A transmission method simultaneously transmitting a first modulated signal and a second modulated signal at a common frequency performs precoding on both signals using a fixed precoding matrix and regularly changes the phase of at least one of the signals, thereby improving received data signal quality for a reception device.

Systems and methods for OFDM channelization are provided that allow for the coexistence of sub-band channels and diversity channels. Methods of defining diversity sub-channels and sub-band sub-channels are provided and systematic channel definition and labeling schemes are provided.

The present invention relates to a method for transmitting, by a base station, a downlink signal using a plurality of transmission antennas comprises the steps of: applying a precoding matrix indicated by the PMI, received from a terminal, in a codebook to a plurality of layers, and transmitting the precoded signal to the terminal through a plurality of transmission antennas. Among precoding matrices included in the codebook, a precoding matrix for even number transmission layers can be a 22 matrix containing four matrices (W1s), the matrix (W1) having rows of a number of transmission antennas and columns of half the number of transmission layers, the first and second columns of the first row in the 22 matrix being multiplied by 1, the first column of the second row being multiplied by coefficient a of a phase, and the first column of the second row being multiplied by a.

Transmitter having multiple transmit antennas for transmitting two or more streams. The transmitter comprises an encoding circuitry configured to perform space-time block encoding to obtain for at least one of the two or more streams a pair of space-time encoded streams. Further, a mapping circuitry is configured to assign each stream of each pair of space-time encoded streams to a transmit antenna of the multiple transmit antennas for wirelessly transmitting the two or more streams. Finally, a control circuitry is configured to adjust one or more parameters of the mapping circuitry in order to achieve a defined channel characteristic between the transmitter and a receiver.

A transmission method simultaneously transmitting a first modulated signal and a second modulated signal at a common frequency performs precoding on both signals using a fixed precoding matrix and regularly changes the phase of at least one of the signals, thereby improving received data signal quality for a reception device.

The present invention belongs to the technical field of common signal transmission, and specifically relates to a CS-based omnidirectional beamforming design method in a uniform rectangular array. The main purpose of the present invention is to handle the beamforming design for realizing cell-level coverage in downlink transmission of common signals. For a large-size antenna base station with a uniform rectangular array, the present invention provides two omnidirectional beamforming design schemes: beamforming design based on complementary sequence sets and CCC-based beamforming design. Both schemes can obtain a completely smooth beam pattern in each direction, with low complexity and closed-form solution. Furthermore, most complementary sequence sets and code words of the complete complementary codes show a constant modulus, so that the whole beamforming scheme can be efficiently realized only by using the simulation-domain beamforming architecture. The hardware efficiency is effectively improved.

A system for includes master and sniffer devices. The master device includes: first antennas with different polarized axes; a transmitter transmitting a challenge signal via the first antennas from the vehicle to a slave device, where the slave device is a portable access device; and a receiver receiving a response signal in response to the challenge signal from the slave device. The sniffer device includes: second antennas with different polarized axes; and a receiver receiving, via the second antennas, the challenge signal from the transmitter and the response signal from the slave device. The sniffer device measures when the challenge signal and the response signal arrive at the sniffer device to provide arrival times. The master or sniffer device estimates at least one of a distance from the vehicle to the slave device or a location of the slave device relative to the vehicle based on the arrival times.

A method of communicating with a portable access device includes iteratively performing an algorithm via an access module of a vehicle. The algorithm includes a series of operations including: selecting a frequency from multiple frequencies; selecting an antenna pair from multiple possible antenna pairs, where antennas of the possible antenna pairs include antennas with different polarized axes; transmitting a packet to the portable access device via the selected antenna pair; receiving a first RSSI and a response signal from the portable access device, the first RSSI corresponds to the transmission of the packet; and measuring a second RSSI of the response signal; based on the first RSSIs and the second RSSIs. A best one of the frequencies and a best antenna pair of the possible antenna pairs are selected. One or more additional packets are transmitted using the selected best frequency and the selected best antenna pair.

A system for detecting a range extension type relay attack includes a transmitter, a receiver and a module. The transmitter transmits a RF signal from one of a vehicle and a portable access device to the other one of the vehicle and the portable access device. The receiver receives a response signal in response to the RF signal. The module: generates a parameter associated with the transmission of the RF signal and the reception of the response signal; based on the parameter, detects the range extension type relay attack performed by an attacking device, where at least one of (i) the RF signal is relayed via the attacking device from the vehicle to the portable access device, or (ii) the response signal is relayed via the attacking device from the portable access device to the vehicle; and perform a countermeasure in response to detecting the range extension type relay attack.

A system for providing operational control of a vehicle includes a first network device and control module. The first network device includes: polarized antennas; a transmitter transmitting an initiator packet via the polarized antennas from the vehicle to a second network device including a synchronization access word and a CW tone, one of the first and second network devices is implemented within the vehicle, the other one of the first and second network devices is a portable access device, and at any moment in time, at least one of the polarized antennas is not cross-polarized with an antenna of the second network device; and a receiver receiving a response packet from the second network device including the synchronization access word and the first CW tone. A control module determines a difference in RTT between the initiator and response packets and detects a range extension type relay attack.