CN101409708A - GPON GTC frame-forming sublayer based on FPGA - Google Patents

Abstract

The invention relates to a GPON GTC framing sub-layer based on FPGA. In the GPON GTC framing sub-layer, a data flow of a GTC framing sub-layer is divided into two paths of uplink and downlink to be treated. The downlink data flow is sent to an ONU by an OLT and is sent to an adaptation layer after the de-framing treatment by a TC layer. In the uplink flow, information required by users is sent to the OLT after the framing treatment of the TC layer in the ONU. The data treatment process is realized in FPGA. The GPON GTC framing sub-layer which has high IP business efficiency and strong TDM business bearing capacity, is based on FPGA, and can provide wider bandwidth for users is provided.

Description

GPON GTC framing sublayer based on FPGA

Technical field

The present invention relates to GPON GTC framing sublayer designs program.

Background technology

The develop rapidly of broadband network and various high bandwidth professional and constantly occurring of using makes the introducing of band optical fiber access network technology lay out agenda, North America and Japan's construction that Fiber to the home (FTTH) at present scale launches, and the experiment of domestic FTTH has come into effect in some places, in the industry the discussion of this respect also be can be heard without end.The technology that is applied to the band optical fiber Access Network at present mainly contains three kinds, they are based on the multi-service tranmission techniques (MSTP) of SDH (Synchronous Digital Hierarchy) (SDH), multiple services passive optical network technique (PON) and the point-to-point optical transceiver of multi-service (P2P or title MC) respectively, have following characteristics:

1.MSTP very high service quality is arranged, but cost is higher, be fit to quality of service and fail safe etc. are required very high large user, be not suitable for the ordinary family user.

2. the star-network of multi-service point to point network optical transceiver topology cooperates highly beneficially with the annular shaft network, and cost advantage is given prominence to, but need take a large amount of optical fiber, suitable most of users' generally access.Lower than PON cost under some applicable cases, should suit measures to local conditions to adopt in conjunction with concrete condition.

3.PON tree network topology cooperate highly beneficial with the annular shaft network, be that optical fiber enters the most effective Networking Solutions ﹠ provisioned of user resident (FTTP), owing to save a large amount of key fiber resources, long-range seeing is that the ideal that fiberize inserts one of is selected, be fit to most of users' generally access, following potential market is very big.

Wherein, preceding two kinds of technology are widely used at home, and PON (EPON) technology is because its high bandwidth, high reliability and extremely low characteristics such as maintenance cost from once proposing to be considered to splendid FTTP/FTTH solution, have very large development potentiality.

EPON (PON) technology is the optical fiber access technology of a kind of point to multiple spot, and it is made up of the optical line terminal (OLT) of office's side, the optical network unit (ONU) and the Optical Distribution Network (ODN) of user side.General its descending employings TDM broadcast mode, up employing time division multiple access access (TDMA) mode, and can form topological structures (typical structure is a tree structure) such as tree type, star-like, bus-type neatly.So-called " passive " is meant and do not contain any active electronic device and electronic power supply among the ODN, all be made up of optical branching device passive devices such as (Splitter), so the cost of its management maintenance is lower.

At present popular PON standard has based on the APON of ATM agreement with based on the EPON of Ethernet protocol.And the APON technology proposes so far not in commercial achieving success, main cause is that atm technology bearer IP service efficient is low, and EPON is the focus of present various countries development, but there is significant limitation in carrier time division multiplexing (TDM) business, a little less than the carrying TDM professional ability, for the user provides limited bandwidth.

Summary of the invention

For the IP operation efficient that overcomes existing EPON based on Ethernet protocol low, a little less than the carrying TDM professional ability, for the user provides the deficiency of limited bandwidth, the invention provides the GPON GTC framing sublayer that a kind of IP operation efficient height, carrying TDM professional ability are strong, bigger bandwidth is provided for the user based on FPGA.

The technical solution adopted for the present invention to solve the technical problems is:

A kind of GPON transmission convergence layer (GTC) framing sublayer based on FPGA, in described GTC framing sublayer, the data flow of GTC framing sublayer is divided into the up-downgoing two-way to be handled, and downstream data flow is sent to ONU by OLT, separates through the TC layer and sends into adaptation layer after frame is handled; Upstream is that TC layer framing handled the back to the OLT transmission among the user's request information via ONU, and data handling procedure realizes in FPGA, comprising:

At down direction, send frame synchronization module to after the high speed serialization bit stream of 1244Mbit/s and clock signal thereof handled the operating rate that adapts to FPGA through reduction of speed, frame synchronization module according to the Psync field in the PCBd field in the downlink frame by bit the frame head of searching downlink frame to finish frame synchronization; If the back downlink frame data adopts the FEC coding synchronously, it is carried out fec decoder; BIP verification module recomputates BIP according to the data that receive, and compares and check error of transmission with bip field in the downlink frame; After this data enter GTC and separate frame module, downlink data is divided into two-way handles respectively:

One the tunnel is PLOAMd and the Bwmap field is sent into message processing module respectively and authorization handler module is carried out relevant treatment; Authorization module extracts the T-CONT bandwidth allocation information of this ONU from BWmap, the mandate that OLT is distributed is mapped in the ascending time slot: message processing module then extracts the information among the PLOAMd, send into up frame head processing module, the result with authorisation process sends into range finder module simultaneously; Range finder module is handled the message among the PLOAMd, and according to the state exchange of these message and associated control signal control state machine, cooperates OLT to finish the distance measurement function of GPON system simultaneously; Information after the range finding is controlled uplink data frames in conjunction with the result of authorization handler module simultaneously and is sent in the time slot of regulation through T-CONT queue scheduling resume module;

Another circuit-switched data is to separate load that frame module comes out through GTC to enter GEM and separate frame module carries out payload segment subsequently to the GEM frame extraction, sends into the FIFO buffer and transfers to adaptation layer and carry out the conversion of protocol data to service data;

At up direction, data at first become frame module to form the GEM frame through GEM, process information according to up frame head processing module becomes frame module to form the GTC frame by GTC more then, and sends in the up sending time slots of T-CONT queue scheduling module assignment, checks whether carry out the FEC coding when sending.

Technical conceive of the present invention is: GPON transmission convergence sublayer (GTC) is the core and key of whole ONU design.The main task of GTC layer design is to realize the frame synchronization of PON among the ONU, range finding, up access, functions such as encoding and decoding.

The information flow that the GTC layer need be handled is divided into the up-downgoing two-way.Downlink information stream promptly is the light signal that OLT sends to ONU; Uplink information stream is the demand information of ONU process user and the light signal that sends to OLT.Information flow meets the general format of typical data grouping, is divided into frame head and load two parts.

Downlink information stream: downstream rate is 1.244Gbit/s, and frame length is 125us, 19440 bytes.

(1) synchronization field

ONU utilizes 32 long physics synchronization field (Psync) territories of downlink frame to come achieve frame synchronous.According to agreement G.984.3, the value in Psync territory is defined as 0xB6AB31E0.

(2) superframe indication territory

Superframe indication territory (Ident) is as the superframe indication, and value is the beginning of a superframe of indication in 0 o'clock.One has 32.When search condition, ONU is loaded into the superframe counter that receives at Ident in its local counter.Synchronous and the synchronous regime in standard, ONU compares its local value and the Counter Value that receives, and the words of coupling show synchronously, otherwise then show error of transmission or asynchronous.The highest 1 of the Ident territory is used for representing whether preceding paragraph error checking and correction (FEC) just calls descending.The inferior high position in Ident territory keeps.Minimum effective 30 will comprise a counter.

(3) Message Processing territory

Down physical layer oam (PLOAM) message has 13 byte longs, and structure is shown in Fig. 4-5.The purpose ONU of this PLOAM message is represented in optical terminus address (ONU_ID), message addresses (Message ID) is represented the type of this message, and Data represents the load of this PLOAM message, and Cyclic Redundancy Check is the check field in this territory, if CRC check is made mistakes, just abandon this message.

(4) bit interleaved parity sign indicating number territory

The BIP territory is the bit interleaved parity sign indicating number, and length is 8 bits, is used for measuring the quantity of tie point mistake.

(5) descending payload length territory

Descending payload length territory (Plend) is used for the length in bandwidth mapping territory, territory (Bwmap) and the number of load ATM cell are described that in order to strengthen fault-tolerance, Plend occurs twice.Each Plend is 32 bits, is divided into Blen and Alen territory.

(6) bandwidth mapping territory

OLT authorizes each type of service (T-CONT) of ONU by the mapping of the bandwidth in downlink frame territory, territory (BWmap), the length in BWmap territory is 8 * N bytes, the value of N is by the Blen regulation in Plend territory in the downlink frame, SStart and SStop are respectively transmission time started and the dwell time (is unit with the byte) of the T-CONT of ID=Alloc ID, and whether the Flags decision of 12 bits comprises power detection (PLSu), PLOAMu, bandwidth distribution (DBRu) and upstream data in the uplink frame expense whether FEC encodes.

(7) load

GEM territory and data have been comprised in the load.The major function that GEM separates the frame territory is that the payload segment from the GEM frame extracts the Ethernet data bag.ONU filters downlink frame according to the territory, 12 bit port address (Port-ID) that is included in every flag of frame territory, and the frame that belongs to this ONU continues to be delivered to GEM user, does not belong to then being dropped of this ONU.

Uplink information stream: speed uplink also is 1.244Gbit/s, and frame length is 125us, 19440 bytes.The uplink frame header overhead is made up of PLOu (physical layer overhead module), upstream physical layer oam (PLOAMu), power measurement sequence (PLSu) and up dynamic bandwidth report (DBRu), wherein, whether send PLOAMu, PLSu and DBRu by the long Flags decision of the 12bits of downlink frame.

(1) PLOu territory

The PLOu module is made up of five parts: lead code (Preamble), delimiter (Delimiter), parity check territory (BIP), ONU identifier (ONU ID), indication territory (Ind).

(2) PLOAMu territory

Up PLOAM territory is identical with descending PLOAM domain structure.13 byte longs are arranged.ONU ID represents the purpose ONU of this PLOAM message, and Message ID represents the type of this message, and Data represents the load of this PLOAM message, carries out CRC at last and calculates.

(3) PLSu territory

There are 120 byte lengths in the PLSu territory, and it is used for the power control measurement of ONU.

(4) DBRu territory

DBRu comprises DBA territory and CRC territory.This content comprises two parts: CRC check information field and DBA territory.The DBA territory comprises the transmission state of T-CONT in question.

(5) load

The same with ascending load.

The bandwidth of frame head inside mapping territory is set at 2, i.e. Blen=2, and load is reduced to 194 bytes; The PLSu territory abandons earlier, and the key of up-downgoing all saves earlier, realizes a simple uplink and downlink GPON TC convergence-level (GTC) frame.

Based on the GPON framing sublayer program of FPGA, mainly comprise the design of GTC frame structure in the agreement G.984.3, realize the group bag with upstream of unpacking to downstream data flow.Can finally accomplish the emulation and the hardware debug of software based on the design of FPGA.Can see at output and to meet the G.984.3 generation and the decomposition of the frame structure of agreement.Because the particularity of applied environment and the restriction of own level, removed PLSu in the present designed GTC frame emission process of the present invention, the frequency of the signal source output of writing by oneself is f1, and the workload that this significantly reduces also is convenient to utilize FPGA to finish this work.

The required function of finishing in ONU TC layer framing sublayer is a lot, technology is more complicated also, so we adopt modular design method when it designs, function uses an independent module to design, and is convenient to the modification of module like this and does not influence other module.The eda tool that we use is the Quartus II of altera corp, and the chip of selecting for use is the FPGA device of Arria GX series, and the modes such as design by Verilog HDL language, schematic diagram and state machine realize the required function of finishing in framing sublayer.

Whole three bulks that are divided into, 1. input data rate conversion; 2.GTC downlink frame is separated frame; 3.GTC uplink frame framing.Write a GTC downstream signal source according to GTC frame head agreement, give the data rate modular converter with the data of signal source output, the reason of using this module is up to 1.244Gbit/s because of the GPON downstream rate, a reduction of speed process must be arranged, not so FPGA can not be below too high speed steady operation; Give the descending frame module of separating of GTC the GTC downlink data that obtains after the reduction of speed, untie the GTC frame head of packet front, obtain some necessary management information and ascending control information and required packet.Up framing is formed the GTC frame head and is formed uplink frame in conjunction with the packet of required transmission by descending control information of separating frame and encapsulates.Whole invention all is that the debugging of carrying out hardware on the fpga chip of writing and download at the enterprising line program of fpga chip realizes.

Implementation procedure: the descending frame of separating of (1) GTC: the GTC downlink frame is delivered to FPGA by the light oral instructions, because the too high elder generation of transmission digit rate realizes reduction of speed to downlink frame, reach the treatable speed of internal logic, give the descending frame module of separating the later downlink frame of reduction of speed, untie the GTC frame head of packet front, obtain some necessary management information and ascending control information and required packet.(2) the up framing of GTC: up framing comprises PLOu by the descending front end data of separating the control information composition GTC frame of frame, PLOAMu, and DBRu, these up frame heads of GEM are placed on these data the output of the suitable time of front end of load.

Following three kinds of functions are realized in GTC framing sublayer:

(1) multiplex technique reconciliation multiplex technique: PLOAM and GEM part are multiplexed in descending TC frame according to the boundary information that shows at frame head.Every part is extracted from up channel according to an indicating device.

(2) frame head Code And Decode: the TC frame head is encoded in downlink frame and form.Frame head is decoded in uplink frame.And, also carry out Embedded OAM.

(3) based on the inside routing function of Alloc-ID: the route based on Alloc-ID is the data, services that commutes between ATM and GEM TC adapter.

Beneficial effect of the present invention mainly shows: IP operation efficient height, carrying TDM professional ability be strong, provide bigger bandwidth for the user.

Description of drawings

Fig. 1 is the downlink frame frame assumption diagram.

Fig. 2 is the uplink frame frame assumption diagram.

Fig. 3 is the GEM encapsulating structure.

Fig. 4 is a downlink frame top-level functionality structure chart.

Fig. 5 is a uplink frame top-level functionality structure chart.

Fig. 6 is a GEM decapsulation functional structure chart.

Fig. 7 is the descending frame flow chart of separating.

Fig. 8 is up framing flow chart.

Fig. 9 is the integral module block diagram.

Embodiment

Below in conjunction with accompanying drawing the present invention is further described.

With reference to Fig. 1～Fig. 9, a kind of GPON GTC framing sublayer based on FPGA, in described GPON GTC framing sublayer, the data flow of GTC framing sublayer is divided into the up-downgoing two-way and handles, downstream data flow is sent to ONU by OLT, separates through the TC layer and sends into adaptation layer after frame is handled; Upstream is that TC layer framing handled the back to the OLT transmission among the user's request information via ONU, and data handling procedure realizes in FPGA, comprising:

At down direction, send frame synchronization module to after the high speed serialization bit stream of 1244Mbit/s and clock signal thereof handled the operating rate that adapts to FPGA through reduction of speed, frame synchronization module according to the Psync field in the PCBd field in the downlink frame by bit the frame head of searching downlink frame to finish frame synchronization; If the back downlink frame data adopts the FEC coding synchronously, it is carried out fec decoder; BIP verification module recomputates BIP according to the data that receive, and compares and check error of transmission with bip field in the downlink frame; After this data enter GTC and separate frame module, downlink data is divided into two-way handles respectively:

One the tunnel is PLOAMd and the Bwmap field is sent into message processing module respectively and authorization handler module is carried out relevant treatment; Authorization module extracts the T-CONT bandwidth allocation information of this ONU from BWmap, the mandate that OLT is distributed is mapped in the ascending time slot: message processing module then extracts the information among the PLOAMd, send into up frame head processing module, the result with authorisation process sends into range finder module simultaneously; Range finder module is handled the message among the PLOAMd, and according to the state exchange of these message and associated control signal control state machine, cooperates OLT to finish the distance measurement function of GPON system simultaneously; Information after the range finding is controlled uplink data frames in conjunction with the result of authorization handler module simultaneously and is sent in the time slot of regulation through T-CONT queue scheduling resume module;

Another circuit-switched data is to separate load that frame module comes out through GTC to enter GEM and separate frame module carries out payload segment subsequently to the GEM frame extraction, sends into the FIFO buffer and transfers to adaptation layer and carry out the conversion of protocol data to service data;

At up direction, data at first become frame module to form the GEM frame through GEM, process information according to up frame head processing module becomes frame module to form the GTC frame by GTC more then, and sends in the up sending time slots of T-CONT queue scheduling module assignment, checks whether carry out the FEC coding when sending.

The implementation procedure of present embodiment: the descending frame of separating of (1) GTC: the GTC downlink frame is delivered to FPGA by the light oral instructions, because the too high elder generation of transmission digit rate realizes reduction of speed to downlink frame, reach the treatable speed of internal logic, give the descending frame module of separating the later downlink frame of reduction of speed, untie the GTC frame head of packet front, obtain some necessary management information and ascending control information and required packet.(2) the up framing of GTC: up framing comprises PLOu by the descending front end data of separating the control information composition GTC frame of frame, PLOAMu, and DBRu, these up frame heads of GEM are placed on these data the output of the suitable time of front end of load.

Following three kinds of functions are realized in GTC framing sublayer:

(1) multiplex technique reconciliation multiplex technique: PLOAM and GEM part are multiplexed in descending TC frame according to the boundary information that shows at frame head.Every part is extracted from up channel according to an indicating device.

(2) frame head Code And Decode: the TC frame head is encoded in downlink frame and form.Frame head is decoded in uplink frame.And, also carry out Embedded OAM.

(3) based on the inside routing function of Alloc-ID: the route based on Alloc-ID is the data, services that commutes between ATM and GEM TC adapter.

As scheme shown in the l, PCBd is a down physical layer controll block, and OAM(Operation Administration Maintenance)s such as frame synchronization, timing and Dynamic Bandwidth Allocation are provided; Transparent carrying ATM cell of payload segment and GEM frame.ONU obtains information such as synchronous according to PCBd, and filters ATM cell according to the VPI/VCI of ATM cell head, according to the Port-ID filtration GEM frame of GEM frame head.ATM cell and GEM frame are filled in the Payload territory.

Physical layer synchronization (Psync) is 32 fixing when each PCBd begins bit patterns.ONU can utilize this pattern to find the beginning of frame.The decoding in Psync territory is 0xB6AB31E0; Ident is as the superframe indication, and value is the beginning of a superframe of indication in 0 o'clock; PLOAMd is used for bearing downlink PLOAM information; BIP is bit interleaved parity 8 bit code, as error monitoring; Plend is used for illustrating the number of the length and the load ATM cell in BWmap territory, and in order to strengthen fault-tolerance, Plend occurs twice; The BWmap territory is used for upstream bandwidth and distributes, the controlling object of allocated bandwidth is T-CONT, an ONU can distribute a plurality of T-CONT, each T-CONT can comprise a plurality of VPI/VCI or Port-ID with identical qos requirement, this is the notion of introducing in the GPON dynamic bandwidth allocation technology, has improved the efficient of Dynamic Bandwidth Allocation.

As shown in Figure 2, upstream physical layer expense (PLOu) burst synchronization comprises lead code (Preamble), delimiter (Delimiter), parity check territory (BIP), ONU identifier (ONU ID), indication territory (Ind).Its length is provided with when the initialization ONU by OLT, and ONU at first sends the PLOu unit after occupying up channel so that OLT can be fast synchronously and the correct data that receive ONU; Upstream physical layer oam (PLOAMu) is used to carry up PLOAM information, length 13 bytes; Power measurement sequence (PLSu) length 120 bytes are used to adjust luminous power; Up dynamic bandwidth report (DBRu) comprises DBA territory and CRC territory, is used for uplink bandwidth application, totally 5 bytes; ATM cell, GEM frame or DBA report are filled in the Payload territory; The present invention does not load the PLSu territory.

As shown in Figure 3, the GEM frame is that the greatest feature of GPON transmission convergence layer is to have adopted brand-new Transmission Convergence layer protocol.It is made up of the frame head of 5 bytes and the payload of L byte.The GEM frame head comprises five part compositions of the wrong control of head (HEC) of payload length indication (PLI), Port-ID, payload type indication (PTI) and 13 bits.What PLI indicated is the byte length of payload.Because the GEM piece is transmission continuously, so PLI can regard a pointer as, is used to refer to and finds next GEM frame head.PLI is made up of 12 bits, so the payload maximum byte length of back is 4095 bytes.If data surpass this upper limit, GEM will adopt burst mechanism.The Port-ID of 12 bits can provide 4096 different ports, is used to support multiport multiplexing, is equivalent to the VPI among the APON.PTI is used to refer to the type of payload.Whether PTI highest order indication GEM frame is OAM information, and it is congested whether inferior high-order indication user data takes place, and whether the lowest order indication is the end of frame in burst mechanism.HEC has 13 bits, and it provides an EDC error detection and correction function of GEM frame head.HEC is made up of BCH (39,12,2) and one 's parity check bit.In case after frame head is determined, will calculate the bit of receiving with fixing pattern XOR, the result is sent, receiver uses same XOR calculating to recover head.

As shown in Figure 9, whole procedure is divided into descending frame and up framing two large programs separated.The descending frame of separating is a top document with 11, comprises three module: signal, changer and GPON_practice as shown in Figure 4.Signal is the descending auxiliary routine of separating frame, and it is the descending frame service of separating that its effect provides one group of data.The effect reduction of changer receives the speed of downlink frame and downlink frame data is changed into 8 bit data and makes things convenient for inside to separate reading of frame module, and it comprises six module: qq, dc, tq, mem, yanshi, datab.Qq is the LVDS receiver module, and FPGA receives downlink frame by the LVDS mouth, and has changed the arrangement of downlink data, and this moment, data bit became 16 from initial 4.The effect of dc is that the data bit of align-err reverted to original downlink frame data after LVDS was received.The effect of tq is the original position that finds downlink frame according to the downlink frame frame head that it is stipulated in the agreement that.The effect that mem is is that preceding 4 bytes of the downlink frame original position that finds are kept in the register.Yanshi has two, its effect is the time of the later required processing of data time-delay mem of tq, and then in datab, the preceding several bytes in the register are combined again with the byte after delaying time, the datab module has two equally, like this data are changed into two groups 8 downlink frame data, realize the reduction of speed process.Changer is the readiness that whole downlink frame is separated frame, and it provides the data flow of match operation for GPON_practice.

The effect of GPON_practice is to separate the downlink frame frame head, and it comprises ten big module: tqz, deframe, tongbu, Ident, Ploamd, BIP, Plend, de_Bwmap, Bwmap and GEM again.The effect of tqz is the original position that obtains downlink frame behind the reduction of speed.The effect of deframe is that descending frame head is separated by the zone according to byte number, carries out modularization and handles, and gives tongbu respectively, Ident, Ploamd, BIP, Plend, de_Bwmap, Bwmap and GEM.The effect of tongbu is to realize fast synchronously.The effect of Ident is that the value and the local counter of the counter that will receive under synchronous or presynchronization state of ONU made comparisons, identical just expression synchronously, difference is exactly to represent error of transmission or lose synchronously.What Ploamd comprised is some informations.BIP is the bit interleaved parity sign indicating number, and length is 8 bits, is used for measuring the quantity of tie point mistake.The effect of Plend is to be used for illustrating the length in bandwidth mapping territory, territory (Bwmap) and the number of load ATM cell.The effect of De_Bwmap is the length that reads Bwmap according to Plend.The effect of Bwmap is that each type of service (T-CONT) of ONU is authorized, determine transmission time started and the dwell time (is unit with the byte) of T-CONT, whether the Flags decision of 12 bits comprises power detection (PLSu), PLOAMu, bandwidth distribution (DBRu) and upstream data in the uplink frame expense whether FEC encodes.GEM is that GEM separates the frame territory, and its major function is that the payload segment from the GEM frame extracts the Ethernet data bag.As Fig. 7 and shown in Figure 4, the effect of 11.v is that the function synthesized with each module obtains required downlink frame speed together and can unpack this by module for downlink frame data of FPGA operation obtaining required control information and packet.Data are through having finished the reduction of speed of downlink frame data after the processing of changer.v.To be input to GPON_practice.v from the data that changer.v transmits then, find the original position of frame earlier through synchronization module,, then carry out fec decoder, then skip as not needing if the Ident indication will be carried out fec decoder; If indication counter value superframe, not matching with local counter then abandons this frame.Separate the PLOAM information that frame comes out and produce some management and control information thereby the PLOAM module receives.And then compare the BIP territory, and this program adopts comparison method, and different words also will abandon this frame; Identical words enter the length that the Plend module is determined Bwmap and GEM, calculate the reliability of determining downlink frame by the CRC check in the module again, enter the up allocated bandwidth of control signal control that the BWmap module is extracted T-CONT at last.

Up framing is top-level module with frame, comprises 5 modules: PLOu as shown in Figure 5, Ploamu, DBRu, GEM and frameu.PLOu comprises six little module: preamble, de, in, ounu, BIP and PLO again.The effect of Preamble is be used for uplink frame synchronous.The effect of De is the demarcation that is used for uplink frame.Whether the effect of In is the real-time status of report ONU, make mistakes, and whether needs FEC coding and service condition.The effect of Ounu is the ONU_ID of this uplink frame of sign.BIP is the bit interleaved parity sign indicating number, and length is 8 bits, is used for measuring the quantity of tie point mistake.The effect of PLO is that five little modules are combined into PLOu.The effect of Ploamu is to be used to respond the Ploamd information that OLT sends to ONU.The effect of DBRu is the situation of the professional T-CONT of report.The effect of the up framing of GTC is that the function synthesized with each module produces GTC uplink frame data together, as shown in Figure 5 and Figure 8.Data are through PLOu.v, and Ploam.v has finished the encapsulation of uplink frame after the processing of DBRu.v.Encapsulation is added in the last of up frame head through GEM with packet then, finishes the function of whole procedure.

GEM is divided into decapsulation and two parts of encapsulation, is applicable to downlink frame and the uplink frame of GPON.The GEM decapsulation is as an integral module such as Fig. 6, but five little modules can be divided in inside, deGEM.v, bch_decoder.v, GEM_header.v, yanshi.v, payload.v, its effect is that data were through specific GEM decapsulation form after downlink frame was separated frame through GTC, untie the GEM frame head of down load, obtain downlink data packet accurately.The effect of deGEM.v is that the form by the GEM frame head carries out the zone separately, obtains PTI, PLI, Port_ID, the data field of HEC; Bch_decoder.v is exactly the HEC decoding, and its effect is to strengthen safety of data; The effect of GEM_header.v is PTI, PLI, the effect that the agreement that is mapped to the data field of Port_ID reads these three control information that the territory comprises: yanshi.v is the time of the required processing of time-delay GEM_header.v, and the control data bag is removed in the front that makes the data of handling just be added in payload.v on time domain; Payload.v is a complete data bag, and its effect is to send to select, and promptly can send to the user, also can send to webmaster.

The GEM encapsulation is to occur with standalone module, and inside is to separate by the territory, is respectively PTI, PLI, and Port_ID, HEC, payload, its effect is each territory to be combined form the GPON packet of GEM encapsulation.Data process PTI, PLI, Port_ID finishes the GEM encapsulation after the processing of HEC, then payload is added in the last of GEM frame head, finishes the GEM encapsulation.

The present embodiment written program will be carried out hardware debug by Arria GX development board, and the main chip of this development board is fpga chip EP1AGX60DF780C6.Utilize logic analyzer to observe the accuracy of dateout.For the ease of observing, the present invention has designed several special modules and has assisted.

16 outputs of 4 bit data that 4 frequency divider fenp4.v will import, design frequency divider are used for clock and handle.

Data producer signal.v produces downlink frame input data, when overall reset signal rst signal comes, begins to produce data, and per 64 clock conversion once obtain the signal number certificate of protocol compliant.

Data producer test.v produces uplink frame input data, when overall reset signal rst signal comes, begins to produce data, and every clock conversion once obtains the signal number certificate of protocol compliant.

Claims (1)

1, a kind of GPON GTC framing sublayer based on FPGA, it is characterized in that: in described GPONGTC framing sublayer, the data flow of GTC framing sublayer is divided into the up-downgoing two-way to be handled, and downstream data flow is sent to ONU by OLT, separates through the TC layer and sends into adaptation layer after frame is handled; Upstream is that TC layer framing handled the back to the OLT transmission among the user's request information via ONU, and data handling procedure realizes in FPGA, comprising:

At down direction, send frame synchronization module to after the high speed serialization bit stream of 1244Mbit/s and clock signal thereof handled the operating rate that adapts to FPGA through reduction of speed, frame synchronization module according to the Psync field in the PCBd field in the downlink frame by bit the frame head of searching downlink frame to finish frame synchronization; If the back downlink frame data adopts the FEC coding synchronously, it is carried out fec decoder; BIP verification module recomputates BIP according to the data that receive, and compares and check error of transmission with bip field in the downlink frame; After this data enter GTC and separate frame module, downlink data is divided into two-way handles respectively:

One the tunnel is PLOAMd and the Bwmap field is sent into message processing module respectively and authorization handler module is carried out relevant treatment; Authorization module extracts the T-CONT bandwidth allocation information of this ONU from BWmap, the mandate that OLT is distributed is mapped in the ascending time slot: message processing module then extracts the information among the PLOAMd, send into up frame head processing module, the result with authorisation process sends into range finder module simultaneously; Range finder module is handled the message among the PLOAMd, and according to the state exchange of these message and associated control signal control state machine, cooperates OLT to finish the distance measurement function of GPON system simultaneously; Information after the range finding is controlled uplink data frames in conjunction with the result of authorization handler module simultaneously and is sent in the time slot of regulation through T-CONT queue scheduling resume module;

Another circuit-switched data is to separate load that frame module comes out through GTC to enter GEM and separate frame module carries out payload segment subsequently to the GEM frame extraction, sends into the FIFO buffer and transfers to adaptation layer and carry out the conversion of protocol data to service data;

At up direction, data at first become frame module to form the GEM frame through GEM, process information according to up frame head processing module becomes frame module to form the GTC frame by GTC more then, and sends in the up sending time slots of T-CONT queue scheduling module assignment, checks whether carry out the FEC coding when sending.

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