WO2018063190A1 - Transmission of beam refinement reference signals (brrs) - Google Patents

Abstract

Technology for an eNodeB operable to process beam refinement reference signals (BRRS) for transmission to a plurality of user equipments (UEs) is disclosed. The eNodeB can assign, using a downlink control information (DCI) format, a grouped BRRS configuration that includes grouped BRRS symbols, and each group of BRRS symbols can be associated with a different transmit (Tx) beam. The eNodeB can process the grouped BRRS configuration for transmission on one or more Tx beams to the plurality of UEs. The grouped BRRS symbols can enable each of the plurality of UEs to select a receive (Rx) beam for data reception.

Description

TRANSMISSION OF BEAM REFINEMENT

REFERENCE SIGNALS (BRRS)

BACKGROUND

[0001] Wireless mobile communication technology uses various standards and protocols to transmit data between a node (e.g., a transmission station) and a wireless device (e.g., a mobile device). Some wireless devices communicate using orthogonal frequency -division multiple access (OFDMA) in a downlink (DL) transmission and single carrier frequency division multiple access (SC-FDMA) in uplink (UL). Standards and protocols that use orthogonal frequency-division multiplexing (OFDM) for signal transmission include the third generation partnership project (3GPP) long term evolution (LTE), the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard (e.g., 802.16e, 802.16m), which is commonly known to industry groups as WiMAX (Worldwide interoperability for Microwave Access), and the IEEE 802.11 standard, which is commonly known to industry groups as WiFi.

[0002] In 3GPP radio access network (RAN) LTE systems (e.g., Release 13 and earlier), the node can be a combination of Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node Bs (also commonly denoted as evolved Node Bs, enhanced Node Bs, eNodeBs, or eNBs) and Radio Network Controllers (RNCs), which communicates with the wireless device, known as a user equipment (UE). The downlink (DL) transmission can be a communication from the node (e.g., eNodeB) to the wireless device (e.g., UE), and the uplink (UL) transmission can be a communication from the wireless device to the node.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Features and advantages of the disclosure will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the disclosure; and, wherein:

[0004] FIG. 1 illustrates a transmission of a beam refinement reference signal (BRRS) in accordance with an example;

[0005] FIG. 2 illustrates a transmission of a beam refinement reference signal (BRRS) with multiple BRRS grouped symbols in accordance with an example;

[0006] FIG. 3 illustrates a hierarchical beam search performed at a user equipment (UE) in accordance with an example;

[0007] FIG. 4 illustrates a beam refinement reference signal (BRRS) resource allocation in accordance with an example;

[0008] FIG. 5 illustrates another beam refinement reference signal (BRRS) resource allocation in accordance with an example;

[0009] FIG. 6 illustrates yet another beam refinement reference signal (BRRS) resource allocation in accordance with an example;

[0010] FIG. 7 illustrates a further beam refinement reference signal (BRRS) resource allocation in accordance with an example;

[0011] FIG. 8 depicts functionality of an eNodeB operable to transmit beam refinement reference signals (BRRS) to a plurality of user equipments (UEs) in accordance with an example;

[0012] FIG. 9 depicts functionality of a user equipment (UE) operable to perform hierarchical beam searching based on beam refinement reference signals (BRRS) symbols in accordance with an example;

[0013] FIG. 10 depicts a flowchart of a machine readable storage medium having instructions embodied thereon for transmitting beam refinement reference signals (BRRS) from an eNodeB to a plurality of user equipments (UEs) in accordance with an example;

[0014] FIG. 11 illustrates a diagram of a wireless device (e.g., UE) and a base station (e.g., eNodeB) in accordance with an example; and

[0015] FIG. 12 illustrates a diagram of a wireless device (e.g., UE) in accordance with an example.

[0016] 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 no limitation of the scope of the technology is thereby intended. DETAILED DESCRIPTION

[0017] Before the present technology is disclosed and described, it is to be understood that this technology is not limited to the particular structures, process actions, or materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular examples only and is not intended to be limiting. The same reference numerals in different drawings represent the same element. Numbers provided in flow charts and processes are provided for clarity in illustrating actions and operations and do not necessarily indicate a particular order or sequence.

EXAMPLE EMBODIMENTS

[0018] An initial overview of technology embodiments is provided below and then specific technology embodiments are described in further detail later. This initial summary is intended to aid readers in understanding the technology more quickly but is not intended to identify key features or essential features of the technology nor is it intended to limit the scope of the claimed subject matter.

Grouped BRRS Configuration

[0019] Fifth Generation (5G) wireless communication systems can implement high frequency band communication. In a high frequency band, beam forming can be applied at both an eNodeB and a user equipment (UE). Beamforming applied at the eNodeB can be referred to as transmit (Tx) side beamforming, and beamforming applied at the UE can be referred to as receive (Rx) side beamforming. The Tx beam applied at the eNodeB and the Rx beam applied at the UE can be referred to as a Tx/Rx beam pair. The Tx and Rx side beamforming can be applied to provide beam forming gain, which can compensate for path loss and suppress mutual user interference. The beam forming gain that is obtained can improve system capacity and coverage.

[0020] In order to obtain beam forming gain at both the eNodeB and the UE (i.e., at both the Tx and Rx sides), the UE can search for an optimum Tx/Rx beam pair using a beam reference signal (BRS). The BRS can be a signal that is broadcasted from the eNodeB to the UE, and the BRS can be periodically transmitted to traverse the Tx beam in a fixed manner. In some instances, the UE may have to wait until a next BRS sub frame in order to perform an Rx beam refinement, which can cause an undue delay in achieving the Rx beam refinement. On the other hand, a channel state information (CSI) reference signal (RS) or a sounding RS can be utilized at the UE for Rx beam refinement, but the Tx beams on that RS are limited to a most recent reported BRS measurement.

[0021] In order for the UE to perform the Rx beam refinement and update the Rx beam according to the channel in a reduced amount of time, a beam refinement reference signal (BRRS) can be utilized at the UE. Here, multiple BRRS symbols can be transmitted from the eNodeB to the UE with the same Tx beam, which can enable the UE to apply different Rx beams for reception and refine the Rx beam. In other words, based on the BRRS, the UE can select an appropriate Rx beam based on the Tx beam applied at the eNodeB. The BRRS symbols can be transmitted before data is transmitted to the UE, which may enable the UE to refine the Rx beam before data reception.

[0022] As explained in further detail below, in order to reduce the signaling overhead associated with the Rx beam refinement performed at the UE, a grouped BRRS configuration can be utilized, such that multiple UEs can share the same BRRS resource. As explained in further detail below, the grouped BRRS configuration can be based on downlink control information (DCI), and the grouped BRRS configuration can be transmitted using a dedicated channel for BRRS configuration, such as an enhanced physical beam refinement control channel (xPBRCH). The xPBRCH can be compatible with 5G wireless communication systems.

[0023] FIG. 1 illustrates an exemplary transmission of a beam refinement reference signal (BRRS). One subframe can be assigned for the BRRS transmission. For example, during subframe #n, an eNodeB can transmit downlink control information (DCI) to a user equipment (UE). The DCI can inform the UE on how to receive the BRRS from the eNodeB. For example, the DCI can provide various types of information related to the BRRS, such as a number of resource blocks, subframe index, resource allocation type, modulation scheme, transport block, redundancy version, coding rate, etc. [0024] After a defined number of sub frames (e.g., subframe #(n+N₀fr_Set)), the eNodeB can transmit the subframe with the BRRS. The subframe can include a defined number of BRRS symbols. The UE can detect the BRRS based on the DCI that was previously received from the eNodeB. The BRRS symbols can be transmitted based on the Tx beam of the eNodeB. The subframe can include symbols carried over a physical downlink control channel (PDCCH), as well as symbols carried over a physical uplink control channel (PUCCH). The BRRS transmission can be configured by a first DCI grant (DCI Grant #1). The subframe can include a guard period (GP) between the BRRS symbols and the symbols carried over the PUCCH. As a result, the UE can be provided with a sufficient number of BRRS symbols to perform a receive (Rx) beam refinement, as the number of BRRS symbols provided in the one subframe can enable a full Rx beam sweeping at the UE (i.e., the UE is sufficiently able to refine the Rx beam).

[0025] FIG. 2 illustrates an exemplary transmission of a beam refinement reference signal (BRRS) with multiple BRRS grouped symbols. One subframe can be assigned for a grouped BRRS transmission containing the multiple BRRS grouped symbols. For example, during subframe #n, an eNodeB can transmit downlink control information (DCI) to a user equipment (UE). The DCI can inform the UE on how to receive the grouped BRRS transmission from the eNodeB.

[0026] After a defined number of sub frames (e.g., subframe #(n+N₀fr_Set)), the eNodeB can transmit the subframe containing the grouped BRRS transmission. The UE can detect the grouped BRRS transmission based on the DCI that was previously received from the eNodeB. The one subframe can be divided into N BRRS groups, wherein N is an integer. Within each BRRS group, multiple BRRS symbols can be transmitted, and duplicate reference signals can be transmitted within each BRRS symbol. The BRRS symbols within one group can be transmitted based on a same Tx beam. As a result, multiple Tx beams can be transmitted to the UEs, which can enable an increased number of UEs with different preferred Tx beams to perform Rx beam refinement using the same BRRS resources.

[0027] As an example, the grouped BRRS transmission can include first grouped BRRS symbols and second grouped BRRS symbols. The first grouped BRRS symbols can be transmitted based on a first Tx beam, and the second grouped BRRS symbols can be transmitted based on a second Tx beam. A first UE that prefers the first Tx beam can detect the first grouped BRRS symbols, while a second UE that prefers the second Tx beam can detect the second grouped BRRS symbols. However, both the first UE and the second UE can utilize the same subframe that is used to transmit the grouped BRRS transmission.

[0028] In one example, the subframe carrying the grouped BRRS transmission can include symbols carried over a physical downlink control channel (PDCCH), as well as symbols carried over a physical uplink control channel (PUCCH). The grouped BRRS transmission can be configured by a first DCI grant (DCI Grant #1). The subframe can include a guard period (GP) between the grouped BRRS symbols and the symbols carried over the PUCCH.

[0029] In one configuration, a novel DCI format can be defined for the grouped BRRS transmission. The novel DCI format can be defined for the grouped BRRS transmission for multiple UEs in the same subframe. The bits of the DCI can be denoted as b(0),...,b(M_bit - 1) , where b(0) represents the block of bits and Mbit represents a number of bits to be transmitted. The bits can be transmitted from the eNodeB to the UE on a cell specific scrambling sequence, which can be represented by b (/^') = {b(i) + c(/^'))mod 2 . Here, b (i) represents a block of scrambled bits, b(i) represents a block of bits, and c(i) is the cell specific scrambling sequence.

[0030] In one example, a scrambling sequence generator can be initialized in accordance with c_imt = |_«_s /2_| - 2⁹ + «^s™ , where Cinit represents an initialization value, n_s represents a slot number, and «^SJD represents beam index information utilized at the eNodeB when transmitting the grouped BRRS symbols to the UE.

[0031] In one example, the eNodeB can transmit the DCI based on a same Tx beam as the grouped BRRS symbols. In another example, the eNodeB can transmit the DCI based on a predefined wide beam pattern.

[0032] In one example, the can be predefined or configured at the UE by higher layer radio resource control (RRC) signaling, or the «^s™ can be configured via broadcast signaling to the UE, e.g. , via an enhanced master information block (xMIB) or an enhanced system information block (xSIB). The UE can utilize the «_{BRRS ID} associated with a desired Tx beam to blindly detect the DCI. If the UE can successfully detect the DCI, the UE can detect the corresponding grouped BRRS symbols, and the grouped BRRS symbols can be utilized at the UE to refine the Rx beam.

[0033] In addition, the UE can detect the novel DCI format based on a new radio network temporary identifier (RNTI), such as a BRRS-RNTI, and the BRRS-RNTI can be predefined or configured at the UE by higher layer signaling or radio resource control (RRC) signaling. Alternatively, the UE can determine the BRRS-RNTI based on a cell identifier (ID), a BRRS ID, a subframe index and/or a Tx beam index, wherein the Tx beam index can correspond to a BRRS group of symbols. A cyclic redundancy check (CRC) can be scrambled by the BRRS-RNTI. In addition, in order to avoid excessive blind decoding attempts at the UE, zero padding can be utilized for the novel DCI format to match with other DCI format(s).

[0034] In one example, different grouped BRRS symbols can be configured by different DCI grants. For example, the first grouped BRRS symbols can correspond to DCI grant #0, and the second grouped BRRS symbols can correspond to DCI grant #1. In addition, different DCI can be transmitted using frequency division multiplexing (FDM) or time division multiplexing (TDM).

[0035] In one example, the configuration of multiple BRRS grouped symbols can be configured within one DCI grant. For this combined DCI grant, the DCI can be transmitted for multiple configured Tx beams. For example, if three grouped BRRS symbols are configured within one subframe, e.g. #Tx0, #Txl , #Tx2, then the DCI can be transmitted triply based on these three Tx beams. In another example, the combined DCI can be transmitted using different time/frequency resources within one subframe. In yet another example, the combined DCI can be transmitted within different subframes, while a different subframe offset can be configured between the DCI and the grouped BRRS transmissions.

[0036] In one example, one or multiple Tx beam indexes, which can correspond to one or multiple grouped BRRS symbols, can be indicated within the DCI. Within the DCI, multiple Tx beam indexes can be concatenated in an increasing order along with a BRRS group number. After the UE receives the DCI, the UE can perform a Tx/Rx beam pair refinement accordingly. In another example, the Tx beam index can be implicitly configured by a corresponding DCI. For example, the CRC can be masked with a codeword, which can be defined as a function of the Tx beam index.

[0037] In one example, an association between different BRRS groups and an assigned resource, including BRRS antenna ports and OFDM symbols, can be configured within the DCI. In another example, the BRRS group number can be implicitly configured by referring to the number of indicated Tx beam indexes. In yet another example, the BRRS group number can be configured within the DCI or by high layer signaling.

[0038] In one configuration, a start symbol and an end symbol for a grouped BRRS transmission within one subframe can be configured within the DCI. The start symbol and the end symbol can each be configured using a one-bit indicator. As an example, a one-bit indicator can be set to "0" when the grouped BRRS symbols are transmitted starting from the #2 OFDM symbol, and the one-bit indicator can be set to "1" when the grouped BRRS symbols are transmitted starting from the #0 OFDM symbol. As another example, a one-bit indicator can be set to "0" to indicate that the grouped BRRS symbols end at the #11 OFDM symbol, and the one-bit indicator can be set to "1" to indicate that the grouped BRRS symbols end at the #13 OFDM symbol.

[0039] In one example, a number of BRRS antenna ports (APs) and a number of repetitions can be configured, or pre-defined. For example, 4 repetitions can be configured for 8 BRRS APs, or 8 repetitions can be configured for 4 BRRS APs. In another example, a subframe offset N₀ff_set between the DCI and the grouped BRRS symbols can be configured by the DCI or higher layer signaling.

[0040] In one configuration, the grouped BRRS symbols can be transmitted from the eNodeB to the UE via an enhanced physical beam refinement control channel (xPBRCH). The xPBRCH can be a dedicated channel for transmitting the grouped BRRS symbols (or BRRS configuration) to the UE. The eNodeB can utilize the xPBRCH for transmitting the grouped BRRS symbols instead of an xPDCCH. The xPBRCH can be used to broadcast BRRS configuration information in one subframe to the UE. The BRRS configuration information carried by the xPBRCH can include a BRRS format and Tx beam indexes for grouped BRRS transmissions. The BRRS format can indicate a number of symbols that are occupied by BRRS. The Tx beam index can indicate a Tx beam for a configured grouped BRRS transmission. The UE can determine that a particular Tx beam is applied to a certain grouped Tx transmission, and the UE can refine its Rx beam according to the Tx beam.

[0041] In one example, in order to simultaneously support more than one beam refinement, the Tx beam index can be configured for different BRRS antenna ports. The xPBRCH can be transmitted by an aggregated beam based on all the beams within the Tx beam index. Alternatively, more than one xPBRCH can be transmitted and the Tx beam index can only indicate one Tx beam. The xPBRCH for different BRRS APs can be mapped to consecutive resource blocks (RBs) in an increasing antenna port (AP) index order.

[0042] In one example, signal generation for the xPBRCH may be similar as compared to the xPDCCH or an enhanced physical broadcast channel (xPBCH). A CRC can be predefined or determined based on a cell ID. A scrambler can be determined based on the cell ID and a subframe index. Resource elements used for the xPBRCH can be pre- defined or determined based on the cell ID. The xPBRCH can be mapped to the same symbol as the xPDCCH. For example, the xPDCCH can take 96 resource blocks (RBs) in the first symbol, where a maximum of 16 control channel elements (CCEs) can be transmitted. Then, the xPBRCH can take 4 RBs, and a starting RB can be predefined or determined based on the cell ID.

BRRS Overhead Reduction

[0043] In massive multiple input multiple output (MIMO) systems, beamforming can be applied at both the eNodeB and the UE. Beamforming applied at the eNodeB can be referred to as transmit (Tx) side beamforming, and beamforming applied at the UE can be referred to as receive (Rx) side beamforming. The Tx beam applied at the eNodeB and the Rx beam applied at the UE can be referred to as a Tx/Rx beam pair. The Tx beam can also be referred to as a network (NW) beam, and the Rx beam can also be referred to as a UE beam.

[0044] In one example, the eNodeB can apply different transmit (Tx) beams to a beam reference signal (BRS). The UE can select one of the Tx beams to access based on a measurement of BRS receiving power (BRS-RP) with a given receive (Rx) beam. In other words, the UE can determine which Tx beam provides the highest BRS-RP for a given Rx beam.

[0045] In another example, due to UE movement (e.g., rotation), the UE can refine the Rx beam for the Tx beam. For example, a beam refinement reference signal (BRRS) can be used to refine the Rx beam, by which an interleaved frequency division multiple access (IFDMA) based signal with one Tx beam can be transmitted and the UE can receive each time domain replica using different Rx beams, such that the UE can determine an optimum Rx beam for the corresponding Tx beam.

[0046] In one example, there can be N time domain replicas for the UE to refine its beam (i.e., the Rx beam) within one symbol, where N is a repetition factor (RPF) of the BRRS. The value of N can be lower than a defined value in case a detection performance cannot be confirmed for one Rx beam, or a desired UE beam switching speed is relatively high. As an example, when N is set to 4, the UE can refine 4 Rx beams in one symbol. In this example, to refine X number of Rx beams (e.g., X=20), the UE can use (X/N) symbols to transmit BRRS. In this example, the UE can use 20/4, or 5, symbols to transmit the BRRS. In some cases, the overhead for the BRRS can be relatively high, such that the transmission of other signals can be inhibited. For example, the overhead for the BRRS can inhibit the transmission of the enhanced physical downlink shared channel

(xPDSCH).

[0047] Therefore, as described in further detail below, the overhead of the BRRS for a full Rx beam search can be reduced, in part, by enabling the UE to perform a hierarchical Rx beam search.

[0048] In one configuration, in order to reduce the overhead for the BRRS, the UE can perform a hierarchical Rx beam search based on BRRS symbols received from the eNodeB. For example, the UE can receive a first BRRS symbol from the eNodeB. The UE can perform a first hierarchical Rx beam search by searching a first subset of Rx beams for the first BRRS symbol. The first subset of Rx beams can be a partial number of the total Rx beams for the UE. Then, the UE can receive a second BRRS symbol. The first BRRS symbol and the second BRRS symbol can be received in one or more slots of a downlink subframe. The first BRRS symbol and the second BRRS symbol can be separated by a defined interval. The UE can perform a second hierarchical Rx beam search by searching a second subset of Rx beams for the second BRRS symbol. The second subset can include Rx beams that surround one or more Rx beams from the first hierarchical beam search that satisfy defined criteria. In other words, the UE can select an optimum Rx beam from the first hierarchical Rx beam search, and then the UE can only search one or more Rx beams that surround the optimum Rx beam from the first hierarchical Rx beam search. As a result, the UE may not search the total number of Rx beams. Rather, the UE can only search a subset of the total number of Rx beams, thereby causing a reduction in the number of symbols that are used to transmit the BRRS. After the first hierarchical Rx beam search and the second hierarchical Rx beam search, the UE can obtain an Rx beam that is optimal with respect to the Tx beam that is applied at the eNodeB.

[0049] Given that the UE may have X receive (Rx) beams (or UE beams), wherein X is an integer, in previous solutions, the UE may search X times in order to determine which Rx beam is most suitable for the UE. In other words, the UE may search X times to identify the Rx beam that is optimum for a Tx beam applied at an eNodeB, but this level of searching may cause an undesirable amount of signaling overhead for BRRS.

[0050] FIG. 3 illustrates an example of a hierarchical beam search for beam refinement reference signal (BRRS) performed at a user equipment (UE). The hierarchical beam search can consume a reduced amount of signaling overhead for BRRS as compared to previous solutions in which the UE searches for all the receive (Rx) beams. By employing the hierarchical beam search, the UE can first search a partial set of Rx beams. Then, the UE can search one or more Rx beams surrounding an Rx beam from the first search that satisfies certain criteria. For example, the Rx beam that satisfies certain criteria can be an optimum Rx beam. Here, the optimum Rx beam can refer to an Rx beam that archives an increased amount of beamforming gain when paired with a corresponding Tx beam.

[0051] For example, as shown in FIG. 3, the UE may have 20 Rx beams. For the first BRRS symbol, the UE can search beams 2, 7, 14 and 19. For these four Rx beams, the UE can identify an optimum Rx beam (e.g., an Rx beam that provides an increased amount of beamforming gain when paired with the Tx beam applied at an eNodeB). Then, for the second BRRS symbol, the UE can search sunounding Rx beams around the optimum Rx beam from beams 2, 7, 14 and 19. In this example, the UE can perform two rounds of hierarchical beam searching in order to identify the optimum Rx beam. In this example, the UE can utilize two symbols to perform the hierarchical beam search, whereas previous solutions that do not employ the hierarchical beam search use an increased number of symbols (e.g., five symbols).

[0052] In one example, to reduce the overhead of BRRS, the UE can support the hierarchical Rx beam search. Based on the hierarchical Rx beam search, the UE can prepare Rx beams for the BRRS symbol according to the detection of a last BRRS symbol. Therefore, there can be a defined time interval between each BRRS symbols to reserve processing time for detection of each BRRS symbol.

[0053] FIG. 4 illustrates an example of a beam refinement reference signal (BRRS) resource allocation. As shown, one BRRS subframe can include slot 0 and slot 1 , and each slot can include 7 symbols. The can be S BRRS symbols in the subframe, and the interval between the BRRS symbols can be T symbols, wherein S and T are integers. In addition, S and T can be predefined or configured by higher layer signaling or via downlink control information (DCI). In this example, there can be 2 BRRS symbols in one subframe, and one BRRS symbol can be located in each slot. The DCI can be transmitted in a first slot of the subframe. The one subframe can be utilized by a user equipment (UE) to perform a receive (Rx) beam hierarchical search.

[0054] FIG. 5 illustrates an example of a beam refinement reference signal (BRRS) resource allocation. As shown, one BRRS subframe can include slot 0 and slot 1 , and each slot can include 7 symbols. To reserve additional time for enhanced physical downlink control channel (xPDCCH) decoding, two BRRS symbols can be located in the last slot of the subframe. The first BRRS symbol can be at a selected time interval from the second BRRS symbol. Since BRRS detection can include a time domain autocorrelation or a channel estimation, which may utilize fewer symbols as compared to xPDCCH detection, an interval between each BRRS symbol can be smaller than an interval between the xPDCCH and the first BRRS symbol. In addition, DCI can be transmitted in a first slot of the subframe.

[0055] FIG. 6 illustrates an example of a beam refinement reference signal (BRRS) resource allocation. As shown, one BRRS subframe can include slot 0 and slot 1 , and each slot can include 7 symbols. To enable time feedback for BRRS detection, the BRRS and a physical uplink control channel (xPUCCH) can be transmitted in one subframe with a predefined or configured interval. As shown, an interval between a BRRS symbol and the xPUCCH can be larger than an interval between the two BRRS symbols. In addition, DCI can be transmitted in a first slot of the subframe.

[0056] In one configuration, a BRRS process can be defined, and the BRRS process can include BRRS in M consecutive downlink subframes, wherein M is an integer. Here, M can be predefined by the system or configured by higher layer signaling or via DCI. Each downlink subframe can include one or more BRRS symbols. In the DCI that is used to detect the BRRS transmission, an indicator for a number of BRRS subframe

transmissions within a BRRS process can be added. For example, the indicator in the DCI can indicate a current number of BRRS subframe transmissions in one BRRS process with a length of [log2M] bits, wherein M is the number of consecutive downlink subframes.

[0057] FIG. 7 illustrates an example of a beam refinement reference signal (BRRS) resource allocation. As shown, the BRRS resource allocation can be a BRRS process that includes two downlink subframes, and each downlink subframe can include slot 0 and slot 1, and each slot can include 7 symbols. In this example, the two downlink subframes can correspond to M=2, and one BRRS symbol can be transmitted in each subframe. In addition, t can indicate a value of an indicator in DCI. The DCI can be transmitted in a first slot of each downlink subframe. In some cases, the BRRS symbol index in each subframe can be different, which can be predefined or configured by higher layer signaling or via the DCI.

[0058] In one example, cross subframe scheduling can be utilized for BRRS scheduling. The DCI and BRRS can be transmitted in different subframes, such that the DCI can be transmitted in subframe n, and the BRRS can be transmitted in subframe n+k when more than one subframe is utilized for a BRRS process. The subframe delay k can be predefined or configured by higher layer signaling or via the DCI.

[0059] In one configuration, a network device (e.g., eNodeB) can transmit beam refinement reference signal (BRRS) symbols and control signaling for the BRRS symbols. In one example, each BRRS symbol can be transmitted in one slot. In another example, an interval between two BRRS symbols can be predefined or configured by higher layer signaling or via downlink control information (DCI). In yet another example, the BRRS symbols can be located in a second slot in one subframe, and DCI that is used to configure a transmission of the BRRS symbols can be in a first slot in the same subframe. In a further example, DCI, BRRS symbols, and symbols carried via an enhanced physical uplink control channel (xPUCCH) can be transmitted in the same subframe.

[0060] In one example, DCI can be transmitted in a first slot and BRRS symbols and symbols carried via an xPUCCH can be transmitted in a second slot with a predefined interval between the DCI and the BRRS/xPUCCH symbols. In another example, a BRRS process can include a defined number of consecutive BRRS subframes. In yet another example, each BRRS subframe can include one BRRS symbol, and the BRRS symbol can be triggered by DCI in the same subframe. In a further example, BRRS symbols can be transmitted a defined number of times within a BRRS process, and the defined number of times can be configured by DCI in the same subframe. In yet a further example, DCI can be transmitted in subframe n and BRRS symbols can be transmitted in subframe n+k, where k can be predefined or configured by higher layer signaling or via DCI.

[0061] Another example provides functionality 800 of an eNodeB operable to transmit beam refinement reference signals (BRRS) to a plurality of user equipments (UEs), as shown in FIG. 8. The eNodeB can comprise one or more processors and memory configured to: assign, at the eNodeB, using a downlink control information (DCI) format, a grouped BRRS configuration that includes grouped BRRS symbols, and each group of BRRS symbols is associated with a different transmit (Tx) beam, as in block 810. The eNodeB can comprise one or more processors and memory configured to: process, at the eNodeB, the grouped BRRS configuration for transmission on one or more Tx beams to the plurality of UEs, wherein the grouped BRRS symbols enables each of the plurality of UEs to select a receive (Rx) beam for data reception, as in block 820.

[0062] Another example provides functionality 900 of a user equipment (UE) operable to perform hierarchical beam searching based on beam refinement reference signals (BRRS) symbols, as shown in FIG. 9. The UE can comprise one or more processors and memory configured to: process, at the UE, a first beam refinement reference signals (BRRS) symbol received from an eNodeB, as in block 910. The UE can comprise one or more processors and memory configured to: perform, at the UE, a first hierarchical beam search by searching a first subset of receive (Rx) beams for the first BRRS symbol, as in block 920. The UE can comprise one or more processors and memory configured to: process, at the UE, a second BRRS symbol received from the eNodeB, wherein the first BRRS symbol and the second BRRS symbol are received in one or more slots of a downlink subframe, and the first BRRS symbol and the second BRRS symbol are separated by a defined interval, as in block 930. The UE can comprise one or more processors and memory configured to: perform, at the UE, a second hierarchical beam search by searching a second subset of Rx beams for the second BRRS symbol, wherein the second subset includes Rx beams are selected based on one or more Rx beams from the first hierarchical beam search that satisfy defined criteria, as in block 940. The UE can comprise one or more processors and memory configured to: obtain, at the UE, an Rx beam based on the first hierarchical beam search and the second hierarchical beam search, as in block 950.

[0063] Another example provides at least one machine readable storage medium having instructions 1000 embodied thereon for transmitting beam refinement reference signals (BRRS) from an eNodeB to a plurality of user equipments (UEs), as shown in FIG. 10. The instructions can be executed on a machine, where the instructions are included on at least one computer readable medium or one non-transitory machine readable storage medium. The instructions when executed perform: allocating, using one or more processors at the eNodeB, a grouped BRRS configuration that includes multiple groups of BRRS symbols, wherein the multiple groups of BRRS symbols are configured using a downlink control information (DCI) format, and each group of BRRS symbols is associated with a different transmit (Tx) beam, as in block 1010. The instructions when executed perform: processing, using the one or more processors at the eNodeB, the grouped BRRS configuration for transmission in one or more subframes to the plurality of UEs, wherein the multiple groups of BRRS symbols enables each of the plurality of UEs to refine a receive (Rx) beam for data reception, as in block 1020.

[0064] FIG. 11 provides an example illustration of a user equipment (UE) device 1100 and a node 1120. The UE device 1100 can include a wireless device, a mobile station (MS), a mobile wireless device, a mobile communication device, a tablet, a handset, or other type of wireless device. The UE device 1100 can include one or more antennas configured to communicate with the node 1120 or transmission 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 type of wireless wide area network (WWAN) access point. The node 1120 can include one or more processors 1122, memory 1124 and a transceiver 1126. The UE device 1100 can be configured to communicate using at least one wireless communication standard including 3 GPP LTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth, and WiFi. The UE device 1100 can communicate using separate antennas for each wireless communication standard or shared antennas for multiple wireless communication standards. The UE device 1100 can communicate in a wireless local area network (WLAN), a wireless personal area network (WPAN), and/or a WWAN.

[0065] In some embodiments, the UE device 1100 may include application circuitry 1102, baseband circuitry 1104, Radio Frequency (RF) circuitry 1106, front-end module (FEM) circuitry 1108 and one or more antennas 1110, coupled together at least as shown. In addition, the node 1120 may include, similar to that described for the UE device 1100, application circuitry, baseband circuitry, Radio Frequency (RF) circuitry, front-end module (FEM) circuitry and one or more antennas

[0066] The application circuitry 1102 may include one or more application processors. For example, the application circuitry 1102 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor(s) may include any combination of general -purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors may be coupled with and/or may include a storage medium, and may be configured to execute instructions stored in the storage medium to enable various applications and/or operating systems to run on the system.

[0067] The baseband circuitry 1104 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 1104 may include one or more baseband processors and/or control logic to process baseband signals received from a receive signal path of the RF circuitry 1106 and to generate baseband signals for a transmit signal path of the RF circuitry 1106. Baseband processing circuity 1104 may interface with the application circuitry 1102 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 1106. For example, in some embodiments, the baseband circuitry 1104 may include a second generation (2G) baseband processor 1104a, third generation (3G) baseband processor 1104b, fourth generation (4G) baseband processor 1104c, and/or other baseband processor(s) 1104d for other existing generations, generations in development or to be developed in the future (e.g., fifth generation (5G), 6G, etc.). The baseband circuitry 1104 (e.g., one or more of baseband processors 1104a-d) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 1106. The radio control functions may include, but are not limited to, signal modulation/demodulation, encoding/decoding, radio frequency shifting, etc. In some embodiments, modulation/demodulation circuitry of the baseband circuitry 1104 may include Fast-Fourier Transform (FFT), precoding, and/or constellation

mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 1104 may include convolution, tail-biting convolution, turbo, Viterbi, and/or Low Density Parity Check (LDPC) encoder/decoder functionality.

Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.

[0068] In some embodiments, the baseband circuitry 1104 may include elements of a protocol stack such as, for example, elements of an evolved universal terrestrial radio access network (EUTRAN) protocol including, for example, physical (PHY), media access control (MAC), radio link control (RLC), packet data convergence protocol (PDCP), and/or radio resource control (RRC) elements. A central processing unit (CPU) 1104e of the baseband circuitry 1104 may be configured to run elements of the protocol stack for signaling of the PHY, MAC, RLC, PDCP and/or RRC layers. In some embodiments, the baseband circuitry may include one or more audio digital signal processor(s) (DSP) 1104f. The audio DSP(s) 104f may be include elements for compression/decompression and echo cancellation and may include other suitable processing elements in other embodiments. Components of the baseband circuitry may be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some embodiments. In some embodiments, some or all of the constituent components of the baseband circuitry 1104 and the application circuitry 1102 may be implemented together such as, for example, on a system on a chip (SOC).

[0069] In some embodiments, the baseband circuitry 1104 may provide for

communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 1104 may support communication with an evolved universal terrestrial radio access network (EUTRAN) and/or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN). Embodiments in which the baseband circuitry 1104 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

[0070] The RF circuitry 1106 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 1106 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 1106 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 1108 and provide baseband signals to the baseband circuitry 1104. RF circuitry 1106 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 1104 and provide RF output signals to the FEM circuitry 1108 for transmission.

[0071] In some embodiments, the RF circuitry 1106 may include a receive signal path and a transmit signal path. The receive signal path of the RF circuitry 1106 may include mixer circuitry 1106a, amplifier circuitry 1106b and filter circuitry 1106c. The transmit signal path of the RF circuitry 1106 may include filter circuitry 1106c and mixer circuitry 1106a. RF circuitry 1106 may also include synthesizer circuitry 1106d for synthesizing a frequency for use by the mixer circuitry 1106a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 1106a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 1108 based on the synthesized frequency provided by synthesizer circuitry 1106d. The amplifier circuitry 1106b may be configured to amplify the down-converted signals and the filter circuitry 1106c may be a low-pass filter (LPF) or band -pass filter (BPF) configured to remove unwanted signals from the down-converted signals to generate output baseband signals. Output baseband signals may be provided to the baseband circuitry 1104 for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although this is not a necessity. In some embodiments, mixer circuitry 1106a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect.

[0072] In some embodiments, the mixer circuitry 1106a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 1106d to generate RF output signals for the FEM circuitry 1108. The baseband signals may be provided by the baseband circuitry 1104 and may be filtered by filter circuitry 1106c. The filter circuitry 1106c may include a low-pass filter (LPF), although the scope of the embodiments is not limited in this respect.

[0073] In some embodiments, the mixer circuitry 1106a of the receive signal path and the mixer circuitry 1106a of the transmit signal path may include two or more mixers and may be arranged for quadrature down-conversion and/or up-conversion respectively. In some embodiments, the mixer circuitry 1106a of the receive signal path and the mixer circuitry 1106a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 1106a of the receive signal path and the mixer circuitry 1106a may be arranged for direct down-conversion and/or direct up-conversion, respectively. In some embodiments, the mixer circuitry 1106a of the receive signal path and the mixer circuitry 1106a of the transmit signal path may be configured for super-heterodyne operation.

[0074] In some embodiments, the output baseband signals and the input baseband signals may be analog baseband signals, although the scope of the embodiments is not limited in this respect. In some alternate embodiments, the output baseband signals and the input baseband signals may be digital baseband signals. In these alternate embodiments, the RF circuitry 1106 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 1104 may include a digital baseband interface to communicate with the RF circuitry 1106.

[0075] In some dual-mode embodiments, a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the embodiments is not limited in this respect.

[0076] In some embodiments, the synthesizer circuitry 1106d may be a fractional -N synthesizer or a fractional N/N+l synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers may be suitable. For example, synthesizer circuitry 1106d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.

[0077] The synthesizer circuitry 1106d may be configured to synthesize an output frequency for use by the mixer circuitry 1106a of the RF circuitry 1106 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 1106d may be a fractional N/N+l synthesizer.

[0078] In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO), although that is not a necessity. Divider control input may be provided by either the baseband circuitry 1104 or the applications processor 1102 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) may be determined from a look-up table based on a channel indicated by the applications processor 1102.

[0079] Synthesizer circuitry 1106d of the RF circuitry 1106 may include a divider, a delay -locked loop (DLL), a multiplexer and a phase accumulator. In some embodiments, the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by either N or N+l (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop. In these embodiments, the delay elements may be configured to break a VCO period up into Nd equal packets of phase, where Nd is the number of delay elements in the delay line. In this way, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

[0080] In some embodiments, synthesizer circuitry 1106d may be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency may be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with quadrature generator and divider circuitry to generate multiple signals at the carrier frequency with multiple different phases with respect to each other. In some embodiments, the output frequency may be a LO frequency (fLO). In some embodiments, the RF circuitry 1106 may include an IQ/polar converter.

[0081] FEM circuitry 1108 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 1110, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 1106 for further processing. FEM circuitry 1108 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 1106 for transmission by one or more of the one or more antennas 1110.

[0082] In some embodiments, the FEM circuitry 1108 may include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include a low-noise amplifier (LNA) to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 1106). The transmit signal path of the FEM circuitry 1108 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 1106), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 1110.

[0083] FIG. 12 provides an example illustration of the wireless device, such as a user equipment (UE), a mobile station (MS), a mobile wireless device, a mobile

communication device, a tablet, a handset, or other type of wireless device. The wireless device can include one or more antennas configured to communicate with a node, macro node, low power node (LPN), or, transmission station, such as a base station (BS), an evolved Node B (eNB), a baseband processing unit (BBU), a remote radio head (RRH), a remote radio equipment (RRE), a relay station (RS), a radio equipment (RE), or other type of wireless wide area network (WWAN) access point. The wireless device can be configured to communicate using at least one wireless communication standard such as, but not limited to, 3GPP LTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth, and WiFi. The wireless device can communicate using separate antennas for each wireless communication standard or shared antennas for multiple wireless communication standards. The wireless device can communicate in a wireless local area network

(WLAN), a wireless personal area network (WPAN), and/or a WWAN. The wireless device can also comprise a wireless modem. The wireless modem can comprise, for example, a wireless radio transceiver and baseband circuitry (e.g., a baseband processor). The wireless modem can, in one example, modulate signals that the wireless device transmits via the one or more antennas and demodulate signals that the wireless device receives via the one or more antennas.

[0084] FIG. 12 also provides an illustration of a microphone and one or more speakers that can be used for audio input and output from 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 another type 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 a 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.

Examples

[0085] The following examples pertain to specific technology embodiments and point out specific features, elements, or actions that can be used or otherwise combined in achieving such embodiments.

[0086] Example 1 includes an apparatus of an eNodeB of an eNodeB operable to process beam refinement reference signals (BRRS) for transmission to a plurality of user equipments (UEs), the apparatus comprising one or more processors and memory configured to: assign, at the eNodeB, using a downlink control information (DCI) format, a grouped BRRS configuration that includes grouped BRRS symbols, and each group of BRRS symbols is associated with a different transmit (Tx) beam; and process, at the eNodeB, the grouped BRRS configuration for transmission on one or more Tx beams to the plurality of UEs, wherein the grouped BRRS symbols enables each of the plurality of UEs to select a receive (Rx) beam for data reception.

[0087] Example 2 includes the apparatus of Example 1, further comprising a transceiver configured to transmit the grouped BRRS configuration to the plurality of UEs via an enhanced physical downlink control channel (xPDCCH).

[0088] Example 3 includes the apparatus of any of Examples 1 to 2, wherein the one or more processors and memory are configured to process the grouped BRRS configuration for transmission to the plurality of UEs via an enhanced physical beam refinement control channel (xPBRCH).

[0089] Example 4 includes the apparatus of any of Examples 1 to 3, wherein the one or more processors and memory are configured to generate the grouped BRRS configuration such that the UEs performing beam refinement share the same BRRS configuration resources when the UEs possess different preferred Tx beams.

[0090] Example 5 includes the apparatus of any of Examples 1 to 4, wherein the DCI format is transmitted to one of the plurality of UEs using a cell-specific scrambling sequence, and the cell-specific scrambling sequence is initialized using

C_init = |_A7_s/2j · 2⁹ + fi_gppg^_p , wherein C represents an initialization value, A7_S represents a slot number, ^ERR^D represents beam index information and is utilized to transmit the grouped BRRS configuration, and «^s™ is predefined or configured using higher layer radio resource control (RRC) signaling or broadcast signaling to the UE, wherein the UE is configured to: blindly detect the DCI format utilizing the ^_pg^ associated with a desired Tx beam, and detect a group of BRRS symbols based on the DCI format for refinement of the Rx beam.

[0091] Example 6 includes the apparatus of any of Examples 1 to 5, wherein the one or more processors and memory are configured to define the DCI format to include one or more Tx beam indexes and one or more corresponding groups of BRRS symbols, wherein the Tx beam indexes are concatenated in an increasing order with a BRRS group index.

[0092] Example 7 includes the apparatus of any of Examples 1 to 6, wherein the one or more processors and memory are configured to define the DCI format to include assigned resources that correspond to the grouped BRRS symbols including BRRS antenna ports.

[0093] Example 8 includes the apparatus of any of Examples 1 to 7, wherein the one or more processors and memory are configured to define a BRRS radio network temporary identifier (RNTI), wherein the BRRS RNTI is signaled from the eNodeB to one of the plurality of UEs via higher layer signaling or radio resource control (RRC) signaling, wherein a cyclic redundancy check (CRC) is scrambled by the BRRS RNTI, and the BRRS RNTI enables the UE to detect the DCI format received from the eNodeB.

[0094] Example 9 includes the apparatus of any of Examples 1 to 8, wherein the one or more processors and memory are configured to process BRRS configuration information for transmission via an enhanced physical beam refinement control channel (xPBRCH), wherein the BRRS configuration information includes a BRRS format and a Tx beam index for BRRS, wherein the BRRS format indicates a number of symbols occupied by the BRRS, and the Tx beam index indicates a Tx beam for a configured BRRS.

[0095] Example 10 includes an apparatus of a user equipment (UE) operable to process beam refinement reference signals (BRRS) symbols received from an eNodeB, the apparatus comprising: a transceiver; and one or more processors and memory configured to: process, at the UE, a first beam refinement reference signals (BRRS) symbol received from the eNodeB via the transceiver; perform, using the transceiver at the UE, a first hierarchical beam search by searching a first subset of receive (Rx) beams for the first BRRS symbol; process, at the UE, a second BRRS symbol received from the eNodeB via the transceiver, wherein the first BRRS symbol and the second BRRS symbol are received in one or more slots of a downlink subframe, and the first BRRS symbol and the second BRRS symbol are separated by a defined interval; perform, using the transceiver at the UE, a second hierarchical beam search by searching a second subset of Rx beams for the second BRRS symbol, wherein the second subset includes Rx beams are selected based on one or more Rx beams from the first hierarchical beam search that satisfy defined criteria; and obtain, at the UE, an Rx beam based on the first hierarchical beam search and the second hierarchical beam search.

[0096] Example 11 includes the apparatus of Example 10, wherein the one or more processors and memory are further configured to process downlink control information (DCI) received from the eNodeB, wherein the DCI enables the UE to receive the first BRRS symbol and the second BRRS symbol, and the DCI indicates the defined interval between the first BRRS symbol and the second BRRS symbol.

[0097] Example 12 includes the apparatus of any of Examples 10 to 11 , wherein the first BRRS symbol is received at the UE in a first slot and the second BRRS symbol is received at the UE in a second slot, and downlink control information (DCI) is received at the UE in the first slot.

[0098] Example 13 includes the apparatus of any of Examples 10 to 12, wherein downlink control information (DCI) is received at the UE in a first slot, and the first BRRS symbol and the second BRRS symbol are received at the UE in a second slot.

[0099] Example 14 includes the apparatus of any of Examples 10 to 13, wherein downlink control information (DCI) is received at the UE in a first slot, and the first BRRS symbol, the second BRRS symbol and an enhanced physical uplink control channel (xPUCCH) symbol are received at the UE in a second slot, wherein the defined interval between the first BRRS symbol and the second BRRS symbol is less than an interval between the second BRRS symbol and the xPUCCH symbol.

[00100] Example 15 includes the apparatus of any of Examples 10 to 14, wherein the defined interval between the first BRRS symbol and the second BRRS symbol is predefined or configured via higher layer signaling.

[00101] Example 16 includes the apparatus of any of Examples 10 to 15, wherein the first BRRS symbol is received at the UE in a first subframe and the second BRRS symbol is received at the UE in a second subframe, wherein the first BRRS symbol and the second BRRS symbol are included in a BRRS process that spans a defined number of consecutive downlink subframes, wherein the first BRRS symbol is detected using first downlink control information (DCI) sent in the first subframe, and the second BRRS symbol is detected using second DCI sent in the second subframe.

[00102] Example 17 includes the apparatus of any of Examples 10 to 16, wherein the first BRRS symbol, the second BRRS symbol and downlink control information (DCI) are received from the eNodeB on different subframes in accordance with cross subframe scheduling.

[00103] Example 18 includes at least one machine readable storage medium having instructions embodied thereon for processing beam refinement reference signals (BRRS) for transmission from an eNodeB to a plurality of user equipments (UEs), the instructions when executed perform the following: allocating, using one or more processors at the eNodeB, a grouped BRRS configuration that includes multiple groups of BRRS symbols, wherein the multiple groups of BRRS symbols are configured using a downlink control information (DCI) format, and each group of BRRS symbols is associated with a different transmit (Tx) beam; and processing, using the one or more processors at the eNodeB, the grouped BRRS configuration for transmission in one or more subframes to the plurality of UEs, wherein the multiple groups of BRRS symbols enables each of the plurality of UEs to refine a receive (Rx) beam for data reception.

[00104] Example 19 includes the at least one machine readable storage medium of Example 18, further comprising instructions when executed perform the following:

processing the grouped BRRS configuration for transmission to the plurality of UEs via an enhanced physical beam refinement control channel (xPBRCH).

[00105] Example 20 includes the at least one machine readable storage medium of any of Examples 18-19, further comprising instructions when executed perform the following: generating the grouped BRRS configuration such that the UEs performing beam refinement share the same BRRS configuration resources when the UEs possess different preferred Tx beams.

[00106] Example 21 includes the at least one machine readable storage medium of any of Examples 18-20, wherein the DCI format is transmitted to one of the plurality of UEs using a cell-specific scrambling sequence, and the cell-specific scrambling sequence is initialized using C_m = |_A7_s/2j · 2⁹ + ηζ^ .™ , wherein C represents an initialization value, A7_S represents a slot number, ABRRS D represents beam index information and is

^xPDCCH

utilized to transmit the grouped BRRS configuration, and ^{BRRS ID} is predefined or configured using higher layer radio resource control (RRC) signaling or broadcast signaling to the UE, wherein the UE is configured to: blindly detect the DCI format utilizing the HBRRS'ID associated with a desired Tx beam, and detect a group of BRRS symbols based on the DCI format for refinement of the Rx beam.

[00107] Example 22 includes the at least one machine readable storage medium of any of Examples 18-21, further comprising instructions when executed perform the following: defining a BRRS radio network temporary identifier (RNTI), wherein the BRRS RNTI is signaled from the eNodeB to one of the plurality of UEs via higher layer signaling or radio resource control (RRC) signaling, wherein a cyclic redundancy check (CRC) is scrambled by the BRRS RNTI, and the BRRS RNTI enables the UE to detect the DCI format received from the eNodeB.

[00108] Example 23 includes an eNodeB operable to process beam refinement reference signals (BRRS) for transmission to a plurality of user equipments (UEs), the eNodeB comprising: means for allocating a grouped BRRS configuration that includes multiple groups of BRRS symbols, wherein the multiple groups of BRRS symbols are configured using a downlink control information (DCI) format, and each group of BRRS symbols is associated with a different transmit (Tx) beam; and means for processing the grouped BRRS configuration for transmission in one or more subframes to the plurality of UEs, wherein the multiple groups of BRRS symbols enables each of the plurality of UEs to refine a receive (Rx) beam for data reception.

[00109] Example 24 includes the eNodeB of Example 23, further comprising means for processing the grouped BRRS configuration for transmission to the plurality of UEs via an enhanced physical beam refinement control channel (xPBRCH).

[00110] Example 25 includes the eNodeB of any of Examples 23 to 24, further comprising means for generating the grouped BRRS configuration such that the UEs performing beam refinement share the same BRRS configuration resources when the UEs possess different preferred Tx beams.

[00111] Example 26 includes the eNodeB of any of Examples 23 to 25, wherein the DCI format is transmitted to one of the plurality of UEs using a cell-specific scrambling sequence, and the cell-specific scrambling sequence is initialized using

C_m = |_A7_s/2j · 2⁹ + fi_gppg^_p , wherein C represents an initialization value, A7_S represents a slot number, ABRR_S D represents beam index information and is utilized to transmit the

^xPDCCH

grouped BRRS configuration, and ^{BRRS ID} is predefined or configured using higher layer radio resource control (RRC) signaling or broadcast signaling to the UE, wherein the UE is configured to: blindly detect the DCI format utilizing the HBRR_S'ID associated with a desired Tx beam, and detect a group of BRRS symbols based on the DCI format for refinement of the Rx beam.

[00112] Example 27 includes the eNodeB of any of Examples 23 to 26, further comprising means for defining a BRRS radio network temporary identifier (RNTI), wherein the BRRS RNTI is signaled from the eNodeB to one of the plurality of UEs via higher layer signaling or radio resource control (RRC) signaling, wherein a cyclic redundancy check (CRC) is scrambled by the BRRS RNTI, and the BRRS RNTI enables the UE to detect the DCI format received from the eNodeB.

[00113] Various techniques, or certain aspects or portions thereof, may take the form of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, compact disc-read-only memory (CD-ROMs), hard drives, non-transitory computer readable storage medium, or any other machine-readable storage medium wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the various techniques. In the case of program code execution on programmable computers, the computing device may include a processor, a storage medium readable by the processor (including volatile and nonvolatile memory and/or storage elements), at least one input device, and at least one output device. The volatile and non-volatile memory and/or storage elements may be a random-access memory (RAM), erasable programmable read only memory (EPROM), flash drive, optical drive, magnetic hard drive, solid state drive, or other medium for storing electronic data The node and wireless device may also include a transceiver module (i.e., transceiver), a counter module (i.e., counter), a processing module (i.e., processor), and/or a clock module (i.e., clock) or timer module (i.e., timer). In one example, selected components of the transceiver module can be located in a cloud radio access network (C-RAN). One or more programs that may implement or utilize the various techniques described herein may use an application programming interface (API), reusable controls, and the like. Such programs may be implemented in a high level procedural or object oriented programming language to communicate with a computer system. However, the program(s) may be implemented in assembly or machine language, if desired. In any case, the language may be a compiled or interpreted language, and combined with hardware implementations. [00114] As used herein, the term "circuitry" may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, circuitry may include logic, at least partially operable in hardware.

[00115] It should be understood that many of the functional units described in this specification have been labeled as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom very-large-scale integration (VLSI) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like.

[00116] Modules may also be implemented in software for execution by various types of processors. An identified module of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions, which may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module may not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module.

[00117] Indeed, a module of executable code may be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network. The modules may be passive or active, including agents operable to perform desired functions.

[00118] Reference throughout this specification to "an example" or "exemplary" means that a particular feature, structure, or characteristic described in connection with the example is included in at least one embodiment of the present technology. Thus, appearances of the phrases "in an example" or the word "exemplary" in various places throughout this specification are not necessarily all referring to the same embodiment.

[00119] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present technology may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as defacto equivalents of one another, but are to be considered as separate and autonomous representations of the present technology.

[00120] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of layouts, distances, network examples, etc., to provide a thorough understanding of embodiments of the technology. One skilled in the relevant art will recognize, however, that the technology can be practiced without one or more of the specific details, or with other methods, components, layouts, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the technology.

[00121] While the forgoing examples are illustrative of the principles of the present technology in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the technology. Accordingly, it is not intended that the technology be limited, except as by the claims set forth below.

Claims

claimed is:

An apparatus of an eNodeB operable to process beam refinement reference signals (BRRS) for transmission to a plurality of user equipments (UEs), the apparatus comprising one or more processors and memory configured to: assign, at the eNodeB, using a downlink control information (DCI) format, a grouped BRRS configuration that includes grouped BRRS symbols, and each group of BRRS symbols is associated with a different transmit (Tx) beam; and

process, at the eNodeB, the grouped BRRS configuration for transmission on one or more Tx beams to the plurality of UEs, wherein the grouped BRRS symbols enables each of the plurality of UEs to select a receive (Rx) beam for data reception.

The apparatus of claim 1, further comprising a transceiver configured to transmit the grouped BRRS configuration to the plurality of UEs via an enhanced physical downlink control channel (xPDCCH).

The apparatus of claim 1, wherein the one or more processors and memory are configured to process the grouped BRRS configuration for transmission to the plurality of UEs via an enhanced physical beam refinement control channel (xPBRCH).

The apparatus of any of claims 1 to 3, wherein the one or more processors and memory are configured to generate the grouped BRRS configuration such that the UEs performing beam refinement share the same BRRS configuration resources when the UEs possess different preferred Tx beams.

The apparatus of claim 1, wherein the DCI format is transmitted to one of the plurality of UEs using a cell-specific scrambling sequence, and the cell- specific scrambling sequence is initialized using C_init = xPDCCH

BRRS, ID ' wherein C_init represents an initialization value, A7_S represents a slot number, ^BRRSJD represents beam index information and is utilized to transmit the grouped BRRS configuration, and «^s™ ^1S predefined or configured using higher layer radio resource control (RRC) signaling or broadcast signaling to the UE, wherein the UE is configured to: blindly detect the DCI format utilizing the ABRRS D associated with a desired Tx beam, and detect a group of BRRS symbols based on the DCI format for refinement of the Rx beam.

The apparatus of claim 1, wherein the one or more processors and memory are configured to define the DCI format to include one or more Tx beam indexes and one or more corresponding groups of BRRS symbols, wherein the Tx beam indexes are concatenated in an increasing order with a BRRS group index.

The apparatus of claim 1, wherein the one or more processors and memory are configured to define the DCI format to include assigned resources that correspond to the grouped BRRS symbols including BRRS antenna ports.

The apparatus of claim 1, wherein the one or more processors and memory are configured to define a BRRS radio network temporary identifier (RNTI), wherein the BRRS RNTI is signaled from the eNodeB to one of the plurality of UEs via higher layer signaling or radio resource control (RRC) signaling, wherein a cyclic redundancy check (CRC) is scrambled by the BRRS RNTI, and the BRRS RNTI enables the UE to detect the DCI format received from the eNodeB.

The apparatus of claim 1, wherein the one or more processors and memory are configured to process BRRS configuration information for transmission via an enhanced physical beam refinement control channel (xPBRCH), wherein the BRRS configuration information includes a BRRS format and a Tx beam index for BRRS, wherein the BRRS format indicates a number of symbols occupied by the BRRS, and the Tx beam index indicates a Tx beam for a configured BRRS.

An apparatus of a user equipment (UE) operable to process beam refinement reference signals (BRRS) symbols received from an eNodeB, the apparatus comprising:

a transceiver; and

one or more processors and memory configured to:

process, at the UE, a first beam refinement reference signals (BRRS) symbol received from the eNodeB via the transceiver;

perform, using the transceiver at the UE, a first hierarchical beam search by searching a first subset of receive (Rx) beams for the first BRRS symbol; process, at the UE, a second BRRS symbol received from the eNodeB via the transceiver, wherein the first BRRS symbol and the second BRRS symbol are received in one or more slots of a downlink subframe, and the first BRRS symbol and the second BRRS symbol are separated by a defined interval; perform, using the transceiver at the UE, a second hierarchical beam search by searching a second subset of Rx beams for the second BRRS symbol, wherein the second subset includes Rx beams are selected based on one or more Rx beams from the first hierarchical beam search that satisfy defined criteria; and

obtain, at the UE, an Rx beam based on the first hierarchical beam search and the second hierarchical beam search.

The apparatus of claim 10, wherein the one or more processors and memory are further configured to process downlink control information (DCI) received from the eNodeB, wherein the DCI enables the UE to receive the first BRRS symbol and the second BRRS symbol, and the DCI indicates the defined interval between the first BRRS symbol and the second BRRS symbol.

The apparatus of claim 10, wherein the first BRRS symbol is received at the UE in a first slot and the second BRRS symbol is received at the UE in a second slot, and downlink control information (DCI) is received at the UE in the first slot.

The apparatus of claim 10, wherein downlink control information (DCI) is received at the UE in a first slot, and the first BRRS symbol and the second BRRS symbol are received at the UE in a second slot.

The apparatus of claim 10, wherein downlink control information (DCI) is received at the UE in a first slot, and the first BRRS symbol, the second BRRS symbol and an enhanced physical uplink control channel (xPUCCH) symbol are received at the UE in a second slot, wherein the defined interval between the first BRRS symbol and the second BRRS symbol is less than an interval between the second BRRS symbol and the xPUCCH symbol.

The apparatus of claim 10, wherein the defined interval between the first BRRS symbol and the second BRRS symbol is predefined or configured via higher layer signaling.

The apparatus of claim 10, wherein the first BRRS symbol is received at the UE in a first subframe and the second BRRS symbol is received at the UE in a second subframe, wherein the first BRRS symbol and the second BRRS symbol are included in a BRRS process that spans a defined number of consecutive downlink subframes, wherein the first BRRS symbol is detected using first downlink control information (DCI) sent in the first subframe, and the second BRRS symbol is detected using second DCI sent in the second subframe.

The apparatus of claim 10, wherein the first BRRS symbol, the second BRRS symbol and downlink control information (DCI) are received from the eNodeB on different subframes in accordance with cross subframe scheduling. At least one machine readable storage medium having instructions embodied thereon for processing beam refinement reference signals (BRRS) for transmission from an eNodeB to a plurality of user equipments (UEs), the instructions when executed by one or more processors at the eNodeB perform the following:

allocating, using the one or more processors at the eNodeB, a grouped BRRS configuration that includes multiple groups of BRRS symbols, wherein the multiple groups of BRRS symbols are configured using a downlink control information (DCI) format, and each group of BRRS symbols is associated with a different transmit (Tx) beam; and

processing, using the one or more processors at the eNodeB, the grouped BRRS configuration for transmission in one or more subframes to the plurality of UEs, wherein the multiple groups of BRRS symbols enables each of the plurality of UEs to refine a receive (Rx) beam for data reception.

The at least one machine readable storage medium of claim 18, further comprising instructions when executed perform the following: processing the grouped BRRS configuration for transmission to the plurality of UEs via an enhanced physical beam refinement control channel (xPBRCH).

The at least one machine readable storage medium of any of claims 18 to 19, further comprising instructions when executed perform the following:

generating the grouped BRRS configuration such that the UEs performing beam refinement share the same BRRS configuration resources when the UEs possess different preferred Tx beams.

The at least one machine readable storage medium of claim 18, wherein the DCI format is transmitted to one of the plurality of UEs using a cell-specific scrambling sequence, and the cell-specific scrambling sequence is initialized using C_m = |_A7_s/2j · 2⁹ + figppg^p , wherein C_m represents an initialization value, A7_S represents a slot number, ^ERR^D represents beam index information ^ xPDCCH and is utilized to transmit the grouped BRRS configuration, and ^{BRRS ID} is predefined or configured using higher layer radio resource control (RRC) signaling or broadcast signaling to the UE, wherein the UE is configured to: blindly detect the DCI format utilizing the

associated with a desired

Tx beam, and detect a group of BRRS symbols based on the DCI format for refinement of the Rx beam.

The at least one machine readable storage medium of claim 18, further comprising instructions when executed perform the following: defining a BRRS radio network temporary identifier (RNTI), wherein the BRRS RNTI is signaled from the eNodeB to one of the plurality of UEs via higher layer signaling or radio resource control (RRC) signaling, wherein a cyclic redundancy check (CRC) is scrambled by the BRRS RNTI, and the BRRS RNTI enables the UE to detect the DCI format received from the eNodeB.