U.S. patent application number 15/448338 was filed with the patent office on 2017-11-23 for das integrated digital off-air repeater.
This patent application is currently assigned to Dali Wireless, Inc.. The applicant listed for this patent is Dali Wireless, Inc.. Invention is credited to Shawn Patrick Stapleton.
Application Number | 20170339625 15/448338 |
Document ID | / |
Family ID | 50930792 |
Filed Date | 2017-11-23 |
United States Patent
Application |
20170339625 |
Kind Code |
A1 |
Stapleton; Shawn Patrick |
November 23, 2017 |
DAS INTEGRATED DIGITAL OFF-AIR REPEATER
Abstract
Embodiments may allow remote base transceiver stations (BTSs)
physically located away from a local source of users to be able to
provide local service as if the remote BTSs were at or near the
local source of users. Some embodiments may include a plurality of
BTSs, each having one or more sectors, and one or more digital
access units (DAUs). Embodiments may also include a plurality of
repeater digital units (RDUs), where each RDU may be configured to
communicate to at least one of the plurality of BTSs and may be
operable to route signals optically to the one or more DAUs.
Embodiments may also include a plurality of digital remote units
(DRUs) located at a location remote to the one or more DAUs,
wherein the plurality of remote DRUs may be operable to transport
signals to the one or more DAUs.
Inventors: |
Stapleton; Shawn Patrick;
(Vancouver, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dali Wireless, Inc. |
Menlo Park |
CA |
US |
|
|
Assignee: |
Dali Wireless, Inc.
Menlo Park
CA
|
Family ID: |
50930792 |
Appl. No.: |
15/448338 |
Filed: |
March 2, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14743789 |
Jun 18, 2015 |
9622148 |
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15448338 |
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14044668 |
Oct 2, 2013 |
9112549 |
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14743789 |
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61710391 |
Oct 5, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 88/085 20130101;
H04B 10/25753 20130101; H04W 40/20 20130101; H04B 7/026 20130101;
H04W 40/22 20130101 |
International
Class: |
H04W 40/22 20090101
H04W040/22; H04B 10/2575 20130101 H04B010/2575; H04W 40/20 20090101
H04W040/20; H04B 7/026 20060101 H04B007/026 |
Claims
1. (canceled)
2. A digital unit in a distributed antenna system (DAS), the
digital unit comprising: a radio frequency (RF) port operable to
communicate with a base tranceiver station (BTS); a converter
operable to convert communications to and from the BTS between
analog signals and digital signals; and an optical port operable to
route the digital signals to one or more remote units.
3. The digital unit of claim 1, wherein the RF port is operable to
communicate with the base transceiver station via an antenna.
4. The digital unit of claim 1, wherein the RF port is operable to
communicate with the BTS via a cable.
5. The digital unit of claim 1, wherein the BTS is located remotely
from the digital unit.
6. The digital unit of claim 1, wherein the RF port is operable to
communicate with a sector of the BTS.
7. The digital unit of claim 1, further comprising: an access unit;
and a repeater.
8. The digital unit of claim 7, wherein the access unit is coupled
to the repeater unit via an optical fiber.
9. The digital unit of claim 7, wherein the access unit is operable
to exchange digital signals with the repeater.
10. The digital unit of claim 7, wherein the access unit is
operable to route communications between the repeater and at least
one of the one or more remote units.
11. The digital unit of claim 1, wherein the one or more remote
units are located at different locations than the digital unit.
12. The digital unit of claim 1, wherein the digital unit is
operable to route the digital signals to another digital unit.
13. The digital unit of claim 1, wherein the digital unit is
operable to route the digital signals to another BTS.
14. A system comprising: a digital unit, the digital unit
configured to: communicate with at least one base transceiver
station (BTS); convert communications to and from the at least one
BTS between analog and digital; route digital signals from the
digital unit to another digital unit; and route digital signals
between the at least one BTS and at least one remote unit.
15. The system of claim 14, wherein the digital unit is operable to
communicate with the at least one BTS via at least one of an
antenna or a cable.
16. The system of claim 14, wherein the at least one BTS is located
remotely from the digital unit.
17. The system of claim 14, wherein the digital unit is operable to
communicate with a sector of the BTS.
18. The system of claim 14, wherein the digital unit includes: an
access unit; and a repeater.
19. The system of claim 18, wherein the access unit is coupled to
the repeater unit via an optical fiber.
20. The system of claim 18, wherein the access unit is operable to
exchange digital signals with the repeater.
21. The system of claim 14, wherein the digital unit is operable to
route the digital signals to another digital unit.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/743,789, filed on Jun. 18, 2015; which is a
continuation of U.S. patent application Ser. No. 14/044,668, filed
on Oct. 2, 2013, now U.S. Pat. No. 9,112,549, issued on Aug. 18,
2015; which claims priority to U.S. Provisional Patent Application
No. 61/710,391, filed on Oct. 5, 2012. The disclosures of each are
hereby incorporated by reference in their entirety for all
purposes.
BACKGROUND OF THE INVENTION
[0002] Wireless and mobile network operators face the continuing
challenge of building networks that effectively manage high
data-traffic growth rates. Mobility and an increased level of
multimedia content for end users requires end-to-end network
adaptations that support both new services and the increased demand
for broadband and flat-rate Internet access. One of the most
difficult challenges faced by network operators is maximizing the
capacity of their DAS networks while ensuring cost-effective DAS
deployments and at the same time providing a very high degree of
DAS remote unit availability.
[0003] Despite the progress made in DAS networks, there is a need
in the art for improved methods and systems related to DAS
networks.
SUMMARY OF THE INVENTION
[0004] The present invention generally relates to wireless
communication systems employing Distributed Antenna Systems (DAS)
as part of a distributed wireless network. More specifically, the
present invention relates to a DAS utilizing a software
configurable repeater digital unit (RDU). In a particular
embodiment, the present invention has been applied to optically fed
digital repeaters that can be configured in a star configuration or
a daisy chained configuration. The methods and systems described
herein are applicable to a variety of communications systems
including systems utilizing various communications standards.
[0005] Wireless and mobile network operators face the continuing
challenge of building networks that effectively manage high
data-traffic growth rates. Mobility and an increased level of
multimedia content for end users typically employs end-to-end
network adaptations that support new services and the increased
demand for broadband and flat-rate Internet access.
[0006] A distributed antenna system (DAS) provides an efficient
means of utilization of base station resources. The base station or
base stations associated with a DAS can be located in a central
location and/or facility commonly known as a base station hotel.
The DAS network comprises one or more digital access units (DAUs)
that function as the interface between the base stations and the
digital remote units (DRUs). The DAUs can be collocated with the
base stations. Under certain embodiments the base station resources
may not be collocated with the DAUs. Off-Air Repeaters can be used
to relay remote BTS signals to one or more DAUs. One or more
Off-Air Repeaters can be used to communicate with one or more base
stations. The Off-Air Repeaters relay the RF signals between the
Donor BTS and coverage area.
[0007] Some embodiments may include a system for routing signals in
a Distributed Antenna System (DAS). The system may include a
plurality of base transceiver stations (BTS), each having one or
more sectors, and one or more digital access units (DAUs). The
system may also include a plurality of repeater digital units
(RDUs), where each RDU may be configured to communicate to at least
one of the plurality of BTSs and may be operable to route signals
optically to the one or more DAUs. The system may also include a
plurality of digital remote units (DRUs) located at a location
remote to the one or more DAUs, wherein the plurality of remote
DRUs may be operable to transport signals to the one or more
DAUs.
[0008] In some embodiments, the one or more DAUs may be coupled
together via at least one of Ethernet cable, Optical Fiber,
Microwave Line of Sight Link, Wireless Link, or Satellite Link. In
some embodiments, the plurality of RDUs may be connected to the one
or more DAUs via at least one of Ethernet cable, Optical Fiber,
Microwave Line of Sight Link, Wireless Link, or Satellite Link. In
some embodiments, the plurality of RDUs may be interconnected in a
daisy chain configuration. In other embodiments, the plurality of
RDUs may be connected to one of the one or more DAUs in a star
configuration. In some embodiments, the plurality of RDUs may
include multi-frequency, multi-operator and multi-antenna
characteristics. In some embodiments, the plurality of RDUs may
exhibit multiple input multiple output (MIMO) characteristics.
[0009] Some embodiments may include a method for routing signals in
a Distributed Antenna System (DAS). The method may comprise
receiving at a repeater digital unit (RDU) a radio frequency (RF)
signal from a remote base transceiver station (BTS), converting the
signal from RF to a digital signal, and transporting the digital
signal through an optical cable to a digital access unit (DAU).
Embodiments may also include multiplexing the digital signal, and
routing the multiplexed signal from the DAU to at least one digital
remote unit (DRU). Some embodiments may also include demultiplexing
the digital signal at the least one DRU to regenerate the digital
signal. In some embodiments, the RDU may comprise one or more PEER
ports and one or more LAN ports. In some embodiments, the DAU may
comprise one or more PEER ports and one or more LAN ports.
[0010] Numerous benefits are achieved by way of the present
invention over conventional techniques. Traditionally an Off-Air
Repeater communicates with the donor BTS via a wireless RF signal
and communicates with the coverage area via a wireless RF signal.
Off-Air Repeaters are prone to instability because of their high
gain and RF coupling between the Donor RF port and the Coverage RF
port. A software configurable digital repeater digital unit (RDU)
relays the RF signals to a DAU via an optical cable. The RF signals
from the Off-Air Repeater are transported digitally over an optical
cable to one or more DAUs. This eliminates the instability problems
associated with a traditional Off-Air Repeater as well as enabling
multiple Off-Air Repeaters to be configured in a star or daisy
chain configuration. Transporting the Off-Air Repeater signal from
the donor BTSs optically provides an additional benefit of enabling
multiplexing of multiband signals from multiple Off-Air Repeaters.
Additionally, embodiments enable the routing of the Off-Air
Repeater signals to one or more remote locations. These and other
embodiments of the invention along with many of its advantages and
features are described in more detail in conjunction with the text
below and attached figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a block diagram according to one embodiment
showing a basic structure and an example of the transport routing
based on having a three-sector BTS with 3 Digital Access Units
(DAUs) at a local location, two Repeater Digital Units (RDUs) at a
local location and Digital Remote Units (DRUs) at a remote
location. In embodiments according to FIG. 1, two RDUs are
connected to a DAU at the local location.
[0012] FIG. 2A is a block diagram according to one embodiment
showing a basic structure and an example of the transport routing
based on having a three-sector BTS with 3 DAUs at a local location,
two RDUs daisy chained together at a local location and optical
interfaces to DRUs at the remote locations.
[0013] FIG. 2B is a timing diagram reflecting the framing of the
multiple frequency bands for the uplink and downlink signals
according to some embodiments.
[0014] FIG. 3 is a block diagram according to some embodiments
showing a basic structure and an example of the transport routing
based on having multiple RDUs at local locations with multiple DAUs
at a local location, and multiple Digital Remote Units (DRUs) at a
remote location and optical interfaces to the Remotes.
[0015] FIG. 4 is a block diagram illustrating a DAU, which contains
physical Nodes and a Local Router, according to some
embodiments.
[0016] FIG. 5 is a block diagram illustrating a Repeater Digital
Unit (RDU), which contains physical Nodes and a repeater router,
according to some embodiments.
[0017] FIG. 6 illustrates an example flowchart according to some
embodiments.
[0018] FIG. 7 is an illustration of multiple input-multiple output
(MIMO) configurations, according to some embodiments.
[0019] FIG. 8 is a block diagram according to some embodiments
showing a basic structure and an example of the transport routing
based on having multiple MIMO (multiple input-multiple output) RDUs
at local locations with multiple DAUs at a local location, and
multiple Digital Remote Units (DRUs) at a remote location and
optical interfaces to the Remotes.
DETAILED DESCRIPTION
[0020] Embodiments may be drawn to off air repeaters, which are
telecommunications repeaters that take a signal "off air," but
"over the air." Traditionally, repeaters in the prior art may be
coupled to base transceiver stations (BTS) via radio frequency (RF)
cable. Typically, all communications to and from repeaters in the
prior art may occur via RF. There may be several problems to the
traditional approach of repeaters. One problem may be that feedback
may occur from the RF cable connecting the repeaters to the antenna
at the BTS. This feedback may cause signal oscillations, which
results in co-channel interference. Another problem may be that the
quality of the signal may degrade over longer distances of RF
cable, due to cable losses over longer distances.
[0021] In addition, in traditional configurations having a base
station in an enclosed, less accessible area, e.g. a basement, only
some telecommunications operators--e.g. AT&T, Verizon,
etc.--may own base stations in that enclosed area. Other operators,
e.g. Sprint or T-Mobile, may not own base stations housed in that
same area, but instead may own base stations that are at some
remote location, e.g. locations 2 kilometers away. Users near the
basement--e.g. users in the same building above the basement--with
subscriptions to AT&T and Verizon should have superior
reception compared to users near the basement with subscriptions to
Sprint or T-Mobile. It may be desirable then for operators of
remote base stations to be able to access the base stations in the
basement, rather than build their own base stations and spend more
resources in the process. It may also be desirable to transmit
signals from the remote BTSs to the local source in a reliable and
efficient manner, without loss of signal quality and minimal
interference.
[0022] An off air repeater according to embodiments may help solve
at least these problems. Embodiments may allow remote BTSs
physically located away from a local source of users to be able to
provide local service as if the remote BTSs were at or near the
local source of users. In some embodiments, base stations may be
housed in areas that are less accessible, e.g. in a basement of a
building. In this context, some embodiments may house a rack of
digital access units (DAUs) close to the base station which may be
coupled via RF cable. Embodiments may utilize an off-air repeater,
or a repeater digital unit (RDU), to route signals from the remote
BTSs over the air to at least one DAU (e.g. a rack of DAUs) housed
near the local source of users (e.g. the basement in the building
of the users). RDUs of some embodiments may receive the Downlink RF
signal from a donor/remote BTS, amplify and filter the RF signal
and then re-transmit it to a coverage area. The coverage area may
be outdoors or indoors. The uplink signal from the coverage area
may be amplified, filtered and re-transmitted to the donor/remote
BTS. A traditional repeater has one or more RF input ports and RF
output ports. Using RF cables between the Repeater and indoor
antennas facilitates indoor coverage. Embodiments may utilize
optical cable, instead of RF, connecting from the RDUs to the at
least one DAU. The optical cabling may allow for digital
transmission of signals between the remote BTSs and the at least
one DAU. Once signals reach the at least one DAU, they can be
routed to various digital remote units (DRUs), which may provide
close reception to the local source of users.
[0023] As previously mentioned, embodiments may utilize RDUs
connected by optical cabling, rather than RF cabling, to transport
signals. Advantages may include, for example, eliminating
co-channel interference. Another may be having the ability to
multiplex the RF signal due to transporting the signal digitally.
Another advantage may be reducing or eliminating signal degradation
due to transporting the signal digitally. Also, embodiments may be
distinguishable from traditional systems with repeaters in that the
downlink and uplink signal directions between RDUs and DRUs may be
reversed. For example, signals coming from an RDU, going down to a
DAU and then being routed to DRUs may traditionally be downlink
signals. In contrast, embodiments have the ability to reverse the
direction of the downlink and uplink signals in the DAU.
[0024] FIG. 1 may illustrate a distributed antenna system (DAS)
network architecture according to some embodiments of the present
invention. A DAS according to some embodiments may provide an
efficient means of utilization of base station resources. The base
station or base stations associated with a DAS can be located in a
central location and/or facility commonly known as a base station
hotel. The DAS network comprises one or more digital access units
(DAUs) that function as the interface between the base stations and
the digital remote units (DRUs). The DAUs can be collocated with
the base stations. The DRUs can be daisy chained together and/or
placed in a star configuration and provide coverage for a given
geographical area. The DRUs may be connected with the DAUs by
employing a high-speed optical fiber link. This approach may
facilitate transport of the RF signals from the base stations to a
remote location or area served by the DRUs. A base station may
comprise three independent radio resources, commonly known as
sectors. These three sectors may be used to cover three separate
geographical areas without creating co-channel interference between
users in the three distinct sectors. In other embodiments,
additional sectors are associated with each BTS, for example, up to
or more than twelve sectors.
[0025] Here, FIG. 1 provides an example of a data transport
scenario between a three-sector Base Station, multiple local DAUs,
multiple Repeater Digital Units (RDUs) and multiple DRUs. BTS1 100
is connected to DAU1 102, DAU2 108, and DAU3 111 (i.e., local DAUs)
by an RF cable in the illustrated embodiment. BTS2 130 and BTS3 140
communicate Off-Air RF signals with RDU1 120 and RDU2 121,
respectively. Each of the local DAUs is connected to server 150. In
FIG. 1, the RDUs are connected in a star configuration with DAU1
102 using optical cables. The following descriptions provide
additional detail to several different features in FIG. 1 according
to some embodiments.
[0026] Still referring to FIG. 1, multiple RDUs, e.g. RDU1 120 and
RDU2 121, may be placed in varying locations while being connected
to the same DAU1 102. Each RDU may provide repeater service to a
different BTS, e.g. RDU1 120 provides repeater service for BTS2 130
to DAU1 102, and RDU2 121 provides repeater service for BTS3 to
DAU1 102. Multiple RDUs servicing multiple remote BTSs may be
beneficial for several reasons. For example, the DAUs 102, 108,
111. may be housed in a building, and a telecommunications
operator, e.g. Sprint, may have a remote BTS located west of the
building, a few kilometers away. Thus, it would be desirable to
have an antenna on the top of the building facing west. At the same
time, another telecommunications operator, e.g. T-Mobile, may have
a base station that is north of the building. Thus, it would be
beneficial to have two different repeaters communicating with those
different base stations, one for the northern located BTS and the
other for the western located BTS. Other benefits may include an
ability for multiple telecommunications operators to have more
exclusive control and access with different RDUs. Other benefits
may include reducing resources needed to optimally service multiple
operators.
[0027] Some embodiments include the ability to route the local Base
Station 100 and remote Base Stations 130, 140 radio resources,
among the RDUs and DAUs. In order to route radio resources
available from one or more Base Stations, it may be desirable to
configure the individual router tables of the DAUs and RDUs in the
DAS network. This functionality may be provided by some
embodiments.
[0028] Still referring to FIG. 1, the DAUs may be networked
together to facilitate the routing of signals among multiple DAUs.
The DAUs may support the transport of the RF downlink and RF uplink
signals between the BTSs and the various DAUs. This architecture
may enable the various BTS signals to be transported simultaneously
to and from multiple DAUs. PEER ports are used for interconnecting
DAUs. PEER ports may be discussed in more detail in later
paragraphs of this disclosure.
[0029] The DAUs may have the capability to control the gain (in
small increments over a wide range) of the downlink and uplink
signals that are transported between the DAU and the base station
(or base stations) connected to that DAU. This capability may
provide flexibility to simultaneously control the uplink and
downlink connectivity of the path between a particular RDU (or a
group of RDUs) and a particular base station.
[0030] The DAU may communicate with a Network Operational Control
(NOC). The NOC sends commands and receives information from the DAS
network. The DAS network can include a plurality of DAUs, RDUs and
DRUs. The DAU communicates with the network of DRUs and the DAU
sends commands and receives information from the DRUs. The DAUs
include physical nodes that accept and deliver RF signals and
optical nodes that transport data. A DAU can include an internal
server or an external server. The server is used to archive
information in a database, store the DAS network configuration
information, and perform various traffic related processing. The
server can be used to communicate information from the DAS Network
to the NOC.
[0031] Additionally, an RDU may communicate with a DAU or rack of
DAUs. In some embodiments, the RDU does not communicate with the
NOC. The RDU receives commands from the DAU and delivers
information to the DAU. The RDUs include physical nodes that accept
and deliver RF signals and optical nodes that transport data.
[0032] As previously mentioned, BTS1 100 may be separated into a
plurality of sectors. In this case, BTS1 100 shows three sectors:
sector 1 101, sector 2 109, and sector 3 110. Each sector may be
associated with at least one antenna on top of at least one tower,
each antenna connected to typically an RF cable that would connect
to BTS1 100. Each antenna would provide signal coverage up to some
angle, e.g. 120 degrees, around BTS1 100. Thus, when combining all
three sectors, BTS1 100 may provide 360 degrees of signal
coverage.
[0033] Each sector may be connected via RF cable to a DAU. In this
case, sector 1 101 is connected to DAU1 102, sector 2 109 is
connected via RF cable to DAU2 108, and sector 3 110 is connected
via RF cable to DAU3 111. In other embodiments, the sectors may be
connected to the same DAU. In some embodiments, each DAU may be
owned by a different telecommunications operator, allowing each
operator to control information of its subscribers. Each DAU may
also contain a neutral host that allows other operators to transmit
their information and signals to DAUs they do not control.
[0034] As alluded to above, embodiments may allow for different
telecommunications operators with remote base stations to provide
stronger signal coverage to a local building containing the DAS
architecture according to some embodiments described herein. For
example, say Verizon owns BTS2 130, and T-Mobile owns BTS3 140, but
Metro PCS owns BTS1 100 and Verizon and T-Mobile do not normally
have access to BTS1 100. However, both Verizon and T-Mobile want
coverage in the building housing BTS1 100. Transmitting signals
just from their respective BTSs 130, 140, Verizon and T-Mobile may
be able to provide only weak signal coverage to the building
because the building is several kilometers from their respective
BTSs 130, 140. Using various embodiments of the present invention,
however, the RDUs connecting the BTSs 130, 140 may allow Verizon
and T-Mobile to provide coverage to the building with a signal
strength just as strong as Metro PCS.
[0035] Embodiments may connect the DAUs to various cells of DRUs to
complete the configuration of supplying signals of different
operators from remote BTSs to their customers or users. In this
case, cell 1 105, cell 2 106, and cell 3 107 may contain a "flower"
arrangement of DRUs, which may be located in the building. Thus,
each operator may provide strong coverage to all of the users that
cell 1 105, cell 2 106, and cell 3 107 provide coverage for, even
though some other operator's BTSs are located far away.
[0036] In FIG. 1, server 150 is shown to be connected to the three
DAUs 102, 108, and 111. In some embodiments, a server 150 may
provision all the DRUs, all the DAUs and the RDUs to be configured
as needed. In essence, server 150 may act like a network management
server. In other embodiments, server 150 may configure how the DAS
is going to be set up. Each DAU, DRU, and RDU may contain a series
of ports that are configurable, depending on need and function.
Server 150 may facilitate designation of what each port is supposed
to function as. For example, a port may act as a PEER port, or a
LAN port, and server 150 may designate that. In another example,
server 150 may configure the DRUs because some of the DRUs may only
be able to transmit certain bands. An example description of the
hardware configurations will be described in later figures.
[0037] In addition, FIG. 1 may show a star configuration of RDUs,
in that each RDUs is connected to the same DAU1 102. In this case,
signals in different frequency bands and with different frequencies
within the same frequency band may be summed in DAU1 102 to create
a single composite signal when transmitted to the various cells.
The signals can then be separated using traditional filtering
techniques, knowing that the signals each originate in different
frequencies. A benefit to having a star configuration of RDUs may
be where the BTSs are located if different geographic
locations.
[0038] Referring to FIG. 2A, the individual base station radio
resources from BTS2 230, BTS3 231 and BTS4 232 are transported to a
daisy-chained network of RDUs. Each individual BTS radio resources
provide coverage to an independent geographical area. FIG. 2A
demonstrates how three independent BTSs, each BTS communicating
with an independent RDU, provide input into a single DAU while the
RDUs are connected in a daisy-chained configuration. A server 240
may be utilized to control the routing function provided in the DAS
network, and may function similarly to server 150 described in FIG.
1.
[0039] Referring to FIG. 2A and by way of example, DAU1 202 may
receive downlink signals and may transmit uplink signals from and
to the daisy chained network of RDUs 220, 221, 222. RDU1 220 may
translate the RF signals to optical signals for the downlink and
may translate the optical signals to RF signals for the uplink. The
optical fiber cable 224 may transport the BTS2 230 signals between
RDU1 221 and RDU2 222. The optical signals from RDU1 221 and RDU2
222 may be multiplexed on optical fiber cable 225. The other RDUs
in the daisy chain may be involved in passing the optical signals
onward to DAU1 202. DAU1 202, DAU2 208 and DAU3 211 may transport
the optical signals to and from the network of DRUs, at cells 1
205, 2 206, and 3 207.
[0040] Benefits of daisy chaining RDUs according to some
embodiments may include connecting multiple RDUs in near proximity
to each other with minimal cabling. In addition, another RDU may be
easily connected in the daisy chain with minimal cabling.
[0041] An RDU communicates over the air with a base station (BTS).
The base station is generally specific to a given operator. The RDU
is required to frequency select via a digital filter the band
allocated to that given operator and reject signals from other
operators. This approach is required to insure that another
operator's signal is not transported to the venue. The RDU will
contain a digital bandpass filter for the receive as well as the
transmit paths. The installer will select the digital bandpass
filters.
[0042] Referring to FIG. 2B, timing schematics 250 and 251 show
example timing diagrams for different frequency bands for the
uplink signals and downlink signals. Each frequency band is
allocated a time slot and the signals are time multiplexed
together. The same principles may hold true for the upstream frames
shown in timing schematic 251. These principles may be consistent
with the multiplexing examples described in any of the disclosures
herein. The time divisions may be of any evenly divided lengths,
and embodiments are not so limited.
[0043] Referring to FIG. 3, a DAS system employing multiple
Repeater Digital Units (RDUs) at the local location and multiple
Digital Remote Units (DRUs) at the remote location may be depicted
according to some embodiments. In some embodiments, each RDU may
provide unique information associated with each RDU, which uniquely
identifies data received and transmitted by a particular Digital
Remote Unit. In some embodiments consistent with FIG. 3, the
individual RDUs may be independently connected to DAUs. FIG. 3 may
show how some embodiments may have separate RDUs connected directly
to a separate DAU, in neither a daisy chain or a star
configuration. Such embodiments may be useful when operators desire
their own separate connection from their BTS to the subscribers
within the DRU cells, e.g. cell 1 305, cell 2 306, or cell 3
307.
[0044] The servers illustrated herein, for example, server 350, may
provide unique functionality in the systems described herein. The
following discussion related to server 350 may also be applicable
to other servers discussed herein an illustrated in the figures.
Server 350 can be used to set up the switching matrices to allow
the routing of signals between the remote DRUs. The server 350 can
also store configuration information, for example, if the system
gets powered down or one DRU or RDU goes off-line and then you
power up the system, it will typically need to be reconfigured. The
server 350 can store the information used in reconfiguring the
system and/or the DRUs, RDUs or DAUs.
[0045] Another advantage of embodiments according to FIG. 3 may be
that all signals occur off air. In other words, there is no BTSs
connected via RF cable. For example, an operator like AT&T may
not want to share anything with another operator, like Verizon.
Each operator may want their own equipment. With their own
equipment, each operator may control the power levels and other
configurable parameters.
[0046] While each operator may have their own equipment according
to FIG. 3, there may still be value in connecting each DAU to each
other, also shown in FIG. 3. For example, routing signals from one
DAU to another may still be desired. This may be because, for
example, the DRU cells as shown in FIG. 3 may be connected via
optical cable to only one of the three DAUs. Each DRU cell may
provide coverage to different geographic areas, and each operator
may still desire to provide coverage to all three areas. Thus, any
or every BTS may still want to have access to the different cells,
which in this case may require a connection to each DAU. In cases
like these, a neutral host built into the DAUs may provide access
from the different DAUs to the DRU cells without interfering with
each operator's own telecommunications operations. A neutral host
may itself be a repeater, not unlike the RDUs described in the
present disclosures.
[0047] Thus, in some embodiments, the repeater concept familiar to
those with ordinary skill in the art may be redistributed into at
least two repeater elements, according embodiments consistent with
FIG. 3. Persons of ordinary skill in the art may observe that RDU1
321 and DRU16 together may act as a repeater in the traditional
sense. This is because RF is coming into the RDUs, and RF is going
out of the DRUs, which may be what a traditional repeater may
behave like. Of course, the bifurcation of the repeater concept may
not be trivial or obvious without the present disclosures.
[0048] FIG. 4 may show two elements in a DAU, the Physical Nodes
400 and the Local Router 401. The Physical Nodes translate the RF
signals to baseband for the Downlink and from baseband to RF for
the Uplink. The local Router directs the traffic between the
various LAN Ports, PEER Ports and the External Ports. The physical
nodes connect to the BTS at radio frequencies (RF). The physical
nodes can be used for different operators, different frequency
bands, different channels, or the like. The physical nodes can
combine the downlink and uplink signals via a duplexer or they can
keep them separate, as would be the case for a simplex
configuration.
[0049] FIG. 4 may illustrate a digital access unit (DAU) according
to some embodiments whereby the physical nodes have separate
outputs for the uplinks 405 and separate inputs for the downlink
paths 404. A DAU consistent with FIG. 4 may serve as one of the
DAUs found in any of FIG. 1, 2, or 3. The physical node may
translate the signals from RF to baseband for the downlink path and
from baseband to RF for the uplink path. The physical nodes are
connected to a local Router via external ports 409, 410. The router
may direct the uplink data stream from the LAN and PEER ports (e.g.
LAN Port 1, LAN Port 2, PEER Port M, etc.) to the selected External
U ports. Similarly, the router directs the downlink data stream
from the External D ports to the selected LAN and PEER ports.
[0050] Embodiments may vary or reconfigure which ports 401 may be
LAN or PEER. FIG. 4 is merely one example, and many other
configurations are possible according to embodiments of the present
invention. DAUs of some embodiments may be reconfigurable in this
sense in order to adapt to the various DAS configurations possible,
examples of which may include FIGS. 1, 2, and 3.
[0051] A difference between a LAN port and a PEER port may be that
a LAN port would have the downlink signal going out, and the uplink
signal coming back. A PEER port would be the exact opposite. It
would have the downlink signal coming into the DAU, and the uplink
signal going out of it. Thus, when provisioning the DAU, for
example, assume that there is a repeater RDU1 connected to PEER
port M. If is it known there is a repeater there, then it may be
understood that a PEER connection must be established. Thus, the
port is designated as a PEER port. In contrast, a LAN port, e.g.
LAN port 1, may connect up to the daisy chain of DRUs, as shown in
FIGS. 1, 2, and 3.
[0052] As another example, PEER ports may provide the connection
between DAU1 102 and DAU2 108 of FIG. 1, which may be represented
as the two-way arrow between the DAUs 102 and 108 according to the
figures. In another example, PEER ports may be used to daisy chain
the DAUs together.
[0053] Referring again to FIG. 4, in some embodiments, the LAN and
PEER ports may be connected via an optical fiber to a network of
DAUs and DRUs. The network connection can also use copper
interconnections such as CAT 5 or 6 cabling, or other suitable
interconnection equipment. The DAU is also connected to the
internet network using IP 406. An Ethernet connection 408 is also
used to communicate between the Host Unit 402 and the DAU. The DRU
and RDU can also connect directly to the Remote Operational Control
center 407 via the Ethernet port. Again, these descriptions may be
consistent with the DAUs shown in FIGS. 1, 2, and 3.
[0054] FIG. 5 may show two elements in a repeater digital unit
(RDU) according to some embodiments: the Physical Nodes 501 and the
Repeater Router 500. The RDU may include both a Repeater Router and
Physical Nodes. The Repeater Router may direct the traffic between
the LAN ports, External Ports and PEER Ports. The physical nodes
may connect wirelessly to the BTS at radio frequencies (RF). The
physical nodes can be used for different operators, different
frequency bands, different channels, different antennas, etc. FIG.
5 shows an embodiment whereby the physical nodes have separate
inputs for the uplinks 504 and separate outputs for the downlink
paths 503. A physical node may translate signals from RF to
baseband for the uplink path and from baseband to RF for the
downlink path. The physical nodes are connected to a Repeater
Router via external ports 506, 507. The router may direct the
downlink data stream from the LAN and PEER ports to the selected
External D ports. Similarly, the router directs the uplink data
stream from the External U ports to the selected LAN and PEER
ports. The RDU may also contain an Ethernet Switch 505 so that a
remote computer or wireless access points can connect to the
internet.
[0055] In some embodiments, the RDUs each have an amplifier to send
out the uplink signal down to a BTS. For example, in FIG. 1, an
amplifier in RDU1 120 may be included to send that signal out to
BTS2 130. In DRU16, the amplifier is actually in the downlink path.
Thus, structurally a larger amplifier on the different uplink for
the repeater may be needed as opposed to the downlink for the
DRU16. Thus, one difference to note between a RDU and a DRU may be
that the uplink and downlink signals are reversed in a RDU compared
to a DRU, and vice versa. That is, the downlink signals come in to
a DRU, while the downlink signals go out of the RDU.
[0056] In some embodiments, a RDU and a DAU may be constructed
quite similarly, such that a single platform may easily switch from
being configured as a RDU to a DAU. Such a construction may be
another benefit according to some embodiments, allowing for
flexibility, cost efficiency, elegant design and ease of
replacement, among other advantages.
[0057] In some embodiments, the DAU may be connected to a host
unit/server, whereas the RDU may not connect to a host unit/server.
In these embodiments, parameter changes for the RDU may be received
from a DAU, with the central unit that updates and reconfigures the
RDU being part of the DAU, which can be connected to the host
unit/server. Embodiments of the present invention are not limited
to these embodiments, which are described only for explanatory
purposes.
[0058] Referring to FIG. 6, example flowchart 600 shows example
method steps according to some embodiments. At block 610,
embodiments may receive at a repeater digital unit (RDU) a radio
frequency (RF) signal from a remote base transceiver station (BTS).
Example processes of block 610 may be consistent with any of the
descriptions in FIGS. 1, 2, and 3 related to receiving signals at
any RDU described. Returning to FIG. 6, at block 612, embodiments
may convert the signal from RF to a digital signal. The conversion
may occur in the RDU, consistent with descriptions in FIG. 5, for
example. Returning to FIG. 6, signal processing of the digital
signal will occur at block 613. The signal processing may include
filtering, data compression, frequency translation, etc. At block
614, embodiments may transport the digital signal through an
optical cable to a digital access unit (DAU). Again, FIGS. 1, 2,
and 3 may show examples of this transportation. Returning to FIG.
6, block 616, embodiments may multiplex the digital signal.
[0059] Examples of multiplexing the digital signal may include
combining two or more signals that occur at different frequencies
or frequency bands. For example, a first operator, e.g. AT&T
may transmit a first signal via a first BTS with a first frequency.
A second operator, e.g. Verizon, may transmit a second signal via a
second BTS with a second frequency different than the first. The
two signals may be multiplexed such that a single combined signal
contains information sufficient to filter out the two original
signals at a later time and place. These descriptions may be
consistent with those discussed in FIGS. 1, 2, and 3. In FIG. 6, at
block 618, embodiments may route the multiplexed signal from the
DAU to at least one digital remote unit (DRU). The routing may be
sent over optical cable or Ethernet cable, for example. These
descriptions may be consistent with those found in FIGS. 1, 2, and
3.
[0060] Additionally, some embodiments may include that the RF
signal from the remote base station has a downlink and an uplink.
Some embodiments may include that the RDU and/or the DAU has PEER
ports and LAN ports. PEER ports may be distinguished from LAN ports
based on which path to and from the RDU and/or DAU is designated as
a downlink path versus an uplink path.
[0061] FIG. 7 is an illustration 700 of a multiple input-multiple
output (MIMO) configuration. The number of transmit (Tx) antennas
and receive (Rx) antennas will determine the classification of the
system. MIMO systems can be expanded to N Transmit antennas and M
Receive antennas, where N and M are integers greater than one.
[0062] FIG. 8 demonstrates the application of a MIMO repeater, RDU1
820, according to some embodiments. Also shown is another MIMO
repeater RDU2 821. A MIMO repeater according to some embodiments
interfaces with a DAU before the signal is transported out to the
remote units. The MIMO RDUs can be cascaded together at the DAU as
shown in FIG. 8 or they could be daisy-chained together. Each
antenna in a MIMO RDU may be treated as a separate frequency band,
and thus MIMO signals transmitted to and received from the DAU,
e.g. DAU1 802, may be similarly time division multiplexed, as
described in the disclosures above. For example, extra time slots
for the signals from the additional antennas may be provided as
information travels through the optical cables 823 and 824. In some
embodiments, no other configurations need to be modified in
comparison to non-MIMO RDUs.
[0063] It is also understood that the examples and embodiments
described herein are for illustrative purposes only and that
various modifications or changes in light thereof will be suggested
to persons skilled in the art and are to be included within the
spirit and purview of this application and scope of the appended
claims.
GLOSSARY OF TERMS
[0064] ACLR Adjacent Channel Leakage Ratio [0065] ACPR Adjacent
Channel Power Ratio [0066] ADC Analog to Digital Converter [0067]
AQDM Analog Quadrature Demodulator [0068] AQM Analog Quadrature
Modulator [0069] AQDMC Analog Quadrature Demodulator Corrector
[0070] AQMC Analog Quadrature Modulator Corrector [0071] BPF
Bandpass Filter [0072] BTS Base Transceiver Station [0073] CDMA
Code Division Multiple Access [0074] CFR Crest Factor Reduction
[0075] DAC Digital to Analog Converter [0076] DAS Distributed
Antenna System [0077] DAU Digital Access Unit [0078] DET Detector
[0079] DHMPA Digital Hybrid Mode Power Amplifier [0080] DDC Digital
Down Converter [0081] DNC Down Converter [0082] DPA Doherty Power
Amplifier [0083] DQDM Digital Quadrature Demodulator [0084] DQM
Digital Quadrature Modulator [0085] DRU Digital Remote Unit [0086]
DSP Digital Signal Processing [0087] DUC Digital Up Converter
[0088] EER Envelope Elimination and Restoration [0089] EF Envelope
Following [0090] ET Envelope Tracking [0091] EVM Error Vector
Magnitude [0092] FFLPA Feedforward Linear Power Amplifier [0093]
FIR Finite Impulse Response [0094] FPGA Field-Programmable Gate
Array [0095] GSM Global System for Mobile communications [0096] I-Q
In-phase/Quadrature [0097] IF Intermediate Frequency [0098] LINC
Linear Amplification using Nonlinear Components [0099] LO Local
Oscillator [0100] LPF Low Pass Filter [0101] MCPA Multi-Carrier
Power Amplifier [0102] MDS Multi-Directional Search [0103] MIMO
Multiple Input Multiple Output [0104] OFDM Orthogonal Frequency
Division Multiplexing [0105] PA Power Amplifier [0106] PAPR
Peak-to-Average Power Ratio [0107] PD Digital Baseband
Predistortion [0108] PLL Phase Locked Loop [0109] QAM Quadrature
Amplitude Modulation [0110] QPSK Quadrature Phase Shift Keying
[0111] RF Radio Frequency [0112] RDU Repeater Digital Unit [0113]
RRH Remote Radio Head [0114] RRU Remote Radio Head Unit [0115] SAW
Surface Acoustic Wave Filter [0116] UMTS Universal Mobile
Telecommunications System [0117] UPC Up Converter [0118] WCDMA
Wideband Code Division Multiple Access [0119] WLAN Wireless Local
Area Network
* * * * *