A method is provided of receiving user data from multiple transmitters, the user data from each transmitter having been encoded as a Low Density Lattice codeword, and the multiple Low Density Lattice codewords having been transmitted so as to be received as a combined signal at a receiver, the method of receiving comprising the steps of: (i) receiving the signal, (ii) calculating coefficients of linear combinations of the codewords from the multiple transmitters, (iii) calculating a scaling factor to be applied to the signal based on the coefficients, (iv) applying the scaling factor to the signal to provide a linear combination of the codewords, (v) decoding the linear combination of the codewords based on channel state information to obtain an optimal independent linear combination of user data, (vi) repeating steps (ii), (iii) (iv) and (v) to obtain at least as many optimal independent linear combinations as the number of transmitters, and recovering the user data from the optimal independent linear combinations.

Methods, systems, and devices for wireless communications are described in which different spreading sequences may be used to distinguish concurrent non-orthogonal multiple access (NOMA) transmissions. The spreading sequences may be selected based on one or more codebooks configured at a user equipment (UE) and a codebook for an uplink NOMA transmission determined based on a set of common resources allocated for the uplink NOMA transmission and a number of expected transmitters in a transmitter group. The UE may identify data to transmit in the uplink NOMA transmission, apply the spreading sequence to the data, and transmit the spread data in the uplink NOMA transmission. A base station may receive multiple concurrent uplink NOMA transmissions, perform receive signal processing to identify spreading signals and UE identity, de-spread the signals based on different spreading sequences, and demodulate and decode the de-spread signals of the NOMA UE.

Techniques for framing data in various data transmission contexts are described. A data framing technique may include a transmitter sending a data stream including repeating bits in alternating forward and reverse order. A receiver of the data stream may fold the data stream, and correlate portions of the folded data stream for purposes of validating the data stream and/or identifying an ID in the data stream. In at least some instances, once the receiver validates the data stream, the receiver may accept payload accompanying the data stream.

In order provide a communication control apparatus, a radio communication apparatus, a communication control method, a radio communication method, and a program that are capable of contributing to improving a radio communication technology related to IDMA, a communication control apparatus is provided. The communication control apparatus includes a communication unit configured to communicate with a radio communication apparatus of a radio communication system using interleave division multiple access (IDMA); and a control unit configured to allocate an interleaver type of an interleaver to be used for IDMA by the radio communication apparatus.

A method and apparatus for generation of signals with unpredictable transmission properties allowing physically secure, unscheduled and interference-resistant communication over machine-to-machine (M2M) networks is claimed. A physical dwell structure comprising time slots and frequency channels is established, and a combination of unpredictable physical dwells, spread spectrum modulation formats employing unpredictable spreading vectors, and additional physical properties allowing unpredictable selection of intended receivers is described. These unpredictable transmission properties enable receivers employing blind detection and signal separation techniques to detect and extract transmissions intended for the receive, and excise transmissions not intended for the receiver, as part of the despreading procedure, and even if those transmissions are received at a much higher power level than the intended transmissions. The resultant system eliminates the ability for an adversary to predict and override M2M transmissions; allows reception of ad-hoc transmissions in dense environments without scheduling, CSMA/CA protocols, or feedback paths enabling scheduling, and allows macrodiverse reception of transmissions at networks of connected receivers, thereby providing additional efficiency and security improvements by exploiting the route diversity of the network.

A transmitter apparatus in a wireless communication system that includes a processor. In one embodiment, the processor is configured to receive at least one modulated data message and spread the at least one modulated data message into a transmission signal using a low density signature matrix. The low density signature matrix is a cycle-free signature matrix. A receiver apparatus is configured to receive the transmission signal and detect within the received transmission signal at least one modulated data message. The processor is configured to detect the at least one modulated data message in one iteration using the cycle-free signature matrix.

Methods, systems, and devices for wireless communications are described in which different spreading sequences may be used to distinguish concurrent non-orthogonal multiple access (NOMA) transmissions. The spreading sequences may be selected based on one or more codebooks configured at a user equipment (UE) and a codebook for an uplink NOMA transmission determined based on a set of common resources allocated for the uplink NOMA transmission and a number of expected transmitters in a transmitter group. The UE may identify data to transmit in the uplink NOMA transmission, apply the spreading sequence to the data, and transmit the spread data in the uplink NOMA transmission. A base station may receive multiple concurrent uplink NOMA transmissions, perform receive signal processing to identify spreading signals and UE identity, de-spread the signals based on different spreading sequences, and demodulate and decode the de-spread signals of the NOMA UE.

A hybrid multi-layer method for decomposing of a source signal to a plurality of decomposed signals that can be used to collectively represent the source signal or recover the source signal. An example embodiment is a method that includes multi-layer (or multi-stage) signal decomposition to generate constant envelope signals without impact on the original signal. In an example embodiment, the method includes signal decomposition to maintain constant envelope properties and limit bandwidth expansion from the signal decomposition. The method includes decomposing a source signal into two first-stage decomposed signals that each have a constant envelope amplitude value. The method further includes iteratively decomposing each of the constant envelope signals into further-stage decomposed signals based on a threshold amplitude value at each iteration. The further-stage decomposed signals have a constant envelope with an envelope amplitude value in dependence of the threshold amplitude value at each iteration.

A hybrid multi-layer method for decomposing of a source signal to a plurality of decomposed signals that can be used to collectively represent the source signal or recover the source signal. An example embodiment is a method that includes multi-layer (or multi-stage) signal decomposition to generate constant envelope signals without impact on the original signal. In an example embodiment, the method includes signal decomposition to maintain constant envelope properties and limit bandwidth expansion from the signal decomposition. The method includes decomposing a source signal into two first-stage decomposed signals that each have a constant envelope amplitude value. The method further includes iteratively decomposing each of the constant envelope signals into further-stage decomposed signals based on a threshold amplitude value at each iteration. The further-stage decomposed signals have a constant envelope with an envelope amplitude value in dependence of the threshold amplitude value at each iteration.

Higher rates of data communication may be utilized for downlink than for uplink. However, the decoding complexity of Sparse Code Multiple Access (SCMA) may become prohibitive for very high rates, resulting from, for example, a large number of layers, for very large constellations, or a combination of the two. Methods and transmitters are provided herein for transmitting that has been generated to reduce complexity at the receiver and methods and receivers are provided herein for receiving and decoding a received signal with reduced complexity. The reduced complexity in part is provided by the ability to maintain real and imaginary parts of a transmitted signal independent from one another.