Communication systems are described that use unequally spaced constellations that have increased capacity compared to conventional constellations operating within a similar SNR band. One embodiment is a digital communications system including a transmitter transmitting signals via a communication channel, the transmitter including a coder capable of receiving user bits and outputting encoded bits at a rate, a mapper capable of mapping encoded bits to symbols in a constellation, and a modulator capable of generating a modulated signal for transmission via the communication channel using symbols generated by the mapper, wherein the constellation is unequally spaced and characterizable by assignment of locations and labels of constellation points to maximize parallel decode capacity of the constellation at a given signal-to-noise ratio so that the constellation provides a given capacity at a reduced signal-to-noise ratio compared to a uniform constellation that maximizes the minimum distance between constellation points of the uniform constellation.

An apparatus for receiving signals includes a receiver for receiving a time domain signal from a transmitter, wherein at least one first information bit is mapped, resulting in at least one first mapped symbol; at least one second information bit is mapped, resulting in at least one second mapped symbol; the at least one second mapped symbol is multiplied by at least one third information bit; and the time domain signal is generated from the at least one first mapped symbol and the at least one second mapped symbol.

One embodiment provides a system for detecting and reporting information associated with RF signals. The system obtains in-phase and quadrature (IQ) data of the RF signals received at a predetermined center frequency and computes statistics associated with time-dependent changes of the IQ data. Computing the statistics includes: placing IQ data points included in the IQ data into a plurality of bins in an IQ plane; computing, for each IQ data point, a change in position in the IQ plane between the IQ data point and a corresponding IQ data point recorded prior to a predetermined time interval; and computing, for each bin, an average change in position of IQ data points inside the bin. The system assembles a data packet to be transmitted over a bandwidth-limited communication channel. The data packet includes a small number of bits representing the computed statistics associated with the time-dependent changes of the IQ data.

The present invention relates to a method and apparatus for processing a modulation symbol. The processing method includes: a transmitter obtaining a transmission power ratio j, wherein in the transmission power ratio .sub.j{.sub.0, .sub.1, .sub.2}, j is a natural number, and .sub.0, .sub.1 and .sub.2 are all positive numbers; and the transmitter modulating a first group of bit sequences b0(i), b.sub.0(i+1) and a second group of bit sequences b.sub.1(i), b.sub.1(i+1), . . . , b.sub.1(i+n) according to the transmission power ratio .sub.j so as to obtain a modulation symbol, wherein i is a natural number, and n{1, 3, 5}. The present invention solves the problem in the relevant art that an uncertain number of transmission power ratios affects the performance of a system and increases the design complexity of signaling, thereby reducing signaling overheads and improving system stability and demodulation performance.

Aspects of the present disclosure relate to retransmissions of data within wireless communication networks. For a retransmission, at least a portion of the encoded bits of an original transmission may be mapped to different bit locations in one or more modulated symbols based on a non-random mapping rule. In some examples, the encoded bits of a symbol may be reversed within the symbol for a retransmission. In other examples, the first and last encoded bits within a symbol may be switched for a retransmission. Other non-random mapping rules, such as a bit location offset, may also be used to map encoded bits to different bit locations in the modulated symbol within a retransmission.

A method for generating a non-uniform constellation is provided. The method comprises the step of performing a first process, the first process comprising the steps of: obtaining a first constellation defined by one or more parameter values; and generating a second constellation based on the first constellation using a second process. The second process comprises the steps of: obtaining a set of candidate constellations, wherein the set of candidate constellations comprises the first constellation and one or more modified constellations, wherein each modified constellation is obtained by modifying the parameter values defining the first constellation; determining the performance of each candidate constellation according to a predetermined performance measure; selecting the candidate constellation having the best performance as the second constellation.

Communication systems are described that use unequally spaced constellations that have increased capacity compared to conventional constellations operating within a similar SNR band. One embodiment is a digital communications system including a transmitter transmitting signals via a communication channel, the transmitter including a coder capable of receiving user bits and outputting encoded bits at a rate, a mapper capable of mapping encoded bits to symbols in a constellation, and a modulator capable of generating a modulated signal for transmission via the communication channel using symbols generated by the mapper, wherein the constellation is unequally spaced and characterizable by assignment of locations and labels of constellation points to maximize parallel decode capacity of the constellation at a given signal-to-noise ratio so that the constellation provides a given capacity at a reduced signal-to-noise ratio compared to a uniform constellation that maximizes the minimum distance between constellation points of the uniform constellation.

Communication systems are described that use unequally spaced constellations that have increased capacity compared to conventional constellations operating within a similar SNR band. One embodiment is a digital communications system including a transmitter transmitting signals via a communication channel, the transmitter including a coder capable of receiving user bits and outputting encoded bits at a rate, a mapper capable of mapping encoded bits to symbols in a constellation, and a modulator capable of generating a modulated signal for transmission via the communication channel using symbols generated by the mapper, wherein the constellation is unequally spaced and characterizable by assignment of locations and labels of constellation points to maximize parallel decode capacity of the constellation at a given signal-to-noise ratio so that the constellation provides a given capacity at a reduced signal-to-noise ratio compared to a uniform constellation that maximizes the minimum distance between constellation points of the uniform constellation.

Communication systems are described that use unequally spaced constellations that have increased capacity compared to conventional constellations operating within a similar SNR band. One embodiment is a digital communications system including a transmitter transmitting signals via a communication channel, the transmitter including a coder capable of receiving user bits and outputting encoded bits at a rate, a mapper capable of mapping encoded bits to symbols in a constellation, and a modulator capable of generating a modulated signal for transmission via the communication channel using symbols generated by the mapper, wherein the constellation is unequally spaced and characterizable by assignment of locations and labels of constellation points to maximize parallel decode capacity of the constellation at a given signal-to-noise ratio so that the constellation provides a given capacity at a reduced signal-to-noise ratio compared to a uniform constellation that maximizes the minimum distance between constellation points of the uniform constellation.

Communication systems are described that use unequally spaced constellations that have increased capacity compared to conventional constellations operating within a similar SNR band. One embodiment is a digital communications system including a transmitter transmitting signals via a communication channel, the transmitter including a coder capable of receiving user bits and outputting encoded bits at a rate, a mapper capable of mapping encoded bits to symbols in a constellation, and a modulator capable of generating a modulated signal for transmission via the communication channel using symbols generated by the mapper, wherein the constellation is unequally spaced and characterizable by assignment of locations and labels of constellation points to maximize parallel decode capacity of the constellation at a given signal-to-noise ratio so that the constellation provides a given capacity at a reduced signal-to-noise ratio compared to a uniform constellation that maximizes the minimum distance between constellation points of the uniform constellation.