A transmission apparatus and method include modulating a transmission signal using a first modulation scheme selected from a plurality of modulation schemes to generate a first symbol sequence. A second symbol, generated using a phase shift keying (PSK) modulation scheme, is inserted in the first symbol sequence to generate a first modulation signal for transmission. A second modulation signal is received that includes a third symbol generated using a PSK modulation scheme and inserted in a second symbol sequence generated using a second modulation scheme selected from the plurality of modulation schemes. The third symbol is extracted from the received modulation signal. A transmission path associated with the received modulation signal is estimated using the third symbol. A received data signal from the second symbol sequence included in the received modulation signal is output using the estimated transmission path.

A carrier-phase recovery method includes: (i) applying a first carrier-phase recovery algorithm to complex-valued symbols of a signal received by a product detector, yielding coarse phase-estimates, the signal being modulated per an M-QAM scheme; (ii) modelling the coarse phase-estimates as a weighted sum of M probability-density functions of an M-component mixture model; (iii) optimizing the M probability-density functions with an expectation-maximization algorithm to yield M optimized probability-density functions; (iv) mapping, based on the M optimized probability-density functions, the coarse phase-estimates to one of M symbols corresponding to the QAM scheme, each coarse phase-estimate mapped to a same symbol belonging to a same one of M clusters; (v) applying a second carrier-phase recovery algorithm to each of the M clusters to generate refined phase-estimates each corresponding to a respective coarse phase-estimate; and (vi) mapping, based on the M optimized probability-density functions, each refined phase-estimate to one of the M symbols.

A Radio Network Node (RNN) 110 and a method therein for improving capacity in a wireless communications system 100. The RNN is configured to serve a first wireless device 120 and a second wireless device (WD) 130. The RNN assigns a shared uplink pilot signal to the first and second WDs. Further, the RNN transmits, to the first WD, an indication of how possible second data intended for the second WD will be comprised in a signal to be transmitted to the first WD. Furthermore, the RNN estimates a combined channel based on a received shared uplink pilot signal from the first WD and/or the second WD. Yet further, the RNN determines a beamforming vector for the estimated combined channel; and transmits the signal to the first WD, wherein the signal comprises first data and the possible second data, which first data is decodable only by the first WD.

A system and method are provided relating generally to data transmission and more particularly to modulation techniques offering increased data transmission rates. To so provide, a first amplitude-time modulated (ATM) signal and a first phase modulated signal are combined at a first combiner to produce a complex wave modulation signal, and the complex wave modulation signal and an additional signal are combined at a second combiner to produce a second complex wave modulation signal. The additional signal may be a second ATM signal or a second phase modulated signal. Optionally, the second complex wave modulation signal and a second additional signal may be combined to produce a third complex wave modulation signal. In accordance with at least one embodiment, a shape of an element of information according to the first ATM signal may be defined programmatically over subportions of less than the duration of the element of information.

A transmission apparatus and method include modulating a transmission signal using a first modulation scheme selected from a plurality of modulation schemes to generate a first symbol sequence. A second symbol, generated using a phase shift keying (PSK) modulation scheme, is inserted in the first symbol sequence to generate a first modulation signal for transmission. A second modulation signal is received that includes a third symbol generated using a PSK modulation scheme and inserted in a second symbol sequence generated using a second modulation scheme selected from the plurality of modulation schemes. The third symbol is extracted from the received modulation signal. A transmission path associated with the received modulation signal is estimated using the third symbol. A received data signal from the second symbol sequence included in the received modulation signal is output using the estimated transmission path.

An OFDM system synchronization tracking method includes: A1: performing OFDM symbol segmentation on a received digital signal, performing FFT on OFDM symbols obtained through the segmentation, performing step A2 to A5 on each frequency domain OFDM symbol in a frequency domain OFDM symbol sequence; A2: extracting information subcarrier symbols, pilot symbols, a DC subcarrier from a current frequency domain OFDM symbol, detecting and implementing a decision on the information subcarrier symbols, generating a recovery information subcarrier symbol; A3: recovering the OFDM symbol; A4: performing frequency offset estimation and timing offset estimation on the recovery OFDM symbol; A5: performing phase compensation on a next frequency domain OFDM symbol in the frequency domain OFDM symbol sequence by using a frequency offset estimation phase rotation value and a timing offset estimation phase rotation value, setting the compensated frequency domain OFDM symbol to a current frequency domain OFDM symbol, returning to the step A2.

The transmission of data signals transmitted by a plurality of transmitters may be rendered more efficient by combining multi-user superposition coding with appropriate phase shift estimation at the receiver so that phase shift compensation at the transmitter's side may lead to a superposition of the data signals which may be demapped correctly so as to obtain information data per data signal. Owing to the combination, the concept is applicable to typical uplink situations or downlink situations of separate contributing BSs: contrary to the simple downlink situation where the data signals stem from one BS and are superimposed in one domain, namely the base station's domain, the data signals to be superimposed stem from separate transmitters, such as user entities or mobile terminals in the typical uplink situation, or different base stations in the downlink situation.

A transmission apparatus and method include modulating a transmission signal using a first modulation scheme selected from a plurality of modulation schemes to generate a first symbol sequence. A second symbol, generated using a phase shift keying (PSK) modulation scheme, is inserted in the first symbol sequence to generate a first modulation signal for transmission. A second modulation signal is received that includes a third symbol generated using a PSK modulation scheme and inserted in a second symbol sequence generated using a second modulation scheme selected from the plurality of modulation schemes. The third symbol is extracted from the received modulation signal. A transmission path associated with the received modulation signal is estimated using the third symbol. A received data signal from the second symbol sequence included in the received modulation signal is output using the estimated transmission path.

The present disclosure relates to a 5G or pre-5G communication system for supporting a higher data rate beyond a 4G communication system such as LTE. According to an embodiment of the present invention, a method for transmitting a synchronization signal by a base station in a filter bank multi carrier (FBMC) system and a base station using the same may be provided, the method comprising the steps of: generating a frequency-domain quadrature amplitude modulation (QAM) symbol sequence having a length of k for a synchronization signal; mapping the QAM symbol sequence to a sub-carrier of a filter bank on the basis of the correlation characteristic of the synchronization signal; generating a quadrature amplitude modulation-filter bank multicarrier (QAM-FBMC) symbol including the synchronization signal on the basis of the mapping, and transmitting the generated QAM-FBMC symbol. In addition, a terminal communicating with the base station and an operation method for the terminal may be provided.

A phase ambiguity processing method and device are provided. The phase ambiguity processing method includes: deciding symbols on a Y polarization state and an X polarization state of a received signal, and mapping to obtain first bit information, where the received signal includes a plurality of first signals; checking and analyzing the first bit information to generate a first check result; judging the first check result to obtain a judgment result as to whether the received signal has phase ambiguity; acquiring at least one of the plurality of first signals in the received signal when the judgment result indicates that the received signal has phase ambiguity; performing phase rotation on the first signal to obtain a second signal; and checking and analyzing the second signal, storing the second signal so that the first signal is replaced with the second signal for decoding processing if a check result is normal.