Patent Description:
Research and development continue to advance the UMTS technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.

<CIT> relates to a base station including a plurality of first REs corresponding to at least two of a second OFDM symbol, a third OFDM symbol, and a fourth OFDM symbol of a first time slot, in a first CSI-RS resource pool configured in a first subframe including the first time slot and a second time slot subsequent to the first time slot.

There still exists a need for improved utilization of CSI-RS.

A solution is provided according to the subject-matter of the independent claims.

The scope of protection is defined by the appended set of claims.

In one aspect of the disclosure, a method of wireless communication includes determining a channel state information (CSI) reference signal (CSI-RS) configuration by a base station with a CSI-RS resource having greater than or equal to <NUM>-ports, identifying a group of CSI-RS configurations into which one or more CSI-RS ports of the CSI-RS resource will be mapped, applying a permutation to each port on the same polarization according to the configuration, and sequentially mapping the permutated CSI-RS ports to each component configuration.

In an additional aspect of the disclosure, a method of wireless communication includes determining, by a base station, a CSI-RS resource having greater than a threshold number of antenna ports and a code divisional multiplex (CDM) length of at least eight, identifying a group of four CSI-RS configurations into which one or more CSI-RS ports of the CSI-RS resource will be mapped into, mapping each of the one or more ports of the CSI-RS resource into each configuration of the group of four CSI-RS configurations, allocating the one or more mapped ports to a set of resource elements (REs) within the corresponding configuration of the group of four CSI-RS configurations, and selecting one CSI-RS configuration of the group of four CSI-RS configurations for CSI-RS transmission based on available CSI-RS resources and subframe type.

In an additional aspect of the disclosure, an apparatus configured for wireless communication includes means for determining a CSI-RS configuration by a base station with a CSI-RS resource having greater than or equal to <NUM>-ports, means for identifying a group of CSI-RS configurations into which one or more CSI-RS ports of the CSI-RS resource will be mapped, means for applying a permutation to each port on the same polarization according to the configuration, and means for sequentially mapping the permutated CSI-RS ports to each component configuration.

In an additional aspect of the disclosure, an apparatus configured for wireless communication includes means for determining, by a base station, a CSI-RS resource having greater than a threshold number of antenna ports and a CDM length of at least eight, means for identifying a group of four CSI-RS configurations into which one or more CSI-RS ports of the CSI-RS resource will be mapped, means for mapping each of the one or more ports of the CSI-RS resource into each configuration of the group of four CSI-RS configurations, means for allocating the one or more mapped ports to a set of REs within the corresponding configuration of the group of four CSI-RS configurations, and means for selecting one CSI-RS configuration of the group of four CSI-RS configurations for CSI-RS transmission based on available CSI-RS resources and subframe type.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon. When executed by a computer, the program code causes the computer to control or implement the functionality based on the instructions of the program code. The program code further includes code to determine a CSI-RS configuration by a base station with a CSI-RS resource having greater than or equal to <NUM>-ports, code to identify a group of CSI-RS configurations into which one or more CSI-RS ports of the CSI-RS resource will be mapped, code to apply a permutation to each port on the same polarization according to the configuration, and code to sequentially map the permutated CSI-RS ports to each component configuration.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon. When executed by a computer, the program code causes the computer to control or implement the functionality based on the instructions of the program code. The program code further includes code to determine, by a base station, a CSI-RS resource having greater than a threshold number of antenna ports and a CDM length of at least eight, code to identify a group of four CSI-RS configurations into which one or more CSI-RS ports of the CSI-RS resource will be mapped, code to map each of the one or more ports of the CSI-RS resource into each configuration of the group of four CSI-RS configurations, code to allocate the one or more mapped ports to a set of REs within the corresponding configuration of the group of four CSI-RS configurations, and code to select one CSI-RS configuration of the group of four CSI-RS configurations for CSI-RS transmission based on available CSI-RS resources and subframe type.

In an additional aspect of the disclosure, an apparatus configured for wireless communication is disclosed. The apparatus includes at least one processor, and a memory coupled to the processor. The processor is configured to determine a CSI-RS configuration by a base station with a CSI-RS resource having greater than or equal to <NUM>-ports, to identify a group of CSI-RS configurations into which one or more CSI-RS ports of the CSI-RS resource will be mapped, to apply a permutation to each port on the same polarization according to the configuration, and to sequentially map the permutated CSI-RS ports to each component configuration.

In an additional aspect of the disclosure, an apparatus configured for wireless communication is disclosed. The apparatus includes at least one processor, and a memory coupled to the processor. The processor is configured to determine, by a base station, a CSI-RS resource having greater than a threshold number of antenna ports and a CDM length of at least eight, to identify a group of four CSI-RS configurations into which one or more CSI-RS ports of the CSI-RS resource will be mapped, to map each of the one or more ports of the CSI-RS resource into each configuration of the group of four CSI-RS configurations, to allocate the one or more mapped ports to a set of REs within the corresponding configuration of the group of four CSI-RS configurations, and to select one CSI-RS configuration of the group of four CSI-RS configurations for CSI-RS transmission based on available CSI-RS resources and subframe type.

In an additional aspect of the disclosure, a method of wireless communication includes determining, by a base station, a CSI-RS resource having greater than or equal to a threshold number of antenna ports and a CDM length of at least eight, identifying a group of four CSI-RS configurations into which one or more CSI-RS ports of the CSI-RS resource will be mapped into, mapping each of the one or more ports of the CSI-RS resource into each configuration of the group of four CSI-RS configurations, allocating the one or more mapped ports to a set of REs within the corresponding configuration of the group of four CSI-RS configurations, and transmitting the one or more CSI-RS ports from the determined set of resource elements within the group of four CSI-RS configurations.

In an additional aspect of the disclosure, an apparatus configured for wireless communication includes means for determining, by a base station, a CSI-RS resource having greater than or equal to a threshold number of antenna ports and a CDM length of at least eight, means for identifying a group of four CSI-RS configurations into which one or more CSI-RS ports of the CSI-RS resource will be mapped into, means for mapping each of the one or more ports of the CSI-RS resource into each configuration of the group of four CSI-RS configurations, means for allocating the one or more mapped ports to a set of REs within the corresponding configuration of the group of four CSI-RS configurations, and means for transmitting the one or more CSI-RS ports from the determined set of resource elements within the group of four CSI-RS configurations.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon. When executed by a computer, the program code causes the computer to determine, by a base station, a CSI-RS resource having greater than or equal to a threshold number of antenna ports and a CDM length of at least eight, to identify a group of four CSI-RS configurations into which one or more CSI-RS ports of the CSI-RS resource will be mapped into, to map each of the one or more ports of the CSI-RS resource into each configuration of the group of four CSI-RS configurations, to allocate the one or more mapped ports to a set of REs within the corresponding configuration of the group of four CSI-RS configurations, and to transmit the one or more CSI-RS ports from the determined set of resource elements within the group of four CSI-RS configurations.

In an additional aspect of the disclosure, an apparatus configured for wireless communication is disclosed. The apparatus includes at least one processor, and a memory coupled to the processor. The processor is configured to determine, by a base station, a CSI-RS resource having greater than or equal to a threshold number of antenna ports and a CDM length of at least eight, to identify a group of four CSI-RS configurations into which one or more CSI-RS ports of the CSI-RS resource will be mapped into, to map each of the one or more ports of the CSI-RS resource into each configuration of the group of four CSI-RS configurations, to allocate the one or more mapped ports to a set of REs within the corresponding configuration of the group of four CSI-RS configurations, and to transmit the one or more CSI-RS ports from the determined set of resource elements within the group of four CSI-RS configurations.

This disclosure relates generally to providing or participating in authorized shared access between two or more wireless communications systems, also referred to as wireless communications networks. In various aspects, the techniques and apparatus may be used for wireless communication networks such as code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single-carrier FDMA (SC-FDMA) networks, LTE networks, GSM networks, as well as other communications networks. As described herein, the terms "networks" and "systems" may be used interchangeably.

A CDMA network may implement a radio technology such as universal terrestrial radio access (UTRA), cdma2000, and the like.

3GPP defines standards for the GSM EDGE (enhanced data rates for GSM evolution) radio access network (RAN), also denoted as GERAN. GERAN is the radio component of GSM/EDGE, together with the network that joins the base stations (for example, the Ater and Abis interfaces) and the base station controllers (A interfaces, etc.). The radio access network represents a component of a GSM network, through which phone calls and packet data are routed from and to the public switched telephone network (PSTN) and Internet to and from subscriber handsets, also known as user terminals or user equipments (UEs). A mobile phone operator's network may comprise one or more GERANs, which may be coupled with UTRANs in the case of a UMTS/GSM network. An operator network may also include one or more LTE networks, and/or one or more other networks. The various different network types may use different radio access technologies (RATs) and radio access networks (RANs).

UTRA, E-UTRA, and GSM are part of universal mobile telecommunication system (UMTS). 3GPP long term evolution (LTE) is a 3GPP project aimed at improving the universal mobile telecommunications system (UMTS) mobile phone standard. For clarity, certain aspects of the apparatus and techniques may be described below for LTE implementations or in an LTE-centric way, and LTE terminology may be used as illustrative examples in portions of the description below; however, the description is not intended to be limited to LTE applications. Indeed, the present disclosure is concerned with shared access to wireless spectrum between networks using different radio access technologies or radio air interfaces.

A new carrier type based on LTE/LTE-A including in unlicensed spectrum has also been suggested that can be compatible with carrier-grade WiFi, making LTE/LTE-A with unlicensed spectrum an alternative to WiFi. LTE/LTE-A, when operating in unlicensed spectrum, may leverage LTE concepts and may introduce some modifications to physical layer (PHY) and media access control (MAC) aspects of the network or network devices to provide efficient operation in the unlicensed spectrum and meet regulatory requirements. The unlicensed spectrum used may range from as low as several hundred Megahertz (MHz) to as high as tens of Gigahertz (GHz), for example. In operation, such LTE/LTE-A networks may operate with any combination of licensed or unlicensed spectrum depending on loading and availability. Accordingly, it may be apparent to one of skill in the art that the systems, apparatus and methods described herein may be applied to other communications systems and applications.

System designs may support various time-frequency reference signals for the downlink and uplink to facilitate beamforming and other functions. A reference signal is a signal generated based on known data and may also be referred to as a pilot, preamble, training signal, sounding signal, and the like. A reference signal may be used by a receiver for various purposes such as channel estimation, coherent demodulation, channel quality measurement, signal strength measurement, and the like. MIMO systems using multiple antennas generally provide for coordination of sending of reference signals between antennas; however, LTE systems do not in general provide for coordination of sending of reference signals from multiple base stations or eNBs.

In some implementations, a system may utilize time division duplexing (TDD). For TDD, the downlink and uplink share the same frequency spectrum or channel, and downlink and uplink transmissions are sent on the same frequency spectrum. The downlink channel response may thus be correlated with the uplink channel response. Reciprocity may allow a downlink channel to be estimated based on transmissions sent via the uplink. These uplink transmissions may be reference signals or uplink control channels (which may be used as reference symbols after demodulation). The uplink transmissions may allow for estimation of a space-selective channel via multiple antennas.

In LTE implementations, orthogonal frequency division multiplexing (OFDM) is used for the downlink - that is, from a base station, access point or eNodeB (eNB) to a user terminal or UE. Use of OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for very wide carriers with high peak rates, and is a well-established technology. For example, OFDM is used in standards such as IEEE <NUM>. 11a/g, <NUM>, High Performance Radio LAN-<NUM> (HIPERLAN-<NUM>, wherein LAN stands for Local Area Network) standardized by the European Telecommunications Standards Institute (ETSI), Digital Video Broadcasting (DVB) published by the Joint Technical Committee of ETSI, and other standards.

Time frequency physical resource blocks (also denoted here in as resource blocks or "RBs" for brevity) may be defined in OFDM systems as groups of transport carriers (e.g. sub-carriers) or intervals that are assigned to transport data. The RBs are defined over a time and frequency period. Resource blocks are comprised of time-frequency resource elements (also denoted here in as resource elements or "REs" for brevity), which may be defined by indices of time and frequency in a slot. Additional details of LTE RBs and REs are described in the 3GPP specifications, such as, for example, 3GPP TS <NUM>.

UMTS LTE supports scalable carrier bandwidths from <NUM> down to <NUM>. In LTE, an RB is defined as <NUM> sub-carriers when the subcarrier bandwidth is <NUM>, or <NUM> sub-carriers when the sub-carrier bandwidth is <NUM>. In an exemplary implementation, in the time domain there is a defined radio frame that is <NUM> long and consists of <NUM> subframes of <NUM> millisecond (ms) each. Every subframe consists of <NUM> slots, where each slot is <NUM>. The subcarrier spacing in the frequency domain in this case is <NUM>. Twelve of these subcarriers together (per slot) constitute an RB, so in this implementation one resource block is <NUM>. Six Resource blocks fit in a carrier of <NUM> and <NUM> resource blocks fit in a carrier of <NUM>.

<FIG> shows a wireless network <NUM> for communication, which may be an LTE-A network. The wireless network <NUM> includes a number of evolved node Bs (eNBs) <NUM> and other network entities. An eNB may be a station that communicates with the UEs and may also be referred to as a base station, a node B, an access point, and the like. Each eNB <NUM> may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to this particular geographic coverage area of an eNB and/or an eNB subsystem serving the coverage area, depending on the context in which the term is used.

An eNB may provide communication coverage for a macro cell or a small cell, such as a pico cell or a femto cell, and/or other types of cell. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB or a home eNB. In the example shown in <FIG>, the eNBs 105a, 105b and 105c are macro eNBs for the macro cells 110a, 110b and 110c, respectively. The eNBs 105x, 105y, and 105z are small cell eNBs, which may include pico or femto eNBs that provide service to small cells 110x, 110y, and 110z, respectively. An eNB may support one or multiple (e.g., two, three, four, and the like) cells.

For synchronous operation, the eNBs may have similar frame timing, and transmissions from different eNBs may be approximately aligned in time. For asynchronous operation, the eNBs may have different frame timing, and transmissions from different eNBs may not be aligned in time.

The UEs <NUM> are dispersed throughout the wireless network <NUM>, and each UE may be stationary or mobile. A UE may also be referred to as a terminal, a mobile station, a subscriber unit, a station, or the like. A UE may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, or the like. A UE may be able to communicate with macro eNBs, pico eNBs, femto eNBs, relays, and the like. In <FIG>, a lightning bolt (e.g., communication links <NUM>) indicates wireless transmissions between a UE and a serving eNB, which is an eNB designated to serve the UE on the downlink and/or uplink, or desired transmission between eNBs. Wired backhaul communication <NUM> indicate wired backhaul communications that may occur between eNBs.

LTE/-A utilizes orthogonal frequency division multiplexing (OFDM) on the downlink and single-carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM partition the system bandwidth into multiple (X) orthogonal subcarriers, which are also commonly referred to as tones, bins, or the like. Each subcarrier may be modulated with data. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (X) may be dependent on the system bandwidth. For example, X may be equal to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> for a corresponding system bandwidth of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> megahertz (MHz), respectively. The system bandwidth may also be partitioned into sub-bands. For example, a sub-band may cover <NUM>, and there may be <NUM>, <NUM>, <NUM>, <NUM> or <NUM> sub-bands for a corresponding system bandwidth of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>, respectively.

<FIG> shows a block diagram of a design of a base station/eNB <NUM> and a UE <NUM>, which may be one of the base stations/eNBs and one of the UEs in <FIG>. For a restricted association scenario, the eNB <NUM> may be the small cell eNB 105z in <FIG>, and the UE <NUM> may be the UE 115z, which in order to access small cell eNB 105z, would be included in a list of accessible UEs for small cell eNB 105z. The eNB <NUM> may also be a base station of some other type. The eNB <NUM> may be equipped with antennas 234a through 234t, and the UE <NUM> may be equipped with antennas 252a through 252r.

At the eNB <NUM>, a transmit processor <NUM> may receive data from a data source <NUM> and control information from a controller/processor <NUM>. The control information may be for the PBCH, PCFICH, PHICH, PDCCH, etc. The data may be for the PDSCH, etc. The transmit processor <NUM> may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor <NUM> may also generate reference symbols, e.g., for the PSS, SSS, and cell-specific reference signal. A transmit (TX) multiple-input multiple-output (MIMO) processor <NUM> may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 232a through 232t. Downlink signals from modulators 232a through 232t may be transmitted via the antennas 234a through 234t, respectively.

At the UE <NUM>, the antennas 252a through 252r may receive the downlink signals from the eNB <NUM> and may provide received signals to the demodulators (DEMODs) 254a through 254r, respectively. A MIMO detector <NUM> may obtain received symbols from all the demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols.

On the uplink, at the UE <NUM>, a transmit processor <NUM> may receive and process data (e.g., for the PUSCH) from a data source <NUM> and control information (e.g., for the PUCCH) from the controller/processor <NUM>. The symbols from the transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by the modulators 254a through 254r (e.g., for SC-FDM, etc.), and transmitted to the eNB <NUM>. At the eNB <NUM>, the uplink signals from the UE <NUM> may be received by the antennas <NUM>, processed by the demodulators <NUM>, detected by a MIMO detector <NUM> if applicable, and further processed by a receive processor <NUM> to obtain decoded data and control information sent by the UE <NUM>. The processor <NUM> may provide the decoded data to a data sink <NUM> and the decoded control information to the controller/processor <NUM>.

The controllers/processors <NUM> and <NUM> may direct the operation at the eNB <NUM> and the UE <NUM>, respectively. The controller/processor <NUM> and/or other processors and modules at the eNB <NUM> may perform or direct the execution of various processes for the techniques described herein. The controllers/processor <NUM> and/or other processors and modules at the UE <NUM> may also perform or direct the execution of the functional blocks illustrated in <FIG> and <FIG>, and/or other processes for the techniques described herein. The memories <NUM> and <NUM> may store data and program codes for the eNB <NUM> and the UE <NUM>, respectively.

Multiple-input multiple-output (MIMO) technology generally allows communication to take advantage of the spatial dimension through use of channel state information (CSI) feedback at the eNB. An eNB may broadcast cell-specific CSI reference signals (CSI-RS) for which the UE measures CSI based on configurations signaled by eNB via RRC, such as CSI-RS resource configuration and transmission mode. The CSI-RS are periodically transmitted at periodicities of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or the like. A UE may report CSI at CSI reporting instances also configured by the eNB. As a part of CSI reporting the UE generates and reports channel quality indicator (CQI), precoding matrix indicator (PMI), and rank indicator (RI). The CSI can be reported either via PUCCH or via PUSCH and may be reported either periodically or aperiodically, with potentially different granularity. When reported via PUCCH, the payload size for CSI may be limited.

In order to increase system capacity, full-dimensional (FD)-MIMO technology has been considered, in which an eNB uses a two-dimensional (2D) active antenna array with a large number of antennas with antenna ports having both horizontal and vertical axes, and has a larger number of transceiver units. For conventional MIMO systems, beamforming has typically implemented using only azimuth dimension, although of a 3D multi-path propagation. However, for FD-MIMO each transceiver unit has its own independent amplitude and phase control. Such capability together with the 2D active antenna array allows the transmitted signal to be steered not only in the horizontal direction, as in conventional multi-antenna systems, but also simultaneously in both the horizontal and the vertical direction, which provides more flexibility in shaping beam directions from an eNB to a UE. Providing dynamic beam steering in the vertical direction has been shown to result in significant gain in interference avoidance. Thus, FD-MIMO technologies may take advantage of both azimuth and elevation beamforming, which would greatly improve MIMO system capacity and signal quality.

<FIG> is a block diagram illustrating a typical 2D active antenna array <NUM>. Active antenna array <NUM> is a <NUM>-transmitter, cross-polarized uniform planar antenna array comprising four columns, in which each column includes eight cross-polarized vertical antenna elements. Active antenna arrays are often described according to the number of antenna columns (N), the polarization type (P), and the number of vertical elements having the same polarization type in one column (M). Thus, active antenna array <NUM> has four columns (N = <NUM>), with eight vertical (M = <NUM>) cross-polarized antenna elements (P = <NUM>).

For a 2D array structure, in order to exploit the vertical dimension by elevation beamforming the CSI is needed at the base station. The CSI, in terms of PMI, RI, and CQI, can be fed back to the base station by a mobile station based on downlink channel estimation and predefined PMI codebook(s). However, different from the conventional MIMO system, the eNB capable of FD-MIMO is typically equipped with a large scale antenna system and, thus, the acquisition of full array CSI from the UE is quite challenging due to the complexity of channel estimation and both excessive downlink CSI-RS overhead and uplink CSI feedback overhead.

For CSI reporting in systems having FD-MIMO, a CSI process may be configured with either of two CSI reporting classes, class A non-precoded or class B beamformed. <FIG> is a block diagram illustrating an example base station <NUM> transmitting non-precoded CSI-RS <NUM>. In class A non-precoded reporting, one non-zero power (NZP) CSI-RS resource per CSI process may be used for channel measurement in which the number of CSI-RS ports may be <NUM>, <NUM>, or <NUM>. This category includes schemes where different CSI-RS ports may have the same wide beam width and direction and, hence, generally are useful in cell wide coverage. Interference measurement in class A reporting may include one CSI--interference measurement (IM) resource per CSI process. The UE may report rank indicator, and CQI, as well as PMI, which consists of a first PMI corresponding to the parameters (i<NUM>, i<NUM>) and one or multiple second PMI corresponding to the parameter, i<NUM>.

Base station <NUM> serves UEs <NUM> and <NUM> and UEs <NUM> and <NUM> in structure <NUM>. 2D CSI-RS ports transmit non-precoded CSI-RS <NUM> and PDSCH <NUM> to UEs <NUM>-<NUM>. In reporting CSI feedback, UEs <NUM>-<NUM> measure the non-precoded CSI-RS and reports CQI, first PMI (i<NUM>, i<NUM>) and one or more second PMI, i<NUM>, (2D codebook), and rank indicator to base station <NUM>.

<FIG> is a block diagram illustrating an example base station <NUM> transmitting beamformed CSI-RS using CSI-RS resources <NUM>-<NUM>. CSI-RS resources <NUM>-<NUM> may be directed to serve different UE groups, such as UE group <NUM>, including UEs <NUM> and <NUM>, and UE group <NUM>, including UEs <NUM> and <NUM> in structure <NUM>. Because different CSI-RS resources are used for different UE groups, when providing CSI feedback, UEs <NUM>-<NUM> report CQI, PMI (1D codebook), rank indicator, as well as the CSI-RS resource indicator (CRI), if K > <NUM>, which identifies to base station <NUM> which of the CSI-RS resources the UE has measured and provided channel state information (CSI) feedback for.

In class B beamformed CSI reporting, each CSI process may be associated with K NZP CSI-RS resources/configurations, with Nk ports for the kth CSI-RS resource (K could be ≥ <NUM>), in which Nk may be <NUM>, <NUM>, <NUM>, or <NUM>, and may be different for each CSI-RS resource. Each CSI-RS resource may also have different CSI-RS port virtualization, e.g., virtualized from different sets of antenna elements or from the same set of antenna elements but with different beamforming weights. Multiple CSI-IM per CSI process is also possible, with one-to-one linkage to each NZP CSI-RS resource.

For FD-MIMO, CSI-RS with more than <NUM> ports may be supported. CSI-RS port layout can be either <NUM>-D or <NUM>-D, according to the configured parameters (N<NUM>, N<NUM>), for which N<NUM> and N<NUM> determines the number of CSI-RS port in the <NUM>st and <NUM>nd dimension.

<FIG> is a block diagram illustrating different port layout configurations <NUM> and <NUM> for a <NUM>-port CSI-RS resource. Each of the antenna arrays illustrated in port configurations <NUM> and <NUM> is a <NUM>-port antenna array. However, whichever number is designated for N<NUM> and N<NUM> will result in a different configuration of antenna ports. For example, with port configuration <NUM>, N<NUM>=<NUM> and N<NUM>=<NUM>. Therefore, port configuration <NUM> begins with port <NUM> with port <NUM> being designated as the first port in the row of ports above. In contrast, because port configuration <NUM> uses N<NUM>=<NUM> and N<NUM>=<NUM>, after port <NUM>, port <NUM> is in the next column of antenna ports.

For CSI-RS design with more than <NUM> ports, two things are generally considered: port indexing and resource configuration. Resource configuration assigns a set of physical resource elements (REs) for CSI-RS and port indexing includes mapping of CSI-RS ports to the assigned REs. In Rel-<NUM>, a <NUM>-port or <NUM>-port CSI-RS resource is composed as an aggregation of K CSI-RS configurations (e.g., K predetermined RE patterns). For example, a <NUM>-port resource may be aggregated by three <NUM>-port CSI-RS configurations and a <NUM>-port resource may be aggregated by two <NUM>-port configurations. Table <NUM> below indicates the resource configurations for <NUM>- and <NUM>-port antennas.

For port indexing, e.g., assigning a CSI-RS port to a predetermined RE pattern, the mapping approach may depend upon the configurable code division multiplex (CDM) length (e.g., <NUM> or <NUM>), which means that the mapping may be different depending on the CDM length. For a CDM length of two, the port indexing may be determined by: <MAT> and, for a CDM length of four, the port index may be determined by: <MAT>.

Where, p represents the port index in the <NUM>- and <NUM>-port CSI-RS resource, p' represents port numbering within each component configuration, <MAT> represents a number of ports in the component configurations, and i represents the index of the component configuration. It can be seen that, for a CDM length of two, the cross-polarized antenna ports are assigned to each component CSI-RS configuration, and, for a CDM length of four, sequential mapping of CSI-RS ports to each component configuration is applied and, as a result, antenna ports mapped to each component configuration may not be on same polarization.

<FIG> are block diagrams illustrating example aggregation of multiple <NUM>-port CSI-RS resources into a <NUM>-port CSI-RS resource <NUM>. CSI-RS resource <NUM> is a <NUM>-port (<NUM>,<NUM>,<NUM>) antenna array. When configured with a CDM length of <NUM>, as illustrated in <FIG>, CSI-RS resource <NUM> is implemented through aggregation of three <NUM>-port CSI-RS resources <NUM>, in which the antenna ports of the <NUM>-port CSI-RS resources <NUM> are selected based on cross-polarized antenna port sets. When configured with a CDM length of <NUM>, as illustrated in <FIG>, CSI-RS resource <NUM> is also implemented through aggregation of three <NUM>-port CSI-RS resources <NUM>, in which the antenna ports of the <NUM>-port CSI-RS resources <NUM> are sequential by antenna port indexing of the ports of CSI-RS resource <NUM> regardless of polarization.

It should be noted that CDM length <NUM> is typically applied to Rel-<NUM><NUM>/<NUM>-port CSI-RS resources, but usually not for Rel-<NUM><NUM>/<NUM>-port CSI-RS resources.

For CSI-RS with more than <NUM>-ports (e.g., <NUM>, <NUM>, <NUM>, <NUM> ports), the aggregation approach for resource configuration may be reused. In one optional aspect, the same Nk may be used for all K component CSI-RS configurations. In another optional aspect, a different Nk may be used for different component CSI-RS configurations.

For CSI-RS with more than <NUM>-ports, one design target is to allow port sharing with CSI-RS resources having smaller numbers of antenna ports, such as <NUM> and <NUM> ports. For example, ports mapped to one CSI-RS configuration may be reused by a legacy CSI-RS resource (e.g., <NUM> or <NUM>-ports). For the case of CDM length two, the port indexing for CSI-RS with more than <NUM>-ports can reuse the Rel-<NUM> methodology for <NUM>/<NUM>-ports CSI-RS in order to keep cross-polarized antenna ports on each component CSI-RS configuration. Port sharing of CDM length two CSI-RS resources with legacy CSI-RS resources is, thus, supported. For the case of CDM length four, however, reusing the Rel-<NUM> port indexing methodology (e.g., sequential mapping) does not support port sharing with legacy CSI-RS resources for CSI-RS port layout configurations when N<NUM> is neither <NUM> or <NUM>. In networks where CDM length eight is supported, port indexing for CSI-RS resources with more than <NUM>-ports should support CDM lengths across multiple CSI-RS configurations.

<FIG> is a block diagram illustrating a eNB <NUM> performing an example mapping of a <NUM>-port CSI-RS resource <NUM>, with a CDM length of four for CSI-RS transmissions to UE <NUM>. As noted above, port sharing with a <NUM>-port CSI-RS resource may not be feasible when reusing existing CDM length four port indexing for a <NUM>-port CSI-RS resource with N<NUM>=<NUM> and N<NUM>=<NUM>. A <NUM>-port CSI-RS resource with CDM length four provides for the antenna ports on each valid component configuration to be either a uniform 1D port layout or a uniform 2D port layout. If a component configuration results in a non-uniform 1D or 2D layout of ports, the resulting configuration would be invalid for the <NUM>-port CSI-RS resource. <NUM>-port CSI-RS resource <NUM> is shown mapped by eNB <NUM> to CSI-RS mappings <NUM> including, an <NUM>-port CSI-RS resource of CSI-RS configuration #<NUM>, a <NUM>-port CSI-RS resource of CSI-RS configuration #<NUM>, and a second <NUM>-port CSI-RS resource of CSI-RS configuration #<NUM>. However, as illustrated with CSI-RS mappings <NUM>, CSI-RS ports mapped from <NUM>-port CSI-RS resource <NUM> to CSI-RS configuration #<NUM><NUM> and CSI-RS configuration #<NUM><NUM> do not have either a uniform 1D or uniform 2D structure. Thus, CSI-RS configuration #<NUM> and #<NUM> may not be configured for a <NUM>-port CSI-RS resource for allowing port sharing. Accordingly, various aspects of the present disclosure provide for port permutation for certain CSI-RS configurations in order to create uniform resource configurations.

<FIG> is a block diagram illustrating example blocks executed to implement one aspect of the present disclosure. The example blocks will also be described with respect to eNB <NUM> as illustrated in <FIG> is a block diagram illustrating eNB <NUM> configured according to one aspect of the present disclosure. eNB <NUM> includes the structure, hardware, and components as illustrated for eNB <NUM> of <FIG>. For example, eNB <NUM> includes controller/processor <NUM>, which operates to execute logic or computer instructions stored in memory <NUM>, as well as controlling the components of eNB <NUM> that provide the features and functionality of eNB <NUM>. eNB <NUM>, under control of controller/processor <NUM>, transmits and receives signals via wireless radios 1200a-t and antennas 234a-t. Wireless radios 1200a-t includes various components and hardware, as illustrated in <FIG> for eNB <NUM>, including modulator/demodulators 232a-t, MIMO detector <NUM>, receive processor <NUM>, transmit processor <NUM>, and TX MIMO processor <NUM>.

At block <NUM>, a CSI-RS configuration is determined by the base station with a CSI-RS resource having greater than or equal to <NUM>-ports. For example, eNB <NUM> includes CSI-RS resources <NUM>, stored in memory <NUM>, which identifies the various resources associated with corresponding CSI-RS configurations. eNB <NUM> identifies those CSI-RS resources that have greater than or equal to <NUM> ports for port permutation.

At block <NUM>, the base station identifies a group of CSI-RS configurations into which one or more CSI-RS ports of the CSI-RS resource will be mapped. For example, eNB <NUM> also includes CSI-RS configurations <NUM>, stored in memory <NUM>, which identifies the various CSI-RS configurations for mapping the CSI-RS ports into. Under control of controller/processor <NUM>, the various configurations within CSI-RS configurations <NUM> are identified for mapping.

At block <NUM>, the base station applies a permutation to each port on the same polarization according to the configuration. eNB <NUM> executes port permutation logic <NUM>, under control of controller/processor <NUM>. Port permutation logic <NUM> includes soft mathematic operations in additional to mathematic operations that are implemented in hardware, such as adders to apply the port permutation formula for the modifying the port indexing. The execution environment of port permutation logic <NUM> is applied for each polarization, such that, with reference to <FIG>, a first operation of port permutation logic <NUM> would be applied to the antenna ports <NUM>-<NUM>, having a first polarization, and a second operation of port permutation logic <NUM> would be applied to the antenna ports <NUM>-<NUM>, having a second polarization.

At block <NUM>, the base station then sequentially maps the permutated CSI-RS ports to each component configuration. For example, under control of controller/processor <NUM>, eNB <NUM> executes RE mapping functionality <NUM> stored in memory <NUM>, which maps the permutated port indexes to the new port layout.

It should be noted that, the port permutation at block <NUM>, is applied for CSI-RS port layouts (N<NUM>, N<NUM>) where N<NUM> does not equal <NUM> or <NUM>, or as determined by higher layer signaling. Table <NUM> below provides when port permutation is and is not performed based on the number of CSI-RS resource ports.

As indicated in block <NUM>, port permutation through the execution environment of port permutation <NUM>, under control of controller/processor <NUM>, is separately applied for each polarization. Thus, in one aspect of the present disclosure, ports in the first polarization identified according to: <MAT>.

Have the port permutation equation applied as follows: <MAT>.

Ports in the second polarization identified according to: <MAT>.

The permutated port indexing for the <NUM>-port and <NUM>-port CSI-RS resources are shown in Table <NUM> below (bold = <NUM>st polarization; roman = <NUM>nd polarization).

<FIG> is a block diagram illustrating a eNB <NUM> configured according to one aspect of the present disclosure performing mapping of a <NUM>-port CSI-RS resource <NUM>, with a CDM length of four for CSI-RS transmissions to UE <NUM>. eNB <NUM> determines that the number of ports for CSI-RS resource <NUM> is greater than <NUM> and that configuration of the port layout provides an N<NUM> = <NUM>, which is not equal to either <NUM> or <NUM>, as noted above. As such, eNB <NUM> performs the port permutations according execution of port permutation logic <NUM> to aspects of the present disclosure on each of the polarizations of the antenna ports. The original ports, indexed as illustrated in CSI-RS mappings <NUM>, when applied to the execution environment of port permutation logic <NUM>, changes the port indexing through the permutations, as indicated in the first row (<NUM>-ports with (<NUM>,<NUM>)) of Table <NUM>. The permutated CSI-RS ports are assigned to each component CSI-RS configuration, CSI-RS configurations #<NUM>-#<NUM>, of CSI-RS mappings <NUM>, by using the sequential mapping approach.

For example, the permutated CSI-RS ports with an index from <MAT> to <MAT> are assigned by eNB <NUM> to the kth component CSI-RS configuration. It may be seen that the CSI-RS ports mapped to CSI-RS configuration #<NUM><NUM> and CSI-RS configuration #<NUM><NUM>, after the port permutation function, have a uniform 2D port structure and, thus, can now be reused by a <NUM>-port CSI-RS resource.

Alternatively, port indexing for CSI-RS resources with more than <NUM>-ports can be written as: <MAT> where
<MAT> is port indexing within the kth component CSI-RS configuration, and f is a permutation function, e.g., f(p) = p, if either port permutation is not configured or <MAT> and <MAT>.

Additional aspects of the present disclosure provide for CSI-RS resources having more than <NUM>-ports and a CDM of length eight to achieve full CSI-RS power utilization with <NUM> dB power boosting and to improve CSI-RS coverage. One issue with CDM of length eight is the construction of the RE sets, since the simple way of using eight REs within an <NUM>-port CSI-RS configuration cannot achieve the desired maximum <NUM> dB power boosting, such as with the CSI-RS on symbol <NUM>/<NUM>, thus, not achieving full power utilization.

<FIG> is a block diagram illustrating an eNB <NUM> mapping CSI-RS resources with a CDM length of eight for CSI-RS transmissions to UE <NUM>. When transmitting CSI-RS to UE <NUM>, the CSI-RS resources with a CDM length of eight are mapped to resource block (RB) <NUM> in a predetermined pattern of <NUM> REs. RB <NUM> includes <NUM> carriers across <NUM> OFDM symbols divided into a first slot <NUM> of seven OFDM symbols and a second slot <NUM> of seven OFDM symbols. The CSI-RS resource configuration or pattern of REs for the CDM length eight illustrated in RB <NUM> provides for the CSI-RS RE sets across six symbols. However, this particular pattern for CDM length eight may not be supported for TDD DwPTS of the special subframe, as only <NUM> symbols would be available for CSI-RS. Thus, if CDM length eight is supported, it may be preferred that the network flexibly configure the sets of REs based on the available CSI-RS resource.

A CSI-RS resource with CDM length of eight is generally composed as an aggregation of K=<NUM> CSI-RS configurations with the same <MAT>. The four CSI-RS configurations can be any four selected from a total of five possible configurations, labeled with numbers <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> in <FIG>. A CDM length of two is assumed for each of the CSI-RS configurations. One CSI-RS port will be mapped to all of the four configurations, e.g., CSI-RS port p ∈ (<NUM>,. ,<NUM> + <NUM>N<NUM>N<NUM> -<NUM>) is mapped to <MAT> of CSI-RS configurations #<NUM>, #<NUM>, #<NUM> and #<NUM>. Ports {<NUM>, <NUM>, <NUM>, <NUM>} are mapped to p' = <NUM> of CSI-RS configurations #<NUM>, <NUM>, <NUM>, and <NUM>, and ports {<NUM>, <NUM>, <NUM>, <NUM>} are mapped to p' = <NUM> of CSI-RS configurations #<NUM>, <NUM>, <NUM>, and <NUM>, etc. Since a CDM length of two is assumed for port p' in each CSI-RS configurations, e.g., port p' = <NUM> and p' = <NUM> are mapped to the same set of two REs by a length-<NUM> orthogonal cover code [<NUM><NUM>] or [<NUM> -<NUM>]. Therefore, ports {<NUM>, <NUM>, <NUM>, <NUM>} and ports {<NUM>, <NUM>, <NUM>, <NUM>} are in the same CDM-<NUM> groups. Similarly, ports {<NUM>, <NUM>, <NUM>, <NUM>} and ports {<NUM>, <NUM>, <NUM>, <NUM>} are in a second CDM-<NUM> group, ports {<NUM>, <NUM>, <NUM>, <NUM>} and ports {<NUM>, <NUM>, <NUM>, <NUM>} are in a third CDM-<NUM> group, and ports {<NUM>, <NUM>, <NUM>, <NUM>} and ports {<NUM>, <NUM>, <NUM>, <NUM>} are in a fourth CDM-<NUM> group. The set of REs for CDM length eight may be constructed by eight REs occupied by port {x, x+<NUM>} of four configurations where x=<NUM>, <NUM>, <NUM> and <NUM>. The spreading sequence for CSI-RS port p is represented by wp = wp' ⊗wg, where wp' = [<NUM><NUM>] or [<NUM> -<NUM>] determined by port index p' and wg is sequence for spreading across four configurations wg = [a b c d] with <MAT> where a is used for first CSI-RS configuration, b is used for the second CSI-RS configuration, c is used for third CSI-RS configuration and d is used for the forth CSI-RS configuration. One example for wg spread sequence is to use a length-<NUM> Walsh code, that is w<NUM> = [<NUM><NUM><NUM><NUM>], w<NUM> = [<NUM> -<NUM><NUM> -<NUM>], w<NUM> = [<NUM><NUM> -<NUM> -<NUM>] and w<NUM> = [<NUM> -<NUM> -<NUM><NUM>].

<FIG> are block diagrams illustrating eNB <NUM>, configured according to aspects of the present disclosure with a CSI-RS resource mapping of CDM length eight for CSI-RS transmissions to UE <NUM>. RBs <NUM>, <NUM>, and <NUM> of <FIG>, respectively, are example possible RE sets for CDM length eight based on different combinations of <NUM>-port CSI-RS configurations. The RBs <NUM>-<NUM> provides RE mappings for CSI-RS configurations #<NUM>, #<NUM>, #<NUM>, and #<NUM> for CDM length eight. It should be noted that the different shadings for the CSI-RS configurations indicate a different set of REs available for CDM length eight. Based on the illustrated RBs <NUM>-<NUM>, it may be observed that the RE sets for CDM length eight may be provided either across <NUM> symbols or <NUM> symbols, based on the particular CSI-RS configuration used and, thus, CDM length eight may be supported in both downlink and DwPTS subframes.

The mapping of CSI-RS port p to spreading sequence wg and wp' in CMD length eight are provided in Tables <NUM> and <NUM> below. A combined length-<NUM> spreading sequence for each CSI-RS port p is provided in Table <NUM> below. It is noted that the mapping of spread sequence wp can be configuration order specific, e.g., a<NUM> and a<NUM> are used for first CSI-RS configuration, b<NUM> and b<NUM> are used for the second CSI-RS configuration, c<NUM> and c<NUM> are used for third CSI-RS configuration and d<NUM> and d<NUM> are used for the forth CSI-RS configuration. Alternatively, the mapping of the spread sequence can be non-configuration order specific, e.g., for the same four CSI-RS configurations the sequence mapping is not determined by the order of the configuration in the group of four CSI-RS configurations.

<FIG> is a block diagram illustrating example blocks executed to implement one aspect of the present disclosure. The example blocks will also be described with respect to eNB <NUM> as illustrated in <FIG>. At block <NUM>, a base station determines a CSI-RS resource having greater than or equal to a threshold number of antenna ports and a CDM length of at least eight. For example, eNB <NUM>, under control of controller/processor <NUM>, accesses CSI-RS resources <NUM> in memory <NUM> to identify the number of antennas ports associated with a particular CSI-RS resource. Controller/processor <NUM> compares the number of antenna ports against a threshold number and identifies the CDM length.

At block <NUM>, the base station identifies a group of four CSI-RS configurations into which one or more CSI-RS ports of the CSI-RS resource will be mapped into. For example, eNB <NUM>, under control of controller/processor <NUM> accesses CSI-RS configurations <NUM> to identify the configurations into which the CSI-RS ports will be mapped into.

At block <NUM>, the base station maps each of the one or more ports of the CSI-RS resource into each configuration of the group of four CSI-RS configurations. For example, eNB <NUM>, within the execution environment of CSI-RS configurations <NUM>, controller/processor <NUM> maps the ports of the identified CSI-RS resource into four of the available CSI-RS configurations.

At block <NUM>, the base station the one or more mapped ports to a set of REs within the corresponding configuration of the group of four CSI-RS configurations. For example, eNB <NUM>, under control of controller/processor <NUM>, executes RE mapping logic <NUM>, stored in memory <NUM>, which operates to map the identified antenna ports into a specific pattern of REs.

At block <NUM>, the base station transmits the one or more CSI-RS ports from the determined set of resource elements within the group of four CSI-RS configurations. For example, controller/processor <NUM> of eNB <NUM> transmits the one or more CSI-RS ports from the determined set of REs with the group of four CSI-RS configurations. the transmissions occur via wireless radios 1200a-t and antennas 234a-t.

The functional blocks and modules described herein may comprise processors, electronics devices, hardware devices, electronics components, logical circuits, memories, software codes, firmware codes, etc., or any combination thereof.

The present disclosure comprises a first aspect, such as a non-transitory computer-readable medium non-transitory computer-readable medium having program code recorded thereon, the program code comprising:.

Based on the first aspect, the non-transitory computer-readable medium of a second aspect, wherein the CSI-RS resource is configured according to a port layout defined by (N<NUM>, N<NUM>), and wherein the program code executable by the computer for causing the computer to apply the port permutation is triggered when N<NUM> is one of: not equal to <NUM>, not equal to <NUM>, or determined by higher layer signaling.

Based on the second aspect, the non-transitory computer-readable medium of a third aspect, wherein the program code executable by the computer for causing the computer apply a port permutation includes:.

A fourth aspect of the non-transitory computer-readable medium of any combination of the first through third aspects.

The present disclosure comprises a fifth aspect, such as a non-transitory computer-readable medium non-transitory computer-readable medium having program code recorded thereon, the program code comprising:.

Based on the fifth aspect, the non-transitory computer-readable medium of a sixth aspect, wherein the one or more mapped ports are allocated to the set of REs within the corresponding configuration based on a spreading sequence for spreading across the group of four CSI-RS configurations.

Based on the sixth aspect, the non-transitory computer-readable medium of a seventh aspect, wherein the group of four CSI-RS configurations include the set of REs positioned across one of: four symbols or six symbols, based on the corresponding CSI-RS configuration.

An eighth aspect of the non-transitory computer-readable medium of any combination of the fifth through seventh aspects.

In one or more exemplary designs, the functions described may be implemented through computer-executable instructions in hardware, software, firmware, or any combination thereof.

Claim 1:
A method of wireless communication, comprising:
determining (<NUM>), by a base station (<NUM>), a channel state information, CSI, reference signal, CSI-RS, resource having greater than or equal to a threshold number of antenna ports and a code divisional multiplex, CDM, length of at least eight;
identifying (<NUM>) a group of four CSI-RS configurations into which one or more CSI-RS ports of the CSI-RS resource will be mapped into;
mapping (<NUM>) each of the one or more ports of the CSI-RS resource into each configuration of the group of four CSI-RS configurations;
allocating (<NUM>) the one or more mapped ports to a set of resource elements, REs, within the corresponding configuration of the group of four CSI-RS configurations; and
transmitting (<NUM>) the one or more CSI-RS ports from the determined set of resource elements within the group of four CSI-RS configurations,
wherein the one or more mapped ports are allocated to the set of REs within the corresponding configuration based on a spreading sequence for spreading across the group of four CSI-RS configurations,
wherein the mapping of spreading sequence to the set of resource elements is determined by the order of the four CSI-RS configurations in the group of four CSI-RS configurations.