156 results about "Qam constellations" patented technology

A digital automatic gain control (AGC) system comprising an AGC amplifier configured to scale an input signal by a scale factor, and configured to generate an analog scaled input signal. An analog-to-digital (A / D) converter is configured to sample and convert the analog scaled input signal into a digital scaled input signal. The frequency down converted digital scaled input signal is processed by a power level detector circuit to detect its power level. The logarithmic comparison circuit (LCC) is configured to compare the detected power level of the digital scaled input signal to a predetermined reference signal and configured to generate a digital error signal. Finally, an error processing circuit is configured to process the digital error signal and configured to determine the scale factor of the AGC circuit. The test results show that for any applicable QAM constellation the AGC circuit of the present invention can control the broadest fades (or decreases) in the power level of the input signal with an accuracy up to 200 dB / per second.

A method of transmitting digital information comprises the steps of forward error correction encoding a plurality of bits of digital information using complementary pattern-mapped convolutional codes, modulating a plurality of carrier signals with the forward error corrected bits, and transmitting the carrier signals. The modulation can include the step of independently amplitude shift keying in-phase and quadrature components of the QAM constellation using Gray code constellation points corresponding to amplitude levels. Transmitters that transmit signals in accordance with the method and receivers that receive such signals are also included.

The invention discloses a constellation mapping method based on an absolute phase shift keying (APSK) constellation map. The constellation mapping method is characterized in that the order M of an APSK constellation is equal to 2<m>; the number n1 of points on each ring is equal to a value of powers to 2, namely n1=2<m1>, the number n1=2<m1>-PSK (phase shift keying), the number of rings R=2<m2>, and a set consisting of different ring radiuses is a special 2<m2>-PAM(pulse amplitude modulation ), wherein m1+m2=m; and the phase deflection theta1 of all the rings are the same. The method comprises the following steps of: B1, for a bit vector which is m in length, setting m1 bits to be only related to the phase, and adopting PSK Gray mapping between the m1 bits and the 2<m1>-PSK; and B2, setting the rest m2 bits to be only related to the amplitude, and adopting PAM Gray mapping between the m2 bits and the 2<m2>-PAM. The invention has the advantages that compared with the conventional coded modulation system adopting quadrature amplitude modulation (QAM) constellation map mapping, the coded modulation system adopting the APSM constellation map Gray mapping can acquire a considerable error control performance gain regardless of adopting independent demapping or iterative demapping by a receiving end.

A method and transmitter and receiver for determining and transmitting or receiving a non-uniform QAM signal comprises selecting a signal to noise ratio for a channel and forward error corrector and then determining positions of constellation points that maximise a measure of channel capacity at the selected signal to noise ratio. The position of one constellation point and another constellation point within the constellation are constrained to be equal to one another prior to determining the positions of the constellation points. In doing so, a so called condensed QAM constellation arrangement may be derived having fewer than conventional number of constellation points for a given QAM scheme. The condensed QAM arrangement has improved performance at certain signal to noise ratios.

A MIMO detection method for a receiver in a MIMO system using N-QAM for modulation, the MIMO detection method including generating a plurality of symbol vector sets and a plurality of search radiuses, selecting a candidate symbol vector set corresponding to a highest level of a multilevel structure of N-QAM constellation, generating a search space corresponding to a lower level of the multilevel structure of N-QAM constellation according to the selected candidate symbol vector set, confirming which level the search space corresponds to, and generating a detection signal according to the search space when the level of the search space is the lowest level of the multilevel structure of the N-QAM constellation.

A transmitter may map, using a selected modulation constellation, each of C′ bit sequences to a respective one of C′ symbols, where C′ is a number greater than one. The transmitter may process the C′ symbols to generate C′ inter-carrier correlated virtual subcarrier values. The transmitter may decimate the C′ virtual subcarrier values down to C physical subcarrier values, C being a number less than C′. The transmitter may transmit the C physical subcarrier values on C orthogonal frequency division multiplexed (OFDM) subcarriers. The modulation constellation may be an N-QAM constellation, where N is an integer. The processing may comprise filtering the C′ symbols using an array of C′ filter tap coefficients. The filtering may comprise cyclic filtering. The filtering may comprise multiplication by a circulant matrix populated with the C′ filter tap coefficients.

The invention discloses a method for retransmitting a hybrid automatic request. Four constellation diagrams are defined in the method to form a rearranging HARQ technology based on a 256-QAM constellation diagram. The method comprises the following steps that: a) the first constellation diagram is defined as a standard constellation diagram, and the rearrangement of significance bit for other constellation diagrams based on the first constellation diagram is performed; b) data is mapped to the first constellation diagram to modulate and transmit, after a binary random bit stream generated by an information source is scrambled and coded by a transmitting terminal; c) a receiving terminal passes through an inverse process of step b), decodes and judges the data after modulation, when the data is correct, the data is descrambled and transmitted to an information sink; when the data is incorrect, NACK is transmitted to the transmitting terminal, and the data is mapped to the second constellation diagram, and so on, the data is mapped to the third constellation diagram and the fourth constellation diagram for the modulation and transmission in the third time and the fourth time; when the transmitting terminal receives the NACK for the fourth time, the data is mapped to the first constellation diagram once more for the modulation and the transmission, thereby finishing the circulation.

The invention discloses three schemes for processing channel coding suitable to packet data transmission of multicarrier HSDPA. First scheme: dividing data into N groups, adding CRC to each group of data, sectionalizing code block, encoding channel, treating rate match, carrying out scrambling and interlacing process for N group of matched data, dividing data into N groups again, then rearranged by QAM constellation and mapped to physical channel for transmitting. Second scheme: dividing data needed to send through HS-DSCH channel into groups, carrying out process for encoding each route of data according to single carrier HSDPA, and then through physical channel of a carrier to carry out transmission. Third scheme: N pieces of carrier channel considered as a whole are sent to physical layer, then carrying out process from adding CRC to rearranging QAM constellation, grouping data after rearrangement of QAM constellation, mapping the grouped data to carrier channel for transmission.

A digital television (DTV) system uses parallel concatenated coding (PCC), together with QAM constellations for modulating OFDM carriers. A first encoder responds to bits of randomized data to generate a first component of parallel concatenated coding. A second encoder responds to delayed bits of the randomized data to generate a second component of parallel concatenated coding. A constellation mapper generates QAM symbols responsive to successive time-slices of the first component of the PCC interleaved with successive time-slices of the second component of the PCC. An OFDM modulator generates a COFDM modulating signal responsive to the QAM symbols. In a receiver for the DTV system, the second component of the PCC and delayed first component of the PCC are iteratively decoded. Corresponding soft bits from the second component and delayed first component of the PCC are combined to supply soft randomized data used in that iterative decoding.

A MIMO detection method for a receiver in a MIMO system using N-QAM for modulation, the MIMO detection method including generating a plurality of symbol vector sets and a plurality of search radiuses, selecting a candidate symbol vector set corresponding to a highest level of a multilevel structure of N-QAM constellation, generating a search space corresponding to a lower level of the multilevel structure of N-QAM constellation according to the selected candidate symbol vector set, confirming which level the search space corresponds to, and generating a detection signal according to the search space when the level of the search space is the lowest level of the multilevel structure of the N-QAM constellation.

A Viterbi decoding system interprets bits in received QAM constellations as many-valued parameters rather than binary valued parameters. It performs the Viterbi algorithm using these many-valued parameters to provide results superior to hard decision decoding. Rather than applying a hard 0-1 function to the QAM data, the system uses a non-stepped linear or curved transfer function to assign values to the bits. In another aspect, a system differentiates between data bits based on their estimated reliability, giving more emphasis to decoding reliable bits than unreliable bits using any of a variety of techniques. By differentiating between god and bad bits and de-emphasizing or ignoring unreliable bits, the system can provide a significant reduction in uncorrectable errors and packet loss.

The invention discloses an encoding modulating method. In a modulating process, regular constellation mapping or irregular constellation mapping is carried out on bit data, so as to obtain a constellation mapping symbol, wherein the regular constellation mapping means that the mapping from a bit to a symbol is completed by adopting one constellation diagram and one constellation point mapping way, and the irregular constellation mapping means that the mapping from the bit to the symbol is completed by adopting one constellation diagram and more than one constellation point mapping ways. The invention further discloses a demodulation decoding method corresponding to the encoding demodulating method. In the invention, through using regular APSK (amplitude phase shift keying) constellation mapping at a sending end, the shaping loss can be obviously reduced, or by using irregular QAM (quadrature amplitude modulation) constellation mapping, the decoding and the de-mapping are matched more,so as to improve the transmission capability of an encoding modulating system, and through adopting iterative de-mapping at a receiving end, the loss brought by independent de-mapping can be effectively reduced, so as to obviously improve the performance of the encoding modulating system based on the iterative de-mapping.

Systems and methods for constellation shaping of M-QAM modulation formats in optical transport networks may receive binary data to be transmitted as an optical signal and partition symbols of an M-QAM constellation in the complex plane into two non-overlapping subsets of symbols, The systems and methods may include assigning respective probabilities to each symbol in the first subset of symbols dependent on a target probability distribution for the first subset, mapping at least a portion of the received binary data to the symbols in the first subset, including generating a respective codeword for each symbol in the first subset, in a first symbol period, providing data representing the respective codewords mapped to the symbols in the first subset to an optical modulator for transmission, and refraining from providing any data representing codewords mapped to the symbols in the second subset to the optical modulator until a second symbol period.