Adaptive downlink transmission switching method in air-ground broadband communication system

Abstract

The invention relates to the technical field of air-ground bandwidth communication, in particular to a self-adaptive downlink transmission switching method in an air-ground bandwidth communication system. The adaptive downlink transmission switching method in the air-ground bandwidth communication system specifically comprises the steps of base station resource configuration, base station data transmission, terminal measurement reporting and base station shaping selection, multiple sets of single-port CSI-RS resources are ingeniously configured through a base station, weights of different transmission modes act on the CSI-RS resources, and the CSI-RS resources are transmitted through the base station. A plurality of sets of CSI-RS resources are sent to a terminal, after the terminal receives the CSI-RS resources, channel quality measurement is carried out, RSRP obtained through measurement is fed back to a base station through an uplink channel, the base station further determines the CSI-RS resource corresponding to the optimal RSRP through a screening mechanism, and therefore the optimal transmission mode of the point is accurately judged. In order to ensure the accuracy of measurement results and avoid the influence of accidental errors, the base station is triggered to switch the downlink transmission mode only when three continuous measurement results point to the same transmission mode.

Description

Technical Field

[0001] The present invention relates to the technical field of air-to-ground broadband communication, and in particular to an adaptive downlink transmission switching method in an air-to-ground broadband communication system. Background Art

[0002] In the field of air-to-ground broadband communication (ATG), beamforming technology for downlink transmission data has become the key to improving the quality of signal reception and transmission. At present, the mainstream beamforming methods in air-to-ground broadband communication systems include broadcast beamforming (BC beamforming), precoding matrix indication (PMI beamforming), and angle of arrival (DOA beamforming). They have their own characteristics and are suitable for different scenarios. Appropriate downlink data beamforming transmission can significantly improve channel transmission quality and reduce signal interference and fading. At the same time, by accurately controlling the beam direction of the signal, it can also ensure that the signal is delivered to the target user more accurately.

[0003] At present, the specific selection of the shaping mode is based on whether the terminal reports the corresponding information. If the terminal reports GPS information, DOA shaping is selected; if the terminal does not report GPS but reports PMI, PMI shaping is selected; if the terminal does not report both GPS and PMI feedback, BC shaping is selected. This shaping mode switching selects different shaping modes based on whether the terminal reports relevant information, and does not estimate the gains of the three shaping modes in advance. The selection is not the optimal shaping mode, which is bound to affect the downlink channel quality and downlink services. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in order to solve the problems existing in the prior art in the above-mentioned background technology, an adaptive downlink transmission switching method in an air-to-ground bandwidth communication system is provided.

[0005] The technical solution adopted by the present invention to solve the technical problem is: an adaptive downlink transmission switching method in an air-to-ground bandwidth communication system, comprising the following steps: S1. Base station resource configuration: configure each CSI-RS resource as a single-port resource, configure reportQuantity in CSI-ReportConfig as cri-RSRP, set startingRB to 0 in the frequency domain configuration of CSI-RS, and set nroRBs to full bandwidth. The number of CSI-RS resources included in the CSI-RS resource set matches the number of SSB and PMI resources configured by the base station. S2, base station data transmission: The base station first channels the original bit data, converts the encoded bit-level data into an analog signal through modulation, allocates the analog signal data to the resource elements to be determined, and then maps it to the frequency domain position configured by the base station. By selecting the appropriate shaping mode and converting from the frequency domain to the time domain, the data signal is transmitted to the terminal through the antenna. The calculation formula is as follows: (1), In formula (1), Indicates the frequency domain data of the transmitted CSI-RS resources. Indicates the corresponding shaping weight of each CSI-RS resource, Indicates the data after CSI-RS resource modulation; S3, terminal measurement reporting: The base station sends the configuration information of the cell CSI-RS resources to the terminal through signaling messages. The terminal evaluates the reception performance of each beam in the current environment, selects the optimal reference RSRP value and the corresponding optimal beam in each beamforming mode, and feeds back the result to the base station through uplink UCI control information; S4, base station shaping selection: The base station receives the CRI and RSRP values ​​fed back by the uplink terminal, obtains the optimal beam through comparison, finds the weight of the shaping mode used by the optimal beam, and measures through three consecutive cycles. If the optimal beams all point to the same shaping mode, the shaping mode switching is triggered.

[0006] Furthermore, in step S1, if the base station configures m SSB resources and n PMI beams, the corresponding SSB measurement CSI-RS resources need to be configured with m sets and the PMI measurement resources need to be configured with n sets. At the same time, 1 set of CSI-RS resources under DOA weights needs to be configured, and the parameters of the above CSI-RS resources remain consistent.

[0007] Furthermore, in step S2, if the appropriate shaping mode is BC shaping, its weight is generated as follows: Assume that the number of antennas is M, the angle between the antenna and the normal is θ, and the antenna spacing is d , wavelength is λ, j is an imaginary unit, then the channel response of the M antennas relative to the first antenna forms the steering vector as follows: (2), From formula (2), we can get the steering vectors of vertical and horizontal weights: (3), (4), In formula (3), Indicates the horizontal amplitude, Indicates the horizontal phase; In formula (4), Indicates the vertical amplitude, Indicates the vertical phase; By taking the inner product of equation (3) and equation (4), we can get the weight of the entire antenna. The calculation formula is as follows: , Combined with the beam quadruple of SSB, the BC weights of different beams are obtained, and the BC weights are applied to the CSI-RS resources for transmission.

[0008] Further, in step S2, if the appropriate beamforming mode is PMI beamforming, a codebook for beamforming is generated according to the number of CSI ports sent by the base station and the terminal feedback parameter. According to the mapping relationship between CSI ports and antennas, the codebook of the port dimension is mapped to the antenna dimension and combined with the BC weight of each antenna Multiply, as follows: (5), The weight corresponding to the PMI assignment is obtained, and the weight is applied to the CSI-RS resource corresponding to the PMI assignment for transmission.

[0009] Further, in step S2, if the appropriate shaping mode is DOA shaping, the terminal feeds back its own position to the base station, so that the base station can calculate the horizontal angle Φ and vertical angle θ of the terminal relative to itself at this time, and obtain the steering vector by looking up the weighted steering vector table stored in the baseband. and , the inner product of the two-directional steering vectors is expanded to the entire antenna weight. Taking 64 antennas as an example, since the antenna array has dual polarization, the calculation of 32 antennas is as follows: , in, iHant Indicates the horizontal antenna index, the value range is 1 to 8. iVant Indicates the vertical antenna index, the value range is 1 to 4; floor It represents the inner product of the steering vectors in two directions; use The weights of the first 32 antennas are obtained. The weights of the two polarized antennas are concatenated to obtain the overall antenna weight. The overall antenna weight is calculated as follows: (6), The weight corresponding to the DOA shaping is obtained, and the weight is applied to the CSI-RS resource corresponding to the DOA shaping for transmission.

[0010] Furthermore, in step S3, the configuration information of the cell CSI-RS resources includes the transmission time, frequency position and antenna port parameters of the CSI-RS, so that the terminal can accurately receive and analyze these signals; when the terminal receives the CSI-RS, it will use channel estimation technology to calculate the RSRP of each CSI-RS resource. By measuring the RSRP of different CSI-RS resources, the terminal can evaluate the receiving performance of each beam in the current environment, and further screen out the optimal RSRP value and the corresponding optimal beam under each shaping mode.

[0011] Beneficial effects of the present invention: The present invention skillfully configures multiple sets of single-port CSI-RS resources through a base station, applies weights of different transmission modes to CSI-RS resources, and sends them to a terminal through multiple sets of CSI-RS resources. After receiving these CSI-RS resources, the terminal performs channel quality measurement and feeds back the measured RSRP to the base station through an uplink channel. The base station further determines the CSI-RS resource corresponding to the optimal RSRP through a screening mechanism, thereby accurately determining the optimal transmission mode of the point. To ensure the accuracy of the measurement result and avoid the influence of accidental errors, the base station is triggered to switch the downlink transmission mode only when three consecutive measurement results all point to the same transmission mode, thereby enhancing the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0013] Figure 1 It is a flow chart of the present invention.

[0014] Figure 2 It is a control block diagram of the present invention. DETAILED DESCRIPTION

[0015] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0016] CSI-RS: Channel State Information Reference Signal, mainly used for: a. Acquisition of downlink channel state information: UE (user equipment) measures CSI-RS and reports the measurement results to the base station. The base station implements switching, channel-dependent scheduling and link adaptation based on this information; b. Beam management: used to obtain the shaping weights of the beams at the UE (user equipment) and base station side, and supports the beam management process; CSI-RS measurements include CSI-RSRP (reference signal received power), CSI-RSRQ (reference signal received quality), CSI-RSSI (reference signal received strength indication) and CSI-SINR (reference signal interference and noise ratio). These measurements are crucial for network optimization and scheduling decisions. This embodiment measures CSI-RSRP (reference signal received power), which can reflect the distance between the UE (user equipment) and the base station to a certain extent.

[0017] like Figure 1 As shown, an adaptive downlink transmission switching method in an air-to-ground bandwidth communication system comprises the following steps: S1. Base station resource configuration: configure each CSI-RS resource as a single-port resource, configure reportQuantity in CSI-ReportConfig to cri-RSRP, set startingRB to 0 in the frequency domain configuration of CSI-RS, and set nroRBs to full bandwidth. The number of CSI-RS resources included in the CSI-RS resource set matches the number of SSB and PMI resources configured by the base station. If the base station is configured with m SSB resources and n PMI beams, then the corresponding SSB measurement CSI-RS resources need to be configured with m sets and PMI measurement resources need to be configured with n sets. At the same time, 1 set of CSI-RS resources under DOA weights needs to be configured, and the parameters of the above CSI-RS resources remain consistent.

[0018] Among them, CSI-RS is configured as a single port resource, which means that in a resource block (RB), CSI-RS only occupies one resource element (RE). CSI-ReportConfig is used to configure the parameters of CSI reporting, including the periodicity, offset, and number and type of reports. The reportQuantity in CSI-ReportConfig is configured as cri-RSRP, indicating that the UE (user equipment) needs to report CRI (CSI-RS resource indicator) and related RSRP (reference signal received power) values.

[0019] SSB: Synchronization Signal Block, which provides the initial time and frequency synchronization signals to help UE (user equipment) synchronize with the base station when accessing the network; it is sent periodically on beams in different directions. UE (user equipment) can select the optimal beam by measuring the SSB signal strength on each beam to achieve beam tracking and optimal connection.

[0020] PMI: It is used to indicate the feedback information of the precoding matrix and is closely related to the CSI-RS resource configuration. The configuration of PMI needs to consider the number of CSI-RS ports and the codebook type.

[0021] Precoding is an adaptive technology in multi-antenna systems, that is, according to the channel state information (CSI), the precoding matrix is ​​adaptively changed at the transmitter to change the channel that the signal passes through. A set of codebooks containing several precoding matrices is stored at both the transmitter and the receiver, so that the receiver can select one of the precoding matrices according to the estimated channel matrix and a certain criterion, and feed back its index value and quantized channel state information to the transmitter; at the next moment, the transmitter adopts a new precoding matrix and determines the coding and modulation method for the codeword based on the feedback of the channel state quantization information.

[0022] The frequency domain configuration of CSI-RS is given by the freqBand parameter in the CSI-RS-ResourceMapping IE, where startingRB (starting RB of CSI resource) is set to 0, indicating that CSI-RS is configured from the beginning of the frequency band, and nrofRBs (number of cell material resources) is set to full bandwidth, that is, covering the width of the entire BWP (wideband piece).

[0023] S2, base station data transmission: The base station first channels the original bit data, converts the encoded bit-level data into an analog signal through modulation, allocates the analog signal data to the resource elements to be determined, and then maps it to the frequency domain position configured by the base station. By selecting the appropriate shaping mode and converting from the frequency domain to the time domain, the data signal is transmitted to the terminal through the antenna. The calculation formula is as follows: (1), In formula (1), Indicates the frequency domain data of the transmitted CSI-RS resources. Indicates the corresponding shaping weight of each CSI-RS resource, Indicates the data after CSI-RS resource modulation.

[0024] If the appropriate shaping mode is BC shaping, its weights are generated as follows: Assume that the number of antennas is M, the angle between the antenna and the normal is θ, and the antenna spacing is d , wavelength is λ, j is an imaginary unit, then the channel response of the M antennas relative to the first antenna forms the steering vector as follows: (2), From formula (2), we can get the steering vectors of vertical and horizontal weights: (3), (4), In formula (3), Indicates the horizontal amplitude, Indicates the horizontal phase; In formula (4), Indicates the vertical amplitude, Indicates the vertical phase; By taking the inner product of equation (3) and equation (4), we can get the weight of the entire antenna. The calculation formula is as follows: , Combined with the SSB beam quadruple (horizontal beam width, vertical beam width, azimuth angle, downtilt angle), the BC weights of different beams are obtained, and the BC weights are applied to the CSI-RS resources for transmission.

[0025] PMI beamforming is performed by the terminal according to the CSIRS signal to measure the channel, and at the same time matches the measurement result according to the codebook specified in the protocol, and reports the channel codebook index that best matches the current one to the base station, and the base station performs beamforming according to the reported codebook.

[0026] If the appropriate beamforming mode is PMI beamforming, the codebook used for beamforming is generated according to the number of CSI ports sent by the base station and the terminal feedback parameters. According to the mapping relationship between CSI ports and antennas, the codebook of the port dimension is mapped to the antenna dimension and combined with the BC weight of each antenna Multiply, as follows: (5), The weight corresponding to the PMI shaping is obtained, and the weight is applied to the CSI-RS resource corresponding to the PMI shaping for transmission; BC shaping is the most basic shaping method, where the PMI shaping weight is obtained by multiplying the BC weight by the PMI codebook.

[0027] DOA shaping is sent according to the arrival angle of the incident signal. The space is divided horizontally and vertically, and each part corresponds to a steering vector. Combined with the antenna morphology and theoretical simulation, the antenna weight corresponding to each steering vector is stored in the base station.

[0028] If the appropriate beamforming mode is DOA beamforming, the terminal feeds back its own position to the base station, so that the base station can calculate the horizontal angle Φ and vertical angle θ of the terminal relative to itself at this time, and obtain the steering vector by looking up the weighted steering vector table stored in the baseband. and , the inner product of the two-directional steering vectors is expanded to the entire antenna weight. Taking 64 antennas as an example, since the antenna array has dual polarization, the calculation of 32 antennas is as follows: , in, iHant Indicates the horizontal antenna index, ranging from 1 to 8. iVantIndicates the vertical antenna index, the value range is 1 to 4; floor It represents the inner product of the steering vectors in two directions; use The weights of the first 32 antennas are obtained. The weights of the two polarized antennas are concatenated to obtain the overall antenna weight. The overall antenna weight is calculated as follows: (6), The weight corresponding to the DOA shaping is obtained, and the weight is applied to the CSI-RS resource corresponding to the DOA shaping for transmission.

[0029] S3. Terminal measurement reporting: The base station sends the configuration information of the cell CSI-RS resources to the terminal through signaling messages. This configuration information includes the transmission time, frequency position and antenna port parameters of the CSI-RS, so that the terminal can accurately receive and analyze these signals. When the terminal receives the CSI-RS, it uses channel estimation technology to calculate the RSRP of each CSI-RS resource. By measuring the RSRP of different CSI-RS resources, the terminal evaluates the receiving performance of each beam (i.e., different antenna shaping modes) in the current environment, and further selects the optimal reference RSRP value and the corresponding optimal beam (through the beam index CRI) under each shaping mode, and feeds the results back to the base station through the uplink UCI control information. Among them, UCI is a special information sent by the terminal to the base station, which is used to report various measurement and status information.

[0030] S4, base station shaping selection: The base station receives the CRI and RSRP values ​​fed back by the uplink terminal, obtains the optimal beam through comparison, finds the weight of the shaping mode used by the optimal beam, and measures through three consecutive cycles. If the optimal beams all point to the same shaping mode, the shaping mode switching is triggered.

[0031] The adaptive downlink transmission switching method in the air-to-ground bandwidth communication system of this implementation cleverly configures multiple sets of single-port CSI-RS resources through the base station, applies the weights of different transmission modes to the CSI-RS resources, and sends them to the terminal through multiple sets of CSI-RS resources. When the terminal receives these CSI-RS resources, it will measure the channel quality and feed back the measured reference signal received power (RSRP) to the base station through the uplink channel; the base station further determines the CSI-RS resource corresponding to the optimal RSRP through a screening mechanism, thereby accurately determining the optimal transmission mode at that point. In order to ensure the accuracy of the measurement results and avoid the influence of accidental errors, it is set that when three consecutive measurement results point to the same transmission mode, the base station will be triggered to switch the downlink transmission mode to ensure the stability of the system.

[0032] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. An adaptive downlink transmission switching method in an air-to-ground bandwidth communication system, characterized in that: The steps include: S1. Base station resource configuration: configure each CSI-RS resource as a single-port resource, configure reportQuantity in CSI-ReportConfig as cri-RSRP, set startingRB to 0 in the frequency domain configuration of CSI-RS, and set nroRBs to full bandwidth. The number of CSI-RS resources included in the CSI-RS resource set matches the number of SSB and PMI resources configured by the base station. S2, base station data transmission: The base station first channels the original bit data, converts the encoded bit-level data into an analog signal through modulation, allocates the analog signal data to the resource elements to be determined, and then maps it to the frequency domain position configured by the base station. By selecting the appropriate shaping mode and converting from the frequency domain to the time domain, the data signal is transmitted to the terminal through the antenna. The calculation formula is as follows: （1）， In formula (1), Indicates the frequency domain data of the transmitted CSI-RS resources. Indicates the corresponding shaping weight of each CSI-RS resource, Indicates the data after CSI-RS resource modulation; S3, terminal measurement reporting: The base station sends the configuration information of the cell CSI-RS resources to the terminal through signaling messages. The terminal evaluates the reception performance of each beam in the current environment, selects the optimal reference RSRP value and the corresponding optimal beam in each beamforming mode, and feeds back the result to the base station through uplink UCI control information; S4, base station shaping selection: The base station receives the CRI and RSRP values ​​fed back by the uplink terminal, obtains the optimal beam through comparison, finds the weight of the shaping mode used by the optimal beam, and measures through three consecutive cycles. If the optimal beams all point to the same shaping mode, the shaping mode switching is triggered.

2. The adaptive downlink transmission switching method in the air-to-ground bandwidth communication system according to claim 1, characterized in that: In step S1, if the base station configures m SSB resources and n PMI beams, the corresponding SSB measurement CSI-RS resources need to be configured with m sets and the PMI measurement resources need to be configured with n sets. At the same time, 1 set of CSI-RS resources under DOA weights needs to be configured, and the parameters of the above CSI-RS resources remain consistent.

3. The adaptive downlink transmission switching method in the air-to-ground bandwidth communication system according to claim 1, characterized in that: In step S2, if the appropriate shaping mode is BC shaping, its weight is generated as follows: Assume that the number of antennas is M, the angle between the antenna and the normal is θ, and the antenna spacing is d , wavelength is λ, j is an imaginary unit, then the channel response of the M antennas relative to the first antenna forms the steering vector as follows: （2）, From formula (2), we can get the steering vectors of vertical and horizontal weights: （3）， （4）， In formula (3), Indicates the horizontal amplitude, Indicates the horizontal phase; In formula (4), Indicates the vertical amplitude, Indicates the vertical phase; By taking the inner product of equation (3) and equation (4), we can get the weight of the entire antenna. The calculation formula is as follows: ， Combined with the beam quadruple of SSB, the BC weights of different beams are obtained, and the BC weights are applied to the CSI-RS resources for transmission.

4. The adaptive downlink transmission switching method in the air-to-ground bandwidth communication system according to claim 1, characterized in that: In step S2, if the appropriate beamforming mode is PMI beamforming, a codebook for beamforming is generated according to the number of CSI ports sent by the base station and the terminal feedback parameters. According to the mapping relationship between CSI ports and antennas, the codebook of the port dimension is mapped to the antenna dimension and combined with the BC weight of each antenna Multiply, as follows: （5）， The weight corresponding to the PMI assignment is obtained, and the weight is applied to the CSI-RS resource corresponding to the PMI assignment for transmission.

5. The adaptive downlink transmission switching method in the air-to-ground bandwidth communication system according to claim 1, characterized in that: In step S2, if the appropriate shaping mode is DOA shaping, the terminal feeds back its own position to the base station, so that the base station can calculate the horizontal angle Φ and vertical angle θ of the terminal relative to itself at this time, and obtain the steering vector by looking up the weighted steering vector table stored in the baseband. and , the inner product of the two-directional steering vectors is expanded to the entire antenna weight. Taking 64 antennas as an example, since the antenna array has dual polarization, the calculation of 32 antennas is as follows: ， in, iHant Indicates the horizontal antenna index, the value range is 1 to 8. iVant Indicates the vertical antenna index, the value range is 1 to 4; floor It represents the inner product of the steering vectors in two directions; use The weights of the first 32 antennas are obtained. The weights of the two polarized antennas are concatenated to obtain the overall antenna weight. The overall antenna weight is calculated as follows: （6）， The weight corresponding to the DOA shaping is obtained, and the weight is applied to the CSI-RS resource corresponding to the DOA shaping for transmission.

6. The adaptive downlink transmission switching method in the air-to-ground bandwidth communication system according to claim 1, characterized in that: In step S3, the configuration information of the cell CSI-RS resources includes the transmission time, frequency position and antenna port parameters of the CSI-RS, so that the terminal can accurately receive and analyze these signals; when the terminal receives the CSI-RS, it will use channel estimation technology to calculate the RSRP of each CSI-RS resource. By measuring the RSRP of different CSI-RS resources, the terminal can evaluate the receiving performance of each beam in the current environment, and further screen out the optimal RSRP value and the corresponding optimal beam under each shaping mode.

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