Matrix-based techniques for mapping resource elements to ports for reference signals

Techniques are described for wireless communication. A method of wireless communication at a first wireless device includes identifying a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid; mapping a plurality of resource elements of an orthogonal frequency-division multiplexing (OFDM) time-frequency resource grid to the plurality of ports based at least in part on the template mapping; receiving a reference signal from a second wireless device, on a subset of the plurality of ports, based at least in part on the mapping; and decoding the reference signal from a subset of the plurality of resource elements based at least in part on the mapping. In some cases, each port of the plurality of ports is associated with a corresponding radio frequency (RF) chain.

BACKGROUND

Field of the Disclosure

The present disclosure, for example, relates to wireless communication systems, and more particularly to matrix-based techniques for mapping resource elements to ports for reference signals.

Description of Related Art

A wireless multiple-access communication system may include a number of network access devices, each simultaneously supporting communication for multiple communication devices, otherwise known as user equipment (UEs). In a Long-Term Evolution (LTE) or LTE-Advanced (LTE-A) wireless communication system, a network access device may take the form of a base station, with a set of one or more base stations defining an eNodeB (eNB). In a next generation, new radio (NR), millimeter wave (mmW), or 5G wireless communication system, a network access device may take the form of a smart radio head (or radio head (RH)) or access node controller (ANC), with a set of smart radio heads in communication with an ANC defining a gNodeB (gNB). A network access device may communicate with a set of UEs on downlink channels (e.g., for transmissions from a network access device to a UE) and uplink channels (e.g., for transmissions from a UE to a network access device).

In some cases, a network access device may transmit a reference signal. A reference signal may be broadcast to all UEs. The reference signal may additionally or alternatively be transmitted to one UE or a subset of UEs. It is important that a reference signal be transmitted with a predetermined mapping of resource elements to ports (e.g., radio frequency (RF) chains). The predetermined mapping of resource elements may be distributed in both time and frequency.

SUMMARY

In one example, a method of wireless communications at a first wireless device is described. The method may include identifying a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid, mapping a plurality of resource elements of an orthogonal frequency-division multiplexing (OFDM) time-frequency resource grid to the plurality of ports based at least in part on the template mapping, receiving a reference signal from a second wireless device, on a subset of the plurality of ports, based on the mapping, and decoding the reference signal from a subset of the plurality of resource elements based at least in part on the mapping. In some cases, each port of the plurality of ports is associated with a corresponding radio frequency (RF) chain.

In one example, an apparatus for wireless communications at a first wireless device is described. The apparatus may include means for identifying a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid; means for mapping a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping; means for receiving a reference signal from a second wireless device, on a subset of the plurality of ports, based at least in part on the mapping; and means for decoding the reference signal from a subset of the plurality of resource elements based at least in part on the mapping. In some cases, each port of the plurality of ports is associated with a corresponding RF chain.

In one example, another apparatus for wireless communications at a first wireless device is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be operable, when executed by the processor, to cause the apparatus to identify a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid; map a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping; receive a reference signal from a second wireless device, on a subset of the plurality of ports, based at least in part on the mapping; and decode the reference signal from a subset of the plurality of resource elements based at least in part on the mapping. In some cases, each port of the plurality of ports is associated with a corresponding RF chain.

In one example, a non-transitory computer-readable medium storing computer-executable code for wireless communication at a first wireless device is described. The code may be executable to identify a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid; map a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping; receive a reference signal from a second wireless device, on a subset of the plurality of ports, based at least in part on the mapping; and decode the reference signal from a subset of the plurality of resource elements based at least in part on the mapping. In some cases, each port of the plurality of ports is associated with a corresponding RF chain.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, instructions, or code for receiving a plurality of reference signals, including the reference signal, from the second wireless device, on a plurality of subsets of the plurality of ports, based at least in part on the mapping. In some examples, the plurality of reference signals may be received using a receive beam sweep in time and frequency.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the subset of the plurality of resource elements may be distributed in time and frequency over the OFDM time-frequency resource grid.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the mapping may include mapping each resource element of the plurality of resource elements to a single port of the plurality of ports based at least in part on the template mapping. In some examples, the mapping may include mapping each resource element of the plurality of resource elements to a group of ports of the plurality of ports, based at least in part on an orthogonal cover code (OCC) associated with the template mapping. In some examples, a number of ports in the group of ports may be based at least in part on a length of the OCC.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, instructions, or code for applying an OCC to at least one group of resource elements of the plurality of resource elements. The application of the OCC to a group of resource elements may map each resource element in the group of resource elements to a group of ports, with the group of ports being associated with the group of resource elements by the mapping of the plurality of resource elements to the plurality of ports.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the OFDM time-frequency resource grid may include at least one of a second plurality of frequency subcarriers greater in number than the first plurality of frequency subcarriers, a second plurality of time periods greater in number than the first plurality of time periods, or a combination thereof.

In one example, another method of wireless communications at a first wireless device is described. The method may include identifying a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid; mapping a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping; mapping a reference signal to a subset of the plurality of resource elements based at least in part on the mapping of the plurality of resource elements to the plurality of ports; and transmitting the mapped reference signal to at least a second wireless device, from a subset of the plurality of ports, based at least in part on the mapping of the plurality of resource elements to the plurality of ports and the mapping of the reference signal to the subset of the plurality of resource elements. In some cases, each port of the plurality of ports may be associated with a corresponding RF chain.

In one example, another apparatus for wireless communications at a first wireless device is described. The apparatus may include means for identifying a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid; means for mapping a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping; means for mapping a reference signal to a subset of the plurality of resource elements based at least in part on the mapping of the plurality of resource elements to the plurality of ports; and means for transmitting the mapped reference signal to at least a second wireless device, from a subset of the plurality of ports, based at least in part on the mapping of the plurality of resource elements to the plurality of ports and the mapping of the reference signal to the subset of the plurality of resource elements. In some cases, each port of the plurality of ports may be associated with a corresponding RF chain.

In one example, another apparatus for wireless communications at a first wireless device is described. The apparatus may include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be operable, when executed by the processor, to cause the apparatus to identify a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid; map a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping; map a reference signal to a subset of the plurality of resource elements based at least in part on the mapping of the plurality of resource elements to the plurality of ports; and transmit the mapped reference signal to at least a second wireless device, from a subset of the plurality of ports, based at least in part on the mapping of the plurality of resource elements to the plurality of ports and the mapping of the reference signal to the subset of the plurality of resource elements. In some cases, each port of the plurality of ports may be associated with a corresponding RF chain.

In one example, another non-transitory computer-readable medium storing computer-executable code for wireless communication at a first wireless device is described. The code may be executable to identify a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid; map a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping; map a reference signal to a subset of the plurality of resource elements based at least in part on the mapping of the plurality of resource elements to the plurality of ports; and transmit the mapped reference signal to at least a second wireless device, from a subset of the plurality of ports, based at least in part on the mapping of the plurality of resource elements to the plurality of ports and the mapping of the reference signal to the subset of the plurality of resource elements. In some cases, each port of the plurality of ports may be associated with a corresponding RF chain.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, instructions, or code for mapping a plurality of reference signals including the reference signal to a plurality of subsets of the plurality of resource elements based at least in part on the mapping of the plurality of resource elements to the plurality of ports. In some examples, the method, apparatus, and non-transitory computer-readable medium may further include processes, features, means, instructions, or code for transmitting the mapped plurality of reference signals to at least the second wireless device, from a plurality of subsets of the plurality of ports, based at least in part on the mapping of the plurality of resource elements to the plurality of ports and the mapping of the reference signal to the subset of the plurality of resource elements. In some examples, the mapped plurality of reference signals may be transmitted using a transmit beam sweep in time and frequency.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the subset of the plurality of resource elements may be distributed in time and frequency over the OFDM time-frequency resource grid.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the mapping of the plurality of resource elements to the plurality of ports may include mapping each resource element of the plurality of resource elements to a single port of the plurality of ports based at least in part on the template mapping. In some examples, the mapping of the plurality of resource elements to the plurality of ports may include mapping each resource element of the plurality of resource elements to a group of ports of the plurality of ports, based at least in part on an OCC associated with the template mapping. In some examples, a number of ports in the group of ports may be based at least in part on a length of the OCC.

Some examples of the method, apparatus, and non-transitory computer-readable medium described above may further include processes, features, means, instructions, or code for applying an OCC to at least one group of resource elements of the plurality of resource elements. The application of the OCC to a group of resource elements may map each resource element in the group of resource elements to a group of ports, with the group of ports being associated with the group of resource elements by the mapping of the plurality of resource elements to the plurality of ports.

In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the OFDM time-frequency resource grid may include at least one of a second plurality of frequency subcarriers greater in number than the first plurality of frequency subcarriers, a second plurality of time periods greater in number than the first plurality of time periods, or a combination thereof.

DETAILED DESCRIPTION

A portion of next generation, NR, or 5G wireless communication systems will be based on millimeter wave communication. Millimeter wave communication is expected to provide very high data rates at ultra-low latencies. Beamforming is expected to be used to overcome the poor link margins that are typically associated with mmW communication. Beamforming, and particularly the sweeping of beams by both network access devices and UEs, may use reference signals allocated in time and frequency. Pre-5G wireless communication systems have provided for the transmission of reference signals for beam sweeps based on a time-based mapping or frequency-based mapping of resource elements to ports. More specifically, prior to NR, each antenna port have been allocated to a resource block. However, with the advent of millimeter wave communication, a large number of antennas and a smaller number of RF chains are available for communication. As a result, an RF chain may be mapped to an antenna port in order to effectively communicate using millimeter wave communication. The present disclosure describes matrix-based techniques for mapping resource elements to ports for reference signals. Depending on implementation, the matrix-based techniques can minimize the overhead needed to map resource elements to ports, facilitate simultaneous sweeping of transmit beams (by a network access device) and receive beams (by a UE), and provide for independent mapping periodicities in time and frequency.

FIG. 1shows an example of a wireless communication system100, in accordance with various aspects of the present disclosure. The wireless communication system100may include network access devices105(e.g., gNBs105-a, ANCs105-b, and/or RHs105-c), UEs115, and a core network130. The core network130may provide user authentication, access authorization, tracking, IP connectivity, and other access, routing, or mobility functions. At least some of the network access devices105(e.g., gNBs105-aor ANCs105-b) may interface with the core network130through backhaul links132(e.g., S1, S2, etc.) and may perform radio configuration and scheduling for communication with the UEs115. In various examples, the ANCs105-bmay communicate, either directly or indirectly (e.g., through core network130), with each other over backhaul links134(e.g., X1, X2, etc.), which may be wired or wireless communication links. Each ANC105-bmay additionally or alternatively communicate with a number of UEs115through a number of smart radio heads (e.g., RHs105-c). In an alternative configuration of the wireless communication system100, the functionality of an ANC105-bmay be provided by a radio head105-cor distributed across the radio heads105-cof an gNB105-a. In another alternative configuration of the wireless communication system100(e.g., an LTE/LTE-A configuration), the radio heads105-cmay be replaced with base stations, and the ANCs105-bmay be replaced by base station controllers (or links to the core network130). In some examples, the wireless communication system100may include a mix of radio heads105-c, base stations, and/or other network access devices105for receiving/transmitting communications according to different radio access technologies (RATs) (e.g., LTE/LTE-A, 5G, Wi-Fi, etc.).

A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs115with service subscriptions with a network provider. A small cell may include a lower-powered radio head or base station, as compared with a macro cell, and may operate in the same or different frequency band(s) as macro cells. Small cells may include pico cells, femto cells, and micro cells according to various examples. A pico cell may cover a relatively smaller geographic area and may allow unrestricted access by UEs115with service subscriptions with a network provider. A femto cell also may cover a relatively small geographic area (e.g., a home) and may provide restricted access by UEs115having an association with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs for users in the home, and the like). A gNB for a macro cell may be referred to as a macro gNB. A gNB for a small cell may be referred to as a small cell gNB, a pico gNB, a femto gNB, or a home gNB. A gNB may support one or multiple (e.g., two, three, four, and the like) cells (e.g., component carriers).

The wireless communication system100may support synchronous or asynchronous operation. For synchronous operation, the gNBs105-aand/or radio heads105-cmay have similar frame timing, and transmissions from different gNBs105-aand/or radio heads105-cmay be approximately aligned in time. For asynchronous operation, the gNBs105-aand/or radio heads105-cmay have different frame timings, and transmissions from different gNBs105-aand/or radio heads105-cmay not be aligned in time. The techniques described herein may be used for either synchronous or asynchronous operations.

The UEs115may be dispersed throughout the wireless communication system100, and each UE115may be stationary or mobile. A UE115may also include or be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology. A UE115may 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, an Internet of Everything (IoE) device, etc. A UE115may be able to communicate with various types of gNBs105-a, radio heads105-c, base stations, access points, or other network access devices, including macro gNBs, small cell gNBs, relay base stations, and the like. A UE115may also be able to communicate directly with other UEs115(e.g., using a peer-to-peer (P2P) protocol).

The communication links125shown in wireless communication system100may include uplinks (ULs) from a UE115to a radio head105-c, and/or downlinks (DLs), from a radio head105-cto a UE115. The downlinks may also be called forward links, while the uplinks may also be called reverse links. Control information and data may be multiplexed on an uplink or downlink according to various techniques. Control information and data may be multiplexed on an uplink or downlink, for example, using time-division multiplexing (TDM) techniques, frequency-division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques.

Each communication link125may include one or more carriers, where each carrier may be a signal made up of multiple sub-carriers (e.g., waveform signals of different frequencies) modulated according to one or more radio access technologies. Each modulated signal may be sent on a different sub-carrier and may carry control information (e.g., reference signals, control channels, etc.), overhead information, user data, etc. The communication links125may transmit bidirectional communications using Frequency Division Duplexing (FDD) techniques (e.g., using paired spectrum resources) or Time Division Duplexing techniques (e.g., using unpaired spectrum resources). Frame structures for frequency division duplex (FDD) (e.g., frame structure type 1) and time division duplex (TDD) (e.g., frame structure type 2) may be defined.

In some examples of the wireless communication system100, network access devices105(e.g., radio heads105-c) and UEs115may include multiple antennas for employing antenna diversity schemes to improve communication quality and reliability between network access devices105and UEs115. Additionally or alternatively, network access devices and UEs115may employ multiple-input, multiple-output (MIMO) techniques that may take advantage of multi-path environments to transmit multiple spatial layers carrying the same or different coded data. In some cases, signal processing techniques such as beamforming (i.e., directional transmission) may be used with MIMO techniques to coherently combine signal energies and overcome the path loss in specific beam directions. Precoding (e.g., weighting transmissions on different paths or layers, or from different antennas) may be used in conjunction with MIMO or beamforming techniques.

In some examples, a UE115may include a wireless communication manager140, or a network access device105may include a wireless communication manager150. In some examples, the wireless communication manager140or150may be used to identify a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid; map a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping; receiving a reference signal from a second wireless device, on a subset of the plurality of ports, based at least in part on the mapping; and decode the reference signal from a subset of the plurality of resource elements based at least in part on the mapping, as described for example with reference toFIGS. 3-8 and 13-15. In some examples, the wireless communication manager140or150may additionally or alternatively be used to identify a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid; map a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping; map a reference signal to a subset of the plurality of resource elements based at least in part on the mapping of the plurality of resource elements to the plurality of ports; and transmit the mapped reference signal to at least a second wireless device, from a subset of the plurality of ports, based at least in part on the mapping of the plurality of resource elements to the plurality of ports and the mapping of the reference signal to the subset of the plurality of resource elements.

FIG. 2shows an example of a transmission diagram200including a network access device205and a UE215, in accordance with various aspects of the present disclosure. The network access device205and UE215may be examples of aspects of the network access devices and UEs described with reference toFIG. 1. In transmission diagram200, network access device205includes multiple antenna ports210, where each antenna port210is associated with a single RF transmit chain230. Each antenna port210may be coupled with multiple physical antennas211. The physical antennas may be arranged in antenna panels225, where each antenna panel225may include multiple physical antennas211. Each antenna panel225may be capable of implementing one or more antenna configurations. Each antenna configuration may be referred to as a beam. Each antenna panel225may be single polarized or dual polarized. In some examples, the network access device may include M antenna panels225(e.g., antenna panels225-a,225-b, . . . ,225-m), where each antenna panel225includes N physical antennas211. The distance between the physical antennas211of an antenna panel225may be less than λ/2, where λ describes the shortest working wavelength of the transmitter. Each antenna panel225may be configured to have its own ability to perform phase offsets for the antennas in that antenna panel (e.g., phase shifters221) to generate a beam with selectable beam direction and/or beam width from one of the antenna ports210. Each RF transmit chain230may include digital processing capability for an RF signal, and may generate an analog RF output signal (e.g., via a digital-to-analog converter (DAC)) to transmit via one or more antenna panels225. In some cases, different antenna panels225associated with a common antenna port210may transmit at different frequencies and in different directions. As an example, the outputs of physical antennas211may form a transmit beam260. When transmitting, the network access device205may map a transmission (e.g., a control channel, data channel, or reference signal) to a number of resource elements distributed in time and/or frequency, and transmit the transmission from a number of ports210mapped to the resource elements.

UE215may include multiple physical antennas212and multiple antenna ports220. The physical antennas212may be grouped, where signals from each group are combined in an antenna beam receive component222. For example, each antenna beam receive component222may be an analog combiner that combines signals from multiple physical antennas212in the analog domain. The combined signal may be processed by an RF chain235for reception via an antenna port220. Thus, each antenna port220may be associated with one RF chain235and be capable of receiving a composite beam transmitted from one or more antenna panels225of the network access device205. Although illustrated with two antenna ports220, a UE may have only one, or more than two antenna ports220. When receiving, the UE215may receive a transmission mapped to a number of resource elements distributed in time and/or frequency (e.g., a control channel, data channel, or reference signal) on a composite beam via and antenna port, and decode received symbols of the transmission from the number of resource elements. In some examples, the resource element to port mapping may be based on a template matrix (or template mapping), as described with reference toFIGS. 3 and 4.

FIG. 3shows a template matrix300that may be used to map resource elements to ports, in accordance with various aspects of the present disclosure. The template matrix, P, provides a template mapping of ports (e.g., 16 ports numbered200,201, . . .214,215) to M subcarriers (e.g., 4 subcarriers) and N time periods (e.g., 4 OFDM symbol periods) of a template time-frequency resource grid. In the example ofFIG. 3, the template matrix P is a 2-dimensional 4×4 matrix. The first dimension (e.g., shown horizontally inFIG. 3) may indicate time periods used to map the plurality of ports and the second dimension (e.g., shown vertically inFIG. 3) may indicate frequency resources used to map the ports. In some cases, the template matrix P may be associated with a plurality of RF chains scanning over different symbols. In this example, the template matrix P is associated with 4 RF chains scanning over 4 different symbols. In some examples, each column of the template matrix P may be associated with a separate UE (such as UE115). For example, the ports200,208,204and212may be used to scan 4 different beams associated with a particular UE. Similarly, the ports201,209,205and213may be used to scan different beams for a second UE, the ports202,210,206and214may be used to scan different beams for a third UE, and the ports203,211,207and215may be used to scan different beams for a fourth UE. In some examples, a base station (e.g., network access device105) may be configured to allocate resources to 4 different beams directed to 4 different UEs over 4 different time periods. In some examples, the base station (e.g., network access device105) may allocate additional frequency resources to repeat the template matrix P in the frequency dimension, and additional repetitions of the template matrix may be associated with different antenna panels. The base station may allocate additional time resources to repeat the template matrix P in the time dimension to vary the beam directions associate with each antenna port for a given panel. Repetition of the template matrix P is described in more detail with reference toFIG. 4. It should be understood that the template matrix P may be mapped to contiguous or non-contiguous resources within a set of time-frequency resources. For example, every other, every third, or every fourth subcarrier may be used for transmitting reference signals via the antenna ports, and the template matrix P may be mapped to the reference signal resource elements.

FIG. 4shows a mapping400of resource elements to ports, in accordance with various aspects of the present disclosure. Each resource element405is defined by an intersection of a frequency subcarrier455and a time period445(e.g., an OFDM symbol period) in an OFDM time-frequency resource grid410. By way of example, the OFDM time-frequency resource grid410shown inFIG. 4includes (or spans) F subcarriers455(e.g., 12 subcarriers) and T time periods445(e.g., 8 OFDM symbol periods). Thus, the OFDM time-frequency resource grid410includes 96 resource elements405.

The resource mapping400shows the mapping of a plurality of ports (e.g., 16 ports numbered200,201, . . .214,215) to the elements405using a template mapping, such as the template mapping provided by the template matrix, P, described with reference toFIG. 3. In some cases, the template matrix P may be repeated over time and frequency resources. Based on the M×N template matrix P, the resource element (k, l) may be mapped to a port number port(k, l) of the template matrix P based on the rule:
port(k,l)=P(kmodM,lmodN),
where k is the k-th subcarrier frequency of the OFDM time-frequency resource grid410, l is the l-th time period of the OFDM time-frequency resource grid410, 0≤k≤F−1, and 0≤l≤T−1.

The numbers of the ports mapped to each of the resource elements405are noted within each resource element405. In some examples, transmitting and receiving devices may be configured with a plurality of template matrices, and may select a template matrix for use based on various parameters.

In some examples, one or more reference signals may be mapped to the resource elements405based at least in part on the mapping400. In one example, the first row420of resource elements405shown inFIG. 4may be mapped to ports200-203, the second row425of resource elements405may be mapped to ports208-211, the third row430of resource elements405may be mapped to ports204-207, and the fourth row435of resource elements405may be mapped to ports212-215. In some cases, different instances of the template matrix P may be associated with different beam directions for the antenna ports. For example, the template matrix P for a first set of subcarriers450-aand a first set of time periods440-amay be associated with a first beam direction for a first antenna panel. Additional instances of the template matrix P may be associated with different beam directions for the first antenna panel or different antenna panels. For example, for additional sets of time periods440, the template matrix P may be mapped to the same antenna panel using different beam directions. Thus, the instance of the template matrix P for the first set of subcarriers450-aand a second set of time periods440-bmay also be transmitted via the first antenna panel, but with different beam directions. The instance of the template matrix P for a second set of subcarriers450-band the first set of time periods440-amay be transmitted via a second antenna panel. The instance of the template matrix P for a third set of subcarriers450-cand the first set of time periods440-amay be transmitted via a third antenna panel. In some examples, different ports may be allocated to different polarizations (e.g., orthogonal polarizations)

In some examples, each antenna port may be associated with a corresponding RF chain at the transmitter. In some examples, each antenna port may also be associated with a corresponding RF chain at the receiver. Thus, a receiver may receive a composite beam over a given antenna port (e.g., antenna port200) in a given symbol period via one RF chain that may be coupled with one or more physical antennas (e.g., via an analog combiner). For example, a receiver may have four receive antenna ports used for receiving transmission via antenna ports200,208,204, and212, respectively. In some examples, the receiver may not be able to distinguish between the directions within the composite beam (e.g., because of analog combining for a given antenna port). The transmitter may transmit the template matrix P over five sets of time periods440, with each port being a composite of three beams (via the three antenna panels). Thus, the transmitter may transmit a total of 15 beams over the five sets of time periods440via each antenna port. The receiver may detect the energy of each composite beam and report the composite beam having the highest detected energy. The transmitter may then pursue finer beam refinement to select one or more beams from the identified composite beam for transmissions to the receiver.

In the mapping400, each resource element is mapped to a single port. At times, it may be useful to map a resource element to a linear combination of L ports, where L>1. In some examples, a resource element may be mapped to L ports using an orthogonal cover code (OCC) of length L bits, as shown inFIG. 5.

FIG. 5shows a mapping500of resource elements to ports based on an OCC, in accordance with various aspects of the present disclosure. Each resource element505is defined by an intersection of a frequency subcarrier and a time period (e.g., an OFDM symbol period) in an OFDM time-frequency resource grid510. By way of example, the OFDM time-frequency resource grid510shown inFIG. 5includes (or spans) a plurality of F frequency subcarriers and a plurality of T time periods.

Each resource element505in the OFDM time-frequency resource grid510may be mapped to a group of ports of a plurality of ports based on an OCC having a length of L bits. In some examples, the OFDM time-frequency resource grid510may be divided into a plurality of disjoint (non-overlapping) resource element blocks515having dimensions of FOCCfrequency subcarriers and TOCCtime periods, with each of FOCCand TOCCbeing equal to or greater than one, with at least one of FOCCor TOCCbeing greater than one, and with each resource element block515including L resource elements505(i.e., the area of each resource element block ROCC=FOCC×TOCC=L). Each resource element505within a resource element block515may be mapped to each of the L ports (i.e., to all ports in the set of ports P={p0, . . . , pL-1}) by the OCC.

In some examples, the OCC may be associated with a template mapping of ports to frequency subcarriers and time periods (e.g., the template matrix P described with reference toFIG. 3). In other examples, the OCC may be applied to groups of resource elements independently of a template mapping of ports to frequency subcarriers and time periods. That is, one or both of the dimensions of a group of resource blocks may differ from one or more of the corresponding dimensions of a template matrix, P, such that FOCC×TOCC≠M×N. In some examples, different OCCs may be applied to different groups of resource elements.

FIG. 6shows a block diagram600of an apparatus605for use in wireless communication, in accordance with various aspects of the present disclosure. The apparatus605may be an example of aspects of a UE or network access device described with reference toFIGS. 1 and 2. The apparatus605may include a receiver610, a wireless communication manager615, and a transmitter620. The apparatus605may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

The receiver610may receive data or control signals or information (i.e., transmissions), some or all of which may be associated with various information channels (e.g., data channels, control channels, etc.). Received signals or information, or measurements performed thereon, may be passed to other components of the apparatus605. The receiver610may include a single antenna or a set of antennas.

The wireless communication manager615and/or at least some of its various sub-components may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical devices. In some examples, the wireless communication manager615and/or at least some of its various sub-components may be a separate and distinct component in accordance with various aspects of the present disclosure. In other examples, the wireless communication manager615and/or at least some of its various sub-components may be combined with one or more other hardware components, including but not limited to an I/O component, a transceiver, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure. The wireless communication manager615may be an example of aspects of the wireless communication managers described with reference toFIG. 1.

The wireless communication manager615may be used to manage one or more aspects of wireless communications for the apparatus605, and may be used to identify a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid, to map a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping, and to transmit or receive reference signals based on the mapping. In some cases, each port of the plurality of ports is associated with a corresponding RF chain.

The transmitter620may transmit data or control signals or information (i.e., transmissions) generated by other components of the apparatus605, some or all of which may be associated with various information channels (e.g., data channels, control channels, etc.). In some examples, the transmitter620may be collocated with the receiver610in a transceiver. For example, the transmitter620and receiver610may be an example of aspects of the transceiver1130or1250described with reference toFIG. 11 or 12. The transmitter620may include a single antenna or a set of antennas.

FIG. 7shows a block diagram700of an apparatus705for use in wireless communication, in accordance with various aspects of the present disclosure. The apparatus705may be an example of aspects of a UE or apparatus described with reference toFIGS. 1, 2, and 6. The apparatus705may include a receiver710, a wireless communication manager715, and a transmitter720. The apparatus705may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

The receiver710may receive data or control signals or information (i.e., transmissions), some or all of which may be associated with various information channels (e.g., data channels, control channels, etc.). Received signals or information, or measurements performed thereon, may be passed to other components of the apparatus705. The receiver710may include a single antenna or a set of antennas.

The wireless communication manager715may include a template resource element-to-port mapper725, a reference signal reception manager730, and a reference signal decoder735. The wireless communication manager715may be an example of aspects of a wireless communication manager included in a UE, as described with reference toFIGS. 1 and 6.

The template resource element-to-port mapper725may be used to identify a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid, as described for example with reference toFIGS. 3 and 4. In some examples, each port of the plurality of ports may be associated with a corresponding RF chain. The template resource element-to-port mapper725may additionally or alternatively be used to map a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping, as described for example with reference toFIGS. 3 and 4. In some examples, the mapping may include mapping each resource element of the plurality of resource elements to a single port of the plurality of ports based at least in part on the template mapping. In some examples, the mapping may include mapping each resource element of the plurality of resource elements to a group of ports of the plurality of ports, based at least in part on an OCC associated with the template mapping, as described with reference toFIG. 5. In some examples, the number of ports in the group of ports may be based at least in part on a length of the OCC. In some examples, the OFDM time-frequency resource grid may include at least one of a second plurality of frequency subcarriers greater in number than the first plurality of frequency subcarriers, a second plurality of time periods greater in number than the first plurality of time periods, or a combination thereof.

The reference signal reception manager730may be used to receive one or more reference signals from a second wireless device, on one or more subsets of the plurality of ports, based at least in part on the mapping, as described for example with reference toFIGS. 3 and 4. In some examples, each subset of the plurality of resource elements may be distributed in time and frequency over the OFDM time-frequency resource grid.

The reference signal decoder735may be used to decode the reference signal(s) from one or more subsets of the plurality of resource elements based at least in part on the mapping, as described for example with reference toFIGS. 3 and 4.

The transmitter720may transmit data or control signals or information (i.e., transmissions) generated by other components of the apparatus705, some or all of which may be associated with various information channels (e.g., data channels, control channels, etc.). In some examples, the transmitter720may be collocated with the receiver710in a transceiver. For example, the transmitter720and receiver710may be an example of aspects of the transceiver1130or1250described with reference toFIG. 11 or 12. The transmitter720may include a single antenna or a set of antennas.

FIG. 8shows a block diagram800of a wireless communication manager815, in accordance with various aspects of the present disclosure. The wireless communication manager815may be an example of aspects of a wireless communication manager included in a UE, as described with reference toFIGS. 1, 6, and 7. The wireless communication manager815may include a template resource element-to-port mapper825, an OCC resource element-to-port mapper830, a reference signal reception manager835, and a reference signal decoder840. Each of these components may communicate, directly or indirectly, with one another (e.g., via one or more buses). The template resource element-to-port mapper825, reference signal reception manager835, and reference signal decoder840may be configured similarly to, and may perform the functions of, the template resource element-to-port mapper725, reference signal reception manager730, and reference signal decoder735described with reference toFIG. 7.

The template resource element-to-port mapper825may be used to identify a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid, as described for example with reference toFIGS. 3 and 4. In some examples, each port of the plurality of ports may be associated with a corresponding RF chain. The template resource element-to-port mapper825may additionally or alternatively be used to map a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping, as described for example with reference toFIGS. 3 and 4. In some examples, the OFDM time-frequency resource grid may include at least one of a second plurality of frequency subcarriers greater in number than the first plurality of frequency subcarriers, a second plurality of time periods greater in number than the first plurality of time periods, or a combination thereof.

The OCC resource element-to-port mapper830may be used to apply an OCC to at least one group of resource elements of the plurality of resource elements, as described for example with reference toFIG. 5. The application of the OCC to a group of resource elements may map each resource element in the group of resource elements to a group of ports, in which the group of ports may have been associated with the group of resource elements by the mapping of the plurality of resource elements to the plurality of ports. In some examples, the number of ports in the group of ports may be based at least in part on a length of the OCC.

The reference signal reception manager835may be used to receive one or more reference signals from a second wireless device, on one or more subsets of the plurality of ports, based at least in part on the mapping and the application of the OCC, as described for example with reference toFIGS. 3 and 4. In some examples, each subset of the plurality of resource elements may be distributed in time and frequency over the OFDM time-frequency resource grid.

The reference signal decoder840may be used to decode the reference signal(s) from one or more subsets of the plurality of resource elements based at least in part on the mapping, as described for example with reference toFIGS. 3 and 4.

FIG. 9shows a block diagram900of an apparatus905for use in wireless communication, in accordance with various aspects of the present disclosure. The apparatus905may be an example of aspects of a network access device or apparatus described with reference toFIGS. 1, 2, and 6. The apparatus905may include a receiver910, a wireless communication manager915, and a transmitter920. The apparatus905may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

The receiver910may receive data or control signals or information (i.e., transmissions), some or all of which may be associated with various information channels (e.g., data channels, control channels, etc.). Received signals or information, or measurements performed thereon, may be passed to other components of the apparatus905. The receiver910may include a single antenna or a set of antennas.

The wireless communication manager915may include a template resource element-to-port mapper925, a reference signal mapper930, and a reference signal transmission manager935. The wireless communication manager915may be an example of aspects of a wireless communication manager included in a network access device, as described with reference toFIGS. 1 and 6.

The template resource element-to-port mapper925may be used to identify a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid, as described for example with reference toFIGS. 3 and 4. In some examples, each port of the plurality of ports may be associated with a corresponding RF chain. The template resource element-to-port mapper925may additionally or alternatively be used to map a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping, as described for example with reference toFIGS. 3 and 4. In some examples, the mapping may include mapping each resource element of the plurality of resource elements to a single port of the plurality of ports based at least in part on the template mapping. In some examples, the mapping may include mapping each resource element of the plurality of resource elements to a group of ports of the plurality of ports, based at least in part on an OCC associated with the template mapping, as described with reference toFIG. 5. In some examples, the number of ports in the group of ports may be based at least in part on a length of the OCC. In some examples, the OFDM time-frequency resource grid may include at least one of a second plurality of frequency subcarriers greater in number than the first plurality of frequency subcarriers, a second plurality of time periods greater in number than the first plurality of time periods, or a combination thereof.

The reference signal mapper930may be used to map one or more reference signals to one or more subsets of the plurality of resource elements based at least in part on the mapping of the plurality of resource elements to the plurality of ports, as described for example with reference toFIGS. 3 and 4. In some examples, each subset of the plurality of resource elements may be distributed in time and frequency over the OFDM time-frequency resource grid.

The reference signal transmission manager935may be used to transmit the mapped reference signal(s) to at least a second wireless device, from one or more subsets of the plurality of ports, based at least in part on the mapping of the plurality of resource elements to the plurality of ports and the mapping of the reference signal to the subset of the plurality of resource elements, as described for example with reference toFIGS. 3 and 4.

The transmitter920may transmit data or control signals or information (i.e., transmissions) generated by other components of the apparatus905, some or all of which may be associated with various information channels (e.g., data channels, control channels, etc.). In some examples, the transmitter920may be collocated with the receiver910in a transceiver. For example, the transmitter920and receiver910may be an example of aspects of the transceiver1130or1250described with reference toFIG. 11 or 12. The transmitter920may include a single antenna or a set of antennas.

FIG. 10shows a block diagram1000of a wireless communication manager1015, in accordance with various aspects of the present disclosure. The wireless communication manager1015may be an example of aspects of a wireless communication manager included in a UE, as described with reference toFIGS. 1, 6, and 9. The wireless communication manager1015may include a template resource element-to-port mapper1025, an OCC resource element-to-port mapper1030, a reference signal mapper1035, and a reference signal transmission manager1040. Each of these components may communicate, directly or indirectly, with one another (e.g., via one or more buses). The template resource element-to-port mapper1025, reference signal mapper1035, and reference signal transmission manager1040may be configured similarly to, and may perform the functions of, the template resource element-to-port mapper925, reference signal mapper930, and reference signal transmission manager935described with reference toFIG. 9.

The template resource element-to-port mapper1025may be used to identify a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid, as described for example with reference toFIGS. 3 and 4. In some examples, each port of the plurality of ports may be associated with a corresponding RF chain. The template resource element-to-port mapper1025may additionally or alternatively be used to map a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping, as described for example with reference toFIGS. 3 and 4. In some examples, the OFDM time-frequency resource grid may include at least one of a second plurality of frequency subcarriers greater in number than the first plurality of frequency subcarriers, a second plurality of time periods greater in number than the first plurality of time periods, or a combination thereof.

The OCC resource element-to-port mapper1030may be used to apply an OCC to at least one group of resource elements of the plurality of resource elements, as described for example with reference toFIG. 5. The application of the OCC to a group of resource elements may map each resource element in the group of resource elements to a group of ports, in which the group of ports may have been associated with the group of resource elements by the mapping of the resource elements to the ports. In some examples, the number of ports in the group of ports may be based at least in part on a length of the OCC.

The reference signal mapper1035may be used to map one or more reference signals to one or more subsets of the plurality of resource elements based at least in part on the mapping of the plurality of resource elements to the plurality of ports and the application of the OCC, as described for example with reference toFIGS. 3 and 4. In some examples, each subset of the plurality of resource elements may be distributed in time and frequency over the OFDM time-frequency resource grid.

The reference signal transmission manager1040may be used to transmit the mapped reference signal(s) to at least a second wireless device, from one or more subsets of the plurality of ports, based at least in part on the mapping of the plurality of resource elements to the plurality of ports and the mapping of the reference signal to the subset of the plurality of resource elements, as described for example with reference toFIGS. 3 and 4.

FIG. 11shows a block diagram1100of a UE1115for use in wireless communication, in accordance with various aspects of the present disclosure. The UE1115may be included or be part of a personal computer (e.g., a laptop computer, a netbook computer, a tablet computer, etc.), a cellular telephone, a PDA, a digital video recorder (DVR), an internet appliance, a gaming console, an e-reader, a vehicle, a home appliance, a lighting or alarm control system, etc. The UE1115may, in some examples, have an internal power supply (not shown), such as a small battery, to facilitate mobile operation. In some examples, the UE1115may be an example of aspects of one or more of the UEs described with reference toFIGS. 1 and 2, or aspects of one or more of the apparatuses described with reference toFIGS. 6, 7, and 9. The UE1115may be configured to implement at least some of the UE or apparatus techniques and functions described with reference toFIGS. 1-10.

The UE1115may include a processor1110, a memory1120, at least one transceiver (represented by transceiver(s)1130), antennas1140(e.g., an antenna array), or a wireless communication manager1150. Each of these components may be in communication with each other, directly or indirectly, over one or more buses1135.

The memory1120may include random access memory (RAM) or read-only memory (ROM). The memory1120may store computer-readable, computer-executable code1125containing instructions that are configured to, when executed, cause the processor1110to perform various functions described herein related to wireless communication, including, for example, mapping resource elements to ports based on a template mapping of ports to frequency subcarriers and time periods. Alternatively, the computer-executable code1125may not be directly executable by the processor1110but be configured to cause the UE1115(e.g., when compiled and executed) to perform various of the functions described herein.

The processor1110may include an intelligent hardware device, e.g., a central processing unit (CPU), a microcontroller, an ASIC, etc. The processor1110may process information received through the transceiver(s)1130or information to be sent to the transceiver(s)1130for transmission through the antennas1140. The processor1110may handle, alone or in connection with the wireless communication manager1150, one or more aspects of communicating over (or managing communications over) one or more radio frequency spectrum bands.

The transceiver(s)1130may include a modem configured to modulate packets and provide the modulated packets to the antennas1140for transmission, and to demodulate packets received from the antennas1140. The transceiver(s)1130may, in some examples, be implemented as one or more transmitters and one or more separate receivers. The transceiver(s)1130may support communications in one or more radio frequency spectrum bands. The transceiver(s)1130may be configured to communicate bi-directionally, via the antennas1140, with one or more network access devices or apparatuses, such as one or more of the network access devices described with reference toFIGS. 1 and 2, or one or more of the apparatuses described with reference toFIGS. 6, 7, and 9.

The wireless communication manager1150may be configured to perform or control some or all of the UE or apparatus techniques or functions described with reference toFIGS. 1-10related to wireless communication. The wireless communication manager1150, or portions of it, may include a processor, or some or all of the functions of the wireless communication manager1150may be performed by the processor1110or in connection with the processor1110. In some examples, the wireless communication manager1150may be an example of the wireless communication manager described with reference toFIGS. 1 and 6-10.

FIG. 12shows a block diagram1200of a network access device1205for use in wireless communication, in accordance with various aspects of the present disclosure. In some examples, the network access device1205may be an example of aspects of one or more of the network access devices (e.g., a radio head, a base station, a gNB, or an ANC) described with reference toFIGS. 1 and 2, or aspects of one or more of the apparatuses described with reference toFIGS. 6, 7, and 9. The network access device1205may be configured to implement or facilitate at least some of the network access device techniques and functions described with reference toFIGS. 1-10.

The network access device1205may include a processor1210, a memory1220, at least one transceiver (represented by transceiver(s)1250), antennas1255(e.g., an antenna array), or a wireless communication manager1260. The network access device1205may also include one or more of a network access device communicator1230or a network communicator1240. Each of these components may be in communication with each other, directly or indirectly, over one or more buses1235.

The memory1220may include RAM or ROM. The memory1220may store computer-readable, computer-executable code1225containing instructions that are configured to, when executed, cause the processor1210to perform various functions described herein related to wireless communication, including, for example, mapping resource elements to ports based on a template mapping of ports to frequency subcarriers and time periods. Alternatively, the computer-executable code1225may not be directly executable by the processor1210but be configured to cause the network access device1205(e.g., when compiled and executed) to perform various of the functions described herein.

The processor1210may include an intelligent hardware device, e.g., a CPU, a microcontroller, an ASIC, etc. The processor1210may process information received through the transceiver(s)1250, the network access device communicator1230, or the network communicator1240. The processor1210may also process information to be sent to the transceiver(s)1250for transmission through the antennas1255, or to the network access device communicator1230for transmission to one or more other network access devices (e.g., network access device1205-aand network access device1205-b), or to the network communicator1240for transmission to a core network1245, which may be an example of one or more aspects of the core network130described with reference toFIG. 1. The processor1210may handle, alone or in connection with the wireless communication manager1260, one or more aspects of communicating over (or managing communications over) one or more radio frequency spectrum bands.

The transceiver(s)1250may include a modem configured to modulate packets and provide the modulated packets to the antennas1255for transmission, and to demodulate packets received from the antennas1255. The transceiver(s)1250may, in some examples, be implemented as one or more transmitters and one or more separate receivers. The transceiver(s)1250may support communications in one or more radio frequency spectrum bands. The transceiver(s)1250may be configured to communicate bi-directionally, via the antennas1255, with one or more UEs or apparatuses, such as one or more of the UEs described with reference toFIGS. 1, 2, and 11, or one or more of the apparatuses described with reference toFIGS. 6, 7, and 9. The network access device1205may communicate with the core network1245through the network communicator1240. The network access device1205may also communicate with other network access devices, such as the network access device1205-aand the network access device1205-b, using the network access device communicator1230.

The wireless communication manager1260may be configured to perform or control some or all of the network access device or apparatus techniques or functions described with reference toFIGS. 1-10related to wireless communication. The wireless communication manager1260, or portions of it, may include a processor, or some or all of the functions of the wireless communication manager1260may be performed by the processor1210or in connection with the processor1210. In some examples, the wireless communication manager1260may be an example of the wireless communication manager described with reference toFIGS. 1 and 6-10.

FIG. 13is a flow chart illustrating an example of a method1300for wireless communications at a wireless device (e.g., a first wireless device), in accordance with various aspects of the present disclosure. For clarity, the method1300is described below with reference to aspects of one or more of the UEs described with reference toFIGS. 1, 2, and 11, aspects of one or more of the network access devices described with reference toFIGS. 1, 2, and12, aspects of one or more of the apparatuses described with reference toFIGS. 6 and 7, or aspects of one or more of the wireless communication managers described with reference toFIGS. 1, 6, 7, 8, 11, and 12. In some examples, a first wireless device may execute one or more sets of codes to control the functional elements of the first wireless device to perform the functions described below. Additionally or alternatively, the first wireless device may perform one or more of the functions described below using special-purpose hardware.

At block1305, the method1300may include identifying a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid, as described for example with reference toFIGS. 3 and 4. In some examples, each port of the plurality of ports may be associated with a corresponding RF chain. In certain examples, the operation(s) at block1305may be performed using the template resource element-to-port mapper described with reference toFIGS. 7 and 8.

At block1310, the method1300may include mapping a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping, as described for example with reference toFIGS. 3 and 4. In some examples, the mapping may include mapping each resource element of the plurality of resource elements to a single port of the plurality of ports based at least in part on the template mapping. In some examples, the mapping may include mapping each resource element of the plurality of resource elements to a group of ports of the plurality of ports, based at least in part on an OCC associated with the template mapping, as described with reference toFIG. 5. In some examples, the number of ports in the group of ports may be based at least in part on a length of the OCC. In some examples, the OFDM time-frequency resource grid may include at least one of a second plurality of frequency subcarriers greater in number than the first plurality of frequency subcarriers, a second plurality of time periods greater in number than the first plurality of time periods, or a combination thereof. In certain examples, the operation(s) at block1310may be performed using the template resource element-to-port mapper described with reference toFIGS. 7 and 8.

At block1315, the method1300may include receiving a reference signal from a second wireless device, on a subset of the plurality of ports, based at least in part on the mapping, as described for example with reference toFIGS. 3 and 4. In some examples, the subset of the plurality of resource elements may be distributed in time and frequency over the OFDM time-frequency resource grid. In certain examples, the operation(s) at block1315may be performed using the reference signal reception manager described with reference toFIGS. 7 and 8.

At block1320, the method1300may include decoding the reference signal from a subset of the plurality of resource elements based at least in part on the mapping, as described for example with reference toFIGS. 3 and 4. For example, the decoding may include analog combining of signals associated with the antenna port received at multiple physical antennas to detect the signal energy received via the antenna port. In certain examples, the operation(s) at block1320may be performed using the reference signal decoder described with reference toFIGS. 7 and 8.

FIG. 14is a flow chart illustrating an example of a method1400for wireless communications at a wireless device (e.g., a first wireless device), in accordance with one or more aspects of the present disclosure. For clarity, the method1400is described below with reference to aspects of one or more of the UEs described with reference toFIGS. 1, 2, and 11, aspects of one or more of the network access devices described with reference toFIGS. 1, 2, and12, aspects of one or more of the apparatuses described with reference toFIGS. 6 and 7, or aspects of one or more of the wireless communication managers described with reference toFIGS. 1, 6, 7, 8, 11, and 12. In some examples, a first wireless device may execute one or more sets of codes to control the functional elements of the first wireless device to perform the functions described below. Additionally or alternatively, the first wireless device may perform one or more of the functions described below using special-purpose hardware.

At block1405, the method1400may include identifying a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid, as described for example with reference toFIGS. 3 and 4. In some examples, each port of the plurality of ports may be associated with a corresponding RF chain. In certain examples, the operation(s) at block1405may be performed using the template resource element-to-port mapper described with reference toFIGS. 7 and 8.

At block1410, the method1400may include mapping a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping, as described for example with reference toFIGS. 3 and 4. In some examples, the mapping may include mapping each resource element of the plurality of resource elements to a single port of the plurality of ports based at least in part on the template mapping. In some examples, the mapping may include mapping each resource element of the plurality of resource elements to a group of ports of the plurality of ports, based at least in part on an OCC associated with the template mapping, as described with reference toFIG. 5. In some examples, the number of ports in the group of ports may be based at least in part on a length of the OCC. In some examples, the OFDM time-frequency resource grid may include at least one of a second plurality of frequency subcarriers greater in number than the first plurality of frequency subcarriers, a second plurality of time periods greater in number than the first plurality of time periods, or a combination thereof. In certain examples, the operation(s) at block1410may be performed using the template resource element-to-port mapper described with reference toFIGS. 7 and 8.

At block1415, the method1400may include receiving a plurality of reference signals from a second wireless device, on a plurality of subsets of the plurality of ports, based at least in part on the mapping, as described for example with reference toFIGS. 3 and 4. In some examples, each subset of the plurality of resource elements may be distributed in time and frequency over the OFDM time-frequency resource grid. In some examples, the plurality of reference signals may be received using a receive beam sweep in time and frequency. In certain examples, the operation(s) at block1415may be performed using the reference signal reception manager described with reference toFIGS. 7 and 8.

At block1420, the method1400may include decoding the plurality of reference signals from a plurality of subsets of the plurality of resource elements based at least in part on the mapping, as described for example with reference toFIGS. 3 and 4. In certain examples, the operation(s) at block1420may be performed using the reference signal decoder described with reference toFIGS. 7 and 8.

FIG. 15is a flow chart illustrating an example of a method1500for wireless communications at a wireless device (e.g., a first wireless device), in accordance with one or more aspects of the present disclosure. For clarity, the method1500is described below with reference to aspects of one or more of the UEs described with reference toFIGS. 1, 2, and 11, aspects of one or more of the network access devices described with reference toFIGS. 1, 2, and12, aspects of one or more of the apparatuses described with reference toFIGS. 6 and 7, or aspects of one or more of the wireless communication managers described with reference toFIGS. 1, 6, 7, 8, 11, and 12. In some examples, a first wireless device may execute one or more sets of codes to control the functional elements of the first wireless device to perform the functions described below. Additionally or alternatively, the first wireless device may perform one or more of the functions described below using special-purpose hardware.

At block1505, the method1500may include identifying a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid, as described for example with reference toFIGS. 3 and 4. In some examples, each port of the plurality of ports may be associated with a corresponding RF chain. In certain examples, the operation(s) at block1505may be performed using the template resource element-to-port mapper described with reference toFIGS. 7 and 8.

At block1510, the method1500may include mapping a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping, as described for example with reference toFIGS. 3 and 4. In some examples, the OFDM time-frequency resource grid may include at least one of a second plurality of frequency subcarriers greater in number than the first plurality of frequency subcarriers, a second plurality of time periods greater in number than the first plurality of time periods, or a combination thereof. In certain examples, the operation(s) at block1510may be performed using the template resource element-to-port mapper described with reference toFIGS. 7 and 8.

At block1515, the method1500may include applying an OCC to at least one group of resource elements of the plurality of resource elements, as described for example with reference toFIG. 5. The application of the OCC to a group of resource elements may map each resource element in the group of resource elements to a group of ports, in which the group of ports may have been associated with the group of resource elements by the mapping of the plurality of resource elements to the plurality of ports. In some examples, the number of ports in the group of ports may be based at least in part on a length of the OCC. In certain examples, the operation(s) at block1515may be performed using the OCC resource element-to-port mapper described with reference toFIG. 8.

At block1520, the method1500may include receiving a reference signal from a second wireless device, on a subset of the plurality of ports, based at least in part on the mapping and the application of the OCC, as described for example with reference toFIGS. 3 and 4. In some examples, the subset of the plurality of resource elements may be distributed in time and frequency over the OFDM time-frequency resource grid. In certain examples, the operation(s) at block1520may be performed using the reference signal reception manager described with reference toFIGS. 7 and 8.

At block1525, the method1500may include decoding the reference signal from a subset of the plurality of resource elements based at least in part on the mapping, as described for example with reference toFIGS. 3 and 4. In certain examples, the operation(s) at block1525may be performed using the reference signal decoder described with reference toFIGS. 7 and 8.

FIG. 16is a flow chart illustrating an example of a method1600for wireless communications at a wireless device (e.g., a first wireless device), in accordance with one or more aspects of the present disclosure. For clarity, the method1600is described below with reference to aspects of one or more of the UEs described with reference toFIGS. 1, 2, and 11, aspects of one or more of the network access devices described with reference toFIGS. 1, 2, and12, aspects of one or more of the apparatuses described with reference toFIGS. 6 and 7, or aspects of one or more of the wireless communication managers described with reference toFIGS. 1, 6, 7, 8, 11, and 12. In some examples, a first wireless device may execute one or more sets of codes to control the functional elements of the first wireless device to perform the functions described below. Additionally or alternatively, the first wireless device may perform one or more of the functions described below using special-purpose hardware.

At block1605, the method1600may include identifying a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid, as described for example with reference toFIGS. 3 and 4. In some examples, each port of the plurality of ports may be associated with a corresponding RF chain. In certain examples, the operation(s) at block1605may be performed using the template resource element-to-port mapper described with reference toFIGS. 9 and 10.

At block1610, the method1600may include mapping a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping, as described for example with reference toFIGS. 3 and 4. In some examples, the mapping of the plurality of resource elements to the plurality of ports may include mapping each resource element of the plurality of resource elements to a single port of the plurality of ports based at least in part on the template mapping. In some examples, the mapping of the plurality of resource elements to the plurality of ports may include mapping each resource element of the plurality of resource elements to a group of ports of the plurality of ports, based at least in part on an OCC associated with the template mapping, as described with reference toFIG. 5. In some examples, the number of ports in the group of ports may be based at least in part on a length of the OCC. In some examples, the OFDM time-frequency resource grid may include at least one of a second plurality of frequency subcarriers greater in number than the first plurality of frequency subcarriers, a second plurality of time periods greater in number than the first plurality of time periods, or a combination thereof. In certain examples, the operation(s) at block1610may be performed using the template resource element-to-port mapper described with reference toFIGS. 9 and 10.

At block1615, the method1600may include mapping a reference signal to a subset of the plurality of resource elements based at least in part on the mapping of the plurality of resource elements to the plurality of ports, as described for example with reference toFIGS. 3 and 4. In some examples, the subset of the plurality of resource elements may be distributed in time and frequency over the OFDM time-frequency resource grid. In certain examples, the operation(s) at block1615may be performed using the reference signal mapper described with reference toFIGS. 9 and 10.

At block1620, the method1600may include transmitting the mapped reference signal to at least a second wireless device, from a subset of the plurality of ports, based at least in part on the mapping of the plurality of resource elements to the plurality of ports and the mapping of the reference signal to the subset of the plurality of resource elements, as described for example with reference toFIGS. 3 and 4. In certain examples, the operation(s) at block1620may be performed using the reference signal transmission manager described with reference toFIGS. 9 and 10.

FIG. 17is a flow chart illustrating an example of a method1700for wireless communications at a wireless device (e.g., a first wireless device), in accordance with one or more aspects of the present disclosure. For clarity, the method1700is described below with reference to aspects of one or more of the UEs described with reference toFIGS. 1, 2, and 11, aspects of one or more of the network access devices described with reference toFIGS. 1, 2, and12, aspects of one or more of the apparatuses described with reference toFIGS. 6 and 7, or aspects of one or more of the wireless communication managers described with reference toFIGS. 1, 6, 7, 8, 11, and 12. In some examples, a first wireless device may execute one or more sets of codes to control the functional elements of the first wireless device to perform the functions described below. Additionally or alternatively, the first wireless device may perform one or more of the functions described below using special-purpose hardware.

At block1705, the method1700may include identifying a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid, as described for example with reference toFIGS. 3 and 4. In some examples, each port of the plurality of ports may be associated with a corresponding RF chain. In certain examples, the operation(s) at block1705may be performed using the template resource element-to-port mapper described with reference toFIGS. 9 and 10.

At block1710, the method1700may include mapping a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping, as described for example with reference toFIGS. 3 and 4. In some examples, the mapping of the plurality of resource elements to the plurality of ports may include mapping each resource element of the plurality of resource elements to a single port of the plurality of ports based at least in part on the template mapping. In some examples, the mapping of the plurality of resource elements to the plurality of ports may include mapping each resource element of the plurality of resource elements to a group of ports of the plurality of ports, based at least in part on an OCC associated with the template mapping, as described with reference toFIG. 5. In some examples, the number of ports in the group of ports may be based at least in part on a length of the OCC. In some examples, the OFDM time-frequency resource grid may include at least one of a second plurality of frequency subcarriers greater in number than the first plurality of frequency subcarriers, a second plurality of time periods greater in number than the first plurality of time periods, or a combination thereof. In certain examples, the operation(s) at block1710may be performed using the template resource element-to-port mapper described with reference toFIGS. 9 and 10.

At block1715, the method1700may include mapping a plurality of reference signals to a plurality of subsets of the plurality of resource elements based at least in part on the mapping of the plurality of resource elements to the plurality of ports, as described for example with reference toFIGS. 3 and 4. In some examples, each subset of the plurality of resource elements may be distributed in time and frequency over the OFDM time-frequency resource grid. In certain examples, the operation(s) at block1715may be performed using the reference signal mapper described with reference toFIGS. 9 and 10.

At block1720, the method1700may include transmitting the mapped plurality of reference signals to at least a second wireless device, from a plurality of subsets of the plurality of ports, based at least in part on the mapping of the plurality of resource elements to the plurality of ports and the mapping of the reference signal to the subset of the plurality of resource elements, as described for example with reference toFIGS. 3 and 4. In some examples, the mapped plurality of reference signals may be transmitted using a transmit beam sweep in time and frequency. In certain examples, the operation(s) at block1720may be performed using the reference signal transmission manager described with reference toFIGS. 9 and 10.

FIG. 18is a flow chart illustrating an example of a method1800for wireless communications at a wireless device (e.g., a first wireless device), in accordance with one or more aspects of the present disclosure. For clarity, the method1800is described below with reference to aspects of one or more of the UEs described with reference toFIGS. 1, 2, and 11, aspects of one or more of the network access devices described with reference toFIGS. 1, 2, and12, aspects of one or more of the apparatuses described with reference toFIGS. 6 and 7, or aspects of one or more of the wireless communication managers described with reference toFIGS. 1, 6, 7, 8, 11, and 12. In some examples, a first wireless device may execute one or more sets of codes to control the functional elements of the first wireless device to perform the functions described below. Additionally or alternatively, the first wireless device may perform one or more of the functions described below using special-purpose hardware.

At block1805, the method1800may include identifying a template mapping of a plurality of ports to a first plurality of frequency subcarriers and a first plurality of time periods of a template time-frequency resource grid, as described for example with reference toFIGS. 3 and 4. In some examples, each port of the plurality of ports may be associated with a corresponding RF chain. In certain examples, the operation(s) at block1805may be performed using the template resource element-to-port mapper described with reference toFIGS. 9 and 10.

At block1810, the method1800may include mapping a plurality of resource elements of an OFDM time-frequency resource grid to the plurality of ports based at least in part on the template mapping, as described for example with reference toFIGS. 3 and 4. In some examples, the OFDM time-frequency resource grid may include at least one of a second plurality of frequency subcarriers greater in number than the first plurality of frequency subcarriers, a second plurality of time periods greater in number than the first plurality of time periods, or a combination thereof. In certain examples, the operation(s) at block1810may be performed using the template resource element-to-port mapper described with reference toFIGS. 9 and 10.

At block1815, the method1800may include applying an OCC to at least one group of resource elements of the plurality of resource elements, as described for example with reference toFIG. 5. The application of the OCC to a group of resource elements may map each resource element in the group of resource elements to a group of ports, in which the group of ports may have been associated with the group of resource elements by the mapping of the resource elements to the ports. In some examples, the number of ports in the group of ports may be based at least in part on a length of the OCC. In certain examples, the operation(s) at block1815may be performed using the OCC resource element-to-port mapper described with reference toFIG. 10.

At block1820, the method1800may include mapping a reference signal to a subset of the plurality of resource elements based at least in part on the mapping of the plurality of resource elements to the plurality of ports and the application of the OCC, as described for example with reference toFIGS. 3-5. In some examples, the subset of the plurality of resource elements may be distributed in time and frequency over the OFDM time-frequency resource grid. In certain examples, the operation(s) at block1820may be performed using the reference signal mapper described with reference toFIGS. 9 and 10.

At block1825, the method1800may include transmitting the mapped reference signal to at least a second wireless device, from a subset of the plurality of ports, based at least in part on the mapping of the plurality of resource elements to the plurality of ports and the mapping of the reference signal to the subset of the plurality of resource elements, as described for example with reference toFIGS. 3 and 4. In certain examples, the operation(s) at block1825may be performed using the reference signal transmission manager described with reference toFIGS. 9 and 10.

The methods1300,1400,1500,1600,1700, and1800described with reference toFIGS. 13-18may provide for wireless communication. It should be noted that the methods described inFIGS. 13-18are example implementations of some of the techniques described in the present disclosure, and the operations of the methods may be rearranged, combined with other operations of the same or different method(s), or otherwise modified, such that other implementations are possible. Operations may also be added to the methods.

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope and spirit of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. As used herein, including in the claims, the term “and/or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and/or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination. Also, as used herein, including in the claims, “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of” or “one or more of”) indicates an inclusive list such that, for example, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: A, B, or C” is intended to cover A, B, C, A-B, A-C, B-C, and A-B-C, as well as any combination with multiples of the same element (e.g., A-A A-A-A, A-A-B, A-A-C, A-B-B, A-C-C, B-B, B-B-B, B-B-C, C-C, and C-C-C or any other ordering of A, B, and C). As used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an exemplary step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on.”