The present disclosure discloses a signal sending method and device. The method includes: receiving, by a base station, an uplink pilot signal sent by authorized user equipment, and determining a direction vector parameter and a first channel fading parameter of a channel calculating, according to the direction vector parameter and the first channel fading parameter, a first signal beamformer parameter, determining a transmission area of an artificial noise signal according to the direction vector parameter, and calculating a second signal beamformer parameter; and processing a to-be-transmitted signal by using the first signal beamformer parameter and the second signal beamformer parameter, and transmitting the processed signal. In this way, in a non-target direction, energy leakage of the secrecy signal to the authorized user equipment is relatively small, and transmitted artificial noise signals are concentrated in an area with a relatively high secrecy signal leakage risk.

A circuit arrangement includes a channel estimation circuit configured to acquire a channel estimate including a plurality of channel samples based on a range of time and frequency locations of a received signal, a first calculation circuit configured to calculate a first time and frequency correlation product of the channel estimate and a second calculation circuit configured to calculate a second time and frequency correlation product of the channel estimate, a time offset circuit configured to determine a time offset based on the first time and frequency correlation product and the second time and frequency correlation product, and a frequency offset circuit configured to determine a frequency offset based on the first time and frequency correlation product and the second time and frequency correlation product.

The embodiments provide cryptography that is performed in each of two communicating devices and is based on information known only to the devices. The information is determined in each of the devices at the time of communications. Each of the devices determines the information without communicating key information related to the encryption key with each other. Channel characteristic reciprocity between the two devices allows creation of identical keys in each device. Each of the devices sends a first setup signal to the other device, receives a second setup signal from the other device, where the second setup signal may be a looped back version of the first setup signal, samples the second setup generates sampling results, creates a key based on the sampling results, and utilizes the key to exchange one or more secure data signals with the other device.

The embodiments provide a cryptography key for two communicating devices that is based on information known only to the devices. The information may only be determined by the devices. Each device determines the information without communicating key information related to the encryption key with the other. Channel characteristic reciprocity between the devices allows creation of identical keys in each device. Each device sends a signal to the other device at the same power level based on the distance between the devices. The power level may be set to result in a target receive power level at the other device. Each device samples the received signal, generates sampling results, creates a key based on the sampling results and a threshold power level, and utilizes the key. The threshold power level may be based on the target receive power level, or a median power determined from the sampling results.

Provided is a wireless communication apparatus wherein channel estimation accuracy is improved while keeping the position of each bit in a frame, even when a modulation system having a large modulation multiple value is used for a data symbol. In the wireless communication apparatus, an encoding section encodes and outputs transmitting data to a bit converting section, and the bit converting section converts at least one bit of a plurality of bits constituting a data symbol to be used for channel estimation, among the encoded bit strings, into ‘1’ or ‘0’ and outputs it to a modulating section. The modulating section modulates the bit string inputted from the bit converting section by using a single modulation mapper and a plurality of data symbols are generated.

A first client station receives from an access point an indication of whether angular information is to be included in feedback information in a range measurement session. The first client station transmits a null data packet (NDP) as part of an uplink multi-user (MU) PHY transmission that also includes simultaneous transmissions by one or more second client stations of one or more other respective NDPs to the access point as part of the range measurement session. The first client station receives a downlink physical layer (PHY) data unit from the access point that includes respective downlink feedback frames for the first client station and the one or more second client stations. When angular information is to be included in the feedback, a downlink feedback frame for the first client station includes angular information.

In one aspect, an apparatus includes: a front end circuit to receive and process incoming radio frequency (RF) signals into orthogonal frequency division multiplexing (OFDM) samples; a fast Fourier transform (FFT) engine to receive and convert the OFDM samples into frequency domain sub-carriers; a demodulator to demodulate the frequency domain sub-carriers; a channel estimator to: compute a first pilot channel estimate for a first channel condition comprising a flat channel condition and a second pilot channel estimate for a second channel condition comprising a selective channel condition based on a first set of pilot sub-carriers of the frequency domain sub-carriers; and select one of the first and second pilot channel estimates using the first and second pilot channel estimate; and a control circuit to configure at least the demodulator based at least in part on the selected first or second pilot channel estimate.

Methods, systems, and devices for wireless communications are described. A user equipment (UE) may perform online spur detection and mitigation scheme. The UE may identify spurs during operation, in real time, and apply cancelation and noise equalization to address identified spurs. The UE may apply a high pass filter to reference signals. During a symbol, the UE may apply the high pass filter by estimating the channel on one or more neighbor tones (e.g., tones of higher frequency and tones of lower frequency that also carry reference symbols). Because the UE may assume that a channel will generally be smooth, and that noise may vary slowly or steadily across frequency resources, the UE may compare the channel noise of a particular tone to an average or normalized channel noise of the one or more neighbor tones.

A MIMO symbol detection and search method, a decoding circuit and a receiving antenna system are provided. The signal detection and search method includes the following steps. A symbol search tree is obtained, and a plurality of candidate symbols at each layer of the symbol search tree are sorted. The candidate symbols are traversed in sequence at each layer of the symbol search tree. At each layer of the symbol search tree, if a cumulative partial Euclidean distance is greater than or equal to a threshold, un-scanned candidate symbols are excluded. If the cumulative partial Euclidean distance is less than the threshold, the threshold is updated by the cumulative partial Euclidean distance. When all of the candidate symbols have been calculated, an estimated symbol combination is outputted, and the scan of the symbol search tree is terminated.

One embodiment according to the present specification relates to a technique for transmitting a long training field (LTF) signal in a wireless LAN (WLAN) system. The LTF signal may comprise an LTF sequence transmitted on the basis of a plurality of subcarriers. For example, a minimum subcarrier index of a plurality of subcarriers may be set to −28, and a maximum subcarrier index of the plurality of subcarriers may be set to 28. A pilot tone may be inserted/allocated to four subcarriers from among a plurality of subcarriers.