WO2017082952A1 - Mechanisms for beam switching and refinement in cellular systems - Google Patents

Mechanisms for beam switching and refinement in cellular systems Download PDF

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Publication number
WO2017082952A1
WO2017082952A1 PCT/US2016/025777 US2016025777W WO2017082952A1 WO 2017082952 A1 WO2017082952 A1 WO 2017082952A1 US 2016025777 W US2016025777 W US 2016025777W WO 2017082952 A1 WO2017082952 A1 WO 2017082952A1
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WIPO (PCT)
Prior art keywords
brrs
transmission
ofdm symbols
processors
subcarrier spacing
Prior art date
Application number
PCT/US2016/025777
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French (fr)
Inventor
Wenting CHANG
Huaning Niu
Yuan Zhu
Yushu Zhang
Gang Xiong
Jong-Kae Fwu
Xiangyang Zhuang
Qinghua Li
Xiaogang Chen
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Intel IP Corporation
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Publication of WO2017082952A1 publication Critical patent/WO2017082952A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
    • H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
    • H04B7/0842—Weighted combining
    • H04B7/0862—Weighted combining receiver computing weights based on information from the transmitter
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
    • H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
    • H04B7/0842—Weighted combining
    • H04B7/0865—Independent weighting, i.e. weights based on own antenna reception parameters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0003—Two-dimensional division
    • H04L5/0005—Time-frequency
    • H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0053—Allocation of signaling, i.e. of overhead other than pilot signals

Definitions

  • 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).
  • Standards and protocols that use orthogonal frequency- division multiplexing (OFDM) for signal transmission include the third generation partnership project (3 GPP) 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.
  • 3 GPP third generation partnership project
  • LTE long term evolution
  • IEEE 802.16 standard e.g., 802.16e, 802.16m
  • WiMAX Worldwide interoperability for Microwave Access
  • WiFi Wireless mobile communication technology
  • Evolved Universal Terrestrial Radio Access Network (E-UTRAN) system is referred to as an eNode B (also commonly denoted as evolved Node Bs, enhanced Node Bs, eNodeBs, or eNBs), 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.
  • data can be transmitted from the eNodeB to the UE via a physical downlink shared channel (PDSCH).
  • PDSCH physical downlink shared channel
  • a physical uplink control channel (PUCCH) can be used to acknowledge that data was received.
  • Downlink and uplink channels or transmissions can use time-division duplexing (TDD) or frequency-division duplexing (FDD).
  • TDD time-division duplexing
  • FDD frequency-division duplexing
  • DL Downlink
  • Tx Transmitting
  • Rx Receiving
  • UE User Equipment
  • UE User Equipment
  • the Tx beam that is preferable at a given time may change (e.g., from one Tx beam to another Tx beam).
  • an Rx beam that is preferable may also change.
  • FIG. 1 illustrates an example in which a subcarrier spacing( Af BRRS ) of
  • BRRS symbols is four times a subcarrier spacing ( ⁇ );
  • FIG. 2 illustrates a BRRS transmission format (format 1) in accordance with an example
  • FIG. 3 illustrates a BRRS transmission format (format 2) in accordance with an example
  • FIG. 4 illustrates a BRRS transmission format (format 3) in accordance with an example
  • FIG. 5 shows an example structure for a BRRS that has a subcarrier spacing of 4 ⁇ in accordance with an example
  • FIG. 6 illustrates one example for a beam pattern of a first antenna port in accordance with an example
  • FIG. 7 illustrates a beam structure (Format la) in which a first Tx beam can be used for current downlink data and control transmission in accordance with an example
  • FIG. 8 illustrates a beam structure (Format 2a) with which an eNB may switch a Tx beam gradually;
  • FIG. 9 illustrates a beam structure (Format 3a) in accordance with an example
  • FIG. 10 illustrates a beam structure (Format 4a) in accordance with an example
  • FIG. 11 illustrates functionality of User Equipment (UE) in accordance with an example
  • FIG. 12 illustrates functionality of a cellular base station in accordance with an example
  • FIG. 13 provides an example illustration of a wireless device in accordance with an example
  • FIG. 14 provides an example illustration of a user equipment (UE) device, such as 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; and
  • UE user equipment
  • FIG. 15 illustrates a diagram of a node (e.g., eNB and/or a Serving GPRS Support Node) and a wireless device (e.g., UE) in accordance with an example.
  • a node e.g., eNB and/or a Serving GPRS Support Node
  • a wireless device e.g., UE
  • Tx/Rx beam pair An optimum Transmission/Reception (Tx/Rx) beam pair can be searched based on a beam reference signal (BRS).
  • BRS beam reference signal
  • the BRS is a broadcasting signal and is generally transmitted in a periodic way to traverse all Tx beams.
  • UE User Equipment
  • the resulting delay in Rx beam refinement may adversely affect UE reception performance.
  • N e.g. 8
  • BRS-RP Tx beams' receiving power
  • BRS-RP receiving power
  • eNB evolved Node B
  • CSI channel state information
  • the recommended Tx beam from UE's CSI report may be different from the best Tx beam reported in the most recent BRS-RP.
  • the eNB can determine the exact beamforming weight for data transmission. How the beamforming weight is determined depends on the eNB implementation. For example, the eNB can perform beam interpolation to get higher beamforming gain or can beam to a different direction for diversity gain. The eNB can also pair the UE and perform Multi-User (MU) Multiple-Input Multiple-Output (MIMO) precoding for Downlink (DL) MU MIMO transmission. Such operations at the eNB can result in a Tx beamforming direction slightly different from the beam direction used in BRS or CSI-RS training.
  • MU Multi-User
  • MIMO Multiple-Input Multiple-Output
  • the UE may reply on the Rx beam which the UE used to measure the reported best Tx beam in the BRS-RP report. This Rx beam may be sub-optimal for the Tx beam on the PDSCH.
  • L1 layer-one
  • the beam width used in BRS training can be narrow or wide.
  • the beam width can be chosen based on factors such as as beamforming training overhead, delay, and coverage. Additional factors that may influence the choice of beam width include details of the eNB's implementation, such as the number of antennas and the Radio Frequency (RF) architecture. If the eNB uses a relatively wide beam for BRS training, UE Rx beamforming trained through repeated BRS transmission will likely not be very accurate. Some refinements to Reference Signals (RSs) described herein provide additional UE Rx beamforming gain.
  • RSs Reference Signals
  • an eNB may have to to switch between spatially uncorrelated Tx beams.
  • some layer-one signaling or reference signals are described herein so that Rx beam adjustment at the UE can be accomplished accordingly.
  • a beam refinement reference signal can be used.
  • the BRRS can be inserted before a data channel such as a PDSCH or a physical uplink shared channel (PUSCH).
  • PUSCH physical uplink shared channel
  • a receiver can refine an Rx beam based on the BRRS before data reception.
  • an eNB or a UE can gradually update a Tx or Rx beam to support intra Transmission Point (TP) beam mobility.
  • TP Transmission Point
  • the present disclosure provides some examples of BRRS structures that can help an eNB switch between spatially uncorrelated Tx beams (e.g., by providing more frequent opportunities for beam refinement).
  • PHY physical
  • the Rx beam for data reception can be refined without layer-one signaling for a Tx beam that may gradually change.
  • the Rx beam forming gain can potentially be obtained in real time.
  • the UE can start the beam refinement phase using the most recent refined Rx beam and the eNB can be configured not to deviate far from the best Tx candidate beams. This offers advantages over the initial beam acquisition phase in which the UE may search Tx/Rx beam pairs without any prior knowledge. Furthermore, unlike the initial beam acquisition phase, the full bandwidth can be used for the BRRS in some example of the present disclosure.
  • this disclosure presents a wider subcarrier spacing that can be used for the BRRS.
  • a wider subcarrier spacing is used for the BRRS, a candidate Rx beam search consumes less overhead.
  • the signal subcarrier spacing is inversely proportional to the signal time duration.
  • the subcarrier spacing of the BRRS can be larger than that of the following data OFDM symbols (e.g., PDSCH or PUCCH) by a predefined factor so that the total length of the BRRS in the time domain is reduced by the predefined factor. This reduction in the total length or duration of the BRRS enables more Rx beam candidates to be scanned during the limited time period.
  • BRRS format 1 a BRRS signal structure with a subcarrier spacing that is four times the sub-carrier spacing of the data OFDM symbols can be used (i.e., the predefined factor is 4).
  • Four BRRS OFDM symbols can be used for the BRRS.
  • One Tx beam can be applied to the four BRRS OFDM symbols.
  • the BRRS signal structures can have a subcarrier spacing that is four times the sub-carrier spacing of the data OFDM symbols can be used (i.e., the predefined factor is 4). Eight BRRS OFDM symbols can be used for the BRRS.
  • the eNB may use a first Tx beam for the first four OFDM symbols (of the eight BRRS OFDM symbols) and a second Tx beam for the second four OFDM symbols (of the eight BRRS OFDM symbols).
  • the UE can refine the first Rx beam based on the first four OFDM symbols and the second Rx beam based on the second four OFDM symbols.
  • the BRRS signal structures can have a subcarrier spacing that is four times the sub-carrier spacing of the data OFDM symbols can be used (i.e., the predefined factor is 4). Eight BRRS OFDM symbols can be used for the BRRS. One Tx beam can be applied to the eight BRRS OFDM symbols.
  • a UE can start receiving the data samples (e.g., extended PDSCH (xPDSCH) or extended PUSCH (xPUSCH)) following an extended Physical Downlink Control Channel (xPDCCH) using the same reception beam that was used to receive the xPDCCH.
  • the UE can also attempt to decode the DCI. If BRRS enabling/triggering field in the DCI indicates to the UE that there is a BRRS followed by data OFDM symbols, the UE can start Rx beam refinement using those BRRS symbols and the resulting refined Rx beam can be used to receive the data OFDM symbols.
  • the UE can simply use the most current Rx beam to receive the data OFDM symbols.
  • the enabling of the BRRS is configured by the DCI of a previous subframe or upper layer signaling
  • the BRRS may be transmitted before a control channel (e.g., xPDCCH) and the UE can use the current Rx beam to receive control channel.
  • the subcarrier spacing Af BRRS of the BRRS can be m times larger than the data OFDM symbols in order to reduce the duration of BRRS symbols in the time domain so that more BRRS symbols can be transmitted within a limited time period, thereby providing more opportunities for beam refinement.
  • the subcarrier spacing of the OFDM data symbol(s) that follow the BRRS symbols can be represented as Af .
  • Af BRRS can equal a predefined coefficient multiplied by Af .
  • a subcarrier-spacing extension indicator can be configured by the downlink control information (DO) or the higher layers via master information broadcasting (MIB), system information broadcasting (SIB), or radio resource configuration (RRC) signaling.
  • the subcarrier-spacing extension indicator can indicate a coefficient that can be multiplied by Af to produce Af BRRS .
  • the number of bits N. f used by the subcarrier-spacing extension indicator can be equal to [log 2 (number of Af BRRS candidates)] , where [ 1 indicates the ceiling function.
  • An example of a two-bit subcarrier-spacing extension indicator is provided in the following table.
  • the same BRRS subcarrier spacing can be used.
  • a time domain replica signal can be generated using one non-zero symbol followed by three zero symbols in the frequency domain for each BRRS antenna port. Then eight BRRS symbols can have the same duration as two of the data OFDM symbols. Number of BRRS OFDM symbols
  • DCI downlink control information
  • RRC Radio Resource Control
  • N ⁇ refers to the number of data
  • the actual number of BRRS OFDM symbols may be larger than if the subcarrier spacing of the BRRS is enlarged.
  • the total number of BRRS OFDM symbols can be equal to 14/ " , which would allow I Rx beam candidates to be searched.
  • the optimal Tx/Rx beam pair may change dramatically due to a UE' s movement or a change in an environment surrounding the UE.
  • a BRRS signal structure that provides more frequent opportunities for Rx beam refinement can be defined to support more Tx/Rx beam mobility among spatially uncorrelated Tx/Rx beam pairs.
  • An example is illustrated in FIG. 3, where the first four BRRS symbols can be used to refine a first Rx beam around the first Rx beam and the remaining four BRRS symbols can be used to refine a second Rx beam around the second Rx beam.
  • the first and second Rx beams can be indicated in the most recent BRS-RP report.
  • a 2-bit indicator can be configured by the DCI, or higher layer signaling, such as the MIB, the SIB, or RRC signaling. This 2-bit indicator can indicate whether a default BRRS transmission structure or an alternative transmission structure should be used. In this example, where “00” may indicate that no BRRS is included in a transmission, "01 " may indicate a BRRS format 1 structure, " 10" may indicate a BRRS format 2 transmission structure, and ' 1 1 ' can indicate a BRRS format 2 structure.
  • a UE may expect an eNB to send a
  • BRRS using the top N (e.g.) Tx beams that are measured using a first Rx beam.
  • a single derived Rx beam can be used for Channel State Information Reference Signal (CSI-RS) reception and data reception in the following OFDM symbols (i. e. , the OFDM symbols that are sent after the BRRS).
  • CSI-RS Channel State Information Reference Signal
  • a UE may expect an eNB to send a
  • the BRRS using the top N e.g.
  • the Rx beam derived from the second Rx beam can be used for CSI-RS/data reception in the following OFDM symbols (i. e. , the OFDM symbols that are sent after the BRRS).
  • FIG. 1 illustrates an example in which a subcarrier spacing( Af BRRS ) of
  • BRRS symbols is four times a subcarrier spacing ( ⁇ ) of the following OFDM symbols. As shown in FIG. 1, eight BRRS OFDM symbols may be inserted into a time duration that would ordinarily accommodate two data OFDM symbols.
  • An antenna port (AP) can correspond to regions of BRRS symbols that extend over a frequency range of f BRRS . The first four BRRS symbols can be used for Rx beam refinement in one direction and the remaining four BRRS symbols can be used for Rx beam refinement in another direction.
  • FIG. 2 illustrates a BRRS transmission format (format 1) in accordance with an example.
  • a BRRS transmission may be followed by a CSI-RS transmission.
  • BRRS symbols may be followed by a CSI-RS scheduled by control symbols (e.g., DCI).
  • a UE may refine four Rx beam candidates around a current Rx beam #Ri based on the four consecutive BRRS symbols and derive a refined Rx beam #R2. The UE can then use the Rx beam #R2 to receive the following data OFDM symbols and the CSI-RS symbols.
  • FIG. 3 illustrates a BRRS transmission format (format 2) in accordance with an example.
  • BRRS symbols may be followed by a CSI-RS scheduled by control symbols (e.g., DCI).
  • a UE may derive one Rx beam using four consecutive BRRS symbols. As such, the UE may derive two Rx beams using eight consecutive BRRS symbols.
  • the UE may use an Rx beam derived from the first four BRRS symbols to receive a first CSI-RS symbol and an Rx beam derived from the other four BRRS symbols to receive a second CSI-RS symbol.
  • the UE can use the second derived Rx beam.
  • FIG. 4 illustrates a BRRS transmission format (format 3) in accordance with an example.
  • BRRS symbols may be followed by a CSI-RS scheduled by control symbols (e.g., DCI).
  • a UE may refine eight Rx beam candidates around the current Rx beam #Ri based on eight consecutive BRRS symbols and derive one refined Rx beam #R2. The UE can then use the Rx beam #R2 to receive the following data OFDM symbols and the CSI-RS symbols.
  • the Tx beam #72 can be the same as the Tx beam #Ti.
  • BRRS format 1 structure with four Rx beam refinement opportunities can be used.
  • the BRRS format 2 structure with eight Rx beam refinement opportunities can be used.
  • the BRRS format 2 structure with eight Rx beam refinement opportunities can be used.
  • a new TP index can be indicated in the DCI.
  • a one bit nscio can be used to indicate the new TP.
  • a bit value of '0' for the nsciD can correspond to one TP identity (ID) configured by an upper layer.
  • a bit value of ⁇ ' for the nsciD can correspond to the other TP ID configured by an upper layer.
  • the UE can adjust the Rx beam that corresponds to one TP using the default Rx beam that was used to measure the reported BRS-RP for the other TP.
  • N ⁇ ' N ⁇ j / Af BRRS * Af )
  • NTM resource block size in the frequency domain (expressed as a number of subcarriers)
  • N ⁇ B is uplink bandwidth configuration (expressed in multiples of N ⁇ )
  • j is the imaginary square root of negative one.
  • the pseudo-random sequence c(i) is defined in clause 7.2 of 3GPP
  • c imt pseudo-random sequence generator can be initialized with equation (2) in one example:
  • the « BRRS ID and « ⁇ brrsjd ) can be the same as « SCID and for an Uplink/Downlink (UL/DL) Demodulation Reference Signal (DMRS).
  • DMRS Demodulation Reference Signal
  • a sequence for BRRS generation can be based on the Zadoff-Chu sequence or the Quadrature Phase Shift Keying (QPSK) sequence.
  • the BRRS sequence can be generated according to the cell Identity (ID), virtual cell ID, BSR ID, or BRS group ID as well as a subframe index or an AP index.
  • the base sequence can be generated as the equation below:
  • f u n (n) may indicate the Zadoff-Chu sequence (e.g., similar to the sequence described in section 5.5 of 3GPP Technical Specification (TS) 36.21 may be the imaginary square root of negative one, and a may be a constant value or a configurable cyclic shift configured by the AP index, Downlink Control Information (DCI), or Radio Resource Control (RRC) signaling.
  • DCI Downlink Control Information
  • RRC Radio Resource Control
  • a Zadoff-Chu (ZC) sequence can be used for BRRS sequence generation.
  • ZC Zadoff-Chu
  • a same sequence or known sequences can be transmitted in consecutive BRRS symbols of one subframe.
  • a resource mapping rule of a BRRS can be different from that of an existing reference signal, such as a demodulation reference signal (DMRS) or a channel state information (CSI) RS.
  • New antenna ports wherein two ports are in one pair can be defined for BRRS transmission using both vertical and horizontal polarization of one Tx beam.
  • the pairs of antenna ports can be p e ⁇ 31,32 ⁇ , ⁇ 33,34 ⁇ , ⁇ 35,36 ⁇ , ⁇ 37,38 ⁇ .
  • an eNB may have two kinds of antenna structures. In one type of antenna structure, a signal antenna panel for one sector in which one Tx beam for one direction (defined horizontally and vertically) is used to transmit one symbol. In another type of antenna structure, there are multiple antenna panels for one sector and multiple Tx beams may be used to transmit one symbol.
  • two BRRS ports in the same BRRS port pair can be supported by further modulating an orthogonal cover code (OCC) on the pseudo-random sequence for the two consecutive subcarriers.
  • OCC orthogonal cover code
  • Port 31 can use OCC cover ⁇ 1 1 ⁇
  • port 33 can use OCC cover ⁇ 1 -1 ⁇ .
  • the frequency mapping order of the eight BRRS ports maybe changed from ⁇ 31, 33, 35, 37, 32, 34, 36, 38 ⁇ to ⁇ 31, 32, 33, 34, 35, 36, 37, 38 ⁇ (e.g., in FIG. 1).
  • the antenna ports for the BRRS may be divided into several groups and different Tx beams may be applied to the different BRRS groups.
  • a BRRS group can be indicated implicitly by DMRS information so that the antenna port configuration of the DMRS can be used to indicate the antenna ports of the BRRS.
  • DMRS port pairs ⁇ 7,9 ⁇ , ⁇ 8,10 ⁇ , ⁇ 11,13 ⁇ , and ⁇ 12,14 ⁇ can be used to indicate BRRS port pairs ⁇ 31,32 ⁇ , ⁇ 33,34 ⁇ , ⁇ 35,36 ⁇ , and ⁇ 37,38 ⁇ .
  • the BRRS port can be indicated in DCI signaling.
  • the total number of antenna ports ( N ) can be configured by the related DCI or higher layer signaling (e.g., MIB, SIB, or RRC signaling) or can be predefined.
  • the N parameter can indicate how many antenna ports are to share the same Physical Resource Blocks (PRBs) and can be used to calculate a resource mapping, such as the subcarrier gap in interleaved frequency-division multiplexing resource mapping.
  • PRBs Physical Resource Blocks
  • mapping to resource elements a part of the reference signal sequence r(m) can be mapped to complex- valued modulation symbols aff .
  • resource mapping There may be two at least two alternatives for resource mapping.
  • resource elements of the BRRS can be mapped to the same PRBs as the corresponding data.
  • the mapping can be realized in a localized or interleaved way.
  • the BRRS can be assigned within the full bandwidth in a localized or interleaved way.
  • the subcarrier spacing Af BRRS cw be used for the BRRS symbols.
  • the subcarrier spacing Af can be applied.
  • FIG. 5 shows an example structure for a BRRS that has a subcarrier spacing of 4 ⁇ , where Af denotes a subcarrier spacing for an extended (e.g., 5G) Physical Downlink Shared Channel (xPDSCH). Then the duration for one BRRS symbol can be
  • the BRRS sequence for one antenna port may be transmitted repeatedly in each BRRS symbol using a single Tx beam or multiple Tx beams. All the subcarriers within one BRRS symbol can be used for one AP and different APs may be configured with different cyclic shifts. In one example, a first AP may use a cyclic shift of zero and a second AP may use a cyclic shift of 0.5 ⁇ . Alternatively, different APs may use different subcarriers. For example, the BRRS may have two APs. The first AP may use odd subcarriers, while the second AP may use even subcarriers.
  • the BRRS may be used for beam switching and beam refinement.
  • a BRRS format la can be used for Rx beam refinement with a current Tx beam.
  • a BRRS format 2a can be used for gradual Tx beam switching.
  • a BRRS format 3 a can be used when a the full Rx beam search with a new Tx beam is desired.
  • a BRRS format 4a can be used for Tx beam switching between two uncorrelated Tx beams.
  • one UE can use one BRRS AP.
  • the UE may assume that a full Tx beam will be applied in two consecutive BSR-RS symbols.
  • odd- numbered BRRS symbols can be used for horizontal transmission and even BRRS symbols can be used for the vertical transmission direction.
  • FIG. 6 illustrates one example for a beam pattern of a first AP. As shown in FIG. 6, odd BRRS symbols can be used for a vertical Tx beam and even BRRS symbols can be used for a horizontal Tx beam. For a second AP, odd BRRS symbols can be used for a horizontal Tx beam and even BRRS symbols can be used for a vertical Tx beam.
  • FIG. 7 illustrates a beam structure (Format la) in which a first Tx beam can be used for current downlink data and control transmission.
  • the Tx beam used for the BRRS may be the same as a current Tx beam.
  • a UE can try different types of Rx beams to find the a preferred or best Rx beam for Rx beam refinement within N BRRS symbols, wherein N can be predefined by the system or configured by the higher layer signaling or the DCI.
  • FIG. 8 illustrates a beam structure (Format 2a) with which an eNB may switch a Tx beam gradually.
  • the new Tx beam (e.g., the beam to which the eNB switches) may be applied in the BRRS, the xPDSCH, and the CSI-RS.
  • Tx beam 1 indicates the current Tx beam and Tx beam 2 indicated the new Tx beam.
  • Both Tx beams 1 and 2 are highly correlated.
  • a UE can try different types of Rx beams to find a preferred or best Rx beam for the new Tx beam.
  • FIG. 9 illustrates a beam structure (Format 3a) with which an eNB may switch to a new Tx beam directly and a full Rx beam searching process may be applied for the BRRS reception.
  • the new Tx beam may be applied in the BRRS, the xPDSCH, and the CSI-RS.
  • Tx beam 1 indicates a current Tx beam and Tx beam 2 indicates a new Tx beam.
  • 2N BRRS symbols may be applied.
  • N can be predefined by the system or configured by the higher layer signaling or the DCI.
  • FIG. 10 illustrates a beam structure (Format 4a) with which an eNB may switch to a new Tx beam (which may be the second channel cluster).
  • An Rx beam refinement for the new Tx beam may be applied for BRRS reception.
  • the first N symbols may use the current Tx beam and the second N symbols may use the new Tx beam.
  • the new Tx beam may be applied in the xPDSCH.
  • the CSI-RS may use different Tx beams in different symbols.
  • Tx beam 1 indicates the current Tx beam and Tx beam 2 indicates the new Tx beam.
  • FIG. 11 illustrates functionality 1100 of User Equipment (UE) in accordance with an example.
  • the functionality 1100 can be implemented as a method or the functionality can be executed as instructions on a machine (e.g., by one or more processors), where the instructions are included on at least one computer-readable storage medium (e.g., a transitory or non-transitory computer-readable storage medium).
  • UE User Equipment
  • the functionality 1100 can include identifying a Beam
  • BRRS Refinement Reference Signal
  • OFDM Orthogonal Frequency Division Multiplexing
  • the BRRS subcarrier spacing can be predefined in a specification or configured by the cellular base station via one or more of: Downlink Control Information (DCI), master information broadcasting (MIB), system information broadcasting (SIB), or radio resource control (RRC) signaling.
  • DCI Downlink Control Information
  • MIB master information broadcasting
  • SIB system information broadcasting
  • RRC radio resource control
  • the BRRS transmission can comprise one or more BRRS OFDM symbols and the one or more BRRS symbols can contain a plurality of BRRS antenna ports.
  • the BRRS transmission can be mapped in an Orthogonal Frequency Division Multiple Access (OFDMA) symbol between an extended Physical Downlink Control Channel (xPDCCH) and an extended Physical Downlink Shared Channel (xPDSCH) or can be mapped in the OFDMA symbol before the xPDCCH.
  • OFDMA Orthogonal Frequency Division Multiple Access
  • the functionality 1100 can include refining a Reception
  • the BRRS transmission can comprise four BRRS OFDM symbols and, in one example, up to four Rx beams can be refined based the four BRRS OFDM symbols.
  • the BRRS transmission can comprise eight BRRS OFDM symbols.
  • a first Rx beam can be refined based on four first BRRS OFDM symbols of the eight BRRS OFDM symbols.
  • a second Rx beam can be refined based on four second BRRS OFDM symbols of the eight BRRS OFDM symbols.
  • up to eight Rx beams can be refined based on the eight BRRS OFDM symbols.
  • BRRS measurements can be taken using one or more initial Rx beams and a transceiver at the UE can send the BRRS measurements to the cellular base station.
  • the up-to-eight Rx beams can be refined using one or more initial Rx beams.
  • the functionality 1100 can include signaling the transceiver at the UE to use the refined Rx beam to receive the one or more following OFDM symbols.
  • the functionality 1 100 can also include processing a first Channel State
  • CSI-RS Channel State Information Reference Signal
  • PDSCH Physical Downlink Shared Channel
  • the functionality 1100 can also include measuring a BRRS port group, wherein the BRRS port group includes two antenna ports of the plurality of antenna ports, and wherein the two antenna ports are frequency division multiplexed or code division multiplexed.
  • the functionality 1100 can also include refining the Rx beam based on the measuring of the BRRS port group.
  • the two antenna ports can be mapped to all subcarriers used for the BRRS transmission and are generated based on different cyclic shifts.
  • the plurality of antenna ports can be indicated by an antenna port configuration of a Demodulation Reference Signal (DMRS) of an extended Physical Downlink Control Channel (xPDCCH) that is associated with the BRRS transmission.
  • DMRS Demodulation Reference Signal
  • xPDCCH extended Physical Downlink Control Channel
  • FIG. 12 illustrates functionality 1200 of a cellular base station (e.g., an eNB) in accordance with an example.
  • the functionality 1200 can be implemented as a method or the functionality can be executed as instructions on a machine (e.g., by one or more processors), where the instructions are included on at least one computer-readable storage medium (e.g., a transitory or non-transitory computer-readable storage medium).
  • a computer-readable storage medium e.g., a transitory or non-transitory computer-readable storage medium.
  • the functionality 1200 can include identifying a base sequence to be used for a Beam Refinement Reference Signal (BRRS), wherein the base sequence is a Zadoff-Chu sequence or a Quadrature Phase Shift Keying (QPSK) sequence.
  • BRRS Beam Refinement Reference Signal
  • the BRRS subcarrier spacing can be predefined in a specification or the cellular base station can configure the BRRS subcarrier spacing via Downlink Control Information (DO), master information broadcasting (MIB), system information broadcasting (SIB), or radio resource control (RRC) signaling.
  • DO Downlink Control Information
  • MIB master information broadcasting
  • SIB system information broadcasting
  • RRC radio resource control
  • the BRRS transmission can comprise one or more BRRS OFDM symbols (e.g., four or eight) and the one or more BRRS symbols can contain a plurality of BRRS antenna ports.
  • the functionality 1200 can also include signaling a transceiver to frequency-division multiplexed a BRRS sequence for each BRRS antenna port of the plurality of BRRS antenna ports.
  • the functionality 1200 can also include signaling the transceiver to send each BRRS antenna port of the plurality of BRRS antenna ports to the UE from the cellular base station using a respective antenna port.
  • the functionality 1200 can also include signaling the transceiver to indicate the plurality of antenna ports to a UE using an antenna port configuration of a Demodulation Reference Signal (DMRS) of a Physical Downlink Control Channel (xPDCCH) that is associated with the BRRS transmission.
  • DMRS Demodulation Reference Signal
  • xPDCCH Physical Downlink Control Channel
  • the functionality 1200 can also include mapping the BRRS transmission between an extended Physical Downlink Control Channel (xPDCCH) and an extended Physical Downlink Shared Channel (xPDSCH) or before the xPDCCH.
  • xPDCCH extended Physical Downlink Control Channel
  • xPDSCH extended Physical Downlink Shared Channel
  • the functionality 1200 can include identifying at least one transmission beam (Tx) to be used for sending transmissions to a User Equipment (UE).
  • Tx transmission beam
  • UE User Equipment
  • the functionality 1200 can include signaling a transceiver associated with the cellular base station to send a Beam Refinement Reference Signal (BRRS) transmission to the UE, wherein the BRRS transmission uses a BRRS subcarrier spacing, and wherein the BRRS subcarrier spacing is larger than a subcarrier spacing of one more following Orthogonal Frequency Division Multiplexing (OFDM) symbols that follow the BRRS transmission.
  • BRRS Beam Refinement Reference Signal
  • the functionality 1200 can include signaling the transceiver to send a first Channel State Information Reference Signal (CSI-RS) symbol to the UE using a first Tx beam and signaling the transceiver to send a second Channel State Information Reference Signal (CSI-RS) symbol using a second Tx beam.
  • CSI-RS Channel State Information Reference Signal
  • the functionality 1200 can include signaling the transceiver associated with the cellular base station to send a BRRS format indicator to the UE in Downlink Control Information (DO), wherein the BRRS format indicator indicates a format to which the BRRS transmission conforms.
  • DO Downlink Control Information
  • FIG. 13 provides an example illustration of a mobile device, such as a user equipment (UE), a mobile station (MS), a mobile wireless device, a mobile communication device, a tablet, a handset, a CIoT device, or other type of wireless device.
  • the mobile 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 (WW AN) access point.
  • the mobile device can be configured to communicate using at least one wireless
  • the mobile device can communicate using separate antennas for each wireless communication standard or shared antennas for multiple wireless communication standards.
  • the mobile device can communicate in a wireless local area network (WLAN), a wireless personal area network (WPAN), and/or a WWAN.
  • WLAN wireless local area network
  • WPAN wireless personal area network
  • WWAN Wireless Wide Area Network
  • the mobile 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 mobile device transmits via the one or more antennas and demodulate signals that the mobile device receives via the one or more antennas.
  • the mobile device can include a storage medium.
  • the storage medium can be associated with and/or communication with the application processor, the graphics processor, the display, the non-volatile memory port, and/or internal memory.
  • the application processor and graphics processor are storage mediums.
  • FIG. 13 also provides an illustration of a microphone and one or more speakers that can be used for audio input and output from the mobile 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 mobile device.
  • a keyboard can be integrated with the mobile device or wirelessly connected to the wireless device to provide additional user input.
  • a virtual keyboard can also be provided using the touch screen.
  • FIG. 14 provides an example illustration of a user equipment (UE) device
  • the UE device 1400 such as a wireless device, a mobile station (MS), a mobile wireless device, a mobile communication device, a tablet, a handset, a CIoT device, or other type of wireless device.
  • the UE device 1400 can include one or more antennas configured to
  • the UE device 1400 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 UE device 1400 can communicate using separate antennas for each wireless communication standard or shared antennas for multiple wireless communication standards.
  • the UE device 1400 can communicate in a wireless local area network (WLAN), a wireless personal area network (WPAN), and/or a WW AN.
  • the UE device 1400 may include application circuitry 1402, baseband circuitry 1404, Radio Frequency (RF) circuitry 1406, front-end module (FEM) circuitry 1408 and one or more antennas 1410, coupled together at least as shown.
  • application circuitry 1402 baseband circuitry 1404, Radio Frequency (RF) circuitry 1406, front-end module (FEM) circuitry 1408 and one or more antennas 1410, coupled together at least as shown.
  • RF Radio Frequency
  • FEM front-end module
  • the application circuitry 1402 may include one or more application processors.
  • the application circuitry 1402 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 memory/storage (e.g., storage medium 1412) and may be configured to execute instructions stored in the memory /storage (e.g., storage medium 1412) to enable various applications and/or operating systems to run on the system.
  • the baseband circuitry 1404 may include circuitry such as, but not limited to, one or more single-core or multi-core processors.
  • the baseband circuitry 1404 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 1406 and to generate baseband signals for a transmit signal path of the RF circuitry 1406.
  • Baseband processing circuity 1404 may interface with the application circuitry 1402 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 1406.
  • the baseband circuitry 1404 may include a second generation (2G) baseband processor 1404a, third generation (3G) baseband processor 1404b, fourth generation (4G) baseband processor 1404c, and/or other baseband processor(s) 1404d for other existing generations, generations in development or to be developed in the future (e.g., fifth generation (5G), 6G, etc.).
  • the baseband circuitry 1404 e.g., one or more of baseband processors 1404a-d
  • the radio control functions may include, but are not limited to, signal
  • modulation/demodulation circuitry of the baseband circuitry 1404 may include Fast-Fourier Transform (FFT), precoding, and/or constellation
  • encoding/decoding circuitry of the baseband circuitry 1404 may include convolution, tail-biting convolution, turbo, Viterbi, and/or Low Density Parity Check (LDPC) encoder/decoder functionality.
  • LDPC Low Density Parity Check
  • Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and may include other suitable functionality in other embodiments.
  • the baseband circuitry 1404 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.
  • EUTRAN evolved universal terrestrial radio access network
  • a central processing unit (CPU) 1404e of the baseband circuitry 1404 may be configured to run elements of the protocol stack for signaling of the PHY, MAC, RLC, PDCP and/or RRC layers.
  • the baseband circuitry may include one or more audio digital signal processor(s) (DSP) 1404f.
  • the audio DSP(s) 1404f may include elements for
  • compression/decompression and echo cancellation 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.
  • some or all of the constituent components of the baseband circuitry 1404 and the application circuitry 1402 may be implemented together such as, for example, on a system on a chip (SOC).
  • SOC system on a chip
  • the baseband circuitry 1404 may provide for communication compatible with one or more radio technologies.
  • the baseband circuitry 1404 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).
  • EUTRAN evolved universal terrestrial radio access network
  • WMAN wireless metropolitan area networks
  • WLAN wireless local area network
  • WPAN wireless personal area network
  • multi-mode baseband circuitry Embodiments in which the baseband circuitry 1404 is configured to support radio communications of more than one wireless protocol.
  • the RF circuitry 1406 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium.
  • the RF circuitry 1406 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network.
  • RF circuitry 1406 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 1408 and provide baseband signals to the baseband circuitry 1404.
  • RF circuitry 1406 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 1404 and provide RF output signals to the FEM circuitry 1408 for transmission.
  • the RF circuitry 1406 may include a receive signal path and a transmit signal path.
  • the receive signal path of the RF circuitry 1406 may include mixer circuitry 1406a, amplifier circuitry 1406b and filter circuitry 1406c.
  • the transmit signal path of the RF circuitry 1406 may include filter circuitry 1406c and mixer circuitry 1406a.
  • RF circuitry 1406 may also include synthesizer circuitry 1406d for synthesizing a frequency for use by the mixer circuitry 1406a of the receive signal path and the transmit signal path.
  • the mixer circuitry 1406a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 1408 based on the synthesized frequency provided by synthesizer circuitry 1406d.
  • the amplifier circuitry 1406b may be configured to amplify the down-converted signals and the filter circuitry 1406c 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 1404 for further processing.
  • the output baseband signals may be zero-frequency baseband signals, although other types of baseband signals may be used.
  • mixer circuitry 1406a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect.
  • the mixer circuitry 1406a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 1406d to generate RF output signals for the FEM circuitry 1408.
  • the baseband signals may be provided by the baseband circuitry 1404 and may be filtered by filter circuitry 1406c.
  • the filter circuitry 1406c may include a low-pass filter (LPF), although the scope of the embodiments is not limited in this respect.
  • the mixer circuitry 1406a of the receive signal path and the mixer circuitry 1406a of the transmit signal path may include two or more mixers and may be arranged for quadrature down-conversion and/or up-conversion respectively.
  • the mixer circuitry 1406a of the receive signal path and the mixer circuitry 1406a of the transmit signal path may include two or more mixers and may be arranged for image rejection (e.g., Hartley image rejection).
  • the mixer circuitry 1406a of the receive signal path and the mixer circuitry 1406a may be arranged for direct down-conversion and/or direct up-conversion, respectively.
  • the mixer circuitry 1406a of the receive signal path and the mixer circuitry 1406a of the transmit signal path may be configured for super-heterodyne operation.
  • 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.
  • the output baseband signals and the input baseband signals may be digital baseband signals. In these alternate
  • the RF circuitry 1406 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 1404 may include a digital baseband interface to communicate with the RF circuitry 1406.
  • ADC analog-to-digital converter
  • DAC digital-to-analog converter
  • a separate radio IC circuitry may be provided for processing signals for each spectrum, although the scope of the
  • the synthesizer circuitry 1406d may be a fractional -
  • synthesizer circuitry 1406d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.
  • the synthesizer circuitry 1406d may be configured to synthesize an output frequency for use by the mixer circuitry 1406a of the RF circuitry 1406 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 1406d may be a fractional N/N+l synthesizer.
  • frequency input may be provided by a voltage controlled oscillator (VCO), although other types of devices may provide the frequency input.
  • VCO voltage controlled oscillator
  • Divider control input may be provided by either the baseband circuitry 1404 or the applications processor 1402 depending on the desired output frequency.
  • a divider control input (e.g., N) may be determined from a look-up table based on a channel indicated by the applications processor 1402.
  • Synthesizer circuitry 1406d of the RF circuitry 1406 may include a divider, a delay -locked loop (DLL), a multiplexer and a phase accumulator.
  • the divider may be a dual modulus divider (DMD) and the phase accumulator may be a digital phase accumulator (DP A).
  • 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.
  • the DLL may include a set of cascaded, tunable, delay elements, a phase detector, a charge pump and a D-type flip-flop.
  • 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.
  • Nd is the number of delay elements in the delay line.
  • synthesizer circuitry 1406d 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.
  • the output frequency may be a LO frequency (fLO).
  • the RF circuitry 1406 may include an IQ/polar converter.
  • FEM circuitry 1408 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 1410, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 1406 for further processing.
  • FEM circuitry 1408 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 1406 for transmission by one or more of the one or more antennas 1410.
  • the FEM circuitry 1408 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 1406).
  • LNA low-noise amplifier
  • the transmit signal path of the FEM circuitry 1408 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 1406), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 1410.
  • PA power amplifier
  • the UE device 1400 may include additional elements such as, for example, memory/storage, display (e.g., touch screen), camera, antennas, keyboard, microphone, speakers, sensor, and/or input/output (I/O) interface.
  • display e.g., touch screen
  • I/O input/output
  • FIG. 15 illustrates a diagram 1500 of a node 1510 (e.g., eNB and/or a
  • the node can include a base station (BS), a Node B (NB), an evolved Node B (eNB), a baseband unit (BBU), a remote radio head (RRH), a remote radio equipment (RRE), a remote radio unit (RRU), or a central processing module (CPM).
  • the node can be a Serving GPRS Support Node.
  • the node 1510 can include a node device 1512.
  • the node device 1512 or the node 1510 can be configured to communicate with the wireless device 1520.
  • the node device 1512 can be configured to implement technologies described herein.
  • the node device 1512 can include a processing module 1514 and a transceiver module 1516.
  • the node device 1512 can include the transceiver module 1516 and the processing module 1514 forming a circuitry for the node 1510.
  • the transceiver module 1516 and the processing module 1514 can form a circuitry of the node device 1512.
  • the processing module 1514 can include one or more processors and memory.
  • the processing module 1522 can include one or more application processors.
  • the transceiver module 1516 can include a transceiver and one or more processors and memory.
  • the transceiver module 1516 can include a baseband processor.
  • the wireless device 1520 can include a transceiver module 1524 and a processing module 1522.
  • the processing module 1522 can include one or more processors and memory. In one embodiment, the processing module 1522 can include one or more application processors.
  • the transceiver module 1524 can include a transceiver and one or more processors and memory. In some examples, components of the transceiver module 1516 can be included in separate devices. For example, selected components of the transceiver module 1516 may be located in a cloud radio access network (C-RAN). In one embodiment, the transceiver module 1524 can include a baseband processor.
  • the wireless device 1520 can be configured to implement technologies described herein.
  • the node 1510 and the wireless devices 1520 can also include one or more storage mediums, such as the transceiver module 1516, 1524 and/or the processing module 1514, 1522.
  • Example 1 includes an apparatus of a User Equipment (UE), the apparatus comprising one or more processors and memory configured to: identify a Beam
  • BRRS Refinement Reference Signal
  • OFDM Orthogonal Frequency Division Multiplexing
  • Rx Reception
  • example 2 the subject matter of example 1 or any of the examples described herein may further include that the BRRS subcarrier spacing is predefined in a specification or is configured by the cellular base station via one or more of: Downlink Control Information (DCI), master information broadcasting (MIB), system information broadcasting (SIB), or radio resource control (RRC) signaling.
  • DCI Downlink Control Information
  • MIB master information broadcasting
  • SIB system information broadcasting
  • RRC radio resource control
  • Af BRRS the BRRS subcarrier spacing
  • example 4 the subject matter of example 1, 2, 3, or any of the examples described herein may further include that the BRRS transmission comprises four BRRS OFDM symbols and the one or more processors and memory are further configured to refine up to four Rx beams based the four BRRS OFDM symbols.
  • example 5 the subject matter of example 1, 2, 3, or any of the examples described herein may further include that the BRRS transmission comprises eight BRRS OFDM symbols and the one or more processors and memory are further configured to: refine a first Rx beam based on four first BRRS OFDM symbols of the eight BRRS OFDM symbols; and refine a second Rx beam based on four second BRRS OFDM symbols of the eight BRRS OFDM symbols.
  • example 6 the subject matter of example 5 or any of the examples described herein may further include that the one or more processors and memory are further configured to: process a first Channel State Information Reference Signal (CSI- RS) symbol that is received using the first Rx beam; and process a second Channel State Information Reference Signal (CSI-RS) symbol and Physical Downlink Shared Channel (PDSCH) data that are received using the second Rx beam.
  • CSI- RS Channel State Information Reference Signal
  • PDSCH Physical Downlink Shared Channel
  • example 7 the subject matter of example 1, 2, 3, or any of the examples described herein may further include that the BRRS transmission comprises eight BRRS OFDM symbols and the one or more processors and memory are further configured to refine up to eight Rx beams based on the eight BRRS OFDM symbols.
  • example 8 the subject matter of example 7 or any of the examples described herein may further include that the one or more processors and memory are further configured to: take BRRS measurements using one or more initial Rx beams; signal the transceiver to send the BRRS measurements to the cellular base station; and refine the up-to-eight Rx beams using one or more initial Rx beams.
  • the subject matter of example 1, 2, 3, 4, 5, 6, 7, 8, or any of the examples described herein may further include that the BRRS transmission comprises one or more BRRS OFDM symbols and the one or more BRRS symbols contain a plurality of BRRS antenna ports.
  • example 10 the subject matter of example 9 or any of the examples described herein may further include that the one or more processors and memory are further configured to: measure a BRRS port group, wherein the BRRS port group includes two antenna ports of the plurality of antenna ports, and wherein the two antenna ports are frequency division multiplexed or code division multiplexed; and refine the Rx beam based on the measuring of the BRRS port group.
  • the one or more processors and memory are further configured to: measure a BRRS port group, wherein the BRRS port group includes two antenna ports of the plurality of antenna ports, and wherein the two antenna ports are frequency division multiplexed or code division multiplexed; and refine the Rx beam based on the measuring of the BRRS port group.
  • example 11 the subject matter of example 10 or any of the examples described herein may further include that the two antenna ports are mapped to all subcarriers used for the BRRS transmission and are generated based on different cyclic shifts.
  • example 12 the subject matter of example 9 or any of the examples described herein may further include that the plurality of antenna ports is indicated by an antenna port configuration of a Demodulation Reference Signal (DMRS) of an extended Physical Downlink Control Channel (xPDCCH) that is associated with the BRRS transmission.
  • DMRS Demodulation Reference Signal
  • xPDCCH extended Physical Downlink Control Channel
  • example 13 the subject matter of example 1, 2, 3, 4, 5, 6, 7, 8, or any of the examples described herein may further include that the BRRS transmission comprises one or more BRRS OFDM symbols and the BRRS transmission is mapped in an
  • Orthogonal Frequency Division Multiple Access symbol between an extended Physical Downlink Control Channel (xPDCCH) and an extended Physical Downlink Shared Channel (xPDSCH) or is mapped in the OFDMA symbol before the xPDCCH.
  • Example 14 includes an apparatus of a cellular base station in a Multiple
  • MIMO Input Multiple Output
  • the apparatus comprising one or more processors and memory configured to: identify a base sequence to be used for a Beam Refinement Reference Signal (BRRS), wherein the base sequence is a Zadoff-Chu sequence or a Quadrature Phase Shift Keying (QPSK) sequence; identify at least one transmission beam (Tx) to be used for sending transmissions to a User Equipment (UE); and signal a transceiver associated with the cellular base station to send a Beam Refinement Reference Signal (BRRS) transmission to the UE, wherein the BRRS transmission uses a BRRS subcarrier spacing, and wherein the BRRS subcarrier spacing is larger than a subcarrier spacing of one more following Orthogonal Frequency Division Multiplexing (OFDM) symbols that follow the BRRS transmission.
  • OFDM Orthogonal Frequency Division Multiplexing
  • example 15 the subject matter of example 15 or any of the examples described herein may further include that the BRRS subcarrier spacing is predefined in a specification or the one or more processors and memory are further configured to configure the BRRS subcarrier spacing via Downlink Control Information (DCI), master information broadcasting (MIB), system information broadcasting (SIB), or radio resource control (RRC) signaling.
  • DCI Downlink Control Information
  • MIB master information broadcasting
  • SIB system information broadcasting
  • RRC radio resource control
  • Af BRRS the BRRS subcarrier spacing
  • example 17 the subject matter of example 14, 15, 16, or any of the examples described herein may further include that the BRRS transmission comprises four BRRS OFDM symbols.
  • example 18 the subject matter of example 14, 15, 16, or any of the examples described herein may further include that the BRRS transmission comprises eight BRRS OFDM symbols.
  • example 19 the subject matter of example 19 or any of the examples described herein may further include that the one or more processors and memory are further configured to: signal the transceiver to send a first Channel State Information Reference Signal (CSI-RS) symbol to the UE using a first Tx beam; and signal the transceiver to send a second Channel State Information Reference Signal (CSI-RS) symbol using a second Tx beam.
  • CSI-RS Channel State Information Reference Signal
  • example 20 the subject matter of example 14, 15, 16, 17, 18, 19, or any of the examples described herein may further include that the BRRS transmission comprises one or more BRRS OFDM symbols and the one or more BRRS symbols contain a plurality of BRRS antenna ports.
  • example 21 the subject matter of example 20 or any of the examples described herein may further include that the one or more processors and memory are further configured to: signal the transceiver to frequency-division multiplexed a BRRS sequence for each BRRS antenna port of the plurality of BRRS antenna ports; and signal the transceiver to send each BRRS antenna port of the plurality of BRRS antenna ports to the UE from the cellular base station using a respective antenna port.
  • example 22 the subject matter of example 20 or any of the examples described herein may further include that the one or more processors and memory are further configured to: signal the transceiver to indicate the plurality of antenna ports to the UE using an antenna port configuration of a Demodulation Reference Signal (DMRS) of a Physical Downlink Control Channel (xPDCCH) that is associated with the BRRS transmission.
  • DMRS Demodulation Reference Signal
  • xPDCCH Physical Downlink Control Channel
  • example 23 the subject matter of example 14 or any of the examples described herein may further include that the BRRS transmission comprises one or more BRRS OFDM symbols and the one or more processors and memory are further configured to map the BRRS transmission between an extended Physical Downlink Control Channel (xPDCCH) and an extended Physical Downlink Shared Channel (xPDSCH) or before the xPDCCH.
  • xPDCH extended Physical Downlink Control Channel
  • xPDSCH extended Physical Downlink Shared Channel
  • example 24 the subject matter of example 14, 15, 16, 17, 18, 19, 20, 21,
  • the one or more processors and memory are further configured to signal the transceiver associated with the cellular base station to send a BRRS format indicator to the UE in Downlink Control Information (DO), wherein the BRRS format indicator indicates a format to which the BRRS transmission conforms.
  • DO Downlink Control Information
  • BRRS Beam Refinement Reference Signal
  • example 26 the subject matter of example 25 or any of the examples described herein may further include that the computer-readable medium further contains instructions thereon which, when executed by one or more processors, perform the following:
  • example 27 the subject matter of example 25, 26, or any of the examples described herein may further include that the computer-readable medium further contains instructions thereon which, when executed by one or more processors, perform the following: refining a first Rx beam based on four first BRRS OFDM symbols included in the BRRS transmission; and refining a second Rx beam based on four second BRRS OFDM symbols included in the BRRS transmission.
  • example 28 the subject matter of example 25 or any of the examples described herein may further include that the computer-readable medium further contains instructions thereon which, when executed by one or more processors, perform the following: refining up to eight Rx beams based on eight BRRS OFDM symbols included in the BRRS transmission.
  • BRRS Beam Refinement Reference Signal
  • example 30 the subject matter of example 29 or any of the examples described herein may further include that the means for refining an Rx beam further comprises:
  • example 31 the subject matter of example 29 or any of the examples described herein may further include that the means for refining an Rx beam further comprises: a means for refining a first Rx beam based on four first BRRS OFDM symbols included in the BRRS transmission; and a means for refining a second Rx beam based on four second BRRS OFDM symbols included in the BRRS transmission.
  • BRRS Beam Refinement Reference Signal
  • example 33 the subject matter of example 32 or any of the examples described herein may further include that the BRRS transmission comprises four BRRS OFDM symbols and the one or more processors and memory are further configured to refine up to four Rx beams based the four BRRS OFDM symbols.
  • example 34 the subject matter of example 32 or any of the examples described herein may further include that the BRRS transmission comprises eight BRRS OFDM symbols and the one or more processors and memory are further configured to: refine a first Rx beam based on four first BRRS OFDM symbols of the eight BRRS
  • CSI-RS Channel State Information Reference Signal
  • PDSCH Physical Downlink Shared Channel
  • the subject matter of example 32 or any of the examples described herein may further include that the BRRS transmission comprises eight BRRS OFDM symbols and the one or more processors and memory are further configured to: refine up to eight Rx beams based on the eight BRRS OFDM symbols; take BRRS measurements using one or more initial Rx beams; signal the transceiver to send the BRRS measurements to the cellular base station; and refine the up-to-eight Rx beams using one or more initial Rx beams.
  • example 36 the subject matter of example 32, 33, 34, 35, or any of the examples described herein may further include that the BRRS transmission comprises one or more BRRS OFDM symbols and the one or more BRRS symbols contain a plurality of BRRS antenna ports, and that the one or more processors and memory are further configured to: measure a BRRS port group, wherein the BRRS port group includes two antenna ports of the plurality of antenna ports, and wherein the two antenna ports are frequency division multiplexed or code division multiplexed; and refine the Rx beam based on the measuring of the BRRS port group.
  • example 37 the subject matter of example 36 or any of the examples described herein may further include that the plurality of antenna ports is indicated by an antenna port configuration of a Demodulation Reference Signal (DMRS) of an extended Physical Downlink Control Channel (xPDCCH) that is associated with the BRRS transmission.
  • DMRS Demodulation Reference Signal
  • xPDCCH extended Physical Downlink Control Channel
  • BRRS Beam Refinement Reference Signal
  • example 39 the subject matter of example 38 or any of the examples described herein may further include that the BRRS transmission comprises eight BRRS OFDM symbols, and that the one or more processors and memory are further configured to: signal the transceiver to send a first Channel State Information Reference Signal (CSI- RS) symbol to the UE using a first Tx beam; and signal the transceiver to send a second Channel State Information Reference Signal (CSI-RS) symbol using a second Tx beam.
  • CSI- RS Channel State Information Reference Signal
  • CSI-RS Channel State Information Reference Signal
  • the subject matter of example 38, 39, or any of the examples described herein may further include that the BRRS transmission comprises one or more BRRS OFDM symbols and the one or more BRRS symbols contain a plurality of BRRS antenna ports, and wherein the one or more processors and memory are further configured to: signal the transceiver to frequency-division multiplexed a BRRS sequence for each BRRS antenna port of the plurality of BRRS antenna ports; and signal the transceiver to send each BRRS antenna port of the plurality of BRRS antenna ports to the UE from the cellular base station using a respective antenna port.
  • example 41 the subject matter of example 40 or any of the examples described herein may further include that the one or more processors and memory are further configured to: signal the transceiver to indicate the plurality of antenna ports to the UE using an antenna port configuration of a Demodulation Reference Signal (DMRS) of a Physical Downlink Control Channel (xPDCCH) that is associated with the BRRS transmission.
  • DMRS Demodulation Reference Signal
  • xPDCCH Physical Downlink Control Channel
  • example 42 the subject matter of example 38 or any of the examples described herein may further include that the BRRS transmission comprises one or more BRRS OFDM symbols and the one or more processors and memory are further configured to map the BRRS transmission between an extended Physical Downlink Control Channel (xPDCCH) and an extended Physical Downlink Shared Channel (xPDSCH) or before the xPDCCH.
  • xPDCH extended Physical Downlink Control Channel
  • xPDSCH extended Physical Downlink Shared Channel
  • example 43 the subject matter of example 38, 39, 40, 41, or any of the examples described herein may further include that the one or more processors and memory are further configured to signal the transceiver associated with the cellular base station to send a BRRS format indicator to the UE in Downlink Control Information (DCI), wherein the BRRS format indicator indicates a format to which the BRRS transmission conforms.
  • DCI Downlink Control Information
  • 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, a transitory or 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.
  • a non-transitory computer readable storage medium can be a computer readable storage medium that does not include signal.
  • the computing device may include a processor, a storage medium readable by the processor (including volatile and non-volatile 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).
  • a transceiver module i.e., transceiver
  • a counter module i.e., counter
  • a processing module i.e., processor
  • a clock module i.e., clock
  • timer module i.e., timer
  • 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
  • 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.
  • ASIC Application Specific Integrated Circuit
  • the circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules.
  • circuitry may include logic, at least partially operable in hardware.
  • the word “or” indicates an inclusive disjunction.
  • the phrase “A or B” represents an inclusive disjunction of exemplary conditions A and B. Hence, “A or B” is false only if both condition A is false and condition B is false. When condition A is true and condition B is also true, “A or B” is also true. When condition A is true and condition B is false, “A or B” is true. When condition B is true and condition A is false, “A or B” is true. In other words, the term “or,” as used herein, should not be construed as an exclusive disjunction. The term “xor” is used where an exclusive disjunction is intended.
  • processor can include general-purpose processors, specialized processors such as VLSI, FPGAs, and other types of specialized processors, as well as base-band processors used in transceivers to send, receive, and process wireless communications.
  • modules can be implemented as a hardware circuit (e.g., an application-specific integrated circuit (ASIC)) comprising custom VLSI circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components.
  • a module can also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like.
  • Modules can also be implemented in software for execution by various types of processors.
  • An identified module of executable code can, for instance, comprise one or more physical or logical blocks of computer instructions, which can, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module do not have to be physically located together, but can comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module.
  • a module of executable code can be a single instruction, or many instructions, and can even be distributed over several different code segments, among different programs, and across several memory devices.
  • operational data can be identified and illustrated herein within modules, and can be embodied in any suitable form and organized within any suitable type of data structure. The operational data can be collected as a single data set, or can be distributed over different locations including over different storage devices, and can exist, at least partially, merely as electronic signals on a system or network.
  • the modules can be passive or active, including agents operable to perform desired functions.
  • processor can include general purpose processors, specialized processors such as VLSI, FPGAs, and other types of specialized processors, as well as base band processors used in transceivers to send, receive, and process wireless communications.

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Abstract

Technologies described herein provide mechanisms and formats for Beam Refinement Reference Signals (BRRSs) and downlink signaling for BRRSs. A BRRS transmission can be sent from a cellular base station and received via a transceiver at a UE. The BRRS transmission can uses a BRRS subcarrier spacing that is larger than a subcarrier spacing of the one more data Orthogonal Frequency Division Multiplexing (OFDM) symbols that follow the BRRS transmission. The UE can refine one or more Reception (Rx) beams based on the BRRS transmission and use the refined Rx beam to receive the data OFDM symbols.

Description

MECHANISMS FOR BEAM SWITCHING AND REFINEMENT IN CELLULAR SYSTEMS
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). Standards and protocols that use orthogonal frequency- division multiplexing (OFDM) for signal transmission include the third generation partnership project (3 GPP) 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, the node in an
Evolved Universal Terrestrial Radio Access Network (E-UTRAN) system is referred to as an eNode B (also commonly denoted as evolved Node Bs, enhanced Node Bs, eNodeBs, or eNBs), 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.
[0003] In LTE, data can be transmitted from the eNodeB to the UE via a physical downlink shared channel (PDSCH). A physical uplink control channel (PUCCH) can be used to acknowledge that data was received. Downlink and uplink channels or transmissions can use time-division duplexing (TDD) or frequency-division duplexing (FDD).
[0004] In a massive Multiple-Input Multiple-Output (MIMO) system, a downlink
(DL) signal may be transmitted using Transmitting (Tx) beamforming and received using Receiving (Rx) beamforming. As a result of User Equipment (UE) rotation, movement, and Doppler frequency shift, the Tx beam that is preferable at a given time may change (e.g., from one Tx beam to another Tx beam). In addition, within one Tx beam, an Rx beam that is preferable may also change. BRIEF DESCRIPTION OF THE DRAWINGS
[0005] 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:
[0006] FIG. 1 illustrates an example in which a subcarrier spacing( AfBRRS) of
BRRS symbols is four times a subcarrier spacing ( Δ );
[0007] FIG. 2 illustrates a BRRS transmission format (format 1) in accordance with an example;
[0008] FIG. 3 illustrates a BRRS transmission format (format 2) in accordance with an example;
[0009] FIG. 4 illustrates a BRRS transmission format (format 3) in accordance with an example;
[0010] FIG. 5 shows an example structure for a BRRS that has a subcarrier spacing of 4Αΐ in accordance with an example;
[0011] FIG. 6 illustrates one example for a beam pattern of a first antenna port in accordance with an example;
[0012] FIG. 7 illustrates a beam structure (Format la) in which a first Tx beam can be used for current downlink data and control transmission in accordance with an example;
[0013] FIG. 8 illustrates a beam structure (Format 2a) with which an eNB may switch a Tx beam gradually;
[0014] FIG. 9 illustrates a beam structure (Format 3a) in accordance with an example;
[0015] FIG. 10 illustrates a beam structure (Format 4a) in accordance with an example;
[0016] FIG. 11 illustrates functionality of User Equipment (UE) in accordance with an example;
[0017] FIG. 12 illustrates functionality of a cellular base station in accordance with an example;
[0018] FIG. 13 provides an example illustration of a wireless device in accordance with an example; [0019] FIG. 14 provides an example illustration of a user equipment (UE) device, such as 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; and
[0020] FIG. 15 illustrates a diagram of a node (e.g., eNB and/or a Serving GPRS Support Node) and a wireless device (e.g., UE) in accordance with an example.
[0021] 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 is thereby intended. DETAILED DESCRIPTION
[0022] Before some embodiments are disclosed and described, it is to be understood that the claimed subject matter is not limited to the particular structures, process operations, 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 operations and do not necessarily indicate a particular order or sequence.
[0023] 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.
[0024] Beamforrning gain is especially beneficial for high frequency band communication systems. An optimum Transmission/Reception (Tx/Rx) beam pair can be searched based on a beam reference signal (BRS). However, the BRS is a broadcasting signal and is generally transmitted in a periodic way to traverse all Tx beams. Sometimes, a User Equipment (UE) may have to wait until the next BRS subframe in order to achieve Rx beam refinement. Under some circumstances, the resulting delay in Rx beam refinement may adversely affect UE reception performance.
[0025] In addition, the UE may only report the top N (e.g., N=8) Tx beams' receiving power (BRS-RP); the reported BRS-RP for the top N Tx beams may be measured using the same or different Rx beams. Based on the BRS-RP report received from the UE, an evolved Node B (eNB) or another type of cellular base station can derive candidate Tx beams for the UE to measure channel state information (CSI). The recommended Tx beam from UE's CSI report may be different from the best Tx beam reported in the most recent BRS-RP.
[0026] After the eNB receives CSI-RS reports from the UE, the eNB can determine the exact beamforming weight for data transmission. How the beamforming weight is determined depends on the eNB implementation. For example, the eNB can perform beam interpolation to get higher beamforming gain or can beam to a different direction for diversity gain. The eNB can also pair the UE and perform Multi-User (MU) Multiple-Input Multiple-Output (MIMO) precoding for Downlink (DL) MU MIMO transmission. Such operations at the eNB can result in a Tx beamforming direction slightly different from the beam direction used in BRS or CSI-RS training.
[0027] If layer-one (LI) signaling is not used to indicate which Tx beam the eNB has used for the Physical Downlink Shared Channel (PDSCH), the UE may reply on the Rx beam which the UE used to measure the reported best Tx beam in the BRS-RP report. This Rx beam may be sub-optimal for the Tx beam on the PDSCH.
[0028] The beam width used in BRS training can be narrow or wide. The beam width can be chosen based on factors such as as beamforming training overhead, delay, and coverage. Additional factors that may influence the choice of beam width include details of the eNB's implementation, such as the number of antennas and the Radio Frequency (RF) architecture. If the eNB uses a relatively wide beam for BRS training, UE Rx beamforming trained through repeated BRS transmission will likely not be very accurate. Some refinements to Reference Signals (RSs) described herein provide additional UE Rx beamforming gain.
[0029] In another scenario, an eNB may have to to switch between spatially uncorrelated Tx beams. In order to help a UE to correctly receive a spatially un-correlated Tx beam, some layer-one signaling or reference signals are described herein so that Rx beam adjustment at the UE can be accomplished accordingly.
[0030] In order to achieve faster Rx beam refinement to improve a match of Tx and Rx beams according to the channel in a timely manner, a beam refinement reference signal (BRRS) can be used. The BRRS can be inserted before a data channel such as a PDSCH or a physical uplink shared channel (PUSCH). In this way, a receiver can refine an Rx beam based on the BRRS before data reception. In addition, an eNB or a UE can gradually update a Tx or Rx beam to support intra Transmission Point (TP) beam mobility. The present disclosure provides some examples of BRRS structures that can help an eNB switch between spatially uncorrelated Tx beams (e.g., by providing more frequent opportunities for beam refinement). The present disclosure also provides examples of detailed physical (PHY) structures for the BRRS, including sequence generation, port definition, and resource mapping.
[0031] Due to the consecutive transmission of the BRRS and data (e.g., in a
PDSCH or PUSCH), the Rx beam for data reception can be refined without layer-one signaling for a Tx beam that may gradually change. As a result, the Rx beam forming gain can potentially be obtained in real time. However, there is a tradeoff between the granularity of the Rx beam refinement and the overhead of the BRRS. If more Rx beam candidates are to be scanned before data reception, more BRRS symbols are transmitted and overhead is therefore increased.
[0032] In some examples of the present disclosure, the UE can start the beam refinement phase using the most recent refined Rx beam and the eNB can be configured not to deviate far from the best Tx candidate beams. This offers advantages over the initial beam acquisition phase in which the UE may search Tx/Rx beam pairs without any prior knowledge. Furthermore, unlike the initial beam acquisition phase, the full bandwidth can be used for the BRRS in some example of the present disclosure.
Accordingly, this disclosure presents a wider subcarrier spacing that can be used for the BRRS. When a wider subcarrier spacing is used for the BRRS, a candidate Rx beam search consumes less overhead.
[0033] In an Orthogonal Frequency Division Multiplexing (OFDM) system, the signal subcarrier spacing is inversely proportional to the signal time duration. The subcarrier spacing of the BRRS can be larger than that of the following data OFDM symbols (e.g., PDSCH or PUCCH) by a predefined factor so that the total length of the BRRS in the time domain is reduced by the predefined factor. This reduction in the total length or duration of the BRRS enables more Rx beam candidates to be scanned during the limited time period.
[0034] The present disclosure provides several examples of BRRS transmission formats. In one example (BRRS format 1), a BRRS signal structure with a subcarrier spacing that is four times the sub-carrier spacing of the data OFDM symbols can be used (i.e., the predefined factor is 4). Four BRRS OFDM symbols can be used for the BRRS. One Tx beam can be applied to the four BRRS OFDM symbols.
[0035] In another example (BRRS format 2), the BRRS signal structures can have a subcarrier spacing that is four times the sub-carrier spacing of the data OFDM symbols can be used (i.e., the predefined factor is 4). Eight BRRS OFDM symbols can be used for the BRRS. The eNB may use a first Tx beam for the first four OFDM symbols (of the eight BRRS OFDM symbols) and a second Tx beam for the second four OFDM symbols (of the eight BRRS OFDM symbols). The UE can refine the first Rx beam based on the first four OFDM symbols and the second Rx beam based on the second four OFDM symbols.
[0036] In another example (BRRS format 3), the BRRS signal structures can have a subcarrier spacing that is four times the sub-carrier spacing of the data OFDM symbols can be used (i.e., the predefined factor is 4). Eight BRRS OFDM symbols can be used for the BRRS. One Tx beam can be applied to the eight BRRS OFDM symbols.
[0037] A beam refinement reference signal (BRRS) enabling/triggering field
(e.g., using 1 or 2 bits) can be included in related downlink control information (DCI). A UE can start receiving the data samples (e.g., extended PDSCH (xPDSCH) or extended PUSCH (xPUSCH)) following an extended Physical Downlink Control Channel (xPDCCH) using the same reception beam that was used to receive the xPDCCH. At the same time, the UE can also attempt to decode the DCI. If BRRS enabling/triggering field in the DCI indicates to the UE that there is a BRRS followed by data OFDM symbols, the UE can start Rx beam refinement using those BRRS symbols and the resulting refined Rx beam can be used to receive the data OFDM symbols. Otherwise, the UE can simply use the most current Rx beam to receive the data OFDM symbols. In one example, if the enabling of the BRRS is configured by the DCI of a previous subframe or upper layer signaling, the BRRS may be transmitted before a control channel (e.g., xPDCCH) and the UE can use the current Rx beam to receive control channel.
A BRRS structure with wider subcarrier spacing [0038] In one example, the subcarrier spacing AfBRRS of the BRRS can be m times larger than the data OFDM symbols in order to reduce the duration of BRRS symbols in the time domain so that more BRRS symbols can be transmitted within a limited time period, thereby providing more opportunities for beam refinement. The subcarrier spacing of the OFDM data symbol(s) that follow the BRRS symbols can be represented as Af . In some examples, AfBRRS can equal a predefined coefficient multiplied by Af . In one example, the subcarrier spacing for the BRRS OFDM symbols can be fixed in a specification (e.g., AfBRRS = 4Af such that m=4).
[0039] In another example, a subcarrier-spacing extension indicator can be configured by the downlink control information (DO) or the higher layers via master information broadcasting (MIB), system information broadcasting (SIB), or radio resource configuration (RRC) signaling. The subcarrier-spacing extension indicator can indicate a coefficient that can be multiplied by Af to produce AfBRRS . The number of bits N.f used by the subcarrier-spacing extension indicator can be equal to [log2 (number of AfBRRS candidates)] , where [ 1 indicates the ceiling function.
An example of a two-bit subcarrier-spacing extension indicator is provided in the following table. For UEs within a MU-MIMO pair, the same BRRS subcarrier spacing can be used.
Figure imgf000009_0001
[0040] One alternative that can enable Rx beam training without increasing the BRRS sub-carrier spacing is to use a time domain replica waveform. A time domain replica signal can be generated using one non-zero symbol followed by three zero symbols in the frequency domain for each BRRS antenna port. Then eight BRRS symbols can have the same duration as two of the data OFDM symbols. Number of BRRS OFDM symbols
[0041] In one example, a number of OFDM symbols for BRRS transmission can be configured by downlink control information (DCI) or by the higher layers via MIB, SIB or Radio Resource Control (RRC) signaling or fixed in a specification (e.g. = 2 ). In this context, N^ refers to the number of data
OFDM symbols that would occupy the same amount of time as the BRRS symbols. Hence, the actual number of BRRS OFDM symbols may be larger than if the subcarrier spacing of the BRRS is enlarged. The total number of BRRS OFDM symbols can be equal to
Figure imgf000010_0001
14/" , which would allow I Rx beam candidates to be searched.
Multiple BRRS transmission formats [0042] In some circumstances, the optimal Tx/Rx beam pair may change dramatically due to a UE' s movement or a change in an environment surrounding the UE. In one example, a BRRS signal structure that provides more frequent opportunities for Rx beam refinement can be defined to support more Tx/Rx beam mobility among spatially uncorrelated Tx/Rx beam pairs. An example is illustrated in FIG. 3, where the first four BRRS symbols can be used to refine a first Rx beam around the first Rx beam and the remaining four BRRS symbols can be used to refine a second Rx beam around the second Rx beam. The first and second Rx beams can be indicated in the most recent BRS-RP report.
[0043] In one example, a 2-bit indicator can be configured by the DCI, or higher layer signaling, such as the MIB, the SIB, or RRC signaling. This 2-bit indicator can indicate whether a default BRRS transmission structure or an alternative transmission structure should be used. In this example, where "00" may indicate that no BRRS is included in a transmission, "01 " may indicate a BRRS format 1 structure, " 10" may indicate a BRRS format 2 transmission structure, and ' 1 1 ' can indicate a BRRS format 2 structure. UE assumption of Tx/Rx beams for BRRS/CSI-RS/PDSCH
[0044] For the BRRS structure format 1 , a UE may expect an eNB to send a
BRRS using the top N (e.g.) Tx beams that are measured using a first Rx beam. A single derived Rx beam can be used for Channel State Information Reference Signal (CSI-RS) reception and data reception in the following OFDM symbols (i. e. , the OFDM symbols that are sent after the BRRS).
[0045] For the BRRS structure format 2, a UE may expect an eNB to send a
BRRS using the top N (e.g.) Tx beams that are measured using either the first Rx beam or the second Rx beam. The Rx beam derived from the second Rx beam can be used for CSI-RS/data reception in the following OFDM symbols (i. e. , the OFDM symbols that are sent after the BRRS).
[0046] FIG. 1 illustrates an example in which a subcarrier spacing( AfBRRS) of
BRRS symbols is four times a subcarrier spacing ( Δ ) of the following OFDM symbols. As shown in FIG. 1, eight BRRS OFDM symbols may be inserted into a time duration that would ordinarily accommodate two data OFDM symbols. An antenna port (AP) can correspond to regions of BRRS symbols that extend over a frequency range of fBRRS. The first four BRRS symbols can be used for Rx beam refinement in one direction and the remaining four BRRS symbols can be used for Rx beam refinement in another direction.
[0047] FIG. 2 illustrates a BRRS transmission format (format 1) in accordance with an example. A BRRS transmission may be followed by a CSI-RS transmission. In a BRRS transmission conforming to BRRS transmission format 1 , BRRS symbols may be followed by a CSI-RS scheduled by control symbols (e.g., DCI). A UE may refine four Rx beam candidates around a current Rx beam #Ri based on the four consecutive BRRS symbols and derive a refined Rx beam #R2. The UE can then use the Rx beam #R2 to receive the following data OFDM symbols and the CSI-RS symbols.
[0048] FIG. 3 illustrates a BRRS transmission format (format 2) in accordance with an example. In a BRRS transmission conforming to BRRS transmission format 2, BRRS symbols may be followed by a CSI-RS scheduled by control symbols (e.g., DCI). A UE may derive one Rx beam using four consecutive BRRS symbols. As such, the UE may derive two Rx beams using eight consecutive BRRS symbols. The UE may use an Rx beam derived from the first four BRRS symbols to receive a first CSI-RS symbol and an Rx beam derived from the other four BRRS symbols to receive a second CSI-RS symbol. For data reception (e.g., of the data OFDM symbols), the UE can use the second derived Rx beam.
[0049] FIG. 4 illustrates a BRRS transmission format (format 3) in accordance with an example. In a BRRS transmission conforming to BRRS transmission format 3, BRRS symbols may be followed by a CSI-RS scheduled by control symbols (e.g., DCI). A UE may refine eight Rx beam candidates around the current Rx beam #Ri based on eight consecutive BRRS symbols and derive one refined Rx beam #R2. The UE can then use the Rx beam #R2 to receive the following data OFDM symbols and the CSI-RS symbols. In a special case, the Tx beam #72 can be the same as the Tx beam #Ti.
Beam mobility [0050] For intra-TP mobility in which a Tx/Rx beam changes gradually, the
BRRS format 1 structure with four Rx beam refinement opportunities can be used. For intra-TP mobility in which a Tx/Rx beam can switch between spatially uncorrelated beams (e.g., between two dominant channel clusters), the BRRS format 2 structure with eight Rx beam refinement opportunities can be used. For inter-TP mobility in which a Tx beam may change between beams that belong to different TPs, the BRRS format 2 structure with eight Rx beam refinement opportunities can be used. A new TP index can be indicated in the DCI. A one bit nscio can be used to indicate the new TP. A bit value of '0' for the nsciD can correspond to one TP identity (ID) configured by an upper layer. A bit value of Ί ' for the nsciD can correspond to the other TP ID configured by an upper layer. The UE can adjust the Rx beam that corresponds to one TP using the default Rx beam that was used to measure the reported BRS-RP for the other TP.
Detailed BRRS PHY structure [0051] With regard to sequence generation, the reference-signal sequence r(m) for BRRS generation can be equal to: r(m) = -^r(\ - 2 - c(2m)) + j - = (l - 2 · c(2m + 1)), (1) where m = 0,1,...,N^ 'N^ - 1 , and N^ = N (N™ = ) for downlink (uplink) transmission, N^' is the subcarrier numbers per extended PB (which is
N^ '= N^j / AfBRRS * Af ), N™ is resource block size in the frequency domain (expressed as a number of subcarriers), N^B is uplink bandwidth configuration (expressed in multiples of N^ ), and j is the imaginary square root of negative one.
[0052] The pseudo-random sequence c(i) is defined in clause 7.2 of 3GPP
Technical Specification (TS) 36.211. The cimt pseudo-random sequence generator can be initialized with equation (2) in one example:
¾t = (L»s /2j + l) - (2«SBRRS-m) + 1)- 216 + ^BRRS O (2) ns = ns mod 20
[0053] In one example, the «BRRS ID and «^brrsjd ) can be the same as «SCID and for an Uplink/Downlink (UL/DL) Demodulation Reference Signal (DMRS). In another example, the quantities «^brrsjd) , /' = 0,1 can be provided by higher layers and the «BRRS ID can be provided through the related downlink control information (DCI).
[0054] A sequence for BRRS generation can be based on the Zadoff-Chu sequence or the Quadrature Phase Shift Keying (QPSK) sequence. In one example, the BRRS sequence can be generated according to the cell Identity (ID), virtual cell ID, BSR ID, or BRS group ID as well as a subframe index or an AP index. In one example, the base sequence can be generated as the equation below:
r( ) = e;an un( )) (3)
where fu n(n) may indicate the Zadoff-Chu sequence (e.g., similar to the sequence described in section 5.5 of 3GPP Technical Specification (TS) 36.21 may be the imaginary square root of negative one, and a may be a constant value or a configurable cyclic shift configured by the AP index, Downlink Control Information (DCI), or Radio Resource Control (RRC) signaling.
[0055] In another example, a Zadoff-Chu (ZC) sequence can be used for BRRS sequence generation. In one example, a same sequence or known sequences can be transmitted in consecutive BRRS symbols of one subframe.
[0056] With regard to port definition, in one example, a resource mapping rule of a BRRS can be different from that of an existing reference signal, such as a demodulation reference signal (DMRS) or a channel state information (CSI) RS. New antenna ports wherein two ports are in one pair can be defined for BRRS transmission using both vertical and horizontal polarization of one Tx beam. In one example, the pairs of antenna ports can be p e {{31,32}, {33,34}, {35,36}, {37,38}} . In general, an eNB may have two kinds of antenna structures. In one type of antenna structure, a signal antenna panel for one sector in which one Tx beam for one direction (defined horizontally and vertically) is used to transmit one symbol. In another type of antenna structure, there are multiple antenna panels for one sector and multiple Tx beams may be used to transmit one symbol.
[0057] In another example, two BRRS ports in the same BRRS port pair (e.g. {31, 33}) can be supported by further modulating an orthogonal cover code (OCC) on the pseudo-random sequence for the two consecutive subcarriers. Port 31 can use OCC cover {1 1 } and port 33 can use OCC cover { 1 -1 } . In another example, the frequency mapping order of the eight BRRS ports maybe changed from {31, 33, 35, 37, 32, 34, 36, 38} to {31, 32, 33, 34, 35, 36, 37, 38} (e.g., in FIG. 1).
[0058] In another example, the antenna ports for the BRRS may be divided into several groups and different Tx beams may be applied to the different BRRS groups. A BRRS group can be indicated implicitly by DMRS information so that the antenna port configuration of the DMRS can be used to indicate the antenna ports of the BRRS. For example, DMRS port pairs {7,9}, {8,10}, { 11,13}, and { 12,14} can be used to indicate BRRS port pairs {31,32}, {33,34}, {35,36}, and{37,38} . Alternatively, the BRRS port can be indicated in DCI signaling.
[0059] In another example, the total number of antenna ports ( N ) can be configured by the related DCI or higher layer signaling (e.g., MIB, SIB, or RRC signaling) or can be predefined. The N parameter can indicate how many antenna ports are to share the same Physical Resource Blocks (PRBs) and can be used to calculate a resource mapping, such as the subcarrier gap in interleaved frequency-division multiplexing resource mapping.
[0060] With regard to mapping to resource elements, a part of the reference signal sequence r(m) can be mapped to complex- valued modulation symbols aff . There may be two at least two alternatives for resource mapping. In alternative, resource elements of the BRRS can be mapped to the same PRBs as the corresponding data. The mapping can be realized in a localized or interleaved way. In another alternative, the BRRS can be assigned within the full bandwidth in a localized or interleaved way.
[0061] With regard to OFDM signal generation, the subcarrier spacing AfBRRScw be used for the BRRS symbols. For the other symbols, the subcarrier spacing Af can be applied.
[0062] FIG. 5 shows an example structure for a BRRS that has a subcarrier spacing of 4Αΐ, where Af denotes a subcarrier spacing for an extended (e.g., 5G) Physical Downlink Shared Channel (xPDSCH). Then the duration for one BRRS symbol can be
- Ti , where ; denotes the duration of one OFDM symbol with normal Cyclic Prefix (CP)
4
for the xPDSCH.
[0063] In one example, the BRRS sequence for one antenna port (AP) may be transmitted repeatedly in each BRRS symbol using a single Tx beam or multiple Tx beams. All the subcarriers within one BRRS symbol can be used for one AP and different APs may be configured with different cyclic shifts. In one example, a first AP may use a cyclic shift of zero and a second AP may use a cyclic shift of 0.5π. Alternatively, different APs may use different subcarriers. For example, the BRRS may have two APs. The first AP may use odd subcarriers, while the second AP may use even subcarriers.
BRRS Beam Pattern
[0064] The BRRS may be used for beam switching and beam refinement.
Different BRRS formats may be used for different functions. A BRRS format la can be used for Rx beam refinement with a current Tx beam. A BRRS format 2a can be used for gradual Tx beam switching. A BRRS format 3 a can be used when a the full Rx beam search with a new Tx beam is desired. A BRRS format 4a can be used for Tx beam switching between two uncorrelated Tx beams.
[0065] In one example, to facilitate supporting more UEs within one subframe with a single antenna panel, one UE can use one BRRS AP. The UE may assume that a full Tx beam will be applied in two consecutive BSR-RS symbols. For example, odd- numbered BRRS symbols can be used for horizontal transmission and even BRRS symbols can be used for the vertical transmission direction. [0066] FIG. 6 illustrates one example for a beam pattern of a first AP. As shown in FIG. 6, odd BRRS symbols can be used for a vertical Tx beam and even BRRS symbols can be used for a horizontal Tx beam. For a second AP, odd BRRS symbols can be used for a horizontal Tx beam and even BRRS symbols can be used for a vertical Tx beam.
[0067] FIG. 7 illustrates a beam structure (Format la) in which a first Tx beam can be used for current downlink data and control transmission. For Format la, the Tx beam used for the BRRS may be the same as a current Tx beam. A UE can try different types of Rx beams to find the a preferred or best Rx beam for Rx beam refinement within N BRRS symbols, wherein N can be predefined by the system or configured by the higher layer signaling or the DCI.
[0068] FIG. 8 illustrates a beam structure (Format 2a) with which an eNB may switch a Tx beam gradually. The new Tx beam (e.g., the beam to which the eNB switches) may be applied in the BRRS, the xPDSCH, and the CSI-RS. Tx beam 1 indicates the current Tx beam and Tx beam 2 indicated the new Tx beam. In this example, Both Tx beams 1 and 2 are highly correlated. A UE can try different types of Rx beams to find a preferred or best Rx beam for the new Tx beam.
[0069] FIG. 9 illustrates a beam structure (Format 3a) with which an eNB may switch to a new Tx beam directly and a full Rx beam searching process may be applied for the BRRS reception. The new Tx beam may be applied in the BRRS, the xPDSCH, and the CSI-RS. Tx beam 1 indicates a current Tx beam and Tx beam 2 indicates a new Tx beam. For full Rx beam searching, 2N BRRS symbols may be applied. N can be predefined by the system or configured by the higher layer signaling or the DCI.
[0070] FIG. 10 illustrates a beam structure (Format 4a) with which an eNB may switch to a new Tx beam (which may be the second channel cluster). An Rx beam refinement for the new Tx beam may be applied for BRRS reception. There may be 2N BRRS symbols. N can be predefined by the system or configured by the higher layer signaling or the DCI. The first N symbols may use the current Tx beam and the second N symbols may use the new Tx beam. The new Tx beam may be applied in the xPDSCH. The CSI-RS may use different Tx beams in different symbols. In FIG. 10, Tx beam 1 indicates the current Tx beam and Tx beam 2 indicates the new Tx beam. For the CSI-RS, the first symbol may use Tx beam 1 and the second symbol may use the Tx beam 2. [0071] FIG. 11 illustrates functionality 1100 of User Equipment (UE) in accordance with an example. The functionality 1100 can be implemented as a method or the functionality can be executed as instructions on a machine (e.g., by one or more processors), where the instructions are included on at least one computer-readable storage medium (e.g., a transitory or non-transitory computer-readable storage medium).
[0072] As in block 11 10, the functionality 1100 can include identifying a Beam
Refinement Reference Signal (BRRS) transmission sent from a cellular base station and received via a transceiver at the UE, wherein the BRRS transmission uses a BRRS subcarrier spacing and is followed by one more following Orthogonal Frequency Division Multiplexing (OFDM) symbols that follow the BRRS transmission, and wherein the BRRS subcarrier spacing is larger than a subcarrier spacing of the one more following Orthogonal Frequency Division Multiplexing (OFDM) symbols.
[0073] The BRRS subcarrier spacing can be predefined in a specification or configured by the cellular base station via one or more of: Downlink Control Information (DCI), master information broadcasting (MIB), system information broadcasting (SIB), or radio resource control (RRC) signaling. The BRRS subcarrier spacing ( fBRRS) can be equal to four times the subcarrier spacing of the one or more following OFDM symbols (Δ ) such that fBRRS = 4■ Af. The BRRS transmission can comprise one or more BRRS OFDM symbols and the one or more BRRS symbols can contain a plurality of BRRS antenna ports. The BRRS transmission can be mapped in an Orthogonal Frequency Division Multiple Access (OFDMA) symbol between an extended Physical Downlink Control Channel (xPDCCH) and an extended Physical Downlink Shared Channel (xPDSCH) or can be mapped in the OFDMA symbol before the xPDCCH.
[0074] As in block 1120, the functionality 1100 can include refining a Reception
(Rx) beam based on the BRRS transmission. The BRRS transmission can comprise four BRRS OFDM symbols and, in one example, up to four Rx beams can be refined based the four BRRS OFDM symbols. In another example, the BRRS transmission can comprise eight BRRS OFDM symbols. A first Rx beam can be refined based on four first BRRS OFDM symbols of the eight BRRS OFDM symbols. A second Rx beam can be refined based on four second BRRS OFDM symbols of the eight BRRS OFDM symbols. Alternatively, up to eight Rx beams can be refined based on the eight BRRS OFDM symbols. BRRS measurements can be taken using one or more initial Rx beams and a transceiver at the UE can send the BRRS measurements to the cellular base station. The up-to-eight Rx beams can be refined using one or more initial Rx beams.
[0075] As in block 1130, the functionality 1100 can include signaling the transceiver at the UE to use the refined Rx beam to receive the one or more following OFDM symbols.
[0076] The functionality 1 100 can also include processing a first Channel State
Information Reference Signal (CSI-RS) symbol that is received using the first Rx beam and processing a second Channel State Information Reference Signal (CSI-RS) symbol and Physical Downlink Shared Channel (PDSCH) data that are received using the second Rx beam.
[0077] The functionality 1100 can also include measuring a BRRS port group, wherein the BRRS port group includes two antenna ports of the plurality of antenna ports, and wherein the two antenna ports are frequency division multiplexed or code division multiplexed. The functionality 1100 can also include refining the Rx beam based on the measuring of the BRRS port group. The two antenna ports can be mapped to all subcarriers used for the BRRS transmission and are generated based on different cyclic shifts. The plurality of antenna ports can be indicated by an antenna port configuration of a Demodulation Reference Signal (DMRS) of an extended Physical Downlink Control Channel (xPDCCH) that is associated with the BRRS transmission.
[0078] FIG. 12 illustrates functionality 1200 of a cellular base station (e.g., an eNB) in accordance with an example. The functionality 1200 can be implemented as a method or the functionality can be executed as instructions on a machine (e.g., by one or more processors), where the instructions are included on at least one computer-readable storage medium (e.g., a transitory or non-transitory computer-readable storage medium).
[0079] As in block 1210, the functionality 1200 can include identifying a base sequence to be used for a Beam Refinement Reference Signal (BRRS), wherein the base sequence is a Zadoff-Chu sequence or a Quadrature Phase Shift Keying (QPSK) sequence. The BRRS subcarrier spacing can be predefined in a specification or the cellular base station can configure the BRRS subcarrier spacing via Downlink Control Information (DO), master information broadcasting (MIB), system information broadcasting (SIB), or radio resource control (RRC) signaling. The BRRS subcarrier spacing ( fBRRS) can be equal to four times the subcarrier spacing of the one or more following OFDM symbols (Δ ) such that fBRRS = 4■ Af. The BRRS transmission can comprise one or more BRRS OFDM symbols (e.g., four or eight) and the one or more BRRS symbols can contain a plurality of BRRS antenna ports.
[0080] The functionality 1200 can also include signaling a transceiver to frequency-division multiplexed a BRRS sequence for each BRRS antenna port of the plurality of BRRS antenna ports. The functionality 1200 can also include signaling the transceiver to send each BRRS antenna port of the plurality of BRRS antenna ports to the UE from the cellular base station using a respective antenna port.
[0081] The functionality 1200 can also include signaling the transceiver to indicate the plurality of antenna ports to a UE using an antenna port configuration of a Demodulation Reference Signal (DMRS) of a Physical Downlink Control Channel (xPDCCH) that is associated with the BRRS transmission.
[0082] The functionality 1200 can also include mapping the BRRS transmission between an extended Physical Downlink Control Channel (xPDCCH) and an extended Physical Downlink Shared Channel (xPDSCH) or before the xPDCCH.
[0083] As in block 1220, the functionality 1200 can include identifying at least one transmission beam (Tx) to be used for sending transmissions to a User Equipment (UE).
[0084] As in block 1230, the functionality 1200 can include signaling a transceiver associated with the cellular base station to send a Beam Refinement Reference Signal (BRRS) transmission to the UE, wherein the BRRS transmission uses a BRRS subcarrier spacing, and wherein the BRRS subcarrier spacing is larger than a subcarrier spacing of one more following Orthogonal Frequency Division Multiplexing (OFDM) symbols that follow the BRRS transmission.
[0085] The functionality 1200 can include signaling the transceiver to send a first Channel State Information Reference Signal (CSI-RS) symbol to the UE using a first Tx beam and signaling the transceiver to send a second Channel State Information Reference Signal (CSI-RS) symbol using a second Tx beam.
[0086] The functionality 1200 can include signaling the transceiver associated with the cellular base station to send a BRRS format indicator to the UE in Downlink Control Information (DO), wherein the BRRS format indicator indicates a format to which the BRRS transmission conforms.
[0087] FIG. 13 provides an example illustration of a mobile device, such as a user equipment (UE), a mobile station (MS), a mobile wireless device, a mobile communication device, a tablet, a handset, a CIoT device, or other type of wireless device. The mobile 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 (WW AN) access point. The mobile 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 mobile device can communicate using separate antennas for each wireless communication standard or shared antennas for multiple wireless communication standards. The mobile device can communicate in a wireless local area network (WLAN), a wireless personal area network (WPAN), and/or a WWAN.
[0088] The mobile 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 mobile device transmits via the one or more antennas and demodulate signals that the mobile device receives via the one or more antennas.
[0089] The mobile device can include a storage medium. In one aspect, the storage medium can be associated with and/or communication with the application processor, the graphics processor, the display, the non-volatile memory port, and/or internal memory. In one aspect, the application processor and graphics processor are storage mediums.
[0090] FIG. 13 also provides an illustration of a microphone and one or more speakers that can be used for audio input and output from the mobile 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 mobile device. A keyboard can be integrated with the mobile device or wirelessly connected to the wireless device to provide additional user input. A virtual keyboard can also be provided using the touch screen.
[0091] FIG. 14 provides an example illustration of a user equipment (UE) device
1400, such as a wireless device, a mobile station (MS), a mobile wireless device, a mobile communication device, a tablet, a handset, a CIoT device, or other type of wireless device. The UE device 1400 can include one or more antennas configured to
communicate with a node 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 (WW AN) access point. The UE device 1400 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 UE device 1400 can communicate using separate antennas for each wireless communication standard or shared antennas for multiple wireless communication standards. The UE device 1400 can communicate in a wireless local area network (WLAN), a wireless personal area network (WPAN), and/or a WW AN.
[0092] In some embodiments, the UE device 1400 may include application circuitry 1402, baseband circuitry 1404, Radio Frequency (RF) circuitry 1406, front-end module (FEM) circuitry 1408 and one or more antennas 1410, coupled together at least as shown.
[0093] The application circuitry 1402 may include one or more application processors. For example, the application circuitry 1402 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 memory/storage (e.g., storage medium 1412) and may be configured to execute instructions stored in the memory /storage (e.g., storage medium 1412) to enable various applications and/or operating systems to run on the system.
[0094] The baseband circuitry 1404 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 1404 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 1406 and to generate baseband signals for a transmit signal path of the RF circuitry 1406. Baseband processing circuity 1404 may interface with the application circuitry 1402 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 1406. For example, in some embodiments, the baseband circuitry 1404 may include a second generation (2G) baseband processor 1404a, third generation (3G) baseband processor 1404b, fourth generation (4G) baseband processor 1404c, and/or other baseband processor(s) 1404d for other existing generations, generations in development or to be developed in the future (e.g., fifth generation (5G), 6G, etc.). The baseband circuitry 1404 (e.g., one or more of baseband processors 1404a-d) may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 1406. 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 1404 may include Fast-Fourier Transform (FFT), precoding, and/or constellation
mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 1404 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.
[0095] In some embodiments, the baseband circuitry 1404 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) 1404e of the baseband circuitry 1404 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) 1404f. The audio DSP(s) 1404f may 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 1404 and the application circuitry 1402 may be implemented together such as, for example, on a system on a chip (SOC).
[0096] In some embodiments, the baseband circuitry 1404 may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 1404 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 1404 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.
[0097] The RF circuitry 1406 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 1406 may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 1406 may include a receive signal path which may include circuitry to down-convert RF signals received from the FEM circuitry 1408 and provide baseband signals to the baseband circuitry 1404. RF circuitry 1406 may also include a transmit signal path which may include circuitry to up-convert baseband signals provided by the baseband circuitry 1404 and provide RF output signals to the FEM circuitry 1408 for transmission.
[0098] In some embodiments, the RF circuitry 1406 may include a receive signal path and a transmit signal path. The receive signal path of the RF circuitry 1406 may include mixer circuitry 1406a, amplifier circuitry 1406b and filter circuitry 1406c. The transmit signal path of the RF circuitry 1406 may include filter circuitry 1406c and mixer circuitry 1406a. RF circuitry 1406 may also include synthesizer circuitry 1406d for synthesizing a frequency for use by the mixer circuitry 1406a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 1406a of the receive signal path may be configured to down-convert RF signals received from the FEM circuitry 1408 based on the synthesized frequency provided by synthesizer circuitry 1406d. The amplifier circuitry 1406b may be configured to amplify the down-converted signals and the filter circuitry 1406c 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 1404 for further processing. In some embodiments, the output baseband signals may be zero-frequency baseband signals, although other types of baseband signals may be used. In some embodiments, mixer circuitry 1406a of the receive signal path may comprise passive mixers, although the scope of the embodiments is not limited in this respect.
[0099] In some embodiments, the mixer circuitry 1406a of the transmit signal path may be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 1406d to generate RF output signals for the FEM circuitry 1408. The baseband signals may be provided by the baseband circuitry 1404 and may be filtered by filter circuitry 1406c. The filter circuitry 1406c may include a low-pass filter (LPF), although the scope of the embodiments is not limited in this respect.
[00100] In some embodiments, the mixer circuitry 1406a of the receive signal path and the mixer circuitry 1406a 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 1406a of the receive signal path and the mixer circuitry 1406a 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 1406a of the receive signal path and the mixer circuitry 1406a may be arranged for direct down-conversion and/or direct up-conversion, respectively. In some embodiments, the mixer circuitry 1406a of the receive signal path and the mixer circuitry 1406a of the transmit signal path may be configured for super-heterodyne operation.
[00101] 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 1406 may include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 1404 may include a digital baseband interface to communicate with the RF circuitry 1406.
[00102] 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.
[00103] In some embodiments, the synthesizer circuitry 1406d 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 1406d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider.
[00104] The synthesizer circuitry 1406d may be configured to synthesize an output frequency for use by the mixer circuitry 1406a of the RF circuitry 1406 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 1406d may be a fractional N/N+l synthesizer.
[00105] In some embodiments, frequency input may be provided by a voltage controlled oscillator (VCO), although other types of devices may provide the frequency input. Divider control input may be provided by either the baseband circuitry 1404 or the applications processor 1402 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 1402.
[00106] Synthesizer circuitry 1406d of the RF circuitry 1406 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 (DP A). 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.
[00107] In some embodiments, synthesizer circuitry 1406d 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 1406 may include an IQ/polar converter. [00108] FEM circuitry 1408 may include a receive signal path which may include circuitry configured to operate on RF signals received from one or more antennas 1410, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 1406 for further processing. FEM circuitry 1408 may also include a transmit signal path which may include circuitry configured to amplify signals for transmission provided by the RF circuitry 1406 for transmission by one or more of the one or more antennas 1410.
[00109] In some embodiments, the FEM circuitry 1408 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 1406). The transmit signal path of the FEM circuitry 1408 may include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 1406), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 1410.
[00110] In some embodiments, the UE device 1400 may include additional elements such as, for example, memory/storage, display (e.g., touch screen), camera, antennas, keyboard, microphone, speakers, sensor, and/or input/output (I/O) interface.
[00111] FIG. 15 illustrates a diagram 1500 of a node 1510 (e.g., eNB and/or a
Serving GPRS Support Node) and a wireless device 1520 (e.g., UE) in accordance with an example. The node can include a base station (BS), a Node B (NB), an evolved Node B (eNB), a baseband unit (BBU), a remote radio head (RRH), a remote radio equipment (RRE), a remote radio unit (RRU), or a central processing module (CPM). In one aspect, the node can be a Serving GPRS Support Node. The node 1510 can include a node device 1512. The node device 1512 or the node 1510 can be configured to communicate with the wireless device 1520. The node device 1512 can be configured to implement technologies described herein. The node device 1512 can include a processing module 1514 and a transceiver module 1516. In one aspect, the node device 1512 can include the transceiver module 1516 and the processing module 1514 forming a circuitry for the node 1510. In one aspect, the transceiver module 1516 and the processing module 1514 can form a circuitry of the node device 1512. The processing module 1514 can include one or more processors and memory. In one embodiment, the processing module 1522 can include one or more application processors. The transceiver module 1516 can include a transceiver and one or more processors and memory. In one embodiment, the transceiver module 1516 can include a baseband processor.
[00112] The wireless device 1520 can include a transceiver module 1524 and a processing module 1522. The processing module 1522 can include one or more processors and memory. In one embodiment, the processing module 1522 can include one or more application processors. The transceiver module 1524 can include a transceiver and one or more processors and memory. In some examples, components of the transceiver module 1516 can be included in separate devices. For example, selected components of the transceiver module 1516 may be located in a cloud radio access network (C-RAN). In one embodiment, the transceiver module 1524 can include a baseband processor. The wireless device 1520 can be configured to implement technologies described herein. The node 1510 and the wireless devices 1520 can also include one or more storage mediums, such as the transceiver module 1516, 1524 and/or the processing module 1514, 1522.
Examples
[00113] The following examples pertain to specific embodiments and point out specific features, elements, or steps that can be used or otherwise combined in achieving such embodiments.
[00114] Example 1 includes an apparatus of a User Equipment (UE), the apparatus comprising one or more processors and memory configured to: identify a Beam
Refinement Reference Signal (BRRS) transmission sent from a cellular base station and received via a transceiver at the UE, wherein the BRRS transmission uses a BRRS subcarrier spacing and is followed by one more following Orthogonal Frequency Division Multiplexing (OFDM) symbols that follow the BRRS transmission, and wherein the BRRS subcarrier spacing is larger than a subcarrier spacing of the one more following Orthogonal Frequency Division Multiplexing (OFDM) symbols; refine a Reception (Rx) beam based on the BRRS transmission; and signal the transceiver at the UE to use the refined Rx beam to receive the one or more following OFDM symbols.
[00115] In example 2, the subject matter of example 1 or any of the examples described herein may further include that the BRRS subcarrier spacing is predefined in a specification or is configured by the cellular base station via one or more of: Downlink Control Information (DCI), master information broadcasting (MIB), system information broadcasting (SIB), or radio resource control (RRC) signaling.
[00116] In example 3, the subject matter of example 1, 2 or any of the examples described herein may further include that the BRRS subcarrier spacing (AfBRRS) is equal to four times the subcarrier spacing of the one or more following OFDM symbols (Δί) such that AfBRRS = 4■ Af.
[00117] In example 4, the subject matter of example 1, 2, 3, or any of the examples described herein may further include that the BRRS transmission comprises four BRRS OFDM symbols and the one or more processors and memory are further configured to refine up to four Rx beams based the four BRRS OFDM symbols.
[00118] In example 5, the subject matter of example 1, 2, 3, or any of the examples described herein may further include that the BRRS transmission comprises eight BRRS OFDM symbols and the one or more processors and memory are further configured to: refine a first Rx beam based on four first BRRS OFDM symbols of the eight BRRS OFDM symbols; and refine a second Rx beam based on four second BRRS OFDM symbols of the eight BRRS OFDM symbols.
[00119] In example 6, the subject matter of example 5 or any of the examples described herein may further include that the one or more processors and memory are further configured to: process a first Channel State Information Reference Signal (CSI- RS) symbol that is received using the first Rx beam; and process a second Channel State Information Reference Signal (CSI-RS) symbol and Physical Downlink Shared Channel (PDSCH) data that are received using the second Rx beam.
[00120] In example 7, the subject matter of example 1, 2, 3, or any of the examples described herein may further include that the BRRS transmission comprises eight BRRS OFDM symbols and the one or more processors and memory are further configured to refine up to eight Rx beams based on the eight BRRS OFDM symbols.
[00121] In example 8, the subject matter of example 7 or any of the examples described herein may further include that the one or more processors and memory are further configured to: take BRRS measurements using one or more initial Rx beams; signal the transceiver to send the BRRS measurements to the cellular base station; and refine the up-to-eight Rx beams using one or more initial Rx beams. [00122] In example 9, the subject matter of example 1, 2, 3, 4, 5, 6, 7, 8, or any of the examples described herein may further include that the BRRS transmission comprises one or more BRRS OFDM symbols and the one or more BRRS symbols contain a plurality of BRRS antenna ports.
[00123] In example 10, the subject matter of example 9 or any of the examples described herein may further include that the one or more processors and memory are further configured to: measure a BRRS port group, wherein the BRRS port group includes two antenna ports of the plurality of antenna ports, and wherein the two antenna ports are frequency division multiplexed or code division multiplexed; and refine the Rx beam based on the measuring of the BRRS port group.
[00124] In example 11, the subject matter of example 10 or any of the examples described herein may further include that the two antenna ports are mapped to all subcarriers used for the BRRS transmission and are generated based on different cyclic shifts.
[00125] In example 12, the subject matter of example 9 or any of the examples described herein may further include that the plurality of antenna ports is indicated by an antenna port configuration of a Demodulation Reference Signal (DMRS) of an extended Physical Downlink Control Channel (xPDCCH) that is associated with the BRRS transmission.
[00126] In example 13, the subject matter of example 1, 2, 3, 4, 5, 6, 7, 8, or any of the examples described herein may further include that the BRRS transmission comprises one or more BRRS OFDM symbols and the BRRS transmission is mapped in an
Orthogonal Frequency Division Multiple Access (OFDMA) symbol between an extended Physical Downlink Control Channel (xPDCCH) and an extended Physical Downlink Shared Channel (xPDSCH) or is mapped in the OFDMA symbol before the xPDCCH.
[00127] Example 14 includes an apparatus of a cellular base station in a Multiple
Input Multiple Output (MIMO) system, the apparatus comprising one or more processors and memory configured to: identify a base sequence to be used for a Beam Refinement Reference Signal (BRRS), wherein the base sequence is a Zadoff-Chu sequence or a Quadrature Phase Shift Keying (QPSK) sequence; identify at least one transmission beam (Tx) to be used for sending transmissions to a User Equipment (UE); and signal a transceiver associated with the cellular base station to send a Beam Refinement Reference Signal (BRRS) transmission to the UE, wherein the BRRS transmission uses a BRRS subcarrier spacing, and wherein the BRRS subcarrier spacing is larger than a subcarrier spacing of one more following Orthogonal Frequency Division Multiplexing (OFDM) symbols that follow the BRRS transmission.
[00128] In example 15, the subject matter of example 15 or any of the examples described herein may further include that the BRRS subcarrier spacing is predefined in a specification or the one or more processors and memory are further configured to configure the BRRS subcarrier spacing via Downlink Control Information (DCI), master information broadcasting (MIB), system information broadcasting (SIB), or radio resource control (RRC) signaling.
[00129] In example 16, the subject matter of example 14, 15, or any of the examples described herein may further include that the BRRS subcarrier spacing (AfBRRS) is equal to four times the subcarrier spacing of the one or more following OFDM symbols (Δί) such that AfBRRS = 4■ Af.
[00130] In example 17, the subject matter of example 14, 15, 16, or any of the examples described herein may further include that the BRRS transmission comprises four BRRS OFDM symbols.
[00131] In example 18, the subject matter of example 14, 15, 16, or any of the examples described herein may further include that the BRRS transmission comprises eight BRRS OFDM symbols.
[00132] In example 19, the subject matter of example 19 or any of the examples described herein may further include that the one or more processors and memory are further configured to: signal the transceiver to send a first Channel State Information Reference Signal (CSI-RS) symbol to the UE using a first Tx beam; and signal the transceiver to send a second Channel State Information Reference Signal (CSI-RS) symbol using a second Tx beam.
[00133] In example 20, the subject matter of example 14, 15, 16, 17, 18, 19, or any of the examples described herein may further include that the BRRS transmission comprises one or more BRRS OFDM symbols and the one or more BRRS symbols contain a plurality of BRRS antenna ports.
[00134] In example 21, the subject matter of example 20 or any of the examples described herein may further include that the one or more processors and memory are further configured to: signal the transceiver to frequency-division multiplexed a BRRS sequence for each BRRS antenna port of the plurality of BRRS antenna ports; and signal the transceiver to send each BRRS antenna port of the plurality of BRRS antenna ports to the UE from the cellular base station using a respective antenna port.
[00135] In example 22, the subject matter of example 20 or any of the examples described herein may further include that the one or more processors and memory are further configured to: signal the transceiver to indicate the plurality of antenna ports to the UE using an antenna port configuration of a Demodulation Reference Signal (DMRS) of a Physical Downlink Control Channel (xPDCCH) that is associated with the BRRS transmission.
[00136] In example 23, the subject matter of example 14 or any of the examples described herein may further include that the BRRS transmission comprises one or more BRRS OFDM symbols and the one or more processors and memory are further configured to map the BRRS transmission between an extended Physical Downlink Control Channel (xPDCCH) and an extended Physical Downlink Shared Channel (xPDSCH) or before the xPDCCH.
[00137] In example 24, the subject matter of example 14, 15, 16, 17, 18, 19, 20, 21,
22, 23, or any of the examples described herein may further include that the one or more processors and memory are further configured to signal the transceiver associated with the cellular base station to send a BRRS format indicator to the UE in Downlink Control Information (DO), wherein the BRRS format indicator indicates a format to which the BRRS transmission conforms.
[00138] Example 25 includes a computer-readable medium (e.g., a non-transitory computer-readable medium) containing instructions thereon which, when executed by one or more processors, perform the following: identifying a Beam Refinement Reference Signal (BRRS) transmission sent from a cellular base station, wherein the BRRS transmission either: uses a BRRS subcarrier spacing (AfBRRS) that is equal to four times a subcarrier spacing of one or more following OFDM symbols (Δί) that follow the BRRS transmission such that AfBRRS = 4■ Δί, or uses a time domain replica waveform and is equal to the subcarrier spacing of the one or more following OFDM symbols; refining a Reception (Rx) beam based on the BRRS transmission; and signaling a transceiver to use the Rx beam to receive the one or more following OFDM symbols.
[00139] In example 26, the subject matter of example 25 or any of the examples described herein may further include that the computer-readable medium further contains instructions thereon which, when executed by one or more processors, perform the following:
[00140] refining up to four Rx beams based on four BRRS OFDM symbols that are included in the BRRS transmission..
[00141] In example 27, the subject matter of example 25, 26, or any of the examples described herein may further include that the computer-readable medium further contains instructions thereon which, when executed by one or more processors, perform the following: refining a first Rx beam based on four first BRRS OFDM symbols included in the BRRS transmission; and refining a second Rx beam based on four second BRRS OFDM symbols included in the BRRS transmission.
[00142] In example 28, the subject matter of example 25 or any of the examples described herein may further include that the computer-readable medium further contains instructions thereon which, when executed by one or more processors, perform the following: refining up to eight Rx beams based on eight BRRS OFDM symbols included in the BRRS transmission.
[00143] Example 29 includes a means for refining a reception (Rx) beam, the means comprising: a means for identifying a Beam Refinement Reference Signal (BRRS) transmission sent from a cellular base station, wherein the BRRS transmission either: uses a BRRS subcarrier spacing (AfBRRS) that is equal to four times a subcarrier spacing of one or more following OFDM symbols (Δί) that follow the BRRS transmission such that AfBRRs = 4■ Δί, or uses a time domain replica waveform and is equal to the subcarrier spacing of the one or more following OFDM symbols; a means for refining a Reception (Rx) beam based on the BRRS transmission; and a means for signaling a transceiver to use the Rx beam to receive the one or more following OFDM symbols.
[00144] In example 30, the subject matter of example 29 or any of the examples described herein may further include that the means for refining an Rx beam further comprises:
[00145] a means for refining up to four Rx beams based on four BRRS OFDM symbols that are included in the BRRS transmission..
[00146] In example 31, the subject matter of example 29 or any of the examples described herein may further include that the means for refining an Rx beam further comprises: a means for refining a first Rx beam based on four first BRRS OFDM symbols included in the BRRS transmission; and a means for refining a second Rx beam based on four second BRRS OFDM symbols included in the BRRS transmission.
[00147] Example 32 includes an apparatus of a User Equipment (UE), the apparatus comprising one or more processors and memory configured to: identify a Beam Refinement Reference Signal (BRRS) transmission sent from a cellular base station and received via a transceiver at the UE, wherein the BRRS transmission uses a BRRS subcarrier spacing and is followed by one more following Orthogonal Frequency Division Multiplexing (OFDM) symbols that follow the BRRS transmission, and wherein wherein the BRRS subcarrier spacing (AfBRRS) is equal to four times a subcarrier spacing of the one or more following OFDM symbols (Δί) such that AfBRRS = 4■ Δί; refine a Reception (Rx) beam based on the BRRS transmission; and signal the transceiver at the UE to use the refined Rx beam to receive the one or more following OFDM symbols.
[00148] In example 33, the subject matter of example 32 or any of the examples described herein may further include that the BRRS transmission comprises four BRRS OFDM symbols and the one or more processors and memory are further configured to refine up to four Rx beams based the four BRRS OFDM symbols.
[00149] In example 34, the subject matter of example 32 or any of the examples described herein may further include that the BRRS transmission comprises eight BRRS OFDM symbols and the one or more processors and memory are further configured to: refine a first Rx beam based on four first BRRS OFDM symbols of the eight BRRS
OFDM symbols; refine a second Rx beam based on four second BRRS OFDM symbols of the eight BRRS OFDM symbols; process a first Channel State Information Reference Signal (CSI-RS) symbol that is received using the first Rx beam; and process a second Channel State Information Reference Signal (CSI-RS) symbol and Physical Downlink Shared Channel (PDSCH) data that are received using the second Rx beam.
[00150] In example 35, the subject matter of example 32 or any of the examples described herein may further include that the BRRS transmission comprises eight BRRS OFDM symbols and the one or more processors and memory are further configured to: refine up to eight Rx beams based on the eight BRRS OFDM symbols; take BRRS measurements using one or more initial Rx beams; signal the transceiver to send the BRRS measurements to the cellular base station; and refine the up-to-eight Rx beams using one or more initial Rx beams. [00151] In example 36, the subject matter of example 32, 33, 34, 35, or any of the examples described herein may further include that the BRRS transmission comprises one or more BRRS OFDM symbols and the one or more BRRS symbols contain a plurality of BRRS antenna ports, and that the one or more processors and memory are further configured to: measure a BRRS port group, wherein the BRRS port group includes two antenna ports of the plurality of antenna ports, and wherein the two antenna ports are frequency division multiplexed or code division multiplexed; and refine the Rx beam based on the measuring of the BRRS port group.
[00152] In example 37, the subject matter of example 36 or any of the examples described herein may further include that the plurality of antenna ports is indicated by an antenna port configuration of a Demodulation Reference Signal (DMRS) of an extended Physical Downlink Control Channel (xPDCCH) that is associated with the BRRS transmission.
[00153] Example 38 includes an apparatus of a cellular base station in a Multiple Input Multiple Output (MIMO) system, the apparatus comprising one or more processors and memory configured to: identify a base sequence to be used for a Beam Refinement Reference Signal (BRRS), wherein the base sequence is a Zadoff-Chu sequence or a Quadrature Phase Shift Keying (QPSK) sequence; identify at least one transmission beam (Tx) to be used for sending transmissions to a User Equipment (UE); and signal a transceiver associated with the cellular base station to send a Beam Refinement Reference Signal (BRRS) transmission to the UE, wherein the BRRS transmission uses a BRRS subcarrier spacing, and wherein the BRRS subcarrier spacing (AfBRRS) is equal to four times the subcarrier spacing of one or more following OFDM symbols (Δί) that follow the BRRS transmission such that AfBRRS = 4■ Δί.
[00154] In example 39, the subject matter of example 38 or any of the examples described herein may further include that the BRRS transmission comprises eight BRRS OFDM symbols, and that the one or more processors and memory are further configured to: signal the transceiver to send a first Channel State Information Reference Signal (CSI- RS) symbol to the UE using a first Tx beam; and signal the transceiver to send a second Channel State Information Reference Signal (CSI-RS) symbol using a second Tx beam.
[00155] In example 40, the subject matter of example 38, 39, or any of the examples described herein may further include that the BRRS transmission comprises one or more BRRS OFDM symbols and the one or more BRRS symbols contain a plurality of BRRS antenna ports, and wherein the one or more processors and memory are further configured to: signal the transceiver to frequency-division multiplexed a BRRS sequence for each BRRS antenna port of the plurality of BRRS antenna ports; and signal the transceiver to send each BRRS antenna port of the plurality of BRRS antenna ports to the UE from the cellular base station using a respective antenna port.
[00156] In example 41, the subject matter of example 40 or any of the examples described herein may further include that the one or more processors and memory are further configured to: signal the transceiver to indicate the plurality of antenna ports to the UE using an antenna port configuration of a Demodulation Reference Signal (DMRS) of a Physical Downlink Control Channel (xPDCCH) that is associated with the BRRS transmission.
[00157] In example 42, the subject matter of example 38 or any of the examples described herein may further include that the BRRS transmission comprises one or more BRRS OFDM symbols and the one or more processors and memory are further configured to map the BRRS transmission between an extended Physical Downlink Control Channel (xPDCCH) and an extended Physical Downlink Shared Channel (xPDSCH) or before the xPDCCH.
[00158] In example 43, the subject matter of example 38, 39, 40, 41, or any of the examples described herein may further include that the one or more processors and memory are further configured to signal the transceiver associated with the cellular base station to send a BRRS format indicator to the UE in Downlink Control Information (DCI), wherein the BRRS format indicator indicates a format to which the BRRS transmission conforms.
[00159] 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, a transitory or 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. A non-transitory computer readable storage medium can be a computer readable storage medium that does not include signal. 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 non-volatile 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). 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.
[00160] 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.
[00161] While the flowcharts presented for this technology may imply a specific order of execution, the order of execution may differ from what is illustrated. For example, the order of two more blocks may be rearranged relative to the order shown. Further, two or more blocks shown in succession may be executed in parallel or with partial parallelization. In some configurations, one or more blocks shown in the flow chart may be omitted or skipped. Any number of counters, state variables, warning semaphores, or messages may be added to the logical flow for enhanced utility, accounting, performance, measurement, troubleshooting, or other purposes.
[00162] As used herein, the word "or" indicates an inclusive disjunction. For example, as used herein, the phrase "A or B" represents an inclusive disjunction of exemplary conditions A and B. Hence, "A or B" is false only if both condition A is false and condition B is false. When condition A is true and condition B is also true, "A or B" is also true. When condition A is true and condition B is false, "A or B" is true. When condition B is true and condition A is false, "A or B" is true. In other words, the term "or," as used herein, should not be construed as an exclusive disjunction. The term "xor" is used where an exclusive disjunction is intended.
[00163] As used herein, the term processor can include general-purpose processors, specialized processors such as VLSI, FPGAs, and other types of specialized processors, as well as base-band processors used in transceivers to send, receive, and process wireless communications.
[00164] 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 can be implemented as a hardware circuit (e.g., an application-specific integrated circuit (ASIC)) comprising custom VLSI circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module can also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like.
[00165] Modules can also be implemented in software for execution by various types of processors. An identified module of executable code can, for instance, comprise one or more physical or logical blocks of computer instructions, which can, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module do not have to be physically located together, but can comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module.
[00166] Indeed, a module of executable code can be a single instruction, or many instructions, and can even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data can be identified and illustrated herein within modules, and can be embodied in any suitable form and organized within any suitable type of data structure. The operational data can be collected as a single data set, or can be distributed over different locations including over different storage devices, and can exist, at least partially, merely as electronic signals on a system or network. The modules can be passive or active, including agents operable to perform desired functions. [00167] As used herein, the term "processor" can include general purpose processors, specialized processors such as VLSI, FPGAs, and other types of specialized processors, as well as base band processors used in transceivers to send, receive, and process wireless communications.
[00168] Reference throughout this specification to "an example" means that a particular feature, structure, or characteristic described in connection with the example is included in at least one embodiment. Thus, appearances of the phrases "in an example" in various places throughout this specification are not necessarily all referring to the same embodiment.
[00169] As used herein, a plurality of items, structural elements, compositional elements, and/or materials can 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 examples can 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 de facto equivalents of one another, but are to be considered as separate and autonomous.
[00170] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the foregoing description, numerous specific details are provided, such as examples of layouts, distances, network examples, etc., to provide a thorough understanding of some embodiments. One skilled in the relevant art will recognize, however, that the some embodiments 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 different embodiments.
[00171] While the forgoing examples are illustrative of the principles used in various embodiments 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 embodiments. Accordingly, it is not intended that the claimed matter be limited, except as by the claims set forth below.

Claims

CLAIMS What is claimed is:
1. An apparatus of a User Equipment (UE), the apparatus comprising one or more processors and memory configured to:
identify a Beam Refinement Reference Signal (BRRS) transmission sent from a cellular base station and received via a transceiver at the UE, wherein the BRRS transmission uses a BRRS subcarrier spacing and is followed by one more following Orthogonal Frequency Division Multiplexing (OFDM) symbols that follow the BRRS transmission, and wherein the BRRS subcarrier spacing is larger than a subcarrier spacing of the one more following Orthogonal Frequency Division Multiplexing (OFDM) symbols;
refine a Reception (Rx) beam based on the BRRS transmission; and
signal the transceiver at the UE to use the refined Rx beam to receive the one or more following OFDM symbols.
2. The apparatus of claim 1, wherein the BRRS subcarrier spacing is predefined in a specification or is configured by the cellular base station via one or more of: Downlink Control Information (DCI), master information broadcasting (MIB), system information broadcasting (SIB), or radio resource control (RRC) signaling.
3. The apparatus of claim 1 or 2, wherein the BRRS subcarrier spacing ( fBRRS) is equal to four times the subcarrier spacing of the one or more following OFDM symbols (Δ/) such that AfBRRS = 4■ Af.
4. The apparatus of claim 1 , 2, or 3, wherein the BRRS transmission comprises four BRRS OFDM symbols and the one or more processors and memory are further configured to refine up to four Rx beams based the four BRRS OFDM symbols.
The apparatus of claim 1, 2, or 3, wherein the BRRS transmission comprises eight BRRS OFDM symbols and the one or more processors and memory are further configured to:
refine a first Rx beam based on four first BRRS OFDM symbols of the eight BRRS OFDM symbols; and
refine a second Rx beam based on four second BRRS OFDM symbols of the eight BRRS OFDM symbols.
The apparatus of claim 5, wherein the one or more processors and memory are further configured to:
process a first Channel State Information Reference Signal (CSI- RS) symbol that is received using the first Rx beam; and
process a second Channel State Information Reference Signal (CSI-RS) symbol and Physical Downlink Shared Channel (PDSCH) data that are received using the second Rx beam.
The apparatus of claim 1, 2, or 3, wherein the BRRS transmission comprises eight BRRS OFDM symbols and the one or more processors and memory are further configured to refine up to eight Rx beams based on the eight BRRS OFDM symbols.
The apparatus of claim 7, wherein the one or more processors and memory are further configured to:
take BRRS measurements using one or more initial Rx beams; signal the transceiver to send the BRRS measurements to the cellular base station; and
refine the up-to-eight Rx beams using one or more initial Rx beams.
The apparatus of claim 1, 2, 3, 4, 5, 6, 7, or 8, wherein the BRRS transmission comprises one or more BRRS OFDM symbols and the one or more BRRS symbols contain a plurality of BRRS antenna ports.
10. The apparatus of claim 9, wherein the one or more processors and memory are further configured to:
measure a BRRS port group, wherein the BRRS port group includes two antenna ports of the plurality of antenna ports, and wherein the two antenna ports are frequency division multiplexed or code division multiplexed; and
refine the Rx beam based on the measuring of the BRRS port group.
11. The apparatus of claim 10, wherein the two antenna ports are mapped to all
subcarriers used for the BRRS transmission and are generated based on different cyclic shifts.
12. The apparatus of claim 9, wherein the plurality of antenna ports is indicated by an antenna port configuration of a Demodulation Reference Signal (DMRS) of an extended Physical Downlink Control Channel (xPDCCH) that is associated with the BRRS transmission.
13. The apparatus of claim 1, 2, 3, 4, 5, 6, 7, or 8, wherein the BRRS transmission comprises one or more BRRS OFDM symbols and the BRRS transmission is mapped in an Orthogonal Frequency Division Multiple Access (OFDMA) symbol between an extended Physical Downlink Control Channel (xPDCCH) and an extended Physical Downlink Shared Channel (xPDSCH) or is mapped in the OFDMA symbol before the xPDCCH.
14. An apparatus of a cellular base station in a Multiple Input Multiple Output
(MIMO) system, the apparatus comprising one or more processors and memory configured to:
identify a base sequence to be used for a Beam Refinement Reference Signal (BRRS), wherein the base sequence is a Zadoff-Chu sequence or a Quadrature Phase Shift Keying (QPSK) sequence; identify at least one transmission beam (Tx) to be used for sending transmissions to a User Equipment (UE); and signal a transceiver associated with the cellular base station to send a Beam Refinement Reference Signal (BRRS) transmission to the UE, wherein the BRRS transmission uses a BRRS subcarrier spacing, and wherein the BRRS subcarrier spacing is larger than a subcarrier spacing of one more following Orthogonal Frequency Division Multiplexing (OFDM) symbols that follow the BRRS transmission.
15. The apparatus of claim 14, wherein the BRRS subcarrier spacing is predefined in a specification or the one or more processors and memory are further configured to configure the BRRS subcarrier spacing via Downlink Control Information (DCI), master information broadcasting (MIB), system information broadcasting (SIB), or radio resource control (RRC) signaling.
16. The apparatus of claim 14 or 15, wherein the BRRS subcarrier spacing
( fBRRS) is equal to four times the subcarrier spacing of the one or more following OFDM symbols (Δ ) such that AfBRRs = 4■ Af.
17. The apparatus of claim 14, 15, or 16, wherein the BRRS transmission comprises four BRRS OFDM symbols.
18. The apparatus of claim 14, 15, or 16, wherein the BRRS transmission comprises eight BRRS OFDM symbols.
19. The apparatus of claim 18, wherein the one or more processors and memory are further configured to:
signal the transceiver to send a first Channel State Information Reference Signal (CSI-RS) symbol to the UE using a first Tx beam; and signal the transceiver to send a second Channel State Information Reference Signal (CSI-RS) symbol using a second Tx beam.
20. The apparatus of claim 14, 15, 16, 17, 18, or 19, wherein the BRRS transmission comprises one or more BRRS OFDM symbols and the one or more BRRS symbols contain a plurality of BRRS antenna ports.
21. The apparatus of claim 20, wherein the one or more processors and memory are further configured to:
signal the transceiver to frequency-division multiplexed a BRRS sequence for each BRRS antenna port of the plurality of BRRS antenna ports; and
signal the transceiver to send each BRRS antenna port of the plurality of BRRS antenna ports to the UE from the cellular base station using a respective antenna port.
22. The apparatus of claim 20, wherein the one or more processors and memory are further configured to: signal the transceiver to indicate the plurality of antenna ports to the UE using an antenna port configuration of a Demodulation Reference Signal (DMRS) of a Physical Downlink Control Channel (xPDCCH) that is associated with the BRRS transmission.
23. The apparatus of claim 14, wherein the BRRS transmission comprises one or more BRRS OFDM symbols and the one or more processors and memory are further configured to map the BRRS transmission between an extended Physical Downlink Control Channel (xPDCCH) and an extended Physical Downlink Shared Channel (xPDSCH) or before the xPDCCH.
24. The apparatus of claim 14, 15, 16, 17, 18, 19, 20, 21, 22, or 23, wherein the one or more processors and memory are further configured to signal the transceiver associated with the cellular base station to send a BRRS format indicator to the UE in Downlink Control Information (DO), wherein the BRRS format indicator indicates a format to which the BRRS transmission conforms.
25. A computer-readable medium containing instructions thereon which, when
executed by one or more processors, perform the following: identifying a Beam Refinement Reference Signal (BRRS) transmission sent from a cellular base station, wherein the BRRS transmission either:
uses a BRRS subcarrier spacing ( fBRRS) that is equal to four times a subcarrier spacing of one or more following OFDM symbols (Δ ) that follow the BRRS transmission such that fBRRS = 4■ Δ/, or
uses a time domain replica waveform and is equal to the subcarrier spacing of the one or more following OFDM symbols;
refining a Reception (Rx) beam based on the BRRS transmission; and
signaling a transceiver to use the Rx beam to receive the one or more following OFDM symbols. The computer-readable medium of claim 25, further containing instructions thereon which, when executed by one or more processors, perform the following:
refining up to four Rx beams based on four BRRS OFDM symbols that are included in the BRRS transmission.. The computer-readable medium of claim 25 or 26, further containing instructions thereon which, when executed by one or more processors, perform the following:
refining a first Rx beam based on four first BRRS OFDM symbols included in the BRRS transmission; and
refining a second Rx beam based on four second BRRS OFDM symbols included in the BRRS transmission. The computer-readable medium of claim 25, further containing instructions thereon which, when executed by one or more processors, perform the following:
refining up to eight Rx beams based on eight BRRS OFDM symbols included in the BRRS transmission.
PCT/US2016/025777 2015-11-11 2016-04-02 Mechanisms for beam switching and refinement in cellular systems WO2017082952A1 (en)

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