A method is disclosed for mitigating phase noise at high frequencies in 5G and 6G. Quadrature modulation schemes, in which orthogonal branches are amplitude modulated, are susceptible to phase noise which rotates the branches, causing demodulation faults. Disclosed is a single-branch reference signal that can mitigate phase noise. The transmitter can transmit a particular resource element having a normal amplitude in one branch, and zero amplitude in the orthogonal branch. The receiver can then measure the amplitudes of the particular resource element as-received (with phase noise), and determine a phase rotation angle according to a ratio of the two branch amplitudes. The receiver can then correct the branch amplitudes of each message element, and thereby negate the effect of the phase noise. The disclosed procedures can thereby make high-frequency, high-reliability communication feasible, at extremely low cost.

Included are a demodulation unit 20 that demodulates a received OFDM modulation signal to acquire a demodulated constellation signal, an ideal constellation signal generation unit 312 that generates an ideal constellation signal from the demodulated constellation signal, a data extraction unit 313 that extracts signal data included in some symbol sections including a known reference symbol, among all symbol sections, from the demodulated constellation signal and the ideal constellation signal, a phase error calculation unit 314 that calculates the phase error of the demodulated constellation signal for the ideal constellation signal, with respect to the extracted signal data, a phase error characteristics estimation unit 315 that estimates the frequency characteristics of the phase error, and a phase error correction unit 316 that corrects the phase error of the demodulated constellation signal, based on the frequency characteristics of the phase error.

At high frequencies planned for 5G and 6G, phase noise may be a limiting factor on reliability and throughput. The default modulation scheme is currently QAM. Disclosed is a more versatile demodulation method based on the amplitude and phase of the sum-signal, which is the vector sum of the two branch amplitudes of QAM. The transmitter modulates a message by sum-signal amplitude and phase. The receiver can process the received waveform according to quadrature branches as usual, and determines the branch amplitudes. The receiver then calculates, from the branch amplitudes, the sum-signal amplitude and sum-signal phase for demodulation. The receiver can thereby obtain substantially enhanced phase-noise tolerance and amplitude spacing uniformity at virtually no cost. In addition, methods are disclosed for determining specific message fault types and non-square modulation tables depending on the type of mitigation required. Sum-signal modulation can provide access to high-frequency bands with enhanced reliability and throughput.

A method and apparatus for transmitting PPDU in a wireless LAN system are proposed. Specifically, a transmitter generates the PPDU, and transmits the PPDU to a receiver through a 320 MHz band in which some bands are punctured. The PPDU includes a legacy preamble and an EHT field. The legacy preamble includes L-STF and L-LTF. The legacy preamble is generated by applying a first phase rotation value or a second phase rotation value. The first phase rotation value is obtained on the basis of a third phase rotation value and a fourth phase rotation value. The third phase rotation value is a phase rotation value having repeated a phase rotation value defined for an 80 MHz band in an 802.11ax system. The fourth phase rotation value is a phase rotation value defined in units of the 80 MHz band in the 320 MHZ band on the basis of an optimal PAPR of the L-LTF.

A method is disclosed for mitigating phase noise at high frequencies in 5G and 6G. Quadrature modulation schemes, in which orthogonal branches are amplitude modulated, are susceptible to phase noise which rotates the branches, causing demodulation faults. Disclosed is a single-branch reference signal that can mitigate phase noise. The transmitter can transmit a particular resource element having a normal amplitude in one branch, and zero amplitude in the orthogonal branch. The receiver can then measure the amplitudes of the particular resource element as-received (with phase noise), and determine a phase rotation angle according to a ratio of the two branch amplitudes. The receiver can then correct the branch amplitudes of each message element, and thereby negate the effect of the phase noise. The disclosed procedures can thereby make high-frequency, high-reliability communication feasible, at extremely low cost.

At high frequencies planned for 5G and 6G, phase noise may be a limiting factor on reliability and throughput. The default modulation scheme is currently QAM. Disclosed is a more versatile demodulation method based on the amplitude and phase of the sum-signal, which is the vector sum of the two branch amplitudes of QAM. The transmitter modulates a message by sum-signal amplitude and phase. The receiver can process the received waveform according to quadrature branches as usual, and determines the branch amplitudes. The receiver then calculates, from the branch amplitudes, the sum-signal amplitude and sum-signal phase for demodulation. The receiver can thereby obtain substantially enhanced phase-noise tolerance and amplitude spacing uniformity at virtually no cost. In addition, methods are disclosed for determining specific message fault types and non-square modulation tables depending on the type of mitigation required. Sum-signal modulation can provide access to high-frequency bands with enhanced reliability and throughput.

Included are a demodulation unit 20 that demodulates a received OFDM modulation signal to acquire a demodulated constellation signal, an ideal constellation signal generation unit 312 that generates an ideal constellation signal from the demodulated constellation signal, a data extraction unit 313 that extracts signal data included in some symbol sections including a known reference symbol, among all symbol sections, from the demodulated constellation signal and the ideal constellation signal, a phase error calculation unit 314 that calculates the phase error of the demodulated constellation signal for the ideal constellation signal, with respect to the extracted signal data, a phase error characteristics estimation unit 315 that estimates the frequency characteristics of the phase error, and a phase error correction unit 316 that corrects the phase error of the demodulated constellation signal, based on the frequency characteristics of the phase error.

Precision synchronization is key to reliable communications at the high frequencies planned for 5G and 6G. A timing reference signal can provide a compact, resource-efficient, low-complexity phase noise mitigation while also providing an amplitude noise calibration. The timing reference signal is a QAM (quadrature amplitude modulation) signal with an I branch multiplexed with an orthogonal Q branch, in which one of the branches is modulated according to a maximum amplitude level of the modulation scheme, and the other branch has zero amplitude as-transmitted. When received, the amplitude and phase may be altered by noise. The receiver can measure the overall magnitude of the received I and Q signals to mitigate amplitude noise, and can also calculate a phase rotation angle according to a ratio of the I and Q branch signals as-received, and thereby correct for phase noise in the message.

The present disclosure describes the generation of long sequences from short sequences to support concurrent transmissions of large numbers of machine-type communication devices operating in a wireless communication system. These long sequences may be assigned to devices so that the devices can use the long sequences scramble their transmissions. The use of such long sequences permits many machine-type communication devices to transmit during the same time and frequency resource.

Disclosed is a sequence generation method comprising: generating a basic sequence structure including C.sub.48 having 48 tones, X.sub.6 having six tones, and X.sub.5 having five tones; selecting any one of a plurality of phase rotation factors predetermined for a bandwidth; and generating a sequence to be inputted into a preamble to be transmitted to a terminal, by using the phase rotation factor, applied in basic sequence structural units, and the basic sequence structure.