Method and apparatus for wireless communication by a wireless node

Abstract

Certain aspects of the present disclosure provide techniques for demodulation reference signal (DMRS) sequence selection. One aspect provides a method for wireless communications by a first wireless node. The method generally includes selecting a type of DMRS sequence to use for communications with a second wireless node based on a signal quality associated with the communications, receiving a message having the type of DMRS sequence, and performing channel estimation based on the DMRS sequence using the message.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Application No. 17 / 453,814, filed November 5, 2021, which claims the benefit and priority to U.S. Provisional Patent Application Serial No. 63 / 141,330, filed January 25, 2021, both of which are expressly incorporated herein by reference in their entirety, as if fully set forth below and for all applicable purposes. Technical Field

[0003] Various aspects of this disclosure relate to wireless communication, and more specifically, to techniques for selecting the type of sequence of a demodulation reference signal (DMRS). Background Technology

[0004] Wireless communication systems are widely deployed to provide a variety of telecommunications services, such as telephone, video, data, messaging, broadcasting, or other similar services. These wireless communication systems can employ multiple access technologies that enable communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, or other resources). Multiple access technologies can rely on any of code division, time division, frequency division, orthogonal frequency division, single-carrier frequency division, or time-division synchronous code division, to name just a few. These and other multiple access technologies have been adopted in various telecommunications standards to provide a common protocol that enables different wireless devices to communicate at the municipal, national, regional, and even global levels.

[0005] Despite significant technological advancements in wireless communication systems over the years, challenges remain. For example, complex and dynamic environments can still attenuate or block signals between wireless transmitters and receivers, disrupting various established wireless channel measurement and reporting mechanisms used to manage and optimize the use of limited wireless channel resources. Therefore, further improvements to wireless communication systems are needed to overcome these challenges.

[0006] Wireless devices can perform channel estimation to obtain channel quality information, which allows the device to correctly decode received signals. As the demand for mobile broadband access continues to increase, so does the need for improved channel estimation. Summary of the Invention

[0007] One approach provides a method for wireless communication by a first wireless node. This method typically includes selecting a demodulation reference signal (DMRS) sequence type to be used for communication with a second wireless node based on signal quality associated with the communication, generating a message having the DMRS sequence type, and sending the message to the second wireless node.

[0008] On the other hand, a method for wireless communication by a first wireless node is provided. This method typically includes selecting the type of demodulation reference signal (DMRS) sequence to be used for communication with a second wireless node based on signal quality associated with the communication, receiving a message having the type of DMRS sequence, and performing channel estimation based on the DMRS sequence using that message.

[0009] Other aspects include: an apparatus operable, configurable, or otherwise adapted to perform the methods described above and elsewhere herein; a non-transitory, computer-readable medium including instructions that, when executed by one or more processors of the apparatus, cause the apparatus to perform the methods described above and elsewhere herein; a computer program product embodied on a computer-readable storage medium, including code for performing the methods described above and elsewhere herein; and an apparatus including components for performing the methods described above and elsewhere herein. For example, an apparatus may include a processing system, a device having a processing system, or a processing system cooperating via one or more networks.

[0010] For illustrative purposes, the following description and accompanying figures illustrate certain features. Attached Figure Description

[0011] The accompanying drawings depict certain features of the various aspects described herein and should not be considered as a limitation on the scope of this disclosure.

[0012] Figure 1 It is a conceptual block diagram illustrating an example wireless communication network.

[0013] Figure 2 It is a block diagram that conceptually illustrates aspects of an example of a base station and user equipment.

[0014] Figures 3A to 3D Various example aspects of data structures used in wireless communication networks are described.

[0015] Figure 4 An exemplary send and receive chain is depicted.

[0016] Figure 5 This is a flowchart illustrating an example operation of wireless communication performed by a transmitter device according to certain aspects of this disclosure.

[0017] Figure 6 This is a flowchart illustrating an example operation of wireless communication performed by a receiver device according to certain aspects of this disclosure.

[0018] Figure 7 The process for selecting a demodulation reference signal (DMRS) sequence according to certain aspects of this disclosure is described.

[0019] Figure 8 and Figure 9 An example communication device is described. Detailed Implementation

[0020] This disclosure provides apparatus, methods, processing systems, and computer-readable media for configuring demodulation reference signal (DMRS) sequence types.

[0021] Several aspects enable flexible DMRS sequence type configuration, allowing trade-offs between channel estimation performance and processing complexity at the receiver (e.g., user equipment (UE)). For example, a radio node can choose between using pseudo-noise (PN) sequences or Zadoff-Chu (ZC) sequences for DMRS based on various considerations. PN sequences are less computationally complex than ZC sequences, but offer lower channel estimation performance compared to ZC sequences using higher-order modulation and decoding schemes (MCS). Higher-order MCSs can be used in scenarios with higher signal quality (e.g., higher signal-to-interference-plus-noise ratio (SINR)). In some aspects of this disclosure, the radio node can select the DMRS sequence type based on signal quality. For example, if a higher-order MCS (e.g., indicating higher SINR) is used, ZC can be selected as the DMRS sequence to take advantage of the higher channel estimation performance associated with ZC sequences. On the other hand, if a lower-order MCS (e.g., indicating lower SINR) is used, PN can be selected as the DMRS sequence, thereby reducing the processing complexity of the receiver. Therefore, certain aspects of this disclosure allow for the selection of sequences with lower processing complexity under appropriate circumstances for a given signal quality scenario, thereby improving processing efficiency at the receiver. For example, because the selected sequence of DMRS has lower processing complexity, the UE can process (e.g., perform channel estimation on it) the received packets more efficiently and save power.

[0022] Introduction to Wireless Communication Networks

[0023] Figure 1 An example of a wireless communication system 100 is depicted, in which the aspects described herein can be implemented.

[0024] Generally, wireless communication system 100 includes base station (BS) 102, user equipment (UE) 104, evolved packet core (EPC) 160, and core network 190 (e.g., 5G core (5GC)), which interoperate to provide wireless communication services.

[0025] Base station 102 can provide user equipment 104 with access to EPC 160 and / or core network 190, and can perform one or more of the following functions: transmitting user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and device tracking, RAN information management (RIM), paging, location, and delivery of warning messages. In various contexts, a base station may include and / or be referred to as gNB, Node B, eNB, access point, base transceiver, radio base station, radio transceiver, or transceiver function, or transmit / receive point (TRP).

[0026] Base station 102 wirelessly communicates with UE 104 via communication link 120. Each of base stations 102 can provide communication coverage for a corresponding geographic coverage area 110, which may overlap in some cases. For example, a small cell 102' (e.g., a low-power base station) may have a coverage area 110' that overlaps with the coverage areas 110 of one or more macro cells (e.g., high-power base stations).

[0027] The communication link 120 between base station 102 and UE 104 may include uplink (UL) (also known as reverse link) transmission from UE 104 to base station 102 and / or downlink (DL) (also known as forward link) transmission from base station 102 to UE 104. The communication link 120 may use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity in various aspects.

[0028] Examples of UE 104 include cellular phones, smartphones, Session Initiation Protocol (SIP) phones, laptops, personal digital assistants (PDAs), satellite radios, GPS devices, multimedia devices, video devices, digital audio players, cameras, game consoles, tablets, smart devices, wearable devices, vehicles, electronic instruments, air pumps, large or small kitchen appliances, healthcare devices, implants, sensors / actuators, displays, or other similar devices. Some of UE 104 may be Internet of Things (IoT) devices (e.g., parking meters, air pumps, toasters, vehicles, heart monitors, or other IoT devices), always-on (AON) devices, or edge processing devices. UE 104 may also be more generally referred to as a station, mobile station, subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile subscriber device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, mobile phone, user agent, mobile client, or client.

[0029] The wireless communication network 100 includes a DMRS component 199, which can be configured to select a sequence of DMRS for communication. The wireless communication system 100 also includes a DMRS component 198, which can be configured to select a sequence of DMRS for communication.

[0030] Figure 2 Various aspects of the example base station (BS) 102 and user equipment (UE) 104 are depicted.

[0031] Generally, base station 102 includes various processors (e.g., 220, 230, 238, and 240), antennas 234a-t (collectively referred to as 234), transceivers 232a-t (collectively referred to as 232), transceivers 232a-t including modulators and demodulators, as well as other aspects enabling wireless transmission of data (e.g., data source 212) and wireless reception of data (e.g., data sink 239). For example, base station 102 can transmit and receive data between itself and user equipment 104.

[0032] Base station 102 includes a controller / processor 240, which can be configured to implement various functions related to wireless communication. In the depicted example, controller / processor 240 includes a DMRS component 241, which can represent Figure 1 The DMRS component 199. It is worth noting that although it is depicted as one aspect of the controller / processor 240, in other implementations, the DMRS component 241 may be additionally or alternatively implemented in various other aspects of the base station 102.

[0033] Generally, user equipment 104 includes various processors (e.g., 258, 264, 266, and 280), antennas 252a-r (collectively referred to as 252), transceivers 254a-r (collectively referred to as 254), transceivers 254a-r including modulators and demodulators, as well as other aspects that enable wireless transmission of data (e.g., data source 262) and wireless reception of data (e.g., data sink 260).

[0034] User equipment 104 includes a controller / processor 280, which can be configured to implement various functions related to wireless communication. In the depicted example, the controller / processor 280 includes a DMRS component 281, which can represent Figure 1 The DMRS component 198. It is worth noting that although it is depicted as one aspect of the controller / processor 280, in other implementations, the DMRS component 281 may be additionally or alternatively implemented in various other aspects of the user equipment 104.

[0035] Figures 3A to 3D Describes the use of wireless communication networks (such as Figure 1 The data structure of the wireless communication network 100. In particular, Figure 3A Figure 300 illustrates an example of the first subframe within a 5G (e.g., 5G NR) frame structure. Figure 3B Figure 330 illustrates an example of a DL channel within a 5G subframe. Figure 3C Figure 350 illustrates an example of the second subframe within a 5G frame structure, and Figure 3D Figure 380 illustrates an example of a UL channel within a 5G subframe.

[0036] Information regarding will be provided later in this disclosure. Figure 1 , Figure 2 and Figures 3A to 3D Further discussion is needed.

[0037] Introduction to Single-Carrier (SC) Waveforms

[0038] Single-carrier (SC) waveforms and time-domain symbol ordering can be associated with a lower peak-to-average power ratio (PAPR) than multi-carrier waveforms. A lower PAPR facilitates higher power amplifiers (PAs) in the transmitter chain of a wireless node (e.g., Figure 2The PA (Power Aspect Ratio) efficiency of transceiver 232 or transceiver 254 is improved, thereby extending the battery life of the wireless node. Transmitter designs supporting SC waveforms can be simpler than those supporting multicarrier waveforms. Equalizers can be used to achieve high spectral efficiency in the presence of multipath interference between the transmitter and receiver. An example waveform that can be used for SC may include SC Frequency Domain Equalization (FDE), as described in more detail herein.

[0039] For OFDM-based multicarrier waveforms and frequency domain symbol ordering, multiple orthogonal subcarriers within a given carrier bandwidth can be supported. Integration of OFDM-based multicarrier waveforms with Multiple-Input Multiple-Output (MIMO) can improve spectral efficiency. An example waveform that can be used for OFDM-based multicarrier waveforms includes Cyclic Prefix (CP)-OFDM. Another example waveform that can be used for OFDM-based multicarrier waveforms includes Discrete Fourier Transform (DFT) Extended (DFT-s)-OFDM.

[0040] Compared to CP-OFDM / DFT-s-OFDM, the SC waveform can have a lower PAPR. Therefore, the UE may be able to transmit at higher power because less PA backoff is possible. In other words, a higher PAPR signal allows the PA to operate at a lower power level to accommodate the higher PAPR. Thus, a lower PAPR allows the PA to transmit at higher power because it allows the PA to operate at a higher power level. OFDM-based multicarrier waveforms are suitable for scenarios with more lenient energy efficiency specifications, while SC waveforms can be used for scenarios with higher energy efficiency specifications.

[0041] Example transmit and receive chains for single-carrier (SC) waveforms

[0042] Figure 4 An example transmit and receive chain is depicted for supporting quadrature amplitude modulation (QAM) with SC-FDE waveforms. Figure 4 The sending and receiving chains can be Figure 2 This is part of transceivers 232 and 254. SC-QAM with SC-FDE offers various advantages, such as lower PAPR than multicarrier waveforms, lower adjacent channel leakage rate (ACLR) due to the use of pulse shaping filters, and simpler waveform synthesis at the transmitter. SC-QAM with SC-FDE also allows frequency domain equalization in the receiver to reduce interference associated with multipath interference by using a cyclic prefix (CP). In other words, inserting a CP allows for performance improvements when frequency domain equalization is implemented at the receiver. On the other hand, adding a CP with SC-FDE for QAM may result in a slight decrease in spectral efficiency.

[0043] As shown in the figure, at the transmit chain of transmitter 400, CP addition component 402 can be used to add a CP to a packet. This packet can be provided to QAM modulation component 404 and root raised cosine (RRC) pulse shaping component 406 for processing before transmission to receiver 410. At receiver 410, CP removal component 412 can be used to remove the CP from each symbol of the packet, which can then be provided to serial-to-parallel conversion (S / P) component 414, which provides the digital data stream to Fast Fourier Transform (FFT) component 416. FFT component 416 converts the digital data stream from the time domain to the frequency domain.

[0044] As shown in the figure, once the CP is removed, the packet can also be transmitted to the channel estimation component 418. The channel estimation component 418 can generate a channel estimate using the demodulation reference signal (DMRS) of the received packet. The result of the channel estimation can be provided to the frequency domain equalizer (FDE) component 420. Via the FDE component 420, the output of the FFT component 416 can be processed based on the channel estimate provided by the channel estimation component 418. The equalized output obtained by the FDE component 420 is then converted back to the time domain using the inverse fast Fourier transform (IFFT) component 422 and demodulated using the QAM demodulation component 424, as shown in the figure.

[0045] In some implementations, a fractional-interval equalizer (FSE) for SC-FDE waveforms can be used, offering performance advantages over conventional symbol-interval equalizers due to its robustness to the sampling phase. The performance of the SC-FDE receiver (which incorporates an FSE based on minimum mean square error (MMSE)) is influenced by the performance of the channel estimation algorithm (e.g., implemented at channel estimation component 418). For example, suppose the FSE is performed at 2x symbol rate. The corresponding channel (e.g., at 2x symbol rate) can be estimated using the correlation equation:

[0046] ,

[0047] in, Indicates the channel response. The vector representing the received sample. Represents the training sequence, and for , , This represents a circular convolution operation. In other words, the known sequence used to transmit the DMRS can be correlated with the actual received DMRS to estimate the channel and implement an equalizer. One of the factors that can affect the performance of correlation-based channel estimation in SC-FDE is the type of DMRS sequence chosen. In other words, the better the autocorrelation function of the DMRS sequence used to estimate the channel, the more effective the channel estimation function is likely to be.

[0048] Aspects related to sequence selection of demodulation reference signal (DMRS)

[0049] Having different DMRS sequences for channel estimation can be useful because it provides greater flexibility in UE operation. Some example types of DMRS sequences can include pseudo-noise (PN) sequences or Zadoff-Chu (ZC) sequences. Energy-efficient UEs, or UEs operating in energy-efficient mode, can use PN sequences because they are easier to implement, while high-performance UEs (e.g., using spectrally efficient modulation and decoding schemes (MCS)) can use more complex ZC sequences.

[0050] Typically, PN sequences use 1s and -1s, making the channel estimation process at the receiver less computationally complex. PN sequences also provide a wide array of possible sequences of varying lengths. However, PN sequences do not have an ideal autocorrelation function, which can lead to lower channel estimation performance compared to ZC sequences. Example PN sequences include m-sequences, Gold codes, or Kasami codes. Complex ZC sequences have an ideal autocorrelation function. In other words, the out-of-phase autocorrelation of a ZC sequence is 0. However, due to the complex number of elements involved in ZC sequences, implementations may involve more computation, especially when the receiver performs channel estimation.

[0051] For low signal-to-interference-plus-noise ratio (SINR) regimes, channels with PN sequence-based DMRS (e.g., PDSCH) exhibit similar performance to channels with ZC sequence-based DMRS. Lower-range MCS can be used in low SINR regimes. For high SINR regimes, channels with ZC sequence-based DMRS (e.g., PDSCH) offer a performance advantage over PN sequence-based DMRS. Higher-range MCS can be used in high SINR regimes.

[0052] Some aspects of this disclosure relate to selecting the DMRS sequence type based on signal quality (e.g., SINR, MCS, etc.). For example, in the case of lower SINR, where a low-order MCS can be used for the channel (e.g., PDSCH), the radio node (e.g., BS) can employ PN sequence-based DMRS. The selection of the PN sequence for the DMRS can simplify the receiver's channel estimation process by reducing multiplication operations (e.g., replacing them with computationally less demanding addition and subtraction operations), with a slight performance penalty. On the other hand, in the case of higher SINR, where a higher-order MCS is used for the channel and higher performance is desired, the radio node (e.g., BS) can employ ZC sequence-based DMRS.

[0053] Example operation of DMRS sequence selection

[0054] Figure 5 This is a block diagram illustrating an example operation 500 for wireless communication. Operation 500 can be performed, for example, by a first wireless node (e.g., such as...). Figure 1 A BS such as BS 102 in a wireless communication network 100, or such as Figure 1 The wireless communication system 100 uses a UE (such as UE 104) to perform the operation.

[0055] Operation 500 can be implemented in one or more processors (e.g., Figure 2 Software components that execute and run on the controller / processor 240 or 280. Furthermore, for example, this can be achieved via one or more antennas (e.g., Figure 2 The antenna 234 or 252 enables the BS to transmit and receive signals in operation 500. In some respects, the transmission and / or reception of signals by the BS or UE can be achieved via a bus interface of one or more processors (e.g., controller / processor 240 or 280, or DMRS component 241 or 281) to obtain and / or output signals.

[0056] Operation 500 begins at block 502, whereby the first wireless node selects the signal quality associated with the communication to be used with the second wireless node (e.g., UE, such as...). Figure 1 The type of DMRS sequence used for communication with the UE (104) in the BS. For example, the BS can determine the MCS to be used for communication with the radio node, and selecting the type of DMRS sequence can include selecting the type of DMRS sequence based on the MCS. If the determined MCS is a first MCS, the type of the selected DMRS sequence can be a PN sequence; and if the determined MCS is a second MCS, the type of the selected DMRS sequence can be a ZC sequence, which has a higher order than the first MCS.

[0057] In some aspects, selecting the type of DMRS sequence based on signal quality at box 502 may include selecting the length of the DMRS sequence based at least in part on the Doppler spread associated with the communication. For example, a shorter DMRS sequence may be selected for a higher Doppler spread, and a longer DMRS sequence may be selected for a lower Doppler spread.

[0058] In some aspects, selecting the type of DMRS sequence based on signal quality at box 502 includes selecting the type of DMRS sequence based on a mapping between one or more candidate MCSs and one or more candidate DMRS sequence types. The BS may indicate the mapping to a second radio node (e.g., UE).

[0059] In some respects, the first wireless node may receive instructions from the second wireless node (e.g., a request for the type of sequence to be used, or signal quality parameters), and the selection of the type of DMRS sequence may be further based on instructions from the second wireless node. For example, the first wireless node may receive a request for the type of DMRS sequence to be used for communication, receive instructions for one or more signal quality parameters associated with the communication, or both.

[0060] At box 504, the first wireless node can generate a message of type (e.g., PDSCH) with a selected DMRS sequence. At box 506, the first wireless node can send a message to the second wireless node.

[0061] Figure 6 This is a flowchart illustrating an example operation 600 for wireless communication according to certain aspects of this disclosure. Operation 600 may be performed, for example, by a second wireless node (e.g., such as...). Figure 1 A BS such as BS 102 in a wireless communication network 100, or such as Figure 1 The operation 600 is performed by a UE (such as a UE 104) in a wireless communication system 100. Operation 600 can be implemented in one or more processors (e.g., Figure 2 Software components that execute and run on the controller / processor 240, 280 or DMRS component 241, 281. Additionally, for example, it can be a software component executed and run on one or more antennas (e.g., Figure 2 The antenna 234 or 252 is used to enable the UE to transmit and receive signals in operation 600. In some aspects, the UE's transmission and / or reception of signals can be achieved via a bus interface of one or more processors (e.g., controller / processor 240 or 280) to obtain and / or output signals.

[0062] Operation 600 begins at block 602, where the first radio node (e.g., UE) selects the type of DMRS sequence to be used for communicating with the second radio node (e.g., BS) based on the signal quality associated with the communication. For example, the first radio node may determine the MCS to be used for communicating with the radio node. Selecting the type of DMRS sequence at block 602 may include selecting the type of DMRS sequence based on the MCS.

[0063] At box 604, the first wireless node can receive a message of the type having a DMRS sequence. For example, the first wireless node (e.g., UE 104) can receive the message via antenna 252.

[0064] At box 606, the first wireless node can use this message to perform channel estimation based on the DMRS sequence (e.g., via channel estimation component 418).

[0065] Figure 7 A process 700 for DMRS sequence selection according to certain aspects of this disclosure is described.

[0066] As shown in the figure, at box 728, BS 702 can select the DMRS configuration. For example, as described herein, at box 726, BS 702 can select the MCS used for communication with UE 704, and at box 728, select either the PN sequence or the ZC sequence for DMRS based on the selected MCS. BS 702 can then send a message with DMRS 710 to UE 704. At box 712, UE 704 can perform channel estimation and decoding based on DMRS 710, as shown in the figure.

[0067] In some respects, the DMRS sequence type can be selected based on Doppler spread at box 728. For example, in high Doppler scenarios (e.g., where the UE moves at high speed), a shorter DMRS sequence can accommodate a shorter coherence time. In some cases, when a shorter DMRS sequence is selected for a higher Doppler spread, more than one DMRS can be included in the time slot to estimate the channel more efficiently. In some cases, a shorter PN sequence can be avoided due to higher side peaks associated with the PN sequence.

[0068] In some respects, the DMRS sequence type configuration 708 can communicate between a transmitter (e.g., BS 702) and a receiver (e.g., UE 704). For example, BS 702 can directly (e.g., explicitly) indicate to UE 704 information about the selected type of DMRS sequence. The DMRS sequence type configuration 708 can indicate this to UE 704 using downlink control information (DCI) in the physical downlink control channel (PDCCH), medium access control (MAC)-control unit (CE), or via radio resource control (RRC) configuration.

[0069] In some respects, a default DMRS sequence type can be defined and used as a fallback configuration. For example, at box 730, BS 702 and UE 704 can communicate using a default DMRS sequence type, which can be pre-configured (e.g., using RRC signaling or configured in a standard specification).

[0070] If BS 702 does not explicitly indicate the selected DMRS sequence type to UE 704, UE 704 can use the default DMRS sequence type (e.g., at box 730). A specific DMRS sequence type configuration can remain valid until a new configuration is signaled to UE 704. In some respects, the configured DMRS sequence configuration can be valid for a specific time period 790. For example, a timer can be defined and associated with the DMRS sequence type configuration. Once the timer expires, the system falls back to using the default DMRS sequence type (e.g., at box 792).

[0071] In some respects, BS 702 can indirectly indicate the DMRS sequence type by associating the DMRS sequence type with the MCS. For example, a static configuration can be used in conjunction with a fixed MCS-to-DMRS sequence mapping. In this case, BS 702 can implicitly indicate the DMRS sequence type based on the MCS configuration to be used, rather than explicitly signaling the selected DMRS sequence type.

[0072] In some aspects, the MCS-to-DMRS sequence type mapping can be configured dynamically or semi-statically. In other words, the configurable MCS-to-DMRS sequence type mapping can be defined and modified over time. In some implementations, several MCS-to-DMRS sequence type mappings can be predefined, allowing BS 702 and UE 704 to switch between mappings for various given scenarios. As shown in the figure, mapping 720 can be delivered to UE 704. In some aspects, the mapping can be delivered to UE 704 via Radio Resource Control (RRC) messages and subsequently enabled or disabled via Downlink Control Information (DCI).

[0073] In some implementations, the DMRS sequence type configuration can be selected based on UE indications (also known as UE feedback). For example, BS 702 can receive DMRS sequence indication 706 from UE 704, which can be considered for the selection of the DMRS sequence type configuration. That is, the feedback from UE 704 can include feedback indicating the processing capabilities of UE 704, which can be considered by BS 702 for selecting the DMRS sequence type configuration at block 728. For example, if the UE is a low-capacity UE (also known as a redcap UE), the PN sequence, which has lower processing complexity compared to the ZC sequence, can be selected.

[0074] In some aspects, UE feedback may include feedback indicating the SINR and / or Doppler spread measured by UE 704. In other words, BS 702 may select the DMRS sequence type and length based on the SINR and Doppler spread indicated by UE 704. In some aspects, feedback may be delivered as part of Channel State Information (CSI) feedback. In other words, BS 702 may send a CSI Reference Signal (CSI-RS) to UE 704, based on which UE 704 may provide CSI feedback to BS 702. CSI feedback may include DMRS sequence indication 706.

[0075] In some implementations, feedback from UE 704 can be direct. In other words, UE 704 can directly request a specific DMRS sequence type to use. For example, DMRS sequence indication 706 can request a specific DMRS sequence type to select. This request can be included in a new Layer 1 (L1) message or in some existing L1 message (e.g., as part of a Downlink Control Information (DCI)). The request can be delivered via a Layer 3 (L3) message (e.g., a Radio Resource Control (RRC) message). In some cases, BS 702 can consider but not comply with UE 704's feedback request. In other words, BS 702 can configure a different DMRS sequence type than the one requested as part of the UE's feedback.

[0076] Example wireless communication device

[0077] Figure 8 An example communication device 800 is depicted, which includes operations operable, configurable, or adapted to perform the techniques disclosed herein (such as regarding...). Figure 5 Various components (depicting and describing operations). In some examples, the communication device 800 may be, for example, a reference... Figure 1 and Figure 2The base station 102 is described. In some examples, the communication device 800 may be, for example, reference... Figure 1 and Figure 2 The user equipment 104 described.

[0078] The communication device 800 includes a processing system 802 coupled to a transceiver 808 (e.g., a transmitter and / or receiver). The transceiver 808 is configured to transmit (or transmit) and receive signals, such as the various signals described herein, for the communication device 800 via an antenna 810. The processing system 802 may be configured to perform processing functions of the communication device 800, including processing signals received and / or transmitted by the communication device 800.

[0079] Processing system 802 includes one or more processors 820 coupled to computer-readable medium / memory 830 via bus 806. In some aspects, computer-readable medium / memory 830 is configured to store instructions (e.g., computer-executable code) that, when executed by the one or more processors 820, cause the one or more processors 820 to perform. Figure 5 The operations shown are or other operations used to perform the various techniques discussed herein for DMRS sequence selection.

[0080] In the depicted example, the computer-readable medium / memory 830 stores code 831 for selection (e.g., selecting the type of DMRS sequence), code 832 for generation (e.g., generating a message), and code 833 for communication (e.g., receiving or sending). The computer-readable medium / memory 830 may also optionally include code 834 for determination (e.g., determining the MCS).

[0081] In the depicted example, the one or more processors 820 include circuitry configured to implement code stored in a computer-readable medium / memory 830. This circuitry includes circuitry 821 for selection (e.g., selecting the type of DMRS sequence), circuitry 822 for generation (e.g., generating a message), and circuitry 823 for communication (e.g., receiving or sending). The one or more processors 820 may also optionally include circuitry 824 for determination (e.g., determining the MCS).

[0082] The various components of the communication device 800 can provide for performing the functions described herein, including those related to... Figure 5 The components of the method.

[0083] In some examples, the components used for sending or transmitting (or for outputting for transmission) may include Figure 2 The transceiver 232 or 254 and / or (multiple) antennas 234 or 252 of the base station 102 or user equipment 104 shown, and / or Figure 8 The transceiver 808 and antenna 810 of the communication device 800.

[0084] In some cases, a device may have an interface to output signals and / or data for transmission (the output component), rather than actually sending signals and / or data. For example, a processor may output signals and / or data to a radio frequency (RF) front end for transmission via a bus interface. Similarly, a device may have an interface to acquire signals and / or data received from another device (the acquisition component), rather than actually receiving signals and / or data. For example, a processor may acquire (or receive) signals and / or data from an RF front end for reception via a bus interface. In various aspects, the RF front end may include a variety of components, including transmit and receive processors, transmit and receive MIMO processors, modulators, demodulators, etc., such as... Figure 2 As depicted in the example.

[0085] In some examples, the component for receiving (or the component for obtaining) may include Figure 2 The base station or user equipment shown includes transceivers 232 or 254 and / or (multiple) antennas 234 or 252, and / or Figure 8 The transceiver 808 and antenna 810 of the communication device 800.

[0086] In some examples, the components for selection, generation, communication, and determination can include various processing system components, such as: Figure 8 One or more of the processors 820, or Figure 2 Various aspects of the base station 102 or user equipment 104 depicted include a receiving processor 238 or 258, a transmitting processor 220 or 264, a TXMIMO processor 230 or 266, and / or a controller / processor 240 or 280 (including a DMRS component 241 or 281).

[0087] It is worth noting that, Figure 8 This is just one use case, and many other examples and configurations of the communication device 800 are possible.

[0088] Figure 9 An example communication device 900 is depicted, which includes operations operable, configurable, or adapted to perform the techniques disclosed herein (such as regarding...). Figure 6 Various components (depicting and describing operations). In some examples, the communication device 900 may be, for example, a reference... Figure 1 and Figure 2 The user equipment 104 is described. In some examples, the communication device 900 may be, for example, reference... Figure 1 and Figure 2The described base station 102.

[0089] The communication device 900 includes a processing system 902 coupled to a transceiver 908 (e.g., a transmitter and / or receiver). The transceiver 908 is configured to transmit (or transmit) and receive signals, such as the various signals described herein, for the communication device 900 via an antenna 910. The processing system 902 may be configured to perform processing functions of the communication device 900, including processing signals received and / or transmitted by the communication device 900.

[0090] Processing system 902 includes one or more processors 920 coupled to computer-readable medium / memory 930 via bus 906. In some aspects, computer-readable medium / memory 930 is configured to store instructions (e.g., computer-executable code) that, when executed by the one or more processors 920, cause the one or more processors 920 to perform. Figure 6 The operations shown are or other operations used to perform the various techniques discussed herein for DMRS sequence selection.

[0091] In the depicted example, the computer-readable medium / memory 930 stores code 931 for selection (e.g., selecting the type of DMRS sequence), code 932 for performing channel estimation, and code 933 for communication (e.g., receiving or transmitting). The computer-readable medium / memory 930 may also optionally include code 934 for determination (e.g., determining the MCS).

[0092] In the depicted example, the one or more processors 920 include circuitry configured to implement code stored in a computer-readable medium / memory 930. This circuitry includes circuitry 921 for selection (e.g., selecting the type of DMRS sequence), circuitry 922 for performing channel estimation, and circuitry 923 for communication (e.g., receiving or transmitting). The one or more processors 920 may also optionally include circuitry 924 for determination (e.g., determining the MCS).

[0093] The various components of the communication device 900 can provide for performing the functions described herein, including those related to... Figure 6 The components of the method.

[0094] In some examples, the components used for sending or transmitting (or for outputting for transmission) may include Figure 2 The transceiver 232 or 254 and / or (multiple) antennas 234 or 252 of the base station 102 or user equipment 104 shown, and / or Figure 9 The transceiver 908 and antenna 910 of the communication device 900.

[0095] In some examples, the component for receiving (or the component for obtaining) may include Figure 2 The transceiver 232 or 254 and / or (multiple) antennas 234 or 252 of the base station 102 or user equipment 104 shown, and / or Figure 9 The transceiver 908 and antenna 910 of the communication device 900.

[0096] In some examples, the components for selection, for performing channel estimation, for communication, and for determination can include various processing system components, such as: Figure 9 One or more of the 920 processors, or Figure 2 Various aspects of the base station 102 or user equipment 104 depicted include a receiving processor 258, a transmitting processor 220 or 264, a TXMIMO processor 230 or 266, and / or a controller / processor 240 or 280 (including a DMRS component 241 or 281).

[0097] It is worth noting that, Figure 9 This is just one use case, and many other examples and configurations of the communication device 900 are possible.

[0098] Implementation Examples

[0099] An example of the implementation is described below:

[0100] One implementation example provides a method for wireless communication by a first wireless node, comprising: selecting a type of demodulation reference signal (DMRS) sequence to be used for communication with a second wireless node based on signal quality associated with the communication; generating a message having the DMRS sequence type; and sending the message to the second wireless node.

[0101] Optionally, the signal quality includes the signal-to-interference-plus-noise ratio (SINR).

[0102] Optionally, the method further includes: determining a modulation and decoding scheme (MCS) to be used for communication with the second wireless node, wherein selecting the type of DMRS sequence includes selecting the type of DMRS sequence based on the MCS.

[0103] Optionally, if the determined MCS is a first MCS, the type of the selected DMRS sequence includes pseudo-noise (PN) sequences; and if the determined MCS is a second MCS, the type of the selected DMRS sequence includes Zadoff-Chu (ZC) sequences, which have a higher order than the first MCS.

[0104] Optionally, the method further includes sending an indication of the type of the selected DMRS sequence to a second wireless node.

[0105] Optionally, the method further includes communicating with the second wireless node using a default DMRS sequence type before sending an indication of the type of the selected DMRS sequence.

[0106] Optionally, selecting the type of DMRS sequence based on signal quality includes selecting the type of DMRS sequence based on a mapping between one or more candidate MCSs and one or more candidate DMRS sequence types.

[0107] Optionally, the method further includes: indicating the mapping to the second wireless node.

[0108] Optionally, the type of DMRS sequence selected is active within the configured time period.

[0109] Optionally, selecting the type of DMRS sequence based on signal quality includes selecting the length of the DMRS sequence based at least in part on the Doppler spread associated with the communication.

[0110] Optionally, the method further includes receiving an indication from a second wireless node, wherein the selection of the type of DMRS sequence is also based on the indication from the second wireless node.

[0111] Optionally, the instruction includes a request for the type of DMRS sequence to be used for communication.

[0112] Optionally, the type of DMRS sequence requested by the second wireless node is different from the type of DMRS sequence selected by the first wireless node.

[0113] Optionally, the indication may include an indication of one or more signal quality parameters associated with the communication.

[0114] Optionally, one or more signal quality parameters include at least one of the following: a signal-to-interference-plus-noise ratio (SINR) parameter; or an indication of Doppler spread associated with communication.

[0115] Optionally, the indication may include an indication of the processing capabilities of the second wireless node.

[0116] Optionally, this indication is received as part of the channel state information (CSI) feedback.

[0117] Optionally, the indication is received as part of either Layer 1 (L1) signaling or Layer 3 (L3) signaling.

[0118] Optionally, the first wireless node includes a base station, and the second wireless node includes a user equipment (UE).

[0119] One implementation example provides a method for wireless communication by a first wireless node, comprising: selecting a type of demodulation reference signal (DMRS) sequence to be used for communication with a second wireless node based on signal quality associated with the communication; receiving a message having the type of DMRS sequence; and performing channel estimation based on the DMRS sequence using the message.

[0120] Optionally, the signal quality includes the signal-to-interference-plus-noise ratio (SINR).

[0121] Optionally, the method further includes: determining a modulation and decoding scheme (MCS) to be used for communication with the second wireless node, wherein selecting the type of DMRS sequence includes selecting the type of DMRS sequence based on the MCS.

[0122] Optionally, if the determined MCS is a first MCS, the type of the selected DMRS sequence includes pseudo-noise (PN) sequences; and if the determined MCS is a second MCS, the type of the selected DMRS sequence includes Zadoff-Chu (ZC) sequences, which have a higher order than the first MCS.

[0123] Optionally, the method further includes receiving an indication of the type of the selected DMRS sequence from a second wireless node.

[0124] Optionally, the method further includes: communicating with the second wireless node using a default DMRS sequence type before receiving an indication of the type of the selected DMRS sequence.

[0125] Optionally, selecting the type of DMRS sequence based on signal quality includes selecting the type of DMRS sequence based on a mapping between one or more candidate MCSs and one or more candidate DMRS sequence types.

[0126] Optionally, the method further includes receiving an indication of mapping from a second wireless node.

[0127] Optionally, the type of DMRS sequence selected is active within the configured time period.

[0128] Optionally, selecting the type of DMRS sequence based on signal quality includes selecting the length of the DMRS sequence based at least in part on the Doppler spread associated with the communication.

[0129] Optionally, the method further includes sending an indication to a second wireless node of the type to be used to select the DMRS sequence.

[0130] Optionally, the instruction includes a request for the type of DMRS sequence to be used for communication.

[0131] Optionally, the method further includes receiving an indication of the type of DMRS sequence from a second wireless node, wherein the type of DMRS sequence requested by the first wireless node is different from the type of DMRS sequence indicated from the second wireless node.

[0132] Optionally, the indication may include an indication of one or more signal quality parameters associated with the communication.

[0133] Optionally, one or more signal quality parameters include at least one of the following: a signal-to-interference-plus-noise ratio (SINR) parameter; or an indication of Doppler spread associated with communication.

[0134] Optionally, the indication may include an indication of the processing capabilities of the second wireless node.

[0135] Optionally, this indication is received as part of the channel state information (CSI) feedback.

[0136] Optionally, the indication is received as part of either Layer 1 (L1) signaling or Layer 3 (L3) signaling.

[0137] Optionally, the first wireless node includes a user equipment (UE), and the second wireless node includes a base station.

[0138] One embodiment provides an apparatus including: a memory including executable instructions; and one or more processors configured to execute the executable instructions and cause the apparatus to perform the methods described above.

[0139] One embodiment provides an apparatus including components for performing the method described above.

[0140] One implementation example provides a non-transitory computer-readable medium including executable instructions that, when executed by one or more processors of a device, cause the device to perform the method described above.

[0141] One implementation example provides a computer program product for implementation on a computer-readable storage medium, including code for performing the methods described above.

[0142] Other considerations for wireless communication networks

[0143] The techniques and methods described herein can be used in a variety of radio communication networks (or radio wide area networks (WWANs)) and radio access technologies (RATs). Although this document may use terms commonly associated with 3G, 4G, and / or 5G (e.g., 5G New Radio (NR)) radio technologies to describe aspects, the aspects of this disclosure are equally applicable to other communication systems and standards not explicitly mentioned herein.

[0144] 5G wireless communication networks can support a variety of advanced wireless communication services, such as enhanced mobile broadband (eMBB), millimeter wave (mmWave), machine-type communication (MTC), and / or mission-critical ultra-reliable low-latency communication (URLLC). These and other services may include latency and reliability requirements.

[0145] Return to Figure 1 Various aspects of this disclosure can be implemented in the example wireless communication system 100.

[0146] In 3GPP, depending on the context in which the term is used, the term "cell" can refer to the coverage area of ​​a Node B (NB) and / or the NB subsystem serving that coverage area. In NR systems, the term "cell" is used interchangeably with BS, Next Generation Node B (gNB or gNodeB), Access Point (AP), Distributed Unit (DU), Carrier, or Transmitter Receiver Point (TRP). A BS can provide communication coverage to macrocells, picocells, femtocells, and / or other cell types.

[0147] Macro cells typically cover a relatively large geographic area (e.g., a radius of several kilometers) and allow unrestricted access for UEs with service subscriptions. Pico cells cover a relatively small geographic area and allow unrestricted access for UEs with service subscriptions. Femto cells cover a relatively small geographic area (e.g., a home) and allow restricted access for UEs associated with that femto cell (e.g., UEs in a Closed Subscriber Group (CSG) and UEs belonging to users in a home). A BS used for a macro cell can be called a macro BS. A BS used for a pico cell can be called a pico BS. A BS used for a femto cell can be called a femto BS or a home BS.

[0148] Base station 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) can interact with EPC 160 via a first backhaul link 132 (e.g., S1 interface). Base station 102 configured for 5G (e.g., 5G NR or Next Generation RAN (NG-RAN)) can interact with core network 190 via a second backhaul link 184. Base station 102 can communicate with each other directly or indirectly (e.g., via EPC 160 or core network 190) via a third backhaul link 134 (e.g., X2 interface). The third backhaul link 134 can generally be wired or wireless.

[0149] Cell 102' can operate in licensed and / or unlicensed spectrum. When operating in unlicensed spectrum, cell 102' can employ NR and use the same 5 GHz unlicensed spectrum as Wi-Fi AP 150. Employing NR in unlicensed spectrum can extend the coverage and / or increase the capacity of the access network.

[0150] Some base stations, such as gNB 180, can operate in the conventional sub-6 GHz spectrum at millimeter wave (mmWave) frequencies and / or communicate with UE 104 at near-mmWave frequencies. When the gNB 180 operates at mmWave or near-mmWave frequencies, it can be referred to as an mmWave base station.

[0151] A communication link 120 between base station 102 and, for example, UE 104 can use one or more carriers. For example, base station 102 and UE 104 can use a spectrum of up to Y MHz (e.g., 5 MHz, 10 MHz, 15 MHz, 20 MHz, 100 MHz, 400 MHz, and other MHz) bandwidth allocated to each carrier in carrier aggregation for transmission in each direction, totaling up to Yx MHz (x component carriers). Carriers can be adjacent to each other or not. Carrier allocation can be asymmetrical relative to DL and UL (e.g., more or fewer carriers can be allocated to DL compared to UL). Component carriers can include primary component carriers and one or more secondary component carriers. The primary component carrier can be referred to as the primary cell (PCell), while the secondary component carrier can be referred to as the secondary cell (SCell).

[0152] The wireless communication system 100 also includes a Wi-Fi access point (AP) 150, which communicates with a Wi-Fi station (STA) 152 via a communication link 154 in, for example, unlicensed spectrum at 2.4 GHz and / or 5 GHz. When communicating in unlicensed spectrum, the STA 152 / AP 150 can perform a free channel assessment (CCA) before communication to determine whether the channel is available.

[0153] Some UEs 104 may communicate with each other using device-to-device (D2D) communication link 158. D2D communication link 158 may use DL / UL WWAN spectrum. D2D communication link 158 may use one or more sidelink channels, such as Physical Sidelink Broadcast Channel (PSBCH), Physical Sidelink Discovery Channel (PSDCH), Physical Sidelink Shared Channel (PSSCH), and Physical Sidelink Control Channel (PSCCH). D2D communication may be conducted through a variety of wireless D2D communication systems, such as, for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, 4G (e.g., LTE), or 5G (e.g., NR), to name just a few.

[0154] EPC 160 may include a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172. MME 162 can communicate with the Home Subscriber Server (HSS) 174. MME 162 is the control node that handles signaling between UE 104 and EPC 160. Generally, MME 162 provides bearer and connection management.

[0155] Typically, user Internet Protocol (IP) packets are transmitted through Serving Gateway 166, which is itself connected to PDN Gateway 172. PDN Gateway 172 provides UE IP address allocation and other functions. PDN Gateway 172 and BM-SC 170 are connected to IP Service 176, which may include, for example, the Internet, intranet, IP Multimedia Subsystem (IMS), PS streaming service, and / or other IP services.

[0156] The BM-SC 170 provides functionality for MBMS user service provisioning and delivery. It can serve as an entry point for content provider MBMS transmissions, authorize and initiate MBMS bearer services within a Public Land Mobile Network (PLMN), and schedule MBMS transmissions. The MBMS gateway 168 can allocate MBMS services to base station 102 within a Broadcast-Specific Service Multicast Single Frequency Network (MBSFN) area, and is responsible for session management (start / stop) and collecting billing information related to eMBMS.

[0157] The core network 190 may include Access and Mobility Management Functions (AMF) 192, other AMFs 193, Session Management Functions (SMF) 194, and User Plane Functions (UPF) 195. AMF 192 may communicate with Unified Data Management (UDM) 196.

[0158] AMF 192 is typically the control node that handles signaling between UE 104 and the core network 190. Generally, AMF192 provides QoS flow and session management.

[0159] All user Internet Protocol (IP) packets are transmitted through UPF 195, which connects to IP service 197 and provides UE IP address allocation and other functions for core network 190. IP service 197 may include, for example, the Internet, intranet, IP Multimedia Subsystem (IMS), PS streaming service, and / or other IP services.

[0160] Return to Figure 2 It depicts BS 102 and UE 104 (e.g., Figure 1 Various example components of the wireless communication network 100 can be used to implement various aspects of this disclosure.

[0161] At BS 102, the transmitting processor 220 can receive data from the data source 212 and control information from the controller / processor 240. The control information can be used for the Physical Broadcast Channel (PBCH), Physical Control Format Indicator Channel (PCFICH), Physical Hybrid ARQ Indicator Channel (PHICH), Physical Downlink Control Channel (PDCCH), Group Common PDCCH (GC PDCCH), etc. In some examples, this data can be used for the Physical Downlink Shared Channel (PDSCH).

[0162] The Media Access Control (MAC)-Control Element (MAC-CE) is a MAC layer communication structure that can be used for the exchange of control commands between wireless nodes. The MAC-CE can be carried in shared channels, such as the Physical Downlink Shared Channel (PDSCH), Physical Uplink Shared Channel (PUSCH), or Physical Sidelink Shared Channel (PSSCH).

[0163] Processor 220 can process (e.g., encode and map symbols) the data and control information to obtain data symbols and control symbols, respectively. Transmitter processor 220 can also generate reference symbols, such as those for the primary synchronization signal (PSS), secondary synchronization signal (SSS), PBCH demodulation reference signal (DMRS), and channel state information reference signal (CSI-RS).

[0164] The transmit (TX) multiple-input multiple-output (MIMO) processor 230 can perform spatial processing (e.g., pre-decoding) on ​​data symbols, control symbols, and / or reference symbols (if applicable), and can provide output symbol streams to the modulators (MODs) in transceivers 232a-232t. Each modulator in transceivers 232a-232t can process its own output symbol stream (e.g., for OFDM) to obtain an output sample stream. Each modulator can further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The downlink signal from the modulators in transceivers 232a-232t can be transmitted via antennas 234a-234t respectively.

[0165] At UE 104, antennas 252a-252r can receive downlink signals from BS 102 and can accordingly provide the received signals to demodulators (DEMODs) in transceivers 254a-254r. Each demodulator in transceivers 254a-254r can modulate (e.g., filter, amplify, down-convert, and digitize) the corresponding received signal to obtain an input sample. Each demodulator can also process the input sample (e.g., for OFDM) to obtain the received symbols.

[0166] The MIMO detector 256 can obtain received symbols from all demodulators in transceivers 254a-254r, perform MIMO detection on the received symbols if applicable, and provide the detected symbols. The receiver processor 258 can process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for UE 104 to data sink 260, and provide decoding control information to controller / processor 280.

[0167] On the uplink, at UE 104, the transmitting processor 264 can receive and process data from data source 262 (e.g., for the Physical Uplink Shared Channel (PUSCH)) and control information from the controller / processor 280 (e.g., for the Physical Uplink Control Channel (PUCCH)). The transmitting processor 264 can also generate reference symbols for reference signals (e.g., for Sounding Reference Signals (SRS)). If applicable, the symbols from the transmitting processor 264 can be pre-decoded by the TX MIMO processor 266, further processed by the modulators in transceivers 254a-254r (e.g., for SC-FDM), and transmitted to BS 102.

[0168] At BS 102, uplink signals from UE 104 can be received by antennas 234a-t, processed by demodulators in transceivers 232a-232t, detected by MIMO detector 236 (if applicable), and further processed by receiver processor 238 to obtain decoded data and control information transmitted by UE 104. Receiver processor 238 can provide the decoded data to data sink 239 and the decoded control information to controller / processor 240.

[0169] Memory 242 and 282 can respectively store data and program code for BS 102 and UE 104.

[0170] Scheduler 244 can schedule UE for data transmission on downlink and / or uplink.

[0171] 5G can utilize Orthogonal Frequency Division Multiplexing (OFDM) with a cyclic prefix (CP) on both the uplink and downlink. 5G can also support half-duplex operation using Time Division Duplex (TDD). OFDM and Single-Carrier Frequency Division Multiplexing (SC-FDM) divide the system bandwidth into multiple orthogonal subcarriers, often referred to as tones and bins. Each subcarrier can be modulated with data. Modulation symbols can be transmitted in the frequency domain using OFDM and in the time domain using SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers can depend on the system bandwidth. In some examples, the minimum resource allocation, called a resource block (RB), can be 12 consecutive subcarriers. The system bandwidth can also be divided into subbands. For example, a subband can cover multiple RBs. NR can support a basic subcarrier spacing (SCS) of 15 kHz, and other SCSs can be defined relative to the basic SCS (e.g., 30 kHz, 60 kHz, 120 kHz, 240 kHz, etc.).

[0172] As mentioned above, Figures 3A-3D Describing such as Figure 1 Various example aspects of the data structures used in the wireless communication network 100.

[0173] In various aspects, the 5G frame structure can be Frequency Division Duplex (FDD), where subframes within a specific set of subcarriers (carrier system bandwidth) are dedicated to either DL (Deep Flow) or UL (Ultra-Low Flow). The 5G frame structure can also be Time Division Duplex (TDD), where subframes within a specific set of subcarriers (carrier system bandwidth) are dedicated to both DL and UL. Figure 3A and Figure 3CIn the provided example, it is assumed that the 5G frame structure is TDD, subframe 4 is configured with slot format 28 (mostly DL), where D is DL, U is UL, and X is used flexibly between DL / UL, and subframe 3 is configured with slot format 34 (primarily UL). Although subframes 3 and 4 are shown with slot formats 34 and 28 respectively, any particular subframe can be configured with any of the various available slot formats 0-61. Slot formats 0 and 1 are all DL and all UL, respectively. Other slot formats 2-61 include a mixture of DL, UL, and flexible symbols. The slot format is configured for the UE via the received Slot Format Indicator (SFI) (dynamically via DL Control Information (DCI) or semi-statically / statically via Radio Resource Control (RRC) signaling). It should be noted that the following description also applies to 5G frame structures as TDD.

[0174] Other wireless communication technologies may have different frame structures and / or different channels. A frame (10 ms) can be divided into 10 equal-sized subframes (1 ms). Each subframe may include one or more time slots. Subframes may also include mini-time slots, which may include 7, 4, or 2 symbols. In some examples, depending on the time slot configuration, each time slot may include 7 or 14 symbols.

[0175] For example, for slot configuration 0, each slot can include 14 symbols, while for slot configuration 1, each slot can include 7 symbols. Symbols on the DL can be Cyclic Prefix (CP) OFDM (CP-OFDM) symbols. Symbols on the UL can be CP-OFDM symbols (for high-throughput scenarios) or Discrete Fourier Transform (DFT) Extended OFDM (DFT-s-OFDM) symbols (also known as Single Carrier Frequency Division Multiple Access (SC-FDMA) symbols) (for power-constrained scenarios; limited to single-stream transmission).

[0176] The number of time slots within a subframe is based on the time slot configuration and numerical parameters. For time slot configuration 0, different numerical parameters (µ) 0 to 5 allow for 1, 2, 4, 8, 16, and 32 time slots per subframe, respectively. For time slot configuration 1, different numerical parameters 0 to 2 allow for 2, 4, and 8 time slots per subframe, respectively. Therefore, for time slot configuration 0 and numerical parameter µ, there are 14 symbols / time slot per slot, and 2µ time slots / subframe per subframe. The subcarrier spacing and symbol length / duration are functions of the numerical parameters. The subcarrier spacing can be equal to... kHz, where μ is a digital parameter from 0 to 5. Similarly, digital parameters... It has a subcarrier spacing of 15 kHz and digital parameters It has a subcarrier spacing of 480 kHz. The symbol length / duration is inversely proportional to the subcarrier spacing. Figures 3A-3D An example of slot configuration 0 is provided, in which each slot has 14 symbols, and for the digital parameters... Each subframe has 4 time slots. The time slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs.

[0177] A resource grid can be used to represent the frame structure. Each time slot consists of a resource block (RB) that extends 12 consecutive subcarriers (also known as a physical RB (PRB)). The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0178] like Figure 3A As shown, some REs carry UEs (e.g., Figure 1 and Figure 2 The reference (pilot) signal (RS) for the UE (104) may include a demodulation RS (DMRS) (indicated as Rx for a particular configuration, where 100x is the port number, but other DMRS configurations are also possible) and a channel state information reference signal (CSI-RS) for channel estimation at the UE. The RS may also include a beam measurement RS (BRS), a beam refinement RS (BRRS), and a phase tracking RS (PT-RS).

[0179] Figure 3B The illustration shows examples of various DL channels within a subframe of a frame. The Physical Downlink Control Channel (PDCCH) carries the DCI within one or more Control Channel Elements (CCEs), each CCE comprising nine RE groups (REGs), each REG comprising four consecutive REs in OFDM symbols.

[0180] The primary synchronization signal (PSS) can be within symbol 2 of a specific subframe of the frame. The UE (e.g., Figure 1 and Figure 2 104) Use PSS to determine subframe / symbol timing and physical layer identifier.

[0181] The secondary synchronization signal (SSS) can be located within symbol 4 of a specific subframe of a frame. The UE uses the SSS to determine the physical layer cell identifier group number and radio frame timing.

[0182] Based on the Physical Layer Identifier and Physical Layer Cell Identifier Group Number, the UE can determine the Physical Cell Identifier (PCI). Based on the PCI, the UE can determine the location of the aforementioned DMRS. The Physical Broadcast Channel (PBCH) carrying the Master Information Block (MIB) can be logically grouped with the PSS and SSS to form a Synchronization Signal (SS) / PBCH block. The MIB provides many RBs in the system bandwidth and System Frame Number (SFN). The Physical Downlink Shared Channel (PDSCH) carries user data and broadcast system information not transmitted via the PBCH, such as System Information Blocks (SIBs) and paging messages.

[0183] like Figure 3C As shown, some REs carry DMRS (indicated as R for a specific configuration, but other DMRS configurations are also possible) for channel estimation at the base station. The UE can transmit DMRS for the Physical Uplink Control Channel (PUCCH) and DMRS for the Physical Uplink Shared Channel (PUSCH). PUSCH DMRS can be transmitted in the first one or two symbols before the PUSCH. PUCCH DMRS can be transmitted in different configurations depending on whether it is transmitted short or long and depending on the specific PUCCH format used. The UE can transmit a Sounding Reference Signal (SRS). SRS can be transmitted in the last symbol of a subframe. SRS can have a comb structure, and the UE can transmit SRS on one of the comb teeth. The base station can use SRS for channel quality estimation to enable frequency-dependent scheduling on the UL.

[0184] Figure 3D The illustration shows examples of various UL channels within a subframe of a frame. The PUCCH can be positioned as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicators (CQI), pre-decoding matrix indicators (PMI), rank indicators (RI), and HARQ ACK / NACK feedback. The PUCCH carries data and can additionally be used to carry buffer status reports (BSR), power headroom reports (PHR), and / or UCI.

[0185] Other precautions

[0186] The foregoing description provides examples of DMRS configurations in communication systems. The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. The examples discussed herein do not limit the scope, applicability, or aspects set forth in the claims. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. For example, changes may be made to the function and arrangement of the elements discussed without departing from the scope of this disclosure. Various processes or components may be appropriately omitted, substituted, or added to the various examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined in some other examples. For example, an apparatus or a method may be practiced using any number of aspects set forth herein. Moreover, the scope of this disclosure is intended to cover such apparatuses or methods practiced using structures, functions, or structures and functions other than or different from the aspects of this disclosure set forth herein. It should be understood that any aspect of the disclosure herein may be implemented by one or more elements of the claims.

[0187] The techniques described in this article can be used in various wireless communication technologies, such as 5G (e.g., 5G NR), 3GPP Long Term Evolution (LTE), LTE-A Advanced (LTE-A), 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), Time Division Synchronous Code Division Multiple Access (TD-SCDMA), and other networks. The terms "network" and "system" are often used interchangeably. CDMA networks can implement radio technologies such as Universal Terrestrial Radio Access (UTRA) and cdma2000. UTRA includes Wideband CDMA (WCDMA) and other CDMA variants. cdma2000 covers the IS-2000, IS-95, and IS-856 standards. TDMA networks can implement radio technologies such as Global System for Mobile Communications (GSM). OFDMA networks can implement radio technologies such as NR (e.g., 5G RA), evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). LTE and LTE-A are UMTS versions using E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization called the 3rd Generation Partnership Project (3GPP). cdma2000 and UMB are described in documents from an organization called the 3rd Generation Partnership Project 2 (3GPP2). NR is an emerging wireless communication technology under development.

[0188] The various illustrative logic blocks, modules, and circuits described in this disclosure may be implemented or performed using a general-purpose processor, DSP, ASIC, field-programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general-purpose processor may be a microprocessor, but alternatively, it may be any commercially available processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, a combination of one or more microprocessors and a DSP core, a system-on-a-chip (SoC), or any other such configuration.

[0189] If implemented in hardware, an example hardware configuration could include a processing system within a wireless node. This processing system could be implemented using a bus architecture. The bus can contain any number of interconnect buses and bridges, depending on the specific application and overall design constraints of the processing system. The bus can connect various circuitry, including processors, machine-readable media, and bus interfaces. The bus interface can be used to connect network adapters, etc., to the processing system via the bus. The network adapter can be used to implement signal processing functions at the PHY layer. When using user equipment (see...) Figure 1 In this case, the user interface (e.g., keyboard, display, mouse, joystick, touchscreen, biosensor, proximity sensor, light-emitting element, etc.) can also be connected to the bus. This bus can also link various other circuits well-known in the art, such as timing sources, peripheral devices, voltage regulators, power management circuits, etc., and therefore will not be described further. The processor can be implemented using one or more general-purpose and / or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuits capable of executing software. Those skilled in the art will recognize how the functions described for the processing system can be optimally implemented based on the specific application and the overall design constraints imposed on the system as a whole.

[0190] If implemented in software, the functions can be stored or transmitted as one or more instructions or codes on a computer-readable medium. Software should be broadly interpreted to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media includes computer storage media and communication media, with communication media including any medium that facilitates the transfer of computer programs from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on the machine-readable storage medium. The computer-readable storage medium may be coupled to the processor, allowing the processor to read information from and write information to the storage medium. Alternatively, the storage medium may be integrated with the processor. For example, the machine-readable medium may include a transmission line, a carrier wave modulated by data, and / or a computer-readable storage medium on which instructions separate from the wireless node are stored, all of which can be accessed by the processor via a bus interface. Alternatively or additionally, the machine-readable medium or any part thereof may be integrated into the processor, such as in cases where it may have a cache and / or a general-purpose register file. Examples of machine-readable storage media may include, for example, RAM (random access memory), flash memory, ROM (read-only memory), PROM (programmable read-only memory), EPROM (erasable programmable read-only memory), EEPROM (electrically erasable programmable read-only memory), registers, disks, optical disks, hard disks, or any other suitable storage media, or any combination thereof. The machine-readable medium may be included in a computer program product.

[0191] Software modules may include single or multiple instructions and may be distributed across several different code segments, across different programs, and across multiple storage media. Computer-readable media may include multiple software modules. A software module includes instructions that, when executed by a device such as a processor, cause the processing system to perform various functions. The software module may include transfer modules and receive modules. Each software module may reside in a single storage device or be distributed across multiple storage devices. For example, a software module may be loaded from a hard disk drive into RAM when a trigger event occurs. During the execution of a software module, the processor may load some instructions into a cache to improve access speed. One or more cache lines may then be loaded into a general-purpose register file for processor execution. When the functionality of a software module is mentioned below, it will be understood that this functionality is implemented by the processor when executing the instructions from that software module.

[0192] As used herein, the phrase “at least one” in a list of items refers to any combination of those items, including a single member. As an example, “at least one of a, b, or c” is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combination with multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other order of a, b, and c).

[0193] As used herein, the term "determine" encompasses a variety of actions. For example, "determine" can include operations, calculations, processing, derivation, investigation, searching (e.g., looking in a table, database, or other data structure), ascertaining, etc. Furthermore, "determine" can include receiving (e.g., receiving information), accessing (e.g., accessing data in memory), etc. Additionally, "determine" can include parsing, selecting, picking, building, etc.

[0194] The methods disclosed herein include one or more steps or actions for implementing the method. The method steps and / or actions may be interchanged without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and / or use of a particular step and / or action may be modified without departing from the scope of the claims. Furthermore, the various operations of the methods described above can be performed by any suitable component capable of performing the corresponding function. The apparatus may include various hardware and / or (multiple) software components and / or (multiple) modules, including but not limited to circuits, application-specific integrated circuits (ASICs), or processors. Typically, where operations as shown in the figures are present, those operations may have corresponding components with similar numbering plus functional components.

[0195] The following claims are not intended to be limited to the aspects shown herein, but are consistent with the full scope of the language of the claims. In the claims, unless specifically stated otherwise, an element referred to in the singular does not mean “one and only one,” but rather “one or more.” Unless otherwise specifically stated, the term “some” means one or more. No claim element is interpreted pursuant to the provisions of 35 USC §112(f) unless the element is explicitly stated using the phrase “component for…” or, in the case of a method claim, the element is stated using the phrase “step for…”. All structural and functional equivalents of elements throughout the various aspects described in this disclosure that are known or will be known hereafter by one of ordinary skill in the art are expressly incorporated herein by reference and are intended to be covered by the claims. Furthermore, nothing disclosed herein is intended to be contributed to the public, whether or not such disclosure is expressly stated in the claims.

Claims

1. A method for wireless communications by a first wireless node, comprising: selecting a type of demodulation reference signal (DMRS) sequence to use for communications with a second wireless node based on a signal quality associated with the communications, wherein selecting the type of DMRS sequence based on the signal quality comprises selecting a length of the DMRS sequence based at least in part on a Doppler spread associated with the communications; generating a message having the type of DMRS sequence; and transmitting the message to the second wireless node.

2. The method of claim 1, further comprising: determining a modulation and coding scheme (MCS) to use for communications with the second wireless node, wherein selecting the type of DMRS sequence comprises selecting the type of DMRS sequence based on the MCS.

3. The method of claim 2, wherein: if the MCS is a first MCS, the selected type of DMRS sequence comprises a pseudo-noise (PN) sequence; and if the MCS is a second MCS, the selected type of DMRS sequence comprises a Zadoff-Chu sequence, the second MCS having a higher order than the first MCS.

4. The method of claim 1, further comprising: transmitting an indication of the selected type of DMRS sequence to the second wireless node.

5. The method of claim 4, further comprising: communicating with the second wireless node using a default DMRS sequence type prior to transmitting the indication of the selected type of DMRS sequence.

6. The method of claim 1, wherein, selecting the type of DMRS sequence based on the signal quality comprises selecting the type of DMRS sequence based on a mapping between one or more candidate MCSs and one or more candidate DMRS sequence types.

7. The method of claim 6, further comprising: indicating the mapping to the second wireless node.

8. The method of claim 1, further comprising: receiving an indication from the second wireless node, wherein selecting the type of DMRS sequence is further based on the indication from the second wireless node.

9. The method of claim 8, wherein, the indication comprises a request for a type of DMRS sequence to use for the communications.

10. The method of claim 8, wherein, the indication comprises an indication of one or more signal quality parameters associated with the communications.

11. The method of claim 10, wherein, the one or more signal quality parameters comprise at least one of: a signal to interference plus noise ratio (SINR) parameter; or an indication of a Doppler spread associated with the communications.

12. The method of claim 8, wherein, the indication comprises an indication of a processing capability of the second wireless node.

13. The method of claim 8, wherein, the indication is received as part of channel state information (CSI) feedback.

14. A method for wireless communications by a first wireless node, comprising: selecting a type of demodulation reference signal (DMRS) sequence to use for communications with a second wireless node based on a signal quality associated with the communications, wherein selecting the type of DMRS sequence based on the signal quality comprises selecting a length of the DMRS sequence based at least in part on a Doppler spread associated with the communications; receiving a message from the second wireless node having the type of DMRS sequence; and performing channel estimation based on the type of DMRS sequence using the message.

15. The method of claim 14, further comprising: determining a modulation and coding scheme (MCS) to use for the communication with the second wireless node, wherein selecting the type of DMRS sequence comprises selecting the type of DMRS sequence based on the MCS.

16. The method of claim 15, wherein: if the MCS is a first MCS, the selected type of DMRS sequence comprises a pseudo-noise (PN) sequence; and if the MCS is a second MCS, the selected type of DMRS sequence comprises a Zadoff-Chu sequence, the second MCS having a higher order than the first MCS.

17. The method of claim 14, further comprising: receiving, from the second wireless node, an indication of the selected type of DMRS sequence.

18. The method of claim 17, further comprising: communicating with the second wireless node using a default DMRS sequence type prior to receiving the indication of the selected type of DMRS sequence.

19. The method of claim 14, wherein, selecting the type of DMRS sequence based on the signal quality comprises selecting the type of DMRS sequence based on a mapping between one or more candidate MCSs and one or more candidate DMRS sequence types.

20. The method of claim 19, further comprising: receiving, from the second wireless node, an indication of the mapping.

21. The method of claim 14, further comprising: sending, to the second wireless node, an indication of a request to select the type of DMRS sequence.

22. The method of claim 21, wherein, the indication comprises a request for a type of DMRS sequence to use for the communication.

23. The method of claim 21, wherein, the indication comprises an indication of one or more signal quality parameters associated with the communication.

24. The method of claim 23, wherein, the one or more signal quality parameters comprise at least one of: a signal to interference plus noise ratio (SINR) parameter; or an indication of a Doppler spread associated with the communication.

25. The method of claim 21, wherein, the indication comprises an indication of a processing capability of the second wireless node.

26. The method of claim 21, wherein, the indication is received as part of channel state information (CSI) feedback.

27. An apparatus for wireless communication by a first wireless node, comprising: at least one memory including instructions; and at least one processor configured to execute the instructions to cause the apparatus to: select a type of demodulation reference signal (DMRS) sequence to use for a communication with a second wireless node based on a signal quality associated with the communication, wherein selecting the type of DMRS sequence based on the signal quality comprises selecting a length of the DMRS sequence based at least in part on a Doppler spread associated with the communication; generate a message having the type of DMRS sequence; and send the message to the second wireless node.

28. An apparatus for wireless communication by a first wireless node, comprising: at least one memory including instructions; and at least one processor configured to execute the instructions to cause the apparatus to: select a type of demodulation reference signal (DMRS) sequence to use for a communication with a second wireless node based on a signal quality associated with the communication, wherein selecting the type of DMRS sequence based on the signal quality comprises selecting a length of the DMRS sequence based at least in part on a Doppler spread associated with the communication; receive, from the second wireless node, a message having the type of DMRS sequence; and perform channel estimation based on the DMRS sequence using the message.

29. A computer readable medium having program code embodied thereon, wherein, The program code can be executed by one or more processors of a wireless node to cause the one or more processors to perform the method of any of claims 1-13.

30. A computer readable medium having program code embodied thereon, wherein, The program code can be executed by one or more processors of a wireless node to cause the one or more processors to perform the method of any of claims 14-26.

31. A computer program product comprising computer readable instructions which, when executed by a processor, perform the method of any of claims 1-13.

32. A computer program product comprising computer readable instructions which, when executed by a processor, perform the method of any of claims 14-26.

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