WO2018009516A1 - High resolution angle of arrival estimation and dynamic beam nulling - Google Patents

Abstract

High resolution angle of arrival (AoA) estimation and dynamic beam nulling may be provided. A beam direction with a highest received interference power may be determined, for example, by sweeping a beam. The beam may be a generic fixed beam. The generic fixed beam may have a predefined shape with a larger main lobe and narrow nulls. A null may be directed in the determined beam direction. A request for scheduling information may be sent to one or more transmit nodes. Scheduling information feedback may be received from the one or more transmit nodes. Beam shaping may be employed with nulling. The beam shaping may be employed based on the determined beam direction and/or the scheduling information feedback. A beam shape may be optimized and/or one or more nulls may be allocated based on the scheduling information feedback.

Description

HIGH RESOLUTION ANGLE OF ARRIVAL ESTIMATION AND DYNAMIC BEAM

NULLING

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No.

62/358,331 filed July 5, 2016, and U.S. Provisional Application Serial No. 62/430,063 filed December 5, 2016, the contents of which are incorporated by reference herein, and this application claims benefit of the filing date of these priority applications.

BACKGROUND

[0002] Current beamforming techniques may suffer from weaknesses. For certain phased array antennas (PAAs) (e.g., low-cost PAAs that may be limited to analog beam forming), shaping and/or nulling a signal based on per element signal observations at the receiver may not be feasible.

SUMMARY

[0003] Systems, methods, and instrumentalities are disclosed for high resolution angle of arrival (AoA) estimation and dynamic beam nulling. Nulling may be performed based on high resolution AoA estimation (e.g. , at a receiving node). Measurement null shaping may be performed based on one or more interfering AoAs. An AoA aware receiving node may perform beam shaping. Beam shaping and/or nulling may be performed based on one or more measurement inputs and/or feedback. A transmitting node may perform nulling and/or null shaping. A multi-stage beamforming may be performed that enables nulling such that directional interference may be mitigated. A receive and/or a transmit beam may be adjusted based on a signal frequency. One or more interference measurement campaigns may be updated based on nulling. A central controller based backhaul measurements campaign may be provided. A sub- controller based access measurements campaign may be provided.

[0004] A beam direction with a highest received interference power may be determined, for example, by sweeping a beam. The beam may be a generic fixed beam. The generic fixed beam may have a predefined shape with a larger main lobe and narrow nulls. A null may be directed in the determined beam direction. A request for scheduling information may be sent to one or more transmit nodes. Scheduling information feedback may be received from the one or more transmit nodes. A request for exclusion scheduling information may be sent to the one or more transmit nodes. Beam shaping may be employed with nulling. The beam shaping may be employed based on the determined beam direction and/or the scheduling information feedback. A beam shape may be optimized and/or one or more nulls may be allocated based on the scheduling information feedback. A plurality of nulls may be directed based on one or more AoAs associated with a plurality of simultaneous interfering rays. A null may be shaped based on the one or more AoAs associated with the plurality of simultaneous interfering rays.

[0005] A receiving node (RN) may include one or more antennas and/or antenna element. The RN may be configured to receive one or more beamformed signals from one or more transmitting nodes (TNs). For example, the RN may receive a first beamformed signal from a first TN and a second beamformed signal from a second TN. The first beamformed signal may include a first beam identification (ID) associated with the first TN, and the second beamformed signal may include a second beam ID associated with the second TN.

[0006] The RN may perform first measurement on the first beamformed signal and second measurement on the second beamformed signal. The RN may be configured to send the first measurement on the first beamformed signal and the second measurement on the second beamformed signal to a central controller.

[0007] The RN may generate or receive first feedback information based on the first measurement and second feedback information based on the second measurement. The RN may determine or receive an indication that at least one of the first measurement or the second measurement is above a threshold interference level. The RN may receive the first scheduled transmission information associated with the first TN and/or the second scheduled transmission information associated with the second TN. The first scheduled transmission information may include first indication of the first time that the first TN is scheduled to transmit. The second scheduled transmission information may include the second indication of the second time that the second TN is scheduled to transmit. The RN may receive an interference matrix from the central controller. [0008] The RN may configure the first dynamic null associated with the first scheduled transmission information and/or the second dynamic null associated with the second scheduled transmission information. The RN may configure the first dynamic null based on one or more of the first measurement, the first scheduled transmission information, or the first beam ID. The RN may configure the second dynamic null based on one or more of the second measurement, the second scheduled transmission, or the second beam ID. The RN may configure the first dynamic null based on one or more of the interference matrix and the first scheduled

transmission. The RN may configure the second dynamic null based on one or more of the interference matrix and the second scheduled transmission. The first signal that comprises the first dynamic null and/or the second signal that comprises the second dynamic null may be configured to have one or more dynamically changing main lobe, null depth, and/or null width. The RN may send a first signal associated with the first dynamic null to the first TN and/or a second signal associated with the second dynamic null to the second TN. The first signal that comprises the first dynamic null and/or the second signal that comprises the second dynamic null may be sent via analog beamforming.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 depicts example transmit and receive chains for analog beam forming.

[0010] FIG. 2 depicts an example mesh network with directional transmit and receive beams.

[0011] FIG. 3 depicts an example architecture supporting joint access/backhaul ultra dense network deployment.

[0012] FIG. 4 depicts an example receive beam shape.

[0013] FIG. 5 depicts an example null oriented towards an initial interference ray estimate direction.

[0014] FIG. 6 depicts example multiple simultaneous nulling based on coarse angles of arrivals (AoAs).

[0015] FIG. 7 depicts an example feedback messaging chart for dynamic and/or semi- dynamic beam shaping.

[0016] FIG. 8 depicts an example feedback messaging chart for dynamic and/or semi- dynamic beam shaping using exclusion scheduling.

[0017] FIG. 9 depicts an example chart of AoAs at a receiving node over time.

[0018] FIG. 10 depicts an example multi-stage beamforming to enable nulling.

[0019] FIG. 11 depicts an example messaging chart for transmit side nulling signaling. [0020] FIG. 12A is a system diagram of an example communications system in which one or more disclosed embodiments may be implemented.

[0021] FIG. 12B is a system diagram of an example wireless transmit/receive unit

(WTRU) that may be used within the communications system illustrated in FIG. 12A.

[0022] FIG. 12C is a system diagram of an example radio access network and an example core network that may be used within the communications system illustrated in FIG. 12A.

[0023] FIG 12D is a system diagram of another example radio access network and an example core network that may be used within the communications system illustrated in FIG. 12A.

[0024] FIG. 12E is a system diagram of another example radio access network and an example core network that may be used within the communications system illustrated in FIG. 12A.

[0025] FIG. 12F illustrates exemplary wireless local area network (WLAN) devices.

DETAILED DESCRIPTION

[0026] A detailed description of illustrative embodiments will now be described with reference to the various Figures. Although this description provides a detailed example of possible implementations, it should be noted that the details are intended to be exemplary and in no way limit the scope of the application.

[0027] Ray tracing may be performed based on one or more mmW channel models. A narrow-band channel matrix based on a clustered channel model may be represented by:

where N_ci may represent a number of scattering clusters. Each of the scattering clusters may have Nray paths, oui may represent a complex gain of the 1^th ray in the i^th cluster. Ar and At may represent the transmit antenna gain and the receive antenna gain, respectively. a_r and at may represent the normalized transmit array response vectors.

[0028] Analog beamforming may include performing channel sounding to determine channel sounding information, determining statistical channel information based on the channel sounding information, and/or determining one or more analog beamforming coefficients based on the statistical channel information. Antenna array response vectors for Uniform Linear Array (ULA) may be represented as, „

uULAy

with k=2pi/ , and d may represent the inter-element spacing.

y = W_R ^* _FHF_RFs + W_R ^* _Fn,

where FRF: lxNtRF RF precoder and WRF: lxNrRF RF combining matrix.

[0029] A throughput optimal RF precoder (FRF) at a transmitter with a perfect (ML) receiver assumption may be represented as;

k = arg max_{l=1 >} ... , Ν^Ν^ΨΨ^*^ Ψ = A^* _TF_RES where, Fres = Vi

ray' ^lvcl^lvray

H = U∑V^* ∑ V = [V₁ V₂]

[0030] With a fixed FRF, a minimum mean square error (MMSE) based combining vector

(WRF) at the receiver may be represented as;

A_r = [ _Γ(φϊ ₁, Q ₁ , ... , a_t($^r _{Ncl Nray}, Q^rN_clN_ray )]

k = arg max_l=1 , ... , N_clN_ray( ^*)_{l l}

Ψ = A^* _rE[yy^*]W_RES W_RES = W_MMSE

where

W_MMSE = ^[s lECyy^*]-¹ = ^ F^F^_FH^*(^ HF_RFF_BBF^_BF^_FH^* + o^-ⁱ

[0031] For certain phased array antennas (PAAs) (e.g., low-cost PAAs that may be limited to analog beam forming), shaping and/or nulling a signal based on per element signal observations at the receiver may not be feasible. If the radio frequency (RF) chain has access to an aggregated signal (e.g., access to an aggregated signal only), this may result in large main lobes and/or narrow nulls. High resolution angle of arrival (AoA) estimation based on the weighted sum signals may not be provided. For efficient interference mitigation, nulling techniques may be needed that may rely on high resolution AoA estimation. Analog

beamforming may not accommodate the nulling and/or may not maximize the desired signal power.

[0032] Current transmitter side beamforming techniques may focus on maximizing the desired signal power. Efficient mechanisms to incorporate transmitter side nulling leveraging network side information, e.g., scheduling, may be needed. A null in the antenna pattems may be sensitive to frequency. For example, a null angle may vary in different parts of the channel BW. A given set of weights may place the null (e.g., to determine the null angle) exactly at the AoA at the center of the channel. The full depth of the null may not be measured (e.g. , since the null may be at a slightly different direction than the AoA at the channel edges).

[0033] Interference measurement campaigns may be updated based on the nulling employed at the nodes.

[0034] Nulling may be performed based on high resolution AoA estimation. One or more high resolution AoAs may be identified for low-cost PAAs (e.g. , for efficient nulling). Analog beamforming may accommodate nulling and/or a maximized desired signal power. For example, high resolution AoA estimation may be performed at a receiver (e.g. , Rx).

[0035] FIG. 2 depicts an example mesh network with directional transmit (Tx) and receive (Rx) beams. WRF may represent the combining vector with WRF = [e>^ei, e>^e2, ... ., ei^9Nt].

[0036] A cluster may include a plurality of nodes, for example, as shown in FIG. 2. In a scheduled interference measurement campaign scenario, each of the plurality of nodes may be scheduled for transmission at a predefined time interval. When a node of the plurality of nodes sends a transmission at a predefined time interval, other nodes in the cluster may measure the interference observed due to the transmission. The transmitting node may use one or more transmit (e.g. , Tx) beams which are beamformed and/or refined for its destinations, e.g., in a previous beamforming stage. The previous beamforming stage may include an initial device discovery and/or a measurement campaign.

[0037] FIG. 3 depicts an example architecture supporting joint access and backhaul, e.g., in an ultra-dense network deployment. The schedule of a transmitter and/or a receiver may be available to each node via one or more central or distributed control entities, as shown in FIG. 3.

[0038] A central controller entity may create an interference matrix. The interference matrix may associate one or more parameters such as null depths, widths, and/or directions for backhaul links. The central controller may set up routing between one or more nodes and/or wireless transmit receive units (WTRUs). The interference matrix may include one or more WTRUs in each access node. For example, a sub-controller may interfere with a neighboring node and/or one or more interfering WTRUs. The example architecture may include a plurality of sub-controllers. The plurality of sub-controllers may communicate with each other. The plurality of sub-controllers may communicate with the central controller. The central controller may reside in a core cellular network, for example.

[0039] Discovery during network formation may include access and/or backhaul links.

When the discovery process is complete, one or more beamforming campaigns in a periodic and/or event driven fashion may be utilized to update the interference matrix among the nodes as shown in FIG. 3. The example architecture may support in-band and/or macro overlay control plane messaging. The central controller may be an IP cloud or a cell network based solution. The plurality of sub-controllers may be logically connected to the central controller.

[0040] One or more transmissions may be sent over a plurality of time intervals. One or more nodes other than the receiving node and the transmitting node may measure an interference power of a transmission. For example, a first node (e.g. , transmitting node or Node G in FIG. 2) may send a first transmission to a second node (e.g. , receiving node or Node A in FIG. 2) in a first time interval. The first transmission may be sent using a first refined transmit beam. One or more other nodes (e.g. , Node B, C, D, and/or E in FIG. 2) may measure an interference power of the first refined transmit beam. The first node (e.g. , transmitting node or Node G in FIG. 2) may send a second transmission to a third node (e.g. , receiving node or Node C in FIG. 2) in a second time interval. The second transmission may be sent using the first refined transmit beam. One or more other nodes (e.g. , Node A, B, D, and/or E in FIG. 2) may measure an interference power of the first refined transmit beam. A fourth node (e.g. , transmitting node or Node E in FIG. 2) may send a third transmission to the third node (e.g. , receiving node or Node C in FIG. 2). The third transmission may be sent using a second refined transmit beam. One or more other nodes (e.g. , Node A, B, D, and/or G in FIG. 2) may measure an interference power of the second refined transmit beam.

[0041] A high resolution interfering ray AoA for nulling (e.g. , with higher resolution than receive sector sweep (rxss) AoA estimation) may be determined. To determine the high resolution interfering ray AoA for nulling, a measuring node may perform one or more of the following.

[0042] A receiving and/or measuring node (e.g. , such as nodes B, C, D, E in FIG. 2) may sweep one or more beams (e.g. , a generic fixed beam) to identify a beam orientation with the highest received power (e.g. , interference power). For example, the receiving and/or measuring node may sweep 360 degrees horizontally and/or vertically. The generic Rx beam may have a predefined shape. The generic Rx beam may have a larger main lobe and narrow nulls (e.g. , due to access to the aggregated signal only).

[0043] For nulling, the beam direction with the highest received power, e.g. , ΘΗ, may be used as the initial candidate space to identify the high resolution AoA.

[0044] FIG. 4 depicts an example receive beam shape. ΘΗ may represent an AoA for a received signal. ΘΝ may represent a null angle. A null (e.g. , fixed width, ΘΝ degrees) may be initially directed towards the AoA for a received signal, ΘΗ. The Rx node may sweep the beam starting from the ΘΗ direction. The beam sweeping may be continuous. The beam sweeping may be performed in discrete actions, e.g. , two or more discrete steps. [0045] FIG. 5 depicts an example null oriented toward an initial interference ray estimate direction (e.g. , the AoA for a received signal, ΘΗ).

[0046] Faster AoA estimation may be configured. For faster AoA estimation, the Rx node may identify the beam orientation that results in an interference power (Pint) below a target threshold. When the Rx node identifies the beam orientation that results in an interference power (Pint) below a target threshold, e.g., Pint < *noise floor (e.g., where the parameter β may take any predefined value), the beam sweeping may be terminated. For example, the receiving node may stop beam sweeping when the interference power is determined to be below a predefined threshold.

[0047] The minimum Rx power orientation in the nulling direction may be the high resolution interfering ray AoA.

[0048] Measurement null shaping may be performed based on one or more interfering

AoAs. When the Rx node identifies two or more interfering ray AoAs (e.g., such as ΘΗΙ and Qm) that are closer than a threshold, e.g. , Qm - Qm≤ 6th, the Rx node may dynamically shape its null to accommodate the two or more interfering ray AoAs. The dynamic null shaping may determine a wider null width, ΘΝ, and/or more depth. The wider null width and/or more depth may be determined by the measurement results, e.g. , the AoAs and/or received interference powers, Pint.

[0049] AoAs for multiple simultaneous interfering rays may be detected. Detecting

AoAs for multiple simultaneous interfering rays may enable better interference mitigation.

When a measurement corresponding to the largest signal power is completed, the Rx node may continue the measurement initially oriented at the angle corresponding to the next largest received signal. The Rx node may identify the AoAs that correspond to N largest interference power directions: ΘΗ = [ΘΗΙ, ΘΗ2, . . . , ΘΗΝ].

[0050] FIG. 6 illustrates an example of multiple simultaneous nulling, e.g. , based on coarse AoAs.

[0051] The generic Rx beam may be swept within the vicinity of the directions estimated to identify the high resolution AoAs. The generic Rx beam may be swept starting from the direction corresponding to the largest received power and sequentially following the remaining coarse AoA directions (e.g., in descending order of received power). For a faster operation, the search space per direction may be configured to (e.g., or limited to) a particular window, e.g. , [ΘΗΙ - 6s, ΘΗΙ + 6S] . [0052] The Rx node may sweep 360 degrees (e.g. , the entire 360 degrees). The sweeping may be optimized based on the identified high resolution AoAs, e.g., using one or more steepest descent methods.

[0053] Using the identified high resolution AoAs, e.g. , [ΘΗΙ, ΘΗ2, . . . , ΘΗΝ], the Rx node may allocate one or more nulls at directions corresponding to the identified high resolution AoAs. For example, the high resolution AoA estimation may be continued simultaneously for some or all the identified interference angles above a predetermined threshold. With the nulls placed at the identified high resolution AoAs [ΘΗΙ, ΘΗ2, . . . , ΘΗΝ], the Rx node may sweep its beam to identify the minimum total received interference power.

[0054] The one or more interfering ray AoAs at the measuring nodes may be determined when particular nodes are scheduled for transmission, e.g. , Node G and A as shown in FIG. 2. The one or more interfering ray AoAs at the measuring nodes may be used in beam shaping for interference mitigation as described herein.

[0055] A receiver may perform AoA aware beam shaping. The Rx node may identify one or more AoAs of the dominant interfering signals corresponding to each potentially interfering transmission (e.g. , such as Nodes B, C, D, and/or E during G- A transmission, as shown in FIG. 2). One or more Rx beams may be generated and/or modified based on the identification of the one or more AoAs of the dominant interfering signals. The one or more Rx beams may be generated and/or modified such that nulls may be located at the one or more AoAs of the dominant interfering signals, as described herein.

[0056] In an example, an Rx node may identify one or more nodes that create interference (e.g., interference above a threshold, such as a predetermined threshold). The Rx node may obtain scheduling information of the one or more nodes that create an interference that is above a predetermined threshold (e.g. , from the central controller). The scheduling information may be used to modify the beam shapes accordingly (e.g., by optimizing the main lobe and/or null depths and widths).

[0057] One or more of the following may be considered for the Rx beam shaping and/or scheduling information feedback from the neighbor nodes (e.g. , dynamic beam shaping and/or semi-dynamic beam shaping).

[0058] A Rx node may use the Rx beam shaping and/or scheduling information feedback from one or more neighbor nodes to perform dynamic beam shaping. For example, the Rx node may generate its Rx beam (e.g. , dynamically) such that the nulls and/or the main lobe may be placed in every transmit time interval (TTI)/scheduling interval or in one or more multiples of TTI/scheduling interval. The Rx beam may be optimized based on one or more of the available scheduling information, the desired signal, and/or interfering rays AoAs (e.g. , and their received power). For example, the Rx node may request scheduling information from one or more nodes that create above threshold information. The Rx node may request scheduling information from a central controller. The Rx node may request scheduling information periodically (e.g., every k TTI intervals). The scheduling information request message may include additional information that indicates one or more Tx beams of the interfering node that create above threshold interference. The interfering nodes may be configured to transmit during the scheduled times (e.g. , only during the scheduled times) with these beams associated with the beam IDs such that the Rx node may employ beam shaping configured according to these beams (e.g., to minimize the feedback overhead).

[0059] When the interfering beam IDs and/or scheduling times are received via the feedback, the Rx node may employ beam shaping and/or assign nulls dynamically. The beam shaping and/or null optimization may include implementation(s) as described herein.

[0060] The feedback may be sent (e.g. , automatically) to the affected nodes by the transmitting node. For example, the transmitting node may send the feedback to the affected nodes based on an interference matrix during or prior to the respective scheduled transmissions.

[0061] Beam shaping may be performed semi-dynamically. An Rx node may create a fixed beam shape in durations longer than a TTI/scheduling interval. The Rx node may request an averaged scheduling information from one or more dominant interference source(s). The averaged scheduling information may identify how many slots the interfering transmission is scheduled for. The Rx node may request scheduling information from one or more nodes that create an interference above a predetermined threshold interference every n TTI intervals (n » k). The scheduling information may include the Tx beam IDs for the one or more Tx beams that create high interference (e.g., above the predetermined threshold interference). The interfering nodes may determine how many TTIs each Tx beam is scheduled for, based on the scheduling information.

[0062] FIG. 7 depicts an example feedback chart for dynamic and/or semi-dynamic beam shaping. The parameter k may be determined, for example, based on the frequency of beam- shaping. For example, a Rx node may initiate a measurement campaign to identify one or more AoAs. The Rx node may determine that one or more nodes (e.g., Node A and/or Node B) have Tx beams above a predetermined threshold interference. The Rx node may request feedback from the one or more nodes (e.g. , Node A and/or Node B) for each k (e.g., 100) TTIs. The one or more nodes may send scheduling information feedback to the Rx node. Node A and/or Node B may inform the Rx node how many TTIs its Tx Beam 1 , Tx Beam 2, ... , Tx Beam N are scheduled. The one or more nodes may not send the exact timing of the Tx beams. The Rx node may perform beam shaping with nulling based on the scheduling information feedback from one or more nodes (e.g., Node A and/or Node B).

[0063] After receiving the average number of Tx beams used in the upcoming N TTIs, the Rx beam may optimize its beam shape and/or allocate its nulls accordingly.

[0064] FIG. 8 depicts an example feedback messaging chart for dynamic and/or semi- dynamic beam shaping using exclusion scheduling. The parameter k may be determined, for example, based on the frequency of beam-shaping. An Rx node (e.g., a measuring node) may send a request for exclusion scheduling information to one or more nodes (e.g., potentially interfering reporting nodes). The nodes (e.g., potential interfering nodes) may report to the Rx node regarding, for example, the channel resources that the nodes will not use to schedule transmissions that may interfere with the requesting node (e.g., Rx or measuring node). For example, instead of reporting the schedule of interfering transmissions, the nodes may report exclusion schedule information to the Rx node. The exclusion schedule information may be the schedule when the interfering transmissions/beams will be inactive. Exclusion schedule information reporting may be dynamic or semi-dynamic. Whether the exclusion schedule information is reported dynamically or semi-dynamically may affect the reporting periodicity. When the exclusion schedule information is reported dynamically, the nodes may report the exclusion schedule information on a per TTI basis (e.g., for a relatively small number of upcoming TTIs). When the exclusion schedule information is reported semi-dynamically, the nodes may report the exclusion schedule information every n TTIs (e.g., where n » k). The semi-dynamic reporting may include an average number of inactive TTIs at the nodes. The exclusion schedule information may be exchanged during node association. The exclusion schedule information may be exchanged periodically (e.g., every n TTIs). The reporting nodes may specify individual Resource Blocks (RBs) and/or a series of RBs that will not be used to schedule transmissions that may interfere with the Rx node. As shown in FIG. 8, multiple messages may be sent to or from the same node at the same time.

[0065] The reporting nodes may reserve some channel resources and/or RBs, such that the reserved channel resources and/or RBs are not used for transmission. Corresponding channel resources and/or RBs may be reserved for a node transmitting to the Rx node (e.g., Node G in FIG. 8) to schedule one or more transmissions to the Rx node (e.g., the requesting/measuring node) to avoid interference from the reporting nodes. The reporting nodes may determine an amount of channel resources and/or RBs to leave vacant (e.g., to prevent interference for transmissions from the Tx node to the Rx node). For example, the reporting nodes may use historical scheduling information to determine the amount of channel resources and/or RBs that may be left vacant. The reporting nodes may report, to the Rx node, the channel resources that are left vacant. The Rx node may report the channel resources that are left vacant to one or more other nodes, for example, such as Node G in FIG. 8.

[0066] The reporting nodes may periodically report interference schedules or exclusion schedules to the requesting/measuring node. The requesting/measuring node may modify the reporting parameters by sending a request (e.g. , a new request) to the reporting nodes.

[0067] When the interference transmission schedule or the exclusion schedule is known to the requesting/measuring node, the requesting/measuring node may determine an appropriate receiver beam shape to use for receiving transmissions from the transmitting node (e.g. , Node G in FIG. 8). When interference is expected, beam nulling may be used, and nulling may be removed when no interference is expected. Beam nulling may impact the receive antenna gain. For example, some antenna gain may be sacrificed in a desired direction when nulling is applied in another direction. The transmitting node (e.g. , Node G) may use a lower Modulation and Coding Scheme (MCS) for one or more (e.g. , all) transmissions. Using a lower MCS for transmissions may ensure successful signal reception by the intended receiver, e.g. , under some or all conditions.

[0068] The reporting nodes may send the interference transmission schedule or the exclusion schedule to the transmitting node, for example, so that the transmission MCS may be adjusted depending on the interference transmission schedule or exclusion schedule. The Rx node may send the interference transmission schedule and/or the exclusion schedule to the transmitting node.

[0069] In the dynamic beam shaping and/or semi-dynamic beam shaping, the width and depth of the nulls may be determined based on one or more of the following measurement inputs/parameters .

[0070] The width and depth of the nulls may be determined based on a power of the interfering signal at the detected AoA obtained via the measurement campaign.

[0071] The width and depth of the nulls may be determined based on an uncertainty of an interfering signal AoA (e.g. , mainly due to the AoA estimation). Faster AoA estimation, e.g. , interval based [ΘΗΙ - 6s, ΘΗΙ + 6s], may result in higher uncertainty, which may require larger null widths.

[0072] The width and depth of the nulls may be determined based on a proximity of the interfering AoAs to the desired signal AoAs. In the case of adjacent AoAs for desired and interfering signals, the null depth and width may be determined based on the desired and interfering signal power ratios, e.g. , signal-to-interference-plus-noise ratio (SINR). For large interference-to-noise ratio (INR) value, the null width and depth may be made larger. For a small INR value, the null width may be made smaller.

[0073] The width and depth of the nulls may be determined based on one or more adjacent interfering rays with closer AoAs. A null may be generated wide enough to capture the neighboring AoAs within the null.

[0074] The Rx node may determine the nulls in an orientation to minimize the dominant

(e.g. , most dominant) interference source. The Rx node may determine a weighted average of the received interference AoA correlated with their power and allocate its nulls (AoA) accordingly.

[0075] FIG. 9 depicts an example chart of AoAs (e.g., interfering AoAs) at a receiving node (e.g. , Rx node) over time. The Rx node may shape its Rx beam using the scheduling information received from, for example, the interfering nodes. In the example shown in FIG. 9, the largest interference is observed in the AoA of 120 degrees. The Rx node may allocate nulls based on the dynamic and/or semi-dynamic beam shaping.

[0076] FIG. 10 depicts an example multi-stage beamforming to enable nulling (e.g. , antenna nulling). The antenna nulling may mitigate directional interference. A receiving node may identify one or more good receive beams. A good receive beam may be a receive beam associated with a receive power above a predefined threshold, a predefined SNR, and/or a predefined SINR. A good receive beam may satisfy one or more beam-width constraints, for example, a beam-width larger than a predefined beam-width threshold. A good receive beam may be chosen based on one or more of an observed interference below a predefined threshold, a time duration for which interference is observed or not observed, and/or one or more interference power management characteristics. The receiving node may determine the transmit beam IDs associated with the good receive beams at the transmitting node. The receiving node may identify multiple beam pairs that satisfy certain channel quality conditions (e.g. , as described herein). The maximum number of beam pairs to be identified may be pre-defined, or the receiving node may identify one or more (e.g., all) possible beam pairs that meet the channel quality requirements.

[0077] The receiving node may identify one or more (e.g. , all) directions from where the receiving node detects directional interference that exceeds a threshold, e.g. , a certain predefined signal strength (e.g. , signal level) threshold. For example, the receiving node may determine the angles associated with one or more interfering nodes that exceeds a certain predefined signal strength threshold. [0078] The receiving node may calculate an antenna weight vector (AWV) that maximizes the SINR. For example, the receiving node may map the optimum receive beam direction associated with the intended transmitting node to an AoA value. The beams associated with one or more interfering nodes may be mapped to equivalent AoA values. The receiving node may calculate the AWV that maximizes the signal strength along the desired AoA, and may minimize the gain in the directions of the interfering nodes. The AWV calculations may be repeated for the acceptable beams associated with the intended transmitting node, for example, the beams identified by the receiving node as good receive beams.

[0079] The receiving node may report back to the intended transmitting node regarding the chosen transmit beams that the transmitting node is paired (e.g. , will use) to communicate with the receiving node. The chosen transmit beams may be different than the beam(s) that maximize SINR between the transmitting node and the receiving node.

[0080] FIG. 11 depicts an example messaging chart for Tx side nulling signaling. A transmitter may perform nulling. During the interference measurement campaign, one or more Rx/measuring nodes may identify the interfering AoAs that create interference above a threshold interference power. The Tx beam ID may be made available to the one or more receiving nodes due to the predefined measurement campaign, and/or by the transmitting nodes during the measurement campaign.

[0081] An Rx node may identify which Tx node(s) to inform regarding one or more high interfering beams during the initial measurement stage where the maximum interfering AoAs may be determined. The Rx node may employ the high resolution AoA estimation (e.g., initially) and may identify the received interference power after nulling. The Rx node may identify the Tx node(s) to be informed for Tx side nulling, e.g. , based on the identified received interference power.

[0082] The Rx node may inform one or more transmitters (e.g., transmit nodes) regarding the maximum interference directions (e.g., and Tx beam IDs) at the end of the interference measurement and/or Rx side nulling. For example, the Rx node may inform the one or more Tx nodes regarding which receive beams are most affected, e.g. , Tx beam-Rx beam pair with maximum interference power (e.g. , INR). Which receive beams are most affected and/or scheduling information may be used by the Tx node for nulling.

[0083] When the scheduling is carried out at the Rx node, the Rx node may send indicator information to one or more interference sources. The indicator information may indicate the necessity for Tx nulling for the Rx beams that are scheduled and known to be affected by the interference/Tx nodes. The exact TTI of the expected interference may be included in the indicator information. The indicator information may be part of scheduling process prior to the actual transmission or signaled during the transmission as part of control plane messages.

[0084] Based on the indicator information, the Tx node may perform nulling at the Tx beam that is known to create interference if the Tx node is scheduled for transmission. When the scheduling information is available, e.g. , the exact TTI time of interference is known, the Tx node may determine whether its scheduled transmission overlaps (e.g., interferes) with the Rx nodes scheduling. If the scheduled transmission interferes (e.g. , overlaps) with the Rx node scheduling, the Tx node may perform nulling at the corresponding TTI.

[0085] Using the feedback received from the Rx node, the Tx node may identify one or more Tx beams that create interference with the corresponding Rx beam. For example, the Tx node may determine the nulling angle and/or width/depth based on the Tx beam IDs angle of departure (AoD) of the one or more Tx beams. One or more of the following may be used to optimize the Tx side nulling.

[0086] After the Rx side nulling is performed, the Rx node may request a Tx side nulling operation based on the post-Rx side nulling received interference power.

[0087] The Rx node may send feedback to one or more Tx nodes that create interference above a predetermined threshold interference. The feedback may include the beam ID per transmitter.

[0088] The Rx node may inform each Tx node after interference measurement scheduling allocated for the node pair. The Tx side nulling may be carried out at the end of the measurement period allocated to the node pair. To accommodate the Tx side nulling, the interference measurement campaign may assign one or more optional periods at the end of each node pair's measurement slot. The node pair may request the measurement campaign in the network to be updated accordingly, which is informed to the central node. The central node may update the measurement campaign and/or may send the updated measurement scheduling to the nodes.

[0089] In the Tx side nulling signaling, the Tx node may (e.g. , initially) assign the nulling direction based on the Tx beam ID.

[0090] Where higher Tx side nulling resolution is needed, the Tx node may transmit narrower beams that sweep the angles of one or more interfering Tx beams. For example, assuming the one or more interfering Tx beams have the width of θτ, the K pilot beams have width of Θτ/Κ each. The Tx node may transmit the pilot beams (e.g. , sequentially) where the Rx beam measures the interference (e.g. , using its interfered Rx beam). The Rx node may send the feedback of pilot ID to the Tx node, based on the measured interference.

[0091] Based on the determined nulling direction, the Tx node may allocate a null at the corresponding AoD. The depth and width of the null may be determined based on the INR value feedback received from the Rx node. The INR value feedback may be determined, for example, during the measurement campaign.

[0092] The Tx node may sweep the beams with the allocated null(s) within an AoD range

(e.g. , to optimize the nulling direction and/or shape). The Rx node may measure the interference value corresponding to each transmission. The transmission that gives the minimum INR value at the Rx beam may be indicated via feedback to the transmitter. The feedback to the transmitter may identify the high resolution nulling direction from the Tx node's perspective.

[0093] A receive and/or a transmit beam may be adjusted based on a signal frequency.

Antenna beamforming and/or beam adjustment at the transmit and/or receive antennas may alter the frequency response of the processed signal. For example, the frequency response of the processed signal may be altered as a function of the signal's operating frequency, e.g. , carrier frequency and/or bandwidth. The change in the signal's frequency response due to beamforming operation may be different at each frequency value (e.g. , due to the underlying transmit and/or receive array vectors). A beamforming, or beam shape and its corresponding transmit and/or receive antenna array vectors, that are operating under one frequency band may have a different beam shape under another frequency band (e.g. , even with the same antenna array vectors). A beamforming or beam shape with different shapes based on an operating frequency may result in different null AoA and/or AoD for different frequency bands. For large signal bandwidths, such as mmW systems, frequency dependent and/or dynamic beamforming may be performed.

[0094] The receive beamforming may be constructed considering the bandpass nature of the transmitted signals and one or more of the following.

[0095] A frequency band of a transmitted signal may be split into m parts, where m may be an arbitrary number. In an example, m may be equal to 3 (e.g. , m = 3). In this example, si = s[fo, fc - fW], s2 = s[fc - fW, fc + fW], s3 = s[fc + fW, fE] may be provided where si, s2, and s3 corresponding to 3 non-overlapping segments (e.g. , in frequency) of the signal, fo may represent the lowest frequency of the signal s, fc may represent the carrier frequency, fE may represent the highest frequency of the signal s, and fW may represent the pre-determined frequency window used in beamforming operation.

[0096] The receiver AoA estimation campaign, described herein, may be carried out at the lower end of the transmit signal frequency band, e.g. , [fo, fc - fW]. For example, the receiver may apply a band-pass filter within the transmit signal frequency band [fo, fc - fW]. After application of the band-pass filter, the received signal may include null components for one or more other frequencies. The receiver may employ measurement and/or AoA estimation, as described herein, by using a predetermined receive beam shape with nulls at identified angles, e.g. , as shown in FIG. 5. The AoA angle with a minimum aggregate received signal power may be identified and/or recorded. In examples, the receiver and/or transmitter may coordinate the frequency band for the measurement campaign. The transmitter may transmit a pilot signal with one or more frequencies, e.g., [fo, fc - fW].

[0097] The receiver may perform AoA arrival measurement corresponding to a frequency band, e.g. , [fc - fW, fc + fW]. The frequency band may be selected via post processing band pass filtering and/or the transmitter transmitting a signal that indicates the frequency band. AoA results for the frequency band may be determined.

[0098] The measurement campaign may include a last portion of the frequency band.

The receiver may apply band-pass filtering corresponding to the frequency band, e.g. , [fc + fW, ffi]. Applying band-pass filtering may nullify one or more remaining frequency responses. An AoA measurement campaign, as described herein, may be performed to identify one or more signal reception angles with the highest power.

[0099] In the example using k = 3, three different measurement results may be available.

Each of the three different measurement results may correspond to a different frequency band, e.g. , {[fo, fc - fW], [fc - fW, fc + fW], [fc + fW, ffi]}, and AoA_setl, AoA_set2, and AoA_set3. The receiver may form a receive beam based on the AoA sets. For example, the receiver may include one or more (e.g., all) AoA sets in receive beamforming. In other example, the receiver may selectively include a subset (e.g., one or more) of the AoA sets, for example, based on the operating frequency of the received signal.

[0100] Interference measurement campaigns may be updated based on nulling employed at the nodes.

[0101] An interference measurement campaign may include one or more of the following. The measuring Rx node may identify the interfering ray AoAs with high power. One or more high resolution AoAs may be determined, for example, by placing nulls.

[0102] When the interfering AoAs, null orientations, and/or characteristics (e.g. , width and/or depth) are identified, Rx receive beams updated with these nulls may be used in the measurement campaign.

[0103] A central controller based backhaul measurements campaign may be provided.

During network set up, each node (e.g. , as shown in FIG. 3) may perform initialization. Each node may be associated with a unique cell ID that may be used to identify transmissions, rays, and/or the like by the other nodes in the system. A node may start searching for the unique cell IDs at the start up provided, for example, that at least the node(s) gateway to the communication network are set up. An association matrix may be created when the new node detects and/or identifies its neighbors, and/or associates to the central controller entity.

[0104] When the association matrix is generated that identifies AoAs of the reception from one or more (e.g. , all) neighboring nodes to one or more (e.g., all) other nodes, the central controller entity may collect measurements and/or update the association matrix at each node periodically. The measurement campaigns may be initiated based on an event such as a sudden drop in network performance and/or node performance. During the measurement process, the central controller entity may create overlapping or non-overlapping clusters to execute one or more measurement campaigns (e.g. , simultaneously) to expedite the measurement process. In each cluster, the nodes may take turns to transmit pilot sequences while other nodes (e.g. , non- transmitting nodes) may perform measurements to determine associated matrix parameters such as AoAs, signal strengths, and/or the like.

[0105] The central controller entity may perform route set up by using the interference matrix created among backhaul links for traffic management. The route set up information may be exchanged with the neighboring nodes (e.g. , that may be affected by the route assignments). For example in a network setting, Node 1 may be transmitting to Node 2, and Node 3 may be transmitting to Node 4 simultaneously. If the interference matrix identifies that Nodes 1 and 3 interfere with Nodes 4 and 2, Node 2 may place a null in the direction of Node 3, and/or Node 4 may place a null in the direction of Node 1.

[0106] Nulling may be initiated by letting effected neighboring nodes to be informed by the central controller entity when a particular transmission(s) takes place (e.g. , so that the nodes being effected may put null at the direction of the interferer).

[0107] Null initialization may not require the scheduling information for a particular transmission(s). In scheduling unaware nulling, a node may place nulls at the interfering rays if the node can differentiate AoA estimates between the desired and the interfering nodes.

[0108] The central controller may initiate transmit domain nulling (e.g., to suppress the interference on particular AoD(s) that effects network performance).

[0109] A sub-controller based access measurements campaign may be provided. In the joint access and backhaul architecture (e.g., as shown in FIG. 3), one or more sub-controllers may interface access and backhaul links at each node. The generated interference matrix relevant to the backhaul links may be updated and sent to the sub-controllers (e.g. , regularly). Each of the one or more sub-controllers may expand the interference matrix to include one or more WTRUs and/or neighboring nodes associated with the sub-controller (e.g., to enable AoA estimates and/or null creation campaigns among the associated WTRUs and/or the neighboring links). For example, a WTRU in reception mode may create one or more nulls against its neighboring nodes to suppress interference.

[0110] The sub-controller may set up periodic and/or event driven AoA measurement campaigns among its associated WTRUs and/or neighbor nodes.

[0111] In a scheduling aware approach, a WTRU may be informed about the scheduling activities of interfering nodes and/or the other interfering WTRUs (e.g. , to enable dynamic nulling against them). The network may request nulling at the transmitting WTRUs and/or the neighboring node(s) on particular AoD(s) to further suppress the interference.

[0112] In a scheduling unaware approach, a WTRU (e.g., each WTRU) may determine its interferers' AoA and/or may create dynamic nulling against them. The Rx nodes may dynamically measure the interfering AoAs without a schedule, or with the information of a one- hop neighbor. The Rx node(s) or the WTRU(s) may utilize the unique ID to differentiate the desired and/or the interfering rays and their respective AoAs.

[0113] FIG. 12A is a diagram of an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc. , to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single- carrier FDMA (SC-FDMA), and the like.

[0114] As shown in FIG. 12A, the communications system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, and/or 102d (which generally or collectively may be referred to as WTRU 102), a radio access network (RAN) 103/104/105, a core network 106/107/109, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d may be configured to transmit and/or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, consumer electronics, and the like.

[0115] The communications systems 100 may also include a base station 114a and a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the core network 106/107/109, the Internet 110, and/or the networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

[0116] The base station 114a may be part of the RAN 103/104/105, which may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and/or the base station 114b may be configured to transmit and/or receive wireless signals within a particular geographic region, which may be referred to as a cell (not shown). The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, e.g., one for each sector of the cell. In another embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and, therefore, may utilize multiple transceivers for each sector of the cell.

[0117] The base stations 114a, 114b may communicate with one or more of the WTRUs

102a, 102b, 102c, 102d over an air interface 115/116/117, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 115/116/117 may be established using any suitable radio access technology (RAT).

[0118] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 103/104/105 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115/116/117 using wideband CDMA (WCDMA).

WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink Packet Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

[0119] In another embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 115/116/117 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE- A).

[0120] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.16 (e.g. , Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 IX, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0121] The base station 114b in FIG. 12A may be a wireless router, Home Node B,

Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In another embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g. , WCDMA, CDMA2000, GSM, LTE, LTE- A, etc.) to establish a picocell or femtocell. As shown in FIG. 12A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the core network 106/107/109.

[0122] The RAN 103/104/105 may be in communication with the core network

106/107/109, which may be any type of network configured to provide voice, data, applications, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. For example, the core network 106/107/109 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc. , and/or perform high-level security functions, such as user authentication. Although not shown in FIG. 12A, it will be appreciated that the RAN 103/104/105 and/or the core network 106/107/109 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 103/104/105 or a different RAT. For example, in addition to being connected to the RAN 103/104/105, which may be utilizing an E-UTRA radio technology, the core network 106/107/109 may also be in communication with another RAN (not shown) employing a GSM radio technology.

[0123] The core network 106/107/109 may also serve as a gateway for the WTRUs 102a,

102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or other networks 112. The PSTN 108 may include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and the internet protocol (IP) in the TCP/IP internet protocol suite. The networks 112 may include wired or wireless

communications networks owned and/or operated by other service providers. For example, the networks 112 may include another core network connected to one or more RANs, which may employ the same RAT as the RAN 103/104/105 or a different RAT.

[0124] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system

100 may include multi-mode capabilities, e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links. For example, the WTRU 102c shown in FIG. 12A may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0125] FIG. 12B is a system diagram of an example WTRU 102. As shown in FIG. 12B, the WTRU 102 may include a processor 118, a transceiver 120, a transmit/receive element 122, a speaker/microphone 124, a keypad 126, a display/touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and other peripherals 138. It will be appreciated that the WTRU 102 may include any subcombination of the foregoing elements while remaining consistent with an embodiment. Also, embodiments contemplate that the base stations 114a and 114b, and/or the nodes that base stations 114a and 114b may represent, such as but not limited to transceiver station (BTS), a Node-B, a site controller, an access point (AP), a home node-B, an evolved home node-B (eNodeB), a home evolved node-B (HeNB), a home evolved node-B gateway, and proxy nodes, among others, may include some or all of the elements depicted in FIG. 12B and described herein.

[0126] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of

microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Array (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit/receive element 122. While FIG. 12B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0127] The transmit/receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g. , the base station 114a) over the air interface

115/116/117. For example, in one embodiment, the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. In another embodiment, the transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit/receive element 122 may be configured to transmit and receive both RF and light signals. It will be appreciated that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

[0128] In addition, although the transmit/receive element 122 is depicted in FIG. 12B as a single element, the WTRU 102 may include any number of transmit/receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 115/116/117.

[0129] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit/receive element 122 and to demodulate the signals that are received by the transmit/receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, for example.

[0130] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128 (e.g. , a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132. The non-removable memory 130 may include random- access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0131] The processor 118 may receive power from the power source 134, and may be configured to distribute and/or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0132] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g. , longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 115/116/117 from a base station (e.g., base stations 114a, 114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0133] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and/or hardware modules that provide additional features, functionality and/or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, and the like.

[0134] FIG. 12C is a system diagram of the RAN 103 and the core network 106 according to an embodiment. As noted above, the RAN 103 may employ a UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 115. The RAN 103 may also be in communication with the core network 106. As shown in FIG. 12C, the RAN 103 may include Node-Bs 140a, 140b, 140c, which may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 115. The Node-Bs 140a, 140b, 140c may each be associated with a particular cell (not shown) within the RAN 103. The RAN 103 may also include RNCs 142a, 142b. It will be appreciated that the RAN 103 may include any number of Node-Bs and RNCs while remaining consistent with an embodiment.

[0135] As shown in FIG. 12C, the Node-Bs 140a, 140b may be in communication with the RNC 142a. Additionally, the Node-B 140c may be in communication with the RNC142b. The Node-Bs 140a, 140b, 140c may communicate with the respective RNCs 142a, 142b via an Iub interface. The RNCs 142a, 142b may be in communication with one another via an Iur interface. Each of the RNCs 142a, 142b may be configured to control the respective Node-Bs 140a, 140b, 140c to which it is connected. In addition, each of the RNCs 142a, 142b may be configured to carry out or support other functionality, such as outer loop power control, load control, admission control, packet scheduling, handover control, macrodiversity, security functions, data encryption, and the like.

[0136] The core network 106 shown in FIG. 12C may include a media gateway (MGW)

144, a mobile switching center (MSC) 146, a serving GPRS support node (SGSN) 148, and/or a gateway GPRS support node (GGSN) 150. While each of the foregoing elements are depicted as part of the core network 106, it will be appreciated that any one of these elements may be owned and/or operated by an entity other than the core network operator.

[0137] The RNC 142a in the RAN 103 may be connected to the MSC 146 in the core network 106 via an IuCS interface. The MSC 146 may be connected to the MGW 144. The MSC 146 and the MGW 144 may provide the WTRUs 102a, 102b, 102c with access to circuit- switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices.

[0138] The RNC 142a in the RAN 103 may also be connected to the SGSN 148 in the core network 106 via an IuPS interface. The SGSN 148 may be connected to the GGSN 150. The SGSN 148 and the GGSN 150 may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between and the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0139] As noted above, the core network 106 may also be connected to the networks 112, which may include other wired or wireless networks that are owned and/or operated by other service providers.

[0140] FIG. 12D is a system diagram of the RAN 104 and the core network 107 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the core network 107. [0141] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a.

[0142] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell

(not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the uplink and/or downlink, and the like. As shown in FIG. 12D, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0143] The core network 107 shown in FIG. 12D may include a mobility management gateway (MME) 162, a serving gateway 164, and a packet data network (PDN) gateway 166. While each of the foregoing elements are depicted as part of the core network 107, it will be appreciated that any one of these elements may be owned and/or operated by an entity other than the core network operator.

[0144] The MME 162 may be connected to each of the eNode-Bs 160a, 160b, 160c in the

RAN 104 via an SI interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer

activation/deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may also provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM or WCDMA.

[0145] The serving gateway 164 may be connected to each of the eNode-Bs 160a, 160b,

160c in the RAN 104 via the SI interface. The serving gateway 164 may generally route and forward user data packets to/from the WTRUs 102a, 102b, 102c. The serving gateway 164 may also perform other functions, such as anchoring user planes during inter-eNode B handovers, triggering paging when downlink data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0146] The serving gateway 164 may also be connected to the PDN gateway 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. [0147] The core network 107 may facilitate communications with other networks. For example, the core network 107 may provide the WTRUs 102a, 102b, 102c with access to circuit- switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the core network 107 may include, or may communicate with, an IP gateway (e.g. , an IP multimedia subsystem (IMS) server) that serves as an interface between the core network 107 and the PSTN 108. In addition, the core network 107 may provide the WTRUs 102a, 102b, 102c with access to the networks 112, which may include other wired or wireless networks that are owned and/or operated by other service providers.

[0148] FIG. 12E is a system diagram of the RAN 105 and the core network 109 according to an embodiment. The RAN 105 may be an access service network (ASN) that employs IEEE 802.16 radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 117. As will be further discussed below, the communication links between the different functional entities of the WTRUs 102a, 102b, 102c, the RAN 105, and the core network 109 may be defined as reference points.

[0149] As shown in FIG. 12E, the RAN 105 may include base stations 180a, 180b, 180c, and an ASN gateway 182, though it will be appreciated that the RAN 105 may include any number of base stations and ASN gateways while remaining consistent with an embodiment. The base stations 180a, 180b, 180c may each be associated with a particular cell (not shown) in the RAN 105 and may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 117. In one embodiment, the base stations 180a, 180b, 180c may implement MIMO technology. Thus, the base station 180a, for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a. The base stations 180a, 180b, 180c may also provide mobility management functions, such as handoff triggering, tunnel establishment, radio resource management, traffic classification, quality of service (QoS) policy enforcement, and the like. The ASN gateway 182 may serve as a traffic aggregation point and may be responsible for paging, caching of subscriber profiles, routing to the core network 109, and the like.

[0150] The air interface 117 between the WTRUs 102a, 102b, 102c and the RAN 105 may be defined as an Rl reference point that implements the IEEE 802.16 specification. In addition, each of the WTRUs 102a, 102b, 102c may establish a logical interface (not shown) with the core network 109. The logical interface between the WTRUs 102a, 102b, 102c and the core network 109 may be defined as an R2 reference point, which may be used for

authentication, authorization, IP host configuration management, and/or mobility management. [0151] The communication link between each of the base stations 180a, 180b, 180c may be defined as an R8 reference point that includes protocols for facilitating WTRU handovers and the transfer of data between base stations. The communication link between the base stations 180a, 180b, 180c and the ASN gateway 182 may be defined as an R6 reference point. The R6 reference point may include protocols for facilitating mobility management based on mobility events associated with each of the WTRUs 102a, 102b, 102c.

[0152] As shown in FIG. 12E, the RAN 105 may be connected to the core network 109.

The communication link between the RAN 105 and the core network 109 may defined as an R3 reference point that includes protocols for facilitating data transfer and mobility management capabilities, for example. The core network 109 may include a mobile IP home agent (MIP-HA) 184, an authentication, authorization, accounting (AAA) server 186, and a gateway 188. While each of the foregoing elements are depicted as part of the core network 109, it will be appreciated that any one of these elements may be owned and/or operated by an entity other than the core network operator.

[0153] The MIP-HA may be responsible for IP address management, and may enable the

WTRUs 102a, 102b, 102c to roam between different ASNs and/or different core networks. The MIP-HA 184 may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The AAA server 186 may be responsible for user authentication and for supporting user services. The gateway 188 may facilitate interworking with other networks. For example, the gateway 188 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. In addition, the gateway 188 may provide the WTRUs 102a, 102b, 102c with access to the networks 112, which may include other wired or wireless networks that are owned and/or operated by other service providers.

[0154] Although not shown in FIG. 12E, it will be appreciated that the RAN 105 may be connected to other ASNs and the core network 109 may be connected to other core networks. The communication link between the RAN 105 the other ASNs may be defined as an R4 reference point, which may include protocols for coordinating the mobility of the WTRUs 102a, 102b, 102c between the RAN 105 and the other ASNs. The communication link between the core network 109 and the other core networks may be defined as an R5 reference, which may include protocols for facilitating interworking between home core networks and visited core networks. [0155] FIG. 12F illustrates exemplary wireless local area network (WLAN) devices.

One or more of the devices may be used to implement one or more of the features described herein. The WLAN may include, but is not limited to, access point (AP) 152, station (STA) 156, and STA 158. STA 156 and 158 may be associated with AP 152. The WLAN may be configured to implement one or more protocols of the IEEE 802.11 communication standard, which may include a channel access scheme, such as DSSS, OFDM, OFDMA, etc. A WLAN may operate in a mode, e.g., an infrastructure mode, an ad-hoc mode, etc.

[0156] A WLAN operating in an infrastructure mode may comprise one or more APs communicating with one or more associated STAs. An AP and STA(s) associated with the AP may comprise a basic service set (BSS). For example, AP 152, STA 156, and STA 158 may comprise BSS 196. An extended service set (ESS) may comprise one or more APs (with one or more BSSs) and STA(s) associated with the APs. An AP may have access to, and/or interface to, distribution system (DS) 192, which may be wired and/or wireless and may carry traffic to and/or from the AP. Traffic to a STA in the WLAN originating from outside the WLAN may be received at an AP in the WLAN, which may send the traffic to the STA in the WLAN. Traffic originating from a STA in the WLAN to a destination outside the WLAN, e.g. , to server 194, may be sent to an AP in the WLAN, which may send the traffic to the destination, e.g. , via DS 192 to network 190 to be sent to server 194. Traffic between STAs within the WLAN may be sent through one or more APs. For example, a source STA (e.g. , STA 156) may have traffic intended for a destination STA (e.g. , STA 158). STA 156 may send the traffic to AP 152, and, AP 152 may send the traffic to STA 158.

[0157] A WLAN may operate in an ad-hoc mode. The ad-hoc mode WLAN may be referred to as independent basic service set (IBBS). In an ad-hoc mode WLAN, the STAs may communicate directly with each other (e.g., STA 156 may communicate with STA 158 without such communication being routed through an AP).

[0158] IEEE 802.11 devices (e.g. , IEEE 802.11 APs in a BSS) may use beacon frames to announce the existence of a WLAN network. An AP, such as AP 102, may transmit a beacon on a channel, e.g., a fixed channel, such as a primary channel. A STA may use a channel, such as the primary channel, to establish a connection with an AP.

[0159] The processes described above may be implemented in a computer program, software, and/or firmware incorporated in a computer-readable medium for execution by a computer and/or processor. Examples of computer-readable media include, but are not limited to, electronic signals (transmitted over wired and/or wireless connections) and/or computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as, but not limited to, internal hard disks and removable disks, magneto-optical media, and/or optical media such as CD-ROM disks, and/or digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, terminal, base station, RNC, and/or any host computer.

Claims

CLAIMS What is Claimed:

1. A receiving node (RN) comprising:

a plurality of antennas or antenna elements; and

a processor, wherein the RN is configured to:

receive a first beamformed signal from a first transmitting node (TN) and a second beamformed signal from a second TN;

perform a first measurement on the first beamformed signal and a second measurement on the second beamformed signal;

generate or receive a first feedback information based on the first measurement and a second feedback information based on the second measurement;

determine or receive an indication that at least one of the first measurement or the second measurement is above a threshold interference level;

receive a first scheduled transmission information associated with the first TN and a second scheduled transmission information associated with the second TN;

configure a first dynamic null associated with the first scheduled transmission information and a second dynamic null associated with the second scheduled transmission information; and

send a first signal that comprises the first dynamic null towards the first TN and a second signal that comprises the second dynamic null towards the second TN.

2. The RN of claim 1, wherein the RN configures the first dynamic null based on the first measurement and the first scheduled transmission information, and the second dynamic null based on the second measurement and the second scheduled transmission.

3. The RN of claim 1, wherein the first scheduled transmission information comprises a first indication of a first time that the first TN is scheduled to transmit, and the second scheduled transmission information comprises a second indication of a second time that the second TN is scheduled to transmit.

4. The RN of claim 1, wherein the first signal that comprises the first dynamic null and the second signal that comprises the second dynamic null are configured to have at least one of dynamically changing main lobe, null depth, or null width.

5. The RN of claim 1, wherein the RN is further configured to send the first measurement on the first beamformed signal and the second measurement on the second beamformed signal to a central controller.

6. The RN of claim 5, wherein the RN receives an interference matrix from the central controller.

7. The RN of claim 6, wherein the RN configures the first dynamic null based on the interference matrix and the first scheduled transmission, and the second dynamic null based on the interference matrix and the second scheduled transmission.

8. The RN of claim 1, wherein the first signal that comprises the first dynamic null and the second signal that comprises the second dynamic null are sent via analog beamforming.

9. The RN of claim 1, wherein the first beamformed signal further comprises a first beam identification (ID) associated with the first TN, and the second beamformed signal further comprises a second beam ID associated with the second TN.

10. The RN of claim 9, wherein the first dynamic null is configured based on at least one of the first beam ID or the first scheduled transmission information, and the second dynamic null is configured based on at least one of the second beam ID or the second scheduled transmission information.

11. A method comprising:

receiving a first beamformed signal from a first transmitting node (TN) and a second beamformed signal from a second TN;

performing a first measurement on the first beamformed signal and a second

measurement on the second beamformed signal;

generating or receiving a first feedback information based on the first measurement and a second feedback information based on the second measurement;

determining or receiving an indication that at least one of the first measurement or the second measurement is above a threshold interference level; receiving a first scheduled transmission information associated with the first TN and a second scheduled transmission information associated with the second TN;

configuring a first dynamic null associated with the first scheduled transmission information and a second dynamic null associated with the second scheduled transmission information; and

sending a first signal that comprises the first dynamic null towards the first TN and a second signal that comprises the second dynamic null towards the second TN.

12. The method of claim 11, wherein the RN configures the first dynamic null based on the first measurement and the first scheduled transmission information, and the second dynamic null based on the second measurement and the second scheduled transmission.

13. The method of claim 11, wherein the first scheduled transmission information comprises a first indication of a first time that the first TN is scheduled to transmit, and the second scheduled transmission information comprises a second indication of a second time that the second TN is scheduled to transmit.

14. The method of claim 11, wherein the first signal that comprises the first dynamic null and the second signal that comprises the second dynamic null are configured to have at least one of dynamically changing main lobe, null depth, or null width.

15. The method of claim 11 wherein the RN is further configured to send the first measurement on the first beamformed signal and the second measurement on the second beamformed signal to a central controller.

16. The method of claim 15, wherein the RN receives an interference matrix from the central controller.

17. The method of claim 16, wherein the RN configures the first dynamic null based on the interference matrix and the first scheduled transmission, and the second dynamic null based on the interference matrix and the second scheduled transmission.

18. The method of claim 11, wherein the first signal that comprises the first dynamic null and the second signal that comprises the second dynamic null are sent via analog beamforming.

19. The method of claim 11, wherein the first beamformed signal further comprises beam identification (ID) associated with the first TN, and the second beamformed signal further comprises a second beam ID associated with the second TN.

20. The method of claim 19, wherein the first dynamic null is configured based on at least one of the first beam ID or the first scheduled transmission information, and the second dynamic null is configured based on at least one of the second beam ID or the second scheduled transmission information.