Optical cable network with an excess number of leads in reserve

An optical cable network constructed with light waveguide cables for one or more transmission systems comprising a plurality of existing and planned connecting points for individual system nodes. In order to facilitate the network set-up, as well as the network expansion, all existing and planned connecting points of an optical cable network are connected in series with one another by means of through extending light waveguide cables that comprise a plurality of fibers. All fibers are laid in the multiple loops at each connecting point for the formation of a cable reserve, with only the fibers needed for a system connection being cut and spliced to components for the connecting point.

BACKGROUND OF THE INVENTION 
The present invention is directed to an optical cable network constructed 
with light waveguide cables for one or more transmission systems including 
ring systems, star systems and bus systems, said network comprising a 
plurality of existing and, respectively, planned connecting points for 
individual system nodes. 
Local-area networks, which are referred to as LANs, are playing an 
increasing part within present-day communication system. The optical local 
networks constructed with light waveguides are of great significance in 
turn within these local area networks. Optical networks comprise a number 
of advantages over electrical networks. Among other things, a considerable 
simplified laying of the optical cable in comparison to laying of the 
electrical network occurs because of the smaller dimensions of the optical 
cable and because of the lower weight of the optical cable. This is 
opposed by a disadvantage in an optical network in comparison to 
electrical network that the interconnects and distribution of light 
waveguides is not as unproblematical as with electrical conductors because 
every connection in an optical network between two light waveguides leads 
to an attenuation loss. 
The maximally allowable link attenuation in an optical cable network is 
determined by the output power of the transmitter and by the input 
sensitivity of the receiver. What is understood by link attenuation is the 
maximum loss on the path between two arbitrary terminals of a transmission 
system. The link attenuation is essentially composed of the line 
attenuation and of the auxiliary attenuations. The auxiliary attenuations 
are caused by aging, repair splices, optical distributors (attenuation per 
connector location of .ltoreq.1 dB), splices (0.1 -0.2 dB), optical relays 
(insertion attenuation of 1-1.5 dB) and by the shortening of the 
bridgeable link length due to dispersion in the light waveguide. 
Within the present-day optical cable networks which comprise one or more 
transmission systems, the cabling of the light waveguides almost always 
occurs with the assistance of light waveguide distributors. These light 
waveguide distributors serve the purpose of branching light waveguide 
cables, as well as the purpose of problem-free reconfiguration or, 
respectively, connecting new optical fiber paths or optical fiber rings. 
Light waveguide distributors are also very frequently provided as a prior 
foundation for potential enlargement of the optical network. 
When one assumes that a plug connection between two light waveguide leads 
can cause an additional attenuation of up to 1 dB, then the disadvantage 
of light waveguide distributors and plug connections are universally 
obvious for the set-up of optical cable networks. 
SUMMARY OF THE INvENTION 
An object of the present invention is to provide an optical cable network 
of the above-noted types that guarantees easy installation and 
expandability of optical, local-area networks, given a low cost prior 
foundation without thereby causing additional attenuation losses. 
This object is inventively achieved in an optical cable network including 
one or more transmission systems, such as ring systems, star systems, and 
bus systems, wherein all the existing and, additionally, planned 
connecting points of the optical cable network are connected in series 
with one another by means of a prescribed plurality of through light 
waveguide leads with each lead being composed of two fibers in one or more 
light waveguide cables, the plurality being defined based on the maximum 
size of the network in that the through light waveguide leads are laid in 
a plurality of loops per connecting point for the formation of cable 
reserve and only that light waveguide lead or, respectively, those light 
waveguide leads required for a system connection are parted, whereby the 
corresponding light waveguide leads are joined to the corresponding system 
component on the basis of a splicing technology. 
The optical cable network of the present invention can be easily installed 
with little prior cost and can also be easily expanded as needed. The 
prior costs are merely composed of the employment of one or more cables in 
which additional light waveguide optical fibers are provided for future 
applications and is further composed of the formation of cable reserves by 
cable loops which are provided respectively at each of the original and 
planned connecting points. Since the principle costs incurred are the 
actual laying work for the cable, the added cost due to the additional 
fibers and the cable loops are of no substantial consequence. 
The easy installation and/or expansion of the optical cable network of the 
invention occurs from the fact that during installation or, respectively, 
expansion of the optical cable network, the corresponding optical fiber 
that has to be parted only at one or more connecting points in order to 
subsequently join the free ends to the respective system component with 
splices. A further significant advantage of the cable network of the 
present invention is that an easy expandability of the network is enabled 
without employing branching or, respectively, optical distributors as 
previous done. The expansion leads to practically no additional 
attenuation loss. Because of this reduced losses for attenuation, greater 
distances can be bridged with the local optical network of the present 
invention when compared to traditional networks. 
An expedient development of the network of the invention is characterized 
in that the formation of the cable reserve respectively occurs inside a 
connector box in which the system component needed for a connection are 
also situated. A surveyable and clear network format occurs due to the 
formation of the cable reserves inside the connector boxes including those 
connector boxes which are not in use in the system during the initial 
installation. 
Other practical developments of the cable network of the present invention 
will be readily apparent from the following description of the preferred 
embodiments, the drawings and claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The principles of the present invention are particularly useful in a 
portion of the optical cable network, as schematically illustrated in FIG. 
1. Only those parts of the network needed for an understanding of the 
invention are shown. The illustrated embodiment assumes an optical cable 
network wherein all the connecting points, i.e., the connecting boxes, are 
connected with a cable K that comprises n light waveguide fibers F1-Fn. In 
the illustrated embodiment of FIG. 1, only the connector boxes AD1-AD6 are 
shown. The partially illustrated optical network has two transmission 
systems, one being a star system and the other being a ring system. 
Of the star-shaped transmission system, FIG. 1 shows the central terminal 
or station StZ can be fashioned as an active optical star and has two 
terminals St1 and St2 that belong to this transmission system. The 
connector boxes AD2, AD4 and AD6 are allocated to this star system. Light 
waveguide fibers F1-F6 are also used by this system, with only the 
illustrated portions being considered. Each dot in FIG. 1 denotes a 
splice. It should be mentioned that, in this context, the two fibers are 
combined to form a light waveguide lead in the illustrated exemplary 
embodiment. Since the light waveguide cable K connects all connecting 
points of the optical cable network to one another, it can be seen that 
the same fibers can be allocated to different systems corresponding to 
their topical position. Proceeding on the basis of the exemplary 
embodiment, the fiber sections of the fibers F1-F2 that lie at the left of 
the terminal St1 and St2 can be employed for cabling other systems without 
having to install new cables or fibers. 
FIG. 1 also shows a part of a ring system that comprises terminals R1 and 
R2. The fibers F7 and F8 are allocated to this ring system in the 
illustrated exemplary embodiment. The connection of the terminals of the 
ring system occur from FIG. 1. Technical details of the coupling of the 
terminals shall not be discussed in greater detail here, since these are 
conventional and not critical to the present invention. 
The fibers F9-Fn in the illustrated embodiment would be reserve fibers that 
would be placed in use given a later expansion of the optical local-area 
network. Since the future, maximum extent is usually predictable given a 
new installation of an optical cable system, it is possible to immediately 
lay the optimum plurality of light waveguide fibers upon new installation 
of the network. 
The connector box AD3 shown in FIG. 1 is a connecting point that will be 
provided later in the optical cable network. This connector box AD3 can 
serve the purpose of connecting a terminal to an arbitrary, third 
transmission system that is not shown. The connector box AD3, however, can 
also be used to expand the existing ring system by a terminal between the 
existing terminals R1 and R2. It would also be conceivable to expand the 
illustrated star-shaped transmission system by a station St3 via the 
connector box AD3 with the assistance of two fibers of the reserve fibers 
F9-Fn. The enormous flexibility of the optical cable system of the 
invention, given set-up as well as given a potential expansion, is readily 
apparent from these few examples. 
FIG. 2 shows a perspective view of a connector box AD. A cable K is 
stripped of installation within the connector box and the individual light 
waveguide leads are laid into a plurality of loops 18. When a terminal of 
a transmission system is to be connected to this connector box, then only 
the lead provided for the system connection is cut or parted to form free 
ends 17. The free ends 17 of the parted light waveguide lead are connected 
to the system component with a splicing technique. Included among these 
system components, for example, are an optical transmitter 13 and an 
optical receiver 14, as well as a light waveguide relay 16. In the design 
of optical rings, it is also necessary, for safety reasons, to insert a 
light waveguide relay at the taps for a terminal. The light waveguide 
relay bridges the ring at this location when the station connected to the 
ring is malfunctioning or when the station is being disconnected from the 
ring. One part of the system components is accommodated on a receptacle 
plate 11, to which corresponding printed circuit boards can also be 
secured. A drop cable connector 15 is situated on the receptacle plate 11. 
The connector box is closed with a cover or cap 12. 
The cable loops 18 are needed in order to attach splices to the free ends 
of the parted light waveguide fibers, given a later expansion of the 
optical, local-area network, since a defined fiber length preceding and 
following the splice is necessary for a splicing operation. On the other 
hand, these cable loops mean practically no additional attenuation for the 
through fibers. 
Although various minor modifications may be suggested by those versed in 
the art, it should be understood that we wish to embody within the scope 
of the patent granted hereon all such modifications as reasonably and 
properly come within the scope of our contribution to the art.