U.S. patent application number 16/387082 was filed with the patent office on 2019-08-08 for antenna array beamforming in a remote unit(s) in a wireless distribution system (wds).
The applicant listed for this patent is Corning Optical Communications LLC. Invention is credited to Volker Aue, Albrecht Fehske, Yuval Zinger, Roi Yosy Ziv.
Application Number | 20190245601 16/387082 |
Document ID | / |
Family ID | 61560596 |
Filed Date | 2019-08-08 |
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United States Patent
Application |
20190245601 |
Kind Code |
A1 |
Aue; Volker ; et
al. |
August 8, 2019 |
ANTENNA ARRAY BEAMFORMING IN A REMOTE UNIT(S) IN A WIRELESS
DISTRIBUTION SYSTEM (WDS)
Abstract
Embodiments of the disclosure relate to antenna array
beamforming in a remote unit(s) in a wireless distribution system
(WDS). In this regard, a remote unit in a WDS includes an antenna
array having a plurality of radio frequency (RF) antennas. The RF
antennas transmit a plurality of modified downlink RF signals in a
plurality of phases. A control circuit in the remote unit
determines the phases to cause the RF antennas to transmit a formed
radiation beam(s) in a radiation direction(s). The control circuit
controls a plurality of phase shifters to generate the modified
downlink RF signals in the phases. By supporting antenna array
beamforming in the remote unit, it is possible to steer the formed
radiation beam(s) according to a specific floor layout(s) to
provide enhanced indoor RF coverage in the WDS. As a result, it may
be possible to reduce deployment and/or installation costs of the
WDS.
Inventors: |
Aue; Volker; (Dresden,
DE) ; Fehske; Albrecht; (Dresden, DE) ;
Zinger; Yuval; (Charlotte, NC) ; Ziv; Roi Yosy;
(Ramat Gan, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Corning Optical Communications LLC |
Hickory |
NC |
US |
|
|
Family ID: |
61560596 |
Appl. No.: |
16/387082 |
Filed: |
April 17, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15264024 |
Sep 13, 2016 |
10333599 |
|
|
16387082 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04B 7/0617 20130101;
H04B 7/022 20130101; H04L 5/14 20130101; H04B 7/0413 20130101 |
International
Class: |
H04B 7/06 20060101
H04B007/06; H04B 7/022 20060101 H04B007/022; H04L 5/14 20060101
H04L005/14 |
Claims
1. A wireless distribution system (WDS), comprising: a central
unit; and a plurality of remote units configured to: receive a
plurality of downlink electrical communications signals from the
central unit; and provide a plurality of uplink electrical
communications signals to the central unit; wherein one or more of
the plurality of remote units each comprises: an antenna array
comprising a plurality of radio frequency (RF) antennas configured
to transmit a plurality of modified downlink RF signals in at least
one formed radiation beam in at least one radiation direction; a
plurality of phase shifters configured to: phase-shift a plurality
of downlink RF signals to generate the plurality of modified
downlink RF signals in a plurality of phases, respectively; and
provide the plurality of modified downlink RF signals to the
plurality of RF antennas in the antenna array; and a control
circuit configured to: determine the plurality of phases to cause
the plurality of RF antennas to transmit the plurality of modified
downlink RF signals in the at least one formed radiation beam in
the at least one radiation direction; and control the plurality of
phase shifters to generate the plurality of modified downlink RF
signals in the plurality of phases, respectively.
2. The WDS of claim 1, wherein the antenna array comprises a
plurality of omnidirectional RF antennas configured to transmit the
plurality of modified downlink RF signals in the at least one
formed radiation beam in the at least one radiation direction.
3. The WDS of claim 1, wherein each of the plurality of phase
shifters comprises: a first switched line phase shifter configured
to phase-shift a respective downlink RF signal among the plurality
of downlink RF signals by zero degrees (0.degree.) or one hundred
eighty degrees (180.degree.) to generate a first intermediate
downlink RF signal; a reflective phase shifter configured to
phase-shift the first intermediate downlink RF signal between zero
degrees (0.degree.) and ninety degrees (90.degree.) to generate a
second intermediate downlink RF signal; and a second switched line
phase shifter configured to phase-shift the second intermediate
downlink RF signal by zero degrees (0.degree.) or ninety degrees
(90.degree.) to generate a respective modified downlink RF signal
among the plurality of modified downlink RF signals.
4. The WDS of claim 1, wherein each of the one or more of the
plurality of remote units further comprises: a duplexer circuit
configured to receive a downlink RF communications signal among the
plurality of downlink electrical communications signals
corresponding to one or more downlink communications services and
configured to be transmitted from the remote unit in a
predetermined RF band; and a splitter combiner configured to: split
the downlink RF communications signal into the plurality of
downlink RF signals; and provide the plurality of downlink RF
signals to the plurality of phase shifters, respectively.
5. The WDS of claim 4, wherein: the plurality of RF antennas is
further configured to receive a plurality of modified uplink RF
signals, respectively; the plurality of phase shifters is further
configured to generate a plurality of uplink RF signals based on
the plurality of modified uplink RF signals, respectively; and the
splitter combiner is further configured to: combine the plurality
of uplink RF signals to generate an uplink RF communications signal
associated with one or more uplink communications services; and
provide the uplink RF communications signal to the duplexer circuit
to be transmitted to the central unit among the plurality of uplink
electrical communications signals.
6. The WDS of claim 4, wherein: X first RF antennas selected from
the plurality of RF antennas are disposed uniformly on a first
line, wherein each of the X first RF antennas is separated from an
immediately adjacent first RF antenna by a predetermined distance;
and X-1 second RF antennas selected from the plurality of RF
antennas are disposed uniformly on a second line located
immediately adjacent to the first line and separated from the first
line by a line separation distance, wherein each of the X-1 second
RF antennas is separated from an immediately adjacent second RF
antenna by the predetermined distance, wherein X is an integer
variable.
7. The WDS of claim 6, wherein: X-1 third RF antennas selected from
the plurality of RF antennas are disposed uniformly on a third line
located immediately adjacent to the first line and separated from
the first line by the line separation distance, wherein each of the
X-1 third RF antennas is separated from an immediately adjacent
third RF antenna by the predetermined distance; X-2 fourth RF
antennas selected from the plurality of RF antennas are disposed
uniformly on a fourth line located immediately adjacent to the
second line and separated from the second line by the line
separation distance, wherein each of the X-2 fourth RF antennas is
separated from an immediately adjacent fourth RF antenna by the
predetermined distance; and X-2 fifth RF antennas selected from the
plurality of RF antennas are disposed uniformly on a fifth line
located immediately adjacent to the third line and separated from
the third line by the line separation distance, wherein each of the
X-2 fifth RF antennas is separated from an immediately adjacent
fifth RF antenna by the predetermined distance.
8. The WDS of claim 7, wherein the predetermined distance equals
one-half of a wavelength of a center frequency of the predetermined
RF band.
9. The WDS of claim 4, wherein: the antenna array comprises
nineteen RF antennas configured to transmit nineteen modified
downlink RF signals in the at least one formed radiation beam in
the at least one radiation direction; the plurality of phase
shifters comprises nineteen phase shifters configured to:
phase-shift nineteen downlink RF signals to generate the nineteen
modified downlink RF signals in nineteen phases, respectively; and
provide the nineteen modified downlink RF signals to the nineteen
RF antennas in the antenna array; and the control circuit is
configured to: determine the nineteen phases to cause the nineteen
RF antennas to transmit the nineteen modified downlink RF signals
in the at least one formed radiation beam in the at least one
radiation direction; and control the nineteen phase shifters to
generate the nineteen modified downlink RF signals in the nineteen
phases, respectively.
10. The WDS of claim 9, wherein the splitter combiner comprises: a
first three-way splitter configured to split the downlink RF
communications signal having a determined power level to generate
three first downlink RF signals, each having one-third of the
determined power level; three second two-way splitters each
configured to split the three first downlink RF signals to generate
nine second downlink RF signals, each having one-ninth of the
determined power level; eight two-way splitters configured to split
eight of the nine second downlink RF signals to generate sixteen of
the nineteen downlink RF signals, each having one-eighteenth (of
the determined power level; and a third three-way splitter
configured to split one of the nine second downlink RF signals to
generate three of the nineteen downlink RF signals, each having
one-twenty-seventh of the determined power level.
11. The WDS of claim 10, wherein the nineteen RF antennas in the
antenna array are disposed in a circular-shaped area.
12. The WDS of claim 11, wherein: one first selected RF antenna
among the nineteen RF antennas is disposed at a center point of the
circular-shaped area; six second selected RF antennas among the
nineteen RF antennas are disposed respectively at six first
vertices of a first regular hexagon having a first radius extending
from the center point of the circular-shaped area; six third
selected RF antennas among the nineteen RF antennas are disposed
respectively at six second vertices of a second regular hexagon
having a second radius extending from the center point of the
circular-shaped area, wherein the second radius equals two times
the first radius; and six fourth selected RF antennas among the
nineteen RF antennas are disposed respectively at six respective
midpoints of six sides of the second regular hexagon.
13. The WDS of claim 12, wherein three of the six second selected
RF antennas disposed at the six first vertices of the first regular
hexagon are configured to receive the three downlink RF signals
having the one-twenty-seventh of the determined power level.
14. The WDS of claim 12, wherein: the nineteen RF antennas are
configured to transmit the nineteen modified downlink RF signals in
the predetermined RF band; and the first radius of the first
regular hexagon equals one-half of a wavelength of a center
frequency of the predetermined RF band.
15. The WDS of claim 14, wherein each of the one or more of the
plurality of remote units further comprises a second RF antenna
configured to: transmit a second downlink RF communications signal
in a second predetermined RF band located in a lower frequency
spectrum than the predetermined RF band; and receive a second
uplink RF communications signal in the second predetermined RF
band.
16. The WDS of claim 14, wherein each of the one or more of the
plurality of remote units further comprises: a plurality of second
phase shifters configured to phase-shift a plurality of second
downlink RF signals to generate a plurality of second modified
downlink RF signals in a plurality of second phases, respectively;
a second splitter combiner configured to: split a second downlink
RF communications signal into the plurality of second downlink RF
signals; and provide the plurality of second downlink RF signals to
the plurality of second phase shifters, respectively; and a
plurality of multiple-input multiple-output (MIMO) splitter
combiners configured to: receive the plurality of modified downlink
RF signals from the plurality of phase shifters, respectively;
receive the plurality of second modified downlink RF signals from
the plurality of second phase shifters, respectively; generate a
plurality of downlink MIMO signals based on the plurality of
modified downlink RF signals and the plurality of second modified
downlink RF signals, respectively; and provide the plurality of
downlink MIMO signals to the plurality of RF antennas in the
antenna array.
17. The WDS of claim 2, wherein the central unit comprises: an
electrical-to-optical (E/O) converter configured to convert the
plurality of downlink electrical communications signals into a
plurality of downlink optical fiber-based communications signals,
respectively; and an optical-to-electrical (O/E) converter
configured to convert a plurality of uplink optical fiber-based
communications signals into the plurality of uplink electrical
communications signals, respectively.
18. The WDS of claim 17, wherein the plurality of remote units
comprises: a plurality of remote unit O/E converters configured to
convert the plurality of downlink optical fiber-based
communications signals into the plurality of downlink electrical
communications signals, respectively; and a plurality of remote
unit E/O converters configured to convert the plurality of uplink
electrical communications signals into the plurality of uplink
optical fiber-based communications signals, respectively.
19. The WDS of claim 1, wherein the central unit comprises: an
electrical-to-optical (E/O) converter configured to convert the
plurality of downlink electrical communications signals into a
plurality of downlink optical fiber-based communications signals,
respectively; and an optical-to-electrical (O/E) converter
configured to convert a plurality of uplink optical fiber-based
communications signals into the plurality of uplink electrical
communications signals, respectively.
20. The WDS of claim 19, the plurality of remote units comprises: a
plurality of remote unit O/E converters configured to convert the
plurality of downlink optical fiber-based communications signals
into the plurality of downlink electrical communications signals,
respectively; and a plurality of remote unit E/O converters
configured to convert the plurality of uplink electrical
communications signals into the plurality of uplink optical
fiber-based communications signals, respectively.
Description
PRIORITY APPLICATION
[0001] This application is a continuation of U.S. application Ser.
No. 15/264,024, filed Sep. 13, 2016, the entire contents of which
being hereby incorporated by reference.
BACKGROUND
[0002] The disclosure relates generally to a wireless distribution
system (WDS) and more particularly to techniques for supporting
antenna array beamforming in a remote unit(s) in a WDS.
[0003] Wireless customers are increasingly demanding digital data
services, such as streaming video signals. At the same time, some
wireless customers use their wireless communications devices in
areas that are poorly serviced by conventional cellular networks,
such as inside certain buildings or areas where there is little
cellular coverage. One response to the intersection of these two
concerns has been the use of distributed antenna systems (DASs).
DASs include remote units configured to receive and transmit
communications signals to client devices within the antenna range
of the remote units. DASs can be particularly useful when deployed
inside buildings or other indoor environments where the wireless
communications devices may not otherwise be able to effectively
receive radio frequency (RF) signals from a signal source.
[0004] In this regard, FIG. 1 illustrates distribution of
communication services to remote coverage areas 100(1)-100(N) of a
WDS 102 provided in the form of a DAS, wherein `N` is the number of
remote coverage areas. These communication services can include
cellular services, wireless services, such as radio frequency
identification (RFID) tracking, Wireless Fidelity (Wi-Fi), local
area network (LAN), wireless LAN (WLAN), wireless solutions
(Bluetooth, Wi-Fi Global Positioning System (GPS) signal-based, and
others) for location-based services, and combinations thereof, as
examples. The remote coverage areas 100(1)-100(N) may be remotely
located. In this regard, the remote coverage areas 100(1)-100(N)
are created by and centered on remote antenna units (RAUs)
104(1)-104(N) connected to a head-end equipment (HEE) 106 (e.g., a
head-end controller, a head-end unit (HEU), or a central unit). The
HEE 106 may be communicatively coupled to a signal source 108, for
example, a base transceiver station (BTS) or a baseband unit (BBU).
In this regard, the HEE 106 receives downlink communications
signals 110D from the signal source 108 to be distributed to the
RAUs 104(1)-104(N). The RAUs 104(1)-104(N) are configured to
receive the downlink communications signals 110D from the HEE 106
over a communications medium 112 to be distributed to the
respective remote coverage areas 100(1)-100(N) of the RAUs
104(1)-104(N). In a non-limiting example, the communications medium
112 may be a wired communications medium, a wireless communications
medium, or an optical fiber-based communications medium. Each of
the RAUs 104(1)-104(N) may include an RF transmitter/receiver and a
respective antenna 114(1)-114(N) operably connected to the RF
transmitter/receiver to wirelessly distribute the communication
services to client devices 116 within the respective remote
coverage areas 100(1)-100(N). The RAUs 104(1)-104(N) are also
configured to receive uplink communications signals 110U from the
client devices 116 in the respective remote coverage areas
100(1)-100(N) to be distributed to the signal source 108. The size
of each of the remote coverage areas 100(1)-100(N) is determined by
the amount of RF power transmitted by the respective RAUs
104(1)-104(N), receiver sensitivity, antenna gain, and RF
environment, as well as by RF transmitter/receiver sensitivity of
the client devices 116. The client devices 116 usually have a fixed
maximum RF receiver sensitivity, so that the above-mentioned
properties of the RAUs 104(1)-104(N) mainly determine the size of
the respective remote coverage areas 100(1)-100(N).
[0005] Each of the antennas 114(1)-114(N) may be provided as an
omnidirectional antenna, which provides equal radiation to three
hundred sixty degrees (360.degree.) around the antenna in the
horizontal plan. In this regard, an omnidirectional antenna is
well-suited to provide RF coverage in a circular-shaped coverage
area. However, an omnidirectional antenna may not be particularly
effective in providing effective RF coverage in such indoor areas
that include irregularly shaped areas, such as hallways,
rectangular-shaped rooms, and irregular-shaped offices. Further, it
may be particularly difficult to provide effective RF coverage at
endpoints in these indoor areas, such near exterior windows and
corners where an RF coverage area may not reach, or only reach if
the RF coverage area is boosted, which may then overextend the RF
coverage area outside the indoor area in an unintended manner. For
example, extending a WDS RF coverage area outside an intended
indoor area may cause outdoor client devices to be within indoor RF
coverage areas in an unintended manner. In this regard, it may be
desirable to effectively control directional radiation patterns of
the antennas 114(1)-114(N) to meet specific coverage requirements
of the client devices 116 located at certain endpoints in the
respective remote coverage areas 100(1)-100(N), especially when the
respective remote coverage areas 100(1)-100(N) are not
circular-shaped.
[0006] No admission is made that any reference cited herein
constitutes prior art. Applicant expressly reserves the right to
challenge the accuracy and pertinency of any cited documents.
SUMMARY
[0007] Embodiments of the disclosure relate to antenna array
beamforming in a remote unit(s) in a wireless distribution system
(WDS). By supporting antenna array beamforming in a remote unit, it
is possible to steer a formed radiation beam according to a
specific floor layout(s) to provide enhanced indoor radio frequency
(RF) coverage in the WDS. As a result, it may be possible to reduce
deployment and/or installation costs of the WDS and provide
additional opportunities for supporting more advanced applications
in the WDS. In this regard, at least one remote unit in a WDS
includes an antenna array having a plurality of RF antennas (e.g.,
omnidirectional antennas). The RF antennas are configured to
transmit a plurality of modified downlink RF signals in a plurality
of phases. A control circuit in the remote unit(s) is configured to
determine the phases for the modified downlink RF signals to cause
the RF antennas to transmit at least one formed radiation beam in
at least one radiation direction. The control circuit is further
configured to control a plurality of phase shifters to generate the
modified downlink RF signals in the phases determined by the
control circuit.
[0008] In one embodiment, a remote unit in a WDS is provided. The
remote unit includes an antenna array comprising a plurality of RF
antennas configured to transmit a plurality of modified downlink RF
signals in at least one formed radiation beam in at least one
radiation direction. The remote unit also includes a plurality of
phase shifters. The plurality of phase shifters is configured to
phase-shift a plurality of downlink RF signals to generate the
plurality of modified downlink RF signals in a plurality of phases,
respectively. The plurality of phase shifters is also configured to
provide the plurality of modified downlink RF signals to the
plurality of RF antennas in the antenna array. The remote unit also
includes a control circuit. The control circuit is configured to
determine the plurality of phases to cause the plurality of RF
antennas to transmit the plurality of modified downlink RF signals
in the at least one formed radiation beam in the at least one
radiation direction. The control circuit is also configured to
control the plurality of phase shifters to generate the plurality
of modified downlink RF signals in the plurality of phases,
respectively.
[0009] In another embodiment, a method for supporting antenna array
beamforming in a remote unit in a WDS is provided. The method
includes determining a plurality of phases to cause a plurality of
RF antennas in an antenna array in the remote unit to transmit a
plurality of modified downlink RF signals in at least one formed
radiation beam in at least one radiation direction. The method also
includes phase-shifting a plurality of downlink RF signals to
generate the plurality of modified downlink RF signals in the
plurality of phases, respectively. The method also includes
providing the plurality of modified downlink RF signals to the
plurality of RF antennas in the antenna array. The method also
includes transmitting the plurality of modified downlink RF signals
from the plurality of RF antennas in the at least one formed
radiation beam in the at least one radiation direction.
[0010] In another embodiment, a WDS is provided. The WDS includes a
central unit and a plurality of remote units. The plurality of
remote units is configured to receive a plurality of downlink
electrical communications signals from the central unit. The
plurality of remote units is also configured to provide a plurality
of uplink electrical communications signals to the central unit.
One or more of the plurality of remote units includes an antenna
array comprising a plurality of RF antennas configured to transmit
a plurality of modified downlink RF signals in at least one formed
radiation beam in at least one radiation direction. One or more of
the plurality of remote units also includes a plurality of phase
shifters. The plurality of phase shifters is configured to
phase-shift a plurality of downlink RF signals to generate the
plurality of modified downlink RF signals in a plurality of phases,
respectively. The plurality of phase shifters is also configured to
provide the plurality of modified downlink RF signals to the
plurality of RF antennas in the antenna array. One or more of the
plurality of remote units also includes a control circuit. The
control circuit is configured to determine the plurality of phases
to cause the plurality of RF antennas to transmit the plurality of
modified downlink RF signals in the at least one formed radiation
beam in the at least one radiation direction. The control circuit
is also configured to control the plurality of phase shifters to
generate the plurality of modified downlink RF signals in the
plurality of phases, respectively.
[0011] Additional features and advantages will be set forth in the
detailed description which follows, and in part will be readily
apparent to those skilled in the art from the description or
recognized by practicing the embodiments as described in the
written description and claims hereof, as well as the appended
drawings.
[0012] It is to be understood that both the foregoing general
description and the following detailed description are merely
exemplary, and are intended to provide an overview or framework to
understand the nature and character of the claims.
[0013] The accompanying drawings are included to provide a further
understanding, and are incorporated in and constitute a part of
this specification. The drawings illustrate one or more
embodiments, and together with the description serve to explain
principles and operation of the various embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a schematic diagram of an exemplary wireless
distribution system (WDS);
[0015] FIGS. 2A and 2B are schematic diagrams providing exemplary
illustrations of vertical and horizontal views of a radiation
pattern of an omnidirectional antenna, respectively;
[0016] FIG. 3A is a schematic diagram of an exemplary antenna array
configured to transmit a formed radiation beam in a radiation
direction based on antenna array beamforming techniques;
[0017] FIG. 3B is a schematic diagram providing an exemplary
illustration of the antenna array of FIG. 3A configured to transmit
a formed radiation beam in a radiation direction that is different
from the radiation direction of FIG. 3A;
[0018] FIG. 4 is a schematic diagram of an exemplary remote unit in
a wireless distribution system (WDS) having an antenna array
configured to provide enhanced radio frequency (RF) coverage in the
WDS via antenna array beamforming;
[0019] FIG. 5 is a flowchart of an exemplary process that can be
employed by the remote unit of FIG. 4 for supporting antenna array
beamforming in the WDS;
[0020] FIG. 6A is a schematic diagram of an exemplary phase shifter
that can be provided in the remote unit of FIG. 4 to generate a
three-hundred-sixty-degree (360.degree.) phase shift;
[0021] FIG. 6B is a schematic diagram of an exemplary switched line
phase shifter that can be provided in the phase shifter of FIG. 6A
to provide a larger phase shift with coarse resolution;
[0022] FIG. 6C is a schematic diagram of an exemplary reflective
phase shifter that can be provided in the phase shifter of FIG. 6A
to provide a smaller phase shift with fine resolution;
[0023] FIG. 7 is a schematic diagram providing an exemplary
illustration of a one-to-nineteen (1:19) splitter combiner
configured to split a downlink RF communications signal into
nineteen (19) downlink RF signals;
[0024] FIG. 8 is a schematic diagram of an exemplary antenna array
including nineteen (19) RF antennas disposed in a circular-shaped
area;
[0025] FIG. 9 is a schematic diagram of an exemplary elevation
pattern of a formed radiation beam when the remote unit of FIG. 4
is mounted on a ceiling of a building.
[0026] FIG. 10 is a schematic diagram of an exemplary remote unit
including the antenna array of FIG. 4 for supporting antenna array
beamforming in a higher frequency band and a second RF antenna for
transmitting a second downlink RF communications signal in a lower
frequency band;
[0027] FIG. 11A is a schematic diagram of an exemplary remote unit
configured to support concurrent multiple-input multiple-output
(MIMO) and antenna array beamforming operations;
[0028] FIG. 11B is a schematic diagram providing an exemplary
illustration of a first formed radiation beam and a second formed
radiation beam transmitted from an antenna array in the remote unit
of FIG. 11A;
[0029] FIG. 12 is a schematic diagram of an exemplary WDS provided
in the form of a distributed antenna system (DAS) that can include
one or more remote units that support antenna array beamforming,
including but not limited to the remote units of FIGS. 4, 10, and
11A;
[0030] FIG. 13 is a partial schematic cut-away diagram of an
exemplary building infrastructure in which the WDS of FIG. 12 can
be provided; and
[0031] FIG. 14 is a schematic diagram representation of additional
detail illustrating an exemplary computer system that could be
employed in a control circuit, including a control circuit in the
remote units of FIGS. 4 and 10 for instructing the passive
beamforming network to support antenna array beamforming.
DETAILED DESCRIPTION
[0032] Embodiments of the disclosure relate to antenna array
beamforming in a remote unit(s) in a wireless distribution system
(WDS). By supporting antenna array beamforming in a remote unit, it
is possible to steer a formed radiation beam according to a
specific floor layout(s) to provide enhanced indoor radio frequency
(RF) coverage in the WDS. As a result, it may be possible to reduce
deployment and/or installation costs of the WDS and provide
additional opportunities for supporting more advanced applications
in the WDS. In this regard, at least one remote unit in a WDS
includes an antenna array having a plurality of RF antennas (e.g.,
omnidirectional antennas). The RF antennas are configured to
transmit a plurality of modified downlink RF signals in a plurality
of phases. A control circuit in the remote unit(s) is configured to
determine the phases for the modified downlink RF signals to cause
the RF antennas to transmit at least one formed radiation beam in
at least one radiation direction. The control circuit is further
configured to control a plurality of phase shifters to generate the
modified downlink RF signals in the phases determined by the
control circuit.
[0033] Before discussing exemplary aspects of supporting
beamforming in a remote unit(s) in a WDS that includes specific
exemplary aspects of the present disclosure starting at FIGS. 3A
and 3B, a brief overview of radiation patterns of omnidirectional
antennas are first provided in FIGS. 2A and 2B.
[0034] In this regard, FIGS. 2A and 2B are schematic diagrams
providing exemplary illustrations of vertical and horizontal views
of a radiation pattern 200 of an omnidirectional antenna 202,
respectively. As illustrated in FIGS. 2A and 2B, the
omnidirectional antenna 202 spreads RF energy uniformly in a sphere
204. According to the vertical view of the radiation pattern 200 in
FIG. 2A, the omnidirectional antenna 202 may have some directivity
towards a ground 206. As such, the omnidirectional antenna 202 may
generate an elevation gain toward the ground 206. However,
according to the horizontal view of FIG. 2B, the omnidirectional
antenna 202 has no directivity and, thus, provides zero
decibels-isotropic (0 dBi) gain.
[0035] Because the omnidirectional antenna 202 spreads RF energy
uniformly in the sphere 204, the omnidirectional antenna 202 may be
suited to providing RF coverage in a circular-shaped indoor
coverage area. However, the omnidirectional antenna 202 may not
provide desired RF coverage in such indoor coverage areas that
require the RF energy to be concentrated in a specific direction(s)
or in non-circular shaped areas, as opposed to being spread
uniformly around the omnidirectional antenna 202. In a non-liming
example, an RF coverage area in a building can be a long, narrow
hallway (e.g., length is significantly greater than width).
Accordingly, it may be desirable to direct the RF energy to
sufficiently cover the entire length of the hallway. In other
words, more RF energy is preferentially directed along the length
of the hallway than along the width of the hallway. In this regard,
if the omnidirectional antenna 202 is configured to cover the
entire length of the hallway, the omnidirectional antenna 202 will
generate excessive RF energy along the width of the hallway. As a
result, the RF energy radiated along the width of the hallway may
be absorbed by walls of the hallway. Moreover, the excessive RF
energy radiated along the width of the hallway may cause
interference to adjacent coverage areas. As such, it may be
desirable to utilize antenna array beamforming techniques to direct
the RF energy along the length of the hallway, while suppressing RF
energy along the width of the hallway.
[0036] Thus, in exemplary embodiments herein discussed in more
detail below, WDSs and related components are provided that support
antenna array beamforming in a remote unit(s). In this regard, FIG.
3A is a schematic diagram of an exemplary antenna array 300 that
can be provided in a remote unit in a WDS. The antenna array 300 is
configured to transmit a formed radiation beam 302 in a radiation
direction 304 based on antenna array beamforming techniques. With
reference to FIG. 3A, the antenna array 300 includes a plurality of
RF antennas 306(1)-306(M), which may be omnidirectional antennas
for example. The RF antennas 306(1)-306(M) receive and transmit a
plurality of RF signals 308(1)-308(M), respectively. To generate
the formed radiation beam 302 (also known as "beamforming") from
the antenna array 300, a beamforming network 310 is configured to
manipulate respective phases .theta..sub.1-.theta..sub.M of the RF
signals 308(1)-308(M) that are fed to the RF antennas
306(1)-306(M). When the respective phases
.theta..sub.1-.theta..sub.M of the RF signals 308(1)-308(M) are
substantially similar, the RF signals 308(1)-308(M) can be
constructively combined to generate the formed radiation beam 302
having an effective radiation beam 312 reinforced in the radiation
direction 304 and suppressed in radiation directions other than the
radiation direction 304. In this regard, the radiation direction
304 can be directed along the length of the long, narrow hallway in
the building. In a non-limiting example, the beamforming network
310 can be configured to include such passive components as
splitter combiner(s) and phase shifter(s). Accordingly, the
beamforming network 310 can be referred to as a passive beamforming
network 310.
[0037] In a non-limiting example, the effective radiation beam 312
of the RF antennas 306(1)-306(M) can be configured to be
substantially parallel to an orientation 314 of the RF antennas
306(1)-306(M). In this regard, the passive beamforming network 310
manipulates the respective phases .theta..sub.1-.theta..sub.M of
the RF signals 308(1)-308(M) to be substantially aligned with the
orientation 314 (e.g., with a zero-degree (0.degree.) phase shift).
In one non-limiting example, the passive beamforming network 310
can further configure respective amplitudes A.sub.1-A.sub.M of the
RF antennas 306(1)-306(M) to be substantially similar. In another
non-limiting example, it is also possible to configure selective
respective amplitudes A.sub.1-A.sub.M of the RF antennas
306(1)-306(M) to be smaller than the rest of the respective
amplitudes A.sub.1-A.sub.M. As a result, the passive beamforming
network 310 can control the RF antennas 306(1)-306(M) to generate
the effective radiation beam 312 that is substantially parallel to
the orientation 314 of the RF antennas 306(1)-306(M).
[0038] The effective radiation beam 312 can also be directed to
different radiation directions without changing the orientation 314
of the RF antennas 306(1)-306(M). In this regard, FIG. 3B is a
schematic diagram providing an exemplary illustration of the
antenna array 300 of FIG. 3A configured to transmit a formed
radiation beam 302' in a radiation direction 304' that is different
from the radiation direction 304 of FIG. 3A. Common elements
between FIGS. 3A and 3B are shown therein with common element
numbers and will not be re-described herein.
[0039] With reference to FIG. 3B, in a non-limiting example, the
passive beamforming network 310 changes the respective phases
.theta..sub.1-.theta..sub.M of the RF signals 308(1)-308(M) to be
substantially equal to forty-five degrees (45.degree.). The
beamforming network 310 may also configure the respective
amplitudes A.sub.1-A.sub.M of the RF signals 308(1)-308(M) in
ascending magnitudes (A.sub.1<A.sub.2< . . . A.sub.M). As a
result, the passive beamforming network 310 can steer the effective
radiation beam 312 of the RF antennas 306(1)-306(M) in the
radiation direction 304', which is different from the radiation
direction 304 by approximately 45.degree., for example. Hence, by
controlling the respective phases .theta..sub.1-.theta..sub.M
and/or the respective amplitudes A.sub.1-A.sub.M of the RF signals
308(1)-308(M), it is possible to steer the effective radiation beam
312 to a desired direction without changing the orientation 314 of
the RF antennas 306(1)-306(M).
[0040] The antenna array 300 and the passive beamforming network
310 can be provided in a remote unit in a WDS to help improve RF
coverage in such indoor coverage areas such as a long, narrow
hallway by steering the effective radiation beam 312 of the antenna
array 300 along the length of the hallway. In this regard, FIG. 4
is a schematic diagram of an exemplary remote unit 400 having an
antenna array 402 configured to provide enhanced RF coverage in a
WDS 404 via antenna array beamforming. The antenna array 402
includes a plurality of RF antennas 406(1)-406(N), which may be
omnidirectional RF antennas such as monopole antennas for example.
The RF antennas 406(1)-406(N) are configured to transmit a
plurality of modified downlink RF signals 408(1)-408(N),
respectively. The RF antennas 406(1)-406(N) are coupled to a
passive beamforming network 410, which includes a plurality of
phase shifters 412(1)-412(N) and a splitter combiner 414. The
passive beamforming network 410 is reciprocal in phases and losses
in this example. As such, the passive beamforming network 410 has a
forward voltage gain S.sub.21 that is substantially equal to a
reverse voltage gain S.sub.12 (S.sub.21=S.sub.12) in this example.
Accordingly, the passive beamforming network 410 can be provided in
both downlink and uplink paths of the remote unit 400.
[0041] With continuing reference to FIG. 4, the splitter combiner
414 is configured to split a downlink RF communications signal 416
into a plurality of downlink RF signals 418(1)-418(N). The phase
shifters 412(1)-412(N) are configured to phase-shift the downlink
RF signals 418(1)-418(N) to generate the modified downlink RF
signals 408(1)-408(N) in a plurality of phases
.theta..sub.1-.theta..sub.N, respectively. The remote unit 400
includes a control circuit 420, which may be a microprocessor or a
microcontroller as non-limiting examples. The control circuit 420
is configured to determine the phases .theta..sub.1-.theta..sub.N
to cause the RF antennas 406(1)-406(N) to transmit the modified
downlink RF signals 408(1)-408(N) in at least one formed radiation
beam 422, such as the formed radiation beam 302 of FIG. 3A or the
formed radiation beam 302' of FIG. 3B. In a non-limiting example,
the formed radiation beam 422 is a main radiation lobe of the
antenna array 402. The phases .theta..sub.1-.theta..sub.N are so
determined to cause the modified downlink RF signals 408(1)-408(N)
to be constructively combined at the antenna array 402 to transmit
the formed radiation beam 422. Further, the phases
.theta..sub.1-.theta..sub.N are so determined to cause the antenna
array 402 to transmit the formed radiation beam 422 in at least one
radiation direction 424. In a non-limiting example, the formed
radiation beam 422 is substantially similar to the effective
radiation beam 312 of FIGS. 3A and 3B. Likewise, the radiation
direction 424 is substantially similar to the radiation direction
304 of FIG. 3A or the radiation direction 304' of FIG. 3B. The
control circuit 420 controls the phase shifters 412(1)-412(N) in
the passive beamforming network 410 to generate the modified
downlink RF signals 408(1)-408(N) in the phases
.theta..sub.1-.theta..sub.N, respectively. The phase shifters
412(1)-412(N) in turn provide the modified downlink RF signals
408(1)-408(N) to the RF antennas 406(1)-406(N).
[0042] According to previous discussions in FIGS. 3A and 3B, the
passive beamforming network 410 can manipulate the phases
.theta..sub.1-.theta..sub.N and/or amplitudes in the modified
downlink RF signals 408(1)-408(N) to steer the radiation direction
424 without changing physical orientations of the RF antennas
406(1)-406(N). By controlling the respective phases
.theta..sub.1-.theta..sub.N of the modified downlink RF signals
408(1)-408(N), it is possible to transmit the formed radiation beam
422 from the antenna array 402 with higher directivity in the
radiation direction 424. As a result, the remote unit 400 can be
configured to improve RF coverage in such indoor coverage areas as
the long, narrow hallway referenced in FIG. 2 by steering the
formed radiation beam 422 along the length of the hallway. In this
regard, it may be possible to adapt the formed radiation beam 422
according to specific floor layout(s) to provide enhanced indoor RF
coverage in an entire building(s). As a result, it may be possible
to reduce deployment and/or installation costs of the WDS 404.
Further, by configuring the remote unit 400 to support antenna
array beamforming, it may be possible to provide additional
opportunities for supporting more advanced applications in the WDS
404.
[0043] The remote unit 400 can be configured to support antenna
array beamforming according to a process. In this regard, FIG. 5 is
a flowchart of an exemplary process 500 that can be employed by the
remote unit 400 of FIG. 4 for supporting antenna array beamforming
in the WDS 404.
[0044] With reference to FIG. 5, the control circuit 420 is
configured to determine the phases .theta..sub.1-.theta..sub.N to
cause the RF antennas 406(1)-406(N) in the antenna array 402 in the
remote unit 400 to transmit the modified downlink RF signals
408(1)-408(N) in the formed radiation beam 422 in the radiation
direction 424 (block 502). The phase shifters 412(1)-412(N) are
controlled by the control circuit 420 to phase-shift the downlink
RF signals 418(1)-418(N) to generate the modified downlink RF
signals 408(1)-408(N) in the phases .theta..sub.1-.theta..sub.N,
respectively (block 504). The phase shifters 412(1)-412(N) then
provide the modified downlink RF signals 408(1)-408(N) to the RF
antennas 406(1)-406(N) (block 506). The RF antennas 406(1)-406(N)
transmit the modified downlink RF signals 408(1)-408(N) in the
formed radiation beam 422 in the radiation direction 424 (block
508).
[0045] With reference back to FIG. 4, the remote unit 400 includes
a duplexer circuit 426. The duplexer circuit 426 is configured to
receive the downlink RF communications signal 416. The downlink RF
communications signal 416 corresponds to one or more downlink
communications services 428(1)-428(L). In a non-limiting example,
the downlink communications services 428(1)-428(L) include an
Advanced Wireless Services (AWS) service(s) and a Personal
Communications Service (PCS) service(s). The antenna array 402 is
configured to transmit the downlink RF communications signal 416 in
a predetermined RF band. In a non-limiting example, the
predetermined RF band occupies an RF spectrum between 1710
megahertz (MHz) and 2180 MHz. In this regard, the predetermined RF
band has a center frequency of 1945 MHz.
[0046] In a non-limiting example, the remote unit 400 receives a
downlink digital communications signal from central unit. In this
regard, the remote unit 400 may include a digital-to-analog
converter (DAC) to convert the downlink digital communications
signal into the downlink RF communications signal 416 before
providing the downlink RF communications signal 416 to the duplexer
circuit 426. In this regard, the remote unit 400 is a digital
remote unit. In another non-limiting example, the remote unit 400
receives the downlink RF communications signal 416 from the central
unit. Accordingly, the remote unit 400 would be an analog remote
unit. It shall be appreciated that the remote unit 400 can be
configured to support antenna array beamforming regardless of
whether the remote unit 400 is a digital or an analog remote
unit.
[0047] With continuing reference to FIG. 4, the downlink RF
communications signal 416 has a determined power level P.sub.S. The
splitter combiner 414 is configured to split the determined power
level P.sub.S into a plurality of power levels P.sub.1-P.sub.N and
associate the power levels P.sub.1-P.sub.N with the downlink RF
signals 418(1)-418(N), respectively. A non-limiting example of the
splitter combiner 414 is further discussed with reference to FIG. 7
later in this disclosure.
[0048] As previously discussed, the passive beamforming network 410
is reciprocal in phases and losses. Accordingly, the passive
beamforming network 410 can be provided in both downlink and uplink
paths of the remote unit 400. In this regard, the RF antennas
406(1)-406(N) are configured to receive a plurality of modified
uplink RF signals 430(1)-430(N), respectively. The phase shifters
412(1)-412(N) are configured to generate a plurality of uplink RF
signals 432(1)-432(N) based on the modified uplink RF signals
430(1)-430(N), respectively. The splitter combiner 414 is
configured to combine the uplink RF signals 432(1)-432(N) to
generate an uplink RF communications signal 434, which may include
one or more uplink communications services 436(1)-436(K). The
splitter combiner 414 provides the uplink RF communications signal
434 to the duplexer circuit 426. The remote unit 400 may include an
analog-to-digital converter (ADC) (not shown) for converting the
uplink RF communications signal 434 into an uplink digital
communications signal (not shown) before providing the uplink
digital communications signal to the central unit.
[0049] With continuing reference to FIG. 4, each of the phase
shifters 412(1)-412(N) is a three-hundred-sixty-degree
(360.degree.) phase shifter that includes a combination of switched
line phase shifter(s) and a reflective shifter. An example of the
phase shifter 412(1) is illustrated and discussed next with
reference to FIGS. 6A-6C as a non-limiting example.
[0050] In this regard, FIG. 6A is a schematic diagram providing an
exemplary illustration of the phase shifter 412(1) of FIG. 4 that
can be provided in the remote unit 400 to generate a 360.degree.
phase shift. The phase shifter 412(1) includes a first switched
line phase shifter 600, a reflective phase shifter 602, and a
second switched line phase shifter 604 disposed in a cascading
arrangement. The first switched line phase shifter 600 and the
second switched line phase shifter 604 are configured to provide
larger phase shifts (e.g., one-hundred-eighty-degree (180.degree.)
by the first switched line phase shifter 600 and ninety-degree
(90.degree.) by the second switched line phase shifter 604) phase
shifts with coarse resolution. The reflective phase shifter 602 is
configured to provide a smaller phase shift (e.g., less than
90.degree. phase shift) with fine resolution. As is further
discussed later, each of the first switched line phase shifter 600,
the reflective phase shifter 602, and the second switched line
phase shifter 604 can be digitally controlled (e.g., based on
digital words) to generate a desired phase shift.
[0051] The first switched line phase shifter 600 is configured to
phase-shift the downlink RF signal 418(1) by either zero degrees
(0.degree.) or 180.degree. to generate a first intermediate
downlink RF signal 606. The reflective phase shifter 602 is
configured to phase-shift the first intermediate downlink RF signal
606 between 0.degree. and 90.degree. to generate a second
intermediate downlink RF signal 608. The second switched line phase
shifter 604 is configured to phase-shift the second intermediate
downlink RF signal 608 by 0.degree. or 90.degree. to generate the
modified downlink RF signal 408(1). Hence, by cascading the first
switched line phase shifter 600, the reflective phase shifter 602,
and the second switched line phase shifter 604, the phase shifter
412(1) can phase-shift the downlink RF signal 418(1) (e.g., in
increments of three degrees)(3.degree.) up to 360.degree..
[0052] FIG. 6B is a schematic diagram of an exemplary switched line
phase shifter 610 that can be provided in the phase shifter 412(1)
of FIG. 6A as the first switched line phase shifter 600 and the
second switched line phase shifter 604 to provide a larger phase
shift with coarse resolution. The switched line phase shifter 610
includes a first two-way switch 612 and a second two-way switch
614, which are controlled by the control circuit 420 of FIG. 4. The
switched line phase shifter 610 includes a first switched path 616
configured to provide a 90.degree. or 180.degree. phase shift with
coarse resolution. The switched line phase shifter 610 also
includes a second switched path 618, which includes a band pass
filter 620 that can provide approximately 0.degree. phase shift. In
a non-limiting example, the band pass filter 620 has a phase
linearity slope across an operation frequency range similar to the
operation frequency range of a 90.degree. or a 180.degree.
linearity slope. When phases associated with the first switched
path 616 and the second switched path 618 are observed, a wide band
flat 90.degree. or 180.degree. phase shift is achieved.
[0053] FIG. 6C is a schematic diagram of an exemplary reflective
phase shifter 622 that can be provided in the phase shifter 412(1)
of FIG. 6A as the reflective phase shifter 602 to provide a smaller
phase shift with fine resolution. The reflective phase shifter 622
includes a three decibel (3 dB) hybrid coupler 624. The 3 dB hybrid
coupler 624 has an input port 626 connected to an input port 628 of
the reflective phase shifter 622. The 3 dB hybrid coupler 624 has
an output port 630 connected to an output port 632 of the
reflective phase shifter 622. The 3 dB hybrid coupler 624 has a
coupled port 634 and an isolated port 636 connected to a first
switched capacitor 638 and a second switched capacitor 640,
respectively. The first intermediate downlink RF signal 606 is
divided by two between the coupled port 634 and the isolated port
636 of the 3 dB hybrid coupler 624. An incident wave at the coupled
port 634 and the isolated port 636 are reflected back to the first
switched capacitor 638 and the second switched capacitor 640 that
have approximately zero decibel (0 dB) return loss. The incident
wave reflected from the coupled port 634 and the isolated port 636
are combined in-phase at the output port 632. As such, by changing
capacitances of the first switched capacitor 638 and the second
switched capacitor 640 via the control circuit 420 of FIG. 4, it is
possible to control the reflective phase shifter 622 to provide a
smaller phase shift with fine resolution. The phase shift
resolution of the reflective phase shifter 622 is determined by
capacitance resolution of the first switched capacitor 638 and the
second switched capacitor 640.
[0054] With reference back to FIG. 6A, the first switched line
phase shifter 600 is configured to generate either a 0.degree. or a
180.degree. phase shift based on a first control bit 642. In a
non-limiting example, the first switched line phase shifter 600 is
configured to generate the 0.degree. phase shift when the first
control bit 642 is set to zero, and generate the 180.degree. phase
shift when the first control bit 642 is set to one. The reflective
phase shifter 602 is configured to generate a phase shift between
0.degree. and 90.degree. based on five second control bits
644(1)-644(5). The five second control bits 644(1)-644(5) are able
to define thirty-two (between binary value 00000 and 11111)
possible phase shift resolutions for the reflective phase shifter
602. In a non-limiting example, the reflective phase shifter 602
generates a forty-five-degree (45.degree.) phase shift when the
five second control bits 644(1)-644(5) are set to binary value
01111. The second switched line phase shifter 604 is configured to
generate either a 0.degree. or a 90.degree. phase shift based on a
third control bit 646. In a non-limiting example, the second
switched line phase shifter 604 is configured to generate the
0.degree. phase shift when the third control bit 646 is set to zero
(0), and generate the 90.degree. phase shift when the third control
bit 646 is set to one. Hence, by changing a combination of the
first control bit 642, the five second control bits 644(1)-644(5),
and the third control bit 646, it is possible to configure the
phase shifter 412(1) to generate a 0.degree. to 360.degree. phase
shift. A summary of common combinations of the first control bit
642, the five second control bits 644(1)-644(5), and the third
control bit 646 for the phase shifter 412(1) is provided in the
table below.
TABLE-US-00001 Total Phase Shift First Five (5) Second by the Phase
Control Bit Control Bits Third Control Bit Shifter (412(1)) (642)
(644(1)-644(5)) (646) 0.degree. 0 00000 0 45.degree. 0 01111 0
90.degree. 0 00000 1 135.degree. 0 01111 1 180.degree. 1 00000 0
225.degree. 1 01111 0 270.degree. 1 00000 1 315.degree. 1 01111
1
[0055] The second switched line phase shifter 604 is also
configured to phase-shift the modified uplink RF signal 430(1) by
0.degree. or 90.degree. to generate a first intermediate uplink RF
signal 648. The reflective phase shifter 602 is configured to
phase-shift the first intermediate uplink RF signal 648 between
0.degree. and 90.degree. to generate a second intermediate uplink
RF signal 650. The first switched line phase shifter 600 is
configured to phase-shift the second intermediate uplink RF signal
650 by either 0.degree. or 180.degree. to generate the uplink RF
signal 432(1). Hence, the phase shifter 412(1) can phase-shift the
modified uplink RF signal 430(1) (e.g., in increments of three
degrees)(3.degree.) up to 360.degree..
[0056] With reference back to FIG. 4, the antenna array 402 can be
configured to include any positive integer number of the RF
antennas 406(1)-406(N) as appropriate. In one non-limiting example,
the antenna array 402 is configured to include nineteen (19) RF
antennas 406(1)-406(19). In this regard, the nineteen (19) RF
antennas 406(1)-406(19) are configured to transmit nineteen
modified downlink RF signals 408(1)-408(19) in the formed radiation
beam 422 in the radiation direction 424. The passive beamforming
network 410 includes nineteen phase shifters 412(1)-412(19)
configured to phase-shift nineteen downlink RF signals
418(1)-418(19) to generate the nineteen modified downlink RF
signals 408(1)-408(19) in nineteen phases
.theta..sub.1-.theta..sub.19, respectively. The nineteen phase
shifters 412(1)-412(19) are functionally equivalent to the phase
shifters 412(1)-412(N). The control circuit 420 is configured to
determine the nineteen phases .theta..sub.1-.theta..sub.19 to cause
the nineteen RF antennas 406(1)-406(19) to transmit the nineteen
(19) modified downlink RF signals 408(1)-408(19) in the formed
radiation beam 422 in the radiation direction 424. The control
circuit 420 controls the nineteen phase shifters 412(1)-412(19) to
generate the nineteen modified downlink RF signals 408(1)-408(19)
in the nineteen phases .theta..sub.1-.theta..sub.19, respectively.
The remote unit 400 also includes a one-to-nineteen (1:19) splitter
combiner 414', which is functionally equivalent to the splitter
combiner 414, configured to split the downlink RF communications
signal 416 into the nineteen downlink RF signals 418(1)-418(19).
The 1:19 splitter combiner 414' provides the nineteen downlink RF
signals 418(1)-418(19) to the phase shifters 412(1)-412(19).
Aspects related to supporting antenna array beamforming using the
nineteen RF antennas 406(1)-406(19) in the remote unit 400 are
discussed next with references to FIGS. 7 and 8.
[0057] In this regard, FIG. 7 is a schematic diagram providing an
exemplary illustration of the 1:19 splitter combiner 414' of FIG. 4
to split the downlink RF communications signal 416 into the
nineteen downlink RF signals 418(1)-418(19). With reference to FIG.
7, the 1:19 splitter combiner 414' includes a first three-way
splitter 700, three second three-way splitters 702(1)-702(3), a
third three-way splitter 704, and eight two-way splitters
706(1)-706(8) disposed in a cascading arrangement. The first
three-way splitter 700 receives the downlink RF communications
signal 416 having the determined power level P.sub.S. The first
three-way splitter 700 splits the downlink RF communications signal
416 to generate three first downlink RF signals 708(1)-708(3), each
having approximately one-third of the determined power level
P.sub.S (1/3 P.sub.S). The three second three-way splitters
702(1)-702(3) receive the first downlink RF signals 708(1)-708(3),
respectively. The three second three-way splitters 702(1)-702(3)
split the first downlink RF signals 708(1)-708(3) to generate nine
(9) second downlink RF signals 710(1)-710(9), each having one-ninth
of the determined power level P.sub.S ( 1/9 P.sub.S). The third
three-way splitter 704 receives and splits the second downlink RF
signal 710(5) to generate the downlink RF signals 418(9)-418(11),
each having one-twenty-seventh of the determined power level
P.sub.S ( 1/27 P.sub.S). The eight two-way splitters 706(1)-706(8)
receive and split the second downlink RF signals 710(1)-710(4),
710(6)-710(9) to generate sixteen downlink RF signals
418(1)-418(8), 418(12)-418(19), each having one-eighteenth of the
determined power level P.sub.S ( 1/18 P.sub.S).
[0058] As a result, the sixteen downlink RF signals 418(1)-418(8),
418(12)-418(19) among the nineteen downlink RF signals
418(1)-418(19) each have 1/18 P.sub.S, while the three downlink RF
signals 418(9)-418(11) among the nineteen downlink RF signals
418(1)-418(19) each have 1/27 P.sub.S. Understandably, the power
inequality among the nineteen downlink RF signals 418(1)-418(19)
can result in similar power inequality among the nineteen modified
downlink RF signals 408(1)-408(19). As such, it is necessary to
properly arrange the nineteen RF antennas 406(1)-406(19) in the
antenna array 402 to mitigate potential impact of the power
inequality on RF performance of the antenna array 402.
[0059] In this regard, FIG. 8 is a schematic diagram providing an
exemplary circular-shaped arrangement 800 of the nineteen RF
antennas 406(1)-406(19) of FIG. 4. According to FIG. 8, the
nineteen RF antennas 406(1)-406(19) are disposed in a
circular-shaped area 802 having a center point 804. It shall be
appreciated that the circular-shaped arrangement 800 is one of many
possible arrangements for the nineteen RF antennas 406(1)-406(19)
and thus shall not be considered as being limiting. In fact, it may
be possible to dispose the nineteen RF antennas 406(1)-406(19)
according to other geometrical shapes, such as a triangle,
rectangle, pentagon, hexagon, and so on.
[0060] With reference to FIG. 8, one first selected RF antenna
among the nineteen RF antennas 406(1)-406(19) is disposed at the
center point 804 of the circular-shaped area 802. In a non-limiting
example, the RF antenna 406(1) is selected to be disposed at the
center point 804 of the circular-shaped area 802. The RF antenna
406(1) is configured to transmit the modified downlink RF signal
408(1) having 1/18 P.sub.S.
[0061] Next, six second selected RF antennas among the nineteen RF
antennas 406(1)-406(19) are disposed respectively at six first
vertices 806(1)-806(6) of a first regular hexagon 808. According to
the same non-limiting example above, the RF antennas 406(2)-406(4)
and the RF antennas 406(9)-406(11) are selected to be disposed at
the six first vertices 806(1)-806(6). The RF antennas
406(2)-406(4), which are configured to transmit the modified
downlink RF signals 408(2)-408(4) each having 1/18 P.sub.S, are
disposed at the first vertices 806(1), 806(3), and 806(5),
respectively. The RF antennas 406(9)-406(11), which are configured
to transmit the modified downlink RF signals 408(9)-408(11) each
having 1/27 P.sub.S, are disposed at the first vertices 806(2),
806(4), and 806(6), respectively. The first regular hexagon 808 has
a first radius d.sub.1 extending from the center point 804 of the
circular-shaped area 802. In this regard, the first regular hexagon
808 is also centered at the center point 804 of the circular-shaped
area 802.
[0062] With continuing reference to FIG. 8, six third selected RF
antennas among the nineteen RF antennas 406(1)-406(19) are disposed
respectively at six second vertices 810(1)-810(6) of a second
regular hexagon 812. According to the same non-limiting example
above, the RF antennas 406(5)-406(8) and the RF antennas 406(12),
406(13) are selected to be disposed at the six second vertices
810(1)-810(6), respectively. The RF antennas 406(5)-406(8) are
configured to transmit the modified downlink RF signals
408(5)-408(8) each having 1/18 P.sub.S. The RF antennas 406(12),
406(13) are configured to transmit the modified downlink RF signals
408(12), 408(13) each having 1/18 P.sub.S. The second regular
hexagon 812 has a second radius d.sub.2 extending from the center
point 804 of the circular-shaped area 802. In this regard, the
second regular hexagon 812 is also centered at the center point 804
of the circular-shaped area 802.
[0063] The second regular hexagon 812 has six sides 814(1)-814(6)
having six respective midpoints 816(1)-816(6). Six fourth selected
RF antennas among the nineteen RF antennas 406(1)-406(19) are
disposed at six respective midpoints 816(1)-816(6) of the six sides
814(1)-814(6). According to the same non-limiting example above,
the RF antennas 406(14)-406(19) are selected to be disposed at the
six respective midpoints 816(1)-816(6). The RF antennas
406(14)-406(19) are configured to transmit the modified downlink RF
signals 408(14)-408(19) each having 1/18 P.sub.S.
[0064] The second radius d.sub.2 of the second regular hexagon 812
equals two times the first radius d.sub.1 of the first regular
hexagon 808 (d.sub.2=2d.sub.1). In this regard, each of the
nineteen RF antennas 406(1)-106(19) in the antenna array 402 is
separated from respective neighboring RF antennas by the first
radius d.sub.1. In a non-limiting example, the nineteen RF antennas
406(1)-406(19) are configured to transmit the nineteen modified
downlink RF signals 408(1)-408(19) in the predetermined RF band. To
help reduce RF interference among the nineteen RF antennas
406(1)-406(19) in the antenna array 402, the first radius d.sub.1
is configured to be one-half of a wavelength of the center
frequency of the predetermined RF band. If the predetermined RF
band occupies the RF spectrum between 1710 MHz and 2180 MHz, the
center frequency of the predetermined RF band will be 1910 MHz.
Accordingly, the first radius d.sub.1 needs to be approximately six
point five centimeters (6.5 cm). As such, the circular-shaped area
802 may be configured to have a diameter of approximately thirty
centimeters (30 cm).
[0065] With continuing reference to FIG. 8, the RF antennas
406(1)-406(N) of FIG. 4 can be disposed in the circular-shaped area
802 based on a tiered arrangement, which is discussed and
illustrated next with reference to the nineteen RF antennas
406(1)-406(19). It shall be appreciated that the tired arrangement
can be generalized to be applicable to any number of RF
antennas.
[0066] In this regard, X first RF antennas 406(12), 406(4), 406(1),
406(9), and 406(6), wherein X is a positive non-zero integer
number, selected from among the nineteen RF antennas 406(1)-406(19)
are disposed uniformly on a first line 818 that crosses the center
point 804 of the circular-shaped area 802. Each of the X first RF
antennas 406(12), 406(4), 406(1), 406(9), and 406(6) is separated
from an immediately adjacent first RF antenna by the first radius
d.sub.1 (the first radius d.sub.1 being a predetermined distance).
X-1 second RF antennas 406(18), 406(11), 406(2), and 406(14)
selected from among the nineteen RF antennas 406(1)-406(19) are
disposed uniformly on a second line 820 located immediately
adjacent to the first line 818 and separated from the first line
818 by a line separation distance d.sub.L. Each of the X-1 second
RF antennas 406(18), 406(11), 406(2), and 406(14) is separated from
an immediately adjacent second RF antenna by the first radius
d.sub.1. X-1 third RF antennas 406(17), 406(10), 406(3), and
406(15) selected from among the nineteen RF antennas 406(1)-406(19)
are disposed uniformly on a third line 822 located immediately
adjacent to the first line 818 and separated from the first line
818 by the line separation distance d.sub.L. Each of the X-1 third
RF antennas 406(17), 406(10), 406(3), and 406(15) is separated from
an immediately adjacent third RF antenna by the first radius
d.sub.1. X-2 fourth RF antennas 406(13), 406(19), and 406(5)
selected from among the nineteen RF antennas 406(1)-406(19) are
disposed uniformly on a fourth line 824 located immediately
adjacent to the second line 820 and separated from the second line
820 by the line separation distance d.sub.L. Each of the X-2 fourth
RF antennas 406(13), 406(19), and 406(5) is separated from an
immediately adjacent fourth RF antenna by the first radius d.sub.1.
X-2 fifth RF antennas 406(8), 406(16), and 406(7) selected from
among the nineteen RF antennas 406(1)-406(19) are disposed
uniformly on a fifth line 826 located immediately adjacent to the
third line 822 and separated from the third line 822 by the line
separation distance d.sub.L. Each of the X-2 fifth RF antennas
406(8), 406(16), and 406(7) is separated from an immediately
adjacent fifth RF antenna by the first radius d.sub.1.
[0067] With reference back to FIG. 4, when the antenna array 402 is
configured to include the nineteen RF antennas 406(1)-406(19), the
passive beamforming network 410 will include the 1:19 splitter
combiner 414' and the nineteen phase shifters 412(1)-412(19). In
this regard, in a non-limiting example, insertion loss associated
with the 1:19 splitter combiner 414' can cause approximately a
twelve point eight decibel (12.8 dB), which equals approximately
ten logarithm nineteen (10 log(19)), loss of the determined power
level P.sub.S of the downlink RF communications signal 416. In
addition, insertion loss associated with the nineteen phase
shifters 412(1)-412(19) can also cause approximately a three
decibel (3 dB) loss of the determined power level P.sub.S. However,
the nineteen RF antennas 406(1)-406(19) in the antenna array 402
are capable of generating approximately a twenty-five point six
decibel (25.6 dB), which equals approximately twenty logarithm
nineteen (20 log(19)), gain in the formed radiation beam 422. As a
result, the remote unit 400 may have approximately an eight decibel
(8 dB) gain despite the losses caused by the 1:19 splitter combiner
414' and the nineteen phase shifters 412(1)-412(19).
[0068] In a non-limiting example, the remote unit 400 is mounted on
a ceiling of a building with a twenty-five-degree (25.degree.)
downward tilt. As such, a portion of the formed radiation beam 422
may be reflected by a physical object(s) (e.g., a floor) in the
building. In this regard, FIG. 9 is a schematic diagram of an
exemplary elevation pattern 900 of the formed radiation beam 422
when the remote unit 400 of FIG. 4 is mounted on a ceiling of a
building.
[0069] With reference to FIG. 9, the elevation pattern 900 of the
formed radiation beam 422 is flipped along a horizontal axis 902
when the remote unit 400 is mounted on the ceiling and the RF
antennas 406(1)-406(N) are tilted downward. Further, the elevation
pattern 900 needs to be weighted with respect to an inherent
pattern of a monopole antenna. In a non-limiting example, the
elevation pattern 900 closely resembles an overall pattern of the
formed radiation beam 422 for transmitting the modified downlink RF
signals 408(1)-408(N) in the RF spectrum between 1710 MHz and 2180
MHz.
[0070] With reference back to FIG. 4, the remote unit 400 can be
configured to support antenna array beamforming in a higher
frequency band (e.g., the 1710 MHz to 2180 MHz band), while
concurrently supporting transmissions in a lower frequency band
(e.g., 700 MHz band or 850 MHz band). In this regard, FIG. 10 is a
schematic diagram of an exemplary remote unit 1000 including the
antenna array 402 of FIG. 4 for supporting antenna array
beamforming in a higher frequency band, and a second RF antenna
1002 for transmitting a second downlink RF communications signal
1004 in a lower frequency band. Common elements between FIGS. 4 and
10 are shown therein with common element numbers and will not be
re-described herein.
[0071] With reference to FIG. 10, in a non-limiting example, the
second RF antenna 1002 is an omnidirectional antenna (e.g., a
monopole antenna). The remote unit 1000 includes a duplexer circuit
1006 configured to receive the downlink RF communications signal
416 and the second downlink RF communications signal 1004. The
duplexer circuit 1006 provides the downlink RF communications
signal 416 to the passive beamforming network 410 and the antenna
array 402 for transmission over the predetermined RF band (e.g.,
the 1710 MHz to 2180 MHz band). The duplexer circuit 1006 also
provides the second downlink RF communications signal 1004 to
signal processing circuitry 1008. The signal processing circuitry
1008 in turn provides the second downlink RF communications signal
1004 to the second RF antenna 1002 for transmission in a second
predetermined RF band (e.g., the 700 MHz band or the 850 MHz band).
In this regard, the second predetermined RF band occupies a lower
frequency spectrum than the predetermined RF band. The second RF
antenna 1002 is also configured to receive a second uplink RF
communications signal 1010. The signal processing circuitry 1008 in
turn provides the second uplink RF communications signal 1010 to
the duplexer circuit 1006.
[0072] The remote unit 400 of FIG. 4 may be adapted to concurrently
support multiple-input multiple-output (MIMO) and antenna array
beamforming. In this regard, FIG. 11A is a schematic diagram of an
exemplary remote unit 1100 configured to support concurrent MIMO
and antenna array beamforming operations. Common elements between
FIGS. 4 and 11A are shown therein with common element numbers and
will not be re-described herein.
[0073] With reference to FIG. 11A, the remote unit 1100 includes a
second passive beamforming network 410'. The second passive
beamforming network 410' includes a second splitter combiner 414'',
which is functionally equivalent to the splitter combiner 414. The
second passive beamforming network 410' also includes a plurality
of second phase shifters 412(1)'-412(N)'. The second phase shifters
412(1)'-412(N)' are functionally equivalent to the phase shifters
412(1)-412(N), respectively.
[0074] The second splitter combiner 414'' is configured to split a
second downlink RF communications signal 416' into a plurality of
second downlink RF signals 418(1)'-418(N)'. The second splitter
combiner 414'' is configured to provide the second downlink RF
signals 418(1)'-418(N)' to the second phase shifters
412(1)'-412(N)', respectively. The second phase shifters
412(1)'-412(N)' are configured to phase-shift the second downlink
RF signals 418(1)'-418(N)' to generate a plurality of second
modified downlink RF signals 408(1)'-408(N)' in a plurality of
second phases .theta..sub.1'-.theta..sub.N', respectively.
[0075] The remote unit 1100 includes a plurality of MIMO splitter
combiners 1102(1)-1102(N). The MIMO splitter combiners
1102(1)-1102(N) are configured to receive the modified downlink RF
signals 408(1)-408(N) from the phase shifters 412(1)-412(N),
respectively. The MIMO splitter combiners 1102(1)-1102(N) are
configured to receive the second modified downlink RF signals
408(1)'-408(N)' from the second phase shifters 412(1)'-412(N)',
respectively. The MIMO splitter combiners 1102(1)-1102(N) are
further configured to generate a plurality of downlink MIMO signals
1104(1)-1104(N) based on the modified downlink RF signals
408(1)-408(N) and the second modified downlink RF signals
408(1)'-408(N)', respectively. For example, the MIMO splitter
combiner 1102(1) generates the downlink MIMO signal 1104(1) by
combining the modified downlink RF signal 408(1) and the second
modified downlink RF signal 408(1)'. Likewise, the MIMO splitter
combiner 1102(2) generates the downlink MIMO signal 1104(2) by
combining the modified downlink RF signal 408(2) and the second
modified downlink RF signal 408(2)', and so on. The MIMO splitter
combiners 1102(1)-1102(N) further provide the downlink MIMO signals
1104(1)-1104(N) to the RF antennas 406(1)-406(N), respectively.
[0076] The control circuit 420 (not shown) determines the phases
.theta..sub.1-.theta..sub.N and the second phases
.theta..sub.1'-.theta..sub.N' to cause the antenna array 402 to
transmit a first formed radiation beam 1106(1) and a second formed
radiation beam 1106(2). FIG. 11B is a schematic diagram providing
an exemplary illustration of the first formed radiation beam
1106(1) and the second formed radiation beam 1106(2) transmitted
from the antenna array 402 in the remote unit 1100 of FIG. 11A.
[0077] FIG. 12 is a schematic diagram of an exemplary WDS 1200
provided in the form of a distributed antenna system (DAS) that
includes one or more remote units that support antenna array
beamforming, including but not limited to the remote unit 400 of
FIG. 4, the remote unit 1000 of FIG. 10, and the remote unit 1100
of FIG. 11A. The WDS 1200 may be an optical fiber-based WDS that
includes an optical fiber for distributing communications services
for multiple frequency bands. Otherwise, the WDS 1200 may include
an electrical link for distributing communications services for
multiple frequency bands. The WDS 1200 in this example is comprised
of three main components. One or more radio interfaces provided in
the form of radio interface modules (RIMs) 1202(1)-1202(M) are
provided in a head-end unit (HEU) 1204 to receive and process
downlink electrical communications signals 1206D(1)-1206D(R) prior
to optical conversion into downlink optical fiber-based
communications signals. The downlink electrical communications
signals 1206D(1)-1206D(R) may be received from a base station (not
shown) as an example. The RIMs 1202(1)-1202(M) provide both
downlink and uplink interfaces for signal processing. The notations
"1-R" and "1-M" indicate that any number of the referenced
component, 1-R and 1-M, respectively, may be provided. The HEU 1204
is configured to accept the RIMs 1202(1)-1202(M) as modular
components that can easily be installed and removed or replaced in
the HEU 1204. In one example, the HEU 1204 is configured to support
up to twelve (12) RIMs 1202(1)-1202(12). Each RIM 1202(1)-1202(M)
can be designed to support a particular type of radio source or
range of radio sources (i.e., frequencies) to provide flexibility
in configuring the HEU 1204 and the WDS 1200 to support the desired
radio sources.
[0078] For example, one RIM 1202 may be configured to support the
Personalized Communications System (PCS) radio band. Another RIM
1202 may be configured to support the 800 megahertz (MHz) radio
band. In this example, by inclusion of the RIMs 1202(1)-1202(M),
the HEU 1204 could be configured to support and distribute
communications signals on both PCS and Long-Term Evolution (LTE)
700 radio bands, as an example. The RIMs 1202(1)-1202(M) may be
provided in the HEU 1204 that support any frequency bands desired,
including but not limited to the US Cellular band, PCS band,
Advanced Wireless Service (AWS) band, 700 MHz band, Global System
for Mobile communications (GSM) 900, GSM 1800, and Universal Mobile
Telecommunications System (UMTS). The RIMs 1202(1)-1202(M) may also
be provided in the HEU 1204 that support any wireless technologies
desired, including but not limited to Code Division Multiple Access
(CDMA), CDMA200, 1.times.RTT, Evolution-Data Only (EV-DO), UMTS,
High-speed Packet Access (HSPA), GSM, General Packet Radio Services
(GPRS), Enhanced Data GSM Environment (EDGE), Time Division
Multiple Access (TDMA), LTE, iDEN, and Cellular Digital Packet Data
(CDPD).
[0079] The RIMs 1202(1)-1202(M) may be provided in the HEU 1204
that support any frequencies desired, including but not limited to
US FCC and Industry Canada frequencies (824-849 MHz on uplink and
869-894 MHz on downlink), US FCC and Industry Canada frequencies
(1850-1915 MHz on uplink and 1930-1995 MHz on downlink), US FCC and
Industry Canada frequencies (1710-1755 MHz on uplink and 2110-2155
MHz on downlink), US FCC frequencies (698-716 MHz and 776-787 MHz
on uplink and 728-746 MHz on downlink), EU R & TTE frequencies
(880-915 MHz on uplink and 925-960 MHz on downlink), EU R & TTE
frequencies (1710-1785 MHz on uplink and 1805-1880 MHz on
downlink), EU R & TTE frequencies (1920-1980 MHz on uplink and
2110-2170 MHz on downlink), US FCC frequencies (806-824 MHz on
uplink and 851-869 MHz on downlink), US FCC frequencies (896-901
MHz on uplink and 929-941 MHz on downlink), US FCC frequencies
(793-805 MHz on uplink and 763-775 MHz on downlink), and US FCC
frequencies (2495-2690 MHz on uplink and downlink).
[0080] With continuing reference to FIG. 12, when the WDS 1200 is
the optical fiber-based WDS, the downlink electrical communications
signals 1206D(1)-1206D(R) are provided to a plurality of optical
interfaces provided in the form of optical interface modules (OIMs)
1208(1)-1208(N) in this embodiment to convert the downlink
electrical communications signals 1206D(1)-1206D(R) into downlink
optical fiber-based communications signals 1210D(1)-1210D(R). The
notation "1-N" indicates that any number of the referenced
component 1-N may be provided. The OIMs 1208(1)-1208(N) may be
configured to provide one or more optical interface components
(OICs) that contain optical-to-electrical (O/E) and
electrical-to-optical (E/O) converters, as will be described in
more detail below. The OIMs 1208(1)-1208(N) support the radio bands
that can be provided by the RIMs 1202(1)-1202(M), including the
examples previously described above.
[0081] The OIMs 1208(1)-1208(N) each include E/O converters to
convert the downlink electrical communications signals
1206D(1)-1206D(R) into the downlink optical fiber-based
communications signals 1210D(1)-1210D(R). The downlink optical
fiber-based communications signals 1210D(1)-1210D(R) are
communicated over a downlink optical fiber-based communications
medium 1212D to a plurality of remote units 1214(1)-1214(S). At
least one remote unit among the remote units 1214(1)-1214(S) is
provided as the remote unit 400 of FIG. 4, the remote unit 1000 of
FIG. 10, or the remote unit 1100 of FIG. 11A for supporting antenna
array beamforming. The notation "1-S" indicates that any number of
the referenced component 1-S may be provided. Remote O/E converters
provided in the remote units 1214(1)-1214(S) convert the downlink
optical fiber-based communications signals 1210D(1)-1210D(R) back
into the downlink electrical communications signals
1206D(1)-1206D(R), which are provided to antennas 1216(1)-1216(S)
in the remote units 1214(1)-1214(S) to client devices in the
reception range of the antennas 1216(1)-1216(S).
[0082] Remote unit E/O converters are also provided in the remote
units 1214(1)-1214(S) to convert uplink electrical communications
signals 1218U(1)-1218U(S) received from the client devices through
the antennas 1216(1)-1216(S) into uplink optical fiber-based
communications signals 1210U(1)-1210U(S). The remote units
1214(1)-1214(S) communicate the uplink optical fiber-based
communications signals 1210U(1)-1210U(S) over an uplink optical
fiber-based communications medium 1212U to the OIMs 1208(1)-1208(N)
in the HEU 1204. The OIMs 1208(1)-1208(N) include O/E converters
that convert the received uplink optical fiber-based communications
signals 1210U(1)-1210U(S) into uplink electrical communications
signals 1220U(1)-1220U(S), which are processed by the RIMs
1202(1)-1202(M) and provided as the uplink electrical
communications signals 1220U(1)-1220U(S). The HEU 1204 may provide
the uplink electrical communications signals 1220U(1)-1220U(S) to a
base station or other communications system.
[0083] Note that the downlink optical fiber-based communications
medium 1212D and the uplink optical fiber-based communications
medium 1212U connected to each remote unit 1214(1)-1214(S) may be a
common optical fiber-based communications medium, wherein for
example, wave division multiplexing (WDM) is employed to provide
the downlink optical fiber-based communications signals
1210D(1)-1210D(R) and the uplink optical fiber-based communications
signals 1210U(1)-1210U(S) on the same optical fiber-based
communications medium.
[0084] The WDS 1200 of FIG. 12 may be provided in an indoor
environment, as illustrated in FIG. 13. FIG. 13 is a partial
schematic cut-away diagram of an exemplary building infrastructure
1300 in which the WDS 1200 of FIG. 12 can be employed. The building
infrastructure 1300 in this embodiment includes a first (ground)
floor 1302(1), a second floor 1302(2), and a third floor 1302(3).
The floors 1302(1)-1302(3) are serviced by an HEU 1304 to provide
antenna coverage areas 1306 in the building infrastructure 1300.
The HEU 1304 is communicatively coupled to a base station 1308 to
receive downlink communications signals 1310D from the base station
1308. The HEU 1304 is communicatively coupled to a plurality of
remote units 1312 to distribute the downlink communications signals
1310D to the remote units 1312 and to receive uplink communications
signals 1310U from the remote units 1312, as previously discussed
above. The downlink communications signals 1310D and the uplink
communications signals 1310U communicated between the HEU 1304 and
the remote units 1312 are carried over a riser cable 1314. The
riser cable 1314 may be routed through interconnect units (ICUs)
1316(1)-1316(3) dedicated to each of the floors 1302(1)-1302(3)
that route the downlink communications signals 1310D and the uplink
communications signals 1310U to the remote units 1312 and also
provide power to the remote units 1312 via array cables 1318.
[0085] FIG. 14 is a schematic diagram representation of additional
detail illustrating an exemplary computer system 1400 that could be
employed in a control circuit, including the control circuit 420 in
the remote unit 400 of FIG. 4 and the remote unit 1000 of FIG. 10
for controlling the passive beamforming network 410 in the remote
unit 400 to support antenna array beamforming. In this regard, the
computer system 1400 is adapted to execute instructions from an
exemplary computer-readable medium to perform these and/or any of
the functions or processing described herein.
[0086] In this regard, the computer system 1400 in FIG. 14 may
include a set of instructions that may be executed to predict
frequency interference to avoid or reduce interference in a
multi-frequency DAS. The computer system 1400 may be connected
(e.g., networked) to other machines in a LAN, an intranet, an
extranet, or the Internet. While only a single device is
illustrated, the term "device" shall also be taken to include any
collection of devices that individually or jointly execute a set
(or multiple sets) of instructions to perform any one or more of
the methodologies discussed herein. The computer system 1400 may be
a circuit or circuits included in an electronic board card, such as
a printed circuit board (PCB), a server, a personal computer, a
desktop computer, a laptop computer, a personal digital assistant
(PDA), a computing pad, a mobile device, or any other device, and
may represent, for example, a server or a user's computer.
[0087] The exemplary computer system 1400 in this embodiment
includes a processing device or processor 1402, a main memory 1404
(e.g., read-only memory (ROM), flash memory, dynamic random access
memory (DRAM), such as synchronous DRAM (SDRAM), etc.), and a
static memory 1406 (e.g., flash memory, static random access memory
(SRAM), etc.), which may communicate with each other via a data bus
1408. Alternatively, the processor 1402 may be connected to the
main memory 1404 and/or the static memory 1406 directly or via some
other connectivity means. The processor 1402 may be a controller
including the controller 438 of FIG. 4, as an example, and the main
memory 1404 or the static memory 1406 may be any type of
memory.
[0088] The processor 1402 represents one or more general-purpose
processing devices, such as a microprocessor, central processing
unit, or the like. More particularly, the processor 1402 may be a
complex instruction set computing (CISC) microprocessor, a reduced
instruction set computing (RISC) microprocessor, a very long
instruction word (VLIW) microprocessor, a processor implementing
other instruction sets, or other processors implementing a
combination of instruction sets. The processor 1402 is configured
to execute processing logic in instructions for performing the
operations and steps discussed herein.
[0089] The computer system 1400 may further include a network
interface device 1410. The computer system 1400 also may or may not
include an input 1412, configured to receive input and selections
to be communicated to the computer system 1400 when executing
instructions. The computer system 1400 also may or may not include
an output 1414, including but not limited to a display, a video
display unit (e.g., a liquid crystal display (LCD) or a cathode ray
tube (CRT)), an alphanumeric input device (e.g., a keyboard),
and/or a cursor control device (e.g., a mouse).
[0090] The computer system 1400 may or may not include a data
storage device that includes instructions 1416 stored in a
computer-readable medium 1418. The instructions 1416 may also
reside, completely or at least partially, within the main memory
1404 and/or within the processor 1402 during execution thereof by
the computer system 1400, the main memory 1404 and the processor
1402 also constituting computer-readable medium. The instructions
1416 may further be transmitted or received over a network 1420 via
the network interface device 1410.
[0091] While the computer-readable medium 1418 is shown in an
exemplary embodiment to be a single medium, the term
"computer-readable medium" should be taken to include a single
medium or multiple media (e.g., a centralized or distributed
database, and/or associated caches and servers) that store the one
or more sets of instructions. The term "computer-readable medium"
shall also be taken to include any medium that is capable of
storing, encoding, or carrying a set of instructions for execution
by the processing device and that cause the processing device to
perform any one or more of the methodologies of the embodiments
disclosed herein. The term "computer-readable medium" shall
accordingly be taken to include, but not be limited to, solid-state
memories, optical medium, and magnetic medium.
[0092] The embodiments disclosed herein include various steps. The
steps of the embodiments disclosed herein may be formed by hardware
components or may be embodied in machine-executable instructions,
which may be used to cause a general-purpose or special-purpose
processor programmed with the instructions to perform the steps.
Alternatively, the steps may be performed by a combination of
hardware and software.
[0093] The embodiments disclosed herein may be provided as a
computer program product, or software, that may include a
machine-readable medium (or computer-readable medium) having stored
thereon instructions, which may be used to program a computer
system (or other electronic devices) to perform a process according
to the embodiments disclosed herein. A machine-readable medium
includes any mechanism for storing or transmitting information in a
form readable by a machine (e.g., a computer). For example, a
machine-readable medium includes: a machine-readable storage medium
(e.g., ROM, random access memory ("RAM"), a magnetic disk storage
medium, an optical storage medium, flash memory devices, etc.); and
the like.
[0094] Unless otherwise expressly stated, it is in no way intended
that any method set forth herein be construed as requiring that its
steps be performed in a specific order. Accordingly, where a method
claim does not actually recite an order to be followed by its
steps, or it is not otherwise specifically stated in the claims or
descriptions that the steps are to be limited to a specific order,
it is in no way intended that any particular order be inferred.
[0095] It will be apparent to those skilled in the art that various
modifications and variations can be made without departing from the
spirit or scope of the invention. Since modifications,
combinations, sub-combinations and variations of the disclosed
embodiments incorporating the spirit and substance of the invention
may occur to persons skilled in the art, the invention should be
construed to include everything within the scope of the appended
claims and their equivalents.
* * * * *