System and method for providing additional DM-RS port for 5G MU-MIMO transmission

Abstract

In one embodiment, a user equipment (UE) may receive a configuration from a gNB, where the configuration is configured to configure a first orthogonal cover code (OCC) length and a second OCC length to perform demodulation reference signal (DM-RS) communication between the gNB and the UE, the first OCC length is 4, the second OCC length is 2, and the first OCC length is 4, the second OCC length is 4, and the first OCC length is 4, and the second OCC length is 2. And a signaling is received, and the signaling indicates the UE to transmit the DM-RS according to the first OCC length or the second OCC length. The UE may transmit a DM-RS with the gNB according to the first OCC length or the second OCC length indicated by the signaling.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to U.S. Provisional Application No. 63 / 335,590, filed on April 27, 2022, entitled “SYSTEM AND METHOD FOR ADDING ADDITIONAL DM-RS PORTS FOR 5G MU-MIMO TRANSMISSION,” and U.S. Provisional Application No. 63 / 335,606, filed on April 27, 2022, entitled “SYSTEM AND METHOD FOR ADDING ADDITIONAL DM-RS PORTS FOR 5G MU-MIMO TRANSMISSION,” the contents of which are incorporated herein by reference as if reproduced in their entirety. Technical Field

[0003] The present disclosure relates generally to telecommunications and, in particular embodiments, to systems and methods for providing additional DM-RS ports for 5G MU-MIMO transmissions. Background Art

[0004] Downlink and uplink transmissions in 5G new radio (NR) are based on demodulation reference signals (DM-RS). In single user / multi user multiinput multi output (SU / MU-MIMO) transmission, each DM-RS port can carry a DM-RS, which is used for channel estimation to demodulate the corresponding data layer transmitted on the same port. Ideally, there are a large number of orthogonal DM-RS ports and one or more multiplexing schemes with less DM-RS overhead while ensuring good demodulation performance to support a large number of data layers for large-scale SU / MU-MIMO transmission. Summary of the invention

[0005] According to one aspect of the present disclosure, a method is provided. The method includes: a user equipment (UE) receives a configuration from a gNB, wherein the configuration is used to configure a first orthogonal cover code (OCC) length and a second OCC length for demodulation reference signal (DM-RS) communication between the gNB and the UE, wherein the first OCC length is 4 and the second OCC length is 2; the UE receives signaling, wherein the signaling indicates that the UE transmits DM-RS according to the first OCC length or the second OCC length; the UE transmits DM-RS with the gNB according to the first OCC length or the second OCC length indicated by the signaling.

[0006] Optionally, in any of the above aspects, the signaling is RRC signaling.

[0007] Optionally, in any of the above aspects, the signaling is carried in a medium access control (MAC) control element (CE).

[0008] Optionally, in any of the above aspects, the signaling is carried in a downlink control information (DCI) message.

[0009] Optionally, in any of the above aspects, the method also includes: the UE sends a message to the gNB confirming receipt of the configuration.

[0010] Optionally, in any of the above aspects, the transmitting DM-RS includes: when the signaling indicates the first OCC length, the UE receives or sends the DM-RS through the DM-RS port associated with the OCC of the first OCC length, or when the signaling indicates the second OCC length, the UE receives or sends the DM-RS through the DM-RS port associated with the OCC of the second OCC length.

[0011] Optionally, in any of the above aspects, the method also includes: the UE receives a physical downlink shared channel (PDSCH) through a DM-RS port associated with the OCC of the first OCC length, or through a DM-RS port associated with the OCC of the second OCC length; or, the UE sends a physical uplink shared channel (PUSCH) through a DM-RS port associated with the OCC of the first OCC length, or through a DM-RS port associated with the OCC of the second OCC length.

[0012] Optionally, in any of the above aspects, the OCC of the first OCC length includes: [+1+1+1+1], [+1–1+1–1], [+1+j–1–j] or [+1–j–1+j].

[0013] Optionally, in any of the above aspects, the method also includes: the UE receives a DCI message including an indication; the UE receives a DM-RS port offset bit, wherein the combination of the indication and the DM-RS port offset bit indicates information of the DM-RS port to be used by the UE.

[0014] Optionally, in any of the above aspects, the method also includes: when the signaling indicates the first OCC length, the signaling indicates and the DM-RS port offset bit has a first value, the UE determines the first port number of the DM-RS port to be used according to a first corresponding relationship associated with the second OCC length, and the first port number corresponds to the indication; or, when the signaling indicates the first OCC length and the DM-RS port offset bit has a second value, the UE determines the second port number of the DM-RS port to be used, and the second port number is obtained by adding a non-zero integer to the first port number respectively.

[0015] Optionally, in any of the above aspects, the non-zero integer is 8 or 12.

[0016] Optionally, in any of the above aspects, the method also includes: when the signaling indicates the first OCC length and the DM-RS port offset bit has a first value, the UE determines that the DM-RS port to be used has the port number based on a first correspondence between the port number and the indication, wherein the first correspondence is associated with the second OCC length; or, when the signaling indicates the first OCC length and the DM-RS port offset bit has a second value, the UE determines that the DM-RS port to be used has the port number based on a second correspondence between the port number and the indication, wherein the second correspondence is associated with the first OCC length.

[0017] Optionally, in any of the above aspects, the DM-RS port offset bit is included in the DCI message.

[0018] Optionally, in any of the above aspects, the DCI message is a traditional DCI message.

[0019] Optionally, in any of the above aspects, when one symbol is configured for type 1 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 8, when 2 symbols are configured for type 1 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 16, when one symbol is configured for type 2 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 12, or when two symbols are configured for type 2 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 24.

[0020] Optionally, in any of the above aspects, the DM-RS communication includes type 1 DM-RS transmission or type 2 DM-RS transmission.

[0021] According to another aspect of the present disclosure, a method is provided. The method includes: a communication device sends a first demodulation reference signal (DM-RS) through a first DM-RS port associated with an orthogonal cover code (OCC) of length 4; or the communication device receives a second DM-RS through a second DM-RS port associated with an OCC of length 4.

[0022] Optionally, in any of the above aspects, the communication device is a user equipment (UE) or a gNB.

[0023] Optionally, in any of the above aspects, the OCC includes: [+1+1+1+1], [+1–1+1–1], [+1+j–1–j] or [+1–j–1+j].

[0024] Optionally, in any of the above aspects, the method also includes: the communication device receives a DCI message including an indication, wherein the communication device is a user equipment (UE); the UE receives a DM-RS port offset bit, wherein a combination of the indication and the DM-RS port offset bit indicates information of the DM-RS port.

[0025] Optionally, in any of the above aspects, the method also includes: when the DM-RS port offset bit has a first value, the UE determines that the DM-RS port has a first port number based on a first correspondence relationship associated with an OCC of length 2, and the first port number corresponds to the indication; or when the DM-RS port offset bit has a second value, the UE determines that the DM-RS port has a second port number, and the second port number is obtained by adding a non-zero integer to the first port number respectively.

[0026] Optionally, in any of the above aspects, the non-zero integer is 8 or 12.

[0027] Optionally, in any of the above aspects, the method also includes: when the DM-RS port offset bit has a first value, the UE determines the DM-RS port according to a first correspondence between the port number and the indication, wherein the first correspondence is associated with an OCC of length 2; or when the DM-RS port offset bit has a second value, the UE determines the DM-RS port according to a second correspondence between the port number and the indication, wherein the second correspondence is associated with the OCC of length 4.

[0028] Optionally, in any of the above aspects, the method also includes: the communication device sends a DCI message including an indication, wherein the communication device is a gNB; the gNB sends a DM-RS port offset bit, wherein a combination of the indication and the DM-RS port offset bit indicates the DM-RS port.

[0029] Optionally, in any of the above aspects, the DM-RS port offset bit is included in the DCI message.

[0030] Optionally, in any of the above aspects, the DCI message is a traditional DCI message.

[0031] Optionally, in any of the above aspects, when one symbol is configured for type 1 DM-RS transmission, the number of DM-RS ports associated with the OCC with a length of 4 is 8, when two symbols are configured for type 1 DM-RS transmission, the number of DM-RS ports associated with the OCC with a length of 4 is 16, when one symbol is configured for type 2 DM-RS transmission, the number of DM-RS ports associated with the OCC with a length of 4 is 12, and when two symbols are configured for type 2 DM-RS transmission, the number of DM-RS ports associated with the OCC with a length of 4 is 24.

[0032] Optionally, in any of the above aspects, the first DM-RS or the second DM-RS includes a type 1 DM-RS or a type 2 DM-RS.

[0033] According to another aspect of the present disclosure, a method is provided. The method includes: a gNB sends a configuration to a user equipment (UE), wherein the configuration is used to configure a first orthogonal cover code (OCC) length and a second orthogonal cover code length for demodulation reference signal (DM-RS) communication between the gNB and the UE, wherein the first OCC length is 4 and the second OCC length is 2; the gNB sends a signaling, wherein the signaling instructs the UE to transmit the DM-RS according to the first OCC length or the second OCC length; the gNB transmits the DM-RS with the UE according to the first OCC length or the second OCC length indicated by the signaling.

[0034] Optionally, in any of the above aspects, the sending configuration includes: the gNB sending the configuration in radio resource control (radioresource control, RRC) signaling.

[0035] Optionally, in any of the above aspects, the signaling is RRC signaling.

[0036] Optionally, in any of the above aspects, the signaling is carried in a medium access control (MAC) control element (CE).

[0037] Optionally, in any of the above aspects, the signaling is carried in a downlink control information (DCI) message.

[0038] Optionally, in any of the above aspects, the method also includes: the gNB receives a message from the UE confirming receipt of the configuration.

[0039] Optionally, in any of the above aspects, the transmitting DM-RS includes: when the signaling indicates the first OCC length, the gNB receives or sends the DM-RS through a DM-RS port associated with the OCC of the first OCC length, or when the signaling indicates the second OCC length, the gNB receives or sends the DM-RS through a DM-RS port associated with the OCC of the second OCC length.

[0040] Optionally, in any of the above aspects, the method also includes: the gNB sends a physical downlink shared channel (PDSCH) through a DM-RS port associated with the OCC of the first OCC length, or through a DM-RS port associated with the OCC of the second OCC length; or, the gNB receives a physical uplink shared channel (PUSCH) through a DM-RS port associated with the OCC of the first OCC length, or through a DM-RS port associated with the OCC of the second OCC length.

[0041] Optionally, in any of the above aspects, the OCC of the first OCC length includes: [+1+1+1+1], [+1–1+1–1], [+1+j–1–j] or [+1–j–1+j].

[0042] Optionally, in any of the above aspects, the method also includes: the gNB sends a DCI message including an indication; the gNB sends a DM-RS port offset bit, wherein a combination of the indication and the DM-RS port offset bit indicates a DM-RS port to be used.

[0043] Optionally, in any of the above aspects, when the signaling indicates the first OCC length and the DM-RS port offset bit has a first value, according to a first correspondence relationship associated with the second OCC length, the DM-RS port to be used has a first port number, and the first port number corresponds to the indication; or, when the signaling indicates the first OCC length and the DM-RS port offset bit has a second value, the DM-RS port to be used has a second port number, and the second port number is obtained by adding a non-zero integer to the first port number respectively.

[0044] Optionally, in any of the above aspects, the non-zero integer is 8 or 12.

[0045] Optionally, in any of the above aspects, when the signaling indicates the first OCC length and the DM-RS port offset bit has a first value, according to a first correspondence between the port number and the indication, the DM-RS port has the port number, wherein the first correspondence is associated with the second OCC length; or, when the signaling indicates the first OCC length and the DM-RS port offset bit has a second value, according to a second correspondence between the port number and the indication, the DM-RS port to be used has the port number, wherein the second correspondence is associated with the first OCC length.

[0046] Optionally, in any of the above aspects, the DM-RS port offset bit is included in the DCI message.

[0047] Optionally, in any of the above aspects, the DCI message is a traditional DCI message.

[0048] Optionally, in any of the above aspects, when one symbol is configured for type 1 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 8, when 2 symbols are configured for type 1 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 16, when one symbol is configured for type 2 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 12, or when two symbols are configured for type 2 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 24.

[0049] Optionally, in any of the above aspects, the DM-RS communication includes type 1 DM-RS transmission or type 2 DM-RS transmission.

[0050] According to another aspect of the present disclosure, a device is provided, comprising: a non-transitory memory including instructions; and one or more processors communicating with the memory, wherein when the instructions are executed by the one or more processors, the device executes the method in any of the above aspects.

[0051] According to another aspect of the present disclosure, a non-transitory computer-readable medium storing computer instructions is provided. When the computer instructions are executed by one or more processors, the one or more processors execute the method in any of the above aspects.

[0052] According to another aspect of the present disclosure, a system is provided. The system includes a gNB and a user equipment (UE) communicating with the gNB, wherein the UE is used to perform the following operations: receiving a configuration from the gNB, wherein the configuration is used to configure a first orthogonal cover code (OCC) length and a second OCC length for a demodulation reference signal (DM-RS) communication between the gNB and the UE, wherein the first OCC length is 4 and the second OCC length is 2; receiving signaling, wherein the signaling instructs the UE to transmit DM-RS according to the first OCC length or the second OCC length; transmitting DM-RS with the gNB according to the first OCC length or the second OCC length indicated by the signaling; the gNB is used to perform the following operations: sending the configuration to the UE; sending the signaling to the UE; transmitting the DM-RS with the UE.

[0053] According to another aspect of the present disclosure, a device is provided. The device includes: a receiving module, configured to: receive a configuration from a gNB, wherein the configuration is used to configure a first orthogonal cover code (OCC) length and a second OCC length for demodulation reference signal (DM-RS) communication between the gNB and the UE, wherein the first OCC length is 4 and the second OCC length is 2, and receive signaling, wherein the signaling indicates that the UE transmits the DM-RS according to the first OCC length or the second OCC length; and a communication module, configured to transmit the DM-RS with the gNB according to the first OCC length or the second OCC length indicated by the signaling.

[0054] According to another aspect of the present disclosure, a device is provided. The device includes: a sending module, configured to send a first demodulation reference signal (DM-RS) through a first DM-RS port associated with an orthogonal cover code (OCC) of length 4; or, a receiving module, configured to receive a second DM-RS through a second DM-RS port associated with an OCC of length 4.

[0055] According to another aspect of the present disclosure, a device is provided. The device includes: a sending module, used to: send a configuration to a user equipment (UE), wherein the configuration is used to configure a first orthogonal cover code (OCC) length and a second OCC length for demodulation reference signal (DM-RS) communication between a gNB and the UE, wherein the first OCC length is 4 and the second OCC length is 2; send signaling, wherein the signaling instructs the UE to transmit DM-RS according to the first OCC length or the second OCC length; a communication module, used to transmit DM-RS with the UE according to the first OCC length or the second OCC length indicated by the signaling.

[0056] The above aspects of the present disclosure can transmit DM-RS according to OCC length 4. This increases the number of orthogonal DM-RS ports that can be used for DM-RS communication while maintaining relatively small DM-RS overhead, achieves good demodulation performance, and can support a large number of data layers for large-scale SU / MU-MIMO transmission. The above aspects of the present disclosure can also quickly switch between DM-RS communication according to OCC length 4 and DM-RS communication according to OCC length 2. This allows dynamic switching between robust and high-throughput SU / MU-MIMO transmissions based on the channel environment and communication requirements of the UE. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] For a more complete understanding of the present disclosure and its advantages, reference is made to the following description taken in conjunction with the accompanying drawings, in which:

[0058] Figure 1 is a schematic diagram of an exemplary communication network;

[0059] Figure 2 is a schematic diagram of an exemplary resource allocation of orthogonal DM-RS antenna ports according to a conventional type 1 DM-RS configuration;

[0060] Figure 3 is a schematic diagram of another exemplary resource allocation of orthogonal DM-RS antenna ports according to a conventional type 1 DM-RS configuration;

[0061] Figure 4 is a schematic diagram of an exemplary resource allocation of orthogonal DM-RS antenna ports according to a conventional type 2 DM-RS configuration;

[0062] Figure 5 is a schematic diagram of another exemplary resource allocation of orthogonal DM-RS antenna ports according to a conventional type 2 DM-RS configuration;

[0063] Fig. 6A and Figure 6B An exemplary configuration of doubling the DM-RS port in the type 1 DM-RS configuration for configuring one OFDM symbol according to scheme 1 is shown;

[0064] Fig. 7A , Figure 7B , Figure 7C and Fig.7D An exemplary configuration of doubling the DM-RS ports in the type 1 DM-RS configuration for configuring two OFDM symbols according to scheme 1 is shown;

[0065] Figure 8 yes Fig. 6A and Figure 6B as well as 7A to 7D A schematic diagram of an exemplary relative time position of a Type 1 DM-RS port in FIG.

[0066] Fig. 9 is a schematic diagram of an exemplary DM-RS port allocation of a UE in a cyclic shift and comb tooth domain;

[0067] Fig.10 is a schematic diagram of an exemplary configuration in which a DM-RS port under a type 1 DM-RS configuration for configuring one OFDM symbol according to scheme 2 is doubled;

[0068] Fig.11A and Fig. 11B An exemplary configuration of doubling the DM-RS ports in the type 1 DM-RS configuration for configuring two OFDM symbols according to scheme 2 is shown;

[0069] Fig.12 yes Fig.10 A schematic diagram of an exemplary relative time position of a DM-RS port in FIG.

[0070] Fig.13 yes Fig.11A and Fig. 11B A schematic diagram of an exemplary relative time position of a DM-RS port in FIG.

[0071] Fig.14 is a schematic diagram of another DM-RS port allocation of UE in the cyclic shift and comb tooth domain;

[0072] Fig.15 is a flow chart highlighting an exemplary method of mode configuration and activation via RRC signaling;

[0073] Fig.16 is a flow chart highlighting an exemplary method of mode configuration via RRC signaling and mode activation via MAC-CE;

[0074] Fig.17 is a flow chart highlighting an exemplary method of mode configuration via RRC signaling and mode activation via DCI;

[0075] Fig.18 is a schematic diagram of an exemplary configuration of doubling the DM-RS ports of a type 2 DM-RS configuration configuring one OFDM symbol;

[0076] Fig.19 is a schematic diagram of an exemplary configuration of doubling the DM-RS ports of a type 2 DM-RS configuration configuring two OFDM symbols;

[0077] Fig. 20 yes Fig.18 and Fig.19 A schematic diagram of exemplary relative subcarrier positions of DM-RS ports in FIG.

[0078] Fig.21 is a schematic diagram of an exemplary DM-RS port allocation of a UE in the frequency domain based on a type 2 DM-RS configuration;

[0079] Fig. 22 is a flow chart of an exemplary method for DM-RS communication;

[0080] Fig.23 is a flow chart of another exemplary method for DM-RS communication;

[0081] Fig.24 is a flow chart of another exemplary method for DM-RS communication;

[0082] Fig.25 is a block diagram of an exemplary processing system for performing the methods described herein;

[0083] Fig.26 is a block diagram of an exemplary transceiver for sending and receiving signaling over a telecommunications network.

[0084] Unless otherwise indicated, corresponding numerals and symbols in the different figures generally refer to corresponding parts. These figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale. DETAILED DESCRIPTION

[0085] The making and use of the disclosed embodiments will be discussed in detail below. However, it should be understood that the concepts disclosed herein can be embodied in a variety of specific contexts, and the specific embodiments discussed herein are merely illustrative and are not intended to limit the scope of the claims. In addition, it should be understood that various changes, substitutions, and modifications may be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.

[0086] Figure 1A network 100 for transmitting data is shown. The network 100 includes a base station 110 having a coverage area 101, a plurality of user equipments (UEs) 120, and a backhaul network 130. As shown, the base station 110 establishes an uplink (dashed line) connection and / or a downlink (dotted line) connection with the UE 120, which are used to transmit data from the UE 120 to the base station 110, and vice versa. The data transmitted via the uplink / downlink connection may include data transmitted between the UEs 120 and data transmitted to / from a remote terminal (not shown) via the backhaul network 130. The term "base station" as used herein refers to any component (or collection of components) used to provide wireless access to a network, for example, NodeB, evolved NodeB (eNB), next generation (NG) NodeB (gNB), master eNB (MeNB), secondary eNB (SeNB), master gNB (MgNB), secondary gNB (SgNB), network controller, control node, access node (AN), access point (AP), transmission point (TP), transmission-reception point (TRP), cell, carrier, macro cell, femto cell, pico cell, relay station, customer premises equipment (CPE), Wi-Fi access point (AP) or other wireless enabling device. The base station can provide wireless access according to one or more wireless communication protocols such as long term evolution (LTE), advanced LTE (LTE-A), high speed packet access (HSPA), Wi-Fi802.11a / b / g / n / ac, etc. The term "user equipment" used in this article refers to any component (or collection of components) that can establish a wireless connection with a base station. UE can also be generally referred to as a mobile station, mobile device, mobile phone, terminal, user, subscriber, site, communication equipment, CPE, relay station, Integrated Access and Backhaul (IAB) relay station, etc.It should be noted that when relay technology (based on relay stations, micro cells, CPE, etc.) is used, especially when multi-hop relay technology is used, the boundary between the controller and the node controlled by the controller may become blurred, and dual nodes (e.g., controllers or nodes controlled by the controller) are deployed, wherein the first node that provides configuration or control information to the second node is considered to be the controller. Similarly, the concepts of UL transmission and DL transmission can also be expanded. In some embodiments, the network 100 may include various other wireless devices, such as relay stations, low-power nodes, etc.

[0087] Downlink and uplink transmissions (e.g., in 5G new radio (NR)) are based on demodulation reference signals (DM-RS). For example, in single user / multi user multi input multi output (SU / MU-MIMO) transmission, each DM-RS port can carry a DM-RS, which is used for channel estimation in order to demodulate the corresponding data layer transmitted on the same port. DM-RS design needs to consider different scenarios and various, sometimes conflicting requirements. Ideally, there are a large number of orthogonal DM-RS ports and one or more multiplexing schemes, while maintaining relatively small DM-RS overhead (e.g., frequency resources and / or time resources for DM-RS transmission) and ensuring good demodulation performance to support large-scale SU / MU-MIMO transmissions with a large number of data layers.

[0088] Two types (i.e., type 1 and type 2) of DM-RS configurations are introduced in NR for the DM-RS time and frequency patterns in the grid of subcarriers (in the frequency domain) and orthogonal frequency division multiplexing (OFDM) symbols (in the time domain). Type 1 DM-RS configuration supports up to 4 orthogonal DM-RS ports when 1 OFDM symbol is configured for DM-RS transmission; and up to 8 orthogonal DM-RS ports when 2 OFDM symbols are configured for DM-RS transmission. Type 2 DM-RS configuration supports up to 6 orthogonal DM-RS ports when 1 OFDM symbol is configured for DM-RS transmission; and up to 12 orthogonal DM-RS ports when 2 OFDM symbols are configured for DM-RS transmission. The orthogonal DM-RS ports used for DM-RS transmission are multiplexed in the time and frequency domains using orthogonal cover codes (OCC). Both types of DM-RS configurations can be used for downlink transmission and uplink transmission. In the present disclosure, a type 1 / type 2 DM-RS configuration may be referred to as a type 1 / type 2 DM-RS configuration, or a type 1 / type 2 configuration, or a DM-RS configuration type 1 / type 2 (Type 1 / Type 2 or type 1 / type 2). The type 1 configuration for legacy UEs is referred to as a legacy type 1 DM-RS configuration or a legacy type 1 configuration. The type 2 configuration for legacy UEs is referred to as a legacy type 2 DM-RS configuration or a legacy type 2 configuration. A DM-RS configured according to a type 1 / type 2 DM-RS configuration may be referred to as a type 1 / type 2 DM-RS.

[0089] Figure 2 200 is a schematic diagram of an exemplary resource allocation in a grid of subcarriers and OFDM symbols (i.e., resource elements (REs)) for orthogonal DM-RS antenna ports according to a conventional type 1 configuration when configuring one symbol. For the conventional type 1 configuration, a comb tooth of every other subcarrier (or tone) in frequency and an OCC pattern in frequency are assigned to the DM-RS antenna port. With 2 comb teeth and 2 OCC patterns, 4 orthogonal DM-RS ports are supported when 1 OFDM symbol (symbol #2 in this example) is configured for DM-RS transmission. Figure 2As shown, according to the exemplary traditional type 1 configuration, two CDM groups (i.e., CDM group 0 and DCM group 1) are provided. CDM group 0 includes port 0 and port 1, and CDM group 1 includes port 2 and port 3. Symbol #2 and REs at even-indexed subcarriers are allocated to CDM group 0, while symbol #2 and REs at odd-indexed subcarriers are allocated to CDM group 1. The four ports are multiplexed in the frequency domain using OCC modes [+1+1] and [+1–1], and the OCC length (or size) of these OCC modes is 2. The OCC modes [+1+1], [+1–1] can be referred to as traditional OCC modes, or traditional modes, or traditional OCCs.

[0090] In an embodiment of the present disclosure, in RE (e.g., Figure 2 The notation “n,s” shown on the box in the table is used to indicate that the RE is assigned to CDM group n and OCC value s is applied to the RE. n is an integer greater than or equal to zero (0), and s can be +, –, +1, –1, +j, or –j. “+” and “+1” represent the same OCC value “+1”. “–” and “–1” represent the same OCC value “–1”. For example, in Figure 2 , the "0,+" displayed on the RE at symbol #2 and subcarrier index 0 indicates that the RE is used for CDM group 0 and the OCC value "+1" is applied to the RE in DM-RS transmission. For another example, the "1,+" displayed on the RE at symbol #2 and subcarrier index 1 indicates that the RE is used for CDM group 1 and the OCC value "+1" is applied to the RE in DM-RS transmission. For another example, the "1,–" displayed on the RE at symbol #2 and subcarrier index 7 indicates that the RE is used for CDM group 1 and the OCC value "–1" is applied to the RE in DM-RS transmission. Figure 2 To Figure 7, Fig.10 Figure 11 Fig.18 and Fig.19 A similar notation is used in . In these figures, DM-RS ports of the same CDM group are represented by different shading.

[0091] When two (2) OFDM symbols are configured for the conventional type 1 configuration, a time domain OCC of length 2 can still be used to generate orthogonal DM-RS ports, resulting in a total of 8 orthogonal ports, such as Figure 3 shown. Figure 3300 is a schematic diagram of an exemplary resource allocation of orthogonal DM-RS antenna ports according to a conventional type 1 DM-RS configuration when two symbols are configured. In this example, two CDM groups (i.e., CDM group 0 and CDM group 1) are provided, each group including 4 ports (CDM group 0 includes ports 0, 1, 4, 5, and CDM group 1 includes ports 2, 3, 6, 7). Each port occupies symbols #2 and #3. Type 1 configuration can be configured for cyclic prefix (CP)-OFDM PDSCH and PUSCH transmission. For discrete Fourier transform-spread (DFT-s)-OFDM PUSCH, only type 1 DM-RS is used.

[0092] For DM-RS type 2 configuration, when one OFDM symbol is configured for DM-RS transmission, a frequency domain OCC of length 2 on two adjacent REs and frequency division multiplexing (FDM) are used to support six orthogonal DM-RS ports. Figure 4 4 is a schematic diagram 400 of an exemplary resource allocation for 6 ports configured according to DM RS type 2 when configuring 1 OFDM symbol. The 6 ports are included in 3 CDM groups, namely CDM group 0, CDM group 1 and CDM group 2. For example, in Figure 4 In the example, the "0,+" shown on the RE at symbol #2 and subcarrier index 0 indicates that the RE is used for CDM group 0 and the OCC value "+1" is applied to the RE in DM-RS transmission. For another example, the "2,–" shown on the RE at symbol #2 and subcarrier index 5 indicates that the RE is used for CDM group 2 and the OCC value "–1" is applied to the RE in DM-RS transmission.

[0093] When 2 OFDM symbols are configured for DM-RS transmission, the time domain OCC with a length of 2 can also be used to generate orthogonal DM-RS ports according to the DM-RS type 2 configuration, so that a total of 12 orthogonal ports are obtained. Figure 5 is a diagram 500 of an exemplary resource allocation for 12 ports according to a DM RS Type 2 configuration. With more orthogonal ports, the Type 2 configuration has the potential to provide high system throughput for massive MIMO requiring a large number of MU-MIMO data streams.

[0094] Supports two configurable 16-bit DM-RS scrambling IDs to scramble the DM-RS. The DM-RS scrambling ID can be configured through RRC signaling. The DM-RS scrambling ID can also be dynamically selected and indicated through downlink control information (DCI). Before using the RRC-configured 16-bit DM-RS scrambling ID, the cell ID is used to scramble the DM-RS.

[0095] When mapped to the symbol position of the physical downlink shared channel / physical uplink shared channel (PDSCH / PUSCH) transmission within the time slot, it can be configured to use only the pre-DM-RS symbols (for pre-DM-RS) or the pre-DM-RS plus the additional DM-RS symbols (for pre-DM-RS and additional DM-RS). The configuration of the additional DM-RS (if present) can be the same as the configuration of the pre-DM-RS for PDSCH / PUSCH transmission, that is, they can have the same number of symbols, antenna ports, sequence, etc.

[0096] For PDSCH / PUSCH mapping type A, the pre-DM-RS starts from the third or fourth symbol of each slot (or each hop if frequency hopping is supported). For PDSCH / PUSCH mapping type B, the pre-DM-RS starts from the first symbol of the transmission duration. The number of additional DM-RS symbols for each network configuration can be 1, 2, or 3.

[0097] Many antennas are envisioned in NR networks, while the number of antennas on mobile phones is relatively small. Multi-user (MU) multiple input multiple output (MIMO) technology is used to exploit the spatial dimension of a multi-antenna system to achieve high spectral efficiency. In order to achieve a good balance between MU-MIMO performance and the MU-MIMO overhead associated with a large number of layers of UEs, explicit indication of DM-RS antenna ports for multiple UEs is supported. In order to support more layers of single user (SU) / MU-MIMO transmissions, it is ideal to increase the number of orthogonal DM-RS ports without increasing the associated overhead. The associated overhead may include time resources and / or frequency resources for DM-RS transmission. For UEs in favorable conditions such as short path propagation delay and high SINR, a network that enables UEs to operate using additional orthogonal DM-RS ports can greatly improve the system MU-MIMO spectral efficiency.

[0098] In order to achieve high spectral efficiency, MU-MIMO transmission and reception need to dynamically adapt to channel conditions, UE distribution, data traffic, and various other conditions. This means that the number of MIMO layers and occupied DM-RS ports of paired UEs (e.g., two target UEs in DL MU-MIMO transmission) may vary over time (from transmission to transmission) and frequency (from resource block group (RBG) to RBG). The more transmission layers, the higher the throughput, but the DM-RS overhead is increased. In NR, in addition to the DM-RS ports for data transmission (e.g., PDSCH or PUSCH) of the target UE, DCI can also be used to indicate the number of DM-RS code division multiplexing (CDM) groups for which no data is mapped to the corresponding resource element (RE). These DM-RS CDM groups may include CDM groups for DM-RS ports of the target UE, etc., and may also include CDM groups for DM-RS ports of other UEs. DCI can be used to indicate MU-MIMO transmission and to dynamically adjust the overhead associated with MU-MIMO transmission. In the following, unless otherwise specified, the terms "DM-RS CDM group" and "CDM group" may be used interchangeably, the terms "DM-RS port", "orthogonal CDM DM-RS port", "orthogonal DM-RS port", "orthogonal port" and "port" may be used interchangeably, and the terms "antenna port" and "port" may be used interchangeably.

[0099] In order to increase the number of DM-RS ports based on the existing 5G NR DM-RS definition / configuration, one possible approach is to double the maximum number of DM-RS ports supported in 5G NR Release 17 (Rel.17) and previous releases (e.g., for legacy UEs) under 1 and 2 OFDM symbol configurations and type 1 and type 2 configurations. That is, for type 1 DM-RS, 1 OFDM symbol configuration (i.e., when one symbol is configured for DM-RS transmission) can support up to 8 orthogonal ports, and 2 OFDM symbol configurations (i.e., when two symbols are configured for DM-RS transmission) can support up to 16 orthogonal ports; for type 2 DM-RS, 1 OFDM symbol configuration can support up to 12 orthogonal ports, and 2 OFDM symbol configurations can support up to 24 orthogonal ports. The benefit of this approach is that the DM-RS configuration in Rel.17 can be retained and reused to the maximum extent, and the workload of providing additional port configurations and signaling indications can be minimized.

[0100] Embodiments of the present disclosure provide various mechanisms for providing additional orthogonal DM-RS ports in addition to the orthogonal DM-RS ports supported according to the existing 5G NR DM-RS definition / configuration (e.g., the type 1 / type 2 configuration in the above-mentioned 5G SU / MU-MIMO transmission). In some embodiments, the maximum number of orthogonal DM-RS ports currently supported in the type 1 / type 2 configuration can be doubled. To achieve this goal, two exemplary schemes (i.e., scheme 1 and scheme 2) can be considered, which will be described below using the type 1 DM-RS configuration as an example. Those of ordinary skill in the art will recognize that these schemes can be similarly applied to the type 2 configuration and any other one or more applicable DM-RS configurations. In addition, scheme 1 and scheme 2 can be combined and applied to the DM-RS configuration to provide more DM-RS ports.

[0101] Scheme 1 for additional DM-RS port configuration

[0102] In exemplary scheme 1, for type 1 DM-RS configuration, the number of comb teeth in the frequency domain can be maintained at 2, while the number of cyclic shifts in the time domain can be doubled. By applying more OCC patterns in the frequency domain, the number of cyclic shifts in the time domain can be doubled. In one embodiment, two (2) new OCC patterns can be introduced. By using these 2 new OCC patterns and 2 traditional patterns, an OCC pattern / sequence of size / length 4 can be formed, and four (4) orthogonal DM-RS ports can be formed for each comb tooth. An example of 4 OCC patterns can be [+1+1+1+1], [+1–1+1–1], [+1+j–1–j], [+1–j–1+j]. Other OCC sequences of length 4 can also be used to generate orthogonal DM-RS ports, for example, the 4 OCC patterns can be [+1+1+1+1], [+1–1+1–1], [+1+1–1–1], [+1–1–1+1].

[0103] For example, for one OFDM symbol configuration (i.e., when one symbol is configured for DM-RS transmission), when there are four modes on each of the two comb teeth, the exemplary scheme 1 provides a total of eight orthogonal DM-RS ports, such as Fig. 6A and Figure 6B shown. Fig. 6A and Figure 6B 600 is a schematic diagram of an exemplary configuration for doubling the DM-RS ports of a type 1 configuration for configuring one symbol. Ports 0 to 3 are provided according to the type 1 configuration, and ports 8 to 11 are additional ports provided according to scheme 1. The pattern of ports 0 to 3 is a legacy port pattern defined in the current 5G NR specification, and the pattern of ports 8 to 11 as shown in the figure is an additional port pattern.

[0104] As another example, for a 2-OFDM symbol configuration (i.e., when two symbols are configured for DM-RS transmission), in addition to applying two new OCC patterns in the frequency domain, the same traditional time domain OCC of length 2, i.e., {[+1+1], [+1–1]}, can also be used to double the orthogonal DM-RS ports, thereby obtaining a total of 16 orthogonal DM-RS ports, as shown in FIG. 7A to 7D shown. 7A to 7D FIG. 7 is a diagram 700 of an exemplary configuration for doubling the DM-RS ports of a type 1 configuration that configures two symbols.

[0105] In exemplary scheme 1, the number of CDM groups may remain the same as in the type 1 DM-RS configuration in Rel.17. Fig. 6A and Figure 6B as well as 7A to 7D A pattern is shown for each orthogonal port distributed over 2 resource blocks. This pattern repeats every 2 resource blocks; however, the actual number of resource blocks scheduled for DM-RS transmission is not necessarily a multiple of 2.

[0106] Therefore, by adopting Scheme 1, the Type 1 configuration can support 8 ports configured with a single OFDM symbol and 16 ports configured with a dual OFDM symbol. For ease of description, the ports provided by the Type 1 configuration in 5G NR Rel.17 and previous versions may be referred to as the first group of Type 1 (DM-RS) ports, and the ports provided by the Type 1 configuration applying Scheme 1 may be referred to as the second group of Type 1 ports. The second group of Type 1 ports includes the first group of Type 1 ports and additional DM-RS ports added by Scheme 1. Scheme 1 doubles the first group of Type 1 ports. The second group of Type 1 ports may each be assigned an index p, where p = 0, 1...15. For ease of description, port numbers 0 to 7 are used to refer to traditional DM-RS ports, and port numbers 8 to 15 are used to refer to additional DM-RS ports added by Scheme 1.

[0107] Figure 8 Exemplary relative time positions of the second set of Type 1 DM-RS ports are shown, which are obtained by converting the received DM-RS signal to the time domain. Figure 8 Including the second group of type 1 ports when configuring an OFDM symbol (i.e. Fig. 6A and Figure 6B Table 800 of the relative time positions of the ports shown in FIG. 8 . Four ports are provided on each of the two comb teeth (comb tooth 0 and comb tooth 1), for a total of 8 ports. Figure 8 Table 820 in FIG. 8 shows the second group of type 1 ports (i.e. 7A to 7D The relative time positions of the ports shown are shown in FIG. 8 . Eight ports are provided on each of the two comb teeth, for a total of sixteen (16) ports. Figure 8The cyclic shifts applied to these ports respectively are also shown.

[0108] In some embodiments, to map the DM-RS sequence to the resource elements (REs) of each DM-RS port with indices p=0, 1, ... 15, according to the modified equation in Section 7.4.1.1.2 of TS 38.211, the UE may assume such mapping according to the following equation:

[0109]

[0110] k=8n+2k′+ΔConfigurationtype1

[0111] k′=0,1,2,3Configurationtype1

[0112]

[0113] n=0,1…

[0114] in, is the scaling factor, is to be mapped to resource unit (k,l) p,u The result value of the DM-RS sequence, k and l are the subcarrier index and symbol index, indicating the resource unit, w t (l′) and time domain related parameters and l′ are defined in the same manner, given by Tables 7.4.1.1.2-1, 7.4.1.1.2-2, 7.4.1.1.2-3, 7.4.1.1.2-4, and 7.4.1.1.2-5 in the 5G NR TS 38.211 specification, the entire contents of which are incorporated herein by reference. r(n) is defined in Section 7.4.1.1.1 of the 5G NR 38.211 specification. It can be calculated as:

[0115]

[0116] Table 1 below shows exemplary parameters for mapping. Table 1 is obtained by modifying Table 7.4.1.1.2-1 in TS 38.211. For example, the parameter "p" in Table 1 is associated with the DM-RS port index (0, 1...15), p=1000+DM-RS port index. In each entry in Table 1, the parameter w f(k′) (where k′=0, 1, 2, 3) indicates a frequency domain (FD)-OCC of length 4 associated with the corresponding parameter p in the entry and its associated DM-RS port (e.g., DM-RS port index=p–1000). Here, FD-OCC refers to OCC applied in the frequency domain (e.g., applied to REs in the same OFDM symbol). For example, the entry with p=1008 indicates that the FD-OCC pattern [+1–j–1+j] is applied to DM-RS port 8, and the entry with p=1009 indicates that the FD-OCC pattern [+1+j–1–j] is applied to DM-RS port 9. In Table 1, only the DM-RS ports indicated by parameter “p” and parameter w are not related. f (k′) as an example. There may also be other alternatives / variants for associating DM-RS ports and FD-OCC. For example, the FD-OCC patterns of p=1008 and p=1009 shown in Table 1 can be switched so that the FD-OCC pattern [+1+j–1–j] is applied to DM-RS port 8, and the FD-OCC pattern [+1–j–1+j] is applied to DM-RS port 9. Similarly, the FD-OCC patterns of p=1010 and p=1011 can be switched. Similar switching can be applied to p=1012 and p=1013 and p=1014 and p=1015.

[0117] Table 1

[0118]

[0119] In Rel.17, in order to achieve a good balance between MU-MIMO performance and the overhead associated with a possible large number of layers of the UE, explicit indication of DM-RS antenna ports for multiple UEs is supported. The DCI message (e.g., format 1-1) is used to indicate to the UE the number of scheduled DM-RS ports, the index of each DM-RS port, and the CDM group of the co-scheduled UE for MU-MIMO transmission. By reading the entries corresponding to the antenna port bit values ​​in the DCI message from the lookup tables of the 5G NR TS 38.212 specification, the detailed DM-RS port index, mapping and co-scheduling CDM group can be obtained. These lookup tables are Table 7.3.1.2.2-1 and Table 7.3.1.2.2-1A for type 1 1 OFDM symbol configuration, Table 7.3.1.2.2-2 and Table 7.3.1.2.2-2A for type 1 2 OFDM symbol configuration, Table 7.3.1.2.2-3 and Table 7.3.1.2.2-3A for type 2 1 OFDM symbol configuration, and Table 7.3.1.2.2-4 and Table 7.3.1.2.2-4A for type 2 2 OFDM symbol configuration.

[0120] Under certain channel conditions (e.g., channels with large path propagation delays), reducing the DM-RS density in the frequency domain or the cyclic shift duration in the time domain may result in a degradation of the MU-MIMO performance of the UE. Reducing the DM-RS resource overhead per port may easily result in poor DM-RS channel estimation due to a lower effective operating signal to interference and noise ratio (SINR). Therefore, it is desirable that the UE may choose to operate under the conventional DM-RS port configuration, indexing, mapping, and indication.

[0121] As the maximum number of orthogonal DM-RS ports doubles, the port combinations, signaling indications, and message mappings also grow significantly. If additional orthogonal DM-RS ports are provided only for MU-MIMO transmission, and the Rel.17 design for port combinations, signaling indications, and message mapping is satisfactory, it is ideal to leverage the legacy design as much as possible and minimize the necessary modifications to minimize the standards work and enjoy the performance gains from the additional orthogonal DM-RS ports.

[0122] Therefore, it can be understood that the design of the port index, grouping, and signaling of Scheme 1 takes into account backward compatibility with legacy UEs as much as possible and avoids completely redesigning the port index, grouping, and signaling. If the addition of additional DR-MS ports in Rel.18 is for MU-MIMO scenarios, it is desirable to reuse the legacy DM-RS port index, grouping, and signaling as much as possible.

[0123] For SU-MIMO scenarios, the traditional design can be reused. As described in Section 7.3.1.2 of [5, TS 38.212] (the entire contents of which are incorporated herein by reference), the UE can be scheduled using a small number of DM-RS ports by indexing the antenna ports under DCI format 1_1.

[0124] TS 38.212 specifies that for DM-RS configuration type 1,

[0125] - if the UE is scheduled using one codeword and is assigned an antenna port mapping with index {2, 9, 10, 11 or 30} in Table 7.3.1.2.2-1 and Table 7.3.1.2.2-2 of Section 7.3.1.2 of [5, TS 38.212], or

[0126] - If the UE is scheduled using one codeword and is assigned an antenna port mapping with an index of {2, 9, 10, 11 or 12} in Table 7.3.1.2.2-1A of Section 7.3.1.2 of [5, TS 38.212] and {2, 9, 10, 11, 30 or 31} in Table 7.3.1.2.2-2A,

[0127] or

[0128] -If the UE uses two codewords for scheduling,

[0129] The UE may then assume that all remaining orthogonal antenna ports are not associated with PDSCH transmissions of other UEs.

[0130] In some embodiments, for DM-RS configuration type 1 of SU / MU-MIMO scenarios and application scheme 1, the UE may be configured with two operating modes for DM-RS port indication: mode 1 and mode 2. When the network indicates the DM-RS port to be used for communication with the UE, the UE may interpret the indication according to its mode. When operating in mode 1, the DM-RS ports available to the UE may include only the first group of type 1 ports supported by the type 1 configuration; when operating in mode 2, the DM-RS ports available to the UE may include a second group of type 1 ports generated according to scheme 1.

[0131] Mode 1: Traditional DM-RS CDM port

[0132] In this mode of operation, the DCI message is transmitted and interpreted in the same manner as described in Section 7.3.1.2.2 of TS 38.212 and Section 5.1.6.2 of TS 38.214 (the entire contents of which are incorporated herein by reference). The definition of DM-RS ports follows the traditional definition. The DCI message may indicate a port in the first group of type 1 ports. The purpose of this mode may be to better handle longer propagation path delays or to be backward compatible with legacy UEs.

[0133] Mode 2: Doubling the DM-RS CDM ports

[0134] In this working mode, scheme 1 is applied, the number of DM-RS ports is doubled, and the time length corresponding to the cyclic shift time position of each DM-RS port is halved. The DM-RS ports in this mode include the second group of type 1 ports as described above. This mode can be used to multiplex more UE transmissions simultaneously.

[0135] In some embodiments, in order to use DCI to indicate orthogonal DM-RS ports in working mode 2, a new bit may be defined outside the traditional DCI message, or a bit in the traditional DCI message may be redefined. This bit may be called a DM-RS port offset bit, and in one embodiment, may be designed as follows:

[0136] - If the DM-RS port offset bit is 0, no port offset is added;

[0137] - If the DM-RS port offset bit is 1, the port index of the corresponding entry in the corresponding lookup table (e.g., Table 7.3.1.2.2-1, Table 7.3.1.2.2-1A, Table 7.3.1.2.2-2, and Table 7.3.1.2.2-2A in TS 38.212) is increased by 8;

[0138] - Alternatively, a bit value of 1 for the DM-RS port offset bit indicates that no port offset is added, while a bit value of 0 for the DM-RS port offset bit indicates that the port index is increased by 8.

[0139] For example, the maximum length of an OFDM symbol (e.g., the maximum number of OFDM symbols for a leading DM-RS) is 2, and Table 7.3.1.2.2-2 in 38.212 (as shown in Table 2 below) is used for the lookup table of DM-RS ports. Assuming that one codeword is enabled and the value of the antenna port bit is 26 (i.e., the value in Table 2 = 26), DM-RS ports 0, 1, and 4 are indicated according to Table 2. If the DM-RS port offset bit is 0, the UE may expect DM-RS transmission on DM-RS ports 0, 1, and 4. If the DM-RS port offset bit is 1, the UE may expect DM-RS transmission on ports 8, 9, and 12 by adding 8 to 0, 1, and 4.

[0140] Table 7.3.1.2.2-2: Antenna port (1000 + DM-RS port), dmrs-Type = 1, maxLength = 2

[0141] Table 2

[0142]

[0143]

[0144] In some embodiments, when the DM-RS port offset bit is 1, a new lookup table may be created to provide the DM-RS ports in operating mode 2. Using the same example as above (where value = 26), if the DM-RS port offset bit is 1, the UE may read the DM-RS port index directly from a new lookup table (e.g., Table 3 below) obtained by modifying Table 7.3.1.2.2-2 in 38.212. Table 7.3.1.2.2-1, Table 7.3.1.2.2-1A, and Table 7.3.1.2.2-2A may be similarly modified.

[0145] Table 3

[0146]

[0147]

[0148] In one embodiment, for example, one of the two working modes can be specifically configured to the UE and activated by high-level signaling such as radio resource control (RRC) signaling. In another embodiment, the two working modes can be configured to the UE through high-level (e.g., RRC) signaling, and one of the two working modes can be activated through RRC signaling, medium access control-control element (MAC-CE) or DCI. In order to achieve flexible network scheduling, it is hoped that the network can coordinate the scheduling of MU-MIMO UEs in hybrid working mode.

[0149] In some embodiments, the network can dynamically instruct the UE to dynamically switch between the two modes by defining a new bit outside the traditional DCI message or redefining the bit in the traditional DCI message. This bit can be called the DM-RS working mode bit and can be defined as follows:

[0150] -If the DM-RS operating mode bit is 1, the UE operates in mode 1;

[0151] - If the DM-RS operating mode bit is 0, the UE operates in mode 2;

[0152] -Alternatively, if the DM-RS operating mode bit is 0, the UE operates in mode 1; if the DM-RS operating mode bit is 1, the UE operates in mode 2.

[0153] For example, assuming that the maximum length of an OFDM symbol is 1, Table 7.3.1.2.2-1 in TS 38.212 (as shown in Table 4 below) can be used for table lookup.

[0154] Table 7.3.1.2.2-1: Antenna port (1000+DM-RS port), dmrs-Type=1, maxLength=1 Table 4

[0155]

[0156] In this example, 4 UEs (UE1 to UE4) are scheduled for MU-MIMO transmission, and the network can indicate a mode to each UE, thereby indicating that the UE operates in the indicated mode. Each UE determines the DM-RS port according to the indicated mode, the indicated value (antenna port bit value) corresponding to the DM-RS port (e.g., "value" in Table 4), the indicated DM-RS port offset bit value and the lookup table, as described below:

[0157] - Indicates that UE1 operates in mode 2 and indicates that UE1 has antenna port bit value 7 and DM-RS port offset bit value 0

[0158] (eg, indicating that no port offset is added) UE1 desires DM-RS transmission on ports 0 and 1 in the second group of type 1 ports according to Table 4.

[0159] - Indicates that UE2 operates in mode 2 and indicates that UE2 has antenna port bit value 3 and DM-RS port offset bit value 1

[0160] (For example, indicating that the port index of the corresponding entry in the lookup table is increased by 8.) UE2 expects to perform DM-RS transmission on port 8 (ie, port 0+8=port 8) according to Table 4.

[0161] - Indicates that UE3 operates in mode 2, and indicates that UE3 has an antenna port bit value of 4 and a DM-RS port offset bit value of 1.

[0162] UE3 expects to perform DM-RS transmission on port 9 (ie, port 1+8=port 9) according to Table 4.

[0163] - Indicates that UE4 operates in mode 1, and indicates that UE4 has an antenna port bit value of 8 and a DM-RS port offset bit value of 0.

[0164] UE4 expects DM-RS transmission on ports 2 and 3 under the legacy DM-RS port definition.

[0165] Fig. 9 FIG. 9 is a diagram of exemplary DM-RS port allocations of UE1 to UE4 in the cyclic shift and comb domains. UE4 has a legacy duration, which is beneficial for handling longer propagation path delays or backward compatibility.

[0166] Solution 2: Solution 2 for additional DM-RS port configuration

[0167] In some embodiments, to provide additional DM-RS ports in a Type 1 configuration, the number of comb teeth in the frequency domain can be increased, for example, from 2 to 4, while the number of cyclic shifts in the time domain can remain at 2. Doubling the number of comb teeth in the frequency domain can halve the DM-RS RE density (each DM-RS port occupies half the subcarriers in a resource block). Each comb tooth carries 2 orthogonal DM-RS ports via cyclic shift CDM (e.g., using a frequency domain OCC pattern), and the 4 comb teeth together provide 8 ports in a single OFDM symbol configuration. For a dual OFDM symbol configuration, the same time domain conventional OCC of length 2, i.e., {[+1+1],[+1–1]}, can be used to double the orthogonal DM-RS ports, resulting in a total of 16 orthogonal DM-RS ports.

[0168] Fig.10 Figure 11 shows the pattern for each orthogonal port distributed over 2 resource blocks, where scheme 2 with 4 comb teeth is applicable to type 1 configuration. Note that these patterns are repeated every 2 resource blocks, but the actual number of resource blocks scheduled for DM-RS transmission is not necessarily a multiple of 2. Fig.10 1000 is a schematic diagram of an exemplary configuration for doubling the DM-RS ports under the type 1 DM-RS configuration for configuring a single OFDM symbol according to Scheme 2. Compared with the NR traditional DM-RS configuration, the frequency density of each DM-RS port is halved. Since the number of comb teeth increases from 2 to 4, the number of CDM groups also increases from 2 to 4 (i.e., CDM groups 0 to 3 as shown in the figure). In this example, the DM-RS port index is mapped to the CDM group index so that ports 0 to 3 have the same comb tooth offset as the traditional DM-RS configuration, i.e., ports 0 and 1 are on comb tooth offset 0 corresponding to CDM group 0, and ports 2 and 3 are on comb tooth offset 1 corresponding to CDM group 1. For additional DM-RS port indexes, ports 8 and 9 are on comb tooth offset 2 corresponding to CDM group 2, and ports 10 and 11 are on comb tooth offset 3 corresponding to CDM group 3.

[0169] Fig.11A and Fig. 11B1100 is a schematic diagram of an exemplary configuration for doubling the DM-RS ports under the type 1 DM-RS configuration of dual OFDM symbols configured according to Scheme 2. Compared with the NR traditional DM-RS configuration, the frequency density of each DM-RS port is halved. Since the number of comb teeth increases from 2 to 4, the number of CDM groups also increases from 2 to 4 (i.e., CDM groups 0 to 3 as shown in the figure). In this example, the DM-RS port index is mapped to the CDM group index so that ports 0 to 7 have the same comb tooth offset as the traditional DM-RS configuration, i.e., ports 0, 1, 4, 5 are on comb tooth offset 0 corresponding to CDM group 0, and ports 2, 3, 6, 7 are on comb tooth offset 1 corresponding to CDM group 1. For additional DM-RS port indexes, ports 8, 9, 12, 13 are on comb tooth offset 2 corresponding to CDM group 2, and ports 10, 11, 14, 15 are on comb tooth offset 3 corresponding to CDM group 3.

[0170] Fig.12 yes Fig.10 1200 is a diagram of exemplary relative time positions of DM-RS ports in an example of , which are obtained by converting the received DM-RS signal into the time domain. Fig.12 Eight DM-RS ports are shown with corresponding comb teeth in the frequency domain and cyclic shifts in the time domain.

[0171] Fig.13 yes Fig.11A and Fig. 11B 1300 is a diagram of exemplary relative time positions of DM-RS ports in an example of , which are obtained by converting the received DM-RS signal into the time domain. Fig.13 16 DM-RS ports are shown with corresponding comb teeth in the frequency domain and cyclic shifts in the time domain.

[0172] In some embodiments, in order to map the DM-RS sequence to the resource elements of the DM-RS ports with indices p=0, 1, 2, ... 15 in Scheme 2, according to the modified equation in Section 7.4.1.1.2 of TS 38.211, the UE may assume the mapping according to the following equation:

[0173]

[0174] k=8n+2k′+ΔConfigurationtype1

[0175] k′=0,1Configurationtype1

[0176]

[0177] n=0,1…

[0178] Among them, w t (l′) and time domain related parameters and l' are defined in the same way, given by Table 7.4.1.1.2-1, Table 7.4.1.1.2-2, Table 7.4.1.1.2-3, Table 7.4.1.1.2-4 and Table 7.4.1.1.2-5 in the 5G NR TS 38.211 specification. r(n) is defined in Section 7.4.1.1.1 of the 5G NR TS 38.211 specification. Table 5 below shows exemplary parameters for mapping. This table is obtained by modifying Table 7.4.1.1.2-1 in TS 38.211.

[0179] Table 5

[0180]

[0181]

[0182] Similar to what is described in conjunction with Solution 1, the design of the port index, grouping, and signaling of Solution 2 also needs to be backward compatible with legacy UEs as much as possible to avoid completely redesigning the port index, grouping, and signaling. If the purpose of adding additional DR-MS ports in Rel.18 is only for MU-MIMO scenarios rather than SU-MIMO scenarios, the legacy DM-RS port index, grouping, and signaling can be reused as much as possible.

[0183] For SU-MIMO scenarios, the traditional design can be reused. As described in Section 7.3.1.2 of [5, TS 38.212], the UE can use a small number of DM-RS ports for scheduling through antenna port indexing under DCI format 1_1.

[0184] TS 38.212 specifies that for DM-RS configuration type 1,

[0185] - if the UE is scheduled using one codeword and is assigned an antenna port mapping with index {2, 9, 10, 11 or 30} in Table 7.3.1.2.2-1 and Table 7.3.1.2.2-2 of Section 7.3.1.2 of [5, TS 38.212], or

[0186] - If the UE is scheduled using one codeword and is assigned an antenna port mapping with an index of {2, 9, 10, 11 or 12} in Table 7.3.1.2.2-1A of Section 7.3.1.2 of [5, TS 38.212] and {2, 9, 10, 11, 30 or 31} in Table 7.3.1.2.2-2A,

[0187] or

[0188] -If the UE uses two codewords for scheduling,

[0189] The UE may then assume that all remaining orthogonal antenna ports are not associated with PDSCH transmissions of other UEs.

[0190] For ease of description, the ports provided by the type 1 configuration of solution 2 are referred to as the third group of type 1 ports. The third group of type 1 ports includes the first group of type 1 ports and the additional DM-RS ports added by solution 2. In some embodiments, for SU / MU-MIMO scenarios and DM-RS configuration type 1 of solution 2, the UE may be configured with three working modes for DM-RS port indication:

[0191] Mode 1: Traditional DM-RS CDM port

[0192] In this mode of operation, DCI messages are transmitted and interpreted in the same manner as described in Section 7.3.1.2.2 of TS 38.212 and Section 5.1.6.2 of TS 38.214. The definition of DM-RS ports follows the traditional definition. The DCI message may indicate a port in the first group of Type 1 ports. This mode may be used to better handle longer propagation path delays or for backward compatibility with legacy UEs.

[0193] Mode 2: Double the DM-RS CDM ports and double the CDM groups with no data

[0194] In this mode of operation, Scheme 2 is applied, doubling the number of DM-RS CDM ports and halving the frequency density of each DM-RS CDM port. The number of DM-RS CDM groups without data is also doubled according to the number of DM-RS CDM groups without data scheduled. The DM-RS ports in this mode include the third group of type 1 ports as described above. This mode can be used to multiplex more UE transmissions simultaneously.

[0195] Mode 3: Double the DM-RS CDM ports only

[0196] In this mode of operation, the number of DM-RS CDM ports is doubled and the frequency density of each DM-RS CDM port is halved. The number of DM-RS CDM groups without data is not doubled. The DM-RS ports in this mode include the third group of type 1 ports as described above. This mode can be used to achieve high spectral efficiency and reduce UE DM-RS overlap in the frequency domain.

[0197] In order to indicate the DM-RS port in modes 2 and 3, a new bit, namely the DM-RS port offset bit, may be defined outside the traditional DCI message, or the bit in the traditional DCI message may be redefined. In one embodiment, the bit may be defined as follows:

[0198] - If the DM-RS port offset bit is 0, no port offset is added;

[0199] - If the DM-RS port offset bit is 1, the port index of the corresponding entry in the corresponding lookup table (e.g., Table 7.3.1.2.2-1, Table 7.3.1.2.2-1A, Table 7.3.1.2.2-2, or Table 7.3.1.2.2-2A in TS 38.212) is increased by 8;

[0200] - Alternatively, a bit value of 1 for the DM-RS port offset bit indicates that no port offset is added, while a bit value of 0 for the DM-RS port offset bit indicates that the port index is increased by 8.

[0201] For DM-RS type 1 with doubled ports using Scheme 2, the maximum number of DM-RS CDM groups without data increases from 2 to 4. The indication of the number of DM-RS CDM groups without data also changes accordingly. Mode 2 and Mode 3 are used to handle this situation in different ways.

[0202] For Mode 2, the network schedules multiple UEs for simultaneous transmission. In one embodiment, the UE may determine the number of CDM groups and DM-RS ports as described below. The UE may derive DM-RS port transmission information based on the antenna port bits and DM-RS port offset bits indicated in the received DCI signaling. The UE may search the lookup table and read the entry in the lookup table corresponding to the received antenna port bits. The UE may derive the number of CDM groups without data by doubling the corresponding number in the entry. The additional DM-RS CDM group index without data may be obtained by adding 2 to the DM-RS CDM group index in the entry.

[0203] For example, if the configuration of DM-RS is type 1 and the maximum length of OFDM symbol is 2, Table 7.3.1.2.2-2 in TS 38.212 (Table 2 above) can be used for table lookup. In this example, one codeword is enabled and the value of the antenna port bit is 26. From the entry corresponding to the value 26 in the lookup table (Table 2), the indicated DM-RS ports are 0, 1, 4, and the number of data-free DM-RS CDM groups indicated is 2, that is, two DM-RS CDM groups indexed {0, 1}. The UE then doubles the number 2 to obtain the number of new data-free DM-RS CDM groups, that is, 4. The UE can then add 2 to {0, 1} to obtain the indices of the two new data-free DM-RS CDM groups, that is, {2, 3}, and merge these indices with the group index {0, 1} to obtain the final data-free DM-RS CDM group indices, that is, {0, 1, 2, 3}. If the DM-RS Port Offset bit is 0, the UE expects DM-RS transmission on ports 0, 1, 4. If the DM-RS Port Offset bit is 1, the UE adds 8 to {0, 1, 4} and expects DM-RS transmission on ports 8, 9, 12.

[0204] In some embodiments, if the DM-RS port offset bit is 0, the UE can directly read the DM-RS port index and the number of DM-RS CDM groups without data from the new lookup table obtained by modifying Table 7.3.1.2.2-2. If the DM-RS port offset bit is 1, the UE can directly read the DM-RS port index and the number of DM-RS CDM groups without data from other new lookup tables x obtained by modifying Table 7.3.1.2.2-2. Table 7.3.1.2.2-1, Table 7.3.1.2.2-1A and Table 7.3.1.2.2-2A can be similarly modified.

[0205] For mode 3, the network schedules multiple UEs for simultaneous transmission. In some embodiments, the UE can derive the DM-RS port transmission information based on the antenna port bits and DM-RS port offset bits indicated in the received DCI signaling. The UE can search the lookup table and read the entry corresponding to the received antenna port bits in the lookup table. If the DM-RS port offset bit is 0, the DM-RS CDM group index of the data-free is the same as the index of the entry. If the DM-RS port offset bit is 1, the DM-RS CDM group index of the data-free can be derived by adding 2 to the DM-RS CDM group index in the entry.

[0206] For example, if the DM-RS is configured as type 1 and the maximum length of the OFDM symbol is 2, Table 7.3.1.2.2-2 in TS 38.212 (Table 2 above) can be used for table lookup. In this example, one codeword is enabled and the value of the antenna port bit is 26. From the entry corresponding to the value 26 in the lookup table (Table 2), the indicated DM-RS ports are 0, 1, and 4, and the number of data-free DM-RS CDM groups is 2, that is, two DM-RS CDM groups indexed {0, 1}. If the DM-RS port offset bit is 0, the UE can directly derive the index of the data-free DM-RS CDM group based on the indicated value {0, 1} (based on the number of data-free CDM groups and the indicated DM-RS port), and expects DM-RS transmission on ports 0, 1, and 4. If the DM-RS port offset bit is 1, the UE adds 2 to {0, 1} to obtain the index of the final data-free DM-RS CDM group, i.e., {2, 3}, and expects to perform DM-RS transmission on ports 8, 9, and 12 by adding 8 to ports 0, 1, and 4.

[0207] In some embodiments, if the DM-RS port offset bit is 0, the UE may read the DM-RS port index and the number of DM-RS CDM groups without data directly from the new lookup obtained by modifying Table 7.3.1.2.2-2. If the DM-RS port offset bit is 1, the UE may read the DM-RS port index and the number of DM-RS CDM groups without data directly from the new lookup table x obtained by modifying Table 7.3.1.2.2-2. Table 7.3.1.2.2-1, Table 7.3.1.2.2-1A, and Table 7.3.1.2.2-2A may be similarly modified.

[0208] In one embodiment, one of the three working modes can be specifically configured for each UE and activated through high-layer signaling such as RRC signaling. In another embodiment, one of the mode combinations (e.g., a mode combination of modes 1 and 2, or a mode combination of modes 1 and 3) can be configured for each UE through high-layer signaling such as RRC signaling, and one of the two modes in the configured mode combination can be activated through RRC signaling, MAC-CE, or DCI.

[0209] In some embodiments, the network can dynamically instruct the UE to switch between two modes (i.e., modes 1 and 2, or modes 1 and 3) in the configured mode combination by defining a new bit outside the traditional DCI message or redefining the bit in the traditional DCI message. This bit can be called a DM-RS working mode bit.

[0210] When this bit is configured for a mode combination of Mode 1 and Mode 2, the bit may be defined as follows, for example:

[0211] -If the DM-RS operating mode bit is 1, the UE operates in mode 1;

[0212] - If the DM-RS operating mode bit is 0, the UE operates in mode 2;

[0213] -Alternatively, if the DM-RS operating mode bit is 0, the UE operates in mode 1; if the DM-RS operating mode bit is 1, the UE operates in mode 2.

[0214] When this bit is configured for the mode combination of mode 1 and mode 3, the bit can be defined as follows, for example:

[0215] -If the DM-RS operating mode bit is 1, the UE operates in mode 1;

[0216] - If the DM-RS operating mode bit is 0, the UE operates in mode 3;

[0217] -Alternatively, if the DM-RS operating mode bit is 0, the UE operates in mode 1; if the DM-RS operating mode bit is 1, the UE operates in mode 3.

[0218] For example, assuming that the maximum length of an OFDM symbol is 1, Table 7.3.1.2.2-1 in 38.212 (Table 4 above) can be used for table lookup. In the case of scheduling 4 UEs for MU-MIMO transmission, the network can indicate a mode to each UE. Each UE can determine the DM-RS port based on the network's signaling, as described below:

[0219] - Indicates that UE1 operates in mode 2 and indicates that UE1 has antenna port bit value 7 and DM-RS port offset bit value 0

[0220] (eg, indicating that no port offset is added.) UE1 desires DM-RS transmission on ports 0 and 1 on comb 0.

[0221] - Indicates that UE2 operates in mode 2 and indicates that UE2 has antenna port bit value 3 and DM-RS port offset bit value 1

[0222] (For example, indicating that the port index of the lookup table is increased by 8.) UE2 expects to perform DM-RS transmission on port 8 (port 0+8) on comb 2.

[0223] - Indicates that UE3 operates in mode 2, and indicates that UE3 has an antenna port bit value of 4 and a DM-RS port offset bit value of 1.

[0224] UE3 desires to perform DM-RS transmission on port 9 (port 1+8) on comb tooth 2.

[0225] - Indicates that UE4 operates in mode 1, and indicates that UE4 has an antenna port bit value of 8 and a DM-RS port offset bit value of 0.

[0226] UE4 expects DM-RS transmission on ports 2 and 3 on comb 1 under the legacy DM-RS port definition (combs 1 and 3 under the new DM-RS port definition).

[0227] Fig.14 FIG1400 is a schematic diagram of DM-RS port allocation in the cyclic shift and comb domains for UE1 to UE4 in the above example. UE4 has a traditional duration to better handle longer propagation path delays or backward compatibility.

[0228] For the working modes of Scheme 1 and Scheme 2, Figures 15 to 17 A corresponding flow chart is shown. Figures 15 to 17 Exemplary methods for configuring modes and activating modes for UEs are provided, including message exchanges between UEs and gNBs. These exemplary methods can be applied to two working modes under scheme 1 and three working modes under scheme 2. The exemplary methods shown take PDSCH transmission as an example for reference only, and can also be applied to PUSCH and other applicable channel / signal transmissions.

[0229] Fig.151 is a flow chart highlighting an exemplary method 1500 for mode configuration and activation via RRC signaling. The gNB may send a DM-RS configuration and a mode configuration to a UE via RRC signaling, and activate one of the two configured modes for the UE via RRC signaling (step 1502). For example, the mode configuration may configure two operating modes under scheme 1 or a mode combination under scheme 2 (e.g., mode 1 and mode 3, or mode 1 and mode 2) for the UE, and may activate / indicate one of the two modes for use by the UE. The configuration and activation / indication may use the same RRC signaling or separate RRC signaling. In one embodiment, the mode configuration may include information indicating the two modes configured for the UE, such as indices or identifiers of the two modes. In another embodiment, for scheme 1, the mode configuration may be performed by configuring an orthogonal cover code (OCC) pattern of length / size 4 (corresponding to mode 2) and an OCC pattern of length 2 (corresponding to mode 1) for DM-RS communication. In another embodiment, for scheme 1, the mode configuration can be performed by configuring a frequency domain OCC (FD-OCC) length of 4 (corresponding to mode 2) and a FD-OCC length of 2 (corresponding to mode 1). Two different FD-OCC lengths can be indicated by indexes or identifiers associated with the two different lengths, respectively. Therefore, the UE can understand that the two modes are configured by itself based on the indicated OCC patterns of different lengths or the indicated different OCC lengths. In this case, activation can be performed by indicating one of the lengths of the OCC pattern (an OCC pattern of length 4 or an OCC pattern of length 2), so that the UE understands which mode is activated. For example, the OCC can be indicated by the antenna port field in the DCI. An embodiment of the mode configuration can be applicable to Fig.16 and Fig.17 The method shown. For SU / MU-MIMO, the mode configuration can be specifically configured for each UE, and a mode is activated through high-level RRC signaling. The DM-RS configuration includes one or more type 1 and / or type 2 DM-RS configurations, the maximum length of OFDM symbols, and other information.

[0230] In response to receiving the configuration and activation in step 1502, the UE may send a configuration confirmation to the gNB (step 1504). The gNB may then schedule the PDSCH for the UE via a DCI message on the PDCCH (step 1506), and send the PDSCH accordingly (step 1508). The DM-RS corresponding to the PDSCH is also sent to the UE. The DCI includes DM-RS port information. The UE acquires the information of the DM-RS port according to the DCI and activation mode as described above, receives the DM-RS on the acquired DM-RS port, and receives the PDSCH according to the DM-RS. The UE may send a PDSCH confirmation / negative confirmation (ACK / NACK) to the gNB to indicate whether the PDSCH is successfully received (step 1510). Steps 1508 and 1510 may be performed in a conventional manner.

[0231] Fig.16 is a flow chart highlighting an exemplary method 1600 for configuring two modes via higher-layer RRC signaling and activating one of the two modes via MAC-CE. The gNB may send a DM-RS configuration and a mode configuration to the UE via RRC signaling (1602). The mode configuration may configure the UE with two operating modes under scheme 1 or a combination of modes under scheme 2 (e.g., mode 1 and mode 3, or mode 1 and mode 2). As described above, the mode configuration may directly indicate the two modes, or indicate two OCC modes of length 2 and 4 for scheme 1, or indicate two OCC lengths (e.g., OCC length 2 and OCC length 4). In response to receiving the configuration in step 1602, the UE may send a configuration confirmation to the gNB (step 1604). The gNB may activate one of the configured modes via MAC-CE (step 1606). The MAC-CE may include an index or identifier of the mode to be activated; or may indicate OCC length 2 or OCC length 4 as described above for scheme 1. Steps 1608 to 1612 are similar to steps 1506 to 1510. The gNB may schedule the PDSCH for the UE via a DCI message on the PDCCH (step 1608) and transmit the PDSCH accordingly (step 1610). The UE receives the PDSCH based on the DM-RS through the DM-RS ports, which are determined based on the DCI message and the activation mode as described above. The UE may send a PDSCH ACK / NACK to the gNB (step 1612).

[0232] Fig.171 is a flowchart highlighting an exemplary method 1700 for configuring two modes via RRC signaling and activating one of the two modes via a DCI message. In this embodiment, the network may dynamically instruct the UE to switch between the two configured modes via a DCI message. As shown, the gNB may send a DM-RS configuration and a mode configuration to the UE via RRC signaling (1702). The mode configuration may configure the UE with two operating modes under scheme 1 or a combination of modes under scheme 2 (e.g., mode 1 and mode 3, or mode 1 and mode 2). As described above, the mode configuration may directly indicate the two modes, or indicate two OCC modes of length 2 and 4 for scheme 1, or indicate two OCC lengths (e.g., OCC length 2 and OCC length 4). In response to receiving the configuration in step 1702, the UE may send a configuration confirmation to the gNB (step 1704). The gNB may activate one of the configured modes via a DCI message. The DCI message may include an index or identifier of the mode to be activated; or may indicate an OCC length 2 or an OCC length 4 as described above for scheme 1. If the UE is already in one mode, the DCI message serves as an instruction to switch the UE to the active mode. In one embodiment, the gNB may schedule PDSCH for the UE via a DCI message on the PDCCH, and may also activate one of the two modes via a DCI message (step 1706). The gNB sends the PDSCH (step 1708), and the UE receives the PDSCH based on the DM-RS through the DM-RS ports, which are determined based on the DCI message and the activation mode as described above. The UE may send a PDSCH ACK / NACK to the gNB, indicating whether the PDSCH was successfully received (step 1710).

[0233] Scheme 1 or Scheme 2 achieves the goal of doubling the number of DM-RS orthogonal ports without increasing DM-RS resource overhead. For Scheme 1, the time length of the cyclic shift in the time domain to adapt to the UE channel impulse response is halved. In MU-MIMO where there are multiple UEs experiencing large path propagation delays, the mutual interference caused by the channel impulse response between cyclic shifts may cause additional DM-RS channel estimation errors and may degrade the system MU-MIMO performance. For Scheme 2, the duration of the non-overlapping effective time window of each comb tooth is halved. For UEs experiencing large path propagation delays, the additional DM-RS channel estimation error may degrade system performance due to partial overlap and interference of impulse responses.

[0234] Example of Type 2 DM-RS Configuration

[0235] For the traditional type 2 DM-RS configuration, when one OFDM symbol is configured (such as Figure 4When two OFDM symbols are configured for the traditional type 2 DM-RS configuration, the time domain OCC with a length of 2 can also be used to generate orthogonal DM-RS ports, resulting in a total of 12 orthogonal ports (as shown in FIG. Figure 5 As shown in Figure 2.1, Type 2 configurations have the potential to provide high system throughput for massive MIMO that requires a large number of MU-MIMO data streams with the addition of more orthogonal ports. Through RRC configuration, only Type 2 DM-RS can be configured for CP-OFDM PDSCH and PUSCH configurations.

[0236] In some embodiments, to provide additional DM-RS ports in type 2 configuration, all 6 pairs of adjacent 2 REs in a resource block can be used to support different orthogonal ports. By using a frequency domain OCC of length 2 on each pair of adjacent REs, a single OFDM symbol configuration can support 12 orthogonal DM-RS ports. For dual OFDM symbol configurations, the same traditional time domain OCC of length 2, i.e., {[+1+1], [+1–1]}, can also be used to double the orthogonal DM-RS ports, resulting in a total of 24 orthogonal DM-RS ports in the frequency domain.

[0237] Fig.18 1800 is a schematic diagram of an exemplary configuration for doubling the DM-RS ports of a type 2 configuration for configuring one symbol. In this example, an additional 6 ports 12 to 17 are provided, resulting in a total of 12 ports. The resources of each port in the frequency domain are halved. This exemplary configuration also provides three new CDM groups indexed as 3, 4, and 5, which are not supported by the traditional type 2 configuration (including CDM groups 0, 1, and 2). In this example, it is determined that ports 12 and 13 belong to CDM group 3, ports 14 and 15 belong to CDM group 4, and ports 16 and 17 belong to CDM group 5.

[0238] Fig.19 1900 is a schematic diagram of an exemplary configuration for doubling the DM-RS ports of a type 2 configuration with two symbols. The resources of each port in the frequency domain are halved. This exemplary configuration provides an additional 12 ports 12 to 23, and three new CDM groups indexed as 3, 4 and 5, which are not supported by the traditional type 2 configuration (including CDM groups 0, 1, 2). In this example, it is determined that ports 12, 13, 18 and 19 belong to CDM group 3, ports 14, 15, 20 and 21 belong to CDM group 4, and ports 16, 17, 22 and 23 belong to CDM group 5.

[0239] Fig. 20 Shows Fig.18 and Fig.19 Example relative subcarrier positions of DM-RS ports in FIG. Fig. 20 include Fig.18 Table 2000 of relative subcarrier positions of DM-RS ports in the frequency domain. OCC patterns of length 2 are applied respectively in the frequency domain. Fig. 20 Also includes Fig.19 Table 2020 of the relative subcarrier positions of the DM-RS ports in. As shown, in addition to the two OCCs of length 2 applied in the frequency domain, the same traditional time domain OCC of length 2 is also applied in the time domain, {[+1+1], [+1–1]}.

[0240] In some embodiments, to map the DM-RS sequence to the resource elements of the additional DM-RS port, according to the modified equation in Section 7.4.1.1.2 of TS 38.211, the UE may assume such mapping according to the following equation:

[0241]

[0242] k=12n+2k′+ΔConfigurationtype2

[0243] k′=0,1

[0244]

[0245] n=0,1…

[0246] Among them, w t (l′) and time domain related parameters and l′ are defined in the same way, given by Table 7.4.1.1.2-1, Table 7.4.1.1.2-2, Table 7.4.1.1.2-3, Table 7.4.1.1.2-4 and Table 7.4.1.1.2-5 in the 5G NR TS 38.211 specification. r(n) is defined in Section 7.4.1.1.1 of the 5G NR TS 38.211 specification. w f (k') is given in Table 7.4.1.1.2-1 of TS 38.212. Table 6 below shows exemplary parameters for mapping. This table is obtained by modifying Table 7.4.1.1.2-1 in TS 38.211.

[0247] Table 6

[0248]

[0249]

[0250] Similarly, the design of port indexing, grouping, and signaling needs to consider backward compatibility with the traditional DM-RS port definition as much as possible. The design may also need to avoid completely redesigning the port indexing, grouping, and signaling. If the purpose of adding additional DR-MS ports in Rel.18 is only for MU-MIMO scenarios instead of SU-MIMO scenarios, the traditional DM-RS port indexing, grouping, and signaling can be reused as much as possible.

[0251] For SU-MIMO scenarios, the design of the traditional DM-RS ports can be reused. As described in Section 7.3.1.2 of [5, TS 38.212], the UE can use a small number of DM-RS ports for scheduling through antenna port indexing under DCI format 1_1.

[0252] TS 38.212 specifies that for DM-RS configuration type 2,

[0253] - if the UE is scheduled using one codeword and is assigned an antenna port mapping of {2, 10 or 23} in Table 7.3.1.2.2-3 and Table 7.3.1.2.2-4 of Section 7.3.1.2 with an index of [5, TS 38.212], or

[0254] - if the UE is scheduled using one codeword and is assigned an antenna port mapping with an index of {2, 10, 23 or 24} in Table 7.3.1.2.2-3A and {2, 10, 23 or 58} in Table 7.3.1.2.2-4A of section 7.3.1.2 of [5, TS 38.212], or

[0255] -If the UE uses two codewords for scheduling,

[0256] The UE may then assume that all remaining orthogonal antenna ports are not associated with PDSCH transmissions of other UEs.

[0257] For SU / MU-MIMO scenarios and DM-RS configuration type 2, the UE may be configured with three working modes for DM-RS port indication, as described below.

[0258] Mode 1: Traditional DM-RS CDM port

[0259] In this mode of operation, DCI messages are transmitted and interpreted in the same manner as described in Section 7.3.1.2.2 of TS 38.212 and Section 5.1.6.2 of TS 38.214. The definition of DM-RS ports follows the traditional DM-RS port definition. This mode may be used to better handle longer propagation path delays or for backward compatibility with legacy UEs.

[0260] Mode 2: Double the number of DM-RS CDM ports and double the number of CDM groups with no data

[0261] In this mode of operation, the number of DM-RS CDM ports is doubled and the frequency density of each DM-RS CDM port is halved. The number of DM-RS CDM groups without data is also doubled according to the number of DM-RS CDM groups without data scheduled. This mode can be used to multiplex more UE transmissions simultaneously.

[0262] Mode 3: Double the number of DM-RS CDM ports

[0263] In this mode of operation, the number of DM-RS CDM ports is doubled and the frequency density of each DM-RS CDM port is halved. The number of DM-RS CDM groups without data is not doubled and is the same as the number of scheduled DM-RS CDM groups without data. This mode can be used to provide high spectral efficiency and reduce UE DM-RS overlap in the frequency domain for different transmitters.

[0264] To indicate the additional DM-RS ports in modes 2 and 3, in some embodiments, a new bit may be defined outside of the traditional DCI message, or a bit in the traditional DCI message may be redefined. This bit is called the DM-RS port offset bit. In one embodiment, the bit may be designed as follows:

[0265] - If the DM-RS port offset bit is 0, no port offset is added;

[0266] - If the DM-RS port offset bit is 1, the port index of the corresponding entry in the corresponding lookup table (e.g., Table 7.3.1.2.2-3, Table 7.3.1.2.2-3A, Table 7.3.1.2.2-4, or Table 7.3.1.2.2-4A in TS 38.212) is increased by 12.

[0267] - Alternatively, a bit value of 1 for the DM-RS port offset bit indicates that no port offset is added, while a bit value of 0 for the DM-RS port offset bit indicates that 12 is added to the port index.

[0268] For DM-RS type 2, which doubles the number of ports, the maximum number of DM-RS CDM groups without data increases from 3 to 6. The indication of the number of DM-RS CDM groups without data also changes accordingly. Mode 2 and Mode 3 are used to handle this situation in different ways.

[0269] For Mode 2, the network schedules multiple UEs for simultaneous transmission. In one embodiment, the UE may determine the number of data-free CDM groups and DM-RS ports as described below, which is referred to as the Mode 2 method. The UE may derive the DM-RS port transmission information based on the antenna port bits and DM-RS port offset bits indicated in the received DCI signaling. The UE may search the lookup table and read the entry corresponding to the received antenna port bits. The UE may derive the number of data-free CDM groups by doubling the corresponding number of data-free CDM groups in the entry. The data-free additional DM-RS CDM group index may be obtained by adding 3 to the index in the entry.

[0270] For example, if the configuration of DM-RS is type 2 and the maximum length of OFDM symbol is 2, Table 7.3.1.2.2-4 in 38.212 (Table 7 below) can be used for table lookup. In this example, one codeword is enabled and the value of the antenna port bit is 45. From the entry corresponding to the value 45 in the lookup table (Table 7), the indicated DM-RS ports are 0, 1, 6, 7, and the number of DM-RS CDM groups without data is 3, that is, 3 DM-RS CDM groups with indices {0, 1, 2}. Then, the UE doubles the number of DM-RS CDM groups of 3 to obtain the number of new DM-RS CDM groups without data, that is, 6. The UE can add 3 to {0, 1, 2} to obtain the indices of 3 new DM-RS CDM groups without data, that is, {3, 4, 5}, and merge these indices with {0, 1, 2} to obtain the final indices of the DM-RS CDM groups without data, that is, {0, 1, 2, 3, 4, 5}. If the DM-RS Port Offset bit is 0, the UE expects DM-RS transmission on ports 0, 1, 6, 7. If the DM-RS Port Offset bit is 1, the UE adds 12 to {0, 1, 6, 7} and expects DM-RS transmission on ports 12, 13, 18, 19.

[0271] As another example, if the DM-RS is configured as type 2 and the maximum length of the OFDM symbol is 2, Table 7.3.1.2.2-4 (Table 7) in 38.212 can be used for table lookup. In this example, one codeword is enabled and the value of the antenna port bit is 7. From the entry corresponding to the value 7 in the lookup table, the indicated DM-RS ports are 0, 1, and the number of data-free DM-RS CDM groups is 2, i.e., two DM-RS CDM groups indexed {0, 1}. The UE should then double the number of 2 data-free DM-RS CDM groups to obtain the new number of data-free DM-RS CDM groups, i.e., 4. The UE can add 3 to {0, 1} (to obtain {3, 4}) and combine these indices with {0, 1} to obtain the final index of the data-free DM-RS CDM group {0, 1, 3, 4}. If the DM-RS port offset bit is 0, the UE expects DM-RS transmission on ports 0, 1. If the DM-RS port offset bit is 1, the UE adds 12 to {0, 1} and expects DM-RS transmission on ports 12, 13.

[0272] Table 7.3.1.2.2-4: Antenna port (1000 + DM-RS port), dmrs-Type = 2, maxLength = 2 Table 7

[0273]

[0274]

[0275]

[0276] In some embodiments, if the DM-RS port offset bit is 0, the UE can directly read the DM-RS port index and the number of DM-RS CDM groups without data from a new lookup table (e.g., Table 8 below) obtained by modifying Table 7.3.1.2.2-4. If the DM-RS port offset bit is 1, the UE can directly read the DM-RS port index and the number of DM-RS CDM groups without data from other new lookup tables (e.g., Table 9 below) obtained by modifying Table 7.3.1.2.2-4. Table 7.3.1.2.2-3, Table 7.3.1.2.2-3A, and Table 7.3.1.2.2-4A can be similarly modified.

[0277] Table 8

[0278]

[0279]

[0280]

[0281] Table 9

[0282]

[0283]

[0284]

[0285] For Mode 3, the network schedules multiple UEs for simultaneous transmission. In some embodiments, the UE may determine the number of data-free CDM groups and DM-RS ports as described below, which is referred to as a Mode 3 method. The UE may derive the DM-RS port transmission information based on the antenna port bits and DM-RS port offset bits indicated / included in the received DCI signaling. The UE may search the lookup table and read the entry corresponding to the received antenna port bits. If the DM-RS port offset bit is 0, the data-free DM-RS CDM group index is the same as the index of the entry. If the DM-RS port offset bit is 1, the data-free DM-RS CDM group index may be derived by adding 3 to the index in the entry.

[0286] For example, if the DM-RS is configured as type 2 and the maximum length of the OFDM symbol is 1, Table 7.3.1.2.2-3 in 38.212 (Table 10 below) can be used for table lookup. In this example, one codeword is enabled and the value of the antenna port bit is 8. From the entry corresponding to the value 8 in the lookup table, the indicated DM-RS ports are 2 and 3, and the number of DM-RS CDM groups without data is 2, that is, two DM-RS CDM groups indexed {0, 1}. If the DM-RS port offset bit is 0, the UE can directly derive the index of the DM-RS CDM group without data based on the indicated value {0, 1}, and expects DM-RS transmission on ports 2 and 3. If the DM-RS port offset bit is 1, the UE adds 3 to {0, 1} to obtain the final index of the DM-RS CDM group without data, that is, {3, 4}, and expects DM-RS transmission on ports 14 and 15 (that is, ports 2, 3 + 12 = ports 14, 15).

[0287] Table 7.3.1.2.2-3: Antenna port (1000+DMRS port), dmrs-Type=2, maxLength=1 Table 10

[0288]

[0289] In some embodiments, if the DM-RS port offset bit is 1, the UE can directly read the DM-RS port index and the number of DM-RS CDM groups without data from the new lookup table x (e.g., Table 11 below) obtained by modifying Table 7.3.1.2.2-3. Table 7.3.1.2.2-3A, Table 7.3.1.2.2-4, and Table 7.3.1.2.2-4A can be similarly modified.

[0290] Table 11

[0291]

[0292] In one embodiment, one of the three working modes can be specifically configured for each UE and activated through high-level RRC signaling. In another embodiment, one of the mode combinations (e.g., a combination of modes 1 and 2 or modes 1 and 3) can be configured for each UE through high-level RRC signaling, and one of the configured mode combinations can be activated through RRC signaling, MAC-CE or DCI.

[0293] In some embodiments, the network may dynamically instruct the UE to switch between two modes (i.e., modes 1 and 2, or modes 1 and 3) in the configured mode combination by defining a new bit outside the traditional DCI message or redefining the bit in the traditional DCI message. This bit may be referred to as a DM-RS working mode bit, as described above in conjunction with the type 1 configuration.

[0294] When this bit is configured for a mode combination of Mode 1 and Mode 2, the bit can be defined as follows:

[0295] -If the DM-RS operating mode bit is 1, the UE operates in mode 1;

[0296] - If the DM-RS operating mode bit is 0, the UE operates in mode 2;

[0297] -Alternatively, if the DM-RS operating mode bit is 0, the UE operates in mode 1; if the DM-RS operating mode bit is 1, the UE operates in mode 2.

[0298] When this bit is configured for the mode combination of Mode 1 and Mode 3, the bit can be defined as follows:

[0299] -If the DM-RS operating mode bit is 1, the UE operates in mode 1;

[0300] - If the DM-RS operating mode bit is 0, the UE operates in mode 3;

[0301] -Alternatively, if the DM-RS operating mode bit is 0, the UE operates in mode 1; if the DM-RS operating mode bit is 1, the UE operates in mode 3.

[0302] For example, assuming that the DM-RS is configured as type 2 and the maximum length of the OFDM symbol is 1, Table 7.3.1.2.2-3 in TS 38.212 (e.g., Table 10 above) can be used for table lookup. In this example, 4 UEs are scheduled for MU-MIMO transmission, and the network can indicate a mode to each UE. Each UE determines the DM-RS port based on the network's signaling:

[0303] - Indicates that UE1 operates in Mode 2 and indicates that UE1 has antenna port bit value 14 and DM-RS port offset bit value 0. According to the Mode 2 method, UE1 expects DM-RS transmission on port 3 and DM-RS CDM groups indexed {0, 1, 2, 3, 4, 5} with no data.

[0304] -Indicates that UE2 operates in Mode 2 and indicates that UE2 has antenna port bit value 14 and DM-RS port offset bit value 1. According to the Mode 2 method, UE2 expects DM-RS transmission on port 15 (port 3+12) and DM-RS CDM groups with indices {0, 1, 2, 3, 4, 5} with no data.

[0305] - Indicates that UE3 operates in Mode 2 and indicates that UE3 has antenna port bit value 15 and DM-RS port offset bit value 0. According to the Mode 2 method, UE3 expects DM-RS transmission on port 4 and DM-RS CDM groups with indices {0, 1, 2, 3, 4, 5} with no data.

[0306] - Indicates that UE4 operates in mode 1 and indicates that UE4 has an antenna port bit value of 17 and a DM-RS port offset bit value of 0.

[0307] UE4 expects DM-RS transmission on ports 0, 1 under the traditional DM-RS port definition and the DM-RS CDM group with index {0, 1, 2} without data.

[0308] Fig.21 FIG21 is a schematic diagram 2100 of exemplary DM-RS port allocation in the frequency domain for UE1 to UE4 in the above example.

[0309] Figures 15 to 17 The described exemplary method may also be applicable to mode configuration and activation of the three modes in a Type 2 configuration.

[0310] Fig. 222200 for DM-RS communication. The method 2200 may represent operations performed by a user equipment (UE). As shown, the UE may receive a configuration from a gNB, wherein the configuration is used to configure a first orthogonal cover code (OCC) length of 4 and a second OCC length of 2 for demodulation reference signal (DM-RS) communication between the gNB and the UE (step 2202). The UE may receive signaling from the gNB, wherein the signaling indicates that the UE uses a first OCC length or a second OCC length for DM-RS communication (step 2204). The UE may then transmit the DM-RS with the gNB according to the first OCC length or the second OCC length indicated by the signaling (step 2206).

[0311] Fig.23 2300 is a flowchart of another exemplary method 2300 for DM-RS communication. As shown, a communication device may send a first DM-RS via a first demodulation reference signal (DM-RS) port associated with an orthogonal cover code (OCC) of length 4 (step 2302); or a communication device may receive a second DM-RS via a second DM-RS port associated with an OCC of length 4 (step 2304). The communication device may be a UE or a network device, such as a gNB or an access point. The OCC may be [+1+1+1+1], [+1–1+1–1], [+1+j–1–j], or [+1–j–1+j].

[0312] Fig.24 is a flow chart of another exemplary method 2400 for DM-RS communication. The method 2400 may represent operations performed by a network device (e.g., a gNB). As shown, the gNB may send a configuration to a UE, wherein the configuration is used to configure a first orthogonal cover code (OCC) length of 4 and a second OCC length of 2 for demodulation reference signal (DM-RS) communication between the gNB and the UE (step 2402). The gNB may send signaling to the UE, wherein the signaling indicates that the UE communicates according to the first OCC length or the second OCC length (step 2404). The gNB may transmit a DM-RS with the UE according to the first OCC length or the second OCC length indicated by the signaling (step 2406).

[0313] The embodiments of the present disclosure may be implemented as computer-implemented methods. These embodiments may be executed by a processing system. Fig.25 A block diagram of an exemplary processing system 2500 for executing the methods described herein is shown, and the processing system 2500 can be installed in a host device. As shown in the figure, the processing system 2500 includes a processor 2504, a memory 2506, and interfaces 2510 to 2514, which may (or may not) be as described in the embodiment of the present invention. Fig.25 Arranged as shown. Processor 2504 can be any component or collection of components for performing calculations and / or other processing-related tasks, and memory 2506 can be any component or collection of components for storing programs and / or instructions for execution by processor 2504. In one embodiment, memory 2506 includes a non-transitory computer-readable medium. Interfaces 2510, 2512, and 2514 can be any component or collection of components that supports processing system 2500 to communicate with other devices / components and / or users. For example, one or more of interfaces 2510, 2512, and 2514 can be used to send data, control, or management messages from processor 2504 to applications installed on a host device and / or a remote device. For another example, one or more of interfaces 2510, 2512, and 2514 can be used to support users or user devices (e.g., personal computers (PCs), etc.) to interact / communicate with processing system 2500. Processing system 2500 may include Fig.25 Other components not shown, such as long term storage (eg, non-volatile memory, etc.).

[0314] In some embodiments, processing system 2500 is included in a network device that accesses a telecommunication network or otherwise becomes a part of a telecommunication network. In one example, processing system 2500 is in a network side device in a wireless or wired telecommunication network, such as a base station, a relay station, a scheduler, a controller, a gateway, a router, an application server, or any other device in a telecommunication network. In other embodiments, processing system 2500 is in a user side device that accesses a wireless or wired telecommunication network, such as a mobile station, a user equipment (UE), a personal computer (PC), a tablet computer, a wearable communication device (e.g., a smart watch, etc.), or any other device for accessing a telecommunication network. In some embodiments, one or more interfaces in interfaces 2510, 2512, and 2514 connect processing system 2500 to a transceiver for sending and receiving signaling through a telecommunication network.

[0315] Fig.26A block diagram of a transceiver 2600 for sending and receiving signaling through a telecommunications network is shown. The transceiver 2600 can be installed in a host device. As shown, the transceiver 2600 includes a network side interface 2602, a coupler 2604, a transmitter 2606, a receiver 2608, a signal processor 2610, and a device side interface 2612. The network side interface 2602 may include any component or component set for sending or receiving signaling through a wireless or wired telecommunications network. The coupler 2604 may include any component or component set for facilitating bidirectional communication through the network side interface 2602. The transmitter 2606 may include any component or component set (e.g., upconverter, power amplifier, etc.) for converting a baseband signal into a modulated carrier signal for transmission through the network side interface 2602. The receiver 2608 may include any component or component set (e.g., downconverter, low noise amplifier, etc.) for converting a carrier signal received through the network side interface 2602 into a baseband signal. The signal processor 2610 may include any component or set of components for converting baseband signals into data signals for communication through the device-side interface 2612 or converting data signals into baseband signals. The one or more device-side interfaces 2612 may include any component or set of components for transmitting data signals between the signal processor 2610 and components within a host device (e.g., the processing system 2500, a local area network (LAN) port, etc.).

[0316] The transceiver 2600 can send and receive signaling through any type of communication medium. In some embodiments, the transceiver 2600 sends and receives signaling through a wireless medium. For example, the transceiver 2600 can be a wireless transceiver for communicating according to a wireless telecommunication protocol such as a cellular protocol (e.g., long-term evolution (LTE), etc.), a wireless local area network (WLAN) protocol (e.g., Wi-Fi, etc.) or any other type of wireless protocol (e.g., Bluetooth, near field communication (NFC), etc.). In these embodiments, the network side interface 2602 includes one or more antenna / radiation units. For example, the network side interface 2602 may include a single antenna, multiple separate antennas, or a multi-antenna array for multi-layer communications such as single input multiple output (SIMO), multiple input single output (MISO), multiple input multiple output (MIMO), etc. In other embodiments, the transceiver 2600 sends and receives signaling through a wired medium such as a twisted pair cable, a coaxial cable, and an optical fiber. A particular processing system and / or transceiver may use all or only a subset of the components shown, and the level of integration may vary from device to device.

[0317] The following provides exemplary proposals described in the above embodiments:

[0318] Proposal 1: Support doubling the maximum number of orthogonal DM-RS ports for 1 and 2 OFDM symbol configurations and Type-1 and Type-2 DM-RS configurations.

[0319] Proposal 2: Consider doubling the time domain cyclic shift or frequency domain comb teeth to double the maximum number of orthogonal DM-RS ports in Type 1 configuration.

[0320] Proposal 3: Consider increasing the frequency domain size 2 RE pairs carrying different DM-RS ports from 3 to 6 to double the maximum number of orthogonal DM-RS ports in Type 2 configuration.

[0321] Proposal 4: Support UE to operate in legacy mode, i.e. DM-RS port configuration, indexing, mapping and indication.

[0322] Proposal 5: Support UE to operate in additional DM-RS port mode to improve system MU-MIMO performance.

[0323] Proposal 6: Support scheduling of MU-MIMO transmission for UEs operating in different modes (eg, legacy mode and additional DM-RS port mode).

[0324] Proposal 7: Based on the traditional design of DM-RS port combination, signaling indication, and message mapping, make as few necessary modifications as possible to the additional orthogonal DM-RS ports to reduce the standardization workload.

[0325] According to one aspect of the present disclosure, a method is provided. The method includes: a user equipment (UE) receives a downlink control information (DCI) message, wherein the DCI message includes an antenna port bit field and a demodulation reference signal (DM-RS) port offset bit; the UE obtains a first DM-RS port number from an antenna port table according to the antenna port bit field; when the DM-RS port offset bit is a first value, the UE determines a second DM-RS port number by adding the first DM-RS port number to a preconfigured number; and the UE transmits the DM-RS using the antenna port corresponding to the second DM-RS port number.

[0326] Optionally, in any of the above aspects, the method may further include: when the DM-RS port offset bit is a second value, the UE transmits the DM-RS using an antenna port corresponding to the first DM-RS port number.

[0327] Optionally, in any of the above aspects, the method may further include: the UE determining the number of DM-RS code division multiplexing (CDM) groups without data from the antenna port table according to the antenna port bit field.

[0328] Optionally, in any of the above aspects, the preconfigured number is 8.

[0329] Optionally, in any of the above aspects, the method may also include: the UE obtains a first number of data-free DM-RS code division multiplexing (CDM) groups from the antenna port table according to the antenna port bit field; the UE determines a second number of data-free DM-RS CDM groups, wherein the second number is twice the first number of the data-free DM-RS CDM groups; and the UE communicates according to the second number of the data-free DM-RS CDM groups.

[0330] Optionally, in any of the above aspects, the method may also include: the UE determines a first group of CDM group indices corresponding to the first number of the data-free DM-RS CDM groups respectively; the UE determines a second group of CDM group indices by adding an offset to the first group of CDM group indices; the UE merges the first group of CDM group indices with the second group of CDM group indices to obtain a third group of CDM group indices, wherein the third group of CDM group indices correspond to the second number of the data-free DM-RS CDM groups respectively.

[0331] Optionally, in any of the above aspects, the method may also include: the UE obtains a first number of data-free DM-RS code division multiplexing (CDM) groups from the antenna port table according to the antenna port bit field; when the DM-RS port offset bit is the first value, the UE obtains a first group of CDM group indexes from the antenna table according to the antenna port bit field; the UE determines a second group of CDM group indexes by adding the offset to the first group of CDM group indexes, wherein the second group of CDM group indexes correspond to the first number of data-free DM-RS CDM groups respectively.

[0332] Optionally, in any of the above aspects, the offset is 2.

[0333] The present disclosure also provides a device for implementing any of the methods in the above aspects.

[0334] Advantages of the disclosed embodiments include: increasing the number of orthogonal DM-RS ports while maintaining relatively low DM-RS overhead. These embodiments achieve good demodulation performance and can support a large number of data layers for large-scale SU / MU-MIMO transmission.

[0335] It should be understood that one or more steps of the exemplary methods provided herein can be performed by corresponding units or modules. For example, a signal can be sent by a sending unit or a sending module. A signal can be received by a receiving unit or a receiving module. A signal can be processed by a processing unit or a processing module. Other steps can be performed by a configuration unit / module, an activation unit / module, a table search or table lookup unit / module, a determination unit / module, a signaling unit / module and / or an indication unit / module. The corresponding unit / module can be hardware, software or a combination thereof. For example, one or more units / modules can be integrated circuits, such as field programmable gate arrays (FPGA) or application-specific integrated circuits (ASIC).

[0336] Although the present disclosure has been described with reference to illustrative embodiments, this specification is not to be interpreted in a limiting sense. With reference to this article, those skilled in the art will clearly understand various modifications and combinations of the illustrative embodiments and other embodiments of the present disclosure. Therefore, the appended claims cover any such modifications or embodiments.

[0337] Provided below are abbreviations that may be used in this disclosure.

[0338]

[0339]

[0340]

Claims

1. A method, characterized in that include: The user equipment UE receives a configuration from the gNB, wherein the configuration is used to configure a first orthogonal cover code OCC length and a second OCC length for demodulation reference signal DM-RS communication between the gNB and the UE, the first OCC length is 4, and the second OCC length is 2; The UE receives signaling, wherein the signaling instructs the UE to transmit a DM-RS according to the first OCC length or the second OCC length; The UE transmits DM-RS with the gNB according to the first OCC length or the second OCC length indicated by the signaling.

2. The method according to claim 1, characterized in that The receiving configuration includes: The UE receives the configuration in radio resource control RRC signaling.

3. The method according to claim 1 or 2, characterized in that: The signaling is RRC signaling.

4. The method according to claim 1 or 2, characterized in that: The signaling is carried in a medium access control MAC control element CE.

5. The method according to claim 1 or 2, characterized in that: The signaling is carried in a downlink control information DCI message.

6. The method according to any one of claims 1 to 5, characterized in that Also includes: The UE sends a message to the gNB confirming receipt of the configuration.

7. The method according to any one of claims 1 to 6, characterized in that The transmission DM-RS includes: When the signaling indicates the first OCC length, the UE receives or sends the DM-RS through the DM-RS port associated with the OCC of the first OCC length, or when the signaling indicates the second OCC length, the UE receives or sends the DM-RS through the DM-RS port associated with the OCC of the second OCC length.

8. The method according to claim 7, characterized in that Also includes: The UE receives a physical downlink shared channel PDSCH through a DM-RS port associated with the OCC of the first OCC length, or through a DM-RS port associated with the OCC of the second OCC length; or, The UE sends a physical uplink shared channel PUSCH through a DM-RS port associated with the OCC of the first OCC length, or through a DM-RS port associated with the OCC of the second OCC length.

9. The method according to any one of claims 1 to 8, characterized in that The OCC of the first OCC length includes: [+1+1+1+1], [+1–1+1–1], [+1+j–1–j], or [+1–j–1+j].

10. The method according to any one of claims 1 to 9, characterized in that Also includes: The UE receives a DCI message including an indication; The UE receives a DM-RS port offset bit, wherein a combination of the indication and the DM-RS port offset bit indicates information of a DM-RS port to be used by the UE.

11. The method according to claim 10, characterized in that Also includes: When the signaling indicates the first OCC length and the DM-RS port offset bit has a first value, the UE determines, according to a first corresponding relationship associated with the second OCC length, that the DM-RS port to be used has a first port number, and the first port number corresponds to the indication; or, When the signaling indicates the first OCC length and the DM-RS port offset bit has a second value, the UE determines that the DM-RS port to be used has a second port number, and the second port is obtained by adding a non-zero integer to the first port number respectively.

12. The method according to claim 11, characterized in that The non-zero integer is 8 or 12.

13. The method according to claim 10, characterized in that Also includes: When the signaling indicates the first OCC length and the DM-RS port offset bit has a first value, the UE determines the port number of the DM-RS port to be used according to a first corresponding relationship between the port number and the indication, wherein the first corresponding relationship is associated with the second OCC length; or When the signaling indicates the first OCC length and the DM-RS port offset bit has a second value, the UE determines the port number of the DM-RS port to be used based on a second correspondence between the port number and the indication, wherein the second correspondence is associated with the first OCC length.

14. The method according to claim 10, characterized in that The DM-RS port offset bit is included in the DCI message.

15. The method according to claim 10, characterized in that The DCI message is a traditional DCI message.

16. The method according to any one of claims 1 to 15, characterized in that When one symbol is configured for type 1 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 8, When 2 symbols are configured for type 1 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 16, When a symbol is configured for type 2 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 12, or When two symbols are configured for type 2 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 24.

17. The method according to any one of claims 1 to 16, characterized in that The DM-RS communication includes type 1 DM-RS transmission or type 2 DM-RS transmission.

18. A method, characterized in that include: The communication device sends a first DM-RS through a first demodulation reference signal DM-RS port associated with an orthogonal cover code OCC of length 4; or The communication device receives a second DM-RS through a second DM-RS port associated with an OCC of length 2.

19. The method according to claim 18, characterized in that The communication device is a user equipment UE or a gNB.

20. The method according to claim 18 or 19, characterized in that The OCC includes: [+1+1+1+1], [+1–1+1–1], [+1+j–1–j], or [+1–j–1+j].

21. The method according to any one of claims 18 to 20, characterized in that Also includes: The communication device receives a DCI message including an indication, wherein the communication device is a user equipment UE; The UE receives a DM-RS port offset bit, wherein a combination of the indication and the DM-RS port offset bit indicates information of the DM-RS port.

22. The method according to claim 21, characterized in that Also includes: When the DM-RS port offset bit has a first value, the UE determines, according to a first corresponding relationship associated with an OCC of length 2, that the DM-RS port has a first port number, the first port number corresponding to the indication; or When the DM-RS port offset bit has a second value, the UE determines that the DM-RS port has a second port number, where the second port number is obtained by adding a non-zero integer to the first port number, respectively.

23. The method according to claim 22, characterized in that The non-zero integer is 8 or 12.

24. The method according to claim 21, characterized in that Also includes: When the DM-RS port offset bit has a first value, the UE determines the DM-RS port according to a first correspondence between a port number and the indication, wherein the first correspondence is associated with an OCC of length 2; or When the DM-RS port offset bit has a second value, the UE determines the DM-RS port according to a second corresponding relationship between the port number and the indication, wherein the second corresponding relationship is associated with the OCC with a length of 4.

25. The method according to claim 18 or 20, characterized in that Also includes: The communications device sends a DCI message including an indication, wherein the communications device is a gNB; The gNB sends a DM-RS port offset bit, wherein a combination of the indication and the DM-RS port offset bit indicates the DM-RS port.

26. The method according to claim 21 or 25, characterized in that The DM-RS port offset bit is included in the DCI message.

27. The method according to claim 21 or 25, characterized in that The DCI message is a traditional DCI message.

28. The method according to any one of claims 18 to 27, characterized in that When one symbol is configured for type 1 DM-RS transmission, the number of DM-RS ports associated with the OCC of length 4 is 8, When two symbols are configured for type 1 DM-RS transmission, the number of DM-RS ports associated with the OCC of length 4 is 16, When one symbol is configured for type 2 DM-RS transmission, the number of DM-RS ports associated with the OCC of length 4 is 12, When two symbols are configured for type-2 DM-RS transmission, the number of DM-RS ports associated with the OCC of length 4 is 24.

29. The method according to any one of claims 18 to 28, characterized in that The first DM-RS or the second DM-RS includes a type 1 DM-RS or a type 2 DM-RS.

30. A method, characterized in that include: The gNB sends a configuration to the user equipment UE, wherein the configuration is used to configure a first orthogonal cover code OCC length and a second OCC length for demodulation reference signal DM-RS communication between the gNB and the UE, the first OCC length is 4, and the second OCC length is 2; The gNB sends signaling, wherein the signaling instructs the UE to transmit a DM-RS according to the first OCC length or the second OCC length; The gNB transmits DM-RS to the UE according to the first OCC length or the second OCC length indicated by the signaling.

31. The method according to claim 30, characterized in that The sending configuration includes: The gNB sends the configuration in radio resource control RRC signaling.

32. The method according to claim 30 or 31, characterized in that The signaling is RRC signaling.

33. The method according to claim 30 or 31, characterized in that The signaling is carried in a medium access control MAC control element CE.

34. The method according to claim 30 or 31, characterized in that The signaling is carried in a downlink control information DCI message.

35. The method according to any one of claims 30 to 34, characterized in that Also includes: The gNB receives a message from the UE confirming receipt of the configuration.

36. The method according to any one of claims 30 to 35, characterized in that The transmission DM-RS includes: When the signaling indicates the first OCC length, the gNB receives or sends the DM-RS through the DM-RS port associated with the OCC of the first OCC length, or when the signaling indicates the second OCC length, the gNB receives or sends the DM-RS through the DM-RS port associated with the OCC of the second OCC length.

37. The method according to claim 36, characterized in that Also includes: The gNB sends a physical downlink shared channel PDSCH through a DM-RS port associated with the OCC of the first OCC length, or through a DM-RS port associated with the OCC of the second OCC length; or, The gNB receives a physical uplink shared channel PUSCH through a DM-RS port associated with the OCC of the first OCC length, or through a DM-RS port associated with the OCC of the second OCC length.

38. The method according to any one of claims 30 to 37, characterized in that The OCC of the first OCC length includes: [+1+1+1+1], [+1–1+1–1], [+1+j–1–j], or [+1–j–1+j].

39. The method according to any one of claims 30 to 38, characterized in that Also includes: The gNB sends a DCI message including an indication; The gNB sends a DM-RS port offset bit, wherein a combination of the indication and the DM-RS port offset bit indicates a DM-RS port to be used.

40. The method according to claim 39, characterized in that When the signaling indicates the first OCC length and the DM-RS port offset bit has a first value, according to a first corresponding relationship associated with the second OCC length, the DM-RS port to be used has a first port number, and the first port number corresponds to the indication; or When the signaling indicates the first OCC length and the DM-RS port offset bit has a second value, the DM-RS port to be used has a second port number, which is obtained by adding a non-zero integer to the first port number respectively.

41. The method according to claim 40, characterized in that The non-zero integer is 8 or 12.

42. The method according to claim 39, characterized in that When the signaling indicates the first OCC length and the DM-RS port offset bit has a first value, the DM-RS port has the port number according to a first correspondence between the port number and the indication, wherein the first correspondence is associated with the second OCC length; or When the signaling indicates the first OCC length and the DM-RS port offset bit has a second value, the DM-RS port to be used has the port number according to a second correspondence between the port number and the indication, wherein the second correspondence is associated with the first OCC length.

43. The method according to claim 39, characterized in that The DM-RS port offset bit is included in the DCI message.

44. The method according to claim 39, characterized in that The DCI message is a traditional DCI message.

45. The method according to any one of claims 30 to 34, characterized in that When one symbol is configured for type 1 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 8, When 2 symbols are configured for type 1 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 16, When a symbol is configured for type 2 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 12, or When two symbols are configured for type 2 DM-RS transmission, the number of DM-RS ports associated with the first OCC length of 4 is 24.

46. ​​The method according to any one of claims 30 to 45, characterized in that The DM-RS communication includes type 1 DM-RS transmission or type 2 DM-RS transmission.

47. A device, characterized in that include: non-transitory memory, including instructions; One or more processors in communication with the memory, wherein the instructions, when executed by the one or more processors, cause the apparatus to perform the method according to any one of claims 1 to 46.

48. A non-transitory computer readable medium storing computer instructions, characterized in that: The computer instructions, when executed by one or more processors, cause the one or more processors to perform the method according to any one of claims 1 to 46.

49. A system, characterized in that: include: gNB; A user equipment UE communicating with the gNB, wherein: The UE is used to perform the following operations: Receive a configuration from a gNB, wherein the configuration is used to configure a first orthogonal cover code OCC length and a second OCC length for demodulation reference signal DM-RS communication between the gNB and the UE, the first OCC length is 4, and the second OCC length is 2; receiving signaling, wherein the signaling instructs the UE to transmit a DM-RS according to the first OCC length or the second OCC length; Transmitting a DM-RS with the gNB according to the first OCC length or the second OCC length indicated by the signaling; The gNB is used to perform the following operations: Sending the configuration to the UE; Sending the signaling to the UE; The DM-RS is transmitted to the UE.

50. A device, characterized in that: include: A receiving module, configured to: receive a configuration from a gNB, wherein the configuration is used to configure a first orthogonal cover code OCC length and a second OCC length for demodulation reference signal DM-RS communication between the gNB and the UE, the first OCC length is 4, and the second OCC length is 2, and receive signaling, wherein the signaling instructs the UE to transmit the DM-RS according to the first OCC length or the second OCC length; A communication module is used to transmit DM-RS with the gNB according to the first OCC length or the second OCC length indicated by the signaling.

51. A device, characterized in that include: A sending module, configured to send a first DM-RS through a first demodulation reference signal DM-RS port associated with an orthogonal cover code OCC of length 4; or, The receiving module is configured to receive a second DM-RS through a second DM-RS port associated with an OCC with a length of 4.

52. A device, characterized in that include: A sending module, configured to: send a configuration to a user equipment UE, wherein the configuration is used to configure a first orthogonal cover code OCC length and a second OCC length for demodulation reference signal DM-RS communication between the gNB and the UE, the first OCC length is 4, and the second OCC length is 2; send signaling, wherein the signaling instructs the UE to transmit the DM-RS according to the first OCC length or the second OCC length; A communication module is used to transmit a DM-RS with the UE according to the first OCC length or the second OCC length indicated by the signaling.

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