CN107006017B

CN107006017B - Evolved node B, user equipment and method for group probing in a full-dimensional multiple-input multiple-output system

Info

Publication number: CN107006017B
Application number: CN201480082783.0A
Authority: CN
Inventors: 朱源; 李庆华; 涂方泽; 陈晓刚
Original assignee: Intel IP Corp
Current assignee: Intel IP Corp
Priority date: 2014-11-18
Filing date: 2014-11-18
Publication date: 2020-05-19
Anticipated expiration: 2034-11-18
Also published as: EP3222099A4; EP3222099A1; WO2016077975A1; CN107006017A

Abstract

An evolved node B (eNB) is configured to support group sounding at a multiple-input multiple-output (MIMO) antenna array. The eNB may include hardware processing circuitry configured to: transmitting a Physical Downlink Control Channel (PDCCH) data block including the masked group SRS requests for reception at a plurality of User Equipments (UEs). The hardware processing circuitry is configured to receive a group SRS including a sum of SRSs from each UE of the plurality of UEs during the group SRS transmission time period and in the group SRS frequency resource. The hardware processing circuitry may include one or more transceivers configured to be coupled to a multiple-input multiple-output (MIMO) antenna array, the MIMO antenna array including a grid of multiple antenna elements; and the reception of the SRS from each UE of the plurality of UEs may be performed at a MIMO antenna array.

Description

Evolved node B, user equipment and method for group probing in a full-dimensional multiple-input multiple-output system

Technical Field

Embodiments relate to wireless communications. Some embodiments relate to a cellular communication network comprising an LTE network. Some embodiments relate to multiple-input multiple-output (MIMO) systems. Some embodiments relate to detecting (sounding) reference signals.

Background

A base station may employ a multiple-input multiple-output (MIMO) antenna array to improve reception performance when communicating with mobile devices. In some cases, a MIMO antenna array may include a large number of antenna elements, which may be beneficial in terms of diversity gain or the ability to receive signals from multiple mobile devices on the same time and frequency resources. However, the computational complexity involved in processing signals on a large number of antenna elements can be challenging or difficult to handle. Accordingly, there is a general need for methods and systems for reducing or mitigating the computational complexity associated with MIMO antenna arrays.

Drawings

Fig. 1 is a functional diagram of a 3GPP network according to some embodiments;

fig. 2 is a functional diagram of a User Equipment (UE) according to some embodiments;

fig. 3 is a functional diagram of an evolved node B (eNB) in accordance with some embodiments;

fig. 4 is an example of a multiple-input multiple-output (MIMO) antenna array, in accordance with some embodiments;

FIG. 5 illustrates operations of a group detection method according to some embodiments;

FIG. 6 illustrates operations of another group probing method according to some embodiments; and is

Fig. 7 illustrates an example of an Information Element (IE) that may enable group probing according to some embodiments.

Detailed Description

The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in, or substituted for, those of others. Embodiments set forth in the claims encompass all available equivalents of those claims.

Fig. 1 is a functional diagram of a 3GPP network according to some embodiments. The network includes a Radio Access Network (RAN) (e.g., as shown, E-UTRAN or evolved universal terrestrial radio access network) 100 and a core network 120 (e.g., shown as Evolved Packet Core (EPC)) coupled together via an S1 interface 115. For convenience and brevity, only a portion of the core network 120 and the RAN 100 are shown.

The core network 120 includes a Mobility Management Entity (MME)122, a serving gateway (serving GW)124, and a packet data network gateway (PDN GW)126. The RAN 100 includes an evolved node B (eNB)104 (which may serve as a base station) for communicating with User Equipment (UE) 102. The enbs 104 may include macro enbs and Low Power (LP) enbs.

The MME is functionally similar to the control plane of a legacy Serving GPRS Support Node (SGSN). The MME manages mobility aspects in access such as gateway selection and tracking area list management. The serving GW 124 terminates the interface towards the RAN 100 and routes data packets between the RAN 100 and the core network 120. Further, it may be a local mobility anchor for inter-eNB handover, and may also provide an anchor for inter-3 GPP mobility. Other responsibilities may include lawful interception, charging, and some policy enforcement. The serving GW 124 and MME 122 may be implemented in one physical node or in multiple separate physical nodes. The PDN GW126 terminates the SGi interface towards the Packet Data Network (PDN). The PDN GW126 routes data packets between the EPC 120 and the external PDN, and may be a key node for policy enforcement and charging for data collection. It may also provide an anchor point for mobility with non-LTE access. The external PDN may be any kind of IP network as well as IP Multimedia Subsystem (IMS) domain. The PDN GW126 and the serving GW 124 may be implemented in one physical node or in multiple separate physical nodes.

The (macro and micro) enbs 104 terminate the air interface protocol and may be the first point of contact for the UE 102. In some embodiments, the eNB104 may implement various logical functions for the RAN 100, including but not limited to RNCs (radio network controller functions), such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management. According to an embodiment, the UE102 may be configured to communicate OFDM communication signals with the eNB104 over a multicarrier communication channel in accordance with an OFDMA communication technique. The OFDM signal may include a plurality of orthogonal subcarriers.

In accordance with some embodiments, the eNB104 may receive a group Sounding Reference Signal (SRS) including a sum of SRS from each of the plurality of UEs 102 during a SRS transmission time period and in a group SRS frequency resource. The group SRS may enable the eNB104 to form a channel dimension reduction matrix for reduced complexity during reception of traffic signals from the same UE during traffic transmission time periods. These embodiments are described in more detail below.

The S1 interface 115 is an interface that separates the RAN 100 and the EPC 120. It is divided into two parts: S1-U carrying traffic data between the eNB104 and the serving GW 124, and S1-MME signaling interface between the eNB104 and the MME 122. The X2 interface is the interface between enbs 104. The X2 interface comprises two parts of X2-C and X2-U. X2-C is the control plane interface between eNBs 104, while X2-U is the user plane interface between eNBs 104.

For cellular networks, LP cells are typically used to extend coverage to indoor areas where outdoor signals do not reach well, or to increase network capacity at areas where cell phones are very densely used (e.g., train stations). As used herein, the term Low Power (LP) eNB refers to any suitable relatively low power eNB for implementing a narrower cell (narrower than a macro cell), such as a femto cell, pico cell, or micro cell. Femtocell enbs are typically provided by mobile network operators to their residential or business customers. A femto cell is typically the size of a residential gateway or smaller and is typically connected to a subscriber's broadband line. Upon power up, the femto cell connects to the mobile operator's mobile network and provides additional coverage for the residential femto cell, typically in the range of 30 to 50 meters. Thus, since the LP enbs are coupled through the PDN GW126, the lpenbs may be femto cell enbs. Similarly, a picocell is a wireless communication system that typically covers a small area, such as within a building (office, mall, train station, etc.), or recently in an aircraft cabin. A picocell eNB may typically connect to other enbs via an X2 link (e.g., to a macro eNB through its Base Station Controller (BSC) functionality). Thus, since the LP eNB is coupled to the macro eNB via the X2 interface, the LP eNB may be implemented by a pico eNB. A pico eNB or other LP eNB may incorporate some or all of the functionality of a macro eNB. In some cases, this may be referred to as an access point base station or an enterprise femtocell.

In some embodiments, the downlink resource grid may be used for downlink transmissions from the eNB104 to the UE102, while uplink transmissions from the UE102 to the eNB104 may utilize similar techniques. The grid may be a time-frequency grid, referred to as a resource grid or a time-frequency resource grid, which is a physical resource in the downlink in each slot. This time-frequency plane representation is a common practice for OFDM systems, which makes radio resource allocation intuitive. Each column and each row of the resource grid corresponds to one OFDM symbol and one OFDM subcarrier, respectively. The duration of the resource grid in the time domain corresponds to one slot in a radio frame. The smallest unit of time-frequency in the resource grid is represented as a resource element. Each resource grid includes a plurality of resource blocks, which describe the mapping of certain physical channels to resource elements. Each resource block comprises a set of resource elements and in the frequency domain this represents the minimum amount of resources that can currently be allocated. There are several different physical downlink channels that are transmitted using such resource blocks. Of particular relevance to the present disclosure, two of these physical downlink channels are a physical downlink shared channel and a physical downlink control channel.

The Physical Downlink Shared Channel (PDSCH) carries user data and higher layer signaling to the UE102 (fig. 1). The Physical Downlink Control Channel (PDCCH) carries information about the transport format and resource allocation associated with the PDSCH channel, as well as other information. It also informs the UE102 of transport format, resource allocation and H-ARQ information associated with the uplink shared channel. In general, downlink scheduling is performed at the eNB104 (allocating control and shared channel resource blocks to UEs 102 within a cell) based on channel quality information fed back from the UEs 102 to the eNB104, and then downlink resource allocation information is transmitted to the UEs 102 on a control channel (PDCCH) for (allocated to) the UEs 102.

The PDCCH transmits control information using CCEs (control channel elements). The PDCCH complex-valued symbols are first organized into quaternary groups and then permuted using sub-block interleavers for rate matching before mapping to resource elements. Each PDCCH is transmitted using one or more of these Control Channel Elements (CCEs), where each CCE corresponds to nine sets of four physical resource elements called Resource Element Groups (REGs). Four QPSK symbols are mapped to each REG. Depending on the size of the DCI and the channel conditions, the PDCCH may be transmitted using one or more CCEs. There may be four or more different PDCCH formats defined in LTE, with different numbers of CCEs (e.g., aggregation level L ═ 1, 2, 4, or 8).

Fig. 2 is a functional diagram of a User Equipment (UE) according to some embodiments. Fig. 3 is a functional diagram of an evolved node B (eNB) in accordance with some embodiments. It should be noted that in some embodiments, eNB 300 may be a fixed non-mobile device. The UE 200 may be the UE102 as shown in fig. 1, and the eNB 300 may be the eNB104 as shown in fig. 1. The UE 200 may include physical layer circuitry 202 for transmitting and receiving signals to and from the eNB 300, other enbs, other UEs, or other devices using one or more antennas 201; while eNB 300 may include physical layer circuitry 302 for transmitting and receiving from and to UE 200, other enbs, other UEs, or other devices using one or more antennas 301. As will be described in more detail below, the

antennas

201, 301 may be multiple-input multiple-output (MIMO) antennas. The UE 200 may also include medium access control layer (MAC) circuitry 204 to control access to the wireless medium, while the eNB 300 may also include medium access control layer (MAC) circuitry 304 to control access to the wireless medium. The UE 200 may also include the processing circuitry 206 and memory 208 arranged to perform the operations described herein, and the eNB 300 may also include the processing circuitry 306 and memory 308 arranged to perform the operations described herein.

In some embodiments, the mobile devices or other devices described herein may be part of a portable wireless communication device, such as a Personal Digital Assistant (PDA), a laptop or portable computer with wireless communication capability, a web tablet, a wireless telephone, a smart phone, a wireless headset, a pager, an instant messaging device, a digital camera, an access point, a television, a medical device (e.g., a heart rate monitor, a blood pressure monitor, etc.), or other device that may receive and/or transmit information wirelessly. In some embodiments, the mobile device or other device may be a UE102 or eNB104 configured to operate in accordance with 3GPP standards. In some embodiments, the mobile device or other device may be configured to operate in accordance with other protocols or standards, including IEEE802.11 or other IEEE standards. In some embodiments, the mobile device or other device may include one or more of a keyboard, a display, a non-volatile memory port, multiple antennas, a graphics processor, an application processor, speakers, and other mobile device elements. The display may be an LCD screen including a touch screen.

Antennas

201, 301 may include one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmission of RF signals. In some multiple-input multiple-output (MIMO) embodiments, the

antennas

201, 301 may be effectively isolated to take advantage of the spatial diversity and different channel characteristics that may result. Fig. 4 is an example of a multiple-input multiple-output (MIMO) antenna array in accordance with some embodiments. Referring to fig. 4, an exemplary MIMO antenna array 400 illustrates a two-dimensional planar array having antenna elements arranged in a grid having M rows and N columns. In this example, half of the antenna elements may have a tilt angle of positive 45 degrees, while the other half of the antenna elements may have a tilt angle of negative 45 degrees. Thus, the

elements

412, 422, 432 and other solid lines shown may have an angle of positive 45 degrees; while the

elements

414, 424, 434 and other dashed lines shown may have an angle of minus 45 degrees.

One possible arrangement includes the values M-10 and N-2. With two layers in MIMO antenna array 400, there are 40 antenna elements. The signals received at the 40 antenna elements may be different but correlated, particularly when the spacing between the elements is not large. Thus, the diversity gain achieved by MIMO antenna array 400 having 40 antenna elements may not be as high as the diversity gain achieved when 40 independent signals are received. However, using such a large number of antenna elements may increase diversity gain in addition to that achieved by antenna configurations having 4 or 8 antenna elements. Thus, in some cases, MIMO antenna array 400 may be considered a full-dimensional MIMO (FD-MIMO) array.

Although the UE 200 and eNB 300 are each illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements (e.g., processing elements including Digital Signal Processors (DSPs)) and/or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, Field Programmable Gate Arrays (FPGAs), Application Specific Integrated Circuits (ASICs), Radio Frequency Integrated Circuits (RFICs), and combinations of various hardware and logic circuitry for at least performing the functions described herein. In some embodiments, a functional element may refer to one or more processes operating on one or more processing elements.

Embodiments may be implemented in one or a combination of hardware, firmware, and software. Embodiments may also be implemented as instructions stored on a computer-readable storage device, which may be read and executed by at least one processor to perform the operations described herein. A computer-readable storage device may include any non-transitory mechanism that stores information in a form readable by a machine (e.g., a computer). For example, a computer-readable storage device may include Read Only Memory (ROM), Random Access Memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, and other storage devices and media. Some embodiments may include one or more processors and may be configured with instructions stored on a computer-readable storage device.

According to an embodiment, the eNB104 may include hardware processing circuitry configured to transmit Sounding Reference Signal (SRS) radio network temporary identifiers (SRS-RNTIs) for reception at a plurality of UEs, which may include the UE102, for detection of a group SRS request at the UE. The hardware processing circuitry may be further configured to apply the SRS-RNTI to the group SRS request to generate a masked group SRS request, and to transmit a Physical Downlink Control Channel (PDCCH) data block including the masked group SRS request. The hardware processing circuitry may be further configured to receive, during the group SRS transmission time period and in the group SRS frequency resource, a group SRS comprising a sum of SRSs from each UE of the plurality of UEs. These embodiments are described in more detail below.

Fig. 5 illustrates operations of a group detection method according to some embodiments. It is important to note that method 500 may include more or even fewer operations or processes than those shown in fig. 5. Furthermore, embodiments of method 500 are not necessarily limited to the chronological order shown in FIG. 5. In describing the method 500, reference may be made to fig. 1-4 and 6-7. Although it is understood that the method 500 may be implemented with any other suitable systems, interfaces, and components. For example, reference may be made to the MIMO antenna array 400 of fig. 4 described above for purposes of illustration. The techniques and operations of method 500 are not limited in this regard.

Additionally, although the method 500 and other methods are described with reference to an eNB104 or UE102 operating in accordance with 3GPP or other standards, embodiments of the methods are not limited to only those enbs 104 or UEs 102, but may also be implemented on other mobile devices, such as Wi-Fi Access Points (APs) or user Stations (STAs). Moreover, method 500 and other methods described herein may be implemented by wireless devices configured to operate in other suitable types of wireless communication systems, including systems configured to operate in accordance with various IEEE standards, such as IEEE 802.11.

At operation 505 of method 500, a SRS radio network temporary identifier (SRS-RNTI) may be transmitted for reception at a plurality of UEs, including UE 102. The UEs may be assigned to SRS groups and SRS-RNTIs may be reserved for SRS groups and may enable the UEs 102 to detect group SRS requests, as will be described below. In some embodiments, the transmission of the SRS-RNTIs to the plurality of UEs may include transmission of the SRS-RNTIs in a dedicated control message for each of the plurality of UEs. As an example, an Information Element (IE) of a Radio Resource Control (RRC) control message may include a SRS-RNTI or an index to a SRS-RNTI, which may refer to a predetermined group of RNTIs known at the UE 102. The dedicated control message may be transmitted at any suitable time, including during an establishment procedure for a connection between the eNB104 and the UE102 or during an update procedure.

At operation 510, a generic RRC IE including SRS sequence parameters may be transmitted by the eNB 104. The SRS sequence parameters may enable determination at the UE of a group SRS bit sequence that can be used for group sounding by the UE, as will be described below. The group SRS bit sequence may be used at the UE102 to form the SRS transmitted by the UE 102. As an example, the bit sequence may be input to an encoder function, such as Forward Error Correction (FEC), interleaving, bit-to-symbol mapping, or other functions to produce modulation symbols for transmission. As previously described, in some embodiments, modulation symbols may be used to form an OFDM signal for SRS.

Fig. 7 illustrates an example of an Information Element (IE) that may implement group probing, according to some embodiments. The generic RRCIE may be sent in one or more broadcast control messages (which may be received at multiple UEs). Fig. 7 shows an example of one such generic RRC IE, where a generic SRS IE 705 (which may be included in an RRC or other control message) may include other SRS parameters or information 710 (which may be null in some cases) and an SRS configuration index 720. The SRS configuration index 720 may be an index (e.g., an index in the range of 0-1023) that references a predefined SRS bit sequence, or may be an input to a formula or other algorithm, such as a seed value or the like, that may be used to generate the SRS bit sequence at the UE. It should be noted that the SRS bit sequences for group sounding are not limited to a special group of SRS bit sequences reserved for group sounding, although such an arrangement may also be used. The SRS bit sequence may be any suitable SRS sequence, and in some cases, the SRS bit sequence for group sounding may also be used for non-group sounding for other UEs of different time and/or frequency resources. As shown in fig. 7, the generic SRS IE 705 may be a "SoundingRS-UL-configcommoneadic-r 13" IE or the like from 3GPP or other standards, although these embodiments are not limiting.

In operation 515, a dedicated SRS configuration IE including a cyclic shift for a UE may be transmitted to each UE of the plurality of UEs. The example of fig. 7 shows a dedicated SRS IE 755 that may include other SRS parameters or information 760 (which may be null in some cases), and an SRS cyclic shift 770 for the UE 102. The SRS transmitted by the UE102 may be determined by applying a cyclic shift for the UE102 to the SRS described previously. In some embodiments, the cyclic shifts for some or all UEs may be different, which may result in some or all UEs transmitting different SRSs to the eNB104 in the same set of REs during a common or overlapping time period. As shown in fig. 7, dedicated SRS IE 755 may be a "soundngrs-UL-ConfigDedicated" IE from 3GPP or other standards, or the like, although these embodiments are not limiting.

At operation 520, the SRS-RNTI may be applied to the group SRS request to generate a masked group SRS request. A PDCCH data block including the masked group SRS request may be transmitted at operation 525. In some embodiments, applying the SRS-RNTI to the group SRS request can include applying the SRS-RNTI to Cyclic Redundancy Check (CRC) bits of the group SRS request.

At operation 530, a group SRS may be received from a plurality of UEs. The eNB104 may include one or more transceivers configured to be coupled to a MIMO antenna array that includes a grid of multiple antenna elements and at which reception of the group SRS may be performed. Thus, each UE of the plurality of UEs may transmit SRS (or cyclically shifted versions of SRS) during the group SRS transmission period and in the group SRS frequency resources, and the sum of the transmitted SRS (weighted by the channel of each SRS) may form or contribute to the group SRS signal.

At operation 535, a composite received sample vector for the UE at the MIMO antenna array may be determined. The determination may include using a Fast Fourier Transform (FFT), matched filtering, or other techniques. As an example, when the SRS is an OFDM signal, an FFT operation may be performed on the received signal at each antenna element during an OFDM symbol period to produce FFT samples for each Resource Element (RE) or subcarrier. Thus, each RE (or at least a number of REs) may then be associated with a received sample vector (the length of which equals the number of antenna elements in the MIMO antenna array). Thus, a composite received sample vector may actually be determined for each RE, and the determination of multiple composite received sample vectors may be performed jointly in some cases. For example, the FFT operation inherently operates on multiple REs. However, embodiments are not limited to such implementations.

The following FD-MIMO model may be employed to illustrate the concept. At each RE, FFT values may be extracted from the FFT operations performed on each antenna element to form a composite received sample vector for the RE, which may be modeled as:

y＝HPx+n

in the model, the dimension of the received sample vector y is N_rX 1, H is N_r×N_tMatrix, P isN_t×N_pMatrix, x being N_pX 1 data symbol vector, N is N_rX 1 noise vector, N_rIs the number of receiving antennas, N_tIs the number of antenna elements, and N_pIs the number of layers. For example, if the antenna array is a 2D antenna array as shown in fig. 4, N_t2NM and N_tCan be significantly greater than 8. For example, when N is 2 and M is 10, N_t＝40。

When the number of antenna elements is relatively large, the matrix calculations and other calculations may be very high, especially when such calculations may have to be performed at each RE. Therefore, the total number of antenna elements N can be reduced_tVirtualization achieves a reduction in computational complexity for smaller quantities. By way of example, the smaller number of virtual elements may be 1, 2, 4, or 8, which may be compatible with the number of antenna ports available for channel state information reference signals (CSI-RS) in 3GPP or other standards.

The above model can be rewritten as:

matrix P_eIs N_t×N_eMatrix, P_dIs N_e×N_pMatrix, parallel moon

Is dimension N_r×N_eAnd N_t＝N_eK, the effective channel matrix. Thus, the number of columns in the effective channel matrix may be reduced, e.g. from the previous example value 40 to 8.

As part of the model, the mean covariance matrix estimate may be determined by: receiving individual SRSs from multiple UEs, forming an average channel estimate for each user

Formed by averaging (relative to the UE) the matrix products of each average channel estimate with its corresponding Hermite transposeMean covariance matrix estimate, which is expressed as follows:

in this equation, the right hand side is the Singular Value Decomposition (SVD) of the mean covariance matrix estimate, and the "H" symbols on the vector sum matrix represent the hermitian transpose. The columns of matrix V are the eigenbeams of the mean covariance matrix estimate and the diagonal entries of matrix S are the eigenvalues. The previous results may also be obtained by utilizing received sample vectors associated with respective SRSs from multiple UEs instead of channel estimates, e.g., as

In any case, the eigenbeam associated with the strongest eigenvalue may be selected as the matrix P_eThe column (c). As an example, if the strongest 8 eigenbeams are selected, the effective channel matrix

There are also 8 columns.

Improvements in the computational aspects of the above process may be achieved by group probing. As previously described, the group SRS received at the MIMO antenna array may include a sum of the SRS from each of the plurality of UEs during the group SRS transmission time period and in the group SRS frequency resource. The matrix product of the received sample vectors for the group SRS and their hermitian transposes may average out the same result as the SVD described above. I.e. the matrix product of the sums of the individual SRSs comprises the sum of the matrix products of some cross products between the single SRS (found in the last equation) and the SRS of different UEs. Statistically, the cross products may average to zero because they are caused by different UEs transmitting on different channels. Thus, the above-described desired SVD can be obtained by using group probing.

At operation 540, an average covariance matrix estimate may be determined using a matrix product of the group SRS receive sample vector and a transpose of the group SRS receive sample vector. It should be noted that the average may actually be from more than a single group of SRS received sample vectors. I.e., a group SRS receive sample vector from multiple time periods, where the group SRS is transmitted by a group of UEs, may be used at operation 540. At operation 545, a set of eigenvalues and eigenbeams for the mean covariance matrix estimate may be determined using SVD or other suitable techniques. A reduced set of feature bundles may be selected from the set of feature bundles at operation 550; and at operation 555, the reduced set of eigenbeams may be included as columns in the channel dimension reduction matrix. In some embodiments, the selected eigenbeams for the reduced set may be associated with the largest magnitude eigenvalue.

It should be noted that the above operations may occur at each RE or multiple REs, and each UE of these REs may be associated with a channel dimension reduction matrix. Additionally, for each RE, a traffic receive sample vector based at least in part on received signals at antenna elements of a MIMO antenna array may be determined for UE102 during a traffic transmission time period for UE 102. The traffic transmission period may be exclusive to the group SRS transmission period and may also be exclusive to other SRS transmission periods for other UEs.

At operation 560, a channel dimension reduction matrix for a particular RE may be applied to the traffic received sample vector for the RE to produce a reduced dimension received sample vector that may be modeled according to the previously described effective channel. Decoding or demodulation operations may also be simplified because the active channel after virtualization may have much fewer dimensions than the full-dimensional channel previously described. Accordingly, at operation 565, the reduced-dimension vector of received samples may be demodulated to produce soft decisions of decoded symbols or bits from the constellation (or corresponding data bits) for the particular RE. Moreover, similar operations may be performed at other REs, and decoded symbols or bits (hard decisions) or soft decisions from some or all of these operations may be further processed using an FEC decoder or other techniques to produce one or more decoded data blocks.

The eNB104 may also coordinate with other enbs, such as neighboring enbs. In some cases, those enbs or UEs supported by them may cause interference to the enbs 104 during the group sounding period or other time periods. For estimation of the channel covariance matrix as part of group sounding, it may be beneficial for UEs supported by neighboring enbs or other enbs to avoid transmission of sounding signals during the group sounding period of eNB 104. Coordination between the eNB104 and neighboring enbs or other enbs may be performed by appropriate inter-eNB coordination techniques. For example, signaling formats and related procedures for inter-eNB signaling, including as part of 3GPP, LTE, or other standards, may be used. Thus, Information Elements (IEs) in such standards may be defined, created, or modified to include relevant information that may enable enbs to reduce or avoid interference with each other during group sounding or other sounding periods.

FIG. 6 illustrates operations of another group detection method according to some embodiments. As previously described with respect to method 500, embodiments of method 600 may include more or even fewer operations or processes than those shown in fig. 6, and embodiments of method 600 are not necessarily limited to the temporal order shown in fig. 6. In describing the method 600, reference may be made to fig. 1-5 and 7, although it is understood that the method 600 may be implemented with any other suitable systems, interfaces, and components. Further, embodiments of the method 600 may refer to an eNB104, UE102, AP, STA, or other wireless or mobile device.

It should be noted that although not so limited, method 600 may be implemented at UE102, while method 500 may be implemented at eNB 104. Some operations included in one of the

methods

500, 600 may be similar to operations included in the other method, and some or all of the discussion related to one of the

methods

500, 600 may be applicable to the other method. For example, the method 500 may include transmitting a message by the eNB104, while the method 600 may include receiving a similar or related message at the UE 102. Thus, some or all of the description of the message may apply to both

methods

500, 600.

At operation 605, an SRS radio network temporary identifier (SRS-RNTI) associated with the SRS group may be received from the eNB 104. The SRS-RNTI may be received in a dedicated control message for the UE 102. In some embodiments, the SRS group may include UE102 and other UEs. At operation 610, a generic RRCIE including SRS sequence parameters may be received at the UE102, and the SRS sequence parameters may enable determination of a group SRS bit sequence at the UE 102. In some embodiments, the RRC IE may be a generic SRS IE 705 or the like. At operation 615, a dedicated SRS configuration IE may be received that includes a cyclic shift for the UE 102. In some embodiments, the dedicated SRS configuration IE may be a dedicated SRS IE 755, or the like.

At operation 620, a PDCCH data block including the group SRS request may be received at the UE 102. At operation 625, the SRS-RNTI may be applied to the PDCCH data block to detect the group SRS request. In some embodiments, the application of the SRS-RNTI to the PDCCH data block may include applying the SRS-RNTI to Cyclic Redundancy Check (CRC) bits of the group SRS request. At operation 630, an SRS may be transmitted at the UE 102. The transmission may be in response to detection of a group SRS request, and the SRS may be transmitted during a transmission time period and in frequency resources of the group SRS transmission by the group of SRS. As previously described, the SRS signal may be formed using the group SRS bit sequence and the cyclic shift for the UE 102.

An evolved node B (eNB) is disclosed herein. The eNB may include hardware processing circuitry configured to: sounding Reference Signal (SRS) radio network temporary identifiers (SRS-RNTIs) are transmitted for reception at a plurality of User Equipments (UEs) for detection of a group SRS request at the UEs, and the SRS-RNTIs are applied to the group SRS request to generate a masked group SRS request. The hardware processing circuitry may be further configured to transmit a Physical Downlink Control Channel (PDCCH) data block including the masked group SRS requests, and receive a group SRS including a sum of SRS from each UE of the plurality of UEs during the group SRS transmission period and in the group SRS frequency resources. The hardware processing circuitry may include one or more transceivers configured to be coupled to a MIMO antenna array comprising a grid of multiple antenna elements. The receiving of the SRS from each UE of the plurality of UEs may be performed at a MIMO antenna array. In some embodiments, a MIMO antenna array may comprise a two-dimensional planar array of antenna elements. In some embodiments, the MIMO antenna array may be a full-dimensional MIMO antenna array comprising at least 16 elements. The hardware processing circuitry may be further configured to determine a group SRS receive sample vector based at least in part on received signals at antenna elements of the MIMO antenna array during the group SRS transmission time period.

The hardware processing circuitry may be further configured to determine an average covariance matrix estimate based at least in part on a matrix product of the group SRS receive sample vector and the transpose of the group SRS receive sample vector, and determine a set of eigenvalues and eigenbeams of the average covariance matrix estimate. The hardware processing circuitry may be further configured to select a reduced set of eigenbeams from the set of eigenbeams and form a channel dimension reduction matrix according to the magnitude of the corresponding eigenvalue. In some embodiments, a column of the channel dimension reduction matrix may comprise a reduced set of eigenbeams. The hardware processing circuitry may be further configured to determine, for one of the UEs, a traffic receive sample vector based at least in part on the received signals at the antenna elements of the MIMO antenna array during a traffic transmission time period for the UE. The hardware processing circuitry may be further configured to apply a channel dimension reduction matrix to the traffic receive sample vector to form a reduced-dimension traffic receive sample vector, and to demodulate the reduced-dimension traffic receive sample vector to produce decoded data symbols or one or more soft metrics for the data symbols.

In some embodiments, the UEs may be allocated to SRS groups and SRS-RNTIs may be reserved for SRS groups. In some embodiments, the application of the SRS-RNTI to the group SRS request can include applying the SRS-RNTI to Cyclic Redundancy Check (CRC) bits of the group SRS request. In some embodiments, the transmission of the SRS-RNTIs to the plurality of UEs may include transmitting the SRS-RNTIs in a dedicated control message for each of the plurality of UEs. The hardware processing circuitry may be further configured to transmit a generic Radio Resource Control (RRC) Information Element (IE) including SRS sequence parameters to the plurality of UEs to enable determination of a group SRS bit sequence at the UEs. In some embodiments, the SRS received from each UE of the plurality of UEs may be based at least in part on the group SRS bit sequence. The hardware processing circuitry may be further configured to transmit, to each of the UEs, a dedicated SRS configuration IE including a cyclic shift for the UE. In some embodiments, the SRS received from each UE of the plurality of UEs may also be based at least in part on the cyclic shift for that UE, and the cyclic shifts for at least some UEs may be different. In some embodiments, the SRS-RNTI may be reserved for a generic data block included in the PDCCH, which is intended for multiple UEs.

Disclosed herein is a non-transitory computer-readable storage medium that stores instructions for execution by one or more processors to perform operations of transmitting and receiving signals at an evolved node B (eNB). The operations may configure one or more processors to perform the following operations: the method includes transmitting a Sounding Reference Signal (SRS) radio network temporary identifier (SRS-RNTI) for reception at a plurality of User Equipments (UEs) for detection of a group SRS request at the UEs, and applying the SRS-RNTI to the group SRS request to generate a masked group SRS request. The operations may further configure the one or more processors to transmit a Physical Downlink Control Channel (PDCCH) data block including the masked group SRS requests, and receive a group SRS including a sum of SRS from each UE of the plurality of UEs during the group SRS transmission period and in the group SRS frequency resource. In some embodiments, the receiving of the SRS from each UE of the plurality of UEs may be performed at a MIMO antenna array, wherein one or more transceivers included at the eNB are configured to couple to the MIMO antenna array. In some embodiments, the transmission of the SRS-RNTI to the plurality of UEs may include transmission of the SRS-RNTI in a dedicated control message for each of the plurality of UEs. The operations may further configure the one or more processors to transmit a general Radio Resource Control (RRC) Information Element (IE) including SRS sequence parameters to the plurality of UEs to enable determination of a group SRS bit sequence at the UEs. In some embodiments, the SRS received from each UE of the plurality of UEs may be based at least in part on the group SRS bit sequence.

Methods of transmitting and receiving signals at an evolved node B (eNB) are also disclosed. The method may include transmitting a Sounding Reference Signal (SRS) radio network temporary identifier (SRS-RNTI) for reception at a plurality of User Equipments (UEs) for detection of a group SRS request at the UEs, and applying the SRS-RNTI to the group SRS request to generate a masked group SRS request. The method may also include transmitting a Physical Downlink Control Channel (PDCCH) data block including the masked group SRS request, and receiving a group SRS including a sum of the SRS from each of the plurality of UEs during the group SRS transmission time period and in the group SRS frequency resource. In some embodiments, the receiving of the SRS from each UE of the plurality of UEs may be performed at a MIMO antenna array, wherein one or more transceivers included at the eNB are configured to couple to the MIMO antenna array. In some embodiments, the transmission of the SRS-RNTIs to the plurality of UEs may include transmission of the SRS-RNTIs in a dedicated control message for each of the plurality of UEs. The method may also include transmitting a generic Radio Resource Control (RRC) Information Element (IE) including SRS sequence parameters to the plurality of UEs to enable determination of a group SRS bit sequence at the UEs. In some embodiments, the SRS received from each UE of the plurality of UEs may be based at least in part on the group SRS bit sequence.

A User Equipment (UE) is also disclosed. The UE may include hardware processing circuitry configured to receive, from an evolved node B (eNB), Sounding Reference Signal (SRS) radio network temporary identifiers (SRS-RNTIs) associated with a group of SRS including the UE and other UEs. The hardware processing circuitry may be further configured to receive a Physical Downlink Control Channel (PDCCH) data block including the group SRS request and apply the SRS-RNTI to the PDCCH data block to detect the group SRS request. The hardware processing circuitry may be further configured to transmit the SRS during the group SRS transmission time period and in the group SRS frequency resources in response to detection of the group SRS request. In some embodiments, the application of the SRS-RNTI to the PDCCH data block may include applying the SRS-RNTI to Cyclic Redundancy Check (CRC) bits of the group SRS request. In some embodiments, the SRS-RNTI may be received in a dedicated control message for the UE. The hardware processing circuitry may be further configured to receive, from the eNB, a general Radio Resource Control (RRC) Information Element (IE) including SRS sequence parameters to enable determination of a group SRS bit sequence at the UE. In some embodiments, the transmitted SRS may be based at least in part on the group SRS bit sequence. The hardware processing circuitry may also be configured to receive, from the eNB, a dedicated SRS configuration IE including a cyclic shift for the UE. In some embodiments, the transmitted SRS may also be based at least in part on a cyclic shift for the UE.

The abstract is provided to comply with section 37c.f.r. 1.72(b), which clause will allow the reader to ascertain the nature and gist of the technical disclosure. The abstract is submitted with the understanding that it will not be used to limit or interpret the scope or meaning of the claims. Thus the following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.

Claims

1. An evolved node-B comprising hardware processing circuitry comprising one or more transceivers configured to couple to a multiple-input multiple-output, MIMO, antenna array comprising a grid of multiple antenna elements, the hardware processing circuitry configured to:

transmitting sounding reference signals, SRS, radio network temporary identifiers, SRS-RNTIs, for reception at a plurality of user equipments, UEs, for detection of a group SRS request at the UEs;

applying the SRS-RNTI to a group SRS request to generate a masked group SRS request;

transmitting a physical downlink control channel, PDCCH, data block comprising the masked group SRS requests;

receiving, by the MIMO antenna array, a group SRS comprising a sum of SRSs from each UE of the plurality of UEs during a group SRS transmission time period and in a group SRS frequency resource;

determining a group SRS receive sample vector based at least in part on received signals at antenna elements of the MIMO antenna array during the group SRS transmission time period;

determine an average covariance matrix estimate based at least in part on a matrix product of the group SRS receive sample vector and a transpose of the group SRS receive sample vector;

determining a set of eigenvalues and eigenbeams of the mean covariance matrix estimate;

selecting a reduced set of feature beams from the set of feature beams according to the magnitude of the corresponding feature value; and is

Forming a channel dimension reduction matrix, wherein a column of the channel dimension reduction matrix comprises a reduced set of the eigenbeams.

2. The evolved node B of claim 1 wherein the MIMO antenna array comprises a two-dimensional planar array of antenna elements.

3. The evolved node B of claim 1 wherein the MIMO antenna array is a full-dimensional MIMO antenna array comprising at least 16 antenna elements.

4. The evolved node B of claim 1, the hardware processing circuitry further configured to:

determining, for one of the UEs, a traffic receive sample vector based at least in part on received signals at antenna elements of the MIMO antenna array during a traffic transmission time period for the UE;

applying the channel dimension reduction matrix to the traffic receive sample vector to form a reduced-dimension traffic receive sample vector; and is

The reduced-dimension traffic received sample vector is demodulated to produce decoded data symbols or one or more soft metrics for the data symbols.

5. The evolved node B of claim 1 wherein the UE is allocated to a group of SRS and the SRS-RNTI is reserved for the group of SRS.

6. The evolved node B of claim 1 wherein application of the SRS-RNTI to the group SRS request includes applying the SRS-RNTI to Cyclic Redundancy Check (CRC) bits of the group SRS request.

7. The evolved node B of claim 1 wherein the transmission of the SRS-RNTIs to the plurality of UEs comprises a transmission of the SRS-RNTIs in a dedicated control message for each of the plurality of UEs.

8. The evolved node B of claim 1 wherein:

the hardware processing circuitry is further configured to transmit, to the plurality of UEs, a universal radio resource control, RRC, information element, IE, including SRS sequence parameters to enable determination of a group SRS bit sequence at the UE;

the SRS received from each UE of the plurality of UEs is based at least in part on the group SRS bit sequence.

9. The evolved node B of claim 8 wherein:

the hardware processing circuitry is further configured to transmit, to each UE of the plurality of UEs, a dedicated SRS configuration IE comprising a cyclic shift for the UE;

the SRS received from each UE of the plurality of UEs is further based at least in part on the cyclic shift for that UE; and is

The cyclic shifts for at least some of the UEs are different.

10. The evolved node B of claim 1 wherein the SRS-RNTI is reserved for a generic data block included in the PDCCH, the generic data block intended for a plurality of UEs.

11. A non-transitory computer-readable storage medium that stores instructions for execution by one or more processors at an evolved node B to configure the evolved node B to:

receiving, by a multiple-input multiple-output (MIMO) antenna array at the evolved node B, a group SRS comprising a sum of SRSs from each UE of the plurality of UEs during a group SRS transmission period and in a group SRS frequency resource;

determining a group SRS receive sample vector based at least in part on received signals at a plurality of antenna elements of the MIMO antenna array during the group SRS transmission time period;

12. The non-transitory computer readable storage medium of claim 11, wherein:

the transmission of the SRS-RNTIs to the plurality of UEs comprises a transmission of the SRS-RNTIs in a dedicated control message for each UE of the plurality of UEs;

the instructions are also for execution by the one or more processors to further configure the evolved node B to transmit a universal radio resource control, RRC, information element, IE, including SRS sequence parameters to the plurality of UEs to enable determination of a group SRS bit sequence at the UEs; and is

13. A method performed at an evolved node B, the method comprising:

14. The method of claim 13, wherein:

the method also includes transmitting a generic radio resource control, RRC, information element, IE, including SRS sequence parameters to the plurality of UEs to enable determination of a group SRS bit sequence at the UEs; and is

15. An apparatus at an evolved node B, the apparatus comprising:

means for transmitting sounding reference signals, SRS, radio network temporary identifiers, SRS-RNTIs, for reception at a plurality of user equipments, UEs, for detection of a group SRS request at the UEs;

means for applying the SRS-RNTI to a group SRS request to generate a masked group SRS request;

means for transmitting a physical downlink control channel, PDCCH, data block comprising the masked group SRS request;

means for receiving, by a multiple-input multiple-output (MIMO) antenna array at the evolved node B, a group SRS comprising a sum of SRSs from each UE of the plurality of UEs during a group SRS transmission time period and in a group SRS frequency resource;

means for determining a group SRS receive sample vector based at least in part on received signals at a plurality of antenna elements of the MIMO antenna array during the group SRS transmission time period;

means for determining an average covariance matrix estimate based at least in part on a matrix product of the group SRS receive sample vector and a transpose of the group SRS receive sample vector;

means for determining a set of eigenvalues and eigenbeams of the mean covariance matrix estimate;

means for selecting a reduced set of feature beams from the set of feature beams as a function of the magnitude of the corresponding feature value; and

means for forming a channel dimension reduction matrix, wherein a column of the channel dimension reduction matrix comprises a reduced set of the eigenbeams.

16. The apparatus of claim 15, wherein:

the apparatus further includes means for transmitting a generic radio resource control, RRC, information element, IE, including SRS sequence parameters to the plurality of UEs to enable determination of a group SRS bit sequence at the UEs; and is