A method in the embodiments of this application includes: generating, by a terminal device, first information, where the first information includes parameters q, m.sub.1, m.sub.2, . . . , m.sub.L, and indication information of a vector V; q is an integer, and q<Q; Q is an integer, and Q>1; 0≤m.sub.l≤N−1, and 1≤l≤L; L>1, N, L, and l are integers, and N is a quantity of subbands in a frequency domain bandwidth; and the vector V includes L elements and satisfies V=F.sub.q×C, where C is a vector formed by N elements c.sup.1, . . . , c.sup.N, C=[c.sup.1 c.sup.2 . . . c.sup.N].sup.T, c.sup.k is used to indicate channel state information on a k.sup.th frequency domain subband, c.sup.k is a complex number, a modulus of c.sup.k is |c.sup.k|≤1, and 1≤k≤N; and sending, by the terminal device, the first information to a network device.

The present invention discloses an ML (Maximum Likelihood) detector. An embodiment of the ML detector comprises a search value selecting circuit and an ML detecting circuit. The search value selecting circuit is configured to select a first-layer search value. The ML detecting circuit is configured to carry out the following steps: selecting first-layer candidate values according to the first-layer search value, one of a reception signal and a derivative thereof, and one of a channel estimation signal and a derivative thereof, and adding one or more first-layer candidate value(s), if necessary; calculating second-layer candidate values according to all the above-mentioned first-layer candidate values, and adding one or more second-layer candidate value(s) and its/their corresponding first-layer candidate value(s), if necessary; and calculating log likelihood ratios according to the whole first-layer and second-layer candidate values.

Embodiments herein provide a method of estimating channel states of a plurality of user equipments (UEs) in a single instance. The method includes receiving pilot samples from the plurality of UEs. The method includes selecting a predetermined number of tones, wherein the channel associated with each UE across the selected pre-determined number of tones is same. The method includes collecting the received pilot samples from each pilot symbol and stacking the received pilot samples as a vector. Further, the method includes constructing a matrix. The matrix includes known pilot values used by each UE. Furthermore, the method includes estimating channel states of the plurality of UEs by applying a filter on the vector formed from the received pilot samples. The number of channel states to be estimated is reduced by selecting the pre-determined number of tones.

Embodiments of the present disclosure provide a method performed by a communication device. The method includes obtaining, in frequency domain, channel estimation for a transmission unit for a channel between the communication device and another communication device, and calculating correlation coefficients for the transmission unit based on the channel estimation. The method also includes obtaining a delay spread for the channel from the calculated correlation coefficients.

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 MIMO detection for a first OFDM symbol in a MIMO-OFDM pack and channel matrix preprocessing for the channel matrix of each subcarrier to generate a global dynamic K-value table; performing MIMO detection for each subsequent 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 method of designing a digital filter for example for use in an FBMC/OQAM telecommunications system, with a target overlapping factor and meeting a specified signal to interference ratio is described, whereby a candidate filter design defined by an impulse response, satisfying the Nyquist criterion and having an overlapping factor higher than the target is selected, and the time and frequency coefficients of its impulse response inverted to define a new filter design; and

truncating the impulse response defining said new filter design to the minimum number of coefficients achieving said specified signal to interference ratio.

The present disclosure relates to a pre-5th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4th-Generation (4G) communication system such as Long Term Evolution (LTE). A method for operating a receiving device in a wireless communication system comprises determining inter-symbol interference between symbols in a received signal, determining a location of a receive detection window according to the inter-symbol interference, and demodulating the received signal based on the location of the receive detection window. A receiving device includes at least one transceiver, and at least one processor configured to determine inter-symbol interference between symbols in a received signal, determine a location of a receive detection window according to the inter-symbol interference, and demodulate the received signal based on the location of the receive detection window. A transmitting device includes at least one processor configured to estimate an equivalent channel frequency response based on characteristic information of a time-domain filter, estimate an inter-symbol interference based on the equivalent channel frequency response, and generate indication information regarding an adjustment of a location of a receive detection window.

The present technology provides a system and methods for carrier frequency offset (CFO) estimation. According to embodiments, there is provided a system and method for CFO estimation for narrow band 3GPP LTE/LTE-A Machine Type Communication (MTC) uplinks.

There is provided a method of estimating channel spread at a receiver of a user equipment, UE, for one antenna port of a network node. The method is performed in the UE. The method comprises acquiring channel estimates for one antenna port of a network node. The method further comprises determining a variation of acquired channel estimates representing subframes associated with a common precoder, the subframes comprising resource blocks scheduled to the UE. The method further comprises estimating the channel spread by using a pre-determined mapping from the determined variation to a channel spread value. A user equipment and a computer program are also provided.

A method for measuring channel quality in a Long Term Evolution (LTE) transceiver is disclosed, comprising: receiving, at a Long Term Evolution (LTE) wireless transceiver, an analog signal from a user equipment (UE); converting the analog signal to a plurality of digital samples at an analog to digital converter (ADC); performing a fast Fourier transform (FFT) on the plurality of digital samples to generate frequency domain samples; identifying an uplink demodulation reference signal (DMRS) symbol; performing channel estimation on the DMRS symbol to identify an estimate of channels; creating a noise covariance matrix from the estimate of channels; and deriving an interference measure from the noise covariance matrix.