Method and apparatus for onu grouping

Abstract

An apparatus is disclosed for use by an optical line termination (OLT) communicatively connected to an optical network unit (ONU), comprising means for: grouping data units for the optical network unit into one or more groups of encapsulation method (EM) frames, wherein a respective group of one or more EM frames comprises data units addressed to a respective subset of the ONUs, generating a framing sublayer payload comprising at least one particular frame based on the one or more groups of EM frames, wherein the particular frame comprises a length indicator determined relative to a length of one or more groups of one or more EM frames directly following the particular frame and addressed to at least one subset of the ONUs; instructing the ONUs of at least one of the at least one subset to process the EM frames directly following the particular frame, and instructing the ONUs not assigned to the at least one subset to process the EM frames indicated by the length indicator of the particular frame; and transmitting the framing sublayer payload to the ONUs.

Description

Technical Field

[0001] Various example embodiments relate to optical networks, and more particularly to downlink communications. Background Technology

[0002] European patent application No. EP20151843.8 is incorporated herein by reference.

[0003] EP20151843.8 proposes a method for grouping Optical Network Units (ONUs) and allows ONUs in an ONU group to identify data intended for use by the ONUs in that group in the data stream.

[0004] In EP20151843.8, it is required that all ONUs attached to the optical line terminal (OLT) support ONU packetization.

[0005] However, in one example scenario, not all ONUs in the network support ONU grouping.

[0006] According to EP20151843.8, ONU packetization is impossible if not all ONUs in the network support ONU packetization. Summary of the Invention

[0007] The purpose of the embodiments of this disclosure is to implement ONU grouping while maintaining support for ONUs that do not have ONU grouping capabilities.

[0008] According to a first exemplary aspect of this disclosure, this objective is achieved by an apparatus used by an optical line terminal (OLT) communicatively connected to an optical network unit (ONU), comprising components for performing the following operations: grouping data units for the ONU into groups of one or more encapsulation method EM frames, wherein a corresponding group of one or more EM frames includes data units addressed to a corresponding subset of the ONU; generating a framing sublayer payload comprising at least one specific frame based on the group of one or more EM frames, wherein the specific frame includes a length indicator that is determined relative to the length of one or more groups of one or more EM frames that directly follow the specific frame and address to at least one subset of the ONU; instructing ONUs in at least one subset of the at least one subset to process EM frames that directly follow the specific frame, and instructing ONUs in no subset of the at least one subset to process EM frames indicated by the length indicator of the specific frame; and transmitting the framing sublayer payload to the ONU.

[0009] In one embodiment, a specific frame is a special EM frame that includes an EM header and zero payload.

[0010] In one embodiment, the length indicator is included in the payload length indicator field of the EM header of a special EM frame.

[0011] In one embodiment, the specific frame further includes response information for instructing ONU processing of at least one subset of the at least one subset to directly follow the specific frame in an EM frame, and / or instructing ONU processing of an EM frame not assigned to at least one subset to be indicated by the length indicator of the specific frame.

[0012] In one embodiment, the response information is included in the port-ID field or option field of the EM header of a specific EM frame.

[0013] In one embodiment, a specific frame includes a subset indicator that indicates a subset, and a length indicator is determined relative to the length of a group of one or more EM frames that directly follow the specific frame and are addressed to a subset of the ONU indicated in the subset indicator, or relative to the length of one or more groups of one or more EM frames that directly follow the specific frame and are not addressed to a subset of the ONU indicated in the subset indicator.

[0014] In one embodiment, a specific frame includes at least one of the following: an ONU indicator with an invalid value, an unassigned ONU indicator, or an ONU indicator indicating an ONU that is different from the ONU assigned to a subset of ONUs addressed by a group of one or more EM frames preceding the specific frame, and wherein a length indicator is determined relative to the length of one or more groups of one or more EM frames that directly follow the specific frame and do not address to a subset of ONUs addressed by a group of one or more EM frames preceding the specific frame.

[0015] In one embodiment, the component is further configured to transmit to the corresponding ONU an indication of the start position of a group of one or more EM frames corresponding to the subset to which it is assigned.

[0016] In one embodiment, at least one group of one or more EM frames is transmitted using a predetermined modulation format and / or encoded using a predetermined FEC code, and at least another group of one or more EM frames is transmitted using a different modulation format and / or encoded using a different FEC code.

[0017] In one embodiment, the component is further configured to transmit to the corresponding ONU a subset identifier to which it is assigned.

[0018] According to a second aspect of this disclosure, an apparatus is provided for use by an optical network unit (ONU) communicatively connected to an optical line terminal (OLT), comprising components for performing the following operations: receiving a framing sublayer payload from the OLT; obtaining a specific frame included in the framing sublayer payload, wherein the specific frame includes a length indicator relating to the length of one or more groups of one or more EM frames that directly follow a specific frame addressed to the ONU; if the ONU is assigned to the at least one subset, then, as instructed by the OLT, determining the next EM frame to be processed as the EM frame that directly follows the specific frame, or if the ONU is not assigned to the at least one subset, determining the next EM frame to be processed as the EM frame indicated by the length indicator of the specific frame.

[0019] In one embodiment, the component is further configured to: determine the next EM frame to be processed based on a special configuration regarding the ONU group, wherein the special configuration regarding the ONU group includes at least one of the following: a subset identifier of the subset to which the corresponding ONU is assigned or an indication of the start position of a group of one or more EM frames corresponding to the subset to which it is assigned.

[0020] In one embodiment, the component is also configured to receive special configurations regarding ONU packets from the OLT (110).

[0021] According to a third aspect of this disclosure, a method is provided for use by an optical line terminal (OLT) communicatively connected to an optical network unit (ONU), comprising: grouping data units for the ONU into groups of one or more encapsulation method (EM) frames, wherein a corresponding group of the one or more EM frames includes data units addressed to a corresponding subset of the ONU; generating a framing sublayer payload including at least one specific frame based on the group of the one or more EM frames, wherein the specific frame includes a length indicator, the length indicator being determined relative to the length of one or more groups of one or more EM frames that directly follow the specific frame and address to at least one subset of the ONU; instructing ONUs in at least one subset of the at least one subset to process EM frames that directly follow the specific frame, and instructing ONUs in no subset of the at least one subset to process EM frames indicated by the length indicator of the specific frame; and transmitting the framing sublayer payload to the ONU.

[0022] According to a fourth aspect of this disclosure, a method is provided for use by an optical network unit (ONU) communicatively connected to an optical line terminal (OLT), comprising: receiving a framing sublayer payload from the OLT; obtaining a specific frame included in the framing sublayer payload, wherein the specific frame includes a length indicator related to the length of one or more groups of one or more EM frames that directly follow a specific frame addressed to the ONU; if the ONU is assigned to the at least one subset, then, as instructed by the OLT, determining the next EM frame to be processed as the EM frame that directly follows the specific frame, or if the ONU is not assigned to the at least one subset, determining the next EM frame to be processed as the EM frame indicated by the length indicator of the specific frame.

[0023] Various example embodiments of the first example aspect can be applied as example embodiments to other example aspects.

[0024] According to various embodiments, ONU grouping can be implemented without explicitly supporting the presence of an ONU grouping. Furthermore, ONU grouping can be implemented with greater flexibility.

[0025] Furthermore, ONU grouping can be implemented without a strict distinction between codewords and EM frames. This allows for the removal of coupling between the service adaptation sublayer and the physical adaptation sublayer. Attached Figure Description

[0026] To gain a more complete understanding of exemplary embodiments of the present invention, reference is now made to the following description taken in conjunction with the accompanying drawings, wherein:

[0027] Figure 1 A portion of an example communication network in which the disclosed embodiments can be applied is shown;

[0028] Figure 2 An example structure of the framework according to EP20151843.8 is shown;

[0029] Figure 3 An example structure of the framework according to an example embodiment is shown;

[0030] Figure 4 Example behavior of a device used by an OLT according to an example embodiment is shown;

[0031] Figure 5 Example behavior of a device used by an ONU according to an example embodiment is shown;

[0032] Figure 6 An example structure of a framework according to another embodiment is shown;

[0033] Figure 7Example embodiments of suitable computing systems for performing one or more steps in various embodiments are shown;

[0034] Figure 8 An example method 800 is shown, incorporating aspects of an example embodiment;

[0035] Figure 9 Another example method 900 combining aspects of the example embodiment is shown. Detailed Implementation

[0036] Example embodiments of this application are described in detail herein and illustrated by way of example in the accompanying drawings. It should be understood that although specific embodiments are discussed herein, it is not intended to limit the scope of the invention to these embodiments. Rather, it should be understood that the embodiments discussed herein are for illustrative purposes and modified and alternative embodiments may be implemented without departing from the scope of the invention as defined in the claims. The order of method steps is not limited to a particular embodiment, and the method steps may be performed in other possible orders. Similarly, the specific structural and functional details disclosed herein are for the purpose of describing embodiments only. However, the invention described herein can be implemented in many alternative forms and should not be construed as being limited to the embodiments set forth herein.

[0037] Figure 1 A portion of an exemplary communication network in which examples of the disclosed embodiments can be applied is shown.

[0038] like Figure 1 As shown, in the Passive Optical Network (PON) 100, the network-side OLT 110 is used to connect multiple ONUs 131, 132, ..., 133 on the user side via an Optical Distribution Network (ODN) or an optical fiber facility 120 containing optical fibers and splitters but not active components. Those skilled in the art should understand that the number of ONUs is not limited to the given example. The OLT 110 can be connected to, for example, up to 64 ONUs.

[0039] Most PON technologies, such as G-PON, E-PON, and XG(S)-PON, are time-division multiplexing (TDM) PON technologies, in which the fiber medium is shared in time among different ONUs. In addition, there are time-division and wavelength-division multiplexing (TWDM) PON technologies, such as the next-generation NG-PON2, in which multiple TDM systems of different wavelengths are stacked on the same PON system. Example embodiments apply to both TDM and TWDM PON systems.

[0040] EP20151843.8 proposes a method for ONU grouping and allows ONUs in an ONU group to identify data for the ONUs in that group in the data stream.

[0041] Figure 2 An example structure of the framework according to EP20151843.8 is shown.

[0042] exist Figure 2 In the example shown, ONUs are divided into two subsets. For example, ONUs 131 and 132 can be assigned to group 1, and ONU 133 is assigned to group 2.

[0043] Data units addressed to ONUs assigned to group 1 are grouped together to form EM frames and marked with dashed lines. Data units addressed to ONUs assigned to group 2 are grouped together to form a set of EM frames and marked with diagonal stripes. Although not shown in the figure, data units can have various sizes. The last data unit in each group can be fragmented.

[0044] Then, as part of the framing sublayer (FS) payload, the EM frames addressed to Group 1 are encoded and modulated into a set of non-return-to-zero (NRZ) codewords, also marked with a dashed pattern, and the EM frames addressed to Group 2 are encoded and modulated into a set of 4-level pulse amplitude modulation (PAM4) codewords, also marked with diagonal stripes.

[0045] exist Figure 2 In the example shown, the ONU assigned to group 1 receives the following: Figure 2 The third row shows the FS payload. In the FS payload, the FS payload corresponding to the NRZ codeword set is demodulated and decoded, and is marked with a dashed pattern. Because the ONUs assigned to group 1 do not need to decode the PAM4 codewords, the PAM4 codewords in the obtained FS payload may not be decoded or may be incorrectly decoded. The PAM4 codewords are irrelevant to the ONUs assigned to group 1, therefore... Figure 2 The corresponding FS payload in the third line is marked as blank.

[0046] Similarly, ONUs assigned to group 2 (e.g., ONU 133) receive the following: Figure 2 The second row shows the FS payload. In the FS payload, the FS payload corresponding to the PAM4 codeword set is decoded and marked with diagonal stripes. Because the ONUs assigned to group 2 do not need to decode the NRZ codewords, the NRZ codewords in the obtained FS payload may not be decoded or may be incorrectly decoded. The NRZ codewords are irrelevant to the ONUs assigned to group 2, therefore... Figure 2 The corresponding FS payload in the second line is marked as blank.

[0047] like Figure 2 As shown, there is a strict distinction between EM framing and encoding. The alignment between EM framing and encoding leads to dependencies or relationships that complicate the processing.

[0048] Furthermore, according to EP20151843.8, all ONUs attached to the OLT need to support ONU grouping. For example, each ONU needs to know subset information such as assignment patterns in order to be able to locate data units for the subset to which it has been assigned.

[0049] However, in one example scenario, not all ONUs in the network support ONU packetization. Therefore, an improved apparatus and method are needed to implement ONU packetization in a way that is compatible with ONUs that do not support ONU packetization.

[0050] Figure 3 An example structure of the framework according to an example embodiment is shown.

[0051] exist Figure 3 In the example shown, the ONUs are also grouped into two subsets. For example, group 1 may include ONUs compliant with the first version of G.hsp.com TC (ITU-T G.9804.2), meaning they may not be aware of the specific configuration regarding ONU grouping. Group 2 may include ONUs that are aware of the specific configuration regarding ONU grouping. The specific configuration regarding ONU grouping may include at least one of the following: the subset identifier of the subset to which the corresponding ONU is assigned, or the start position of the group of one or more EM frames corresponding to the subset to which it is assigned, which will be referred to below. Figure 6 This will be explained. Specific configurations for ONU groups can be sent from the OLT to the ONU or configured manually within the ONU.

[0052] An OLT (e.g., an embodiment in which examples of the disclosed embodiments can be applied) implements an example of an apparatus. Figure 1 The OLT 110) groups the data units of the ONU into groups of one or more EM frames, where each group of one or more EM frames includes a subset of data units addressed to the corresponding ONU. Figure 2 Similar to the example in the example, data units addressed to ONUs assigned to group 1 are grouped together to form a set of EM frames marked with dashed lines. Data units addressed to ONUs assigned to group 2 are grouped together to form a set of EM frames marked with diagonal stripes. Likewise, data units can have various sizes. The last data unit in each group can be fragmented.

[0053] Then, the OLT 110 generates the FS payload based on groups of one or more EM frames. Specifically, in Figure 3In the illustrated embodiment, prior to the expected data unit assigned to the ONU of group 2, there is a specific frame marked by a horizontal stripe included in the FS payload. The specific frame includes a length indicator that is determined relative to the length of the group of EM frames that directly follow the specific frame and are assigned to the ONU of group 2.

[0054] In one embodiment, a specific frame is a special EM frame that includes an EM header and zero payload. In G.hsp.comTC, the EM header acts as a linked list: each EM header indicates its payload length (PLI), which the ONU can use to locate the next header in the bitstream. This allows the ONU to easily locate EM headers one by one within a frame and retrieve payload data from EM packets with matching port-IDs.

[0055] In one embodiment, the length indicator is included in the Payload Length Indicator (PLI) field of the EM header of a special EM frame.

[0056] In other examples, different structures (e.g., new message structures) can be used for specific frames while still having the same functionality.

[0057] In one embodiment, the specific frame further includes response information used to instruct ONUs assigned to at least a subset of one or more subsets of one or more groups of one or more EM frames (whose length is indicated in the length indicator of the specific frame) to process EM frames that directly follow the specific frame, and instructs ONUs not assigned to said one or more subsets to process EM frames indicated by the length indicator of the specific frame. Those skilled in the art will understand that "processing an EM frame" does not necessarily mean processing the entire EM frame, but can be limited to processing only the header of the EM frame, for example, depending on the ONU ID in that header.

[0058] In one embodiment, the response information is included in the port-ID field or option field of the EM header of a special EM frame.

[0059] Specifically, in Figure 3 In the illustrated embodiment, a subset indicator may be included in the port-ID field of the EM header of a specific EM frame. The subset indicator may indicate group 2, i.e., a subset of ONUs addressed by the EM frame group that directly follows the specific frame. A length indicator included in the specific frame indicates the length of the group of EM frames that directly follow the specific frame and are addressed to group 2, i.e., the subset of ONUs indicated in the subset indicator.

[0060] Figure 4 Example behavior of a device used by an OLT according to an example embodiment is shown.

[0061] like Figure 4 As shown, OLT 110 can begin constructing an FS frame in step S410, and then initialize the current group to a (fixed or variable) group g in step S420. OLT 110 can determine in step S430 whether the current group of the frame is complete. This determination can be based on the grouping of EM frames in previous steps. Alternatively, this determination can be based on the ingress or queue information of the current or other groups of the frame. Alternatively, this determination can be based on achieving the desired length for that group of frames. The last frame in the group can be fragmented.

[0062] If OLT 110 determines that the current group of frames is not complete, it can insert the next EM frame in step S450.

[0063] If OLT 110 determines that the current group of frames has been completed, then in step S440, it can proceed as described in reference... Figure 3 And below Figure 6 The specific frame is inserted as described, and the current group is set as the group for the next EM group. Then, in step S450, OLT 110 can insert the next EM frame.

[0064] If OLT 110 determines in step S460 that the end of the FS frame has not been reached, it can continue to step S430. If the end of the FS frame has been reached, then in step S470, the FS frame ends.

[0065] After generating the FS payload, the OLT 110 sends the FS payload to the ONU. The OLT can begin transmitting the FS payload before the complete FS frame is generated.

[0066] Specifically, still refer to Figure 3 As part of the FS payload, the EM frames intended for ONUs assigned to Group 1, preceding the EM frames intended for ONUs assigned to Group 2, can then be encoded using predetermined FEC codes and modulated into a set of NRZ codewords, also marked with dashed patterns. A portion of the EM frames intended for ONUs assigned to Group 2 can be encoded using different FEC codes and modulated using different modulation formats (e.g., PAM4) into a set of PAM4 codewords, also marked with diagonal stripes. In cases where different FEC codes and / or different modulation formats result in different information rates, the length indicated by the length indicator can be used to compensate for differences in information rates between groups of one or more EM frames (e.g., EM frames assigned to ONUs in Groups 1 and 2) transmitted using different modulation formats and / or encoded using different FEC codes.

[0067] In another example, all EM frames may also be encoded and / or modulated in the same way.

[0068] Those skilled in the art will understand that the codewords of the two sets can be bit-interleaved before being sent to the ONU.

[0069] After receiving the codeword stream, the ONU assigned to group 1 can demodulate the NRZ codewords and then decode them according to the predetermined FEC code, thereby obtaining... Figure 3 The third row shows the FS payload. Since such an ONU (e.g., ONU131) may not know the specific configuration regarding the ONU group, the codeword using PAM4 encoding will be decoded into an incorrect payload, using vertical striping. Meanwhile, because the specific frame preceding the EM frame assigned to the ONU in group 2 is encoded using a predetermined FEC code, it can be decoded correctly.

[0070] The ONU 131 assigned to Group 1 can determine that a subset indicator in a specific frame does not match its own ONU port-ID, thus allowing it to skip erroneous payloads based on the length indicator included in the specific frame, thereby locating the next regular EM header expected for Group 1, such as... Figure 3 The link arrows around the FS payload in the third line are shown.

[0071] Therefore, various embodiments can implement ONU grouping in a manner compatible with ONUs that do not explicitly support ONU grouping, such as ONUs compatible with the first version of G.hsp.comTC.

[0072] In another example, ONU 132 assigned to group 1 can know the specific configuration of the ONU group, and it can also determine that the subset indicator in a particular frame does not match its subset ID, and then determine the next EM frame to be processed as the EM frame indicated by the length indicator of the particular frame.

[0073] Therefore, the length indicator in a specific frame allows the ONU (even traditional G.hsp.comTC-compatible ONUs) to locate the corresponding group ( Figure 3 The next regular EM header of group 1) in the illustrated embodiment is assigned to an intermittent EM packet of another group, even if the ONU cannot decode or otherwise interpret the payload in the segment of another ONU group.

[0074] After receiving the codeword stream, the ONU (e.g., ONU 133) assigned to group 2, implementing the apparatus in which the examples of the disclosed embodiments can be applied, knows the special configuration of the ONU group. This ONU can demodulate PAM4 codewords and NRZ codewords, and then decode the codewords according to the FEC code used to encode the corresponding codewords, thereby obtaining... Figure 3 The second line shows the FS payload.

[0075] Typically, after the ONU reads a specific frame included in the FS payload, if the ONU is assigned to at least one subset addressed by one or more groups of one or more EM frames (whose length is indicated in the length indicator of the specific frame), the ONU determines the next EM frame to be processed as the EM frame directly following the specific frame. Alternatively, if the ONU is not assigned to at least one subset, it determines the next EM frame to be processed as the EM frame indicated by the length indicator of the specific frame.

[0076] Specifically, when ONU 133 assigned to group 2 determines that the subset indicator in a particular frame matches its own subset ID, this means that the frame immediately following the particular frame is expected to be used for its subset. It can ignore the length indicator of the particular frame and locate the next EM header immediately following the particular frame.

[0077] In one embodiment, the OLT can transmit the subset identifier of the subset to which it is assigned to the corresponding ONU. For example, assignment is accomplished by associating the subset ID with the subset of the ONU, and then the OLT transmits the subset ID to the ONU assigned to that subset, for example, using unicast physical layer operation management and management PLOAM messages.

[0078] Alternatively, ONU group and subset identifiers can be fixed or manually configured.

[0079] Despite Figure 3 In the example shown, the ONUs are grouped into only two subsets; however, those skilled in the art will understand that in other examples, the ONUs may be grouped into more than two subsets. In such cases, the structure of the FS payload can be adjusted accordingly. For simplicity, this will not be elaborated upon here. Alternatively, any particular ONU may be assigned to more than one subset.

[0080] Figure 5 Example behavior of a device used by an ONU according to an example embodiment is shown.

[0081] like Figure 5 As shown, the ONU can obtain the EM header in step S510, and then determine in step S520 whether the port-ID in the EM header corresponds to a port-ID in the ONU's port-IDs. If the ONU determines that the port-ID in the EM header matches a port-ID in its ONU port-IDs, it means that this EM frame is intended for it. In step S530, the ONU then processes the payload following the EM header.

[0082] If the ONU determines that the port-ID in the EM header does not match one of its ONU port-IDs, then in step S540, it further determines whether the port-ID in the EM header corresponds to a subset ID of the subset ID to which it is assigned.

[0083] If the port-ID in the EM header matches a subset ID of the subset assigned to it, it means that the current EM frame is a specific frame, and the EM frame that directly follows the specific frame is expected to be used for its subset. In step S550, the ONU may ignore the length indicator of the specific frame, obtain the next EM header that directly follows the current EM header, and further proceed to step S520.

[0084] If the port-ID in the EM header does not match one of the subset IDs of the subset to which it is assigned, the ONU can skip the payload following the EM header indicated by the length indicator of the current EM header and proceed to step S520.

[0085] Figure 6 An example structure of a framework according to another embodiment is shown.

[0086] exist Figure 6 In the example shown, the ONU grouping is similar to the reference. Figure 3 The description is as described, and will not be repeated here.

[0087] OLTs that implement examples of the disclosed embodiments in which the disclosed embodiments can be applied (e.g.) Figure 1 The OLT 110) groups the data units of the ONU into groups of one or more EM frames, where each group of one or more EM frames includes a subset of data units addressed to the corresponding ONU. Figure 3 Similar to the example in the example, data units addressed to ONUs assigned to group 1 are grouped together to form a set of EM frames marked with a dashed pattern. Data units addressed to ONUs assigned to group 2 are grouped together to form a set of EM frames marked with diagonal stripes.

[0088] Then, the OLT 110 generates the FS payload based on groups of one or more EM frames. Specifically, in Figure 6In the illustrated embodiment, after a predetermined data unit assigned to the ONU of group 1 and before a predetermined data unit assigned to the ONU of group 2, there exists a first specific frame marked with a horizontal stripe included in the FS payload. The first specific frame includes a length indicator that is determined relative to the length of the group of EM frames that immediately follow the first specific frame and are assigned to the ONU of group 2. A second specific frame, also marked with a horizontal stripe, exists after a data unit assigned to the ONU of group 2 and before a data unit assigned to the ONU of group 1. The second specific frame includes a length indicator that is determined relative to the length of the group of EM frames that immediately follow the second specific frame and are expected to be used for assignment to the ONU of group 1.

[0089] The first specific frame may include a subset indicator of indicator group 1, that is, a subset of ONUs group-addressed by the EM frames preceding the specific frame. The second specific frame may include a subset indicator of indicator group 2.

[0090] Alternatively, any or all specific frames may include at least one of the following: an ONU indicator with an invalid value, an unassigned ONU indicator, or an ONU indicator indicating an ONU that is different from the subset of ONUs assigned to group-addressed by one or more preceding EM frames. For example, any or all specific frames may include an invalid value in the port-ID field of a special EM header.

[0091] Typically, response information selected from subset indicators, unassigned ONU indicators, ONU indicators, or ONU indicators with invalid values ​​can be used to instruct ONUs that are not assigned to a subset of ONUs addressed by a group of one or more EM frames (whose length is indicated in the length indicator) to process the EM frame indicated by the length indicator of the specific frame.

[0092] In another embodiment, the ONUs can be grouped into more than two groups. A length indicator can then be determined relative to the length of a group of EM frames that directly follows the specific frame and does not address a subset of ONUs addressed by groups of one or more EM frames preceding the specific frame. For example, the length indicator can indicate the combined length of more than one group.

[0093] After the FS payload is generated, the OLT 110 sends the FS payload to the ONU. Those skilled in the art will understand, as referenced... Figure 3 The same encoding / decoding can be used for two ONU groups, or different modulation and / or FEC codes can be used for different groups. If the same modulation / FEC code is used, the ONUs in both groups will receive the same FS payload, such as... Figure 6As shown. If different modulation / FEC codes are used, the payload of one group will be incorrect for another group, as referenced. Figure 3 The explanation given.

[0094] In obtaining such Figure 6 Following the FS payload shown in the first line, the ONU assigned to group 1 (e.g., ONU131) can locate the next EM header based on the PLI field of the current EM header, and determine the payload to process the EM frame when the port-ID in the EM header matches its own ONU port-ID. It can locate the EM header by following the link arrow below the FS payload.

[0095] In one example, ONU 131 assigned to group 1 may not be aware of the specific configuration of the ONU group. When it reads the first specific frame, it determines that the subset indicator in the first specific frame (alternatively, an unassigned ONU indicator, an ONU indicator, or an invalid value) does not match its own ONU port-ID, and it will skip subsequent EM frames based on the length indicator included in the first specific frame.

[0096] In another example, the ONU 132 assigned to group 1 can know the specific configuration of the ONU group, and it can also determine that the subset indicator in a particular frame matches its subset ID, and then determine the next EM frame to be processed as the EM frame indicated by the length indicator of the particular frame. For example, knowing these can be advantageous for clock recovery, equalization tracking, and / or incrementing of counters used for forward error correction.

[0097] In an example where a specific frame includes a subset indicator that indicates a subset, the next EM frame to be processed can be further determined based on predetermined rules. These predetermined rules indicate the next EM frame to be processed when the ONU is assigned to the subset indicated in the subset indicator. For example, in... Figure 3 In the example shown, if the subset indicator in a specific frame matches the subset ID to which the ONU is assigned, a predefined rule can instruct the ONU to process the EM frame that directly follows the specific frame as the next EM frame. And... Figure 6 In the example shown, if the subset indicator in a specific frame matches the subset ID to which the ONU is assigned, a predefined rule can instruct the ONU to process the EM frame indicated by the length indicator of the specific frame as the next EM frame. The predefined rule can be configured manually or transmitted from the OLT to the ONU.

[0098] In one embodiment, the OLT 110 can transmit to the corresponding ONU an indication of the start position of a group of one or more EM frames corresponding to the subset to which it has been assigned. For example, the start position of the corresponding group can be included in the FS header. In another example, the start position of the corresponding group can be transmitted via a control message such as a PLOAM message or an ONU management and control interface OMCI message. This information is then used by the corresponding ONU to locate its associated EM frame. In this way, an ONU assigned to at least one subset of one or more EM frames addressed by one or more groups (the length of which is indicated in the length indicator of the specific frame) is instructed to process the EM frame directly following the specific frame.

[0099] Therefore, ONU 133 assigned to group 2 can start from the first EM header corresponding to group 2, and follow... Figure 6 The first line shows the link arrow above the FS payload. When the ONU 133 assigned to group 2 reads the second specific frame, it determines that the subset indicator in the second specific frame matches its own subset ID (alternatively, including unassigned ONU indicators, ONU indicators, or invalid values ​​in the second specific frame that do not match their own ONU port-ID). This means that subsequent EM frames whose length is indicated in the length indicator of the specific frame are not addressed to the subset to which they were assigned. In this case, it will skip the following EM frame based on the length indicator included in the second specific frame.

[0100] exist Figure 6 In the example, ONU 131 assigned to group 1 does not read the second specific frame because the length indicator in the first specific frame directs ONU 131 assigned to group 1 to the next EM header for group 1. Similarly, ONU 133 assigned to group 2 does not read the first specific frame because ONU 133 assigned to group 2 starts after the first specific frame, and the length indicator in the second specific frame directs ONU 133 assigned to group 2 directly to the next EM header for group 2.

[0101] In another example, a particular frame may not contain any response information, but only a length indicator. In this case, based on the length indicator included in the particular frame, any ONU processing that frame can always skip the following EM frame. This is for Figure 6 Examples are possible because any particular frame is only processed by a subset of the ONU, and that subset of the ONU should not process the following EM frame indicated by the length indicator.

[0102] In this way, each subset of ONUs can have a linked list of its separate EM headers. The length indicator in a particular frame points to the next EM header for the subset of ONUs addressed by the previous EM frame; therefore, the length indicator can be the sum of the lengths of more than one ONU segment.

[0103] The advantage of this embodiment is that all ONUs can process a specific frame in the same way, while... Figure 3 In this implementation, compared to Group 1 ONUs, Group 2 ONUs require different behavior for a given frame. This embodiment is particularly useful if different ONU groups use different FECs or modulations, as it avoids rapid context switching in the digital receiver chain.

[0104] Specifically, in embodiments where no subset indicator or at least one of the following is included in any or all specific frames: an ONU indicator with an invalid value, an unassigned ONU indicator, or an ONU indicator of an ONU that indicates a subset of group-addressed ONUs different from those assigned to one or more EM frames preceding the specific frame, the ONU does not need to determine whether the port-ID in the EM header corresponds to a subset ID of the subset to which it is assigned, such as... Figure 5 As stated in [the document], it is not even necessary to assign any subset IDs.

[0105] Alternatively, instead of transmitting the start position to the ONU, a specific frame is positioned immediately after the framing sublayer header in the framing sublayer frame that includes the framing sublayer payload. That is, the first EM frame in the FS frame can be a specific frame.

[0106] The advantage of this method is that it does not require pre-transmitting the start position of each subset of ONUs in the frame. In this embodiment, a length indicator is determined relative to the length of a single ONU segment. All ONUs read the first specific frame. Afterward, different subsets can read different headers.

[0107] One of the original use cases for ONU grouping is energy efficiency. Here, multiple ONU groups are created, and ONUs in a group are allowed to shut down some functions while a transfer to another group is in progress. For example, an ONU assigned to group 2 will be able to 'sleep' during the load period for an ONU in group 1. Energy saving can be achieved, in particular, by avoiding LDPC decoding. Therefore, for this use case, preferably, for example in Figure 3 The portion marked with vertical stripes contains one or more full codewords. Those skilled in the art will understand that this also applies to the reference. Figure 6Example of the description. Advantageously, one or more complete FEC CWs are respectively included in the dashed-line marked portion and / or the portion marked with diagonal stripes. Therefore, ONUs not assigned to a subset of frames group-addressed can avoid decoding complete codewords that are not intended for them. This method is transparent to conventional G.hsp.comTC-compatible ONUs.

[0108] Another use case for ONU grouping is to differentiate coding and / or modulation based on channel characteristics or ONU capabilities. Using a flexible FEC, various code rates are defined to allow ONUs to achieve higher throughput (high code rate) or cover a larger optical loss budget (lower code rate) for ONUs supporting these code rates. Here, a traditional G.hsp.comTC-compatible ONU can only decode codewords using conventional LDPC codes with a code rate of 0.84 as defined in the first version of G.hsp.comTC. This completely falls into... Figure 3 Codewords within segments marked with vertical stripes can be encoded using the coderate assigned to that group, while codewords falling only partially within segments marked with vertical stripes are encoded using the regular coderate. A specific frame is entirely contained within regularly encoded codewords, allowing the traditional ONU to know the start of the next EM frame even if some intermediate codewords are corrupted. Similarly, in Figure 3 The EM header of the first EM frame, following the portion marked with vertical stripes, is in the regularly encoded codeword.

[0109] Codewords can all be of equal length, or alternatively, an integer N of regular codewords can be replaced by an integer M of alternative codewords. For example, if the length of the alternative codewords is 2 / 3 of the length of the regular codewords, then M = 3 alternative codewords can replace N = 2 regular codewords.

[0110] The use cases for flexible modulation are similar to those for flexible FEC, but different modulation formats can be used instead of different FEC code rates. 100Gbps PAM4 is a 50Gbaud modulation format, so a traditional G.hsp.comTC-compatible ONU can maintain its clock and data recovery, including equalization, while receiving PAM4 symbols. When block bit interleaving across D codewords is applied, preferably, all D CWs in the block use the same modulation format to avoid error propagation in DFE-like equalizers that can be applied to traditional G.hsp.comTC ONUs. If the ONU group payload boundaries are mapped to PAM-4 codeword boundaries, i.e. Figure 3 The part marked with vertical stripes corresponds to Figure 3 The section marked with diagonal stripes further simplifies the ONU implementation. Specific headers must fall within the NRZ section so that the NRZ ONU can maintain the linked list. Therefore, specific frames are located at the end (or near the end) of the NRZ section, such as... Figure 6As shown.

[0111] There are several advantages to applying ONU packetization without flexible FEC or flexible modulation (i.e., in a conventional PON system):

[0112] Decoupling ONU packets from FEC codewords: Utilizing framing according to various embodiments, information about which data corresponds to which group is fully contained within a specific frame, and how they are placed. This allows for the decoupling of ONU packets from FEC codewords. In other words, switching between different groups is not limited to occurring at the edges of FEC codewords, but can occur anywhere. This addresses one of the problems in EP20151843.8, where the necessary alignment between EM packets and FEC codewords of different groups leads to coupling between the protocol's service adaptation sublayer (where EM frames are generated) and physical adaptation sublayer (where FEC codewords are generated), which complicates processing.

[0113] Greater flexibility: In EP20151843.8, FEC codewords are assigned to groups using a pre-transmitted pattern. In this disclosure, there is no obligation to have a static pattern. During frame construction, the OLT can choose to switch between groups as needed. This can be managed by a specific frame (which indicates the switching between groups) and can be included during frame construction. Note the additional advantage of not having to transmit mappings, i.e., ... This flexibility also... Figure 6 As shown in the diagram.

[0114] In the case of flexible FEC / modulation, the OLT can still pre-transmit which part of the frame uses which FEC / modulation to the ONU. In this case, it is advantageous to still use the alignment of ONU groups with FEC codewords as in EP20151843.8 and pre-transmit the assignment.

[0115] Various embodiments can be applied to time-division multiplexing, TDM, and PON technologies, such as gigabit PON, G-PON, Ethernet PON, E-PON, 10 gigabit symmetrical PON, XGS-PON, and higher-speed PON. Furthermore, the proposed technology can also be applied to time-division and wavelength-division multiplexing, TWDM, and PON technologies, where TDM systems of different wavelengths are stacked on the same PON system. Then, one or more wavelengths in the TWDM PON system operate according to this disclosure.

[0116] Figure 7A computing system 700 is illustrated, comprising at least one processor and at least one memory including computer program code, the at least one memory and the computer program code being configured to cause execution of the device together with the at least one processor. The computing system 700 can generally be configured as a suitable general-purpose computer and includes a bus 710, a processor 702, local memory 704, one or more optional input interfaces 714, one or more optional output interfaces 716, a communication interface 712, a storage element interface 706, and one or more storage elements 708. The bus 710 may include one or more wires allowing communication between components of the computing system 700. The processor 702 may include any type of conventional processor or microprocessor that interprets and executes programmed instructions. The local memory 704 may include random access memory (RAM) or another type of dynamic storage device storing information and instructions executed by the processor 702 and / or read-only memory (ROM) or another type of static storage device storing static information and instructions used by the processor 702. Input interface 714 may include one or more conventional mechanisms that allow an operator or user to input information into computing device 700, such as a keyboard 720, mouse 730, pen, voice identification and / or biometric mechanisms, camera, etc. Output interface 716 may include one or more conventional mechanisms that output information to an operator or user, such as a display 740, etc. Communication interface 712 may include any transceiver-like mechanism, such as one or more Ethernet interfaces that enable computing system 700 to communicate with other devices and / or systems, such as communicating with other computing devices 750, 760, 770. The communication interface 712 of computing system 700 may be connected to another computing system via a local area network (LAN) or a wide area network (WAN), such as the Internet. Storage element interface 706 may include a storage interface, such as a Serial Advanced Technology Attachment (SATA) interface or a Small Computer System Interface (SCSI), for connecting bus 710 to one or more storage elements 708, such as one or more local disks, such as SATA disk drives, and controlling the reading of data from and / or the writing of data to these storage elements 708. Although one or more of the aforementioned storage elements 708 are described as local disks, in general, any other suitable computer-readable medium may be used, such as removable disks, optical storage media such as CDs or DVDs, ROM disks, solid-state drives, flash memory cards, etc. The computing system 700 may be implemented as or may include application-specific integrated circuits (ASICs), application-specific instruction set processors (ASIPs), field-programmable gate arrays (FPGAs), digital signal processor-based systems (DSPs), or combinations thereof.

[0117] According to various embodiments of this disclosure, such a computing system 700 is suitable for performing various steps performed by an OLT in an optical network. According to this disclosure, a communication interface 712 allows the OLT, according to various embodiments of this disclosure, to exchange control information and data with ONUs in a PON. According to an example embodiment, the processor can run computer program code that allows the construction of OLT control frames. More specifically, the program code performs the following steps: grouping data units of an optical network unit into groups of one or more Encapsulation Method (EM) frames, wherein a corresponding group of one or more EM frames includes data units addressed to a corresponding subset of ONUs; generating a framing sublayer payload including at least one specific frame based on the group of one or more EM frames, wherein the specific frame includes a length indicator that is determined relative to the length of one or more groups of one or more EM frames that directly follow the specific frame and are addressed to at least one subset of ONUs; instructing ONUs in at least one subset of the at least one subset to process EM frames that directly follow the specific frame, and instructing ONUs not assigned to at least one subset to process EM frames indicated by the length indicator of the specific frame; and sending the framing sublayer payload to the ONUs.

[0118] Furthermore, according to various embodiments of the present invention, the computing system 700 is also adapted to perform various steps performed by an ONU in an optical network. According to this disclosure, the communication interface 712 allows an ONU according to various embodiments of the present invention to receive control information and exchange data with an OLT in a PON. According to an example embodiment, the processor can run computer program code that allows the ONU to control the decoding of received frames. More specifically, the program code performs the following steps: receiving a framing sublayer payload from the OLT; obtaining a specific frame included in the framing sublayer payload, wherein the specific frame includes a length indicator relating to the length of one or more groups of EM frames that directly follow a specific frame addressed to at least one subset of the ONU; if the ONU is assigned to the at least one subset, then, as instructed by the OLT, the next EM frame to be processed is determined to be the EM frame directly following the specific frame, or if the ONU is not assigned to the at least one subset, then the next EM frame to be processed is the EM frame indicated by the length indicator of the specific frame.

[0119] Figure 8 An example method 800 combining aspects of an example embodiment is shown.

[0120] In step S810, the OLT implementing various aspects of the example embodiment groups data units for ONUs into groups of one or more EM frames, wherein the corresponding group of one or more EM frames includes data units addressed to a corresponding subset of ONUs.

[0121] In step S820, the OLT generates an FS payload comprising at least one specific frame based on a group of one or more EM frames, wherein the specific frame includes a length indicator that is determined relative to the length of one or more groups of one or more EM frames that directly follow the specific frame and address to at least a subset of the ONU.

[0122] In step S830, the OLT instruction assigns the processing of the EM frame that directly follows the specific frame to the ONU processing of at least one subset of the at least one subset, and instructs the processing of the EM frame that is not assigned to the ONU processing of at least one subset to be indicated by the length of the specific frame.

[0123] In step S840, the OLT sends the FS payload to the ONU.

[0124] Figure 9 Another example method 900 combining aspects of the example embodiment is shown.

[0125] In step S910, the ONU of the example embodiment receives the FS payload from the OLT.

[0126] In step S920, the ONU obtains a specific frame contained in the FS payload, wherein the specific frame includes a length indicator that is related to the length of one or more groups of one or more EM frames that follow at least one subset of the specific frames addressed to the ONU.

[0127] In step S930, if the ONU is assigned to the at least one subset, the next EM frame to be processed by the ONU is determined as the EM frame that directly follows the specific frame, as indicated by the OLT; or if the ONU is not assigned to the at least one subset, the next EM frame to be processed is determined as the EM frame indicated by the length indicator of the specific frame.

[0128] While the invention has been described with reference to specific embodiments, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the invention can be implemented with various changes and modifications without departing from its scope. Therefore, these embodiments are to be considered illustrative in all respects and not restrictive, and the scope of the invention is indicated by the appended claims rather than by the foregoing description, and all changes falling within the scope of the claims are therefore intended to be included therein.

[0129] Furthermore, the reader of this patent application will understand that the words “comprising” or “including” do not exclude other elements or steps, the words “a” or “an” do not exclude multiple, and a single element such as a computer system, processor, or another integrated unit can perform the functions of several components recited in the claims. No reference numerals in the claims should be construed as limiting the corresponding claim. When used in the specification or claims, the terms “first,” “second,” “third,” etc., are introduced to distinguish similar elements or steps and do not necessarily describe a sequence or chronological order. Similarly, the terms “top,” “bottom,” “above,” “below,” etc., are introduced for descriptive purposes and not necessarily to indicate relative positions. It should be understood that the terms used are interchangeable where appropriate, and embodiments of the invention can be operated in other orders or in one or more directions different from those described or illustrated.

Claims

1. A communication apparatus used by an optical line terminal (OLT) (110) communicatively connected to an optical network unit (ONU) (131, 132, 133), comprising components for performing the following operations: - Grouping data units for the optical network unit into one or more groups of encapsulation method EM frames, wherein the corresponding group of one or more EM frames includes data units addressed to a corresponding subset of the ONU. - Generate a framed sublayer payload based on the group of the one or more EM frames, including at least one specific frame, wherein the specific frame includes a length indicator that is determined relative to the length of the group of one or more EM frames that directly follow the specific frame and address to at least a subset of the ONU; - The instruction assigned to the ONU processing of at least one subset of the at least one subset directly follows the EM frame after the specific frame, and the instruction not assigned to the ONU processing of the at least one subset is the EM frame indicated by the length indicator of the specific frame; - Send the framed sublayer payload to the ONU (131, 132, 133).

2. The apparatus of claim 1, wherein the specific frame is a special EM frame including an EM header and zero payload.

3. The apparatus of claim 2, wherein the length indicator is included in the payload length indicator field of the EM header of the special EM frame.

4. The apparatus of claim 2, wherein the specific frame further comprises response information for instructing the ONU processing assigned to at least one subset of the at least one subset to directly follow the EM frame after the specific frame, and / or instructing the ONU processing not assigned to the at least one subset to the EM frame indicated by the length indicator of the specific frame.

5. The apparatus of claim 4, wherein the response information is included in the port-ID field or option field of the EM header of the special EM frame.

6. The apparatus of claim 1, wherein the specific frame includes a subset indicator indicating a subset, and the length indicator is determined relative to the length of a group of one or more EM frames of the subset that directly follows the specific frame and is addressed to the ONU indicated in the subset indicator, or relative to the length of one or more groups of one or more EM frames of the subset that directly follows the specific frame and is not addressed to the ONU indicated in the subset indicator.

7. The apparatus of claim 1, wherein the specific frame includes at least one of the following: an ONU indicator with an invalid value, an unassigned ONU indicator, or an ONU indicator indicating an ONU different from that assigned to a subset of ONUs addressed by a group of one or more EM frames preceding the specific frame, and wherein the length indicator is determined relative to the length of one or more groups of one or more EM frames that directly follow the specific frame and do not address to a subset of ONUs addressed by a group of one or more EM frames preceding the specific frame.

8. The apparatus of claim 1, wherein the component is further configured to: - Transmit to the corresponding ONU (131, 132, 133) an indication of the start position of the group of one or more EM frames corresponding to the subset to which it is assigned.

9. The apparatus according to claim 1, wherein, At least one group of one or more EM frames is transmitted using a predetermined modulation format and / or encoded using a predetermined FEC code, and at least another group of one or more EM frames is transmitted using a different modulation format and / or encoded using a different FEC code.

10. The apparatus according to any one of the preceding claims, wherein the component is further configured to: - Transmit the subset identifier of the subset to which it is assigned to the corresponding ONU (131, 132, 133).

11. An apparatus for communication, used by an optical network unit (ONU) (131, 132, 133) communicatively connected to an optical line terminal (OLT) (110), comprising components for performing the following operations: - Receive the framed sublayer payload from the OLT (110); - Obtain a specific frame included in the framing sublayer payload, wherein the specific frame includes a length indicator that is related to the length of one or more groups of one or more EM frames that directly follow the specific frame addressed to at least a subset of the ONU; - If the ONU is assigned to the at least one subset, the next EM frame to be processed is determined as the EM frame that directly follows the specific frame, as instructed by the OLT (110), or if the ONU is not assigned to the at least one subset, the next EM frame to be processed is the EM frame indicated by the length indicator of the specific frame.

12. The apparatus of claim 11, wherein the component is further configured to: - The next EM frame to be processed is determined based on a special configuration of the ONU group, wherein the special configuration of the ONU group includes at least one of the following: a subset identifier of the subset to which the corresponding ONU is assigned or an indication of the start position of the group of one or more EM frames corresponding to the subset to which it is assigned.

13. The apparatus according to claim 12, wherein, The component is also configured to: - Receive the special configuration regarding ONU packets from the OLT (110).

14. A method of communication, used by an optical line terminal (OLT) (110) communicatively connected to an optical network unit (ONU) (131, 132, 133), comprising: - Grouping data units for the optical network unit into one or more groups of encapsulation method EM frames, wherein the corresponding group of one or more EM frames includes data units addressed to a corresponding subset of the ONU. - Generate a framed sublayer payload based on the group of the one or more EM frames, including at least one specific frame, wherein the specific frame includes a length indicator, the length indicator being determined relative to the length of the group of one or more EM frames that directly follow the specific frame and address to at least a subset of the ONU; - The instruction assigned to the ONU processing of at least one subset of the at least one subset directly follows the EM frame after the specific frame, and the instruction not assigned to the ONU processing of the at least one subset is the EM frame indicated by the length indicator of the specific frame; - Send the framed sublayer payload to the ONU (131, 132, 133).

15. A method of communication, used by an optical network unit (ONU) (131, 132, 133) communicatively connected to an optical line terminal (OLT) (110), comprising: - Receive the framed sublayer payload from the OLT (110); - Obtain a specific frame included in the framing sublayer payload, wherein the specific frame includes a length indicator that is related to the length of one or more groups of one or more EM frames that directly follow the specific frame addressed to at least a subset of the ONU; - If the ONU is assigned to the at least one subset, the next EM frame to be processed is determined as the EM frame that directly follows the specific frame, as instructed by the OLT (110), or if the ONU is not assigned to the at least one subset, the next EM frame to be processed is the EM frame indicated by the length indicator of the specific frame.

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