A signal detection method for a MIMO-OFDM wireless communication system includes obtaining a channel matrix of each subcarrier through channel estimation for each MIMO-OFDM data packet in a plurality of MIMO-OFDM data packets; receiving a reception vector of each subcarrier; performing channel matrix preprocessing for the channel matrix of each subcarrier to generate a global dynamic K-value table, in which the global dynamic K-value table includes a global dynamic K-value corresponding to each search layer of each subcarrier; performing MIMO detection for each OFDM symbol in the MIMO-OFDM data packet, in which the MIMO detection includes performing the following steps for each subcarrier of a current OFDM symbol: reading channel matrix preprocessing results and reception vector of the current subcarrier; transforming the reception vector of the current subcarrier into an LR search domain; and performing K-best search for the current subcarrier to obtain an LR domain candidate transmission vector of the current subcarrier, in which a K-value applied to each search layer of the current subcarrier during the K-best search is a global dynamic K-value in the global dynamic K-value table corresponding to the search layer.

A symbol boundary detection method includes: calculating desired signal power according to a receiving signal by a receiver device; calculating interference power according to the receiving signal by the receiver device; calculating a signal-to-interference power ratio according to the desired signal power and the interference power by the receiver device; finding a best signal-to-interference power ratio to determine a reference symbol boundary time by the receiver device; and processing the receiving signal according to the reference symbol boundary time by the receiver device for a subsequent demodulation process performed by a demodulator circuit.

A system that incorporates aspects of the subject disclosure may perform operations including, for example, receiving, via an antenna, a signal generated by a communication device, detecting passive intermodulation interference in the signal, the interference generated by one or more transmitters unassociated with the communication device, and the interference determined from signal characteristics associated with a signaling protocol used by the one or more transmitters. Other embodiments are disclosed.

Message reliability is a key requirement of 5G/6G communications. In many challenging network environments, two successive retransmissions of a message can both be corrupted, greatly reducing reliability. Therefore, methods are disclosed for identifying faulted message elements according to a metric that includes the waveform or SNR of the message element, its modulation quality, and a consistency check between the received versions. The receiver can then assemble a merged message version by selecting the higher quality version of each message element from the two (or more) corrupted versions, and thereby avoid requesting yet another retransmission. In addition, the receiver can monitor the background level and, if it is above a predetermined limit, can request that the receiver store the message for a predetermined time, or until the background level subsides below the limit.

Described are methods for dealing with phase noise, e.g., common phase error and/or inter-carrier interference, in communication systems, and apparatuses for the same. A method can include at least: transmitting one or more reference signals (in-band signals within a channel); and mapping the reference signals to radio resources in the channel for transmission of the reference signals. An amount of the radio resources may depend on, e.g., information about a modulation and coding scheme used for transmission. An associated method can include at least: receiving one or more reference signals, and mapping the reference signals to radio resources in the channel for reception of the reference signals; receiving information about a modulation and coding scheme to be used, an amount of the radio resources depending on, e.g., information about the modulation and coding scheme used for reception; and using the reference signals to compensate for phase noise.

Message faults are inevitable in the high-throughput environment of 5G and planned 6G. Retransmissions are costly in time and resources, while generating extra backgrounds and interference. Therefore, methods are disclosed for recovering a faulted message by identifying and correcting each mis-demodulated message element. The faulted message elements generally have substantially lower modulation quality than the correctly demodulated elements, and can be identified by determining the modulation quality of each received message element. If the number of faulted message elements is small, the receiver may correct them using a grid search tested by an associated error-detection code. If the number of faults exceeds a predetermined threshold, the receiver can request a retransmission, and then assemble a merged copy of the message by selecting the message element with the best modulation quality from each version. Substantial time and resources may be saved, and reliable communication may be restored despite poor reception.

In current practice, faulted messages are typically discarded and a retransmission is requested. Forward error-correction codes (FEC) in 5G and 6G are bulky, resource-expensive, and often unable to resolve the problem. Disclosed are systems and methods for determining which specific message elements are faulted, so that just the faulted portion can be retransmitted, instead of the entire message. For example, the amplitudes of the I and Q branches, of each message element, can be compared to the calibrated amplitude levels of the modulation scheme. Any message element with a large amplitude deviation is suspect. Other factors, such as the SNR, can also be considered in evaluating the validity of each message element. Usually, all of the faulted message elements occupy just a portion of the message. Compact formats are disclosed specifying which portion of the message is to be retransmitted, thereby saving time, power, and background generation.

Message faults are inevitable in the high-throughput environment of 5G and planned 6G. Retransmissions are costly in time and resources, while generating extra backgrounds and interference. Therefore, methods are disclosed for recovering a faulted message by identifying and correcting each mis-demodulated message element. The faulted message elements generally have substantially lower modulation quality than the correctly demodulated elements, and can be identified by determining the modulation quality of each received message element. If the number of faulted message elements is small, the receiver may correct them using a grid search tested by an associated error-detection code. If the number of faults exceeds a predetermined threshold, the receiver can request a retransmission, and then assemble a merged copy of the message by selecting the message element with the best modulation quality from each version. Substantial time and resources may be saved, and reliable communication may be restored despite poor reception.

This document discloses a solution for reducing a frequency offset. According to an aspect, a method comprises: acquiring a signal distorted by the frequency offset; estimating a frequency offset estimate describing the frequency offset; computing coefficients for a frequency-domain filter on the basis of a relation between the frequency offset estimate and a combination of the frequency offset estimate and an index of the frequency-domain filter; and performing frequency-domain filtering of the signal by using the computed coefficients.

A receiver performing a half cyclic prefix (CP) shift on received subframes is disclosed, comprising: an analog to digital conversion (ADC) module; a cyclic prefix (CP) removal module coupled to the ADC module configured to retain a portion of cyclic prefix samples; a fast Fourier transform (FFT) module configured to receive samples from the cyclic prefix removal module, and to perform a FFT procedure on the received samples using a FFT window, the FFT window being shifted ahead based on the retained portion of cyclic prefix samples, to output an orthogonal frequency division multiplexed (OFDM) symbol; and a rotation compensation module coupled to the FFT module, the rotation compensation module configured to perform phase de-rotation of the OFDM symbol.