NZ791129A - Systems and methods for mitigating interference within actively used spectrum - Google Patents
Systems and methods for mitigating interference within actively used spectrumInfo
- Publication number
- NZ791129A NZ791129A NZ791129A NZ79112917A NZ791129A NZ 791129 A NZ791129 A NZ 791129A NZ 791129 A NZ791129 A NZ 791129A NZ 79112917 A NZ79112917 A NZ 79112917A NZ 791129 A NZ791129 A NZ 791129A
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- NZ
- New Zealand
- Prior art keywords
- wireless network
- wireless
- band
- fdd
- antennas
- Prior art date
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Abstract
Systems and methods are described to mitigate interference to out of band receivers using out of band training signals.
Description
SYSTEMS AND METHODS FOR MITIGATING INTERFERENCE WITHIN ACTIVELY
USED SPECTRUM
CROSS REFERENCE TO RELATED APPLICATIONS
This ation claims the benefit of U.S. Provisional Patent Application No.
62/380,126, filed August 26, 2016.
This application is also a continuation-in-part of U.S. ation Serial No.
14/672,014, entitled “Systems and Methods for Concurrent Spectrum Usage Within
Actively Used Spectrum” filed March 27, 2015, which claims the benefit of and priority to
U.S. Provisional Patent Application No. 61/980,479, entitled, “Systems and Methods for
rent Spectrum Usage Within Actively Used Spectrum” filed April 16, 2014 all of
which is herein incorporated by reference.
This application may be related to the following co-pending U.S. Patent
Applications and U.S. Provisional Applications:
U.S. Application Serial No. 14/611,565, entitled “Systems and Methods for
Mapping Virtual Radio Instances into Physical Areas of Coherence in Distributed
Antenna Wireless Systems”
U.S. Application Serial No. ,700, entitled “Systems and Methods for
Exploiting Inter-cell Multiplexing Gain in Wireless ar Systems Via Distributed Input
Distributed Output Technology”
U.S. Application Serial No. 13/844,355, entitled “Systems and Methods for
Radio Frequency Calibration ting Channel Reciprocity in Distributed Input
Distributed Output Wireless Communications”
U.S. Application Serial No. 13/797,984, entitled “Systems and Methods for
Exploiting Inter-cell lexing Gain in Wireless Cellular Systems Via Distributed Input
Distributed Output logy”
U.S. ation Serial No. 13/797,971, entitled “Systems and Methods for
Exploiting Inter-cell Multiplexing Gain in Wireless Cellular Systems Via Distributed Input
Distributed Output Technology”
U.S. ation Serial No. ,950, entitled “Systems and Methods for
Exploiting Inter-cell Multiplexing Gain in Wireless Cellular Systems Via Distributed Input
Distributed Output Technology”
U.S. Application Serial No. ,598, entitled “Systems and Methods to
enhance spatial diversity in buted-input distributed-output wireless systems”
U.S. Application Serial No. 13/233,006, entitled “System and Methods for
planned evolution and obsolescence of multiuser spectrum”
U.S. Application Serial No. 13/232,996, entitled “Systems and Methods to
Exploit Areas of Coherence in Wireless Systems”
U.S. Application Serial No. 12/802,989, entitled “System And Method For
Managing f Of A Client Between Different Distributed-Input-Distributed-Output
(DIDO) Networks Based On Detected Velocity Of The Client”
U.S. Application Serial No. 12/802,988, entitled “Interference Management,
Handoff, Power Control And Link Adaptation In Distributed-Input Distributed-Output
(DIDO) ication Systems”
U.S. Application Serial No. 12/802,975, entitled “System And Method For
Link adaptation In DIDO Multicarrier Systems”
U.S. Application Serial No. 12/802,974, entitled “System And Method For
ng Inter-Cluster Handoff Of Clients Which Traverse Multiple DIDO Clusters”
U.S. Application Serial No. 12/802,958, entitled “System And Method For
Power Control And Antenna Grouping In A Distributed-Input-Distributed-Output (DIDO)
Network”
U.S. Patent No. 9,386,465, issued July 5, 2016 ed “System and Method
For Distributed Antenna Wireless ications”
U.S. Patent No. 9,369,888, issued June 14, 2016 entitled “Systems And
s To Coordinate issions In Distributed Wireless Systems Via User
ring”
U.S. Patent No. 9,312,929, issued April 12, 2016, entitled “System and
Methods to Compensate for Doppler s in Distributed-Input Distributed Output
Systems”
U.S. Patent No. 8,989,155, issued March 24, 2015, entitled “Systems and
Methods for Wireless ul in Distributed-Input Distributed-Output Wireless
Systems”
U.S. Patent No. 380, issued March 3, 2015, entitled “System and
Method for Adjusting DIDO Interference Cancellation Based On Signal Strength
Measurements
U.S. Patent No. 815, issued February 18, 2014, entitled “System and
Method for Distributed Input Distributed Output Wireless Communications”
U.S. Patent No. 8,571,086, issued October 29, 2013, entitled “System and
Method for DIDO Precoding olation in Multicarrier Systems”
U.S. Patent No. 763, issued September 24, 2013, entitled “Systems
and Methods To Coordinate Transmissions In Distributed Wireless Systems Via User
Clustering”
U.S. Patent No. 8,428,162, issued April 23, 2013, entitled “System and
Method for Distributed Input Distributed Output Wireless Communications”
U.S. Patent No. 081, issued May 1, 2012, entitled m And
Method For Adjusting DIDO Interference Cancellation Based On Signal th
Measurements”
U.S. Patent No. 8,160,121, issued Apr. 17, 2012, entitled, ”System and
Method For Distributed Input-Distributed Output Wireless Communications”;
U.S. Patent No. 7,885,354, issued Feb. 8, 2011, entitled “System and
Method For Enhancing Near Vertical Incidence Skywave (“NVIS”) ication
Using Time Coding.”
U.S. Patent No. 7,711,030, issued May 4, 2010, entitled “System and
Method For Spatial-Multiplexed Tropospheric Scatter Communications”;
U.S. Patent No. 7,636,381, issued Dec. 22, 2009, entitled “System and
Method for Distributed Input Distributed Output Wireless Communication”;
U.S. Patent No. 7,633,994, issued Dec. 15, 2009, entitled “System and
Method for Distributed Input Distributed Output ss Communication”;
U.S. Patent No. 7,599,420, issued Oct. 6, 2009, entitled “System and
Method for Distributed Input Distributed Output Wireless Communication”;
U.S. Patent No. 053, issued Aug. 26, 2008, entitled “System and
Method for Distributed Input buted Output Wireless Communication”.
BACKGROUND
Both Frequency Division Duplex (“FDD”) and Time Division Duplex (“TDD”)
modes are commonly used in wireless communications s. For example, the LTE
standard supports both FDD and TDD modes, as another example 802.11 versions
(e.g. Wi-Fi) support TDD mode of operation.
In the case of LTE, various numbered bands are defined within what is called
“Evolved UMTS Terrestrial Radio Access” (E-UTRA) air interface. Each E-UTRA band
not only specifies a particular band number, but it defines whether the band is FDD or
TDD, and what bandwidths are supported within the band (e.g. see
http://en.wikipedia.org/wiki/LTE_frequency_bands#Frequency_bands_and_channel_ba
ndwidths for a list of E-UTRA bands and their specifications). For example, Band 7 is an
FDD band defined as using the frequency ranges of 2,500 – 2,570 MHz for Uplink
(“UL”), 2,620 – 2,690 for downlink (“DL”), it supports 5, 10, 15, 20 and MHz signal
bandwidths within each of the UL and DL bands.
In many cases E-UTRA bands overlap. For example, different bands may be
common spectrum that has been ted in different markets or regions. For example,
Band 41 is a TDD band using the frequency ranges of 2,496 – 2,690 MHz for both UL
and DL, which overlaps with both UL and DL ranges in FDD Band 7 (e.g. see Figures
16a and 16b.. Currently, Band 41 is used in the U.S. by Sprint, while Band 7 is used by
Rogers Wireless in the bordering y of . Thus, in the U.S., 2,500-2,570
MHz is TDD spectrum, while in Canada that same frequency range is UL for FDD
spectrum.
Typically, a mobile device, upon attaching to a wireless network, will scan
through the band searching for transmissions from one or more base stations, and
lly during the attach procedure, the base n will transmit the characteristics of
the network, such as the bandwidth used by the network, and details of the protocol in
use. For example, if an LTE device scans through 2,690 MHz in the U.S., it might
receive an LTE DL frame transmitted by an eNodeB that identifies the spectrum as
Band 41, and if the LTE device supports Band 41 and TDD, it may attempt to connect to
the eNodeB in TDD mode in that band. Similarly, if an LTE device scans through 2,620-
2,690 MHz in the Canada, it might receive an LTE DL frame transmitted by an eNodeB
that identifies the spectrum as Band 7, and if the LTE device ts Band 7 and FDD,
it may attempt to connect to the eNodeB in FDD mode in Band 7.
Most early LTE networks deployed worldwide used FDD mode (e.g.,
Verizon, AT&T), but increasingly TDD mode is being used, both in markets with
extensive FDD coverage, such as the U.S. (where Sprint is deploying TDD) and in
s that do not yet have extensive LTE coverage, such as China (where China
Mobile is deploying TDD). In many cases, a single operator is deploying both FDD and
TDD at different frequencies (e.g. Sprint operates both FDD LTE and TDD LTE in
different frequencies in the U.S.), and may offer LTE devices which can e in both
modes, depending on which band is used.
Note that the E-UTRA list of LTE bands is by no means a final list, but rather
evolves as new spectrum is ted to mobile operators and devices to use that
spectrum are specified. New bands are specified both in spectrum with no current band
that overlaps its frequencies, and in spectrum in bands overlapping frequencies of
previous band allocations. For example, Band 44, a TDD band spanning 703-803 MHz,
was added as an E-UTRA band several years after older 700 MHz FDD bands were
specified, such as Bands 12, 13, 14 and 17.
As can be seen in Figure 6, the bulk of mobile data used to be voice data
(e.g. Q1 2007), which is highly symmetric. But, with the introduction of the iPhone in
2007, and the rapid adoption of Android and then introduction of the iPad in 2009, nonvoice
mobile data rapidly outpaced the growth of voice data, to the point where, by the
middle of 2013, voice data was a small fraction of mobile data traffic. Non-voice data is
projected to continue to grow exponentially, increasingly dwarfing voice data.
As can been seen in Figure 7, non-voice mobile data is largely dominated by
media, such as streaming video, audio and Web browsing (much of which includes
streaming video). Although some streaming media is UL data (e.g. during a
videoconference), the vast majority is DL data, resulting is highly asymmetric DL vs. UL
data usage. For example, in the Financial Times May 28, 2013 article, “Asymmetry and
the impending (US) um crisis”, it states that “…industry tes of the ratio of
data traffic downlink to data traffic in the uplink ranges from a ratio of about eight to one
(8:1)—to considerably more.” The article then points out that the largely FDD
deployments in the U.S. are very cient in handling such asymmetry since FDD
mode tes the same amount of spectrum to each DL and UL. As another example,
Qualcomm estimated DL/UL traffic asymmetry as high as 9:1 for one of the U.S.
operators, based on 2009 measurements in live ks (cfr., Qualcomm, “1000x:
more spectrum – especially for small cells”, Nov. 2013,
http://www.qualcomm.com/media/documents/files/1000x-more-spectrum-especially-forsmall-cells.pdf
). Thus, even when FDD DL spectrum is heavily ed (potentially to the
point of being overloaded), the UL spectrum may be largely .
The Financial Times article points out that TDD is far better suited to such
asymmetry since it can be configured to allocate far more timeslots to the DL data than
the UL data. For example, in the case when 20 MHz is ted to FDD (as 10+10
MHz), DL data throughput is limited to a maximum of full-time use of 10 MHz (even
when the UL data needs far less than the 10 MHz it has been ted), whereas when
MHz allocated to TDD, DL data throughput can use all 20 MHz the vast majority of
the time, allocating the 20MHz to UL data a small percentage of the time, far better
matching the characteristics of data usage today. The article acknowledges that,
unfortunately, most existing U.S. mobile spectrum is already committed to FDD mode,
but urges the FCC to age the use of TDD as it allocates new spectrum.
Although TDD would certainly allow for more efficient use of new spectrum
allocations given the increasingly asymmetric nature of mobile data, unfortunately
existing FDD networks ments cannot change operating mode to TDD since the
vast majority of users of such LTE FDD networks have devices that only t FDD
mode and their s would cease to be able to connect if the network were switched
to TDD mode. Consequently, as LTE data usage becomes increasingly asymmetric,
existing LTE FDD networks will see increasing DL congestion, while UL spectrum will
be increasingly underutilized (at 8:1 DL:UL ratio, the lower estimate of the May 28, 2013
Financial Times e, that would imply that if the DL channel is fully utilized, only 1/8th,
equivalent to 1.25MHz of 10Mhz, would be used of the UL channel). This is extremely
wasteful and inefficient, particularly given the limited physical existence of practical
mobile spectrum (e.g. frequencies that can penetrate walls and propagate well non-lineof-sight
, such as ~450-2600 MHz) and the exponential growth of (increasingly
asymmetric) mobile data (e.g. Cisco 2/2013 VNI predicts a 61% CAGR in mobile data
growth through 2018, most of which is streaming video and other highly asymmetric
data).
Thus there is a need for systems and methods for mitigating interference within
actively used spectrum or which at least es the public or industry with a useful
choice.
SUMMARY OF THE INVENTION
According to an example embodiment there is provided a system
comprising: a first wireless k operating with a first protocol and comprising a
plurality of wireless eiver stations that share a cell ID and collectively transmit a
plurality of simultaneous terfering ed data streams to a plurality of user
equipment (UE) within a same frequency band, a second wireless network operating
with a second protocol and sing one or a plurality of antennas, wherein the first
wireless k creates one or a ity of points of zero radio frequency (RF) energy
at the location of the one or at least one of the plurality of antennas.
According to another example embodiment there is provided a system
comprising: a first wireless network operating with a first protocol and comprising a
plurality of wireless transceiver stations that share a cell ID and tively transmit a
plurality of simultaneous non-interfering precoded data streams to a plurality of user
equipment (UE) within a same frequency band, a second wireless network operating
with a second protocol and comprising one or a plurality of as, wherein the first
wireless network creates one or a plurality of points of zero radio frequency (RF) energy
at the on of the one or at least one of the plurality of antennas, and the second
wireless network has knowledge of the first protocol of the first wireless network.
According to another example embodiment there is provided a method for
communicating over a network comprising: a first wireless network operating with a first
protocol and comprising a plurality of wireless transceiver stations that share a cell ID
and collectively transmit a ity of simultaneous non-interfering precoded data
streams to a plurality of user ent (UE) within a same frequency band, a second
wireless network operating with a second protocol and comprising one or a plurality of
as, the first wireless k creating one or a plurality of points of zero radio
frequency (RF) energy at the location of the one or at least one of the plurality of
antennas
According to another example ment there is provided a method for
communicating over a k comprising: a first wireless network operating with a first
protocol and comprising a plurality of wireless eiver stations that share a cell ID
and collectively transmit a plurality of simultaneous non-interfering precoded data
streams to a ity of user equipment (UE) within a same frequency band, a second
wireless network operating with a second ol and comprising one or a plurality of
antennas, the first wireless network creating one or a plurality of points of zero radio
frequency (RF) energy at the location of the one or at least one of the plurality of
antennas, and the second wireless network having knowledge of the first protocol of the
first wireless network.
BRIEF DESCRIPTION OF THE DRAWINGS
A better understanding of the present invention can be obtained from the
following detailed description in conjunction with the drawings, in which:
illustrates the general framework of the DIDO Radio Access Network
(DRAN)
illustrates the protocol stack of the Virtual Radio Instance (VRI)
tent to the OSI model and LTE standard
illustrates adjacent DRANs to extend ge in DIDO wireless
networks
illustrates handoff between DRAN and adjacent wireless networks
illustrates handoff n DRAN and LTE cellular ks
is prior art showing voice and non-voice data utilization of mobile
spectrum from 2007-2013.
is prior art showing mobile data traffic share by application type in
2012.
Fig. 8 is a prior art comparison of FDD LTE and TDD LTE modes of
operations
Fig. 9 illustrates a new TDD network concurrently using UL spectrum with an
existing FDD k
Fig. 10 is a prior art chart of TDD LTE duplex configurations
Fig. 11 illustrates a new TDD network concurrently using DL um with
an existing FDD network
Fig. 12 illustrates two new TDD networks concurrently using UL and DL
um with an existing FDD network
Fig. 13 illustrates a new FDD network concurrently using UL and DL
spectrum with an existing FDD network
Fig. 14 illustrates a DRAN that synthesizes null pCells at the location of base
n as.
Figs. 15a, 15b, 15c, and 15d illustrate various propagation scenarios
between base station antennas.
Figs. 16a and 16b are prior art diagrams of allocations of the 2500-2690
MHz band in different regions as either FDD and TDD or only as TDD.
DETAILED DESCRIPTION
One solution to overcome many of the above prior art limitations is to have
user devices concurrently operate in TDD mode in the same spectrum as currently
used UL or DL FDD spectrum, such that the TDD spectrum usage is coordinated so as
to not conflict with current FDD spectrum usage. ularly in the FDD UL channel,
there is increasingly more unused spectrum, and TDD devices could use that spectrum
without impacting the throughput of the existing FDD network. The also enables TDD
usage highly propagation-efficient UHF spectrum which, in many s of the world is
almost entirely allocated to FDD, ting TDD to far less propagation-efficient
ave bands.
In another embodiment is to have user devices concurrently operated in FDD
mode in the same spectrum as currently used UL or DL FDD spectrum, such that the
UL and DL channels are ed and each network’s spectrum usage is coordinated
so as not to conflict with the other network’s spectrum usage. Given that the UL
channel of each network is increasingly underutilized relative to the DL channel, it
allows each network’s DL channel to utilize the unused spectrum in the other network’s
UL l.
Further, in either embodiment spectral efficiency can be vastly increased by
implementing one or both networks using Distributed-Input Distributed-Output (“DIDO”)
technology as described in the following patents, patent applications and ional
applications, all of which are assigned the assignee of the present patent and are
incorporated by reference. These patents, ations and provisional applications are
sometimes referred to collectively herein as the “Related Patents and Applications.”
U.S. Application Serial No. 14/672,014, entitled “Systems And Methods For
Concurrent Spectrum Usage Within ly Used Spectrum”.
U.S. Provisional Patent Application No. 61/980,479, filed April 16, 2014,
entitled, “Systems and Methods for Concurrent Spectrum Usage Within Actively Used
U.S. Application Serial No. 14/611,565, entitled “Systems and Methods for
Mapping Virtual Radio Instances into Physical Areas of Coherence in Distributed
Antenna Wireless Systems”
U.S. ation Serial No. 14/086,700, entitled “Systems and s for
Exploiting Inter-cell Multiplexing Gain in Wireless Cellular Systems Via Distributed Input
Distributed Output Technology”
U.S. Application Serial No. ,355, entitled “Systems and s for
Radio ncy Calibration Exploiting Channel Reciprocity in Distributed Input
Distributed Output Wireless Communications”
U.S. Application Serial No. 13/797,984, entitled ms and Methods for
Exploiting Inter-cell Multiplexing Gain in Wireless Cellular Systems Via Distributed Input
buted Output logy”
U.S. Application Serial No. 13/797,971, entitled “Systems and Methods for
Exploiting Inter-cell Multiplexing Gain in ss Cellular Systems Via Distributed Input
Distributed Output Technology”
U.S. Application Serial No. 13/797,950, entitled “Systems and Methods for
Exploiting Inter-cell Multiplexing Gain in Wireless Cellular Systems Via Distributed Input
Distributed Output Technology”
U.S. Application Serial No. 13/475,598, entitled “Systems and Methods to
enhance spatial diversity in distributed-input distributed-output wireless s”
U.S. Application Serial No. 13/233,006, entitled “System and s for
planned evolution and obsolescence of multiuser spectrum”
U.S. Application Serial No. 13/232,996, ed “Systems and Methods to
Exploit Areas of Coherence in Wireless Systems”
U.S. ation Serial No. ,989, entitled m And Method For
Managing Handoff Of A Client Between Different Distributed-Input-Distributed-Output
(DIDO) Networks Based On Detected Velocity Of The Client”
U.S. Application Serial No. 12/802,988, entitled “Interference Management,
Handoff, Power Control And Link Adaptation In Distributed-Input Distributed-Output
(DIDO) Communication Systems”
U.S. Application Serial No. 12/802,975, entitled “System And Method For
Link adaptation In DIDO Multicarrier Systems”
U.S. Application Serial No. 12/802,974, entitled “System And Method For
Managing Cluster Handoff Of s Which Traverse Multiple DIDO Clusters”
U.S. Application Serial No. 12/802,958, entitled “System And Method For
Power Control And Antenna Grouping In A Distributed-Input-Distributed-Output (DIDO)
Network”
U.S. Patent No. 9,386,465, issued July 5, 2016 entitled “System and Method
For Distributed Antenna Wireless Communications”
U.S. Patent No. 9,369,888, issued June 14, 2016 entitled “Systems And
Methods To nate Transmissions In Distributed Wireless Systems Via User
Clustering”
U.S. Patent No. 929, issued April 12, 2016, ed “System and
Methods to Compensate for Doppler Effects in Distributed-Input Distributed Output
Systems”
U.S. Patent No. 155, issued March 24, 2015, entitled ms and
Methods for Wireless Backhaul in Distributed-Input Distributed-Output Wireless
Systems”
U.S. Patent No. 8,971,380, issued March 3, 2015, entitled “System and
Method for Adjusting DIDO Interference Cancellation Based On Signal Strength
Measurements
U.S. Patent No. 8,654,815, issued February 18, 2014, entitled “System and
Method for Distributed Input buted Output Wireless Communications”
U.S. Patent No. 8,571,086, issued October 29, 2013, entitled “System and
Method for DIDO Precoding Interpolation in Multicarrier Systems”
U.S. Patent No. 8,542,763, issued September 24, 2013, entitled “Systems
and Methods To nate Transmissions In Distributed Wireless Systems Via User
Clustering”
U.S. Patent No. 8,428,162, issued April 23, 2013, entitled m and
Method for Distributed Input Distributed Output Wireless Communications”
U.S. Patent No. 8,170,081, issued May 1, 2012, entitled m And
Method For Adjusting DIDO Interference Cancellation Based On Signal th
Measurements”
U.S. Patent No. 8,160,121, issued Apr. 17, 2012, entitled, ”System and
Method For buted Input-Distributed Output ss ications”;
U.S. Patent No. 7,885,354, issued Feb. 8, 2011, entitled “System and
Method for Enhancing Near Vertical Incidence Skywave (“NVIS”) Communication Using
Space-Time Coding.”
U.S. Patent No. 7,711,030, issued May 4, 2010, entitled “System and
Method For Spatial-Multiplexed Tropospheric Scatter Communications”;
U.S. Patent No. 381, issued Dec. 22, 2009, entitled “System and
Method for Distributed Input Distributed Output Wireless Communication”;
] U.S. Patent No. 7,633,994, issued Dec. 15, 2009, entitled “System and
Method for Distributed Input Distributed Output Wireless Communication”;
U.S. Patent No. 7,599,420, issued Oct. 6, 2009, entitled “System and
Method for Distributed Input Distributed Output Wireless Communication”;
U.S. Patent No. 7,418,053, issued Aug. 26, 2008, entitled “System and
Method for Distributed Input Distributed Output Wireless Communication”.
The present invention discloses systems and methods for concurrent
spectrum usage within actively used spectrum. Some of the ments utilize
Distributed-Input Distributed-Output and MU-MAS technology previously disclosed by
the assignee of the assignee of the present patent. The disclosures in Section 1 and
Section 2 below pond to the disclosures in the U.S. Provisional Application Serial
No. 61/937,273 filed February 7, 2014, entitled “Systems and Methods for Mapping
Virtual Radio Instances into Physical Areas of Coherence in Distributed a
Wireless s” and relate to the present invention. The disclosures of Sections 3
and 4 below correspond to the disclosures in the U.S. Provisional Application Serial No.
61/980,479 filed April 16, 2014, entitled m and Methods for Concurrent Spectrum
Usage Within Actively Used Spectrum” and also relate the present invention.
1. Systems and Methods for Mapping VRIs into Areas of Coherence
One embodiment of the present invention discloses systems and methods to
deliver multiple simultaneous non-interfering data streams within the same frequency
band between a network and a plurality of areas of coherence in a wireless link through
Virtual Radio Instances (VRIs). In one embodiment the system is a multiuser multiple
antenna system (MU-MAS) as depicted in Figure 1. The color-coded units in Figure 1
show one-to-one mapping between the data sources 101, the VRIs 106 and the areas
of coherence 103 as described hereafter.
1.1 Overview of the System Architecture
] In Figure 1, the data sources 101 are data files or streams carrying web
content or files in a local or remote server, such as text, images, sounds, videos or
ations of those. One or multiple data files or streams are sent or received
n the network 102 and every area of nce 103 in the wireless link 110. In
one embodiment the network is the Internet or any wireline or wireless local area
network.
The area of coherence is a volume in space where the waveforms from
different antennas of the MU-MAS add up coherently in a way that only the data output
112 of one VRI is received within that area of coherence, without any interference from
other data output from other VRIs sent simultaneously over the same wireless link. In
the present application we use the term “area of coherence” to describe volumes of
coherence or private cells (e.g., s™” 103) as described in our previous patent
ation [U.S. Application Serial No. ,996, entitled ms and Methods to
Exploit Areas of Coherence in Wireless s”]. In one embodiment, the areas of
coherence correspond to the locations of the user equipment (UE) 111 or subscribers of
the wireless network, such that every subscriber is associated to one or multiple data
sources 101. The areas of coherence may vary in size and shape depending on
propagation conditions as well as type of MU-MAS precoding techniques ed to
te them. In one embodiment of the invention, the MU-MAS precoder dynamically
adjusts size and shape of the areas of coherence to adapt to the changing propagation
conditions while delivering contents to the users with good link reliability.
The data sources 101 are first sent through the k 102 to the DIDO
Radio Access Network (DRAN) 104. The n, the DRAN translates the data files or
streams into a data format that can be received by the UEs and sends the data files or
streams aneously to the plurality of areas of coherence, such that every UE
receives its own data files or streams t interference from other data files or
streams sent to other UEs. The DRAN consists of a gateway 105 as the interface
between the network and the VRIs 106. The VRIs translate packets being routed by the
gateway into data streams 112, either as raw data, or in a packet or frame structure,
that are fed to a MU-MAS baseband unit. In one embodiment, the VRI comprises the
open systems interconnection (OSI) protocol stack consisting of sever layers:
application, presentation, session, transport, k, data link and physical, as
depicted in Figure 2a. In another embodiment, the VRI only comprises a subset of the
OSI layers.
In r embodiment, the VRIs are d from different wireless
standards. By way of example, but not limitation, a first VRI consists of the ol
stack from the GSM standard, a second VRI from the 3G standard, a third VRI from
HSPA+ standard, a fourth VRI from LTE standard, as fifth VRI from LTE-A standard and
a sixth VRI from the Wi-Fi standard. In an exemplary embodiment, the VRIs comprise
the l-plane or user-plane protocol stack defined by the LTE standards. The userplane
protocol stack is shown in Figure 2b. Every UE 202 ic ates with its own
VRI 204 through the PHY, MAC, RLC and PDCP layers, with the gateway 203 through
the IP layer and with the network 205 through the application layer. For the controlplane
protocol stack, the UE also communicates directly with the mobility management
entity (MME) through the NAS (as defined in the LTE standard stack) layer.
The l Connection Manager (VCM) 107 is responsible for assigning the
PHY layer identity of the UEs (e.g., pecific radio network temporary identifier,
RNTI), authentication and ty of the VRI and UE. The data streams 112 at the
output of the VRIs are fed to the Virtual Radio Manager (VRM) 108. The VRM
comprises a scheduler unit (that schedules DL (downlink) and UL (uplink) packets for
different UEs), a baseband unit (e.g., comprising of FEC encoder/decoder,
tor/demodulator, resource grid builder) and a MU-MAS baseband processor
(comprised of precoding logic for implementing precoding operations). In one
embodiment, the data streams 112 are I/Q samples at the output of the PHY layer in
Figure 2b that are processed by the MU-MAS baseband processor. In a different
embodiment, the data streams 112 are MAC, RLC or PDCP packets sent to a scheduler
unit that ds them to a baseband unit. The baseband unit converts packets into I/Q
fed to the MU-MAS baseband processor.
The MU-MAS baseband processor is the core of the VRM that ts the
M I/Q samples from the M VRIs into N data streams 113 sent to N access points (APs)
109. In one embodiment, the data streams 113 are I/Q samples of the N waveforms
transmitted over the wireless link 110 from the APs 109. In this ment the AP
consists of ADC/DAC, RF chain and antenna. In a different embodiment, the data
s 113 are bits of information and MU-MAS precoding ation that are
combined at the APs to generate the N waveforms sent over the wireless link 110. In
this embodiment every AP is equipped with CPU, DSP or SoC to carry out additional
baseband processing before the ADC/DAC units.
1.2 Supporting Mobility and Handoff
The systems and methods described thus far work as long the UEs are within
reach of the APs. When the UEs travel away from the AP coverage area the link may
drop and the DRAN 301 is unable to create areas of coherence. To extend the
coverage area, the systems can gradually evolve by adding new APs. There may not be
enough processing power in the VRM, however, to support the new APs or there may
be practical installation issues to connect the new APs to the same VRM. In these
scenarios, it is necessary to add nt DRANs 302 and 303 to support the new APs
as depicted in Figure 3.
In one embodiment a given UE is located in the coverage area served by the
first DRAN 301 and the adjacent DRAN 302. In this embodiment, the adjacent DRAN
302 only carries out MU-MAS baseband processing for that UE, jointly with the MUMAS
processing from the first DRAN 301. No VRI is handled by the adjacent DRAN 302
for the given UE, since the VRI for that UE is already running within the first DRAN 301.
To enable joint precoding n the first and nt DRANs, baseband information
is exchanged between the VRM in the first DRAN 301 and the VRM in the adjacent
DRAN 302 through the cloud-VRM 304 and the links 305. The links 305 are any wireline
(e.g., fiber, DSL, cable) or wireless link (e.g., line-of-sight links) that can support
adequate tion quality (e.g. low enough latency and adequate data rate) to avoid
degrading performance of the MU-MAS precoding.
In a different embodiment a given UE moves out of the coverage area of the first
DRAN 301 into the coverage area of the adjacent DRAN 303. In this embodiment the
VRI ated to that UE is orted” from the first DRAN 301 to the adjacent DRAN
303. What is meant by the VRI being teleported or “VRI teleportation” is the VRI state
information is transferred from DRAN 301 to DRAN 303, and the VRI ceases to execute
within DRAN 301 and begins to execute within DRAN 303. Ideally, the VRI teleportation
occurs fast enough that, from the perspective of the UE served by the teleported VRI, it
does not experience any discontinuity in its data stream from the VRI. In one
embodiment, if there is a delay before the VRI is fully executing after being teleported,
then before the VRI teleportation begins, the UE served by that VRI is put into a state
where it will not drop its connection or otherwise enter an rable state until the VRI
starts up at the adjacent DRAM 303, and the UE once again is served by an executing
VRI. “VRI teleportation” is enabled by the cloud-VCM 306 that connects the VCM in the
first DRAN 301 to the VCM in the adjacent DRAN 303. The wireline or wireless links
307 between VCM do not have the same restrictive constraints as the links 305
between VRMs since they only carry data and do not affect performance of the MUMAS
precoding. In the same embodiment of the invention, additional links 305 are
employed between the first DRAN 301 and the adjacent DRAN 303 to connect their
VRMs that can support te connection quality (e.g., low enough latency and
adequate data rate) to avoid degrading performance of the MU-MAS ing. In one
embodiment of the invention, the gateways of the first and adjacent DRANs are
connected to the cloud-gateway 308 that manages all network address (or IP address)
translation across DRANs.
In one embodiment of the invention, VRI teleportation occurs between the
DRAN network disclosed in the present application and any adjacent wireless network
401 as depicted in Figure 4. By way of e, but not limitation, the wireless network
401 is any conventional cellular (e.g., GSM, 3G, HSPA+, LTE, LTE-A) or wireless local
area network (WLAN, e.g., Wi-Fi). As the VRI is teleported from the DRAN to the
adjacent wireless k 401 the UE is handed off n the two networks and its
wireless connection may continue.
In one embodiment, the adjacent wireless network 401 is the LTE network
shown in Figure 5. In this embodiment, the VCM 502 is connected to the LTE
ty management entity (MME) 501. All the information about ty, authentication
and mobility of every UE handing-off between the LTE and the DRAN ks is
exchanged between the MME 501 and the cloud-VCM 502. In the same embodiment,
the MME is connected to one or multiple eNodeBs 503 connecting to the UE 504
h the wireless cellular network. The eNodeBs are ted to the network 507
through the serving gateway (S-GW) 505 and the packet data network gateway (P-GW)
2. Systems and Methods for DL and UL MU-MAS processing
Typical downlink (DL) wireless links consist of broadcast physical channels
carrying information for the entire cell and dedicated physical channels with information
and data for given UE. For example, the LTE standard defines broadcast channels such
as P-SS and S-SS (used for synchronization at the UE), MIB and PDCCH as well as
channels for carrying data to given UE such as the PDSCH. In one embodiment of the
present invention, all the LTE broadcast channels (e.g., P-SS, S-SS, MIC, PDCCH) are
ed such that every UE receives its own dedicated information. In a different
embodiment, part of the broadcast channel is precoded and part is not. By way of
example, but not limitation, the PDCCH contains ast information as well as
information ted to one UE, such as the DCI 1A and DCI 0 used to point the UEs
to the resource blocks (RBs) to be used over DL and uplink (UL) channels. In one
embodiment, the broadcast part of the PDCCH is not precoded, whereas the portion
containing the DCI 1A and 0 is ed in such a way that every UE obtains its own
dedicated information about the RBs that carry data.
In another embodiment of the invention, precoding is applied to all or only part of
the data channels, such as the PDSCH in LTE systems. By applying precoding over the
entire data channel, one embodiment of the MU-MAS disclosed in the present
application allocates the entire bandwidth to every UE and the plurality of data streams
of the plurality of UEs are ted via spatial processing. In typical ios,
however, most, if not all, of the UEs do not need the entire bandwidth (e.g., ~70Mbps
per UE, peak data rate for TDD configuration #2 in 20MHz of spectrum). Then, one
embodiment of the MU-MAS in the present ation subdivides the DL RBs in
multiple blocks as in OFDMA systems and assigns each block to a subset of UEs. All
the UEs within the same block are separated through the MU-MAS precoding. In
r embodiment, the MU-MAS allocates different DL subframes to ent subsets
of UEs, thereby dividing up the DL as in TDMA systems. In yet another embodiment,
the MU-MAS both subdivides the DL RBs in multiple blocks as in OFDMA systems
among subsets of UEs and also allocates different DL subframes to different subsets of
UEs as in TDMA systems, thus utilizing both OFDMA and TDMA to divide up the
throughput. For example, if there are 10 APs in a TDD configuration #2 in 20 MHz, then
there is an ate DL capacity of 70 Mbps * 10 = 700Mbps. If there are 10 UEs, then
each UE could receive 70 Mbps rently. If there are 200 UEs, and the ate
throughput is to be divided up equally, then using OFDMA, TDMA or a combination
thereof, the 200 UEs would be divided into 20 groups of 10 UEs, whereby each UE
would receive s/200 = s. As another example, if 10 UEs required 20
Mbps, and the other UEs were to evenly share the remaining throughput, then
20Mbps*10=200Mbps of the 700Mbps would be used for 10 UEs, g 700Mbps-
200Mbps=500Mbps to divide among the remaining 200-10=190 UEs. As such, each of
the remaining 90 UEs would receive 500Mbps/190=2.63Mbps. Thus, far more UEs than
APs can be ted in the MU-MAS system, and the aggregate throughput of all the
APs can be d among the many UEs.
In the UL channel, the LTE standard defines conventional multiple access
techniques such as TDMA or SC-FDMA. In one embodiment of the present invention,
the MU-MAS precoding is enabled over the DL in a way to assign UL grants to different
UEs to enable TDMA and SC-FDMA multiple access techniques. As such, the
aggregate UL throughput can be divided among far more UEs than there are APs.
When there are more UEs than there are APs and the aggregate throughput is
divided among the UEs, as described above, in one embodiment, the MU-MAS system
supports a VRI for each UE, and the VRM controls the VRIs such that VRIs utilize RBs
and resource grants in keeping with the chosen OFDMA, TDMA or SC-FDMA system(s)
used to subdivide the aggregate throughput. In another embodiment, one or more
dual VRIs may support multiple UEs and manage the ling of throughput
among these UEs via OFDMA, TDMA or SC-FDMA techniques.
In another embodiment, the scheduling of throughput is based on load balancing
of user demand, using any of many prior art techniques, depending upon the policies
and performance goals of the system. In another embodiment, scheduling is based
upon Quality of Service (QoS) requirements for particular UEs (e.g.. that pay for a
particular tier of service, guaranteeing certain throughput levels) or for particular types
of data (e.g. video for a television service).
In a different embodiment, UL receive antenna selection is applied to improve
link y. In this method, the UL channel y is estimated at the VRM based on
signaling information sent by the UEs (e.g., SRS, DMRS) and the VRM decides the best
receive antennas for different UEs over the UL. Then the VRM assigns one receive
antenna to every UE to improve its link quality. In a different embodiment, receive
a ion is employed to reduce cross-interference between frequency bands
due to the SC-FDMA scheme. One significant advantage of this method is that the UE
would transmit over the UL only to the AP closest to its location. In this scenario, the UE
can icantly reduce its transmit power to reach the closest AP, thereby improving
battery life. In the same embodiment, different power scaling s are utilized for the
UL data channel and for the UL signaling channel. In one ary embodiment, the
power of the UL signaling channel (e.g., SRS) is increased compared to the data
channel to allow UL CSI estimation and MU-MAS precoding (exploiting UL/DL channel
reciprocity in TDD systems) from many APs, while still limiting the power required for UL
data transmission. In the same ment, the power levels of the UL signaling and
UL data channels are adjusted by the VRM through DL signaling based on transmit
power l methods that equalize the relative power to/from different UEs.
In a different embodiment, maximum ratio combining (MRC) is applied at the UL
er to improve signal y from every UE to the plurality of APs. In a different
embodiment zero-forcing (ZF) or minimum mean squared error (MMSE) or successive
interference cancellation (SIC) or other non-linear techniques or the same precoding
technique as for the DL precoding are applied to the UL to differentiate data streams
being received from different UEs’ areas of coherence. In the same embodiment,
receive l processing is d to the UL data channel (e.g., PUSCH) or UL
control channel (e.g., PUCCH) or both.
3. s and Methods for Concurrent spectrum usage within
actively used um
As detailed in the Background section above, and shown in Figure 6 and
Figure 7 mobile data usage has changed dramatically from being dominated by largely
symmetric voice data to highly asymmetric non-voice data, particularly media such as
video streaming. Most mobile LTE deployments worldwide are FDD LTE, whose
physical layer ure is illustrated in the upper half of Figure 8, which have fixed,
symmetric uplink (“UL”) and downlink (“DL”) channels, and as a , as the DL
channels have become increasingly congested with exponential growth of DL data
relative to UL data, the UL data channels have been increasingly underutilized.
The LTE standard also supports TDD LTE (also called “TD-LTE”) whose
physical layer structure is illustrated in the lower half of Figure 8, and the mobile
operator can choose whether the UL and DL channels are symmetric (as shown in this
illustration) or asymmetric (e.g. with more subframes allocated to either the DL or UL
l), and as a result, as the DL channels become increasingly ted with
exponential growth of DL data relative to UL data, the mobile operator can choose to
allocate more subframes to DL than to UL. For example, in one configuration TD-LTE
supports an 8:1 DL:UL ratio, allocating 8 times as many subframes to DL as to UL.
Other than the fact that TD-LTE is bi-directional in one channel, the structure
and details of TD-LTE and FDD LTE are almost identical. In both modes every frame
has 10ms duration and consists of ten subframes of 1ms each. The modulation and
coding schemes are almost identical, and the upper layers of the protocol stack are
effectively the same. In both cases, the time and frequency reference for the user
equipment (“UE”) devices (e.g. mobile phones, tablets) is provided by the eNodeB (the
LTE base station protocol stack) to all devices (via the DL channel with FDD LTE and
during DL mes with TD-LTE).
Notably, in the case of both FDD and TDD LTE, the network can be configured
so that a UE may only transmit UL data when given a grant to do so by the eNodeB,
received through a DL transmission. As such, the eNodeB not only controls when it
transmits DL data, but it also controls when UEs may transmit UL data.
Also, notably, in the case of an LTE FDD UE, its er is only tuned to its DL
channel and has no receiver tuned to its UL l. As such an FDD UE is “deaf” to
anything that is transmitted in its UL channel by another device.
And, in the case of all LTE UEs, r FDD or TDD, even to the extent their
receivers are tuned to a particular channel, other than certain control signals intended
for all UEs (or for a given UE) which maintain their time reference and tion to the
network, or give them directions at what time and frequency they are to receive data,
they ignore DL data not ed to them. Or to put it another way, the only relevant DL
data to an LTE UE is data that is either control information or is data that is directed to
the UE. During other times, whether the channel is utilized with a DL to another UE, not
utilized at all or utilized for a purpose that falls outside of the LTE standard, the UE is
“deaf” to any DL transmissions that are not control information or DL data directed to
that UE. Thus, LTE receivers, whether FDD or TDD, only receive control data intended
for all UEs or for a given UE, or receive data for a given UE. Other issions in the
DL channel are ignored.
Figure 9 rates how an FDD and TDD network can concurrently e
actively utilize FDD spectrum. The top two lines of boxes labeled “FDD LTE 910”
illustrate one LTE frame interval (10ms) made up of ten 1ms subframe intervals, in both
the Uplink (“UL”) and nk (“DL”) channels. This ration shows the type of
asymmetric data transmission that is increasingly more l (e.g. downlink streaming
video) where there is far more DL data than UL data. Boxes with solid outlines filled with
slanted lines (e.g. box 912 and boxes 911) indicate subframes where data is being
transmitted, boxes with dotted outlines that are blank (e.g. boxes 914) show “idle”
mes were no data is being transmitted (i.e. there are no issions in the
channel during that subframe interval). Boxes 911 are 2 of the 10 DL subframes, all of
which are full of data. Box 912 shows 1 UL subframe which has data. And boxes 914
are 3 of the 9 idle UL subframes which have no data transmissions.
] The middle two lines of boxes in Figure 9 labeled “TDD LTE 920” illustrate one
LTE frame interval (10ms) made up of 10 1ms subframe als, including 2 “Special”
subframe intervals, but unlike the FDD LTE 910 lines, both lines of boxes in the TDD
LTE 920 line not only share the same spectrum with each other, but they share the
same spectrum as the FDD Uplink. This illustration shows asymmetric data
transmission where there are 4 DL subframes and 3 UL mes transmitting data.
Boxes with solid outlines filled with dashed lines (e.g. box 921, box 922 and box 923)
indicate subframes where data is being transmitted, the box with a dotted outline that is
blank (i.e. box 924) shows an idle subframe were no data is being transmitted (i.e. there
are no transmissions in the channel during that subframe al). Box 921 is 1 of 4 DL
subframes, all of which are full of data. Box 922 shows 1 of 3 UL subframes all of which
have data. Box 924 is the 1 idle UL subframe which is empty.
The third two lines of boxes in Figure 9 labeled “FDD+TDD LTE 930” illustrate
one LTE frame interval (10ms) made up of 10 1ms subframe intervals, including 2
“Special” me intervals, and shows the concurrent operation of the FDD LTE 910
system and the TDD LTE 920 system, with the TDD LTE 920 system sharing the same
spectrum as the FDD LTE 910 Uplink. The two systems do not interfere with each other
because, (a) during the subframe interval 912 where the FDD LTE 910 system has UL
data transmission, the TDD LTE 920 system has an idle interval 924 when it is neither
an UL or DL and (b) during the subframe intervals where the TDD LTE 920 system has
transmissions in either the UL or DL direction (e.g. 921, 923 and 922), the FDD LTE 910
system has idle UL intervals (e.g. idle UL subframes 914) with no UL data
transmissions. Thus, the two systems coexist using the same spectrum with no
interference between them.
For FDD LTE 910 and TDD LTE 920 networks to concurrently use the same
spectrum, their operation must be coordinated by either one eNodeB that is set up to
e two spectrum sharing networks concurrently, or by the coordination of an
eNodeB operating the existing TDD LTE 920 network and a second network ller
that could be a second eNodeB or r system compatible with LTE timing and
frame structure, such as the Distributed-Input Distributed-Output Distributed antenna
MU-MAS C-RAN system disclosed in Sections 1 and 2 above and in the Related
Patents and Applications. In any of these cases, both the frames of the FDD LTE 910
and TDD LTE 920 s have to be synchronized, not only in terms of timing, but in
terms of subframe resource allocations. For example, in the case of Figure 9, the
system controlling the FDD LTE 910 system will need to be aware of which subframes
are TDD UL subframes that are available to be used for UL (e.g. will not conflict with
TDD DL control signals sent over subframes #0 and #5 for time and frequency
synchronization at the UE), and use one of those subframes for its FDD UL subframe
912. If the same system is also controlling the TDD LTE 920 system, it will also have to
be sure not to schedule an UL from a TDD device during that subframe 912, and if it is
not controlling the TDD LTE 920 system, it will have to notify er system is
controlling the TDD LTE 920 system to not schedule an UL from a TDD device during
that subframe 912. Of course, it may be the case that the FDD LTE 910 system requires
more than one UL subframe during a frame time, and if so, its controller would use any
or all of the 3 TDD LTE 920 subframes 922 for its UL mes, appropriately
controlling or notifying as described above. Note that it may be the case that in some 10
ms frames all of the UL subframes are allocated to one of the networks and the other
network gets no UL subframes. LTE devices do not expect to be able to transmit UL
data every frame time (e.g. when an LTE network is congested, an LTE device may wait
many frame times before it is granted even a portion of a UL subframe), so one
embodiment of the present invention will function when all of the available TDD LTE 920
UL subframes in a given frame are utilized by one network (i.e. “starving” the other
network of UL subframes). However, starving one k for too many successive
frames or allowing too few UL frames in aggregate will result in poor k
performance (e.g., low UL throughput, or high round-trip latency) and, at some point, if
the LTE devices attached to the network g to transmit UL data may determine the
network is not usable and disconnect. As such, establishing appropriate scheduling
priorities and paradigms to balance the UL subframe resources between the FDD LTE
910 and TDD LTE 920 networks may result in the best overall k mance and
user (and/or UE) experience.
One tool that is available for balancing the UL subframe resources (and to meet
network operator priorities) that is not available in a standalone FDD LTE system are
the TDD LTE Duplex Configurations shown in Figure 10. Figure 9 illustrates TDD LTE
920 system TDD LTE Duplex Configuration 1, in which during the 10 subframes in the
ms frame, there are 4 UL mes, 4 DL subframes and 2 Special subframes. As
can be seen in Figure 10, there are several TDD LTE Duplex Configurations which can
be used, depending on the mobile operator’s needs and data c patterns, and for
balancing the UL subframe resources with the FDD LTE 910 k needs. The TDD
LTE Duplex Configuration can also be changed over time as data traffic patterns
change. Any of the TDD LTE Duplex Configurations can be used with the embodiments
of the ion. For example, in Configuration 1, as shown in Figure 9, 1 UL subframe
has been ted to the FDD network and 3 UL subframes have been assigned to the
TDD network. If the FDD network had a sudden need for more UL throughput, then 2
UL subframes can be allocated for FDD, leaving 2 for TDD, the very next frame time.
So, switching UL subframe allocation between the FDD and TDD network can be
extremely dynamic.
] Note that, if desired, UL resource allocation between the FDD LTE 910 and TDD
LTE 920 networks can be even more fine-grained than a subframe basis. It is possible
to allocate some resource blocks within a single subframe to FDD devices and others to
TDD devices. For example, the LTE standard employs SC-FDMA multiple access
technique for the UL channel. As such, UL ls from FDD and TDD devices can be
ed to different resource blocks within the same subframe via SC-FDMA scheme.
Finally, it is possible to schedule an FDD LTE 910 UL during what would be a
TDD LTE 920 DL or Special subframe. One consideration is that TDD DL control
signals used by the TDD LTE UEs to maintain their connections and maintain timing
(e.g., P-SS and S-SS broadcast signaling sent over subframes #0 and #5) must be
received by the TDD LTE UEs with sufficient regularity or else the UEs may disconnect.
Figure 11 shows the same concept in Figure 9 and described above, except
the shared channel is the FDD DL channel, not the FDD UL channel. The same
subframe filling and ing designations from Figure 9 are used in Figure 11 and as
can be seen, the FDD traffic situation is ed with all of the subframes of FDD LTE
1110 UL channel being used for data while only 1 of the FDD LTE 1110 DL subframes
is used for data, while all of the other DL subframes are “idle” and not transmitting data.
Similarly, all of the TDD LTE 1120 UL subframes are used for data, while all but one of
the TDD LTE 1120 DL subframes are used for data, and in this case the TDD LTE 1120
LTE channel is the same frequency as the FDD LTE 1110 DL l. The result of the
combined FDD LTE 1110 and TDD LTE 1120 networks is shown in the FDD+TDD LTE
1120 channels. As with the example in Figure 9 the two ks can be lled by
a single controller or by coordination of multiple controllers, with scheduling between
them to be sure both networks operate as desired by the network operator with
adequate performance to the users and user devices.
Note that the FDD devices attached to the FDD LTE 1110 network are g
on DL transmissions for control and timing information, as well as for data and they
must receive adequate control signals on a sufficiently r basis to remain
connected. In one embodiment of the invention, the FDD devices use the broadcast
signaling sent by the TDD LTE 1120 network over the DL subframes (e.g., subframes
#0 and #5) to obtain time and ncy synchronization. In a different embodiment,
subframes #0 and #5 carrying broadcast signaling are assigned to the FDD LTE 1110
network and used to derive time and frequency synchronization at every FDD device.
Although, as described above, lly the FDD DL channel is far more
congested than the FDD UL l, there may be reasons why a mobile operator
wishes to share the DL channel. For example, some UL channels are d to only UL
use by the spectrum regulating authority (e.g. there may be concerns about output
power ering with adjacent bands). Also, once a mobile operator begins to offer
TDD devices compatible with its FDD spectrum, the mobile operator will likely find these
devices to be using spectrum more ently than FDD devices and, as such, may
discontinue sales of FDD devices. As old FDD devices gradually are replaced and an
increasing percentage of devices are TDD, the operator may wish to te
increasingly more of its spectrum to TDD devices, but still maintain compatibility with the
remaining FDD devices in the market.
Toward this end, as there are fewer and fewer FDD devices remaining in
operation, the operator may decide to use both the UL and DL bands for TDD operation.
This is illustrated in Figure 12 where FDD LTE 1210 only has one subframe in use for
UL and one for DL and the remainder are idle. There are two TDD LTE networks 1220
and 1230 each respectively using the FDD LTE 1210 UL and DL channels, resulting the
three networks sharing the two channels as show in FDD+TDD LTE 1240. The same
flexibilities and constraints apply as described previously, and there can be a single
controller of all 3 networks or multiple controllers. The two TDD networks can be
operated independently, or by using Carrier Aggregation techniques.
] An operator may also choose to forgo TDD altogether but d add a second
FDD network in the same spectrum as an existing FDD k, but with the Uplink
and Downlink channels swapped. This is illustrated in Figure 13 where FDD LTE 1310
network is very asymmetrically utilized in favor of the DL channel, so only one subframe
is used for UL, and a second FDD LTE 1320 k is also very asymmetrically
utilized in favor of the DL channel, but notice that in Figure 13 the channel tion for
FDD LTE 1320 is swapped, with the FDD Downlink channel shown above the FDD
Uplink channel, contrary to the channel order for FDD LTE 1310 or as shown in prior
figures. In the case of both FDD LTE 1310 and 1320, the DL channel leaves one DL
me idle that corresponds with the one UL frame that is used by the other network.
When the networks are combined as shown in FDD+TDD LTE 1230, all of the
mes in both channels are DL, except for mes 1231 and 1232. Thus, 90% of
the subframes are devoted to DL, which better matches mobile traffic patterns as they
have evolved than symmetric spectrum allocation for UL and DL.
Also, this structure enables the controller (or controllers) that manage the
network to dynamically change the number of UL and DL subframes allocated to each
network on a subframe-by-subframe basis, affording extremely dynamic UL/DL traffic
adaptation, despite the fact that FDD devices are using both networks.
As with the combined FDD/TDD networks previously described, the same
constraints apply for FDD mode in that the LTE devices must receive sufficient control
and timing information to remain connected and e well, and they need sufficiently
regular and adequate number of UL frames.
The two FDD networks can be operated independently or through r
Aggregation.
In another embodiment, the control information itted by the DL channel
an existing active network (e.g. in Figures 9, 11, 12 and 13 FDD LTE 910, FDD LTE
1110, FDD LTE 1210, or FDD LTE 1310) is used by a new network (or networks) using
the same channel (e.g. in Figures 9, 11, 12 and 13 TDD LTE 920, TDD LTE 1120, TDD
LTE 1220 and TDD LTE 1230, or FDD LTE 1320) to determine which subframes and/or
resource blocks and and/or other intervals will be idle. In this way, the new k(s)
can determine when it is able to it (whether DL or UL) without interfering with the
existing active k. This embodiment may make it possible to concurrently use the
spectrum of the existing active network without any modification of the existing active
network or relying upon any special connection to the existing active network’s
controller, since it is just a matter of the controller of the new network(s) receiving what
is already in the DL transmission from the existing active network. In another
embodiment, the only modification to the existing active k is to make sure it
enables the new network(s) to transmit ial control and timing ation to
in connections with UEs. For example, the existing active network could be
configured to not it during times when essential timing and synchronization
information are being transmitted, but otherwise operate unmodified.
Although the above ments of concurrently supporting networks in the
same spectrum used the LTE standard for examples, similar techniques can be utilized
with other wireless protocols as well.
4. Utilizing Distributed Antenna MU-MAS concurrently with actively
used spectrum
The Distributed Antenna MU-MAS techniques (collectively called “DIDO”) as
disclosed in Sections 1 and 2 and in the d Patents and Applications, ically
increase the capacity of wireless networks, improve reliability and throughput per
device, and make it le to reduce the cost of devices as well.
In general, DIDO operates more efficiently in TDD than FDD networks because
the UL and DL are in the same channel and, as a result, training transmission received
in the UL channel can be used to derive channel state information for the DL channel by
exploiting channel reciprocity. Also, as described above, TDD mode inherently better
suits the asymmetry of mobile data, allowing for more efficient spectrum utilization.
] Given that most of the s current LTE deployments are FDD, by utilizing the
techniques disclosed in Section 3, it is possible to deploy a TDD network in spectrum
actively used for FDD, and DIDO can be used with that new TDD network, y
dramatically increasing the capacity of the spectrum. This is particularly significant in
that, UHF frequencies propagate far better than microwave ncies, but most UHF
mobile frequencies are already in use by FDD networks. By combining DIDO-based
TDD networks with existing FDD networks in UHF spectrum, an exceptionally efficient
TDD k can be deployed. For example, Band 44 is a TDD band from 703-803
MHz, overlaying a large number of 700 MHz FDD bands in the U.S. Band 44 devices
could be used concurrently in the same spectrum as 700 MHz FDD devices, enabling
DIDO TDD in prime spectrum.
DIDO does not add significant new constraints to the spectrum combining
techniques described above. The DRAN 104 shown in Figure 1 would either replace
the existing eNodeBs in the coverage area, or coordinate with the ng s
401, as shown in Figure 4 per the subframe (or ce block) sharing techniques
described above.
Notably, if the DIDO system is controlling the entire system and providing the
eNodeB for the FDD network, then DIDO can use a training signal such as the SRS UL
from the FDD devices so as to decode via spatial processing the UL from multiple
existing FDD devices at the same time and within the same frequency band, thus
dramatically increasing the spectral efficiency of the existing FDD UL channel and also
ng the UL power required r receiving better signal quality) since the
buted DIDO APs are likely closer to the UEs than a single cellular base station, and
also can utilize signal combining ques, such as maximum ratio combining (MRC)
or other techniques as described previously for DIDO.
Thus, DIDO can replace existing eNodeBs and simultaneously use existing
spectrum with DIDO TDD s, while also applying the benefits of DIDO to the UL of
the existing FDD devices that are already ed.
. Mitigating interference in actively used spectrum
As noted previously, when a TDD k is deployed in either UL or DL
frequencies in a band that has been allocated as an FDD band, there may be concerns
about output power interfering with adjacent bands. This can be caused by out of band
emissions (OOBE) interference and/or er “blocking” or receiver sitization”.
OOBE refers to power emissions outside of the allocated band. OOBE are lly are
at highest power in frequencies immediately adjacent to a transmit band and typically
diminish as frequencies become more distant to the transmit band. “Receiver blocking”
or “receiver desensitization” refers to a receiver’s front-end amplifier losing sensitivity to
a desired in-band signal due to the presence of a powerful out-of-band signal, typically
in a nearby band.
When regulatory authorities (e.g. the FCC) allocate spectrum in adjacent bands
for use by le mobile operators or other users of spectrum, typically rules are put in
place to limit OOBE and power levels so that mobile devices (e.g. mobile ) and
base stations can be manufactured to practical specifications given logy available
at the time of the regulatory ruling. Further, consideration is given to existing users of
adjacent um and the rules under which those devices were manufactured. For
example, a new allocation of spectrum may take into account the availability of
technology that will better tolerate OOBE to better reject powerful out-of-band
transmissions than technology made during prior spectrum allocations, where older
technology was deployed that is more sensitive to OOBE and powerful out-of-band
transmissions. Since it is often impractical to replace prior generation base stations and
mobile devices, it is necessary for the new deployments to adhere to the OOBE and
powerful out-of-band transmission tions of the prior deployments.
In the case of TDD deployments in FDD bands, there are additional constraints
that must be adhered to. In an FDD pair, each of the UL or DL bands was allocated with
an expectation of, respectively, UL-only transmissions or DL-only transmissions. Since
TDD its alternatively in both UL and DL, then if a TDD deployment is operating in
a FDD band the was previously allocated as UL-only or DL-only band, then it is
operating in a transmit direction that was not anticipated. Thus, to be sure the TDD
transmissions do not interfere with previously-defined FDD usage in adjacent spectrum,
the TDD transmissions in the opposite direction of the previously-defined FDD usage
must meet the emission requirements for the existing usage. For example, if TDD is
deployed in an FDD UL band, then the UL part of the TDD transmission should not be a
problem, since UL is the direction of usly-defined usage. But, since the DL part of
the TDD transmission is in the opposite direction of the previously-defined UL usage,
lly the TDD DL transmission must meet the OOBE and powerful out-of-band
transmission requirements d for UL transmissions.
In the case of deploying TDD in an UL band, the UL part of the TDD
transmission will typically be a transmission from a mobile device (e.g. a mobile phone).
FDD phones in adjacent bands and base stations in adjacent bands will have been
designed to tolerate the UL transmissions from mobile phones in adjacent bands. For
example, Figure 16a shows the FDD band 7 UL band divided into sub-bands A through
G. FDD mobile phones and base ns operating in shaded sub-band E are designed
to tolerate UL transmission in FDD sub-bands A through D, F and G. Thus, if a TDD
device is operated in nt nd D (as shown shaded in Figure 16b in TDD
band 41 sub-band D, the same frequency as FDD band 7 sub-band D), the FDD band 7
mobile phone and base station devices will have no issue with UL part of the TDD
transmission in band 41 sub-band D.
But, the DL transmission in TDD band 41 sub-band D is not a scenario that was
anticipated in the tion of FDD band 7 or in mobile phones and base stations
designed to operate in that band. Let’s consider each device in turn.
In the case of a FDD band 7 mobile phone in sub-band E, it is unlikely to be
adversely impacted by base station DL transmissions in adjacent TDD band 41 subband
D e a mobile phone’s band 7 receiver is designed to reject UL
transmissions from other mobile phones transmitting in adjacent UL bands. In normal
usage, mobile phones might operate within inches of each other (e.g. if two people
seated next to each other at a stadium are both making calls) resulting in very high
it power incident upon each phone’s receiver. Technologies (e.g. cavity filters)
reject such powerful nearby band transmissions, ng mobile phones that are
physically close to mobile phones using an adjacent band to transmit UL signals without
ely impacting the adjacent mobile phone’s DL reception.
But the case of a FDD band 7 base station operating in sub-band E is different.
Its receiver was designed to receive UL from mobile devices in FDD band 7 sub-band E
and to reject UL from mobiles devices in adjacent FDD band 7 sub-bands A through D,
F and G. It was also designed to reject DL transmissions in band 38 TDD sub-band H
and band 7 FDD DL in sub-bands A’-H’ shown in Figure 16a. Thus, the only scenario
the FDD band 7 base station was not designed for is to reject DL transmissions from
other base stations in sub-band A through D, F and G. We shall consider this case.
Figures 15a, 15b, 15c and 15d consider four transmission scenarios between a
TDD band 41 base station (BTS) 1510 on structure 1501 (e.g. a building, a tower, etc.)
transmitting in nd D and an FDD band 7 base station (BTS) 1530 on structure
1502 receiving in UL nd E and transmitting in DL sub-band E’. In scenario:
a. 15a: there no path between TDD BTS 1510 and FDD BTE 1530 because the
transmission is completely obstructed by building 1505 and there is no path
route around building 1505, and as a result no TDD DL signal will reach FDD
BTS 1530.
b. 15b: there is only a Line of Sight (LOS) path between TDD BTS 1510 and FDD
BTS 1530. A LOS path will result in a very ul TDD DL signal reaching FDD
BTS 1530.
c. 15c: there is a Non-Line of Sight (NLOS) path n TDD BTS 1510 and FDD
BTS 1530, but no LOS path. While it is possible that an NLOS path is via a highly
efficient reflector (e.g. a large wall of metal) that is exactly angled such that the
signal reaching FDD BTS 1530 approaches the power of an LOS signal, it is
statistically unlikely in real-world scenarios that an NLOS path exists that
approaches the efficiency of a LOS path. In contrast, what is likely in orld
ios is that an NLOS path will be affected by objects that t and r
in a variety of angles as well as objects that absorb and refract the signal to a
greater or lesser degree. Further, by definition NLOS paths are longer than LOS
paths resulting in higher path loss. All of these factors result in significant path
loss in NLOS paths relative to LOS paths. Thus, statistically, it is likely in realworld
scenarios that the TDD DL NLOS signal power received by the FDD BTS
1530 will be much less than the TDD DL LOS signal power received by the FDD
BTS 1530 as illustrated in Figure 15b.
d. 15d: there is both an LOS and NLOS path between TDD BTS 1510 and FDD
BTS 1530. This scenario is effectively the sum of scenarios 15b and 15c,
resulting in the FDD BTS 1530 receiving the sum of a very powerful signal from
the LOS path from TDD BTS 1510 as well as a statistically much weaker signal
from the NLOS path from TDD BTS 1510.
In ering the four scenarios of the previous paragraph, clearly scenario 15a
presents no issue at all since there is no signal received by FDD BTS 1530. NLOS
scenario 15c results in some TDD DL BTS 1510 signal reaching FDD BTS 1530, but
statistically it is a much weaker signal than an LOS signal. Further, in the unlikely, but
possible, scenario where an NLOS path is a highly efficient reflector, then that can often
be mitigated by site planning, e.g., repositioning or repointing the TDD DL BTS 1510
antenna such that the NLOS path is not efficiently reflected. Scenarios 15b (LOS) and
15d (LOS + NLOS) are the problematic scenarios because of the LOS component in
each resulting in a high power signal in an adjacent band, which the FDD BTS 1530
was not ed to tolerate.
While the NLOS components of scenarios 15c and 15d certainly can result in a
lower power signal received by the FDD BTS 1530 in an adjacent UL band, the FDD
BTS 1530 is designed to reject lower power, largely NLOS signal from the entire UL
band from mobile devices, e.g., using cavity filters. Thus, if the LOS component of
scenarios 15b and 15d can be mitigated, leaving only a lower power (e.g. ng
unlikely highly efficient reflections) NLOS signal component from scenarios 15c and
15d, then this would result in the FDD BTS 1530 only receiving transmissions in the UL
band at power levels it was designed to tolerate and would thus enable DL
transmissions from TDD BTS 1510 in the UL band without disrupting the operation of
the FDD BTS 1530. As noted previously, no other transmission direction in the FDD UL
band will disrupt adjacent band operation and, thus, if the TDD DL BTS 1510 LOS
transmission component to the FDD BTS 1530 can be mitigated, then FDD UL bands
can be used for TDD ectional operation without disrupting adjacent band FDD
operation.
As previously disclosed in the Related Patents and Applications, a multi-user
multi-antennas system (MU-MAS), such as the DIDO system, the logy marketed
under pCell™ trademark, or other multi-antenna s are able to utilize channel
state information (CSI) knowledge from the location of a user a to either
synthesize a coherent signal at the location of the user antenna, or synthesize a null
(i.e. zero RF energy) at that location. Typically, such CSI is determined from an in-band
(IB) training , either transmitted from the base station to the user device, with the
user device ding with CSI ation, or transmitting from the user device to the
base station, with the base station exploiting reciprocity to determine CSI as the location
of the user antenna.
In one embodiment the MU-MAS system as depicted in Fig. 14 and es as
described in Sections 1-4, above, estimates the CSI at each UE location 111,
synthesizing independent pCells 103 (pCell1, pCell2, … pCellM) in the same ncy
band at each UE location 111 with the signal from each of the respective VRIs 106
(VRI1, VRI2, … VRIM). In addition to estimating the CSI at each UE location 111 as
described in n 1-4 above, in this embodiment the MU-MAS system also estimates
CSI at each antenna 1403 shown on structures 1431-1433 and as it synthesizes pCells
103 at each location 111, it also concurrently synthesizes pCells 1411 (pCells 1..7,
8..14, and (b-6)..b, (collectively, pCells1..b)) at the location of each antenna 1403, with all
pCells in the same ncy band. But unlike pCells 103, which each contains a
synthesized waveform from its respective VRI, each pCell 1411 is a null with zero RF
energy.
In one embodiment the null pCells 1411 bed in the previous paragraph are
synthesized by instantiating VRIs 1466 that input flat (Direct Current (DC1..b)) signals to
the VRM 108. In another embodiment, they are calculated within the VRM as null
locations using techniques previously disclosed in the Related Patents and Applications
for synthesizing null signal (zero RF energy) contributions at antenna locations.
When an in-band (“IB”) training signal is used to estimate the CSI at the location
of each antenna 1403, a highly accurate CSI estimation will result, using the techniques
described in ns 1 through 4 and in the Related Patents and ations. For
example, if the pCell transmission band is from 2530 to 2540 MHz, band D in Fig. 16b, if
a training signal in the same frequency range of 2530 to 2540 is used, a highly accurate
CSI estimation will result. But when an out-of-band (“OOB”) signal (e.g. at 2660 to 2670
MHz) is used to te the CSI at the location of an a instead of an IB signal
(e.g. at 2530 to 2540 MHz, band E’ in Fig. 16a), such an OOB CSI estimate will only be
reasonably accurate if the channel is “frequency flat” between the IB and OOB
frequencies. Frequency flat means that the channel has flat fading in both the IB and
OOB frequencies, such that the signals in each of the IB and OOB frequencies
experience the same magnitude of fading. If the IB and OOB frequencies have selective
, i.e. frequency components of IB and OOB frequencies experience elated
fading, then using the CSI te obtained from an OOB signal may not be very
accurate for an IB signal. Thus, if band E’ of Fig. 16a is frequency flat relative to band D
of Fig. b then a training signal in band E’ can be used to obtain a highly accurate CSI for
band D. But, if band E’ has significant ive fading ve to band D, then a training
signal from band E’ will not result in an accurate CSI for band D.
A purely LOS signal in free space where there is no NLOS component (e.g. as
rated in Fig. 15b) is in a frequency-flat channel. Thus, if the only component to the
signal is LOS, then an OOB signal can be used to accurately estimate the CSI for an IB
signal in at the location of a user antenna. In many real-world deployments, however,
there is not a purely LOS signal, but rather there is either no signal at all (e.g. Fig. 15a),
only an NLOS signal (e.g. Fig. 15c) or a combined LOS and NLOS signal (e.g. 15d).
If an OOB signal is used to estimate the CSI of FDD BTS 1530’s antenna from
the perspective of TDD BTS antenna 1510, then the following be the results for each of
the scenarios in Figs. 15a, 15b, 15c and 15d:
a. 15a: no signal, so no CSI will .
b. 15b: LOS-only will result in CSI that is tently accurate.
c. 15c: NLOS-only will result in CSI that is not consistently accurate due to the
likelihood of selective fading from the NLOS-only channel.
d. 15d: LOS + NLOS that, the resulting CSI will be a combination of CSI
components where the NLOS component is not consistently accurate and LOS
component is tently accurate.
We refer to the CSI derived from a pure LOS channel as CL, the CSI derived
from a pure NLOS channel as CN, and the CSI derived from a l with a
combination of pure LOS and pure NLOS components as CLN. The CSI of a combined
LOS and NLOS can then be formulated as CLN = CL + CN.
In the case of a pure LOS l between Access Points 109 (AP1..N) and
antennas 1403 in Fig. 14, then the only CSI component is a CL for each antenna 1403.
Since pure LOS channels are frequency flat, if an OOB signal is used for the deriving
the CSI, the CSI for each a 1403 will still be accurate. Thus, when using an OOB
signal to derive the CSI, the LOS signal from each AP 109 will be nulled with a high
degree of accuracy at the location of each antenna 1403, resulting in little or no
detectable signal by each antenna 1403 from the transmissions of APs 109.
In the case of a pure NLOS channel between APs 109 and the antennas 1403,
then the only CSI component for is a CN for each antenna 1403. If an OOB signal is
used for the deriving the CSI, the CSI for each antenna 1403 will be more or less
accurate, depending on how frequency flat the channel is. Thus, when using an OOB
signal to derive the CSI, the NLOS signal from each AP 109 will be either nulled
completely (in the case of a perfectly frequency-flat channel), partially nulled, or not
nulled at all, depending on the degree of channel frequency selectivity. To the extent the
NLOS signals are not nulled, each antenna 1403 will receive some random summation
of the NLOS signals from the APs 109. Thus, there may be some reduction in the NLOS
signal strength from APs 109 to the antennas 1403, but the NLOS signal strength will be
no higher than NLOS signal strength than would have been received had no CSI been
applied to attempt to null the NLOS signals.
In the case of a combined LOS and NLOS channel between APs 109 and the
antennas 1403, then the CSI is a combination of LOS and NLOS components CLN = CL +
CN for each antenna 1403. If an OOB signal is used for the ng the CSI, the CL
ent of the CSI for each antenna 1403 will be highly te and CSI for CN
component will be more or less accurate, depending on how frequency flat the channel
is. The CL component of the CSI affects the g of the LOS component of the signal
between the APs 109 and the antennas 1403, while the CN component of the CSI
affects the g of the NLOS component of the signal between the APs 109 and the
antennas 1403. Thus, when using an OOB signal to derive the CSI, the LOS signal from
each AP 109 will be consistently nulled completely, while the NLOS signal from each
AP 109 will be nulled to a greater or lesser degree, depending on the degree of channel
frequency ivity. So, in sum, the LOS components of the transmissions from APs
109 will be completely nulled, and NLOS components of the transmissions from APs
109 will have no greater signal strength than would have been received by the antennas
1403 had no CSI been applied to attempt to null the NLOS s.
As previously noted above, in the scenarios shown in Figures 15a, 15b, 15c,
and 15d, the problematic scenarios are when the LOS component of TDD BTS 1510 is
received by FDD BTS 1530. It is generally not a problem when the NLOS component of
TDD BTS 1510 is received by FDD BTS 1530. Consider the MU-MAS embodiment
described in the preceding paragraphs: If TDD BTS 1510 is one of the APs 109 from
Fig. 14 and FDD BTS 1530 is one of the as 1403, then if the training signal used
to determine the CSI for antennas 1403 is an IB signal, then transmission from TDD
BTS 1530 will be completely nulled at FDD BTS 1530. If the training signal used to
determine the CSI for as 1403 is an OOB signal, then the LOS transmission from
TDD BTS 1530 will be completely nulled at FDD BTS 1530, and the NLOS transmission
from TDD BTS 1530 to FDD BTS 1530 will be no worse than if no CSI had been applied
to attempt to null the NLOS signals. Thus, an OOB training signal from a 1530
will completely null any LOS component of a transmission from antenna 1510, but will
neither reliable null nor make any stronger any NLOS component of a transmission from
a 1510.
Since only the LOS component of the signal transmitted from antenna 1510 is
problematic and it has been nulled, and NLOS component of antenna 1510 is not
problematic and won’t be made any worse, we thus have an embodiment in which a
TDD BTS 1530 can operate in a MU-MAS system such as that shown in Fig. 14 in FDD
UL spectrum without significantly disrupting the receiver performance of an adjacent
band FDD BTS, provided that at least an OOB signal from the FDD BTS is available.
In the case of many FDD systems, such an OOB signal is indeed available. For
example, in Fig. 16a, the FDD BTS 1530 that is receiving UL in sub-band E is
concurrently transmitting DL in nd E’. While data traffic may vary in the DL subband
, the control signals typically (e.g. in the LTE standard) are transmitted repeatedly.
So, at a minimum, these DL control signals can be used as the OOB ng signal
used for determining the CSI of the FDD BTS 1530, utilizing ocity techniques
previously disclosed in the Related Patents and Applications, and applying the CSI
derived from channel reciprocity of the DL transmission from FDD BTS 1530
(corresponding to antennas 1403 in Fig. 14) in nd E’ to create a null at FDD BTS
1530 (corresponding to antennas 1403 in Fig. 14) in sub-band D concurrently with the
TDD DL transmission from TDD BTS 1510 (corresponding to APs 109 in Fig 14) to UEs
at locations 111. The LOS ent of the sub-band D TDD DL ission from
TDD BTS 1510 (corresponding to APs 109 in Fig 14) will be completely nulled at FDD
BTS 1530 (corresponding to antennas 1403 in Fig. 14), while the NLOS component of
the sub-band D TDD DL transmission will be no worse that it would be had been had
there been no nulling of the LOS component.
In addition to creating a null for TDD DL transmissions at the on of FDD
BTS locations 1530 within the bandwidth of the TDD DL transmissions, it is desirable to
also null high power OOBE from the TDD DL transmission at the FDD BTS locations.
Because the OOBE from the LOS component is in a frequency-flat channel, then nulling
of the d LOS component will also null the OOBE from the LOS component.
However, to the extent the NLOS ent is in a frequency-selective l, the
OOBE of the NLOS component will not be nulled, but it will be no worse than the OOBE
from the NLOS would have been had there been no attempt to null the LOS component.
The power of the OOBE of each of the LOS and NLOS transmissions is proportionate to
the power of the in-band LOS and NLOS transmissions, respectively. Thus, nulling the
OOBE of the LOS transmission, and making the OOBE of the NLOS transmission no
worse than it would ise have been, addresses the highest-power and most
problematic OOBE component, LOS, will making the less-problematic NLOS
component no worse.
FDD base stations typically have multiple antennas for ity, beamforming,
MIMO or other reasons. This scenario is depicted in Fig. 14 where there are le
antennas 1411 on each structure 1431-1433. So, rather than the single FDD BTS
a 1530 depicted in Figs. 15a, 15b, 15c and 15d, typically there would be multiple
FDD BTS antennas 1411. To the extent any such antennas are transmitting, then the
MU-MAS system described above and depicted in Fig. 14 would receive a transmission
from each of the antennas 1411 that it would use to derive the CSI for each antenna
and null the LOS component of the APs 109 transmissions to that antenna. In another
embodiment, nulls would only be created for some of the BTS antenna 1411. For
example, some of the antennas 1411 might not be used in UL reception, and it would be
unnecessary to create a null for them.
In a wide-scale deployment of the above embodiments, many TDD BTS
antennas and adjacent sub-band FDD BTS antennas would be distributed throughout a
large coverage area (e.g. a city, a region, a y or a ent). Clearly, not all
antennas would be within range of each other, and as such it would only be ary
to null a TDD BTS DL transmission that is of ient power levels to interfere with a
given FDD BTS antenna. In one embodiment, the VRM 108 receives from TDD BTS DL
APs 109 transmissions from FDD BTS antennas 1403 and assesses the power level
nt from the TDD BTS APs 109 upon each FDD BTS antenna 1403 from each TDD
BTS AP 109. Various means can be used to make this assessment, including utilizing
channel reciprocity. The VRM 108 only synthesizes nulls at the FDD BTS antennas
1403 that would be receiving OOBE or receiver ng/receiver desensitization power
above a given threshold. The threshold can be set to any level, including, but not limited
thresholds that are determined to be an interfering threshold or a threshold established
by spectrum regulations.
The null pCells 1411 are similar to pCells 103 transmitting a signal in that they
require computing resources and AP 109 resources. Thus, it is advantageous to
minimize the number of AP 109 resources needed to create null pCells throughout the
coverage area. In another ment clustering techniques such as those previously
disclosed in the Related Patents and Applications can be utilized to reduce the number
of APs 109 needed to synthesize the pCells 103 needed for user devices and pCells
1411 needed to null antennas 1403 throughout the coverage area.
The embodiments described above address creating nulls at FDD DL antennas
that have no knowledge of the TDD operation in adjacent spectrum. In another
ment the FDD DL antennas do have knowledge of the TDD operation in
nt spectrum and cooperate with the TDD system. In one embodiment, the FDD
DL antennas 1403 regularly transmit a training signal within the TDD band (e.g. such as
the LTE SRS signal) the enables the MU-MAS system in Fig. 14 to have an IB
reference for determining accurate CSI for the FDD DL antennas 1403. With accurate
CSI the VRM 108 will be able to synthesize a null for both the LOS and NLOS
components, thus enabling a very high power TDD DL transmission to be used in
adjacent spectrum since even the NLOS signal will be nulled. In another ment
the FDD DL transmission is timing and/or ncy interleaved with training signals
from either the UEs (such as SRS) or the TDD DL BTS. In another embodiment the
FDD DL antennas 1403 also transmit an IB training signal in their own UL spectrum
(e.g. choosing a time when there is no concurrent UL activity) that the VRM 108 can use
to determine the OOBE CSI and create nulls for both the NLOS as well as the LOS
OOBE.
In another embodiment the antennas 1403 are TDD as used in adjacent
TDD spectrum. When adjacent TDD systems are synchronized in UL and DL, then
interference from OOBE and receiver blocking/receiver desensitization is minimized
since all BSTs are in transmit or receive mode at the same time. Sometimes there is a
need to have adjacent TDD system operate without synchronizing DL and UL times, for
example, if adjacent ks e different DL and UL ratios or if they have different
y requirements, e.g., if one network needs more frequent DL or UL intervals to
reduce round-trip latency. In these scenarios, adjacent bands will be in use with UL and
DL at the same time. The same techniques bed above can be used for one or
both systems to synthesize nulls at the BST antennas of the other system during DL
intervals. Per the techniques described above, one or both of the in-band and the
OOBE transmissions can be nulled, either nulling the LOS component or the NLOS
component as well.
In one embodiment the same spectrum for the MU-MAS system in Fig. 14 is
used to provide terrestrial wireless services while it is concurrently used as a DL band
(i.e. with transmissions ed skyward) for aircraft. Even though the MU-MAS system
is intended for terrestrial use, to the extent the ft falls within the antenna pattern of
the APs 109 the path from the APs 109 to the ft will be LOS or largely LOS and
potentially could interfere with the DL to the aircraft. By receiving the UL (i.e.
transmission directed to the ground) from the aircraft, the VRM can derive the CSI to the
aircraft as using the techniques described previously and thus synthesize a null
at the locations of the aircraft antennas. Since the path to the aircraft is LOS, the CSI
can be quite accurate, even if the aircraft UL signal is OOB. Thus, in this way spectrum
can be concurrently used with aircraft DL. This is a very efficient use of spectrum since
aircraft do not fly by very often and if spectrum were reserved exclusively for aircraft, it
would be inactive most of the time.
In another embodiment the aircraft’s antenna(s) are treated as one or more UEs
along with the terrestrial UEs, and when the aircraft flies within range of the MU-MAS
system show in Fig. 14, it uses UL and DL capacity the same as any other UEs. Multiple
antennas can be used on the aircraft to increase capacity. The antennas can be located
spread apart from each other on or in the aircraft and can be polarized to se
capacity. Individuals within the aircraft can also use their own devices (e.g. mobile
phones) in the same spectrum, ted to the same MU-MAS. The MU-MAS would
create independent pCells for the aircraft antennas and for the user UEs.
Embodiments of the invention may include s steps, which have been
described above. The steps may be embodied in machine-executable instructions
which may be used to cause a general-purpose or special-purpose processor to
perform the steps. Alternatively, these steps may be performed by ic hardware
components that contain hardwired logic for performing the steps, or by any
combination of programmed computer components and custom hardware components.
As described herein, instructions may refer to specific configurations of
hardware such as application specific integrated circuits ) ured to m
certain operations or having a predetermined functionality or software instructions
stored in memory embodied in a non-transitory computer le medium. Thus, the
techniques shown in the figures can be implemented using code and data stored and
executed on one or more electronic devices. Such electronic devices store and
communicate nally and/or with other onic devices over a network) code and
data using computer machine-readable media, such as non-transitory computer
machine-readable storage media (e.g., ic disks; optical disks; random access
memory; read only memory; flash memory devices; phase-change memory) and
transitory computer machine-readable communication media (e.g., electrical, optical,
acoustical or other form of ated signals – such as carrier waves, infrared signals,
l signals, etc.).
Throughout this detailed description, for the purposes of explanation, numerous
specific s were set forth in order to provide a thorough understanding of the
present invention. It will be apparent, however, to one skilled in the art that the
invention may be practiced without some of these specific s. In certain instances,
well known structures and ons were not described in elaborate detail in order to
avoid obscuring the subject matter of the present invention. Accordingly, the scope and
spirit of the invention should be judged in terms of the claims which follow.
Claims (20)
1. A system comprising: a first wireless k ing with a first protocol
and comprising a ity of wireless transceiver stations that share a cell ID and
tively transmit a plurality of simultaneous non-interfering precoded data s to
a plurality of user ent (UE) within a same frequency band, a second wireless
network operating with a second protocol and comprising one or a plurality of antennas,
wherein the first wireless network creates one or a plurality of points of zero radio
frequency (RF) energy at the location of the one or at least one of the plurality of
antennas.
2. The system as in claim 1 wherein the one or the plurality of points of zero RF
energy are created to mitigate out-of-band emission (OOBE) or blocking from the first
wireless network to the second wireless network.
3. The system as in claim 1 wherein the first wireless network is a multi-user
multiple antenna system (MU-MAS) that uses precoding to create the one or the
plurality of points of zero RF energy.
4. The system as in claim 1 wherein the first wireless network is a multi-user
multiple antenna system (MU-MAS) that uses precoding to create the one or the
plurality of points of zero RF energy and the precoding is computed based on channel
state information (CSI) between the plurality of wireless transceiver stations of the first
wireless network and the one or the plurality of antennas of the second wireless
network.
5. The system as in claim 1 wherein the first wireless network is a multi-user
multiple a system (MU-MAS) that uses ing to create the one or the
plurality of points of zero RF energy and the precoding is computed based on channel
state information (CSI) between the ity of wireless transceiver stations of the first
wireless network and the one or the plurality of antennas of the second wireless
k, and wherein the CSI is estimated using in-band or out-of-band ng signals
sent over a plurality of wireless links between the plurality of wireless transceiver
stations and the one or the plurality of antennas.
6. A system comprising: a first wireless network operating with a first protocol
and comprising a plurality of wireless transceiver stations that share a cell ID and
tively transmit a plurality of aneous non-interfering precoded data streams to
a plurality of user equipment (UE) within a same frequency band, a second wireless
network operating with a second protocol and comprising one or a plurality of antennas,
wherein the first wireless network creates one or a plurality of points of zero radio
frequency (RF) energy at the location of the one or at least one of the plurality of
antennas, and the second ss network has knowledge of the first ol of the
first wireless network.
7. The system as in claim 6 wherein the one or the plurality of points of zero RF
energy are created to mitigate out-of-band emission (OOBE) or blocking from the first
wireless network to the second wireless network.
8. The system as in claim 6 wherein the first ss network is a multi-user
multiple antenna system (MU-MAS) that uses precoding to create the one or the
plurality of points of zero RF energy.
9. The system as in claim 6 wherein the first wireless k is a user
multiple antenna system (MU-MAS) that uses precoding to create the one or the
plurality of points of zero RF energy and the precoding is computed based on channel
state information (CSI) n the plurality of wireless transceiver stations of the first
wireless network and the one or the plurality of antennas of the second wireless
network.
10. The system as in claim 6 wherein the first wireless network is a multi-user
multiple antenna system (MU-MAS) that uses precoding to create the one or the
ity of points of zero RF energy and the precoding is ed based on channel
state information (CSI) between the plurality of wireless transceiver stations of the first
wireless network and the one or the plurality of as of the second wireless
network, and wherein the CSI is estimated using in-band or out-of-band training signals
sent over a plurality of wireless links between the ity of ss eiver
stations and the one or the plurality of antennas.
11. A method for communicating over a network comprising: a first wireless
network operating with a first protocol and comprising a plurality of wireless eiver
stations that share a cell ID and collectively transmit a plurality of simultaneous noninterfering
precoded data streams to a plurality of user equipment (UE) within a same
frequency band, a second wireless network operating with a second protocol and
comprising one or a plurality of antennas, the first wireless network creating one or a
plurality of points of zero radio frequency (RF) energy at the location of the one or at
least one of the plurality of antennas.
12. The method as in claim 11 wherein the one or the plurality of points of zero
RF energy are created to te out-of-band emission (OOBE) or blocking from the
first wireless k to the second wireless k.
13. The method as in claim 11 wherein the first ss network is a multi-user
multiple antenna system (MU-MAS) that uses precoding to create the one or the
plurality of points of zero RF .
14. The method as in claim 11 n the first wireless network is a multi-user
multiple antenna system (MU-MAS) that uses precoding to create the one or the
plurality of points of zero RF energy and the precoding is computed based on channel
state information (CSI) between the plurality of wireless transceiver stations of the first
wireless network and the one or the plurality of antennas of the second wireless
15. The method as in claim 11 wherein the first wireless network is a multi-user
multiple antenna system (MU-MAS) that uses preceding to create the one or the
plurality of points of zero RF energy and the precoding is computed based on l
state information (CSI) between the plurality of wireless transceiver stations of the first
wireless network and the one or the plurality of antennas of the second wireless
network, and wherein the CSI is estimated using in-band or out-of-band training signals
sent over a plurality of wireless links between the plurality of wireless transceiver
stations and the one or the plurality of antennas.
16. A method for communicating over a network comprising: a first wireless
network operating with a first protocol and comprising a plurality of ss transceiver
stations that share a cell ID and tively it a plurality of simultaneous erfering
precoded data s to a plurality of user equipment (UE) within a same
frequency band, a second wireless network operating with a second protocol and
comprising one or a plurality of antennas, the first wireless network creating one or a
ity of points of zero radio frequency (RF) energy at the location of the one or at
least one of the plurality of antennas, and the second wireless network having
knowledge of the first protocol of the first wireless network.
17. The method as in claim 16 wherein the one or the plurality of points of zero
RF energy are created to te out-of-band emission (OOBE) or blocking from the
first wireless network to the second wireless network.
18. The method as in claim 16 wherein the first wireless network is a multi-user
multiple antenna system (MU-MAS) that uses ing to create the one or the
plurality of points of zero RF energy.
19. The method as in claim 16 wherein the first wireless network is a multi-user
multiple antenna system (MU-MAS) that uses precoding to create the one or the
plurality of points of zero RF energy and the precoding is computed based on channel
state ation (CSI) between the plurality of wireless transceiver stations of the first
wireless network and the one or the plurality of antennas of the second wireless
network.
20. The method as in claim 16 wherein the first wireless network is a user
multiple antenna system (MU-MAS) that uses precoding to create the one or the
plurality of points of zero RF energy and the precoding is computed based on channel
state information (CSI) between the plurality of ss transceiver stations of the first
wireless network and the one or the plurality of antennas of the second wireless
network, and wherein the CSI is estimated using in-band or out-of-band training signals
sent over a plurality of wireless links between the plurality of wireless transceiver
stations and the one or the plurality of antennas.
21. The system of claim 1 as herein described with reference to the drawings.
22. The system of claim 6 as herein described with reference to the drawings.
23. A method for icating over a network of claim 11 as herein described
with reference to the drawings.
24. A method for communicating over a network of claim 16 as herein described
with reference to the drawings.
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Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US62/380,126 | 2016-08-26 | ||
US15/682,076 | 2017-08-21 |
Publications (1)
Publication Number | Publication Date |
---|---|
NZ791129A true NZ791129A (en) | 2022-08-26 |
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