Apparatus and method for enhanced DM-RS for enhanced PDCCH transmission using multiple beams from multiple TRPs

Abstract

Apparatuses and methods for enhanced DM-RS for enhanced PDCCH transmission using multiple beams from multiple TRPs are disclosed. The apparatus includes: a processor that determines a plurality of activated transmission configuration indication (TCI) states using a plurality of radio transmit-receive identities for transmission of a physical downlink control channel (PDCCH) using demodulation reference signals (DM-RS) in a control resource set (CORESET), where the CORESET includes a plurality of transmission units having a predefined granularity; and determines, based on a TCI state mapping scheme, one of the TCI states to be used for each of the transmission units and its corresponding DM-RS; and a transmitter that transmits media access control (MAC) control elements (CEs) for activating each of the TCI states; and transmits the PDCCH using the plurality of radio transmit-receive identities through the transmission units and the corresponding DM-RS having the corresponding TCI states determined by the processor.

Description

Technical Field

[0001] The subject matter disclosed herein generally relates to wireless communication and, more particularly, but not limited to, apparatuses and methods for enhanced demodulation reference signals (DM-RS) for enhanced physical downlink control channel (PDCCH) transmissions that utilize multiple beams from multiple transmit and receive points (TRPs). Background Art

[0002] The following abbreviations and acronyms are defined herein, at least some of which are referred to in the specification.

[0003] 3rd Generation Partnership Project (3GPP), 5th Generation (5G), New Radio (NR), 5G Node B / Generalized Node B (gNB), Long Term Evolution (LTE), LTE-Advanced (LTE-A), E-UTRAN Node B / Evolved Node B (eNB), Universal Mobile Telecommunications System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX), Evolved UMTS Terrestrial Radio Access Network (E-UTRAN), Wireless Local Area Network (WLAN), Orthogonal Frequency Division Multiplexing (OFDM), Single Carrier Frequency Division Multiple Access (SC-FDMA), Downlink (DL), Uplink (UL), User Entity / Device (UE), Network Equipment (NE), Radio Access Technology (RAT), Receive or Receiver (RX), Transmit or Transmitter (TX), Physical Downlink Control Channel (PDCCH), Physical Downlink Shared Channel (PDSCH), Control Channel Element (CCE), Control Element (CE), Control Resource Set (CORESET), Cyclic Redundancy Check (CRC), Downlink Control Information (DCI), Frequency Division Multiple Access (FDMA), Identity (ID), Medium Access Control (MAC), Multiple Input Multiple Output (MIMO), Multi-User MIMO (MU-MIMO), Physical Resource Block (PRB), Quadrature Phase Shift Keying (QPSK), Resource Block (RB), Resource Element (RE), Resource Element Group (REG), Reference Signal (RS), Subcarrier Spacing (SCS), Transmit and Receive Point (TRP), Ultra-Reliable Low-Latency Communication (URLLC), Frequency Range 1 (FR1), Frequency Range 2 (FR2), Transmission Configuration Indicator (TCI), Demodulation Reference Signal (DM-RS), Information Element (IE).

[0004] In wireless communication such as a 3rd Generation Partnership Project (3GPP) mobile network, a wireless mobile network may provide seamless wireless communication services to a wireless communication terminal with mobility, i.e., a user equipment (UE). The wireless mobile network may be formed by multiple base stations and the base stations may perform wireless communication with the UE.

[0005] 5G New Radio (NR) is the latest in the 3GPP standard series and supports very high data rates and lower latency compared to its predecessor LTE (4G) technology. Two types of frequency ranges (FR) are defined in 3GPP. Frequencies in the sub-6 GHz range (from 450 to 6000 MHz) are called FR1, and the millimeter wave range (from 24.25 GHz to 52.6 GHz) is called FR2. 5G NR supports both FR1 and FR2 frequency bands.

[0006] Enhancements to multi-TRP / panel transmission were studied, including improved reliability and stability in the case of ideal and non-ideal backhaul between these TRPs. A TRP is a device that transmits and receives signals and is controlled by the gNB via the backhaul between the gNB and the TRP. A TRP can also be referred to as a Radio Transmit-Receive Identity, or simply an Identity.

[0007] In the current NR system, the Physical Downlink Control Channel (PDCCH) is transmitted from a single TRP. Additional transmission resources are introduced in the spatial domain by different beams from different TRPs, so enhanced transmission of the PDCCH for multiple TRPs is desirable, for example, to increase PDCCH capacity and / or improve PDCCH stability. Therefore, enhanced Physical Downlink Control Channel Demodulation Reference Signal (DM-RS) is also desirable for enhanced PDCCH transmission. Summary of the Invention

[0008] Apparatus and methods for enhanced DM-RS for enhanced PDCCH transmission using multiple beams from multiple TRPs are disclosed.

[0009] According to a first aspect, there is provided an apparatus comprising: a processor that determines a plurality of active Transmission Configuration Indicator (TCI) states using a plurality of Radio Transmit-Receive Identities for transmission of a Physical Downlink Control Channel (PDCCH) using Demodulation Reference Signals (DM-RS) in a Control Resource Set (CORESET), where the CORESET includes a plurality of transmission units with a predefined granularity; and determines, based on a TCI state mapping scheme, one TCI state in the TCI states to be used for each of the transmission units and its corresponding DM-RS; and a transmitter that transmits Media Access Control (MAC) Control Elements (CE) for activating each of the TCI states; and transmits the PDCCH using the plurality of Radio Transmit-Receive Identities via the transmission units and the corresponding DM-RS having the corresponding TCI states determined by the processor.

[0010] According to a second aspect, there is provided an apparatus, comprising: a receiver that receives a media access control (MAC) control element (CE) for activating a plurality of transmission configuration indication (TCI) states; and receives a physical downlink control channel (PDCCH) using a demodulation reference signal (DM-RS) in a control resource set (CORESET), where the CORESET includes a plurality of transmission units having a predefined granularity, and the PDCCH is received through the transmission units and the DM-RS, and each of the transmission units and its corresponding DM-RS have a corresponding TCI state; and a processor that determines that the PDCCH is transmitted from a transmitting device using a plurality of radio transmit-receive identities; and estimates a channel condition for PDCCH demodulation using the received DM-RS and the corresponding TCI state based on a TCI state mapping scheme.

[0011] According to a third aspect, there is provided a method, comprising: determining, by a processor, a plurality of activated transmission configuration indication (TCI) states using a plurality of radio transmit-receive identities for transmission of a physical downlink control channel (PDCCH) using a demodulation reference signal (DM-RS) in a control resource set (CORESET), where the CORESET includes a plurality of transmission units having a predefined granularity; determining, by the processor, a TCI state to be used for each of the transmission units and its corresponding DM-RS based on a TCI state mapping scheme; transmitting, by a transmitter, a media access control (MAC) control element (CE) for activating each of the TCI states; and transmitting, by the transmitter, the PDCCH using a plurality of radio transmit-receive identities through the transmission units and the corresponding DM-RS having the corresponding TCI state as determined by the processor.

[0012] According to a fourth aspect, there is provided a method, comprising: receiving, by a receiver, a media access control (MAC) control element (CE) for activating a plurality of transmission configuration indication (TCI) states; receiving, by the receiver, a physical downlink control channel (PDCCH) using a demodulation reference signal (DM-RS) in a control resource set (CORESET), where the CORESET includes a plurality of transmission units having a predefined granularity, and the PDCCH is received through the transmission units and the DM-RS, and each of the transmission units and its corresponding DM-RS have a corresponding TCI state; determining, by a processor, that the PDCCH is transmitted from a transmitting device using a plurality of radio transmit-receive identities; and estimating, by the processor, a channel condition for demodulating the PDCCH using the received DM-RS and the corresponding TCI state based on a TCI state mapping scheme. Description of the Drawings

[0013] A more specific description of the embodiments is provided below by reference to specific embodiments illustrated in the accompanying drawings. In view of the fact that these drawings only depict some embodiments and are thus not to be considered as limiting the scope, the embodiments are described and explained below with additional specificity and detail by using the drawings, wherein:

[0014] Figure 1 is a schematic diagram illustrating a wireless communication system according to some embodiments of the present disclosure;

[0015] Figure 2 is a schematic block diagram illustrating components of a user equipment (UE) according to some embodiments of the present disclosure;

[0016] Figure 3 is a schematic block diagram illustrating components of a network device (NE) according to some embodiments of the present disclosure;

[0017] Figure 4 is a schematic diagram illustrating restricted PDCCH resources for a UE with a high aggregation level in the case of a small bandwidth configuration;

[0018] Figure 5 is a schematic diagram illustrating an example of PDCCH resource mapping with an interleaved single TRP;

[0019] Figure 6A is a schematic diagram illustrating an example of TCI state indication for a UE-specific PDCCH media access control (MAC) control element (CE) for a single TRP;

[0020] Figure 6B is a schematic diagram illustrating an example of TCI state indication for a UE-specific PDCCH MAC CE in the case of enhanced PDCCH transmission;

[0021] Figure 6C is a schematic diagram illustrating another example of TCI state indication for a UE-specific PDCCH MAC CE in the case of enhanced PDCCH transmission;

[0022] Figure 7 is a schematic diagram illustrating an example of determination of PDCCH DM-RS TCI state and DM-RS port index for multi-TRP transmission using resource element group (REG)-level spatial division multiplexing (SDM);

[0023] Figure 8 is a schematic diagram illustrating an example of determination of PDCCH DM-RS TCI state and DM-RS port index for multi-TRP transmission using control channel element (CCE)-level spatial division multiplexing (SDM);

[0024] Figure 9It is a schematic diagram showing an example of determining the PDCCH DM-RSTCI state for multi-TRP transmission using REG bundling group level frequency division multiplexing (FDM);

[0025] Figure 10 It is a schematic diagram showing an example of determining the PDCCH DM-RS TCI state for CCE level frequency division multiplexing (FDM) in multi-TRP transmission;

[0026] Figure 11 It is a flowchart showing the steps of transmitting enhanced DM-RS for enhanced PDCCH transmission using multiple beams from multiple TRPs by the NE; and

[0027] Figure 12 It is a flowchart showing the steps of receiving enhanced DM-RS for enhanced PDCCH transmission using multiple beams from multiple TRPs by the UE. Detailed implementation mode

[0028] As those skilled in the art will understand, various aspects of the embodiments can be embodied as a system, device, method, or program product. Therefore, the embodiments can take the form of an all-hardware embodiment, an all-software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects.

[0029] For example, the disclosed embodiments can be implemented as hardware circuits, including custom very large scale integration (VLSI) circuits or gate arrays, existing semiconductors such as logic chips, transistors, or other discrete components. The disclosed embodiments can also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, etc. As another example, the disclosed embodiments can include one or more physical or logical blocks of executable code, for example, organized as objects, procedures, or functions.

[0030] In addition, one or more embodiments can take the form of a program product embodied in one or more computer-readable storage devices that store machine-readable code, computer-readable code, and / or program code, hereinafter referred to as "code". The storage device can be tangible, non-transitory, and / or non-transmissive.

[0031] Any combination of one or more computer-readable media can be utilized. The computer-readable medium can be a computer-readable storage medium. The computer-readable storage medium can be a storage device for storing code. The storage device can be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micro-mechanical, or semiconductor system, apparatus, or device, or any suitable combination of the above.

[0032] A non-exhaustive list of more specific examples of storage devices can include the following: electrical connections with one or more wires, portable computer floppy disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), portable compact disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing. In the context of this document, a computer-readable storage medium can be any tangible medium that is capable of containing or storing a program for use by or in connection with an instruction execution system, apparatus, or device.

[0033] References in this specification to "one embodiment", "an embodiment", "an example", "some embodiments", "some examples", or similar language mean that a particular feature, structure, or characteristic is included in at least one embodiment or example. Thus, instances of the phrases "in one embodiment", "in an example", "in some embodiments", and similar language throughout the specification may, but do not necessarily, all refer to the same (one or more) embodiment. It may include some or all of the disclosed embodiments. Unless otherwise expressly stated, features, structures, elements, or characteristics described in connection with one or some embodiments are also applicable to other embodiments. Unless otherwise expressly stated, the terms "comprises", "comprising", "has", and their variants mean "including but not limited to".

[0034] Unless otherwise expressly stated, the listed items in a list do not imply that any or all of the items are mutually exclusive. Unless otherwise expressly stated, the terms "a", "an", and "the" also mean "one or more".

[0035] It should be understood that the term "and / or" as used herein refers to and includes any and all possible combinations of one or more of the associated listed items. For example, "A and / or B" can refer to any one of the following three combinations: only A exists, only B exists, and A and B coexist.

[0036] The character " / " generally indicates an "or" relationship between related items, but can also include an "and" relationship between related items. For example, "A / B" means "A or B", which can also include the coexistence of A and B, unless the context otherwise indicates.

[0037] Throughout the disclosure, the terms "first", "second", "third", etc. are used solely as terms of reference to relevant devices, components, program steps, etc., and do not denote any spatial or temporal order, unless expressly stated otherwise. For example, "a first device" and "a second device" may refer to two separately formed devices, or two parts or components of the same device. In some cases, for example, "a first device" and "a second device" may be the same and may be arbitrarily named. Similarly, the "first step" of a method or process may be performed or carried out after or simultaneously with the "second step".

[0038] Furthermore, the features, structures, or characteristics of the described embodiments may be combined in any suitable manner. In the following description, numerous specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of the embodiments. However, those skilled in the relevant art will recognize that the embodiments may be practiced without one or more of the specific details or by other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the embodiments.

[0039] Aspects of various embodiments are described below with reference to schematic flowcharts and / or schematic block diagrams of methods, devices, systems, and program products. It will be understood that each step in the schematic flowcharts and / or schematic block diagrams, as well as combinations of steps in the schematic flowcharts and / or schematic block diagrams, can be implemented by code. This code can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine such that instructions executed by the processor of the computer or other programmable data processing device create a means for implementing the functions or actions specified in the schematic flowcharts and / or schematic block diagrams.

[0040] The code can also be stored in a storage device that can direct a computer, other programmable data processing device, or other device to operate in a particular manner such that the instructions stored in the storage device produce an article of manufacture including instructions for implementing the functions or actions specified in the schematic flowcharts and / or schematic block diagrams.

[0041] The code can also be loaded onto a computer, other programmable data processing apparatus, or other device so that a series of operational steps are performed on the computer, other programmable device, or other device to produce a computer-implemented process such that the code executed on the computer or other programmable device provides a process for implementing the functions or actions specified in the schematic flowcharts and / or schematic block diagrams.

[0042] The schematic flowcharts and / or schematic block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of the possible implementations of different apparatuses, systems, methods, and program products according to various embodiments. To this end, each step in the schematic flowchart and / or schematic block diagram may represent a module, segment, or portion of code that includes one or more executable instructions for implementing the specified logical function(s). However, those skilled in the relevant art will recognize that the flowchart need not be practiced in the order shown and can be practiced without one or more of the specific steps or with other steps not shown.

[0043] It should also be noted that in some alternative implementations, the functions recited in the identified boxes may not occur in the order mentioned in the accompanying drawings. For example, depending on the functions involved, two steps shown in succession may actually be executed simultaneously, or sometimes may be executed in the reverse order. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps or portions of the steps illustrated in the accompanying drawings.

[0044] The description of an element in each drawing may refer to the elements of the previous drawings. In all the drawings, the same reference numerals denote the same elements, including alternative embodiments of the same elements.

[0045] Figure 1 is a schematic diagram illustrating a wireless communication system. It depicts an embodiment of a wireless communication system 100 having multiple TRPs 104a. In one embodiment, the wireless communication system 100 may include a user equipment (UE) 102 and a network device (NE) 104. Although a specific number of UEs 102 and NEs 104 are depicted in Figure 1 those skilled in the art will recognize that any number of UEs 102 and NEs 104 may be included in the wireless communication system 100.

[0046] The UE 102 may be referred to as a remote device, remote unit, subscriber unit, mobile station, mobile terminal, user, terminal, mobile terminal, fixed terminal, subscriber station, user terminal, apparatus, device, or other terms used in the art.

[0047] In one embodiment, the UE 102 can be an autonomous sensor device, an alarm device, an actuator device, a remote control device, etc. In some other embodiments, the UE 102 can include a computing device, such as a desktop computer, a laptop computer, a personal digital assistant (PDA), a tablet computer, a smart phone, a smart TV (e.g., a TV connected to the Internet), a set-top box, a gaming console, a security system (including security cameras), an in-vehicle computer, a network device (e.g., a router, a switch, a modem), etc. In some embodiments, the UE 102 includes a wearable device, such as a smart watch, a fitness band, an optical head-mounted display, etc. The UE 102 can communicate directly with one or more NEs 104.

[0048] The NE 104 can also be referred to as a base station, an access point, an access terminal, a base station, a Node-B, an eNB, a gNB, a home Node-B, a relay node, a device, an apparatus, or any other term used in the art. Throughout the specification, references to a base station can represent any one of the above reference types of the network device 104 such as an eNB and a gNB.

[0049] The NEs 104 can be distributed over a geographical area. The NE 104 is generally part of a radio access network that includes one or more controllers communicatively coupled to one or more corresponding NEs 104. The radio access network is generally communicatively coupled to one or more core networks, which can be coupled to other networks such as the Internet and the public switched telephone network. These and other elements of the radio access and core networks are not shown but are well known to those of ordinary skill in the art.

[0050] In one implementation, the wireless communication system 100 complies with 3GPP 5G New Radio (NR). In some implementations, the wireless communication system 100 complies with 3GPP protocols, where the NE 104 uses an OFDM modulation scheme to transmit on the DL, and the UE 102 uses an SC-FDMA scheme or an OFDM scheme to transmit on the UL. However, more generally, the wireless communication system 100 can implement some other open or proprietary communication protocols, e.g., WiMAX. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol.

[0051] The NE 104 can serve multiple UEs 102 within the service area of, for example, a cell (or a cell sector) or more cells via a wireless communication link. The NE 104 transmits DL communication signals to serve the UEs 102 in the time domain, the frequency domain, and / or the spatial domain.

[0052] A communication link is provided between the NE 104 and the UEs 102a, 102b, 102c, and 102d, which can be, for example, an NR UL or DL communication link. Some UEs 102 can communicate with different radio access technologies (RATs) simultaneously, such as NR and LTE.

[0053] A direct or indirect communication link can be provided between two or more NEs 104.

[0054] The NE 104 can also include one or more transmit-receive points (TRPs) 104a. In some embodiments, the network device can be a gNB 104 that controls multiple TRPs 104a. Additionally, there is a backhaul between two TRPs 104a. In some other embodiments, the network device can be a TRP 104a controlled by a gNB.

[0055] Communication links are provided between the NEs 104, 104a and the UEs 102, 102a respectively, which can be, for example, NR UL / DL communication links. Some UEs 102, 102a can communicate with different radio access technologies (RATs) simultaneously, such as NR and LTE.

[0056] In some embodiments, the UE 102a can be capable of communicating simultaneously with two or more TRPs 104a that utilize non-ideal backhaul. The TRP can be a transmission point of a gNB. The UE and / or one or more TRPs can use multiple beams. Two or more TRPs can be TRPs of different gNBs or can be of the same gNB.

[0057] Figure 2 is a schematic block diagram illustrating components of a user equipment (UE) according to one embodiment. The UE 200 can include a processor 202, a memory 204, an input device 206, a display 208, and a transceiver 210. In some embodiments, the input device 206 and the display 208 are combined into a single device, such as a touch screen. In certain embodiments, the UE 200 may not include any input device 206 and / or display 208. In various embodiments, the UE 200 can include one or more processors 202 and may not include the input device 206 and / or display 208.

[0058] In one embodiment, the processor 202 may include any known controller capable of executing computer-readable instructions and / or capable of performing logical operations. For example, the processor 202 may be a microcontroller, a microprocessor, a central processing unit (CPU), a graphics processing unit (GPU), an auxiliary processing unit, a field programmable gate array (FPGA), or a similar programmable controller. In some embodiments, the processor 202 executes instructions stored in the memory 204 to perform the methods and routines described herein. The processor 202 is communicatively coupled to the memory 204 and the transceiver 210.

[0059] In one embodiment, the memory 204 is a computer-readable storage medium. In some embodiments, the memory 204 includes volatile computer storage media. For example, the memory 204 may include RAM, which includes dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), and / or static RAM (SRAM). In some embodiments, the memory 204 includes non-volatile computer storage media. For example, the memory 204 may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory 204 includes both volatile and non-volatile computer storage media. In some embodiments, the memory 204 stores data related to trigger conditions for transmitting measurement reports to a network device. In some embodiments, the memory 204 also stores program code and related data.

[0060] In one embodiment, the input device 206 may include any known computer input device, including a touch panel, buttons, a keyboard, a stylus, a microphone, etc. In some embodiments, the input device 206 may be integrated with the display 208, for example, as a touch screen or a similar touch-sensitive display. In some embodiments, the input device 206 includes a touch screen such that text can be input using a virtual keyboard displayed on the touch screen and / or by handwriting on the touch screen. In some embodiments, the input device 206 includes two or more different devices, such as a keyboard and a touch panel.

[0061] In one embodiment, the display 208 can include any known electronically controllable display or display device. The display 208 can be designed to output visual, audio, and / or tactile signals. In some embodiments, the display 208 includes an electronic display capable of outputting visual data to a user. For example, the display 208 can include, but is not limited to, an LCD display, an LED display, an OLED display, a projector, or a similar display device capable of outputting images, text, etc. to a user. As another non-limiting example, the display 208 can include a wearable display such as a smartwatch, smart glasses, a head-up display, etc. Additionally, the display 208 can be a component of a smartphone, a personal digital assistant, a television, a desktop computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, etc.

[0062] In certain embodiments, the display 208 includes one or more speakers for generating sound. For example, the display 208 can generate an audio alert or notification (e.g., a beep or a ring). In some embodiments, the display 208 includes one or more tactile devices for generating vibration, movement, or other tactile feedback. In some embodiments, all or a portion of the display 208 can be integrated with the input device 206. For example, the input device 206 and the display 208 can form a touchscreen or a similar touch-sensitive display. In other embodiments, the display 208 can be positioned close to the input device 206.

[0063] In one embodiment, the transceiver 210 is configured to communicate wirelessly with a network device. In certain embodiments, the transceiver 210 includes a transmitter 212 and a receiver 214. The transmitter 212 is used to transmit UL communication signals to the network device, and the receiver 214 is used to receive DL communication signals from the network device.

[0064] The transmitter 212 and the receiver 214 can be any suitable type of transmitter and receiver. Although only one transmitter 212 and one receiver 214 are illustrated, the transceiver 210 can have any suitable number of transmitters 212 and receivers 214. For example, in some embodiments, the UE 200 includes multiple pairs of transmitters 212 and receivers 214 for communicating on multiple wireless networks and / or radio frequency bands, with each pair of transmitter 212 and receiver 214 being configured to communicate on a different wireless network and / or radio frequency band.

[0065] Figure 3FIG. 0 is a schematic block diagram illustrating components of a network device (NE) 300 according to one embodiment. The NE 300 may include a processor 302, a memory 304, an input device 306, a display 308, and a transceiver 310. As can be understood, in some embodiments, the processor 302, the memory 304, the input device 306, the display 308, and the transceiver 310 may be similar to the processor 202, the memory 204, the input device 206, the display 208, and the transceiver 210 of the UE 200, respectively.

[0066] In some embodiments, the processor 302 controls the transceiver 310 to transmit a DL signal or data to the UE 200. The processor 302 may also control the transceiver 310 to receive a UL signal or data from the UE 200. In another example, the processor 302 may control the transceiver 310 to transmit a DL signal containing various configuration data to the UE 200, as described above.

[0067] In one embodiment, the transceiver 310 is configured to communicate wirelessly with the UE 200. In certain embodiments, the transceiver 310 includes a transmitter 312 and a receiver 314. The transmitter 312 is used to transmit a DL communication signal to the UE 200, and the receiver 314 is used to receive a UL communication signal from the UE 200.

[0068] The transceiver 310 may communicate with multiple UEs 200 simultaneously. For example, the transmitter 312 may transmit a DL communication signal to the UE 200. As another example, the receiver 314 may receive UL communication signals from the UE 200 simultaneously. The transmitter 312 and the receiver 314 may be any suitable type of transmitter and receiver. Although only one transmitter 312 and one receiver 314 are illustrated, the transceiver 310 may have any suitable number of transmitters 312 and receivers 314. For example, the NE 300 may serve multiple cells and / or cell sectors, where the transceiver 310 includes a transmitter 312 and / or a receiver 314 for each cell or cell sector.

[0069] Figure 4 FIG. 13 is a schematic diagram illustrating restricted PDCCH resources for a high aggregation level UE in a small bandwidth configuration according to some embodiments of the present disclosure. In the current NR system, the physical downlink control channel (PDCCH) is transmitted from a single transceiver point (TRP) or a transmit and receive point (TRP). For small bandwidth configurations or for the case of multiple scheduled users via multi-user multiple input multiple output (MU-MIMO), the PDCCH capacity is limited. As Figure 4As shown in [figure], it is an example of a typical PDCCH configuration for FR2. For a 100M bandwidth and a 120K subcarrier spacing (SCS) for a UE capable of supporting aggregation level 8, the control resource set (CORESET) 400 has eleven (11) CCEs 412 in one OFDM symbol. This cannot support a UE with an aggregation level of 16 for a CORESET 400 with one OFDM symbol. That is, the PDCCH resources are insufficient for a UE with an aggregation level of 16 because there are only 11 CCEs. Additionally, for the ultra-reliable low-latency communication (URLLC) scenario, the reliability of the PDCCH can be further enhanced, where the enhancement for the physical downlink shared channel (PDSCH) has been carried out using multiple TRP transmissions.

[0070] The enhanced transmission of the PDCCH using multiple TRPs is the subject of an enhanced MIMO work item in Release 17. The PDCCH can be transmitted from multiple TRPs with many candidates in time-frequency resources, such as being transmitted simultaneously from multiple TRPs through spatial division multiplexing or from alternating TRPs through frequency division multiplexing / time division multiplexing. For these schemes, there are several problems based on the available PDCCH DM-RS designed in Release 15. First, multiple active PDCCH DM-RS TCI states are required for the enhanced PDCCH transmission using multiple TRPs, while only one TCI state can be activated for the PDCCH DM-RS in the current specification. Second, the TCI state for the PDCCH DM-RS can change according to the transmitted beam / TRP for the enhanced PDCCH transmission using multiple TRPs. Therefore, it is necessary to specify how to determine the TCI state to align the behavior between the gNB and the UE. Third, the interference between different PDCCH DM-RS ports from different beams can be randomized using different DM-RS sequences, and thus improve the demodulation performance. In Release 15, only the CORESET-specific PDCCH scrambling ID is configured, and thus according to the current specification, the same scrambling sequence can be used for different ports of the PDCCH DM-RS. Additionally, orthogonal DM-RS can be used to reduce the interference between different ports with different beams, and thus improve the demodulation performance.

[0071] Figure 5 is a schematic diagram illustrating an example of PDCCH resource mapping for a single TRP with interleaving according to some embodiments of the present disclosure. In Release 15, a detailed resource mapping scheme was specified for the PDCCH. Specifically, for a UE, it can be configured with multiple control resource sets (CORESETs), where each control resource set consists of resource blocks in the frequency domain and It consists of a number of symbols. The transmission resources in a CORESET 500 are divided into multiple REGs 532, and each of the multiple REGs 532 is equal to one resource block (RB or PRB) within one OFDM symbol. A REG or PRB is further composed of 12 resource elements (REs) 542. The REGs 532 within the CORESET are numbered in ascending order first in the time domain and then in the frequency domain. Six REGs form a control channel element (CCE) 512, and one or more CCEs can be aggregated for a PDCCH transmission. The supported aggregation levels are shown in Table 1 below.

[0072] Table 1 - Supported PDCCH Aggregation Levels.

[0073] Aggregation level Number of CCEs 1 1 2 2 4 4 8 8 16 16

[0074] As Figure 5 shown, the CORESET 500 consists of 24 PRBs and 2 OFDM symbols. There are a total of 48 REGs 532 in the CORESET. A PDCCH with an aggregation level of 2 uses 2 CCEs 512 for transmission, where each CCE 512 is composed of 6 REGs 532. In this mapping scheme, only the time-frequency two-dimensional resource mapping is specified. It does not support PDCCH transmissions from multiple TRPs, and thus the resource mapping for the spatial domain, e.g., the resource mapping for different beams / TRPs, is not specified.

[0075] Each CORESET can be associated with only one CCE-to-REG mapping. It can be in an interleaved or non-interleaved mode. When the interleaved mode is configured, as Figure 5 shown, based on the interleaving size defined by the higher layer configuration value interleaverSize, the REGs 532 of the interleaved CORESET 500a are interleaved with a row-column interleaver. The granularity of the interleaving unit is a REG bundle 522, which can also be referred to as a REG bundle group, where the bundle size is defined by the higher layer configuration value reg-BundleSize. In this disclosure, the terms "REG bundle" and "REG bundle group" can be used interchangeably and have the same meaning.

[0076] In Figure 5In the example shown, the REG bundle size, i.e., L, is 2 and the interleaver size, i.e., R, is 6. Thus, one CCE consists of 6 REGs from 3 interleaved REG bundle groups. Specifically, CCE 0 consists of an interleaved REG bundle group formed by REGs {0,1}, {2,3}, and {4,5}. CCE 1 consists of an interleaved REG bundle group formed by REGs {6,7}, {8,9}, and {10,11}. Other values of the REG bundle size L and the interleaver size R are also possible. For example, L can also be 3 or 6.

[0077] When the non-interleaved mode is configured, the REGs are not interleaved and the REG bundle size is fixed at 6. In Release 15, the interleaving is well-designed in the time-frequency domain. At least some of the proposed resource mapping schemes are compatible with this two-dimensional interleaving scheme.

[0078] Figure 6A is a schematic diagram showing an example of the TCI state indication for a UE-specific PDCCH medium access control (MAC) control element (CE) for a single TRP. In Release 15, for a CORESET, the list of TCI-States is configured as candidates for indicating the quasi-co-location information of the DM-RS ports for PDCCH reception. The network can indicate the TCI state for PDCCH reception of the CORESET of the serving cell by sending the TCI state indication for the UE-specific PDCCH MAC CE. Then, the MAC entity indicates the information about the TCI state indication for the UE-specific PDCCH MAC CE to the higher layer. Figure 6A Details for this UE-specific PDCCH MAC CE 600a are shown. In this example, the PDCCH MAC CE 600a includes a 5-bit serving cell ID 602, a 4-bit CORSET ID 604, and a 7-bit TCI state ID 606. Only one TCI state ID is indicated for the quasi-co-location information of the DM-RS ports for PDCCH reception. In the case of multi-beam / TRP transmission that requires information on multiple TCI states, it cannot provide sufficient TCI information. In addition, the actual TCI state may change according to the transmit beam / TRP during a PDCCH transmission. The determination of the TCI state needs to consider the enhanced PDCCH DM-RS design.

[0079] In the 3GPP Release 15 specification, the DM-RS sequence for the PDCCH on an OFDM symbol is defined by the following formula

[0080]

[0081] The pseudo-random sequence generator for c(i) shall be initialized using the following formula

[0082]

[0083] where l is the number of OFDM symbols in a time slot, is the number of time slots in a frame, and

[0084] - If provided, N ID ∈ {0, 1,..., 65535} is given by the higher layer parameter pdcch-DMRS-ScramblingID

[0085] - Otherwise

[0086] The PDCCH DM-RS is scrambled by the CORESET specific higher layer parameter pdcch-DMRS-ScramblingID (i.e., N ID or N_ID) which is defined in the RRC signaling for the ControlResourceSet. If different ports of the PDCCH DM-RS are from the same CORESET, the same DM-RS sequence is used for different ports. From the perspective of randomizing interference, this is not optimal and may have an impact on the DM-RS demodulation performance.

[0087] An example of the relevant Radio Resource Control (RRC) signaling can be provided as follows:

[0088]

[0089] The information element (IE) ControlResourceSet is used to configure the time / frequency control resource set (CORESET) where the downlink control information (DCI) is searched. A detailed description of the fields in the ControlResourceSet can be found in 3GPP specification TS 38.331. For example, resource element groups (REGs) can be bundled to create REG bundles. The parameter reg-BundleSize defines the size of such a bundle.

[0090] For PDCCH transmissions with multiple TRPs, support from UE capabilities is required. Specifically, for FR2, multiple panel receptions on the UE side are needed to receive enhanced PDCCHs transmitted using different beams from multiple TRPs. For FR1, multiple receivers are also needed to receive enhanced PDCCHs transmitted using different beams from multiple TRPs. Additionally, the UE can cut off some panels according to its requirements, e.g., power saving. The gNB needs to decide whether to activate the proposed PDCCH transmission scheme based on actual conditions such as the UE's capabilities and requirements, and the actual channel conditions from multiple candidate beams. Therefore, activation of enhanced PDCCH transmission requires a specific mechanism, where an implicit activation scheme can be used due to low signaling overhead.

[0091] Implicit rules can be defined to determine the PDCCH DM-RS TCI state for enhanced PDCCH transmission, where the TCI state is associated with a corresponding transmission unit (or transmission element, which can be used interchangeably in this disclosure) and the transmit beam / TRP. The transmission unit can be a CCE or a REG bundle group or a REG. Additionally, the N_ID for PDCCH scrambling is extended to multiple values to randomize interference between DM-RS ports from different beams / TRPs, where each value is associated with an activated TCI state and is used to determine the initial sequence of the PDCCH DM-RS transmitted from the linked beam / TRP. With some examples in this disclosure, accurate demodulation can be performed for PDCCH transmissions with multiple beams / TRPs for more diversity gain. Based on the implicit determination principle for determining the TCI state, the same multi-beam transmission behavior is achieved on the gNB and UE sides. There is no additional signaling overhead. Additionally, better performance is achieved by randomizing interference with different sequences of PDCCH DM-RS transmitted from different TRPs / beams.

[0092] A common step in some embodiments is to activate multiple TCI states for multi-TRP / beam transmission. Two or more TCI states need to be activated to indicate the quasi-co-location information of the DM-RS ports for PDCCH reception. In one example, two or more TCI states are indicated one by one for the UE-specific PDCCH MAC CE, which can be easily extended from the available PDCCH DM-RS TCI indication MAC CE. Additionally, the list of TCI-States for activating multiple TCI states may be different because the TCI states are associated with different beams or candidate beams from different TRPs.

[0093] Figure 6B is a schematic diagram showing an example of TCI state indication for the UE-specific PDCCH MAC CE in the case of enhanced PDCCH transmission. In as Figure 6BIn the example shown, the PDCCH MAC CE 600b includes a 5-bit serving cell ID 602, a 4-bit CORSET ID 604, two 7-bit TCI state IDs 606 and 608 each, and a reserved bit 610. TCI state 1 606 and TCI state 2 608 are used to indicate the TCI for enhanced PDCCH transmissions from two TRPs. In this example, TCI state 1 can be from the PDCCH tci-state list 1; while TCI state 2 can be from the PDCCH tci-state list 2, and the tci-state list 1 and the tci-state list 2 can be the same list or different lists. This example can be applicable to the case with a small number of active TCI states.

[0094] Figure 6C is a schematic diagram showing another example of TCI state indication for UE-specific PDCCH MAC CE in the case of enhanced PDCCH transmission. In as Figure 6C shown in the example, a TCI state group ID 612, which can be an index of a group consisting of multiple TCI states, can be used for PDCCH DM-RS TCI indication in the PDCCH MAC CE 600c. The TCI state group 612 can be activated by one MAC CE from a set of candidate TCI state lists configured by RRC. The TCI state group, for example, TCI state group 1, can be selected from a set of TCI state lists configured by RRC signaling. This example can be applicable to the case with a large number of active TCI states.

[0095] PDCCH DM-RS TCI states, DM-RS port indices, and implicit determination of DM-RS signals for multi-TRP transmission using spatial multiplexing Implicit determination

[0096] Figure 7 is a schematic diagram showing an example of determination of PDCCH DM-RS TCI states and DM-RS port indices for multi-TRP transmission using resource element group (REG) level spatial division multiplexing (SDM).

[0097] As Figure 7 shown, the CORESET includes a first resource set 702 for transmissions from TRP 0, and a second resource set 704 for transmissions from TRP 1. In two OFDM symbols 700a and 700b, each resource set includes a plurality of REGs, which are 48 in this example. Each REG can be associated with an identification number or REG ID, ranging from 0 to 47. This REG ID can be referred to as the local index of the REG. Since there are two sets of REGs, one from each of the TRPs, there are a total of 96 (48 x 2) REGs. The global index of the REG can be defined, ranging from 0 to 95. In as Figure 7In the example shown, the REG from TRP 0 with local index 0 can be mapped to global index 0; the REG from TRP 1 with local index 0 can be mapped to global index 1; the REG from TRP0 with local index 1 can be mapped to global index 2; the REG from TRP 1 with local index 1 can be mapped to global index 3; and so on.

[0098] Each CCE may include six REGs and may be associated with yet another identification number or CCE ID. Some examples of CCEs are shown as CCE 0, CCE 1, CCE 2, etc. In this example, a CCE may include REGs from two TRPs, for example, three REGs from each TRP. Based on the aggregation level, a preset number of CCEs may be grouped together to form a resource candidate. In this example, the aggregation level is 2, and thus each candidate resource includes two CCEs. For example, resource candidate 1712 includes CCE 0 and CCE 1; and resource candidate 2714 includes CCE 2 and CCE 3. The CCE ID indicates the CCE from two TRPs and can thus be referred to as the global index of the CCE.

[0099] Figure 8 is a schematic diagram illustrating an example for determining PDCCH DM-RS TCI states and DM-RS port indices for multi-TRP transmission utilizing control channel element (CCE)-level spatial division multiplexing (SDM).

[0100] As Figure 8 shown, the CORESET includes a first resource set 802 for transmissions from TRP 0, and a second resource set 804 for transmissions from TRP 1. In two OFDM symbols 800a and 800b, each resource set includes a plurality of REGs, which is 48 in this example. Each REG may be associated with an identification number or REG ID, ranging from 0 to 47.

[0101] Each CCE may include six REGs and may be associated with yet another identification number or CCE ID. In this example, a CCE may include only REGs from one TRP. Some examples of CCEs are shown as CCE 0, CCE 1, CCE 2, etc. For example, CCE 0 includes six REGs 0 to 5 from TRP 0, while CCE 1 includes six REGs 0 to 5 from TRP 1. Based on the aggregation level, a preset number of CCEs may be combined together to form a resource candidate. In this example, the aggregation level is 2, and thus each candidate resource includes two CCEs. For example, resource candidate 1812 includes CCE 0 and CCE 1; and resource candidate 2814 includes CCE 2 and CCE 3.

[0102] Alternatively, an extended basic unit can be utilized as one or more REG bundles for resource mapping. That is, a REG bundle can be a predefined granularity of a transmission unit. In this case, a CCE can be composed of REG bundle units from multiple TRPs, that is, one or more REG bundles.

[0103] To utilize time-frequency resources from multiple beams / TRPs, spatial multiplexing can be used for enhanced PDCCH transmission. Resource mapping can be extended to spatial resources for transmission units with different granularities, which can be REGs, or REG bundle groups, or CCEs. To utilize more diversity in the spatial, temporal, and frequency domains, transmission units are cascaded in a first increasing order of the transmission units through a beam / TRP followed by (one or more) other beam / (one or more) TRP. Based on this property, the TCI state of the PDCCH DM-RS alternates according to the beam / TRP for each transmission unit. REGs, REG bundle groups, or CCEs from one TRP are linked to a specific TCI state, and thus their TCI states can be implicitly determined, for example, through a TCI state mapping scheme. Specifically, the TCI state mapping scheme can be expressed as follows:

[0104] k = i mod N

[0105] where

[0106] k is the TCI state index for (one or more) PRBs in a REG, REG bundle group, or CCE;

[0107] i is the global index of the REG, REG bundle group, or CCE;

[0108] N is the total number (quantity) of active TCI states; and

[0109] mod is the modulo operation.

[0110] That is, the index of the TCI state for a transmission unit is the remainder after dividing the index of the transmission unit by the number of active TCI states.

[0111] In the example shown in Figure 7 and 8 , by using 2 active TCI states for 2 TRPs, the TCI state of the PDCCH DM-RS for (one or more) PRBs in a REG or CCE can be implicitly determined, for example, by alternately using TCI state 0 and TCI state 1 according to the global index of the REG or CCE.

[0112] Since spatial multiplexing is used, a DM-RS port is associated with a TCI state. For example, DM-RS port 2000 is linked to the active TCI state 0, and DM-RS port 2001 is linked to the active TCI state 1 for PDCCH transmissions from two TRPs. Similar to the implicit principle for determining the TCI state, the DM-RS port index can also be implicitly determined based on the global index of a REG, REG bundle group, or CCE, which is determined by a port mapping scheme. Specifically, the port mapping scheme can be expressed as:

[0113] p = 2000 + i mod N

[0114] where

[0115] p is the DM-RS port index for one or more PRBs in a REG, REG bundle group, or CCE;

[0116] i is the global index of a REG, REG bundle group, or CCE;

[0117] N is the total number of active TCI states; and

[0118] mod is the modulo operation.

[0119] That is, the DM-RS port index for the resources in a transmission unit is 2000 plus the remainder after dividing the index of the transmission unit by the number of active TCI states.

[0120] To improve channel estimation quality and demodulation performance, orthogonal or quasi-orthogonal DM-RS can be used.

[0121] For orthogonal DM-RS ports, different OCCs (orthogonal cover codes) can be used for different DM-RS ports over the available REs (resource elements) in a PRB. The same DM-RS sequence is applied to all DM-RS ports. Based on the TS 38.211 specification, there are 3 available REs with a density of 1 / 4 in a REG for PDCCH DM-RS. An example of the OCC sequence is shown in Table 2 below, which can be used for DM-RS with up to 3 orthogonal layers.

[0122] Table 2 OCC Sequences for PDCCH DM-RS

[0123] OCC index for DM-RS Orthogonal cover code 0 [1 1 1] 1 <![CDATA[[1 e j2π / 3 e j4π / 3 > 2 <![CDATA[[1 e j4π / 3 e j2π / 3 >

[0124] Each OCC is linked to a DM-RS port. Specifically, if TCI state 0 or TCI state 1 is used for PDCCH DM-RS port 2000 or port 2001 from which enhanced PDCCH is transmitted from beam / TRP 0 or beam / TRP 1, OCC0 or OCC 1 will be used respectively to orthogonally cover the DM-RS sequence for transmission in a REG during physical resource mapping. On the UE side, a similar link between the DM-RS OCC sequence and the TCI state or DM-RS port is assumed. It is used to de-cover the transmitted DM-RS sequence during physical resource demapping for channel estimation for demodulation.

[0125] For quasi-orthogonal DM-RS ports, different DM-RS sequences can be used for different DM-RS ports with SDM to support interference randomization between DM-RS ports with different beams from different TRPs. Therefore, multiple DM-RS scrambling IDs can be configured for each CORESET, where each DM-RS scrambling ID is implicitly associated with a DM-RS port. Specifically, if TCI state 0 or TCI state 1 is used for PDCCH DM-RS port 2000 or port 2001, from which enhanced PDCCH is transmitted from beam / TRP 0 or beam / TRP 1, DM-RS scrambling ID 0 or DM-RS scrambling ID 1 will be used respectively to obtain the initial value for generating the sequence. On the UE side, a similar association between the DM-RS scrambling ID and the TCI state is assumed. It is used to determine the scrambling ID for generating the DM-RS sequence for channel estimation for demodulation.

[0126] Implicit PDCCH DM-RS TCI state determination for multi-TRP transmission using frequency division multiplexing

[0127] Figure 9 is a schematic diagram illustrating an example of the determination of the PDCCH DM-RS TCI state for multi-TRP transmission using REG bundle group-level frequency division multiplexing (FDM); and Figure 10 is a schematic diagram illustrating an example of the determination of the PDCCH DM-RS TCI state for multi-TRP transmission using control channel element (CCE)-level frequency division multiplexing (FDM).

[0128] To utilize time-frequency resources from multiple beams / TRPs, frequency division multiplexing can be used for enhanced PDCCH transmission for better stability. To utilize more diversity in space, time, and frequency domains, multiple beam alternations can be used for transmission units in the frequency domain. The transmission units can have different granularities, e.g., REG bundle groups or CCEs. Based on this property, the TCI state of PDCCH DM-RS can alternate according to the beam / TRP used for each transmission unit. A REG bundle group or CCE from one TRP is linked to a specific TCI state, and thus its TCI state can be implicitly determined. Specifically, the TCI state mapping scheme can be expressed as:

[0129] k = i mod N

[0130] where

[0131] k is the TCI state index for the PRB in the REG bundle group / CCE;

[0132] i is the global index of the REG bundle group / CCE;

[0133] N is the total number of active TCI states; and

[0134] mod is the modulo operation.

[0135] In some examples, as Figure 9 and 10 shown, the TCI state of PDCCH DM-RS for the PRB in the REG bundle group or CCE can be implicitly determined, i.e., TCI state 0 and TCI state 1 are used alternately, according to the global index of the REG bundle group or CCE. Since only one beam is used for transmission on one PRB, although the transmit beam can be different for different PRBs, only DM-RS port 2000 with different TCI states is used for different PRBs. In these examples, a DM-RS sequence similar to that of version 15 can be applied in the frequency domain, regardless of the TCI state used.

[0136] In Figure 9In the example shown, the CORESET includes resource sets from two TRPs, namely, TRP 0 and TRP 1, which are arranged in an alternative manner based on REG bundling or REG bundling groups. The resources include multiple REGs in two OFDM symbols 900a and 900b. Resource candidate 1 912 may include two CCEs, namely, CCE 0 and CCE 1. Each CCE may include REGs from two different TRPs. For example, CCE 0 includes REG 0, REG 1, REG 4, and REG 5 from TRP 0, and REG 2 and REG 3 from TRP 1; and CCE 1 includes REG 6, REG 7, REG 10, and REG 11 from TRP 1, and REG 8 and REG 9 from TRP 0.

[0137] In Figure 10 the example shown, the CORESET includes resource sets from two TRPs, namely, TRP0 and TRP 1, which are arranged in an alternative CCE-based manner. The resources include multiple REGs in two OFDM symbols 1000a and 1000b. Candidate resource 1 1012 may include two CCEs, namely, CCE 0 and CCE 1. Each CCE may be composed of REGs from a single TRP. For example, CCE 0 includes REG 0 to REG 5, all of which are from TRP 0; and CCE 1 includes REG 6 to REG 11, all of which are from TRP 1.

[0138] For FDM-based enhanced PDCCH transmission from multiple TRPs, one sequence may be used for DM-RS on all PRBs, regardless of which TRP they are from. Alternatively, separate sequences may be used for DM-RS on PRBs from different beams / TRPs. In this case, a DM-RS sequence generation scheme may be used, which is similar to the aforementioned SDM-related sequence generation scheme with multiple configurations of PDCCH DM-RS scrambling IDs, where one scrambling ID is linked to one TCI state.

[0139] Figure 11 is a flowchart illustrating steps of transmission of enhanced DM-RS for enhanced PDCCH transmission using multiple beams from multiple TRPs via an NE according to some embodiments of the present disclosure.

[0140] In step 1102, the processor 302 of the NE 300 determines a plurality of active transmission configuration indication (TCI) states using a plurality of radio transmit - receive identities (i.e., TRPs) for transmission of a physical downlink control channel (PDCCH) that utilizes demodulation reference signals (DM - RS) in a control resource set (CORESET), where the CORESET includes a plurality of transmission units having a predefined granularity.

[0141] The predefined granularity may be a resource element group (REG), a REG bundle, and / or a control channel element (CCE).

[0142] In step 1104, the processor 302 further determines, based on a TCI state mapping scheme, the TCI states to be used for each of the transmission units and each of their corresponding DM - RSs.

[0143] In step 1106, the transmitter 314 transmits a media access control (MAC) control element (CE) for activating each of the TCI states.

[0144] In step 1106, the transmitter 314 further transmits the PDCCH using a plurality of radio transmit - receive identities, e.g., TRP0 and TRP 1, via the transmission units and the corresponding DM - RSs having the corresponding TCI states as determined by the processor.

[0145] In some embodiments, the TCI state mapping scheme maps the active TCI states to the transmission units according to the index of the transmission units and the number of active TCI states. The TCI state mapping scheme may be predefined between a transmitting device (e.g., NE 300) including the processor 302 and a receiving device 200 such that the receiving device 200 can implicitly derive the TCI state for the DM - RS. The TCI state mapping scheme may include deriving an index of the TCI state for the transmission unit, which is the remainder after dividing the index of the transmission unit by the number of active TCI states.

[0146] In some embodiments, the processor 302 further determines a plurality of DM - RS ports for the PDCCH DM - RS based on a port mapping scheme. The port mapping scheme may be predefined between a transmitting device 300 including the processor 302 and a receiving device 200 such that the receiving device 200 can implicitly derive the DM - RS ports. The port mapping scheme may include deriving a DM - RS port index for the resources in the transmission unit, which is 2000 plus the remainder after dividing the index of the transmission unit by the number of active TCI states.

[0147] In some embodiments, the processor 302 further generates a plurality of PDCCH DM-RS scrambling IDs, and each PDCCH DM-RS scrambling ID is associated with a TCI state or a DM-RS port and is used to generate a PDCCH DM-RS sequence. A plurality of orthogonal cover codes (OCCs) can be used for the DM-RS ports, and each OCC is associated with a TCI state or a DM-RS port.

[0148] Figure 12 FIG. is a flowchart illustrating steps of receiving, by a UE, enhanced DM-RS for enhanced PDCCH transmission using multiple beams from multiple TRPs according to some embodiments of the present disclosure.

[0149] In step 1202, the receiver 214 of the UE 200 receives a media access control (MAC) control element (CE) for activating a plurality of transmission configuration indication (TCI) states.

[0150] In step 1204, the receiver 214 of the UE 200 further receives a physical downlink control channel (PDCCH) using demodulation reference signals (DM-RS) in a control resource set (CORESET), where the CORESET includes a plurality of transmission units with a predefined granularity, and the PDCCH is received through the transmission units and the DM-RS, and each of the transmission units and its corresponding DM-RS has a corresponding TCI state.

[0151] The predefined granularity can be a resource element group (REG), a REG bundle, and / or a control channel element (CCE).

[0152] In step 1206, the processor 202 determines that the PDCCH is transmitted from the transmitting device 300 using a plurality of radio transmit-receive identities, e.g., TRP 0 and TRP 1.

[0153] In step 1208, the processor 202 estimates channel conditions for demodulating the PDCCH using the received DM-RS and the corresponding TCI state based on a TCI state mapping scheme.

[0154] In some embodiments, the processor 202 further determines a plurality of DM-RS ports for the PDCCH DM-RS based on a port mapping scheme. The port mapping scheme can be predefined between the transmitting device 300 and the receiving device 200 including the processor 202 such that the processor 202 can implicitly derive the DM-RS ports. The port mapping scheme can include deriving a DM-RS port index for resources in the transmission units, which is 2000 plus the remainder of the index of the transmission unit divided by the number of activated TCI states.

[0155] Various embodiments and / or examples are disclosed to provide illustrative and explanatory information to enable those of ordinary skill in the art to practice the disclosure. Features or components disclosed with reference to one embodiment or example are also applicable to all embodiments or examples unless otherwise specifically indicated.

[0156] The embodiments may be practiced in other specific forms. The described embodiments are to be considered in all respects only as illustrative and not restrictive. Thus, the scope of the invention is indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A network device (NE), comprising: a processor, the processor using multiple radio transmit - receive identities to determine multiple active transmission configuration indication (TCI) states for the transmission of a physical downlink control channel (PDCCH) that utilizes demodulation reference signals (DM - RS) in a control resource set (CORESET), wherein the CORESET includes multiple transmission units having a predefined granularity, and wherein the predefined granularity includes one selected from the group consisting of: resource element group (REG), REG bundle, and control channel element (CCE); based on a TCI state mapping scheme, determining, for each of the transmission units and its corresponding DM - RS, a TCI state to be used for the transmission, wherein in the TCI state mapping scheme, REGs, REG bundle groups, or CCEs from one TRP are linked to a TCI state; and a transmitter, the transmitter transmitting media access control (MAC) control elements (CEs) for activating each of the TCI states; transmitting the PDCCH using the multiple radio transmit - receive identities through the transmission units having the corresponding TCI states determined by the processor and the corresponding DM - RS.

2. The NE according to claim 1, wherein The TCI state mapping scheme maps the active TCI states to the transmission units according to the index of the transmission units and the number of active TCI states.

3. The NE according to claim 2, wherein, The TCI state mapping scheme is predefined between the NE and a receiving device such that the receiving device can implicitly deduce the TCI state for the DM - RS.

4. The NE according to claim 2, wherein The TCI state mapping scheme includes deducing an index of the TCI state for a transmission unit, and the index of the TCI state is the remainder after dividing the index of the transmission unit by the number of active TCI states.

5. The NE according to claim 1, wherein The processor further determines multiple DM - RS ports for the PDCCH DM - RS based on a port mapping scheme.

6. The NE according to claim 5, wherein, The port mapping scheme is predefined between the NE and a receiving device such that the receiving device can implicitly deduce the DM - RS ports.

7. The NE according to claim 5, wherein The port mapping scheme includes deducing a DM - RS port index for resources in a transmission unit, and the DM - RS port index is 2000 plus the remainder after dividing the index of the transmission unit by the number of active TCI states.

8. The NE according to claim 1 or 5, wherein The processor further generates multiple PDCCH DM - RS scrambling IDs, and each PDCCH DM - RS scrambling ID is associated with a TCI state or the DM - RS port and is used to generate a PDCCH DM - RS sequence.

9. The NE according to claim 1 or 5, wherein Multiple orthogonal cover codes (OCCs) are used for the DM - RS ports, and each OCC is associated with a TCI state or a DM - RS port.

10. A user equipment (UE), comprising: a receiver, the receiver receiving media access control (MAC) control elements (CEs) for activating multiple transmission configuration indication (TCI) states; Receiving a Physical Downlink Control Channel (PDCCH) using Demodulation Reference Signals (DM-RS) in a Control Resource Set (CORESET), where the CORESET includes a plurality of transmission units having a predefined granularity, where the predefined granularity includes one selected from the group consisting of Resource Element Groups (REGs), REG bundles, and Control Channel Elements (CCEs), and the PDCCH is received via the transmission units and the DM-RS, and each of the transmission units and its corresponding DM-RS has a corresponding TCI state; and a processor, the processor determining that the PDCCH is transmitted from a transmitting device using a plurality of radio transmit-receive identities; estimating channel conditions for demodulation of the PDCCH using the received DM-RS and the corresponding TCI state based on a TCI state mapping scheme, in which REGs, REG bundle groups, or CCEs from one TRP are linked to one TCI state.

11. The UE according to claim 10, wherein The TCI state mapping scheme maps the active TCI states to the transmission units according to the index of the transmission units and the number of active TCI states.

12. The UE according to claim 11, wherein, The TCI state mapping scheme is predefined between the UE and the transmitting device such that the UE can implicitly derive the TCI state for the DM-RS.

13. The UE according to claim 11, wherein, The TCI state mapping scheme includes deriving an index of the TCI state for a transmission unit, where the index of the TCI state is the remainder after dividing the index of the transmission unit by the number of active TCI states.

14. The UE according to claim 10, wherein, The processor further determines a plurality of DM-RS ports for the PDCCH DM-RS based on a port mapping scheme.

15. The UE according to claim 14, wherein, The port mapping scheme is predefined between the UE and the transmitting device such that the UE can implicitly derive the DM-RS ports.

16. The UE according to claim 14, wherein, The port mapping scheme includes deriving a DM-RS port index for resources in a transmission unit, where the DM-RS port index is 2000 plus the remainder after dividing the index of the transmission unit by the number of active TCI states.

17. The UE according to claim 10 or 14, wherein, The receiver further receives a plurality of PDCCH DM-RS scrambling IDs, and each PDCCH DM-RS scrambling ID is associated with a TCI state or the DM-RS port and is used to generate a PDCCH DM-RS sequence.

18. The UE according to claim 10 or 14, wherein A plurality of Orthogonal Cover Codes (OCCs) are used to cancel coverage of the DM-RS ports, and each OCC is associated with a TCI state or a DM-RS port.

19. A method performed by a Network Equipment (NE), comprising: A processor determines multiple active transmission configuration indication (TCI) states using multiple radio transmit - receive identities for transmission of a physical downlink control channel (PDCCH) that utilizes demodulation reference signals (DM - RS) in a control resource set (CORESET), wherein the CORESET includes multiple transmission units having a predefined granularity, and wherein the predefined granularity includes one selected from the group consisting of: resource element group (REG), REG bundle, and control channel element (CCE); The processor determines, based on a TCI state mapping scheme, a TCI state to be used for each of the transmission units and its corresponding DM - RS in the TCI state mapping scheme, in which REGs, REG bundle groups, or CCEs from one TRP are linked to a TCI state; A transmitter transmits media access control (MAC) control elements (CEs) for activating each of the TCI states; and The transmitter transmits the PDCCH using the multiple radio transmit - receive identities via the transmission units and the corresponding DM - RS having the corresponding TCI states determined by the processor.

20. The method according to claim 19, wherein, The TCI state mapping scheme maps the active TCI states to the transmission units according to the index of the transmission units and the number of active TCI states.

21. The method according to claim 20, wherein, The TCI state mapping scheme is predefined between the transmitting device and the receiving device including the processor, such that the receiving device can implicitly derive the TCI state for the DM - RS.

22. The method according to claim 20, wherein The TCI state mapping scheme includes deriving an index of the TCI state for a transmission unit, where the index of the TCI state is the remainder after dividing the index of the transmission unit by the number of active TCI states.

23. The method according to claim 19, wherein, The processor further determines multiple DM - RS ports for the PDCCH DM - RS based on a port mapping scheme.

24. The method according to claim 23, wherein The port mapping scheme is predefined between the transmitting device and the receiving device including the processor, such that the receiving device can implicitly derive the DM - RS ports.

25. The method according to claim 23, wherein, The port mapping scheme includes deriving a DM - RS port index for resources in a transmission unit, where the DM - RS port index is 2000 plus the remainder after dividing the index of the transmission unit by the number of active TCI states.

26. The method according to claim 19 or 23, wherein, The processor further generates multiple PDCCH DM - RS scrambling IDs, and each PDCCH DM - RS scrambling ID is associated with a TCI state or the DM - RS port and is used to generate a PDCCH DM - RS sequence.

27. The method according to claim 19 or 23, wherein Multiple orthogonal cover codes (OCCs) are used for the DM - RS ports, and each OCC is associated with a TCI state or a DM - RS port.

28. A method performed by a user equipment (UE), comprising: A receiver receives media access control (MAC) control elements (CEs) for activating multiple transmission configuration indication (TCI) states; The physical downlink control channel (PDCCH) is received by the receiver using demodulation reference signals (DM-RS) in a control resource set (CORESET), where the CORESET includes a plurality of transmission units with a predefined granularity, where the predefined granularity includes one selected from the group consisting of: resource element group (REG), REG bundle, and control channel element (CCE), and the PDCCH is received via the transmission units and the DM-RS, and each of the transmission units and its corresponding DM-RS has a corresponding TCI state; It is determined by the processor that the PDCCH is transmitted from a transmitting device using a plurality of radio transmit-receive identities; and The processor estimates the channel conditions for demodulating the PDCCH based on a TCI state mapping scheme using the received DM-RS and the corresponding TCI state, in which REG, REG bundle group, or CCE from one TRP is linked to one TCI state.

29. The method according to claim 28, wherein The TCI state mapping scheme maps the active TCI states to the transmission units according to the index of the transmission units and the number of active TCI states.

30. The method according to claim 29, wherein, The TCI state mapping scheme is predefined between the transmitting device and the receiving device including the processor, such that the processor can implicitly derive the TCI state for the DM-RS.

31. The method according to claim 29, wherein, The TCI state mapping scheme includes deriving an index of the TCI state for a transmission unit, where the index of the TCI state is the remainder after dividing the index of the transmission unit by the number of active TCI states.

32. The method according to claim 28, wherein, The processor further determines a plurality of DM-RS ports for the PDCCH DM-RS based on a port mapping scheme.

33. The method according to claim 32, wherein The port mapping scheme is predefined between the transmitting device and the receiving device including the processor, such that the processor can implicitly derive the DM-RS ports.

34. The method according to claim 32, wherein, The port mapping scheme includes deriving a DM-RS port index for the resources in a transmission unit, where the DM-RS port index is 2000 plus the remainder after dividing the index of the transmission unit by the number of active TCI states.

35. The method according to claim 28 or 32, wherein The receiver further receives a plurality of PDCCH DM-RS scrambling IDs, and each PDCCH DM-RS scrambling ID is associated with a TCI state or the DM-RS port and is used to generate a PDCCH DM-RS sequence.

36. The method according to claim 28 or 32, wherein, A plurality of orthogonal cover codes (OCC) are used to cancel the coverage of the DM-RS ports, and each OCC is associated with a TCI state or a DM-RS port.

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