Abstract: A frequency synthesis system and a frequency generation method of microwave photons based on photoelectric synergy are provided, the system includes an optical frequency comb for generating narrow optical pulse signals with high stability and low phase noise through; an optical frequency doubling/dividing unit for performing frequency doubling or frequency dividing on a repetition frequency of the narrow optical pulse signals output by the optical frequency comb; a photoelectric conversion unit for performing photoelectric conversion on input optical pulse signals, and outputting an electrical frequency comb; a second electrical filter unit for filtering input electrical signals; and a second electrical amplifying unit for performing power amplification on the input electrical signals.

Abstract: Method, terminal device, and storage medium of displaying a user interface are provided. The method includes obtaining an initial contact point of a user on a display component, the display component including two or more different position areas; determining a position area to which the initial contact point belongs in the display component based on position information of the initial contact point on the display component, the two or more different position areas corresponding to different angle thresholds; and controlling the user interface to display in the display component, based on a sliding operation of the user starting from the initial contact point and an angle threshold corresponding to the position area to which the initial contact point belongs in the display component.

Abstract: The present disclosure provides an image display method, device, gimbal and storage medium. The gimbal includes: at least two gimbal frames configured to stabilize a camera device carried by the gimbal; a user interface; a memory configured to store program instructions; and a processor. The processor is configured to execute the program instructions to perform: determining a display mode of an image data to be displayed on a user interface; adjusting the image data according to the display mode to obtain a target image; and displaying the target image on the user interface.

Abstract: A tracking shot method includes determining object feature information used to describe a target object based on a tracking trigger operation, obtaining display position information of the target object set on a screen displaying a preview image, and controlling an imaging device to perform tracking shot on the target object to obtain a target image based on the object feature information and the display position information.

Abstract: Allocation schemes are provided for one or more portions of time during a data transmission time interval for contention by personal coordination points, access points and client devices to perform transmit sector sweep operations. In addition, a personal coordination point determines whether the set of channels universally agreed to be free by nearby synchronization access points is empty and selects any channel in the frequency band to initiate a Basic Service Set or continue operation of an existing Basic Service Set if it is determined that no channel in the frequency band is free among the channels that are universally agreed to be free.

Abstract: Techniques are provided herein for improving multiple-input multiple-output (MIMO) wireless communications, and in particular to dynamically determining when to switch MIMO transmission modes on a communication link between two devices that are capable of supporting multiple MIMO transmission modes. A base station receives from a client device one or more signals containing information representing a first signal-to-noise ratio (SNR) measurement and a second SNR measurement made by the client device. The first SNR measurement is associated with a first MIMO transmission mode and the second SNR measurement is associated with a second MIMO transmission mode. The base station computes a MIMO channel quality indicator from the first SNR measurement and the second SNR measurement, and evaluates the MIMO channel quality indicator to determine whether to switch MIMO transmission modes for transmissions to the client device.

Abstract: Techniques are provided for generating a precoding matrix for a multi-user multiple-input multiple-output wireless communication system. A first wireless communication device is provided that has a plurality of antennas from which multiple spatial streams are to be simultaneously transmitted to a plurality of second wireless communication devices. A channel matrix is computed between the antennas of the first device and the antennas of each of the second wireless communication devices to produce a plurality of client-specific channel matrices. A singular value decomposition is computed of each client-specific channel matrices. A number of strongest singular values and their corresponding singular vectors are stored from the singular decomposition of each of the client-specific channel matrices. From each client-specific channel matrix, a principal component-like single-client channel matrix is computed.

Abstract: Techniques are provided for generating a precoding matrix for a multi-user multiple-input multiple-output wireless communication system. A first wireless communication device is provided that has a plurality of antennas from which multiple spatial streams are to be simultaneously transmitted to a plurality of second wireless communication devices. A channel matrix is computed between the antennas of the first device and the antennas of each of the second wireless communication devices to produce a plurality of client-specific channel matrices. A singular value decomposition is computed of each client-specific channel matrices. A number of strongest singular values and their corresponding singular vectors are stored from the singular decomposition of each of the client-specific channel matrices. From each client-specific channel matrix, a principal component-like single-client channel matrix is computed.

Abstract: Techniques are provided for computing downlink beamforming weights based on the received data at a base station from a mobile station in a MIMO communication system. An uplink transmission is received at a plurality of antennas at a first communication device from a second communication device, where the uplink transmission comprises a plurality of uplink subbands. The uplink spatial signature is estimated for each of the plurality of uplink subbands. The uplink spatial signature is decomposed into a plurality of direction of arrival (DOA) components for each uplink subband using a transform. Data representing multiple propagation paths between the first communication device and the second communication device is computed for each DOA component. A plurality of direction of departure (DOD) components for each of a plurality of downlink subbands is computed based on the data representing the multiple propagation paths.

Abstract: The present invention discloses a method for generating a signal stream in a multiple-input-multiple-output (MIMO) channel of a wireless communications system. The method comprises encoding at least one transmitting message into a first signal sequence, transforming the first signal sequence into a second and a third signal sequence by a first and a second predetermined rule, respectively, coupling the second signal sequence to a first antenna, coupling the third signal sequence to a second antenna, transmitting a signal stream comprising the first and second signal sequences to a mobile station.

Abstract: Techniques are provided to improve wireless beamformed communication between first and second wireless communication devices. At a plurality of antennas of the first wireless communication device (e.g., a base station) uplink transmissions sent from the second wireless communication device (e.g., a client or mobile device or station) are received. The first wireless communication device generates a downlink beamforming weight vector from received uplink transmissions, and computes a covariance matrix for received uplink transmissions. The first wireless communication device stores history information based on the covariance matrices for received uplink transmissions. The first wireless communication device computes first and second beamforming-space time code weight vectors based on the covariance matrix for an uplink transmission received in a current frame and the history information.

Abstract: Techniques are provided for improving performance of a multiple-input multiple-output (MIMO) wireless communication system. At a first wireless communication device (e.g., a base station) having a plurality of antennas, uplink transmissions are received from a second wireless communication device (e.g., a client device). The base station determines a measure of multipath conditions between it and the second wireless communication device based on the received uplink transmissions. The base station applies downlink beamforming weight vectors together with power balance and phase adjustment factors depending on the measure of multipath conditions to transmit multiple downlink data streams across the plurality of antennas simultaneously to the second wireless communication device.

Abstract: A dynamically adaptive channel estimation process is provided for use in a wireless communication device. At a first device, a wireless transmission is received from a second device. The transmission comprises a plurality of successive symbols each of which comprises a plurality of subcarriers. The first device is configured to compute channel characterizing information for a wireless channel between the first device and the second device based on the received values at subcarriers of the successive symbols. The first device is configured to select one of a plurality of channel estimation schemes based on the channel characterizing information, and to compute an estimate of channel information for the wireless channel using the selected one of the plurality of channel estimation schemes.

Abstract: Techniques are provided to performing beamforming on a wireless communication link that employs multi-carrier code division multiple access (MC-CDMA) signal formatting techniques. At a first wireless communication device, a waveform is received at each of a plurality of antennas, where the waveform comprises a multi-carrier code division multiple access ranging transmission from each of one or more of a plurality of second wireless communication devices such that MC-CDMA ranging transmissions from two or more second wireless communication devices overlap in time and frequency. All codes in a set of possible codes that may be used by the second wireless communication devices are searched to determine whether which codes in the set are present in the one or more MC-CDMA ranging transmissions contained in the received waveform.

Abstract: A first wireless communication device recovers data from a transmission received over a wireless channel from a second wireless communication device and processes the received data with each of multiple channel variation compensations to produce corresponding processed received data subjected to respective ones of the multiple channel variation compensations. For symbols in the received data and in each of the processed received data, distances are computed to their closest symbols in a symbol constellation set used in the wireless transmission. A corresponding distance metric is computed from the distances for symbols in the received data and from the distances for symbols in each of the processed received data resulting in a distance metric for the received data, and a distance metric for each of the processed received data. Channel variation of a wireless channel between the first and second wireless communication devices is estimated based on the distance metrics.

Abstract: The present invention discloses a method for selecting a transmission scheme in a multiple-input-multiple-output (MIMO) wireless communications system. The method comprises receiving a downlink request to transmit a data stream to a wireless station, checking the availability of channel state information (CSI) associated with the wireless station, determining the validity characteristic of beamforming weighting vectors associated with the wireless station, selecting a transmission scheme from a plurality of predetermined transmission schemes based on the availability of the CSI and the validity characteristic of the beamforming weighting vectors.

Abstract: Techniques are provided herein to estimate channel information based a received burst that is comprises of consecutive transmissions. Each transmission comprises a plurality of data subcarriers and a plurality of pilot subcarriers on a radio frequency (RF) channel, wherein locations of the pilot subcarriers in the consecutive transmissions are different. Channel information at the pilot subcarriers is computed for each transmission in the burst. A time variation parameter and a frequency variation parameter of the channel for the burst are computed using the channel information at the pilot subcarriers for the transmissions in the burst. Channel information for at least one data subcarrier of a transmission in the burst is computed by interpolation and/or extrapolation of the channel information at the pilot subcarriers using the time variation parameter and the frequency variation parameter.

Abstract: The present invention discloses a method for estimating a channel response of data subcarriers in a wireless communications network. The method comprises estimating a first plurality of channel responses of pilot subcarriers carrying pilot signals at the time instance using pilot signals, generating a pseudo time instance for pilot subcarriers according to a predetermined rule, approximating a second plurality of channel responses at the pseudo time instance using the first plurality of channel responses, computing a rate of change in the channel response using the first and second plurality of channel responses, calculating a third plurality of channel responses of pilot subcarriers carrying data at the time instance using the first plurality of channel responses and the rate of change in the channel response, estimating the channel response of the data subcarriers from the first and third plurality of channel responses using a predetermined conventional two-dimensional channel estimation algorithm.

Abstract: An adaptive transmission selection technique is provided. A retransmission scheme is selected for a multiple-input-multiple-output wireless system. A plurality of communication techniques is provided for when a first device needs to retransmit a signal to a second device. The first device determines when the original signal, transmitted to the second device using beamforming techniques, needs to be retransmitted to the second device. If a retransmission is needed, the first device determines channel conditions with respect to the second device. The first device selects a retransmission scheme from a plurality of transmission schemes based on the channel conditions for retransmitting the signal. A first retransmission technique is selected when the channel conditions are static. A second retransmission technique is selected when the channel conditions are relatively slowly changing, and a third retransmission technique is selected when the channel conditions are relatively quickly changing.

Abstract: Techniques are provided to enable wireless communication between first and second wireless communication devices each having a plurality of antennas, where the second device sends the transmissions via less than all of its plurality of antennas. Each transmission may comprise a plurality of time-frequency instances. At the first communication device, data is derived representing parameters of a communication channel between the plurality of antennas of the first device and all of the plurality of antennas of the second device from the transmissions received at the plurality of antennas of the first device. Beamforming weights for transmitting one or more signal streams via the plurality of antennas of the first device to the plurality of antennas of the second device are computed based on the data representing parameters of the communication channel between the plurality of antennas of the first device and the plurality of antennas of the second device.