CN116470986A

CN116470986A - Method, device and system for determining transmission mode

Info

Publication number: CN116470986A
Application number: CN202210027105.0A
Authority: CN
Inventors: 王婷; 金石; 孙欢; 周星宇; 刘永; 张静
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2022-01-11
Filing date: 2022-01-11
Publication date: 2023-07-21

Abstract

The application provides a method, a device and a system for determining a transmission mode, wherein the method comprises the following steps: determining an orthogonal frequency division multiplexing, OFDM, transmission mode from among candidate transmission modes, the candidate transmission modes comprising a first mode in which the OFDM signal comprises a cyclic prefix and a second mode in which the OFDM signal does not comprise a cyclic prefix; an OFDM signal is received according to the OFDM transmission mode. The method, the device and the system for determining the transmission mode support the switching between the Full-CP mode and the CP-free mode, so that the communication system has good spectrum efficiency, and can ensure higher signal detection performance, thereby improving the capacity of the communication system.

Description

Method, device and system for determining transmission mode

Technical Field

The present invention relates to the field of communications, and in particular, to a method, apparatus, and system for determining a transmission mode.

Background

MIMO-OFDM technology, which combines multiple-input multiple-out (MIMO) with orthogonal frequency division multiplexing (orthogonal frequency division multiplexing, OFDM), is one of the most promising technologies to improve wireless link throughput. In a multipath channel environment, the transmitted signal will experience multiple paths with different delays, creating inter-symbol interference (inter-symbol interference, ISI) and inter-carrier interference (inter-carrier interference, ICI) at the first communication device. The cyclic prefix is inserted before the OFDM symbol, so that the function of a guard interval is realized, and the linear convolution is converted into the cyclic convolution, so that ISI and ICI can be obviously reduced. Theoretically, the cyclic prefix length is at least equal to the delay spread of the channel to sufficiently cancel the ISI and ICI effects. However, with the vigorous development of the internet of things (Internet of things, ioT), massive data will be generated in wireless transmission, and the time-delay sensitive application scenario will increase exponentially, so it is urgent to shorten the OFDM frame length, reduce the system delay, and improve the frequency band utilization, which is constrained by the cyclic prefix. However, the lack of cyclic prefix would subject the MIMO-OFDM system to severe ISI and ICI, degrading the performance of signal detection, and further making the communication system capacity low.

Therefore, a method, apparatus and system for determining a transmission mode that can achieve both system spectrum efficiency and signal detection performance are needed to be developed.

Disclosure of Invention

The method, the device and the system for determining the transmission mode support the switching of the mode for transmitting the OFDM symbol between a Full-CP mode with sufficient cyclic prefix and a CP-free mode without cyclic prefix, so that the method, the device and the system can give consideration to good spectrum efficiency and signal detection performance of a communication system, and are beneficial to improving the capacity of the communication system.

In a first aspect, a method of determining a transmission mode is provided, which may be performed by a terminal device or may also be performed by a network device. The method may be performed by a component (e.g., a chip or a chip system, etc.) configured in the terminal device, or may be performed by a component (e.g., a chip or a chip system, etc.) configured in the network device, for example. The following description is made with respect to an example of execution of the first communication device that receives OFDM signals.

The method may include: determining an orthogonal frequency division multiplexing, OFDM, transmission mode from among candidate transmission modes, the candidate transmission modes comprising a first mode in which the OFDM signal comprises a cyclic prefix and a second mode in which the OFDM signal does not comprise a cyclic prefix; an OFDM signal is received according to the OFDM transmission mode.

In some possible implementations, in the first mode, the OFDM signal contains sufficient cyclic prefix; alternatively, only a portion of the cyclic prefix is included, as this application is not specifically limited. Illustratively, in the first mode, the length of the cyclic prefix may be a length designed according to a delay spread, or may be a length determined in other manners.

Further, in the first mode, the length of the cyclic prefix of the OFDM signal may be varied. In some possible implementations, determining the OFDM transmission mode includes determining a length of a cyclic prefix of the OFDM signal.

In the above technical solution, the first communication device may select a suitable transmission mode from the first mode and the second mode to transmit data or a channel, so that the communication system can have good spectrum efficiency, and meanwhile, ensure higher signal detection performance, thereby improving the capacity of the communication system.

With reference to the first aspect, in certain implementations of the first aspect, the method further includes: determining a mode parameter, the mode parameter being used to determine a switching boundary of the OFDM transmission mode; determining channel environment information; the determining an OFDM transmission mode from the candidate transmission modes includes: the OFDM transmission mode is determined from the candidate transmission modes based on the mode parameters and channel environment information.

In some possible implementations, the above-mentioned channel environment information may be determined by the first communication device detecting the channel environment at the beginning of each time slot, for example, may be determined by detecting the channel environment according to the demodulation reference signal DMRS, which is not limited in this application specifically.

In some possible implementations, the switching boundary of the OFDM transmission mode may be a signal-to-noise ratio SNR value, which is included in the mode parameter. The mode parameter may be transmitted by the second communication device or may be predefined by the second communication device and the first communication device according to a protocol, which is not specifically limited in this application.

In the above technical solution, the first communication device determines whether to use a required OFDM transmission mode according to the channel environment information, and uses different OFDM transmission modes in different channel environments, so that it is able to ensure that higher spectrum efficiency and higher signal detection performance are both considered in the operation process of the communication system.

With reference to the first aspect, in certain implementation manners of the first aspect, the mode parameter is a relationship between a first parameter and a switching boundary of the OFDM transmission mode, where the first parameter includes at least one of: scene, modulation mode, antenna configuration, data stream number, channel space correlation coefficient, service type.

In the above technical solution, the first communication device may determine a required OFDM transmission mode according to the first parameter, and may use different OFDM transmission modes under different first parameters, so as to ensure that higher spectral efficiency and higher signal detection performance are both considered in the operation process of the communication system.

In some possible implementations, the relationship between the first parameter and the OFDM transmission mode switching boundary is predetermined. Illustratively, the OFDM handoff boundary is determined based on spectral efficiency, block error rate, and bit error rate of the communication system when operating in the first mode and the second mode, respectively.

With reference to the first aspect, in certain implementations of the first aspect, the method further includes: receiving first information, wherein the first information is used for indicating the candidate transmission modes supported by different area positions; the OFDM transmission mode is determined based on the first information.

Illustratively, the first information may indicate that a region supports the first mode; alternatively, a region supports the second mode; or indicate that a region supports a first mode and a second mode switch. It should be appreciated that when the first information indicates that a region supports the first mode and the second mode switching, and when the first communication device is located in the region supporting the first mode and the second mode switching, the first communication device further needs to determine a mode parameter, and further determines the OFDM transmission mode according to the channel environment information and the mode parameter.

In some possible implementations, the first information may be PBCH/SIB system broadcast signaling or common RRC signaling; alternatively, the first information is group downlink control information (downlink control information, DCI); alternatively, the first information is DCI or RRC signaling; alternatively, the first information may be other information, which is not specifically limited in this application.

In some possible implementations, the first communication device determines a region in which to locate, and further determines the OFDM transmission mode based on the received first information. Alternatively, the first communication device may determine the area according to the location information, or may determine the area according to the indication information of the second communication device.

In the above technical solution, the first communication device determines, according to the first information, an OFDM transmission mode supported by the area, and when the area supports only one OFDM transmission mode, no additional signaling interaction is required, so that signaling overhead can be reduced, and further communication performance is improved.

With reference to the first aspect, in certain implementations of the first aspect, the method further includes: the mode parameter is determined from predefined transmission scheme information comprising a relation between a switching boundary of the OFDM transmission mode predefined by a protocol and the first parameter.

In the technical scheme, the OFDM transmission scheme is determined in a protocol predefined mode, so that signaling overhead can be reduced, and further communication performance is improved.

With reference to the first aspect, in certain implementations of the first aspect, the method further includes: the channel environment information comprises a received signal-to-noise ratio, the mode parameter comprises a signal-to-noise ratio (SNR) switching boundary, the OFDM transmission mode is determined from the candidate transmission modes according to the mode parameter and the channel environment information, and when the received signal-to-noise ratio is smaller than the SNR switching boundary, the OFDM transmission mode is determined to be the first mode; and when the received signal-to-noise ratio is greater than or equal to the SNR switching boundary, determining the OFDM transmission mode as the second mode.

With reference to the first aspect, in certain implementations of the first aspect, the method further includes: and sending first indication information, wherein the first indication information is used for indicating the OFDM transmission mode.

In some possible implementations, after the first communication device acknowledges the OFDM transmission mode, it is necessary to instruct the second communication device to transmit an OFDM signal using the OFDM transmission mode. Illustratively, the first communication device transmits the first indication information after making the channel state information CSI measurement; alternatively, the first communication device may send the first indication information after receiving the downlink data sent by the second network device and after sending the HARQ-ACK, which is not specifically limited in this application. For example, the first indication information may be a one-bit air interface indication signal, and when the one-bit air interface indication signal is 1, the OFDM transmission mode is indicated as a first mode; when the one-bit null indication signal is 0, the OFDM transmission mode is indicated as a second mode. Alternatively, the first indication information may be in other forms, which is not specifically limited in this application.

With reference to the first aspect, in certain implementations of the first aspect, the first indication information is transmitted in combination with CSI feedback information or HARQ-ACK information.

In the technical scheme, the joint transmission of the first indication information and the CSI feedback information or the HARQ-ACK information can reduce signaling overhead, reduce indication time delay and feedback time delay and improve communication performance.

With reference to the first aspect, in certain implementations of the first aspect, the method further includes: transmitting second information, wherein the second information is used for indicating capability information, and the capability information comprises at least one of the following items: the first mode is supported, the second mode is not supported, the first mode and the second mode are supported, or the first mode is supported and the second mode is not supported.

In the above technical solution, the OFDM signal receiving end sends capability indication information to the OFDM signal transmitting end, so as to suggest what OFDM transmission mode the OFDM signal transmitting end adopts, so that the processing complexity of the OFDM signal receiving end can be reduced, and the capability conditions of different terminals are considered, so that the system performance and complexity are balanced.

With reference to the first aspect, in certain implementations of the first aspect, the method further includes: when the OFDM transmission mode is the first mode, after receiving an OFDM signal, removing a cyclic prefix in the OFDM signal, transforming a time domain symbol into a frequency domain symbol through Fourier transformation, and determining a real-value frequency domain channel matrix and a real-value frequency domain symbol vector of the frequency domain symbol; and according to the real-value frequency domain channel matrix and the real-value frequency domain symbol vector, performing the signal detection on the OFDM signal by using a depth neural network determined based on a conjugate gradient iteration method.

With reference to the first aspect, in certain implementations of the first aspect, the method further includes: when the OFDM transmission mode is the first mode, after receiving an OFDM signal, eliminating inter-symbol interference in the OFDM signal according to an estimated value of a symbol vector sent in the last symbol time, and determining a real-value time domain symbol vector and a real-value time domain channel matrix of the OFDM symbol; and according to the real-value time domain symbol vector and the real-value time domain channel matrix, performing the signal detection on the OFDM symbol by using a depth neural network determined based on a conjugate gradient iteration method.

In the technical scheme, the depth neural network is constructed by using the conjugate gradient algorithm to detect the OFDM signal, so that complex direct matrix inversion is avoided, and the running time can be reduced.

With reference to the first aspect, in certain implementations of the first aspect, the method further includes: the solution vector of the real-value noise vector is determined by utilizing the conjugate gradient method iteration solution, and the decorrelation coefficient is determined according to the real-value frequency domain channel matrix; calculating an outward mean value vector and an error variance according to the solution vector and the decorrelation coefficient, wherein the update step sizes of the outward mean value vector and the error variance are respectively adjusted by a second parameter and a third parameter; and calculating an estimated value of the symbol vector by using a non-divergence nonlinear function according to the outward mean value vector and the error variance, wherein a non-divergence characteristic of the non-divergence nonlinear function is adjusted by a fourth parameter and a fifth parameter.

In the above technical solution, based on the adjustable parameters of each layer: the second parameter, the third parameter, the fourth parameter and the fifth parameter can reduce the cost required for training the neural network, so that the method for determining the transmission mode has the advantages of being strong in generalization and capable of being deployed quickly.

With reference to the first aspect, in certain implementations of the first aspect, the method further includes: and calculating a first estimation error variance according to the estimation value of the symbol vector, and determining an estimation error variance according to the first estimation error variance and a second estimation error variance transmitted by a previous layer of sub-network, wherein the estimation error variance is used for calculating a solution vector of a real-valued noise vector of a next layer of sub-network.

In the above technical solution, the stability of the signal detection network can be enhanced by performing convex linear combination on the updated error variance and the numerical value transmitted by the previous layer of sub-network and limiting the minimum value of the output variance.

In a second aspect, a method of determining a transmission mode is provided, which may be performed by a terminal device or may also be performed by a network device. The method may be performed by a component (e.g., a chip or a chip system, etc.) configured in the terminal device, or may be performed by a component (e.g., a chip or a chip system, etc.) configured in the network device, for example. The following description will be made with a second communication device that transmits OFDM signals as an example.

The method may include: determining an orthogonal frequency division multiplexing, OFDM, transmission mode from among candidate transmission modes, the candidate transmission modes including a first mode and a second mode; wherein in the first mode, the OFDM signal includes a cyclic prefix; in the second mode, the OFDM signal does not include a cyclic prefix; and transmitting the OFDM signal according to the OFDM transmission mode.

With reference to the second aspect, in certain implementations of the second aspect, the method further includes: receiving third information, and determining the OFDM transmission mode from the candidate transmission modes according to the third information; wherein the third information is used for indicating that the OFDM transmission mode is the first mode or the second mode; alternatively, the third information is used to indicate the received signal-to-noise ratio of the channel.

In some possible implementations, the first communication device, that is, the OFDM signal receiving end indicates or suggests an OFDM transmission mode, the third information may be the first indication information, or the second information, or other information capable of indicating the OFDM transmission mode, which is not specifically limited in this application.

In some possible implementations, the second communication device, that is, the OFDM signal transmitting end indicates an OFDM transmission mode, or the OFDM transmission mode is predefined by a protocol, the third information needs to include a received signal-to-noise ratio of the channel, so that the second communication device determines the OFDM transmission mode according to the received signal-to-noise ratio of the channel and the OFDM transmission mode switching boundary.

With reference to the second aspect, in certain implementations of the second aspect, the method further includes: when the third information is used for indicating the received signal-to-noise ratio, determining the OFDM transmission mode from the candidate transmission modes according to the received signal-to-noise ratio and a mode parameter, wherein the mode parameter is used for indicating a switching boundary of the OFDM transmission mode.

With reference to the second aspect, in certain implementations of the second aspect, the method further includes: the mode parameter includes a signal-to-noise ratio (SNR) switching boundary, the OFDM transmission mode is determined from the candidate transmission modes according to the received SNR and the mode parameter, and the OFDM transmission mode is determined to be the first mode when the received SNR is smaller than the SNR switching boundary; and when the received signal-to-noise ratio is greater than or equal to the SNR switching boundary, determining the OFDM transmission mode as the second mode.

With reference to the second aspect, in certain implementations of the second aspect, the method further includes: and transmitting second indication information, wherein the second indication information is used for indicating the OFDM transmission mode.

It should be understood that when the second communication device needs to indicate the OFDM transmission mode of the first communication device, the second communication device needs to determine the received signal-to-noise ratio according to the third information, further determine the OFDM transmission mode from the candidate transmission modes according to the received signal-to-noise ratio and the mode parameter, and further indicate the OFDM transmission mode of the first communication device through the second indication information.

With reference to the second aspect, in certain implementations of the second aspect, the method further includes: transmitting fourth information, where the fourth information is used to indicate a switching boundary of the OFDM transmission mode corresponding to a first parameter, and the first parameter includes at least one of: scene, modulation mode, antenna configuration, data stream number, channel space correlation coefficient, service type.

In the above technical solution, the second communication device sends the fourth information, so that the fourth information receiving end can determine the required OFDM transmission mode according to the first parameter, and can use different OFDM transmission modes under different first parameters, so as to ensure that higher spectral efficiency and higher signal detection performance are both considered in the operation process of the communication system.

With reference to the second aspect, in certain implementations of the second aspect, the method further includes: and sending first information, wherein the first information is used for indicating the candidate transmission modes supported by different area positions.

With reference to the second aspect, in certain implementations of the second aspect, the method further includes: receiving second information, the second information being used to indicate capability information, the capability information comprising at least one of: support the first mode, support the second mode, support the first mode and the second mode, or support the first mode and not support the second mode; the OFDM transmission mode is determined based on the second information.

In the above technical solution, the OFDM signal transmitting end receives the capability indication information, so as to determine what OFDM transmission mode is adopted according to the capability indication information, so that the system performance and complexity can be balanced.

In a third aspect, an apparatus for determining a transmission mode is provided, the apparatus may include: a processing unit for orthogonal frequency division multiplexing, OFDM, transmission modes from among candidate transmission modes, the candidate transmission modes comprising a first mode in which the OFDM signal comprises a cyclic prefix and a second mode in which the OFDM signal does not comprise a cyclic prefix; and the receiving and transmitting unit is used for receiving the OFDM signal according to the OFDM transmission mode.

In the above technical solution, the device may select a suitable transmission mode from the first mode and the second mode to transmit data or a channel, so that the communication system can have good spectrum efficiency, and simultaneously ensure higher signal detection performance, thereby improving the capacity of the communication system.

With reference to the third aspect, in certain implementations of the third aspect, the processing unit is further configured to: determining a mode parameter, the mode parameter being used to determine a switching boundary of the OFDM transmission mode; determining channel environment information; the OFDM transmission mode is determined from the candidate transmission modes based on the mode parameters and channel environment information.

In the technical scheme, the device determines whether the required OFDM transmission mode is needed according to the channel environment information, and different OFDM transmission modes are used under different channel environments, so that the higher frequency spectrum efficiency and higher signal detection performance can be guaranteed in the running process of the communication system.

With reference to the third aspect, in some implementations of the third aspect, the mode parameter is a relationship between a first parameter and a switching boundary of the OFDM transmission mode, where the first parameter includes at least one of: scene, modulation mode, antenna configuration, data stream number, channel space correlation coefficient, service type.

In the above technical scheme, the device can determine the required OFDM transmission mode according to the first parameter, and can use different OFDM transmission modes under different first parameters, so that higher spectrum efficiency and higher signal detection performance can be guaranteed in the running process of the communication system.

With reference to the third aspect, in certain implementations of the third aspect, the transceiver unit is further configured to: receiving first information, wherein the first information is used for indicating the candidate transmission modes supported by different area positions; the processing unit is also configured to determine the OFDM transmission mode based on the first information.

In the technical scheme, the device determines the OFDM transmission mode supported by the area according to the first information, and when the area supports only one OFDM transmission mode, no additional signaling interaction is needed, so that signaling overhead can be reduced, and further communication performance is improved.

With reference to the third aspect, in certain implementations of the third aspect, the processing unit is further configured to: the mode parameter is determined from predefined transmission scheme information comprising a relation between a switching boundary of the OFDM transmission mode predefined by a protocol and the first parameter.

With reference to the third aspect, in certain implementations of the third aspect, the channel environment information includes a received signal-to-noise ratio, the mode parameter includes a signal-to-noise ratio SNR switching boundary, the OFDM transmission mode is determined from the candidate transmission modes according to the mode parameter and the channel environment information, and the processing unit is further configured to: when the received signal-to-noise ratio is smaller than the SNR switching boundary, determining the OFDM transmission mode as the first mode; and when the received signal-to-noise ratio is greater than or equal to the SNR switching boundary, determining the OFDM transmission mode as the second mode.

With reference to the third aspect, in certain implementations of the third aspect, the transceiver unit is further configured to: and sending first indication information, wherein the first indication information is used for indicating the OFDM transmission mode.

With reference to the third aspect, in some implementations of the third aspect, the first indication information is transmitted in combination with CSI feedback information or HARQ-ACK information.

With reference to the third aspect, in certain implementations of the third aspect, the transceiver unit is further configured to: transmitting second information, wherein the second information is used for indicating capability information, and the capability information comprises at least one of the following items: the first mode is supported, the second mode is not supported, the first mode and the second mode are supported, or the first mode is supported and the second mode is not supported.

In the above technical scheme, the device sends the capability indication information to suggest what kind of OFDM transmission mode is adopted by the OFDM signal transmitting end, so that the processing complexity of the OFDM signal receiving end can be reduced, and the capability conditions of different terminals are considered to balance the system performance and complexity.

With reference to the third aspect, in certain implementations of the third aspect, the processing unit is further configured to: when the OFDM transmission mode is the first mode, after receiving an OFDM signal, removing a cyclic prefix in the OFDM signal, transforming a time domain symbol into a frequency domain symbol through Fourier transformation, and determining a real-value frequency domain channel matrix and a real-value frequency domain symbol vector of the frequency domain symbol; and according to the real-value frequency domain channel matrix and the real-value frequency domain symbol vector, performing the signal detection on the OFDM signal by using a depth neural network determined based on a conjugate gradient iteration method.

With reference to the third aspect, in certain implementations of the third aspect, the processing unit is further configured to: when the OFDM transmission mode is the first mode, after receiving an OFDM signal, eliminating inter-symbol interference in the OFDM signal according to an estimated value of a symbol vector sent in the last symbol time, and determining a real-value time domain symbol vector and a real-value time domain channel matrix of the OFDM symbol; and according to the real-value time domain symbol vector and the real-value time domain channel matrix, performing the signal detection on the OFDM symbol by using a depth neural network determined based on a conjugate gradient iteration method.

In the technical scheme, the device utilizes the conjugate gradient algorithm to construct the deep neural network to detect the OFDM signal, so that complex direct matrix inversion is avoided, and the running time can be reduced.

With reference to the third aspect, in certain implementations of the third aspect, the processing unit is further configured to: the solution vector of the real-value noise vector is determined by utilizing the conjugate gradient method iteration solution, and the decorrelation coefficient is determined according to the real-value frequency domain channel matrix; calculating an outward mean value vector and an error variance according to the solution vector and the decorrelation coefficient, wherein the update step sizes of the outward mean value vector and the error variance are respectively adjusted by a second parameter and a third parameter; and calculating an estimated value of the symbol vector by using a non-divergence nonlinear function according to the outward mean value vector and the error variance, wherein a non-divergence characteristic of the non-divergence nonlinear function is adjusted by a fourth parameter and a fifth parameter.

In the above technical solution, the device is based on adjustable parameters of each layer: the second parameter, the third parameter, the fourth parameter and the fifth parameter can reduce the cost required for training the neural network, so that the transmission mode switching method has the advantages of being strong in generalization and capable of being deployed quickly.

With reference to the third aspect, in certain implementations of the third aspect, the processing unit is further configured to: and calculating a first estimation error variance according to the estimation value of the symbol vector, and determining an estimation error variance according to the first estimation error variance and a second estimation error variance transmitted by a previous layer of sub-network, wherein the estimation error variance is used for calculating a solution vector of a real-valued noise vector of a next layer of sub-network.

In the above technical solution, the device can strengthen the stability of the signal detection network by performing convex linear combination on the updated error variance and the numerical value transmitted by the previous layer of sub-network and limiting the minimum value of the output variance.

In a fourth aspect, an apparatus for determining a transmission mode is provided, the apparatus may include: a processing unit for orthogonal frequency division multiplexing, OFDM, transmission modes from among candidate transmission modes, the candidate transmission modes comprising a first mode in which the OFDM signal comprises a cyclic prefix and a second mode in which the OFDM signal does not comprise a cyclic prefix; and the receiving and transmitting unit is used for transmitting the OFDM signal according to the OFDM transmission mode.

With reference to the fourth aspect, in some implementations of the fourth aspect, the transceiver unit is further configured to: receiving third information, and determining the OFDM transmission mode from the candidate transmission modes according to the third information; wherein the third information is used for indicating that the OFDM transmission mode is the first mode or the second mode; alternatively, the third information is used to indicate the received signal-to-noise ratio of the channel.

With reference to the fourth aspect, in certain implementations of the fourth aspect, the processing unit is further configured to: when the third information is used for indicating the received signal-to-noise ratio, determining the OFDM transmission mode from the candidate transmission modes according to the received signal-to-noise ratio and a mode parameter, wherein the mode parameter is used for indicating a switching boundary of the OFDM transmission mode.

With reference to the fourth aspect, in certain implementations of the fourth aspect, the mode parameter includes a signal-to-noise ratio SNR switching boundary, the OFDM transmission mode is determined from the candidate transmission modes according to the received signal-to-noise ratio and the mode parameter, and the processing unit is further configured to: when the received signal-to-noise ratio is smaller than the SNR switching boundary, determining the OFDM transmission mode as the first mode; and when the received signal-to-noise ratio is greater than or equal to the SNR switching boundary, determining the OFDM transmission mode as the second mode.

With reference to the fourth aspect, in some implementations of the fourth aspect, the transceiver unit is further configured to: and transmitting second indication information, wherein the second indication information is used for indicating the OFDM transmission mode.

With reference to the fourth aspect, in some implementations of the fourth aspect, the transceiver unit is further configured to: transmitting fourth information, where the fourth information is used to indicate a switching boundary of the OFDM transmission mode corresponding to a first parameter, and the first parameter includes at least one of: scene, modulation mode, antenna configuration, data stream number, channel space correlation coefficient, service type.

In the above technical scheme, the device sends the fourth information so that the fourth information receiving end can determine the required OFDM transmission mode according to the first parameter, and can use different OFDM transmission modes under different first parameters, so that higher spectrum efficiency and higher signal detection performance can be guaranteed in the running process of the communication system.

With reference to the fourth aspect, in some implementations of the fourth aspect, the transceiver unit is further configured to: and sending first information, wherein the first information is used for indicating the candidate transmission modes supported by different area positions.

With reference to the fourth aspect, in some implementations of the fourth aspect, the transceiver unit is further configured to: receiving second information, the second information being used to indicate capability information, the capability information comprising at least one of: support the first mode, support the second mode, support the first mode and the second mode, or support the first mode and not support the second mode; the OFDM transmission mode is determined based on the second information.

In the above technical scheme, the device receives the capability indication information to determine which OFDM transmission mode is adopted, so that the processing complexity of the OFDM signal receiving end can be reduced, and the system performance and complexity can be balanced.

In a fifth aspect, an apparatus for determining a transmission mode is provided, the apparatus may include: a memory for storing a program; a processor for executing a memory-stored program, which when executed is adapted to carry out the method of any one of the possible implementations of the first to second aspects described above.

In a sixth aspect, a system for determining a transmission mode is provided, the system comprising means for transmitting a message signature as in any of the possible implementations of the third aspect or the third aspect, and means for transmitting a message signature as in any of the possible implementations of the fourth aspect or the fourth aspect.

In a seventh aspect, there is provided a computer program product comprising: computer program code which, when run on a computer, causes the computer to perform the method of any one of the first to second aspects described above as possible.

In an eighth aspect, there is provided a computer readable medium storing program code which, when run on a computer, causes the computer to perform the first and second aspects and any one of the methods of the first and second aspects. These computer-readable stores include, but are not limited to, one or more of the following: read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), flash memory, electrically EPROM (EEPROM), and hard disk drive (hard drive).

In a ninth aspect, a chip is provided, the chip comprising a processor and a data interface, wherein the processor reads instructions stored on a memory via the data interface to perform the method of the first aspect or any one of the possible implementations of the first aspect. In a specific implementation, the chip may be implemented in the form of a central processing unit (central processing unit, CPU), microcontroller (micro controller unit, MCU), microprocessor (micro processing unit, MPU), digital signal processor (digital signal processing, DSP), system on chip (SoC), application-specific integrated circuit (ASIC), field programmable gate array (field programmable gate array, FPGA) or programmable logic device (programmable logic device, PLD).

Drawings

Fig. 1 is a schematic diagram of a communication system according to an embodiment of the present application.

Fig. 2 is a schematic flow chart of a method for determining a transmission mode according to an embodiment of the present application.

Fig. 3 is a schematic diagram of an application scenario of a method for determining a transmission mode according to an embodiment of the present application.

Fig. 4 is a schematic flow chart of a method for determining a transmission mode according to an embodiment of the present application.

Fig. 5 is a schematic diagram of a communication system formed by a transmitting end and a receiving end according to an embodiment of the present application.

Fig. 6 is a schematic flow chart of a method for determining a transmission mode according to an embodiment of the present application.

Fig. 7 is a schematic diagram of a signal detection network according to an embodiment of the present application.

Fig. 8 is a schematic diagram of SNR switching boundaries in a method for determining a transmission mode according to an embodiment of the present application.

Fig. 9 is a further schematic flow chart of a method of determining a transmission mode provided in an embodiment of the present application.

Fig. 10 is a schematic diagram of an RRC signaling configuration terminal device according to an embodiment of the present application.

Fig. 11 is a further schematic flow chart of a method of determining a transmission mode provided in an embodiment of the present application.

Fig. 12 is yet another schematic flow chart of a method of determining a transmission mode provided in an embodiment of the present application.

Fig. 13 is a further schematic flow chart of a method for determining a transmission mode according to an embodiment of the present application.

Fig. 14 is a further schematic flow chart of a method for determining a transmission mode according to an embodiment of the present application.

Fig. 15 is a schematic block diagram of a communication device provided in an embodiment of the present application.

Fig. 16 is yet another schematic block diagram of a communication device provided in an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

Fig. 1 is a schematic diagram of a scenario of a wireless communication system 100 to which embodiments of the present application are applied. The wireless communication system 100 may include a network device 110. Network device 110 may be a device that communicates with terminal device 120. Network device 110 may provide communication coverage for a particular geographic area and may communicate with terminal devices located within the coverage area.

Fig. 1 illustrates one network device 110 and one terminal device 120 by way of example, and the wireless communication system 100 may alternatively include multiple network devices 110 and may include other numbers of terminal devices 120 within the coverage area of each network device 110, as embodiments of the present application are not limited in this regard.

It should be noted that, the two side entities for communication in the embodiment of the present application may be the network device 110 and the terminal device 120, or may also be the network device 110 and the network device 110, or may also be the terminal device 120 and the terminal device 120, or may also be other entities with communication capabilities, which is not limited in this application specifically.

Optionally, the wireless communication system 100 may further include a network controller, a mobility management entity, and other network entities, which are not limited in this embodiment of the present application.

It should be understood that the technical solution of the embodiments of the present application may be applied to various communication systems, for example: global system for mobile communications (global system of mobile communication, GSM), code division multiple access (code division multiple access, CDMA) system, wideband code division multiple access (wideband code division multiple access, WCDMA) system, general packet radio service (general packet radio service, GPRS), long term evolution (Long Term Evolution, LTE) system, LTE frequency division duplex (frequency division duplex, FDD) system, LTE time division duplex (Time Division Duplex, TDD), universal mobile telecommunications system (universal mobile telecommunication system, UMTS), worldwide interoperability for microwave access (worldwide interoperability for microwave access, wiMAX) communication system, access backhaul integrated (integrated access and backhaul, IAB) communication system, satellite inter-satellite link communication system, future fifth generation (5th generation,5G) mobile communication system or New Radio (NR) or future sixth generation (6th generation,6G) mobile communication system, and the like.

The type of the terminal device in the embodiments of the present application is not particularly limited, for example, the terminal device (UE) may be a wireless terminal device capable of receiving the scheduling and indication information of the network device, and the wireless terminal device may be a device that provides voice and/or data connectivity to the user, or a handheld device with a wireless connection function, or other processing device connected to a wireless modem. The wireless terminal device may communicate with one or more core networks or the internet via a radio access network (e.g., radio access network, RAN), which may be a mobile terminal device such as a mobile phone (or "cellular" phone), a computer, and a data card, e.g., a portable, pocket, hand-held, computer-built-in, or vehicle-mounted mobile device that exchanges voice and/or data with the radio access network. Such as personal communication services (personal communication service, PCS) phones, cordless phones, session Initiation Protocol (SIP) phones, wireless local loop (wireless local loop, WLL) stations, personal digital assistants (personal digital assistant, PDAs), tablet computers (Pad), computers with wireless transceiver capabilities, and the like. The wireless terminal device may also be referred to as a system, subscriber unit (subscriber unit), subscriber station (subscriber station), mobile Station (MS), remote station (AP), access Point (AP), remote terminal device (remote), access terminal device (access terminal), user terminal device (user terminal), user agent (user agent), user station (subscriber station, SS), user equipment (customer premises equipment, CPE), terminal (terminal), user Equipment (UE), mobile Terminal (MT), etc. The wireless terminal device may also be a wearable device as well as a next generation communication system, e.g. a terminal device in a 5G network or a terminal device in a future evolved public land mobile network (public land mobile network, PLMN) network, a terminal device in an NR communication system, etc.

By way of example, and not limitation, in embodiments of the present application, the terminal device may also be a wearable device. The wearable device can also be called as a wearable intelligent device, and is a generic name for intelligently designing daily wear by applying wearable technology and developing wearable devices, such as glasses, gloves, watches, clothes, shoes and the like. The wearable device is a portable device that is worn directly on the body or integrated into the clothing or accessories of the user. The wearable device is not only a hardware device, but also can realize a powerful function through software support, data interaction and cloud interaction. The generalized wearable intelligent device includes full functionality, large size, and may not rely on the smart phone to implement complete or partial functionality, such as: smart watches or smart glasses, etc., and focus on only certain types of application functions, and need to be used in combination with other devices, such as smart phones, for example, various smart bracelets, smart jewelry, etc. for physical sign monitoring.

The type of the network device in the embodiment of the present application is not particularly limited, and is, for example, a new generation base station (generation Node B, gmodeb). The network device may be a device for communicating with a mobile device. The network device may be an AP in a wireless local area network (wireless local area networks, WLAN), a base station (base transceiver station, BTS) in a global system for mobile communications (global system for mobile communication, GSM) or code division multiple access (code division multiple access, CDMA), a base station (NodeB, NB) in wideband code division multiple access (wideband code division multiple access, WCDMA), an evolved base station (evolutional Node B, eNB or eNodeB) in long term evolution (long term evolution, LTE), or a relay station or access point, or a vehicle device, a wearable device, and a network device in a future 5G network or a network device in a future evolved public land mobile network (public land mobile network, PLMN) network, or a gndeb in an NR system, etc. In addition, in the embodiment of the present application, the network device provides a service for a cell, where the terminal device communicates with the network device through a transmission resource (for example, a frequency domain resource, or a spectrum resource) used by the cell, where the cell may be a cell corresponding to the network device (for example, a base station), and the cell may belong to a macro base station, or may belong to a base station corresponding to a small cell (small cell), where the small cell may include: urban cells (Metro cells), micro cells (Micro cells), pico cells (Pico cells), femto cells (Femto cells) and the like, and the small cells have the characteristics of small coverage area and low transmitting power and are suitable for providing high-rate data transmission services. Furthermore, the network device may be other means of providing wireless communication functionality for the terminal device, as other possibilities. The embodiment of the application does not limit the specific technology and the specific device form adopted by the network device. For convenience of description, in the embodiments of the present application, an apparatus that provides a wireless communication function for a terminal device is referred to as a network device.

The communication system may be a 5G NR system, or may be a satellite communication system, an inter-satellite link communication system, or the like. The embodiment of the application can also be applied to other communication systems as long as the entity in the communication system needs to send the transmission direction indication information, and the other entity needs to receive the indication information and determine the transmission direction in a certain time according to the indication information. Illustratively, as shown in fig. 1, a network device 110 and a terminal device 120 constitute a communication system. In the communication system, the terminal device 120 may transmit uplink data to the network device 110, and the network device 110 receives the uplink data transmitted by the terminal device 120. The network device 110 may also send downlink data to the terminal device 120, where the terminal device 120 receives the downlink data. The data may be generalized data, such as user data, system information, broadcast information, control information, feedback information, or other information, for example. The data is illustratively data carried on the PDSCH.

As a possible way, the network device may be constituted by a Centralized Unit (CU) and a Distributed Unit (DU). One CU may be connected to one DU, or one CU may be shared by a plurality of DUs, which may save costs and facilitate network expansion. The splitting of CUs and DUs may be in terms of protocol stack splitting, with one possible way being to deploy radio resource control (radio resource control, RRC), service data mapping protocol stack (service data adaptation protocol, SDAP) and packet data convergence protocol (packet data convergence protocol, PDCP) layers at the CUs and the remaining radio link control (radio link control, RLC), medium access control (media access control, MAC) and physical layers at the DUs.

In addition, in the embodiment of the present application, the network device provides services for the cell, and the terminal device communicates with the network device through the transmission resources (for example, frequency domain resources, or spectrum resources) used by the cell. The cell may be a cell corresponding to a network device (e.g., a base station), where the cell may belong to a macro base station or may belong to a base station corresponding to a small cell (small cell), where the small cell may include: urban cells (Metro cells), micro cells (Micro cells), pico cells (Pico cells), femto cells (Femto cells) and the like, and the small cells have the characteristics of small coverage area and low transmitting power and are suitable for providing high-rate data transmission services.

Illustratively, in a cell, network device 110 and terminal device 120 may transmit data over air interface resources. The air interface resources may include time domain resources and frequency domain resources, which may also be referred to as time-frequency resources. The frequency domain resource may be located in a set frequency range, which may also be referred to as a band (band) or a frequency band, and the width of the frequency domain resource may be referred to as a Bandwidth (BW).

The time-frequency resource may specifically be a resource grid, including a time domain and a frequency domain, for example, the time domain unit may be a symbol (symbol), the frequency domain unit may be a subcarrier (subcarrier), and the smallest resource unit in the resource grid may be referred to as a Resource Element (RE). One Resource Block (RB) may include one or more subcarriers in the frequency domain, for example, may be 12 subcarriers. One slot may include one or more symbols in a time domain, and illustratively, one slot may include 14 symbols under a common Cyclic Prefix (CP); under the extended cyclic prefix, one slot may include 12 symbols.

In a wireless communication system, for example, in an OFDM-based communication system, one resource grid includes X1 subcarriers in the frequency domain, and X1 is an integer of 1 or more. Illustratively, X1 is a multiple of 12. In general, the X1 subcarriers may be numbered in the direction of increasing frequency. In the time domain, one resource grid includes X2 symbols, and X2 is an integer greater than or equal to 1. Illustratively, X2 is 7 or 14. In general, the X2 symbols may be numbered in the direction of time domain increase. In the resource grid, one subcarrier and one symbol uniquely identify one RE, and an index corresponding to one RE may be denoted as (k, l), where k represents a subcarrier index and l represents a symbol index. The complex values transmitted over the resource elements (k, l) can be noted asWhere p is the antenna port number.

In NR, various frame structures (which may include various subcarrier spacings) are introduced, so that a resource grid (resource grid) may be defined for each frame structure parameter. The method comprises the following steps:

for each subcarrier spacing and carrier, the defined resource grid includesSub-carriers and method for forming the sameAnd OFDM symbols. Wherein (1) >Refers to the size of the resource grid or may refer to the number of RBs included. Mu represents subcarrier spacing configuration, and subscript x represents downlink or uplink data transmission mode. Illustratively, one resource grid may include X3 physical resource blocks (physical resource block, PRBs), X3 being an integer greater than or equal to 1. In some possible implementations, each PRB may be numbered sequentially from 0 to X3-1 based on the direction of the frequency increase, resulting in a number value for each RB. In the present embodiments, the term "number value" may also be referred to as "identification" or "index".

Refers to the number of subcarriers included in each resource block. />Refers to the number of symbols included in each subframe in the subcarrier spacing configuration μ. Further, a subframe may include a plurality of slots (slots). Illustratively, the->Refers to the number of slots included in each subframe in the subcarrier spacing configuration μ. />Refers to the number of symbols contained in each slot.

For one subcarrier spacing (numerology) and one carrier, a resource grid may be defined in the carrier, wherein a starting position of the resource grid in the carrier or a starting position of a first subcarrier in the resource grid in the carrier is The value may be indicated by higher layer signaling. In some possible implementations, various subcarrier spacings (numerologies) may be described as frame structure parameters, which may include subcarrier spacings and/or CPs, for example, table 1 shows frame structure parameters supported in NR:

frame structure parameters supported by table 1 NR

μ	Δf＝2 ^μ ·15[kHz]	CP
			0	15	General
1	30	General
			2	60	General, extension
3	120	General
			4	240	General

The CP length is as followsWhere l denotes a symbol and μ denotes a subcarrier spacing.

The communication between the network device and the terminal device is described in detail below based on the wireless communication system shown in fig. 1. In a wireless communication system, when a network device and a terminal device perform data transmission, the network device may schedule the terminal device, and the network device may allocate, for the terminal device, frequency domain resources and/or time domain resources of a data channel such as a physical downlink shared channel (physical downlink shared channel, PDSCH) or a physical uplink shared channel (physical uplink shared channel, PUSCH) from a resource grid through control information, where the control information may indicate, for example, symbols and/or RBs to which the data channel is mapped, and the network device and the terminal device perform data transmission on the allocated time-frequency resources through the data channel.

As described above, the cyclic prefix is inserted before the OFDM symbol, although it can function as a guard interval, and ISI and ICI can be significantly reduced. However, inserting redundant cyclic prefixes severely limits the spectral efficiency of the system. In addition, the multiplication of the number of antennas places additional stress on the receiver signal detection strategy. However, the absence of cyclic prefix will bring about severe ISI and ICI, deteriorating the performance of signal detection. The conventional scheme is to use complex equalization to compensate the loss caused by insufficient CP length, and to increase the complexity of the system to obtain the improvement of the spectrum efficiency, and the combination of MIMO and OFDM further complicates the design of the system.

In view of this, in order to achieve both the spectrum efficiency and the signal detection performance of the communication system, the embodiments of the present application provide a method, an apparatus, and a system for switching OFDM transmission modes, which support switching between a cyclic prefix (CP-free) mode and a Full-CP mode, and can determine the OFDM transmission mode according to different scenarios/requirements, thereby reducing CP overhead and guaranteeing a good compromise between the spectrum efficiency and the signal detection performance of the system.

The present application will present various aspects, embodiments, or features about a system comprising a plurality of devices, components, modules, etc. It is to be understood and appreciated that the various systems may include additional devices, components, modules, etc. and/or may not include all of the devices, components, modules etc. discussed in connection with the figures. Furthermore, combinations of these schemes may also be used. A method for determining a transmission mode according to an embodiment of the present application is described in detail below with reference to an application scenario of fig. 1.

Fig. 2 is a schematic flowchart of a method 200 for determining a transmission mode according to an embodiment of the present application. It should be understood that the steps or operations of the method for determining a transmission mode shown in fig. 2 are merely examples, and that other operations or variations of the operations in fig. 2 may also be performed by embodiments of the present application. Furthermore, the various steps in fig. 2 may be performed in a different order than presented in fig. 2, and it is possible that not all of the operations in fig. 2 are performed. Specifically, the method 200 includes:

s201, the first communication device determines a transmission mode according to a received signal-to-noise ratio (SNR) of a channel and a switching boundary.

In some possible implementations, the first communication device determines a mode parameter for determining a switching boundary of the OFDM transmission mode; the first communication device determines channel environment information.

The mode parameter may be transmitted by the second communication device or may be predefined by the second communication device and the first communication device according to a protocol, which is not specifically limited in this application.

Specifically, the first communication device measures a received signal-to-noise ratio of the channel, further judges whether the received signal-to-noise ratio of the channel is smaller than a CP-free and Full-CP communication switching boundary, determines that the transmission mode is a Full-CP mode when the received signal-to-noise ratio is smaller than the switching boundary, and determines that the transmission mode is a CP-free mode when the received signal-to-noise ratio is greater than or equal to the switching boundary. The above-mentioned received signal-to-noise ratio and channel spatial correlation coefficient information may be illustratively determined for the first communication device to detect the channel environment at the beginning of each time slot, e.g., the first communication device may detect the channel environment according to the demodulation reference signal (demodulation reference signal, DMRS). Further, the received signal-to-noise ratio is calculated and obtained according to the received signal and the noise statistical information; the channel spatial correlation coefficient is obtained by correlating the time channel response vector.

In some possible implementations. The first communication device determines the handover boundary based on the mode parameter. Specifically, when the second communication device is a network device, the above-mentioned mode parameter may be transmitted for the second communication device.

The mode parameters can be SNR switching boundary values corresponding to different modulation modes; alternatively, the mode parameter may be a value of SNR switching boundary corresponding to different antenna configurations or data streams; alternatively, the mode parameter may also include a received signal-to-noise ratio and channel spatial correlation coefficient information; alternatively, the mode parameter may include information such as a channel model.

In some possible implementations, the data transmission modes supported by the fixed area are fixed, and the transmission modes supported by different areas may be the same or different, so that the mode parameters may also be included as the area position. For example, the transmission modes supported by different region locations may be indicated by the region range indication information. FIG. 3 shows two kinds of zone division, as shown in (a) of FIG. 3, zone 1 supports the CP-free mode, zone 2 supports the CP-free and Full-CP flexible switching modes, and zone 3 supports the Full-CP mode; as shown in (b) of fig. 3, the area 1 supports the CP-free mode, the areas 2 and 3 support the CP-free and Full-CP flexible switching modes, and the area 4 supports the Full-CP mode.

Optionally, the first communication device may receive first information, where the first information is used to indicate whether the candidate transmission modes supported by different area locations are CP-free mode or Full-CP mode, or CP-free and Full-CP flexible switching modes; the first communication device may determine the OFDM transmission mode based on the first information.

In some possible implementations, the terminal device determines the area in which the terminal device is located, and determines the OFDM transmission mode according to the received area range indication information. Alternatively, the terminal device may determine the area according to the location information, or the terminal device may determine the area according to the indication information of the network device. When the terminal device determines that the current area is the area 1, the terminal device can determine the transmission mode as the CP-free mode according to the area range indication information, and does not need to measure the receiving signal-to-noise ratio of the channel; when the terminal device determines that the current area is the area 2 and determines the transmission mode as the CP-free and Full-CP flexible switching mode according to the area range indication information, the terminal device still needs to measure the receiving signal-to-noise ratio of the channel, and further determines the OFDM transmission mode according to the information such as the switching boundary in the mode parameters. It should be understood that if a certain area supports only one mode, there may be no handover boundary information in the mode parameters sent by the network device to the terminal device.

In some possible implementations, the mode parameter may also include SNR value quantization indication information. Since the SNR switching boundaries are different for different channel environments or scenarios, different bit values may be used to represent different SNR switching boundaries, e.g., the number of bits may be 1,2,3,4, or other positive integer. Illustratively, for an SNR switch boundary range of 15-35 dB, 3 bits may be used to quantize 15-35 dB, for example, bit value 000 may be used to represent an SNR switch boundary of 15-17 dB, bit value 001 may represent an SNR switch boundary of 18-20 dB, bit value 010 may represent an SNR switch boundary of 21-23 dB, bit value 011 may represent an SNR switch boundary of 24-26 dB, bit value 100 may represent an SNR switch boundary of 27-29 dB, bit value 101 may represent an SNR switch boundary of 30-32, and bit value 110 may represent an SNR switch boundary of 33-35. Alternatively, the range of the SNR switching boundary may be expressed using 2 or 4 bits, which is not particularly limited in the embodiment of the present application.

Further, the network device may broadcast mode parameters of different channel environments/scenarios through the system, for example, broadcast signaling broadcast mode parameters through the PBCH/SIB or the common RRC signaling and other systems; alternatively, the network device may indicate the mode parameters of the different channel environments/scenarios described above by multicast mode parameters, e.g. by means of group downlink control information (downlink control information, DCI); or, the network device may also directly indicate the corresponding mode parameters of the terminal device through DCI indication or UE specific RRC signaling; alternatively, the mode parameter may be indicated to the terminal device in other manners, which is not specifically limited in the embodiments of the present application.

Optionally, the mode parameter may represent a correspondence between a first parameter and an OFDM transmission mode switching boundary, wherein the first parameter includes at least one of: scene, modulation mode, antenna configuration, data stream number, spatial correlation, and service type. For example, the correspondence is shown in at least one value (for example, at least one value of x11 to x 36) and/or at least one row and/or at least one column in table 2, where x11 to x36 represent OFDM transmission mode switching boundaries indicated by mode parameters, and more specifically, x11 in table 2 represents that in indoor, modulation mode is 16QAM, and when other configurations are default reference configurations, the OFDM transmission mode switching boundaries are snr=x11; x33 in table 2 represents that when the antenna configuration (such as the number of transmit antennas, or the number of receive antennas, the number of transmission streams, etc.) is 6 in the sparse urban area, and the other configurations are default reference configurations, the OFDM transmission mode switching boundary is snr=x33, and other values in the table are the same. In some possible implementations, the default reference configuration may be: the number of OFDM subcarriers is 64; the number of the transmitting antennas is 6, and the number of the receiving antennas is 8; the modulation mode is 64QAM; the channel model is the SUI channel model, and the maximum delay is extended to 10 sample periods. The reference configuration may be other configurations, and the embodiment of the present application is not limited in particular. It should be noted that the parameters in table 2 are only exemplary, and in some possible implementations, the mode parameter may also indicate an OFDM transmission mode switching boundary under a specific scenario, a modulation mode, an antenna configuration, and a spatial correlation, for example, the mode parameter may indicate that in a dense urban area, the modulation mode is 16QAM, the antenna configuration is 8, and the OFDM transmission mode switching boundary when the spatial correlation is 0.7 is snr=x27, which is not limited in the embodiments of the present application. It should be noted that, the x11-x36 may be an exact SNR value, or may be an SNR range, which is not limited in the embodiment of the present application. Wherein, the values of x11-x36 can be real numbers. The network device may send one or more values in table 2, or one or more rows of mode parameters, one or more columns of mode parameters, or all mode parameters to the terminal device through high layer signaling and/or physical layer signaling, which is not specifically limited in this embodiment of the present application.

In some possible implementations, the relationship between the first parameter and the OFDM transmission mode switching boundary is predetermined. The OFDM handoff boundary is illustratively determined based on the spectral efficiency, block error rate, and bit error rate of the communication system when operating in Full-CP mode and CP-free mode, respectively.

In some possible implementations, the network device sends fourth information to the terminal device through higher layer signaling and/or physical layer signaling, where the fourth information is used to indicate a switching boundary of the OFDM transmission mode corresponding to a first parameter, where the first parameter includes at least one of: scene, modulation mode, antenna configuration, data stream number, channel space correlation coefficient, service type.

Table 2 examples of switching boundaries among different mode parameters

Further, the terminal device may determine the first indication information according to the mode parameter and the measured received signal-to-noise ratio of the channel. The terminal device may determine the first indication information based on x11-x36 in table 2 and SNR of the channel.

It should be understood that, in the Full-CP mode, the second communication device inserts a cyclic prefix before the transmitted OFDM symbol, and the first communication device uses a Full-CP receiver to receive the OFDM symbol, and then restores the bit stream in the OFDM symbol through operations such as preprocessing, signal detection, demapping and the like; the CP-free mode refers to that the second communication device does not insert a cyclic prefix before the transmitted OFDM symbol, and the first communication device uses the CP-free receiver to receive the OFDM symbol, and then restores the bit stream in the OFDM symbol through operations such as preprocessing, signal detection, demapping, and the like.

It should be understood that the above-mentioned switching boundary is different under different MIMO-OFDM reference scenario configurations, i.e. under different antenna configurations, modulation schemes and channel spatial correlation coefficients, the Bit Error Rate (BER), block error rate (BLER) and spectral efficiency changes with the received signal-to-noise ratio when the system operates in the Full-CP mode and the CP-free mode should be measured first, so that the specific received signal-to-noise ratio switching boundary is determined according to the frequency spectrum efficiency. After the switching boundaries of various scenes are determined, when a specific scene is deployed, the corresponding OFDM transmission mode is selected only according to the measured channel space correlation coefficient and the system configuration.

Illustratively, one is provided with N _t Root transmit antenna and N _r MIMO-OFDM system with multiple receive antennas is an example, where each antenna uses N _c The sub-carriers transmit information. In some possible implementations, the number of antennas N is taken _t ＝6,N _r Number of subcarriers n=8 _c The modulation scheme adopts 64QAM square constellation modulation, and specific reference scene configuration is shown in table 3.

Table 3 MIMO-OFDM reference scene configuration

Parameters (parameters)	Value of
		OFDM subcarrier number	64
Cyclic prefix length	0 (CP-free) or 16 (Full-CP)
		Number of transmitting/receiving antennas	The number of transmission days is 6, and the number of receiving antennas is 8
Modulation scheme	64QAM
		Channel(s)	SUI channel model, maximum delay spread to 10 sample periods

Illustratively, when the MIMO-OFDM reference scenario configuration shown in table 3 is deployed, the change situation of the spectrum efficiency of the Full-CP mode and the CP-free mode along with the received signal-to-noise ratio is compared, so as to determine the switching boundary of the mode parameter. The comparison results of the system performance of the Full-CP mode and the CP-free mode in the reference scenario shown in table 3 are shown in table 4, and it can be seen that when the received signal-to-noise ratio is lower than 20dB, the spectrum efficiency of the Full-CP mode is higher than that of the CP-free mode, and when the received signal-to-noise ratio is 20dB or higher, the BLER of the CP-free mode is reduced to a lower level, and the spectrum efficiency is higher, so that the received signal-to-noise ratio switching boundary in the reference scenario is set to 20dB. The values in the table are BER/BLER/spectral efficiency (bps/Hz).

Table 4 reference scene performance comparison

S202, the first communication device determines the first indication information.

The first communication device may, for example, determine the first indication information based on the transmission mode or may also determine the first indication information based on the received signal-to-noise ratio and the handover boundary.

Optionally, determining that the OFDM transmission mode is Full-CP mode when the received signal-to-noise ratio is less than (less than or equal to) the SNR switching boundary; when the received signal-to-noise ratio is greater than or equal to (greater than) the SNR switching boundary, the OFDM transmission mode is determined to be the CP-free mode.

For example, the first indication information may be a one-bit air interface indication signal, for example, when the signal-to-noise ratio of channel reception measured by the first communication device is smaller than a switching boundary indicated by the mode parameter, the one-bit air interface indication signal is set to 1, which indicates that the transmission mode of the system is a Full-CP mode, so as to improve the detection performance; when the signal-to-noise ratio of the channel received by the first communication equipment is greater than or equal to the switching boundary indicated by the mode parameter, a bit air interface indication signal is set to 0, the system transmission mode is indicated to be a CP-free mode, and the spectrum efficiency is improved.

For example, assuming that the transmission mode of the first communication device is CP-free mode before determining the first indication information, if the first indication information indicates that the transmission mode is Full-CP mode, the first communication device switches the transmission mode from CP-free to Full-CP mode.

For example, assuming that the transmission mode of the first communication device is Full-CP mode before determining the first indication information, if the first indication information indicates that the transmission mode is Full-CP mode, the first communication device may continue to employ the transmission mode of Full-CP.

For example, assuming that the transmission mode of the first communication device is Full-CP mode before determining the first indication information, if the first indication information indicates that the transmission mode is CP-free mode, the first communication device switches the transmission mode from Full-CP to CP-free mode.

For example, assuming that the transmission mode of the first communication device is CP-free mode before determining the first indication information, the first communication device may continue to employ the CP-free transmission mode if the first indication information indicates that the transmission mode is CP-free mode.

In some possible implementations, the first communication device may further determine the first indication information based on a received signal-to-noise ratio and a channel spatial correlation coefficient.

S203, the first communication device transmits the first indication information.

Optionally, the first indication information is used to indicate an OFDM transmission mode that the second communication device should use, so that the second communication device determines to use the CP-free mode or the Full-CP mode.

Alternatively, the first indication information may be a transmission mode suggested for indicating the first communication device. The second communication device may or may not employ the proposed transmission mode, which is not limited in this application.

Optionally, the first communication device sends the first indication information through higher layer signaling.

In some possible implementations, the first communication device is a network device, and the second communication device is a terminal device, and then, for example, in a scenario where a received signal-to-noise ratio of the terminal device changes slowly, the OFDM transmission mode may remain unchanged for a period of time, and then, the network device may instruct, through RRC signaling, the terminal device that the OFDM transmission mode is a CP-free mode or a Full-CP mode. In this case, the OFDM transmission modes of the control channel and the data channel may be the same or different. Accordingly, for the OFDM transmission mode of the control channel and the data channel, the network device may jointly indicate, for example, that the Full-CP mode is used for the control channel and the CP-free mode is used for the data channel; or, the control channel and the data channel are in Full-CP mode, or, the control channel and the data channel are in CP-free mode; alternatively, the network device may also indicate the OFDM transmission modes of the two channels separately, such as indicating the transmission mode of the control channel (e.g. transmission scheme for control channel), and/or indicating the transmission mode of the data channel (e.g. transmission scheme for data channel), which is not specifically limited in this embodiment of the present application.

Illustratively, the OFDM transmission mode of the data channel and the control channel may be indicated using 1 bit, it being understood that the OFDM transmission mode of the data channel and the control channel is the same in this case; alternatively, 2 bits may be used to indicate the data channel and the control channel, respectively, e.g., 00 for the data channel and the control channel both employ CP-free mode, 01 for the data channel employing CP-free mode, control channel employing Full-CP mode, and so on.

In the above scenario, the network device and the terminal device should pre-agree on what mode to instruct the OFDM transmission mode, for example, which indication field exists in the DCI may be configured through RRC signaling, or may be configured through other modes, which is not specifically limited in the embodiment of the present application.

Optionally, the first communication device sends the first indication information through physical layer signaling.

For example, in a scenario where the received signal to noise ratio of the terminal device changes rapidly, the network device may indicate the terminal device OFDM transmission mode through DCI signaling. Optionally, the network device may indicate, in a bit field in DCI, whether the DCI schedules data transmission in a Full-CP or CP-free mode; or, the network device may indicate, in a bit field in the DCI, whether the DCI schedules data and subsequent control channel transmission adopts a Full-CP or CP-free mode transmission scheme; alternatively, the network device may also indicate in the bit field in the DCI whether to change the transmission scheme of the subsequent data channel or control channel, and illustratively, may use 1 bit to indicate whether the transmission scheme of the data/control channel is changed, for example: 0 indicates no change, and 1 indicates a change. In some possible implementations, the previous data transmission uses Full-cp, when the field is 1, indicating that the subsequent data transmission uses cp-free; when the field is 0, this indicates that Full-cp is used for subsequent data transmission.

In some possible implementations, the network device may also indicate in the group DCI what OFDM transmission mode the terminal device adopts. Illustratively, a group transmission mode radio network temporary identifier (transmission mode radio Network temporary identifier, TM-RNTI) may be used to scramble different transmission schemes for different terminal devices in the group, and each terminal device is illustratively assigned an information block for indicating the OFDM transmission mode that the terminal device should employ. In some possible implementations, the location of the information block corresponding to the terminal device may be configured through RRC signaling. Illustratively, each information block may include 1 bit or 2 bits to indicate whether the data channel and the control channel of the terminal device are transmitted in the Full-CP or CP-free mode, which is not specifically limited in the embodiments of the present application.

In some possible implementations, the first communication device is a terminal device. For example, the terminal device receives a channel state information reference signal (CSI-RS) sent by the network device, and indicates, in a channel state information (channel state information, CSI) measurement feedback, an OFDM transmission mode corresponding to the CSI resource, that is, carries the first indication information in the CSI, for example, a transmission scheme feedback indication including 1 bit in the CSI, or the first indication information may be independently encoded, as shown in (a) in fig. 4; or, the terminal device receives downlink data sent by the network device, and indicates a transmission scheme suggested by the subsequent data transmission in ACK/NACK feedback, that is, the ACK/NACK feedback carries the first indication information, for example, a transmission scheme feedback indication including 1 bit in ACK/NACK, or the first indication information may be encoded independently, as shown in (b) in fig. 4, which is not specifically limited in this embodiment of the present application.

S204, the second communication device determines whether to insert a cyclic prefix in front of the OFDM symbol according to the received first indication information.

Specifically, if the first indication information is information indicating that the transmission mode is a Full-CP mode, the second communication device inserts a cyclic prefix before the transmitted OFDM symbol, otherwise does not insert the cyclic prefix before the transmitted OFDM symbol. For example, if the first indication information is a one-bit null indication signal, if the one-bit null indication signal is 1, a cyclic prefix is inserted before the transmitted OFDM symbol; when the one-bit null indication signal is 0, a cyclic prefix is not inserted before the transmitted OFDM symbol.

In some possible implementations, in Full-CP mode, the length of the cyclic prefix may be a length designed according to a delay spread, or may be a length determined in other ways.

Further, in the Full-CP mode, the cyclic prefix length of the OFDM signal may be varied. In some possible implementations, determining the OFDM transmission mode includes determining a length of a cyclic prefix of the OFDM signal.

S205, the second communication device transmits an OFDM signal.

It should be noted that, the OFDM signal includes OFDM symbols, and in the Full-CP mode, the OFDM signal has a cyclic prefix; in CP-free mode, the OFDM signal has no cyclic prefix, i.e. the OFDM signal can be regarded as an OFDM symbol.

Specifically, if the first indication information received in S204 indicates that the transmission mode is the Full-CP mode, the OFDM signal sent in this step carries a cyclic prefix, otherwise, the OFDM signal has no cyclic prefix.

In an exemplary embodiment, if the transmission mode of the second communication device is the CP-free mode before receiving the first indication information, the second communication device switches the transmission mode from the CP-free mode to the Full-CP mode after receiving the first indication information if the first indication information indicates that the transmission mode is the Full-CP mode, and further transmits the OFDM signal in the Full-CP mode.

Illustratively, the MIMO-OFDM reference scenario configuration shown in table 3 above is usedFor example, the total number of bits transmitted by the second communication device in one symbol time is 64×6x6=2304 bits, the input bit stream is first converted into QAM symbols on each sub-carrier by serial-to-parallel conversion and QAM mapping, frequency domain N transmitted on the nth sub-carrier _t The dimensional MIMO complex vector is denoted asThrough N _c Inverse point Fourier transform, u _n Conversion to a time-domain signal vector q _n Simultaneously transmitted from multiple antennas and fed into a multipath channel.

It should be noted that in the present embodiment, the channel is quasi-static, i.e. it remains unchanged for one symbol time, p (p e {1, …, N _t (q) the transmitting antenna and q (q. Epsilon {1, …, N) _r And }) the time domain multipath channel between the receiving antennas can be modeled as an FIR filter with a tap number L ', taking a maximum delay spread L of 10, where L'. Gtoreq.L. It should be appreciated that L represents the number of active taps of the FIR filter. The tap coefficients of the filter areThe MIMO channel matrix formed by the first path between the transmit and receive antenna arrays can be expressed as:

in a general MIMO-OFDM system, a length N is inserted before OFDM symbols in order to eliminate the influence of intersymbol interference _g (N _g Cyclic prefix of ≡L-1). After removing the cyclic prefix, the received time domain symbol Y is restored to the frequency domain through Fourier transformation, and a frequency domain symbol vector Y on the nth sub-carrier is obtained _n Can be expressed as:

Y _n ＝G _n u _n +v _n (1)

wherein v is _n Is the frequency domain noise vector on the nth sub-carrier, the noise variance isG _n Is a frequency domain MIMO channel matrix, specifically:

for the MIMO-OFDM system of CP-free, the cyclic prefix is not inserted before the transmitted OFDM symbol, and the received MIMO-OFDM time domain symbol vectorCan be expressed as:

wherein, the liquid crystal display device comprises a liquid crystal display device,for the currently transmitted frequency domain symbol vector, +.>And->Respectively representing the currently transmitted time domain symbol vector and the time domain symbol vector transmitted in the last symbol time, respectively>For the time domain noise vector, the variance of each element is +.>Matrix->Wherein F is N _c ×N _c Dimension normalized Fourier transform matrix, (-) ^H Representing the conjugate transpose of the matrix +.>Representing Cronecker product, metropolyl>Is N _t ×N _t An identity matrix of dimensions. />Is N in the current symbol time _c N _r ×N _c N _t The expression of the order blocking circulation channel matrix is: />

A and A _-1 N in the current symbol time and in the last symbol time, respectively _c N _r ×N _c N _t The order blocking truncates the channel matrix, where the expression of a is:

s206, the first communication device processes the received OFDM signal according to the transmission mode.

Specifically, the first communication apparatus determines a mode of receiving an OFDM signal, that is, a receiver of receiving an OFDM signal, according to the transmission mode determined in S202. Further, the receiver performs operations such as preprocessing, signal detection, demapping and the like on the received OFDM signal, and finally restores the transmitted bit stream.

It should be noted that, after the first communication device determines the first indication information according to the received signal-to-noise ratio and the switching boundary of the channel, the first indication information may be sent to the second communication device first, or the transmission mode may be switched first, or the two steps may be performed simultaneously, that is, the execution sequence of S202 and S203 in the embodiment of the present application is not specifically limited.

In some possible implementations, the first communication device may indicate the length of the second communication device CP through the first indication information, i.e. the communication system may also enable dynamic switching between different CP lengths.

It should be further noted that, due to the higher complexity of decoding the OFDM symbols of the CP-free, some terminal devices may not support the CP-free mode.

In some possible implementations, when the second communication device is a network device and the first communication device is a terminal device, the terminal device may report the capability when the terminal device needs to receive the downlink data. In this case, the terminal device may transmit indication information to the network device, the indication information being used to report whether the terminal device supports the CP-free mode, or to indicate whether the terminal device supports the CP-free transmission mode when transmitting a message, and/or whether the terminal device supports the CP-free transmission mode when receiving a message.

Optionally, the first communication device transmits second information, the second information being used to indicate capability information, the capability information comprising at least one of: the Full-CP mode is supported, the CP-free mode is not supported, the Full-CP mode and the CP-free mode are supported, or the Full-CP mode is supported and the CP-free mode is not supported.

The method for determining the transmission mode supports flexible switching of the communication system between the Full-CP mode and the CP-free mode, so that the communication system has good spectrum efficiency and can ensure higher signal detection performance.

The specific operation flows of the first communication device in the Full-CP mode and the CP-free mode, respectively, in the MIMO-OFDM reference scenario configuration shown in table 3 are described below with reference to fig. 5 to 7.

Illustratively, when the system is in Full-CP mode, the second communication device inserts a length of N before the transmitted OFDM symbols _g Cyclic prefix of=16. The length of the cyclic prefix is more than or equal to the maximum delay spread of the channel.

As shown in the second communication device and the first communication device apparatus schematic diagram in fig. 5, the Full-CP receiver includes a preprocessing module for removing cyclic prefix and performing fast fourier transform, a deep neural network (deep neural network, DNN) for signal detection, and a demapping module. The complete receiving process is divided into three steps of receiving preprocessing, signal detection and demapping, specifically, as described in the method 400 shown in fig. 6, the method 400 includes:

S401, removing cyclic prefix in the received OFDM signal, transforming the time domain symbol into frequency domain symbol through Fourier transformation, and determining real value frequency domain channel matrix and real value frequency domain symbol vector.

Specifically, the first communication device removes the cyclic prefix in the OFDM signal Y, and sends the cyclic prefix to the fourier transform module in fig. 5 to restore the time domain symbol to the frequency domain through fourier transform, so as to obtain the frequency domain symbol Y. Specifically, the frequency domain symbol vector Y on the nth sub-carrier _n The expression of (2) is shown as formula (1), wherein the frequency domain channel matrix G _n And is determined by calculation from known channel state information.

Further, the signal detection performance is improved through a deep learning technology. Since the deep learning method is usually implemented in the real number domain, the system represented by the formula (1) is subjected to real value decomposition as follows:

wherein Re (-) and Im (-) represent the real and imaginary parts of the complex, respectively, (-) ^T Representing the transpose operation. The equivalent real number form of the single carrier flat fading signal model is obtained through real value decomposition is as follows:

s402, the estimation of the OFDM signal is completed according to the real-value frequency domain channel matrix and the real-value frequency domain symbol vector.

In particularThe first communication device expands the orthogonal approximation message passing algorithm modified by the conjugate gradient iterative method into a deep neural network having T layers of series sub-networks as a signal detection network, as shown in fig. 7. The signal detection network is based on real-value frequency domain channel matrix And real-valued frequency domain symbol vector->Solving the system represented by the formula (2) to complete the transmission of symbol vector +.>Is a function of the estimate of (2).

Specifically, a key adjustable parameter omega is introduced into a layer t sub-network of the signal detection network shown in fig. 7 _t ＝{γ _t ,θ _t ,φ _t ,ξ _t And the detection performance is greatly improved. The t layer sub-network is based on the input real value frequency domain channel matrixReal-valued frequency domain symbol vector->And (t-1) th layer output estimation signal +.>To complete the estimation of the layer, wherein t=1, 2, …, T,/->The sub-network structures of each layer are the same, and can be divided into three parts, namely a preprocessing module, a linear estimator and a nonlinear estimator, and the working flow of the three parts is specifically described by taking a t-th layer sub-network as an example:

1) And a pretreatment module: the preprocessing module comprises a processing module for calculating a solution vector z _t Conjugate gradient unit and meterCalculating a decorrelation coefficient ζ _t Is provided.

First, a linear minimum mean square error estimation equation is constructed as a symmetric positive linear system, which can be expressed as:

Ξ _t z _t ＝g _t

wherein, xi _t Is a symmetric positive definite matrix, I is an identity matrix, specifically,

for vectorsSolution vector z of the linear system _t The conjugate gradient method can be followed to solve iteratively without using matrix inversion. It should be understood that- >The variance of the error is estimated for the nonlinearities delivered to the upper layer subnetwork. Initialization setting of conjugate gradient method to approximate solution vector x ₀ =0, residual vector ρ ₀ ＝g _t -Ξ _t x ₀ ＝g _t Conjugate direction vector p ₀ ＝ρ ₀ In this embodiment, the maximum iteration number of the conjugate gradient method is set to 50, and the specific steps of the ith iteration are as follows:

a) Updating the approximation solution x for the ith iteration _i ：

x _i ＝x _i-1 +α _i-1 p _i-1

Wherein alpha is _i-1 Is a scalar search step size ρ _i-1 And p _i-1 The residual error and the conjugate direction vector which are respectively output by the (i-1) th iteration;

b) Updating residual vector ρ _i ＝g _t -Ξ _t x _i And a conjugate direction vector p _i ：

ρ _i ＝ρ _i-1 -α _i-1 Ξ _t p _i-1

p _i ＝ρ _i +β _i-1 p _i-1

Wherein beta is _i-1 Is the gram-schmitt orthogonalization constant;

c) Computing residual vector norms iiρ _i II, if II ρ in the present embodiment _i II is less than 10 ^-4 Terminating the iteration and outputting the approximate solution vector x _i As a pair solution vector z _t Is determined by the estimation of (a); otherwise, returning to the step a, and continuing to execute iteration.

On the other hand, for matrixDecomposing the characteristic value to obtain a characteristic value lambda _i (i＝1,…,2N _r ) Then calculate the decorrelation coefficient ζ according to the eigenvalues _t The adopted formula is specifically as follows:

2) A linear estimator: the linear estimator combines the solution vector z derived by the preprocessing module _t And a decorrelation coefficient ζ _t Updating the outward mean vector r _t And calculate the error varianceThe adopted formula is specifically as follows:

Wherein the adjustable parameter gamma _t And theta _t Respectively mean vector r _t Sum error varianceIs used for updating the step size of the step size. R is as follows _t And->Is the prior mean and variance that has an important impact on the accuracy of the OFDM symbol vector estimation, thus by adjusting the parameter gamma _t And theta _t The control signal may detect a convergence characteristic of the network.

3) A non-linear estimator: the nonlinear estimator combines the a priori mean vector r provided by the linear estimator _t Sum of variancesUsing non-linear function eta without divergence _t Calculating an estimated signal>Variance of estimation error->As output of the layer t subnetwork, the estimated signal +.>The adopted formula is specifically as follows:

wherein the non-linear function eta has no divergence _t (. Cndot.) in combination with a priori mean r _t Mean of sum posteriorAdjustable parameter phi _t And xi _t For maintaining eta _t (-) non-divergence property, the stability of the signal detection network is ensured. />For transmitting the true value of the symbol vector. In the examples of the present application, the ∈ ->Each component comes from a modulation symbol set formed by the real part of the 64QAM constellation point

Posterior mean estimationThe expression for each component of (a) is: />

Wherein, the liquid crystal display device comprises a liquid crystal display device,and->Respectively->And r _t Is the kth component of>Is a component->Is judged as a _m The specific formula is:

acquiring an estimated signal After that, the nonlinear estimation error variance is updated +.>The specific formula of (2) is:

in order to enhance the stability of the signal detection network, the updated error variance is convexly and linearly combined with the numerical value transmitted by the previous layer of sub-network, and the minimum value of the output variance is limited, wherein the specific formula is as follows:

where β is the damping factor, taken as 0.5 in this example, ε is a predetermined variance threshold, taken as 10 in this example ^-10 To avoidIs negative.

The three modules of the T layer sub-network all execute the operations according to the steps 1) to 3), and finally output estimated symbol vectors

In the embodiment of the application, each layer of the signal detection neural network has only 4 adjustable parameters { gamma } _t ,θ _t ,φ _t ,ξ _t In a neural network with a T layer sub-network, the total amount of adjustable parameters is 4T, which is independent of the number of antennas and the number of sub-carriers, and thereforeThe architecture is beneficial to reducing training overhead and can realize rapid deployment.

Further, the adjustable parameters of each layer of the signal detection neural network are determined through training optimization, and specific training processes are as follows:

the signal detection network described above was supervised learning trained using a small lot gradient descent algorithm, which in this example, comprised a total of 1000 training rounds, each round containing 5 small lots. A small batch of training sets is represented as Is a set of S randomly generated samples, wherein the transmitted real-valued symbol vector +.>As a tag, real-valued frequency domain symbol vector +.>And real-valued frequency domain channel matrix->As an input feature of the network, i is a sample number, S is taken as 5000 in this example, and an adaptive momentum estimation optimizer is selected to optimize trainable parameters in the neural network, and the initial learning rate is set to 0.001. Training uses a square loss function L ₂ The specific formula is as follows:

wherein, the liquid crystal display device comprises a liquid crystal display device,the i estimated symbol vector sample output by the signal detection network is back propagated after the loss function is calculated and is used for optimizing the adjustable parameters. After the training is completed by the above-mentioned process, the network can be deployed on line rapidly, and forward signal detection is realized.

S403, restoring the estimated symbol vector to a complex domain, combining the data streams on each sub-carrier, and performing demapping to obtain an estimated value of the bit stream.

Specifically, after completing detection of the transmission symbols on all the effective subcarriers, the estimated symbol vectorsRestoring to complex domain, merging the data streams on each sub-carrier, and then demapping. Illustratively, in the embodiments of the present application, soft decisions are performed, in conjunction with channel coding to improve performance, ultimately obtaining an estimate of the original transmitted bit stream.

The above is a process of detecting and demapping the received OFDM signal by the first communication device when the system is in Full-CP mode. It should be noted that when the system is in CP-free mode, the first communication device needs to cancel the inter-symbol interference before detecting the OFDM signal. Specifically, in the CP-free mode, the workflow of the first communication device after receiving the OFDM signal is as follows:

1. eliminating intersymbol interference and real-valued decomposition

First, the estimated value of the time domain symbol vector transmitted in the last symbol time outputted by the feedback loop is utilizedCancellation of received OFDM time domain symbol vector>Redundant intersymbol interference in (B), symbol vector obtained by this procedure>Can be expressed as:

in the channel matrixIs calculated from known channel state information.

After the inter-symbol interference cancellation is completed, the system represented by the formula (3) is subjected to real-valued decomposition, similarly to the operation in the above-described embodiment S401:

the equivalent real form of the system represented by formula (3) is obtained as follows:

y _r ＝C _r u _r +w _r (4)

2. signal detection

For the signal recovery problem shown in equation (4), the signal detection network described in S402 of method 400 can be used to solve the problem, simply by replacing the input of the network with the real OFDM symbol vector y _r Real value channel matrix C _r And noise varianceAnd retraining the 4 adjustable parameters in the network using the corresponding data set, which is not described here. In addition, the training process of the signal detection network is also similar to the training process described in S402, and it should be noted that each small batch is represented asAnd S is taken as 500. After training, the signal detection network is used to perform joint detection on the symbols transmitted on all effective subcarriers, so as to obtain the estimation of the complete OFDM symbol vector +.>

3. Demapping and caching

OFDM symbol vector to be estimated after signal detection is completedRestoring to complex domain, and then demapping to obtain estimated transmitted bit stream +.>Furthermore, the estimated symbol vector +.>Store to buffer, get delayed symbol vector +.>Sending the signal to a feedback loop, and obtaining an estimated +.>For eliminating redundant intersymbol interference in the next round of reception.

According to the method for determining the transmission mode, which is provided by the embodiment of the application, the neural network is detected based on the signals with a plurality of adjustable parameters at each layer, so that the cost of training the neural network can be reduced; based on the adjustable parameters, the signal detection performance can be greatly improved. In addition, a conjugate gradient algorithm is utilized to construct a deep neural network, so that complex direct matrix inversion is avoided, and the running time can be reduced. Therefore, the method for determining the transmission mode provided by the embodiment of the application has the advantages of strong generalization and quick deployment. Further, the communication system based on the deep neural network can be flexibly switched between the CP-free mode and the Full-CP mode, so that the spectrum efficiency and the signal detection performance in the data transmission process can be considered, and the processing complexity of the first communication equipment can be reduced and the system performance and the complexity can be balanced by suggesting an OFDM transmission mode to the second communication equipment through the first communication equipment.

The following describes the technical effects of the method for determining a transmission mode according to the embodiments of the present application, and the influence of the communication system configuration, such as spatial correlation coefficient, antenna configuration, modulation scheme, and channel model, on the switching boundary corresponding to the mode parameters in the above embodiments, in conjunction with tables 5 to 12.

Table 5 is a comparison between the conventional signal detection scheme and the result obtained by detecting the OFDM signal based on the detection method of the signal detection network provided in the embodiment of the present application, taking the first indication information in the above embodiment as a one-bit air interface indication signal as an example under the MIMO-OFDM reference scenario configuration shown in table 3. Wherein the values in the table are in turn BER/BLER/spectral efficiency (bps/Hz). It should be appreciated that the lower the BER and BLER, the better the detection performance, and hence the higher the communication system capacity; the higher the spectral efficiency, the higher the data transmission efficiency. As can be seen from the test results in table 5, the detection performance and the spectrum efficiency in the method for determining the transmission mode provided in the embodiment of the present application are better than those of the conventional detection scheme, both in the Full-CP mode and the CP-free mode. In particular, at a received signal-to-noise ratio below 20dB, the BER and BLER in Full-CP mode are significantly lower than in CP-free mode, while the spectral efficiency in Full-CP mode is significantly higher than in CP-free mode; at a received signal-to-noise ratio greater than or equal to 20dB, the BER and BLER in Full-CP mode are significantly higher than in CP-free mode, while the spectral efficiency in Full-CP mode is significantly lower than in CP-free mode. Therefore, the method for determining the transmission mode provided by the embodiment of the application can achieve higher detection performance and spectrum efficiency.

Table 5 reference scene performance comparison

Illustratively, the influence of the spatial correlation coefficient of the channel on the transmission mode switching boundary is considered on the basis of the reference scenario shown in table 3. Tables 6-9 show the comparison of the signal detection performance when the spatial correlation coefficients of the channels are different, and it can be seen from tables 6 and 7 that in the scenarios where the spatial correlation coefficients ρ=0.3 and 0.5 are low, the signal detection performance is reduced, the received signal-to-noise ratio required for achieving the same performance is higher, but the received signal-to-noise ratio switching boundary remains unchanged, that is, the frequency spectrum efficiency of the CP-free mode is higher when the received signal-to-noise ratio is greater than or equal to 20 dB. However, for channels with stronger correlation, such as spatial correlation coefficients ρ=0.5 and 0.7, it can be seen from tables 8 and 9 that the interference conditions for CP-free transmission are more complex, a higher received signal-to-noise ratio is required to lower the BLER sufficiently low and to make the spectral efficiency sufficiently high, so the received signal-to-noise ratio switching boundary increases to 22dB and 23dB, respectively. That is, when deployed in a scenario where the channel spatial correlations are different, the first communication device first determines a handover boundary from the measured channel spatial correlation coefficients. Alternatively, in some possible implementations, the switching boundary of the transmission mode is determined according to the spatial correlation coefficient of the channel and the received signal-to-noise ratio, i.e. the mode parameters include the spatial correlation coefficient of the channel and the received signal-to-noise ratio as described in the above embodiments. More specifically, the relationship between the switching boundary of the transmission mode and the received signal-to-noise ratio and the spatial correlation coefficient ρ is shown in fig. 8.

Table 6 comparison of performance at spatial correlation coefficient ρ=0.3

Table 7 comparison of performance at spatial correlation coefficient ρ=0.5

Table 8 comparison of performance at spatial correlation coefficient ρ=0.6

Table 9 comparison of performance at spatial correlation coefficient ρ=0.7

Illustratively, the influence of the antenna configuration on the transmission mode switching boundary is considered on the basis of the reference scenario shown in table 3. For example, with a symmetric antenna configuration, the number of transmit antennas and the number of receive antennas were set to 8, and the test results are shown in table 10. It can be seen that as the number of transmit antennas increases, the user transmission data stream increases, and in this case, it is more difficult to eliminate ISI, the performance gap between the CP-free mode and the Full-CP mode increases, and the receiving snr switching boundary needs to be raised to 32dB. In addition, in the symmetrical antenna configuration, the receiving performance gain is smaller, and the performance of each scheme is reduced.

Table 10 comparison of performances when the number of transmitting/receiving antennas is 8

Illustratively, the influence of the modulation scheme on the transmission mode switching boundary is considered on the basis of the reference scene shown in table 3. The modulation scheme is changed to 16QAM modulation, and the test results are shown in Table 11. It can be seen that the performance gap between the CP-free mode and the Full-CP mode is reduced and the receive snr switching margin is reduced to 17dB under low order modulation.

Table 11 comparison of performance at 16qam modulation

Illustratively, the influence of the channel model on the transmission mode switching boundary is considered on the basis of the reference scenario shown in table 3. The channel model was tuned to the "new radio technology of the wireless world" (wireless world initiative new radio, WINNER II) model, the channel maximum delay spread was 16 sample periods, and the test results are shown in table 12. Under the WINNER II channel, the performance of each scheme is improved compared with the reference scene, but the switching boundary of the receiving signal to noise ratio is kept unchanged.

Table 12 Performance comparison under WINNER II channel model

In addition, it should be noted that, as can be seen from the signal detection performance results shown in tables 5 to 12, under the above various communication system configurations, the detection performance and the spectrum efficiency in the method for determining the transmission mode provided in the embodiment of the present application are better than those of the conventional detection scheme.

In some possible implementations, in the communication system shown in fig. 1, the second communication device indicates to the first communication device the transmission mode of the communication system. Fig. 9 shows a schematic flow chart of the second communication device indicating to the first communication device the transmission mode of the communication system. It should be understood that the steps or operations of the method for determining a transmission mode shown in fig. 9 are merely examples, and other operations or variations of the operations in fig. 9 may also be performed by embodiments of the present application. Further, the various steps in fig. 9 may be performed in a different order than presented in fig. 9, and it is possible that not all of the operations in fig. 9 are performed. Specifically, the method 700 includes:

S701, the second communication device determines a cyclic prefix length of the OFDM signal.

Alternatively, the cyclic prefix length may be cyclic prefix-with or cyclic prefix-without.

Illustratively, if a cyclic prefix is included in an OFDM symbol, the second communication device needs to insert the cyclic prefix before the OFDM symbol when generating the OFDM symbol.

For example, before the second communication device determines whether to insert a cyclic prefix before an OFDM symbol, the OFDM transmission mode may be determined according to a received signal-to-noise ratio and a mode parameter. More specifically, the received signal-to-noise ratio information of the first communication device is acquired, and the OFDM transmission mode is determined according to whether the received signal-to-noise ratio is smaller than the SNR switching boundary.

For example, when the received signal-to-noise ratio is less than (less than or equal to) the SNR switching boundary, determining that the OFDM transmission mode is Full-CP mode; when the received signal-to-noise ratio is greater than or equal to (greater than) the SNR switching boundary, the OFDM transmission mode is determined to be the CP-free mode.

Further, the second communication device may determine whether to insert a cyclic prefix before the OFDM symbol according to the OFDM transmission mode.

In some possible implementations, the second communication device receives third information, and determines an OFDM transmission mode from among candidate transmission modes (i.e., full-CP mode and CP-free mode) according to the third information; the third information is used for indicating that the OFDM transmission mode is a Full-CP mode or a CP-free mode; alternatively, the third information is used to indicate the received signal-to-noise ratio of the channel.

The third information is, for example, indication information sent by the first communication device, the indication information being used to indicate a proposed transmission mode of the first communication device.

In some possible implementations, when the first communication device is a terminal device and the second communication device is a network device, that is, the data transmitted in the communication system is uplink data, the terminal device may report the capability. In this case, the terminal device may transmit indication information to the network device, the indication information being used to report whether the terminal device supports the CP-free mode, or to indicate whether the terminal device supports the CP-free transmission mode when transmitting a message, and/or whether the terminal device supports the CP-free transmission mode when receiving a message.

S702, the second communication device sends second indication information.

Optionally, the second indication information is used to indicate an OFDM transmission mode that the first communication device should employ, so that the first communication device determines to employ the CP-free mode or the Full-CP mode.

Alternatively, the second indication information may be a transmission mode suggested for indicating the second communication device. The first communication device may or may not employ the proposed transmission mode, which is not limited in this application.

Illustratively, the second communication device determines the second indication information according to the OFDM transmission mode determined in S701.

Optionally, the second communication device sends the second indication information through higher layer signaling.

In some possible implementations, the second communication device is a network device, and the first communication device is a terminal device, and then, for example, in a scenario where a received signal-to-noise ratio of the terminal device changes slowly, the OFDM transmission mode may remain unchanged for a period of time, and then, the network device may instruct, through RRC signaling, the terminal device that the OFDM transmission mode is a CP-free mode or a Full-CP mode. In this case, the OFDM transmission modes of the control channel and the data channel may be the same or different. Accordingly, for the OFDM transmission mode of the control channel and the data channel, the network device may jointly indicate, for example, that the Full-CP mode is used for the control channel and the CP-free mode is used for the data channel; or, the control channel and the data channel are in Full-CP mode, or, the control channel and the data channel are in CP-free mode; alternatively, the network device may also indicate the OFDM transmission modes of the two channels separately, such as indicating the transmission mode of the control channel (e.g. transmission scheme for control channel), and/or indicating the transmission mode of the data channel (e.g. transmission scheme for data channel), which is not specifically limited in this embodiment of the present application.

Optionally, the second communication device sends the second indication information through physical layer signaling.

In some possible implementations, the network device may also indicate in the group DCI what OFDM transmission mode the terminal device adopts. Illustratively, a group transmission mode radio network temporary identifier (transmission mode radio Network temporary identifier, TM-RNTI) may be used to scramble different transmission schemes for different terminal devices in the group, and each terminal device is illustratively assigned an information block for indicating the OFDM transmission mode that the terminal device should employ. In some possible implementations, the positions of the information blocks corresponding to the terminal devices may be configured through RRC signaling, as shown in fig. 10, where blocks 0 through n-1 are information blocks corresponding to n terminal devices, respectively. Illustratively, each information block may include 1 bit or 2 bits to indicate whether the data channel and the control channel of the terminal device are transmitted in the Full-CP or CP-free mode, which is not specifically limited in the embodiments of the present application.

In some possible implementations, the second communication device is a terminal device. Illustratively, the terminal device receives a channel state information reference signal (CSI-RS) sent by the network device, and indicates, in a channel state information (channel state information, CSI) measurement feedback, an OFDM transmission mode corresponding to the CSI resource, that is, carries the second indication information in the CSI, for example, a transmission scheme feedback indication including 1 bit in the CSI, or the second indication information may be independently encoded, as shown in (a) in fig. 4; or, the terminal device receives the downlink data sent by the network device, and indicates the transmission scheme suggested by the subsequent data transmission in the ACK/NACK feedback, that is, the ACK/NACK feedback carries the second indication information, for example, a transmission scheme feedback indication including 1 bit in the ACK/NACK, or the second indication information may be independently encoded, as shown in (b) in fig. 4, which is not specifically limited in this embodiment of the present application.

S703, the first communication device determines a transmission mode according to the second instruction information.

The first communication device determines the transmission mode, i.e. the transmission mode is determined as CP-free mode or Full-CP mode, on the basis of the second indication information.

S704, the second communication device transmits an OFDM signal.

S705, the first communication device detects the OFDM signal according to the transmission mode.

Specifically, the process of the first communication device detecting the OFDM signal according to the transmission mode may refer to S206 in the method 200, which is not described herein.

It should be noted that, the second communication device may determine whether to insert the cyclic prefix before the OFDM signal, or may first send the second indication information to the first communication device, or may perform the two steps simultaneously, that is, the execution sequence of S701 and S702 is not specifically limited in this embodiment of the present application.

According to the method for determining the transmission mode, based on the communication system of the deep neural network, the communication system can be flexibly switched between the CP-free mode and the Full-CP mode, so that the spectrum efficiency and the signal detection performance in the data transmission process can be considered, and the data transmission efficiency can be improved in a mode that the transmission mode is directly indicated by the second communication equipment.

Alternatively, the first communication device and the second communication device may determine the mode parameters according to predefined transmission scheme information including a relationship between a switching boundary of an OFDM transmission mode predefined by the protocol and the first parameters.

In some possible implementations, the second communication device and the first communication device may predefine, via a protocol, whether the transmission mode of the communication system is CP-free mode or Full-CP mode. For example, SNR switching boundaries under different scenarios and configurations may be specified in the protocol, whereby the second communication device and the first communication device determine the OFDM transmission mode according to the predefined SNR switching boundaries.

Illustratively, SNR switching boundaries in specific scenarios such as indoor, dense urban and sparse urban may be specified in the protocol, as shown in table 13; alternatively, SNR switching boundaries for different scenarios and configurations shown in table 2 may also be specified in the protocol; alternatively, an OFDM transmission mode and/or an SNR switching boundary may be defined for different service types in the protocol, for example, only Full-CP transmission may be supported for data transmission with high reliability requirements, such as ultra-high reliability low latency communication (ultra-reliability low latency communication, URLLC), and an OFDM transmission mode capable of supporting switching between Full-CP and CP-free may be supported for enhanced mobile broadband (enhanced mobile broadband, eMBB), etc.; alternatively, the OFDM transmission mode under other scenarios and configurations may be predefined in the protocol, which is not specifically limited in the embodiments of the present application.

Table 13 protocol specifies parameter boundaries in specific scenarios

Scene/parameter	Parameter boundary (SNR dB)
		Indoor unit	x1
Dense urban area	x2
		Sparse urban area	x3

In some possible implementations, if the second communication device and the first communication device predefine a transmission mode of the communication system through a protocol, before the second communication device determines the OFDM transmission mode, a received signal-to-noise ratio of the first communication device needs to be acquired, and then the OFDM transmission mode is determined according to the received signal-to-noise ratio and the SNR switching boundary of the first communication device.

According to the method for determining the transmission mode, the OFDM transmission mode is predefined through the second communication device and the first communication device, signaling overhead can be saved, and communication performance is improved.

Fig. 11 illustrates a method 1100 for determining a transmission mode according to an embodiment of the present application, where the method 1100 may be applied to the application scenario illustrated in fig. 1, or may also be applied to other scenarios of message transmission, and the embodiment of the present application is not limited to this. Illustratively, the method 1100 is performed by an OFDM receiving end. The method 1100 includes:

s1110 determining an OFDM transmission scheme from among candidate transmission modes, the candidate transmission modes including a first mode in which the OFDM signal includes a cyclic prefix and a second mode in which the OFDM signal does not include a cyclic prefix.

Specifically, the method may be performed by the network device or may also be performed by the terminal device, which is not limited in the embodiments of the present application.

Illustratively, the network device may be the network device 110 shown in fig. 1, and the terminal device may be the terminal device 120 shown in fig. 1.

Illustratively, the first mode may be the Full-CP mode in the above embodiment; the second mode may be the CP-free mode in the above-described embodiments.

Specifically, the method for determining the OFDM transmission mode from the candidate transmission modes may refer to the description in the above embodiment, and will not be described herein.

S1120, receiving an OFDM signal according to the OFDM transmission mode.

Specifically, the specific method for receiving the OFDM signal may refer to the description in the embodiment, and will not be repeated here.

In some possible implementations, after the OFDM receiving end receives the OFDM signal, the OFDM signal is processed in the OFDM transmission mode. The specific method for processing the OFDM signal may refer to the description in the above embodiment, and will not be described herein.

In some possible implementations, as shown in (a) of fig. 12, the OFDM receiving end receives the second indication information before determining the OFDM transmission mode (S1109), and further determines the OFDM transmission mode according to the second indication information. The second indication information may be, for example, the second indication information described in the above embodiment.

In some possible implementations, the method 1100 further includes: determining a mode parameter, the mode parameter being used to determine a switching boundary of the OFDM transmission mode; determining channel environment information; the determining an OFDM transmission mode from the candidate transmission modes includes: the OFDM transmission mode is determined from the candidate transmission modes based on the mode parameters and channel environment information.

In some possible implementations, the mode parameter is a relationship between a first parameter and a switching boundary of the OFDM transmission mode, wherein the first parameter includes at least one of: scene, modulation mode, antenna configuration, data stream number, channel space correlation coefficient, service type.

In some possible implementations, the method 1100 further includes: receiving first information, wherein the first information is used for indicating the candidate transmission modes supported by different area positions; the OFDM transmission mode is determined based on the first information.

The first information may be, for example, the first information described in the above embodiment.

In some possible implementations, the method 1100 further includes: the mode parameter is determined from predefined transmission scheme information comprising a relation between a switching boundary of the OFDM transmission mode predefined by a protocol and the first parameter.

In some possible implementations, the method 1100 further includes: the channel environment information comprises a received signal-to-noise ratio, the mode parameter comprises a signal-to-noise ratio (SNR) switching boundary, the OFDM transmission mode is determined from the candidate transmission modes according to the mode parameter and the channel environment information, and when the received signal-to-noise ratio is smaller than the SNR switching boundary, the OFDM transmission mode is determined to be the first mode; and when the received signal-to-noise ratio is greater than or equal to the SNR switching boundary, determining the OFDM transmission mode as the second mode.

In some possible implementations, the method 1100 further includes: and sending first indication information, wherein the first indication information is used for indicating the OFDM transmission mode.

Illustratively, as shown in (b) of fig. 12, the OFDM receiving end transmits first indication information (S1111) to indicate an OFDM transmission mode that the OFDM transmitting end should use after determining the OFDM transmission mode. The first indication information may be, for example, the first indication information described in the above embodiment.

In some possible implementations, the method 1100 further includes: transmitting second information, wherein the second information is used for indicating capability information, and the capability information comprises at least one of the following items: the first mode is supported, the second mode is not supported, the first mode and the second mode are supported, or the first mode is supported and the second mode is not supported.

The second information may be, for example, the second information described in the above embodiment.

In some possible implementations, the method 1100 further includes: when the OFDM transmission mode is the first mode, after receiving an OFDM signal, removing a cyclic prefix in the OFDM signal, transforming a time domain symbol into a frequency domain symbol through Fourier transformation, and determining a real-value frequency domain channel matrix and a real-value frequency domain symbol vector of the frequency domain symbol; and according to the real-value frequency domain channel matrix and the real-value frequency domain symbol vector, performing the signal detection on the OFDM signal by using a depth neural network determined based on a conjugate gradient iteration method.

In some possible implementations, the method 1100 further includes: when the OFDM transmission mode is the first mode, after receiving an OFDM signal, eliminating inter-symbol interference in the OFDM signal according to an estimated value of a symbol vector sent in the last symbol time, and determining a real-value time domain symbol vector and a real-value time domain channel matrix of the OFDM symbol; and according to the real-value time domain symbol vector and the real-value time domain channel matrix, performing the signal detection on the OFDM symbol by using a depth neural network determined based on a conjugate gradient iteration method.

In some possible implementations, the method 1100 further includes: the solution vector of the real-value noise vector is determined by utilizing the conjugate gradient method iteration solution, and the decorrelation coefficient is determined according to the real-value frequency domain channel matrix; calculating an outward mean value vector and an error variance according to the solution vector and the decorrelation coefficient, wherein the update step sizes of the outward mean value vector and the error variance are respectively adjusted by a second parameter and a third parameter; and calculating an estimated value of the symbol vector by using a non-divergence nonlinear function according to the outward mean value vector and the error variance, wherein a non-divergence characteristic of the non-divergence nonlinear function is adjusted by a fourth parameter and a fifth parameter.

In some possible implementations, the method 1100 further includes: and calculating a first estimation error variance according to the estimation value of the symbol vector, and determining an estimation error variance according to the first estimation error variance and a second estimation error variance transmitted by a previous layer of sub-network, wherein the estimation error variance is used for calculating a solution vector of a real-valued noise vector of a next layer of sub-network.

In the method for determining the transmission mode, the first communication device can select a suitable transmission mode from the first mode and the second mode to receive data or a channel, so that a communication system can have good spectrum efficiency, and meanwhile, higher signal detection performance is guaranteed, and therefore the capacity of the communication system is improved.

Fig. 13 illustrates a method 1200 for determining a transmission mode according to an embodiment of the present application, where the method 1200 may be applied to the application scenario illustrated in fig. 1, or may also be applied to other scenarios of message transmission, and the embodiment of the present application is not limited to this. Illustratively, the method 1200 is performed by an OFDM signal transmitter. The method 1200 includes:

s1210, determining an OFDM transmission scheme from among candidate transmission modes, the candidate transmission modes including a first mode in which the OFDM signal includes a cyclic prefix and a second mode in which the OFDM signal does not include the cyclic prefix.

S1220, an OFDM signal is transmitted according to the OFDM transmission mode.

Specifically, the specific method for transmitting the OFDM signal may refer to the description in the embodiment, and will not be repeated here.

In some possible implementations, as shown in (a) of fig. 14, the OFDM transmitting end receives the first indication information before determining the OFDM transmission mode (S1209), and further determines the OFDM transmission mode according to the first indication information. The first indication information may be, for example, the first indication information described in the above embodiment.

In some possible implementations, the method 1200 further includes: receiving third information, and determining the OFDM transmission mode from the candidate transmission modes according to the third information; wherein the third information is used for indicating that the OFDM transmission mode is the first mode or the second mode; alternatively, the third information is used to indicate the received signal-to-noise ratio of the channel.

The third information may be, for example, the third information described in the above embodiment.

In some possible implementations, the method 1200 further includes: when the third information is used for indicating the received signal-to-noise ratio, determining the OFDM transmission mode from the candidate transmission modes according to the received signal-to-noise ratio and a mode parameter, wherein the mode parameter is used for indicating a switching boundary of the OFDM transmission mode.

In some possible implementations, the method 1200 further includes: the mode parameter includes a signal-to-noise ratio (SNR) switching boundary, the OFDM transmission mode is determined from the candidate transmission modes according to the received SNR and the mode parameter, and the OFDM transmission mode is determined to be the first mode when the received SNR is smaller than the SNR switching boundary; and when the received signal-to-noise ratio is greater than or equal to the SNR switching boundary, determining the OFDM transmission mode as the second mode.

In some possible implementations, the method 1200 further includes: and transmitting second indication information, wherein the second indication information is used for indicating the OFDM transmission mode.

Illustratively, as shown in (b) of fig. 14, the OFDM transmitting end transmits second indication information (S1211) to indicate an OFDM transmission mode that the OFDM receiving end should use after determining the OFDM transmission mode. The second indication information may be, for example, the second indication information described in the above embodiment.

In some possible implementations, the method 1200 further includes: transmitting fourth information, where the fourth information is used to indicate a switching boundary of the OFDM transmission mode corresponding to a first parameter, and the first parameter includes at least one of: scene, modulation mode, antenna configuration, data stream number, channel space correlation coefficient, service type.

The fourth information may be, for example, the fourth information described in the above embodiment.

In some possible implementations, the method 1200 further includes: and sending first information, wherein the first information is used for indicating the candidate transmission modes supported by different area positions.

In some possible implementations, the method 1200 further includes: receiving second information, the second information being used to indicate capability information, the capability information comprising at least one of: support the first mode, support the second mode, support the first mode and the second mode, or support the first mode and not support the second mode; the OFDM transmission mode is determined based on the second information.

In the method for determining the transmission mode, the second communication device can select a suitable transmission mode from the first mode and the second mode to send data or a channel, so that the communication system can have good spectrum efficiency, and meanwhile, higher signal detection performance is guaranteed, and therefore the capacity of the communication system is improved.

The method provided by the embodiments of the present application is described in detail above in connection with fig. 2 to 13. The apparatus provided in the embodiments of the present application will be described in detail below with reference to fig. 15 and 16. It should be understood that the specific process of each unit performing the corresponding steps has been described in detail in the above method embodiments, and is not described herein for brevity.

It should also be understood that the apparatus herein is embodied in the form of functional units. The term "unit" herein may refer to an application specific integrated circuit (application specific integrated circuit, ASIC), an electronic circuit, a processor (e.g., a shared, dedicated, or group processor, etc.) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that support the described functionality. In an alternative example, it may be understood by those skilled in the art that the apparatus may be specifically configured to perform the first network element in the foregoing embodiment of the method and each flow and/or step corresponding to the first network element, or the apparatus may be specifically configured to be configured to perform the network management network element in the foregoing embodiment of the method and each flow and/or step corresponding to the network management network element, which are not repeated herein for avoiding repetition.

Fig. 15 is a schematic block diagram of an apparatus for determining a transmission mode provided in an embodiment of the present application. The apparatus 2000 includes a transceiving unit 2010 and a transceiving unit 2020. The transceiver unit 2010 may implement a corresponding communication function, and the processing unit 2020 is configured to perform data processing.

Optionally, the apparatus 2000 may further include a storage unit, where the storage unit may be configured to store instructions and/or data, and the processing unit 2020 may read the instructions and/or data in the storage unit, so that the apparatus implements the foregoing method embodiments.

The apparatus 2000 may include means for performing the methods of fig. 2, 6, 9, and 11-14. And, each unit in the apparatus 2000 and the other operations and/or functions described above are respectively for implementing the corresponding flows of the method embodiments in fig. 2, 6, 9 and 11-14.

When the apparatus 2000 is used to perform the method 1100 in fig. 11, the transceiver unit 2010 may be used to perform S1120 in the method 1100, and the processing unit 2020 may be used to perform S1110 in the method 1100.

Specifically, the apparatus 2000 includes: a processing unit 2020, configured to orthogonal frequency division multiplex, OFDM, transmission modes from among candidate transmission modes, the candidate transmission modes including a first mode in which the OFDM signal includes a cyclic prefix and a second mode in which the OFDM signal does not include the cyclic prefix; a transceiver unit 2010 is configured to receive OFDM signals according to the OFDM transmission mode.

In some possible implementations, the processing unit 2010 is further configured to: determining a mode parameter, the mode parameter being used to determine a switching boundary of the OFDM transmission mode; determining channel environment information; the OFDM transmission mode is determined from the candidate transmission modes based on the mode parameters and channel environment information.

In some possible implementations, the transceiver 2020 is further configured to: receiving first information, wherein the first information is used for indicating the candidate transmission modes supported by different area positions; the processing unit 2010 is further configured to determine the OFDM transmission mode based on the first information.

In some possible implementations, the processing unit 2010 is further configured to: the mode parameter is determined from predefined transmission scheme information comprising a relation between a switching boundary of the OFDM transmission mode predefined by a protocol and the first parameter.

In some possible implementations, the channel environment information includes a received signal-to-noise ratio, the mode parameter includes a signal-to-noise ratio SNR switching boundary, the OFDM transmission mode is determined from the candidate transmission modes based on the mode parameter and the channel environment information, and the processing unit 2010 is further configured to: when the received signal-to-noise ratio is smaller than the SNR switching boundary, determining the OFDM transmission mode as the first mode; and when the received signal-to-noise ratio is greater than or equal to the SNR switching boundary, determining the OFDM transmission mode as the second mode.

In some possible implementations, the transceiver 2020 is further configured to: and sending first indication information, wherein the first indication information is used for indicating the OFDM transmission mode.

In some possible implementations, the first indication information is transmitted in combination with CSI feedback information or HARQ-ACK information.

In some possible implementations, the transceiver 2020 is further configured to: transmitting second information, wherein the second information is used for indicating capability information, and the capability information comprises at least one of the following items: the first mode is supported, the second mode is not supported, the first mode and the second mode are supported, or the first mode is supported and the second mode is not supported.

In some possible implementations, the processing unit 2010 is further configured to: when the OFDM transmission mode is the first mode, after receiving an OFDM signal, removing a cyclic prefix in the OFDM signal, transforming a time domain symbol into a frequency domain symbol through Fourier transformation, and determining a real-value frequency domain channel matrix and a real-value frequency domain symbol vector of the frequency domain symbol; and according to the real-value frequency domain channel matrix and the real-value frequency domain symbol vector, performing the signal detection on the OFDM signal by using a depth neural network determined based on a conjugate gradient iteration method.

In some possible implementations, the processing unit 2010 is further configured to: when the OFDM transmission mode is the first mode, after receiving an OFDM signal, eliminating inter-symbol interference in the OFDM signal according to an estimated value of a symbol vector sent in the last symbol time, and determining a real-value time domain symbol vector and a real-value time domain channel matrix of the OFDM symbol; and according to the real-value time domain symbol vector and the real-value time domain channel matrix, performing the signal detection on the OFDM symbol by using a depth neural network determined based on a conjugate gradient iteration method.

In some possible implementations, the processing unit 2010 is further configured to: the solution vector of the real-value noise vector is determined by utilizing the conjugate gradient method iteration solution, and the decorrelation coefficient is determined according to the real-value frequency domain channel matrix; calculating an outward mean value vector and an error variance according to the solution vector and the decorrelation coefficient, wherein the update step sizes of the outward mean value vector and the error variance are respectively adjusted by a second parameter and a third parameter; and calculating an estimated value of the symbol vector by using a non-divergence nonlinear function according to the outward mean value vector and the error variance, wherein a non-divergence characteristic of the non-divergence nonlinear function is adjusted by a fourth parameter and a fifth parameter.

In some possible implementations, the processing unit 2010 is further configured to: and calculating a first estimation error variance according to the estimation value of the symbol vector, and determining an estimation error variance according to the first estimation error variance and a second estimation error variance transmitted by a previous layer of sub-network, wherein the estimation error variance is used for calculating a solution vector of a real-valued noise vector of a next layer of sub-network.

When the apparatus 2000 is used to perform the method 1200 in fig. 13, the transceiver unit 2010 may be used to perform S1220 in the method 1200, and the processing unit 2020 may be used to perform S1210 in the method 1200.

Specifically, the apparatus 2000 may include: a processing unit 2020, configured to orthogonal frequency division multiplex, OFDM, transmission modes from among candidate transmission modes, the candidate transmission modes including a first mode in which the OFDM signal includes a cyclic prefix and a second mode in which the OFDM signal does not include the cyclic prefix; 2010 for transmitting OFDM signals according to the OFDM transmission mode.

In some possible implementations, the transceiver 2020 is further configured to: receiving third information, and determining the OFDM transmission mode from the candidate transmission modes according to the third information; wherein the third information is used for indicating that the OFDM transmission mode is the first mode or the second mode; alternatively, the third information is used to indicate the received signal-to-noise ratio of the channel.

In some possible implementations, the processing unit 2010 is further configured to: when the third information is used for indicating the received signal-to-noise ratio, determining the OFDM transmission mode from the candidate transmission modes according to the received signal-to-noise ratio and a mode parameter, wherein the mode parameter is used for indicating a switching boundary of the OFDM transmission mode.

In some possible implementations, the mode parameters include a SNR switching boundary, the OFDM transmission mode is determined from the candidate transmission modes based on the received SNR and the mode parameters, and the processing unit 2010 is further configured to: when the received signal-to-noise ratio is smaller than the SNR switching boundary, determining the OFDM transmission mode as the first mode; and when the received signal-to-noise ratio is greater than or equal to the SNR switching boundary, determining the OFDM transmission mode as the second mode.

In some possible implementations, the transceiver 2020 is further configured to: and transmitting second indication information, wherein the second indication information is used for indicating the OFDM transmission mode.

In some possible implementations, the transceiver 2020 is further configured to: transmitting fourth information, where the fourth information is used to indicate a switching boundary of the OFDM transmission mode corresponding to a first parameter, and the first parameter includes at least one of: scene, modulation mode, antenna configuration, data stream number, channel space correlation coefficient, service type.

In some possible implementations, the transceiver 2020 is further configured to: and sending first information, wherein the first information is used for indicating the candidate transmission modes supported by different area positions.

In some possible implementations, the transceiver 2020 is further configured to: receiving second information, the second information being used to indicate capability information, the capability information comprising at least one of: support the first mode, support the second mode, support the first mode and the second mode, or support the first mode and not support the second mode; the OFDM transmission mode is determined based on the second information.

The processing unit 2020 in fig. 15 may be implemented by at least one processor or processor-related circuit, the transceiver unit 2010 may be implemented by a transceiver or transceiver-related circuit, and the storage unit may be implemented by at least one memory.

Fig. 16 is a schematic block diagram of an apparatus for determining a transmission mode according to an embodiment of the present application. The apparatus 2100 for determining a transmission mode shown in fig. 16 may include: a processor 2110, a transceiver 2120, and a memory 2130. Wherein the processor 2110, the transceiver 2120 and the memory 2130 are connected through an internal connection path, the memory 2130 is used for storing instructions, and the processor 2110 is used for executing the instructions stored in the memory 2130, so that the transceiver 2130 receives/transmits a part of parameters. Alternatively, the memory 2130 may be coupled to the processor 2110 through an interface or may be integrated with the processor 2110.

It should be noted that the transceiver 2120 may include, but is not limited to, a transceiver device such as an input/output interface (i/o interface) to enable communication between the communication device 2100 and other devices or communication networks.

In implementation, the steps of the above method may be performed by integrated logic circuitry in hardware or instructions in software in the processor 2110. The method disclosed in connection with the embodiments of the present application may be embodied directly in hardware processor execution or in a combination of hardware and software modules in a processor. The software modules may be located in a random access memory, flash memory, read only memory, programmable read only memory, or electrically erasable programmable memory, registers, etc. as well known in the art. The storage medium is located in the memory 2130, and the processor 2110 reads information in the memory 2130 and performs the steps of the method in combination with its hardware. To avoid repetition, a detailed description is not provided herein.

It should also be appreciated that in embodiments of the present application, the memory may include read only memory and random access memory, and provide instructions and data to the processor. A portion of the processor may also include nonvolatile random access memory. The processor may also store information of the device type, for example.

Embodiments of the present application also provide a computer readable storage medium storing program code that, when run on a computer, causes the computer to perform any of the methods of fig. 2, 6, 9, and 11-14 described above.

The embodiment of the application also provides a chip, which comprises: at least one processor and a memory, the at least one processor being coupled to the memory for reading and executing instructions in the memory to perform any of the methods of fig. 2, 6, 9 and 11-14 described above.

The method provided by the embodiment of the application can be applied to terminal equipment or network equipment, wherein the terminal equipment or network equipment comprises a hardware layer, an operating system layer running on the hardware layer and an application layer running on the operating system layer. The hardware layer includes hardware such as a central processing unit (central processing unit, CPU), a memory management unit (memory management unit, MMU), and a memory (also referred to as a main memory). The operating system may be any one or more computer operating systems that implement business processes through processes (processes), such as a Linux operating system, a Unix operating system, an Android operating system, an iOS operating system, or a windows operating system. The application layer comprises applications such as a browser, an address book, word processing software, instant messaging software and the like. In addition, in the embodiment of the present application, the specific configuration of the execution body of the method of transmitting a signal is not particularly limited, and the embodiment of the present application is only required to be able to perform communication in the method of transmitting a signal according to the embodiment of the present application by executing a program in which a code of the method of transmitting a signal of the embodiment of the present application is recorded, and for example, the execution body of the method of wireless communication of the embodiment of the present application may be a terminal device or a network device, or a functional module in the terminal device or the network device that is capable of calling a program and executing the program.

Furthermore, various aspects or features of embodiments of the present application may be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques. The term "article of manufacture" as used herein encompasses a computer program accessible from any computer-readable device, carrier, or media. For example, computer-readable media may include, but are not limited to: magnetic storage devices (e.g., hard disk, floppy disk, or magnetic tape, etc.), optical disks (e.g., compact Disk (CD), digital versatile disk (digital versatile disc, DVD), etc.), smart cards, and flash memory devices (e.g., erasable programmable read-only memory (EPROM), cards, sticks, key drives, etc.). Additionally, various storage media described herein can represent one or more devices and/or other machine-readable media for storing information. The term "machine-readable medium" can include, without being limited to, wireless channels and various other media capable of storing, containing, and/or carrying instruction(s) and/or data.

It should be appreciated that the processors referred to in the embodiments of the present application (e.g., processor 2110) may be central processing units (central processing unit, CPU), network processors (network processor, NP) or a combination of CPU and NP. The processor may further comprise a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (programmable logic device, PLD), or a combination thereof. The PLD may be a complex programmable logic device (complex programmable logic device, CPLD), a field-programmable gate array (field-programmable gate array, FPGA), general-purpose array logic (generic array logic, GAL), or any combination thereof.

It should also be appreciated that the memory referred to in embodiments of the present application (e.g., memory 2130) may be volatile memory or nonvolatile memory, or may include both volatile and nonvolatile memory. The nonvolatile memory may be a read-only memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an electrically Erasable EPROM (EEPROM), or a flash memory. The volatile memory may be random access memory (random access memory, RAM) which acts as an external cache.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, and are not repeated herein.

In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of elements is merely a logical functional division, and there may be additional divisions of actual implementation, e.g., multiple elements or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.

The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present application may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

The foregoing is merely specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present application, and the changes or substitutions are intended to be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method of determining a transmission mode, comprising:

determining an Orthogonal Frequency Division Multiplexing (OFDM) transmission mode from candidate transmission modes, wherein the candidate transmission modes comprise a first mode and a second mode, and wherein in the first mode, an OFDM signal comprises a cyclic prefix and in the second mode, the OFDM signal does not comprise the cyclic prefix;

and receiving an OFDM signal according to the OFDM transmission mode.

2. The method according to claim 1, wherein the method further comprises:

determining a mode parameter, wherein the mode parameter is used for determining a switching boundary of the OFDM transmission mode;

determining channel environment information;

the determining an OFDM transmission mode from the candidate transmission modes includes:

and determining the OFDM transmission mode from the candidate transmission modes according to the mode parameters and the channel environment information.

3. The method of claim 2, wherein the mode parameter is a relationship between a first parameter and a switching boundary of the OFDM transmission mode, wherein the first parameter comprises at least one of: scene, modulation mode, antenna configuration, data stream number, channel space correlation coefficient, service type.

4. A method according to claim 2 or 3, characterized in that the method further comprises:

receiving first information, wherein the first information is used for indicating the candidate transmission modes supported by different area positions;

and determining the OFDM transmission mode according to the first information.

5. The method according to any one of claims 2 to 4, wherein the determining a mode parameter comprises:

the mode parameters are determined from predefined transmission scheme information comprising a relation between a switching boundary of the OFDM transmission mode predefined by a protocol and a first parameter.

6. The method according to any of claims 2 to 5, wherein the channel environment information comprises a received signal-to-noise ratio, wherein the mode parameter comprises a signal-to-noise ratio, SNR, switching boundary, and wherein determining the OFDM transmission mode from the candidate transmission modes based on the mode parameter and channel environment information comprises:

when the received signal-to-noise ratio is smaller than the SNR switching boundary, determining the OFDM transmission mode as the first mode;

and when the received signal-to-noise ratio is greater than or equal to the SNR switching boundary, determining the OFDM transmission mode as the second mode.

7. The method according to any one of claims 1 to 6, further comprising:

and sending first indication information, wherein the first indication information is used for indicating the OFDM transmission mode.

8. The method of claim 7, wherein the first indication information is transmitted in combination with CSI feedback information or HARQ-ACK information.

9. The method according to any one of claims 1 to 8, further comprising:

transmitting second information, wherein the second information is used for indicating capability information, and the capability information comprises at least one of the following: the first mode is supported, the second mode is not supported, the first mode and the second mode are supported, or the first mode and the second mode are not supported.

10. A method of determining a transmission mode, comprising:

determining an orthogonal frequency division multiplexing, OFDM, transmission mode from among candidate transmission modes, the candidate transmission modes comprising a first mode and a second mode;

wherein in the first mode, the OFDM signal includes a cyclic prefix; in the second mode, the OFDM signal does not include a cyclic prefix;

And sending the OFDM signal according to the OFDM transmission mode.

11. The method of claim 10, wherein said determining an OFDM transmission mode from among candidate transmission modes comprises:

receiving third information, and determining the OFDM transmission mode from the candidate transmission modes according to the third information;

wherein the third information is used for indicating that the OFDM transmission mode is the first mode or the second mode; alternatively, the third information is used to indicate the received signal-to-noise ratio of the channel.

12. The method of claim 11, wherein when the third information is used to indicate the received signal-to-noise ratio, the method further comprises:

and determining the OFDM transmission mode from the candidate transmission modes according to the received signal-to-noise ratio and a mode parameter, wherein the mode parameter is used for indicating the switching boundary of the OFDM transmission mode.

13. The method of claim 12, wherein the mode parameters include a signal-to-noise ratio, SNR, switching boundary, and wherein the determining the OFDM transmission mode from the candidate transmission modes based on the received signal-to-noise ratio and the mode parameters comprises:

14. The method of claim 10, wherein prior to transmitting an OFDM signal according to the OFDM transmission mode, the method further comprises:

and sending second indication information, wherein the second indication information is used for indicating the OFDM transmission mode.

15. The method according to any of claims 10 to 14, wherein prior to said determining an OFDM transmission mode from among candidate transmission modes, the method further comprises:

transmitting fourth information, where the fourth information is used to indicate a switching boundary of the OFDM transmission mode corresponding to a first parameter, and the first parameter includes at least one of: scene, modulation mode, antenna configuration, data stream number, channel space correlation coefficient, service type.

16. The method according to any one of claims 10 to 15, further comprising:

and sending first information, wherein the first information is used for indicating the candidate transmission modes supported by different area positions.

17. The method according to any one of claims 10 to 16, further comprising:

Receiving second information, wherein the second information is used for indicating capability information, and the capability information comprises at least one of the following: support the first mode, support the second mode, not support the second mode, support the first mode and the second mode, or support the first mode and not support the second mode;

and determining the OFDM transmission mode according to the second information.

18. An apparatus for determining a transmission mode, comprising:

a processing unit, configured to orthogonal frequency division multiplex, OFDM, transmission modes from candidate transmission modes, where the candidate transmission modes include a first mode in which an OFDM signal includes a cyclic prefix and a second mode in which the OFDM signal does not include the cyclic prefix;

and the receiving and transmitting unit is used for receiving the OFDM signals according to the OFDM transmission mode.

19. The apparatus of claim 18, wherein the apparatus is further configured to perform the method of any one of claims 2 to 9.

20. An apparatus for determining a transmission mode, comprising:

a processing unit that determines an orthogonal frequency division multiplexing, OFDM, transmission mode from among candidate transmission modes, the candidate transmission modes including a first mode in which an OFDM signal includes a cyclic prefix and a second mode in which the OFDM signal does not include the cyclic prefix;

And the receiving and transmitting unit is used for transmitting the OFDM signals according to the OFDM transmission mode.

21. The apparatus of claim 20, wherein the apparatus is further configured to perform the method of any one of claims 11 to 17.

22. An apparatus for determining a transmission mode, comprising:

a transceiver for receiving and transmitting messages;

a memory for storing a computer program;

a processor for executing the computer program stored in the memory to cause the apparatus to perform the method of any one of claims 1 to 17; the processor is coupled with the memory.

23. A system for determining a transmission mode, comprising an apparatus as claimed in claim 18 or 19.

24. A system for determining a transmission mode, comprising the apparatus of claim 20 or 21.

25. A computer-readable storage medium, on which a computer program is stored which, when executed by a computer, causes the method of any one of claims 1 to 17 to be implemented.

26. A chip comprising a processor and a data interface, the processor reading instructions stored on a memory via the data interface to perform the method of any one of claims 1 to 17.