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.

A receiver and method applied to the receiver, for estimating a normalized frequency offset value ε between a transmitter and the receiver in a wireless communication system, based on Orthogonal Frequency Division Multiplexing (OFDM), where the method includes receiving a first pilot signal (y.sub.r1) and a second pilot signal (y.sub.r2), from the transmitter, determining a correlation model to be applied based on correlation among involved sub-carrier channels at the y.sub.r1 and the y.sub.r2, computing three complex values μ.sub.−1, μ.sub.0, and μ.sub.1, by a complex extension of a log-likelihood function (λ(ε)), based on the determined correlation model, and estimating the ε by finding a maximum value of a Karhunen-Loeve approximation of the λ(ε), based on the computed three complex values μ.sub.−1, μ.sub.0, and μ.sub.1.

This application relates to a sequence detection method and a device. In embodiments of this application, K candidate frequency domain root sequences may be first filtered based on a differentiation result of received first sequence and differentiation results of candidate frequency domain root sequences, and a candidate frequency domain root sequence to which the first sequence actually corresponds only needs to be determined based on the first sequence and the K candidate frequency domain root sequences. For example, there are U candidate frequency domain root sequences. In this case, a current calculation amount is calculation of U*C.sub.s cross correlation values. In embodiments of this application, a calculation amount is calculation of only L*U+K*C.sub.s, where C.sub.s represents a quantity of sampled time domain cyclic shift values, and L represents a quantity of differentiation granularities.

A method and apparatus having a synchronization signal sequence structure for low complexity cell detection is provided. The method includes establishing a set of a plurality of synchronization signal sequences to be used in connection with a communication target. Each one of the plurality of synchronization signal sequences includes at least a first sub-sequence, which includes either a first preselected sequence or a complex conjugate of the first preselected sequence, and a second sub-sequence, which includes either a second preselected sequence or a complex conjugate of the second preselected sequence. The second preselected sequence is different than the first preselected sequence, and is different than the complex conjugate of the first preselected sequence. Further, a length of the first sub-sequence and a length of the second sub-sequence are smaller than a length of the synchronization signal sequence. A signal including a synchronization signal is then received, where the synchronization signal comprises one of the synchronization signal sequences from the set of the plurality of synchronization signal sequences, and the synchronization signal is then detected.

Described is a method of decoding a physical sidelink control channel (PSCCH). The method comprises: for a PSCCH candidate in a resource grid, processing a received demodulation reference signal (DMRS) in a subframe of the resource grid associated with the PSCCH candidate to determine one or more potential PSCCHs for decoding, each of the one or more potential PSCCHs being identified by resource block (RB) position in the resource grid and a corresponding DMRS cyclic shift (n.sub.cs) value. This step is repeated for at least one other DMRS in the subframe to determine one or more potential PSCCHs for the at least one other DMRS. Then, a subset L of PSCCHs is selected from the potential PSCCHs. The selected subset L of PSCCHs together with their corresponding DMRS cyclic shift (n.sub.cs) values are made available for use in a decoding process for the received channel signal.

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.

Described is a method of decoding a physical sidelink control channel (PSCCH). The method comprises: for a PSCCH candidate in a resource grid, processing a received demodulation reference signal (DMRS) in a subframe of said resource grid associated with said PSCCH candidate to determine one or more potential PSCCHs for decoding, each of said one or more potential PSCCHs being identified by resource block (RB) position in the resource grid and a corresponding DMRS cyclic shift (n.sub.cs) value. The foregoing step is repeated for at least one other DMRS in said subframe to determine one or more potential PSCCHs for said at least one other DMRS. Then, a subset L of PSCCHs is selected from said potential PSCCHs whereby said selected subset L of PSCCHs together with their corresponding DMRS cyclic shift (n.sub.cs) values are made available for use in a decoding process for the received channel signal.

A method for determining coarse carrier phase and frequency offsets of an initial block of received M-QAM symbols includes creating a grid of discrete candidate phase offset values and for each candidate value: applying the candidate value to each symbol, applying a respective hard decision to each applied symbol, and computing a figure of merit based thereon. The candidate value having the best figure of merit is selected as an initial phase offset estimate. An initial frequency offset estimate is computed using the symbols updated with the initial phase offset estimate, their respective hard decisions, and an approximation of the complex exponential function. To track carrier phase and frequency offsets associated with a series of symbol blocks, for each symbol of a current block, set a binary trust weight based on comparison of a computed parameter with a threshold and use the binary trust weights to compute a phase offset error and a frequency offset error for the current block.

Systems and methods for processing a Random Access (RA) transmission are disclosed. In some embodiments, a method of operating a radio access node in a cellular communications network includes receiving an RA transmission from a wireless device. The method also includes detecting an RA preamble in the RA transmission from the wireless device and estimating a timing parameter of the wireless device using the RA transmission from the wireless device separately from detecting the RA preamble. By estimating the timing parameter separately from detecting the RA preamble, increased detection of the RA preamble is possible while also increasing the precision of the timing parameter estimate. In some embodiments, this separation also enables a complexity reduction of the receiver if a low complexity detector is used first and then the high complexity timing estimator is only used when an RA preamble is detected.

Transmitting apparatus and receiving apparatus for communication systems use coded orthogonal frequency-division multiplexed (COFDM) dual-subcarrier-modulation (DCM) signals. The same coded data is mapped both to COFDM subcarriers located in the lower-frequency half spectrum of the DCM signal and to COFDM subcarriers located in its upper-frequency half spectrum. Symbol constellation mappings of COFDM subcarriers in those half spectra preferably employ labeling diversity providing peak-to-average power ratio (PAPR) of the COFDM DCM signals substantially reduced from PAPR of double-sideband COFDM signals.