Various aspects of the present disclosure may relate to wireless communications, and, more particularly, to base station antennae radiation pattern control.
To provide increased coverage and throughput, additional base stations (e.g., small-cell base stations) are being deployed along with macro-cell base stations, especially in urban areas. An antenna system of a small-cell base station may be placed around a support structure, such as a pole and may operate as a circular array. Accordingly, the circular array may operate as an array of antenna elements with phase centers located on a circle, and may be used to form a quasi-omnidirectional radiation pattern in the azimuth plane.
Even though a quasi-omnidirectional radiation pattern may be desirable for many scenarios and environments, other types of radiation patterns, and even other shapes of quasi-omnidirectional radiation patterns may be advantageous. For example, a quasi-omnidirectional radiation pattern may initially be a good option for broad area coverage. However, such a pattern may limit throughput if the number of users in a given area is increased. In such a scenario, a different pattern of radiation may be more desirable. However, such a change in shape and/or radiation pattern typically requires replacing the installed base station antenna and/or changing its orientation. Such changes are costly and time consuming.
Accordingly, it would be advantageous if there was a reconfigurable antenna system including an antenna capable of providing various types of radiation patterns without having to be replaced or needing its orientation changed.
Aspects of the present disclosure are directed to systems and methods for reconfiguring a base station antenna to provide various types of radiation patterns. In one aspect the reconfigurable base station antenna system may include a base station antenna including at least one antenna panel connected to a support structure. Each of the at least one antenna panel includes at least two antenna columns. Each of the at least two antenna columns includes at least one antenna element. A feeder network may be coupled to the at least one antenna panel, and may be configured to cause the base station antenna to form a first quasi-omnidirectional radiation pattern.
In other aspects, the feeder network may be configured to change the first quasi-omnidirectional radiation pattern to another radiation pattern different from the first quasi-omnidirectional radiation pattern.
The following detailed description of the invention will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.
In the drawings;
Certain terminology is used in the following description for convenience only and is not limiting. The words “lower,” “bottom,” “upper” and “top” designate directions in the drawings to which reference is made. Unless specifically set forth herein, the terms “a,” “an” and “the” are not limited to one element, but instead should be read as meaning “at least one.”
The terminology includes the words noted above, derivatives thereof and words of similar import. It should also be understood that the terms “about,” “approximately,” “generally,” “substantially” and like terms, used herein when referring to a dimension or characteristic of a component of the invention, indicate that the described dimension/characteristic is not a strict boundary or parameter and does not exclude minor variations therefrom that are functionally similar. At a minimum, such references that include a numerical parameter would include variations that, using mathematical and industrial principles accepted in the art (e.g., rounding, measurement or other systematic errors, manufacturing tolerances, etc.), would not vary the least significant digit.
Aspects of the present disclosure may be directed to a reconfigurable antenna system including a reconfigurable antenna capable of providing various types of radiation patterns without having to be replaced or needing its orientation changed. The radiation patterns are for the reception and/or transmission of RF signals. The reconfigurable antenna may create various quasi-omnidirectional radiation patterns of different shapes and different types of radiation patterns (e.g., a sector pattern, a peanut shaped pattern, a butterfly pattern, a cardioid, and the like), depending on the environment. For example, the reconfigurable antenna may be able to create a quasi-omnidirectional radiation pattern with one or more shallow nulls, one or more deep nulls, and/or maxima at particular positions. In other cases, it may be desirable to change the type of radiation pattern to another radiation pattern with a predetermined null and/or maximum to potentially increase the throughput in the direction of a maximum and/or reduce interference in the direction of the predetermined null. Further, adjusting the direction of a null may mitigate any passive inter-modulation (PIM) issues if, for example, a PIM source (e.g., a rusty object), is in the direction of strong radiation.
Directions R, V, W represent bisecting directions between respective antenna panels. Based, at least in part, on the fact that amplitudes of overlapping beams (e.g., with axially symmetrical shapes) from some of the antenna elements 1-6 may be nearly equal, deep unwanted nulls may potentially appear in these directions R, V, W. For example, in the directions R, V, W, the traveling length difference ΔL=√3·s. Applied to the configuration of
The corresponding phase difference caused by the offset s may be represented by the following equation:
Phase difference=√3·2π·s/λ
Depending only on s/Δ, deep nulls may appear in directions R, V, W, even at relatively small values of antenna diameter spacing (e.g., D/λ). Table 1 below shows several example cases of offset values and corresponding phase differences in the directions R, V, and W.
As shown above, commonly used half-wavelength spacing s/λ=0.25 of antenna elements may result in a phase difference of 156 degrees. Such a phase difference may result in deep nulls in the directions R, V, and W, in the case of the in-phase feed, and may result in −13.6 dB null depth.
The above-discussed unwanted nulls may be eliminated by applying feed signals of particular phases, according to aspects of the present disclosure.
As reflected in Table 1 above, such a spacing results in a 180 degree phase difference and deep nulls.
To compensate for such nulls in two of the directions, for example, a phase of one of the feed signals, e.g., antenna element 4, may be inverted, which results in the feed vector {0/0, 1/0, 0/0, 1/180, 0/0, 1/0}, being applied. Consequently, as shown in the radiation pattern of
Radiation patterns realized by the reconfigurable antenna may also be affected by the sign of the phase of the feeding signals. For example, when the even-numbered antenna elements are energized (e.g., 2, 4, 6), inverting the sign in the feed vector applied with respect to
which corresponds to a phase difference of 360 degrees.
Quasi-omnidirectional patterns with shallow nulls may even be formed in cases when other than even or odd numbered sets of antenna elements are energized. Such a radiation pattern is shown in
Even though quasi-omnidirectional radiation patterns, such as the various types discussed above with respect to
Referring now to
According to aspects of the present disclosure, other radiation patterns may be realized by energizing all the antenna elements, and for example, using signals of equal amplitudes.
As discussed above, phase differences and radiation patterns may depend, at least in part, on the value D/λ and spacing s/λ As such, assuming that D/λ and spacing s/λ are known, a desired radiation pattern of a circular array of the reconfigurable antenna may be determined for each specific feed vector. For example, through various simulation tools (e.g., Matlab™), a large number of radiation patterns may be simulated by varying the groups of energized antenna elements with varied phases and/or amplitudes of the feed signals of the feed vector. Through these simulations, a large number of radiation patterns may be plotted and stored. Those patterns deemed particularly useful may be selected, categorized, and organized in a lookup table along with their corresponding feed vectors.
Also, as shown in one of the radiation patterns, a corresponding network schematic and feed vector used to realize the radiation pattern is shown. For the sake of simplicity, only one of the radiation patterns is displaying its corresponding network and feed vector. It should be noted that, in the actual look up table, more or all of the remaining radiation patterns may also display corresponding network details and feed vectors.
To create the above-discussed radiation patterns, the feeder network, (e.g., such as the feeder network 16 in
Referring to
Referring to
Referring to
Referring to
According to aspects of the present disclosure, changing a configuration of the radiation pattern may be done by reconnecting one or more different antenna ports to an RF signal or by changing a phase and/or amplitude of one or more signals arriving at the one or more of the antenna ports. Reconnections may be performed manually. For example, a technician or operation at the cell site may physically change one or more hardware connections using individual components, such as power splitters, 90-degree hybrids, 180-degree hybrids, and cables with specified phases (e.g.,
According to other aspects of the present disclosure, reconnections may be performed electronically with RF switches commutating the signals' traveling paths. With electronically performed reconnections, components, such as power splitters, hybrids, and phase shifting circuits, may be printed on a printed circuit board.
Referring now to
Referring now to
Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.
Those of skill would further appreciate that the various illustrative blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The various illustrative blocks described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
Various embodiments of the invention have now been discussed in detail; however, the invention should not be understood as being limited to these embodiments. It should also be appreciated that various modifications, adaptations, and alternative embodiments thereof may be made within the scope and spirit of the present invention.
Number | Name | Date | Kind |
---|---|---|---|
3594798 | Leydorf | Jul 1971 | A |
4687445 | Williams | Aug 1987 | A |
6281849 | Brachat | Aug 2001 | B1 |
6654590 | Boros et al. | Nov 2003 | B2 |
6735182 | Nishimori et al. | May 2004 | B1 |
6894653 | Chiang et al. | May 2005 | B2 |
7031719 | Miyano et al. | Apr 2006 | B2 |
7057573 | Ohira | Jun 2006 | B2 |
7079868 | Guo | Jul 2006 | B2 |
7109929 | Ryken, Jr. et al. | Sep 2006 | B1 |
7203469 | Yamaguchi et al. | Apr 2007 | B2 |
7298332 | Ryken et al. | Nov 2007 | B2 |
7702287 | Kitahara | Apr 2010 | B2 |
8068068 | Kish | Nov 2011 | B2 |
8165595 | Xia et al. | Apr 2012 | B2 |
8290443 | Stirling-Gallacher et al. | Oct 2012 | B2 |
8515493 | Jensen et al. | Aug 2013 | B1 |
8779976 | Eom et al. | Jul 2014 | B2 |
8810465 | Knadle et al. | Aug 2014 | B2 |
8811525 | Eom et al. | Aug 2014 | B2 |
8830133 | Weily et al. | Sep 2014 | B2 |
20050030232 | Monebhurrun | Feb 2005 | A1 |
20050068916 | Jacobsen et al. | Mar 2005 | A1 |
20060128436 | Doi et al. | Jun 2006 | A1 |
20100295728 | Chen | Nov 2010 | A1 |
20130115886 | Khan et al. | May 2013 | A1 |
20130281159 | Ai et al. | Oct 2013 | A1 |
20130300602 | Zhou et al. | Nov 2013 | A1 |
20140354479 | Britz et al. | Dec 2014 | A1 |
Entry |
---|
Harpreet S. Dhillon, “Modeling and Analysis of K-Tier Downlink Heterogeneous Cellular Networks,” IEEE, Dec. 23, 2012, Admitted Prior Art. |
Chapter 20, Antenna Arrays, Admitted Prior Art. |
Constantine A. Balanis, Antenna Theory Analysis and Design, John Wiley & Sons, 2005, Chapter 14-16, pp. 811-999, Admitted Prior Art. |
Number | Date | Country | |
---|---|---|---|
20160285174 A1 | Sep 2016 | US |