A second apparatus for wireless communication includes: a transceiver; and a processing circuit configured to receive, from a first apparatus via the transceiver, a physical layer protocol data unit (PPDU) including a first signal field having a fixed length and a second signal field having a variable length. The second signal field includes an orthogonal frequency-division multiplexing (OFDM) symbol block including at least one OFDM symbol, and one or more repetitions of the OFDM symbol block.

Methods and systems for obtaining improved joint channel estimates for a multi-user, frequency-multiplexed data transmission such as SC-FDMA or OFDM begins by estimating separate contributions of users (and/or other signal sources) to the received signal based on joint frequency domain channel estimates. A reduced data set is obtained by subtracting contributions of one or more users from the received data, leaving only the estimated contributions of the remaining users, with noise and residual estimation error signal. Time domain joint channel estimation is then performed on the reduced data set, which is feasible because the number of users has been reduced. In exemplary embodiments, the reduced data set includes only one estimated user contribution. This process is repeated to obtain channel estimates for all of the users. The method can be repeated by using the channel estimates to re-estimate the user contributions and calculate revised channel estimates.

An encoder architecture for UF-OFDM is provided, in which samples are first processed sub-band wise, and then resorted for sub-carrier-wise processing. The sub-carrier processing may comprise separate processing for the two extremity parts of the base band signal corresponding to the transient state of the UF-OFDM data stream and for a core part of the base band signal corresponding to the non-transient state of the UF-OFDM data stream, and then concatenated to obtain a UF-OFDM data stream. In certain embodiments a first extremity part of the base band signal corresponding to the transient state of the UF-OFDM data stream is calculated directly, and the other extremity part inferred from the core part and the first extremity part. The core and extremity part processors may be implemented with filters adapted to multiply each sample by a respective filter coefficient. Modifying these coefficients can introduce a frequency shift or convert the encoder for OFDM encoding.

A method for transmitting a signal is described, wherein the method has transforming a signal into a frequency domain to obtain a spectrum, forming a filtered spectrum according to a filter spectrum and occupying a set of subcarriers of a frequency domain representation of an Orthogonal Frequency Division Multiplex (OFDM) signal with the filtered spectrum. A temporary signal is obtained by transforming the frequency domain representation of the OFDM signal into a time domain. The temporary signal is subjected to a phase modulation.

Embodiments may comprise an orthogonal frequency division multiplexing (OFDM) system operating in the 1 GHz and lower frequency bands. In many embodiments, the physical layer logic may implement repetition logic to repeat portions of the data streams to increase the ability of a receiving device to detect and decode the data streams. In some embodiments, the repetition logic may comprise a preamble repeater to repeat the training and/or signal fields. In further embodiments, the repetition logic may comprise a payload repeater to repeat the payload one or more times. Other embodiments comprise a receiving device comprising a correlator to correlate the repeated preamble symbols to detect a communication from a transmitting device. The receiving device may also comprise correction logic to correct data streams from the communications signal based upon repetitions of the payload in the data streams.

For example, a first wireless station may be configured to perform hybrid beamforming training including simultaneously communicating a first plurality of spatially multiplexed Synchronization Signals (SS) beamformed in a plurality of wide beam directions; and simultaneously communicating a second plurality of spatially multiplexed SS beamformed in a plurality of narrow beam directions, which correspond to one or more reported wide beam directions.

A telecommunication method which includes: mapping, with a mapper, input data to points of a constellation in order to generate symbols, repeating symbols according to a pattern, modulating the symbols, with a modulator, in order to generate multi-carrier symbols, and transmitting a radio signal representative of the multi-carrier symbols.

A receiving apparatus is provided. The receiving apparatus may include a receiver, a PN sequence remover, and a zero padding performing unit. The receiver may be configured to receive a frame signal. The PN sequence remover may be configured to remove a first PN sequence from a first frame detected from the frame signal corresponding to a first path to generate a PN removed first frame and remove a second PN sequence from a second frame detected from the frame signal corresponding to a second path to generate a PN removed second frame. The zero padding performing unit may be configured zero pad the first PN removed frame to a size of a discrete Fourier transform (DFT) and zero pad the PN removed second frame to the size of the DFT.

Methods and systems for obtaining improved joint channel estimates for a multi-user, frequency-multiplexed data transmission such as SC-FDMA or OFDM begins by estimating separate contributions of users (and/or other signal sources) to the received signal based on joint frequency domain channel estimates. A reduced data set is obtained by subtracting contributions of one or more users from the received data, leaving only the estimated contributions of the remaining users, with noise and residual estimation error signal. Time domain joint channel estimation is then performed on the reduced data set, which is feasible because the number of users has been reduced. In exemplary embodiments, the reduced data set includes only one estimated user contribution. This process is repeated to obtain time domain estimates for all of the users. The method can be repeated by using the TD channel estimates to re-estimate the user contributions and calculate revised TD channel estimates.

A second apparatus for wireless communication includes: a transceiver; and a processing circuit configured to receive, from a first apparatus via the transceiver, a physical layer protocol data unit (PPDU) including a first signal field having a fixed length and a second signal field having a variable length. The second signal field includes an orthogonal frequency-division multiplexing (OFDM) symbol block including at least one OFDM symbol, and one or more repetitions of the OFDM symbol block.