WO1999026357A1

WO1999026357A1 - Improvements to above-ground telecommunications systems and methods of designing same

Info

Publication number: WO1999026357A1
Application number: PCT/US1997/021047
Authority: WO
Inventors: James C. Wren
Original assignee: Wren James C
Priority date: 1997-11-19
Filing date: 1997-11-19
Publication date: 1999-05-27
Also published as: WO1999026357A8; AU3586199A

Abstract

Improvements to above-ground telecommunications systems, and methods of designing same, primarily comprising coupling a telecommunications system bridge station at the edge of a null zone to leaky cable running in or through said null zone, together with a bi-directional amplifier and uplink and downlink filters, for extending telecommunications coverage into said null zone.

Description

IMPROVEMENTS TO ABOVE-GROUND TELECOMMUNICATIONS SYSTEMS AND METHODS OF DESIGNING SAME

BACKGROUND OF THE INVENTION

The present invention generally relates to above-ground telecommunications systems other than analog frequency-modulation systems. More specifically, the present invention relates to a novel and improved subsystem using coaxial cable as an antenna transmitting, receiving and transporting radio frequency signals in areas having materially less coverage than the surrounding

area.

A variety of telecommunications systems have been developed subsequent to the first system transmitting telephone signals through transmission wire. Such newer "wireless" systems include analog frequency-modulated technology, code division multiple access modulation

technology ("CDMA") and personal communication services technology ("PCS"). The present invention relates to some of those newer systems, and more specifically, to systems using

technology other than analog frequency modulation; this application relates primarily to telecommunications systems using digital technology, such as CDMA and PCS (referred to herein collectively as "digital systems").

Wireless telecommunications systems essentially include one or more antennae for receiving and transmitting radio frequency ("RF") signals of particular frequencies, a central

office for identifying and routing incoming and outgoing data and RF transmissions to proper

destinations, and transceivers for customers to use in transmitting and receiving telephone signals.

The central office has electronic equipment acting as a switch room; it interfaces with equipment in the centralized base station controller ("CBSC"), which interconnects with cell sites containing said antennae. Each cell site typically has a transceiver station (sometimes referred to as a base

transceiver station or a "BTS"), which contains equipment transmitting RF signals through cable to an antennae network usually situated atop a tower or on a promontory. The antennae often transmits RF in an omnidirectional pattern, in all directions; alternatively transmissions may be restricted to a desired sector, to enable the analog telecommunications system to reuse a particular frequency in a particular area, to provide services to more customers. Said customer transceivers are usually remote telecommunication devices such as mobile telephones (car phones) and portable telephones (cell phones), collectively referred to herein as "mobile units."

A passive antenna is essentially a metal rod designed to, upon receiving RF transmission signals, vibrate at frequencies corresponding to the received signal for further transport. A cable may be used to transport the signal received by a passive antenna. Rf signals may also be transported along fiber optic cable; alternatively, RF signals may be transported from one particular point to another using microwave RF signals.

The coverage area of a particular system is expanded by the construction of a plurality of cell sites (sometimes referred to simply as "cells"). The telecommunications coverage area for each such cell can generally be visualized as horizontally circular or disc-like in shape, emanating outwardly from the cell site in the center. In flat unobstructed terrain, the strength of the RF signals emanating from the cell decreases the further the receiver is away from the BTS. Often,

the total desired coverage area greatly exceeds the coverage of a single cell, making it necessary to couple and coordinate a plurality of cells to establish and serve the total coverage area.

In the past, telecommunications engineers have essentially designed such wireless systems by situating cell sites on promontories and other key sites, so that each cell's coverage area essentially overlaps other adjacent coverage areas until, ideally, there is coverage in all zones of the total desired coverage area. However, despite the efforts to provide complete coverage everywhere within the coverage area, many coverage areas have zones wherein RF signals are very weak or nonexistent. Such zones are generally known as nulls or holes in RF coverage areas. Such null zones commonly include tunnels, subways, and the interiors of large buildings and ships. In general, nulls typically result when the transport, transmission or receipt of RF signals are blocked, shielded or deflected by features of the surrounding terrain such as mountains or dense foliage, or tall buildings.

Ideally, a particular RF signal arrives at an analog system transceiver from only one source. By contrast, in digital systems, a signal arrives at a transceiver from several sources in different directions, each signal often having a different transmission delay than the others. An analog receiver's reception of RF signals having the same freqency, from multiple sources or pathways, results in a problem known as multipath fading, wherein the multiple incoming signals essentially cancel or distorts each other. As a result, the integrity or deciferability of the RF signal is decreased or destroyed. Multipath fading is a significant consideration in planning an analog telecommunicatios system..

One of the primary benefits of digital technology is the increase in the capacity of the

telecommunications system to simultaneously serve many customers. This technology allows

many RF signals to be simultaneously transmitted and received along a wide spectrum of wavelength frequencies. This is done by assigning a digital Walsh sequence and code to each user.

Therefore, when all users are transmitting at the same frequency, their audio signals will not be destroyed because each is digitally encoded into the frequency or channel that is being used. Primarily because of such digital encoding and decoding of the signal's audio intelligence on a wide band frequency, digital systems often experience cumulative signal gain (rather that fading or destruction) attributable to multipath transmissions. One reason is the ability of digital systems to accomplish a "soft handoff," which is the ability to pass a signal from one cell site to another without any break or interruption of the transmission. Multipath reception does not cause multipath fading in digital systems

Since digital systems use technology that is essentially an outgrowth of the analog technology, the same engineering concepts have been used to design digital systems. Engineers

designing digital systems typically conduct the same studies used in designing analog systems, to determine the proper positioning of cell sites and to assure that cell coverage areas overlap to ideally serve the total desired coverage area.

Providing coverage within areas such as tunnels, subways and buildings poses a different problem for both analog and digital systems, due primarily to the relative insulation of such areas from RF signals transmitted in conventional ways by airwaves. Telecommunications reception within such underground and inside subsystems has been accomplished using several methods in the past, including coupling separate cell sites or repeater stations near or within the boundaries of the insulated area, to provide coverage therein. However, such conventional techniques are relatively expensive and limited in value, since the insulated area is often relatively small and inadequately served by the circular or pie-shaped coverage areas of cell sites and repeater stations.

Recently, coverage has been extended to discrete uncovered zones in underground or above-ground inside subsystems by coupling to such peripheral cell sites or repeater stations special coaxial cable running through the null zone; such cables, known as radiating or "leaky" cables, have slits through the outer sheilding layer, permitting RF signals to emanate outwardly into the surrounding environment. Such cables can also be constructed to act as passive antennas, absorbing selected RF signals transmitted from sources in relatively close proximity Leaky cables have previously not been used to extend coverage into above-ground outdoor null zones though, primarily because system designers have deployed only towers (with conventional antennae) coupled to the donor cell site closest to the null zone. Designers of above- ground outdoor digital systems are still operating under the constraints of the analog systems, especially concerning multipath fading and the designing of coverage networks using cell sites and towers.

Besides Catalog No. 37 published by Andrew Company, Inc. In 1997 (see pages 674 and 675), below is a list of patents that are arguably related to this application: Patent Number Inventor Issue Date

5,602,834 Dean et al. February 11, 1997

5,513, 176 Dean et al. April 30, 1996

5,280,472 Gilhousen et al. January 18, 1994

5,278,989 Burke et al. January 11, 1994

Patent No. 5,602,834 issued to Dean et al (hereinafter the '834 patent) describes a linear coverage area antennae system for a CDMA telecommunications system; said antennae system is essentially a parallel pair of leaky cables. Claim 1 of the '834 patent claims a base

station using digitally modulated telecommunications signals, said base station having an antennae system comprising the parallel pair of antennae coupled to said base station and having a means of splitting a communications signal for transmission by both antennae.

However, that patent focuses upon underground and indoor environments, which are virtually insulated from competing RF signals and the corresponding multipath fading problems.

Moreover, unlike the present invention, that patent depends heavily upon a plurality of base stations directly coupled to said leaky cable. Andrew Corporation, one of the largest providers of leaky cables, promotes leaky cables for underground and indoor communications systems; see Andrew Corporation, catalog number 37, page 675 (1997). By contrast, for above-ground outdoor systems, Andrew Corporation promotes panel antennae rather than leaky cables. (Supra at page 674.)

SUMMARY OF THE INVENTION

In general, this application pertains to improvements to above-ground outdoor components or subsystems of telecommunications systems, and methods of designing same. Such improvements include, for example, using leaky cable to transmit, receive and transport RF signals through a zone having materially less RF reception than the surrounding area. Another improvement described in this application includes providing a subsystem, and a system design, not requiring a plurality of expensive cell sites. The invention disclosed herein also improves telecommunications systems by, among other things, providing a design useable

by a multiplicity of telecommunications providers without a corresponding duplicity of cell sites or expensive equipment. Accordingly, one primary object of the present invention is to provide a method of eliminating or reducing null zones in RF coverage in telecommunications systems other than in analog frequency-modulated systems. Another object is to provide a subsystem that is relatively easy and inexpensive to install and maintain. It is yet another

object to provide a subsystem that is capable of use by a plurality of telecommunications providers. Other objectives of this application will be apparent to those skilled in the art, after a review of this application. DESCRIPTION OF THE DRAWINGS

Figure 1 depicts schematic diagrams of three alternative embodiments of an above- ground subsystem coupled to an existing system (donor cell site), having a bridge station member (such as: (a) a passive antenna, (b) a microwave transceiver, or (c) fiber optic cable) coupled to leaky cable, which may transmit to and receive from a mobile unit (such as a car phone transceiver, not shown).

Figure 2 depicts schematic diagrams of three other alternative embodiments of an above-ground subsystem coupled to an existing system (donor cell site), having essentially the same elements as the systems depicted in Figure 1 plus additional coupling of a bi-directional amplifier, and uplink and downlink filters.

Figure 3 depicts a schematic diagram of another embodiment of an above-ground subsystem having essentially the same elements as the system depicted in Figure 1, including couplings of multiple bridge stations to multiple donor cell sites. This Figure may depict a multipath subsystem, where more than one donor cell site transmits the same provider's signal.

Figure 4 depicts a schematic diagram of another embodiment of an above-ground

subsystem having essentially the same elements as the system depicted in Figure 3, and further including couplings of a bi-directional amplifier and uplink and downlink filters. This Figure may depict a co-location subsystem, where there are a plurality of different telecommunications providers transmitting from one or more of the donor cell sites.

DETAILED DESCRIPTION OF THE INVENTION

For the sake of simplicity and to give the claims of this patent application the broadest interpretation and construction possible, the following definitions will apply:

(a) "analog" means, depending upon the context of use, the relatively narrow spectrum of wavelengths used for telecommunications systems employing frequency modulation, or a frequency or channel assigned to a user or mobile unit;_.it does not include the spectrum of wavelengths used for telecommunications systems such as digital systems using CDMA or PCS technology.

(b) "cell site" or "cell" means a cell site, microcell or other site functioning to transmit and receive RF signals between a mobile unit and a central office.

(c) "central office" means the coordination site of a telecommunications system interfacing with incoming and outgoing data and RF signal sources and providing switching for the identification or a MTN (mobile identificatin

number) and an ESN (electronic serial number), routing of telephone numbers and RF signals to the appropriate destinations.

(d) "leaky cable" means insulated (usually sheilded coaxial) cable having slits through its insulation enabling signals transported along its length to emanate out into the immediately surrounding environment; also known as radiating cable.

(e) "couple" means to functionally connect; for a subsystem, coupling a leaky cable may mean to physically attach it to a bridge station member in a manner to

assure the continuity of electrical conductivity, whereas some couplings (such as a system-to-subsystem coupling between a donor cell site's microwave transceiver and a bridge station's microwave transceiver) will not necessarily involve physical connection between the system and the bridge station.

(f) "filter" means an apparatus to separate or remove from further transmission RF signals having certain characteristics; some known filters separate or remove analog frequency-modulated signals. Another filter will be capable of, either separately or in combination with the aforementioned apparatus, separating or removing RF signals within a designated band, or otherwise

transmitted by certain designated telecommunications providers.

(g) "downlink" pertains to signals passing from a member of a telecommunications

system network "down" to a peripheral apparatus such as a mobile unit.

(h) "uplink" pertains to signals passing from a peripheral apparatus such as a mobile unit "up" to a member of a telecommunications system network through such things as an antenna, microwave transceiver or optic cable.

(i) "amplifier" means an apparatus that amplifies an RF signal traveling either uplink or downlink, for retransmission or further transport; some amplifiers are bi-directional, amplifying both uplink and downlink signals. An amplifier may include filtering apparatus and/or other apparatus for controlling the power or characteristics of signals passing through the amp.

(j) "above-ground" means not in a subterranean tunnel, subway or similar location insulated from outdoor telecommunications systems; however, it does not mean merely physically above the ground (such as suspended on telephone poles). It may mean lying physically on the ground, or slightly covered by ground an insufficient amount to substantially hinder reception, transmission or transport of RF signals, (k) "CBSC" means a centralized base station controller; this interconnects all cell sites to the central office and its switch, synchronizing the transmissions and coordinating them for routing. (1) "bridge station" means any member(s) selected from the group consisting of passive antennas, microwave transceivers, cable (copper, coaxial, fiber optic cable or other means of transporting audio or data communications) and combinations thereof, situated at the periphery of (or within) one or more null zones and coupled between one or more donor cell sites and one or more leaky cables. Also for the sake of simplicity, the conjunctive "and" may also be taken to include the disjunctive "or," and vice versa, whenever necessary to give the claims of this patent application the broadest interpretation and construction possible. Likewise, when the plural form is used, it may be taken to include the singular form, and vice versa.

Similarly, when situational requirements may be satisfied by, for instance, coupling "at least one" of something to another item (or vice versa), subsequent discussion may be in terms of only a 1-on-l coupling, rather than multiple 1-on-l couplings (or rather than plurality-on-1 coupling), describing each of the possible separate couplings; such discussion of only a 1-on-l coupling will not undermine the intention to give the claims of this patent application the broadest interpretation and construction possible. By the same token, when a "plurality" of items may be coupled to a "plurality" of other items, all combinations and permutations of permissible couplings are included.

Operating in conjunction with the invented method and related subsystem, the telecommunications system includes a central office coupled with a CBSC, which in turn is downlinked to several cell sites (A,B and C for example, as in Figure 1), each of which transmits RF signals for possible reception by a mobile unit within the respective coverage area. Each cell of the system may link to the subsystem's one or more bridge stations having passive antennae, microwave transceivers and/or cables to extend its coverage to the edge of one or more null zones. Each such bridge station is coupled to one or more leaky cables running into or through one or more of such null zones, especially along well travelled pathways such as roadways. A stream of systemic digital data signaling is transmitted through the central office via the CBSC and downlinked to said cell sites; in turn, RF signal is downlinked from the BTS/antennae to said bridge stations. Such bridge stations transport and transmit said RF signal down leaky cable, which allows the signal to emanate outwardly for reception by a mobile unit within sufficient proximity of such leaky cable. Signals transmitted by such mobile units travel the same paths, but in the opposite direction.

Generally, the invention comprises a method of reducing limitations in above-ground radio frequency coverage in telecommunications systems other than analog frequency- modulated systems. Said method generally comprises the steps of coupling at least one end of at least one leaky cable to at least one member of the group of bridge station members consisting of passive antennas, microwave transceivers, cables and combinations thereof, said member(s) already being coupled to at least one donor site of at least one operable RF telecommunications system. One of the important characteristics common to each of said members in said group, supporting the inclusion of each member in said group, is that each member in its own way causes the transmission, reception or transport of RF signal. Another common characteristic is that each handles the waveforms so as not to destroy or adversely affect the original characteristics of the waveforms. Said leaky cable transports and transmits downlink signals to at least one transceiver; said leaky cable also receives, transports and transmits uplink signals from at least one transceiver to said telecommunications system donor site(s).

In another version of this method, said coupling occurs separately on a plurality of said leaky cable ends. In yet another version of this method, said coupling also occurs separately on said leaky cable(s) other than at said end(s).

Ideally, the subsystem is comprised of the bridge station(s) and leaky cable(s). The subsystem may also include an amplifier for boosting the signal strength downlinking from the central office CBSC to the BTS, or uplinking from the mobile units. The subsystem may also include additional amplifiers situated at various sites along leaky cable, since the signal strength diminishes as it propogates along (and leaks out of) said leaky cable. Optionally, the subsystem may also include one or more additonal passive antennas, microwave transceivers, cables and combinations thereof, situated a intermediate points along said leaky cable. One or more of said intermediate stations may receive and transmit signals from a different cell site than the others. This arrangement will facilitate the transfer or "handing off' of a signal between different cell sites having different respective coverage areas.

Ideally, the subsystem will also include filtering apparatus for filtering downlink signals and uplink signals. Such filtering may remove or separate all analog signals from the transmission, thereby controlling the frequency being transported or retransmitted; besides eliminating interference, such filtering also facilitates the co-location of different telecommunications providers on the same equipment. In facilitating co-location of different telecommunications providers, it becomes possible for the same infrastructure or equipment to be used to provide a variety of telecommunications providers with coverage in the same null zone.

Accordingly, other optional embodiments of any of the versions set forth herein further comprise coupling to said leaky cable(s) or to said bridge station member(s) at least one member of the group of modifier members consisting of amplifiers, filters and combinations thereof, at a position to optimize the functioning of said modifier member. One of the important characteristics common to each of said members in said group, supporting the inclusion of each member in said group, is that each member in its own way modifies or affects the RF signal as it passes through the subsystem, in such a manner so as to not to destroy the characteristic of the waveform. It is often advantageous to amplify and/or filter signals essentially as soon as they are received from the donor cell site(s); amplifiers and/or filters may essentially be part of the bridge station complex, being inserted into the pathway at the point where said base station member couples to cabling transporting the signals through the subsystem. It may also be advantageous to amplify and/or filter signals at "down system" points along the leaky cable.

The invention also comprises a method described herinabove wherein said leaky cable is coupled with a plurality of said bridge station members, receiving signals from a plurality of different donor sites. This feature, accompanied by appropriate filtering, facilitates the aforementioned co-location.

The methods disclosed herein may likewise be applied to reduce or eliminate limitations in above-ground outdoors radio frequency coverage in telecommunications systems other than analog frequency-modulated systems.

In one detailed embodiment of a method of reducing limitations in above-ground radio frequency coverage in designated operable RF telecommunications systems other than analog frequency-modulated systems, said method comprises the steps of: (a) separately coupling, to at least one donor site each of a plurality of designated telecommunications systems, at least one member selected from the group of bridge station members consisting of passive antennas, microwave transceivers, cables and combinations thereof; (b) coupling said bridge station member(s) to at least one leaky cable extending in a null zone; and (c) downsystem from said bridge station member(s), coupling at least one member of the the group of modifier members consisting of downlink filters, bi-directional amplifiers, uplink filters and combinations thereof. Said downlink filters are for separating from retransmission analog frequency-modulated downlink signals and allowing retranmission of only the downlink signals of designated telecommunications systems; said bi-directional amplifiers are for amplifying and retransmitting said signals, while said uplink filters function by separating from retransmission analog frequency-modulated uplink signals and allowing retranmission of only the uplink signals of designated telecommunications systems. Said leaky cable(s) are for transporting and transmitting downlink signals of designated telecommunications systems to at least one transceiver; said leaky cable(s) also function by receiving, transporting and transmitting uplink signals from at least one transceiver to the donor site(s) of respective designated telecommunications systems.

The invention disclosed herein also includes a subsystem of components for reducing limitations in above-ground radio frequency coverage in telecommunications systems other than analog frequency-modulated systems. Said subsystem generally comprises coupling at least one end of at least one leaky cable to at least one member of said group of bridge station members.

The options and alternative versions specified hereinabove for the invented method apply equally to the various embodiments of the invented subsystem.

It should also be noted that the types of above-ground applications of this invention are essentially infinite, limited only by the number of different null zones. Although the figures primarily depict applications along a roadway within a null zone, the repertoire of possible applications is not so limited. The invention may be applied in many different situations to establish or improve telecommunications coverage in any location.

Those skilled in the art who have the benefit of this disclosure will appreciate that it may be used as the creative basis for designing devices or methods similar to those disclosed herein, or to design improvements to the invention disclosed herein; such new or improved creations should be recognized as dependent upon the invention disclosed herein, to the extent of such reliance upon this disclosure.

Claims

I claim:

1. A method of reducing limitations in above-ground radio frequency coverage in telecommunications systems other than analog frequency-modulated systems, said method comprising the steps of coupling at least one end of at least one leaky cable to at least one member of the group of bridge station members consisting of passive antennas, microwave transceivers, cables and combinations thereof.

2. A method described in claim 1 wherein said coupling occurs separately on a plurality of said leaky cable ends.

3. A method described in claim 1 wherein said coupling also occurs separately on said leaky cable other than at said end.

4. A method described in claim 1 further comprising coupling to said leaky cable or to said bridge station member at least one member of the group of modifier members consisting of amplifiers, filters and combinations thereof, at a position to optimize the functioning of said modifier member.

5. A method described in claim 2 further comprising coupling to said leaky cable or to said bridge station member at least one member of the group of modifier members consisting of amplifiers, filters and combinations thereof, at a position to optimize the functioning of said modifier member.

6. A method described in claim 3 further comprising coupling to said leaky cable or to said bridge station member at least one member of the group of modifier members consisting of amplifiers, filters and combinations thereof, at a position to optimize the functioning of said modifier member.

7. A method described in claim 1 wherein said leaky cable is coupled with a plurality of said bridge station members, receiving signals from a plurality of different donor sites.

8. A method of reducing limitations in above-ground radio frequency coverage in designated operable RF telecommunications systems other than analog frequency-modulated systems, said method comprising the steps of:

(a) separately coupling, to at least one donor site each of a plurality of designated telecommunications systems, at least one member selected from the group of bridge station members consisting of passive antennas, microwave transceivers, cables and combinations thereof;

(b) coupling said bridge station member to at least one leaky cable extending in a null zone,

(c) downsystem from said bridge station member, coupling at least one member of the group of modifier members consisting of downlink filters, bi-directional amplifiers, uplink filters and combinations thereof, for separating from retransmission analog frequency- modulated downlink signals and allowing retranmission of only the downlink signals of designated telecommunications systems, for amplifying and retransmitting said signals, and for separating from retransmission analog frequency-modulated uplink signals and allowing retranmission of only the uplink signals of designated telecommunications systems.

9. A method of reducing limitations in above-ground outdoor radio frequency coverage in telecommunications systems other than analog frequency-modulated systems, said method comprising the steps of coupling at least one end of at least one leaky cable to at least one member of the group of bridge station members consisting of passive antennas, microwave transceivers, cables and combinations thereof.

10. A method described in claim 9 wherein said coupling occurs separately on a plurality of said leaky cable ends.

11. A method described in claim 9 wherein said coupling also occurs separately on said leaky cable other than at said end.

12. A method described in claim 9 further comprising coupling to said leaky cable or to said bridge station member at least one member of the group of modifier members consisting of amplifiers, filters and combinations thereof, at a position to optimize the functioning of said modifier member.

13. A method described in claim 10 further comprising coupling to said leaky cable or to said bridge station member at least one member of the group of modifier members consisting of amplifiers, filters and combinations thereof, at a position to optimize the functioning of said modifier member.

14. A method described in claim 11 further comprising coupling to said leaky cable or to said bridge station member at least one member of the group of modifier members consisting of amplifiers, filters and combinations thereof, at a position to optimize the functioning of said modifier member.

15. A method described in claim 9 wherein said leaky cable is coupled with a plurality of said bridge station members, receiving signals from a plurality of different donor sites.

16. A method of reducing limitations in above-ground outdoor radio frequency coverage in designated operable RF telecommunications systems other than analog frequency- modulated systems, said method comprising the steps of:

(b) coupling said bridge station member to at least one leaky cable extending in a null zone;

(c) downsystem from said bridge station member, coupling at least one member of the the group of modifier members consisting of downlink filters, bi-directional amplifiers, uplink filters and combinations thereof, for separating from retransmission analog frequency- modulated downlink signals and allowing retranmission of only the downlink signals of designated telecommunications systems, for amplifying and retransmitting said signals, and for separating from retransmission analog frequency-modulated uplink signals and allowing retranmission of only the uplink signals of designated telecommunications systems.

17. A subsystem for reducing limitations in above-ground radio frequency coverage in telecommunications systems other than analog frequency-modulated systems, said subsystem comprising coupling at least one end of at least one leaky cable to at least one member of the group of bridge station members consisting of passive antennas, microwave transceivers, cables and combinations thereof.

18. A subsystem described in claim 17 wherein said coupling occurs separately on a plurality of said leaky cable ends.

19. A subsystem described in claim 17 wherein said coupling also occurs separately on said leaky cable other than at said end(s).

20. A subsystem described in claim 17 further comprising coupling to said leaky cable or to said bridge station member at least one member of the group of modifier members consisting of amplifiers, filters and combinations thereof, at a position to optimize the functioning of said modifier member.

21. A subsystem described in claim 18 further comprising coupling to said leaky cable or to said bridge station member at least one member of the group of modifier members consisting of amplifiers, filters and combinations thereof, at a position to optimize the functioning of said modifier member.

22. A subsystem described in claim 19 further comprising coupling to said leaky cable or to said bridge station member at least one member of the group of modifier members consisting of amplifiers, filters and combinations thereof, at a position to optimize the functioning of said modifier member.

23. A method described in claim 17 wherein said leaky cable is coupled with a plurality of said bridge station members, receiving signals from a plurality of different donor sites.

24. A subsystem of reducing limitations in above-ground radio frequency coverage in telecommunications systems other than analog frequency-modulated systems, said subsystem comprising:

(a) at least one member selected from the group consisting of passive antennas, microwave transceivers, cables and combinations thereof (said member(s) already being coupled to an operable RF telecommunications system) separately coupled to a downlink filter;

(b) said downlink filter separately coupled to a bidirectional amplifier;

(c) said amplifier separately coupled to an uplink filter; and

(d) said uplink filter separately coupled to at least one end of a leaky cable.

25. A subsystem for reducing limitations in above-ground outdoor radio frequency coverage in telecommunications systems other than analog frequency-modulated systems, said subsystem comprising coupling at least one end of at least one leaky cable to at least one member of the group of bridge station members consisting of passive antennas, microwave transceivers, cables and combinations thereof.

26. A subsystem described in claim 25 wherein said coupling occurs separately on a plurality of said leaky cable ends.

27. A subsystem described in claim 25 wherein said coupling also occurs separately on said leaky cable other than at said end(s).

28. A subsystem described in claim 25 further comprising coupling to said leaky cable or to said bridge station member at least one member of the group of modifier members consisting of amplifiers, filters and combinations thereof, at a position to optimize the functioning of said modifier member.

29. A subsystem described in claim 26 further comprising coupling to said leaky cable or to said bridge station member at least one member of the group of modifier members consisting of amplifiers, filters and combinations thereof, at a position to optimize the functioning of said modifier member.

30. A subsystem described in claim 27 further comprising coupling to said leaky cable or to said bridge station member at least one member of the group of modifier members consisting of amplifiers, filters and combinations thereof, at a position to optimize the functioning of said modifier member.

31. A method described in claim 25 wherein said leaky cable is coupled with a plurality of said bridge station members, receiving signals from a plurality of different donor sites.

32. A subsystem for reducing limitations in above-ground outdoor radio frequency coverage in designated operable RF telecommunications systems other than analog frequency- modulated systems, said subsystem comprising:

(a) coupling leaky cable extending in a null zone to at least one member selected from the group of bridge station members consisting of passive antennas, microwave transceivers, cables and combinations thereof (said bridge station member already being coupled to at least one donor site each of a plurality of designated telecommunications systems);

(b) coupling to said leaky cable or to said bridge station member at least one downlink filter for separating from retransmission analog frequency-modulated signals and allowing retranmission of only the downlink signals of designated telecommunications systems;

(c) coupling to (or down cable of) said downlink filter at least one bi-directional amplifier; and

(d) coupling to (or down cable of) said amplifier at least one uplink filter for separating from retransmission analog frequency-modulated signals and allowing retranmission of only the uplink signals of designated telecommunications systems; said leaky cable transporting and transmitting downlink signals of designated telecommunications systems to at least one transceiver, said leaky cable also receiving, transporting and transmitting uplink signals from at least one transceiver to the donor site(s) of respective designated telecommunications systems.