MXPA99002531A - Antenna system for enhancing the coverage area, range and reliability of wireless base stations - Google Patents

Abstract

An active antenna system which has a plurality of antenna elements arranged in a column with each element or subarray of elements integrated with an amplifier and other beam forming components. A separate amplifier and filter are disposed immediately adjacent and connected to each of the antenna elements or a subarray of antenna elements and a separate combiner/divider is connected to each of the amplifiers. The antenna elements, amplifier and filter are disposed on a common support. A base station is connected by the feed cables and is remote from each amplifier. A first group of the antenna elements with low power amplifiers forms a transmitting antenna system and/or a second group of the active antenna elements with low noise amplifiers forms a receiving antenna system. A variable attenuator and a variable phase shift circuit can be integrated with each amplifier and can be used for beam shaping and electronic beam pointing. For diversity combining, spatially separated or polarization diverse active antennas are used. For polarization diverse active antennas, implementation involves a shared column or two colocated orthogonally polarized columns.

Description

ANTENNA SYSTEM TO IMPROVE THE AREA OF COVERAGE. THE RANGE CO-RELIABILITY OF WIRELESS BASE STATIONS BACKGROUND OF THE INVENTION FIELD OF THE INVENTION This invention relates to an anten system and, more specifically, to an antenna system primarily to be used in conjunction with a base station in mobile communication systems.

BRIEF DESCRIPTION OF PREVIOUS ART The mobile communication systems generally include a base station for receiving and transmitting electromagnetic radiation with the mobile terminal placed within the coverage area of the base station to transmit electromagnetic radiation and receive such radiation from the base station and where several of Such base stations are generally linked together via base station controllers (BSCs) and master station controllers (MSCs) to provide a seamless communication link between a mobile terminal and the calling party.

Mobile communications are typically comprised within two bands. Those systems approximately 850 and 950 MHZ are mentioned as cellular those systems between approximately 1.8 and 2.0 GHz s mentioned as personal communication systems (PCSs). L total mobile applications which together cover ambbanks are frequently mentioned as personal communication networks (PCNs). This invention relates to all personal communication network systems, for example the systems which operate in either or both of the frequency bands listed above.

The area, range and reliability of the base stations are generally limited in their coverage area by the effective radiated isotropic energy transmission (EIRP) and the received noise figure. The communication network base station architecture currently used uses a vertical column arrangement comprising a plurality of radiating elements spaced apart by the transmission and one of such a plurality of separate radiation elements for reception. The antenna elements are generally placed in a vertical straight line on a support, at a distance between the end antenna elements, often being very large, often a few meters.

To improve performance, the receiving antenna configuration generally comprises two widely spaced columns to provide a spatial diversity or an orthogonally unique polarized column comprising orthogonal polarization outputs to provide polarization diversity.

The radiating elements are generally electrically conductive members placed on a support and are generally spaced between three quarters and one wavelength. The antenna elements are generally connected to a combiner through short transmission lines.

For the transmission configuration, the radiation element is powered by a power amplifier above the ground through a long cable typically between 50 and 200 feet. The placement of the power amplifiers within the base station also requires increasing the force from the amplifiers to overcome the insertion loss from the power cable as well as the combiner.

For receiving configurations, the combiner output is fed to a low noise / filter amplifier (LNA) combination through any short transmission line (as in personal communication network systems for low noise amplifiers) or through a long cable (as in cellular systems for integrated base station low noise amplifiers). Dual redundant amplifiers are typically provided when mast-mounted electronics are used to improve reliability at the cost of complexity. For the receiving configuration, the actual noise increase contributed by the sonic losses in the combiner and the power cable (depending on its length) are amplified by the low noise amplifier and therefore contribute to the increase in the figure of system noise.

There has been a constant desire to improve the range and coverage area capacity for the individual bas stations used in the wireless communication systems of the type described above. One way to solve this problem has been to place a redundant pair of low-noise amplifiers on top of the tower and connect the low-noise amplifiers to a passive antenna column (eg antenna elements with a combiner) with a short transmission line and a switch. The loss of the combined and the loss of the commutator still limits the figure of receiving system noise.

SYNTHESIS OF THE INVENTION The problem noted above is minimized and provides an improvement in the coverage area, range and reliability of the base station by improving transmission efficiency and base station reception sensitivity without sacrificing reliability. These better allow the extension of the communication coverage area for a given base station.

Briefly, the aforementioned improvement is achieved by substituting existing antenna designs for use in conjunction with mobile communication systems with an active phase array antenna. active phase array antenna approach according to the present invention incorporates a low power amplifier (to transmit) and / or a low noise amplifier (pa receive) as closely adjacent as possible to the element of an array, generally separated by a few centimeters or less of the associated element. The antenna elements are usually placed in a column. As an alternative, a filter and an amplifier can be coupled to a subset of array elements, even though this arrangement will provide less versatility as will be evident from the discussion below. The active antenna approach p involves both distributing a plurality of filter amplifiers, when required, through the aperture array. These advantages of the active antenna system for the transmit and receive configurations are discussed briefly below.

For receiving configurations, by keeping the low noise amplifiers close to the radiating elements, the noise of the system is reduced as much as by 4.5 d over the conventional approach in which the low noise amplifier is integrated with the base station and by as much as 1.5 dB where a low noise amplifier is integrated with the passive antenna column on top of the torr or antenna system mast.

Since a significant percentage of the effective noise degradation in the antenna system is a result of the loss in the power cables and the power combiners, it can be seen that, as in the case of the reception section, the Active antenna, the noise taken by the power cables is never amplified while this noise is amplified in the previous art system. Thus, a smaller effective noise element arrives at the base station in relation to the prior art system described above.

Similarly, for configurations of transmitting the low power amplifiers, when integrated with the radiation elements, they increase the EIRP as much as 4.5 dB (for the same amplifier power output) over the conventional approach where the power amplifiers are integrated with the base station.

The distributed nature of the amplifiers also improves reliability since the system can be designed to be completely compliant even after the failure of one or more of the reception or transmission amplifiers. Even when sufficient failures occur to reduce the overall system operation , performance degradation is funny rather than catastrophic.

In the transmission configuration, using active antenna systems, the noise in the power cord amplified by the amplifiers is not of concern, since the signal power is several tenths of dB higher than the noise power. The main advantage of the active antenna systems for the transmission case is that, since the power amplifiers are placed between the antenna elements and the power cable which is connected to the base station impeller amplifier, there is no reduction in the amplified signal power due to the loss of the cable and combiner as in the case of the existing personal communication network base stations.

Another advantage of distributed potentiometer amplifiers is that the amplifiers operate in a reduced thermal density ambient, giving improved reliability. The reduced thermal density results from the fact that the heat is distributed through the entire area occupied by the heating elements. antenna in an array rather than in a small concentrated area as in the case of the unit upper power amplifiers used in the existing PC base stations.

Since the impact of the elements of loss after the low noise amplifiers or preceding the low power amplifiers on the figure of system noise or EIRP respectively is small, the active anten system is capable of a great amount of versatility in e sense that variable attenuators and / or d-phase changers can be placed in the signal path of each antenna element. As is well known in the art, these variable attenuators and phase shifters can operate to provide beam shaping and pointing capability.

The active antenna systems of the present invention can be used for reception systems using spatial or polarization diversity and are in fact valid regardless of the diversity approach used. Therefore, all the advantages claimed for active antennas apply to all diversity reception systems. In addition in the diverse polarization reception system, both orthogonal polarizations are implemented with each polarization port fed to its own filter / network of low noise amplifier and combiner.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagram of an architecture of the personal communication network base station of the prior art for an antenna system for both the transmission and reception of electromagnetic radiation; Figure 2 is a diagram of an active antenna system architecture according to the first embodiment of the present invention; Y Figure 3 is a diagram of an active antenna system architecture according to a second embodiment of the present invention.

DESCRIPTION OF PREFERRED INCORPORATIONS Referring first to Figure 1, a system is shown using the personal communication network bas station antenna architecture of the prior art. Figure 1 is typical of the existing state of the art for personal communication anten systems. However, the discussion that follows does apply to existing cellular systems as well. The system includes a transmission antenna system 1 and a reception antenna system 7. The transmission antenna system includes a support 3 having thereon a plurality of radiant antenna elements 5 placed in a straight line, the distance from the element most superior to the lowest element being a few meters. The transmission antenna system 1 has a high power amplifier (HPA) 13 a filter 15 placed in the base station 17 with the amplifier / filter being connected to each of the variation antenna element 5 through a combiner 54 and of a power cable 31 with the length of the supply cable 31 varying in any of between 15 and 70 meters in general. As can be seen, the long cable 31 leads to a loss of two to three dB of the power transmitted by the base power amplifier to ground.

The receiving antenna system 7 includes a support 9 thereon, a plurality of antennas radiating elements 11 placed in a straight line with dimensions such as the transmission antenna system. The receiving antenna system 7 has a pair of filters 19, 21, the filter 19 couples to a pair of amplifiers 23 and 25 and to the filter 21 coupled to pair of amplifiers 27 and 29. Each antenna element radiates 11 is coupled to each one of the filters 19 and 21 through the power combiners 55 and 56 through the power cable 33 to provide horizontal vertical outputs. Even when the incorporation is shown for reception system with polarization diversity, my discussion applies to the reception system use spatial diversity. For the purpose of illustration, low noise amplifier / filter combination is shown mounted on the mast, as is the common practices for the base stations of the personal communication system. As can be seen, the ohmic losses in the combiners and the short transmission lines between the combiners and the low noise filter / amplifier combination contribute to degradation in the system noise figure.

Referring to Figure 2, there is shown an active antenna architecture according to the present invention. The antenna is similar to that of Figure 1 except that all the radiating antenna elements 5 and 11 are on the same support 35, and rather that having a single filter 15 and amplifier 13 for the transmission section and the filters 1 and 21 and the associated amplifiers 23, 25, 21 and 29 for reception station as shown in Figure 1, the radiating antenna element has its own filter and amplifiers placed as close to the antenna element as possible. This is shown in Figure 2 where, for the transmission part, each antenna element 5 is connected to the filter itself 37 and the amplifier 39 with the power cable 41 extending from the base station 43 to ac one of the amplifiers 39 through the energy divider 54 In the receiving part each radiant antenna element 1 has two outputs orthogonally polarized as in the figure with each output having its own filter 45 and pair d amplifiers 47 and 49. The outputs of the amplifiers 47 49 they are combined and the power combiners 55 and 56 are fed to the base station through the power cables 51 and 53 respectively. The reception configuration with polarization diversity is shown here for the purpose of illustration. However, the active antenn claim is kept well for the reception configuration with spatial or any other diversity as well.

For the reception configuration, it should be understood that the positions of the amplifiers and associated filters can be reversed where the amplification can take place before filtering or filtering can take place before amplification. Where the filter is placed in front of the amplifier, the impact of the filter loss on the noise figure of the system is reduced, but the amplifier phase must be designed to have a high dynamic range, so that the expected interference can be passed through the amplifier. amplifier to the filter without generating any significant intermodulation products. When the amplifier is placed in front of the filter to provide a bandpass of the signals before the band signal amplification (as shown in Figure 2), the filter should have a low power loss with implementation preferably carried over to out on waveguides.

Referring now to Figure 3, a variation of the architecture of Figure 2 is shown in which a variable phase change 51 and a variable attenuator 53 are placed in series with each combination of the amplifier and the filter of Figure 2. By varying phase and amplitude, s provides the ability to electronically tilt the ray and form the beam in elevation, depending on traffic patterns and the topography of the cell being served. Shaping and switching of the elevation beam can be dynamically controlled by the service provider through a remote controller.

A second embodiment of the invention comprises only the receiving part of the structure described above and a third embodiment of the invention comprises only the transmission part of the structure described above.

Even though the invention has been described c with respect to the preferred embodiments thereof, many variations and modifications will be readily apparent to those skilled in the art. It is therefore intended that the appended claims be interpreted as widely as possible in view of prior art to include all variations and modifications.

Claims (18)

R E I V I N D I C A C I O N S

1. An antenna system, comprising a plurality of transmission antenna elements; a plurality of transmit amplifiers individually connected in a one-on-one configuration to said plurality of transmit antenna elements; a transmission splitter having an input terminal for connection to a base station and a plurality of output terminals individually connected in a one-to-one configuration to said plurality of transmission amplifiers; a plurality of reception antenna elements d; a plurality of reception amplifiers individually connected in a one-to-one configuration to said plurality of reception antenna elements; Y a receiving combiner having an output terminator for connection to a base station and a plurality of individually connected input terminals in a one-to-one configuration to said plurality of reception amplifiers.

2. The antenna system, as claimed in clause 1, characterized in that it also comprises a plurality of transmission filters individually connected in a one-to-one configuration to said plurality of transmission amplifiers.

3. The antenna system, as claimed in clause 1, characterized in that it further comprises a plurality of reception filters connected individually in a one-to-one configuration to said plurality of reception amplifiers.

4. The antenna system, as claimed in clause 1, characterized in that it also includes means for holding in a single assembly said plurality of transmission antenna elements, said plurality of transmission amplifiers, said transmission splitter, said plurality of transmission d reception antenna elements, said plurality of reception amplifiers and said receiver combiner.

5. The antenna system, as claimed in clause 1, characterized in that said transmission antennas elements and said receiving antenna elements exhibit spatial diversity.

6. The antenna system, as claimed in clause 1, characterized in that said transmission antennas elements and said receiving elements exhibit diversification of polarization.

7. The antenna system, as claimed in clause 1, characterized in that said reception antenna elements exhibit polarization diversity.

8. An antenna system comprising: a plurality of receiving antenna elements d, each receiving antenna element having two diversity output; a first plurality of reception amplifiers d individually connected in a configuration of an envelope one in one of the outputs of said plurality of reception antenna element; a first receiver combiner having an output for connection to a base station and a plurality of input terminals individually connected in a one-to-one configuration to said first plurality of reception amplifiers; a second plurality of reception amplifiers d individually connected in a configuration of one envelope with the other terminal of said plurality of reception antenna element; Y a second receiver combiner having an output terminal for connection to a base station and a plurality of input terminals individually connected in a one-to-one configuration to said second plurality of reception amplifiers.

9. The antenna system, as claimed in clause 8, characterized in that it comprises: a plurality of transmission antenna elements; a plurality of transmit amplifiers individually connected in a one-on-one configuration to said plurality of transmit antenna elements; Y a transmission splitter having an input termination for connection to a base station and a plurality of output terminals individually connected in a one-to-one configuration to said plurality of transmit amplifiers.

10. The antenna system, as claimed in clause 8, characterized in that the receiving antenna elements have two orthogonally polarized outputs.

11. The antenna system, as claimed in clause 8, characterized in that it also comprises: a first plurality of filters individually connected in a one-on-one configuration to the first plurality of reception amplifiers; Y a second plurality of filters individually connected in a one-on-one configuration to the second plurality of reception amplifiers.

12. The antenna system, as claimed in clause 9, characterized in that it also comprises: a plurality of transmission filters connected individually in a one-on-one configuration to said plurality of transmission amplifiers.

13. An antenna system comprising: a plurality of transmission antenna elements; a plurality of transmission amplifiers individually connected in a configuration of not on a said plurality of transmission antenna elements; a plurality of variable transmission attenuators d connected individually in a one-on-one configuration to said plurality of transmission amplifiers; a transmission splitter having an input terminal for connection to a base station and a plurality of output terminals individually connected in a one-to-one configuration through said plurality of variable attenuators and said plurality of transmission amplifiers for said plurality of transmission antenna elements; a plurality of receiving antenna elements; a plurality of reception amplifiers individually connected in a one-over configuration to said plurality for receiving antenna elements; a plurality of variable attenuators individually connect in a one-to-one configuration to plurality of reception amplifiers; Y a receiving combiner having an output terminator for connection to a base station and or plurality of individually connected input terminals in a one-to-one configuration through said plural to receive the amplifiers and through said plurality of variable reception attenuators to said plurality of reception antenna elements.

14. The antenna system, as claimed in clause 13, characterized in that it also comprises: a plurality of variable shift phasing circuits individually connected in a one-on-one configuration through said plurality of transmission amplifiers and through said plurality of variable transmission attenuators to said plurality of transmission antenna elements; and a plurality of reception variable switching circuits individually connected in a one-to-one configuration through said plurality of reception amplifiers and through said plurality of variable reception attenuators to said plurality of reception antenna elements.

15. The antenna system, as claimed in clause 14, characterized in that it also comprises: a plurality of transmission filters connected individually in a one-on-one configuration through said plurality of transmission amplifiers said plurality of variable transmission attenuators to said plurality of transmission antenna elements; Y a plurality of reception filters connected individually in a one-to-one configuration through said plurality of reception amplifiers and through said plurality of variable attenuators of reception to plurality of reception antenna elements.

16. An antenna system comprising: a plurality of receiving antenna elements, each receiving antenna element having two diversity outputs; a first plurality of reception amplifiers individually connected in a configuration of u on one to one of the outputs of said plurality to receive antenna elements; a first receiving combiner having an output for connection to a base station and a plurality of input terminals individually connected in a one-to-one configuration to said first plurality of receiving amplifiers; a second plurality of reception amplifiers individually connected in a configuration of u on to the other terminal of said plurality of reception antenna elements; a second receiving combiner having an output terminal for connection to a base station and a plurality of input terminals individually connected in a one-on-one configuration to said second plurality of receiving amplifiers; a first plurality of variable receive attenuators individually connected in a one-over-one configuration to said first plurality of reception amplifiers; Y a second plurality of variable receive attenuators individually connected in a one-over-one configuration to said second plurality of reception amplifiers.

17. The antenna system, as claimed in clause 16, characterized in that it also comprises: a plurality of receiver variable shift circuits individually connected in a one-to-one configuration through said plurality of reception amplifiers and through said plurality of variable attenuators to said plurality of reception antennas.

18. The antenna system, as claimed in clause 16, characterized in that it also comprises: a plurality of reception filters connected individually in a one-to-one configuration through said plurality of reception amplifiers and through said plurality of variable reception attenuators to said plurality of reception antenna elements. SUMMARY An active antenna system which has a plurality of antenna elements arranged in a column with each element or sub-array of elements integrated with amplifier and other beam-forming components. Separate amplifier and filter are immediately placed on one side and connected to each of the antenna elements or sub-array of antenna elements and a separate combo / splitter is connected to each of the amplifiers. The antenna elements, the amplifier and the filter is placed on a common support. A base station is connected by the power cables and is remote from the amplifier. A first group of antenna elements with low power amplifiers forms a transmission antenna system and / or a second group of active antenna elements with noise amplifiers in the form of a receiving antenna system. A variable attenuator and a variable phasing circuit can be integrated with each amplifier and can be used for beam change and electronic beam aiming. For a combination of diversity, active polarization or spatially separated polarization antennas are used. For the diverse polarization active antenna the implementation involves a shared column or two polarized columns placed orthogonally.