GB2592532A - System for distributing power and communication signals in optical fibre access networks - Google Patents

Abstract

The present invention relates to a system for distributing power in optical fibre access networks using optical boxes (10), including an optical box bus containing at least one optical splitter box (10) connected in sequence and terminating in a terminal box (12). The at least one optical splitter box (10) receives a splitter cable (CD) formed by a single optical fibre, providing a given optical input power (A'), said optical splitter box (10) having an input splitter (DE) to effect the unbalanced splitting of the optical input power (A') received in the optical box (10) of the bus into two parts. A first part of the optical input power (A') is conveyed to an output splitter (DS). The output splitter (DS) splits the first part of the optical power into optical powers that are selectively transferred to respective user terminal optical cables (CT). A second part of the optical input power (A') is conveyed to a subsequent optical box (10, 12) of the bus over a continuation cable (CC) and so on until said last optical termination box (12) is reached, where the optical input power is fully available to the user terminal optical cables (CT).

Description

"COMMUNICATION SIGNAL AND POWER DISTRIBUTION SYSTEM IN FIBER OPTIC ACCESS NETWORKS"

FIELD OF INVENTION

[1] The present invention refers to a system for the distribution of communication and power signals in optical fiber access networks, using optical junction and / or termination boxes, generally hermetic and of the type that has a housing provided with an entrance opening, to receive an optical distribution or bypass cable, by connectorization or fusion, containing one or more optical fibers, and a plurality of output openings, usually provided in a cap, sealed or removable, and though the output openings it is provided, by connectorization or by fusion, the connection of a respective fiber split of the optical distribution cable or a respective separate optical fiber / derived from the latter, with a respective optical user terminal cable ("drop" cable), projecting of said optical box.

PRIOR ART

[2] Fiber optics is increasingly used for a number of broadband applications, including voice, video, and data transmissions. As a result of the growing demand for broadband communications, telecom and cable service providers and/or operators are expanding their access networks (the entire infrastructure for connecting and providing service to users) in conventional metallic cable network technologies to fiber optic networks to increase the capacity and reach of their networks in order to provide more services to more subscribers both close and far. To facilitate this capacity and reach, fiber optic networks must employ additional fiber optic cables, hardware, and components, resulting in increased installation time, cost, and maintenance. This makes fiber optic networks more complex, requiring architectures that allow more efficient delivery of the fiber optic service to the subscriber. These architectures typically employ fiber optic network devices, such as optical connection terminals or optical boxes, for example, on branches of the fiber optic network. Fiber optic network devices act to optically interconnect branch fiber optic cables, separate or combine optical fibers into single or multiple fiber cables, and / or split or couple optical signals as needed.

[3] Telecommunications carriers and their access networks are increasingly taking advantage of Passive Optical Network (PON) technologies and product solutions compatible with these technologies. Usually these Access networks are designed with "star" or "double star" topologies, taking advantage of components called Optical Splitters, which are concentrated ("Local Convergence") or distributed ("Distributed Topology") over the external access network, but more commonly, with a primary splitter feeding in "star" topology a set of second level splitters, each feeding in turn ("double star") a set of customers of the Operator.

[004] Power distribution systems for optical signals in data transmission access networks are known to the art. Such systems use optical junction boxes to derive at least one optical fiber from an optical distribution cable containing a plurality of optical fibers, allowing at least one derived optical fiber containing a certain optical power to form a respective junction cable to be directed, at the end, to a respective optical termination box.

[5] Inside the optical termination box, the optical signals coming from the downstream optical fiber are split to a plurality of user optical fibers, and these are connected with a respective optical user termination cable ("drop" or access cable) projecting from said optical termination box.

[6] The optical termination box may feature, e.g., the construction subject to patent BR102016029000-7, with multiple outputs for connecting multiple user-terminated optical cables from a distribution or branch optical cable received in said optical box.

[7] These well-known distribution systems, using optical boxes, are designed, according to the design of the network installation, to provide the separation of the signals from the optical fibers of a multi-fiber distribution cable into one or more optical branch cables. Each branch optical cable contains at least one branch fiber and is received and retained, by connectorization or by fusion, in an optical termination box, so that at least one branch optical fiber can be connected, by connectorization or by fusion, with a respective user terminal optical cable ("drop" cable or access cable) projecting from a respective exit slot of said optical termination box.

[8] In the optical termination box construction described in document BR102016029000-7, aforementioned, the single-fiber branch optical cable has its optical fiber spliced/fused to an optical fiber extension that is split one or more times, with balanced optical power, into a plurality of split optical fibers, which are connected, by connectorization or fusion, to respective output adapters provided at the temaination box output openings.

[9] When the branch cable has multiple branched optical fibers, each of them can be connected directly or by means of fiber optic extensions, split with balanced optical power or even unsplit, and using connectorization or fusion, to a respective output adapter. To each output adapter a connector of a user terminal cable can be easily and quickly attached.

[0010] Another optical termination box construction can be seen in document US2014/0219621 Al, in which the branch and user termination cables are connectorized.

[0011] The aforementioned constructions were developed to facilitate the receiving and retention operations, in the optical termination box, without the risk of loosening the branch cable, generally of the multifiber type. Furthermore, such constructions are intended to facilitate the operations of connecting the fiber(s) of the branch optical cable to the box output adapters, performed by the installing operator, preferably outside the installation site of the termination box and before the box is closed.

[0012] Despite the constructive and operational advantages achieved with the well-known optical power distribution systems using junction and termination boxes, these systems do not guarantee an optimized optical signal at all the outputs of the network boxes. When the distribution cable is of the multi-fiber type, the branches performed by separating one or more fibers of the distribution cable to form the terminating cables along the network do not have the optimal splitting ratios in relation to the power demands of certain distribution network patterns in urban environments with higher density and in rural environments with lower user density.

[0013] in addition, pre-wired bus multifiber solutions use multifiber cables or cable bundles, and naturally have a very high diameter and weight. These characteristics represent a greater load (weight) to the poles, with direct implications for the hardware used and, in extreme cases, the need to remodel the infrastructure (replacing poles). In cases of maintenance or fiber breakage, it makes it difficult to repair and restore service.

[0014] Even in cases where a single fiber optical distribution cable is used, the branches of this single fiber along the network are made in a balanced manner in each junction box, both in a first branch splitting step and in a second branch splitting step, to form the optical fiber extensions to be connected to the respective user end cables. So even in this case, the distribution of optical power does not have the optimal split ratios with respect to the power demands of the usual distribution network patterns in urban and rural environments.

[0015] This well-known distribution of the available optical power in a distribution cable is carried out along the network within patterns defined by the optical power of the distribution cable fibers and of any symmetrically split optical fibers, making a "cascading" distribution of optical power difficult, and even preventing it, with the splits and any splits not providing optical power specifically sized according to the needs of the different end users to be served and also according to the characteristics of certain network topologies.

[0016] in many cases, this distribution, lacking flexibility and not being able to match the optical power made available to a user, ends up leading to deficiencies in the power made available or requiring the use of optical power attenuators in order to achieve the desired power matching, with resulting power loss.

[0017] In addition to the aforementioned aspects and related to the difficulty of optimizing the distribution of optical powers demanded along the network, in cases where the distribution is performed with little or no pre-connection of optical cables and optical extensions, this distribution becomes even more problematic when performed in field.

SUMMARY OF THE INVENTION

[0018] Due to the limitations of the known solutions as commented above, the present invention aims at providing a power distribution system in optical fiber access networks, using optical termination boxes and allowing a "cascaded" optical power distribution, with the branches and eventual splits providing optical powers sized according to the needs of the various end users.

[0019] The present invention relates to a power distribution system in optical fiber access networks using optical boxes, comprising a bus of optical boxes containing at least one branch optical box connected in sequence and terminated by a termination box. At least one optical junction box receives a distribution or junction cable consisting of a single optical fiber, providing a given input optical power, the said optical junction box having an input splitter to divide, in an unbalanced way, the input optical power received in the bus optical box into two parts. A first part of the incoming optical power is conducted to an output splitter. The output splitter divides the first part of the optical power into optical powers that are transferred to the respective user end optical cables. A second part of the incoming optical power is fed to the next optical box in the bus by a continuation cable, and so on until the last optical termination box is reached, in which the incoming optical power is made fully available to the user terminating optical cables.

BRIEF DESCRIPTION OF THE DESIGNS

[0020] The relevant system will be described below, with reference being made to the attached drawings, given for illustrative purposes only and in which: [0021] Figure 1 represents a diagram illustrating a portion of a fiber-optic network consisting of various junction boxes and a termination box, the first of which receives a distribution cable containing a single optical fiber and plugged into a termination box input adapter.

[0022] Figure 2 represents a block diagram by which the design directives for an optical box bus are taken.

[0023] Figure 3 illustrates a preferred embodiment of the present invention, where the bus comprises sequentially connected optical junction boxes terminated by a termination box.

[0024] Figure 4 represents an embodiment of the present invention, where the optical housings are each formed into two housing bodies and with the final termination optical housing formed into a single body.

DESCRIPTION OF THE INVENTION

[0025] As previously mentioned and illustrated in Figure 1, the system of simultaneous termination and branch of optical fibers in data distribution networks, uses 10 optical junction boxes and termination optical boxes.

[0026] For purposes of the context of the present invention, an optical junction box is defined as an optical box having a first splitter, which splits an input optical power into a continuation optical power, which will be routed to another optical box, and a termination optical power, which will be routed to a second splitter for splitting the optical power to be delivered to users (drop cable). In addition, an optical termination box is defined as an optical box that comprises only one splitter, which splits the incoming optical power to be delivered to the users (drop cable).

[0027] Preferably, the optical housings used are tubular, airtight optical housings comprising housing for splitters, bases and covers for different reinforced optical adapters. Examples of optical boxes that can be used are the CTOP-L 9P, CTOP-L 1013, and CTOP-L 1013 Generation 2 models, as well as the optical box disclosed in patent BR102016029000-7. However, it is clear to one skilled in the art that any optical box with an unbalanced splitter configuration followed by a balanced splitter can be used, as can a box with only balanced splitter for the last box, as per the bus disclosed in the present invention.

[0028] The optical box 10 can be formed with a closed end provided with an inlet opening (not shown) to receive a CD distribution optical cable containing one optical fiber (figure 1) or a plurality of optical fibers (figure 4), and an open end that is closed by a cover 20 that can be of the sealed or removable type.

[0029] Preferably, the DC distribution cable of an optical fiber is connectorized, i.e. provided with an EC input connector of any suitable construction, to be mated to and retained in an AE input adapter mounted, in a watertight manner, in the input opening of the housing 10. Non-limiting examples of a non-reinforced connector are of the SC model.

[0030] More preferably, the DC distribution cable, consisting of an optical fiber and providing a certain input optical power, can be preconfigured and connected to the optical box 10 by means of a reinforced connector external to the box.

[0031] In the realization example illustrated in Figure 1, the CD distribution cable contains only one optical fiber having a predetermined input optical power and which is connected, either by the CE input connector and AE input adapter or by optical fusion (not illustrated), to an EFO optical fiber extension internal to the housing 10 and which, in the illustrated example is provided with a CL link connector that is coupled to the AE input adapter.

[0032] The fiber optic extension EFO is routed to an input splitting device DE in which it is split into one continuation fiber FC and at least one termination fiber FT. The FT termination fiber, in turn, is led to a DS output splitter device, where it is split into multiple FU user fibers, each of them is selectively connectable, either by fusion or by connectorization, with the respective C-connectors and AS output adapters, which are provided in openings generally located in the cover 20, to respective CT user terminating optical cables that may preferably be connectorized.

[0033] Under the system now proposed, a desired portion of the incoming optical power, available in the distribution cable CD (which can be defined by a branch cable) with a single optical fiber, is divided from the latter, in a generally unbalanced manner in the input splitter device DE, into at least one termination fiber FT and one continuation fiber FC.

[0034] The FT termination fiber has a generally lower optical power than FC continuation fiber, and is sized according to the needs of the users to be served by it. To do this, the FT termination fiber is led, with or without fusion splicing EF of intermediate whips, to the DS output splitting device, where it is divided into multiple FU user fibers, which can have equal or unbalanced optical powers, to provide different connection points for users with different optical power demands.

[0035] The FC continuation fiber, containing any remaining input optical power in the optical box 10, can be provided with a CS output connector to be coupled with an AS output adapter provided in a respective opening of the box 10, usually in the cover 20. the CS output connector of a DC continuation cable to be routed to a following optical termination box 10 is attached to the AS output adapter. Such coupling between optical boxes is repeated successively until a termination optical box 12 is achieved in which the input optical power is made fully available to the user CT terminal cables, to be selectively connected to said optical box 12.

[0036] The branch system proposed by the present invention consists of one or more optical junction boxes 10 and one termination optical box 12, forming a bus of optical boxes. In this way, a first optical junction box 10 receives an input optical power, which is routed inside the box and connected to a DE input splitter that will split the optical power into a continuation optical power and a termination optical power. The continuation optical power will be routed to a new branch optical box 10, or to termination optical box 12. The terminating optical power will be routed to a balanced DS output splitter, which will divide the optical power among the users that will be served by the optical box.

[0037] As can be seen in Figure 1, two bypass optical boxes 10 and one termination optical box 12 are illustrated, where the continuation output of a first box is the distribution cable of the next optical box on the bus.

[0038] The system proposed here allows optical junction boxes 10, provided with a continuation output and termination outputs, and an optical termination box 12, provided with termination outputs, to be sequentially connected on a predetermined bus that receives a CD optical distribution cable with one fiber.

[0039] The bus features, in the optical junction boxes, unbalanced optical power split ratios between the continuation output and the termination outputs, and balanced or unbalanced split ratios between the termination outputs of each optical box.

[0040] The bus design must take into consideration some parameters, such as the number of users that must be served by the bus, the optical power input of the OLT (optical line terminal), as well as the minimum and maximum power that must be delivered to the ONU (optical network unit) or ONT (optical network terminal), i.e. the tenninals present at the users' premises.

[0041] According to the international standard ITU-T 0.984, "Classes" of "loss budgets" are defined, which must be met by the OLT and ONU transmission and reception equipment referenced above. Today, a recognized standard in this standard is Class C+, which provides the value of 32 dB (Thirty-two decibels) as the maximum attenuation limit between OLT and ONT devices, and this value is used as reference for the preferred embodiments Ii ere presented of the invention.

[0042] However, other OLT and ONT devices on the market have loss budget values ranging between 30 dB and 34 dB. Still, other existing or future evolving values/classes of the technology can be considered equally for the invention, since the demonstrations and concepts can be validated for different values/classes of equipment.

[0043] In addition to optical power considerations, the number of users that will be served by the bus is also a factor to be considered when constructing the bus.

[0044] The first is the split ratio (1:N) of the equipment port. Since the optical network has a point-to-multipoint technology, it is necessary to define if each PON equipment port will be shared for 32, 64, 128 ONT (optical network terminal) or according to technologies available in the market.

[0045] In the embodiments illustrated in the present invention, the solution is based on pre-connected optical terminal boxes with 8-output DS balanced output splitters, this metric already guides the amount of boxes that are arranged in the cascade. For example, for output splitters with a split ratio of 1:16, you would need 4 optical boxes, while for 1:4 output splitters, you would need 16 optical boxes.

[0046] Preferably, the split ratios are designed so that the optical signals, made available at the termination outputs of each branch optical box and the termination optical box, meet the optical sensitivity of the ONU. Such a premise allows the optical power delivered to users not to vary greatly, which helps prevent ONUs from not recognizing the optical signal or from saturating.

[0047] Nevertheless, all losses in the system must be taken into account, such as losses along the length of the cable, and losses by the fusion or connectorization of the optical fiber.

[0048] Figure 2 illustrates a block diagram through which the design directives for an optical box bus are taken, in order to consider system losses and still serve the maximum number of users.

[0049] As demonstrated, A represents the optical power emitted by the OLT transceiver (optical port), and due to the length of the optical fiber cable to the bus region, there is a characteristic fiber loss Pf that should preferably be considered in the bus design. Thus, the variable represents the characteristic loss of the fiber by the distance to the first box on the bus.

[0050] The optical power that actually reaches the first bus box, via a DC distribution cable, can be calculated as follows: where A = power emitted by the transceiver; fi characteristic loss of the fiber by the distance to the first box; and A' -input power of the first optical box in the bus.

[0051] According to the present invention, the junction boxes 10 have a DE input splitter with an unbalanced configuration, where the split ratio can be defined by m 1 inl, where ml is the portion of the OUT optical power routed to continuation fiber FC of the first optical box and n1 is the portion of the SU user output optical power routed to termination fiber FT.

[0052] As illustrated in Figure 1, the FT termination fiber is routed to a DS output splitter, which balances the optical power between the user termination cables (drop cable). Since the optical power made available by the FT termination fiber is divided, each terminating user will receive an attenuated power with respect to it. Such attenuation can be defined by PSU, which denotes the considered loss up to the user.

[0053] Thus, the power delivered to users at the termination output of the first optical box can be expressed by: A' Psi! [0054] The PSU value will depend on the 1:N split amount of the DS output balanced splitter of the optical box. In the preferred embodiment of the present invention, where the balanced splitter has 1:8 configuration, the PSU value is equal to 10 dB, for calculation purposes considering the currently available technology. However, other split ratios can be used, such as 1:4,1:8 or 1:16 balanced. Thus, a technician on the subject should consider the PSU value referring to the number N outputs of the 1:N output divider.

[0055] To ensure that a second optical box can be included in the bus and still meet the optical power demand of users, the inventors of the present invention have developed the following criteria: Ae if TA -> , you can insert an additional junction box on the busbar; and if ui. , you must complete the busbar with the termination box; where: B is the Loss budget to the user's UN. In this sense, the usual reference according to the ITU-T G.984 technical standard is 32dB.

[0056] As shown in Figure 2, the optical power A1/m I delivered to a second optical box is divided by a second input divider DE, which has a split ratio m2/n2. Thus, the termination output delivered to the users of the second box can be expressed by: A' 1111 * 112 [0057] So, analogously to the check made for the first box, to ensure that a third optical box can be included in the bus and still meet the optical power demand of the users, one should check: whether nts-na P5(7, it is possible to insert an additional junction box on the busbar; whether mIsnz, one should complete the busbar with the termination box.

[0058] For a third optical junction box, the input optical power will again be divided by the DS input divider, with split ratio m3/n3. Thus, the termination output delivered to the users of the second box can be expressed by: As [0059] So, analogously to the check made for the first and second boxes, to ensure that a fourth optical box can be included in the bus and still meet the optical power demand of the users, one should check: > B it is possible to insert an whether n'a additional junction box on the busbar; P-< whether zni.?-fir, one should complete the busbar with the termination box.

[0060] Through these metrics, one can anticipate from design data what the optimal bus configuration is to meet a design demand. The metrics can be generalized to calculate the possibility of a y-index branch optical box on the bus by: (It where A' is the input power of the first optical box in the bus; y is the index referring to the optical box to be included in the bus; mi is the split value referring to the second part of the optical power, routed to the continuation cable (CC), of the i-th optical box; ny_i is the split value referring to the first part of the optical power, routed to the termination cable (CT), optical box of index immediately preceding the box to be included in the bus.

[0061] If the inequality is satisfied, the y-index branch optical box can be included in the bus. Otherwise, the bus must be terminated by the optical termination box12. In this way, the number y of bypass optical boxes can be obtained.

[0062] According to a preferred realization, the mi/ni split ratio of the optical boxes along the bus is always decreasing from the first box to the last box, i.e.: 1/17 Tit.; > > 111 712 113 fl [0063] This assumption ensures that the boxes closest to the transceiver (OLT) should pass on the higher power to the DC continuation cable than the next optical boxes on the bus.

[0064] Furthermore, since m and n represent the split ratio of the DE input splitter, the following premise can be obtained: mmi+ ijmj = 1, where El = 1,2,3,. El III represents the number of the optical box on the bus.

[0065] Preferably, the split ratio of the DE input splitter of each of the branch optical boxes 10 has a split ratio between 95/05 and 55/45/40, with the numeral before the slash being the percentage of power routed to the next optical box 10 in the system and the numeral after the slash being the percentage of power routed to the access (drop) cables.

[0066] A preferred execution mode for the proposed system, not limited to this, comprises 7 sequentially connected optical junction boxes 10 terminated by a termination box 12, as illustrated in Figure 3.

[0067] In this preferred configuration, the optical boxes are configured with the following split ratios: in the first junction box of the system, 90% of the incoming optical power is routed to the subsequent junction box and 10% of the incoming optical power is routed to the access (drop) cables; in the second junction box, 90% of the incoming optical power available in this box is routed to the subsequent junction box and 10% of the incoming optical power in this second box is routed to the access (drop) cables; in the third junction box, 90% of the incoming optical power available in this box is routed to the subsequent junction box and 10% of the incoming optical power in this third box is routed to the access (drop) cables; in the fourth junction box, 85% of the optical power available at the input of this box is routed to the subsequent junction box and 15% of the incoming optical power in this fourth box is routed to the access (drop) cables; in the fifth junction box, 80% of the optical power available at the input of this box is routed to the subsequent junction box and 20% of the incoming optical power in this fifth box is routed to the access (drop) cables; in the sixth junction box, 70% of the incoming optical power available in this box is routed to the subsequent junction box and 30% of the incoming optical power in this sixth box is routed to the access (drop) cables; in the seventh junction box, 40% of the optical power available at the input of this box is routed to the drop cables, and 60% of the input optical power in this seventh box is routed to the eighth and final box in this system installation example. This box defines an optical termination box 10, its outputs to the drop cables, each of which receives, in balanced or unbalanced mode, a portion of the input optical power in this last optical termination box 10. Such a configuration presents the maximum use of optical power for an application where 64 users must be served.

[0068] Below are the optical losses calculated for this configuration, in dB Optical Splitter Serial output Outbound for UN Box service ( downstream attenuation) 1 Splitter -3.999 -24.899 -25.238 90/10 + Splitter 1x8 2 Splitter -5.403 -26.003 -26.342 90/10+ Splitter 1x8 1 Splitter -6.807 -27.407 -27.746 90/10 + Splitter lx8 4 Splitter -8.511 -27.411 -27.75 85/15 + Splitter 1x8 Splitter -10.615 -27.415 -27.754 80/20+ Splitter 1x8 6 Splitter -13.219 -27.619 -27.958 70/30 + Splitter 1x8 7 60/40 -13.219 -28.923 -29.262 Splitter + 1x8 Splitter 8 Splitter lx8 -27.627 -27.966 [0069] As illustrated in Figure 3, the upstream attenuation at the OLT is -29.645 dB. In this realization, the optical boxes used have pre-connected outputs, and the optical losses in the connection per connector are considered, as well as the losses in the cable length to the first optical box. The spacing between the optical boxes from the first one was 0.4 km, and the losses relative to this distance were neglected. However, if the boxes have greater distances between them, the losses along each DC continuation cable should preferably be considered.

[0070] Usually, and for the purpose of the tests performed in the present invention, the losses in the cable in the transmit direction, wavelength 1490 mu, is -0.26 dB/Km and in the cable in the receive direction, wavelength 1310 is -0.35 dB/Km. In addition, optical losses per cable connection per fusion of -0.1 dB, and per connectorization of -0.3 dB are considered. However, a person skilled in the art will find that new connection forms or different cables will have their respective losses, which can be considered in the optical power distribution bus design proposed in the present invention.

[0071] Although the preferred realization in Figure 3 uses a DS 1:8 output splitter, a technician in the field will note that other configurations can be used, such as 1:4 or 1:16, depending on the available optical power and the users' ONU sensitivity.

[0072] A second embodiment of the present invention will be described below, where the bus comprises 7 sequentially connected optical junction boxes 10 terminated by a termination box 12. The split ratio of the optical boxes is 90/10, 95/5, 90/10, 85/15, 80/20, 70/30 and 60/40, where the numeral before the bar is the percentage of power routed to the next optical box 10 in the bus and the numeral after the bar is the percent of power routed to the access (drop) cables.

[0073] Below are the calculated optical losses for this alternative configuration, in dB Optical Box Splitter Serial output Output for UN service (downstream attenuation) 1 Splitter 90/10 -3.999 -24.899 -25.238 + Splitter 1x8 2 Splitter 95/5 + -5.203 -29.603 -29.942 Splitter 1x8 3 Splitter 90/10 -6.607 -27.207 -27.546 + Splitter 1x8 4 Splitter 85/15 -8.311 -27.211 -27.55 + Splitter 1x8 Splitter 80/20 40.415 -27.215 -27.554 + Splitter 1x8 6 Splitter 70/30 -13.019 -27.419 -27.758 + Splitter 1x8 7 60/40 Splitter -1_6.423 -28.723 -29.062 + lx8 Splitter 8 Splitter lx8 --- -27.427 -27.766 [0074] The calculated data send attenuation on the OLT is -29, 445 dB. Again, cable losses in the transmit and receive direction and optical losses due to connection and fusion are considered. Thus, it is noted that the premise of the mi/ni split ratio of the optical boxes along the bus being always decreasing from the first box to the last box, although preferred, is not essential for the bus design according to the present invention.

[0075] These realization examples can be carried out entirely with pre-connection between the elements, thus avoiding user error and making installation quicker and easier.

[0076] Although both solutions (multi-fiber and single-fiber bus) use pre-connected cables, the issue of cable runs of lengths is advantageous in the realization where the cable is single-fiber, illustrated in Figure 1. This is due to the reduced diameter of the monofiber cable, thus allowing the leftover cable to be easily stored in the CTOP-L optical boxes' own accessories.

[0077] On the other hand, the current multifiber cables on the market, due to their diameter and rigidity, do not allow storage in the optical boxes themselves, so they are manufactured in project-specific lengths and installed without considering leftovers for maneuvers and maintenance. Thus, in multifiber solutions, the designer has to accurately gather this information in field.

[0078] Fixed length monofiber cables can be manufactured without this concern for accuracy because eventual leftovers can be easily stored. Even with an accurate survey, unforeseen problems can occur in the installation, and exact lengths make replacement difficult in cases of maintenance.

[0079] As can be seen from the above, two or even more input DE and output DS splitter devices can be used to provide different split and subdivision ratios, usually unbalanced, to give the system great versatility to adapt to the real needs of the different users of the optical fiber network, minimizing or even eliminating the need for the provision of optical attenuators.

[0080] Considering the characteristics of the proposed system, which allows to provide a versatile installation solution, using pre-sealed optical termination boxes for later and simple connection of CD distribution, CT termination and CC continuation connectorized optical cables, the DE input and DS output splitter devices can be pre-produced in a manufacturing environment and according to the potential characteristics of the network installation to be provided.

[0081] When using unsealed optical boxes 10 and DC distribution cables, termination cables, and DC continuation cables that are not connectorized, the different optical connections are made by fusion, usually at the network installation site.

[0082] As schematically illustrated in Figure 4, it may be convenient for each optical junction box 10 in the network to consist of a first box portion 10A and a second box portion 103, spaced away from the first box portion, according to the network topology characteristics.

[0083] in this construction, the CD distribution cable has its CE input connector, preferably pre-assembled, attached to an AE input adapter of the first 10A box portion of the first 10A junction box, to be connected to an EFO fiber extension internal to the first 10A box portion and provided with a CL link connector that is attached to the AE input adapter. The fiber optic extension EFO is received in an input splitting device DE, arranged inside the first housing portion 10 and in which the fiber optic extension is divided into a continuation fiber FC and a termination fiber FT, which are preferably each pre-connected with a respective connector C that is coupled to a respective output adapter AS, provided in a respective output opening (not shown) of the first housing portion 10A.

[0084] To one of the AS output adapters of the first 10A box portion a C-connector of a DC continuation cable is attached, preferably pre-connected at both ends and which has its opposite C-connector attached to an AE input adapter of the first 10A box portion of a subsequent branch box 10 of the network.

[0085] To the other AS output adapter of the first box portion 10A, of said first optical box 10 of the network, a C connector of a CDT terminal branch cable is attached, preferably preconnectorized at both ends and having its opposite C connector attached to an AE input adapter of the second box portion 103 of the same first optical box 10 of the network.

[0086] The second housing portion 103 houses a DS output splitter device in which an FT-terminating optical fiber is received, preferably preconnectorized and having its C connector mated to the C connector of the CDT terminating branch cable via the AE input adapter.

[0087] In the DS output splitter device, the FT termination optical fiber is split into multiple FU user optical fibers, each of which is selectively connectable, by connectorization, preferably by pre-connecting, with respective C-connectors and AS output adapters, which are provided in output openings (not illustrated) of the second housing portion 10B and into which are connectable respective CT user terminating optical cables that are preferably connectorized, as illustrated in the design figures.

[0088] The individual construction of each optical junction box 10 of the fiber optic network can be done in a single portion, as illustrated in Figure 1, or in two box portions, as illustrated in Figure 4, and the same network can contain both types of construction. However, the optical termination box 10 features only a single portion, as it houses only the DS output splitter device. The configuration of separate box portions is interesting since the bus operator can add the 10B termination box portions only when the need arises, i.e. when there have been subscriber users at the optical box location.

[0089] A preferred execution mode, not limited to this one, foresees the execution of the system entirely with pre-connection between the elements, and this pre-connection can be applied to all or part of the elements. This avoids user error and makes it quicker and easier to install the system.

[0090] However, it should be understood that the DC distribution cable can be received and axially locked inside the housing 10 without the use of a CE input connector, as described, for example, in patent application BR 10 2016 029000-7.

[0091] Considering the characteristics of the proposed system, which allows to provide a versatile installation solution, using pre-sealed optical junction and termination boxes for later and simple connection of optical fibers and preconfigured optical cables, the DE input and DS output splitter devices can be pre-produced in a manufacturing environment and according to the potential characteristics of the network installation to be provided.

[0092] Thus, the present invention is advantageous since the elements of the access network (optical distribution and termination boxes with onboard splitters) are arranged in the form of a sequential bus or cascade, i.e., a first element receives the optical signaling coming from the concentrator equipment (generally, a transmission over kilometers), distributes part of this signaling to a group of nearby clients (tens or hundreds of meters) and sends another part of the optical signaling to the second element of the sequence and so on, following rules and even limits imposed by the PUN transmission technology itself [0093] A second differential of this solution is that, unlike other transmission technologies where complex calculations and the use of proprietary software tools are required to define which element/splitter should be used in each (physical) location and position within a specific sequence, in this case the solution provides for the use of a bus with fixed elements/splitters. Both the quantity of the elements in the cascade, as well as specific attributes such as split ratios and optical signal attenuations, are defined in advance by the manufacturer, and simply installed by the Carrier throughout the Carrier's service region.

[0094] This avoids the need for the Operator to perform such calculations and definitions during the executive project for each section of the access network, facilitating the control of the application of the elements during construction, reducing the types of elements/products that it will keep in stock for construction and maintenance (replacement), among other tangible benefits that can be listed.

[0095] A third differentiating factor of the solution is the use of monofiber optical cables, according to the preferred embodiment in Figure 1 of the present invention. Other optical solutions use multi-fiber cables (multiple optical fibers within the core of a cable) or bundles of cables along the access network, while the proposed solution is based on interconnecting access network elements solely with single-fiber cables (a single fiber within the core of the cable), which is possible through conjunction with splitters in planned arrangement and sequences.

[0096] Solutions with multi-fiber cables naturally have a much larger diameter and weight than a monofiber solution, incurring in a larger occupation and load (weight) to the poles, with direct implications in the hardware used and, in extreme cases, in the need to remodel the infrastructure (changing poles).

[0097] The fourth differentiating characteristic to highlight is the construction of all elements (boxes/splitters and Access network cables) with a pre-connected characteristic, i.e., the elements are provided with factory-prepared optical connectors, for fast and simple "plug-and-play" interconnection.

[0098] Although only a few examples of realizations of the fiber optic termination and branch system in question have been presented here, it should be understood that changes may be made in the form and arrangement of the different component parts of the system without departing from the proposed inventive concept.

Claims (1)

1. CLAIMS1. System for distributing communication and power signals in fiber-optic access networks using optical boxes (10) comprising a bus of optical boxes containing at least one optical junction box (10) connected in sequence and terminated by a termination box (12); where at least every branch optical box (10) receives a distribution or branch cable (DC) formed by a single optical fiber providing a certain input optical power (A'), the branch optical box (10) having an input splitter (DE) to divide, in an unbalanced way, the input optical power (A') received in the bus optical box (10) into two parts; where a first part of the input optical power (A') is fed to an output splitter (DS), the output splitter (DS) splitting the first part of the optical power into optical powers that are selectively transferred to respective user optical terminating cables (CT), where a second part of the incoming optical power (A') is fed to the next optical box (10, 12) of the bus by a continuation cable (CC) consisting of a single optical fiber, and so on until the last optical termination box (12) is reached, in which the incoming optical power is fully made available to the user optical terminating cables (CT); characterized by the fact that each bypass optical box (ED) has, along the bus, a split ratio mi/ni, where mi is the split value referring to the second pre-defined part of the optical power, forwarded to the continuation cable (CC), of the i-th optical box and ni is the split value referring to the first pre-defined part of the optical power, forwarded to the termination cable (CT), of the index optical box immediately preceding the box to be included in the bus; where the mi/ni split ratio of a branch optical (DE) box along the bus is greater than or equal to the split ratio of the next box on the bus, as per: 1 M. 1113 171 > n2 n3 fli 2. System, according to claim 1, characterized in that it comprises y optical junction boxes (10) and a termination optical box (12), wherein the number y of optical junction boxes (10) is calculated according to the following inequation: Pcu B (tet,7 where A' is the input power of the first optical box in the bus; y is the index referring to the optical box to be included in the bus; mi is the split value referring to the second part of the optical power, routed to the continuation cable (CC), of the i-th optical box; ny-1 is the split value referring to the first part of the optical power, routed to the termination cable (CT), of the optical box of index immediately preceding the box to be included in the bus; Psu is the optical power loss to the user; B is the loss budget to the user's optical network unit (ONU); where, if the inequality is satisfied, the y-index optical junction box can be included in the bus; and otherwise, the bus must be terminated by the optical termination box (12) 3. System, according to claim 2, characterized in that the value of Loss Budget B is between 30 dB and 34 dB.4. System, according to any of claims 1 to 3, characterized in that the split ratio of the input splitter (ED) of each of the optical drop boxes (10) is between 95/05 and 55/45, with the numeral before the slash being the percentage of power routed to the next optical box (10) in the system and the numeral after the slash being the percentage of power routed to the output splitter (DS) and to the user (drop) optical terminal (CT) cables.5. System, according to any of claims 1 to 4, characterized in that it comprises seven branch optical boxes (10) and one termination optical box (12), wherein the portion of the incoming optical power into each optical box (10) of the network, is driven, and divided, with respective pre-defined unbalanced optical powers of the branch optical boxes (10) in the ratio of 90/10, 90/10, 90/10, 85/15, 80/20, 70/30, 60/40, wherein the numeral before the bar is the percentage of the power routed to the next optical box (10) of the system and the numeral after the bar is the percentage of the power routed to the access (drop) cables.6. System, according to any of claims 1 to 5, characterized in that the optical junction box comprises an input adapter (AE) connectorized to receive distribution cable (CD) connectorized and of predefined length with an input connector (CE).7. System, according to any of claims 1 to 6, characterized in that the output splitter (DS) of each optical box (10, 12) is an 1:4 or 1:8 or 1:16 balanced splitter.8. System, according to any one of claims 1 to 7, characterized in that each optical housing (10) comprises an output adapter (AS) connectorized to be coupled to the output connector (C) of a single fiber optic continuation cable (CC) connectorized.9. System, according to any of claims 1 to 8, characterized in that each optical junction box comprises an optical fiber extension (EFO) internal to the box (10), provided with a connector (CL), wherein the optical fiber extension (EFO) is led to the input splitting device (DE), in which it is split into a continuation fiber (FC) and at least one termination fiber (FT).10. System, according to any of claims 1 to 9, characterized in that the termination fiber (FT) is led to an output splitter device (DS) and is split into multiple user fibers (EU), each of which is selectively connectable, by connectorization, with respective connectors (C) and output adapters (AS).11. System, according to any of claims 1 to 10, characterized in that each optical junction box (10) comprises a continuation fiber (FC) containing the second part of the optical power input into the optical box (10), wherein the continuation fiber (FC) is provided with an output connector (CS) to be coupled to an output adapter (AS) provided in a respective opening of the box (10).12. System, according to any of claims 1 to 11, characterized in that output adapters (AS) are provided in openings located in the cover (20), for connection with user terminal optical cables (CT).13. System, according to any of claims 1 to 12, characterized in that each junction box (10) of the network comprises: a first box portion (10A), in which an optical signal that is transmitted by the distribution (DC) or continuation (CC) optical cable is received and split and transmitted in a terminal branch optical cable (CDT) and a continuation (CC) optical cable; and a second housing portion (10B) in which the optical signal that is transmitted by the terminal optical branch cable (CDT) is received and split and transmitted in multiple optical fibers, with respective optical powers to be transferred, by connectorization, to the respective user terminal optical cables (CT).14. System, according to claim 13, characterized in that the second housing portion (10B) is distanced from and connected to the first housing portion (10A) by the terminal branch cable (CDT).15. System for distributing communication and power signals in fiber-optic access networks using optical boxes (10) comprising an optical box bus containing seven optical junction boxes (10) connected in sequence and terminated by a termination box (12); in which the branch optical boxes (10) receive a distribution or branch cable (DC) formed by a single optical fiber providing a certain input optical power (A'), each of the branch optical boxes (10) having an input splitter (DE) to divide, in an unbalanced way, the input optical power (A') received in the optical boxes (10) of the bus into two parts; where a first part of the input optical power (A') is fed to an output splitter (DS), the output splitter (DS) splitting the first part of the optical power into optical powers that are selectively transferred to respective user optical terminating cables (CT), where a second part of the incoming optical power (A') is fed to the next optical box (10, 12) of the bus by a continuation cable (CC) consisting of a single optical fiber, and so on until the last optical termination box (12) is reached, in which the incoming optical power is fully made available to the user optical terminating cables (CT); characterized by the fact that the incoming optical power portion of each optical box (10) in the network is conducted, and divided, with respective unbalanced optical powers from the drop optical boxes (10) in the ratio of 90/10, 95/05, 90/10, 85/15, 80/20, 70/30, 60/40, with the numeral before the bar being the percentage of power routed to the next optical box (10) in the system and the numeral after the bar being the percentage of power routed to the access (drop) cables.