A wireless communication system that communicates by an electromagnetic wave includes a first wireless device that includes a transmission rotationally polarized wave frequency generator for giving a rotation period to a polarized wave of the electromagnetic wave to be transmitted, transmits a synchronization code by the electromagnetic wave of the polarized wave rotated using the transmission rotationally polarized wave frequency generator, and transmits data by the electromagnetic wave, and a second wireless device that includes a reception rotationally polarized wave frequency generator for giving a rotation period to the polarized wave received in a reception of the electromagnetic wave, calculates transmission timing of the synchronization code included in the received electromagnetic wave of the polarized wave rotated using the reception rotationally polarized wave frequency generator, and sets a signal included in the received electromagnetic wave, as data based on the calculated transmission timing.

A wireless communication system includes a transmitter that discretely inserts null subcarriers into an OFDM-demodulated signal in time and frequency domains, and a receiver that receive signals by a first and second antennas. The receiver calculates a complex coefficient wherein a result of multiplying a first reception vector for each of the null subcarriers received by the first antenna by the complex coefficient is equal to an amplitude of a second reception vector of the corresponding null subcarrier received by the second antenna and is opposite in phase thereto, calculates a fourth reception vector by multiplying a third reception vector of any data subcarrier received by the first antenna by a coefficient that is obtained by interpolating the complex coefficient, and adds the fourth reception vector to a fifth reception vector of the any data subcarrier received by the second antenna.

Presently disclosed are systems and methods for beamforming training in WLANs. In various embodiments, there are unified MIMO beamforming training procedure, which includes a training period in which an initiator transmits multiple unified training frames for performing a transmit-beamforming training of the initiator and a receive-beamforming training of one or more responders; a feedback period in which each responder replies with a beamforming-feedback response; and an acknowledgement period during which the initiator transmits respective acknowledgement frames to the one or more responders from which responses were received. Rules for restricted random access in various slots of the feedback period may be implemented, to address response contention between multiple qualifying responders.

A signal source association method and receiver. A receiver can be used to detect a plurality of signals transmitted from a plurality of transmission sources. The receiver can determine amplitude and phase information for a plurality of frequency components of each of the plurality of signals. The receiver can also determine a set of comparison values by comparing the respective amplitude and phase information from one or more pairs of the plurality of signals. Finally, the receiver can associate one of the signals with one of the plurality of transmission sources using the set of comparison values. The comparison values can comprise Stokes parameters and the one or more pairs of the plurality of signals can comprise a pair of orthogonally polarized signals or a pair of signals detected from spatially-separated antennas.

A directional link maintenance method and a station STA to improve accuracy and timeliness of directional link availability determined by the STA are described. In at least one embodiment, the method includes monitoring, by a first station STA, an information packet, where the information packet carries first identification information, and the first identification information is used to identify a first directional transmit beam that is used a second STA when the second STA sends the information packet; determining, by the first STA, whether the information packet is an information packet that is sent by the second STA to a third STA, and obtaining the first identification information if the information packet is an information packet that is sent by the second STA to the third STA; and determining, by the first STA, whether the first identification information matches preset second identification information.

Presently disclosed are systems and methods for beamforming training in WLANs. In various embodiments, there are unified MIMO beamforming training procedure, which includes a training period in which an initiator transmits multiple unified training frames for performing a transmit-beamforming training of the initiator and a receive-beamforming training of one or more responders; a feedback period in which each responder replies with a beamforming-feedback response; and an acknowledgement period during which the initiator transmits respective acknowledgement frames to the one or more responders from which responses were received. Rules for restricted random access in various slots of the feedback period may be implemented, to address response contention between multiple qualifying responders.

An apparatus and a method for configuring antenna arrays for scalable radio frequency (RF) architecture are dis-closed. A subset of antenna arrays are grouped into K groups and a receive or transmit weight vector is applied to each of the antenna arrays in each of the K groups. A channel response is measured for each of the antenna in the K groups. The response is summed for each group and complex scaling factors are calculated based on the summed response. Based on the scaling factors the antenna weight vectors arc updated and the updated weight vectors arc applied to the antenna arrays. The steps of grouping the antennas and refining the weight vectors are performed till the antenna weight vectors reach a steady point, i.e. the current antenna weight does not improve the beamforming gain by a predetermined threshold in comparison to the previous antenna weight.

In distributed communication networks, the signal received at the destination is characterized by unknown multiple carrier frequency offsets (MCFOs) and improper channel state information (CSI). The knowledge of offsets and channel gains are required for coherent deployment of distributed systems. Hence, joint training sequence (TS) design method is proposed for joint estimation of MCFOs and channel estimation over spatially correlated channel. Thus, the present invention provides a method of providing joint estimation for distributed communication systems with multiple antennas at the nodes over spatial correlated channels. The designed optimal training sequences are short length and spectrally efficient. The designed training sequence produces zero cross-correlation, facilitating channel estimation without matrix inversion, significantly lowers the complexity of the estimation algorithm.

A wireless communication system includes a transmitter that discretely inserts null subcarriers into an OFDM-demodulated signal in time and frequency domains, and a receiver that receive signals by a first and second antennas. The receiver calculates a complex coefficient wherein a result of multiplying a first reception vector for each of the null subcarriers received by the first antenna by the complex coefficient is equal to an amplitude of a second reception vector of the corresponding null subcarrier received by the second antenna and is opposite in phase thereto, calculates a fourth reception vector by multiplying a third reception vector of any data subcarrier received by the first antenna by a coefficient that is obtained by interpolating the complex coefficient, and adds the fourth reception vector to a fifth reception vector of the any data subcarrier received by the second antenna.

Technology for a user equipment (UE) operable to enhance the receiving performance of a reference signal for beam refinement is disclosed. The UE can determine a receiving beam sweeping structure for each receiving beam of a plurality of receiving beams. The UE can calculate the receiving power rj for each of the plurality of receiving beams. The UE can select a refined receiving beam having a highest receiving power rj.