Direct communication device of optical network unit

Abstract

The utility model provides a direct communication device of an optical network unit. The device comprises an optical line terminal, an optical distribution network, an optical cross connector and an optical network unit group, the optical distribution network comprises a single-mode optical fiber, a reflection unit and a star coupler which are connected in sequence, and the single-mode optical fiber is also connected with the optical line terminal; the optical network unit group comprises a first optical network unit group and a second optical network unit group, the first optical network unit group is connected with the star coupler through the optical cross connector, and the second optical network unit group is directly connected with the star coupler.

Description

Technical Field

[0001] The utility model relates to the technical field of communication, and in particular to an optical network unit direct communication device. Background Art

[0002] PON (Passive Optical Network) is the mainstream fiber-optic access technology in the communications industry. With its advantages such as minimalist architecture and flexible deployment, it has been widely used in operator networks, mainly serving two scenarios: home broadband and enterprise dedicated lines. At the same time, it is expanding into the industrial field to help the digital transformation of industrial manufacturing.

[0003] PON adopts the P2MP (Point to Multipoint) topology, which mainly includes OLT (Optical Line Terminal) at the central office, ONU (Optical Network Unit) at the user side, and ODN (Optical Distribution Network) in the middle. OLT and ONU are optoelectronic integrated devices, and ODN is an optical transmission channel composed of passive devices such as SMF (Single Mode Fiber) and SC (Star Coupler). OLT uses the network side interface to connect to the upper-end device, perform traffic scheduling, buffer control and other functions, and maintain and monitor ONU through ODN. ONU is an access network terminal used to provide user-side interface and is centrally controlled by OLT. By using different carrier wavelengths, the upstream and downstream signals between OLT and ONU are independently transmitted in a single optical fiber. The point-to-multipoint transmission principle of PON is divided into the downstream transmission principle and the upstream transmission principle. The downstream direction adopts the broadcast method. The optical signal sent by the OLT is divided into multiple parts by the ODN. Each part carries exactly the same data, and then each ONU extracts its own part. The upstream direction adopts the TDMA (Time Division Multiple Access) method. The OLT allocates different time windows to each ONU. The ONU only sends optical signals within its own time window, which are then aggregated into an information flow by the ODN and received and processed by the OLT.

[0004] Driven by international standardization organizations such as FSAN (Full Service Access Networks), ITU-T (International Telecommunication Union-Telecommunications Standardization Sector), and IEEE (Institute of Electrical and Electronics Engineers), PON technology has undergone many evolutions and has now achieved large-scale commercial use of 10GPON, which can provide users with symmetrical 10Gbps upstream and downstream rates. According to different technical standards, 10G PON is divided into two major camps: 10G EPON and XG(S)-PON. The splitting ratio and transmission distance in the PON technical specifications are directly related to the attenuation loss of the optical transmission channel. Limited by the sensitivity of the optical receiver, the PON system cannot take into account both the splitting ratio and the long transmission distance. However, a compromise design can be made in the application scenario based on the specific needs of the number of users and coverage: at a splitting ratio of 1:128, the transmission distance of 10G EPON is 30km, and the transmission distance of XG(S)-PON can reach 40km; if the transmission distance is 20km, 10G EPON can support up to 1:256 splitting, and XG(S)-PON can support up to 1:512 splitting.

[0005] In the traditional PON system, ONUs lack the ability to communicate directly, and all data exchanges must be relayed through the OLT located at the central office. The main process includes the following: data is first transmitted from the initiating ONU to the OLT; after the OLT receives the data, it performs necessary processing, such as routing decisions; the data is transmitted downstream by the OLT to the target ONU. The whole process leads to the following problems: the data is processed by the OLT and the time for the two transmissions will generate additional delays. Utility Model Content

[0006] The utility model aims to solve one of the technical problems in the related art at least to a certain extent.

[0007] Therefore, the first object of the present invention is to provide an optical network unit direct communication device to solve the delay problem caused by the data exchange between ONUs having to be relayed through the OLT located at the central office.

[0008] To achieve the above-mentioned purpose, the first aspect of the utility model proposes an optical network unit direct communication device, including an optical line terminal, an optical distribution network, an optical cross-connector and an optical network unit group; the optical distribution network includes a single-mode optical fiber, a reflection unit and a star coupler connected in sequence, and the single-mode optical fiber is also connected to the optical line terminal; the optical network unit group includes a first optical network unit group and a second optical network unit group, the first optical network unit group is connected to the star coupler via the optical cross-connector, and the second optical network unit group is directly connected to the star coupler.

[0009] In the optical network unit direct communication device provided in the first aspect of the utility model, the reflection unit adopts a fiber Bragg grating.

[0010] In the optical network unit direct communication device provided in the first aspect of the utility model, the reflection unit includes a WDM multiplexer and a demultiplexer, and an optical fiber end face reflector.

[0011] In the optical network unit direct communication device provided in the first aspect of the utility model, the optical cross-connector includes a plurality of groups of connection units, and each group of connection units includes a star coupler and a filter module.

[0012] In the optical network unit direct communication device provided in the first aspect of the utility model, the filter module includes a plurality of comb filters connected in series, and the star couplers of each group of connection units are connected to the comb filters in other groups of connection units.

[0013] In the optical network unit direct communication device provided in the first aspect of the utility model, the initiating optical network unit in the first optical network unit group includes a merging module, which uses wavelength division multiplexing to merge the ONU direct communication wavelength group and the uplink transmission wavelength before uplink transmission.

[0014] In the optical network unit direct communication device provided in the first aspect of the utility model, each optical network unit of the optical network unit group adopts TDMA mode to perform uplink transmission in different time windows.

[0015] In the optical network unit direct communication device provided in the first aspect of the utility model, the optical network unit group divides several broadcast domains belonging to the optical network unit direct communication through VLAN.

[0016] In the optical network unit direct communication device provided in the first aspect of the utility model, each optical network unit of the optical network unit group adopts a dual-optical port ONU.

[0017] The optical network unit direct communication device provided by the utility model comprises an optical line terminal, an optical distribution network, an optical cross connector and an optical network unit group; the optical distribution network comprises a single-mode optical fiber, a reflection unit and a star coupler connected in sequence, and the single-mode optical fiber is also connected to the optical line terminal; the optical network unit group comprises a first optical network unit group and a second optical network unit group, the first optical network unit group is connected to the star coupler via an optical cross connector, and the second optical network unit group is directly connected to the star coupler. In this case, through the optical cross connector and the reflection unit set in the optical distribution network, some wavelengths in the ONU direct communication wavelength group generated by the initiating optical network unit of the first optical network unit group can be sent to the corresponding ONU without passing through the OLT at the local end, thereby realizing data exchange between ONUs without passing through the OLT at the local end, shortening the time of data exchange between ONUs, and solving the delay problem caused by the data exchange between ONUs having to be relayed through the OLT at the local end.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description and in part will become apparent from the following description or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0020] Figure 1 The transmission principle diagram of the existing passive optical network provided by the utility model;

[0021] Figure 2 A schematic diagram of the division of the virtual local area network provided by the utility model;

[0022] Figure 3 A block diagram of an optical network unit direct communication device provided by an embodiment of the utility model;

[0023] Figure 4 A connection diagram of an optical distribution network provided by an embodiment of the utility model;

[0024] Figure 5 A connection diagram of a reflection unit provided in an embodiment of the utility model;

[0025] Figure 6 A schematic diagram of virtual local area network division for direct communication of optical network units provided in an embodiment of the utility model;

[0026] Figure 7 An architecture diagram of an optical network unit direct communication device provided by an embodiment of the utility model;

[0027] Figure 8 A schematic diagram of the structure of an optical cross-connector provided in an embodiment of the utility model;

[0028] Fig. 9 for Figure 8 Transmission diagram of the optical cross-connector in different point-to-point direct communications. DETAILED DESCRIPTION

[0029] Here, exemplary embodiments will be described in detail, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the embodiments of the utility model. Instead, they are only examples of devices and methods consistent with some aspects of the embodiments of the utility model as detailed in the attached claims.

[0030] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0031] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. It should also be understood that the term "and / or" used in the present utility model refers to and includes any or all possible combinations of one or more associated listed items.

[0032] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0033] PON (Passive Optical Network) is the mainstream fiber access technology in the communications industry. The existing PON adopts a P2MP (Point to Multipoint) topology, which mainly includes OLT (Optical Line Terminal) at the central office, ONU (Optical Network Unit) at the user side, and ODN (Optical Distribution Network) in the middle. Among them, OLT and ONU are optoelectronic integrated devices, and ODN is an optical transmission channel composed of SMF (Single Mode Fiber) and SC (Star Coupler).

[0034] Figure 1 The transmission principle diagram of the existing passive optical network provided by the present invention is shown in FIG. Figure 1 As shown in the figure, the downstream direction adopts the broadcast mode, and the optical signal sent by the OLT is divided into multiple parts (for example, 3 parts) by the ODN, each of which carries exactly the same data (for example, carrying optical signal 1, optical signal 2, and optical signal 3), and then each ONU extracts its own part; the upstream direction adopts the TDMA (Time Division Multiple Access) mode, and the OLT allocates different time windows to each ONU (such as Figure 1 The red, green and blue colors represent different time windows). ONU only sends optical signals within its own time window, which are then aggregated into an information flow by ODN and then received and processed by OLT. OLT uses the network side interface to connect to the upper-end device, perform traffic scheduling, buffer control and other functions, and maintain and monitor ONU through ODN. ONU is an access network terminal that provides a user-side interface and is centrally controlled by OLT. The splitting ratio of 1:N means that 1 path of light is evenly divided into N paths. The maximum distance between ODN and ONU is the transmission distance. Both the splitting ratio and the transmission distance are directly related to the attenuation loss of the optical transmission channel. Limited by the sensitivity of the optical receiver, the PON system cannot take into account both the splitting ratio and the large transmission distance, but it can be designed as a compromise in the application scenario according to the specific needs of the number of users and coverage.

[0035] PON uses VLAN (Virtual Local Area Network) division to achieve logical isolation between different services such as voice, data, and video. Specifically, each VLAN is a broadcast domain, and users in the same VLAN can communicate directly, which is called Layer 2 communication; different VLANs are isolated from each other, and users cannot directly visit each other, and need to communicate with each other through routers, switches, and other devices with Layer 3 routing functions. Figure 2 This is a schematic diagram of the division of the virtual local area network provided by the utility model. Figure 2 As shown in the figure, CVLAN is the user side VLAN, SVLAN is the service side VLAN, and the two are converted to each other through OLT. 100, 200 and 300 are subnet VLAN numbers of different broadcast domains, which can achieve logical isolation between different services.

[0036] Considering the lack of direct communication between ONUs in traditional PON, all data exchanges must be relayed through the OLT located at the central office, which mainly includes the following steps: the initiating optical network unit (i.e., initiating ONU) is under the control of the OLT, and the data is first transmitted from the initiating ONU to the OLT; after receiving the data, the OLT performs necessary processing, such as routing decisions; the data is transmitted downstream by the OLT to the target optical network unit (i.e., target ONU). The whole process leads to the following problems: the data processing time at the OLT and the two transmission times will generate additional delays; due to the additional processing and transmission process, the energy consumption of the system will also increase accordingly; the OLT, as the central node, carries all upstream and downstream traffic, which may become a bottleneck and affect the efficiency of bandwidth utilization.

[0037] Based on this, the utility model proposes an optical network unit direct communication device to solve the delay problem caused by the data exchange between ONUs having to be relayed through the OLT located at the local end.

[0038] In this embodiment, Figure 3 The block diagram of an optical network unit direct communication device provided by an embodiment of the utility model. The optical network unit direct communication device in the utility model can be referred to as a communication device for short.

[0039] like Figure 3 As shown, the optical network unit direct communication device includes an optical line terminal OLT, an optical distribution network ODN, an optical cross connector OXC and an optical network unit group, and the optical network unit group includes a first optical network unit group and a second optical network unit group. The first optical network unit group is connected to the optical distribution network ODN via the optical cross connector OXC, and the second optical network unit group is directly connected to the optical distribution network ODN.

[0040] In this embodiment, the optical line terminal is used to send an initiating communication instruction to the initiating optical network unit in the first optical network unit group based on the communication demand. Specifically, the optical line terminal determines the initiating optical network unit in the first optical network unit group based on the communication demand and generates the initiating communication instruction, and sends the initiating communication instruction to the initiating optical network unit via the optical distribution network ODN and the optical cross connector OXC.

[0041] In this embodiment, the optical distribution network ODN includes a single-mode optical fiber SMF, a reflection unit and a star coupler SC connected in sequence, wherein the single-mode optical fiber is also connected to an optical line terminal; the first optical network unit group is connected to the star coupler via an optical cross-connector, and the second optical network unit group is directly connected to the star coupler.

[0042] In this embodiment, the optical distribution network ODN is used to reflect the first direct communication wavelength by using a reflection unit.

[0043] For example, the conventional uplink transmission wavelength and downlink transmission wavelength are denoted as λ UP and λ DOWN , the first direct communication wavelength used for ONU direct communication is denoted as λ DIRECT , taking 10G PON system as an example: UP =1270nm,λ DOWN =1577nm,λ DIRECT With λ UP , DOWN There is a certain wavelength interval between them, the optional λ DIRECT =1535nm, so that when the first direct communication wavelength is combined with the uplink transmission wavelength or the downlink transmission wavelength for uplink or downlink transmission by wavelength division multiplexing, the ONU direct communication and the conventional uplink and downlink transmission can be independent of each other. In addition, when the combined data after the first direct communication wavelength is combined with the uplink transmission wavelength is transmitted to the optical distribution network ODN, the reflection unit reflects the first direct communication wavelength λ in the combined data. DIRECT , through the uplink transmission wavelength λ in the combined data UP .

[0044] In some embodiments, the reflection unit may be a fiber Bragg grating (FBG). Figure 4 This is a schematic diagram of the connection of the optical distribution network provided by the embodiment of the utility model. Figure 4 As shown in Figure 1, an FBG is deployed between the SMF and SC in the ODN. The wavelength selectability of FBG is used to achieve DIRECT The reflection of UP and λ DOWNThe splitting ratio of 1:N means that one light path is equally divided into N paths. N is equal to the number of all optical network units (ONUs) in the optical network unit group.

[0045] In some embodiments, the reflection unit may include a WDM multiplexer and demultiplexer, and a fiber end face reflector, which have the same functions as the FBG. Figure 5 A connection diagram of the reflection unit provided in the embodiment of the utility model. Figure 5 As shown, a set of WDM multiplexers / demultiplexers are used to connect the channels. DIRECT Connecting the optical fiber end face reflector to the corresponding channel can also realize the same function as FBG in the system.

[0046] In this embodiment, the Figure 4 In the PON system of the optical distribution network ODN shown, the OLT performs functions such as traffic scheduling and buffer control, and maintains and monitors each ONU of the optical network unit group through the ODN, and the ONU is centrally controlled by the OLT. The PON system of this embodiment performs uplink and downlink transmission in the same manner as the conventional PON system, that is, the downlink direction adopts the broadcast mode, and the optical signal sent by the OLT is divided into multiple parts (for example, N parts) by the ODN, each of which carries exactly the same data, and then each ONU extracts its own part; the uplink direction adopts the TDMA mode, and the OLT allocates different time windows to each ONU. The ONU only sends optical signals within its own time window, and then converges into an information flow through the ODN, and then is received and processed by the OLT.

[0047] Considering that the PON system of this embodiment realizes direct communication in both "point-to-point" and "point-to-multipoint" situations, the PON system of this embodiment performs "point-to-multipoint" ONU direct communication in the following manner: the OLT allocates an exclusive time window (i.e., a preset time window) for direct communication to the initiating ONU of the first optical network unit group according to the demand for ONU direct communication, and adopts TDMA and wavelength division multiplexing to avoid conflicts with conventional uplink transmission; the direct communication optical signal (i.e., the first direct communication wavelength) passes through the SC, is converged by the SC, reflected by the FBG, and passes through the SC again to be sent to all ONUs of the optical network unit group; since all ONUs can receive the direct communication optical signal, several broadcast domains belonging to the ONU direct communication are divided by VLAN to realize logical isolation between different services and ensure data security.

[0048] In this embodiment, the optical network unit group divides several broadcast domains belonging to the optical network unit direct communication through VLAN. Taking three broadcast domains as an example, Figure 6A schematic diagram of virtual local area network division for direct communication of optical network units provided in an embodiment of the utility model. Figure 6 As shown in the figure, the CVLAN (i.e., user-side VLAN) of each ONU divides three services (i.e., three broadcast domains) by subnet VLAN numbers of different broadcast domains (e.g., 100, 200, and 300), thus achieving logical isolation between different services and ensuring data security.

[0049] In this embodiment, the above-mentioned "point-to-multipoint" direct communication is characterized in that: all ONUs share a first direct communication wavelength λ DIRECT , through TDMA and wavelength division multiplexing to avoid conflicts with conventional uplink transmission; all ONUs in the optical network unit group can receive the first direct communication wavelength λ from the initiating ONU DIRECT , through VLAN division, the ONU with the same subnet VLAN number as the initiating ONU obtains the first direct communication wavelength λ DIRECT ; The network has low cost and high flexibility.

[0050] The PON system of this embodiment also implements “point-to-point” direct communication with the help of OXC (Optical Cross-Connect).

[0051] Specifically, the first optical network unit group in the optical network unit group is connected to the optical distribution network ODN via the optical cross connector OXC, and the initiating optical network unit of the first optical network unit group generates an ONU direct communication wavelength group based on the initiating communication instruction and then performs uplink transmission, and the ONU direct communication wavelength group includes a first direct communication wavelength and / or at least one second direct communication wavelength. The first optical network unit group and the second optical network unit group receive the first direct communication wavelength reflected from the optical distribution network, and the target optical network unit in the first optical network unit group also receives the second direct communication wavelength from the optical cross connector.

[0052] For example, the ONUs participating in the "point-to-point" direct communication form the first optical network unit group. The conventional uplink and downlink transmission wavelengths are still recorded as λ UP and λ DOWN , the wavelength group for ONU direct communication is recorded as λ DIRECT_0 , DIRECT_1 , ..., λ DIRECT_n-1 , where λ DIRECT_0 The first direct communication wavelength can be compared to the above λ DIRECT The relevant description of is used for "point-to-multipoint" communication; and λ DIRECT_1 , ..., λ DIRECT_n-1 Used for "point-to-point" direct communication between specific ONUs in the first optical network unit group, where n is the number of ONUs participating in the "point-to-point" direct communication.

[0053] In this embodiment, the optical cross connector is used to send the second direct communication wavelength from the initiating optical network unit to the corresponding target optical network unit. The optical cross connector includes a plurality of star couplers and a plurality of comb filters. Specifically, the optical cross connector includes a plurality of groups of connection units, each group of connection units includes a star coupler and a filter module. The filter module includes a plurality of comb filters connected in series, and the star couplers of each group of connection units are connected to the comb filters in other groups of connection units. The number of groups of connection units is consistent with the number of optical network units included in the first optical network unit group.

[0054] Figure 7 This is a diagram of the architecture of an optical network unit direct communication device provided by an embodiment of the utility model. Figure 7 As shown in the figure, an FBG is deployed between the SMF and SC in the ODN, and its wavelength selectability is used to achieve λ DIRECT_0 The reflection of UP and λ DOWN An OXC device is deployed between the SC and the ONUs participating in the "point-to-point" direct communication (ie, each ONU of the first optical network unit group).

[0055] In this embodiment, each direct communication wavelength of the ONU direct communication wavelength group is located between the uplink transmission wavelength and the downlink transmission wavelength. Taking n=3 as an example, the ONU direct communication wavelength group is, for example, DIRECT_0 =1535nm,λ DIRECT_1 =1535.25nm,λ DIRECT_2 =1535.5nm.

[0056] Taking n=3 (i.e., the first optical network unit group includes 3 optical network units) as an example, Figure 8 The schematic diagram of the structure of the optical cross connector provided by the embodiment of the utility model is shown in FIG. Figure 8 In the structure shown in the figure, the three optical network units of the first optical network unit group are subunit ONU1, subunit ONU2 and subunit ONU3. Figure 8 The OXC shown in the figure includes three groups of connected units, each group of connected units includes two comb filters connected in series and an SC. Figure 8 For example, IL 11, IL 21, and IL 31 are all comb filters with a spacing of 0.25 nm. Figure 8 IL 12, IL 22, and IL 32 are all comb filters with a spacing of 0.5 nm.

[0057] like Figure 8As shown, the comb filters IL12 and IL11 of the first group of connection units are connected in series with the SC of the first group of connection units, the SC of the first group of connection units is connected to the subunit ONU1, and the SC of the first group of connection units is also connected to the comb filters IL22 and IL31 of the second group of connection units through corresponding ports P21 and P31; the comb filters IL22 and IL21 of the second group of connection units are connected in series with the SC of the second group of connection units, the SC of the second group of connection units is connected to the subunit ONU2, and the SC of the second group of connection units is also connected to the comb filters IL11 and IL32 of the first group of connection units through corresponding ports P12 and P32; the comb filters IL32 and IL31 of the third group of connection units are connected in series with the SC of the third group of connection units, the SC of the third group of connection units is connected to the subunit ONU3, and the SC of the third group of connection units is also connected to the comb filters IL11 and IL32 of the first group of connection units. 12. The comb filters IL21 of the second group of connection units are connected via corresponding ports P13 and P23. It should be noted that, considering that there are many connection lines, the connection lines between the same ports are not shown in the figure to ensure the clarity of the drawings.

[0058] The following takes n=3 as an example, and specifically describes the "point-to-point" direct communication of the three optical network units (ONU1, ONU2 and ONU3) in the first optical network unit group in conjunction with the accompanying drawings. The ONUs participating in the "point-to-point" direct communication can achieve the tuning of the transmission wavelength, so that Figure 8 Take the topology in as an example, Fig. 9 for Figure 8 Transmission diagram of the optical cross-connector in different point-to-point direct communications.

[0059] 1) When ONU1 and ONU2 are communicating directly, when ONU1 sends a signal to ONU2, ONU1 is the initiating ONU and ONU2 is the target ONU. The second direct communication wavelength in the ONU direct communication wavelength group generated by ONU1 includes the transmission wavelength λ DIRECT_1 =1535.25nm, which is an odd multiple of 0.25nm. The comb filter IL 11 is bypassed, and the transmission path is as follows Fig. 9 As shown in (a), the emission wavelength λ DIRECT_1 =1535.25nm is sent from ONU1 to ONU2 via the SC of the first group of connection units, the comb filter IL 11 of the first group of connection units, and the SC of the second group of connection units;

[0060] 2) When ONU1 and ONU3 are communicating directly, when ONU1 sends a signal to ONU3, ONU1 is the initiating ONU and ONU3 is the target ONU. The second direct communication wavelength in the ONU direct communication wavelength group generated by ONU1 includes the transmission wavelength λ DIRECT_2 =1535.5nm, which is an even multiple of 0.25nm, then the comb filter IL 11 is passed directly, and it is an odd multiple of 0.5nm, then the comb filter IL 12 is bypassed. The transmission path is as follows Fig. 9 As shown in (b), the emission wavelength λ DIRECT_2 =1535.5nm is sent from ONU1 to ONU3 via the SC of the first group of connection units, the comb filter IL11 of the first group of connection units, the comb filter IL12 of the first group of connection units, and the SC of the third group of connection units;

[0061] 3) When ONU2 and ONU1 communicate directly, when ONU2 sends a signal to ONU1, ONU2 is the initiating ONU, ONU1 is the target ONU, and the second direct communication wavelength in the ONU direct communication wavelength group generated by ONU2 includes the transmission wavelength λ DIRECT_2 =1535.5nm, which is an even multiple of 0.25nm, then the comb filter IL 21 is passed directly, and it is an odd multiple of 0.5nm, then the comb filter IL 22 is bypassed. The transmission path is as follows Fig. 9 As shown in (c), the emission wavelength λ DIRECT_2 =1535.5nm is sent from ONU2 to ONU1 via the SC of the second group of connection units, the comb filter IL21 of the second group of connection units, the comb filter IL22 of the second group of connection units, and the SC of the first group of connection units;

[0062] 4) When ONU2 and ONU3 communicate directly, when ONU2 sends a signal to ONU3, ONU2 is the initiating ONU and ONU3 is the target ONU. The second direct communication wavelength in the ONU direct communication wavelength group generated by ONU2 includes the transmission wavelength λ DIRECT_1 =1535.25nm, which is an odd multiple of 0.25nm. The comb filter IL 21 is bypassed, and the transmission path is as follows Fig. 9 As shown in (d), the emission wavelength λ DIRECT_1 =1535.25nm is sent from ONU2 to ONU3 via the SC of the second group of connection units, the comb filter IL 21 of the second group of connection units, and the SC of the third group of connection units;

[0063] 5) When ONU3 and ONU1 communicate directly, when ONU3 sends a signal to ONU1, ONU3 is the initiating ONU and ONU1 is the target ONU. The second direct communication wavelength in the ONU direct communication wavelength group generated by ONU3 includes the transmission wavelength λ DIRECT_1 =1535.25nm, which is an odd multiple of 0.25nm. The comb filter IL 31 is bypassed, and the transmission path is as follows Fig. 9 As shown in (e), the emission wavelength λ DIRECT_1 =1535.25nm is sent from ONU3 to ONU1 via the SC of the third connection unit, the comb filter IL 31 of the third connection unit, and the SC of the first connection unit;

[0064] 6) When ONU3 and ONU2 communicate directly, when ONU3 sends a signal to ONU2, ONU3 is the initiating ONU and ONU2 is the target ONU. The second direct communication wavelength in the ONU direct communication wavelength group generated by ONU3 includes the transmission wavelength λ DIRECT_2 =1535.5nm, which is an even multiple of 0.25nm, then the comb filter IL 31 is passed directly, and it is an odd multiple of 0.5nm, then the comb filter IL 32 is bypassed. The transmission path is as follows Fig. 9 As shown in (f), the emission wavelength λ DIRECT_2 =1535.5nm is sent from ONU3 to ONU2 via the SC of the third group of connection units, the comb filter IL31 of the third group of connection units, the comb filter IL32 of the third group of connection units, and the SC of the second group of connection units.

[0065] Fig. 9 The "point-to-point" direct communication wavelength examples shown satisfy Table 1.

[0066] Table 1 “Point-to-point” direct communication wavelength table

[0067] Initiator: ONU1 Initiator: ONU2 Initiator: ONU3 Receive: ONU1 <![CDATA[λ DIRECT_2 ]]> <![CDATA[λ DIRECT_1 ]]> Receive: ONU2 <![CDATA[λ DIRECT_1 ]]> <![CDATA[λ DIRECT_2 ]]> Receive: ONU3 <![CDATA[λ DIRECT_2 ]]> <![CDATA[λ DIRECT_1 ]]>

[0068] In this embodiment, Fig. 9 In addition to "point-to-point" direct communication, it also supports "point-to-multipoint" ONU communication. The transmission wavelength of the initiating ONU is: DIRECT_0 =1535nm, which is an even multiple of 0.25nm and an even multiple of 0.5nm, and all comb filters can pass through.

[0069] In this embodiment, the initiating optical network unit in the first optical network unit group includes a merging module, which uses wavelength division multiplexing to merge the ONU direct communication wavelength group and the uplink transmission wavelength before performing uplink transmission.

[0070] In this embodiment, the optical network unit direct communication device uses TDMA to allocate a preset time window to the ONU direct communication wavelength group initiating the optical network unit.

[0071] In this embodiment, each optical network unit of the optical network unit group performs uplink transmission in different time windows using TDMA.

[0072] In this embodiment, since there is an obvious wavelength difference between ONU direct communication and conventional uplink communication, the ONU needs to have dual-wavelength transmission capability, that is, each optical network unit of the optical network unit group adopts a dual-optical port ONU.

[0073] The serial numbers of the above-mentioned embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0074] The optical network unit direct communication device in the embodiment of the utility model includes an optical line terminal, an optical distribution network, an optical cross connector and an optical network unit group; the optical distribution network includes a single-mode optical fiber, a reflection unit and a star coupler connected in sequence, and the single-mode optical fiber is also connected to the optical line terminal; the optical network unit group includes a first optical network unit group and a second optical network unit group, the first optical network unit group is connected to the star coupler via an optical cross connector, and the second optical network unit group is directly connected to the star coupler. In this case, through the optical cross connector and the reflection unit set in the optical distribution network, some wavelengths in the ONU direct communication wavelength group generated by the initiating optical network unit of the first optical network unit group can be sent to the corresponding ONU without passing through the OLT at the local end, thereby realizing data exchange between ONUs without passing through the OLT at the local end, shortening the time of data exchange between ONUs, and solving the delay problem caused by the data exchange between ONUs having to be relayed through the OLT at the local end.

[0075] In the direct communication device of the embodiment of the utility model, a wavelength (group) dedicated to ONU direct communication is planned, and wavelength division multiplexing is used to achieve the coexistence of ONU direct communication and conventional uplink and downlink transmission; passive devices such as optical reflectors and optical filters are deployed at specific locations of the ODN to build an optical fiber transmission path dedicated to ONU direct communication; VLAN is used to achieve service isolation between ONUs to avoid ONU direct communication, especially the security risks of point-to-multipoint direct communication between ONUs; in response to the concurrent requirements of ONU direct communication and conventional uplink and downlink transmission, dual-optical port ONUs or tunable ONUs and other devices are matched.

[0076] The invention has the following technical effects: 1) on the basis of the traditional PON system, a wavelength (group) dedicated to ONU direct communication is planned, and wavelength division multiplexing is used to realize the coexistence of ONU direct communication and conventional upstream and downstream transmission; 2) passive devices such as optical reflectors and optical filters are deployed at specific positions of ODN to build an optical fiber transmission path dedicated to ONU direct communication, so as to solve the problem of "lack of direct communication capability between ONUs, and all data exchange must be relayed through the OLT located at the central office"; 3) VLAN is used to realize service isolation between ONUs, avoid ONU direct communication, especially the security risk of point-to-multipoint direct communication between ONUs; 4) matching dual-optical port ONUs or tunable ONUs and other equipment to meet the concurrent requirements of ONU direct communication and conventional upstream and downstream transmission.

[0077] The accompanying drawings show schematic diagrams of structures according to the disclosed embodiments of the utility model. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0078] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in the utility model can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the utility model can be achieved, and the utility model is not limited here.

[0079] The above specific implementations do not constitute a limitation on the protection scope of the present utility model. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. An optical network unit direct communication device, characterized in that: It comprises an optical line terminal, an optical distribution network, an optical cross connector and an optical network unit group; the optical distribution network comprises a single-mode optical fiber, a reflection unit and a star coupler connected in sequence, and the single-mode optical fiber is also connected to the optical line terminal; the optical network unit group comprises a first optical network unit group and a second optical network unit group, the first optical network unit group is connected to the star coupler via the optical cross connector, and the second optical network unit group is directly connected to the star coupler.

2. The optical network unit direct communication device according to claim 1, characterized in that: The reflection unit adopts a fiber Bragg grating.

3. The optical network unit direct communication device according to claim 1, characterized in that: The reflection unit includes a WDM multiplexer and demultiplexer, and an optical fiber end face reflector.

4. The optical network unit direct communication device according to claim 1, characterized in that: The optical cross connector comprises a plurality of connection units, and each connection unit comprises a star coupler and a filter module.

5. The optical network unit direct communication device according to claim 4, characterized in that: The filter module comprises a plurality of comb filters connected in series, and the star couplers of each group of connection units are connected to the comb filters in other groups of connection units.

6. The optical network unit direct communication device according to claim 1, characterized in that: The initiating optical network unit in the first optical network unit group includes a merging module, which uses wavelength division multiplexing to merge the ONU direct communication wavelength group and the uplink transmission wavelength before uplink transmission.

7. The optical network unit direct communication device according to claim 1, characterized in that: Each optical network unit of the optical network unit group performs uplink transmission in different time windows using TDMA mode.

8. The optical network unit direct communication device according to claim 1, characterized in that: The optical network unit group divides several broadcast domains belonging to direct communication of the optical network units through VLAN.

9. The optical network unit direct communication device according to claim 1, characterized in that: Each optical network unit of the optical network unit group adopts a dual-optical port ONU.

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