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.

To enable low latency uplink to be used in a more preferable mode can be provided. A device includes: a communication unit configured to perform radio communication; and a control unit configured to perform control such that control information is transmitted from the communication unit to a terminal, the control information indicating that a communication scheme in which data non-orthogonally multiplexed for a plurality of layers is demodulated through cancellation of interference between the layers and in which the data is transmitted from the terminal to a base station through a predetermined uplink resource, is available.

A coded imaging and multi-user communications systems using novel codes, algorithms to develop such codes, and technological implementations to use the codes for various types of systems involving multiple (or single) transmitters and multiple (or single) receivers of signals (which could include but are not limited to electromagnetic radiation, acoustic waves, other types of waves or data) as a function of time-or-space.

Provided are a base station apparatus, a terminal apparatus, and a communication method, in all of which interference is reduced to improve throughput and to increase more opportunity for communication by each terminal apparatus. A terminal apparatus according to the present invention is provided with a function of receiving information relating to a multiplexed state of and information relating to a retransmission state of a transmit signal that is transmitted to the terminal apparatus itself; a function of receiving a non-orthogonal multiplexing signal that results from a base station apparatus non-orthogonally multiplexing at least some of the transmit signal that is transmitted to the terminal apparatus itself and a transmit signal that is transmitted to another terminal apparatus, for transmission, using the same radio resource; and a function of performing demodulation processing based on the information relating to the multiplexed state of the transmit signal that is transmitted to the terminal apparatus itself, and the information relating to the retransmission state of the transmit signal that is transmitted to the terminal apparatus itself.

Disclosed are methods and apparatus used in wireless communications. The methods and apparatus establish a codebook for use in sparse code multiple access (SCMA) encoded communications, in particular. The SCMA codebook is configured to set the codebook for at least one layer (i.e., a user) to include a constellation of points having a first grouping of constellation points located at first radial distance from an origin in a complex plane and a second grouping of constellation points located at a second radial distance from the origin. This codebook arrangement provides increased gains at receivers by optimizing the constellation shape to improve the distance between constellation points (i.e., SCMA codebook performance), and in particular more robust performance when encountering amplitude and phase misalignment in uplink (UL) multiple access.

A communication receiving apparatus, a signal receiving method thereof, a signal processing method, and a signal transmitting method based Code Division Multiple Access (CDMA) technology are provided. The signal processing method includes the following steps: the communication transmitting apparatus encodes an original data sequence based on a perfect Gaussian integer sequence (PGIS) to generate a spread signal and transmits a radio frequency (RF) signal including the spread signal. An autocorrelation function of the PGIS conforms to an impulse characteristic, and the PGIS has a spectrum with equal magnitude. The communication receiving apparatus obtains the RF signal from the communication transmitting apparatus and transforms the RF signal into a baseband signal. The baseband signal is de-modulated into a data stream by the communication receiving apparatus. The data stream is recovered into at least one data value of the original data sequence based on the PGIS by the communication receiving apparatus.

A method and apparatus for physically secure communication over machine-to-machine (M2M) networks is claimed, through the use of frequency-hop and random access spread spectrum modulation formats employing using truly random spreading codes and time/frequency hopping and receiver selection strategies at the transmitters in the M2M network, blind signal detection and linear signal separation techniques at the receivers in the M2M network, completely eliminating the ability for an adversary to predict and override M2M transmissions. Additional physical security protocols are also introduced that allow the network to easily detect and identify spoofing transmissions on uplinks and downlinks, and to automatically excise those transmissions as part of the despreading procedure, even if those transmissions are received at a much higher power level than the intended transmissions. Extensions to weakly and strongly macrodiverse networks are also described, which provide additional efficiency and security improvements by exploiting the route diversity of the network.

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.

Method and apparatus embodiments are provided for low complexity message passing algorithm (MPA) detection with substantially minor or tolerated performance loss compared to the standard MPA. A method includes calculating, at a detector, a plurality of function nodes (FNs) according to a plurality of received multiplexing signals for a one or a plurality of user equipments (UEs) using a plurality of first MPA computations that map a plurality of variable nodes (VNs) corresponding to the UEs to the FNs and using a priori information in an initial vector of probabilities for each of the VNs, excluding from the first MPA computations a plurality of first relatively small multiplication terms, updating the probabilities for the VNs using the last calculated FNs and a plurality of second MPA computations that map the FNs to the VNs, and excluding a plurality of second relatively small multiplication terms from the second MPA calculations.

In one embodiment, a method for blindly detecting low density activity includes receiving, by a first node from a second node, a signal and executing a joint message passing algorithm (JMPA) on the signal, where executing the JMPA includes jointly producing a decoded signal and an activity list in accordance with the decoded signal, and calculating a plurality of a priori probabilities in accordance with a plurality of log likelihood ratios (LLRs) corresponding to the signal and a plurality of decoded LLRs.