Trigger demodulation reference signal clustering

Abstract

Methods, systems, and apparatus for wireless communications are described. A user equipment (UE) may use an indication from a base station to determine whether to bundle or not bundle a demodulation reference signal (e.g., DMRS) for multiple downlink data transmissions. The indication may be transmitted from the base station to the UE via control signaling such as downlink control information (DCI). For example, a bit of the DCI may be used to dynamically indicate a current precoding relative to a previous precoding. For example, this bit may indicate whether the current precoding is the same as the previous precoding (e.g., the UE may bundle the DMRS), or this bit may indicate whether the current precoding is different from the previous precoding (e.g., the UE may not bundle the DMRS).

Description

[0001] Cross-references

[0002] This patent application claims priority to U.S. Patent Application No. 16 / 872,210, filed by MANOLAKOS et al. on May 11, 2020, entitled “TRIGGERING DEMODULATION REFERENCE SIGNAL BUNDLING,” which claims priority to Greek Provisional Patent Application No. 20190100251, filed by MANOLAKOS et al. on June 7, 2019, entitled “TRIGGERING DEMODULATION REFERENCE SIGNAL BUNDLING,” each of which is assigned to its assignee. Background Art

[0003] The following relates generally to wireless communications and, more particularly, to triggering demodulation reference signal bundling.

[0004] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, broadcasting, etc. These systems may be able to support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple access systems include fourth generation (4G) systems (such as long term evolution (LTE) systems, advanced LTE (LTE-A) systems, or LTE-A Pro systems), and fifth generation (5G) systems that may be referred to as new radio (NR) systems. These systems may use various technologies, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multiple access communication system may include several base stations or network access nodes, each of which simultaneously supports the communication of multiple communication devices, which may be referred to as user equipment (UE).

[0005] A wireless multiple access communication system may include UEs that support reference signal resource bundling. Reference signal resource bundling may be used to improve transmission and reception quality by using coherent filtering, which may improve channel estimation. Summary of the invention

[0006] The described technology relates to an improved method, system, device, or apparatus (equipment) that supports triggering demodulation reference signal bundling. In general, the described technology provides a dynamic bundling indication, which notifies a user equipment (UE) to bundle or not bundle a demodulation reference signal (DMRS) of multiple downlink data transmissions via an indication from a base station. The bundling indication can be transmitted from the base station to the UE via control signaling such as downlink control information (DCI). For example, a bit of the DCI can be used to dynamically indicate a current precoding related to a previous precoding. For example, if the bit value of the current DCI matches the previous indication bit (e.g., 0 and 0, or 1 and 1), this may indicate that the current precoding is the same as the previous precoding. In this case, the UE may perform reference signal bundling (e.g., DMRS bundling). If the bit value switches from the previous indication bit (e.g., 0 to 1, or 1 to 0), this may indicate that the current precoding is different from the previous precoding. In this case, the UE may not perform reference signal bundling.

[0007] A method of wireless communication at a UE is described. The method may include: identifying a first bundling indicator associated with at least a first demodulation reference signal for a first downlink data transmission; receiving control signaling indicating a second bundling indicator associated with at least a second demodulation reference signal for a second downlink data transmission subsequent to the first downlink data transmission; and determining a precoding to be applied to the second demodulation reference signal based on a comparison of the first bundling indicator and the second bundling indicator.

[0008] An apparatus for wireless communication at a UE is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions are executable by the processor to cause the apparatus to: identify a first bundling indicator associated with at least a first demodulation reference signal of a first downlink data transmission; receive control signaling indicating a second bundling indicator associated with at least a second demodulation reference signal of a second downlink data transmission subsequent to the first downlink data transmission; and determine a precoding to be applied to the second demodulation reference signal based on a comparison of the first bundling indicator and the second bundling indicator.

[0009] Another apparatus for wireless communication at a UE is described. The apparatus may include means for: identifying a first bundling indicator associated with at least a first demodulation reference signal for a first downlink data transmission; receiving control signaling indicating a second bundling indicator associated with at least a second demodulation reference signal for a second downlink data transmission subsequent to the first downlink data transmission; and determining a precoding to be applied to the second demodulation reference signal based on a comparison of the first bundling indicator and the second bundling indicator.

[0010] A non-transitory computer-readable medium storing code for wireless communication at a UE is described. The code may include instructions executable by a processor for the following operations: identifying a first bundling indicator associated with at least a first demodulation reference signal of a first downlink data transmission; receiving control signaling indicating a second bundling indicator associated with at least a second demodulation reference signal of a second downlink data transmission subsequent to the first downlink data transmission; and determining a precoding to be applied to the second demodulation reference signal based on a comparison of the first bundling indicator and the second bundling indicator.

[0011] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, determining precoding may further include operations, features, apparatus, or instructions for determining, based on the first bundling indicator and the second bundling indicator being the same, that the same precoding as that applied to the first demodulation reference signal is to be applied to the second demodulation reference signal.

[0012] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the same precoding may be determined for a subset of physical resource blocks for a second demodulation reference signal and a subset of physical resource blocks for a first demodulation reference signal based on an overlap of resources used for a first downlink data transmission and a second downlink data transmission.

[0013] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, apparatus, or instructions for: evaluating channel transmission properties of a first downlink data transmission and a second downlink data transmission based on the first bundling indicator and the second bundling indicator being the same; and determining, based on the evaluation of the channel transmission properties of the first downlink data transmission and the channel transmission properties of the second downlink data transmission, that a precoding that is the same as a precoding applied to the first demodulation reference signal is to be applied to the second demodulation reference signal.

[0014] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the channel transmission property includes a port identifier, a channel type, a demodulation reference signal mode, a demodulation reference signal type, a virtual frequency resource allocation, a physical frequency resource allocation, or a combination thereof.

[0015] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, determining that the same precoding as that applied to the first demodulation reference signal is to be applied to the second demodulation reference signal may be based on the fact that channel transmission properties of the first downlink data transmission and the second downlink data transmission are the same.

[0016] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the channel type includes a physical downlink shared channel type.

[0017] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the channel transmission property includes a time unit threshold, and determining that the same precoding as that applied to the first demodulation reference signal is to be applied to the second demodulation reference signal may be based on the second demodulation reference signal being within a time period from the first demodulation reference signal that is less than the time unit threshold.

[0018] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, apparatus, or instructions for: receiving a third demodulation reference signal associated with a first downlink channel for a second UE, the third demodulation reference signal being co-scheduled on the same time-frequency resources and different antenna ports as the first demodulation reference signal associated with a first downlink data transmission on the first downlink channel; and receiving a fourth demodulation reference signal associated with a second downlink channel for the second UE, the fourth demodulation reference signal being co-scheduled on the same time-frequency resources and different antenna ports as the second demodulation reference signal associated with a second downlink data transmission on the second downlink channel.

[0019] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, apparatus, or instructions for determining, based on the first bundling indicator and the second bundling indicator being the same, that a precoding the same as that applied to the third demodulation reference signal is to be applied to the fourth demodulation reference signal.

[0020] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, apparatus, or instructions for receiving a group identifier for a fourth demodulation reference signal, the group identifier indicating that data may not be present in the second downlink channel for the second UE and not present in the first downlink channel for the second UE, and wherein determining that a precoding that is the same as a precoding applied to the third demodulation reference signal is to be applied to the fourth demodulation reference signal can be based on receiving the group identifier.

[0021] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, apparatus, or instructions for determining, based on the first bundling indicator and the second bundling indicator being the same, that a precoding different from the precoding applied to the third demodulation reference signal is to be applied to the fourth demodulation reference signal.

[0022] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, apparatus, or instructions for: identifying a first co-scheduling port bundling indicator associated with a third demodulation reference signal; receiving a second co-scheduling port bundling indicator associated with a fourth demodulation reference signal in control signaling; and determining a precoding to be applied to the fourth demodulation reference signal relative to a precoding applied to the third demodulation reference signal based on a comparison of the first co-scheduling port bundling indicator and the second co-scheduling port bundling indicator.

[0023] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, apparatus, or instructions for determining, based on the second bundling indicator being different from the first bundling indicator, that a precoding different from the precoding applied to the first demodulation reference signal is to be applied to the second demodulation reference signal.

[0024] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the second bundling indicator being different from the first bundling indicator includes a bit value of the second bundling indicator being switched from a bit value of the first bundling indicator.

[0025] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the second demodulation reference signal may include operations, features, apparatus, or instructions for: determining, based on a second bundling indicator, the same precoding to be applied to each semi-persistently scheduled demodulation reference signal in a set of semi-persistently scheduled demodulation reference signals; or determining, based on the second bundling indicator, different precoding to be applied to each semi-persistently scheduled demodulation reference signal in a set of semi-persistently scheduled demodulation reference signals.

[0026] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the control signaling includes a DCI.

[0027] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, a bit field of the DCI indicates a demodulation reference signal port index and a second bundling indicator associated with the demodulation reference signal.

[0028] A method of wireless communication at a base station is described. The method may include transmitting a first bundling indicator associated with at least a first demodulation reference signal for a first downlink data transmission; determining a precoding of a second demodulation reference signal to be applied to a second downlink data transmission subsequent to the first downlink data transmission; and transmitting control signaling indicating the second bundling indicator associated with at least the second demodulation reference signal based on a comparison of the precoding to be applied to the second demodulation reference signal with the precoding applied to the first demodulation reference signal.

[0029] An apparatus for wireless communication at a base station is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions are executable by the processor to cause the apparatus to: transmit a first bundling indicator associated with at least a first demodulation reference signal of a first downlink data transmission; determine a precoding of a second demodulation reference signal to be applied to a second downlink data transmission subsequent to the first downlink data transmission; and transmit control signaling indicating a second bundling indicator associated with at least the second demodulation reference signal based on a comparison of the precoding to be applied to the second demodulation reference signal with the precoding applied to the first demodulation reference signal.

[0030] Another apparatus for wireless communication at a base station is described. The apparatus may include means for transmitting a first bundling indicator associated with at least a first demodulation reference signal for a first downlink data transmission; determining a precoding of a second demodulation reference signal to be applied to a second downlink data transmission subsequent to the first downlink data transmission; and transmitting control signaling indicating the second bundling indicator associated with at least the second demodulation reference signal based on a comparison of the precoding to be applied to the second demodulation reference signal with the precoding applied to the first demodulation reference signal.

[0031] A non-transitory computer-readable medium storing code for wireless communication at a base station is described. The code may include instructions executable by a processor for: transmitting a first bundling indicator associated with at least a first demodulation reference signal of a first downlink data transmission; determining a precoding of a second demodulation reference signal to be applied to a second downlink data transmission subsequent to the first downlink data transmission; and transmitting control signaling indicating a second bundling indicator associated with at least the second demodulation reference signal based on a comparison of the precoding to be applied to the second demodulation reference signal with the precoding applied to the first demodulation reference signal.

[0032] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, apparatus, or instructions for applying the same precoding as applied to the first demodulation reference signal to the second demodulation reference signal, wherein the first bundling indicator may be the same as the second bundling indicator.

[0033] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the same precoding may be applied to a subset of the second demodulation reference signals and a subset of the first demodulation reference signals based on an overlap of resources used for the first downlink data transmission and the second downlink data transmission.

[0034] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the second bundling indicator being the same as the first bundling indicator includes a bit value of the second bundling indicator being the same as a bit value of the first bundling indicator.

[0035] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, apparatus, or instructions for: applying a precoding different from the precoding applied to the first demodulation reference signal to the second demodulation reference signal; and switching a bit value of the second bundling indicator from a bit value of the first bundling indicator.

[0036] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, apparatus, or instructions for: transmitting a third demodulation reference signal associated with a first downlink channel of a second UE, the third demodulation reference signal being co-scheduled on the same time-frequency resources and different antenna ports as a first demodulation reference signal associated with a first downlink data transmission of the first downlink channel; and transmitting a fourth demodulation reference signal associated with a second downlink channel of the second UE, the fourth demodulation reference signal being co-scheduled on the same time-frequency resources and different antenna ports as a second demodulation reference signal associated with a second downlink data transmission of the second downlink channel.

[0037] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, apparatus, or instructions for applying the same precoding as applied to the third demodulation reference signal to the fourth demodulation reference signal, wherein the first bundling indicator may be the same as the second bundling indicator.

[0038] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, apparatus, or instructions for transmitting a group identifier of a fourth demodulation reference signal indicating that data may not be present in the second downlink channel for the second UE and not present in the first downlink channel for the second UE.

[0039] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, apparatus, or instructions for applying a precoding different from a precoding applied to a third demodulation reference signal to a fourth demodulation reference signal, wherein the first bundling indicator may be the same as the second bundling indicator.

[0040] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, apparatus, or instructions for: identifying a first co-scheduling port bundling indicator associated with a third demodulation reference signal; determining a precoding to be applied to a fourth demodulation reference signal relative to a precoding applied to the third demodulation reference signal; and transmitting in control signaling a second co-scheduling port bundling indicator associated with the fourth demodulation reference signal based on the first co-scheduling port bundling indicator.

[0041] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the second demodulation reference signal may include operations, features, apparatus, or instructions for: applying the same precoding to each semi-persistently scheduled demodulation reference signal in a set of semi-persistently scheduled demodulation reference signals; and transmitting a second bundling indicator based on applying the same precoding to each semi-persistently scheduled demodulation reference signal.

[0042] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the second demodulation reference signal may include operations, features, apparatus, or instructions for: applying different precoding to each semi-persistently scheduled demodulation reference signal in a set of semi-persistently scheduled demodulation reference signals; and transmitting a second bundling indicator based on applying different precoding to each semi-persistently scheduled demodulation reference signal.

[0043] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the control signaling includes a DCI.

[0044] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, a bit field of the DCI indicates a demodulation reference signal port index and a second bundling indicator associated with the demodulation reference signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1

[0013] An example of a wireless communication system for supporting triggered demodulation reference signal bundling in accordance with aspects of the present disclosure is illustrated.

[0047] Figure 2

[0013] An example of a wireless communication system for supporting triggered demodulation reference signal bundling in accordance with aspects of the present disclosure is illustrated.

[0048] Figure 3 Examples of resource block configurations supporting triggered demodulation reference signal bundling in accordance with aspects of the present disclosure are illustrated.

[0049] Figure 4 An example of a process flow that supports triggering demodulation reference signal bundling in accordance with aspects of the present disclosure is illustrated.

[0050] Figure 5 and 6 A block diagram of an apparatus supporting triggered demodulation reference signal bundling according to aspects of the present disclosure is shown.

[0051] Figure 7 A block diagram of a communication manager supporting triggered demodulation reference signal bundling in accordance with aspects of the present disclosure is shown.

[0052] Figure 8 A diagram of a system including a device supporting triggered demodulation reference signal bundling according to aspects of the present disclosure is shown.

[0053] Fig. 9 and 10 A block diagram of an apparatus supporting triggered demodulation reference signal bundling according to aspects of the present disclosure is shown.

[0054] Fig.11 A block diagram of a communication manager supporting triggered demodulation reference signal bundling in accordance with aspects of the present disclosure is shown.

[0055] Fig.12 A diagram of a system including a device supporting triggered demodulation reference signal bundling according to aspects of the present disclosure is shown.

[0056] Figures 13 to 19 A flow chart illustrating a method of supporting triggered demodulation reference signal bundling according to aspects of the present disclosure is shown.

[0057] Detailed Description

[0058] In some wireless communication systems, base stations and user equipment (UE) may transmit and receive various reference signals associated with data transmission, such as demodulation reference signals (DMRS). DMRS may include, for example, reference signals communicated together with data transmission (downlink, uplink, or sidelink). DMRS may be communicated using a DMRS pattern, wherein the DMRS pattern may include a set of parameters defining resource allocation of time, frequency, and spectrum resources of the DMRS, a multiplexing scheme and / or antenna port mapping of the DMRS in the frequency, time, and code domains, a scrambling code to be applied to the DMRS, and the like. The UE may use the DMRS to estimate channel characteristics of one or more channels on which the base station and the UE communicate data (e.g., via channel quality measurements). The UE may then use the estimated channel characteristics to perform demodulation and / or decoding on the transmission communicated on the estimated channel.

[0059] In some cases, the UE may bundle the DMRS of one or more received data transmissions (e.g., two subsequent downlink data transmissions) from the base station based on a new bundling indicator (NBI). When the UE performs DMRS bundling, the base station may configure parameters shared across time resource bundles (e.g., transmission time intervals (TTIs)), such as common precoding, to coherently transmit the DMRS in each TTI of each corresponding bundle on the antenna port. Thus, the UE may assume that a common precoder is used to transmit the DMRS across some or all data channels of each bundle. In this way, the UE may coherently filter the received DMRS by jointly processing the DMRS received in each bundle to improve the accuracy of its channel estimation procedure.

[0060] The UE may use the NBI received from the base station to determine the reference signal (e.g., DMRS) to which to bundle or not bundle data transmission. The NBI may be transmitted to the UE via control signaling (e.g., downlink control information (DCI)). For example, a single bit of the DCI may be used to dynamically indicate the relationship of the current precoding to the previous precoding. For example, the bit may indicate whether the current precoding is the same as the previous precoding, or the bit may indicate whether the current precoding is different from the previous precoding. In some cases, the precoding may not change frequently, and using a single bit NBI may allow more efficient processing compared to a bundling indication that includes multiple bits to indicate whether bundling may occur and separately indicates the resources to which the bundling indication may apply (e.g., bundling the next resource without bundling the previous resource).

[0061] In some examples, the DCI bit may indicate that the current precoding (e.g., the precoding of the DMRS received in the downlink transmission associated with the DCI) is the same as the previous precoding (e.g., the precoding of the DMRS received in the previous downlink transmission). However, in some examples, even if the DCI bit indicates that the UE should perform DMRS bundling, the UE may check one or more channel transmission parameters of the first and second data transmissions and perform DMRS bundling based on the channel transmission parameters (which may include channel transmission properties). When one or more channel transmission parameters (e.g., port ID, physical downlink shared channel (PDSCH) type, DMRS mode, and DMRS type) are the same across the first and second downlink data transmissions, the UE may bundle the DMRS of the data transmission (or portions of the data transmission). When the one or more channel transmission parameters are different, the UE may not be expected to bundle the DMRS of the data transmission (or may only bundle the same portions of the data transmissions).

[0062] Other channel conditions or channel transmission parameters may be evaluated at the UE to determine when to bundle the DMRS of a data transmission with the DMRS of a previous data transmission. These channel transmission parameters may include a threshold time period between data channels, a precoding resource group (PRG), a virtual frequency domain allocation, and a physical frequency domain allocation. When one or more channel transmission parameters (e.g., PRG, virtual resource block (VRB), and physical resource block (PRB)) are different, it may not be desirable for the UE to bundle part or all of the DMRS of the data channel.

[0063] The UE may bundle co-scheduled ports based on the NBI. Co-scheduled ports may refer to a pair of different ports scheduled for the same time-frequency resources (e.g., one port may be at a first UE and the other port may be at a second UE). In some cases, the NBI may also be used for semi-persistent scheduling (SPS) transmissions between a base station and a UE.

[0064] Various aspects of the present disclosure are initially described in the context of a wireless communication system. In addition, various aspects of the present disclosure are explained by additional wireless communication systems, data channel configurations, and process flows. Various aspects of the present disclosure are further explained and described by and with reference to apparatus (device) diagrams, system diagrams, and flow charts related to triggering demodulation reference signal bundling.

[0065] Figure 1 An example of a wireless communication system 100 supporting triggered demodulation reference signal bundling according to various aspects of the present disclosure is illustrated. The wireless communication system 100 includes a base station 105, a UE 115, and a core network 130. In some examples, the wireless communication system 100 may be a long term evolution (LTE) network, an advanced LTE (LTE-A) network, an LTE-A Pro network, or a new radio (NR) network. In some cases, the wireless communication system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission-critical) communications, low latency communications, or communications with low-cost and low-complexity devices.

[0066] The base station 105 may communicate wirelessly with the UE 115 via one or more base station antennas. The base station 105 described herein may include or may be referred to by those skilled in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a Node B, an evolved Node B (eNB), a next generation Node B, or a Gigabit Node B (any of which may be referred to as a gNB), a Home Node B, a Home Evolved Node B, or some other suitable terminology. The wireless communication system 100 may include different types of base stations 105 (e.g., macro cell base stations or small cell base stations). The UE 115 described herein may be able to communicate with various types of base stations 105 and network equipment (including macro eNBs, small cell eNBs, gNBs, relay base stations, etc.).

[0067] Each base station 105 may be associated with a particular geographic coverage area 110 in which it supports communications with various UEs 115. Each base station 105 may provide communications coverage for a respective geographic coverage area 110 via a communications link 125, and the communications link 125 between the base station 105 and the UE 115 may utilize one or more carriers. The communications link 125 shown in the wireless communication system 100 may include an uplink transmission from the UE 115 to the base station 105, or a downlink transmission from the base station 105 to the UE 115. Downlink transmissions may also be referred to as forward link transmissions, and uplink transmissions may also be referred to as reverse link transmissions.

[0068] The geographic coverage area 110 of the base station 105 may be divided into sectors that constitute a portion of the geographic coverage area 110, and each sector may be associated with a cellular cell. For example, each base station 105 may provide communication coverage for a macrocellular cell, a small cellular cell, a hotspot, or other types of cellular cells, or various combinations thereof. In some examples, the base station 105 may be mobile and therefore provide communication coverage for a mobile geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, and the overlapping geographic coverage areas 110 associated with different technologies may be supported by the same base station 105 or different base stations 105. The wireless communication system 100 may include, for example, a heterogeneous LTE / LTE-A / LTE-A Pro or NR network, in which different types of base stations 105 provide coverage for various geographic coverage areas 110.

[0069] The term "cell" refers to a logical communication entity used to communicate with base station 105 (e.g., on a carrier), and may be associated with an identifier to distinguish adjacent cells operating via the same or different carriers (e.g., physical cell identifier (PCID), virtual cell identifier (VCID)). In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types that may provide access to different types of devices (e.g., machine type communication (MTC), narrowband Internet of Things (NB-IoT), enhanced mobile broadband (eMBB), or others). In some cases, the term "cell" may refer to a portion (e.g., a sector) of a geographic coverage area 110 on which the logical entity operates.

[0070] Each UE 115 can be dispersed throughout the wireless communication system 100, and each UE 115 can be stationary or mobile. UE 115 can also be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable term, wherein "device" can also be referred to as a unit, a station, a terminal, or a client. UE 115 can also be a personal electronic device, such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, UE 115 can also refer to a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or an MTC device, etc., which can be implemented in various items (such as electrical appliances, vehicles, meters, etc.).

[0071] Some UEs 115, such as MTC or IoT devices, may be low-cost or low-complexity devices and may provide automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC may refer to data communication technology that allows devices to communicate with each other or with a base station 105 without human intervention. In some examples, M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay the information to a central server or application, which may utilize the information or present the information to a person interacting with the program or application. Some UEs 115 may be designed to collect information or implement automated behavior of machines. Examples of applications for MTC devices include: smart metering, inventory monitoring, water level monitoring, equipment monitoring, health care monitoring, field survival monitoring, weather and geographic event monitoring, queue management and tracking, remote security sensing, physical access control, and transaction-based commercial charging.

[0072] Some UEs 115 may be configured to employ a reduced power consumption mode of operation, such as half-duplex communication (e.g., a mode that supports unidirectional communication via transmission or reception but not simultaneous transmission and reception). In some examples, half-duplex communication may be performed with a reduced peak rate. Other power saving techniques for UE 115 include entering a power saving "deep sleep" mode when not engaged in active communications, or operating over a limited bandwidth (e.g., in accordance with narrowband communications). In some cases, UE 115 may be designed to support critical functions (e.g., mission critical functions), and the wireless communication system 100 may be configured to provide ultra-reliable communications for these functions.

[0073] In some cases, UE 115 may also be able to communicate directly with other UE 115 (e.g., using a peer-to-peer (P2P) or device-to-device (D2D) protocol). One or more UEs in a group of UEs 115 utilizing D2D communication may be within the geographic coverage area 110 of the base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of the base station 105, or may not be able to receive transmissions from the base station 105 for other reasons. In some cases, each group of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system, in which each UE 115 transmits to each other UE 115 in the group. In some cases, the base station 105 facilitates the scheduling of resources for D2D communication. In other cases, D2D communication is performed between each UE 115 without involving the base station 105.

[0074] The base stations 105 may communicate with the core network 130 and with each other. For example, the base stations 105 may interface with the core network 130 via a backhaul link 132 (e.g., via S1, N2, N3, or other interfaces). The base stations 105 may communicate with each other directly (e.g., directly between the base stations 105) or indirectly (e.g., via the core network 130) on a backhaul link 134 (e.g., via X2, Xn, or other interfaces).

[0075] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC), which may include at least one mobility management entity (MME), at least one serving gateway (S-GW), and at least one packet data network (PDN) gateway (P-GW). The MME may manage non-access layer (e.g., control plane) functions such as mobility, authentication, and bearer management of UEs 115 served by base stations 105 associated with the EPC. User IP packets may be delivered through the S-GW, which itself may be connected to the P-GW. The P-GW may provide IP address allocation and other functions. The P-GW may be connected to network operator IP services. Operator IP services may include access to the Internet, an intranet, an IP multimedia subsystem (IMS), or packet switched (PS) streaming services.

[0076] At least some network devices (such as base stations 105) may include subcomponents, such as access network entities, which may be examples of access node controllers (ANCs). Each access network entity may communicate with each UE 115 through a number of other access network transport entities, which may be referred to as radio heads, smart radio heads, or transmission / reception points (TRPs). In some configurations, the various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio heads and access network controllers) or merged into a single network device (e.g., base station 105).

[0077] The wireless communication system 100 can operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). In general, the 300 MHz to 3 GHz region is referred to as the ultra-high frequency (UHF) region or decimeter band because the wavelengths are in the range of from about 1 decimeter to 1 meter long. UHF waves can be blocked or redirected by buildings and environmental features. However, these waves can penetrate various structures sufficiently for macro cells to provide services to UEs 115 located indoors. Transmission of UHF waves can be associated with smaller antennas and shorter ranges (e.g., less than 100 km) compared to transmission using lower frequencies and longer waves in the high frequency (HF) or very high frequency (VHF) portion of the spectrum below 300 MHz.

[0078] The wireless communication system 100 may also operate in the Super High Frequency (SHF) region using frequency bands from 3 GHz to 30 GHz, also known as centimeter bands. The SHF region includes frequency bands that may be opportunistically used by devices that may be able to tolerate interference from other users, such as the 5 GHz Industrial, Scientific, and Medical (ISM) band.

[0079] The wireless communication system 100 may also operate in the extremely high frequency (EHF) division of the spectrum (e.g., from 30 GHz to 300 GHz), which is also referred to as the millimeter band. In some examples, the wireless communication system 100 may support millimeter wave (mmW) communications between the UE 115 and the base station 105, and the EHF antenna of the corresponding device may be even smaller and more closely spaced than the UHF antenna. In some cases, this may facilitate the use of antenna arrays within the UE 115. However, the propagation of EHF transmissions may be subject to even greater atmospheric attenuation and shorter range than SHF or UHF transmissions. The technology disclosed herein may be adopted across transmissions using one or more different frequency divisions, and the use of frequency bands specified across these frequency divisions may differ by country or regulatory agency.

[0080] In some cases, the wireless communication system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communication system 100 may employ license assisted access (LAA), LTE unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band (such as a 5GHz ISM band). When operating in an unlicensed radio frequency spectrum band, wireless devices (such as base stations 105 and UE 115) may employ a listen-before-talk (LBT) procedure to ensure that the frequency channel is clear before transmitting data. In some cases, operations in unlicensed bands may be based on carrier aggregation configuration (e.g., LAA) in coordination with component carriers operating in licensed bands. Operations in unlicensed spectrum may include downlink transmissions, uplink transmissions, peer-to-peer transmissions, or a combination of these. Duplexing in unlicensed spectrum may be based on frequency division duplexing (FDD), time division duplexing (TDD), or a combination of the two.

[0081] In some examples, the base station 105 or the UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communication, or beamforming. For example, the wireless communication system 100 may use a transmission scheme between a transmitting device (e.g., the base station 105) and a receiving device (e.g., the UE 115), wherein the transmitting device is equipped with multiple antennas and the receiving device is equipped with one or more antennas. MIMO communication may employ multipath signal propagation to increase spectral efficiency by transmitting or receiving multiple signals via different spatial layers, which may be referred to as spatial multiplexing. For example, the transmitting device may transmit multiple signals via different antennas or different antenna combinations. Similarly, the receiving device may receive multiple signals via different antennas or different antenna combinations. Each of these multiple signals may be referred to as a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams. Different spatial layers may be associated with different antenna ports for channel measurement and reporting. MIMO technology includes single-user MIMO (SU-MIMO), in which multiple spatial layers are transmitted to the same receiving device, and multi-user MIMO (MU-MIMO), in which multiple spatial layers are transmitted to multiple devices.

[0082] Beamforming (which may also be referred to as spatial filtering, directional transmission, or directional reception) is a signal processing technique that may be used at a transmitting device or a receiving device (e.g., a base station 105 or a UE 115) to shape or direct an antenna beam (e.g., a transmit beam or a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining signals communicated via antenna elements of an antenna array so that signals propagating at a particular orientation relative to the antenna array experience constructive interference, while other signals experience destructive interference. Adjustments to signals communicated via antenna elements may include the transmitting device or the receiving device applying a particular amplitude and phase shift to the signal carried via each antenna element associated with the device. Adjustments associated with each antenna element may be defined by a set of beamforming weights associated with a particular orientation (e.g., relative to the antenna array of the transmitting device or the receiving device, or relative to some other orientation).

[0083] In one example, the base station 105 may use multiple antennas or antenna arrays to perform beamforming operations for directional communication with the UE 115. For example, some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted multiple times by the base station 105 in different directions, which may include a signal being transmitted according to different beamforming weight sets associated with different transmission directions. The transmissions in different beam directions may be used (e.g., by the base station 105 or a receiving device, such as the UE 115) to identify the beam direction used by the base station 105 for subsequent transmission and / or reception.

[0084] Some signals, such as data signals associated with a particular recipient device, may be transmitted by base station 105 in a single beam direction (e.g., a direction associated with a recipient device, such as UE 115). In some examples, a beam direction associated with transmissions along a single beam direction may be determined based at least in part on signals transmitted in different beam directions. For example, UE 115 may receive one or more signals transmitted by base station 105 in different directions, and UE 115 may report to base station 105 an indication of the signals received by it with the highest signal quality or other acceptable signal quality. Although these techniques are described with reference to signals transmitted by base station 105 in one or more directions, UE 115 may use similar techniques for transmitting signals multiple times in different directions (e.g., for identifying a beam direction used by UE 115 for subsequent transmission or reception) or for transmitting signals in a single direction (e.g., for transmitting data to a recipient device).

[0085] A receiving device (e.g., UE 115, which may be an example of a mmW receiving device) may try multiple receive beams when receiving various signals (such as synchronization signals, reference signals, beam selection signals, or other control signals) from base station 105. For example, the receiving device may try multiple receive directions by receiving via different antenna subarrays, processing received signals according to different antenna subarrays, receiving according to different receive beamforming weight sets applied to signals received at multiple antenna elements of an antenna array, or processing received signals according to different receive beamforming weight sets applied to signals received at multiple antenna elements of an antenna array, any of which may be referred to as "listening" according to different receive beams or receive directions. In some examples, the receiving device may use a single receive beam to receive along a single beam direction (e.g., when receiving a data signal). The single receive beam may be aligned on a beam direction determined at least in part based on listening according to different receive beam directions (e.g., a beam direction determined to have the highest signal strength, highest signal-to-noise ratio, or other acceptable signal quality based at least in part on listening according to multiple beam directions).

[0086] In some cases, the antennas of a base station 105 or a UE 115 may be located within one or more antenna arrays that may support MIMO operations or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some cases, the antennas or antenna arrays associated with a base station 105 may be located at different geographic locations. A base station 105 may have an antenna array having several rows and columns of antenna ports that the base station 105 may use to support beamforming for communications with a UE 115. Likewise, a UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations.

[0087] In some cases, the wireless communication system 100 may be a packet-based network that operates according to a layered protocol stack. In the user plane, the communication of the bearer or packet data convergence protocol (PDCP) layer may be IP-based. The radio link control (RLC) layer may perform packet segmentation and reassembly to communicate on a logical channel. The media access control (MAC) layer may perform priority handling and multiplex logical channels into transport channels. The MAC layer may also use a hybrid automatic repeat request (HARQ) to provide retransmission of the MAC layer, thereby improving link efficiency. In the control plane, the radio resource control (RRC) protocol layer may provide the establishment, configuration and maintenance of an RRC connection for a radio bearer that supports user plane data between UE115 and base station 105 or core network 130. At the physical layer, transport channels may be mapped to physical channels.

[0088] In some cases, UE 115 and base station 105 may support retransmission of data to increase the likelihood that the data is successfully received. HARQ feedback is a technique that increases the likelihood of correctly receiving data on communication link 125. HARQ may include a combination of error detection (e.g., using cyclic redundancy check (CRC)), forward error correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ can improve the throughput of the MAC layer in poor radio conditions (e.g., signal-to-noise ratio conditions). In some cases, a wireless device may support simultaneous slot HARQ feedback, where the device may provide HARQ feedback in a specific time slot for data received in a previous symbol in the time slot. In other cases, the device may provide HARQ feedback in a subsequent time slot or according to some other time interval.

[0089] The time interval in LTE or NR can be represented by a basic time unit (which may refer to a sampling period T, for example). s =1 / 30,720,000 seconds). The time intervals of the communication resources may be organized according to radio frames each having a duration of 10 milliseconds (ms), where the frame period may be expressed as T f =307,200T s . A radio frame may be identified by a system frame number (SFN) ranging from 0 to 1023. Each frame may include 10 subframes numbered from 0 to 9, and each subframe may have a duration of 1 ms. A subframe may be further divided into 2 slots, each slot having a duration of 0.5 ms, and each slot may contain 6 or 7 modulation symbol periods (e.g., depending on the length of a cyclic prefix prepended to each symbol period). Excluding the cyclic prefix, each symbol period may contain 2048 sampling periods. In some cases, a subframe may be the minimum scheduling unit of the wireless communication system 100 and may be referred to as a transmission time interval (TTI). In other cases, the minimum scheduling unit of the wireless communication system 100 may be shorter than a subframe or may be dynamically selected (e.g., in a burst of a shortened TTI (sTTI) or in a selected component carrier using sTTI).

[0090] In some wireless communication systems, a time slot may be further divided into a plurality of mini-slots containing one or more symbols. In some instances, a symbol of a mini-slot or a mini-slot may be the minimum scheduling unit. For example, each symbol may vary in duration depending on the subcarrier spacing or the operating frequency band. Further, some wireless communication systems may implement time slot aggregation, wherein a plurality of time slots or mini-slots are aggregated together and used for communication between UE 115 and base station 105.

[0091] The term "carrier" refers to a set of radio frequency spectrum resources having a defined physical layer structure for supporting communications on the communication link 125. For example, a carrier of the communication link 125 may include a portion of a radio frequency spectrum band that operates according to a physical layer channel for a given radio access technology. Each physical layer channel may carry user data, control information, or other signaling. A carrier may be associated with a predefined frequency channel (e.g., an Evolved Universal Mobile Telecommunications System Terrestrial Radio Access (E-UTRA) Absolute Radio Frequency Channel Number (EARFCN)) and may be located according to a channel grid for discovery by a UE 115. A carrier may be downlink or uplink (e.g., in FDD mode), or configured to carry downlink communications and uplink communications (e.g., in TDD mode). In some examples, a signal waveform transmitted on a carrier may include multiple subcarriers (e.g., using a multi-carrier modulation (MCM) technique such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)).

[0092] For different radio access technologies (e.g., LTE, LTE-A, LTE-A Pro, NR), the organizational structure of the carrier can be different. For example, the communication on the carrier can be organized according to TTIs or time slots, each of which can include user data and control information or signaling to support decoding of the user data. The carrier can also include dedicated acquisition signaling (e.g., synchronization signals or system information, etc.) and control signaling to coordinate the operation of the carrier. In some examples (e.g., in a carrier aggregation configuration), the carrier may also have acquisition signaling or control signaling to coordinate the operation of other carriers.

[0093] Physical channels may be multiplexed on a carrier according to various techniques. Physical control channels and physical data channels may be multiplexed on a downlink carrier, for example, using a time division multiplexing (TDM) technique, a frequency division multiplexing (FDM) technique, or a hybrid TDM-FDM technique. In some examples, control information transmitted in a physical control channel may be distributed in a cascaded manner between different control regions (e.g., between a common control region or a common search space and one or more UE-specific control regions or UE-specific search spaces).

[0094] A carrier may be associated with a particular bandwidth of the radio frequency spectrum, and in some examples, the carrier bandwidth may be referred to as the "system bandwidth" of the carrier or wireless communication system 100. For example, the carrier bandwidth may be one of several predetermined bandwidths of a carrier for a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 MHz). In some examples, each served UE 115 may be configured to operate on part or all of the carrier bandwidth. In other examples, some UEs 115 may be configured to operate using a narrowband protocol type associated with a predefined portion or range (e.g., a set of subcarriers or RBs) within a carrier (e.g., an "in-band" deployment of a narrowband protocol type).

[0095] In a system using MCM technology, a resource element may include a symbol period (e.g., the duration of a modulation symbol) and a subcarrier, where the symbol period and the subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme). Thus, the more resource elements received by UE 115 and the higher the order of the modulation scheme, the higher the data rate of UE 115 can be. In a MIMO system, wireless communication resources may refer to a combination of radio frequency spectrum resources, time resources, and space resources (e.g., space layers), and the use of multiple space layers may further increase the data rate of communication with UE 115.

[0096] A device (e.g., base station 105 or UE 115) of wireless communication system 100 may have a hardware configuration that supports communication on a particular carrier bandwidth, or may be configurable to support communication on one of a set of carrier bandwidths. In some examples, wireless communication system 100 may include base stations 105 and / or UEs 115 that support simultaneous communication via carriers associated with more than one different carrier bandwidths.

[0097] The wireless communication system 100 may support communication with the UE 115 on multiple cells or carriers, a feature that may be referred to as carrier aggregation or multi-carrier operation. The UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used with both FDD and TDD component carriers.

[0098] In some cases, the wireless communication system 100 may utilize an enhanced component carrier (eCC). An eCC may be characterized by one or more features including a wider carrier or frequency channel bandwidth, a shorter symbol duration, a shorter TTI duration, or a modified control channel configuration. In some cases, an eCC may be associated with a carrier aggregation configuration or a dual connectivity configuration (e.g., when multiple serving cells have suboptimal or non-ideal backhaul links). An eCC may also be configured for use in an unlicensed spectrum or a shared spectrum (e.g., where more than one operator is allowed to use the spectrum). An eCC characterized by a wide carrier bandwidth may include one or more segments that may be utilized by a UE 115 that is not capable of monitoring the entire carrier bandwidth or is otherwise configured to use a limited carrier bandwidth (e.g., to save power).

[0099] In some cases, an eCC may utilize a different symbol duration than other component carriers, which may include using a reduced symbol duration compared to the symbol duration of other component carriers. A shorter symbol duration may be associated with an increased spacing between adjacent subcarriers. A device utilizing an eCC (such as a UE 115 or a base station 105) may transmit a wideband signal (e.g., according to a frequency channel or carrier bandwidth of 20, 40, 60, 80 MHz, etc.) with a reduced symbol duration (e.g., 16.67 microseconds). A TTI in an eCC may include one or more symbol periods. In some cases, the TTI duration (i.e., the number of symbol periods in a TTI) may be variable.

[0100] The wireless communication system 100 may be an NR system that may utilize any combination of licensed, shared, and unlicensed spectrum bands, etc. The flexibility of eCC symbol duration and subcarrier spacing may allow eCC to be used across multiple spectrums. In some examples, NR shared spectrum may improve spectrum utilization and spectrum efficiency, particularly through dynamic vertical (e.g., across frequency domain) and horizontal (e.g., across time domain) sharing of resources.

[0101] The wireless communication system 100 may support DMRS bundling, where the base station 105 may configure common parameters (such as common precoding) to coherently transmit DMRS across time unit (e.g., TTI) bundles or data transmissions. Thus, the UE 115 may assume that a common precoder is used to transmit DMRS across some or all of the multiple data transmissions. In this way, the UE 115 may coherently filter the received DMRS (e.g., using knowledge of the common phase of the DMRS across a bundled TTI) to improve the accuracy of its channel estimation procedure by jointly processing the DMRS received in each bundle.

[0102] In some cases, the UE 115 may use an indication from the base station 105 to determine the reference signal (e.g., DMRS) to bundle or not bundle downlink data transmissions. This indication may be referred to as an NBI and may be transmitted from the base station 105 to the UE 115 via control signaling (e.g., DCI). For example, a single bit of the DCI may be used to dynamically indicate the relationship of the current precoding to the previous precoding. For example, this bit may indicate whether the current precoding is the same as the previous precoding, or this bit may indicate whether the current precoding is different from the previous precoding.

[0103] Figure 2 An example of a wireless communication system 200 that supports triggering demodulation reference signal bundling according to aspects of the present disclosure is illustrated. In some examples, the wireless communication system 100 can implement aspects of the wireless communication system 200. The wireless communication system 200 may include a base station 105-a and a UE 115-a, which may be respectively as described herein with reference to Figure 1 Examples of corresponding base stations 105 and UEs 115 are described.

[0104] Base station 105-a may transmit downlink messages to UE 115-a on resources of carrier 205, and UE 115-a may transmit uplink messages to base station 105-a on resources of carrier 210. In some cases, carriers 205 and 210 may be the same carrier or may be separate carriers. An exemplary downlink data transmission is shown in detail and may include resource block 215 (e.g., a first PDSCH) and resource block 220 (e.g., a second PDSCH) transmitted after resource block 215.

[0105] As described herein, UE 115-a may determine whether to bundle reference signals (e.g., DMRS) for resource blocks 215 and resource blocks 220, which may refer to time domain bundling. Bundling may refer to a receiver (e.g., UE 115-a) assuming that the same precoder has been applied to multiple data transmissions or data channels (e.g., a first PDSCH transmission and subsequent PDSCH transmissions) of different scheduling units, including a DMRS associated with each downlink data transmission on the data channel, and a transmitter (e.g., base station 105-a) may coherently transmit reference signals (e.g., DMRS) associated with the data channel at different times (e.g., TTIs, time slots, or mini-slots) on an antenna port. Additionally, the receiver may jointly process and / or coherently filter different reference signals received with each data channel to improve channel estimation. Bundling may occur over time or across frequency, or both.

[0106] In some cases, UE 115-a may use an indication such as an NBI from base station 105-a to determine whether to bundle reference signals (e.g., DMRS) of resource block 215 and resource block 220. The NBI may be transmitted to UE 115-a via control signaling (e.g., DCI). For example, a single bit of the DCI may be used for the NBI, which may dynamically indicate whether the current precoding of the current DMRS is the same as the previous precoding of the DMRS. In some cases, the precoding includes a precoder or other precoding parameters applied to the DMRS determined by base station 105-a.

[0107] In some examples, the NBI may indicate that the current precoding (e.g., of resource block 220) is the same as the previous precoding (e.g., of resource block 215 that may have been received earlier). In some cases, even if the NBI indicates that bundling of resource blocks 215 and 220 is possible, UE 115-a checks whether one or more channel characteristics of resource blocks 215 and 220 are satisfied to determine whether to perform bundling of the DMRS of resource blocks 215 and 220. In some cases, when the NBI is not switched and a certain transmission parameter is the same between successive downlink data transmissions, UE 115-a may perform partial reference signal resource bundling instead of not bundling any reference signal resources.

[0108] In a first example bundling category, the DMRS is bundled for the entire PDSCH if the NBI indicates bundling and if certain channel transmission parameters of resource blocks 215 and 220 are met. In a second example bundling category, the DMRS may be bundled for the entire PDSCH if the NBI indicates bundling and if resource blocks 215 and 220 are received within a threshold time of each other. In a third example bundling category, portions of resource blocks 215 and 220 are bundled if the NBI indicates bundling and if certain channel transmission parameters of the portions are met or identical.

[0109] An example of the first bundling category may include UE 115-a bundling the DMRS of all resource blocks 215 and 220 when the same base station port ID is used for the DMRS of resource blocks 215 and 220. If different base station port IDs are used for the DMRS of resource blocks 215 and 220, bundling may not occur because resource blocks 215 and resource blocks 220 will be different PDSCH channels.

[0110] Another example of the first bundling category may include: when resource block 215 and resource block 220 are of the same type (e.g., both are type A or both are type B), UE 115-a bundles the DMRS of resource blocks 215 and 220. In some examples, DMRS can be mapped to time slots in two different ways, which can also be referred to as PDSCH mapping types. In some cases, the location of the initial DMRS transmission and the location of any subsequent DMRS transmissions can be determined based on parameters configured by higher layers and the time domain allocation of resources for data transmission (e.g., time domain resource allocation for PDSCH). For example, the location of the initial DMRS transmission can be determined by For example, we can use the parameter l d Obtained from the lookup table The value of d The given parameters may represent the duration including data transmission and DMRS transmission. d The duration given may depend on the mapping type of the data transmission. For example, according to PDSCH mapping type A, l d It can be defined as the duration between the first symbol of a TTI and the last symbol of a TTI (which includes resources allocated for PDSCH). In another example, according to PDSCH mapping type B, l d It may be defined according to the number of symbols including resources allocated for data transmission (eg, symbols including resources scheduled for PDSCH). For example, define l d The duration may start at the sixth symbol (e.g., symbol 5) of the resource block and end at the ninth symbol (e.g., symbol 8) of the resource block, which are symbols spanning time resources allocated for data transmission (e.g., PDSCH communication). Type A and type B PDSCHs may have different DMRS patterns, which may increase the complexity of UE 115-a performing bundling, and therefore, when there are different PDSCH mapping types, it may not be necessary to bundle the DMRS of resource block 215 and resource block 220.

[0111] Another example of the first bundling category may include: when there is a same DMRS pattern with respect to the time-frequency position of the DMRS symbols within the resource blocks 215 and 220, the UE 115-a may bundle the DMRS of the resource blocks 215 and 220. In some cases, the base station 105-a may communicate the DMRS according to a pattern (e.g., a DMRS pattern), which may, for example, specify one or more of the following: a parameter set defining resource allocation of time, frequency, and spectrum resources of the DMRS, a multiplexing scheme and / or antenna port mapping of the DMRS in the frequency domain, time domain, and code domain, a scrambling code to be applied to the DMRS, etc. When the time-frequency position of the DMRS symbols within the resource blocks 215 and 220 has the same DMRS pattern, the UE 115-a may perform bundling on the DMRS of the resource blocks 215 and 220. The same time-frequency DMRS pattern may allow for a lower complexity bundling operation compared to a case where the DMRS time-frequency position of the resource blocks 215 and 220 is different.

[0112] Another example of the first bundling category may include UE 115-a bundling DMRS of resource blocks 215 and 220 when the same DMRS type (e.g., type 1 or 2) is used between resource block 215 and resource block 220. DMRS type 1 may refer to a single-symbol or double-symbol DMRS, where six resource elements may be used per port. DMRS type 2 may refer to a single-symbol or double-symbol DMRS, where four resource elements may be used per port.

[0113] According to the first bundling category, when one or more channel transmission parameters (e.g., port ID, PDSCH type, DMRS mode, and DMRS type) are the same, UE 115-a may bundle the DMRS of resource block 215 and resource block 220 to improve channel estimation. When one or more channel transmission parameters (e.g., port ID, PDSCH type, DMRS mode, and DMRS type) are different, UE 115-a may not bundle the DMRS of resource block 215 and resource block 220. In some examples, UE 115-a may communicate its ability to handle complex bundling to base station 105-a. Base station 105-a may schedule resource blocks 215 and 220 accordingly.

[0114] An example of a second bundling category may include: UE 115-a bundling the DMRS of resource blocks 215 and 220 when resource blocks 215 and 220 are received within a threshold time period between each other. For example, if resource blocks 215 and 220 are within X (e.g., X may be 0, 2, or 5) time slots or symbols, mutual bundling may occur; and if resource blocks 215 and 220 are not within X time slots or symbols, mutual bundling may not occur. For example, when no DMRS is received, UE 115-a may clear the stored DMRS after every X time slots or symbols.

[0115] An example of the third bundling category may include: UE 115-a bundling the DMRS of resource blocks 215 and 220 for the same precoding resource group (PRG) across resource blocks 215 and 220, and different PRGs across resource blocks 215 and 220 may not be bundled. In some cases, when the virtual frequency domain allocations of resource blocks 215 and resource blocks 220 are the same, UE 115-a may perform bundling of the DMRS of resource blocks 215 and 220. For example, the resource allocation types may still be different, but both resource blocks 215 and 220 are mapped to the same virtual resource blocks (VRBs). In yet another example, when the physical frequency domain allocations of resource blocks 215 and resource blocks 220 are the same, UE 115-a may perform bundling of the DMRS of resource blocks 215 and 220. For example, the resource allocation types may still be different, but both resource blocks 215 and 220 are mapped to the same PRBs. UE 115 - a may not bundle a portion or all of the DMRSs of resource block 215 and resource block 220 when one or more channel transmission parameters (eg, PRG, VRB, and PRB) are different.

[0116] Box 225 contains a subset of physical resource blocks (PRBs) in resource block 215 and a subset of PRBs in resource block 220. According to aspects of the present disclosure, bundling of DMRSs for resource block 215 and resource block 220 may occur within the identified subset of PRBs. For example, bundling may occur across PDSCHs on the same frequency, and thus, subsets of PRBs for resource block 215 and resource block 220 that overlap in frequency may be bundled.

[0117] In some cases, bundling of co-scheduled ports may be considered based on the NBI. Co-scheduled ports may refer to a pair of different ports scheduled for the same time-frequency resources (e.g., one port may be at a first UE 115-a and the other port may be at a second UE). In some examples, UE 115-a may perform bundling of DMRS of resource blocks 215 and 220 for a first port and a second port. For example, when UE 115-a is signaled the NBI of its own port, potential co-scheduled ports may or may not be bundled in the same manner as the scheduled ports. In another example, UE 115-a may not perform bundling of DMRS of resource blocks 215 and 220 for a first port and a second port. For example, the NBI applies only to the scheduled ports, and UE 115-a may assume that potential co-scheduled ports are not allocated DMRS that are time-domain bundled across two data channels (e.g., PDSCH). In yet another example, an additional DCI toggle bit may be included in the NBI that may inform the UE 115-a whether it may assume that potential co-scheduled ports may be bundled with those ports from a previous PDSCH transmission. In another example, when a specific code domain multiplexing (CDM) group ID is signaled that does not contain data across resource blocks 215 and 220, and the UE 115-a is informed to perform DMRS bundling across resource blocks 215 and 220, the UE 115-a will assume that the specific CDM group ID contains potential co-scheduled DMRS ports that are bundled in the time domain between resource blocks 215 and 220. Figure 3 These co-scheduling port considerations are discussed in more detail.

[0118] The NBI can be transmitted in a variety of ways using DCI. For example, the DCI bit of the traditional DCI format 1_1 now used for PRG indication can be reused for NBI. In some cases, when the bit is used for PRG or DMRS NBI, the DCI format can be configured semi-statically. Alternatively, the NBI can be encoded in a single bit field jointly with the DMRS port indication table, which may include six bits (e.g., two different bit fields may indicate two different entries in the table, which may indicate the same DM-RS port index and different NBI). For example, the table may include two entries with port indexes (e.g., 0 and 1), where the first entry corresponds to a first NBI (e.g., 0) and the second entry corresponds to a second NBI (e.g., 1).

[0119] The NBI can also be used for semi-persistent scheduling (SPS) transmissions between the base station 105-a and the UE 115-a. For example, for a downlink SPS that is not granted, the NBI can be included in the activation command of the SPS. If the UE 115-a receives an activation command (e.g., via a MAC control element (CE)) with an NBI (e.g., NBI equal to 1 or 0), this will indicate that all data channels (e.g., PDSCH) transmitted within the activated SPS will be bundled unless the channel transmission parameters described herein are not met. In some cases, if there are multiple SPS configurations, a MAC CE command including an NBI can be applied to one or more of the SPS configurations.

[0120] Figure 3 An example of a resource block configuration 300 that supports triggering demodulation reference signal bundling according to various aspects of the present disclosure is illustrated. In some examples, the data channel configuration 300 includes resource blocks 315 and resource blocks 320, which can implement various aspects of resource blocks 215 and 220 of the wireless communication system 200. As described herein, the UE can determine whether to bundle the DMRS of a coherent data transmission or a data channel based on the NBI and additional channel transmission parameters. The NBI can also be used for bundling indication of co-scheduled ports. Co-scheduled ports can refer to two or more different ports scheduled for the same time-frequency resources (for example, one port can be at a first UE and another port can be at a second UE).

[0121] Resource blocks 315 and 320 may include DMRS 305 and 310, respectively. DMRS 305 and 310 are illustrated as type 1 single-symbol DMRS, but aspects described herein may also be applied to different DMRS types, such as type 2, and single or double symbols. DMRS 305 and 310 are shown in symbol period 2 of resource block 315, and DMRS 305 of resource block 315 may include a DMRS consisting of Figure 3 The DMRS 310 of the resource block 320 may also include six resource elements for each port as illustrated in the different modes in FIG. 3 , namely, six resource elements for port 0 and six resource elements for port 2. Figure 3 , namely, six resource elements for port 1 and six resource elements for port 3. Port 0 and port 1 may constitute a first CDM group 325. Port 2 and port 3 may constitute a second CDM group 330, which may be different from CDM group 325.

[0122] In some cases, multi-user multiple input multiple output (MU-MIMO) paired ports may have the same DMRS pattern. The frequency domain PRGs of MU-MIMO paired ports on the same CDM group may be the same. A CDM group indicated as having no data (e.g., data not present) may contain MU-MIMO paired ports, which may allow the UE to estimate channel conditions based on the DMRS in the co-scheduled ports.

[0123] In some cases, bundling of co-scheduled ports (e.g., ports 0 and 1, and ports 2 and 3) may be determined based on the NBI of the scheduling port (e.g., port 0). In some examples, UE 115-a may perform bundling of DMRS of resource blocks 315 and 320 for a first port and a second port (e.g., ports 0 and 1, or ports 2 and 3). For example, when the UE is signaled the NBI of its own port (e.g., port 0), potential co-scheduled ports (e.g., ports 1 and 3, respectively) may be bundled or not bundled in the same manner as the scheduling port. In another example, the UE may not perform bundling of DMRS of resource blocks 315 and 320 for the first port and the second port. In other words, the bundling indication may apply only to the scheduling ports, and the UE may assume that the potential co-scheduled ports are not allocated DMRS that are time-domain bundled across two data channels (e.g., PDSCH).

[0124] In yet another example, an additional DCI toggle bit may be included in the NBI, which may inform the UE whether it may assume that potential co-scheduled ports (e.g., ports 1 and 3) may be bundled with those ports from a previous PDSCH transmission. In another example, when a particular CDM group ID (e.g., group 325 or 330) is signaled to not contain data across resource blocks 315 and 320, the UE may be informed to perform DMRS bundling across resource blocks 315 and 320. The UE will then assume that the particular CDM group ID contains potential co-scheduled DMRS ports that are time-domain bundled between resource blocks 315 and 320.

[0125] Figure 4 An example of a process flow 400 for supporting triggered demodulation reference signal bundling according to aspects of the present disclosure is illustrated. In some examples, the process flow 400 can implement aspects of the wireless communication system 100 and / or 200. The process flow 400 can include a base station 105-b and a UE 115-b, which can be respectively described in reference to Figure 1-3 Examples of corresponding base stations 105 and UEs 115 are described.

[0126] In the following description of process flow 400, operations between UE 115-b and base station 105-b may be communicated in an order different from that shown, or operations performed by base station 105-b and UE 115-b may be performed in a different order or at a different time. Certain operations may also be excluded from process flow 400, or other operations may be added to process flow 400. It is understood that although base station 105-b and UE 115-b are shown as performing several operations of process flow 400, any wireless device may perform the operations shown.

[0127] At 405, the base station 105-b may transmit to the UE 115-b a bundling indicator (e.g., an NBI via a DCI) associated with a first demodulation reference signal for a first downlink data transmission (e.g., the data transmission transmitted at 410). In some cases, the NBI may include bits of the DCI that indicate a precoding of the first demodulation reference signal for the first downlink data transmission related to a previous precoding of a previous data channel (e.g., a previous PDSCH).

[0128] At 410, the base station 105-b may transmit a data transmission (e.g., a PDSCH) to the UE 115-b. Figure 2-3 As described, a reference signal (eg, DMRS) for the data transmission may be precoded based on the NBI transmitted at 405. The bundling indicator may be transmitted in the same transmission as the first data transmission (eg, as part of control signaling associated with the data transmission).

[0129] At 415, UE 115-b may identify an NBI associated with the first demodulation reference signal for the first downlink data transmission. For example, UE 115-b may store or recall the NBI received at 405.

[0130] At 420, the base station 105-b may determine a precoding for a second demodulation reference signal to be applied to a second downlink data transmission (e.g., the data transmission transmitted at 440), which may follow the first downlink data transmission (e.g., the data transmission transmitted at 410). Whether the precoding is the same as or different from the previous precoding may depend on the state of the channel or other channel characteristics.

[0131] At 425, the base station 105-b may compare the precoding of the second demodulation reference signal to be applied for the second downlink data transmission with the precoding of the first demodulation reference signal applied for the first downlink data transmission.

[0132] At 430, when a precoding different from the precoding applied to the first demodulation reference signal for the first downlink data transmission is applied to the second demodulation reference signal for the second downlink data transmission, the base station 105-b may optionally switch from a bit value of the first NBI to a bit value of the second NBI (e.g., from 1 to 0 or from 0 to 1). In the case where the precoding is the same between the first and second downlink data transmissions, the DCI bits of the NBI may not be switched.

[0133] At 435, the base station 105-b may transmit an NBI associated with the second demodulation reference signal for the second downlink data transmission to the UE 115-b (e.g., via a DCI). In some cases, the NBI may include bits of the DCI that indicate a precoding of the second demodulation reference signal for the second downlink data transmission relative to a previous precoding of a previous data transmission (e.g., a previous PDSCH, such as the data transmission transmitted at 410).

[0134] At 440, base station 105-b may transmit a data transmission (e.g., a PDSCH) to UE 115-b, which may be precoded according to the NBI transmitted at 435. The bundling indicator may be transmitted in the same transmission as the second data transmission (e.g., as part of control signaling associated with the data transmission).

[0135] At 445 , UE 115 - b may compare the NBI received at 405 with the NBI received at 435 to determine whether the indicator has been switched.

[0136] At 450, UE 115-b may determine a precoder to be applied to the second demodulation reference signal based at least in part on the comparison of the first NBI and the second NBI at 445. For example, if the indicator is not toggled, the same precoder as the previous data transmission associated with the first NBI may be applied. In another example, if the indicator is toggled, a different precoder than the previous data transmission associated with the first NBI may be applied.

[0137] At 455, UE 115-b may optionally bundle (e.g., apply the same precoder) a second demodulation reference signal for the second downlink data transmission with the first demodulation reference signal for the first downlink data transmission based at least in part on the first NBI and the second NBI being the same. In some cases, the same precoding is applied to a subset of physical resource blocks for the second demodulation reference signal and a subset of physical resource blocks for the first demodulation reference signal based at least in part on an overlap of resources used for the first downlink data transmission and the second downlink data transmission.

[0138] Figure 5A block diagram 500 of a device 505 supporting triggered demodulation reference signal bundling according to aspects of the present disclosure is shown. The device 505 may be an example of aspects of a UE 115 as described herein. The device 505 may include a receiver 510, a communication manager 515, and a transmitter 520. The device 505 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0139] The receiver 510 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to triggering demodulation reference signal bundling, etc.). The information may be passed to other components of the device 505. The receiver 510 may be a reference Figure 8 Examples of aspects of the described transceiver 820. The receiver 510 may utilize a single antenna or a collection of antennas.

[0140] The communication manager 515 may identify a first bundling indicator associated with a first demodulation reference signal for a first downlink data transmission; receive control signaling indicating a second bundling indicator associated with a second demodulation reference signal for a second downlink data transmission subsequent to the first downlink data transmission; and determine a precoding to be applied to the second demodulation reference signal based on a comparison of the first bundling indicator and the second bundling indicator. The communication manager 515 may be an example of aspects of the communication manager 810 described herein.

[0141] The communication manager 515 or its subcomponents may be implemented in hardware, in code (e.g., software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 515 or its subcomponents may be performed by a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device designed to perform the functions described in the present disclosure, discrete gate or transistor logic, discrete hardware components, or any combination thereof.

[0142] The communication manager 515 or its subcomponents may be physically located at various locations, including being distributed such that portions of functionality are implemented by one or more physical components at different physical locations. In some examples, according to various aspects of the present disclosure, the communication manager 515 or its subcomponents may be separate and distinct components. In some examples, according to various aspects of the present disclosure, the communication manager 515 or its subcomponents may be combined with one or more other hardware components (including, but not limited to, input / output (I / O) components, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof).

[0143] The transmitter 520 may transmit signals generated by other components of the device 505. In some examples, the transmitter 520 may be co-located with the receiver 510 in a transceiver module. For example, the transmitter 520 may be a reference Figure 8 Examples of aspects of the described transceiver 820. The transmitter 520 may utilize a single antenna or a collection of antennas.

[0144] Figure 6 A block diagram 600 of a device 605 supporting triggered demodulation reference signal bundling according to aspects of the present disclosure is shown. The device 605 may be an example of aspects of the device 505 or UE 115 as described herein. The device 605 may include a receiver 610, a communication manager 615, and a transmitter 635. The device 605 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0145] The receiver 610 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to triggering demodulation reference signal bundling, etc.). The information may be passed to other components of the device 605. The receiver 610 may be a reference Figure 8 Examples of aspects of the described transceiver 820. The receiver 610 may utilize a single antenna or a collection of antennas.

[0146] The communication manager 615 may be an example of aspects of the communication manager 515 as described herein. The communication manager 615 may include a bundling indicator memory 620, a control signal component 625, and a precoder 630. The communication manager 615 may be an example of aspects of the communication manager 810 as described herein. The actions performed by the communication manager 615 as described herein may be implemented to achieve one or more potential advantages. An implementation may allow the UE 115 to reduce the computational complexity and lower signaling or information overhead of DMRS bundling by avoiding having to provide detailed bundling information, and instead may provide an indication of the previous precoding (e.g., in the form of a single bit that is toggled).

[0147] The bundling indicator memory 620 may identify a first bundling indicator associated with a first demodulation reference signal for a first downlink data transmission.

[0148] The control signal component 625 may receive control signaling indicating a second bundling indicator associated with a second demodulation reference signal for a second downlink data transmission subsequent to the first downlink data transmission.

[0149] The precoder 630 may determine precoding to be applied to the second demodulation reference signal based on a comparison of the first bundling indicator and the second bundling indicator.

[0150] The transmitter 635 can transmit signals generated by other components of the device 605. In some examples, the transmitter 635 can be co-located with the receiver 610 in a transceiver module. For example, the transmitter 635 can be a reference Figure 8 Examples of aspects of the described transceiver 820. The transmitter 635 may utilize a single antenna or a collection of antennas.

[0151] Figure 7 A block diagram 700 of a communication manager 705 supporting triggered demodulation reference signal bundling in accordance with aspects of the present disclosure is shown. The communication manager 705 may be an example of aspects of the communication manager 515, the communication manager 615, or the communication manager 810 described herein. The communication manager 705 may include a bundling indicator memory 710, a control signal component 715, a precoder 720, a channel characteristic estimator 725, a co-scheduling port component 730, a group data identifier 735, and a semi-persistent signal controller 740. Each of these modules may communicate directly or indirectly with each other (e.g., via one or more buses).

[0152] The bundling indicator memory 710 may identify a first bundling indicator associated with a first demodulation reference signal for a first downlink data transmission. In some cases, the second bundling indicator being different from the first bundling indicator includes: a bit value of the second bundling indicator being switched from a bit value of the first bundling indicator.

[0153] The control signal component 715 may receive control signaling indicating a second bundling indicator associated with a second demodulation reference signal for a second downlink data transmission subsequent to the first downlink data transmission. In some cases, the control signaling includes a DCI. In some cases, a bit field of the DCI indicates both a demodulation reference signal port index and a second bundling indicator associated with the demodulation reference signal.

[0154] The precoder 720 may determine the precoding to be applied to the second demodulation reference signal based on a comparison of the first bundling indicator and the second bundling indicator. In some examples, the precoder 720 may determine that the same precoding as the precoding applied to the first demodulation reference signal is to be used for the second demodulation reference signal based on the first bundling indicator and the second bundling indicator being the same. In some examples, the precoder 720 may determine that the same precoding as the precoding applied to the first demodulation reference signal is to be used for the second demodulation reference signal based on an evaluation of the channel transmission properties of the first downlink data transmission and the channel transmission properties of the second downlink data transmission. In some examples, the precoder 720 may determine that the same precoding as the precoding applied to the third demodulation reference signal is to be used for the fourth demodulation reference signal based on the first bundling indicator and the second bundling indicator being the same.

[0155] In some examples, the precoder 720 may determine that a precoding different from the precoding applied to the third demodulation reference signal is to be used for the fourth demodulation reference signal based on the first bundling indicator and the second bundling indicator being the same. In some examples, the precoder 720 may determine the precoding to be applied to the fourth demodulation reference signal relative to the precoding applied to the third demodulation reference signal based on a comparison of the first co-scheduling port bundling indicator and the second co-scheduling port bundling indicator. In some examples, the precoder 720 may determine that a precoding different from the precoding applied to the first demodulation reference signal is to be used for the second demodulation reference signal based on the second bundling indicator being different from the first bundling indicator.

[0156] In some cases, the same precoding is applied to a subset of physical resource blocks for the second demodulation reference signal and a subset of physical resource blocks for the first demodulation reference signal based on an overlap of resources used for the first downlink data transmission and the second downlink data transmission. In some cases, determining that the same precoding as the precoding applied to the first demodulation reference signal is to be used for the second demodulation reference signal is based on the channel transmission properties of the first downlink data transmission and the second downlink data transmission being the same.

[0157] The channel characteristic evaluator 725 may evaluate channel transmission properties of the first downlink data transmission and the second downlink data transmission based on the first bundling indicator and the second bundling indicator being the same.

[0158] In some cases, the channel transmission property includes a port identifier, a channel type, a demodulation reference signal mode, a demodulation reference signal type, a virtual frequency resource allocation, a physical frequency resource allocation, or a combination thereof. In some cases, the channel type includes a physical downlink shared channel type. In some cases, the channel transmission property includes a time unit threshold, and determining that the same precoding as applied to the first demodulation reference signal is to be used for the second demodulation reference signal is based on the second demodulation reference signal being within a time period less than the time unit threshold from the first demodulation reference signal.

[0159] The co-scheduling port component 730 can receive a third demodulation reference signal associated with a first downlink channel for a second UE, and the third demodulation reference signal is co-scheduled on the same time-frequency resources and different antenna ports as the first demodulation reference signal associated with the first downlink data transmission of the first downlink channel.

[0160] In some examples, the co-scheduling port component 730 may receive a fourth demodulation reference signal associated with a second downlink channel for the second UE, which is co-scheduled on the same time-frequency resources and different antenna port as the second demodulation reference signal associated with the second downlink data transmission of the second downlink channel.

[0161] In some examples, the co-scheduling port component 730 may identify a first co-scheduling port bundling indicator associated with the third demodulation reference signal. In some examples, the co-scheduling port component 730 may receive a second co-scheduling port bundling indicator associated with the fourth demodulation reference signal in the control signaling.

[0162] The group data identifier 735 may receive a group identifier of a fourth demodulation reference signal, the group identifier indicating that data is not present in the second downlink channel for the second UE and is not present in the first downlink channel for the second UE, and wherein it is determined that the same precoding as that applied to the third demodulation reference signal is to be used for reception of the fourth demodulation reference signal based on the group identifier.

[0163] The semi-persistent signal controller 740 may determine, based on the second bundling indicator, the same precoding to be used for each semi-persistently scheduled demodulation reference signal in the semi-persistently scheduled demodulation reference signal set.

[0164] In some examples, the semi-persistent signal controller 740 may determine, based on the second bundling indicator, different precoding to be used for each semi-persistently scheduled demodulation reference signal in the set of semi-persistently scheduled demodulation reference signals.

[0165] Based on configuring the NBI to provide information about the previous NBI (which allows for reducing the information that may need to be transmitted to the UE for the purpose of bundling indication), the processor of the UE 115 (e.g., controlling the receiver, transmitter, or transceiver) can efficiently determine whether the DMRS of the subsequent PDSCH should be bundled. In this way, when the NBI is received, the processor can prepare the bundled DMRS more efficiently by reducing bundling considerations.

[0166] Figure 8 A diagram of a system 800 including a device 805 supporting triggered demodulation reference signal bundling according to aspects of the present disclosure is shown. The device 805 may be an example of a device 505, a device 605, or a UE 115 as described herein or include a component of the device 505, a device 605, or a UE 115. The device 805 may include components for two-way voice and data communications, including components for transmitting and receiving communications, including a communication manager 810, an I / O controller 815, a transceiver 820, an antenna 825, a memory 830, and a processor 840. These components may be in electronic communication via one or more buses (e.g., a bus 845).

[0167] The communication manager 810 may identify a first bundling indicator associated with a first demodulation reference signal for a first downlink data transmission; receive control signaling indicating a second bundling indicator associated with a second demodulation reference signal for a second downlink data transmission subsequent to the first downlink data transmission; and determine a precoding to be applied to the second demodulation reference signal based on a comparison of the first bundling indicator and the second bundling indicator.

[0168] I / O controller 815 can manage input and output signals of device 805. I / O controller 815 can also manage peripheral devices that are not integrated into device 805. In some cases, I / O controller 815 can represent a physical connection or port to an external peripheral device. In some cases, I / O controller 815 can utilize an operating system, such as Or another known operating system. In other cases, I / O controller 815 may represent or interact with a modem, keyboard, mouse, touch screen, or similar device. In some cases, I / O controller 815 may be implemented as part of a processor. In some cases, a user may interact with device 805 via I / O controller 815 or via hardware components controlled by I / O controller 815.

[0169] The transceiver 820 may communicate bidirectionally via one or more antennas, wired or wireless links, as described herein. For example, the transceiver 820 may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. The transceiver 820 may also include a modem to modulate packets and provide the modulated packets to an antenna for transmission, and demodulate packets received from an antenna.

[0170] In some cases, a wireless device may include a single antenna 825. However, in some cases, the device may have more than one antenna 825, which may be capable of transmitting or receiving multiple wireless transmissions concurrently.

[0171] The memory 830 may include RAM and ROM. The memory 830 may store computer-readable, computer-executable code 835 including instructions that, when executed, cause the processor to perform the various functions described herein. In some cases, the memory 830 may include, among other things, a basic input / output system (BIOS) that may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0172] The processor 840 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor 840 may be configured to operate a memory array using a memory controller. In other cases, the memory controller may be integrated into the processor 840. The processor 840 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 830) to cause the device 805 to perform various functions (e.g., support functions or tasks of triggering demodulation reference signal bundling).

[0173] The code 835 may include instructions for implementing various aspects of the present disclosure, including instructions for supporting wireless communications. The code 835 may be stored in a non-transitory computer-readable medium, such as a system memory or other type of memory. In some cases, the code 835 may not be directly executed by the processor 840, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0174] Fig. 9 A block diagram 900 of a device 905 supporting triggered demodulation reference signal bundling according to aspects of the present disclosure is shown. The device 905 may be an example of aspects of a base station 105 as described herein. The device 905 may include a receiver 910, a communication manager 915, and a transmitter 920. The device 905 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0175] The receiver 910 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to triggering demodulation reference signal bundling, etc.). The information may be passed to other components of the device 905. The receiver 910 may be a reference Fig.12 Examples of various aspects of the described transceiver 1220. The receiver 910 may utilize a single antenna or a collection of antennas.

[0176] The communication manager 915 may transmit a first bundling indicator associated with a first demodulation reference signal for a first downlink data transmission; determine a precoding of a second demodulation reference signal to be applied to a second downlink data transmission subsequent to the first downlink data transmission; and transmit control signaling indicating a second bundling indicator associated with the second demodulation reference signal based on a comparison of the precoding to be applied to the second demodulation reference signal and the precoding applied to the first demodulation reference signal. The communication manager 915 may be an example of aspects of the communication manager 1210 described herein.

[0177] The communication manager 915 or its subcomponents may be implemented in hardware, in code (e.g., software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 915 or its subcomponents may be performed by a general purpose processor, a DSP, an application specific integrated circuit (ASIC), an FPGA or other programmable logic device designed to perform the functions described in the present disclosure, discrete gate or transistor logic, discrete hardware components, or any combination thereof.

[0178] The communication manager 915 or its subcomponents may be physically located at various locations, including being distributed such that portions of functionality are implemented by one or more physical components at different physical locations. In some examples, according to various aspects of the present disclosure, the communication manager 915 or its subcomponents may be separate and distinct components. In some examples, according to various aspects of the present disclosure, the communication manager 915 or its subcomponents may be combined with one or more other hardware components (including, but not limited to, input / output (I / O) components, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof).

[0179] The transmitter 920 may transmit signals generated by other components of the device 905. In some examples, the transmitter 920 may be co-located with the receiver 910 in a transceiver module. For example, the transmitter 920 may be a reference Fig.12 Examples of various aspects of the described transceiver 1220. The transmitter 920 may utilize a single antenna or a collection of antennas.

[0180] Fig.10A block diagram 1000 of a device 1005 supporting triggered demodulation reference signal bundling according to aspects of the present disclosure is shown. The device 1005 may be an example of aspects of the device 905 or base station 105 as described herein. The device 1005 may include a receiver 1010, a communication manager 1015, and a transmitter 1035. The device 1005 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0181] The receiver 1010 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to triggering demodulation reference signal bundling, etc.). The information may be passed to other components of the device 1005. The receiver 1010 may be a reference Fig.12 Examples of various aspects of the described transceiver 1220. The receiver 1010 may utilize a single antenna or a collection of antennas.

[0182] The communication manager 1015 may be an example of aspects of the communication manager 915 as described herein. The communication manager 1015 may include a bundle manager 1020, a precoder 1025, and a control signal component 1030. The communication manager 1015 may be an example of aspects of the communication manager 1210 as described herein.

[0183] The bundle manager 1020 may transmit a first bundling indicator associated with a first demodulation reference signal for a first downlink data transmission.

[0184] The precoder 1025 may determine precoding of a second demodulation reference signal to be applied to a second downlink data transmission following the first downlink data transmission.

[0185] The control signal component 1030 may transmit control signaling indicating a second bundling indicator associated with the second demodulation reference signal based on a comparison of the precoding to be applied to the second demodulation reference signal and the precoding applied to the first demodulation reference signal.

[0186] The transmitter 1035 can transmit signals generated by other components of the device 1005. In some examples, the transmitter 1035 can be co-located with the receiver 1010 in a transceiver module. For example, the transmitter 1035 can be a reference Fig.12 Examples of various aspects of the described transceiver 1220. The transmitter 1035 may utilize a single antenna or a collection of antennas.

[0187] Fig.11A block diagram 1100 of a communication manager 1105 supporting triggered demodulation reference signal bundling according to aspects of the present disclosure is shown. The communication manager 1105 may be an example of aspects of the communication manager 915, the communication manager 1015, or the communication manager 1210 described herein. The communication manager 1105 may include a bundle manager 1110, a precoder 1115, a control signal component 1120, an indicator switch 1125, a co-scheduled port component 1130, a group data identifier 1135, and a semi-persistent signal controller 1140. Each of these modules may communicate directly or indirectly with each other (e.g., via one or more buses).

[0188] The bundle manager 1110 may transmit a first bundling indicator associated with a first demodulation reference signal for a first downlink data transmission.

[0189] The precoder 1115 may determine a precoding of a second demodulation reference signal to be applied to a second downlink data transmission following the first downlink data transmission. In some examples, the precoder 1115 may apply the same precoding as applied to the first demodulation reference signal to the second demodulation reference signal, wherein the first bundling indicator is the same as the second bundling indicator. In some examples, the precoder 1115 may apply a different precoding than the precoding applied to the first demodulation reference signal to the second demodulation reference signal.

[0190] In some examples, the precoder 1115 may apply the same precoding as applied to the third demodulation reference signal to the fourth demodulation reference signal, wherein the first bundling indicator is the same as the second bundling indicator. In some examples, the precoder 1115 may apply a different precoding than the precoding applied to the third demodulation reference signal to the fourth demodulation reference signal, wherein the first bundling indicator is the same as the second bundling indicator. In some examples, the precoder 1115 may determine the precoding to be applied to the fourth demodulation reference signal relative to the precoding applied to the third demodulation reference signal. In some examples, the precoder 1115 may apply the same precoding to each semi-persistently scheduled demodulation reference signal in the set of semi-persistently scheduled demodulation reference signals. In some examples, the precoder 1115 may apply a different precoding to each semi-persistently scheduled demodulation reference signal in the set of semi-persistently scheduled demodulation reference signals.

[0191] In some cases, based on an overlap of resources used for the first downlink data transmission and the second downlink data transmission, the same precoding is applied to a subset of the second demodulation reference signal and a subset of the first demodulation reference signal. In some cases, the second bundling indicator is the same as the first bundling indicator including a bit value of the second bundling indicator being the same as a bit value of the first bundling indicator.

[0192] The control signal component 1120 may transmit control signaling indicating a second bundling indicator associated with the second demodulation reference signal based on a comparison of the precoding to be applied to the second demodulation reference signal and the precoding applied to the first demodulation reference signal.

[0193] In some cases, the control signaling includes a DCI.In some cases, a bit field of the DCI indicates both a demodulation reference signal port index and a second bundling indicator associated with the demodulation reference signal.

[0194] The indicator switch 1125 may switch a bit value of the first bundling indicator to a bit value of the second bundling indicator.

[0195] The co-scheduling port component 1130 can receive a third demodulation reference signal associated with a first downlink channel for a second UE, and the third demodulation reference signal is co-scheduled on the same time-frequency resources and different antenna ports as the first demodulation reference signal associated with the first downlink data transmission of the first downlink channel.

[0196] In some examples, the co-scheduling port component 1130 may transmit a fourth demodulation reference signal associated with a second downlink channel of a second UE, which is co-scheduled on the same time-frequency resources and different antenna port as a second demodulation reference signal associated with a second downlink data transmission of the second downlink channel.

[0197] In some examples, the co-scheduling port component 1130 may identify a first co-scheduling port bundling indicator associated with the third demodulation reference signal. In some examples, the co-scheduling port component 1130 may transmit a second co-scheduling port bundling indicator associated with the fourth demodulation reference signal in control signaling based on the first co-scheduling port bundling indicator.

[0198] The group data identifier 1135 may transmit a group identifier of the fourth demodulation reference signal, the group identifier indicating that data is not present in the second downlink channel for the second UE and is not present in the first downlink channel for the second UE.

[0199] The semi-persistent signal controller 1140 may transmit the second bundling indicator based on applying the same precoding to each semi-persistently scheduled demodulation reference signal. In some examples, the semi-persistent signal controller 1140 may transmit the second bundling indicator based on applying different precoding to each semi-persistently scheduled demodulation reference signal.

[0200] Fig.12A diagram of a system 1200 including a device 1205 supporting triggered demodulation reference signal bundling according to aspects of the present disclosure is shown. The device 1205 may be an example of a device 905, a device 1005, or a base station 105 as described herein or include components of the above devices. The device 1205 may include components for two-way voice and data communications, including components for transmitting and receiving communications, including a communication manager 1210, a network communication manager 1215, a transceiver 1220, an antenna 1225, a memory 1230, a processor 1240, and an inter-station communication manager 1245. These components may be in electronic communication via one or more buses (e.g., bus 1250).

[0201] The communication manager 1210 may transmit a first bundling indicator associated with a first demodulation reference signal for a first downlink data transmission; determine a precoding of a second demodulation reference signal to be applied to a second downlink data transmission following the first downlink data transmission; and transmit control signaling indicating a second bundling indicator associated with the second demodulation reference signal based on a comparison of the precoding to be applied to the second demodulation reference signal with the precoding applied to the first demodulation reference signal.

[0202] The network communications manager 1215 may manage communications with the core network (eg, via one or more wired backhaul links). For example, the network communications manager 1215 may manage the delivery of data communications for client devices, such as one or more UEs 115.

[0203] The transceiver 1220 may communicate bidirectionally via one or more antennas, wired or wireless links, as described herein. For example, the transceiver 1220 may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. The transceiver 1220 may also include a modem to modulate packets and provide the modulated packets to an antenna for transmission, and demodulate packets received from an antenna.

[0204] In some cases, a wireless device may include a single antenna 1225. However, in some cases, the device may have more than one antenna 1225, which may be capable of transmitting or receiving multiple wireless transmissions concurrently.

[0205] The memory 1230 may include RAM, ROM, or a combination thereof. The memory 1230 may store computer readable code 1235 including instructions that, when executed by a processor (e.g., processor 1240), cause the device to perform various functions described herein. In some cases, the memory 1230 may include, among other things, a BIOS that may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0206] Processor 1240 may include an intelligent hardware device (e.g., a general purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, processor 1240 may be configured to operate a memory array using a memory controller. In some cases, the memory controller may be integrated into processor 1240. Processor 1240 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 1230) to cause device 1205 to perform various functions (e.g., support functions or tasks of triggering demodulation reference signal bundling).

[0207] The inter-site communication manager 1245 may manage communications with other base stations 105 and may include a controller or scheduler for controlling communications with UE 115 in cooperation with other base stations 105. For example, the inter-site communication manager 1245 may coordinate scheduling of transmissions to UE 115 for various interference mitigation techniques, such as beamforming or joint transmission. In some examples, the inter-site communication manager 1245 may provide an X2 interface within an LTE / LTE-A wireless communication network technology to provide communications between base stations 105.

[0208] The code 1235 may include instructions for implementing various aspects of the present disclosure, including instructions for supporting wireless communications. The code 1235 may be stored in a non-transitory computer-readable medium, such as a system memory or other type of memory. In some cases, the code 1235 may not be directly executed by the processor 1240, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0209] Fig.13 1 is a flow chart illustrating a method 1300 for supporting triggered demodulation reference signal bundling according to aspects of the present disclosure. The operations of the method 1300 may be implemented by a UE 115 or a component thereof as described herein. For example, the operations of the method 1300 may be implemented by a UE 115 or a component thereof as described herein. Figures 5 to 8 In some examples, the UE may execute an instruction set to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described herein.

[0210] At 1305, the UE may identify a first bundling indicator associated with a first demodulation reference signal for a first downlink data transmission. In some cases, identifying may include receiving a first bundling indicator associated with at least a first demodulation reference signal for the first downlink data transmission. The operations of 1305 may be performed according to the methods described herein. In some examples, aspects of the operations of 1305 may be performed as described with reference to Figures 5 to 8 The described bundling indicator memory is implemented.

[0211] At 1310, the UE may receive control signaling indicating a second bundling indicator associated with at least a second demodulation reference signal for a second downlink data transmission following the first downlink data transmission. The operations of 1310 may be performed according to the methods described herein. In some examples, aspects of the operations of 1310 may be performed as described with reference to Figures 5 to 8 The control signal components described are used to perform the above operations.

[0212] At 1315, the UE may determine a precoding to be applied to the second demodulation reference signal based on a comparison of the first bundling indicator and the second bundling indicator. The operations of 1315 may be performed according to the methods described herein. In some examples, aspects of the operations of 1315 may be performed as described with reference to Figures 5 to 8 The described precoder is performed.

[0213] Fig.14 1400 for supporting triggered demodulation reference signal bundling according to aspects of the present disclosure. The operations of the method 1400 may be implemented by the UE 115 or its components as described herein. For example, the operations of the method 1400 may be implemented by the UE 115 or its components as described herein. Figures 5 to 8 In some examples, the UE may execute an instruction set to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described herein.

[0214] At 1405, the UE may identify a first bundling indicator associated with at least a first demodulation reference signal for a first downlink data transmission. In some cases, the identification may include receiving a first bundling indicator associated with a first demodulation reference signal for the first downlink data transmission. The operations of 1405 may be performed according to the methods described herein. In some examples, aspects of the operations of 1405 may be performed as described with reference to Figures 5 to 8 The described bundling indicator memory is implemented.

[0215] At 1410, the UE may receive control signaling indicating a second bundling indicator associated with at least a second demodulation reference signal for a second downlink data transmission subsequent to the first downlink data transmission. The operations of 1410 may be performed according to the methods described herein. In some examples, aspects of the operations of 1410 may be performed as described with reference to Figures 5 to 8 The control signal components described are used to perform the above operations.

[0216] At 1415, the UE may determine a precoding to be applied to the second demodulation reference signal based on a comparison of the first bundling indicator and the second bundling indicator. The operations of 1415 may be performed according to the methods described herein. In some examples, aspects of the operations of 1415 may be performed as described with reference to Figures 5 to 8 The described precoder is performed.

[0217] At 1420, the UE may evaluate channel transmission properties of the first downlink data transmission and the second downlink data transmission based on the first bundling indicator and the second bundling indicator being the same. The operations of 1420 may be performed according to the methods described herein. In some examples, aspects of the operations of 1420 may be performed as described with reference to Figures 5 to 8 The described channel characteristic estimator is implemented.

[0218] At 1425, the UE may determine, based on an evaluation of the channel transmission property for the first downlink data transmission and the channel transmission property for the second downlink data transmission, that the same precoding as applied to the first demodulation reference signal is to be used for the second demodulation reference signal. The operations of 1425 may be performed according to the methods described herein. In some examples, aspects of the operations of 1425 may be performed as described with reference to Figures 5 to 8 The described precoder is performed.

[0219] Fig.15 1 is a flow chart illustrating a method 1500 for supporting triggered demodulation reference signal bundling according to aspects of the present disclosure. The operations of the method 1500 may be implemented by a UE 115 or a component thereof as described herein. For example, the operations of the method 1500 may be implemented by a UE 115 or a component thereof as described herein. Figures 5 to 8 In some examples, the UE may execute an instruction set to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described herein.

[0220] At 1505, the UE may identify a first bundling indicator associated with at least a first demodulation reference signal for a first downlink data transmission. In some cases, the identification may include receiving a first bundling indicator associated with a first demodulation reference signal for the first downlink data transmission. The operations of 1505 may be performed according to the methods described herein. In some examples, aspects of the operations of 1505 may be performed as described with reference to Figures 5 to 8 The described bundling indicator memory is implemented.

[0221] At 1510, the UE may receive control signaling indicating a second bundling indicator associated with at least a second demodulation reference signal for a second downlink data transmission following the first downlink data transmission. The operations of 1510 may be performed according to the methods described herein. In some examples, aspects of the operations of 1510 may be performed as described with reference to Figures 5 to 8 The control signal components described are used to perform the above operations.

[0222] At 1515, the UE may determine a precoding to be applied to the second demodulation reference signal based on a comparison of the first bundling indicator and the second bundling indicator. The operations of 1515 may be performed according to the methods described herein. In some examples, aspects of the operations of 1515 may be performed as described with reference to Figures 5 to 8 The described precoder is performed.

[0223] At 1520, the UE may receive a third demodulation reference signal associated with the first downlink channel for the second UE, the third demodulation reference signal being co-scheduled on the same time-frequency resources and different antenna ports as the first demodulation reference signal associated with the first downlink data transmission of the first downlink channel. The operations of 1520 may be performed according to the methods described herein. In some examples, aspects of the operations of 1520 may be performed as described with reference to Figures 5 to 8 The described collaborative scheduling port components are executed.

[0224] At 1525, the UE may receive a fourth demodulation reference signal associated with a second downlink channel for the second UE, the fourth demodulation reference signal being co-scheduled on the same time-frequency resources and different antenna ports as the second demodulation reference signal associated with the second downlink data transmission of the second downlink channel. The operations of 1525 may be performed according to the methods described herein. In some examples, aspects of the operations of 1525 may be performed as described with reference to Figures 5 to 8 The described collaborative scheduling port components are executed.

[0225] At 1530, the UE may identify a first co-scheduling port bundling indicator associated with the third demodulation reference signal. The operations of 1530 may be performed according to the methods described herein. In some examples, aspects of the operations of 1530 may be performed as described with reference to Figures 5 to 8 The described collaborative scheduling port components are executed.

[0226] At 1535, the UE may determine, based on a comparison of the first co-scheduling port bundling indicator and the second co-scheduling port bundling indicator, a precoding to be applied to the fourth demodulation reference signal relative to a precoding applied to the third demodulation reference signal. The operations of 1535 may be performed according to the methods described herein. In some examples, aspects of the operations of 1535 may be performed as described with reference to Figures 5 to 8 The described precoder is performed.

[0227] Fig.16 1 is a flow chart illustrating a method 1600 for supporting triggered demodulation reference signal bundling according to aspects of the present disclosure. The operations of the method 1600 may be implemented by a UE 115 or a component thereof as described herein. For example, the operations of the method 1600 may be implemented by a UE 115 or a component thereof as described herein. Figures 5 to 8 In some examples, the UE may execute an instruction set to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described herein.

[0228] At 1605, the UE may identify a first bundling indicator associated with at least a first demodulation reference signal for a first downlink data transmission. In some cases, the identification may include receiving a first bundling indicator associated with a first demodulation reference signal for the first downlink data transmission. The operations of 1605 may be performed according to the methods described herein. In some examples, aspects of the operations of 1605 may be performed as described with reference to Figures 5 to 8 The described bundling indicator memory is implemented.

[0229] At 1610, the UE may receive control signaling indicating a second bundling indicator associated with at least a second demodulation reference signal for a second downlink data transmission following the first downlink data transmission. The operations of 1610 may be performed according to the methods described herein. In some examples, aspects of the operations of 1610 may be performed as described with reference to Figures 5 to 8 The control signal components described are used to perform the above operations.

[0230] At 1615, the UE may determine a precoding to be applied to the second demodulation reference signal based on a comparison of the first bundling indicator and the second bundling indicator. The operations of 1615 may be performed according to the methods described herein. In some examples, aspects of the operations of 1615 may be performed as described with reference to Figures 5 to 8 The described precoder is performed.

[0231] At 1620, the UE may determine that a precoding different from the precoding applied to the first demodulation reference signal is to be used for the second demodulation reference signal based on the second bundling indicator being different from the first bundling indicator. The operations of 1620 may be performed according to the methods described herein. In some examples, aspects of the operations of 1620 may be performed as described with reference to Figures 5 to 8 The described precoder is performed.

[0232] Fig.17 1 is a flow chart illustrating a method 1700 for supporting triggered demodulation reference signal bundling according to aspects of the present disclosure. The operations of the method 1700 may be implemented by a base station 105 or components thereof as described herein. For example, the operations of the method 1700 may be implemented by a base station 105 or components thereof as described herein. Figures 9 to 12 In some examples, a base station may execute an instruction set to control functional elements of the base station to perform the functions described herein. Additionally or alternatively, a base station may use dedicated hardware to perform various aspects of the functions described herein.

[0233] At 1705, the base station may transmit a first bundling indicator associated with at least a first demodulation reference signal for a first downlink data transmission. The operations of 1705 may be performed according to the methods described herein. In some examples, aspects of the operations of 1705 may be performed as described with reference to Figures 9 to 12 The described bundle manager is used to perform the

[0234] At 1710, the base station may determine a precoding of a second demodulation reference signal to be applied to a second downlink data transmission subsequent to the first downlink data transmission. The operations of 1710 may be performed according to the methods described herein. In some examples, aspects of the operations of 1710 may be performed as described with reference to Figures 9 to 12 The described precoder is performed.

[0235] At 1715, the base station may transmit control signaling indicating a second bundling indicator associated with at least the second demodulation reference signal based on a comparison of the precoding to be applied to the second demodulation reference signal and the precoding applied to the first demodulation reference signal. The operations of 1715 may be performed according to the methods described herein. In some examples, aspects of the operations of 1715 may be performed as described with reference to Figures 9 to 12 The control signal components described are used to perform the above operations.

[0236] Fig.18 1 is a flow chart illustrating a method 1800 for supporting triggered demodulation reference signal bundling according to aspects of the present disclosure. The operations of the method 1800 may be implemented by a base station 105 or components thereof as described herein. For example, the operations of the method 1800 may be implemented by a base station 105 or components thereof as described herein. Figures 9 to 12In some examples, a base station may execute an instruction set to control functional elements of the base station to perform the functions described herein. Additionally or alternatively, a base station may use dedicated hardware to perform various aspects of the functions described herein.

[0237] At 1805, the base station may transmit a first bundling indicator associated with at least a first demodulation reference signal for a first downlink data transmission. The operations of 1805 may be performed according to the methods described herein. In some examples, aspects of the operations of 1805 may be performed as described with reference to Figures 9 to 12 The described bundle manager is used to perform the

[0238] At 1810, the base station may determine a precoding of a second demodulation reference signal to be applied to a second downlink data transmission subsequent to the first downlink data transmission. The operations of 1810 may be performed according to the methods described herein. In some examples, aspects of the operations of 1810 may be performed as described with reference to Figures 9 to 12 The described precoder is performed.

[0239] At 1815, the base station may apply the same precoding as applied to the first demodulation reference signal to the second demodulation reference signal, wherein the first bundling indicator is the same as the second bundling indicator. The operations of 1815 may be performed according to the methods described herein. In some examples, aspects of the operations of 1815 may be performed as described with reference to Figures 9 to 12 The described precoder is performed.

[0240] At 1820, the base station may transmit control signaling indicating a second bundling indicator associated with at least the second demodulation reference signal based on a comparison of the precoding to be applied to the second demodulation reference signal and the precoding applied to the first demodulation reference signal. The operations of 1820 may be performed according to the methods described herein. In some examples, aspects of the operations of 1820 may be performed as described with reference to Figures 9 to 12 The control signal components described are used to perform the above operations.

[0241] Fig.19 1 is a flowchart illustrating a method 1900 for supporting triggered demodulation reference signal bundling according to aspects of the present disclosure. The operations of the method 1900 may be implemented by a base station 105 or components thereof as described herein. For example, the operations of the method 1900 may be implemented by a base station 105 or components thereof as described herein. Figures 9 to 12 In some examples, a base station may execute an instruction set to control functional elements of the base station to perform the functions described herein. Additionally or alternatively, a base station may use dedicated hardware to perform various aspects of the functions described herein.

[0242] At 1905, the base station may transmit a first bundling indicator associated with at least a first demodulation reference signal for a first downlink data transmission. The operations of 1905 may be performed according to the methods described herein. In some examples, aspects of the operations of 1905 may be performed as described with reference to Figures 9 to 12 The described bundle manager is used to perform the

[0243] At 1910, the base station may determine a precoding of a second demodulation reference signal to be applied to a second downlink data transmission following the first downlink data transmission. The operations of 1910 may be performed according to the methods described herein. In some examples, aspects of the operations of 1910 may be performed as described with reference to Figures 9 to 12 The described precoder is performed.

[0244] At 1915, the base station may apply a precoding different from the precoding applied to the first demodulation reference signal to the second demodulation reference signal. The operations of 1915 may be performed according to the methods described herein. In some examples, aspects of the operations of 1915 may be performed as described with reference to Figures 9 to 12 The described precoder is performed.

[0245] At 1920, the base station may switch a bit value of the second bundling indicator from a bit value of the first bundling indicator. The operations of 1920 may be performed according to the methods described herein. In some examples, aspects of the operations of 1920 may be performed as described with reference to Figures 9 to 12 The indicator described is switched to execute.

[0246] At 1925, the base station may transmit control signaling indicating a second bundling indicator associated with at least the second demodulation reference signal based on a comparison of the precoding to be applied to the second demodulation reference signal and the precoding applied to the first demodulation reference signal. The operations of 1925 may be performed according to the methods described herein. In some examples, aspects of the operations of 1925 may be performed as described with reference to Figures 9 to 12 The control signal components described are used to perform the above operations.

[0247] It should be noted that the methods described herein describe possible implementations, and that the various operations and steps may be rearranged or otherwise modified and other implementations are possible. Furthermore, aspects from two or more methods may be combined.

[0248] The technology described herein can be used in various wireless communication systems, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA) and other systems. CDMA systems can implement radio technologies such as CDMA2000, Universal Terrestrial Radio Access (UTRA). CDMA2000 covers IS-2000, IS-95 and IS-856 standards. IS-2000 versions are generally referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is generally referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. TDMA systems can implement radio technologies such as Global System for Mobile Communications (GSM).

[0249] OFDMA systems can implement radio technologies such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunications System (UMTS). LTE, LTE-A, and LTE-A Pro are versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, LTE-A Pro, NR, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). CDMA2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). The techniques described herein may be used for systems and radio technologies mentioned herein as well as for other systems and radio technologies. Although aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for example purposes and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein may also be applicable to applications other than LTE, LTE-A, LTE-A Pro, or NR applications.

[0250] A macro cell generally covers a relatively large geographic area (e.g., a radius of several kilometers) and may allow unrestricted access by UEs with service subscriptions to a network provider. A small cell may be associated with a lower power base station (compared to a macro cell), and the small cell may operate in the same or different (e.g., licensed, unlicensed, etc.) frequency band as the macro cell. According to various examples, a small cell may include a pico cell, a femto cell, and a micro cell. A pico cell, for example, may cover a smaller geographic area and may allow unrestricted access by UEs with service subscriptions to a network provider. A femto cell may also cover a smaller geographic area (e.g., a residence) and may provide restricted access by UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs of users in the residence, etc.). An eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB may support one or more (eg, two, three, four, etc.) cells and may also support communication using one or more component carriers.

[0251] The wireless communication systems described herein may support synchronous or asynchronous operation. For synchronous operation, each base station may have similar frame timing, and transmissions from different base stations may be roughly aligned in time. For asynchronous operation, each base station may have different frame timing, and transmissions from different base stations may not be aligned in time. The techniques described herein may be used for synchronous or asynchronous operation.

[0252] The information and signals described herein may be represented using any of a variety of different techniques and technologies. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout this description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0253] The various illustrative blocks and modules described in conjunction with the disclosure herein may be implemented or executed with a general purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in an alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0254] 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 by a computer-readable medium as one or more instructions or codes. Other examples and implementations fall within the scope of the present disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination thereof. Features that implement the functions may also be physically located in various locations, including being distributed so that parts of the functions are implemented at different physical locations.

[0255] Computer-readable medium includes both non-transient computer storage medium and communication medium, and it includes any medium that facilitates computer program to transfer from one place to another.Non-transient storage medium can be any available medium that can be accessed by general or special-purpose computer.As an example and not limitation, non-transient computer-readable medium can include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), flash memory, compact disk (CD) ROM or other optical disk storage, disk storage or other magnetic storage device, or can be used to carry or store instruction or data structure form of desired program code means and can be accessed by general or special-purpose computer or general or special-purpose processor any other non-transient medium.Any connection is also properly referred to as computer-readable medium.For example, if software is transmitted from website, server or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) or wireless technology such as infrared, radio and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL or wireless technology such as infrared, radio and microwave are just included in the definition of medium. Disk and disc as used herein include CDs, laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

[0256] As used herein (including in the claims), "or" used in a list of items (e.g., a list of items with a phrase such as "at least one of" or "one or more of") indicates an inclusive list, so that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Similarly, as used herein, the phrase "based on" should not be interpreted as referring to a closed set of conditions. For example, an exemplary step described as "based on condition A" may be based on both condition A and condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "based at least in part on."

[0257] In the accompanying drawings, similar components or features may have the same reference number. In addition, various components of the same type may be distinguished by following the reference number with a dash and a second reference number that distinguishes between similar components. If only the first reference number is used in the specification, the description may apply to any of the similar components having the same first reference number regardless of the second reference number, or other subsequent reference numbers.

[0258] The descriptions set forth herein in conjunction with the accompanying drawings describe example configurations and do not represent all examples that may be implemented or that fall within the scope of the claims. The term "exemplary" as used herein means "used as an example, instance, or illustration" and does not mean "better than" or "better than other examples." This detailed description includes specific details to provide an understanding of the described techniques. However, these techniques may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0259] The description herein is provided to enable those skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be apparent to those skilled in the art, and the universal principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Thus, the present disclosure is not limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for wireless communication at a user equipment (UE), comprising: identifying a first bundling indicator associated with at least a first demodulation reference signal for a first downlink data transmission; receiving control signaling indicating a second bundling indicator associated with at least a second demodulation reference signal for a second downlink data transmission subsequent to the first downlink data transmission; determining a precoding to be applied to the second demodulation reference signal based at least in part on a comparison of the first bundling indicator and the second bundling indicator; as well as A determination is made whether to perform bundling of the first demodulation reference signal and the second demodulation reference signal based at least in part on a comparison of the first bundling indicator and the second bundling indicator and a comparison of a first channel transmission property of the first downlink data transmission and a second channel transmission property of the second downlink data transmission.

2. The method of claim 1, wherein determining the precoding further comprises: A determination is made that the same precoding as that applied to the first demodulation reference signal is to be applied to the second demodulation reference signal based at least in part on the first bundling indicator and the second bundling indicator being the same.

3. A method as claimed in claim 2, wherein the same precoding is determined for a subset of physical resource blocks of the second demodulation reference signal and a subset of physical resource blocks of the first demodulation reference signal based at least in part on an overlap of resources used for the first downlink data transmission and the second downlink data transmission.

4. The method of claim 1, further comprising: evaluating the first channel transmission property and the second channel transmission property based at least in part on the first bundling indicator and the second bundling indicator being the same; as well as A determination is made based at least in part on an evaluation of the first channel transmission property and the second channel transmission property that the same precoding as applied to the first demodulation reference signal is to be applied to the second demodulation reference signal.

5. The method of claim 1, wherein the first channel transmission property and the second channel transmission property comprise a port identifier, a channel type, a demodulation reference signal mode, a demodulation reference signal type, a virtual frequency resource allocation, a physical frequency resource allocation, or a combination thereof.

6. The method of claim 5, wherein determining that the same precoding as applied to the first demodulation reference signal is to be applied to the second demodulation reference signal is based at least in part on the first channel transmission property and the second channel transmission property being the same.

7. The method of claim 1 , wherein the first channel transmission property and the second channel transmission property include a time unit threshold, and determining that the same precoding as the precoding applied to the first demodulation reference signal is to be applied to the second demodulation reference signal is based at least in part on the second demodulation reference signal being within a time period from the first demodulation reference signal that is less than the time unit threshold.

8. The method of claim 2, further comprising: receiving a third demodulation reference signal associated with a first downlink channel for a second UE, the third demodulation reference signal being co-scheduled on the same time-frequency resources and a different antenna port as the first demodulation reference signal associated with the first downlink data transmission on the first downlink channel; as well as A fourth demodulation reference signal associated with a second downlink channel for the second UE is received, the fourth demodulation reference signal being co-scheduled on the same time-frequency resources and different antenna port as the second demodulation reference signal associated with the second downlink data transmission on the second downlink channel.

9. The method of claim 8, further comprising: A determination is made that the same precoding as that applied to the third demodulation reference signal is to be applied to the fourth demodulation reference signal based at least in part on the first bundling indicator and the second bundling indicator being the same.

10. The method of claim 8, further comprising: identifying a first co-scheduling port bundling indicator associated with the third demodulation reference signal; receiving a second co-scheduling port bundling indicator associated with the fourth demodulation reference signal in the control signaling; and Based at least in part on a comparison of the first co-scheduled port bundling indicator and the second co-scheduled port bundling indicator, a precoding to be applied to the fourth demodulation reference signal is determined relative to a precoding applied to the third demodulation reference signal.

11. The method of claim 1, further comprising: A determination is made that a precoding different from a precoding applied to the first demodulation reference signal is to be applied to the second demodulation reference signal based at least in part on the second bundling indicator being different from the first bundling indicator, wherein the second bundling indicator being different from the first bundling indicator comprises a bit value of the second bundling indicator being switched from a bit value of the first bundling indicator.

12. The method of claim 1, wherein the second demodulation reference signal comprises a plurality of semi-persistently scheduled demodulation reference signals, the method further comprising: determining, based at least in part on the second bundling indicator, a same precoding to be applied to each of the plurality of semi-persistently scheduled demodulation reference signals; or A different precoding to be applied to each of the plurality of semi-persistently scheduled demodulation reference signals is determined based at least in part on the second bundling indicator.

13. An apparatus for wireless communication at a user equipment (UE), comprising: processor; a memory coupled to the processor; as well as instructions stored in the memory and executable by the processor, the instructions causing the apparatus to: identifying a first bundling indicator associated with at least a first demodulation reference signal for a first downlink data transmission; receiving control signaling indicating a second bundling indicator associated with at least a second demodulation reference signal for a second downlink data transmission subsequent to the first downlink data transmission; determining a precoding to be applied to the second demodulation reference signal based at least in part on a comparison of the first bundling indicator and the second bundling indicator; as well as A determination is made whether to perform bundling of the first demodulation reference signal and the second demodulation reference signal based at least in part on a comparison of the first bundling indicator and the second bundling indicator and a comparison of a first channel transmission property of the first downlink data transmission and a second channel transmission property of the second downlink data transmission.

14. The apparatus of claim 13, wherein the instructions for determining the precoding are further executable by the processor to cause the apparatus to: A determination is made that the same precoding as that applied to the first demodulation reference signal is to be applied to the second demodulation reference signal based at least in part on the first bundling indicator and the second bundling indicator being the same.

15. The apparatus of claim 14, wherein the same precoding is determined for a subset of physical resource blocks of the second demodulation reference signal and a subset of physical resource blocks of the first demodulation reference signal based at least in part on an overlap of resources used for the first downlink data transmission and the second downlink data transmission.

16. The apparatus of claim 13, wherein the instructions are further executable by the processor to cause the apparatus to: evaluating the first channel transmission property and the second channel transmission property based at least in part on the first bundling indicator and the second bundling indicator being the same; and A determination is made based at least in part on an evaluation of the first channel transmission property and the second channel transmission property that the same precoding as applied to the first demodulation reference signal is to be applied to the second demodulation reference signal.

17. The apparatus of claim 13, wherein the first channel transmission property and the second channel transmission property comprise a port identifier, a channel type, a demodulation reference signal mode, a demodulation reference signal type, a virtual frequency resource allocation, a physical frequency resource allocation, or a combination thereof.

18. The apparatus of claim 17, wherein determining that the same precoding as applied to the first demodulation reference signal is to be applied to the second demodulation reference signal is based at least in part on the first channel transmission property and the second channel transmission property being the same.

19. The apparatus of claim 13, wherein the first channel transmission property and the second channel transmission property include a time unit threshold, and determining that the same precoding as the precoding applied to the first demodulation reference signal is to be applied to the second demodulation reference signal is based at least in part on the second demodulation reference signal being within a time period from the first demodulation reference signal that is less than the time unit threshold.

20. The apparatus of claim 14, wherein the instructions are further executable by the processor to cause the apparatus to: determining a third demodulation reference signal associated with a first downlink channel for a second UE, the third demodulation reference signal being co-scheduled on the same time-frequency resources and a different antenna port as the first demodulation reference signal associated with the first downlink data transmission on the first downlink channel; and A fourth demodulation reference signal associated with a second downlink channel for the second UE is received, the fourth demodulation reference signal being co-scheduled on the same time-frequency resources and different antenna port as the second demodulation reference signal associated with the second downlink data transmission on the second downlink channel.

21. The apparatus of claim 20, wherein the instructions are further executable by the processor to cause the apparatus to: A determination is made that the same precoding as that applied to the third demodulation reference signal is to be applied to the fourth demodulation reference signal based at least in part on the first bundling indicator and the second bundling indicator being the same.

22. The apparatus of claim 20, wherein the instructions are further executable by the processor to cause the apparatus to: identifying a first co-scheduling port bundling indicator associated with the third demodulation reference signal; receiving a second co-scheduling port bundling indicator associated with the fourth demodulation reference signal in the control signaling; and Based at least in part on a comparison of the first co-scheduled port bundling indicator and the second co-scheduled port bundling indicator, a precoding to be applied to the fourth demodulation reference signal is determined relative to a precoding applied to the third demodulation reference signal.

23. The apparatus of claim 13, wherein the instructions are further executable by the processor to cause the apparatus to: A determination is made that a precoding different from a precoding applied to the first demodulation reference signal is to be applied to the second demodulation reference signal based at least in part on the second bundling indicator being different from the first bundling indicator.

24. The apparatus of claim 23, wherein the second bundling indicator is different from the first bundling indicator comprising a bit value of the second bundling indicator being switched from a bit value of the first bundling indicator.

25. The apparatus of claim 13, wherein the second demodulation reference signal comprises a plurality of semi-persistently scheduled demodulation reference signals, and wherein the instructions are further executable by the processor to cause the apparatus to: determining, based at least in part on the second bundling indicator, a same precoding to be applied to each of the plurality of semi-persistently scheduled demodulation reference signals; or A different precoding to be applied to each of the plurality of semi-persistently scheduled demodulation reference signals is determined based at least in part on the second bundling indicator.

26. An apparatus for wireless communication at a user equipment (UE), comprising: means for identifying a first bundling indicator associated with a first demodulation reference signal for a first downlink data transmission; means for receiving control signaling indicating a second bundling indicator associated with a second demodulation reference signal for a second downlink data transmission subsequent to the first downlink data transmission; means for determining, based at least in part on a comparison of the first bundling indicator and the second bundling indicator, a precoding to be applied to the second demodulation reference signal; as well as Means for determining whether to perform bundling of the first demodulation reference signal and the second demodulation reference signal based at least in part on a comparison of the first bundling indicator and the second bundling indicator and a comparison of a first channel transmission property of the first downlink data transmission and a second channel transmission property of the second downlink data transmission.

27. The apparatus of claim 26, further comprising: Means for determining that a same precoding as a precoding applied to the first demodulation reference signal is to be applied to the second demodulation reference signal based at least in part on the first bundling indicator and the second bundling indicator being the same.

28. The apparatus of claim 27, wherein the same precoding is determined for a subset of physical resource blocks of the second demodulation reference signal and a subset of physical resource blocks of the first demodulation reference signal based at least in part on an overlap of resources used for the first downlink data transmission and the second downlink data transmission.

29. The apparatus of claim 26, further comprising: means for evaluating a channel transmission property of the first downlink data transmission and the second downlink data transmission based at least in part on the first bundling indicator and the second bundling indicator being the same; as well as Means for determining, based at least in part on an evaluation of a channel transmission property of the first downlink data transmission and a channel transmission property of the second downlink data transmission, that the same precoding as applied to the first demodulation reference signal is to be applied to the second demodulation reference signal.

30. A non-transitory computer-readable medium storing code for wireless communication at a user equipment (UE), the code comprising instructions executable by a processor to: identifying a first bundling indicator associated with a first demodulation reference signal for a first downlink data transmission; receiving control signaling indicating a second bundling indicator associated with a second demodulation reference signal for a second downlink data transmission subsequent to the first downlink data transmission; determining a precoding to be applied to the second demodulation reference signal based at least in part on a comparison of the first bundling indicator and the second bundling indicator; as well as A determination is made whether to perform bundling of the first demodulation reference signal and the second demodulation reference signal based at least in part on a comparison of the first bundling indicator and the second bundling indicator and a comparison of a first channel transmission property of the first downlink data transmission and a second channel transmission property of the second downlink data transmission.

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