WO2001001582A2

WO2001001582A2 - Integrated adaptive phased arrays and sector antennas

Info

Publication number: WO2001001582A2
Application number: PCT/IB2000/001639
Authority: WO
Inventors: Bjorn Johannisson; Bo Hagerman; Thomas Ostman; Gunnar Monell
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 1999-04-29
Filing date: 2000-04-28
Publication date: 2001-01-04
Also published as: AU1167901A; WO2001001582A3

Abstract

The physical space available to install both a sector antenna and an adaptive, phased-array antenna at a cellular radio telecommunications base station may be significantly reduced, and the costs associated with manufacturing, installing and maintaining both a sector antenna and an adaptive, phased-array antenna may be appreciably reduced by incorporating the sector antenna and the phased-array antenna into a single antenna cartridge. In so doing, both the sector antenna and the adaptive, phased-array antenna may be supported by a single radio transceiver unit.

Description

INTEGRATED ADAPTIVE AND SECTOR ANTENNAS

FIELD OF INVENTION The present invention relates the field of cellular, radio telecommunications. More particularly, the present invention relates to cellular, radio telecommunications systems which employ both sector antennas and adaptive, phased-array antennas.

BACKGROUND

FIG. 1 illustrates a conventional, cellular radio telecommunications system 100. As shown, it includes a number of radio base stations 105a-n, each of which is connected to a corresponding base station antenna 1 lOa-n. The radio base stations 105a-n, in conjunction with antennas 1 lOa-n, communicate with mobile stations (e.g. , mobile stations 120a, 120b and 120m) operating in a corresponding 130a-n. Radio communication from a base station to a mobile station is referred to as the downlink, whereas radio communication from a mobile station to a base station is referred to as the uplink. In addition, the base stations 105a-n are connected to a mobile switching center (MSC) 150. The MSC 150, in turn, is connected to a public switched telephone network (PSTN) 160, which services various communication devices such as telephones 180a, personal computers 180b, and facsimile machines 180c.

As stated, each base station 130a-n is connected to a corresponding base station antenna 1 lOa-n, through which, the base stations communicate with mobile stations. In general, each antenna may comprise several sector antennas. A sector antenna is designed to transmit and receive radio energy to and from a particular geographic region or sector within a corresponding cell. By restricting the sector antenna to a particular sector, interference emanating from sources located outside the sector is minimized. This, in turn, improves the signal quality between the base station and the mobile stations operating in that sector of the cell. Typically, a base station may employ three sector antennas, each covering one of three 120 degree sectors, as illustrated in FIG. 2A. Alternatively, a base station may employ six sector antennas, each covering one of six 60 degree sectors, as illustrated in FIG. 2B.

As one skilled in the art will readily appreciate, it is possible to further reduce interference levels by transmitting and receiving radio energy to and from sectors which are smaller than those illustrated in FIGs. 2A and 2B. One method for accomplishing this is through the use of fixed-beam, phased-array antennas. FIG. 2C shows an exemplary antenna pattern 200 for a fixed-beam, phased-array antenna associated with a base station 205, wherein the exemplary antenna pattern 200 comprises a number of narrow antenna beams B, through B_m. FIG. 2C also illustrates that each of the antenna beams Bj through B_m remains fixed, whether or not a mobile station is operating in the corresponding sector of the cell. This results in unnecessary radio energy propagation, and it contributes to the overall level of interference experienced by mobile stations operating in other sectors of the cell, or in nearby cells. It also contributes, unnecessarily, to the signal processing and power load requirements imposed on the base station's resources. The shortcomings of fixed-beam, phased-array antennas, mentioned above, may be mitigated to some extent by employing an adaptive, phased-array antenna. FIG. 2D illustrates an exemplary antenna pattern 240 associated with an adaptive, phased-array antenna 250, wherein antenna pattern 240 comprises only two antenna beams b, and b₂ which are employed for point-to-point communication with the two mobile stations A and B. A comparison of the antenna pattern in FIG. 2C and FIG. 2D shows that the amount of radio energy propagated into the cell by the base station can be significantly reduced by employing adaptive, phased-array antennas. The use of adaptive, phased-array antennas is well-known in the art. In many conventional, cellular radio telecommunications systems, a base station may employ sector antennas and adaptive, phased-array antennas simultaneously. In general, the sector antennas are used for broadcasting control channel signals throughout the entire cell, whereas the adaptive, phased-array antennas are used for selective, point-to-point traffic channel communication, as illustrated in FIG. 2D.

When both a sector antenna and a phased-array antenna are employed simultaneously by a base station, the sector antenna is, typically, disposed in a first cartridge, while the phased array antenna is disposed in a second, separate cartridge, wherein the first and the second cartridges are located some distance apart from each other as a function of wavelength. This arrangement, however, is not desirable. First, disposing the sector antenna and the phased-array antenna in separate cartridges takes up a great deal of space. Second, such an arrangement is costly, as two rather than one cartridge must be manufactured and installed. Moreover, much of the hardware required to support the sector antenna and the phased-array antenna is duplicated. Accordingly, it would be highly desirable to provide both a mechanical and electrical solution to facilitate the co-location of a sector antenna and a phased-array antenna, particularly an adaptive, phased-array antenna, in a single antenna cartridge.

SUMMARY OF THE INVENTION The present invention combines a sector antenna and a phased-array antenna into a single, integrated unit. In doing so, space is conserved and the base station antenna is generally more aesthetically pleasing. In addition, this antenna arrangement is less costly to manufacture, install and maintain as there is one antenna cartridge rather than two, and because both the sector antenna and the phased-array antenna may be supported by a single radio transceiver. Further, one antenna cartridge makes it possible for integrating common switch matrixes and amplifier structures connected to both the array and the sector antenna.

In accordance with a first aspect of the invention an antenna arrangement is provided wherein a sector antenna and a phased-array antenna are housed within a single antenna cartridge, such that the sector antenna is positioned immediately adjacent to the phased-array antenna.

In accordance with a second aspect of the invention an antenna arrangement is provided wherein a sector antenna and a phase-array antenna are housed within a single antenna cartridge, such that the sector antenna and the phased-array antenna share at least one radiating element.

In accordance with a third aspect of the invention an antenna arrangement is provided wherein a sector antenna, a phased-array antenna, a transmit switch matrix and a receive switch matrix are housed within a single antenna cartridge, such that the sector antenna is positioned immediately adjacent to the phased-array antenna.

In accordance with a fourth aspect of the invention an antenna arrangement is provided wherein a sector antenna, a phased-array antenna and a transmit amplifier array are housed within a single antenna cartridge, such that the sector antenna is positioned immediately adjacent to the phased-array antenna. In accordance with a fifth aspect of the invention an antenna arrangement is provided wherein a sector antenna, a phased-array antenna, transmit and receive switch matrices and a transmit amplifier array are housed within a single antenna cartridge, such that the sector antenna is positioned immediately adjacent to the phased-array antenna. BRIEF DESCRIPTION OF THE FIGURES

The objectives and advantages of the present invention will be understood by reading the following detailed description in conjunction with the drawings, in which: FIG. 1 illustrates a conventional cellular radio telecommunications network;

FIGs. 2A-D illustrate exemplary base station antenna patterns;

FIG. 3 illustrates a conventional antenna arrangement for a sector antenna and an adaptive, phased-array antenna; FIG. 4 illustrates a sector antenna and adaptive, phased-array antenna arrangement, in accordance with a first exemplary embodiment of the present invention;

FIG. 5 is a block diagram of the antenna arrangement in accordance with the first exemplary embodiment of the present invention; FIG. 6 illustrates a sector antenna and adaptive, phased-array antenna arrangement, in accordance with a second exemplary embodiment of the present invention;

FIGs. 7A and B are block diagrams of the antenna arrangement in accordance with the second exemplary embodiment of the present invention; FIG. 8 illustrates a transceiver unit and switching configuration in accordance with exemplary embodiments of the present invention;

FIGs. 9A-D illustrate exemplary antenna cross sections for increased isolation and improved radiation characteristics;

FIG. 10 is a block diagram of an antenna arrangement in accordance with the third exemplary embodiment of the present invention;

FIG. 11 is a block diagram of the antenna arrangement in accordance with the fourth exemplary embodiment of the present invention; and FIG.12 is a block diagram of the antenna arrangement in accordance with the preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION In many conventional radio telecommunications systems, the base station includes both a sector antenna, for broadcasting control channel signals, and an adaptive, phased-array antenna, for broadcasting point-to-point traffic channel communications. To avoid problems with the antenna pattern of one antenna affecting the antenna pattern of the other antenna, the sector antenna and the adaptive, phased-array antenna are disposed in separate units or cartridges, which are located a sufficient distance from each other, as illustrated in Fig. 3.

However, this arrangement is expense to manufacture, install and maintain.

Moreover, if the two antennas are not aligned properly, with respect to each other, the two antennas may still interfere with each other. In addition, this arrangement takes up a great deal of space, though it is becoming more and more important to keep the physical size of the antenna arrangement to a minimum for aesthetic reasons.

The present invention integrates the sector antenna and the adaptive, phased-array antenna into a single unit or cartridge. In so doing, the above- identified deficiencies associated with conventional configurations are avoided. Of course, there are different ways in which to integrate the two antennas within a single antenna cartridge.

Fig. 4 depicts a first exemplary embodiment of the present invention. As shown, the sector antenna is located immediately adjacent to the adaptive, phased- array antenna. Although the two antennas are enclosed within a single common radome, they are functionally separate. Fig. 5 is a block diagram which illustrates this first exemplary embodiment.

Since the sector antenna and the adaptive, phased-array antenna are located immediately adjacent to one another, the mutual effect between the two antennas may be considerable. Thus, when power is applied to one of the antennas, a portion of that power may be coupled to the radiating elements associated with the other antenna, whereby the antenna pattern associated with one of the antennas affects the other. Accordingly, it is necessary to control this coupling. This may be accomplished by adjusting the position of the individual radiating elements (e.g. , dipoles or microstrip patches) that make up the sector antenna and the adaptive, phased-array antenna as illustrated in FIG 9D. Alternatively, a partition, such as a metal divider, or a choke may be placed between the sector antenna and the adaptive, phased-array antenna, as illustrated in FIGs 9A-C.

Fig. 6 depicts a second exemplary embodiment of the present invention. As shown, the sector antenna is physically incorporated into the adaptive, phased- array antenna. A difference between this embodiment and the previous embodiment is that the sector antenna and the adaptive, phased-array antenna share the power, which results in lower power gain.

In Fig. 6, the left-most column of elements serves both the sector antenna and the adaptive, phased-array antenna. In principle, any of the array columns may be shared. From the vantage point of the sector antenna, however, employing one of the center-most columns would be preferable, as any influence on the sector antenna pattern will be symmetric in the azimuth plane. Although, the antenna pattern associated with the adaptive, phased-array antenna is more likely to be distorted. Choosing one column of elements in the array over another column of elements will, of course, depend on system performance requirements. Fig. 7 A is a block diagram illustrating this second exemplary embodiment. In addition, it is possible to have more than one beam port for sector beam coverage. For example, Fig. 7B illustrates a block diagram of an antenna arrangement using common radiating elements for two sector beam ports.

One advantage attributable to integrating the sector antenna and the adaptive, phased-array antenna into a single antenna cartridge is that such a configuration facilitates the use of a single transceiver unit in support of both antennas. Fig. 8 illustrates a sector antenna 805 and an adaptive, phased-array antenna 810 set immediately adjacent to one another in accordance with the first exemplary embodiment described above, wherein the sector antenna 805 and the adaptive, phased-array antenna 810, along with beam forming unit 815, which may comprise a conventional beam former, such as a butler matrix, are supported by a single transceiver unit 820, a transmit switch 825 and a receive switch 830. Fig. 8 also shows that the sector antenna 805 and each element of the adaptive, phased-array antenna 810 may be connected to one or more of the radio transmitters 835 and radio receivers 840 through transmit switch 825 and receive switch 830, respectively. The transmit switch 825 and the receive switch 830 are utilized by the transceiver unit 420 to selectively assign resources to either or both the sector antenna 805 and the adaptive, phased-array antenna 810 under the supervision of a control unit 845.

The transceiver unit 820 along with sector antenna 805 and the adaptive, phased-array antenna 810 are readily configurable through the use of the transmit switch 825 and the receive switch 830. In addition, the configuration is significantly more flexible, as compared to conventional designs, wherein each antenna is served by a dedicated transceiver unit.

FIG. 10 depicts a third exemplary embodiment of the present invention. As shown, a sector antenna 1020 and an adaptive, phased-array antenna 1030, which are set immediately adjacent to one another, a beamformer unit 1040, a transmit switch matrix 1050 and a receive switch matrix 1060 are all located within the antenna enclosure 1010.

FIG. 11 depicts a fourth exemplary embodiment of the present invention. As shown, a sector antenna 1020 and an adaptive, phased-array antenna 1030, which are set immediately adjacent to one another, a beamformer unit 1040, and a transmit amplifier array 1070 are all located within the antenna enclosure 1010. The transmit amplifier array 1070 contains a first hybrid matrix for spreading an amount of transmit power associated with a given transmit feeder port across each of the plurality of multi-carrier power (MCP) amplifiers, and a second hybrid matrix for combining each amplified output signal associated with the plurality of multi-carrier amplifiers and forwarding the combined signal to the corresponding antenna port.

FIG. 12 depicts a fifth and preferred embodiment of the present invention. As shown, a sector antenna 1020 and an adaptive, phased-array antenna 1030, which are set immediately adjacent to one another, a beamformer unit 1040, a transmit switch matrix 1050, a receive switch matrix 1060, low noise amplifiers 1080 and transmit amplifier array 1070 are all located within the antenna enclosure 1010.

The integration of the sector antenna and the adaptive, phased-array antenna, the transmit and receive switch matrices and the transmit amplifier array into a single antenna cartridge provides many advantages. In addition to the configuration facilitating the use of a single transceiver unit in support of both antennas, it reduces transmit power requirements, provides flexibility in feeder cable selection, and it reduces power loss due to the close proximity of the amplifier array with the radiating elements.

The present invention has been described in accordance with a number of exemplary embodiments, which are intended to be illustrative in all aspects, rather than restrictive. Thus, the present invention is capable of many variations in detailed implementation, which may be derived from the description contained herein by a person or ordinary skill in the art. All such variations are considered to be within the scope and spirit of the present invention as defined by the following claims.

Claims

WHAT IS CLAIMED IS:

1. An antenna arrangement comprising: a sector antenna for transmitting and receiving radio signals to and from a corresponding region; a phased-array antenna for transmitting and receiving radio signals to and from a particular location within said region; and a single antenna cartridge housing said sector antenna and said phased-array antenna, said sector antenna being positioned immediately adjacent to said phased-array antenna, within said single antenna cartridge.

2. The antenna arrangement of claim 1, wherein said phased-array antenna is an adaptive, phased-array antenna.

3. The antenna arrangement of claim 1 further comprising: means for controlling radio energy coupling between said sector antenna and said phased-array antenna.

4. The antenna arrangement of claim 3, wherein said means for controlling radio energy coupling between said sector antenna and said phased- array antenna comprises: means for adjusting the position of individual radiating elements associated with said sector antenna and said phased-array antenna.

5. The antenna arrangement of claim 3, wherein said means for controlling radio energy coupled between said sector antenna and said phased- array antenna comprises: means for physically isolating said sector antenna from said phased- -l i¬

ar ray antenna.

6. The antenna arrangement of claim 5, wherein said means for physically isolating said section antenna from said phased-array antenna comprises: a metal divider located between said sector antenna and said phased-array antenna.

7. An antenna arrangement comprising: a sector antenna for transmitting and receiving radio signals to and from a corresponding region, wherein said sector antenna includes a first number of radiating elements; and a phased-array antenna for transmitting and receiving radio signals to and from a particular location within said region, wherein said phased-array antenna includes a second number of radiating elements, and wherein said sector antenna and said phased-array antenna share at least one radiating element.

8. The antenna arrangement of claim 7 further comprising: a single antenna cartridge housing said sector antenna and said phased-array antenna.

9. The antenna arrangement of claim 7, wherein said phased-array antenna is an adaptive, phased-array antenna.

10. In a cellular, radio telecommunications system, a base station for controlling radio communications in a corresponding cell, said base station comprising: a sector antenna for transmitting and receiving radio signals to and from a corresponding sector of the cell; an adaptive, phased-array antenna for transmitting and receiving radio signals to and from a particular location within the sector; a transmit switch coupled to said sector antenna and said adaptive, phased-array antenna; a receive switch coupled to said sector antenna and said adaptive, phased-array antenna; and a single antenna enclosure containing said sector antenna, said adaptive, phased-array antenna, said transmit switch and said receive switch.

11. The base station of claim 10, wherein said transmit switch is connected to each antenna element associated with said sector antenna and to each antenna element associated with said adaptive, phased-array antenna, and wherein said receive switch is connected to each antenna element associated with said sector antenna and to each antenna element associated with said adaptive, phased- array antenna.

12. The base station of claim 11 further comprising a plurality of amplifier units, wherein each of said amplifier units couples said receive switch with a corresponding one of said antenna elements associated with said sector antenna and said adaptive, phased-array antenna, and wherein said amplifier units are contained within said single antenna enclosure.

13. The base station of claim 12, wherein each amplifier unit is a low- noise amplifier.

14. The base station of claim 11, wherein said receive switch comprises a switch matrix.

15. The base station of claim 11 further comprising a transmit amplifier unit, wherein said transmit amplifier unit couples said transmit switch with the antenna elements associated with said sector antenna and said adaptive, phased- array antenna, and wherein said transmit amplifier unit is contained within said single antenna enclosure.

16. The base station of claim 15, wherein said transmit amplifier unit comprises an amplifier array, and wherein said transmit amplifier unit comprises means for spreading an amount of transmit power associated with a given transmit feeder port across each of a plurality of multi-carrier power amplifiers which make up the amplifier array.

17. The base station of claim 11 , wherein said transmit switch comprises a switch matrix.

18. The base station of claim 10 further comprising: means for controlling radio energy coupling between said sector antenna and said adaptive, phased-array antenna.

19. In a cellular, radio telecommunications system, a base station for controlling radio communications in a corresponding cell, said base station comprising: a sector antenna for transmitting and receiving radio signals to and from a corresponding sector of the cell; an adaptive, phased-array antenna for transmitting and receiving radio signals to and from a particular location within the sector; a plurality of low-noise amplifiers associated with the received radio signals, wherein each antenna element associated with the sector antenna and each antenna element associated with the adaptive, phased-array antenna is coupled to a corresponding one of said low-noise amplifiers; a transmit amplifier array associated with the transmitted radio signals, wherein said transmit amplifier array is coupled to the antenna elements associated with the sector antenna and the adaptive, phased-array antenna; and a single antenna enclosure containing said sector antenna, said adaptive, phased-array antenna, said plurality of low-noise amplifiers and said transmit amplifier array.

20. The base station of claim 19 further comprising: a receive switch matrix, wherein said receive switch matrix is coupled to the antenna elements by said plurality of low-noise amplifiers, and wherein said receive switch matrix is contained within said single antenna enclosure.

21. The base station of claim 19 further comprising: a transmit switch matrix, wherein said transmit switch matrix is coupled to the antenna elements by said transmit amplifier array, and wherein said transmit switch matrix is contained within said single antenna enclosure.

22. The base station of claim 21, wherein said transmit amplifier array comprises: a plurality of multi-carrier power amplifiers; a first hybrid matrix coupled to said transmit switch matrix through a number of transmit feeder ports, said first hybrid matrix including means for spreading an amount of transmit power associated with a given transmit feeder port across each of the plurality of multi-carrier power amplifiers; and a second hybrid matrix for combining each amplified output signal associated with the plurality of multi-carrier amplifiers, and forwarding the combined signal to a corresponding antenna port.