Patent Description:
As described for example in <CIT>, a guided surface wave can be a wave in the millimeter band that propagates along a conductor, for example a wire. The wire acts as a type of waveguide that functions by slowing the propagation velocity of electromagnetic waves below the free-space velocity, causing the wavefronts to slightly bend inwards towards the wire, which keeps the waves entrained in the wire. Bends of large radii are tolerated, but too sharp a bend in the wire will cause the line to radiate and lose some of the wave energy into space. Guided surface-waves can propagate down both insulated and bare metal wires or cables, including twisted pairs of wires.

A communication system based on surface waves in the range of tens to hundreds of Gigahertz (GHz), e.g. <NUM> to <NUM>, is attractive because it allows to reuse a significant amount of existing network infrastructure, i.e. the electric power distribution network or the existingtelephone or building cabling structure. Nonetheless, such a communication system also requires new components such as surface wave launchers, surface wave amplifiers, surface wave repeaters, surface wave splitters, etc. Examples of such components are referred to in the above cited US patent and related literature. <CIT> relates to an optical branch device for branching signal light in optical communication or the like. <CIT> relates to a stranded transmission line and uses thereof. <NPL>" describes a novel combination of simple fabrication techniques and cost-efficient polymer materials for the fabrication of planar polymer optical waveguides.

In view of the known art, it may be seen as a problem to provide a surface wave splitter, preferably a <NUM>-to-<NUM> type splitter, which can be easily integrated into existing network infrastructure.

A splitter and a network infrastructure incorporating such splitter is provided, substantially as shown in and/or described in connection with at least one of the figures, and as set forth more completely in the claims.

These and other aspects, advantages and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings.

<FIG> illustrates different exemplary bending angles of a wire for surface wave transmissions using a bending radius r;
The invention will be better understood with the aid of the description of embodiments given by way of example and illustrated by the figures, in which:.

As the present description refers to bending angle and bending radius, both terms are illustrated in <FIG>, respectively.

As illustrated in <FIG> the bending angle may be regarded as the angle between the (asymptotic or straight) parts of a wire at both sides (ingoing/outgoing) of a bend. <FIG> illustrates bending angles of <NUM>, <NUM> and <NUM> degrees, respectively. From measurements with surface waves it is found that the angle between ingoing and outgoing wire has an impact on the attenuation of the surface wave. Typically, the attenuation grows with increasing bending angle. While the attenuation is very high when the wire makes a <NUM>° turn, the attenuation is reasonable for angles up to about <NUM>°. While the three examples shown in <FIG> are depicted using the same bending radius r, it should be noted that the definition of the bending angle is not dependent on any given bending radius.

Referring again to <FIG> the bending radius r is defined as the radius of a circle, the circumference of which best matches the bending curve of the wire. A large bending radius cause a very smooth bend whilst for very sharp bends or kinks the radius may be close to zero. It has been found that larger bending radii correspond to decreased attenuation of the signal along the wire. However, a larger bending radius at a given bending angle extends the length of the bending section of the wire, hence a more compact device may require choosing the smallest feasible bending radius.

When considering the standard inter-pin distance of an RJ45 connector of <NUM> (as for example specified in the TIA/EIA-<NUM> standard) it is preferable to choose a bending radius which corresponds to a multiple of this distance, in particular twice the distance corresponding to approximately <NUM>. <FIG> illustrates the use of this bending radius in case of an initial +/-<NUM> degrees bending angle to first separate two wires after a <NUM>:<NUM> split and each using a second opposite -/+<NUM> degrees bending angle to redirect the orientation or direction of the two wires to the original orientation or direction of the wire before the split. The minimal distance of such an orientation preserving <NUM>:<NUM> split is <NUM> (=<NUM>*r), for a radius of <NUM>. In other words when using cascading orientation preserving <NUM>:<NUM> splits to generate a <NUM>:n splitter using at each split the bending radius of <NUM>, then each stage of the cascade has a length of <NUM> between the split points. In the case of <FIG>, one of the wires after the split is rotated out of the plane formed by the other two wires as indicated by the arrow.

<FIG> shows a schematic view of the internal wiring of a <NUM>-to-<NUM> surface wave splitter <NUM> in accordance with an example of the invention. It shows a single wire on the central office (CO) side of the splitter oriented to the central office (CO) and eight wires on the customer premises equipment (CPE) side of the splitter. The wires are shown entering and exiting, respectively, the splitter through interfaces or ports conforming in the physical dimensions with the RJ45 standard as commonly used in Ethernet applications. The ports are shown as RJ45(CO) and RJ45 (CPE), respectively.

Also shown is a (horizontal) virtual central plane <NUM> through the splitter defined as the plane which contains the contact points of the two ports RJ45(CO) and RJ45 (CPE). Perpendicular to the virtual central plane <NUM> is the first branch plane <NUM> and a second branch plane <NUM>. The first and the second branch plane <NUM>, <NUM> are also virtual and are used to show points indicating the locations where a wire intersects with the respective plane.

As shown, the single wire on the CO side of the splitter splits into two wires at a location within the splitter between the CO-side port RJ45(CO) and the first branch plane <NUM>. Hence, two intersection points or dots are visible on the first branch plane <NUM>. The single wire on the CO side is shown contacting the splitter at a single pin of CO-side port RJ45(CO). Each of the two wires intersecting the first branch plane <NUM> splits again twofold at a location between the first branch plane <NUM> and the second branch plane <NUM>. The now four intersection points are shown on the second branch plane <NUM>. Each of the four wires intersecting the second branch plane <NUM> splits again twofold at a location between the second branch plane <NUM> and the CPE-side port RJ45(CPE) of the splitter <NUM>. The resulting eight wires are each in contact with a single pin of the CPE-side port RJ45(CPE). As stated above, the pins of the CPE-side port RJ45(CPE) may all be located on a straight line, which may be located in the virtual central plane <NUM> or parallel to it.

Applying the same kind of orientation preserving bending and <NUM>:<NUM> splitting of as illustrated in in <FIG> to the splitting between virtual planes <NUM> and <NUM>, and to the splitting between virtual plane <NUM> and RJ45(CPE) illustrated in <FIG>, results in a minimum length of <NUM> for the whole splitter, corresponding to a minimal distance between the two ports RJ45(CO) and RJ45(CPE). It should be noted that a <NUM>:<NUM> split is preferred over higher numbers of splits such as <NUM>:<NUM> or higher splitting ratios. These higher ratios tend to introduce larger steps in the diameter at the transition point from the single wire to the multiple wires, which in turn may increase the attenuation of the surface wave.

To maintain bending angles of <NUM>° or less throughout within the splitter, the wires extend after a split into a different plane than before the split. To illustrate this out-of-plane layout of the wires, <FIG> shows the entry point of the single wire on the RJ45(CO) side at the central plane <NUM>. <FIG> shows the points where the two wire intersect with the branch plane <NUM> after the first <NUM>:<NUM> split. <FIG> shows the points where the four wires intersect with the branch plane <NUM> after the second <NUM>:<NUM> splits and <FIG> show the eight points where the wires intersect with the RJ45(CPE) port side of the splitter after the third <NUM>:<NUM> splits. At this stage the wires are all at the correct pin locations in the virtual central plane <NUM>.

A collapsed perspective view of <FIG> is shown in <FIG>. In <FIG>, the virtual central plane <NUM> is taken as the plane of reference for the single wire <NUM> as marked by a crossed circle entering the splitter through a single pin on the RJ45(CO) port side. At the first internal <NUM>:<NUM> splitter stage the wire <NUM> splits into a wire <NUM> and a wire <NUM>', where the unmarked numerals indicate a wire which is located above the virtual central plane <NUM> and marked numerals indicate a wire located below the virtual central plane <NUM>. At the subsequent <NUM>:<NUM> internal splitter stage the wire <NUM> splits into a wire 43a and a wire 43b, both located above the plane <NUM>. At the same internal <NUM>:<NUM> splitter stage the wire <NUM>' splits into a wire 43a' and the wire 43b', both located below the plane <NUM>. At the third internal <NUM>:<NUM> splitter stage the wire 43a splits into a wire 44a and a wire 44b. At the same third internal <NUM>:<NUM> splitter stage the wire 43b splits into a wire 44c and a wire 44d. At the same third internal <NUM>:<NUM> splitter stage the wire 43a' splits into a wire 44a' and a wire 44b'. At the same third internal <NUM>:<NUM> splitter stage the wire 43b' splits into a wire 44c' and a wire 44d'.

Again the wires 44a, 44b, 44c and 44d are shown located above the virtual central plane <NUM>, while the wires 44a', 44b', 44c' and 44d' are shown located below the virtual central plane <NUM>. However, each of the eight wires 44a -44d' aim for a pin location of the CPE-side port RJ45(CPE) as indicated by the eight circled dots in <FIG> (and as illustrated in Fig. 3D). The wires can be bent back into the same virtual central plane <NUM> as the single wire <NUM> applying bending angle of more than <NUM> degrees.

After the first internal <NUM>:<NUM> split, i.e. the wires <NUM> and <NUM>' are rotated out of the virtual central plane <NUM> and thus make better use in the internal space or volume of the splitter. In particular, one of the wires (wire <NUM>) is guided through the internal connector volume above virtual central plane <NUM> while the other wire at the internal <NUM>:<NUM> splitter stage (wire <NUM>') is guided through the connector volume below horizontal middle plane or virtual central plane <NUM>. Thus, by stretching the internal wiring and splitter stages into a truly three-dimensional space within the connector, a compact <NUM>:<NUM> splitter can be designed, which on the one hand remains pin compatible with conventional RJ45 connectors, while on the other hand limits the bending of all internal wires at a bending angle of around <NUM>°.

Having an RJ-<NUM> pin compatible splitter device facilitates the setup and maintenance of communication networks based on wire-bound surface wave communication by enabling network connections which go beyond simple point-to-point connections. Using the terminology of the old telephone networks, the advance provided by the splitters as described herein may be regarded as an analogy to the discarding of the old switchboards, where operators were responsible for setting up point-to-point connections between two parties of the telephone network.

<FIG> illustrates a schematic and very basic layout of components of a communication system <NUM> to transmit data from one copper access node to several homes over twisted pairs using surface waves communication. The system as shown comprises a surface-wave copper access node S-CAN <NUM>, which may be located in a central office or at any other distribution point or network node. The S-CAN <NUM> is shown including a transceiver <NUM> and surface wave launcher <NUM> to couple the signals from the transceiver <NUM> with a copper wire <NUM>. The copper wire <NUM> connects to the CO-side of a splitter <NUM> or a cascade of such splitters forming a <NUM>:n splitter. The splitter <NUM> in turn is connected via multiple copper wires <NUM> on its CPE side to n CPEs (Customer Premise Equipments) <NUM>-<NUM>,. ,<NUM>-n each comprising their respective transceiver <NUM> and surface wave launcher <NUM>.

<FIG> illustrates a schematic and extended layout (when compared to <FIG>) of components of a communication system <NUM> to transmit data from one copper access node to several customer locations over twisted pairs using surface waves communication. The system as shown comprises as in <FIG> a surface-wave copper access node S-CAN <NUM>. The S-CAN <NUM> is shown including a transceiver <NUM> and surface wave launcher <NUM> and integrates a splitter <NUM> or a cascade of such splitters forming a first <NUM>:n splitter. The first surface wave splitter <NUM> in turn is connected on its CPE side to a further surface wave splitter <NUM> which connects to CPEs (Customer Premise Equipments) <NUM>-<NUM>,. , <NUM>-n-<NUM> each with a transceiver <NUM> and a surface wave launcher <NUM> as already shown in <FIG>. In the connection to CPE <NUM>-n-<NUM> the surface wave launcher is shown integrated into a separate wall plug <NUM>. This particular set-up may have advantages as beyond the launcher the signal continues on the CPE side as normal wire-bound EM signal, i.e. as a LAN-type signal, not sensitive to attenuation through bending.

The system <NUM> of <FIG> further includes example of a communication line including a surface wave repeater <NUM>. The repeater is able to receive a signal with a launcher and launch it again. Such a unit is helpful in cases where the surface wave has less desired properties that yield higher attenuation than systems where the signal is transmitted in a cable. This are e.g. going around curves where the material on the inner side results in strong attenuation, window feed through, etc. The system <NUM> of <FIG> further includes example of a communication line including a surface wave amplifier <NUM>. The amplifier may contain also an amplifier logic (for amplification in both up- and downlink) between the two launchers. The system <NUM> of <FIG> further includes example of a communication line including a surface wave wireless bridge <NUM>, which can be applied to connect the surface wave system to a wireless system (not shown). The surface wave wireless bridge can be seen as a unit that translates the surface waves into a wireless signal that is sent over an antenna attached to the twisted pair cable. The surface wave wireless bridge may contain a filter (to select the desired frequency range) and a bi-directional amplifier (or two amplifiers for up- and downlink).

The system may make use of a multiuser approach to mitigate crosstalk and other signal interferences between the signals of different users (CPEs). This can be done either by assigning different frequencies, different time-slots or different codes to a specific user, or any other multiple access scheme, for example.

Claim 1:
A splitter having a housing for wire-bound surface wave communication with a plurality of I/O ports (RJ45(C0), RJ45(CPE)) for connecting external wires carrying surface waves and having internal wires (<NUM>, <NUM>, <NUM>', 44a-44d') connecting at least one of the plurality of I/O ports through the interior of said housing with at least two other of the plurality of I/O ports to enable the communication of surface wave signals through the splitter, wherein the connected I/O ports define an internal plane (<NUM>) within the interior of the housing of the splitter and wherein one or more of the internal wires (<NUM>, <NUM>,<NUM>', 44a-44d') extend into the volume of the housing above and/or below the internal plane (<NUM>).