HK40003124A - Systems and methods for mitigating interference within actively used spectrum - Google Patents

Description

System and method for mitigating interference in an active spectrum

Cross reference to related patent applications

This patent application claims the benefit of U.S. provisional patent application No. 62/380,126, filed on 8/26/2016.

This patent application is also a partial continuation of U.S. application Ser. No. 14/672,014, filed on day 2015 3-27, entitled "Systems and Methods for Current Spectrum use with Actively Used Spectrum", claiming the benefit and priority of U.S. provisional patent application No. 61/980,479, filed on day 2014 4-16, entitled "Systems and Methods for Current Spectrum use with Actively Used Spectrum", which is hereby incorporated by reference in its entirety.

The present patent application may be related to the following co-pending U.S. patent applications and U.S. provisional applications:

U.S. application Ser. No. 14/611,565 entitled "Systems and Methods for Mapping Virtual Radio Instances of science in Distributed Antenna Systems";

U.S. application Ser. No. 14/086,700 entitled "Systems and Methods for expanding Inter-cell Multiplexing gain in Wireless cell System" Via Distributed Input Distributed output technology ";

U.S. application Ser. No. 13/844,355 entitled "Systems and Methods for Radio Frequency Call amplification connecting channel Recirculation in Distributed Input Distributed Output Wireless communications";

U.S. application Ser. No. 13/797,984 entitled "Systems and Methods for expanding Inter-cell Multiplexing gain in Wireless cell System" Via Distributed Input Distributed output technology ";

U.S. application Ser. No. 13/797,971 entitled "Systems and Methods for expanding Inter-cell Multiplexing gain in Wireless cell System" Via Distributed Input Distributed output technology ";

U.S. application Ser. No. 13/797,950 entitled "Systems and Methods for expanding Inter-cell Multiplexing gain in Wireless cell System" Via Distributed Input Distributed output technology ";

U.S. application Ser. No. 13/475,598 entitled "Systems and Methods to enhance spatial diversity input distributed-output wireless Systems";

U.S. application Ser. No. 13/233,006 entitled "System and Methods for plated evaluation and obsollence of Multi user Spectrum";

U.S. application Ser. No. 13/232,996 entitled "Systems and Methods to extract Areas of science in Wireless Systems";

U.S. application Ser. No. 12/802,989 entitled "System And Method For Managing Handoff Of A Client BetWeenDifference Distributed-Input-Distributed-output (DIDO) Networks Based on detected Velocity Of The Client";

U.S. application Ser. No. 12/802,988 entitled "Interference Management, Handoff, Power Control And LinkAdaptation In Distributed-Input Distributed-output (DIDO) communication systems";

U.S. application Ser. No. 12/802,975 entitled "System And Method For Link adaptation In DIDO multicarrier systems";

U.S. application Ser. No. 12/802,974 entitled "System And Method For Managing Inter-Cluster Handoff of clients Which trap Multiple DIDO Clusters";

U.S. application Ser. No. 12/802,958 entitled "System And Method For Power Control And Antenna group In inputted-Distributed-output (DIDO) Network";

U.S. patent No. 9,386,465, entitled "System and Method For Distributed Antenna Wireless communications," entitled "United states patent No. 9,386,465, 7,5, 2016;

U.S. Pat. No. 9,369,888, entitled "Systems And Methods To Coordinate transactions In distributed Wireless Systems Via User Clusting", entitled "Systems And Methods", issued on 2016, 6, 14;

U.S. Pat. No. 9,312,929, entitled "System and Methods to Compensate for Doppler Effect in Distributed-Input Distributed Output Systems", entitled "System and Methods", entitled "United states patent No. 9,312,929, 12, 4 months 2016;

U.S. patent No. 8,989,155, 24/3/2015, entitled "Systems and Methods for Wireless Backhaul in Distributed-input Distributed-Output Wireless Systems";

U.S. Pat. No. 8,971,380, 3/2015, entitled "System and Method for Adjusting DIDO Interference based On Signal Strength Measurements";

U.S. patent No. 8,654,815, entitled "System and Method for Distributed Input Distributed output wireless Communications," granted 2 months and 18 days 2014;

U.S. patent No. 8,571,086, entitled "System and Method for DIDO Precoding Interpolation in multicarrier Systems," entitled "year 2013, month 10, day 29;

U.S. patent No. 8,542,763, entitled "Systems and Methods To Coordinate transactions In distributed wireless Systems Via User Clustering," issued on 24/9.2013;

U.S. patent No. 8,428,162 entitled "System and Method for Distributed Input Distributed output wireless Communications," granted on 23/4/2013;

U.S. Pat. No. 8,170,081 issued On 5/1/2012 of the title "System And Method For adding DIDO Interference based On Signal Strength Measurements";

U.S. patent No. 8,160,121, entitled "System and Method for Distributed Input-Distributed output wireless Communications," granted on month 4, 2012, 17;

U.S. Pat. No. 7,885,354, 8/2/2011, entitled "System and Method For Enhancing Near Vertical incorporation Skywave (" NVIS ") Communication Using Space-Time Coding".

U.S. Pat. No. 7,711,030, 5/4/2010, entitled "System and Method For Spatial-Multiplexed Tropsophilic Scattercommunications";

U.S. patent No. 7,636,381 entitled "System and Method for Distributed Input Distributed output wireless Communication," granted on 12 months and 22 days 2009;

U.S. patent No. 7,633,994 entitled "System and Method for Distributed Input Distributed output wireless Communication," granted 12 months and 15 days 2009;

U.S. patent No. 7,599,420 entitled "System and Method for Distributed Input Distributed output wireless Communication," granted on 10/6 th of 2009;

U.S. patent No. 7,418,053 entitled System and Method for Distributed Input Distributed output wireless Communication, granted on 26.2008.

Technical Field

Background

Frequency division duplex ("FDD") and time division duplex ("TDD") modes are often used in wireless communication systems. For example, the LTE standard supports both FDD and TDD modes, as another example, 802.11 release (e.g., Wi-Fi) supports TDD mode of operation.

In the case of LTE, various numbered frequency bands are defined within the so-called "evolved UMTS terrestrial radio access" (E-UTRA) air interface. Each E-UTRA band not only specifies a particular band number, but also defines what bandwidth is FDD or TDD, and supported within that band (see, e.g., the list of E-UTRA bands and their specifications in http:// en. For example, band 7 is an FDD band defined as an FDD band using a frequency range of 2,500MHz to 2,570MHz for the uplink ("UL"), a frequency range of 2,620 to 2,690 for the downlink ("DL"), which supports 5, 10, 15, 20 and MHz signal bandwidths within the respective UL and DL bands.

In many cases, the E-UTRA bands overlap. For example, the different frequency bands may be shared spectrum that has been allocated in different markets or regions. For example, band 41 is a TDD band using a frequency range of 2,496MHz to 2,690MHz for both UL and DL, overlapping with both the UL and DL ranges of FDD band 7 (see, e.g., fig. 16a and 16 b). Currently, band 41 is used by Sprint in the united states, while band 7 is used by Rogers wires in border countries in canada. Thus, in the united states, 2,500MHz to 2,570MHz is the TDD spectrum, while in canada the same frequency range is the UL for FDD spectrum.

Generally, a mobile device will scan through the frequency band upon attaching to a wireless network in order to search for transmissions from one or more base stations, and typically during an attachment procedure, the base stations will transmit characteristics of the network, such as the bandwidth used by the network, and the details of the protocol in use. For example, if an LTE device scans 2,620MHz to 2,690MHz in the united states, the LTE device may receive LTE DL frames transmitted by enodebs that identify the spectrum as band 41, and if the LTE device supports band 41 and TDD, the LTE device may attempt to connect to the eNodeB in TDD mode in that band. Similarly, if an LTE device scans 2,620MHz to 2,690MHz in canada, the LTE device may receive LTE DL frames transmitted by enodebs that identify the spectrum as band 7, and if the LTE device supports band 7 and FDD, the LTE device may attempt to connect to the eNodeB in FDD mode in band 7.

LTE networks deployed most globally use FDD mode (e.g., Verizon, AT & T), but TDD mode is increasingly being used in both markets with extensive FDD coverage, such as the united states (Sprint is deploying TDD), and in markets that have not yet had extensive LTE coverage, such as China (China Mobile is deploying TDD). In many cases, a single operator deploys both FDD and TDD at different frequencies (e.g., in the united states, Sprint operates both FDD LTE and TDD LTE at different frequencies), and LTE devices may be provisioned that may operate in both modes depending on which frequency band is used.

Note that the E-UTRA list of LTE bands is never the final list, but evolves as new spectrum is allocated to mobile carriers and devices using the spectrum are designated. The new band is specified in both a spectrum in which the current band does not overlap its frequency and a spectrum in a band that overlaps a frequency of the previous band configuration. For example, band 44, which is a TDD band spanning 703MHz to 803MHz, is newly added as an E-UTRA band several years after the older 700MHz FDD bands (such as bands 12, 13, 14 and 17) are assigned.

As can be seen in fig. 6, previously, most of the action data was speech data (e.g., Q12007), which was highly symmetric. However, with the introduction of the 2007 iPhone, followed by the introduction of iPad in 2009 after the rapid adoption of Android, the non-voice action data rapidly surpassed the growth of voice data, and by 2013, voice data was only a small part of the action data traffic. It is expected that non-voice data will continue to grow exponentially while voice data will shrink increasingly.

As can be seen in FIG. 7, non-voice action data is mostly media such as streaming video, audio, and Web browsing (most of which includes streaming video). While some streaming media is UL data (e.g., during a video conference), most is DL data, with the result that there is highly asymmetric DL versus UL data usage. For example, the article "Asymmetry and approaching (US) spectrum crisis" in the final Times 2013, 5, 28, states that the … industry estimates that the ratio of downlink data traffic to data traffic in the uplink ranges from about an eight to one (8:1) ratio to significantly greater ranges. The article then indicates that most FDD deployments in the united states are very inefficient at dealing with such asymmetries, since FDD mode allocates the same amount of spectrum to each DL and UL. As another example, based on the 2009 effective network measurements, Qualcomm estimated DL/UL traffic asymmetry for one of the us operators up to 9:1(cfr., Qualcomm, "1000 x: more specific-specific for small cells", 11 months 2013, http:// www.qualcomm.com/media/documents/files/1000 x-more-specific-for-small-ls-pdf). Thus, even in cases where the FDD DL spectrum is heavily utilized (possibly to the extent of overload), a large portion of the UL spectrum may be unused.

The finacial Times article states that TDD is more suitable for such asymmetries because it can be constructed to allocate more time slots to DL data than to UL data. For example, in the case of 20MHz allocation to FDD (at 10+10MHz), DL data traffic is limited to a maximum of 10MHz for full time use (even when UL data needs to be much less than its 10MHz allocated), whereas when TDD is allocated 20MHz, DL data traffic can use all 20MHz most of the time, and UL data is allocated 20MHz only for a short period of time, thus more matching the characteristics of data usage today. The article acknowledges that unfortunately most existing U.S. mobile spectrum has been devoted to FDD mode, but the FCC is motivated to encourage the use of TDD as it allocates new spectrum.

While TDD necessarily may allow for more efficient use of new spectrum configurations in view of the increasingly asymmetric nature of mobile data, existing FDD network deployments unfortunately cannot change the mode of operation to TDD because most users' devices of such LTE FDD networks only support FDD mode and their devices are no longer capable of networking if the network is switched to TDD mode. Thus, as LTE data usage becomes increasingly asymmetric, existing LTE FDD networks will see increased DL congestion, while the UL spectrum will become increasingly under-utilized (the lower estimate of the final Times article, 5/28/2013, is a DL: UL ratio of 8:1, which means that if the DL channel is fully utilized, the UL channel only uses 1/8 (equivalent to 1.25Mhz in 10 Mhz)). This is extremely wasteful and inefficient, especially in view of the limited physical presence of the actual spectrum of motion (e.g., frequencies that can penetrate walls and propagate well off-line-of-sight, such as 450 to 2600MHz) and the exponential growth of (increasingly asymmetric) motion data (e.g., Cisco 2/2013 VNI predicts an increase of 2018 motion data up to 61% CAGR, which is mostly video streaming and other highly asymmetric data).

Disclosure of Invention

Drawings

A preferred understanding of the present invention can be obtained from the following detailed description in conjunction with the following drawings, in which:

fig. 1 shows the general framework of a DIDO Radio Access Network (DRAN).

Fig. 2 shows a protocol stack of a Virtual Radio Instance (VRI) 201 in accordance with the OSI model and the LTE standard.

Fig. 3 shows neighboring DRANs for extending coverage in a DIDO wireless network.

Fig. 4 illustrates a handoff between a drap and a neighboring wireless network.

Fig. 5 illustrates a handoff between a drap and an LTE cellular network.

FIG. 6 is a background art showing voice and non-voice data utilization of the action spectrum from 2007 to 2013.

Fig. 7 is a background art showing the traffic proportion of the action data differentiated by the application type in 2012.

Fig. 8 is a background comparison of FDD LTE and TDD LTE modes of operation.

Fig. 9 shows a new TDD network that uses both UL spectrum and existing FDD network.

Fig. 10 is a background diagram of a TDD LTE duplex configuration.

Fig. 11 shows a new TDD network that uses the DL spectrum simultaneously with an existing FDD network.

Fig. 12 shows two new TDD networks using both UL and DL spectrum with existing FDD networks.

Fig. 13 shows a new FDD network using both UL and DL spectrum and an existing FDD network.

Fig. 14 shows the DRAN for the synthetic null pCell at the location of the base station antenna.

Fig. 15a, 15b, 15c, and 15d illustrate various propagation scenarios 1520-1522 and 1524-1525 between base station antennas 1510 and 1530.

Fig. 16a and 16b are background diagrams of frequency bands from 2500MHz to 2690MHz allocated to FDD and TDD or only TDD in different regions.

Detailed Description

One solution to overcome many of the above background limitations is to have several user devices simultaneously operate in TDD mode in the same spectrum as the currently used UL or DL FDD spectrum, so that TDD spectrum usage is coordinated so as not to conflict with current FDD spectrum usage. Specifically, in FDD UL channels, there is more and more unused spectrum, and TDD devices can use this spectrum without affecting the traffic of existing FDD networks. This solution also enables TDD usage in the highly propagation efficient UHF spectrum, which is almost entirely allocated to FDD in many areas of the world, thereby relegating TDD to the extremely low propagation efficient microwave band.

In another embodiment, several user devices are operated in FDD mode simultaneously in the same spectrum as the currently used UL or DL FDD spectrum, so that the UL and DL channels are reversed and the spectrum usage of each network is coordinated so as not to conflict with the spectrum usage of the other networks. This allows the DL channels of each network to utilize unused spectrum in the UL channels of other networks given that the UL channels of each network are increasingly underutilized relative to the DL channels.

Moreover, in either embodiment, spectral efficiency may be greatly increased by implementing one or both networks using distributed input distributed output ("DIDO") techniques as described in the following patents, patent applications, and provisional applications, all of which are assigned to the assignee of the present patent and incorporated by reference. These patents, applications, and provisional applications are sometimes collectively referred to herein as "related patents and applications".

U.S. application Ser. No. 14/672,014 entitled "Systems And Methods For Current Spectrum use with Actively Used Spectrum".

U.S. provisional patent application No. 61/980,479, filed on 16/4/2014, entitled "Systems And Methods For Current Spectrum use with Actively Used Spectrum".

U.S. application Ser. No. 14/611,565 entitled "Systems and methods for Mapping Virtual Radio Instances of the coherent physical Areas of science in Distributed Antenna Systems".

U.S. application Ser. No. 14/086,700 entitled "Systems and Methods for expanding Inter-cell Multiplexing gain in Wireless cell System" Systems Via Distributed Input Distributed output technology ".

U.S. application Ser. No. 13/844,355 entitled "Systems and Methods for Radio Frequency Calibration expanding channel Recirculation in Distributed Input Distributed Output Wireless communications".

U.S. application Ser. No. 13/797,984 entitled "Systems and Methods for expanding Inter-cell Multiplexing gain in Wireless cell System" Systems Via Distributed Input Distributed output technology ".

U.S. application Ser. No. 13/797,971 entitled "Systems and Methods for expanding Inter-cell Multiplexing gain in Wireless cell System" Systems Via Distributed Input Distributed output technology ".

U.S. application Ser. No. 13/797,950 entitled "Systems and Methods for expanding Inter-cell Multiplexing gain in Wireless cell System" Systems Via Distributed Input Distributed output technology ".

U.S. application Ser. No. 13/475,598 entitled "Systems and Methods to enhance spatial diversity input distributed-output wireless Systems".

U.S. application Ser. No. 13/233,006 entitled "System and Methods for plated evaluation and obsole science of Multi user Spectrum".

U.S. application Ser. No. 13/232,996 entitled "Systems and Methods to extract Areas of science in Wireless Systems".

U.S. application Ser. No. 12/802,989 entitled "System And Method For Managing Handoff Of A Client BetWeenDifference Distributed-Input-Distributed-output (DIDO) Networks Based on detected Velocity Of The Client".

U.S. application Ser. No. 12/802,988 entitled "Interference Management, Handoff, Power Control And LinkAdaptation In Distributed-Input Distributed-output (DIDO) communication systems".

U.S. application Ser. No. 12/802,975 entitled "System And Method For Link adaptation In DIDO multicarrier systems".

U.S. application Ser. No. 12/802,974 entitled "System And Method For Managing Inter-Cluster Handoff of clients Which trap Multiple DIDO Clusters".

U.S. application Ser. No. 12/802,958 entitled System And Method For Power Control And Antenna group In acquired-Input-Distributed-output (DIDO) Network.

U.S. patent No. 9,386,465, entitled "System and Method For Distributed Antenna Wireless communications," filed on 2016, 7, 5.

U.S. Pat. No. 9,369,888, entitled "Systems And Methods To Coordinate transactions In distributed Wireless Systems Via User Clusting", entitled "Systems And Methods", issued on 2016, 6, 14.

U.S. patent No. 9,312,929, entitled "System and Methods to Compensate for Doppler Effect in Distributed-Input Distributed Output Systems", entitled "System and Methods", issued on 12/4/2016.

U.S. patent No. 8,989,155, 24/3/2015, entitled "Systems and Methods for Wireless Back in Distributed-input Distributed-Output Wireless Systems".

U.S. Pat. No. 8,971,380, 3/2015, entitled "System and Method for Adjusting DIDO Interference based On Signal Strength Measurements".

U.S. patent No. 8,654,815, entitled "System and Method for Distributed Input Distributed output wireless Communications," issued on 2 months and 18 days 2014.

U.S. Pat. No. 8,571,086, entitled "System and Method for DIDO Precoding Interpolation in multicarrier Systems", entitled "year 2013, month 10, day 29.

U.S. patent No. 8,542,763, entitled Systems and Methods To Coordinate Transmissions In distributed wireless Systems Via User Clustering, entitled "Systems and Methods," issued on 24.9.2013.

U.S. patent No. 8,428,162 entitled System and Method for Distributed Input Distributed output wireless Communications, granted on 23.4.2013.

U.S. Pat. No. 8,170,081, 5/1/2012 entitled "System And Method For adding DIDO Interference based On Signal Strength Measurements".

U.S. patent No. 8,160,121, entitled "System and Method for Distributed Input-Distributed output wireless Communications," granted on month 4, 2012, 17;

U.S. Pat. No. 7,885,354, 8/2/2011, entitled "System and Method For Enhancing Near Vertical incorporation Skywave (" NVIS ") Communication Using Space-Time Coding".

U.S. Pat. No. 7,711,030, 5/4/2010, entitled "System and Method For Spatial-Multiplexed Tropsophilic Scattercommunications";

U.S. patent No. 7,636,381 entitled "System and Method for Distributed Input Distributed output wireless Communication," granted on 12 months and 22 days 2009;

U.S. patent No. 7,633,994 entitled "System and Method for Distributed Input Distributed output wireless Communication," granted 12 months and 15 days 2009;

U.S. patent No. 7,599,420 entitled "System and Method for Distributed Input Distributed output wireless Communication," granted on 10/6 th of 2009;

U.S. patent No. 7,418,053 entitled System and Method for Distributed Input Distributed output wireless Communication, granted on 26.2008.

Systems and methods for simultaneous spectrum usage within an active (used) spectrum are disclosed. Some embodiments utilize distributed input distributed output and MU-MAS techniques previously disclosed by the present assignee. The disclosure in sections 1 and 2 below corresponds to that disclosed in U.S. provisional application Ser. No. 61/937,273, filed on 2/7/2014, entitled "Systems and Methods for Mapping virtual radio resources of science in Distributed antenna Wireless Systems" and relates to the present invention. The disclosure in sections 3 and 4 below corresponds to that of U.S. provisional application serial No. 61/980,479, filed on day 4/16 2014, entitled "System and Methods for Current Spectrum use with Actively Used Spectrum" and also relates to the present invention.

1. System and method for mapping VRIs into coherent regions

One embodiment of the present invention discloses a system and method for transferring multiple simultaneous non-interfering data streams within the same frequency band between a network and multiple coherent regions in a wireless link via Virtual Radio Instances (VRIs). In one embodiment, the system is a multiuser multiple antenna system (MU-MAS) as depicted in FIG. 1. The color coding unit in fig. 1 shows a one-to-one mapping between the data source 101, VRI 106 and the coherent region 103 as described below.

1.1 overview of the System architecture

In fig. 1, the material source 101 is a data file or stream carrying web content, or a file in a local or remote server, such as a text, an image, a sound, a video, or a combination thereof. One or more data files or streams are sent or received between the network 102 and each coherent segment 103 in the wireless link 110. In one embodiment, the network is the internet or any wireline or wireless local area network.

A coherence region (area of coherence) is a volume in space in which the waveforms from different antennas of a MU-MAS add coherently in such a way that only the data output 112 of one VRI is received within the coherence region without any interference from other data outputs from other VRIs sent simultaneously on the same wireless link. In this patent application, we use the phrase "Coherence region" to describe a phrase such as U.S. application Ser. No. 13/232,996 of our previous patent application entitled "Systems and methods explicit Areas of science in Wireless Systems]The coherent volume or private cell described in (e.g., "pCels^TM"103). In one embodiment, the coherence zone corresponds to the location of a User Equipment (UE)111 or a subscriber of the wireless network such that each subscriber is associated with one or more data sources 101. The size and shape of the coherent regions may vary depending on the propagation conditions and the type of MU-MAS precoding technique used to generate such coherent regions. In one embodiment of the present invention, while delivering content to users with good link reliability, the MU-MAS precoder dynamically adjusts the size and shape of the coherent region to adapt to changing propagation conditions.

A data source 101 is first sent to a DIDO Radio Access Network (DRAN)104 via a network 102. The DRAN then converts the data files or streams into a data format that can be received by the UE and sends such data files or streams to multiple coherence regions simultaneously, so that each UE receives its own data file or stream without interference from other data files or streams sent to other UEs. The DRAN consists of a gateway 105 that interfaces between the network and the VRI 106. The VRI converts the packets routed by the gateway into a data stream 112 that is either raw data or in a packet or frame structure, such data stream being fed to the MU-MAS baseband unit. In one embodiment, the VRI includes an Open Systems Interconnection (OSI) protocol stack consisting of several layers: application layer, presentation layer, talk layer, transport layer, network layer, data link layer, and physical layer, as depicted in fig. 2 a. In another embodiment, the VRI includes only a subset of OSI layers.

In another embodiment, the VRIs are defined by different wireless standards. For example, but not by way of limitation, the first VRI consists of a protocol stack from the GSM standard, the second VRI from the 3G standard, the third VRI from the HSPA + standard, the fourth VRI from the LTE standard, and the fifth VRI from the LTE-a standard and the sixth VRI from the Wi-Fi standard. In an exemplary embodiment, the VRI includes a control plane or user plane protocol stack defined by the LTE standard. The user plane protocol stack is shown in figure 2 b. Each UE 202 communicates with its own VRI 204 through PHY, MAC, RLC, and PDCP layers, with the gateway 203 being through the IP layer and the network 205 being through the application layer. For the control plane protocol stack, the UE also communicates directly with the mobility management physical (MME) through the NAS (as defined in the LTE standard stack) layer.

The Virtual Connection Manager (VCM)107 is responsible for assigning PHY layer identification (e.g., cell specific radio network temporary identifier, RNTI), VRI, and authentication and mobility of the UE for the UE. The data stream 112 at the output of the VRI is fed to a Virtual Radio Manager (VRM) 108. The VRM includes a scheduler unit (which schedules DL (downlink) and UL (uplink) packets for different UEs), a baseband unit (e.g., including FEC encoder/decoder, modulator/demodulator, resource grid builder), and a MU-MAS baseband processor (including precoding logic for performing precoding operations). In one embodiment, the data stream 112 is the I/Q samples at the output of the PHY layer in FIG. 2b, such samples are processed by the MU-MAS baseband processor. In a different embodiment, the data stream 112 is a MAC, RLC or PDCP packet sent to a scheduler unit that forwards such packets to the baseband unit. The baseband unit converts the packets into I/Q that are fed to the MU-MAS baseband processor.

The MU-MAS baseband processor is the core of the VRM, which converts M I/Q samples from M VRIs into N data streams 113 sent to N Access Points (APs) 109. In one embodiment, the data stream 113 is I/Q samples of N waveforms transmitted from the AP 109 over the wireless link 110. In this embodiment, the AP consists of an ADC/DAC, an RF chain, and an antenna. In a different embodiment, the data stream 113 is bits of information and MU-MAS precoding information that are combined at the AP to produce N waveforms that are sent over the wireless link 110. In this embodiment, each AP is equipped with a CPU, DSP, or SoC to perform additional baseband processing prior to the ADC/DAC unit.

1.2 support mobility and Handover

The systems and methods described thus far work as long as the UE is within reach of the AP. When the UE travels away from the AP coverage area, the link may terminate and the DRAN 301 cannot generate a coherent region. To extend the coverage area, the system may evolve gradually by adding new APs. However, there may not be enough processing power in the VRM to support the new AP, or there may be practical installation issues connecting the new AP to the same VRM. In these cases, it is necessary to add neighboring DRANs 302 and 303 to support the new AP, as depicted in fig. 3.

In one embodiment, a given UE is located in an area of coverage served by a first drap 301 and a neighboring drap 302. In this embodiment, the neighboring DRAN 302 only performs MU-MAS baseband processing for that UE, along with MU-MAS processing from the first DRAN 301. The neighboring DRAN 302 does not handle any VRI for the given UE, as the VRI of the UE is already running within the first DRAN 301. To achieve joint precoding between a first drap and an adjacent drap, baseband information is exchanged between the VRM in the first drap 301 and the VRM in the adjacent drap 302 via cloud VRM 304 and link 305. Link 305 is any wired (e.g., fiber, DSL, cable) or wireless (e.g., line-of-sight link) link that can support suitable on-line quality (e.g., sufficiently low latency and suitable data rate) to avoid performance degradation of MU-MAS precoding.

In a different embodiment, a given UE moves out of the coverage area of a first drap 301 and into the coverage area of a neighboring drap 303. In this embodiment, the VRI associated with the UE is transferred (teleported) from the first DRAN 301 "to the neighboring DRAN 303. The VRI is transferred or "VRI transfer" means that VRI state information is transferred from the drap 301 to the drap 303 and the VRI stops executing within the drap 301 and starts executing within the drap 303. Ideally, from the perspective of the UE served by the transmitting VRI, VRI transmission occurs fast enough so that it does not experience any gaps in its data stream from the VRI. In one embodiment, if there is a delay after the VRI is transmitted before it is fully executed, the UE served by the VRI is put into a state in which it will not terminate its connection or otherwise enter an undesirable state until the VRI is initiated at the neighboring DRAN303 before the VRI transmission begins, and the UE is again served by executing the VRI. "VRI transfer" is accomplished by a cloud VCM 306 that connects the VCM in the first DRAN 301 to the VCM in the adjacent DRAN 303. The wire line or wireless links 307 between VCMs do not have the same limiting constraints as the links 305 between VRMs, as they only carry data and do not affect the performance of MU-MAS precoding. In the same embodiment of the present invention, an additional link 305 is employed between the first DRAN 301 and the neighboring DRAN303 to connect their VRMs, which may support appropriate inline quality (e.g., sufficiently low latency and appropriate data rate) to avoid performance degradation of MU-MAS precoding. In one embodiment of the invention, the gateways for the first and adjacent DRANs are connected to a cloud gateway 308 that manages all network address (or IP address) translations across the DRANs.

In one embodiment of the invention, VRI transmissions occur between the drap network disclosed in this patent application and any neighboring wireless network 401, as depicted in fig. 4. For example, and without limitation, wireless network 401 is any well-known cellular network (e.g., GSM, 3G, HSPA +, LTE-A) or wireless local area network (WLAN, e.g., Wi-Fi). When VRI is transmitted from the drap to the neighboring wireless network 401, the UE hands off between the two networks and its wireless connection can continue.

In one embodiment, the neighboring wireless network 401 is an LTE network shown in fig. 5. In this embodiment, the cloud VCM 502 is connected to an LTE mobility management physical (MME) 501. All information regarding the identification, authentication and mobility of each UE handover between LTE and drap networks is exchanged between the MME 501 and the cloud VCM 502. In the same embodiment, the MME is connected to one or more enodebs 503, such enodebs being connected to the UE 504 via a wireless cellular network. The enodebs are connected to a network 507 via a serving gateway (S-GW)505 and a packet data network gateway (P-GW) 506.

2. System and method for DL and UL MU-MAS processing

A general Downlink (DL) radio link is composed of a broadcast physical channel carrying information for the entire cell and a dedicated physical channel with information and data for a given UE. For example, the LTE standard defines broadcast channels such as P-SS and S-SS (for synchronization at the UE), MIB and PDCCH, and channels such as PDSCH for carrying data to a given UE. In one embodiment of the invention, all LTE broadcast channels (e.g., P-SS, S-SS, MIC, PDCCH) are precoded so that each UE receives its own dedicated information. In a different embodiment, portions of the broadcast channel are precoded and portions are not precoded. For example, but not by way of limitation, the PDCCH contains broadcast information as well as information specific to one UE, such as DCI 1A and DCI 0 for directing the UE to Resource Blocks (RBs) used on DL and Uplink (UL) channels. In one embodiment, the broadcast portion of the PDCCH is not precoded, while the portion containing DCI 1A and DCI 0 is precoded in such a way that each UE obtains its own dedicated information about the RBs carrying the data.

In another embodiment of the invention, precoding is applied to all data channels or only part of the data channels, such as PDSCH in LTE systems. By applying precoding across the entire data channel, one embodiment of the MU-MAS disclosed in this patent application allocates the full bandwidth to each UE, and multiple data streams for multiple UEs are separated via spatial processing. However, in the general scenario, most, if not all, UEs do not need the full bandwidth (e.g., 70Mbps per UE, peak data rate for TDD configuration #2 in a 20MHz spectrum). Then, one embodiment of the MU-MAS in this patent application subdivides the DL RBs in multiple blocks, as in OFDMA systems, and assigns each block to a subset of UEs. All UEs within the same block are separated via MU-MAS precoding. In another embodiment, the MU-MAS allocates different DL subframes to different subsets of UEs, dividing the DL as in TDMA systems. In yet another embodiment, the MU-MAS subdivides the DL RBs in multiple blocks among subsets of UEs as in an OFDMA system, and also allocates different DL subframes to different subsets of UEs as in a TDMA system, thus partitioning the traffic with both OFDMA and TDMA. For example, if there are 10 APs for TDD configuration #2 at 20MHz, there is a total DL capacity of 70Mbps by 10 to 700 Mbps. If there are 10 UEs, each UE can receive 70Mbps simultaneously. If there are 200 UEs and the total traffic is to be divided equally, 200 UEs are divided into 20 groups of 10 UEs using OFDMA, TDMA or a combination thereof, whereby each UE will receive 700Mbps/200 — 3.5 Mbps. As another example, if 10 UEs need 20Mbps, and the other UEs share the remaining traffic on average, 20Mbps 10 ═ 200Mbps in 700Mbps will be used for 10 UEs, leaving 700Mbps-200Mbps 500Mbps allocated among the remaining 200-10 ═ 190 UEs. Thus, each of the remaining 190 UEs will receive 500Mbps/190 ═ 2.63 Mbps. Thus, many more UEs than APs may be supported in a MU-MAS system, and the total traffic flow for all APs may be distributed among many UEs.

In the UL channel, the LTE standard defines well-known multiple access techniques such as TDMA or SC-FDMA. In one embodiment of the present invention, MU-MAS precoding is implemented on the DL in a manner that assigns UL grants to different UEs to implement TDMA and SC-FDMA multiple access techniques. Thus, the total UL traffic may be distributed among UEs that are much more than there are APs.

When there are more UEs than APs and total traffic is distributed among such UEs, as described above, in one embodiment, the MU-MAS system supports VRIs for each UE, and the VRMs control such VRIs so that they utilize RB and resource grants consistent with the chosen OFDMA, TDMA, or SC-FDMA system used to subdivide the total traffic. In another embodiment, one or more individual VRIs may support multiple UEs and manage the scheduling of traffic among these UEs via OFDMA, TDMA, or SC-FDMA techniques.

In another embodiment, the scheduling of traffic is load balancing based on user requirements using any of a number of background techniques, depending on the policy and performance goals of the system. In another embodiment, the scheduling is based on quality of service (QoS) requirements for a particular UE (e.g., pay for a particular tier of service to guarantee certain traffic levels) or for a particular data type (e.g., video for television services).

In a different embodiment, UL receive antenna selection is applied to improve link quality. In this approach, the UL channel quality is estimated at the VRM based on signaling information sent by the UE (e.g., SRS, DMRS), and the VRM decides the best receive antenna for different UEs on the UL. The VRM then assigns one receive antenna to each UE to improve its link quality. In a different embodiment, receive antenna selection is utilized to reduce cross-interference between frequency bands due to the SC-FDMA scheme. One significant advantage of this approach is that the UE will only transmit on the UL to the AP closest to its location. In this scenario, the UE may significantly reduce its transmission power for reaching the closest AP, thereby improving battery life. In the same embodiment, different power scaling factors are utilized for the UL data channel and for the UL signaling channel. In one exemplary 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 from many APs (exploiting UL/DL channel reciprocity in TDD systems), while still limiting the power required for UL data transmission. In the same embodiment, the power levels of the UL signaling channel and UL data channel are adjusted by the VRM via DL signaling based on transmission power control methods, which equalize the relative power to/from different UEs.

In a different embodiment, Maximum Ratio Combining (MRC) is applied at the UL receiver to improve the signal quality from each UE to multiple APs. In a different embodiment, either near Zero (ZF) or Minimum Mean Square Error (MMSE) or Successive Interference Cancellation (SIC) or other non-linear techniques or the same precoding technique as used for DL precoding are applied to the UL in order to distinguish the data streams received from the coherent regions of different UEs. In the same embodiment, receive spatial processing is applied to either the UL data channel (e.g., PUSCH) or the UL control channel (e.g., PUCCH) or both.

3. System and method for simultaneous spectrum use within incumbent spectrum

As described in detail above in the background section, and shown in FIGS. 6 and 7, action data usage has changed significantly from mostly symmetric speech data to highly asymmetric non-speech data, particularly media such as video streams. Most mobile LTE deployments worldwide are FDD LTE, whose physical layer structure is shown in the top half of fig. 8, which has fixed, symmetric uplink ("UL") and downlink ("DL") channels, and thus, as the DL channel has become increasingly congested with the exponential growth of DL data relative to UL data, the UL data channel has become increasingly underutilized.

The LTE standard also supports TDD LTE (also referred to as "TD-LTE"), whose physical layer structure is shown in the lower half of fig. 8, and the mobile communication operator may choose to either be symmetric (as shown in this illustration) or asymmetric (e.g., where more subframes are allocated to either the DL channel or the UL channel), and thus, as the DL channel has become increasingly congested with the exponential growth of DL data relative to UL data, the mobile communication operator may choose to allocate more subframes to the DL than the UL. For example, in one configuration, TD-LTE supports an 8:1DL: UL ratio, with subframes allocated for DL 8 times more than for UL.

The structure and details of TD-LTE and FDD LTE are almost identical, except that TD-LTE is bi-directional in one channel. In both modes, each frame has a duration of 10ms 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 virtually identical. In both cases, time and frequency references for user equipment ("UE") devices (e.g., mobile phones, tablets) are provided by the eNodeB (LTE base station protocol stack) to all devices (via DL channel with FDD LTE and during DL subframe with TD-LTE).

Notably, in the case of both FDD and TDD LTE, the network may be constructed such that the UE may transmit UL data received via DL transmissions only if authorization is given by the eNodeB for transmitting UL data. Thus, the eNodeB not only controls when it transmits DL data, but also when the UE can transmit UL data.

It is also worth noting that in the case of LTE FDD UEs, its receiver is tuned only to its DL channel and none to its UL channel. Thus, an FDD UE is "deaf (deaf)" for anything transmitted by another device in its UL channel.

Also, in the case of all LTE UEs, either FDD or TDD, even where their receivers are tuned to a particular channel, they ignore DL material not intended for them, except for certain control signals intended for all UEs (or for a given UE) that maintain their time reference and connection to the network, or direct when and at what frequency they should receive data. Or, in other words, the DL data uniquely associated with the LTE UE is data that is control information or data for the UE. During other times, a UE is "deaf" for any DL transmission of DL data that is not control information or intended for the UE, whether the channel is in DL for the purpose of being to another UE, not utilized at all, or not belonging to the LTE standard. Thus, the LTE receiver receives only control data intended for all UEs or for a given UE, or data for a given UE, whether FDD or TDD. Other transmissions in the DL channel are ignored.

Fig. 9 shows how FDD and TDD networks can simultaneously utilize the FDD spectrum as a right-of-way utilization. The top two rows of boxes labeled "FDD LTE 910" show one LTE frame interval (10ms) consisting of ten 1ms subframe intervals in both uplink ("UL") and downlink ("DL") channels. This illustration shows the type of asymmetric data transmission, which is increasingly typical in situations where there is far more DL data than UL data (e.g., downlink streaming video). Boxes with a solid outline and filled with diagonal lines (e.g., boxes 912 and 911) represent subframes in which data is being transmitted, and blank boxes with a dashed outline (e.g., box 914) represent "idle" subframes in which no data is being transmitted (i.e., no transmission in the lane during the subframe interval). Block 911 is 2 out of 10 DL subframes, all such DL subframes being full of data. Block 912 shows 1 UL subframe with data. And block 914 is 3 of the 9 idle UL subframes with no data transmission.

The two middle rows of blocks labeled "TDD LTE 920" in fig. 9 show one LTE frame interval (10ms) consisting of 101 ms subframe intervals, including 2 "special" subframe intervals, but unlike the FDD LTE910 row, the two rows of blocks in the TDD LTE 920 row share the same spectrum with each other and with the FDD uplink. This illustration shows asymmetric data transmission for 4 DL subframes and 3 UL subframes in which there is transmission data. Boxes with a solid outline and filled in with dashed lines (e.g., boxes 921, 922, and 923) represent subframes in which data is being transmitted, and blank boxes with a dashed outline (e.g., box 924) represent idle subframes in which no data is being transmitted (i.e., no transmission in the channel during the subframe interval). Block 921 is 1 out of 4 DL subframes, all such DL subframes being full of data. Block 922 shows 1 out of 3 UL subframes, all of which have data. Block 924 is 1 empty idle UL subframe.

The third two rows of blocks labeled "FDD + TDD LTE 930" in fig. 9 show one LTE frame interval (10ms) consisting of 101 ms subframe intervals, including 2 "special" subframe intervals, and show simultaneous operation of FDD LTE910 system and TDD LTE 920 system, where TDD LTE 920 system shares the same spectrum as FDD LTE910 uplink. The two systems do not interfere with each other because (a) the TDD LTE 920 system has an idle interval 924 when it is neither UL nor DL during subframe interval 912 where the FDD LTE910 system has UL data transmissions, and (b) the FDD LTE910 system has an idle UL interval (e.g., idle UL subframe 914) with no UL data transmissions during subframe intervals where the TDD LTE 920 system has transmissions in either the UL or DL directions (e.g., 921, 923, and 922). Thus, two systems coexist using the same spectrum and have no interference between them.

For FDD LTE910 and TDD LTE 920 networks to use the same spectrum simultaneously, their operation must be coordinated by one eNodeB set up to operate both spectrum sharing networks simultaneously, or by coordinating the eNodeB operating the existing tddl te 920 network and a second network controller that can be a second eNodeB or another 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 related patents and applications. In any of these cases, the frames of the FDD LTE910 and TDD LTE 920 systems must be synchronized according to timing and according to subframe resource allocations. For example, in the case of fig. 9, the system controlling the fddl te910 system would need to know which subframes are TDD UL subframes available for UL (e.g., would not collide with TDD DL control signals sent on subframes #0 and #5 for time and frequency synchronization at the UE) and use one of these subframes for its FDD UL subframe 912. If the same system also controls the TDD LTE 920 system, it must also be ensured that the UL from the TDD device is not scheduled during the subframe 912, and if the system does not control the TDD LTE 920 system, any system controlling the TDD LTE 920 system will have to be informed that the UL from the TDD device cannot be scheduled during the subframe 912. Of course, it may be the case that the FDD LTE910 system requires more than one UL subframe during a frame time, and if so, its controller will use any or all of the 3 TDD LTE 920 subframes 922 for its UL subframes, to control or inform appropriately, as described above. Note that it may be the case that in some 10ms frames, all UL subframes are allocated to one of the networks, while other networks do not get UL subframes. LTE devices do not expect to be able to transmit UL data every frame time (e.g., when LTE networks are congested, LTE devices may wait many frame times before they are granted even a portion of a UL subframe), so one embodiment of the invention will work when all available TDD LTE 920UL subframes in a given frame are utilized by one network (i.e., make other networks of the UL subframe "starved"). However, starving one network for too many consecutive frames or allowing too few UL frames overall will result in poor network performance (e.g., low UL traffic, or high round trip delay), and in some cases, if an LTE device attached to the network tries to transmit UL data, it may be determined that the network is unavailable and disconnected. Thus, establishing appropriate scheduling priorities and paradigms to balance UL subframe resources between the fddl te910 and TDD LTE 920 networks may result in optimal overall network performance and user (and/or UE) experience.

One tool that can be used to balance UL subframe resources (and meet network operator priorities), not available in a standalone FDD LTE system, is the TDD LTE duplex configuration shown in fig. 10. Fig. 9 shows TDD LTE 920 system TDD LTE duplex configuration 1, where there are 4 UL subframes, 4 DL subframes, and 2 special subframes during 10 subframes in a 10ms frame. As can be seen in fig. 10, there are several TDD LTE duplex configurations that can be used depending on the needs and data traffic patterns of the mobile communication operator and for balancing UL subframe resources with FDD LTE910 network needs. As the data traffic pattern changes, the TDD LTE duplex configuration may also change over time. Any TDD LTE duplex configuration may be used with embodiments of the present invention. For example, in configuration 1, as shown in fig. 9,1 UL subframe has been allocated to the FDD network and 3 UL subframes have been assigned to the TDD network. If the FDD network suddenly needs more UL traffic, 2 UL subframes may be allocated for FDD at the next frame time, leaving 2 for TDD. Therefore, switching the allocation of UL subframes between FDD and TDD networks can be very dynamic.

Note that if desired, the UL resource allocation between the FDD LTE910 and TDD LTE 920 networks may be even finer than on a subframe basis. It is possible to allocate some resource blocks within a single subframe to FDD devices and other resource blocks to TDD devices. For example, the LTE standard employs SC-FDMA multiple access technique for the UL channel. Thus, UL channels from FDD and TDD devices may be assigned to different resource blocks within the same subframe via an SC-FDMA scheme.

Finally, it is possible to schedule the FDD LTE910 UL during the TDD LTE 920 DL or special subframe. One consideration is that the TDD DL control signals (e.g., P-SS and S-SS broadcast signaling sent on subframes #0 and #5) used by the TDD LTE UE to maintain its connection and maintain timing must be received by the TDD LTE UE with sufficient regularity, otherwise the UE will disconnect.

Fig. 11 shows the same concept described in fig. 9 and above, except that the shared channel is an FDD DL channel, not an FDD UL channel. Fig. 11 uses the same subframe padding and outer frame labeling approach from fig. 9, and as can be seen, the FDD traffic situation is reversed, with all subframes of the FDD LTE 1110 UL channel being used for data, and only 1 of the FDD LTE 1110 DL subframes being used for data, while all other DL subframes are "idle" and no data is transmitted. Similarly, all TDD LTE1120 UL subframes are used for data, and all but one TDD LTE1120 DL subframes are used for data, and in this case, the TDD LTE1120 LTE channel is the same frequency as the FDD LTE 1110 DL channel. The results of the combined fddl te 1110 and TDD LTE1120 networks are shown in the FDD + TDD LTE 1130 channel. As with the example in fig. 9, the two networks may be controlled by a single controller or by coordinating the coordination of multiple controllers, with scheduling between them being ensured by the network operator that the two networks operate as needed with appropriate performance for the user and the user device.

Note that FDD devices attached to FDD LTE 1110 networks rely on DL transmission for control and timing information as well as for data, and such FDD devices must receive sufficient control signals on a regular enough basis to maintain the connection. In one embodiment of the invention, the FDD device uses broadcast signaling sent by the TDD LTE1120 network on DL subframes (e.g., subframes #0 and #5) to achieve time and frequency 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 each FDD device.

As mentioned above, although FDD DL channels are generally far more congested than FDD UL channels, there may be reasons why mobile carriers may wish to share DL channels. For example, some UL channels are limited by spectrum regulatory authorities for UL-only use (e.g., there may be concerns about interfering with the output power of adjacent bands). Furthermore, once a mobile carrier begins to offer TDD devices compatible with its FDD spectrum, the mobile carrier may find that these devices will use the spectrum more efficiently than FDD devices, and thus, may discontinue sales of FDD devices. As older FDD devices are gradually replaced and an increasing proportion of the devices are TDD, operators may wish to allocate more and more of their spectrum to TDD devices, while still maintaining compatibility with the remaining FDD devices in the market.

For this purpose, as fewer FDD devices remain operational, an operator may decide to use both UL and DL bands for TDD operation. This is shown in fig. 12, where FDD LTE 1210 has only one subframe in use for UL and one for DL, and the remainder is idle. There are two TDD LTE networks 1220 and 1230 each using FDD LTE 1210 UL and DL channels, respectively, resulting in three networks sharing two channels, as shown in FDD + TDD LTE 1240. The same flexibility and constraints apply as previously described, and there may be a single controller or multiple controllers for all 3 networks. The two TDD networks may operate independently or by using carrier aggregation techniques.

The operator may also choose to forego TDD altogether and add a second FDD network in the same spectrum as the existing FDD network, but with swapping of uplink and downlink channels. This is shown in figure 13 where the FDD LTE 1310 network is highly asymmetrically utilized with preference to the DL channel, thus only one subframe is used for UL, while the second FDD LTE 1320 network is also highly asymmetrically utilized with preference to the DL channel, but note that in figure 13 the channel allocation for FDD LTE 1320 is transposed, where the FDD downlink channel is shown above the FDD uplink channel, as opposed to the channel order for FDD LTE 1310 or as shown in previous figures. In the case of both FDD LTE 1310 and 1320, the DL channel has one DL subframe idle, which corresponds to one UL frame used by the other network. When the network is combined as shown in FDD + TDDLTE 1230, all subframes in both lanes are DL, except for subframes 1231 and 1232. Thus, 90% of subframes are dedicated to DL, which best matches the mobile traffic pattern since it has evolved compared to symmetric spectrum allocation for UL and DL.

In addition, this structure enables the controller (or controllers) to manage the network to dynamically change the number of UL and DL subframes allocated to each network on a subframe-by-subframe basis, providing very dynamic UL/DL traffic adaptation, even though FDD devices use two networks.

As in the case of the combined FDD/TDD network described earlier, the same constraints applicable to FDD mode are that LTE devices must receive enough control and timing information to maintain connectivity and normal operation, and such LTE devices require enough regularity and the appropriate number of UL frames.

The two FDD networks may operate independently or via carrier aggregation.

In another embodiment, control information transmitted by the DL channel of an existing active network (e.g., in fig. 9, 11, 12, and 13, FDD LTE910, 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 fig. 9, 11, 12, and 13, TDD LTE 920, TDD LTE1120, TDD LTE 1220, and TDD LTE 1230, or FDD LTE 1320) to determine which subframes and/or resource blocks and/or other intervals will be idle. In this way, the new network can determine when it is able to transmit (whether DL or UL) without interfering with the existing active network. This embodiment may enable the spectrum of an existing active network to be used simultaneously without requiring any modification to the existing active network or relying on any special connection to the controller of the existing active network, as this is simply for the controller of the new network to receive the existing DL transmission from the existing active network. In another embodiment, the only modification to the existing active network is to ensure that it enables the new network to transmit the necessary control and timing information to maintain the connection with the UE. For example, existing active networks may be constructed so that transmissions are not made during the time that the necessary timing and synchronization information is being transmitted, but otherwise operate unmodified.

Although the above-described embodiment of networks simultaneously supporting in the same spectrum uses the LTE standard as an example, similar techniques may be used with other wireless protocols.

4. Using distributed antennas MU-MAS with the existing spectrum

Distributed antenna MU-MAS techniques (collectively "DIDO") as disclosed in sections 1 and 2 and in related patents and applications significantly increase the capacity of wireless networks, improve reliability and throughput per device, and also make it possible to reduce the cost of devices.

In general, DIDO operates more efficiently in TDD networks than FDD networks because the UL and DL are in the same channel, and therefore, training transmissions received in the UL channel can be used to derive channel state information for the DL channel by exploiting channel interchangeability. Furthermore, as mentioned above, TDD mode inherently prefers to accommodate the asymmetry of the mobile data, allowing for more efficient spectrum utilization.

Given that the current LTE deployment in the world is mostly FDD, by utilizing the techniques disclosed in section 3, it is possible to deploy TDD networks in the spectrum that is currently used for FDD, and DIDO can be used with this new TDD network, thereby significantly increasing the capacity of the spectrum. This is particularly significant in that UHF frequencies propagate better than microwave frequencies, but most UHF mobile frequencies have been used by FDD networks. By combining DIDO-based TDD networks with existing FDD networks in the UHF spectrum, an exceptionally efficient TDD network can be deployed. For example, band 44 is the TDD band from 703MHz to 803MHz, covering a large number of 700MHz FDD bands in the United states. The band 44 device can be used simultaneously in the same spectrum as the 700MHz FDD device, thus enabling DIDO TDD in the best spectrum.

DIDO does not add significant new constraints to the spectrum combining techniques described above. The DRAN104 shown in fig. 1 will replace an existing eNodeB in the coverage area or coordinate with an existing eNodeB 401, as shown in fig. 4, in accordance with the subframe (or resource block) sharing techniques described above.

Note that if the DIDO system controls the entire system and provides an eNodeB for an FDD network, the DIDO can use training signals such as SRS UL from FDD devices in order to simultaneously decode UL from multiple existing FDD devices and within the same frequency band via spatial processing, thereby significantly increasing the spectral efficiency of the existing FDD UL channels and also reducing the required UL power (and/or receiving preferred signal quality) because the distributed DIDO APs may be closer to the UE than a single cellular base station and can also utilize signal combining techniques such as Maximal Ratio Combining (MRC) or other techniques previously described for DIDO.

Thus, DIDO can replace existing enodebs and use existing spectrum concurrently with DIDO TDD devices, while also applying the benefits of DIDO to the UL of already deployed existing FDD devices.

5. Mitigating interference in incumbent spectrum

As previously shown, when a TDD network is deployed in UL or DL frequencies in a frequency band that has been allocated as an FDD frequency band, there may be concerns about interference with the output power of adjacent frequency bands. This may be caused by out of band transmit (OOBE) interference and/or receiver "blocking" or receiver "desensitization". OOBE refers to power transmission outside of the allocated frequency band. OOBE is generally at the highest power in frequencies immediately adjacent to the transmission band and generally decreases as frequencies become more distant from the transmission band. "receiver blocking" or "receiver desensitization" means that the front-end amplifier of the receiver loses sensitivity to a desired in-band (in-band) signal due to the presence of a powerful out-of-band (out-of-band) signal, typically in a nearby frequency band.

When a regulatory authority (e.g., FCC) allocates spectrum in adjacent bands for use by multiple mobile communication operators or other spectrum users, rules are typically imposed to limit OOBE and power levels so that mobile devices (e.g., mobile phones) and base stations can be manufactured to the actual specifications given the technology available at the time of regulatory compliance. Furthermore, existing users of adjacent spectrum and rules for manufacturing such devices are considered. For example, the new allocation of spectrum may consider the availability of a technology that would preferably allow oobs to reject powerful out-of-band transmissions more preferably than a technology determined during a previous spectrum allocation (older technologies that were more sensitive to oobs and powerful out-of-band transmissions were deployed at the time). Because it is often impractical to replace previous generation base stations and mobile devices, new deployments must follow the OOBE and powerful out-of-band transmission limitations of previous deployments.

In case of TDD deployment in FDD bands, there are additional constraints that must be followed. In FDD pairs, either the UL band or the DL band is allocated, which is expected to be UL only transmission or DL only transmission, respectively. Because TDD transmits alternately in both UL and DL, TDD deployments may operate in unintended transmission directions if they operate in FDD bands previously allocated as either UL-only or DL-only bands. Thus, to ensure that TDD transmissions do not interfere with FDD usage in the previously defined adjacent spectrum, TDD transmissions in the opposite direction of the previously defined FDD usage must meet the transmission requirements of the existing usage. For example, if TDD is deployed in FDD UL frequency band, the UL part of TDD transmission should have no problem, since UL is the previously defined direction of use. However, because the DL portion of the TDD transmission is in the opposite direction of the previously defined UL usage, the TDD DL transmission generally must meet the OOBE and powerful out-of-band transmission requirements defined for UL transmission.

In the case of TDD deployed in the UL band, the UL portion of the TDD transmission will typically be a transmission from a mobile device (e.g., mobile phone). FDD phones in adjacent bands and base stations in adjacent bands will have been designed to allow UL transmissions from mobile phones in adjacent bands. For example, fig. 16a shows an FDD band 7UL band divided into sub-bands a-G. FDD mobile phones and base stations operating in the shaded subband E are designed to allow UL transmission in FDD subbands a to D, F and G. Thus, if the TDD device is operated in an adjacent sub-band D (as shown in phantom in fig. 16b in TDD band 41 sub-band D, the same frequencies as FDD band 7 sub-band D), FDD band 7 mobile and base station devices will not have the problem of the UL portion of TDD transmission in band 41 sub-band D.

However, DL transmission in TDD band 41 sub-band D is not the case expected in the allocation of FDD band 7 or in mobile phones and base stations designed to operate in that band. The devices are considered in turn here.

In the case of FDD band 7 mobile phones in sub-band E, it is less likely to be adversely affected by base station DL transmissions in the adjacent TDD band 41 sub-band D, because the band 7 receiver of the mobile phone is designed to reject UL transmissions from other mobile phones transmitting in the adjacent UL band. In normal use, mobile phones may operate within a few inches from each other (e.g., if two people sitting in a stadium next to each other are both making a call), resulting in very high transmission power incident on the receiver of each phone. Techniques (e.g., cavity filters) reject such powerful adjacent band transmissions, enabling mobile phones that are physically close to mobile phones using adjacent bands to transmit UL signals without adversely affecting DL reception by adjacent mobile phones.

But the case of FDD band 7 base stations operating in sub-band E is different. The receiver is designed to receive UL from mobile devices in FDD band 7 sub-band E and reject UL from mobile devices in adjacent FDD band 7 sub-bands A through D, F and G. It is also designed to reject DL transmissions in band 38TDD subband H and band 7FDD DL in the subbands a 'to H' shown in fig. 16 a. Thus, the only case where an FDD band 7 base station is not designed is to reject DL transmissions from other base stations in sub-bands a to D, F and G. We should consider this case.

Fig. 15a, 15b, 15c and 15D consider four transmission scenarios between a TDD band 41 base station (BTS)1510 on a structure 1501 (e.g., building, tower, etc.) transmitting in sub-band D and an FDD band 7 base station (BTS)1530 on a structure 1502 receiving in UL sub-band E and transmitting in DL sub-band E'. In the following cases:

a.15a: there is no path between TDD BTS1510 and FDD BTS1530 because transmission is completely blocked by building 1505 and there are no multipath routes around building 1505 and therefore no TDD DL signal will reach FDD BTS 1530.

b.15b: there is only a Line of Sight (LOS) path between the TDD BTS1510 and the FDD BTS 1530. The LOS path will cause a very strong TDD DL signal to reach the FDD BTS 1530.

c.15c: there is a Non-Line of Sight (NLOS) path between TDD BTS1510 and FDD BTS1530, but no LOS path. While the NLOS path may be via a highly efficient reflector (e.g., a large metal wall) at an exact angle so that the signal reaching the FDD BTS1530 is close to the power of the LOS signal, it is statistically unlikely that there is an NLOS path close to the efficiency of the LOS path in real world scenarios. Conversely, it is possible in real-world situations that the NLOS path will be affected by objects that reflect and scatter at various angles, as well as objects that absorb and refract signals to a greater or lesser degree. Furthermore, by definition, NLOS paths are longer than LOS paths, resulting in higher path LOSs. All of these factors result in significant path LOSs in the NLOS path relative to the LOS path. Thus, statistically, it is likely that in a real-world scenario, the TDD DL NLOS signal power received by the FDD BTS1530 will be much less than the TDDDL LOS signal power received by the FDD BTS1530, as illustrated in fig. 15 b.

d.15d: there are both LOS and NLOS paths between TDD BTS1510 and FDD BTS 1530. This situation is effectively the sum of situations 15b and 15c, resulting in the FDD BTS1530 receiving the sum of the very strong signal from the LOS path of TDD BTS1510 and the statistically weak signal from the NLOS path of TDD BTS 1510.

Considering the four scenarios of the previous paragraph, it is clear that scenario 15a has no problem at all, since no signal is received by the FDD BTS 1530. NLOS case 15c results in some TDD DL BTS1510 signal reaching FDD BTS1530, but statistically, this signal is a much weaker signal than the LOS signal. Furthermore, in unlikely but still possible situations where the NLOS path is an efficient reflector, it can often be mitigated by field planning, e.g., resetting the bit or re-pointing to the TDD DL BTS1510 antenna, so that the NLOS path is not efficiently reflected. Cases 15b (LOS) and 15d (LOS + NLOS) are problematic situations because the LOS component in each results in a high power signal in the adjacent band, while the FDD BTS1530 is not designed to allow for this.

Although the NLOS components of cases 15c and 15d necessarily result in lower power signals being received by the FDD BTS1530 in the adjacent UL band, the FDD BTS1530 is designed to reject lower power, e.g., using a cavity filter, mostly NLOS signals from the entire UL band of the mobile device. Thus, if the LOS components of cases 15b and 15d can be mitigated, leaving only lower power (e.g., avoiding unlikely efficient reflections) NLOS signal components from cases 15c and 15d, this will result in the FDD BTS1530 receiving transmissions in the UL band only at the power level that is designed to allow, and will thus enable DL transmissions from the TDD BTS1510 in the UL band, without disrupting the operation of the FDD BTS 1530. As previously indicated, the other transmission directions in the FDD UL band will not disturb adjacent band operation, and thus, if the TDD dl BTS1510 LOS transmission component to the FDD BTS1530 can be mitigated, the FDD UL band can be used for TDD bi-directional operation without disturbing adjacent band FDD operation.

As previously disclosed in related patents and applications, multi-user multi-day such as DIDO systemsLine system (MU-MAS) with pCell^TMTrademarked technologies, or other multi-antenna systems, can utilize knowledge of Channel State Information (CSI) from the location of the user antenna to synthesize a coherent signal at the location of the user antenna, or to synthesize a null (i.e., zero RF energy) at that location. Generally, such CSI is determined by an in-band (IB) training signal transmitted from the base station to the user devices (in which case the user devices respond with CSI information) or from the user devices to the base station (in which case the base station determines the CSI with the location of the user antennas with interchangeability).

In one embodiment, a MU-MAS system as depicted in FIG. 14 above and operating as described in sections 1-4 above, the CSI at each UE location 111 is estimated, utilizing information from the respective VRI 106 (VRI)₁,VRI₂,…VRI_M) Synthesizes a separate pCell103 (pCell) in the same frequency band at each UE location 111₁,pCell₂,…pCell_M). In addition to estimating CSI at each UE location 111 as described in sections 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 pCell103 at each location 111, it also synthesizes pCell 1411(pCells 1..7, 8..14, and (b-6). b (collectively referred to as pCells) simultaneously at the location of each antenna 1403_1..b) Where all pCell are in the same frequency band. But unlike pCell103, each containing a resultant waveform from its corresponding VRI, each pCell 1411 is a zero bit with zero RF energy.

In one embodiment, the zero bit pCell 1411 described in the previous paragraph is synthesized by instantiating a VRI 1466, which will be flat (direct current (DC)_1..b) ) signals to VRM 108. In another embodiment, they are computed into zero bit positions within the VRM using techniques previously disclosed in the related patents and applications for synthesizing null signal (zero RF energy) contributions at the antenna locations.

When estimating CSI at the location of each antenna 1403 using in-band ("IB") training signals, highly accurate CSI estimates will be obtained using the techniques described in sections 1-4 and related patents and applications. For example, if the pCell transmission band is from 2530 to 2540MHz, in fig. 16b band D, a highly accurate CSI estimate will result if training signals in the same frequency range of 2530 to 2540 are used. But when estimating CSI at the location of the antenna using out-of-band ("OOB") signals (e.g., 2660-2670 MHz) instead of IB signals (e.g., 2530-2540 MHz, band E' in fig. 16 a), such OOB CSI estimation will only be reasonably accurate if the channel is "frequency flat" between the IB and OOB frequencies. Frequency flat means that the channel is flat attenuated in both IB and OOB frequencies, such that the signals in each of the IB and OOB frequencies experience the same amount of attenuation. The CSI estimate obtained using the self OOB signal may be very inaccurate for the IB signal if the IB frequency and OOB frequency have selective attenuation, i.e., the frequency components of the IB frequency and OOB frequency experience uncorrelated attenuation. Thus, if the band E 'of fig. 16a is frequency flat relative to the band D of fig. 16b, the training signal in the band E' can be used to obtain highly accurate CSI for the band D. However, if band E 'has significant selective attenuation relative to band D, the training signal from band E' will not result in accurate CSI for band D.

A pure LOS signal in free space where no NLOS component is present (e.g., as shown in fig. 15 b) is in a frequency-flat channel. Thus, if the only component of the signal is LOS, the OOB signal can be used to accurately estimate CSI for the IB signal at the location of the user antenna. However, in many real-world deployments, there is no pure LOS signal, but rather no signal at all (e.g., fig. 15a), only an NLOS signal (e.g., fig. 15c), or a combination of LOS and NLOS signals (e.g., fig. 15 d).

If the OOB signals are used to estimate the CSI for the antenna of the FDD BTS1530 from the perspective of the TDD BTS antenna 1510, then the following are the respective results for the scenarios in FIG. 15a, FIG. 15b, FIG. 15c, and FIG. 15 d:

a.15a: there is no signal and therefore no CSI will be available.

b.15b: LOS-only will result in consistently accurate CSI.

c.15c: NLOS-only (NLOS-only) will result in non-uniformly accurate CSI due to the possibility of selective fading of the NLOS-only channel.

d.15d: LOS + NLOS, the resulting CSI will be a combination of CSI components, where the NLOS components are non-uniformly accurate and the LOS components are uniformly accurate.

We denote the CSI derived from a pure LOS channel as C_LExpressing the CSI derived from the pure NLOS channel as C_NAnd the CSI derived from a channel with a combination of pure LOS and pure NLOS components is denoted as C_LN. The CSI combining LOS and NLOS can thus be formulated as C_LN＝C_L+C_N。

Access point 109 (AP) in fig. 14_1..N) With a pure LOS channel between antennas 1403, then the only CSI component is C for each antenna 1403_L. Because the pure LOS channel is frequency flat, if OOB signals are used to derive CSI, the CSI for each antenna 1403 will still be accurate. Thus, when deriving CSI using OOB signals, the LOS signals from each AP 109 will be nulled (nulled) with high accuracy at the location of each antenna 1403, resulting in little or no signal detectable by each antenna 1403 for transmissions from the AP 109.

In the case of a pure NLOS channel between AP 109 and antenna 1403, then the only CSI component is C for each antenna 1403_N. If the OOB signals are used to derive the CSI, the CSI for each antenna 1403 will be more or less accurate depending on whether the channel has multi-frequency flatness. Thus, when deriving CSI using OOB signals, the NLOS signals from each AP 109 will be either completely nulled (in the case of a completely frequency flat channel), partially nulled, or not nulled at all, depending on the degree of channel frequency selectivity. Each antenna 1403 will receive some random sum of the NLOS signal from the AP 109 if the NLOS signal is not nulled. Thus, there may be N from AP 109 to antenna 1403Some reduction in LOS semaphore value, but the NLOS semaphore value will not be higher than would be received if the CSI were not applied to attempt to null the NLOS signal.

In the case of a combined LOS and NLOS channel between AP 109 and antenna 1403, then the CSI is the combination C of LOS and NLOS components for each antenna 1403_LN＝C_L+C_N. C for CSI for each antenna 1403 depending on the multi-frequency flatness of the channel if the OOB signals are used to derive CSI_LThe component will be highly accurate and for C_NThe CSI of the component will be more or less accurate. C of CSI_LThe component affects the nulling of the LOS component of the signal between the AP 109 and the antenna 1403, while C of the CSI_NThe components affect nulling of the NLOS component of the signal between AP 109 and antenna 1403. Thus, when deriving CSI using OOB signals, depending on the degree of channel frequency selectivity, LOS signals from each AP 109 will be nulled uniformly throughout, while NLOS signals from each AP 109 will be nulled to a greater or lesser degree. Thus, in summary, the LOS component of the transmission from the AP 109 will be completely nulled, and the NLOS component of the transmission from the AP 109 will not have a larger signal magnitude than would be received by the antenna 1403 if the CSI were not applied to attempt to null the NLOS signal.

As previously indicated above, in the scenarios shown in fig. 15a, 15b, 15c and 15d, the problematic scenario is when the LOS component of TDD BTS1510 is received by FDD BTS 1530. The NLOS component of TDD BTS1510 is typically not a problem when it is received by FDDBTS 1530. Consider the MU-MAS embodiment described in the preceding paragraph: if TDD BTS1510 is one of APs 109 from fig. 14 and FDD BTS1530 is one of antennas 1403, then if the training signal used to determine the CSI for antenna 1403 is an IB signal, the transmission from TDD BTS1530 will be completely nulled at FDD BTS 1530. If the training signal used to determine the CSI for antenna 1403 is an OOB signal, the LOS transmission from TDD BTS1530 will be completely nulled at FDD BTS1530 and the NLOS transmission from TDD BTS1530 to FDD BTS1530 will not be worse than if the CSI was not applied to attempt to null the NLOS signal. Thus, the OOB training signals from the antenna 1530 will completely null any LOS component of the transmission from the antenna 1510, but will neither reliably null nor make stronger any NLOS component of the transmission from the antenna 1510.

Because only the LOS component of the signal transmitted from the antenna 1510 is problematic and it has been nulled, and the NLOS component of the antenna 1510 is not problematic and will not become worse, we therefore have an embodiment where the TDD BTS1530 can operate in an MU-MAS system such as that shown in fig. 14 in the FDDUL spectrum without significantly disrupting the receiver performance of an adjacent band FDD BTS, provided that at least the OOB signal from the FDD BTS is available.

In the case of many FDD systems, such OOB signals are actually available. For example, in fig. 16a, the FDD BTS1530 receiving the UL in sub-band E simultaneously transmits the DL in sub-band E'. Although data traffic may vary in the DL sub-band, control signals are typically transmitted over and over (e.g., in the LTE standard). Thus, at a minimum, these DL control signals can be used as OOB training signals for determining the CSI of the FDD BTS1530, taking advantage of the interchangeability techniques previously disclosed in the related patents and applications, and applying CSI derived from channel interchangeability of DL transmissions from the FDD BTS1530 (corresponding to antenna 1403 in fig. 14) in sub-band E' to generate nulls at FDD BTS1530 (corresponding to antenna 1403 in fig. 14) in sub-band D, simultaneous with TDD DL transmissions from TDD BTS1510 (corresponding to AP 109 in fig. 14) to the UE at location 111. The LOS component of the sub-band D TDD DL transmission from TDD BTS1510 (corresponding to AP 109 in fig. 14) will be completely nulled at FDDBTS 1530 (corresponding to antenna 1403 in fig. 14), while the NLOS component of the sub-band D TDD DL transmission will not be worse than if it were not nulled.

In addition to generating a null for TDD DL transmissions at the location of FDD BTS location 1530 within the bandwidth of the TDD DL transmission, it is also desirable to null the high power oobs from the TDD DL transmissions at the FDD BTS location. Because the OOBE from the LOS component is in a frequency flat channel, nulling of the LOS component in-band will also nullify the OOBE from the LOS component. However, in the case where the NLOS component is in a frequency selective channel, the OOBE of the NLOS component will not be nullified, but it will not be worse than if the OOBE from the NLOS did not attempt to null the LOS component. The power of the respective OOBE for LOS and NLOS transmissions is proportional 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 otherwise solve the highest power and most problematic OOBE component LOS, will not make the less problematic NLOS component worse.

FDD base stations typically have multiple antennas for diversity, beamforming, MIMO or other reasons. This is depicted in fig. 14, where multiple antennas 1411 are present on each structure 1431-1433. Thus, in general, there will be multiple FDDBTS antennas 1411 instead of the single FDD BTS antenna 1530 depicted in fig. 15a, 15b, 15c, and 15 d. In the case of any such antenna being transmitting, then the MU-MAS system described above and depicted in fig. 14 will receive respective transmissions from the antenna 1411, which will be used to derive the CSI for each antenna and the LOS component of the AP 109 transmission that is nulled to that antenna. In another embodiment, nulls will be generated for only some of the BTS antennas 1411. For example, some of the antennas 1411 may not be used for UL reception and will not have to generate nulls for them.

In a large scale deployment of the above embodiments, many TDD BTS antennas and adjacent sub-band FDD BTS antennas will be distributed throughout a large coverage area (e.g., city, region, country or continent). Obviously, not all antennas will be within range of each other, and thus it will only be necessary to null the TDD BTS DL transmissions whose power levels are sufficient to interfere with a given FDD BTS antenna. In one embodiment, VRM108 receives transmissions from FDD BTS DL AP 109 from FDD BTS antenna 1403 and evaluates the power level incident from TDD BTS AP 109 on each FDD BTS antenna 1403 from each TDD BTS AP 109. This evaluation can be done using various means, including utilizing channel interchangeability. VRM108 only synthesizes a zero at FDD BTS antenna 1403, which would receive oobs above a given threshold or receiver blocking/receiver desensitization power. The threshold may be set to any level, including but not limited to a threshold determined as an interference threshold or a threshold established by spectrum regulation.

Zero bit pCell 1411 is similar to that of pCell103 transmitting signals in that such zero bit pCell requires computational resources and AP 109 resources. Therefore, it is advantageous to reduce the number of AP 109 resources required to generate the zero bits pCell over the entire coverage area. In another embodiment, clustering techniques such as those previously disclosed in related patents and applications can be used to reduce the number of APs 109 required for pCell103 required for synthesizing user devices and pCell 1411 required for nulling antenna 1403 throughout the coverage area.

The above described embodiments deal with generating nulls at FDD DL antennas that are not aware of TDD operation in the adjacent spectrum. In another embodiment, the FDD DL antenna is aware of TDD operation in the adjacent spectrum and cooperates with the TDD system. In one embodiment, the FDD DL antenna 1403 regularly transmits training signals (e.g., such as LTE SRS signals) within the TDD band, thereby enabling the MU-MAS system in fig. 14 to have an IB reference for determining the accurate CSI of the FDD DL antenna 1403. With accurate CSI, VRM108 will be able to synthesize nulls for both LOS and NLOS components, enabling very high power TDD DL transmissions to be used in adjacent frequency spectrum, even if the NLOS signal will be nulled. In another embodiment, the FDD DL transmission is time and/or frequency interleaved with the training signal from the UE (such as SRS) or TDD DL BTS. In another embodiment, FDD DL antennas 1403 also transmit IB training signals in their own UL spectrum (e.g., times when simultaneous UL activity is selected to be absent) which can be used by VRM108 to determine OOBE CSI and generate zero bits for both NLOS as well as LOS OOBE.

In another embodiment, antenna 1403 is a TDD antenna used in the adjacent TDD spectrum. When the neighboring TDD system is synchronized in UL and DL, interference from OOBE and receiver blocking/receiver desensitization is minimized because all BSTs are in transmit or receive mode at the same time. It is sometimes desirable to have adjacent TDD system operations without synchronizing DL and UL times, for example, if adjacent networks require different DL and UL ratios or if they have different latency requirements, for example, if one network requires more frequent DL or UL intervals to reduce round trip latency. In these cases, the adjacent bands will be used in UL and DL simultaneously. The same techniques described above can be used for one or both systems to synthesize nulls at the BST antennas of the other system during the DL interval. In accordance with the techniques described above, one or both of in-band and OOBE transmissions may be nulled, also nulling LOS or NLOS components.

In one embodiment, the same spectrum used for the MU-MAS system in FIG. 14 is used to provide terrestrial wireless services while it is simultaneously used as a DL band for aircraft (i.e., with skyward transmissions). While the MU-MAS system is intended for ground use, where the aircraft falls within the antenna pattern of the AP 109, the path from the AP 109 to the aircraft will be LOS or mostly LOS, and may potentially interfere with the DL to the aircraft. By receiving the UL (i.e., ground-directed transmission) from the aircraft, the VRM may derive the CSI to the aircraft antenna using the techniques previously described, and thus synthesize a null at the location of the aircraft antenna. Because 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, the spectrum may be used simultaneously with the aircraft DL. This is a very efficient use of the spectrum, since the aircraft is not flying very often, and most of the time will be inactive if the spectrum is reserved specifically for the aircraft.

In another embodiment, the antenna of the aircraft is considered one or more UEs, along with the ground UE, and uses the same UL and DL capacity as any other UE when the aircraft is flown within range of the MU-MAS system shown in fig. 14. Multiple antennas may be used on an aircraft to increase capacity. The antennas may be positioned on or in the aircraft spread apart from each other and may be polarized to increase capacity. Individuals within the aircraft may also use their own devices (e.g., mobile phones) in the same spectrum, thereby connecting to the same MU-MAS. The MU-MAS will yield a separate pCell for the aircraft antenna and for the user UE.

Embodiments of the invention may include various steps that have been described above. Such steps may be embodied in machine-executable instructions, which may be used to cause a general-purpose or special-purpose processor to perform such steps. Alternatively, the steps may be performed by 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 a particular configuration of hardware, such as an Application Specific Integrated Circuit (ASIC), configured to perform certain operations or have predetermined functions or software instructions stored in a memory embodied in a non-transitory computer readable 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 (either internally and/or over a network) code and data using a computer-machine-readable medium, such as a non-transitory computer-machine-readable storage medium (e.g., magnetic disks; optical disks; random access memories; read only memories; flash memory devices; phase change memories) and a transitory computer-machine-readable communication medium (e.g., electrical, optical, acoustical or other form of propagated signals, such as carrier waves, infrared signals, digital signals, etc.).

Throughout this detailed description, for purposes of explanation, numerous specific details are 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 present invention may be practiced without some of these specific details. In some instances, well-known structures and functions have not been described in detail so as not to obscure the present invention. Accordingly, the scope and spirit of the invention should be judged in terms of the claims which follow.

Claims (16)

1. A first wireless network operating in TDD mode and including a plurality of transceiver stations,

a second wireless network operating in FDD mode and including one or more antennas,

wherein the first wireless network generates one or more points of zero Radio Frequency (RF) energy at a location of at least one of the plurality of antennas.

2. The system of claim 1, wherein the point of zero RF energy is generated to mitigate out-of-band emissions (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 multi-antenna system (MU-MAS) that uses precoding to produce the points of zero RF energy.

4. The system of claim 3, wherein precoding is calculated based on Channel State Information (CSI) between the plurality of wireless transceiver stations of the first wireless network and one or the plurality of antennas of the second wireless network.

5. The system of claim 4, wherein the CSI is estimated using an in-band (in-band) or an out-of-band (out-of-band) training signal, the in-band training signal or the out-of-band training signal being transmitted on a plurality of radio links between the radio transceiver station and one or the plurality of antennas.

6. A first wireless network operating in TDD mode and including a plurality of transceiver stations,

a second wireless network operating in FDD mode and including one or more antennas,

wherein the first wireless network generates one or more points of zero Radio Frequency (RF) energy at the location of at least one of the plurality of antennas, and

the second wireless network is unaware of TDD operation of the first wireless network.

7. A first wireless network operating in TDD mode and including a plurality of transceiver stations,

a second wireless network operating in FDD mode and including one or more antennas,

wherein the first wireless network generates one or more points of zero Radio Frequency (RF) energy at the location of at least one of the plurality of antennas, and

the second wireless network is aware of TDD operation of the first wireless network.

8. A first wireless network operating in TDD mode and including a plurality of transceiver stations,

a second wireless network operating in FDD mode and including one or more antennas,

wherein the first wireless network generates one or more points of zero Radio Frequency (RF) energy at the location of at least one of the plurality of antennas, and

the first wireless network provides terrestrial wireless service and the second wireless network provides wireless service to an aircraft.

9. A method of communicating over a network, the method comprising:

a first wireless network operating in TDD mode and including a plurality of radio transceiver stations,

a second wireless network operating in FDD mode and comprising one or more antennas,

the first wireless network generates one or more points of zero Radio Frequency (RF) energy at a location of at least one of the plurality of antennas.

10. The method of claim 9, wherein the point of zero RF energy is generated to mitigate out-of-band emissions (OOBE) or blocking from the first wireless network to the second wireless network.

11. The method of claim 9 wherein the first wireless network is a multi-user multi-antenna system (MU-MAS) that uses precoding to produce the points of zero RF energy.

12. The method of claim 11, wherein precoding is calculated based on Channel State Information (CSI) between the plurality of wireless transceiver stations of the first wireless network and one or the plurality of antennas of the second wireless network.

13. The method of claim 12, wherein the CSI is estimated using in-band or out-of-band training signals transmitted on a plurality of wireless links between the radio transceiver station and one or the plurality of antennas.

14. A method of communicating over a network, the method comprising:

a first wireless network operating in TDD mode and including a plurality of radio transceiver stations,

a second wireless network operating in FDD mode and comprising one or more antennas,

the first wireless network generates one or more points of zero Radio Frequency (RF) energy at a location of at least one of the plurality of antennas, and

the second wireless network is unaware of TDD operation of the first wireless network.

15. A method of communicating over a network, the method comprising:

a first wireless network operating in TDD mode and including a plurality of radio transceiver stations,

a second wireless network operating in FDD mode and comprising one or more antennas,

the first wireless network generates one or more points of zero Radio Frequency (RF) energy at a location of at least one of the plurality of antennas, and

the second wireless network is aware of TDD operation of the first wireless network.

16. A method of communicating over a network, the method comprising:

a first wireless network operating in TDD mode and including a plurality of radio transceiver stations,

a second wireless network operating in FDD mode and comprising one or more antennas,

the first wireless network generates one or more points of zero Radio Frequency (RF) energy at a location of at least one of the plurality of antennas, and

the first wireless network provides terrestrial wireless service and the second wireless network provides wireless service to an aircraft.