-(14-03-2014)-FORM-1.pdf

3898-KOLNP-2008-(14-03-2014)-FORM-2.pdf

3898-KOLNP-2008-(14-03-2014)-OTHERS.pdf

3898-KOLNP-2008-(18-03-2014)-CORRESPONDENCE.pdf

3898-KOLNP-2008-(18-03-2014)-OTHERS.pdf

3898-KOLNP-2008-(18-09-2013)-CORRESPONDENCE.pdf

3898-KOLNP-2008-(18-09-2013)-FORM-3.pdf

3898-KOLNP-2008-(18-09-2013)-FORM-5.pdf

3898-KOLNP-2008-(18-09-2013)-PETITION UNDER RULE 137.pdf

3898-KOLNP-2008-(29-12-2014)-CORRESPONDENCE.pdf

3898-KOLNP-2008-(30-04-2012)-CORRESPONDENCE.pdf

3898-KOLNP-2008-(30-04-2012)-FORM-3.pdf

3898-kolnp-2008-abstract.pdf

3898-kolnp-2008-claims.pdf

3898-KOLNP-2008-CORRESPONDENCE 1.1.pdf

3898-KOLNP-2008-CORRESPONDENCE 1.2.pdf

3898-kolnp-2008-correspondence.pdf

3898-kolnp-2008-description (complete).pdf

3898-kolnp-2008-drawings.pdf

3898-kolnp-2008-form 1.pdf

3898-kolnp-2008-form 18.pdf

3898-kolnp-2008-form 2.pdf

3898-KOLNP-2008-FORM 3-1.1.pdf

3898-kolnp-2008-form 3.pdf

3898-kolnp-2008-form 5.pdf

3898-kolnp-2008-gpa.pdf

3898-kolnp-2008-international preliminary examination report.pdf

3898-kolnp-2008-international publication.pdf

3898-kolnp-2008-international search report.pdf

3898-kolnp-2008-others pct form.pdf

3898-kolnp-2008-pct priority document notification.pdf

3898-kolnp-2008-specification.pdf

3898-kolnp-2008-translated copy of priority document.pdf

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