An OFDM-PON transmitting end data real-time slicing method

Abstract

The application discloses an OFDM-PON sending end data real-time slicing method, which comprises the following steps: a data processing module of a sending end receives service data through a service interface module, writes the service data into a data storage module of the sending end, and prepares for subsequent reading; the data storage module stores a real-time data storage state to a decision layer; the decision layer sends control information to the data storage module and a data slicing module in each sending period; the data storage module reads out to-be-sliced data streams and sends data stream mark information to the data slicing module in each sending period; the data slicing module slices the to-be-sliced data streams according to the subcarrier mapping format message sent by the decision layer and the mark information and the read data of all to-be-sliced data streams sent by the data storage module, sends the to-be-sliced data streams to parallel subcarrier interfaces, and stores the bit data remaining after slicing in the current period in a to-be-sliced data storage area. The method guarantees the flexibility of system bandwidth allocation and communication performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of passive optical network, and particularly relates to a data real-time slicing method for an OFDM-PON sending end. BACKGROUND

[0002] With the rapid development of Internet technology, the demand for data transmission is growing explosively, and modern networks have higher requirements for data transmission. Traditional passive optical network (PON) technologies, such as time division multiplexing passive optical network (TDM-PON), are difficult to meet the demand of modern networks for flexible bandwidth allocation due to their time division multiplexing characteristics of allocating time slices to users in a single carrier. Orthogonal frequency division multiplexing passive optical network (OFDM-PON) maps multiple user data in the form of OFDM symbols on multiple carriers for modulation communication, and its high spectral efficiency, high flexibility of bandwidth allocation, and low latency and low jitter of services have attracted widespread attention and research.

[0003] In the sending end of OFDM-PON, the function of real-time allocation of service data from reception to each subcarrier in bit units according to dynamic modulation format needs to be completed. ITU-T G.989 protocol gives a suggestion for the low jitter of 40Gbit / s NG-PON2 service from the perspective of network operators and dynamic bandwidth allocation, but it is not suitable for the scenario of transmitting service data in bit level in OFDM-PON; KANG et al. in “OFDM SIGNAL TRANSMITTING APPARATUS AND METHOD FOR OFDM-PON [P]. KR20140127902, 2016-04-01.” provide a method and device for converting a media access control (MAC) layer MAC frame into a physical frame containing a physical layer preamble. This patent realizes the transmission of signals from the macroscopic process of data reception, OFDM symbol modulation, and subcarrier mapping, but does not describe in detail how to map the OFDM symbol form data to the subcarrier for transmission from the bit level. SUMMARY

[0004] In view of the fact that the prior art cannot complete the reception, slicing, and mapping transmission of OFDM-PON data from the bit level, the present application provides a data real-time slicing method for an OFDM-PON sending end, which realizes the whole process from service data reception to transmission by implementing real-time slicing and subcarrier mapping of data in a sending period T send of an OFDM symbol, thereby meeting the low latency and low jitter service requirements, while ensuring the flexibility of system bandwidth allocation and communication performance.

[0005] To achieve the above object, the application provides a real-time data slicing method for an OFDM-PON sending end, comprising the following steps:

[0006] The data processing module of the sending end OLT receives service data from the upper service layer through the service interface module, writes the service data into the data storage module of the sending end, and prepares for subsequent reading;

[0007] The data storage module transmits the data storage state in the data storage module to the decision layer in real time.

[0008] The decision layer sends control information to the data storage module and the data slicing module in each sending period T send .

[0009] The data storage module reads out the data stream to be sliced and sends the data stream marker information to the data slicing module in each sending period T send .

[0010] The data slicing module slices the data stream to be sliced according to the subcarrier mapping format message sent by the decision layer and the marker information and read data of all data streams to be sliced sent by the data storage module, sends the sliced data stream to the parallel subcarrier interface, and registers the remaining bit data of the current period in the data stream to be sliced storage area.

[0011] Further, the data storage module receives service data from the service interface module, buffers in different areas according to different service destination addresses, forms a plurality of data stream buffer areas, and sequentially stores and reads each data stream buffer area in a first-in-first-out queue.

[0012] Further, the data storage module transmits the data storage state in the data storage module to the decision layer in real time, including the source address, the destination address and the data storage amount of each service.

[0013] Further, after the data storage module transmits the data storage state in the data storage module to the decision layer in real time, the decision layer calculates the data reading information and sends it to the data storage module according to the data storage state transmitted by the data storage module in real time, the bit error rate of each ONU, the communication condition of the delay and the uplink and downlink traffic condition, and then calculates the subcarrier mapping format message in the current sending period k and sends it to the data slicing module.

[0014] Further, the data storage module and the data slicing module are connected.

[0015] Further, the data storage module reads out the data stream to be sliced and sends the data stream marker information to the data slicing module in each sending period T send .

[0016] The data storage module calculates the marking information of each data stream to be sliced according to the data reading information sent by the decision layer in the current sending cycle k, reads out the marking information and sends it to the data slicing module in parallel.

[0017] Further, the data storage module calculates the marking information of each data stream to be sliced according to the data reading information sent by the decision layer in the current sending cycle k The data storage module calculates the marking information of each data stream to be sliced according to the data reading information sent by the decision layer in the current sending cycle k reads out the data and sends it to the data slicing module in parallel.

[0018] wherein, is a binary symbol, indicating that the data read out by the data stream i in the current sending cycle k is valid, is a bit identifier indicating the number of valid bits of the data read out by the data stream i in the current sending cycle k.

[0019] Further, the data slicing module, according to the subcarrier mapping format message sent by the decision layer, is and i∈[1,N],l∈[1,M].

[0020] wherein, represents the number of data bits carried by the modulation format used by the subcarrier l in the current sending cycle k, represents the ONU carried by the subcarrier l in the kth sending cycle, and i Further, the data slicing module, according to the subcarrier mapping format message sent by the decision layer and the marking information and read-out data of all data streams to be sliced sent by the data storage module, slices the data streams to be sliced and sends them to the parallel subcarrier interface, and stores the remaining bit data of the current cycle in the data storage area to be sliced, which specifically includes:

[0021] Before slicing, the slicing information of each data stream is extracted through the subcarrier mapping format message, and the length of the data to be sliced is calculated;

[0022] Before slicing, first, for each data stream to be sliced, check whether there is remaining data of the data stream in the previous slicing process in the data storage area to be sliced, if there is, extract the corresponding remaining data and count the number of bits of the remaining data; through the marking information of all data streams to be sliced, the read-out data of each data stream is spliced and stored to form the data to be sliced.

[0023] Compare the length of the data to be sliced and the length of the spliced data, when the length of the spliced data is greater than or equal to the length of the data to be sliced, it means that the data of the data stream i in the current sending cycle has been completely spliced, and the data slicing is performed.

[0024] The data slicing module allocates bits to the data to be sliced through a subcarrier mapping format message, and distributes the obtained binary sequence to the specified subcarriers, and stores the remaining bit data in the corresponding area in the data to be sliced storage area.

[0025] Further, when splicing each data stream, the remaining data is spliced first, and the remaining data of the data stream in the data cache module is spliced, and the length of the spliced data is calculated.

[0026] Technical effects

[0027] 1. The OFDM-PON sending end data real-time slicing method provided by the application can complete the requirements of OFDM-PON sending end from service reception to subcarrier interface transmission from the bit level, meet the requirements of low delay and low jitter of services, guarantee the flexibility of system bandwidth allocation and communication performance, and meet the best communication conditions of each ONU in communication.

[0028] 2. The application guarantees stable transmission of data link by real-time slicing and subcarrier mapping of data at the sending end, solves the problems of low resource utilization and inadaptability of traditional TDM-PON in dynamic rate scenarios, and fully utilizes the flexibility and bandwidth advantages of OFDM-PON system. In one sending period, the flexible rate transmission from N*M*B min (bit / s) to N*M*B max (bit / s) is realized.

[0029] The concept, specific structure and technical effects of the application will be further described below with reference to the accompanying drawings, so as to fully understand the purpose, features and effects of the application. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a flowchart of an OFDM-PON sending end data real-time slicing method of a preferred embodiment of the application;

[0031] Figure 2 is a slicing flowchart of a data slicing module of an OFDM-PON sending end data real-time slicing method of a preferred embodiment of the application;

[0032] Figure 3 is a system architecture diagram of an OFDM-PON sending end data real-time slicing method of a preferred embodiment of the application;

[0033] Figure 4is a data slicing module of an OFDM-PON sending end data real-time slicing method of a preferred embodiment of the present application, and a simulation result diagram of slice information of each data stream extracted by a subcarrier mapping format message;

[0034] Figure 5 is a data splicing and splicing length calculation simulation result diagram of an OFDM-PON sending end data real-time slicing method of a preferred embodiment of the present application;

[0035] Figure 6 is a to-be-sliced data length and spliced data length comparison simulation result diagram of an OFDM-PON sending end data real-time slicing method of a preferred embodiment of the present application;

[0036] Figure 7 is a to-be-sliced data bit allocation simulation result diagram of an OFDM-PON sending end data real-time slicing method of a preferred embodiment of the present application. DETAILED DESCRIPTION

[0037] In order to make the technical problems to be solved by the present application, technical solutions and beneficial effects clearer, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0038] In the following description, specific details are set forth in order to provide a thorough understanding of embodiments of the application. However, persons of ordinary skill in the art will readily recognize that embodiments of the application can be practiced without some or all of the specific details set forth herein. In other instances, well-known structures, circuits, and processes have not been described in detail in order to not unnecessarily obscure aspects of the application.

[0039] As shown in Figure 1 The present application provides an overall flowchart of an OFDM-PON sending end data real-time slicing method, which is applied to the technical field of passive optical network and includes the following steps:

[0040] S101: The data processing module of the sending end OLT receives service data from the upper service layer through the service interface module, writes the service data into the data storage module of the sending end, and prepares for subsequent reading; the data storage module receives the service data from the service interface module, buffers in different areas according to different service destination addresses, forms a plurality of data flow buffer areas, and sequentially stores and reads out each data flow buffer area in a first-in-first-out queue.

[0041] S102: The data storage module transmits the data storage state in the decision layer real-time transmission module; the data storage module transmits the data storage information to the decision layer in real time, including the source address, the destination address and the data storage amount of each service.

[0042] S103: The decision layer transmits the control information to the data storage module in each transmission period T send ; the decision layer transmits the data storage state, the bit error rate, the delay and other communication conditions of each ONU and the uplink and downlink traffic conditions in real time through the data storage module, first calculates the data reading information and transmits it to the data storage module, then calculates the subcarrier mapping format message and of each subcarrier in the current transmission period k, and transmits it to the data slicing module.

[0043] Wherein, N is the maximum number of ONUs, i is the serial number of a data stream. M is the total number of subcarriers, and l is the serial number of a subcarrier. is the number of data bits read out by the data stream sent to the i-th destination address in the k-th transmission period; is the number of data bits carried by the modulation format of the subcarrier l in the k-th transmission period. indicates that the subcarrier l carries the data of the ONU i in the k-th transmission period, and this message is used to inform the data slicing module of the mapping relationship between each data stream and each subcarrier. It should be noted that the number of modulation bits should be within the range of modulation bits that the system can support [B min , B max ].

[0044] S104: The data storage module reads out the data stream to be sliced and transmits the data stream marker information to the data slicing module in each transmission period T send ; the data storage module is connected with the data slicing module, reads out the data stream to be sliced and the data stream marker information to the data slicing module in each transmission period T send , and the specific operation includes:

[0045] The data storage module calculates the marker information of each data stream to be sliced according to the data reading information transmitted by the decision layer in the current transmission period k , reads out the data and transmits it to the data slicing module in parallel.

[0046] Wherein, is a binary symbol, indicating that the data of the data stream i read out in the current transmission period k is valid. is the bit identifier representing the number of valid bits of the data stream i read out in the current transmission period k, and its bit width is is the bit identifier representing the number of valid bits of the data stream i read out in the current transmission period k, and its bit width is BW is the bit identifier representing the number of valid bits of the data stream i read out in the current transmission period k, and its bit width is is the bit identifier representing the number of valid bits of the data stream i read out in the current transmission period k, and its bit width is is the bit identifier representing the number of valid bits of the data stream i read out in the current transmission period k, and its bit width is is the bit identifier representing the number of valid bits of the data stream i read out in the current transmission period k, and its bit width is is the bit identifier representing the number of valid bits of the data stream i read out in the current transmission period k, and its bit width is

[0047] S105: The data slicing module slices the data streams to be sliced according to the subcarrier mapping format message sent by the decision layer and the marking information and read data of all data streams to be sliced sent by the data storage module, sends the sliced data streams to the parallel subcarrier interface, and stores the remaining bit data of the current period in the data storage area to be sliced.

[0048] As shown in Figure 2 , it specifically comprises:

[0049] S1051: Before slicing, the slicing information of each data stream is extracted through the subcarrier mapping format message, including and the binary sequence i∈[1,N]. The length of data to be sliced data_flow_length k,i is calculated.

[0050] wherein, is the total number of subcarriers allocated to the data stream i in the transmission period k, is the number of modulated bits of the subcarriers allocated to the data stream i in the transmission period k, and the bit width of the binary sequence is the total number of subcarriers M, and each bit is used to indicate whether a subcarrier ID is allocated to the data stream i in the current period, and the high level is valid. data_flow_length k,i is the length of the data to be sliced of the data stream i in the transmission period k,

[0051] S1052: Before slicing, first, for each data stream to be sliced, check whether there is remaining data of the data stream in the previous slicing process in the data storage area to be sliced, and if so, extract the corresponding remaining data data_remain k,i and count the number of bits of the remaining data data_remain_length k,iThe read data of each data flow is spliced by the mark information of all data flows to be sliced to form data to be sliced data data_slice. When splicing each data flow, data_slice first splices remaining data data_remain k,i , then splices the remaining data of the data flow in the data cache module, and calculates the length of the spliced data

[0052] S1053: When data_slice_length k,i ≥ data_flow_length k,i , it means that the data of the data flow i in the current sending period has been completely spliced, and data slicing is performed.

[0053] S1054: The data slicing module performs bit allocation on the data to be sliced data data_slice by the subcarrier mapping format message, and allocates the obtained binary sequence to the specified subcarrier, and stores the remaining bit data in the corresponding area in the data to be sliced data storage area in the slicing period.

[0054] As shown in Figure 3 , the application completes the functions of receiving, slicing, and mapping and sending of OFDM-PON service data in each sending period k by the sending end data processing module. The sending end data processing module is connected with the service layer, the decision layer, and the subcarrier interface. The sending end data processing module receives OFDM-PON service data from the service layer, sends storage information to the decision layer and receives control information from the decision layer, and maps and sends the sliced data flow to the subcarrier interface; the service layer is connected with the sending end data processing module and sends OFDM-PON service data to the sending end data processing module; the decision layer is connected with the sending end data processing module, receives the storage information of the sending end data processing module in real time, and sends the control information corresponding to the current sending period to the sending end data processing module; the subcarrier interface is connected with the sending end data processing module and receives the sliced data from the sending end data processing module in each sending period k.

[0055] The sending end data processing module comprises a service interface module, a data storage module and a data slicing module. The service interface module is connected with the service layer and the data storage module, the service interface module receives OFDM-PON service data from the service layer and sends the data stream to the data storage module; the data storage module is connected with the decision layer and the data slicing module, the data storage module receives the data stream of the service interface module, buffers the data stream in different areas according to different service destination addresses, forms a plurality of data stream buffer areas, each data stream buffer area is sequentially stored and read out in a first-in first-out queue, and real-time storage information is sent to the decision layer, data reading information is received from the decision layer, and the corresponding data stream is read out to the data slicing module; the data slicing module is connected with the data storage module and a sub-carrier interface, the data slicing module receives the data stream read out from the data storage module, slices the to-be-sliced data stream according to the sub-carrier mapping format message sent by the decision layer and the marking information of all to-be-sliced data streams sent by the data storage module, and sends the to-be-sliced data stream to the sub-carrier interface, and the remaining bit data of the slicing in the current period is stored in the to-be-sliced data storage area.

[0056] The following will take an OFDM-PON sending end data real-time slicing method implemented on an FPGA as an example to describe the scheme of the present application:

[0057] In this embodiment, the simulation of data slicing of the OFDM-PON sending end, the sending end data processing module has buffered service data of a plurality of data sources, works under a global clock of 200Mhz, and uses a data bus with a bit width of 64bit to transmit the service. In a sending period k, the allocation result received by the sending end from the decision layer is that: data stream 1 needs to splice and slice 137bit data, including 128bit data buffered in the current sending period and 9bit data remaining in the previous sending period, and then map the data to sub-carriers No. 1-45, using an 8-QAM modulation mode, and each sub-carrier carries 3bit data; data stream 2 needs to splice and slice 79bit data, including 64bit data buffered in the current sending period and 15bit data remaining in the previous sending period, and then map the data to sub-carriers No. 46-64, using a 16-QAM modulation mode, and each sub-carrier carries 4bit data. After this slicing, 2bit data of data stream 1 and 3bit data of data stream 2 remain unsliced, the unsliced data is stored in the to-be-sliced data storage area, and is read out in the next slicing period. The slicing method of the present application has a certain interval time in adjacent two sending periods, and can support the FPGA to complete the scheduling slicing and mapping operation of data within several clocks.

[0058] In the embodiment, the data slicing module first analyzes the slicing information sent by the decision layer. In the current sending cycle k, the slicing information received by the FPGA is sc_bitload_info_i=0x6db6db6db6db6db6db6db6db6db6db6db724924924924924, sc_data_l_assign_list=0x00001fffffffffff, and sc_data_2_assign_list=0xffffe00000000000. The analysis shows that data stream 1 is allocated subcarriers No. 1-45, and the number of modulation bits is 3 bits, corresponding to the modulation format 8-QAM; data stream 2 is allocated subcarriers No. 46-64, and the number of modulation bits is 4 bits, corresponding to the modulation format 16-QAM. Thus, it is calculated that in the current sending cycle, data stream 1 needs to slice 135 bits of data, and data stream 2 needs to slice 76 bits of data, as shown in Figure 4 .

[0059] The data received by data stream 1 is 64 bits of data lasting for 2 beats, and each beat of data is assisted by mark signals such as ofdm_rec_flowl_keep_i and ofdm_rec_flowl_valid_i, for the data slicing module to judge the starting position of the data and whether the data is valid. Data stream 2 receives 64 bits of data lasting for 1 beat and mark signals. When each beat of data arrives, the data is spliced. First, the remaining data in the previous sending cycle is taken out from the respective data storage area to be sliced as the head of the sliced data, and then the read data is spliced to form the data to be sliced data_flowl_slice and data_flow2_slice, and the length of the spliced data data_flowl_slice_length and data_flow2_slice_length is accumulated, as shown in Figure 5 .

[0060] The length of the data to be sliced is compared with the length of the spliced data in real time, and the comparison result slice_flag is output, which is high in level and valid, as shown in Figure 6 .

[0061] The spliced data data_flow1_slice and data_flow2_slice are allocated subcarrier IDs according to the data flow (subcarriers 1-45 for data flow 1 and subcarriers 46-64 for data flow 2), the number of bits modulated by the subcarriers (3 bits for data flow 1 and 4 bits for data flow 2), and then data slicing and subcarrier mapping are performed. According to the ID of each subcarrier, the corresponding number of bits is allocated from the end of the spliced data, the data slicing and subcarrier mapping of the current transmission period are completed, the sliced data is used by the lower interface, and the remaining un-sliced data is stored in the to-be-sliced data storage area. The remaining 2 bits of data flow 1 are 2'b00 and the remaining 3 bits of data flow 2 are 3'b100, which are consistent with the theory, as shown in Table 1. Figure 7

[0062] The preferred embodiments of the present application are described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations without creative work based on the concept of the present application. Therefore, any technical solution obtained by logical analysis, reasoning or limited experiment based on the existing technology according to the concept of the present application shall be within the protection scope defined by the claims.​

Claims

1. A method for real-time slicing of data at a transmitting end of an OFDM-PON, characterized in that, The method comprises the following steps: The data processing module of the sending OLT receives service data from the upper service layer through the service interface module, writes the service data into the data storage module of the sending end, and prepares for subsequent reading; The data storage module transmits the data storage state in the data storage module to the decision layer in real time. The decision layer sends control information to the data storage module and data slice module in each sending period T send ; The data storage module reads out the data stream to be sliced and sends the data stream mark information in each sending period t send The inward data slice module reads out the data stream to be sliced and sends the data stream mark information; Specifically comprising: The data storage module calculates the marking information of each piece of data stream to be sliced according to the data reading information sent by the decision layer in the current sending cycle k, reads out the marking information and sends it to the data slicing module in parallel; the data storage module calculates the marking information of each piece of data stream to be sliced according to the data reading information sent by the decision layer in the current sending cycle k calculates the marking information of each piece of data stream to be sliced reads out the data and sends it to the data slicing module in parallel; wherein is a binary symbol indicating that the data read out by the data stream i in the present transmission period k is valid, is a bit identifier indicating the number of valid bits of the data read out by the data stream i in the present transmission period k; The data slicing module slices the to-be-sliced data stream according to the subcarrier mapping format message sent by the decision layer and the marking information and read data of all to-be-sliced data streams sent by the data storage module, sends the to-be-sliced data stream to the parallel subcarrier interface, and registers the remaining bit data in the to-be-sliced data storage area in the current period; specifically comprising: Before slicing, the slicing information of each data stream is extracted through the subcarrier mapping format message, and the to-be-sliced data length is calculated; Before slicing, first, for each to-be-sliced data stream, check whether there is remaining data of the data stream in the to-be-sliced data storage area in the previous slicing process, if there is, extract the corresponding remaining data and count the bit number of the remaining data; through the marking information of all to-be-sliced data streams, the read data of each data stream is spliced and registered to form to-be-sliced data; Compare the to-be-sliced data length and the spliced data length, when the spliced data length is greater than or equal to the to-be-sliced data length, it means that the data of the data stream i in the current sending period has been completely spliced, and data slicing is performed; The data slicing module allocates bits to the to-be-sliced data through the subcarrier mapping format message, and allocates the bits to the specified subcarriers according to the obtained binary sequence, and registers the remaining bit data in the corresponding area in the to-be-sliced data storage area in the slicing period; The data slicing module sends a subcarrier mapping format message to the decision layer according to the subcarrier mapping format message sent by the decision layer and wherein, represents the number of data bits carried by the modulation format adopted by the subcarrier I in the present transmission period k, represents the ONU carried by the subcarrier I in the kth transmission period is ONU i .

2. The method of claim 1, wherein the method further comprises: The data storage module receives service data from the service interface module, buffers different areas according to different service destination addresses, forms a plurality of data stream buffer areas, and sequentially stores and reads each data stream buffer area in a first-in-first-out queue.

3. The OFDM-PON transmitter data real-time slicing method according to claim 1, wherein: The data storage module transmits the data storage state in the data storage module to the decision layer in real time, including the source address, destination address and data storage amount of each service.

4. The OFDM-PON transmitter data real-time slicing method according to claim 1, wherein: After the data storage module transmits the data storage state in the data storage module to the decision layer in real time, the decision layer calculates the data reading information and sends it to the data storage module according to the data storage state transmitted by the data storage module in real time, the bit error rate of each ONU, the communication condition of the delay and the uplink and downlink traffic condition, and then calculates each subcarrier mapping format message in the current sending period k and sends it to the data slicing module.

5. The OFDM-PON transmitting end data real-time slicing method of claim 4, wherein, The data storage module and the data slicing module are connected.

6. The OFDM-PON transmitter data real-time slicing method according to claim 1, wherein: When splicing each data stream, the remaining data is spliced first, then the remaining data of the data stream in the data buffer module is spliced, and the spliced data length is calculated.

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