WO2018055409A2

WO2018055409A2 - Multiplexing apparatus and method of use thereof

Info

Publication number: WO2018055409A2
Application number: PCT/GB2017/052857
Authority: WO
Inventors: Martin Gostling; Duncan AUSTIN
Original assignee: Radio Design Limited
Priority date: 2016-09-26
Filing date: 2017-09-25
Publication date: 2018-03-29
Also published as: WO2018055409A3; GB201616267D0

Abstract

There is provided multiplexing apparatus including at least two input ports and at least two output ports. At least three filter means are provided in the apparatus and are operable over at least three different radio frequencies or frequency bands. Each filter means is connected to an input port and an output port. Each of said filter means is multiplexed to at least one other of said filter means at at least one end thereof. At least a first of said filter means is multiplexed at a first end to a second of said filter means. The first filter means is multiplexed at a second end to a third of said filter means. The first, second and third filter means are different.

Description

Multiplexing Apparatus and Method of Use Thereof

This invention relates to multiplexing apparatus and to a method of use thereof, and particularly to multiplexing apparatus of a type for combining and/or splitting radio frequency signals.

Mobile phone operators seek to minimise the capital expenditure (capex) required to build a wireless network as well as minimise the ongoing operating expenditure (opex). If an operator provides both 3G (3rd generation mobile communication) and 4G (4th generation mobile communication) wireless network services then a way to reduce opex is for the two networks and/or for two different operators to share a cell site.

An example of a typical cell site arrangement, forming part of a wireless telecommunications network, typically comprises a mast, an antenna located at the top of the mast for transmitting and/or receiving one or more radio frequency signals and a base station (BTS) located at the base of the mast. The BTS typically includes a transceiver that generates one or more radio frequency signals for transmission to a mobile phone unit via the antennae, as well as receiving one or more radio frequency signals from a mobile phone unit via the antennae. However, it is becoming increasingly common for different wireless service operators to share cell sites and/or for a particular wireless service operator to provide different services, such as 2G, 3G and 4G at the same cell site to save costs. The greater the number of different radio frequency bands being transmitted and/ or received at a particular cell site, the greater the amount of equipment that is required at the cell site. This leads to problems of space at the cell site and requires electronic apparatus to be provided to prevent interference between the radio signals in different radio frequency bands. As a result of these problems, it is becoming more common to locate some components of the BTS at the top of the mast.

An example of a conventional cell site that provides equipment for operation of the cell site over at least three different radio frequency bands is shown in Figure la. In this example, the three different radio frequency bands are 900MHz, 1800MHz and 2100MHz. The cell site 2 comprises a mast 4 with two antennae 6, 8 located at the top of the mast. Antenna 6 is for the transmission and/ or receiving of one or more signals in the 900MHz frequency band and antenna 8 is for the transmission and/or receiving of one or more signals in the 1800MHz frequency band and the 2100MHz frequency band. Two BTSs 10, 12 are provided at the base of the mast 4 for transmitting one or more radio frequency signals from a mobile phone unit to the antennae 6, 8. More particularly, BTS 10 transmits and/or receives one or more radio frequency signals in the 1800MHz frequency band, and BTS 12 transmits and/ or receives one or more radio frequency signals at the 900MHz frequency band. A combiner 14 is provided at the base of the mast and is connected to BTS 10, 12 for combining radio frequency signals from the two BTS 10, 12 and passing the signals up the mast along a coaxial cable 16, and for splitting signals passing down the mast from the antennae 6, 8 to the appropriate BTS 10, 12. A combiner/splitter 18 is provided at the top of the mast 4 for combining and splitting the 900MHz and 1800MHz radio frequency signals to/from the antenna 6, 8. A remote radio unit 20 is provided at the top of the mast 4 for receiving and/ or transmitting one or more radio frequency signals in the 2100MHz frequency band. A further combiner/ splitter 22 is provided at the top of the mast 4 and is connected between the remote radio unit 20 and antenna 8, and between the combiner/ splitter 18 and the antenna 8. Co-axial cables 24, 26, 28 connect the combiner/ splitters 18, 22, the remote radio unit 20 and the antenna 8 together.

An example of a circuit diagram showing the components of one of the conventional combiner/ splitter units 22 used in the abovementioned cell site arrangement is shown in Figure lb. The unit 22 comprises a common port 30 located at one end of the unit for connection to antenna 8, and two channel ports 32, 34 located at the opposite end of the unit for connection to the remote radio unit 20 and the combiner/ splitter 18 respectively. Two radio frequency paths 36, 38 are provided in unit 22 for allowing the transmission and/ or receiving of one or more radio frequency signals in the 2100MHz frequency band and the 1800MHz frequency band respectively. Each path 36, 38 is connected to channel ports 32, 34 at one end and are multiplexed together at the other end to form a common signal path 39 for connection to common port 30. A first filter 40 is provided in path 36 for allowing the passage of radio frequency signals in the 2100MHz frequency band therethrough but substantially preventing the passage of radio frequency signals outside of this frequency band therethrough. A second filter 42 is provided in path 38 for allowing the passage of radio frequency signals in the 1800MHz frequency band therethrough but substantially preventing the passage of radio frequency signals outside of this frequency band therethrough.

The combiner/splitter described above can also be referred to as a diplexer or multiplexing apparatus. The other combiner/splitter 18 located at the top of the mast is typically the same or similar to the combiner/ splitter unit 22 in terms of topology and/ or block diagram form but in reverse.

A direct current (DC) and low frequency (typically below 15MHz) control signal bypass path can be provided if required (not shown). This allows DC current and low frequency control signals used to power and control RF equipment at the top of the mast respectively, such as TMAs or motorised antenna position equipment (i.e. Remote Electrical Tilt (RET) motors), to bypass filters 40, 42 and be received by the equipment. The low frequency control signals are often referred to as Antenna Interface Standards Group (AISG) control signals and relate to standard based control signals for digital remote control and monitoring of antenna line devices in wireless communication systems. Bias T's (not shown) can be provided either side of the filters 40, 42 to allow DC and low frequency signals to be transmitted through the unit via the DC bypass paths. DC blocks in the form of capacitors can be provided between the Bias T's and the filters to prevent DC and low frequency signals entering the filters as they may provide a DC short circuit and/ or damage the same. Although the abovementioned cell site arrangement allows the cell site to operate over three different radio frequency bands, a number of problems are associated with this type of cell site arrangement. Firstly, the cell site requires a cascade of electronic units to be provided at the top of the mast. This can be difficult to rig together, it is harder to maintain the equipment and there is hmited space at the top of the mast. Due to the relatively large number of connections between the cascaded units, this results in high passive intermodulation (PIM). In addition, due to the number of units and interconnecting cables the RF signals are required to pass through, there is high insertion loss. The abovementioned problems typically increase with the more frequency bands that the cell site is required to operate over.

It is therefore an aim of the present invention to provide multiplexing apparatus that overcomes the abovementioned problems.

It is a further aim of the present invention to provide a method of using or assembling multiplexing apparatus that overcomes the abovementioned problems.

According to a first aspect of the present invention there is provided multiplexing apparatus, said multiplexing apparatus including at least two input ports and at least two output ports, at least three filter means are provided in the apparatus and are operable over at least three different radio frequencies or frequency bands, each filter means is connected to an input port and an output port, and wherein each of said filter means is multiplexed to at least one other of said filter means at at least one end thereof, and at least a first of said filter means is multiplexed at a first end to a second of said filter means, and the first filter means is multiplexed at a second end to a third of said filter means, the first, second and third filter means being different.

Multiplexing apparatus according to the present invention has the advantage that only a single combiner/ splitter unit is required to be provided to allow operation over the three different radio frequencies or frequency bands, or a reduced number of combiner/splitter units are required to be provided compared to prior art arrangements, which is particularly advantageous when the apparatus is being used at the top of a mast. Since less co-axial cables are required for connection of the apparatus of the present invention in a cell site arrangement compared to conventional arrangements where multiple combiner/ splitter apparatuses are provided, this reduces the insertion loss and PIM normally associated with the apparatus. The single combiner/ splitter unit or the reduced number of combiner/ splitter units are easier to rig at the top of the mast and are easier to maintain. As a result, the apparatus of the present invention is more cost effective and is a more compact unit for use in locations where there are space restrictions.

It is to be noted that the apparatus of the present invention can be used at any suitable location, including, but not limited to, the top or base of a telecommunications/ antenna mast.

A further advantage of the present invention is that the apparatus is factory configurable, in that the same or a similar hardware arrangement with minor modifications can be used to cover different combinations of multiple frequency bands. For example, the same housing could be provided with possible minor differences in the circuitry contained in the same.

Reference to the first, second and third filter means being different refers to the radio frequencies or radio frequency bands that the filter means are operable over being different.

Preferably each, or at least one, filter means is provided in or associated with a radio frequency (RF) pathway within the apparatus. An RF pathway allows the transmission and/ or receiving of one or more RF signals therealong in use.

Preferably the apparatus includes at least three RF pathways within the apparatus. Further preferably each of the three RF pathways is associated with one of the at least three different radio frequencies or radio frequency bands.

Preferably the first filter means is provided in a first RF pathway, the second filter means is provided in a second RF pathway, and the third filter means is provided in a third RF athway.

Preferably each RF pathway is associated with a different frequency band or set of frequencies. It will be appreciated that, in one example, 3 + n filters can be provided in the apparatus and 3 + n pathways can be provided, with one filter provided in each pathway, and wherein n = an integer.

In one embodiment at least one of the RF pathways is connected between an input port and an output port for transmitting and/or receiving one or more RF signals therebetween in use.

In one embodiment at least one of the RF pathways is multiplexed to at least one other RF pathway.

In one embodiment at least one of the RF pathways is multiplexed at a first end to a first, or at least first, RF pathway and is multiplexed at a second end to a second, or at least a second, RF pathway.

In one embodiment at least two of the RF pathways are multiplexed together to form a common pathway for connection to one of the input ports, and at least two of the RF pathways are multiplexed together to form a common pathway for connection to one of the output ports.

Preferably the filter means are provided for allowing the passage of one or more RF signals therethrough of at least a first set of frequencies or frequency band and for preventing or substantially preventing the passage of one or more RF signals therethrough of at least a second set of frequencies or frequency bands. The first and second sets of frequencies or frequency bands are different or substantially different.

In one embodiment the at least second set of frequencies or frequency bands is anything other than the first set of frequencies or frequency band.

In one embodiment a single filter means is provided in each of the RF pathways in the apparatus.

In one embodiment two or more filter means are provided in each of the RF pathways in the apparatus.

In one embodiment one of said filter means allows the passage of one or more RF signals of a single set of radio frequencies or a single radio frequency band only and prevents, or substantially prevents, the passage of one or more RF signals of any other radio frequency band therethrough.

In one embodiment one of said filter means allows the passage of one or more RF signals of two or more sets of radio frequencies or two or more RF signal frequency bands and prevents, or substantially prevents, the passage of one or more RF signals from any other frequency band therethrough. The two or more sets of radio frequencies or radio frequency bands are different or substantially different.

Preferably the filter means includes any or any combination of a Low Pass Filter, a High Pass Filter, a Band Pass Filter or a Band Stop Filter.

It will be appreciated that any or any combination of the abovementioned filter means and/ or RF pathways can be provided and still fall within the scope of the present invention.

In one embodiment one or more direct current (DC) and/or control signal bypass paths are provided for the transmission and/or receiving of DC power and/or one or more control signals fherealong in use. The one or more bypass paths are typically provided between an input port and an output port. Preferably the one or more bypass paths are bypassing one or more filter means in a RF athway.

Preferably the one or more control signals are in the form of antenna interface standards group (AISG) signals.

Preferably the one or more DC/AISG/ control signal bypass paths include one or more DC blocks to prevent the passage of DC/AISG/control signals through one or more, or all, of the filter means if required.

Preferably the one or more DC blocks are in the form of, or include, one or more capacitors.

Preferably a DC block is connected to each end or either end of the filter means.

The DC blocks can be provided in a RF pathway allowing the passage of a single set of RF frequencies or single RF frequency band therethrough, and/ or they can be provided in a RF pathway or a common RF pathway allowing the passage of two or more sets of RF frequencies or two or more RF frequency bands therethrough.

Preferably a control means or a control unit is provided in the apparatus in or associated with the one or more DC/AISG/control signal bypass paths. The control means or unit is typically arranged to detect the presence of DC voltage on one or more of the input ports and/or to detect DC short circuit on one or more of the output ports.

Preferably the control means or control unit detects and/ or measures one or more electrical values at or associated with any of the input ports and/ or output ports.

Preferably the control means or control unit is arranged to control whether any of the one or more bypass paths are enabled and/or disabled for DC according to one or more electrical values detected and/or measured at one or more of the ports. Preferably at least one, or all, the DC/AISG/control signal bypass paths are connected to the control means or unit internally or within the apparatus.

In one embodiment the one or more DC/AISG/control signal bypass paths can be arranged and/ or the control means or unit can be arranged so as to make the multiplexing apparatus factory and/or operator configurable for DC, control signals and/ or AISG.

In one embodiment the control means or unit can be arranged to follow different rules to allow different input ports to be connected to different output ports via the DC/AISG, control signal bypass paths.

In one embodiment one or more electrical switches and/ or modems are provided in or associated with the one or more DC/AISG/control signal bypass paths to allow the bypass paths to be moved between enabled and/ or disabled conditions for DC.

Preferably the control means or unit controls the electrical switches and/or modems in use.

In one embodiment the one or more electrical switches are one or more external electrical switches (i.e. external to a housing body of the apparatus).

In one embodiment the control means or control unit includes any or any combination of micro-processing means, electric circuitry, memory means and/or the like.

In one embodiment the control means allows the apparatus to determine which types of connection have been made at one or more connection ports (i.e. whether it is an input port and/or an output port) (i.e. it determines the orientation of the apparatus by determining if a port is in a multiplexing mode or a de-multiplexing mode.

Any or any combination of components of the control means and/or control ckcuitry can be included herein by reference to WO2015/082903, the contents of which are incorporated herein by reference.

In one embodiment, the control unit or means is arranged such that if it detects DC on an input port, it allows connection of this input port to all output ports at which DC short circuit is not detected. Preferably if more than one input port is detected as having DC, the control unit or means refers to an internal preference table stored in or associated with the control unit or means to determine which input port is to be used for supplying DC through the apparatus.

In one embodiment, the control unit or means determines which input ports and output ports are enabled or disabled for DC based on the RF signal flow through the apparatus. For example, the input ports and output ports can be enabled/ disabled in the same manner as the RF signal flow. If the control means or unit detects two or more input ports have DC, these input ports can be connected to one output port. The control unit or means can refer to an internal preference table stored in or associated with the control means or unit to determine which of the two or more input ports is to be enabled for DC.

In one embodiment an internal modem or one or more external switches could be provided for control by the control means or unit to set which input ports and/ or output ports are to be enabled or disabled for DC in use.

According to a second aspect of the present invention there is provided a method of using multiplexing apparatus, said multiplexing apparatus including at least two input ports and at least two output ports, and at least three filter means operable over at least three different radio frequencies or frequency bands, wherein said method includes the step of connecting each filter means to an input port and an output port, multiplexing each of said filter means to at least one other of said filter means at at least one end thereof, multiplexing at least a first of said filter means at a first end to a second of said filter means, multiplexing the first filter means at a second end to a third of said filter means, the first, second and third filter means being different.

Embodiments of the present invention will now be described with reference to the following figures:

Figure la (PRIOR ART) is a simplified view of a conventional mobile telecommunications cell site arrangement;

Figure lb (PRIOR ART) is a simplified circuit diagram of conventional multiplexing apparatus used in the cell site arrangement of Figure la;

Figure 2 is a simplified view of a mobile telecommunications cell site arrangement according to an embodiment of the present invention;

Figure 3 is a simplified circuit diagram of multiplexing apparatus that can used in the cell site arrangement of Figure 2 according to one embodiment;

Figure 4 is a simplified circuit diagram of multiplexing apparatus according to a further embodiment of the present invention; and

Figure 5 is a simplified circuit diagram of multiplexing apparatus according to a yet further embodiment of the present invention.

Referring to figure 2, there is illustrated a mobile telecommunication cell site arrangement 100 according to an embodiment of the present invention. The same reference numerals are used to refer to the same features referred to in Figures l and lb.

In this example the cell site 100 is arranged to operate over three different radio frequency bands; 900MHz, 1800MHz and 2100MHz. The cell site 100 comprises a mast 4 with two antennae 6, 8 located at the top of the mast. Antenna 6 is for the transmission and/or receiving of one or more signals in the 900MHz frequency band and antenna 8 is for the transmission and/ or receiving of one or more signals in the 1800MHz frequency band and the 2100MHz frequency band. Two BTSs 10, 12 are provided at the base of the mast 4 for transmitting one or more radio frequency signals from a mobile phone unit to the antennae 6, 8. More particularly, BTS 10 transmits and/or receives one or more radio frequency signals in the 1800MHz frequency band, and BTS 12 transmits and/or receives one or more radio frequency signals at the 900MHz frequency band. A combiner 14 is provided at the base of the mast and is connected to BTS 10, 12 for combining radio frequency signals from the two BTS 10, 12 and passing the signals up the mast along a coaxial cable 16, and for splitting signals passing down the mast from the antennae 6, 8 to the appropriate BTS 10, 12.

A remote radio unit 20 is provided at the top of the mast 4 for receiving and/or transmitting one or more radio frequency signals in the 2100MHz frequency band. Multiplexing apparatus 102 according to the present invention is also provided at the top of the mast 4 and is connected at one end to the remote radio unit 20 and the combiner/ splitter 14 via coaxial cables 24 and 16 respectively, and is connected at the other end to the antennae 8, 6 via coaxial cables 28, 104.

Figure 3 is an example of a circuit diagram of the multiplexing apparatus 102 in one embodiment. The apparatus 102 includes a housing 106 having a first input port 110 for connection to remote radio unit 20 and a second input port 108 for connection to combiner/ splitter 14 at a first end 112 thereof. Housing 106 also has a first output port 116 for connection to antenna 8 and a second output port 114 for connection to antenna 6 at a second end 118 thereof.

Three filters 120, 122, 124 are provided in the apparatus for connection between the input ports and the output ports. Each filter 120, 122, 124 allows the passage of one or more radio frequency signals of the 900MHz frequency band, the 1800MHz frequency band, and the 2100MHz frequency band respectively, but prevents, or substantially prevents, the passage of any other frequency therethrough in use. Although the frequency bands of 900MHz, 1800MHz, and 2100MHz are used in this example, it will be appreciated that any or any combination of frequency, set of frequencies or frequency bands could be used in this invention.

Filter 120 is connected between input port 108 and output port 114. Filter 122 is connected between input port 108 and output port 116. Filter 124 is connected between input port 110 and output port 116.

Filter 120 is provided in a first RF pathway 126, filter 122 is provided in a second RF pathway 128 and filter 124 is provided in a third RF pathway 130. Filter 120 and filter 122 and their respective pathways 126, 128 are multiplexed together to form a common pathway 132 for connection to input port 108. Filter 122 and filter 124 and their respective pathways 128, 130 are multiplexed together to form a common pathway 134 for connection to output port 116. RF pathway 126 is connected to output port 114 and RF pathway 130 is connected to input port 110.

Thus, in this embodiment, two of the filters are each multiplexed to one other filter at one end thereof, and one of the filters is multiplexed to a first filter at one end and to a second filter at a second end.

Figure 4 is a circuit diagram of an alternative embodiment of the multiplexing apparatus 202 according to the present invention. In this arrangement the apparatus 202 is able to operate over four different radio frequency bands.

The apparatus 202 includes a housing 206 having a first input port 208, and a second input port 210 at a first end 212 thereof. Housing 206 also has a first output port 214 for connection to a first antenna, a second output port 216 for connection to a second antenna, and a third output port 217 for connection to a further antenna, at a second end 218 thereof.

Four filters 220, 222, 224, 225 are provided in the apparatus for connection between the input ports and the output ports. Each filter 220, 222, 224, 225 allows the passage of one or more radio frequency signals of four different frequency bands (i.e. one frequency band per filter), but prevents, or substantially prevents, the passage of any other frequency therethrough in use. It will be noted that more than one filter can be provided for each different frequency band if required.

Filter 220 is connected between input port 208 and output port 214. Filter 222 is connected between input port 210 and output port 214. Filter 224 is connected between input port 210 and output port 216. Filter 225 is connected between input port 210 and output port 217.

Filter 220 is provided in a first RF pathway 226, filter 222 is provided in a second RF pathway 228, filter 224 is provided in a third RF pathway 230, and filter 225 is provided in a fourth RF pathway 231. Filter 220 and filter 222 and their respective pathways 226, 228 are multiplexed together to form a common pathway 232 for connection to output port 214. Filters 222, 224, 225 and their respective pathways 228, 230, 231 are multiplexed together to form a common pathway 234 for connection to input port 210.

RF pathway 226 is connected to input port 208, RF pathway 230 is connected to output port 216, and RF pathway 231 is connected to output port 217.

Thus, in this illustrated embodiment, three of the filters are multiplexed to each other at one end thereof, one of the filters is multiplexed to a first filter at a first end and a second filter at a second end, and one of the filters is multiplexed to one other filter at one end thereof.

Figure 5 is a circuit diagram of a yet further alternative embodiment of the multiplexing apparatus 302 according to the present invention. In this arrangement, the apparatus 302 is based on the apparatus of figure 3 and the same reference numerals have been used accordingly. However, direct current (DC) and antenna interface standards group (AISG) bypass paths have also been provided for routing DC and AISG through the apparatus.

DC blocks in the form of capacitors 304, 304', 304", 304'" are provided in RF pathway 126, common RF pathway 132, RF pathway 130 and common RF pathway 134 so as to prevent DC from passing through one or more of the filters in use. A control unit 136 is provided for connection between the input and output ports 108, 114, 110, 116. Thus, control unit 136 is connected via path 138 to RF pathway 126 between the output port 114 and DC block 304, via path 140 to RF pathway 130 between input port 110 and DC block 304", via path 142 to common RF pathway 134 between output port 116 and DC block 304"', and via path 144 to common RF pathway 132 between input port 108 and DC block 304'.

The control unit 136 is arranged to detect the presence of DC voltage on the input ports and to detect if the output ports are connected to a DC short circuit.

All the DC/AISG bypass paths are connected internally to the control unit within the apparatus.

The DC/AISG bypass paths can be arranged and/or the control unit can be controlled so as to make the apparatus factory and/or operator configurable for DC and AISG.

The control unit can be used to follow different rules to allow different input ports to be connected to different output ports via the DC/AISG bypass paths. For example:

Example 1— If the control unit detects DC on an input port, it can connect this input port to all output ports not having DC short circuit detected. If more than one input port is detected as having DC, the control unit refers to an internal preference table stored in or associated with the control unit to determine which input port it takes DC from.

Example 2— The DC/AISG connections can be the same as the RF signal flow. Thus, in this example, two input ports having DC could be connected to one output port. The control unit refers to an internal preference table stored in or associated with the control unit to determine which of the two input ports will be enabled for DC. Example 3— An internal modem could be provided for communication with the control unit and set which RF paths are enabled or disabled for DC. Alternatively, external switches could be used to allow the control unit to configure which RF paths are enabled or disabled for DC.

Claims

1. Multiplexing apparatus, said multiplexing apparatus including at least two input ports and at least two output ports, at least three filter means are provided in the apparatus and are operable over at least three different radio frequencies or frequency bands, each filter means is connected to an input port and an output port, and wherein each of said filter means is multiplexed to at least one other of said filter means at at least one end thereof, and at least a first of said filter means is multiplexed at a first end to a second of said filter means, and the first filter means is multiplexed at a second end to a third of said filter means, the first, second and third filter means being different.

2. Multiplexing apparatus according to claim 1 wherein each, or at least one, filter means is provided in or associated with a radio frequency (RF) pathway within the apparatus, the RF pathway for the transmission and/ or receiving of one or more RF signals.

3. Multiplexing apparatus according to claim 2 wherein the apparatus includes at least three RF pathways within the apparatus.

4. Multiplexing apparatus according to claim 2 wherein at least one RF pathway is connected between an input port and an output port for transmitting one or more RF signals therebetween in use.

5. Multiplexing apparatus according to claim 2 wherein a plurality of RF pathways are provided in the apparatus, and at least one of the RF pathways is multiplexed to at least one other RF pathway.

6. Multiplexing apparatus according to claim 5 wherein at least one RF pathway is multiplexed at a first end to a first, or at least first, RF pathway, and is multiplexed at a second end to a second, or at least a second, RF pathway.

7. Multiplexing apparatus according to any preceding claim wherein at least two of the RF pathways are multiplexed together to form a common pathway for connection to one of the input ports, and at least two of the RF pathways are multiplexed together to form a common pathway for connection to one of the output ports.

8. Multiplexing apparatus according to claim 2 wherein a single filter means is provided in each of the RF pathways in the apparatus.

9. Multiplexing apparatus according to claim 2 wherein two or more filter means are provided in each of the RF pathways in the apparatus.

10. Multiplexing apparatus according to claim 1 wherein one of said filter means allows the passage of one or more RF signals of a single set of radio frequencies or a single radio frequency band only and prevents, or substantially prevents, the passage of one or more RF signals of any other radio frequency band therethrough.

11. Multiplexing apparatus according to claim 1 wherein one of said filter means allows the passage of one or more RF signals of two or more sets of radio frequencies or two or more radio frequency bands, and prevents, or substantially prevents, the passage of one or more RF signals from any other RF frequency band therethrough.

12. Multiplexing apparatus according to claim 1 wherein the filter means includes any or any combination of a low pass filter, a high pass filter, a band pass filter or a band stop filter.

13. Multiplexing apparatus according to claim 1 wherein one or more direct current (DC) and/or control signal bypass paths are provided for the transmission and/or receiving of DC power and/or one or more control signals therealong in use.

14. Multiplexing apparatus according to claim 13 wherein the one or more control signals are in the form of antenna interface standards group (AISG) signals.

15. Multiplexing apparatus according to claim 13 wherein the one or more DC and/or control signal bypass paths include one or more DC blocks to prevent the passage of DC and/or control signals through one or more, or all, of the filter means in use.

16. Multiplexing apparatus according to claim 15 wherein the one or more DC blocks are in the form of, or include, one or more capacitors.

17. Multiplexing apparatus according to claim 15 wherein a DC block is connected to each end or either end of the filter means.

18. Multiplexing apparatus according to claim 13 wherein control means are provided in the apparatus in or associated with the one or more DC and/or control signal bypass paths, said control means arranged so as to detect the presence of DC voltage on one or more of the input ports and/or to detect DC short circuit on one or more of the output ports.

19. Multiplexing apparatus according to claim 18 wherein the control means detects and/or measures one or more electrical values at or associated with any of the input ports and/ or output ports.

20. Multiplexing apparatus according to claim 19 wherein the control means is arranged to control whether any of the one or more bypass paths are enabled and/or disabled for DC according to one or more electrical values detected and/ or measured at one or more of the ports.

21. Multiplexing apparatus according to any preceding claim wherein at least one, or all, the DC and/or control signal bypass paths are connected to the control means internally of the apparatus or within the apparatus.

22. Multiplexing apparatus according to any preceding claim wherein the control means can be arranged to follow different rules to allow different input ports to be connected to different output ports via the DC and/or control signal paths.

23. Multiplexing apparatus according to claim 13 wherein one or more electrical switches and/or modems are provided in or associated with the one or more DC and/or control signal bypass paths to allow the bypass paths to be moved between enabled and/ or disabled conditions for DC.

24. Multiplexing apparatus according to claim 23 wherein the one or more electrical switches are one or more external electrical switches that are external to a housing body of the apparatus.

25. A method of using multiplexing apparatus, said multiplexing apparatus including at least two input ports and at least two output ports, and at least three filter means operable over at least three different radio frequencies or frequency bands, wherein said method includes the step of connecting each filter means to an input port and an output port, multiplexing each of said filter means to at least one other of said filter means at at least one end thereof, multiplexing at least a first of said filter means at a first end to a second of said filter means, multiplexing the first filter means at a second end to a third of said filter means, the first, second and third filter means being different.