Embodiments include devices and methods that improves quality in radio transmission/reception using a single-carrier scheme and/or a multi-carrier scheme.

Aspects of the present invention include apparatus and methods for transmitting and receiving signals in communication systems. A multicarrier generator generates a multicarrier signal. An optical demultiplexer separates the multicarrier signal into separate multicarrier signals. At least one QPSK modulator modulates signals from the separate multicarrier signals. An optical multiplexer combines the QPSK modulated signals into a multiplexed signal. The multiplexed signal is then transmitted.

A data transmission method and apparatus and a communications system. The method includes: performing phase rotation on a random access preamble sequence according to data to be transmitted, so as to carry the data to be transmitted in the random access preamble sequence; and transmitting the random access preamble sequence carrying the data to be transmitted via a physical random access channel. Hence, random access and data transmission may be achieved in a transmission step, which is high in transmission efficiency and low in overhead, and a MTC equipment may perform data transmission in a high efficiency manner.

A data transmission method and apparatus and a communications system. The method includes: performing phase rotation on a random access preamble sequence according to data to be transmitted, so as to carry the data to be transmitted in the random access preamble sequence; and transmitting the random access preamble sequence carrying the data to be transmitted via a physical random access channel. Hence, random access and data transmission may be achieved in a transmission step, which is high in transmission efficiency and low in overhead, and a MTC equipment may perform data transmission in a high efficiency manner.

A combined symbol constellation may be selected from a uniform symbol constellation that is supported by a de-mapper to provide additional power split options while reducing modifications to the de-mapper. In some examples, a signal may be constructed according to a combined symbol constellation selected from a larger uniform symbol constellation based on a desired power-ratio. The signal may include a base-layer, used to communicate a first set of data, and an enhancement-layer, used to communicate a second set of data, in accordance with the selected combined symbol constellation. The signal may be received and de-mapped according to the combined symbol constellation at a de-mapper that supports a uniform symbol constellation that is larger than the combined symbol constellation.

A combined symbol constellation may be selected from a uniform symbol constellation that is supported by a de-mapper to provide additional power split options while reducing modifications to the de-mapper. In some examples, a signal may be constructed according to a combined symbol constellation selected from a larger uniform symbol constellation based on a desired power-ratio. The signal may include a base-layer, used to communicate a first set of data, and an enhancement-layer, used to communicate a second set of data, in accordance with the selected combined symbol constellation. The signal may be received and de-mapped according to the combined symbol constellation at a de-mapper that supports a uniform symbol constellation that is larger than the combined symbol constellation.

A method and apparatus for underwater acoustic communication are disclosed. A data packet frame structure in the communication transmission includes a preamble, a synchronization code, and a data code. A guard interval is disposed between the preamble and the synchronization code. This method utilizes the different impact response environments of linear frequency modulation signals in different frequency bands to obtain the mapping relationships corresponding to the characteristics of the impulse responses in the frequency band, and adopts the quadrature phase shift keying (QPSK) modulation method to convert four groups of LMF signals with different center frequencies and the same modulation frequency, representing different symbols for signal transmission, where the LFM carrier signal of each center frequency can represent two bits of binary information to improve transmission efficiency. The apparatus for underwater acoustic communication also has the above-mentioned technical effects.

A method for decoding an RF signal bearing a sequence of transmitted symbols modulated by CPM. The method includes, at the receiver: estimating model parameters {h, ω, Φ.sub.0} among which h characterizes a modulation index, ω characterizes a carrier frequency offset and Φ.sub.0 characterizes an initial phase offset, and detecting received symbols corresponding to said transmitted symbols of the sequence, wherein, at time nT where T is a symbol duration, the parameters {h, ω, Φ.sub.0} are estimated by solving a system of three linear equations whose: three unknowns {ĥ.sup.(n), {circumflex over (ω)}.sup.(n), {circumflex over (Φ)}.sub.0.sup.(n)} are respectively function of said model parameters {h, ω, Φ.sub.0}, and coefficients {B.sup.(n), C.sup.(n), D.sup.(n), F.sup.(n), G.sup.(n), H.sup.(n), v.sub.1.sup.(n), v.sub.2.sup.(n), v.sub.3.sup.(n)} are computed in a recursive way in function of: a sequence of symbols {â.sub.n} corresponding to the sequence of transmitted symbols up to time nT, and measured phases {Ψ.sub.k} of samples {y.sub.k} of the RF signal received from time (n−1)T to time nT.

Systems and methods for selecting subcarriers to be used for sub-Physical Resource Block (PRB) transmission and, in some embodiments, for mapping Demodulation Reference Signals (DMRS) to resources on the selected subcarriers are disclosed. In some embodiments, a method of operation of a radio node for providing sub-PRB transmission comprises selecting two adjacent subcarriers from a set of three allocated subcarriers that are allocated for a sub-PRB transmission that uses Single Carrier Frequency Division Multiple Access (SC-FDMA) Pi/2 Binary Phase Shift Keying (BPSK) modulation using only two adjacent subcarriers out of the set of three allocated subcarriers with Discrete Fourier Transform (DFT) spread length of 2. In some embodiments, the selection is such that the selected adjacent subcarriers varies, e.g., from one cell to another. In doing so, interference is distributed.

Systems and methods for selecting subcarriers to be used for sub-Physical Resource Block (PRB) transmission and, in some embodiments, for mapping Demodulation Reference Signals (DMRS) to resources on the selected subcarriers are disclosed. In some embodiments, a method of operation of a radio node for providing sub-PRB transmission comprises selecting two adjacent subcarriers from a set of three allocated subcarriers that are allocated for a sub-PRB transmission that uses Single Carrier Frequency Division Multiple Access (SC-FDMA) Pi/2 Binary Phase Shift Keying (BPSK) modulation using only two adjacent subcarriers out of the set of three allocated subcarriers with Discrete Fourier Transform (DFT) spread length of 2. In some embodiments, the selection is such that the selected adjacent subcarriers varies, e.g., from one cell to another. In doing so, interference is distributed.