WO2017099834A1 - Channel state information reference signal generation with reduced orthogonal frequency division multiplexing symbols - Google Patents

Abstract

A cell network device can operate to generate or process multiple channel state information reference signals (CSI-RSs) within a single orthogonal frequency division multiplexing (OFDM) symbol based on a large subcarrier spacing or an interleaved frequency division multiple access (IFDMA) scheme. A configuration can be generated that indicates the large subcarrier spacing or the IFDMA scheme. The larger subcarrier spacing can comprises a larger subcarrier than a physical downlink channel, such as a 5G physical downlink shared channel (xPDSCH), and a value of the larger subcarrier spacing can be pre-defined by the eNB, configured by a higher signalling layer than a physical layer or configured via a downlink control information (DCI).

Description

CHANNEL STATE INFORMATION REFERENCE SIGNAL GENERATION WITH REDUCED ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SYMBOLS

REFERENCE TO RELATED APPLICATIONS

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

62/264,206 filed December 7, 2015, entitled "CSI-RS SIGNAL GENERATION WITH REDUCED OFDM SYMBOLS", the contents of which are herein incorporated by reference in their entirety.

FIELD

[0002] The present disclosure relates to channel state information reference signals (CSI-RS), and more specifically, to the generation of channel state information reference signals with reduced orthogonal frequency division multiplexing (OFDM) symbols.

BACKGROUND

[0003] In 3GPP systems, the transmission time is partitioned into units of a frame that are a particular length in time (e.g., milliseconds) and further divided into subframes (e.g., as subframe #0 to subframe #9). While the LTE frequency division duplexing (FDD) system may have 10 contiguous downlink subframes and 1 0 contiguous uplink subframes, for example, in each frame, the LTE time-division duplexing (TDD) system may have different downlink-uplink allocations, whose downlink and uplink subframe assignments are different. The frequency domain resource may be partitioned into subcarriers up to a full bandwidth for a time symbol. One physical resource block (PRB) may be defined over a rectangular 2-D frequency-time resource area (e.g., covering 12 contiguous subcarriers over the frequency domain and subframe over the time domain wherein the PRB holds 12^*14=168 resource elements (RE) for a normal-cyclic prefix (CP) subframe).

[0004] In addition, each subframe can contain two equal-length slots. Each slot may contain a number of orthogonal frequency division multiplexing (OFDM) symbols (e.g., 10 symbols). In a normal-CP configuration, the OFDM symbols are indexed per slot, where the symbol index runs from 0 to 6; the OFDM symbols can be also indexed per subframe, where the symbol index runs from 0 to 1 3, for example. In addition, each subframe can also contain two equal-length slots. Each regular subframe may be partitioned into two parts: the PDCCH (Physical Downlink Control Channel) region and the PDSCH (Physical Downlink Shared Channel) region. The PDCCH region normally occupies the first several symbols per subframe and carries the handset specific control channels, and the PDSCH region occupies the rest of the subframe and carries the general-purpose traffic.

[0005] Channel state information reference signals (CSI-RSs) were introduced in the Long Term Evolution (LTE)-Advanced (LTE-A) specification in release 10 (Rel-10) to support channel measurements for CSI calculation and reporting. The CSI-RS of LTE systems can support up to 8 antenna ports {15-22} that can have one subframe with a density of 1 resource element (RE) per antenna port per pair of physical resource blocks (PRBs).

[0006] Multiple-input-multiple-output (MIMO) technology in LTE-A Rel-8 and subsequent MIMO enhancements in Rel-10 and Rel-1 1 were designed to support antenna configurations at an enhanced or evolved NodeB (eNB). In massive MIMO systems, the CSI-RS may be used for a user equipment (UE) (e.g., a wireless or mobile network device) to measure the downlink CSI. To allow more transmit (Tx) beams for CSI-RS within one subframe, more symbols allocated to the CSI-RS may be needed. However this may increase the overhead of CSI-RS transmission so that it may have an impact on the user throughput.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a block diagram illustrating an example user equipment (UE) useable in connection with various aspects described herein.

[0008] FIG. 2 is a block diagram of a system employable in an enhanced/evolved node B (eNB), other base station, or UE that can generate channel state information reference signals (CSI-RSs) with reduced OFDM symbols according to various aspects described herein.

[0009] FIG. 3 illustrates a block diagram of large subcarrier spacing and IFDMA based CSI-RSs according to various aspects described herein.

[0010] FIG. 4 illustrates a block diagram of CSI-RSs within an OFDM symbol according to various aspects described herein.

[0011] FIG. 5 illustrates a process flow for generating CSI-RS according to various aspects or embodiments being disclosed.

[0012] FIG. 6 is a schematic example of a wireless environment that can operate in accordance with aspects disclosed. [0013] FIG. 7 is an illustration of an example wireless network platform to implement various aspects disclosed

DETAILED DESCRIPTION

[0014] The present disclosure will now be described with reference to the attached drawing figures, wherein like reference numerals are used to refer to like elements throughout, and wherein the illustrated structures and devices are not necessarily drawn to scale. As utilized herein, terms "component," "system," "interface," and the like are intended to refer to a computer-related entity, hardware, software (e.g., in execution), and/or firmware. For example, a component can be a processor, a process running on a processor, a controller, a circuit or a circuit element, an object, an executable, a program, a storage device, a computer, a tablet PC and/or a mobile phone with a processing device. By way of illustration, an application running on a server and the server can also be a component. One or more components can reside within a process, and a component can be localized on one computer and/or distributed between two or more computers. A set of elements or a set of other components can be described herein, in which the term "set" can be interpreted as "one or more."

[0015] Further, these components can execute from various computer readable storage media having various data structures stored thereon such as with a module, for example. The components can communicate via local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and/or across a network, such as, the Internet, a local area network, a wide area network, or similar network with other systems via the signal).

[0016] As another example, a component can be an apparatus with specific functionality provided by mechanical parts operated by electric or electronic circuitry, in which the electric or electronic circuitry can be operated by a software application or a firmware application executed by one or more processors. The one or more processors can be internal or external to the apparatus and can execute at least a part of the software or firmware application. As yet another example, a component can be an apparatus that provides specific functionality through electronic components or elements without mechanical parts; the electronic components can include one or more processors therein to execute software and/or firmware that confer(s), at least in part, the functionality of the electronic components. [0017] Use of the word exemplary is intended to present concepts in a concrete fashion. As used in this application, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless specified otherwise, or clear from context, "X employs A or B" is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then "X employs A or B" is satisfied under any of the foregoing instances. In addition, the articles "a" and "an" as used in this application and the appended claims should generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form. Furthermore, to the extent that the terms "including", "includes", "having", "has", "with", or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term

"comprising".

[0018] 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. INTRODUCTION

[0019] In consideration of the above described deficiencies, network devices (e.g., multi-input multi-output network devices, base stations, macro cells network devices, access points (APs), access controllers (ACs), eNBs, small cells, UEs, or other similar devices) described herein can operate to better enable or efficiently reduce the overhead of the generation of channel state information reference signals (CSI-RSs) transmission. A CSI-RS symbol can be a cell specific reference signal that is defined by 3GPP for enabling channel or cell measurements by a UE, such as for channel estimation or channel quality measurement operations, for example.

[0020] In one example, CSI-RS can be generated by increasing the subcarrier spacing and utilizing a larger subcarrier spacing based CSI-RS scheme within one OFDM symbol. The subcarrier spacing of the CSI-RS can be enlarged to accommodate a greater number of CSI-RS symbols compared to other downlink channels, such as a physical downlink shared channel (PDSCH) (e.g., a 5G PDSCH or x-PDSCH, or the like), physical downlink control channel (PDCCH) or other physical downlink channel from an eNB to a UE, for example. As such, increasing the subcarrier spacing by increasing frequency allocation, and further decreasing the OFDM symbol duration or dividing the OFDM symbol into additional parts, can facilitate a larger subcarrier spacing as a CSI-RS scheme with an increased number of CSI-RS parts / replicas. As such, an additional transmit beams can be designated within one OFDM symbol for UEs to measure.

[0021] In another example, an interleaved frequency division multiple access (IFDMA) based CSI-RS scheme can be utilized to generate and transmit the CSI-RS within one OFDM symbol. Multiple beams can be applied or mapped within the CSI-Rs, and different antenna ports different beams can be utilized for the transmission. The UE is then able to measure a beam via the beams applied to a plurality of CSI-RS replicas or parts within an OFDM symbol. As such, more beams (e.g., one, two or three more) can be allocated to a single OFDM symbol (e.g., four beams in one OFDM symbol). As such, the overhead of the CSI-RS can be further reduced. Additional aspects and details of the disclosure are further described below with reference to figures.

[0022] Embodiments described herein may be implemented into a system using any suitably configured hardware or software. FIG. 1 illustrates, for one embodiment, example components of a network device 100, which can also represent a wireless device (e.g., a user equipment (UE)) or other network device (e.g., an eNB, network entity or the like). In some embodiments, the device 100 can include application circuitry 102, baseband circuitry 1 04, radio frequency (RF) circuitry 106, front-end module (FEM) circuitry 108 and one or more antennas 1 1 0, coupled together at least as shown.

[0023] The application circuitry 102 can include one or more application processors. For example, the application circuitry 102 can include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor(s) can include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors can be coupled with or can include memory/storage and can be configured to execute instructions stored in the memory/storage to enable various applications or operating systems to run on the system.

[0024] The baseband circuitry 104 can include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 104 can include one or more baseband processors or control logic to process baseband signals received from a receive signal path of the RF circuitry 106 and to generate baseband signals for a transmit signal path of the RF circuitry 106. Baseband processing circuity 104 can interface with the application circuitry 102 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 106. For example, in some embodiments, the baseband circuitry 104 can include a second generation (2G) baseband processor 104a, third generation (3G) baseband processor 104b, fourth generation (4G) baseband processor 104c, or other baseband processor(s) 104d for other existing generations, generations in development or to be developed in the future (e.g., fifth generation (5G), 6G, etc.). The baseband circuitry 104 (e.g., one or more of baseband processors 104a-d) can handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 106. The radio control functions can 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 1 04 can include Fast-Fourier Transform (FFT), precoding, or constellation mapping/demapping functionality. In some embodiments, encoding/decoding circuitry of the baseband circuitry 104 can include convolution, tail-biting convolution, turbo, Viterbi, or Low Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functionality are not limited to these examples and can include other suitable functionality in other embodiments.

[0025] In some embodiments, the baseband circuitry 104 can 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), or radio resource control (RRC) elements. A central processing unit (CPU) 104e of the baseband circuitry 104 can be configured to run elements of the protocol stack for signaling of the PHY, MAC, RLC, PDCP or RRC layers. In some

embodiments, the baseband circuitry can include one or more audio digital signal processor(s) (DSP) 104f. The audio DSP(s) 104f can be include elements for compression/decompression and echo cancellation and can include other suitable processing elements in other embodiments. Components of the baseband circuitry can 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 104 and the application circuitry 102 can be implemented together such as, for example, on a system on a chip (SOC).

[0026] In some embodiments, the baseband circuitry 104 can provide for

communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry 104 can support communication with an evolved universal terrestrial radio access network (EUTRAN) 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 104 is configured to support radio communications of more than one wireless protocol can be referred to as multi-mode baseband circuitry.

[0027] RF circuitry 106 can enable communication with wireless networks

using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 106 can include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 106 can include a receive signal path which can include circuitry to down-convert RF signals received from the FEM circuitry 108 and provide baseband signals to the baseband circuitry 104. RF circuitry 106 can also include a transmit signal path, which can include circuitry to up- convert baseband signals provided by the baseband circuitry 104 and provide RF output signals to the FEM circuitry 108 for transmission.

[0028] In some embodiments, the RF circuitry 106 can include a receive signal path and a transmit signal path. The receive signal path of the RF circuitry 106 can include mixer circuitry 1 06a, amplifier circuitry 106b and filter circuitry 106c. The transmit signal path of the RF circuitry 106 can include filter circuitry 106c and mixer circuitry 106a. RF circuitry 106 can also include synthesizer circuitry 106d for synthesizing a frequency for use by the mixer circuitry 106a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 106a of the receive signal path can be configured to down-convert RF signals received from the FEM circuitry 108 based on the synthesized frequency provided by synthesizer circuitry 106d. The amplifier circuitry 106b can be configured to amplify the down-converted signals and the filter circuitry 106c can 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 can be provided to the baseband circuitry 104 for further processing. In some embodiments, the output baseband signals can be zero- frequency baseband signals, although this is not a requirement. In some embodiments, mixer circuitry 1 06a of the receive signal path can comprise passive mixers, although the scope of the embodiments is not limited in this respect.

[0029] In some embodiments, the mixer circuitry 106a of the transmit signal path can be configured to up-convert input baseband signals based on the synthesized frequency provided by the synthesizer circuitry 106d to generate RF output signals for the FEM circuitry 108. The baseband signals can be provided by the baseband circuitry 104 and can be filtered by filter circuitry 106c. The filter circuitry 106c can include a low-pass filter (LPF), although the scope of the embodiments is not limited in this respect.

[0030] In some embodiments, the mixer circuitry 106a of the receive signal path and the mixer circuitry 106a of the transmit signal path can include two or more mixers and can be arranged for quadrature downconversion or upconversion respectively. In some embodiments, the mixer circuitry 106a of the receive signal path and the mixer circuitry 106a of the transmit signal path can include two or more mixers and can be arranged for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuitry 106a of the receive signal path and the mixer circuitry 106a can be arranged for direct downconversion or direct upconversion, respectively. In some embodiments, the mixer circuitry 1 06a of the receive signal path and the mixer circuitry 106a of the transmit signal path can be configured for super-heterodyne operation.

[0031] In some embodiments, the output baseband signals and the input baseband signals can 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 can be digital baseband signals. In these alternate embodiments, the RF circuitry 106 can include analog-to-digital converter (ADC) and digital-to-analog converter (DAC) circuitry and the baseband circuitry 104 can include a digital baseband interface to communicate with the RF circuitry 106.

[0032] In some dual-mode embodiments, a separate radio IC circuitry can be provided for processing signals for each spectrum, although the scope of the

embodiments is not limited in this respect.

[0033] In some embodiments, the synthesizer circuitry 106d can be a fractional-N synthesizer or a fractional N/N+1 synthesizer, although the scope of the embodiments is not limited in this respect as other types of frequency synthesizers can be suitable. For example, synthesizer circuitry 106d can be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer comprising a phase-locked loop with a frequency divider. [0034] The synthesizer circuitry 106d can be configured to synthesize an output frequency for use by the mixer circuitry 106a of the RF circuitry 1 06 based on a frequency input and a divider control input. In some embodiments, the synthesizer circuitry 106d can be a fractional N/N+1 synthesizer.

[0035] In some embodiments, frequency input can be provided by a voltage controlled oscillator (VCO), although that is not a requirement. Divider control input can be provided by either the baseband circuitry 104 or the applications processor 102 depending on the desired output frequency. In some embodiments, a divider control input (e.g., N) can be determined from a look-up table based on a channel indicated by the applications processor 1 02.

[0036] Synthesizer circuitry 1 06d of the RF circuitry 106 can include a divider, a delay-locked loop (DLL), a multiplexer and a phase accumulator. In some embodiments, the divider can be a dual modulus divider (DMD) and the phase accumulator can be a digital phase accumulator (DPA). In some embodiments, the DMD can be configured to divide the input signal by either N or N+1 (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL can 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 can 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.

[0037] In some embodiments, synthesizer circuitry 106d can be configured to generate a carrier frequency as the output frequency, while in other embodiments, the output frequency can 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 can be a LO frequency (fLO). In some embodiments, the RF circuitry 106 can include an IQ/polar converter.

[0038] FEM circuitry 108 can include a receive signal path which can include circuitry configured to operate on RF signals received from one or more antennas 1 10, amplify the received signals and provide the amplified versions of the received signals to the RF circuitry 106 for further processing. FEM circuitry 108 can also include a transmit signal path which can include circuitry configured to amplify signals for transmission provided by the RF circuitry 106 for transmission by one or more of the one or more antennas 1 1 0.

[0039] In some embodiments, the FEM circuitry 108 can include a TX/RX switch to switch between transmit mode and receive mode operation. The FEM circuitry 108 can include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry can 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 106). The transmit signal path of the FEM circuitry 108 can include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 106), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 1 1 0.

[0040] In some embodiments, the device 100 can include additional elements such as, for example, memory/storage, display, camera, sensor, or input/output (I/O) interface.

[0041] In accordance with various embodiments described herein, techniques can be employed to generate OFDM symbols with multiple transmit beams mapped with multiple CSI-RS symbols or CSI-RS replicas (or parts). A component of the device 100 can be configured to generate / transmit (e.g., via an eNB), or process / receive (via a UE), CSI-RSs within a single OFDM symbol. The OFDM symbol can have a large- subcarrier spacing OFDM symbol that includes a cyclic prefix (CP) for each CSI-RS of the plurality of CSI-RS, or the OFDM symbol can include a single CP for each CSI-RS of the CSI-RSs within the OFDM symbol as part of an IFDMA scheme so that the OFDM symbol can be generated, processed, transmitted, or received according to IFDMA.

[0042] A processor or other component (e.g., the baseband circuitry 104 or RF circuitry 106) of the device 100 can then generate a configuration that can indicate the transmission scheme or about the configuration scheme of the CSI-RS transmission of the CSI-RSs based on a communication with the eNB (e.g., the device 200 as an eNB of FIG. 2). The configuration that is generated can comprise a downlink control information (DCI) indicator to indicate a trigger of CSI-RS as well as a beam refinement reference signal (BRRS) transmission in a subframe.

[0043] In one example, the configuration can include an indicator that can includes a number of bits (e.g., two bits or the other number) indicating one or more different formats of the transmission. For example, the indicator can include two bits having a value of "00" indicating that that both CSI-RS and BRRS are not to be transmitted. The indicator can have a value of "01 " that indicates only CSI-RS is to be transmitted. In another example, the indicator can have a value of "10" indicating that only BRRS is to be transmitted. In addition, the indicator can have a value of "1 1 " that indicates that CSI- RS and BRRS are to be transmitted.

[0044] In other embodiments, different transmission (Tx) beams can be mapped or processed from a mapping to different CSI-RS Group (CRGs), with each OFDM symbol having about four CRGs. The OFDM symbol generated / transmitted according to the IFDMA has a larger CP than CPs in large-spacing OFDM symbol that includes multiple transmit beams mapped at different CSI-RS parts or replicas within the OFDM symbol. Each CSI-RS part can be further divided into eight CRGs, wherein each CRG

corresponds to or includes two consecutive antenna ports (APs). For the IFDMA scheme, each CSI-RS can be mapped to every ^Ni subcarriers in one OFDM symbol, and remaining subcarriers can be set to zero. Further, ^Ni time domain replica signals (CSI-RS parts) of the OFDM symbol can be generated for each CSI-RS, in which different Tx beams can be applied to each CSI-RS replica signal where ^Nt can be a value or positive integer that is greater than one.

[0045] For the large subcarrier spacing OFDM symbol, the large-spacing OFDM symbol can include N_t CSI-RS transmissions, where the value of N_t is predefined, configured by higher layer signaling, or indicated in the DCI. The large subcarrier spacing OFDM symbol can have a larger CSI-RS subcarrier spacing than a subcarrier spacing of a physical downlink shared channel (xPDSCH), for example. As stated, the value of the CSI-RS subcarrier spacing for the large-spacing OFDM symbol can be predefined or predetermined by the eNB, configured by higher layer signaling, or indicated by the DCI. In addition, the symbol length for each CSI-RS can be smaller than a symbol length of the xPDSCH or other physical downlink channel, and different Tx beams can be applied to different the different CSI-RS symbols (equivalent CSI-RS parts or replica signals) or CRGs.

[0046] Referring to FIG. 2, illustrated is an example of a wireless communication system or device 200 in accordance with various aspects being described such as a UE or eNB or other network device of a communication wireless network. The wireless communication device 200 can be a transceiver or a receiver device (e.g., an OFDM receiver or the other receiver) that is included with the FEM circuitry 108 or can be external thereto. The FEM circuitry 108', for example, can comprise a processor 210 communicatively coupled to memory or data store 240 (e.g., a memory or memory array), a receiver circuitry / component 230, and a transmitter circuitry / component 220. The data store 240 can include instructions that can be implemented by processor 210, transmitter circuitry 220, or receiver circuitry 230 to implement various aspects described herein. The processor 210 can comprise any number of processors as part of or as the baseband circuitry 104 or the RF circuitry 106 of FIG. 1 , for example. In addition, the components described herein can be included in the same device or a different device such as for cloud-RAN (C-RAN) or other external device operation within a system of components.

[0047] In addition, the memory 240 can comprise one or more machine-readable medium / media including instructions that, when performed by a machine or component herein cause the machine to perform acts of the method or of an apparatus or system for concurrent communication using multiple communication technologies according to embodiments and examples described herein. It is to be understood that aspects described herein can be implemented by hardware, software, firmware, or any combination thereof. When implemented in software, functions can be stored on or transmitted over as one or more instructions or code on a computer-readable medium (e.g., the memory described herein or other storage device). Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media or a computer readable storage device can be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD- ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or other tangible and/or non-transitory medium, that can be used to carry or store desired information or executable instructions. Also, any connection is properly termed a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer- readable media.

[0048] The receiver circuitry 230 and the transmitter circuitry 220 can each comprise one or more receiver chains, or one or more transmitter chains, respectively, which can operate to process one or more signals for demodulation or modulation. Each circuitry 220, 230 can comprise any number of components comprising one or more filters, analog digital converters, digital to analog converters, amplifiers, antennas or other signal processing components (not shown), as demonstrated in FIG. 1 with respect to the baseband circuitry 104 or RF circuitry 106, for example. The receiver circuitry component 230 or transmitter circuitry component 220 can operate to process or generate CSI-RSs based on a quadrature phase shift keying (QPSK) signal with a scramble sequence that is initialized by a cell identifier (ID), a virtual cell ID, a beam reference signal (BRS) group ID, or a CSI-RS ID with subframe index or a slot/frame index, for example. The scramble sequence for a CSI-RS sequence can be generated for each CSI-RS based on a Zadoff-Chu (ZC) sequence, for example, or another sequence generating processes. The root index of the ZC sequence, for example, can further be a function of a cell ID, a virtual cell ID, or a BRS group ID, and the CSI-RS ID or subframe/slot/frame index. A virtual cell, for example, can be an intelligent distributed antenna system (IDAS) with capacity routing capability. A beam reference signal can enable a UE to measure a transmit beam from the eNB or a group of beams from the eNB mapping different CSI-RS antenna ports (APs) to different subcarriers reserved for the CSI-RS transmission.

[0049] In one embodiment, the processor 210 with the receiver circuitry component 230 or transmitter circuitry component 220 can process a CSI-RS via one or more inputs or outputs 245 by multiplexing the CSI-RS for different APs in a frequency division multiplexing (FDM) manner or a code division multiplexing (CDM) manner. A CSI-RS for each AP can be mapped to a same subcarrier, in which each AP can be generated to correspond with different cyclic shifts (e.g., in the cyclic prefix), wherein a cyclic shift value for each AP can be a function of an AP index.

[0050] In addition or alternatively, a CSI-RS for each AP can be mapped to a different subcarrier, wherein each AP can generated or made to be associated with a same cyclic shift or different cyclic shifts. Further, the CSI-RS can also be mapped to a first subcarrier, while setting a second subcarrier to zero in order to provide for no transmission or direct current as being set to zero, skipped, muted or transmitted with zero power, for example.

[0051] The CSI-RS can be generated to transmit with N_l OFDM symbols with N_p antenna ports or panels, and there can be a maximum N_t x N_p Tx beams that can be measured with a subframe. In one example, N_t can be 2 and N_p can be 4. To reduce the overhead of CSI-RS, only a single OFDM symbol could be used for the CSI-RS transmission. As discussed herein, a large subcarrier spacing based CSI-RS can be used to transmit the CSI-RS with N_l x N_p Tx beams within 1 OFDM symbol, or an IFDMA based CSI-RS can be used.

[0052] Referring to FIG. 3, illustrates an example time domain signal pattern of CSI- RSs 300 as large subcarrier spacing based CSI-RS 302 and an IFDMA based CSI-RS 304 in accordance with various aspects or embodiments. The CSI-RSs 302 and 304 can be generated by the eNB or UE of 200 of FIG. 2 or any of the circuitry / components of FIG. 1 as part of a UE or eNB, for example.

[0053] In one embodiment, the OFDM symbol 302 can be comprise CSI-RS symbols 31 0 and 312 with cyclic prefixes 306 and 308 respectively. The CPs 306 and 308 can have about the same length as a standard or normal CP of a standard OFDM symbol in the OFDM symbol 302 with a large subcarrier spacing based CSI-RS. Each CP 306 and 308 can be mapped to different CSI-RS (part or replica) components 314, 316. In comparison, the OFDM symbol 304 can comprise a larger CP 31 8 that covers both or multiple CSI-RS parts or replicas 320 and 322, for example. Although the OFDM symbol 302 comprises two CSI-RS symbols 310 and 312, or CSI-RS replicas 320, 322, respectively, additional CSI-RS symbols can be added, such as up to four CSI-RS symbols, in which each CSI-RS symbol maps or is associated with different transmit beams for channel estimation or measurement by a UE. In particular, one CSI-RS group (CRG) can be correspond to one transmit beam, which comprises two consecutive APS each, and multiple CRGs allocated to each CSI-RS symbol (or replica).

[0054] In the large subcarrier spacing based CSI-RS, as one embodiment, the subcarrier spacing can be increased (e.g., about 75 kHz to 300 kHz, for a four to five times increase) for the generation or processing of the CSI-RS (e.g., via the processor 21 0 of FIG. 2). In addition, the symbol duration for the CSI-RSs parts or replicas 314, 31 6 can be reduced. The OFDM symbol 302 can be divided into two sections/parts, or two symbols 310, 312, for example. The OFDM symbol 302 can be divided further into additional sections or parts (e.g., four sections/parts, or four CSI-RS symbols) than shown in order to further utilize a fraction (e.g., a quarter) of the OFDM symbol 302 for mapping analogous or corresponding to transmit beams in comparison to previous standards or other physical downlink channels (e.g. PDSCH). As such, additional transmit beams (e.g., four or more) can be transmitted to a UE for measurements on each OFDM symbol 302.

[0055] In another embodiment, the processor 21 0 or other component of the device 100 or 200 of FIGs. 1 or 2 can generate / process a configuration of a transmission. The configuration can include, for example, an indicator that is added in the DCI to trigger measurements or inform of a CSI-RS and a BRRS transmission in a subframe, and whether the BRRS and the CSI-RS could have the same format. In one example, the trigger or indication can comprise 2 bits, where the trigger having a value of "00" can indicate that both CSI-RS and BRRS are not transmitted, the trigger having a value of "01 " can indicate that only the CSI-RS is being transmitted, the trigger having a value of "10" could indicate that only the BRRS is transmitted, and the trigger having a value of "1 1 " could indicate that the CSI-RS and the BRRS together are transmitted. These configurations are intended as examples and one of ordinary skill in the art can recognize that different bit numbers of the two bit configuration could designate different transmission combinations of the CSI-RS and the BRRS also.

[0056] For the large subcarrier spacing based CSI-RS, the subcarrier spacing for the CSI-RS can be increased as: Afcsi-Rs = ^Ni x Δ/ , where Af denotes the subcarrier spacing for a physical downlink shared channel, such as a 5G physical downlink shared channel (xPDSCH). Then with the same sampling rate, in one OFDM symbol, there can be Ni CSI-RS transmission. In an embodiment, the value of N_t can be pre-defined by the network, system, or eNB, configured by higher layer signaling or indicated in the DCI to the UE.

[0057] In another embodiment, the CSI-RS can be generated based on the QPSK signal with a scramble sequence initialized by a cell identifier (ID), a virtual cell ID, a beam reference signal (BRS) group ID or a CSI-RS ID and subframe index or a slot/frame index. For example, the CSI-RS base sequence can be generated according to the following equation:

[0058] r(m) = j= (l - 2c(2m)) + j j= (1 - 2c(2m) + 1)), m = 0,1, - , -N,

where denotes a maximum number of resource blocks (RBs) in downlink; c(m) indicates a pseudo-random sequence, which can be the same as clause 7.2 in 3GPP TS 36.21 1 and initialized by the subframe index and the CSI-RS ID, where CSI-RS ID can be configured by the higher layer than a physical layer of a computer networking OSI model, for example.

[0059] In another embodiment, the OFDM 304 comprises CSI-RS symbols based on an IFDMA based scheme. Here, the CP 31 8 is larger than the CP 306 from the large subcarrier spacing based CSI-RS generation, or from normal / standard CPs. In addition, the CP 318 can correspond to multiple CSI-RS replicas (e.g., 320 and 322), or to additional replicas within one OFDM symbol. The CP318 is thus larger than the CP 306 from the large subcarrier spacing based CSI-RS generation.

[0060] Multiple beams can be mapped to multiple CSI-RS replicas 320, 322 in one OFDM symbol whether the subcarrier spacing is enlarged or not by utilizing IFDMA based CSI-RS. For the IFDMA based CSI-RS, the CSI-RS can be mapped to every JV₍ subcarriers in one OFDM symbol, while the remaining subcarriers can be set to zero or transmitted with zero power, for example. The IFDMA based CSI-RS generation can be used to generate N_t time domain replica signals 320, 322 for the CSI-RS in a single OFDM symbol and different Tx beams can be applied to each replica.

[0061] In an embodiment, the CSI-RS sequence can be generated based on the Zadoff-Chu (ZC) sequence, for example. The root index of the ZC sequence can be defined as a function of a cell ID, a virtual cell ID, a BRS group ID or CSI-RS ID or a subframe / slot / frame index. The CSI-RS for different APs can be multiplexed in a frequency division multiplexing (FDM) or code division multiplexing (CDM) manner. In one example, the CSI-RS for each AP can be mapped via the processor 21 0 or other component discussed herein to the same subcarrier, which can be generated with different cyclic shifts via the CPs, for example. In particular, the cyclic shift value for each AP can be defined as a function of an AP index.

[0062] In another example, the CSI-RS for each AP can be mapped to different subcarriers within a full bandwidth. In this case, the same or different cyclic shift values can be applied to generate the CSI-RS signals for each AP.

[0063] In another embodiment, the CSI-RS may be mapped from the first subcarrier, and can skip the direct current (DC) or middle subcarrier. Thus the subcarrier |NJcV²J , which can be utilized to map one CSI-RS sequence could be filled with a zero, where Nsc denotes the total subcarrier number for the downlink. For example, if 1 ,200 subcarriers are mapped to each OFDMA symbol, a single CSI-RS could include 600 subcarriers if two are mapped in each OFDMA symbol as illustrated in FIG. 2. The first subcarrier can be zero as well, such as for a resource block with 1 00 blocks, for example.

[0064] Referring to FIG. 4, illustrated is another example of a CSI-RS resource mapping structure, such as for a large subcarrier spacing in accordance with various embodiments being described. The transmit beams can be mapped or applied to different CRGs by an eNB (e.g., as device 200) and communicated in a transmission to a component of a UE, which can decode and utilize the OFDM symbol 406 to measure particular transmit beams.

[0065] In one example embodiment, the APs 15-30 are patterned and illustrated within a legend 402 having sixteen patterned blocks with eight different patterns. The CSI-RS legend 402 can also represent a single CSI-RS symbol 402 or a single subframe of duration. The single OFDM symbol 406 therefore comprises a total of two CSI-RS symbols 410 and 41 2, in the illustrated example configuration scheme. For example, CSI-RS symbol 410 and CSI-RS symbol 412 each comprise sixteen blocks as well as 8 CRGs, with each CRG 404 comprising two consecutive APs each or two differently patterned blocks of a given CSI-RS symbol.

[0066] The differently patterned blocks that are illustrated can correspond to APs 15- 30 based on their pattern and are mapped and use for transmitting blocks of the CSI-Rs symbol 410 and 41 2 accordingly. For example the two bottom blocks adjacent to one another across the time axis can be mapped and transmitted via AP 15 and AP 23, while the two differently patterned blocks next to one another vertically along the frequency axis with increasing frequency can comprise one CRG 404 as well as two consecutive APs. (e.g., vertically from bottom to top, AP 15 and AP 16).

[0067] Each CRG 404 thus can have a different transmit beam applied to it, in which a UE can decode and measure upon reception of the OFDM symbol 406. Therefore, each CSI-RS symbol as represented by the legend 402, and illustrated as CSI-RS symbol 410 and 41 2 in a single OFDM symbol 406, can include 8 CRGs. Accordingly, one OFDM symbol 406 can include 16 CRGs and have 16 different transmit beams being mapped thereto as one example configuration being illustrated. As such, the CSI- RS symbols 410 and 412 can be divided into 8 CRGs, with two CSI-RS symbols 410 and 412 being illustrated for one OFDM symbol 406, and the antenna ports for each CRG can comprise 2 consecutive APs.

[0068] In another aspect, the downlink data and control channel 408 is illustrated alongside the OFDM symbol 406 and represents the physical downlink channel(s) (e.g., the PDCCH or PDSCH) as a point for comparison. The duration of the physical downlink channel can be seen as significantly longer compared to the OFDM symbol 406 or the CSI-RS symbols 410 and 412 therein. In other words, the CSI-RS symbols and the OFDM symbols are significantly shorter in duration than a physical downlink channel (e.g., a 5G PDSCH).

[0069] In addition, the subcarrier spacing for each OFDM symbol 406 can also significantly larger or increased in comparison to a physical downlink channel (e.g., PDSCH). In particular, the value of the spacing or length can be pre-defined by the network system, the eNB, a higher layer signaling or higher signaling layer than a physical layer, or pre-defined by the DCI to the UE. As stated previously, different transmit beams can be applied to different CSI-RS symbols, and in particular be allocated to different CRGs so that one transmit beam is applied to one CRG. The CSI- RS sequence can be generated based on a QPSK signal, which can be scrambled or determined by a cell ID, a virtual cell ID, a BRS group ID, or a CSI-RS ID and additionally a subframe index or a slot index, for example. Further, the different CSI-RS APS can be mapped to different subcarriers reserved for the CSI-RS transmissions.

[0070] In other embodiments, as discussed herein, the CSI-RS signaling can be based on an IFDMA scheme and generated according to ZC sequencing, where different APs utilized different cyclic shifts or timings of the CPs. Here, the CSI-RS signals can be mapped to a fixed subcarrier interval where the middle subcarrier can be skipped or transmitted with zero power, for example.

[0071] For the IFDMA based CSI-RS, the CSI-RS can be mapped to every JV₍ subcarriers in one OFDM symbol, while the remaining subcarriers of a bandwidth can be set to zero or transmitted with zero power. The IFDMA based CSI-RS generation can be used to generate N_t time domain replica signals 320, 322 for the CSI-RS in a single OFDM symbol and different Tx beams can be applied to each replica.

[0072] In an embodiment, the CSI-RS sequence can be generated based on the Zadoff-Chu (ZC) sequence, for example. The root index of the ZC sequence can be defined as a function of a cell ID, a virtual cell ID, a BRS group ID or CSI-RS ID or a subframe / slot / frame index. The CSI-RS for different APs can be multiplexed in a frequency division multiplexing (FDM) or code division multiplexing (CDM) manner.

[0073] In one example, the CSI-RS for each AP can be mapped via the processor 21 0 or other component discussed herein to the same subcarrier, which can be generated with different cyclic shifts via the CPs. In particular, the cyclic shift value for each AP can be defined as a function of an AP index.

[0074] In another example, the CSI-RS for each AP can be mapped to different subcarriers. In this case, the same or different cyclic shift values can be applied to generate the CSI-RS signals for each AP.

[0075] In another embodiment, the CSI-RS may be mapped from the first subcarrier, and can skip the direct current (DC) or middle subcarrier. Thus the subcarrier |NJcV²J , which can be utilized to map one CSI-RS sequence could be filled with a zero, where Nsc denotes the total subcarrier number for the downlink.

[0076] While the methods described within this disclosure are illustrated in and described herein as a series of acts or events, it will be appreciated that the illustrated ordering of such acts or events are not to be interpreted in a limiting sense. For example, some acts may occur in different orders and/or concurrently with other acts or events apart from those illustrated and/or described herein. In addition, not all illustrated acts may be required to implement one or more aspects or embodiments of the description herein. Further, one or more of the acts depicted herein may be carried out in one or more separate acts and/or phases.

[0077] Referring to FIG. 5, illustrated is a process flow for a network device (e.g., a UE or an eNB) or a computer-readable medium comprising executable instructions that cause a processor of the network device, in response to execution, to perform operation in a wireless network to communicate CSI-RS with reduced OFDM signals.

[0078] The method 500 initiates at 502 with generating channel state information reference signals (CSI-RSs) within an orthogonal frequency division multiplexing (OFDM) symbol based on a large subcarrier spacing. The subcarrier spacing, for example, can be larger than a physical downlink channel. The larger subcarrier spacing can be larger than a 5G physical downlink shared channel (xPDSCH), for example, and a value of the larger subcarrier spacing is pre-defined by the eNB, configured by a higher signalling layer than a physical layer or configured via a downlink control information (DCI). In generating the large subcarrier spacing based CSI-RS the symbol length of a CSI-RS of the CSI-RSs can be generated as shorter than another symbol length of a xPDSCH, and different transmit or transmission (Tx) beams can be applied or mapped to different CSI-RS symbols/subframes within the same OFDM symbol.

[0079] The generation of the CSI-RSs within an OFDM symbol can additionally or alternatively be based on an interleaved frequency division multiple access (IFDMA) scheme. In generating an IFDMA based CSI-RS a Zadoff-Chu sequence can be utilized. Different cyclic shifts of the CSI-RSs can be assigned to different Aps. In addition, the CSI-RSs can be mapped in a fixed subcarrier interval with a middle subcarrier being skipped.

[0080] At 504, the method can further comprise generating a configuration of a CSI- RS transmission based on the larger subcarrier spacing or the IFDMA scheme. For example, the configuration can provide an indication in a DCI that indicates whether the CSI-RS transmission, a beam refinement reference signal (BRRS) transmission, both the CSI-RS transmission and the BRRS transmission, or neither are within a sub-frame. In addition, the indicator can indicate the scheme by which the CSI-RS is generated for decoding by the UE.

[0081] In other embodiment, a base sequence of a CSI-RS of the CSI-RSs can be generated according to a quadrature phase-shift keying (QPSK) signal that can be determined by a cell identification (ID), a virtual cell ID, a beam reference signal (BRS) group ID, or a CSI-RS ID, and a subframe index or a slot index. A virtual cell, for example, can be an intelligent distributed antenna system (IDAS) with capacity routing capability. A beam reference signal can enable a UE to measure a transmit beam from the eNB or a group of beams from the eNB mapping different CSI-RS antenna ports (APs) to different subcarriers reserved for the CSI-RS transmission based on a cyclic shift value that is a function of an AP index.

[0082] The OFDM symbol can comprise the CSI-RSs (symbols, parts or replicas) mapped to a plurality of transmitting (Tx) beams. Each CRG can have a separate transmit beam mapped thereto for measured by the UE based on a decoding of the OFDM symbol.

[0083] By way of further description with respect to one or more non-limiting environments to generate CSI-RS with reduced OFDM symbols, FIG. 6 is a schematic example wireless environment 600 that can operate in accordance with aspects described herein. In particular, example wireless environment 600 illustrates a set of wireless network macro cells. Three coverage macro cells 602, 604, and 606 include the illustrative wireless environment; however, it is noted that wireless cellular network deployments can encompass any number of macro cells. Coverage macro cells 602, 604, and 606 are illustrated as hexagons; however, coverage cells can adopt other geometries generally dictated by a deployment configuration or floor plan, geographic areas to be covered, and so on. Each macro cell 602, 604, and 606 is sectorized in a 2ττ/3 configuration in which each macro cell includes three sectors, demarcated with dashed lines in Fig. 6. It is noted that other sectorizations are possible, and aspects or features of the disclosed subject matter can be exploited regardless of type of sectorization. Macro cells 602, 604, and 606 are served respectively through base stations or eNodeBs 608, 61 0, and 61 2. Any two eNodeBs can be considered an eNodeB site pair. It is noted that radio component(s) are functionally coupled through links such as cables (e.g., RF and microwave coaxial lines), ports, switches,

connectors, and the like, to a set of one or more antennas that transmit and receive wireless signals (not illustrated). It is noted that a radio network controller (not shown), which can be a part of mobile network platform(s) 614, and set of base stations (e.g., eNode B 608, 610, and 612) that serve a set of macro cells; electronic circuitry or components associated with the base stations in the set of base stations; a set of respective wireless links (e.g., links 616, 618, and 620) operated in accordance to a radio technology through the base stations, form a macro radio access network. It is further noted that, based on network features, the radio controller can be distributed among the set of base stations or associated radio equipment. In an aspect, for universal mobile telecommunication system-based networks, wireless links 616, 618, and 620 embody a Uu interface (universal mobile telecommunication system Air Interface).

[0084] Mobile network platform(s) 614 facilitates circuit switched-based (e.g., voice and data) and packet-switched (e.g., Internet protocol, frame relay, or asynchronous transfer mode) traffic and signaling generation, as well as delivery and reception for networked telecommunication, in accordance with various radio technologies for disparate markets. Telecommunication is based at least in part on standardized protocols for communication determined by a radio technology utilized for

communication. In addition, telecommunication can exploit various frequency bands, or carriers, which include any electromagnetic frequency bands licensed by the service provider network 622 (e.g., personal communication services, advanced wireless services, general wireless communications service, and so forth), and any unlicensed frequency bands currently available for telecommunication (e.g., mmW, the 2.4 GHz industrial, medical and scientific band or one or more of the 5 GHz set of bands, or otherwise). In addition, mobile network platform(s) 614 can control and manage base stations 608, 610, and 612 and radio component(s) associated thereof, in disparate macro cells 602, 604, and 606 by way of, for example, a wireless network management component (e.g., radio network controller(s), cellular gateway node(s), phased arrays, etc.). Moreover, wireless network platform(s) can integrate disparate networks (e.g., Wi-Fi network(s), femto cell network(s), broadband network(s), service network(s), enterprise network(s), and so on). In cellular wireless technologies (e.g., third generation partnership project universal mobile telecommunication system, global system for mobile communication, mobile network platform 614 can be embodied in the service provider network 622.

[0085] In addition, wireless backhaul link(s) 624 can include wired link components such as T1 /E1 phone line; T3/DS3 line, a digital subscriber line either synchronous or asynchronous; an asymmetric digital subscriber line; an optical fiber backbone; a coaxial cable, etc.; and wireless link components such as line-of-sight or non-line-of- sight links which can include terrestrial air-interfaces or deep space links (e.g., satellite communication links for navigation). In an aspect, for universal mobile

telecommunication system-based networks, wireless backhaul link(s) 624 embodies luB interface.

[0086] It is noted that while exemplary wireless environment 600 is illustrated for macro cells and macro base stations, aspects, features and advantages of the disclosed subject matter can be implemented in micro cells, pico cells, femto cells, or the like, wherein base stations are embodied in home-based equipment related to access to a network (e.g., with one or more phased arrays or the like).

[0087] FIG. 7 illustrates one example of a wireless communication system 700 that could also implement the components and aspects of a phased array as described above. The wireless communication system 700 depicts one base station 710 and one access terminal 750 for sake of brevity. However, it is to be appreciated that system 700 can include more than one base station and/or more than one access terminal, wherein additional base stations and/or access terminals can be substantially similar or different from example base station 710 and access terminal 750 described below. In addition, it is to be appreciated that base station 710 and/or access terminal 750 can employ the systems and/or methods described herein to facilitate wireless

communication there between.

[0088] At base station 710, traffic data for a number of data streams is provided from a data source 71 2 to a transmit (TX) data processor 714. According to an example, each data stream can be transmitted over a respective antenna. TX data processor 714 formats, codes, and interleaves the traffic data stream based on a particular coding scheme selected for that data stream to provide coded data.

[0089] The coded data for each data stream can be multiplexed with pilot data using orthogonal frequency division multiplexing (OFDM) techniques. Additionally or alternatively, the pilot symbols can be frequency division multiplexed (FDM), time division multiplexed (TDM), or code division multiplexed (CDM). The pilot data is typically a known data pattern that is processed in a known manner and can be used at access terminal 750 to estimate channel response. The multiplexed pilot and coded data for each data stream can be modulated (e.g., symbol mapped) based on a particular modulation scheme (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM), etc.) selected for that data stream to provide modulation symbols. The data rate, coding, and modulation for each data stream can be determined by instructions performed or provided by processor 730.

[0090] The modulation symbols for the data streams can be provided to a TX MIMO processor 720, which can further process the modulation symbols (e.g., for OFDM). TX MIMO processor 720 then provides Ντ modulation symbol streams to Ντ transmitters (TMTR) 722a through 722t. In various embodiments, TX MIMO processor 720 applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.

[0091] Each transmitter 722a-t receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. Further, Ντ modulated signals from transmitters 722a through 722t are transmitted from N_T antennas 724a through 724t, respectively.

[0092] At access terminal 750, the transmitted modulated signals are received by N_R antennas 752a through 752r and the received signal from each antenna 752 is provided to a respective receiver (RCVR) 754a through 754r. Each receiver 754 conditions (e.g., filters, amplifies, and downconverts) a respective signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding "received" symbol stream.

[0093] An RX data processor 760 can receive and process the N_R received symbol streams from N_R receivers 754 based on a particular receiver processing technique to provide N_T "detected" symbol streams. RX data processor 760 can demodulate, deinterleave, and decode each detected symbol stream to recover the traffic data for the data stream. The processing by RX data processor 760 is complementary to that performed by TX Ml MO processor 720 and TX data processor 714 at base station 710.

[0094] A processor 770 can periodically determine which available technology to utilize as discussed above. Further, processor 770 can formulate a reverse link message comprising a matrix index portion and a rank value portion.

[0095] The reverse link message can comprise various types of information regarding the communication link and/or the received data stream. The reverse link message can be processed by a TX data processor 738, which also receives traffic data for a number of data streams from a data source 736, modulated by a modulator 780, conditioned by transmitters 754a through 754r, and transmitted back to base station 71 0.

[0096] At base station 710, the modulated signals from access terminal 750 are received by antennas 724, conditioned by receivers 722, demodulated by a

demodulator 740, and processed by a RX data processor 760 to extract the reverse link message transmitted by access terminal 750. Further, processor 730 can process the extracted message to determine which precoding matrix to use for determining the beamforming weights.

[0097] Processors 730 and 770 can direct (e.g., control, coordinate, manage, etc.) operation at base station 71 0 and access terminal 750, respectively. Respective processors 730 and 770 can be associated with memory 732 and 772 that store program codes and data. Processors 730 and 770 can also perform computations to derive frequency and impulse response estimates for the uplink and downlink, respectively.

[0098] Embodiments of the technology herein may be described as related to the third generation partnership project (3GPP) long term evolution (LTE) or LTE-advanced (LTE-A) standards. For example, terms or entities such as eNodeB (eNB), mobility management entity (MME), user equipment (UE), etc. may be used that may be viewed as LTE-related terms or entities. However, in other embodiments the technology may be used in or related to other wireless technologies such as the Institute of Electrical and Electronic Engineers (IEEE) 802.1 6 wireless technology (WiMax), IEEE 802.1 1 wireless technology (WiFi), various other wireless technologies such as global system for mobile communications (GSM), enhanced data rates for GSM evolution (EDGE), GSM EDGE radio access network (GERAN), universal mobile telecommunications system (UMTS), UMTS terrestrial radio access network (UTRAN), or other 2G, 3G, 4G, 5G, etc.

technologies either already developed or to be developed. In those embodiments, where LTE-related terms such as eNB, MME, UE, etc. are used, one or more entities or components may be used that may be considered to be equivalent or approximately equivalent to one or more of the LTE-based terms or entities.

[0099] As it employed in the subject specification, the term "processor" can refer to substantially any computing processing unit or device including, but not limited to including, single-core processors; single-processors with software multithread execution capability; multi-core processors; multi-core processors with software multithread execution capability; multi-core processors with hardware multithread technology;

parallel platforms; and parallel platforms with distributed shared memory. Additionally, a processor can refer to an integrated circuit, an application specific integrated circuit, a digital signal processor, a field programmable gate array, a programmable logic controller, a complex programmable logic device, a discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions and/or processes described herein. Processors can exploit nano-scale architectures such as, but not limited to, molecular and quantum-dot based transistors, switches and gates, in order to optimize space usage or enhance performance of mobile devices. A processor may also be implemented as a combination of computing processing units.

[00100] In the subject specification, terms such as "store," "data store," data storage," "database," and substantially any other information storage component relevant to operation and functionality of a component and/or process, refer to "memory

components," or entities embodied in a "memory," or components including the memory. It is noted that the memory components described herein can be either volatile memory or nonvolatile memory, or can include both volatile and nonvolatile memory.

[00101 ] Examples can include subject matter such as a method, means for performing acts or blocks of the method, at least one machine-readable medium including instructions that, when performed by a machine cause the machine to perform acts of the method or of an apparatus or system for concurrent communication using multiple communication technologies according to embodiments and examples described herein. [00102] Example 1 is a computer-readable medium comprising executable instructions that, in response to execution, cause a processor of an evolved NodeB (eNB) to perform operations in a wireless network, the operations comprising:

generating channel state information reference signals (CSI-RSs) within an orthogonal frequency division multiplexing (OFDM) symbol based on a larger subcarrier spacing than from a physical downlink shared channel or an interleaved frequency division multiple access (IFDMA) scheme; and generating a configuration of a CSI-RS transmission based on the larger subcarrier spacing or the IFDMA scheme.

[00103] Example 2 includes the subject matter of Example 1 , wherein the larger subcarrier spacing is larger than a 5G physical downlink shared channel (xPDSCH), and a value of the larger subcarrier spacing is pre-defined, configured by a higher signalling layer than a physical layer or configured via a downlink control information (DCI).

[00104] Example 3 includes the subject matter of any of Examples 1 -2, including or omitting any elements, wherein the operations further comprise: generating a symbol length of a CSI-RS of the CSI-RSs that is shorter than another symbol length of a xPDSCH, and applying different transmitting (Tx) beams to different CSI-RS groups.

[00105] Example 4 includes the subject matter of any of Examples 1 -3, including or omitting any elements, wherein the operations further comprise: generating a base sequence of a CSI-RS of the CSI-RSs according to a quadrature phase-shift keying (QPSK) signal that is determined by a cell identification (ID), a virtual cell ID, a beam reference signal (BRS) group ID, or a CSI-RS ID, and a subframe index or a slot index.

[00106] Example 5 includes the subject matter of any of Examples 1 -4, including or omitting any elements, wherein the operations further comprise: mapping different CSI- RS antenna ports (APs) to different subcarriers reserved for the CSI-RS transmission based on a cyclic shift value that is a function of an AP index.

[00107] Example 6 includes the subject matter of any of Examples 1 -5, including or omitting any elements, wherein the operations further comprise: generating the IFDMA scheme based on a Zadoff-Chu sequence; assigning different cyclic shifts of the CSI- RSs to different APs; and mapping the CSI-RSs in a fixed subcarrier interval with a middle subcarrier being skipped.

[00108] Example 7 includes the subject matter of any of Examples 1 -6, including or omitting any elements, wherein the operations further comprise: generating the OFDM symbol comprising the CSI-RSs mapped to a plurality of transmitting (Tx) beams; and generating a DCI comprising an indicator that indicates whether the CSI-RS

transmission, a beam refinement reference signal (BRRS) transmission, both the CSI- RS transmission and the BRRS transmission, or neither are within a sub-frame.

[00109] Example 8 is an apparatus configured to be employed within an evolved NodeB comprising: a baseband component configured to generate a plurality of channel state information reference signals (CSI-RSs) within a single orthogonal frequency division multiplexing (OFDM) symbol; and a radio frequency (RF) component, communicatively coupled to the baseband component, configured to generate a configuration of a CSI-RS transmission that indicates whether the CSI-RS transmission is based on a large-spacing OFDM symbol or an interleaved frequency division multiple access (IFDMA) scheme.

[00110] Example 9 includes the subject matter of Example 8, wherein the OFDM symbol comprises a plurality of cyclic prefix (CP)s corresponding in number to the plurality of CSI-RSs in the large-spacing OFDM symbol, or the OFDM symbol comprises a single CP corresponding to the plurality of CSI-RSs in the IFDMA scheme.

[00111 ] Example 10 includes the subject matter of any of Examples 8-9, including or omitting any elements, wherein the RF component comprises a transmit component configured to transmit the single OFDMA symbol according to IFDMA, wherein the OFDM symbol transmitted according to the IFDMA scheme, has a larger CP than CPs in the large-spacing OFDM symbol.

[00112] Example 1 1 includes the subject matter of any of Examples 8-1 1 , including or omitting any elements, wherein different transmission (Tx) beams are mapped to different CSI-RS symbols within the OFDM symbol, and the configuration comprises a downlink control information (DCI) indicator indicating whether the CSI-RS transmission, a beam refinement reference signal (BRRS) transmission, both the CSI-RS

transmission and the BRRS transmission, or neither are within a sub-frame.

[00113] Example 12 includes the subject matter of any of Examples 8-1 1 , including or omitting any elements, wherein a value of a CSI-RS subcarrier spacing for the large- spacing OFDM symbol is predefined, configured by higher layer signaling, or indicated by the DCI, and a CSI-RS symbol length is smaller than another symbol length of the a physical downlink shared channel (xPDSCH), and different Tx beams are applied to different CSI-RS symbols.

[00114] Example 13 includes the subject matter of any of Examples 8-1 2, including or omitting any elements further comprising: a mapping component configured to map the plurality of CSI-RSs to a plurality of antenna ports (APs) associated with different subcarriers based on different cyclic shifts having a cyclic shift value that is a function of an AP index.

[00115] Example 14 includes the subject matter of any of Examples 8-1 3, including or omitting any elements, wherein the mapping component is further configured to allocate a transmit Tx beam to a CSI-RS Group (CRG), and divide at least one CSI-RS of the plurality of CSI-RSs into a plurality of CRGs, and at least one CRG of the plurality of CRGs comprises at least two consecutive antenna ports (APs).

[00116] Example 15 includes the subject matter of any of Examples 8-14, including or omitting any elements, wherein the mapping component is further configured to map at least one CSI-RS of the plurality of CSI-RSs a first subcarrier, and set a second subcarrier to zero.

[00117] Example 16 includes the subject matter of any of Examples 8-1 5, including or omitting any elements, wherein the mapping component is further configured to map at least one CSI-RS of the plurality of CSI-RSs based on the IFDMA scheme to a number of subcarriers in the single OFDM symbol, set one or more remaining subcarrier to zero, generate time domain replica signals associated with the at least one CSI-RS of the plurality of CSI-RSs, and apply different Tx beams to the ^Λ'ί time domain replica signals.

[00118] Example 17 includes the subject matter of any of Examples 8-1 6, including or omitting any elements, wherein the RF component is further configured to multiplex at least one CSI-RS of the plurality of CSI-RSs for different APs in a frequency division multiplexing (FDM) manner or a code division multiplexing (CDM) manner.

[00119] Example 18 includes the subject matter of any of Examples 8-1 7, including or omitting any elements, wherein the RF component is further configured to generate the plurality of CSI-RSs based on a quadrature phase-shift keying (QPSK) signal with a CSI-RS sequence initialized by a cell identifier (ID), a virtual cell ID, a Beam Reference Signal (BRS) group ID, or a CSI-RS ID, with a subframe index or a slot/frame index, and generate the CSI-RS sequence for at least one CSI-RS of the plurality of CSI-RSs based on a Zadoff-Chu (ZC) sequence, wherein a root index of the ZC sequence is a function of the cell ID, the virtual cell ID, the BRS group ID, and/or the CSI-RS ID or subframe/slot/frame index.

[00120] Example 19 is an apparatus configured to be employed within a user equipment (UE), comprising: a radio frequency (RF) component configured to process a plurality of channel state information reference signals (CSI-RSs) within a single orthogonal frequency division multiplexing (OFDM) symbol, wherein the OFDM symbol is configured as a large-spacing OFDM symbol that includes a cyclic prefix (CP) corresponding to a CSI-RS of the plurality of CSI-RSs, or the OFDM symbol is configured according to an interleaved frequency division multiple access (IFDMA) scheme and comprises a single CP corresponding to the plurality of CSI-RSs; and a baseband component configured to process a configuration of a CSI-RS transmission that is associated with the plurality of CSI-RSs.

[00121 ] Example 20 includes the subject matter of any of Examples 19, wherein the configuration includes a downlink control information (DCI) indicator that triggers a measurement of at least one of a CSI-RS signal or a Beam Refinement Reference Signal (BRRS) transmission in a subframe.

[00122] Example 21 includes the subject matter of any of Examples 19-20, including or omitting any elements, further comprising: a mapping component configured to process different transmit beams applied to different CSI-RS Groups (CRGs), wherein the different transmit beams are mapped to different CSI-RS symbols/subframes of the OFDM symbol.

[00123] Example 22 includes the subject matter of any of Examples 19-21 , including or omitting any elements, wherein for the IFDMA scheme, at least one CSI-RS of the plurality of CSI-RSs is mapped to every number of ^Nt- subcarriers in one OFDM symbol, remaining subcarriers are set to zero, and ^N<^, time domain replica signals are processed for the at least one CSI-RS, wherein different Tx beams are applied to the ^Λ'ί time domain replica signals.

[00124] Example 23 includes the subject matter of any of Examples 19-22, including or omitting any elements, wherein the RF component is further configured to process the plurality of CSI-RSs based on a quadrature phase-shift keying (QPSK) signal with a scramble sequence of at least one CSI-RS that is initialized by a cell identifier (ID), a virtual cell ID, a Beam Reference Signal (BRS) group ID, or a CSI-RS ID with subframe index or a slot/frame index.

[00125] Example 24 includes the subject matter of any of Examples 19-23, including or omitting any elements, wherein the RF component is further configured to process the scramble sequence of at least one CSI-RS based on a Zadoff-Chu (ZC) sequence, wherein a root index of the ZC sequence is a function of at least one of the cell ID, the virtual cell ID, the BRS group ID, the CSI-RS ID or a subframe/slot/frame index. [00126] Example 25 includes the subject matter of any of Examples 19-24, including or omitting any elements, wherein RF component is further configured to process the plurality of CSI-RSs based on the configuration according to a fixed subcarrier interval with a middle subcarrier being skipped.

[00127] Example 26 is an apparatus configured to be employed within an Evolved NodeB (eNB), comprising: means for processing configured to: generate channel state information reference signals (CSI-RSs) within an orthogonal frequency division multiplexing (OFDM) symbol based on a larger subcarrier spacing than from a physical downlink shared channel or an interleaved frequency division multiple access (IFDMA) scheme; and generate a configuration of a CSI-RS transmission based on the larger subcarrier spacing or the IFDMA scheme.

[00128] Example 27 includes the subject matter of Example 26, wherein the larger subcarrier spacing is larger than a 5G physical downlink shared channel (xPDSCH), and a value of the larger subcarrier spacing is pre-defined, configured by a higher signalling layer than a physical layer or configured via a downlink control information (DCI).

[00129] Example 28 includes the subject matter of any of Examples 26-27, including or omitting any elements, wherein the means for processing is further configured to generate a symbol length of a CSI-RS of the CSI-RSs that is shorter than another symbol length of a xPDSCH, and applying different transmitting (Tx) beams to different CSI-RS groups.

[00130] Example 29 includes the subject matter of any of Examples 26-28, including or omitting any elements, wherein the means for processing is further configured to generate a base sequence of a CSI-RS of the CSI-RSs according to a quadrature phase-shift keying (QPSK) signal that is determined by a cell identification (ID), a virtual cell ID, a beam reference signal (BRS) group ID, or a CSI-RS ID, and a subframe index or a slot index.

[00131 ] Example 30 includes the subject matter of any of Examples 26-29, including or omitting any elements, further comprising: means for mapping different CSI-RS antenna ports (APs) to different subcarriers reserved for the CSI-RS transmission based on a cyclic shift value that is a function of an AP index.

[00132] Example 31 includes the subject matter of any of Examples 26-30, including or omitting any elements, further comprising: means for generating the IFDMA scheme based on a Zadoff-Chu sequence; means for assigning different cyclic shifts of the CSI- RSs to different APs; and means for mapping the CSI-RSs in a fixed subcarrier interval with a middle subcarrier being skipped.

[00133] Example 32 includes the subject matter of any of Examples 26-31 , including or omitting any elements, wherein the means for processing is further configured to: generate the OFDM symbol comprising the CSI-RSs mapped to a plurality of transmitting (Tx) beams; and generate a DCI comprising an indicator that indicates whether the CSI-RS transmission, a beam refinement reference signal (BRRS) transmission, both the CSI-RS transmission and the BRRS transmission, or neither are within a sub-frame.

[00134] Example 33 is an apparatus configured to be employed within a user equipment (UE), comprising: means for processing configured to: process a plurality of channel state information reference signals (CSI-RSs) within a single orthogonal frequency division multiplexing (OFDM) symbol, wherein the OFDM symbol is configured as a large-spacing OFDM symbol that includes a cyclic prefix (CP) corresponding to a CSI-RS of the plurality of CSI-RSs, or the OFDM symbol is configured according to an interleaved frequency division multiple access (IFDMA) scheme and comprises a single CP corresponding to the plurality of CSI-RSs; and process a configuration of a CSI-RS transmission that is associated with the plurality of CSI-RSs.

[00135] Example 34 is an apparatus configured to be employed within an evolved NodeB comprising: a processor configured to: generate a plurality of channel state information reference signals (CSI-RSs) within a single orthogonal frequency division multiplexing (OFDM) symbol; and generate a configuration of a CSI-RS transmission that indicates whether the CSI-RS transmission is based on a large-spacing OFDM symbol or an interleaved frequency division multiple access (IFDMA) scheme.

[00136] Example 35 is an apparatus configured to be employed within a user equipment (UE), comprising: a processor configured to: process a plurality of channel state information reference signals (CSI-RSs) within a single orthogonal frequency division multiplexing (OFDM) symbol, wherein the OFDM symbol is configured as a large-spacing OFDM symbol that includes a cyclic prefix (CP) corresponding to a CSI- RS of the plurality of CSI-RSs, or the OFDM symbol is configured according to an interleaved frequency division multiple access (IFDMA) scheme and comprises a single CP corresponding to the plurality of CSI-RSs; and process a configuration of a CSI-RS transmission that is associated with the plurality of CSI-RSs. [00137] It is to be understood that aspects described herein can be implemented by hardware, software, firmware, or any combination thereof. When implemented in software, functions can be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media or a computer readable storage device can be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD- ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or other tangible and/or non-transitory medium, that can be used to carry or store desired information or executable instructions. Also, any connection is properly termed a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers.

Combinations of the above should also be included within the scope of computer- readable media.

[00138] Various illustrative logics, logical blocks, modules, and circuits described in connection with aspects disclosed herein can be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other

programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform functions described herein. A general-purpose processor can be a microprocessor, but, in the alternative, processor can be any conventional processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. Additionally, at least one processor can comprise one or more modules operable to perform one or more of the s and/or actions described herein.

[00139] For a software implementation, techniques described herein can be implemented with modules (e.g., procedures, functions, and so on) that perform functions described herein. Software codes can be stored in memory units and executed by processors. Memory unit can be implemented within processor or external to processor, in which case memory unit can be communicatively coupled to processor through various means as is known in the art. Further, at least one processor can include one or more modules operable to perform functions described herein.

[00140] Techniques described herein can be used for various wireless communication systems such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other systems. The terms "system" and "network" are often used interchangeably. A CDMA system can implement a radio technology such as Universal Terrestrial Radio Access (UTRA), CDMA1800, etc. UTRA includes Wideband-CDMA (W-CDMA) and other variants of CDMA. Further, CDMA1800 covers IS-1800, IS-95 and IS-856 standards. A TDMA system can implement a radio technology such as Global System for Mobile

Communications (GSM). An OFDMA system can implement a radio technology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.1 1 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.18, Flash-OFDML , etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). 3GPP Long Term Evolution (LTE) is a release of UMTS that uses E-UTRA, which employs OFDMA on downlink and SC-FDMA on uplink. UTRA, E-UTRA, UMTS, LTE and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). Additionally, CDMA1 800 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). Further, such wireless communication systems can additionally include peer-to-peer (e.g., mobile-to-mobile) ad hoc network systems often using unpaired unlicensed spectrums, 802. xx wireless LAN, BLUETOOTH and any other short- or long- range, wireless communication techniques.

[00141 ] Single carrier frequency division multiple access (SC-FDMA), which utilizes single carrier modulation and frequency domain equalization is a technique that can be utilized with the disclosed aspects. SC-FDMA has similar performance and essentially a similar overall complexity as those of OFDMA system. SC-FDMA signal has lower peak-to-average power ratio (PAPR) because of its inherent single carrier structure. SC-FDMA can be utilized in uplink communications where lower PAPR can benefit a mobile terminal in terms of transmit power efficiency.

[00142] Moreover, various aspects or features described herein can be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques. The term "article of manufacture" as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier, or media. For example, computer-readable media can include but are not limited to magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips, etc.), optical disks (e.g., compact disk (CD), digital versatile disk (DVD), etc.), smart cards, and flash memory devices (e.g., EPROM, card, stick, key drive, etc.). Additionally, various storage media described herein can represent one or more devices and/or other machine-readable media for storing information. The term "machine-readable medium" can include, without being limited to, wireless channels and various other media capable of storing, containing, and/or carrying instruction(s) and/or data. Additionally, a computer program product can include a computer readable medium having one or more instructions or codes operable to cause a computer to perform functions described herein.

[00143] Communications media embody computer-readable instructions, data structures, program modules or other structured or unstructured data in a data signal such as a modulated data signal, e.g., a carrier wave or other transport mechanism, and includes any information delivery or transport media. The term "modulated data signal" or signals refers to a signal that has one or more of its characteristics set or changed in such a manner as to encode information in one or more signals. By way of example, and not limitation, communication media include wired media, such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared and other wireless media.

[00144] Further, the actions of a method or algorithm described in connection with aspects disclosed herein can be embodied directly in hardware, in a software module executed by a processor, or a combination thereof. A software module can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium can be coupled to processor, such that processor can read information from, and write information to, storage medium. In the alternative, storage medium can be integral to processor. Further, in some aspects, processor and storage medium can reside in an ASIC. Additionally, ASIC can reside in a user terminal. In the alternative, processor and storage medium can reside as discrete components in a user terminal. Additionally, in some aspects, the s and/or actions of a method or algorithm can reside as one or any combination or set of codes and/or instructions on a machine-readable medium and/or computer readable medium, which can be incorporated into a computer program product.

[00145] The above description of illustrated embodiments of the subject disclosure, including what is described in the Abstract, is not intended to be exhaustive or to limit the disclosed embodiments to the precise forms disclosed. While specific embodiments and examples are described herein for illustrative purposes, various modifications are possible that are considered within the scope of such embodiments and examples, as those skilled in the relevant art can recognize.

[00146] In this regard, while the disclosed subject matter has been described in connection with various embodiments and corresponding Figures, where applicable, it is to be understood that other similar embodiments can be used or modifications and additions can be made to the described embodiments for performing the same, similar, alternative, or substitute function of the disclosed subject matter without deviating therefrom. Therefore, the disclosed subject matter should not be limited to any single embodiment described herein, but rather should be construed in breadth and scope in accordance with the appended claims below.

[00147] In particular regard to the various functions performed by the above described components (assemblies, devices, circuits, systems, etc.), the terms (including a reference to a "means") used to describe such components are intended to correspond, unless otherwise indicated, to any component or structure which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary implementations of the disclosure. In addition, while a particular feature may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.

Claims

CLAIMS What is claimed is:

1 . A computer-readable medium comprising executable instructions that, in response to execution, cause a processor of an evolved NodeB (eNB) to perform operations in a wireless network, the operations comprising:

generating channel state information reference signals (CSI-RSs) within an orthogonal frequency division multiplexing (OFDM) symbol based on a larger subcarrier spacing than from a physical downlink shared channel or an interleaved frequency division multiple access (IFDMA) scheme; and

generating a configuration of a CSI-RS transmission based on the larger subcarrier spacing or the IFDMA scheme.

2. The computer-readable medium of claim 1 , wherein the larger subcarrier spacing is larger than a 5G physical downlink shared channel (xPDSCH), and a value of the larger subcarrier spacing is pre-defined, configured by a higher signalling layer than a physical layer or configured via a downlink control information (DCI).

3. The computer-readable medium of any of claims 1 -2, wherein the operations further comprise:

generating a symbol length of a CSI-RS of the CSI-RSs that is shorter than another symbol length of a xPDSCH, and applying different transmitting (Tx) beams to different CSI-RS groups.

4. The computer-readable medium of any of claims 1 -3, wherein the operations further comprise:

generating a base sequence of a CSI-RS of the CSI-RSs according to a quadrature phase-shift keying (QPSK) signal that is determined by a cell identification (ID), a virtual cell ID, a beam reference signal (BRS) group ID, or a CSI-RS ID, and a subframe index or a slot index.

5. The computer-readable medium of any of claims 1 -4, wherein the operations further comprise: mapping different CSI-RS antenna ports (APs) to different subcarriers reserved for the CSI-RS transmission based on a cyclic shift value that is a function of an AP index.

6. The computer-readable medium of any of claims 1 -5, wherein the operations further comprise:

generating the IFDMA scheme based on a Zadoff-Chu sequence;

assigning different cyclic shifts of the CSI-RSs to different APs; and

mapping the CSI-RSs in a fixed subcarrier interval with a middle subcarrier being skipped.

7. The computer-readable medium of any of claims 1 -6, wherein the operations further comprise:

generating the OFDM symbol comprising the CSI-RSs mapped to a plurality of transmitting (Tx) beams; and

generating a DCI comprising an indicator that indicates whether the CSI-RS transmission, a beam refinement reference signal (BRRS) transmission, both the CSI- RS transmission and the BRRS transmission, or neither are within a sub-frame.

8. An apparatus configured to be employed within an evolved NodeB comprising: a baseband component configured to generate a plurality of channel state information reference signals (CSI-RSs) within a single orthogonal frequency division multiplexing (OFDM) symbol; and

a radio frequency (RF) component, communicatively coupled to the baseband component, configured to generate a configuration of a CSI-RS transmission that indicates whether the CSI-RS transmission is based on a large-spacing OFDM symbol or an interleaved frequency division multiple access (IFDMA) scheme.

9. The apparatus of claim 8, wherein the OFDM symbol comprises a plurality of cyclic prefix (CP)s corresponding in number to the plurality of CSI-RSs in the large- spacing OFDM symbol, or the OFDM symbol comprises a single CP corresponding to the plurality of CSI-RSs in the IFDMA scheme.

10. The apparatus of any of claims 8-9, wherein the RF component comprises a transmit component configured to transmit the single OFDMA symbol according to IFDMA, wherein the OFDM symbol transmitted according to the IFDMA scheme, has a larger CP than CPs in the large-spacing OFDM symbol.

1 1 . The apparatus of any of claims 8-10, wherein different transmission (Tx) beams are mapped to different CSI-RS symbols within the OFDM symbol, and the

configuration comprises a downlink control information (DCI) indicator indicating whether the CSI-RS transmission, a beam refinement reference signal (BRRS) transmission, both the CSI-RS transmission and the BRRS transmission, or neither are within a sub-frame.

12. The apparatus of any of claims 8-1 1 , wherein a value of a CSI-RS subcarrier spacing for the large-spacing OFDM symbol is predefined, configured by higher layer signaling, or indicated by the DCI, and a CSI-RS symbol length is smaller than another symbol length of the a physical downlink shared channel (xPDSCH), and different Tx beams are applied to different CSI-RS symbols.

13. The apparatus of any of claims 8-12, further comprising:

a mapping component configured to map the plurality of CSI-RSs to a plurality of antenna ports (APs) associated with different subcarriers based on different cyclic shifts having a cyclic shift value that is a function of an AP index.

14. The apparatus of claim 13, wherein the mapping component is further configured to allocate a transmit Tx beam to a CSI-RS Group (CRG), and divide at least one CSI- RS of the plurality of CSI-RSs into a plurality of CRGs, and at least one CRG of the plurality of CRGs comprises at least two consecutive antenna ports (APs).

15. The apparatus of claim 13, wherein the mapping component is further configured to map at least one CSI-RS of the plurality of CSI-RSs a first subcarrier, and set a second subcarrier to zero.

16. The apparatus of claim 13, wherein the mapping component is further configured to map at least one CSI-RS of the plurality of CSI-RSs based on the IFDMA scheme to a number of ^iVJ subcarriers in the single OFDM symbol, set one or more remaining subcarrier to zero, generate ^Ni time domain replica signals associated with the at least one CSI-RS of the plurality of CSI-RSs, and apply different Tx beams to the ^Λ'ί time domain replica signals.

17. The apparatus of any of claims 8-16, wherein the RF component is further configured to multiplex at least one CSI-RS of the plurality of CSI-RSs for different APs in a frequency division multiplexing (FDM) manner or a code division multiplexing (CDM) manner.

18. The apparatus of any of claims 8-17, wherein the RF component is further configured to generate the plurality of CSI-RSs based on a quadrature phase-shift keying (QPSK) signal with a CSI-RS sequence initialized by a cell identifier (ID), a virtual cell ID, a Beam Reference Signal (BRS) group ID, or a CSI-RS ID, with a subframe index or a slot/frame index, and generate the CSI-RS sequence for at least one CSI-RS of the plurality of CSI-RSs based on a Zadoff-Chu (ZC) sequence, wherein a root index of the ZC sequence is a function of the cell ID, the virtual cell ID, the BRS group ID, and/or the CSI-RS ID or subframe/slot/frame index.

19. An apparatus configured to be employed within a user equipment (UE), comprising:

a radio frequency (RF) component configured to process a plurality of channel state information reference signals (CSI-RSs) within a single orthogonal frequency division multiplexing (OFDM) symbol, wherein the OFDM symbol is configured as a large-spacing OFDM symbol that includes a cyclic prefix (CP) corresponding to a CSI- RS of the plurality of CSI-RSs, or the OFDM symbol is configured according to an interleaved frequency division multiple access (IFDMA) scheme and comprises a single CP corresponding to the plurality of CSI-RSs; and

a baseband component configured to process a configuration of a CSI-RS transmission that is associated with the plurality of CSI-RSs.

20. The apparatus of claim 19, wherein the configuration includes a downlink control information (DCI) indicator that triggers a measurement of at least one of a CSI-RS signal or a Beam Refinement Reference Signal (BRRS) transmission in a subframe.

21 . The apparatus of the any of claims 19-20, further comprising:

a mapping component configured to process different transmit beams applied to different CSI-RS Groups (CRGs), wherein the different transmit beams are mapped to different CSI-RS symbols/subframes of the OFDM symbol.

22. The apparatus of any of claims 19-21 , wherein for the IFDMA scheme, at least one CSI-RS of the plurality of CSI-RSs is mapped to every number of ^Nt subcarriers in one OFDM symbol, remaining subcarriers are set to zero, and ^Λ* time domain replica signals are processed for the at least one CSI-RS, wherein different Tx beams are applied to the ^ΛΓ* time domain replica signals.

23. The apparatus of any of claims 19-22, wherein the RF component is further configured to process the plurality of CSI-RSs based on a quadrature phase-shift keying (QPSK) signal with a scramble sequence of at least one CSI-RS that is initialized by a cell identifier (ID), a virtual cell ID, a Beam Reference Signal (BRS) group ID, or a CSI- RS ID with subframe index or a slot/frame index.

24. The apparatus of claim 23, wherein the RF component is further configured to process the scramble sequence of at least one CSI-RS based on a Zadoff-Chu (ZC) sequence, wherein a root index of the ZC sequence is a function of at least one of the cell ID, the virtual cell ID, the BRS group ID, the CSI-RS ID or a subframe/slot/frame index.

25. The apparatus of any of claims 19-24, wherein RF component is further configured to process the plurality of CSI-RSs based on the configuration according to a fixed subcarrier interval with a middle subcarrier being skipped.