Method, device and system for reference signal configuration in wireless communication

Abstract

A method, apparatus, and system for reference signal configuration in wireless communication are disclosed. In one embodiment, a method performed by a wireless communication device is disclosed. The method includes: generating a pilot signal occupying N symbol resources, wherein the pilot signal includes at least one sparsest reference signal (RS) port, which is determined from a predetermined sparsest RS port pool, wherein the predetermined pool includes at least N sparsest RS ports, wherein N is an integer greater than 1; and transmitting a signal including the pilot signal to a wireless communication node.

Description

Technical Field

[0001] The present disclosure relates generally to wireless communications, and more particularly, to methods, apparatuses, and systems for reference signal configuration in wireless communications. Background Art

[0002] In wireless networks, such as fifth generation (5G) new radio (NR) systems, Internet of Things (IoT) systems, or machine type communications (MTC), many terminals want to access the network side for ultra-low power consumption service transmission or ultra-low signaling overhead service transmission or ultra-reliable low latency service transmission. Therefore, unlicensed access or unlicensed transmission is proposed, in which no authorization or scheduling is required from the base station before the terminal transmits data to the base station or another receiver. Therefore, no associated interaction process is required between the terminal and the base station, which can avoid the overhead caused by these interaction processes. There are two types of unlicensed transmission: unlicensed (configured authorization) transmission based on semi-persistent scheduling and contention-based unlicensed transmission. In these two types of unlicensed transmission, there is no need to dynamically schedule the base station before the terminal transmits data.

[0003] Both types of unlicensed data transmission are based on reference signals. When using traditional reference signals (RS) in unlicensed access or unlicensed transmission scenarios, the same reference signal is used not only for active user identification but also for channel estimation, including estimation of the radio channel and time / frequency offset, which requires the reference signal to be propagated throughout the transmission bandwidth and time period. This requires a significant responsibility for the reference signal. As a result, each reference signal occupies a large amount of resources. Therefore, given a certain resource overhead, the number of reference signals is very limited, and it is difficult to support high-load unlicensed access with existing reference signal configurations.

[0004] Therefore, existing systems and methods for reference signal configuration in wireless communications are not entirely satisfactory. Summary of the invention

[0005] The exemplary embodiments disclosed herein are intended to solve problems associated with one or more difficulties presented in the prior art, as well as to provide additional features that will become apparent by reference to the following detailed description when taken in conjunction with the accompanying drawings. According to various embodiments, exemplary systems, methods, devices, and computer program products are disclosed herein. However, it should be understood that these embodiments are presented by way of example and not limitation, and it will be apparent to a person of ordinary skill in the art who reads this disclosure that various modifications may be made to the disclosed embodiments while remaining within the scope of this disclosure.

[0006] In one embodiment, a method performed by a wireless communication device is disclosed. The method includes: generating a pilot signal occupying N symbol resources, wherein the pilot signal includes at least one reference signal (RS) port determined from a predetermined RS port pool, wherein the predetermined pool includes at least N RS ports, wherein N is an integer greater than 1; and transmitting a signal including the pilot signal to a wireless communication node.

[0007] In another embodiment, a method performed by a wireless communication device is disclosed. The method includes: generating a pilot signal, the pilot signal including at least one reference signal (RS) port determined from a predetermined RS port pool, wherein each RS port in the predetermined pool has at most two non-zero elements; and transmitting a signal including the pilot signal to a wireless communication node.

[0008] In another embodiment, a method performed by a wireless communication device is disclosed. The method includes: generating a pilot signal occupying N symbol resources, wherein the pilot signal includes at least one reference signal (RS) port determined from a predetermined RS port pool, wherein each RS port in the predetermined pool has Nz non-zero elements, wherein N is an integer greater than 24, and wherein Nz is an integer greater than 0 and less than 9; and transmitting a signal including the pilot signal to a wireless communication node.

[0009] In another embodiment, a method performed by a wireless communication node is disclosed. The method includes: receiving a signal including a pilot signal from a wireless communication device. The pilot signal occupies N symbol resources. The pilot signal includes at least one reference signal (RS) port determined from a predetermined RS port pool. The predetermined pool includes at least N RS ports. N is an integer greater than 1.

[0010] In another embodiment, a method performed by a wireless communication node is disclosed. The method includes: receiving a signal including a pilot signal from a wireless communication device. The pilot signal includes at least one reference signal (RS) port determined from a predetermined RS port pool. Each RS port in the predetermined pool has at most two non-zero elements.

[0011] In yet another embodiment, a method performed by a wireless communication node is disclosed. The method includes: receiving a signal including a pilot signal from a wireless communication device. The pilot signal occupies N symbol resources. The pilot signal includes at least one reference signal (RS) port determined from a predetermined RS port pool. Each RS port in the predetermined pool has Nz non-zero elements. N is an integer greater than 24. Nz is an integer greater than 0 and less than 9.

[0012] In another embodiment, a wireless communication node configured to perform a method disclosed in an embodiment is disclosed. In yet another embodiment, a wireless communication device configured to perform a method disclosed in an embodiment is disclosed. In another embodiment, a non-transitory computer-readable medium having computer-executable instructions stored thereon for performing a method disclosed in an embodiment is disclosed. The above aspects and other aspects and their implementations are described in more detail in the drawings, the description, and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Various exemplary embodiments of the present disclosure are described in detail below with reference to the following drawings. The drawings are provided for illustrative purposes only and only describe exemplary embodiments of the present disclosure to facilitate the reader's understanding of the present disclosure. Therefore, these drawings should not be considered to limit the breadth, scope or applicability of the present disclosure. It should be noted that for clarity and ease of description, these drawings are not necessarily drawn to scale.

[0014] Figure 1 An exemplary communication network is shown in which the techniques disclosed herein may be implemented according to an embodiment of the present disclosure.

[0015] Figure 2 A block diagram of a base station (BS) according to some embodiments of the present disclosure is shown.

[0016] Figure 3 A flowchart of a method performed by a BS according to some embodiments of the present disclosure is shown.

[0017] Figure 4 A block diagram of a user equipment (UE) according to some embodiments of the present disclosure is shown.

[0018] Figure 5 A flowchart of a method performed by a UE according to some embodiments of the present disclosure is shown.

[0019] Figure 6 An exemplary pool of reference signal ports for a transmission comprising M physical resource blocks (PRBs) is shown according to some embodiments of the present disclosure.

[0020] Figure 7 Another exemplary pool of reference signal ports for a transmission comprising M PRBs according to some embodiments of the present disclosure is shown.

[0021] Figure 8 An exemplary pool of reference signal ports generated based on orthogonal cover codes (OCCs) according to some embodiments of the present disclosure is shown.

[0022] Fig. 9 An exemplary pool of reference signal ports generated based on orthogonal sequences according to some embodiments of the present disclosure is shown.

[0023] Fig.10 Yet another exemplary pool of reference signal ports for a transmission comprising M PRBs according to some embodiments of the present disclosure is shown.

[0024] Fig.11 Yet another exemplary pool of reference signal ports for a transmission comprising M PRBs according to some embodiments of the present disclosure is shown.

[0025] Fig.12 An exemplary pool of reference signal ports for transmission with M PRBs and 1 / 7 reference signal overhead is shown according to some embodiments of the present disclosure.

[0026] Fig.13 Another exemplary pool of reference signal ports for transmission with M PRBs and 1 / 7 reference signal overhead is shown in accordance with some embodiments of the present disclosure.

[0027] Fig.14 An exemplary pool of reference signal ports for transmission with M PRBs and 1 / 7 reference signal overhead based on OCC generation according to some embodiments of the present disclosure is shown.

[0028] Fig.15 An exemplary pool of reference signal ports for transmission with M PRBs and 1 / 7 reference signal overhead based on orthogonal sequence generation according to some embodiments of the present disclosure is shown.

[0029] Fig.16 Yet another exemplary pool of reference signal ports for transmission with M PRBs and 1 / 7 reference signal overhead according to some embodiments of the present disclosure is shown.

[0030] Fig.17 Four exemplary OCCs for generating a reference signal port pool are shown according to some embodiments of the present disclosure.

[0031] Fig.18 Four exemplary orthogonal sequences for generating a reference signal port pool according to some embodiments of the present disclosure are shown.

[0032] Fig.19 A table showing exemplary non-orthogonal sequences for generating a reference signal port pool according to some embodiments of the present disclosure is shown.

[0033] Fig. 20 An exemplary pool of reference signal ports for a transmission including one PRB and M transmission time intervals (TTIs) according to some embodiments of the present disclosure is shown.

[0034] Fig.21Another exemplary pool of reference signal ports for a transmission including one PRB and M TTIs according to some embodiments of the present disclosure is shown.

[0035] Fig. 22 An exemplary pool of reference signal ports for transmissions with a reference signal region at a starting symbol is shown in accordance with some embodiments of the present disclosure.

[0036] Fig.23 Another exemplary pool of reference signal ports for transmissions with a reference signal region at a starting symbol in accordance with some embodiments of the present disclosure is shown.

[0037] Fig.24 Yet another exemplary pool of reference signal ports for transmissions with a reference signal region at a starting symbol according to some embodiments of the present disclosure is shown.

[0038] Fig.25 An exemplary pool of reference signal ports for a transmission including one PRB with 6 subcarriers is shown according to some embodiments of the present disclosure.

[0039] Fig.26 An exemplary pool of reference signal ports for a transmission including one PRB with 3 subcarriers is shown according to some embodiments of the present disclosure.

[0040] Fig. 27 An exemplary pool of reference signal ports for a transmission including one PRB with 1 subcarrier is shown according to some embodiments of the present disclosure.

[0041] Fig.28 An exemplary pool of reference signal ports generated based on non-orthogonal sequences according to some embodiments of the present disclosure is shown.

[0042] Fig.29 Exemplary signals in uplink transmission according to some embodiments of the present disclosure are shown.

[0043] Fig.30 An exemplary uplink signal generated based on a sign spreading technique according to some embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0044] Various exemplary embodiments of the present disclosure are described below with reference to the accompanying drawings so that one of ordinary skill in the art can make and use the present disclosure. As will be apparent to one of ordinary skill in the art, after reading the present disclosure, various changes or modifications may be made to the examples described herein without departing from the scope of the present disclosure. Therefore, the present disclosure is not limited to the exemplary embodiments and applications described and illustrated herein. In addition, the specific order and / or hierarchy of the steps in the methods disclosed herein are merely exemplary methods. Based on design preferences, the specific order or hierarchy of the steps of the disclosed methods or processes may be rearranged while remaining within the scope of the present disclosure. Therefore, one of ordinary skill in the art will understand that the methods and techniques disclosed herein present various steps or behaviors in a sample order, and unless otherwise expressly stated, the present disclosure is not limited to the specific order or hierarchy presented.

[0045] A typical wireless communication network includes: one or more base stations (generally referred to as "BS"), each of which provides a geographical radio coverage; and one or more wireless user equipment (generally referred to as "UE"), which can send and receive data within the radio coverage. In order to have low-latency communication or low-power communication or low signaling overhead communication, the UE can use unlicensed transmission to transmit data to the BS, and the unlicensed transmission can be unlicensed (configured grant) transmission based on semi-persistent scheduling and unlicensed transmission based on contention.

[0046] For semi-persistent scheduling of unlicensed transmission, the base station first allocates transmission resources including reference signals to the terminal that is used to access the base station. The terminal can then perform multiple data transmissions to the base station within a time window. Each data transmission is performed according to the transmission resources pre-configured by the base station. Based on these reference signals, the base station can perform active user discovery and channel estimation for these users, which is a broad channel estimation that includes wireless channel estimation and time-frequency offset estimation, etc. The base station can then perform multi-user data detection, demodulation, decoding, etc.

[0047] Contention-based unlicensed transmission is initiated by the terminal without any scheduling or authorization by the base station. When the terminal performs contention-based unlicensed transmission, it automatically determines the transmission resources including the reference signal. Similar to semi-persistent scheduling-based unlicensed transmission, the base station uses the reference signal to perform active user discovery and channel estimation for these users, where the channel estimation is a broad channel estimation including wireless channel estimation and time-frequency offset estimation, etc. Then, the base station can perform multi-user data detection, demodulation, decoding, etc.

[0048] Therefore, both types of license-free data transmission are based on reference signals.To support both types of license-free access, the system may define a reference signal set or pool containing multiple reference signals.

[0049] In unlicensed transmission based on semi-persistent scheduling, the base station pre-assigns reference signals to each user requesting access. To simplify multi-user detection and ensure access robustness, the base station usually assigns different reference signals to different users. Therefore, when a set of system-defined reference signals contains N different reference signals and different reference signals are assigned to different users, the system can support up to N users with unlicensed access based on semi-persistent scheduling. In order to support more users, the number of reference signals must be increased, which means increasing the size of the reference signal set / pool, which will increase the reference signal overhead and detection complexity.

[0050] In contention-based unlicensed data transmission, the terminal will select a reference signal from the reference signal set / pool defined by the system so that the reference signals selected by different terminals are independent of each other. From the perspective of the base station, the process of selecting a reference signal by the terminal is random. This inevitably leads to two users / terminals selecting the same reference signal, which is also called a reference signal conflict. For example, assuming that the reference signal set / pool defined by the system includes N reference signals, the probability that two users select the same reference signal is 1 / N. Once a reference signal conflict occurs, it will not only lead to undetected active user detection, but also cause serious problems in channel estimation based on conflicting reference signals, which may eventually lead to data demodulation failure. As the number of access users increases, the probability of reference signal conflict will also increase. In order to support more contention-based unlicensed access users, the reference signal conflict rate should be reduced. If the number of reference signals is increased to reduce the conflict rate, the size of the reference signal set / pool can be increased, which may increase the reference signal overhead and detection complexity.

[0051] Therefore, for both types of unlicensed access, the number of users supported is limited by the number of reference signals. In order to support more unlicensed user access, the system needs to define as many reference signals as possible, or the reference signal set / pool defined by the system should include as many reference signals or reference signal ports as possible. However, in existing systems, both types of unlicensed access require reference signals to perform channel estimation for data symbol demodulation. Such reference signals are also commonly referred to as demodulation reference signals (DMRS). Therefore, each reference signal will need to occupy sufficient resources in the entire transmission bandwidth. In other words, each reference signal in the existing system cannot be too sparse in the entire transmission bandwidth, and it must have a certain density so that the wireless multipath channel (i.e., frequency selective channel and timing offset) in the entire transmission bandwidth can be estimated. In addition, if it is also necessary to compensate for the frequency offset of each accessing user, each reference signal in the existing system must have a certain density in the entire transmission time.

[0052] The present invention proposes a new reference signal design and a corresponding advanced multi-user detection method at the receiving end to facilitate and efficiently achieve unlicensed access of ultra-high payloads. One object of the present invention is to support unlicensed access for as many users as possible using a simple transmission and reception scheme.

[0053] The method disclosed in the present invention can be implemented in a wireless communication network, where the BS and the UE can communicate with each other through a communication link (e.g., through a downlink radio frame from the BS to the UE or through an uplink radio frame from the UE to the BS). In various embodiments, the BS in the present disclosure may be referred to as a network side, and may include or be implemented as a next-generation node B (gNB), an E-UTRAN node B (eNB), a transmission / reception point (TRP), an access point (AP), a non-ground receiving point for satellite / hot air balloon / unmanned aerial vehicle (UAV) communication, a radio transceiver in a vehicle of a vehicle-to-vehicle (V2V) wireless network, etc.; and the UE in the present disclosure may be referred to as a terminal, and may include or be implemented as a mobile station (MS), a station (STA), a ground device for satellite / hot air balloon / unmanned aerial vehicle (UAV) communication, a radio transceiver in a vehicle of a vehicle-to-vehicle (V2V) wireless network, etc. According to various embodiments of the present disclosure, the BS and the UE may be described herein as non-limiting examples of a "wireless communication node" and a "wireless communication device", respectively, which may implement the method disclosed herein and may be capable of wireless and / or wired communication.

[0054] Figure 1 FIG. 1 shows an exemplary communication network 100 in which the techniques disclosed herein may be implemented according to one embodiment of the present disclosure. Figure 1 As shown, the exemplary communication network 100 includes a base station (BS) 101 and a plurality of UEs (UE 1 110, UE 2 120 ... UE 3 130), wherein the BS 101 can communicate with the UEs according to a wireless protocol. Each UE can transmit uplink data to the BS 101 through unlicensed transmission based on a reference signal selected from a reference signal set.

[0055] Figure 2 1 shows a block diagram of a base station (BS) 200 according to some embodiments of the present disclosure. BS 200 is an example of a device that can be configured to implement the various methods described herein. Figure 2 As shown, BS 200 includes a housing 240, which contains a system clock 202, a processor 204, a memory 206, a transceiver 210 including a transmitter 212 and a receiver 214, a power module 208, a pilot signal analyzer 220, a channel estimator 222, a time-frequency offset corrector 224, a data payload analyzer 226, a receive beamforming unit 228 and a spatial domain merging unit 229.

[0056] In the present embodiment, system clock 202 provides timing signals to processor 204 to control the timing of all operations of BS 200. Processor 204 controls the general operation of BS 200 and may include one or more processing circuits or modules, such as a central processing unit (CPU) and / or any combination of a general purpose microprocessor, microcontroller, digital signal processor (DSP), field programmable gate array (FPGA), programmable logic device (PLD), controller, state machine, gating logic, discrete hardware components, dedicated hardware finite state machines, or any other suitable circuit, device, and / or structure that can perform computations or other operations on data.

[0057] The memory 206 may include a read-only memory (ROM) and a random access memory (RAM), and may provide instructions and data to the processor 204. A portion of the memory 206 may also include a non-volatile random access memory (NVRAM). The processor 204 typically performs logic and arithmetic operations based on program instructions stored in the memory 206. The instructions (also referred to as software) stored in the memory 206 may be executed by the processor 204 to perform the methods described herein. The processor 204 and the memory 206 together form a processing system that stores and executes software. As used herein, "software" refers to any type of instruction, whether it refers to software, firmware, middleware, microcode, etc., which can configure a machine or device to perform one or more desired functions or processes. Instructions may include code (e.g., in source code format, binary code format, executable code format, or any other suitable code format). When the instructions are executed by one or more processors, the processing system performs the various functions described herein.

[0058] The transceiver 210 includes a transmitter 212 and a receiver 214, allowing the BS 200 to send data to a remote device (e.g., a UE or another BS) and receive data from a remote device (e.g., a UE or another BS). The antenna 250 is generally connected to the housing 240 and electrically coupled to the transceiver 210. In various embodiments, the BS 200 includes (not shown) multiple transmitters, multiple receivers, and multiple transceivers. In one embodiment, the antenna 250 is replaced with a multi-antenna array 250, which can form multiple beams, each beam pointing in a different direction. The transmitter 212 can be configured to wirelessly transmit packets with different packet types or functions, which are generated by the processor 204. Similarly, the receiver 214 is configured to receive packets with different packet types or functions, and the processor 204 is configured to process packets of multiple different packet types. For example, the processor 204 can be configured to determine the type of the packet and process the packet and / or the field of the packet accordingly.

[0059] In wireless communication, BS 200 may receive a signal from a UE via an uplink transmission, wherein the signal includes a pilot signal. For example, the pilot signal analyzer 220 in this example may receive a signal including a pilot signal from the UE via a receiver 214, or may only receive a pilot signal. In one embodiment, the pilot signal occupies N symbol resources, where N is an integer greater than 1, such as greater than 24. The pilot signal analyzer 220 may analyze the pilot signal to determine that the pilot signal includes at least one reference signal (RS) port, which is determined from a predetermined RS port pool, wherein the predetermined pool includes at least N RS ports.

[0060] In one embodiment, the pilot signal includes W RS ports, each RS port is independently selected or determined from a predetermined RS port pool, where W is an integer greater than 1, such as W=2, W=3, or W=4. In one embodiment, each RS port in the predetermined pool has Nz non-zero elements, where Nz is an integer greater than 0 and less than 9, such as Nz=1, Nz=2, Nz=3, Nz=4, or Nz=6. In one embodiment, the Nz non-zero elements of each RS port in the predetermined pool are adjacent in the time domain and / or frequency domain.

[0061] In one embodiment, the predetermined RS port pool is at least one of: a receive beam detection reference signal port pool; and a receive beam estimation reference signal port pool. A signal may be received from the UE via a contention-based unlicensed uplink transmission mode or via a semi-persistent scheduling-based unlicensed uplink transmission mode.

[0062] In one embodiment, the predetermined pool has exactly N RS ports, which are generated based on multiple orthogonal cover codes or multiple orthogonal sequences. In another embodiment, the predetermined pool has more than N RS ports generated based on multiple non-orthogonal sequences. In yet another embodiment, the predetermined pool has more than k*N RS ports generated based on multiple non-orthogonal sequences, where k=2, k=3, k=4, k=8 or k=16. In one embodiment, each RS port in the predetermined pool has at most two non-zero elements, i.e., one non-zero element or two non-zero elements.

[0063] In one embodiment, the signal further comprises a data payload, wherein the data payload comprises information related to a pilot signal comprising at least one RS port.The at least one RS port may be selected from a predetermined pool based on at least one bit in the data payload.

[0064] The channel estimator 222 can estimate a channel value of the entire transmission bandwidth experienced by the signal transmitted by the UE based on the Nz non-zero elements of each RS port in the predetermined pool. In one embodiment, the channel estimator 222 and the data payload analyzer 226 can perform blind channel equalization based on the data payload; and the time-frequency offset corrector 224 and the data payload analyzer 226 can perform blind time-frequency offset correction based on the data payload.

[0065] In one embodiment, the receive beamforming unit 228 may perform receive beamforming based on the pilot signal; and the spatial combining unit 229 may perform spatial combining based on the pilot signal to obtain the data signal. Then, the channel estimator 222 may perform channel estimation and compensation based on the data signal; and the time-frequency offset corrector 224 may perform time-frequency offset estimation and compensation based on the data signal. Then, the data payload analyzer 226 may demodulate and analyze the data payload based on the compensated data signal.

[0066] The power module 208 may include a power source (e.g., one or more batteries) and a power regulator to provide power to the Figure 2 Each of the above modules in provides regulated power. In some embodiments, if BS 200 is coupled to a dedicated external power source (eg, a wall outlet), power module 208 may include a transformer and a power conditioner.

[0067] The various modules described above are coupled together via a bus system 230. The bus system 230 may include a data bus, and in addition to the data bus, may include, for example, a power bus, a control signal bus, and / or a status signal bus. It should be understood that the modules of the BS 200 may be operatively coupled to each other using any suitable technology and medium.

[0068] although Figure 2 Many separate modules or components are shown in the figure, but those skilled in the art will understand that one or more modules can be combined or implemented together. For example, the processor 204 can not only implement the functions described above about the processor 204, but also implement the functions described above about the pilot signal analyzer 220. On the contrary, Figure 2 Each module shown in can be implemented using multiple individual components or elements.

[0069] Figure 3 BS (eg Figure 2200 in the embodiment of the present invention. At operation 302, the BS receives a signal including both a pilot signal and a data payload from the UE via an unlicensed uplink transmission. At operation 304, the BS analyzes the pilot signal. At operation 306, the BS performs receive beamforming or spatial domain combining based on the pilot signal to generate data symbols. At operation 308, the BS performs blind channel estimation based on the data symbols. At operation 310, the BS performs time-frequency offset correction based on the data symbols. At operation 312, the BS demodulates and decodes the data payload. At operation 314, the BS reconstructs and subtracts the received signal associated with the successfully decoded codeword. The reconstruction of the received signal includes the reconstruction of the data signal and the pilot signal, which is based on the information included in the data payload and related to the pilot signal. After reconstruction, the user's data and reference signal will be removed / subtracted from the received signal, and then the next round of multi-user detection will be performed. Figure 3 The order of the steps shown may be changed according to different embodiments of the present disclosure.

[0070] Figure 4 4 is a block diagram of a UE 400 according to some embodiments of the present disclosure. The UE 400 is an example of a device that can be configured to implement the various methods described herein. Figure 4 As shown, UE 400 includes a housing 440 that contains a system clock 402, a processor 404, a memory 406, a transceiver 410 including a transmitter 412 and a receiver 414, a power module 408, a pilot signal generator 420, an RS port selector 422, an RS port pool determiner 424, and a data payload generator 426.

[0071] In this embodiment, the system clock 402, processor 404, memory 406, transceiver 410, and power module 408 operate in a manner similar to the system clock 202, processor 204, memory 206, transceiver 210, and power module 208 in BS 200. Antenna 450 or multiple antenna array 450 is typically connected to housing 440 and electrically coupled to transceiver 410.

[0072] The pilot signal generator 420 in this example can generate a pilot signal, wherein the pilot signal includes at least one reference signal (RS) port, which is determined from a predetermined RS port pool. In one embodiment, the predetermined pool includes at least N RS ports, where N is an integer greater than 1, such as greater than 24. In one embodiment, the pilot signal occupies N symbol resources.

[0073] In one embodiment, the pilot signal includes W RS ports, where W is an integer greater than 1, such as W = 2, W = 3, or W = 4. The RS port selector 422 may independently select or determine each of the W RS ports from a predetermined RS port pool.

[0074] In one embodiment, the RS port pool determiner 424 may determine an RS port pool predefined by a protocol or standard. For example, each RS port in the predetermined pool has Nz non-zero elements, where Nz is an integer greater than 0 and less than 9, such as Nz=1, Nz=2, Nz=3, Nz=4, or Nz=6. In one embodiment, the Nz non-zero elements of each RS port in the predetermined pool are adjacent in the time domain and / or frequency domain. In one embodiment, the Nz non-zero elements of each RS port in the predetermined pool are used to estimate a channel value of the entire transmission bandwidth experienced by the signal transmitted by the UE. In one embodiment, the predetermined RS port pool is at least one of the following: a receive beam detection reference signal port pool; and a receive beam estimation reference signal port pool.

[0075] In one embodiment, the predetermined pool has exactly N RS ports, which are generated based on multiple orthogonal cover codes or multiple orthogonal sequences. In another embodiment, the predetermined pool has more than N RS ports generated based on multiple non-orthogonal sequences. In yet another embodiment, the predetermined pool has more than k*N RS ports generated based on multiple non-orthogonal sequences, where k=2, k=3, k=4, k=8 or k=16. In one embodiment, each RS port in the predetermined pool has at most two non-zero elements, i.e., one non-zero element or two non-zero elements.

[0076] In one embodiment, the data payload generator 426 may generate a data payload including information related to a pilot signal including at least one RS port. The data payload generator 426 may transmit a signal including a pilot signal and a data payload to the BS via the transmitter 412. The signal may be transmitted to the BS via the transmitter 412 in a contention-based unlicensed uplink transmission manner or in a semi-persistent scheduling-based unlicensed uplink transmission manner. In one embodiment, the RS port selector 422 may select at least one RS port from a predetermined pool based on at least one bit in the data payload.

[0077] In one embodiment, the data payload is used to perform blind channel equalization and / or blind time-frequency offset correction at the BS. In another embodiment, the pilot signal is used to perform receive beamforming or spatial combining at the BS before demodulating the data payload.

[0078] The various modules described above are coupled together via a bus system 430. The bus system 430 may include a data bus, and in addition to the data bus, may include, for example, a power bus, a control signal bus, and / or a status signal bus. It should be understood that the modules of the UE 400 may be operatively coupled to each other using any suitable technology and medium.

[0079] although Figure 4 Many separate modules or components are shown in FIG. 4 , but a person skilled in the art will appreciate that one or more modules may be combined or implemented together. For example, the processor 404 may implement not only the functions described above with respect to the processor 404, but may also implement the functions described above with respect to the RS port selector 422. On the contrary, Figure 4 Each module shown in can be implemented using multiple individual components or elements.

[0080] Figure 5 UE (eg Figure 4 4. The method 500 is a flowchart of a method 500 performed by a UE 400 in a UE. At operation 502, the UE generates a data payload to be transmitted to the BS. At operation 504, the UE determines a reference signal (RS) port pool generated based on multiple orthogonal and / or non-orthogonal sequences. At operation 506, the UE selects at least one RS port from the pool based on at least one bit in the data payload. At operation 508, the UE generates a pilot signal including at least one RS port. At operation 510, the UE transmits a signal including both the pilot signal and the data payload to the BS via an unlicensed uplink transmission. Figure 5 The order of the steps shown may be changed according to different embodiments of the present disclosure.

[0081] Now, different embodiments of the present disclosure will be described in detail below. Note that the features of the embodiments and examples in the present disclosure can be combined with each other in any way without conflict.

[0082] A main purpose of the embodiment is to greatly reduce the task of reference signals so that each reference signal occupies the minimum resources, or each reference signal can be the sparsest to achieve the maximum number of reference signals in the pool. This enables semi-persistent scheduling-based unlicensed transmission and contention-based unlicensed transmission to support more users.

[0083] In one embodiment, the disclosed system utilizes advanced data-based channel estimation techniques (rather than reference signal-based) to estimate the channel and time-frequency offsets for the entire transmission bandwidth through the characteristics of the data itself, for example, based on simple geometric characteristics of the constellation shape of low-order modulated data symbols (similar to binary phase shift keying (BPSK) or quadrature phase shift keying (QPSK) data symbols). In other words, it is no longer necessary to estimate the channel over the entire transmission bandwidth and the time-frequency offset based on the reference signal. Therefore, the task of the reference signal in the present invention is much smaller than that in the traditional method. Therefore, each reference signal occupies much less resources than the traditional system. Therefore, under a certain reference signal overhead, the number of reference signals in the present invention is much larger than the number of reference signals in the traditional system.

[0084] On the other hand, when the base station has multiple receiving antennas, it can theoretically provide very powerful spatial capabilities to improve the performance of multi-user access. In order to obtain this spatial capability, the present invention proposes an "extremely sparse" reference signal, which can be used to estimate the spatial channel h of each access user. k =[h k1 ,h k2 ...h kR ] t , where t is the transpose operator. These estimated spatial channel vectors are then used to spatially combine the received signals. Specifically, the signals of user k are combined for spatial domain combining in the following way: s k =w k *y, where y = [y k1 ,y k2 ...y kR ] t represents the received signal of R receiving antennas, and if maximum ratio combining (MRC) is used, then w k =h k ', or if minimum mean square error (MMSE) based spatial merging is used, then w k =h k '(HH'+σ 2 I) -1 , where h k 'It's h k is the conjugate transpose of , H is the matrix consisting of the spatial channel vectors of all detected users, σ is the mean square error of additive white Gaussian noise (AWGN), and I is the R*R identity matrix. The receiver can then use the spatially combined data symbol s k To estimate the channel and its corresponding time-frequency offset experienced by the signal of user k over the entire transmission bandwidth. Then, for the spatially combined data symbol s kChannel equalization and time-frequency offset compensation are performed. The receiver can then demodulate and decode the data symbols after channel and time-frequency offset compensation.

[0085] The reference signal is a pilot signal in the present invention, which is used only for spatial combining and not for channel equalization or demodulation. On the other hand, spatial combining has the same function as receive beamforming. Therefore, the reference signal can be regarded as a spatial combining reference signal (SCR), or a receive beamforming reference signal (RBRS), or a receive beam detection reference signal (RBDRS).

[0086] Therefore, in the disclosed embodiments of the present invention, there is no need to use a reference signal (RS) to estimate the channel over the entire transmission bandwidth, or to estimate the time-frequency offset. Therefore, the reference signal proposed in the present invention is very sparse. Figure 6 An example is shown where the reference signal may be referred to as a reference signal port or an RBDRS port. Figure 6 An exemplary pool of reference signal ports for a transmission including M physical resource blocks (PRBs) according to some embodiments of the present disclosure is shown. Figure 6 As shown, the transmission includes M PRBs of time-frequency resources, where each PRB includes: 14 orthogonal frequency division multiplexing (OFDM) symbols (or DFT-S-OFDM or SC-FDMA symbols) in the time domain and 12 subcarriers in the frequency domain. Figure 6 As shown, each small grid 601 is a subcarrier of an OFDM (or DFT-S-OFDM or SC-FDMA) symbol, which is also generally referred to as a resource element (RE). Figure 6 The PRB shown contains a total of 12*14=168 REs. In each PRB or each transmission, 1 / 14 of the transmission resources are used to transmit reference signals. That is, M*12 REs are used to transmit reference signals. Figure 6 As shown, the data payload 620 occupies the remaining RE resources. However, each reference signal defined by the system has only one non-zero symbol (non-zero signal or useful signal) on one RE, and there is no signal in the remaining resources (or the value in other resources is 0), which is an extremely sparse reference signal or the sparsest reference signal, because no other type of reference signal can be sparser than it. Therefore, the reference signal area 610 accounts for 1 / 14 of the transmission overhead and can be divided into a total of M*12 reference signal ports or RBDRS ports. In one embodiment, in the case of M=6 PRBs with 1 / 14 overhead, there will be a total of 6*12=72 reference signals in the RS pool, which is much larger than the 8 or 12 reference signals in the pool of the existing NR system.

[0087] like Figure 6As shown, different RBDRS ports 611, 612, 613, 614, 615 in the RS pool have non-zero symbols at different RE positions. For example, the first RBDRS port 611 has a non-zero symbol carried on the first RE of the reference signal region 610, and the value is 0 in all other REs; the second RBDRS port 612 has a non-zero symbol carried on the second RE of the reference signal region 610, and the value is 0 in all other REs; ... The M*12th RBDRS port 615 has a non-zero symbol carried on the M*12th RE of the reference signal region 610, and the value is 0 in all other REs.

[0088] In this case, each pilot signal including a corresponding RBDRS port occupies N symbol resources or REs. This is because, when a user transmits a pilot signal and a data symbol in a transmission. Although some RBDRS values ​​of the pilot signal are 0, these 0 value positions cannot be used to transmit data symbols or data payloads. Data payloads are transmitted through data symbols. In one embodiment, the receiver will perform blind detection using data symbols. Each transmission includes a pilot signal and a data payload (or data symbol). Therefore, Figure 6 The symbol resources used to transmit the pilot signal are M*12, or the resource overhead is M*12 symbol resources or REs used to transmit the pilot signal.

[0089] and Figure 6 similar, Figures 7 to 11 Different forms of the sparsest RBDRS under 1 / 14 reference signal overhead are shown. Figures 7 to 11 As shown, there are M PRBs with Figure 6 Therefore, there are a total of M*12 RBDRS ports in the RBDRS pool.

[0090] like Figure 7 As shown, the RBDRS pool includes M*6 RBDRS port groups, each of which includes two RBDRS ports, and their non-zero elements occupy the same two REs. To simplify the expression, the reference signal carried on multiple adjacent or continuous REs in the time domain and frequency domain is called a reference signal unit (RSU). Figure 7 In the IEEE 802.11ac standard, the reference signal carried on two consecutive REs in the frequency domain is called an RSU.

[0091] The non-zero symbols of each RBDRS port group are carried on the same RE, and different reference signals in the same group can only be distinguished by non-zero symbols of different values. Figure 8It is shown that different frequency domain orthogonal cover codes (OCC) of length 2 are used to distinguish different reference signal ports in the same group. Therefore, each of the M*6 RBDRS port groups is divided into two different RBDRS ports. For example, based on two different OCC codes, the RBDRS port group 711 is divided into two RBDRS ports 811, 812. Therefore, M*12 RBDRS ports are included in Figure 8 Similarly, in Fig. 9 In the example, different orthogonal sequences of length 2 are used to distinguish different reference signal ports in the same group. Therefore, each of the M*6 RBDRS port groups is divided into two different RBDRS ports. For example, based on two different orthogonal sequences, the RBDRS port group 711 is divided into two RBDRS ports 911 and 912. Therefore, M*12 RBDRS ports are included in Fig. 9 The RBDRS port pool in the.

[0092] Fig.10 Yet another exemplary pool of reference signal ports for a transmission comprising M PRBs is shown, where M*12 RBDRS ports are grouped into different groups, each group having three non-zero symbols at three adjacent or consecutive RE positions. Fig.11 Another exemplary pool of reference signal ports for transmission comprising M PRBs is shown, where M*12 RBDRS ports are grouped into different groups, where each group has four adjacent or consecutive non-zero symbols at four RE positions. Fig.10 and Fig.11 In the present invention, OCC or orthogonal sequence can be used to distinguish different RBDRS ports in the same group.

[0093] Figures 12 to 19 Different forms of the sparsest RBDRS signal under a larger reference signal overhead (1 / 7 overhead) are shown. There are M*24 RBDRS ports in the reference signal pool. Specifically, when there are M=6 PRBs and the overhead is 1 / 7, there will be 24*6=144 reference signals. This can support 144 semi-persistent scheduling-based unlicensed users and more contention-based unlicensed users than the existing system with only 12 or 8 reference signals, because the probability of reference signal collision between any two contention-based unlicensed users is 1 / 144, which is much lower than the 1 / 12 probability in the existing system.

[0094] like Fig.12As shown, the definition of the RBDRS port enables the first two OFDM symbols to carry the RBDRS signal, that is, the first two OFDM symbols are reference signal areas or reference signal regions 1210, which occupy 1 / 7 of the transmission resource overhead. The remaining resources 1220 can be used to transmit data payloads. Fig.12 Each RBDRS port in the RBDRS pool has only one non-zero symbol on one RE, and no signal or a value of 0 in all other REs. Different RBDRS ports 1211, 1212, ... 1218 in the RBDRS pool have non-zero symbols at different RE positions.

[0095] like Fig.13 As shown, the RBDRS pool includes M*12 RBDRS port groups, where each RBDRS port group includes two consecutive REs in the time domain. The non-zero symbols of each RBDRS port group are carried on the same RE, and different reference signals in the same group can be distinguished by non-zero symbols of different values. For example, Fig.14 It is shown that different time domain orthogonal cover codes (OCC) of length 2 are used to distinguish different reference signal ports in the same group. Therefore, each of the M*12 RBDRS port groups is divided into two different RBDRS ports. For example, based on two different OCC codes, namely, [1, 1] and [1, -1], the RBDRS port group 1311 is divided into two RBDRS ports 1411, 1412. Therefore, M*24 RBDRS ports are included in Fig.14 Similarly, in Fig.15 In the example, different orthogonal sequences of length 2, i.e., [1, j] and [1, -j], are used to distinguish different reference signal ports in the same group. Therefore, each of the M*12 RBDRS port groups is divided into two different RBDRS ports. For example, based on two different orthogonal sequences, the RBDRS port group 1311 is divided into two RBDRS ports 1511 and 1512. Therefore, M*24 RBDRS ports are included in Fig.15 The RBDRS port pool in the.

[0096] Fig.16 Another exemplary pool of reference signal ports for transmission with M PRBs and 1 / 7 reference signal overhead is shown, where M*24 RBDRS ports are grouped into M*6 groups, each group having four non-zero symbols at four adjacent or consecutive RE positions. Fig.17 and Fig.18 As shown, the OCC of length 4 shown in Table 1 1715 or the orthogonal sequence of length 4 shown in Table 2 1815 can be used to distinguish Fig.16 Therefore, each RBDRS port group is divided into four RBDRS ports based on four OCC codes of length 4 or orthogonal sequences of length 4. Other orthogonal sequence sets of length 4 can also be used to divide one RBDRS port group into four RBDRS ports. 16 orthogonal sequence sets of length 4 are as follows: Fig.19 As shown in Table 3, there are 64 rows in total, and every four consecutive rows constitute an orthogonal sequence set with a length of 4.

[0097] In some embodiments, a larger overhead (e.g., 2 / 7 overhead) may also be used for very sparse or most sparse reference signals. Very sparse reference signals with larger overhead may follow Figures 6 to 18 Although the design shown in Figures 6 to 18 The extremely sparse reference signals shown in the figure are all located 1 or 2 symbols in front of the transmission resource, but other positions of the extremely sparse reference signals are also included in the scope of the present invention. For example, the position of the extremely sparse reference signal can also be located in the middle of the transmission resource.

[0098] exist Figure 20 to Figure 24 In the present invention, extremely sparse reference signals are used in transmission resources of longer duration, and the transmission resources include: a bandwidth of one PRB in the frequency domain, and multiple transmission time intervals (TTIs) in the time domain, for example, M TTIs. Figure 20 to Figure 24 The scenario in which the reference signal regions 2010 and 2210 occupy 1 / 7 of the resource overhead is shown. The extremely sparse reference signal region may be located at the start OFDM symbol of each TTI, for example Fig.21 and Fig. 22 or integrated at the starting OFDM symbol of the entire transmission resource, for example Figure 22 to Figure 24 in area 2210.

[0099] exist Figure 25 to Figure 27 In the present invention, extremely sparse reference signals are used in transmission resources, wherein each PRB has a bandwidth of less than 12 subcarriers, i.e., less than 12 subcarriers for each OFDM symbol. Assuming that there are A subcarriers in one PRB bandwidth and each TTI includes 14 OFDM symbols, a transmission includes M TTIs. The extremely sparse reference signal regions 2510, 2610, 2710 use 2*M OFDM symbols. Then, the extremely sparse reference signal regions 2510, 2610, 2710 include a total of 2*M*A symbol elements (REs), and they may include a maximum of 2*M*A orthogonal extremely sparse reference signals.

[0100] Figure 25 to Figure 27 The reference signal area in is at 1 / 7 overhead, i.e., a total of 2*M OFDM symbols are used for extremely sparse reference signals. Fig.25In , one PRB bandwidth includes 6 subcarriers (i.e., 6 subcarriers per OFDM symbol), and there may be a total of M*12 extremely sparse reference signals or RBDRS ports. Fig.26 In , one PRB bandwidth includes 3 subcarriers (i.e., 3 subcarriers per OFDM symbol), and there may be a total of M*6 extremely sparse reference signals or RBDRS ports. Fig. 27 In , one PRB bandwidth includes 1 subcarrier (ie, 1 subcarrier per OFDM symbol), and there may be a total of M*2 extremely sparse reference signals or RBDRS ports.

[0101] The above embodiments and their derivatives can be applied to OFDM and DFT-S-OFDM / SC-FDMA waveforms, which have single carrier characteristics and thus have the advantage of low peak-to-average power ratio (PAPR). When the above embodiments and their derivatives are applied to DFT-S-OFDM / SC-FDMA, the PAPR of the extremely sparse reference signal may not be significantly greater than the PAPR of the data signal. In particular, it can be Figure 7-11 and Fig.16 Any of the schemes shown uses extremely sparse reference signals for DFT-S-OFDM / SC-FDMA. Since extremely sparse reference signals occupy multiple subcarriers, extremely sparse reference signals with low peak-to-average ratio should be used. Fig.10 shows a very sparse reference signal occupying 3 subcarriers, Fig.11 An extremely sparse reference signal occupying 4 subcarriers is shown, which can utilize a demodulation reference signal (DMRS) of length 3 and length 4 in the uplink DFT-S-OFDM / SC-FDMA transmission scheme of an LTE system, a NR system, or a NB-IoT system, respectively.

[0102] Different reference signal ports can be distinguished based on different non-zero symbol positions and different orthogonal sequences. When the reference signal region has N symbols, there may be up to N orthogonal extremely sparse reference signals. In order to further increase the number of reference signals to reduce the collision rate, the orthogonality constraints of the reference signals can be relaxed, and a large number of non-orthogonal sequences can be used to distinguish different extremely sparse or most sparse reference signals. That is, the non-zero symbols in the extremely sparse reference signal can carry sequences from a set of non-orthogonal sequences. Fig.19 A table showing exemplary orthogonal and non-orthogonal sequences for generating a reference signal port pool according to some embodiments of the present disclosure is shown. Fig.19 There are 64 sequences of length 4, divided into 16 groups. Any two sequences in the same group are orthogonal to each other, but any two sequences from two different groups are not orthogonal to each other. These sequences can be used to expand Fig.16 The number of RBDRS ports in the RS pool shown.

[0103] Fig.28 An exemplary pool of reference signal ports generated based on non-orthogonal sequences according to some embodiments of the present disclosure is shown. Fig.28 As shown, each group of extremely sparse reference signals has 4 time-frequency continuous non-zero elements. By carrying 16 non-orthogonal sequences of length 4, 16 extremely sparse reference signals are obtained from one RBDRS group, which is 4 times the reference signal based on orthogonal sequences. When there are M PRBs, each PRB has 12 subcarriers and 14 OFDM symbols, and there is a 1 / 7 overhead for extremely sparse reference signals, the set of non-orthogonal sequences can be used to generate a total of M*24*4=M*96 reference signals. Using an orthogonal sequence of length 4 will generate M*24 reference signals. If using Fig.19 If there are 64 non-orthogonal sequences of length 4 in the RBDRS group, 64 extremely sparse reference signals can be obtained from one RBDRS group, which is 16 times that of the orthogonal sequence scenario. When there are M PRBs, each PRB has 12 subcarriers and 14 OFDM symbols, and has a 1 / 7 overhead for extremely sparse reference signals, Fig.19 The set of non-orthogonal sequences in can be used to generate a total of M*24*16=M*384 reference signals.

[0104] In addition, based on such extremely sparse or most sparse reference signals, contention-based unlicensed access scenarios can be further enhanced. Fig.29 As shown, each access user (or terminal) can autonomously select one or more signals from a set or pool of extremely sparse reference signals. When each terminal autonomously selects multiple reference signals, it can further reduce the reference signal collision rate. For example, each user autonomously selects two extremely sparse reference signals. A collision will only occur when both collide with the reference signal of another user. Therefore, the collision probability is much lower than when only one reference signal is selected.

[0105] The process of autonomously selecting multiple extremely sparse reference signals can be performed in two ways. In the first way, the user (or terminal) autonomously determines multiple extremely sparse reference signals based on the information (or payload) currently being transmitted. Typically, the user (or terminal) autonomously determines multiple extremely sparse transmission signals based on certain information bits (or payload) currently being transmitted. For example, if a predefined set of extremely sparse reference signals of the system contains a total of 2^D (i.e., 2 to the power of D) extremely sparse reference signals, the user (or terminal) can determine one extremely sparse reference signal based on D bits (or payload) of the information currently being transmitted, determine two extremely sparse reference signals based on 2*D bits (or payload) of the information currently being transmitted, and determine W extremely sparse reference signals based on W*D bits (or payload) of the information currently being transmitted.

[0106] In addition, if Fig.30 As shown, by combining with the symbol extension technology, the unlicensed access scenario based on this extremely sparse reference signal technology can be further enhanced. That is, the symbol extension technology is used to generate a data symbol 3020 transmitted together with a pilot signal 3010 including at least one extremely sparse reference signal, and the data payload also contains information about the spread spectrum sequence. A typical symbol extension technology is that each access user (or terminal) uses a spread spectrum code of length L or a spread spectrum code such as c k =[c k1 ,c k2 ...c kL ] to spread its digital modulation symbols, such as BPSK / QPSK symbols. k The extended digital modulation symbol s can generate L symbols s*c k1 、s*c k2 ...s*c kL .

[0107] Since the information (or payload) of different users is independent and unrelated, different users independently select multiple extremely sparse reference signals, so the multiple reference signals selected by different users can avoid conflicts as much as possible.

[0108] In addition, different information bits (or payloads) transmitted by a user (or terminal) are usually independent and uncorrelated, and multiple extremely sparse reference signals selected by a user are also independent and uncorrelated. Independence does not mean inequality. For example, two groups of D bits in the transmitted information are independent and uncorrelated, but can also be equal to each other.

[0109] From the perspective of the system, the extremely sparse reference signals selected by different users and the multiple extremely sparse reference signals selected by one user can be regarded as random signals. From this perspective, it can also be considered that each user randomly selects multiple extremely sparse reference signals.

[0110] In the second method, it is assumed that a set of extremely sparse reference signals predefined by the system contains a total of 2^D extremely sparse reference signals, and the user (or terminal) autonomously generates W*D bits. Then, through these bits, W extremely sparse reference signals are selected from the extremely sparse reference signal set or pool. Then, these W*D bits are transmitted together with the information to be transmitted.

[0111] Both methods can achieve good randomness for multiple extremely sparse reference signals selected by different users, thereby significantly reducing the probability of collision of all reference signals of different users. In addition, these two methods have a common feature. The transmission of each user contains W extremely sparse reference signals and transmission information (or payload), and the transmitted information or payload contains the information of these W extremely sparse reference signals. For example, it contains the index numbers of W extremely sparse reference signals. In this way, once the user's information or payload is successfully decoded, the information of all reference signals used by the user in the transmission can be known, so that interference elimination of the reference signal can be performed. In the first method, multiple extremely sparse reference signals are autonomously selected based on the bits (or payload) of the transmission information itself, so that no additional overhead is required to transmit the information of these extremely sparse reference signals. In the second method, multiple extremely sparse reference signals are autonomously selected using additional bits, which requires additional overhead to transmit the information of these extremely sparse reference signals, resulting in low spectral efficiency.

[0112] In one embodiment, transmission (access) occupies a total of T symbol resources and includes reference signals (or pilots) and data. The overhead rate of the reference signal is a, where a is a real number greater than 0 and less than 1. The total amount of extremely sparse reference signals is T*a.

[0113] For example, the reference signal and the data payload are included in one transmission, which is transmitted through 6 PRBs, where each PRB contains 12*14 REs. The overhead rate of the reference signal is 1 / 7. When the traditional reference signal (DMRS) scheme is used, the total number of reference signals in the RS pool (or the number of DMRS ports) can be as high as 12. In the present invention, under the same 1 / 7 overhead, the number of pilots or reference signals can be 6*24=144 reference signals, and when M=6, each reference signal is very sparse, such as Fig.12 shown.

[0114] These reference signals are defined by the communication system. For example, the communication system can define: how many reference signals the system has, what sequence or pattern each reference signal uses, etc. For example, for LTE uplink transmission, two types of DMRS are defined. One type of reference signal is defined based on different cyclic shifts of a sequence (such as a Zadoff-Chu (ZC) sequence including a quadrature phase shift keying (QPSK) element or a computer-searched ZC-like sequence). In addition, OCC codes can be used to define more reference signals. Another type of reference signal is a DMRS based on a comb structure or a code division multiple access (CDM) group structure. In either case, in existing systems, the maximum number of reference signals is 24 at a certain overhead (1 / 7 or 2 / 7) because channel equalization relies on reference signals to estimate the entire wireless channel. In some cases, reference signals are also relied on to estimate specific time-frequency offsets.

[0115] The system disclosed in the present invention can perform channel equalization and time-frequency offset correction based on the data symbols themselves, which is called blind equalization and blind time-frequency offset correction. Good properties of data symbols are used, such as the simple geometric properties of the constellation shape of low-order modulation (e.g., BPSK, QPSK) data symbols and the second-order moments of received data symbols. Therefore, there is no need to rely on reference signals for channel equalization, and therefore there is no need to use reference signals to estimate the time-frequency offset experienced by the entire wireless channel or transmission.

[0116] In a scenario where there are multiple receiving antennas on the receiving side, when the spatial channel of each access user is known, the receiving side can perform appropriate spatial combining (or receiving beamforming), which can suppress multi-user interference and achieve diversity, thereby significantly improving the multi-user access performance. The use of spatial capabilities is very important for multi-user access systems. Although channel equalization and time-frequency offset correction can be performed by the data symbol itself, spatial combining / receiving beamforming cannot be achieved based on the data symbol itself. Therefore, the present invention proposes to estimate the spatial channel based on few or very sparse pilots (reference signals), which may only include one channel value of the entire transmission bandwidth experienced by the data symbol, and then perform spatial combining / receiving beamforming based on the estimated spatial channel. The spatially combined data symbol still carries the wireless channel and time-frequency offset. Therefore, before demodulation and decoding, channel equalization and time-frequency offset correction are performed based on the spatially combined data symbol. In order to improve the performance of multi-user detection, interference elimination can be performed on the correctly decoded user signal (including data signal and reference signal) to enter the next round of iteration until all possible users are successfully decoded.

[0117] Therefore, the reference signal designed according to the embodiment of the present invention is not used for channel equalization, but for spatial combining or receiving beamforming. That is, the reference signal proposed in this article is to estimate the spatial combining weight of each user, or to estimate the receiving beam of each user, without estimating the entire wireless channel and time-frequency offset of each user. Therefore, the reference signal of each user does not require many resources or many degrees of freedom, or in other words, a small amount of non-zero signals of the reference signal of each user can occupy very local time-frequency resources compared with the entire bandwidth and / or duration of the transmission. Under a given overhead, based on the extremely sparse reference signal scheme proposed in this article, the system can implement more reference signals or reference signal ports in the RS pool.

[0118] In order to pursue the best performance, the maximum number of reference signals can be designed. For example, for a transmission including 6 PRBs and 1 TTI, the reference signal has a resource overhead of 1 / 7, and 144 REs are used to carry the reference signal. Although the conventional scheme has a maximum of 24 DMRS signals, an embodiment of the present invention can implement 144 reference signals, such as Fig.12 As shown, when M=6. In this case, each reference signal is not a DMRS but a receive beam detection RS or a receive beam estimation RS.

[0119] In one embodiment, each reference signal in the RS pool occupies N symbol resources, and there are a total of N extremely sparse reference signals, where N is an integer. In order to maximize the number of reference signals, it is best to design N pilot resources outside the N symbol resources. For example, when transmitting 6 PRBs and 1 TTI with time-frequency resources and 1 / 7 RS overhead, N=2*12*6=144 symbols will be used for reference signals. When a maximum of 24 RS ports are defined in the existing system, the present invention proposes 144 RS ports based on 144 symbol resources. In the case of an unlicensed uplink transmission mode based on semi-persistent scheduling, the user's pilots are orthogonal, and 144 RS ports can be allocated to a maximum of 144 users. In the case of a contention-based unlicensed uplink transmission mode, each user can randomly select an RS from the 144 RS ports, which will result in a smaller probability of conflict.

[0120] In one embodiment, each reference signal in the RS pool occupies N symbol resources, and there are a total of more than N extremely sparse reference signals, where N is an integer. The non-zero symbols in the extremely sparse reference signal can use non-orthogonal sequences to further expand the number of reference signal ports in the RS pool and reduce conflicts. When there are N symbols in the reference signal area, up to N extremely sparse reference signals can be achieved using orthogonal sequences on the non-zero symbols of the extremely sparse reference signal. In order to further increase the number of reference signals and reduce the conflict rate, the orthogonality constraints of the reference signal can be relaxed, and non-orthogonal extremely sparse reference signals can be used. That is, the non-zero symbols of the extremely sparse reference signal carry sequences from a set of non-orthogonal sequences.

[0121] like Fig.28 As shown, each set of sparse reference signals has 4 time-frequency continuous non-zero elements. By carrying 16 non-orthogonal sequences of length 4, 16 extremely sparse reference signals are achieved. When there are M PRBs, each PRB has 12 subcarriers and 14 OFDM symbols, with an overhead of 1 / 7 for extremely sparse reference signals, a set of non-orthogonal sequences can be used to generate a total of M*24*4=M*96 reference signals. Using an orthogonal sequence of length 4 will generate M*24 reference signals.

[0122] In one embodiment, each reference signal includes only one reference signal unit (RSU), and the remaining symbol resources of the RS region (RSregion) or the RS area (RSarea) either have no signal or have a value of zero.

[0123] In one embodiment, the transmitter or terminal autonomously selects an extremely sparse reference signal from an extremely sparse reference signal pool defined by the system. The transmitted information includes information of the selected reference signal. In another embodiment, the transmitter or terminal autonomously selects W RSs from an extremely sparse reference signal pool defined by the system, where W is an integer greater than 1, such as 2, 3, or 4. The transmitted information includes information of the selected W reference signals.

[0124] At the receiving end, when the receiver or base station has multiple receiving antennas, it can provide very powerful spatial capability to improve the performance of multi-user access. In order to obtain the spatial capability, a method is disclosed below according to an embodiment.

[0125] First, the extremely sparse reference signal can be used to estimate the spatial channel or spatial channel vector h of each access user k =[h k1 ,h k2 ...h kR ] t , where t is the transpose operator.

[0126] Second, these estimated spatial channels are then used to spatially combine the received signals. Specifically, spatial combining is performed on the signal of user k by: s k =w k *y, where y = [y k1 ,y k2 ...y kR ] t represents the received signal of R receiving antennas, and if maximum ratio combining (MRC) is used, then w k =h k ', or if minimum mean square error (MMSE) based spatial merging is used, then w k =h k '(HH'+σ 2 I) -1 ,h k 'It's h k is the conjugate transpose of , H is the matrix consisting of the spatial channel vectors of all detected users, σ is the mean square error of AWGN, and I is the R*R identity matrix.

[0127] Third, the receiver can use the spatially combined data symbols s k To estimate the channel over the entire transmission bandwidth experienced by the signal of user k, and to estimate the time-frequency offset. In this estimation, good properties of data symbols are used, such as the simple geometric properties of the constellation shape of low-order modulation (e.g., BPSK, QPSK) data symbols.

[0128] Fourth, for the data symbol s of spatial domain merging k Perform channel compensation and time-frequency offset compensation.

[0129] Fifth, after channel and time-frequency offset compensation, the receiver can demodulate and decode the data symbols.

[0130] Once the user information is successfully decoded, the user's data and reference signal are removed from the received signal and the next round of multi-user detection is performed.

[0131] Each user's transmission contains W extremely sparse reference signals and transmission information (or payload), and the transmitted information or payload contains the information of these W extremely sparse reference signals. For example, the transmitted information or payload contains the index numbers of the W extremely sparse reference signals. In this way, once the user's information or payload is successfully decoded, the information of all reference signals used by the user in the transmission can be known, so that interference cancellation of the reference signals can be performed.

[0132] In the present application, the technical features in various embodiments can be used in combination in one embodiment without causing conflicts. Each embodiment is only an exemplary embodiment of the present application.

[0133] Although various embodiments of the present disclosure have been described above, it should be understood that they are presented only by way of example and not by way of limitation. Similarly, various figures may depict exemplary architectures or configurations, which are provided to enable those of ordinary skill in the art to understand the exemplary features and functions of the present disclosure. However, these persons should understand that the present disclosure is not limited to the exemplary architectures or configurations shown, but may be implemented using various alternative architectures and configurations. In addition, as will be appreciated by those of ordinary skill in the art, one or more features of an embodiment may be combined with one or more features of another embodiment described herein. Therefore, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments.

[0134] It should also be understood that any reference to an element using names such as "first," "second," etc., herein does not generally limit the number or order of these elements. Rather, these names may be used herein as a convenient method of distinguishing between two or more elements or instances of an element. Thus, a reference to a first and a second element does not mean that only two elements may be used, or that the first element must precede the second element in some manner.

[0135] In addition, those skilled in the art will appreciate that any of a variety of different technologies and techniques may be used to represent information and signals. For example, data, instructions, commands, information, signals, bits, and symbols, etc., that may be referenced in the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0136] Those of ordinary skill in the art will further understand that any of the various illustrative logical blocks, modules, processors, devices, circuits, methods, and functions described in conjunction with the aspects disclosed herein may be implemented by electronic hardware (e.g., digital implementations, analog implementations, or a combination of both), firmware, various forms of programs or design codes containing instructions (for convenience, may be referred to herein as "software" or "software modules"), or any combination of these technologies.

[0137] In order to clearly illustrate this interchangeability of hardware, firmware and software, various illustrative components, blocks, modules, circuits and steps have been generally described above with respect to their functions. Whether such functions are implemented as hardware, firmware or software or a combination of these technologies depends on the specific application and design constraints imposed on the entire system. A skilled technician can implement the described functions in various ways for each specific application, but such implementation decisions will not result in deviations from the scope of this disclosure. According to various embodiments, processors, devices, components, circuits, structures, machines, modules, etc. may be configured to perform one or more functions described herein. The terms "configured to" or "configured for" used herein with respect to a specified operation or function refer to a processor, device, component, circuit, structure, machine, module, etc. that is physically constructed, programmed and / or arranged to perform a specified operation or function.

[0138] In addition, it will be understood by those of ordinary skill in the art that the various illustrative logic blocks, modules, devices, components, and circuits described herein may be implemented or performed within an integrated circuit (IC), which may include a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device, or any combination thereof. The logic blocks, modules, and circuits may also include antennas and / or transceivers to communicate with various components within a network or within a device. A general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor), multiple microprocessors, one or more microprocessors combined with a DSP core, or any other suitable configuration for performing the functions described herein.

[0139] If implemented in software, these functions can be stored as one or more instructions or codes on a computer-readable medium. Therefore, the steps of the method or algorithm disclosed herein can be implemented as software stored on a computer-readable medium. Computer-readable media include computer storage media and communication media, which include any media that can be enabled to transfer a computer program or code from one place to another. The storage medium can be any available medium that a computer can access. As an example and not limitation, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to store the desired program code in the form of instructions or data structures and can be accessed by a computer.

[0140] In this application, the term "module" as used herein refers to software, firmware, hardware, and any combination of these elements for performing the relevant functions described herein. In addition, for the purpose of discussion, various units are described as discrete modules; however, as is apparent to those of ordinary skill in the art, two or more modules can be combined to form a single module that performs the relevant functions according to the embodiments of the present disclosure.

[0141] In addition, in the embodiments of the present disclosure, memory or other memory and communication components may be used. It should be understood that, for the sake of clarity, the above description describes the embodiments of the present disclosure with reference to different functional units and processors. However, it is apparent that any appropriate functional distribution between different functional units, processing logic elements or domains may be used without departing from the present disclosure. For example, the functions illustrated as being performed by a separate processing logic element or controller may be performed by the same processing logic element or controller. Therefore, references to specific functional units are merely references to appropriate devices for providing the functions, rather than indicating a strict logical or physical structure or organization.

[0142] Various modifications to the embodiments described in this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the embodiments shown herein, but is to be accorded the broadest scope consistent with the novel features and principles disclosed herein, as described in the following claims.

Claims

1. A method performed by a wireless communication device, the method comprising: generating a pilot signal occupying N symbol resources, wherein the pilot signal includes at least one reference signal (RS) port determined from a predetermined RS port pool, wherein the predetermined pool includes at least N RS ports, wherein N is an integer greater than 1; and transmitting a signal including the pilot signal to a wireless communication node; The signal further comprises a data payload, wherein the data payload comprises information related to the pilot signal comprising at least one RS port.

2. The method according to claim 1, wherein: The pilot signal includes W RS ports, each RS port is independently selected or determined from a predetermined RS port pool; and W is an integer greater than 1.

3. The method according to claim 2, wherein: W=2, W=3 or W=4.

4. The method according to claim 1, wherein: Each RS port in the predetermined pool has Nz non-zero elements; and Nz is an integer greater than 0 and less than 4.

5. The method according to claim 1, wherein: Each RS port in the predetermined pool has Nz non-zero elements; Nz is an integer greater than 0 and less than 9; and The Nz non-zero elements of each RS port in the predetermined pool are adjacent in the time domain and / or the frequency domain.

6. The method according to claim 1, wherein: Each RS port in the predetermined pool has Nz non-zero elements; Nz is an integer greater than 0 and less than 9; and The Nz non-zero elements of each RS port in the predetermined pool are used to estimate a channel value for the entire transmission bandwidth experienced by signals transmitted by the wireless communication device.

7. The method according to claim 1, wherein: The predetermined RS port pool is at least one of the following: a receive beam-sensing reference signal port pool; and Receive beam estimation reference signal port pool.

8. The method according to claim 1, wherein: The signal is transmitted to the wireless communication node via a contention-based unlicensed uplink transmission mode or via a semi-persistent scheduling-based unlicensed uplink transmission mode.

9. The method according to claim 1, wherein: The at least one RS port is selected from the predetermined pool based on at least one bit in the data payload.

10. The method according to claim 1, wherein: The data payload is used to perform blind channel equalization and / or blind time-frequency offset correction at the wireless communication node.

11. The method according to claim 1, wherein: The pilot signal is used to perform receive beamforming or spatial combining at the wireless communication node.

12. The method according to claim 1, wherein: The predetermined pool has exactly N RS ports generated based on a plurality of orthogonal cover codes or a plurality of orthogonal sequences.

13. The method according to claim 1, wherein: The predetermined pool has more than N RS ports generated based on a plurality of non-orthogonal sequences.

14. The method according to claim 13, wherein: The predetermined pool has k*N RS ports generated based on a plurality of non-orthogonal sequences, wherein k=2, k=3, k=4, k=8 or k=16.

15. A method performed by a wireless communication device, the method comprising: generating a pilot signal, the pilot signal comprising at least one reference signal (RS) port determined from a predetermined RS port pool, wherein each RS port in the predetermined pool has at most two non-zero elements; and transmitting a signal including the pilot signal to a wireless communication node, wherein the signal also includes a data payload; and The data payload includes information related to the pilot signal including at least one RS port.

16. The method of claim 15, wherein: The pilot signal includes W RS ports, each RS port is independently selected or determined from the predetermined RS port pool; and W is an integer greater than 1.

17. The method according to claim 15, wherein: The at least one RS port is selected from the predetermined pool based on at least one bit in the data payload.

18. A method performed by a wireless communication device, the method comprising: generating a pilot signal occupying N symbol resources, wherein the pilot signal comprises at least one reference signal (RS) port determined from a predetermined RS port pool, wherein each RS port in the predetermined pool has Nz non-zero elements, wherein N is an integer greater than 24, and wherein Nz is an integer greater than 0 and less than 9; and transmitting a signal including the pilot signal to a wireless communication node, The signal further comprises a data payload, wherein the data payload comprises information related to the pilot signal comprising at least one RS port.

19. The method according to claim 18, wherein: The pilot signal includes W RS ports, each RS port is independently selected or determined from a predetermined RS port pool; and W is an integer greater than 1.

20. The method according to claim 18, wherein: The Nz non-zero elements of each RS port in the predetermined pool are adjacent in the time domain and / or the frequency domain.

21. The method according to claim 18, wherein: The Nz non-zero elements of each RS port in the predetermined pool are used to estimate a channel value for the entire transmission bandwidth experienced by signals transmitted by the wireless communication device.

22. The method of claim 18, wherein: The at least one RS port is selected from the predetermined pool based on at least one bit in the data payload.

23. A method performed by a wireless communication node, the method comprising: A signal including a pilot signal is received from a wireless communication device, wherein The pilot signal occupies N symbol resources. The pilot signal includes at least one reference signal (RS) port determined from a predetermined RS port pool, The predetermined pool includes at least N RS ports, and N is an integer greater than 1, The signal further comprises a data payload, wherein the data payload comprises information related to the pilot signal comprising at least one RS port.

24. The method of claim 23, wherein: The pilot signal includes W RS ports, each RS port is independently selected or determined from a predetermined RS port pool; and W is an integer greater than 1.

25. The method according to claim 24, wherein: W=2, W=3 or W=4.

26. The method of claim 23, wherein: Each RS port in the predetermined pool has Nz non-zero elements; and Nz is an integer greater than 0 and less than 4.

27. The method of claim 23, wherein: Each RS port in the predetermined pool has Nz non-zero elements; Nz is an integer greater than 0 and less than 9; and The Nz non-zero elements of each RS port in the predetermined pool are adjacent in the time domain and / or the frequency domain.

28. The method of claim 23, wherein: Each RS port in the predetermined pool has Nz non-zero elements; Nz is an integer greater than 0 and less than 9; and The method also includes estimating a channel value of an entire transmission bandwidth experienced by signals transmitted by the wireless communication device based on the Nz non-zero elements of each RS port in the predetermined pool.

29. The method of claim 23, wherein: The predetermined RS port pool is at least one of the following: a receive beam-sensing reference signal port pool; and Receive beam estimation reference signal port pool.

30. The method of claim 23, wherein: The signal is received from the wireless communication device via a contention-based unlicensed uplink transmission mode or via a semi-persistent scheduling-based unlicensed uplink transmission mode.

31. The method of claim 23, wherein: The at least one RS port is selected from the predetermined pool based on at least one bit in the data payload.

32. The method of claim 23, further comprising: Blind channel equalization and / or blind time-frequency offset correction are performed based on the data payload.

33. The method of claim 23, further comprising: Performing receive beamforming and / or spatial combining based on the pilot signal to obtain a data signal; and Channel estimation and / or time-frequency offset estimation are performed based on the data signal.

34. The method of claim 23, wherein: The predetermined pool has exactly N RS ports generated based on a plurality of orthogonal cover codes or a plurality of orthogonal sequences.

35. The method of claim 23, wherein: The predetermined pool has more than N RS ports generated based on a plurality of non-orthogonal sequences.

36. The method of claim 35, wherein: The predetermined pool has k*N RS ports generated based on a plurality of non-orthogonal sequences, wherein k=2, k=3, k=4, k=8 or k=16.

37. A method performed by a wireless communication node, the method comprising: A signal including a pilot signal is received from a wireless communication device, wherein The pilot signal includes at least one reference signal (RS) port determined from a predetermined reference signal (RS) port pool, and Each RS port in the predetermined pool has at most two non-zero elements, The signal further comprises a data payload, wherein the data payload comprises information related to the pilot signal comprising at least one RS port.

38. The method of claim 37, wherein: The pilot signal includes W RS ports, each RS port is independently selected or determined from a predetermined RS port pool; and W is an integer greater than 1.

39. The method of claim 37, wherein: The at least one RS port is selected from the predetermined pool based on at least one bit in the data payload.

40. A method performed by a wireless communication node, the method comprising: A signal including a pilot signal is received from a wireless communication device, wherein The pilot signal occupies N symbol resources. The pilot signal includes at least one reference signal (RS) port determined from a predetermined RS port pool, Each RS port in the predetermined pool has Nz non-zero elements, N is an integer greater than 24, and Nz is an integer greater than 0 and less than 9, The signal further comprises a data payload, wherein the data payload comprises information related to the pilot signal comprising at least one RS port.

41. The method of claim 40, wherein: The pilot signal includes W RS ports, each RS port is independently selected or determined from a predetermined RS port pool; and W is an integer greater than 1.

42. The method of claim 40, wherein: The Nz non-zero elements of each RS port in the predetermined pool are adjacent in the time domain and / or the frequency domain.

43. The method of claim 40, further comprising: A channel value of the entire transmission bandwidth experienced by signals transmitted by the wireless communication device is estimated based on the Nz non-zero elements of each RS port in the predetermined pool.

44. The method of claim 40, wherein: The at least one RS port is selected from the predetermined pool based on at least one bit in the data payload.

45. A wireless communication device comprising a processor configured to perform the method of any one of claims 1 to 22.

46. ​​A wireless communication node comprising a processor configured to perform the method of any one of claims 23 to 44.

47. A non-transitory computer readable medium having computer executable instructions stored thereon for performing the method of any one of claims 1 to 44.

Images