HK1221561B - Multiple-input multiple-output cellular network communications - Google Patents

Description

MIMO cellular network communications

Related applications

This application claims the benefit of and is incorporated herein by reference in its entirety by reference to U.S. Provisional Patent Application Serial No. 61/821,635, filed May 9, 2013, having Attorney Docket No. P56618Z.

Background Art

The increasing use of mobile devices such as smartphones and tablets, along with the increasing number of wireless services these devices provide, such as streaming video, has increased the data load and throughput requirements of wireless networks. To handle the increasing number of wireless services provided by a growing number of users, various multi-antenna technologies can be employed in wireless network environments to meet the growing data and throughput requirements.

One multi-antenna technology that meets ever-increasing data and throughput demands is beamforming. Beamforming is a signal processing technique used to control the direction of reception or transmission of signals on a transducer array. While conventional multi-antenna technologies such as beamforming offer improved receiver and/or transmission gain or loss compared to omnidirectional reception, they are inadequate for dynamic antenna systems.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the present disclosure will become apparent from the following detailed description, which illustrates features of the present disclosure by way of example taken in conjunction with the accompanying drawings, in which:

FIG1 illustrates a 2D antenna array according to an example;

FIG2 illustrates a 2D antenna with cross-polarized antennas according to an example;

FIG3A illustrates a cellular network including an eNB having a one-dimensional antenna array according to an example;

FIG3B illustrates another cellular network including an eNB having a one-dimensional antenna array according to an example;

FIG4A illustrates creating a UE-dedicated cell for multiple UEs according to an example;

FIG4B illustrates creating another UE-specific cell for multiple UEs according to an example;

FIG5 illustrates creating a UE-dedicated cell for multiple UEs according to an example;

FIG6 illustrates different antenna array configurations for a 2D antenna array according to an example;

FIG7 shows a table of combined array gains according to an example, where each antenna port has the same electrical tilt and a different number of antenna elements;

FIG8 illustrates functionality of computer circuitry of an eNB operable to perform beamforming using multiple-input multiple-output (MIMO) in a cellular network, according to an example;

FIG9 illustrates functionality of computer circuitry operable at a UE for communicating in a MIMO cellular network, according to an example;

FIG10 shows a flow chart of a method for beamforming in a multiple-input multiple-output (MIMO) cellular network according to an example; and

FIG11 shows a schematic diagram of a UE according to an example.

Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that the scope of the invention is not limited thereby.

DETAILED DESCRIPTION

Before disclosing and describing the present invention, it should be understood that the present invention is not limited to the specific structures, process steps or materials disclosed herein, but encompasses equivalents known to those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing specific examples only and is not intended to limit the present invention. The same reference numerals in different figures represent the same elements. The numbers provided in the flow charts and the processes provided in the explanatory steps are for clarity and do not necessarily indicate a specific order or sequence.

Multiple-antenna technology can be used to achieve advantages such as diversity gain, array gain, and spatial multiplexing gain. Multiple-input, multiple-output (MIMO) systems use multiple antennas at the transmitter and/or receiver to improve communication performance. Conventional MIMO systems can perform beamforming in two dimensions. The beam coverage of a transmission point, such as an enhanced Node B (eNB) or base station in a cellular network, can be dynamically shaped by beamforming multiple antennas at the transmission point. By adapting the beam coverage, the eNB can optimize signal quality and handover. In conventional MIMO systems, user equipment (UE) using reference signals (RS) has a fixed vertical transmission. Because the reference signals have a fixed vertical transmission, each RS port is invisible to vertical beamforming, and the UE cannot pass information to enable vertical precoding. In traditional LTE systems, the UE measures reference signal received power (RSRP) and/or reference signal received quality (RSRQ) to help the eNB make cell association decisions. RSRP is the linear average of the power distribution of a resource element carrying a reference signal for a specific cell within a comparable measurement frequency bandwidth. In one embodiment, the reference point for RSRP measurement can be the UE's antenna connector.

Dynamic antenna systems, such as three-dimensional (3D) MIMO or full-dimensional (FD) MIMO, can use a two-dimensional (2D) antenna array to perform beamforming in the horizontal and vertical dimensions. FIG1 shows a 2D antenna array 100 having N columns and each column having M antenna elements 110, where N and M are defined numbers. In this example, each row is a uniform linear array with N antenna elements 110. FIG2 shows a 2D antenna array 200 having N columns and each column having M antenna elements 210. Each column has a cross-polarized antenna with 2N antennas. The example of FIG1 is not intended to be limiting. Other two-dimensional antenna array configurations can be used to perform 3D or FD MIMO. Throughout this application, the terms 3D MIMO and FD MIMO are used synonymously.

In one embodiment, a 3D MIMO or FD MIMO system performs beamforming in a closed-loop system. 3D MIMO or FD MIMO beamforming in the horizontal or vertical dimensions uses multiple antennas in an antenna array. In one embodiment, 3D MIMO or FD MIMO beamforming can be performed at an enhanced Node B (eNB) or base station in a cellular network, allowing the eNB or base station's beam coverage to be dynamically shaped in the X, Y, and Z axes. In one example, vertical beamforming or antenna tilt can expand or contract the beam coverage angle in the vertical dimension. In another example, horizontal beamforming can change the beam coverage angle in the horizontal dimension. By adjusting the beam coverage, the eNB can optimize signal quality and handover. A cellular communication system can consist of one or more cellular network nodes or cells and one or more Institute of Electrical and Electronics Engineers (IEEE) 802.11-2012-compliant access points. In one embodiment, the one or more cellular networks may be a Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) Rel. 8, 9, 10, 11, or 12 network and/or an IEEE 802.16p, 802.16n, 802.16m-2011, 802.16h-2010, 802.16j-2009, or 802.16-2009 configuration network.

For dynamic antenna systems, the eNB can make multiple antenna ports visible to the UE by configuring a multi-port channel state information reference signal (CSI-RS) pattern to the UE. In one embodiment, the CSI-RS pattern can convey vertical channel information, such as the channel of a column of antennas (antenna columns) in a 2D antenna array. In another embodiment, the CSI-RS pattern can convey horizontal channel information. In one embodiment, each CSI-RS horizontal pattern can be configured to assume that the vertical value has been determined. When the CSI-RS pattern has been determined, the UE can perform CSI-based measurements. The CSI-based measurement results can include a channel quality indication (CQI), a precoding matrix indicator (PMI), and a rank indicator. In one embodiment, after the UE has performed CSI-based measurements, the UE can send data to other devices in the cellular network.

In one embodiment, the UE can use closed-loop beamforming feedback to report beamformed RSRP from the multi-port CSI-RS pattern. In one embodiment, the closed-loop system relies on more than one antenna port. For example, if there are two antenna ports and 8 antennas, the closed-loop system can perform 2×8 measurements.

In one embodiment, for closed-loop beamforming, the UE assumes what is a single codebook. For a CSI-RS system, there can be multiple assumed RSRP reports. The UE can pass the strongest assumed RSRP measurement result to the eNB. In one embodiment, the closed-loop beamforming operation uses transmission mode 4 (TM4). In one embodiment of the closed-loop system, the UE can report CSI to the eNB and the eNB applies a precoder to the CSI, thereby resulting in high spectral efficiency. In one embodiment, the eNB configures a multi-port CSI-RS pattern to the UE to perform RSRP and/or RSRQ measurements, and RSRP and/or RSRQ are measured by the UE using a selected precoder. In one embodiment, the precoder is known to both the eNB and the UE through the codebook. The eNB can use closed-loop beamforming techniques based on feedback from the UE to form a virtual UE-dedicated cell. That is, the eNB can use multiple RSRP reports from one or more UEs to form a virtual cell.

Figure 3A illustrates a cellular network including an eNB with a one-dimensional antenna array 302a. The one-dimensional antenna array 302a further comprises antenna elements 304. A selected number of antenna elements 304a can be associated with one or more antenna ports. The number of antenna elements in the antenna array can vary. For example, antenna columns in the antenna array can include two, four, eight, or more antenna elements. Figure 3A illustrates a cellular network and its corresponding coverage area 308a, including a base station or eNB 306a. Figure 3A also illustrates horizontal directions that can be formed by the antenna array 302a for two-dimensional beamforming of the eNB beam. The horizontal directions provided by the antenna array 302a are illustrated by the different beam direction geometries 310a, 312a, and 314a.

FIG3B illustrates a cellular network including an eNB with a two-dimensional (2D) antenna array 302b. The 2D antenna array 302b includes a set of antenna elements 304b. In one embodiment, each antenna element 304b is mapped to a different antenna port. In one example, MIMO in a 3GPP LTE network may be configured to support only eight antenna ports. In this example, where the antenna array 302b is mapped to 64 antenna ports, such as 64 antenna elements 304b, the number of antenna ports in the antenna array 302b exceeds the maximum eight antenna ports that the MIMO is configured to support.

In one embodiment, antenna elements 304b can be combined into virtual antennas corresponding to a single antenna port. For example, each row or column can correspond to a single virtual antenna port, such as antenna column 316. In another embodiment, a virtual antenna port can be composed of any combination of antenna elements. Figure 3B illustrates a cellular network and its corresponding coverage area 308b, which includes a base station or eNB 306b. Figure 3B also illustrates an example of a vertical direction in which antenna array 302b can form a beam for an eNB to provide three-dimensional or full-dimensional beamforming. The vertical direction provided by antenna array 302b is illustrated by different beam direction geometries 318 and 320. In another embodiment, antenna array 302b can adjust the horizontal direction of the eNB's beam. Both the vertical and horizontal directions can be used to change the width or height of the beam.

Figures 4A and 4B illustrate creating UE-specific cells for multiple UEs. Figure 4A shows a cellular network including an eNB 406a, which has cellular coverage 408a. The eNB may include a 2D antenna array configured to provide coverage for multiple UEs 422a and 424a. The 2D antenna array may be employed at the eNB to configure beam configurations. Example beam configurations include 418a and 420a. Beam configuration 418a is targeted at the area where UE 422a is located. Beam configuration 418a is configured to provide optimal power and signal quality to UE 422a. Beam configuration 420a is targeted at the area where UE 424a is located. However, UE 424a is located at the edge of beam configuration 420a. Because UE 420a is at the edge of beam configuration 424a, UE 424a may receive suboptimal power and signal quality.

In one example, UEs 422a and 424a can be configured to receive CSI-RS from an eNB. The CSI-RS can be configured to provide information for multiple vertical beam configurations, such as beam configuration 418a and beam configuration 420a in FIG. 4A . In this example, UEs 422a and 424a can transmit feedback reports to eNB 406a to allow the eNB to create a UE reference cell based on the feedback reports received from the UEs. The feedback reports can include RSRP messages and/or RSRQ messages.

FIG4B illustrates a UE reference cell created by eNB 406b based on feedback reports from UEs 422b and 424b and used for UEs 422a and 424b. In one embodiment, the phase of one or more antenna elements or antenna arrays may be adjusted to provide vertical and/or horizontal motion of the beam relative to UEs 422b and 424b. The motion of the beam relative to the location of the UEs may be used to provide optimal cellular power and signal quality for UEs 422a and 424b. In one embodiment, an iterative process may be used to construct UE reference cells 422b and 424b, whereby one or more UEs within the cellular network may provide feedback reports to the eNB. The iterative process may continue until one or more configurations for the associated UEs are optimized.

Similar to FIG4 , FIG5 illustrates UE-specific cells and group-UE-specific cells for multiple UEs. FIG5 illustrates multiple UEs 522, 524, 526, 528, 530, and 532 within a cellular network. FIG5 illustrates that eNB 506 can create a UE-specific cell for a single UE and/or create a group-UE-specific cell for multiple UEs, such as UEs 524 and 526 or UEs 530 and 532. FIG5 is similar to FIG4 in other respects.

Figure 6 illustrates different antenna array configurations 648a, 648b, and 648c for a 2D antenna array used by eNB 606. In one embodiment, the eNB can adjust the antenna array configuration by changing the number of antenna ports or beam weights based on feedback reports from one or more UEs. In one embodiment, a virtual antenna may correspond to an antenna port. In another embodiment, multiple antenna elements may be combined to form a virtual antenna port or antenna port. A virtual antenna port or multiple antenna elements of an antenna port may appear to the UE as a single antenna. Any combination of antenna elements may be combined to form a virtual antenna port or antenna port. In one example, 2D antenna array 648a includes antenna ports 650a-664a, e.g., _X1 - _X8 . Antenna ports 650a-664a are used to form beam configuration 648a. Beam configuration 648a is used to provide beam 640 to form a UE-specific cell for UE 642. In another example, the antenna port may include one or more columns of antenna elements, one or more rows of antenna elements, a portion of one or more rows of antenna elements, a portion of one or more columns of antenna elements, all rows or columns of antenna elements, or any other combination.

In another example, antenna ports 650a-664a of the same antenna element can be reused to form different antenna ports 650b-664b, which are configured differently for beam configuration 648b of UE 646. Beam configuration 648b is used to provide beam 644 to UE 646. For example, the eight antenna columns 650b-664b of the 2D antenna array can have different electrical tilts to form eight additional antenna ports, namely, _X9 - _X16 for beam configuration 648b. In one embodiment, beam configurations 648a and 648b can be used simultaneously by eNB 606 for UEs 646 and 648. In another example, the antenna element of antenna port 650c can be used to form a different beam configuration 648c for UE 646. Beam configuration 648c can be used to provide beam 644 to UE 646. In this example, only antenna column 650c of the antenna array is used to form beam configuration 648c for UE 646.

In one embodiment, a desired radiation pattern or beam configuration is created to form a UE-specific cell or a group UE-specific cell. In one embodiment, the desired radiation pattern can be formed by changing the phase, amplitude, and number of antenna elements used for the virtual antenna port or antenna port. In another embodiment, the desired radiation pattern can be formed by changing the electrical tilt level of the virtual antenna port or antenna port and/or by adjusting the beamforming weights of one or more antenna elements of the virtual antenna port or antenna port. Figure 7 shows the combined array gain with the same electrical tilt, where each antenna port has a different number of antenna elements X.

Figure 7 also shows the radiation pattern of the antenna port for the beamforming weights discussed in the previous paragraph. When X antenna elements (1≤X≤M) are assigned the same polarization weight in a column to form an antenna port, the radiation pattern of the antenna port for the beamforming weights is: W = [w ₁ ,w ₂ ,...,w _x ] ^T and n = 1, 2,...X, where W is the beamforming vector used to form a virtual antenna port, w is the beamforming weight applied to each antenna element, T is the transpose operation, X is the number of antenna elements mapped to one antenna port, n is the coefficient of mapping antenna elements to antenna ports, l is the antenna port coefficient used to beamform the multi-port CSI-RS pattern, Q _x is the number of antenna ports in the multi-port CSI-RS pattern, d _v is the vertical antenna element spacing, λ is the wavelength, and θ _etilt is the electrical downtilt angle.

Figure 7 also shows that increasing the number of antenna elements can reduce the mainlobe width and create more nulls. In one embodiment, the eNB can restrict the UE to generate beamforming or weight feedback for a specified number of antennas. In another embodiment, the eNB can allow the UE to select the number of antennas and generate beamforming feedback for the selected number of antennas. In one embodiment, a UE that can change the number of antennas can achieve better coverage than a UE with a fixed number of antennas.

In one embodiment, by performing channel measurements of the CSI-RS pattern from one transmission point or antenna port, the UE can derive a channel matrix H with a number of rows equal to the number of Rx UE antennas and X _max columns. X _max is determined by the maximum number of CSI-RS ports supported by the antenna array. The eNB can require the UE to report the RSRP for the first X antennas, where X = 1, 2, ..., X _max . The UE can then calculate the RSRP for the first X ports of the configured X _max port CSI-RS resources to derive the virtualized RSRP.

For each antenna subset with X antennas (X = 1, 2, ..., X _max ), the UE can reuse a codebook, such as a level-1 codebook for X transmit antennas, to derive the optimal beam weights given the maximum virtualized RSRP. In one embodiment, interference mitigation techniques such as codebook subset restriction can be applied to vertical feedback. In another embodiment, the eNB disables certain codebooks. A new codebook with only DFT vectors for X antennas can be easily defined as: W _X,l = [w _1,l ,w _2,l , ..., w _X,l ] ^T and n = 1, 2, ..., X,l = 0, 1, 2, ..., Q _x -1, where Q _x is the number of DFT vectors in the codebook for X antennas.

In one embodiment, the UE can measure the RSRP and/or RSRQ of multiple cells. The cellular network can then determine which cell to use based on feedback from the UE. For the antenna subset with the first X antennas, the RSRP of the effective channel can be calculated after beamforming, where l _max corresponds to the DFT vector that provides the highest closed-loop RSRP for the antenna subset with the first order X antennas in the configured CSI-RS pattern.

In one embodiment, the UE may measure the CSI of a reference signal for open-loop beamforming or closed-loop beamforming. In one embodiment, open-loop beamforming may be used. For example, open-loop beamforming may be used for downlink transmission mode 3 (TM3). In open-loop beamforming, the UE may report the CSI to the eNB, where the eNB applies a different precoder for each resource element. In another embodiment, closed-loop beamforming may be used. In closed-loop beamforming, such as transmission mode 4 (TM4), the UE may report the CSI to the eNB, and the eNB may select a precoder for beamforming that will produce the desired or optimal spectral efficiency.

In one embodiment where the UE uses closed-loop MIMO operation to define a UE-specific cell, the eNB can configure the UE with a CSI-RS pattern that uses X _max antenna elements. In one embodiment where the 3GPP LTE Rel.10 cellular network has an antenna column with 7 antennas and the number of CSI-RS ports supported by the eNB is 1, 2, 4, or 8, X _max can be 1, 2, or 4. For X _max CSI-RS ports, the eNB can use consecutive X _max antenna elements with the same polarization in a column, as shown in Figures 1 and 2.

In one embodiment, the configured multi-port CSI-RS pattern is used by the UE to measure the channel matrix. For example, in the case where the eNB has 4 antenna columns and each antenna column has 8 antenna elements, the multi-port CSI-RS pattern is used to convey CSI information for one column of 8 antenna elements in a 2D antenna array. In this example, after the UE reports the closed-loop RSRP, the eNB then uses the recommended or selected optimal precoder to beamform the antenna elements of the 4 antenna columns to form a 4-port CSI-RS pattern. The UE will then report the selected or optimal CSI for the 4-port CSI-RS pattern to the eNB.

For an eNB that changes vertical beamforming, the eNB can change the number of antenna elements performing vertical beamforming or change the beamforming weights of the antenna elements. In one embodiment, when the eNB has four columns of antenna elements and each column has eight antenna elements, the eNB can be configured to beamform each antenna column to form a four-port CSI-RS. When forming a four-port CSI-RS, the UE can send CSI or feedback reports for the four-port CSI-RS to the eNB. In another embodiment, the eNB can beamform four of the eight antenna elements in each antenna column to form an eight-port CSI-RS pattern. In this embodiment, the UE can send CSI or feedback reports for the eight-port CSI-RS pattern. In this example, when the eNB maps one column of eight antenna elements to report closed-loop RSRP, the eNB can instruct the UE to report the selected or optimal precoder for the first four-port antenna element and additionally report the selected or optimal precoders for the eight antenna elements.

In one embodiment, the UE may deliver RSRP reports to the eNB per the configured CSI-RS pattern. In this embodiment, each RSRP report may have a different number of antenna elements used to derive the beamformed RSRP. In another embodiment, the UE may report the highest RSRP for the configured CSI-RS pattern and the selected number of antenna elements that derived the highest RSRP. In another embodiment, the UE may report the recommended beamforming weight coefficients used to derive the beamformed RSRP.

In one embodiment, the CSI-RS ports or antenna ports may be beamformed such that each port corresponds to a different vertical beam pattern. One advantage of performing beamforming such that each port corresponds to a different vertical beam pattern is reduced feedback overhead. In another embodiment, the UE may provide feedback on the beamforming weight coefficients and the RSRP of the preferred beam. One advantage of the UE providing feedback on the beamforming weight coefficients and the RSRP of the preferred beam is that the feedback overhead of the vertical beamforming weights is further reduced.

Figure 7 illustrates the main lobe and side lobes of the combined array gain with a selected number of antennas. In Figure 7, the main lobe width and side lobe width can be controlled by the parameter X, which is the number of antenna elements used to form a virtual antenna port. Furthermore, when the number of antenna elements increases to, for example, 10, the antenna gain of the main lobe increases, but the number of side lobes also increases. Similarly, if the number of antenna elements is small, such as 1, the number of side lobes is also small, but the antenna gain of the main lobe is also small. In one embodiment, the antenna gain and the direction of the main lobe and the null between lobes can be used to improve coverage and reduce interference. For example, the main lobe and null can be changed by changing the number of antennas used to form the antenna port. Depending on the UE's elevation angle, better service can be provided to the UE at different values of X.

In one embodiment, different UE-specific cells can be defined by selecting the number X of antenna elements used to form an antenna port and/or changing the electrical tilt of the antenna elements by changing the radiation pattern. In another embodiment, different UE-specific cells can be defined by selecting the number X of antenna elements and selecting beamforming weights by changing the radiation pattern to improve coverage and reduce interference.

FIG8 provides a flow chart 800 illustrating the functionality of one embodiment of computer circuitry of an eNB operable to perform beamforming using multiple-input, multiple-output (MIMO) in a cellular network. The functionality may be implemented as a function or the functionality may be executed as instructions on a machine, wherein the instructions are contained on at least one computer-readable medium or non-transitory machine-readable storage medium. The computer circuitry may be operable to configure one or more UEs to use the same or different multi-port CSI-RS patterns, as shown in block 810. The computer circuitry may also be configured to receive feedback reports at the eNB from one or more UEs associated with the multi-port CSI-RS patterns, as shown in block 820. The computer circuitry may also be configured to use the feedback reports from the one or more UEs to create a UE-dedicated cell or a group of UE-dedicated cells at the eNB for the one or more UEs, as shown in block 830.

In one embodiment, the computer circuit is further configured to make the multiple antenna ports visible to one or more UEs to allow the one or more UEs to receive a multi-port CSI-RS pattern. The computer circuit can also be configured to make the multiple antenna ports visible to the one or more UEs by sending a radio resource control (RRC) configuration message describing the CSI-RS pattern to the one or more UEs. The RRC configuration message can indicate the number of available antenna ports, resource element locations, or CSI-RS energy per resource element (EPRE) ratio on a physical downlink shared channel (PDSCH).

In another embodiment, the computer circuit is further configured to receive a feedback report comprising at least one of a reference signal received power (RSRP) report or a reference signal received quality (RSRQ) report. In another embodiment, the computer circuit is further configured to beamform using 3D MIMO or FD MIMO with a 2D antenna array. In another embodiment, the computer circuit is further configured to form a virtual UE-specific cell or a virtual group UE-specific cell comprising at least one virtual antenna port. In one embodiment, the computer circuit is further configured to associate multiple antenna elements in the 2D antenna array.

In one embodiment, the computer circuit is further configured to create a cell dedicated to a designated UE or group of UEs by changing the number of antenna elements used in a virtual antenna port or by adjusting the beamforming weights of each antenna element of the virtual antenna port in a 2D antenna array to change the electrical tilt level of the virtual antenna port based on feedback reports from one or more UEs to form a desired radiation pattern. In another embodiment, the computer circuit is further configured to configure the one or more UEs with a CSI-RS pattern having X _max antenna elements, where X _max is selected based on a maximum number of CSI-RS ports that is less than or equal to a selected number of antenna elements in the 2D antenna array.

In one embodiment, the computer circuit is further configured to use X _max consecutive antenna elements having the same polarization in a column of a 2D antenna array for a maximum number of _CSI -RS ports. In another embodiment, the computer circuit is further configured to adjust a vertical beamforming portion of 3D beamforming or FD beamforming, wherein the computer circuit adjusts the vertical beamforming portion by changing the number of antenna elements used for the vertical beamforming portion or changing a beamforming weight of at least one antenna element based on feedback reports from one or more UEs associated with the multi-port CSI-RS pattern.

Figure 9 provides a flow chart 900 illustrating the functionality of one embodiment of computer circuitry of a UE operable to communicate in a MIMO network. The functionality may be implemented as a function or the functionality may be executed as instructions on a machine, wherein the instructions are contained on at least one computer-readable medium or a non-transitory machine-readable storage medium. The computer circuitry may be configured to receive, at a UE, a multi-port (multi-port) channel state information reference signal (CSI-RS) pattern from an enhanced Node B (eNB), wherein the multi-port CSI-RS pattern is associated with multiple antenna ports, as shown in block 910. The computer circuitry may also be configured to calculate a reference signal received power (RSRP) or reference signal received quality (RSRQ) for each antenna port associated with the CSI-RS pattern, as shown in block 920. The computer circuitry may also be configured to transmit a feedback report to the eNB, wherein the feedback report includes the RSRP or RSRQ for each antenna port, as shown in block 930.

In one embodiment, the computer circuit is further configured to select the antenna port with the highest received power or the highest received quality and provide feedback to the eNB for the selected antenna port. In another embodiment, the computer circuit configured to receive the multi-port CSI-RS pattern is further configured to receive the multi-port CSI-RS pattern for multiple antenna ports, wherein the multiple antenna ports are associated with: multiple antennas in a 2D antenna array; each antenna in a column in a 2D antenna array; multiple antennas in a column in a 2D antenna array; multiple columns in a 2D antenna array; or each antenna in a 2D antenna array.

In one embodiment, the computer circuit is further configured to derive beamforming weights for the X antennas using a codebook for the X antennas, where X is the number of antennas associated with the plurality of antenna ports. In another embodiment, the computer circuit is further configured to use a codebook having only discrete Fourier transform (DFT) vectors for X antennas, wherein the codebook is defined as W _X,l = [w _1,l , w _{2,l ,} ..., w _X,l ] ^T and n = 1, 2, ..., X,l = 0, 1, ..., Q _x -1, wherein W is a beamforming vector used to form one virtual antenna port, w is a beamforming weight applied to each antenna element, T is a transpose operation, wherein X is the number of antenna elements mapped to one antenna port, wherein n is a coefficient mapping antenna elements to antenna ports, wherein l is an antenna port coefficient used to beamform a multi-port CSI-RS pattern, wherein Q _x is the number of antenna ports in the multi-port CSI-RS pattern, wherein d _v is the vertical antenna element spacing, wherein λ is the wavelength, and wherein θ _etilt is the electrical downtilt angle.

In another embodiment, the computer circuitry is further configured to select an antenna port by determining the maximum RSRP or maximum RSRQ of multiple antenna ports. In one embodiment, the computer circuitry is further configured to report the desired beamforming weight coefficients for selected antenna elements in the eNB's 2D antenna array. In another embodiment, the computer circuitry is further configured to deliver feedback reports to the eNB using closed-loop MIMO. In another embodiment, the computer circuitry is further configured to receive beamformed signals from a virtual UE-dedicated cell or a group UE-dedicated cell based on closed-loop feedback from the UE to the eNB for multiple antenna ports.

Figure 10 provides a flow chart 1000 illustrating a method for beamforming in a multiple-input and multiple-output (MIMO) cellular network. The method may include configuring a user equipment (UE) to use a multiple-port (multi-port) channel state information reference signal (CSI-RS) pattern from an enhanced Node B (eNB), wherein the multi-port CSI-RS pattern is associated with multiple antenna ports, as shown in block 1010. The method also includes receiving, at the eNB, a reference signal received power (RSRP) report from the UE associated with the multi-port CSI-RS pattern, as shown in block 1020. The method may also include, at the eNB, using the RSRP report to create a virtual UE reference cell for the UE, as shown in block 1030. In one embodiment, creating the virtual UE-specific cell further includes beamforming using three-dimensional (3D) MIMO or full-dimensional (FD) MIMO with a 2D antenna array at the eNB. In another embodiment, creating the UE-specific cell or group UE-specific cell further includes forming a virtual UE reference cell comprising at least one virtual antenna port.

In one embodiment, the method further comprises associating a virtual antenna port with a plurality of antenna elements in a 2D antenna array. In another embodiment, the method further comprises configuring the UE with the CSI-RS pattern having X _max antenna elements, wherein X _max is selected based on the maximum number of CSI-RS antenna ports supported by the antenna array of the eNB. In another embodiment, the method further comprises using consecutive X _max antenna elements having the same polarization in a column of the antenna array for the maximum number of CSI-RS antenna ports.

In one embodiment, the method further comprises selecting a defined number of antennas associated with the antenna port based on a feedback report from the UE. In another embodiment, the method further comprises performing beamforming by: adjusting the electrical tilt of a virtual antenna port to be mapped to the virtual antenna port by adjusting the beamforming weights of the antenna elements in the antenna column; adjusting the antenna array tilt; or changing the number of antenna elements used in each antenna column of the 2D antenna array.

Figure 11 provides an example diagram of a wireless device such as a user equipment (UE), a mobile station (MS), a mobile wireless device, a mobile communication device, a tablet, a headset, or other types of wireless devices. The wireless device may include one or more antennas configured to communicate with a node or transmission base station such as a base station (BS), an evolved node B (eNB), a baseband unit (BBU), a remote radio head (RRH), a remote radio equipment (RRE), a relay station (RS), a radio equipment (RE), a remote radio unit (RRU), a central processing module (CPM), or other types of wireless wide area network (WWAN) access points. The wireless device may be configured to communicate using at least one wireless communication standard, including 3GPP LTE, WiMAX, high-speed packet access (HSPA), Bluetooth, and Wi-Fi. The wireless device may communicate using a separate antenna for each wireless communication standard or a shared antenna for multiple wireless communication standards. The wireless device may communicate in a wireless local area network (WLAN), a wireless personal area network (WPAN), and/or a WWAN.

FIG11 also provides an example of a microphone and one or more speakers that can be used for audio input and output of the wireless device. The display screen can be a liquid crystal display (LCD) screen or other type of display screen such as an organic light emitting diode (OLED) display. The display screen can be configured as a touch screen. The touch screen can use capacitive, resistive, or other types of touch screen technology. An application processor and a graphics processor can be coupled to internal memory to provide processing and display capabilities. A non-volatile memory port can also be used to provide data input/output options to the user. The non-volatile memory port can also be used to expand the memory capabilities of the wireless device. A keyboard can be integrated with the wireless device or wirelessly connected to the wireless device to provide additional user input. A virtual keyboard can also be provided using the touch screen.

Various technologies or some aspects or parts of the technology can be in the form of program code (i.e., instruction), and the program code is implemented in tangible media, such as floppy disk, CD-ROM, hard disk drive, non-temporary computer-readable storage medium or any other machine-readable storage medium, wherein, when the program code is loaded and executed by a machine such as a computer, the machine becomes a device for practicing various technologies. When the program code is executed on a programmable computer, the computing device may include a processor, a storage medium readable by the processor (including volatile and non-volatile memory and/or storage element), at least one input device and at least one output device. Volatile and non-volatile memory and/or storage element may be RAM, EPROM flash memory, optical disk drive, magnetic hard disk drive or other media for storing electronic data. Base station and mobile base station may also include a transceiver module, a counter module, a processing module and/or a clock module or a timer module. One or more programs that can implement or adopt various technologies described herein may use application programming interface (API), reusable controls, etc. Such programs may be implemented with high-level programs or object-oriented programming languages to communicate with a computer system. In addition, if necessary, the program may be implemented in assembly language or machine language. In any case, the language may be a compiled or interpreted language and may be combined with a hardware implementation.

It should be understood that many of the functional units described in this specification have been labeled as modules to emphasize their independent implementation. For example, a module can be implemented as a hardware circuit including custom VLSI circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module can also be implemented in a programmable hardware device such as a field programmable gate array, programmable array logic, or a programmable logic device.

Modules may also be implemented in software for execution on various types of processors. An identified module of executable code may, for example, comprise one or more physical or logical blocks of computer instructions, which may, for example, be organized as objects, procedures, or functions. Nevertheless, the executables of an identified module need not be physically located together, but may comprise different instructions stored in different locations that, when logically combined together, comprise the module and achieve the intended purpose of the module.

In fact, the module of executable code can be a single instruction or many instructions, and can even be distributed on several different code segments between different programs and distributed across several memory devices. Similarly, operation data can be identified and shown in the module, and can be implemented in any suitable form and organized in any suitable type of data structure. Operation data can be concentrated into a single data set, or can be distributed on different locations of different storage devices, and can only exist as electronic signals at least partially as electronic signals on a system or network. Modules can be passive or active and include tools that can operate to perform the desired function.

References throughout this specification to "an embodiment" refer to a particular feature, structure, or characteristic described in connection with an example included in at least one embodiment of the present invention. Thus, the appearances of the phrase "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.

As used herein, for convenience, multiple projects, structural elements, combination elements and/or materials can be presented in a common list. However, these lists should be interpreted as each member in the list being individually identified as an independent and unique member. Therefore, based on the performance of the common group without opposite signs, there is no independent member in this type of list that should be interpreted as the de facto equivalent of any other member of the same list. In addition, various embodiments of the present invention and examples can be referring to substitutes of its various components. Should be understood that this type of embodiment, example and substitutes should not be interpreted as equivalents in fact to each other, but should be interpreted as independent and autonomous performance of the present invention.

In addition, the features, structures or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided, such as examples of layouts, distances, examples of networks, etc., to provide a thorough understanding of embodiments of the present invention. However, it should be understood by those skilled in the art that the present invention can be practiced without one or more specific details or with other methods, components, layouts, etc. In other examples, known structures, materials or operations are not shown or described in detail to avoid obscuring various aspects of the present invention.

Although the foregoing examples are illustrative examples of the principles of the present invention in one or more specific applications, it will be apparent to those skilled in the art that many changes in form, implementation, usage, and details may be made without exercising inventive power and without departing from the principles and concepts of the present invention. Therefore, the examples are not intended to limit the present invention, except as set forth in the appended claims.

Claims (19)

1. An enhanced node B (eNB) operable for performing beamforming in a cellular network using multiple-input multiple-output (MIMO), the eNB having computer circuitry configured to: Configure one or more user equipments (UEs) to use the same or different multi-port (multi-port) channel state information reference signal (CSI-RS) modes; Receive feedback reports associated with the multi-port CSI-RS mode from the one or more UEs at the eNB; and Using feedback reports from the one or more UEs, a UE-dedicated cell or group of UE-dedicated cells is created at the eNB for the one or more UEs. The computer circuitry is further configured to form a virtual UE-dedicated cell or a virtual group of UE-dedicated cells, which includes at least one virtual antenna port. The computer circuitry is further configured to associate multiple antenna elements in the 2D antenna array, and The computer circuitry is further configured to create UE-dedicated cells or groups of UE-dedicated cells to form a desired radiation pattern by changing the number of antenna elements used in the virtual antenna port or by adjusting the beamforming weights on each antenna element of the virtual antenna port in the 2D antenna array, based on feedback reports from the one or more UEs. 2. The enhanced node B according to claim 1, wherein the computer circuitry is further configured to make multiple antenna ports visible to the one or more UEs to allow the one or more UEs to receive multi-port CSI-RS mode; and By sending a Radio Resource Control (RRC) configuration message describing the CSI-RS mode to the one or more UEs, the plurality of antenna ports are made visible to the one or more UEs; The RRC configuration message indicates the number of available antenna ports, resource element locations, or the CSI-RS of the energy per resource element (EPRE) ratio on the Physical Downlink Shared Channel (PDSCH). 3. The enhanced node B according to claim 1, wherein the computer circuitry is further configured to receive a feedback report, the feedback report including at least one of a reference signal received power (RSRP) report or a reference signal received quality (RSRQ) report. 4. The augmentation node B according to claim 1, wherein the computer circuitry is further configured to use three-dimensional (3D) MIMO or full-dimensional (FD) MIMO with a 2D antenna array for beamforming. 5. The enhanced node B according to claim 1, wherein the computer circuitry is further configured to configure the one or more UEs using a CSI-RS mode having X _max antenna elements, wherein X _max is selected based on a maximum number of CSI-RS ports that is less than or equal to a selected number of antenna elements in the 2D antenna array. 6. The enhanced node B according to claim 5, wherein the computer circuitry is further configured to use X _max consecutive antenna elements with the same polarization in columns of a 2D antenna array for a maximum number of CSI-RS ports. 7. The enhanced node B of claim 4, wherein the computer circuitry is further configured to adjust the vertical beamforming portion of 3D beamforming or FD beamforming, wherein the computer circuitry adjusts the vertical beamforming portion based on feedback reports from one or more UEs associated with the multiport CSI-RS mode by changing the number of antenna elements for the vertical beamforming portion or changing the beamforming weight of at least one antenna element. 8. A user equipment (UE) operable for communicating in a multiple-input multiple-output (MIMO) cellular network, the UE having computer circuitry configured to: At the UE, a multi-port (multi-port) channel state information reference signal (CSI-RS) mode is received from the enhanced node B (eNB), wherein the multi-port CSI-RS mode is associated with multiple antenna ports; Calculate the reference signal received power (RSRP) or reference signal received quality (RSRQ) for each antenna port associated with the CSI-RS mode; and A feedback report is transmitted to the eNB, wherein the feedback report includes an RSRP or RSRQ for each antenna port. The computer circuitry is further configured to use a codebook for the X-antenna that consists only of discrete Fourier transform (DFT) vectors, wherein the codebook is defined as: W _X,l =[w _1,l ,w _2,l ,...,w _X,l ] ^T and Where W is the beamforming vector used to form a virtual antenna port, w is the beamforming weight applied to each antenna element, T is the transpose operation, X is the number of antenna elements mapped to an antenna port, n is the coefficient of the antenna element mapped to the antenna port, l is the antenna port coefficient used for beamforming multiport CSI-RS mode, _Qx is the number of antenna ports in multiport CSI-RS mode, _dv is the vertical antenna element spacing, λ is the wavelength, and θ _etilt is the electrical downtilt angle. 9. The user equipment according to claim 8, wherein the computer circuitry is further configured to: Select the antenna port with the highest received power or the highest received quality; and Provide feedback to the eNB at the selected antenna port. 10. The user equipment of claim 8, wherein the computer circuitry configured to receive the multi-port CSI-RS mode is further configured to receive a multi-port CSI-RS mode for a multi-antenna port, wherein the multi-antenna port is associated with: Multiple antennas in a 2D antenna array; Each antenna in the column of the 2D antenna array; Multiple antennas in a column of the 2D antenna array; Multiple columns in the 2D antenna array; or Each antenna in the 2D antenna array. 11. The user equipment of claim 8, wherein the computer circuitry is further configured to derive the beamforming weights of the X antenna using a codebook for the X antenna, wherein X is the number of antennas associated with a plurality of antenna ports. 12. The user equipment of claim 8, wherein the computer circuitry is further configured to select an antenna port by determining the maximum RSRP or the maximum RSRQ of the multi-antenna port. 13. The user equipment of claim 8, wherein the computer circuitry is further configured to report desired beamforming weighting coefficients for selecting antenna elements in the 2D antenna array of the eNB. 14. The user equipment of claim 8, wherein the computer circuitry is further configured to transmit feedback reports to the eNB using closed-loop MIMO. 15. The user equipment of claim 8, wherein the computer circuitry is further configured to receive beamforming signals from a virtual UE dedicated cell or a group of UE dedicated cells based on closed-loop feedback from the UE to the eNB for the plurality of antenna ports. 16. A method for beamforming in a multiple-input multiple-output (MIMO) cellular network, the method comprising: Configure the user equipment (UE) to use a multi-port (multi-port) channel state information reference signal (CSI-RS) mode from the enhanced node B (eNB), wherein the multi-port CSI-RS mode is associated with multiple antenna ports; At the eNB, a Reference Signal Received Power (RSRP) report associated with the multi-port CSI-RS mode is received from the UE; and At the eNB, a virtual UE-dedicated cell is created for the UE using the RSRP report. Creating a dedicated UE cell or a group of dedicated UE cells also includes forming a virtual dedicated UE cell containing at least one virtual antenna port. The method further includes associating the virtual antenna port with multiple antenna elements in a 2D antenna array; The UE is configured using a CSI-RS mode with X _max antenna elements, where X _max is selected based on the maximum number of CSI-RS antenna ports supported by the antenna array of the eNB; and In a column of an antenna array used for the maximum number of CSI-RS antenna ports, X _max consecutive antenna elements with the same polarization are used. 17. The method of claim 16, wherein creating a virtual UE dedicated cell further includes using three-dimensional (3D) MIMO or full-dimensional (FD) MIMO with a 2D antenna array at the eNB for beamforming. 18. The method of claim 16, wherein the method further comprises selecting a defined number of antennas associated with the antenna port based on a feedback report from the UE. 19. The method of claim 16, further comprising performing beamforming by: The electrical tilt of a virtual antenna port is adjusted by regulating the beamforming weights of the antenna elements in the antenna array to map onto the virtual antenna port; Adjust the tilt of the antenna array; or Change the number of antenna elements used in each antenna column of a 2D antenna array.