U.S. patent application number 17/009651 was filed with the patent office on 2020-12-24 for inter-cell interference mitigation.
The applicant listed for this patent is Parallel Wireless, Inc.. Invention is credited to Kaitki Agarwal, Yang Cao, Prashanth Rao.
Application Number | 20200404596 17/009651 |
Document ID | / |
Family ID | 1000005063168 |
Filed Date | 2020-12-24 |
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United States Patent
Application |
20200404596 |
Kind Code |
A1 |
Rao; Prashanth ; et
al. |
December 24, 2020 |
Inter-Cell Interference Mitigation
Abstract
To address the problem of inter-cell interference in a
heterogeneous network, several methods and systems are disclosed
for determining interference caused by an aggressor mobile node,
and transmitting at appropriate times and with transmit power that
does not cause interference. Methods disclosed include using X2
communications, such as HII and RNTP messages, switching to an
alternative radio access technology, sniffing at the eNodeB to
obtain information, coordinating with a cloud coordination server,
and using CFI information to avoid interfering with communications
on the PDCCH.
Inventors: |
Rao; Prashanth; (Wilmington,
MA) ; Cao; Yang; (Westford, MA) ; Agarwal;
Kaitki; (Westford, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Parallel Wireless, Inc. |
Nashua |
NH |
US |
|
|
Family ID: |
1000005063168 |
Appl. No.: |
17/009651 |
Filed: |
September 1, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14828432 |
Aug 17, 2015 |
10772051 |
|
|
17009651 |
|
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62037982 |
Aug 15, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 52/40 20130101;
H04W 84/12 20130101; H04W 48/18 20130101; H04W 36/22 20130101; H04W
88/06 20130101; H04W 52/243 20130101 |
International
Class: |
H04W 52/40 20060101
H04W052/40; H04W 48/18 20060101 H04W048/18; H04W 52/24 20060101
H04W052/24 |
Claims
1. A method for reducing uplink interference at a first base
station, comprising: assessing frequency resources shared between
the first and a second base station to determine frequency
resources that cause reduced interference at the first base station
in comparison to other shared uplink frequency resources.
determining whether mobile devices connected to the first base
station may be switched to a Wi-Fi connection; and switching
services provided to the mobile devices to a Wi-Fi connection
between the mobile devices and the first base station.
2. The method of claim 1, further comprising determining whether
each mobile device of the mobile devices is capable of using
Wi-Fi.
3. The method of claim 1, further comprising determining whether
each mobile device of the mobile devices is within a Wi-Fi-capable
range.
4. The method of claim 1, further comprising determining whether
radio frequency resources are available for using Wi-Fi.
5. The method of claim 1, further comprising determining at a
controller whether to switch to Wi-Fi based on one or more of: a
number of mobile devices already attached to the first base station
on Wi-Fi; bandwidth required for switching a specific mobile device
to Wi-Fi; backhaul network capacity; system load; and a relative
load of one or more base stations.
6. A method for reducing interference at a first base station,
comprising: at the first base station, sniffing shared frequency
resources on the uplink of a second base station; and based on the
sniffed frequency resources, identifying low interference resources
for uplink scheduling use by the first base station.
7. The method of claim 6, wherein sniffing frequency resources
further comprises: receiving signals over a plurality of radio
frequency bands; and performing power spectral density analysis
over the plurality of radio frequency bands.
8. The method of claim 6, further comprising sniffing frequency
resources at intervals over a period of time.
9. The method of claim 6, wherein sniffing frequency resources is
performed at a digital signal processor at the first base
station.
10. The method of claim 6, further comprising transmitting an
overload indicator (OI) message via an X2 protocol from the first
base station to the second base station to cause the second base
station to reduce transmission power.
11. The method of claim 6, wherein the first base station in
coordination with a controller determines whether mobile devices
connected to the first base station may be switched to a Wi-Fi
connection.
12. A method for reducing uplink interference at a second base
station, comprising: receiving, at a first base station,
measurement information from one or more of a mobile device
attached to the first base station; and based on the received
measurement information and on a coverage radius of the first base
station, sending a power configuration message to the mobile device
to limit the transmit power of signals from the mobile device to
the first base station.
13. The method of claim 12, the measurement information further
comprising measurement reports received from a user equipment and
system information block messages from the second base station.
14. The method of claim 12, further comprising sending a power
configuration message to the mobile device to limit a ratio of
transmission power and noise to below a specific threshold for
transmissions from the mobile device.
15. The method of claim 12, wherein the first base station
determines, in coordination with a controller, whether mobile
devices connected to the mobile base station may be switched to a
Wi-Fi connection.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of, and claims
the benefit under 35 U.S.C. .sctn. 120 of, U.S. patent application
Ser. No. 14/828,432, having attorney docket no. PWS-71771US01,
filed Aug. 17, 2015 and entitled "Inter-Cell Interference
Mitigation," which itself claims the benefit of priority under 35
U.S.C. .sctn. 119(e) of U.S. Provisional Patent Application Nos.
62/037,982, having attorney docket no. PWS-71771U500, filed Aug.
15, 2014, and entitled "Inter-Cell Interference Mitigation," each
of which is hereby incorporated by reference in its entirety for
all purposes. Additionally, U.S. Pat. App. Pub. Nos. US20140086120,
US20140092765, US20140133456, US20150045063, and US20150078167 are
hereby incorporated by reference in their entirety for all
purposes.
TECHNICAL FIELD
[0002] This disclosure relates to wireless base stations and mesh
networks. More specifically, this disclosure relates to reducing
inter-cell interference at a base station.
BACKGROUND
[0003] In deployment of cellular radio networks, a base station is
needed to be placed for each region that requires coverage. Prior
deployment strategies assumed a regular cell topology, resulting in
the emplacement of radio base stations according to a strict
geometric pattern. However, in real-world deployments,
identically-sized cells are ill-suited to providing effective
coverage because of topological features (i.e., mountains, hills,
highways, etc.), and because of varying population density
patterns, among other reasons.
[0004] To handle these varying characteristics, strategies
involving multiple cell sizes have been proposed. For example, a
traditional macro cell base station may be used to cover a
relatively large area, but may be supplemented in an area of
increased population density by a micro-cell (covering a smaller
area than a macro-cell), a femto-cell (covering a smaller area than
a micro-cell, such as a single building), or a mobile base
station.
[0005] However, integration of these base stations of various sizes
causes interference between cells. This is particularly true
because micro-cells and other smaller cells are often placed in a
location that overlaps substantially or completely with the
coverage area of a macro cell. The micro cell base station and the
macro cell base station may end up competing for radio resources
and reducing the effectiveness of attached mobile nodes via
inter-cell interference. Techniques are needed to cancel this
interference and to enable multiple cells to coexist and provide
enhanced service.
SUMMARY
[0006] To address the problem of inter-cell interference in a
heterogeneous network, several methods and systems are disclosed
for determining interference caused by an aggressor mobile node,
and transmitting at appropriate times and with transmit power that
does not cause interference. Methods disclosed include using X2
communications, such as HII and RNTP messages, switching to an
alternative radio access technology, sniffing at the eNodeB to
obtain information, coordinating with a cloud coordination server,
and using CFI information to avoid interfering with communications
on the PDCCH.
BRIEF DESCRIPTION OF DRAWINGS
[0007] FIG. 1 illustrates a schematic diagram of four interference
scenarios.
[0008] FIG. 2 depicts an example usage pattern of a subframe.
[0009] FIG. 3 is a block diagram of hardware and/or software used
in some embodiments.
DETAILED DESCRIPTION
[0010] Four scenarios for interference mitigation, for mitigating
four types of interference, are described. Each of the four
scenarios may occur at the same time, or may occur separately. For
purposes of the below disclosure, a macro cell base station may be
provided that does not perform interference mitigation, and a
mobile eNodeB may be provided that is enhanced with the mitigation
techniques and methods described herein. A user equipment (UE) that
causes interference may be called an aggressor, and a UE that is
subject to interference may be called a victim, in some aspects of
the below disclosure.
[0011] FIG. 1 illustrates a schematic diagram of four interference
scenarios. Macro eNodeB 101 has coverage area 102, and micro eNodeB
103 has coverage area 104. UEs 105, 106, 107, 108 are located in
coverage area 102. UEs 106 and 108 are additionally located in
coverage area 104. Coordinating node 109 is in communication with
eNodeBs 101 and 103 via the X2 protocol, represented by a
dot-dashed line. Each of the UEs illustrates a different
interference scenario. Desired signals are shown as solid lines and
interfering signals are shown as dotted lines.
[0012] In a first scenario, UE 105 is attached to (associated with)
a macro eNodeB and transmits data to the macro eNodeB, which
generates interference on the uplink band for UEs attached to a
nearby micro eNodeB. In a second scenario, UE 106 is attached to a
micro cell eNodeB and transmits data to the micro cell eNodeB,
which generates interference on the uplink band for UEs attached to
a nearby macro cell eNodeB. In a third scenario, UE 107 is attached
to a macro cell eNodeB and receives data from the macro cell
eNodeB, which generates interference on the downlink band for UEs
attached to a nearby micro cell eNodeB. In a fourth scenario, UE
108 is attached to a micro cell eNodeB and receives data from the
micro cell eNodeB, which generates interference on the downlink
band for UEs attached to a nearby macro cell eNodeB.
[0013] Turning to the first scenario, a UE is attached to
(associated with) a macro eNodeB and transmits data to the macro
eNodeB, which generates interference on the uplink band for UEs
attached to a nearby micro eNodeB.
[0014] In one embodiment, an X2 protocol-based coordination scheme
may be used to preventively address the uplink interference.
Various messages may be used by an eNodeB to share interference
information with other eNodeBs, including relative narrowband
transmit power indicator (RNTP) messages for downlink channels and
high interference indicator (HII) messages for uplink channels. An
HII message is a bitmap that indicates, with one bit per physical
resource block (PRB) in the uplink, indicating that eNodeBs in the
neighborhood should expect a high-interference power event in the
near future.
[0015] In the case that a micro cell eNodeB receives an HII message
from the macro cell, the micro cell eNodeB may avoid using the
uplink physical resource related to the identified PRB in the next
time window, which may be a transport time interval (TTI).
[0016] In one embodiment, the macro cell eNodeB can identify
potential interfering UEs by using UE measurements, such as based
on signal measurements sent by the UE as scheduled UE measurement
reports. The macro cell eNodeB may, after identifying interfering
UEs, send a HII message to neighboring eNodeBs via the X2
protocol.
[0017] In another embodiment, a coordinated reactive solution is
provided in which a micro cell eNodeB performs a sniffing procedure
across all uplink frequency resources. The micro cell eNodeB
thereby identifies suitable resources for uplink scheduling for
communicating with its own UEs. No X2 coordination is required in
this case.
[0018] In another embodiment, in which sniffing is used by the
micro cell, X2 coordination may be used by the micro cell, which
may send an overload indicator (OI) via X2 to the macro cell eNodeB
when high uplink interference is sensed from the UE attached to the
macro cell. The OI message may request that the macro cell base
station either reduce the power or re-schedule the interfering UE's
uplink resource.
[0019] Sniffing may be used to assess available uplink resources.
The sniffing base station may listen on a plurality of radio
frequencies to determine how each radio resource is used. For each
radio resource, the sniffing base station may receive signals
broadcast on that resource, and may then calculate power spectral
density for each band. The calculation of power spectral density
may be over a short time period, such as over 1 TTI, or less than 1
TTI. The calculation of power spectral density may be performed at
a digital signal processor (DSP). In other embodiments, sniffing
may be used to assess available downlink resources.
[0020] In another embodiment, a micro cell eNodeB may check whether
the affected UEs can be switched to a different radio access
technology (RAT), such as Wi-Fi. As Wi-Fi has different
characteristics, the check may include determining whether the
desired spectral band is available, and may also include
determining whether the UE is within Wi-Fi range, which may be less
than the range of the LTE protocol air interface. A soft handoff
may be performed between the LTE and Wi-Fi interfaces. Wi-Fi may be
used as a last resort in the case that interference is above a
maximum permitted threshold. Wi-Fi may also be used in the case
that other interference mitigation attempts are not successful. A
switch to Wi-Fi may be performed in connection with each of the
below scenarios as well, in some embodiments.
[0021] In a second scenario, a UE is attached to a micro cell
eNodeB and transmits data to the micro cell eNodeB, which generates
interference on the uplink band for UEs attached to a nearby macro
cell eNodeB. In this scenario, different options are available to
the micro cell eNodeB.
[0022] The micro cell eNodeB may be receiving radio signal
measurement reports from the attached UE. Based on these UE
measurements, and optionally on system information blocks (SIBs)
received from the macro eNodeB, the micro cell eNodeB may compute
path loss to the macro cell eNodeB from each UE served by the micro
cell eNodeB.
[0023] Based on the computed path loss, the micro eNodeB may
configure each UE's maximum uplink transmit power to ensure that
the ratio of interference power to noise does not exceed a
specified threshold.
[0024] In some embodiments, the UE's maximum uplink transmit power
may be based on either the estimated range of the micro cell eNodeB
or the estimated range of the macro cell eNodeB, or both.
[0025] As in the prior scenario, the micro cell eNodeB may also
check whether each aggressor UE may be switched to a different RAT,
such as Wi-Fi, in some embodiments.
[0026] In a third scenario, a UE is attached to a macro cell eNodeB
and receives data from the macro cell eNodeB, which generates
interference on the downlink band for UEs attached to a nearby
micro cell eNodeB.
[0027] In one embodiment, a micro cell eNodeB may take into account
RNTP messages sent from the macro cell. Similar to HII messages but
for downlink channels, RNTP messages are messages sent according to
the X2 protocol that include a bitmap indicating, with one bit per
physical resource block (PRB) in the downlink, indicating that
eNodeBs in the neighborhood should expect a high-interference power
event in the near future. The micro cell eNodeB may use received
RNTP messages to schedule use of downlink radio resources.
[0028] The micro cell eNodeB may also use UE measurements of nearby
interference, such as those included with UE measurement reports,
in some embodiments. Using UE-specific measurement reports may
permit micro cell eNodeBs to decide which PRBs to avoid for
specific UEs.
[0029] In some embodiments, the transmit power for each UE may be
dynamically adjusted based on one or more parameters, such as
measured interference, signal strength of other base station nodes,
or other parameters. Transmit power may be adjusted based on
signals received at more than one eNodeB, including micro cell
eNodeBs and macro cell eNodeBs, in some embodiments. Transmit power
may be adjusted based on communications with a cloud coordination
server, which may coordinate interference and signal strength
reports from multiple eNodeBs, in some embodiments.
[0030] One particular type of interference that requires special
treatment on the downlink is control channel interference. While
HII and RNTP messages allow a base station to avoid control channel
interference on the uplink by transmitting during periods when
there is less interference, the downlink control channel, otherwise
known as the physical downlink control channel (PDCCH), is active
during each TTI for each UE at a fixed time, designated to be the
first 1 or 2 or 3 (or 4, under special circumstances) OFDM symbols
at the beginning of each subframe. Since interference during
transmission of the control channel may lead to the inability of
the UE to receive any data during a given TTI, it is important to
reduce interference particularly during transmission of the
PDCCH.
[0031] The PDCCH appears within the first 4 OFDM symbols of each
subframe, each symbol including 12 subcarriers, so that there are
48 resource elements that may be used by an eNodeB to transmit
PDCCH data. In some embodiments, the micro cell base station is
enabled to avoid PDCCH interference between the macro cell base
station and the macro cell-attached UE by changing the PDCCH symbol
location and/or modulation and control scheme (MCS) for each UE
attached to the micro cell eNodeB to use non-interfering resource
elements, as described below.
[0032] In some embodiments, control format indicator (CFI)
information of the macro cell may be used to mitigate interference.
Typically, the control channel of an LTE downlink connection is
synchronized with the base station and scheduled for a particular
time within the TTI, with the most important information being sent
at the beginning of a subframe sent at the particular time. The CFI
is a parameter that indicates, on the control channel for the
downlink, what time span to use for a particular downlink subframe.
The time span is indicated in symbols, according to an orthogonal
frequency division multiplexing (OFDM) encoding scheme. A single
resource block consists of 72 resource elements, divided into 12
subcarriers and 6 symbols, in some embodiments. The CFI may have a
value of 1, 2, or 3, according to some versions of the LTE
standard, and indicates which of the first three symbol columns in
each subframe is used to contain the PDCCH. CFI is transmitted on
the downlink to a UE on the physical control format indicator
channel (PCFICH), and is subject to channel coding along that
channel.
[0033] FIG. 2 depicts an example usage pattern of a subframe, for
reference. Diagram 200 depicts a part of a radio frame. The radio
frame has several subframes, of which subframe 0 is shown, and each
subframe has multiple physical resource blocks (PRBs), of which PRB
5 is shown. Each PRB has multiple subcarriers; here, subcarriers
60-71 are shown. Each subframe also has two slots, 0 and 1, and
each slot has 7 symbols, 0-6. At 201, the first two symbols of slot
0, excepting subcarriers 60, 63, 66 and 69 for symbol 0, are the
physical downlink control channel (PDCCH). At 202, three symbols
are available for a physical downlink shared channel (PDSCH). At
203, a subset of one symbol is available for a secondary
synchronization channel (SSCH). At 204, a subset of one symbol is
available for a primary synchronization channel (PSCH). At 205, a
subset of four symbols are available for a physical broadcast
channel (PBCH). At 206, a subset of three symbols are available for
PDSCH.
[0034] For a CFI received from a macro cell eNodeB, when the CFI is
1, the first symbol of a given subframe is occupied by the PDCCH.
When the CFI is 2 or higher, the first n symbols of the given
subframe are occupied by the PDCCH. With this information, the
micro cell eNodeB may assign resource elements that are not
occupied by the macro cell eNodeB's PDCCH. This assignment may be
done by identifying the specific resource elements occupied by the
macro cell eNodeB's PDCCH.
[0035] Assignment of resource elements may also be done by taking
into account which symbols of the subframe are occupied by the
macro cell eNodeB's PDCCH. If the CFI is 1, and only a single
symbol is being used, the micro cell eNodeB is free to use the
second symbol as well as any subsequent symbol for sending its own
PDCCH information. In cases where the macro cell eNodeB's CFI is 1
or 2, micro cell eNodeB may set the CFI of an attached UE to {1+the
CFI of the macro cell eNodeB}, taking care only to not use symbols
that are in use by the macro cell eNodeB. In cases where the macro
cell eNodeB's CFI is 3 or 4, one of the other approaches discussed
below may be used.
[0036] In addition to being transmitted from the macro cell to the
UE, CFI information may be present in the RNTP received from the
macro cell eNodeB by the micro cell eNodeB and carried via X2, and
may be used on that basis, in some embodiments. Alternatively, the
CFI may be learned via real-time sniffing by the micro cell
eNodeB.
[0037] Next, the PDCCH control channel element (CCE) aggregation
level may also be increased to reduce PDCCH interference from the
macro cell eNodeB, based on the downlink signal strength of the
macro cell. The signal strength may have been received directly
from the macro cell base station, measured by a UE and sent via
measurement report from the UE to the micro cell base station, or
reported from the UE based on an RSRP message from the macro cell
base station, or measured by an RF sniffer present in the micro
cell base station, as described above, in some embodiments.
[0038] In some embodiments, the CCE aggregation level may be
increased at the micro cell eNodeB to use more aggregated resource
elements at the beginning of a subframe in a TTI. The CCE
aggregation level is the number of consecutive resource element
groups (REGs) used for sending the downlink control information for
a particular TTI, and may take values 1, 2, 4, and 8, or other
values, in some versions of the LTE standard. The CCE aggregation
level is multiplied by the number of resource elements in a
resource element group, 4, to obtain the total number of resource
elements that are being claimed. However, not all claimed resource
elements must be used.
[0039] In some embodiments, in the case that the CCE aggregation
level for a UE connected to a macro cell eNodeB is known by the
micro cell eNodeB, the micro cell eNodeB may use a method in which
the micro cell eNodeB uses the CCE aggregation level to identify
specific resource entities that are being used by the macro cell
eNodeB for a given UE's DCI, and the micro cell eNodeB may then
send its own DCI to each of its UEs without using the identified
resource entities, which are known to be interfering.
[0040] In some embodiments, the CCE aggregation level may be
increased in conjunction with increasing the code rate of the
control channel. This causes the introduction of greater redundancy
into the transmission of a PDCCH DCI message to a given UE, which
allows the micro cell eNodeB to use a lower transmit power, thus
causing less interference to the macro cell eNodeB and its
PDCCH.
[0041] In some embodiments, either a plurality of eNodeBs in
communication with one another, or a central coordination server
may be used to plan what PCI to use for each UE. The plan may be
based on sniffing and/or UE measurements to avoid PCFICH
interference, as described above.
[0042] In some embodiments, a micro cell eNodeB may use a sub-band
channel quality indication (CQI) report received from a UE to
schedule a downlink PRB so as to not use the channels identified as
being of poor quality. In addition, the CQI report may be used as
feedback for adjusting the transmit power of the micro cell eNodeB.
In addition, the CQI report may be used as feedback for adjusting
the modulation and coding scheme (MCS) of the attached UE.
[0043] In some embodiments, as described above, the micro cell
eNodeB may check whether the victim UE can be switched to different
RAT, such as Wi-Fi.
[0044] In a fourth scenario, a UE is attached to a micro cell
eNodeB and receives data from the micro cell eNodeB, which
generates interference on the downlink band for UEs attached to a
nearby macro cell eNodeB. The method for handling interference in
this case is similar to that given for the third scenario, with the
following differences. As the micro cell eNodeB has the option of
generating and sending an RNTP message, the micro cell eNodeB may
send such a message to the macro cell eNodeB, in some embodiments.
As well, the micro cell eNodeB may not use a sub-band CQI, in some
embodiments. In some embodiments, the micro cell eNodeB may not
receive UE measurement reports, but instead may perform sniffing
and/or out-of-band querying to obtain signal strength information
for neighboring base stations. In some embodiments, the aggressor
mobile node and the victim mobile node may be associated with two
eNodeBs that are each in communication with a cloud coordination
server, and the signal strength information for neighboring base
stations may be shared among both eNodeBs via the cloud
coordination server. In some embodiments, the micro cell eNodeB may
determine, based on measurement reports from its own attached UEs,
that each of its UEs are well-covered, and may reduce transmit
power, further mitigating interference.
[0045] FIG. 3 is a block diagram of hardware and/or software used
in some embodiments. In one embodiment, a multi-RAT node 300 is
comprised of at least one processor 310, access hardware 320,
backhaul hardware 330, an RF front-end 340, and a timing source
350. By way of example, the at least one processor 310 could
contain firmware written in Linux. Additionally, the RF front-end
340 can be configured to provide RF capabilities for multiple radio
access technologies.
[0046] In one embodiment, the timing source could be GPS.
Alternatively, the timing source could be derived from the
Ethernet, or an IEEE 3588 source, such as SyncE, PTP/1588v2, and
the like. In an alternate embodiment, wherein one multi-RAT node
300 may have access to GPS time, but another multi-RAT node 300 may
be indoors, the two multi-RAT nodes 300 could use differential time
synching techniques well known to those of skill in the art so that
the indoor multi-RAT node 300 could sync its timing with that of
the outdoor multi-RAT node 300. In another embodiment, the
multi-RAT node 300 could be a dynamic multi-RAT node.
[0047] In alternate embodiments, the at least one processor 310,
could be broken down into an access processor 312, a backhaul
processor 314, a common processor 316, or any combination thereof.
In this embodiment, the access hardware 320 is coupled to the at
least one processor 310. In an alternate embodiment, having a
separate access processor 312, the access hardware 320 could be
coupled to the access processor 312, to the at least one processor
310, or to the common processor 316, or any combination thereof.
Similarly, in another alternate embodiment, having a separate
backhaul processor 314, the backhaul hardware 330 could be coupled
to the backhaul processor 314, to the common processor 310, or to
the common processor 316, or any combination thereof.
[0048] Those skilled in the art will appreciate that access and
backhaul hardware will vary depending on the access or backhaul
protocol or frequency being used to perform access or backhaul. By
way of example, if a particular multi-RAT node 300 was designed to
permit access on LTE and Wi-Fi, it could have the radio access
technology components that would perform access on these two
different protocols. For LTE access, the access hardware 320 could
be comprised of: a baseband processor and one or more CPU cores for
the firmware. The baseband processor could generate digital RF
signals, which are modulated by the RF front end 340. These
processors could be connected to the RF front end 340 via radio
interfaces. Alternatively, some or all of the necessary radio
access technology may incorporate commercial off-the-shelf (COTS)
hardware/firmware devices, such as conventional Wi-Fi access
hardware based on Atheros chips with embedded firmware and one or
more external antennas.
[0049] Those skilled in the art will recognize that multiple
hardware and software configurations could be used depending upon
the access protocol, backhaul protocol, duplexing scheme, or
operating frequency band by adding or replacing daughtercards to
the dynamic multi-RAT node 300. Presently, there are radio cards
that can be used for the varying radio parameters. Accordingly, the
multi-RAT nodes 300 of the present invention could be designed to
contain as many radio cards as desired given the radio parameters
of heterogeneous mesh networks within which the multi-RAT node 300
is likely to operate. Those of skill in the art will recognize
that, to the extent an off-the shelf radio card is not available to
accomplish transmission/reception in a particular radio parameter,
a radio card capable of performing, e.g., in white space
frequencies, would not be difficult to design.
[0050] Those of skill in the art will also recognize that hardware
may embody software, software may be stored in hardware as
firmware, and various modules and/or functions may be performed or
provided either as hardware or software depending on the specific
needs of a particular embodiment.
[0051] Although the scenarios for interference mitigation are
described in relation to macro cells and micro cells, the same
techniques could be used for reducing interference between any two
cells, in which only one of the two cells is required to perform
the interference mitigation methods described herein. The
applicability of the above techniques to one-sided deployments
makes them particularly suitable for heterogeneous networks,
including heterogeneous mesh networks, in which all network nodes
are not identically provisioned.
[0052] In any of the scenarios described herein, where processing
may be performed at the micro cell, the processing may also be
performed in coordination with a cloud coordination server. The
micro cell eNodeB may be in communication with the cloud
coordination server via an X2 protocol connection, or another
connection. The micro cell eNodeB may perform inter-cell
coordination via the cloud communication server, when other cells
are in communication with the cloud coordination server. The micro
cell eNodeB may communicate with the cloud coordination server to
determine whether the UE has the ability to support a handover to
Wi-Fi.
[0053] Although the methods above are described as separate
embodiments, one of skill in the art would understand that it would
be possible and desirable to combine several of the above methods
into a single embodiment, or to combine disparate methods into a
single embodiment. For example, all of the above methods could be
combined. In the scenarios where multiple embodiments are
described, the methods could be combined in sequential order, in
various orders as necessary.
[0054] Although the above systems and methods for providing
interference mitigation are described in reference to the Long Term
Evolution (LTE) standard, and in particular LTE Release 9, one of
skill in the art would understand that these systems and methods
could be adapted for use with other wireless standards or versions
thereof.
[0055] In some embodiments, the software needed for implementing
the methods and procedures described herein may be implemented in a
high level procedural or an object-oriented language such as C,
C++, C#, Python, Java, or Perl. The software may also be
implemented in assembly language if desired. Packet processing
implemented in a network device can include any processing
determined by the context. For example, packet processing may
involve high-level data link control (HDLC) framing, header
compression, and/or encryption. In certain embodiments, the
software is stored on a storage medium or device such as read-only
memory (ROM), programmable-read-only memory (PROM), electrically
erasable programmable-read-only memory (EEPROM), flash memory, or a
magnetic disk that is readable by a general or special
purpose-processing unit to perform the processes described in this
document. The processors can include any microprocessor (single or
multiple core), system on chip (SoC), microcontroller, digital
signal processor (DSP), graphics processing unit (GPU), or any
other integrated circuit capable of processing instructions such as
an x86 microprocessor.
[0056] Although the present disclosure has been described and
illustrated in the foregoing example embodiments, it is understood
that the present disclosure has been made only by way of example,
and that numerous changes in the details of implementation of the
disclosure may be made without departing from the spirit and scope
of the disclosure, which is limited only by the claims which
follow. Other embodiments are within the following claims. For
example, the out-of-band channel may be implemented over a virtual
channel over the public Internet.
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