This document describes techniques and systems for independent transmit and receive channel calibration for multiple-input multiple-output (MIMO) systems. Antenna responses are collected from each virtual channel of a MIMO system at an angle respective to an object. The transmit components and the receive components of the virtual channels are separated and organized into vectors (one for the transmit components and one for the receive components). Calibration values for elements of the vectors are computed and maintained in a transmit calibration matrix and a receive calibration matrix, respectively. Together, the transmit calibration matrix and the receive calibration matrix may include fewer elements than a calibration matrix for the virtual channels and, therefore, may require less memory and fewer computations to calibrate a MIMO system than using other calibration techniques. As such, described is a less expensive and less complex way to calibrate MIMO system by accurately approximating an ideal antenna array.

Embodiments of the present disclosure provide a server data sending method and a server data sending apparatus. The method can include: acquiring, by a server, crystal oscillator error information and operating rate information of a terminal; setting, by the server, preamble length information according to the crystal oscillator error information and the operating rate information; and sending, by the server, a downlink data frame to the terminal, the downlink data frame comprising a preamble aligned with the preamble length information.

Embodiments of the present disclosure provide a server data sending method and a server data sending apparatus. The method can include: acquiring, by a server, crystal oscillator error information and operating rate information of a terminal; setting, by the server, preamble length information according to the crystal oscillator error information and the operating rate information; and sending, by the server, a downlink data frame to the terminal, the downlink data frame comprising a preamble aligned with the preamble length information.

Radio Frequency (RF) circuit (amplifiers, mixer, etc.) design with RFIC, e.g., implemented in CMOS, CaAs, SiGe, or other silicon processes, suffers performance variations (gain phase, frequency, bandwidth, nonlinearity) due to wafer process variations, temperature changes, and supply voltage changes, and random variations. In this invention, methods are proposed to precisely calibrate the bias current of all active devices in the system, and to precisely calibrate the gain of individual path leading to each amplifiers such that the same Pout is achieved for all antenna elements in the system.

Radio Frequency (RF) circuit (amplifiers, mixer, etc.) design with RFIC, e.g., implemented in CMOS, CaAs, SiGe, or other silicon processes, suffers performance variations (gain phase, frequency, bandwidth, nonlinearity) due to wafer process variations, temperature changes, and supply voltage changes, and random variations. In this invention, methods are proposed to precisely calibrate the bias current of all active devices in the system, and to precisely calibrate the gain of individual path leading to each amplifiers such that the same Pout is achieved for all antenna elements in the system.

A radio frequency receiving link and a radio frequency transceiving device are provided. The radio frequency receiving link includes: an input unit, configured to input a first input signal; a clock unit, configured to generate a local oscillator signal; a receiving link frequency-mixing unit, configured to obtain the first input signal and the local oscillator signal, and generate a first frequency-mixing signal according to the first input signal and the local oscillator signal; and a calibration unit, configured to obtain first direct current offset information of the radio frequency receiving link, wherein the first direct current offset information is direct current offset information in the radio frequency receiving link when the receiving link frequency-mixing unit generates the first frequency-mixing signal.

An electronic device is provided. The electronic device includes a communication circuit, a memory configured to store a learning model, and at least one processor, wherein the at least one processor is configured to obtain data related to a network situation of a base station from the communication circuit, calculate a performance indicator value related to network performance according to a performance indicator, based on the data related to the network situation, train the model, based on the performance indicator value calculated according to the performance indicator, determine an off threshold of traffic for turning off a cell, based on the trained model, and transmit the determined off threshold to the base station via the communication circuit.

An electronic device is provided. The electronic device includes a communication circuit, a memory configured to store a learning model, and at least one processor, wherein the at least one processor is configured to obtain data related to a network situation of a base station from the communication circuit, calculate a performance indicator value related to network performance according to a performance indicator, based on the data related to the network situation, train the model, based on the performance indicator value calculated according to the performance indicator, determine an off threshold of traffic for turning off a cell, based on the trained model, and transmit the determined off threshold to the base station via the communication circuit.

A method and system for outputting a state of a physical system using a calibrated model of the physical system, where the calibrated model is used to generate a model prediction. The system includes a plurality of sensors connected to a routing node are used to monitor measured data of the physical system. A first sensor of the plurality of sensors includes a logic module configured to determine an uncertainty quantification, and to combine the uncertainty quantification with the model prediction to output the state of the physical system.

A method and system for outputting a state of a physical system using a calibrated model of the physical system, where the calibrated model is used to generate a model prediction. The system includes a plurality of sensors connected to a routing node are used to monitor measured data of the physical system. A first sensor of the plurality of sensors includes a logic module configured to determine an uncertainty quantification, and to combine the uncertainty quantification with the model prediction to output the state of the physical system.