EP4681399A1

EP4681399A1 - Method of generating a comb reference signal pattern over discrete-fourier-transform-spread orthogonal frequency division multiplexing symbol and related user equipment

Info

Publication number: EP4681399A1
Application number: EP24792033.3A
Authority: EP
Inventors: Rui Zhang; Shiauhe Shawn TSAI; Tzu-Han Chou
Original assignee: MediaTek Inc
Current assignee: MediaTek Inc
Priority date: 2023-04-21
Filing date: 2024-04-17
Publication date: 2026-01-21
Also published as: WO2024217448A1; CN121040016A

Abstract

A method of generating a comb reference signal (RS) pattern over a discrete-Fourier-transform-spread orthogonal frequency division multiplexing (DFT-s-OFDM) symbol includes repeating a time-domain sequence with a number of repetition to obtain a repeated time sequence; performing a phase rotation for the repeated time sequence to obtain a phase-rotated time sequence; concatenating a plurality of phase-rotated time sequences; and performing a DFT-s-OFDM operation for the plurality of phase-rotated time sequences.

Description

METHOD OF GENERATING A COMB REFERENCE SIGNAL PATTERN OVER DISCRETE-FOURIER-TRANSFORM-SPREAD ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SYMBOL AND RELATED USER EQUIPMENT

CROSS REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. Provisional Application No. 63/497,476, filed on April 21st, 2023. The content of the application is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a method of generating a comb reference signal pattern over a discrete-Fourier-transform-spread orthogonal frequency division multiplexing (DFT-s-OFDM) symbol and related user equipment, and more particularly, to a method of generating a comb RS pattern over a DFT-s-OFDM symbol and related user equipment capable of adapting reference signal patterns for ambiguity performances.

BACKGROUND

The reference signal configuration is vital in conventional sensing performance when the orthogonal frequency domain multiplexing (OFDM) is applied to joint communication and sensing, especially for bi-static sensing. However, depending on the reference signal patterns, a method of utilizing staggered comb-based reference signal patterns based on Cyclic Prefix-Orthogonal Frequency Division Multiplexing (CP-OFDM) for multiple-target sensing using super-resolution sensing algorithms is absent.

SUMMARY

In light of this, the present invention provides a method of generating a comb reference signal pattern over a discrete-Fourier-transform-spread orthogonal frequency division multiplexing symbol and related user equipment to enable a staggered comb structure in the frequency domain.
An embodiment of the present invention provides a method of generating a comb reference signal (RS) pattern over a discrete-Fourier-transform-spread orthogonal frequency division multiplexing (DFT-s-OFDM) symbol, which comprises repeating a time-domain sequence with a number of repetition to obtain a repeated time sequence; performing a phase rotation for the repeated time sequence to obtain a phase-rotated time sequence; concatenating a plurality of phase-rotated time sequences; and performing a DFT-s-OFDM operation for the plurality of phase-rotated time sequences.
Another embodiment of the present invention provides a user equipment (UE) of an orthogonal frequency domain multiplexing (OFDM) communication system, which comprises a wireless transceiver, configured to perform wireless transmission and reception to and from a service terminal; and a controller, configured to repeat a time-domain sequence with a number of repetition to obtain a repeated time sequence; perform a phase rotation for the repeated time sequence to obtain a phase-rotated time sequence; concatenate a plurality of phase-rotated time sequences; and perform a DFT-s-OFDM operation for the plurality of phase-rotated time sequences.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a wireless communication network according to an embodiment of the present invention.
FIGs. 2a, 2b are schematic diagrams of a comb-2 structure of a reference signal (RS) pattern according to an embodiment of the present invention.
FIG. 3 is a schematic diagram of a comb-4 structure of a RS pattern according to an embodiment of the present invention.
FIG. 4 is a schematic diagram of a method of generating the comb RS pattern over the DFT-s-OFDM symbol.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is a schematic diagram of a wireless communication network 100 according to an embodiment of the present invention.
As shown in FIG. 1, the wireless communication network 100 may include a user equipment (UE) 110 and a service network 120, wherein the UE 110 may be wirelessly connected to the service network 120 for obtaining mobile services and performing cell measurements to the cell (s) of the service network 120.
The UE 110 may be a feature phone, a smartphone, a panel Personal Computer (PC) , a laptop computer, a moving vehicle or any wireless communication device supporting the wireless technology (e.g., the 5G NR technology) utilized by the service network 120. In another embodiment, the UE 110 may support more than one wireless technology. For example, the UE may support the 5G NR technology and a legacy 4G technology, such as the LTE/LTE-A/TD-LTE technology.
The service network 120 includes an access network 121 and a core network 122. The access network 121 is responsible for processing radio signals, terminating radio protocols, and connecting the UE 110 with the core network 122. The core network 122 is responsible for performing mobility management, network-side authentication, and interfaces with public/external networks (e.g., the Internet) . Each of the access network 121 and the core network 122 may comprise one or more network nodes for carrying out said functions.
In one embodiment, the service network 120 may be a 5G NR network, and the access network 121 may be a Radio Access Network (RAN) and the core network 122 may be a Next Generation Core Network (NG-CN) .
A RAN may include one or more cellular stations, such as next generation NodeBs (gNBs) , which support high frequency bands (e.g., above 24 GHz) , and each gNB may further include one or more Transmission Reception Points (TRPs) , wherein each gNB or TRP may be referred to as a 5G cellular station. Some gNB functions may be distributed across different TRPs, while others may be centralized, leaving the flexibility and scope of specific deployments to fulfill the requirements for specific cases.
A 5G cellular station may form one or more cells with different Component Carriers (CCs) for providing mobile services to the UE 110. For example, the UE 110 may camp on one or more cells formed by one or more gNBs or TRPs, wherein the cells which the UE 110 is camped on may be referred to as serving cells, including a Primary cell (Pcell) and one or more Secondary cells (Scells) .
An NG-CN generally consists of various network functions, including Access and Mobility Function (AMF) , Session Management Function (SMF) , Policy Control Function (PCF) , Application Function (AF) , Authentication Server Function (AUSF) , User Plane Function (UPF) , and User Data Management (UDM) , wherein each network function may be implemented as a network element on a dedicated hardware, or as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., a cloud infrastructure.
The AMF provides UE-based authentication, authorization, mobility management, etc. The SMF is responsible for session management and allocates Internet Protocol (IP) addresses to UEs. It also selects and controls the UPF for data transfer. If a UE has multiple sessions, different SMFs may be allocated to each session to manage them individually and possibly provide different functions per session. The AF provides information on the packet flow to PCF responsible for policy control in order to support Quality of Service (QoS) . Based on the information, the PCF determines policies about mobility and session management to make the AMF and the SMF operate properly. The AUSF stores data for authentication of UEs, while the UDM stores subscription data of UEs.
In another embodiment, the service network 120 may be an LTE/LTE-A/TD-LTE network, and the access network 121 may be an Evolved-Universal Terrestrial Radio Access Network (E-UTRAN) and the core network 122 may be an Evolved Packet Core (EPC) .
An E-UTRAN may include at least one cellular station, such as an evolved NodeB (eNB) (e.g., macro eNB, femto eNB, or pico eNB) , each of which may form a cell for providing mobile services to the UE 110. For example, the UE 110 may camp on one or more cells formed by one or more eNBs, wherein the cells which the UE 110 is camped on may be referred to as serving cells, including a Pcell and one or more Scells.
An EPC may include a Home Subscriber Server (HSS) , Mobility Management Entity (MME) , Serving Gateway (S-GW) , and Packet Data Network Gateway (PDN-GW or P-GW) .
It should be understood that the wireless communication network 100 described in the embodiment of FIG. 1 is for illustrative purposes and is not intended to limit the scope of the application. For example, the wireless communication network 100 may include both a 5G NR network and a legacy network (e.g., an LTE/LTE-A/TD-LTE network, or a WCDMA network) , and the UE 110 may be wirelessly connected to both the 5G NR network and the legacy network.
An embodiment of the present invention enables a staggered comb structure in a frequency domain and applies the derived principles to either new 6G joint communication sensing, or existing 5G NR, reference signal (RS) patterns.
Please refer to FIGs. 2 (a) , 2 (b) , which are schematic diagrams of a comb-2 structure of a reference signal (RS) pattern according to an embodiment of the present invention. FIGs. 2 (a) , 2(b) illustrate a staggered comb-2 RS pattern in a time domain for discrete-Fourier-transform-spread orthogonal frequency division multiplexing (DFT-s-OFDM) .
Y₁ is a time sequence with a length ofand Y is the RS time sequence with a length of L. Without loss of generality, Y is a concatenation of sequences Y₁ and Y₂, which is expressed as Y= {Y₁, Y₂} ..
When Y₂=Y₁, the RS pattern in the frequency domain (DFT of Y) is the comb-2 structure with zero staggering offset as illustrated in FIG. 2 (a) . When Y₂=-Y₁, the RS pattern in the frequency domain (DFT of Y) is the comb-2 structure with staggering offset equal to one as illustrated in FIG. 2 (b) .
Please refer to FIG. 3, which is a schematic diagram of a comb-4 structure of an RS pattern according to an embodiment of the present invention. As shown in FIG. 3, N (unit in subcarrier numbers) is the regular spacing, which is called as a comb density or a comb size, of the RS resource elements (RE) in a frequency domain, and N≥2 for a non-trivial comb structure, (unit in subcarrier numbers) is a staggering offset RS REs in the frequency domain of each DFT-s-OFDM symbol, L is a total length of the RS time sequence, Y is the RS time sequence, and L·N is a DFT-s-OFDM FFT size.
To generate the RS comb pattern with the comb size/density equal to N and the staggering offset equal to F, the RS time sequence Y is generated through the concatenation of N sub-sequencesas Y= {Y₁, Y₂, …Y_N} . Also, for any Y_h, 1<h≤N,
In other words, the repeated time sequence, i.e., N sub-sequencescan be designed as a constant envelope in a frequency domain .
Moreover, Y₁ is designed to let DFT of Y to show low peak-to-average power ratio (PAPR) properties in the time domain and/or the frequency domain, such that the sensing algorithms in the frequency domain are facilitated.
Please refer to FIG. 4, which is a schematic diagram of a method 40 of generating the comb RS pattern over the DFT-s-OFDM symbol. The method 40 includes the following steps:
Step 402: Start;
Step 404: Repeat a time-domain sequence with a number of repetition to obtain a repeated time sequence;
Step 406: Perform a phase rotation for the repeated time sequence to obtain a phase-rotated time sequence;
Step 408: Concatenate a plurality of phase-rotated time sequences;
Step 410: Perform a DFT-s-OFDM operation for the plurality of phase-rotated time sequences;
Step 412: End.
Further details about the method 40 can be known by referring to the embodiments of the comb-2 structure of the RS pattern above, and are therefore not narrated here for brevity.
Notably, those skilled in the art may properly design the comb RS pattern according to different system requirements, and not limited thereto.
In summary, the present invention provides a method of generating a comb reference signal pattern over a DFT-s-OFDM and related user equipment, which enables a staggered comb structure in the frequency domain and applies the derived principles to either new 6G joint communication sensing, or existing 5G NR, reference signal (RS) patterns.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

Claims

Amethod of generating a comb reference signal (RS) pattern over a discrete-Fourier-transform-spread orthogonal frequency division multiplexing (DFT-s-OFDM) symbol, comprising:

repeating a time-domain sequence with a number of repetition to obtain a repeated time sequence;

performing a phase rotation for the repeated time sequence to obtain a phase-rotated time sequence;

concatenating a plurality of phase-rotated time sequences; and

performing a DFT-s-OFDM operation for the plurality of phase-rotated time sequences.
The method of generating a comb RS pattern over a DFT-s-OFDM symbol of claim 1, wherein the number of repetitions is a comb size of the comb RS pattern.
The method of generating a comb RS pattern over a DFT-s-OFDM symbol of claim 1, wherein the repeated time sequence is of a low peak-to-average power ratio (PAPR) in a time domain and/or a frequency domain.
The method of generating a comb RS pattern over a DFT-s-OFDM symbol of claim 1, wherein the repeated time sequence is of a constant envelope in a frequency domain.
A user equipment (UE) of an orthogonal frequency domain multiplexing (OFDM) communication system, comprising:

a wireless transceiver, configured to perform wireless transmission and reception to and from a service terminal; and

a controller, configured to repeat a time-domain sequence with a number of repetition to obtain a repeated time sequence; perform a phase rotation for the repeated time sequence to obtain a phase-rotated time sequence; concatenate a plurality of phase-rotated time sequences; and perform a DFT-s-OFDM operation for the plurality of phase-rotated time sequences.
The UE of an OFDM communication system of claim 5, wherein the number of repetition is a comb size of the comb RS pattern.
The UE of an OFDM communication system of claim 5, wherein the repeated time sequence is of a low peak-to-average power ratio (PAPR) in a time domain and/or a frequency domain.
The UE of an OFDM communication system of claim 5, wherein the repeated time sequence is of a constant envelope in a frequency domain.