Abstract: A communication system that sends and receives signals via each of two adjacent channels ch1 and ch2 in which interchannel interference exists, wherein the receiver device comprises a soft decision target value generation unit for each of a plurality of received bits inputted from the corresponding channel; and a soft decision unit that makes a soft decision with respect to each of the plurality of received bits by using the respective soft decision target values. Each soft decision target value generation unit generates its own soft decision target values by using the respective soft decision target values of the plurality of bits inputted from the receiver device of the other channel and the soft decision unit makes a decision with respect to the received bits on the basis of the soft decision target values.

Abstract: In a communication system 10, a method and apparatus provide for decoding a sequence of turbo encoded data symbols. The channel nodes Rx, Ry and Rz are updated based on a received channel output, and the outgoing messages from symbol nodes (701, 707, 708) are initialized. The symbol nodes symbol nodes (701, 707, 708) are in communication with the channel nodes Rx, Ry and Rz. Updates of computational nodes C (704) and D (706) at different time instances are performed in accordance with a triggering schedule.

Abstract: A sub-optimal method is disclosed for calculating the reliability values (soft values) for the bits of a multilevel signal. The log-likelihood values are approximated using only the dominant terms, so called max-log approximation, that is for each bit position only the two closest signal symbols of opposite bit value (S8, S6) are considered in the sum. The used modulation scheme is 16-QAM together with Gray-labelling. Two versions of approximation are proposed: one version consists of using the two distances between the received value and the two closest symbols of opposite bit value (?1 ?2 ). In order to simplify and speed up the calculation, the second version consists of using the distance between the two closest symbols (?3 ) to approximate the distance between the second closest symbol and the received value. Furthermore, precalculated results are stored in look-up tables to speed up the calculation.

Abstract: An image transmitter, comprising: a color difference differential calculating unit configured to calculate color difference differential data relating to a difference between a current predicting value predicted based on a previous image data and current actual image data; a coding unit configured to code the color difference differential data to generate coding data; a multi-valuation unit configured to generate multi-valued data based on the coding data and an occurrence probability of the coding data based on statistical properties of the image data; and a transmitting unit configured to transmit the multi-valued data via at least one transmission line.

Abstract: The invention relates to a method for improving the performance of data transmissions over a communications channel, wherein data is coded and modulated for transmission, wherein coding the data results in differently coded bits. In order to allow for a simple way of a more flexible coding, it is proposed that the differently coded bits are mapped for modulation to different modulation symbols of a symbol alphabet, to which modulation symbols different relative reliabilities are assigned, and wherein by mapping the coded bits to the modulated symbols, different reliabilities are associated to differently coded bits depending on the conditions on the communications channel. The invention equally relates to a corresponding communications system and to elements of such a communications system.

Abstract: A wireless communication receiving device includes an initializing section for obtaining a temporary solution from a transmission route estimation value and a reception signal, a solution candidate calculating section for obtaining a solution candidate for each dimension existing inside a search area around the temporary solution, a solution candidate selecting section for deleting a solution candidate a cumulative distance of which is large when the number of solution candidates exceeds a specified resource number, a distance calculating section for obtaining a partial distance between the temporary solution and the solution candidate for each dimension, and a cumulative distance of the obtained partial distances, and a distance comparing section.

Abstract: A decoder may include a constellation mapper arranged to receive a symbol and to determine two constellation points that are proximate the received symbol. An index mapper may determine a constellation index corresponding to the received symbol based on the received symbol and the two constellation points that are proximate the received symbol. A coset selector may receive successive constellation indices from the index mapper and may determine a number of nearest cosets to the successive constellation indices.

Abstract: A method for diversity transmission and reception for channels with intersymbol interference is created. With this method one can transmit from two or more antennas in such a way that a receiver with one or more antennas can benefit from the diversity offered by the difference in channels from the transmit antennas to the receiver antenna(s). The way the transmission and reception is organized makes it relatively simple to in the receiver detect the transmitted symbols despite intersymbol interference in the channel. Due to the increased diversity experienced by the receiver the average power level required at the receiver is reduced which can be used to increase the capacity or coverage of a wireless network and/or reduce the required transmitted power.

Abstract: We describe a voltage level coding system and method. The voltage level coding system includes a level encoder having an input to receive data segments coded using a first code and an output to supply second data codes indicating one of 2N plus at least one additional voltage level to which each data segment is assigned. A converter converts the second data codes into such voltage levels. A controller output supplies the voltage levels. A method for coding digital data includes determining a first data transition, generating a code that includes at least one additional level that minimizes data skew in the first data transition, and coding the first data transition with the additional level in the code.

Abstract: In the case of a method and a device for transmitting data units by way of a transmission medium that comprises at least three adjacent transmission lines, first of all a plurality of codes is supplied. Each code has a number of code sections that corresponds to the number of transmission lines of the transmission medium. Each code section has on an associated transmission line a predetermined signal value, the sum of the signal values for each transmitted code being substantially constant. For each data unit to be transmitted, a code is selected from the plurality of codes, and the selected code is supplied for transmission by way of the transmission medium. The data units and the codes to be transmitted can be supplied in accordance with a predetermined clock pulse, a new code being selected at each new clock pulse, based on the preceding code and the new data unit.

Abstract: Methods and apparatus for use in making improved symbol decisions in a demodulator in the presence of distortion in the received signaling. In one implementation, a method includes the steps of: determining a centroid symbol location for a received symbol of a constellation, the centroid symbol location different than an ideal symbol location due to distortion of the received symbol; and adjusting a decision line bounding the received symbol based on the centroid symbol location. In preferred embodiments, the method is implemented in a satellite communication system, which the distortion is a nonlinear distortion and is caused by a high power amplifier at the transmitting terminal and in which bandwidth efficient modulation formats are used to transmit data at a high rate. In some embodiments, centroid symbol locations are used to improve soft decision decoding.

Abstract: A multilevel LINC transmitter. The multilevel LINC transmitter comprises a multilevel signal component separator, a phase modulator block, a mixer block, an up-converter block, a predistorter and an RF block. The multilevel signal component separator comprises a multilevel scaler and converts an input signal to phase signals. The phase modulator block and the predistorter are coupled to the multilevel signal component separator. The mixer block is coupled to the phase modulator block and the predistorter. The up-converter block is coupled to the mixer block. The RF block comprises a plurality of power amplifiers coupled to the up-converter block and a power combiner coupled to the power amplifiers.

Abstract: A method and apparatus for data communication in a variety of communication systems using spread spectrum techniques and multilevel sequences in which distinct multilevel sequences used contain binary subsequences that interfere constructively such that synchronous cross-correlation values add constructively. By adding two subsequences from different sets, it is ensured that neither subsequence belongs to the same set. This, in combination with use of correlators, reduces complexity and facilitates increasing the order of a modulation scheme, thus enhancing the bandwidth efficiency.

Abstract: A method for diversity transmission and reception for channels with intersymbol interference is created. With this method one can transmit from two or more antennas in such a way that a receiver with one or more antennas can benefit from the diversity offered by the difference in channels from the transmit antennas to the receiver antenna(s). The way the transmission and reception is organized makes it relatively simple to in the receiver detect the transmitted symbols despite intersymbol interference in the channel. Due to the increased diversity experienced by the receiver the average power level required at the receiver is reduced which can be used to increase the capacity or coverage of a wireless network and/or reduce the required transmitted power.

Abstract: In a QAM modulation system, (3p+1) or (3p+2) input signal strings, where p is an integer not less than 3 or 2, are converted into three (p+1) string signals which are then allocated to three phase planes. The converted three (p+1) string signals are time-division multiplexed and multi-level modulated to realize QAM modulation in which the n-ary number may be set to approximately 2(p+1/3) or 2(p+2/3). In a QAM modulation system, (4p+3) input signal strings, where p is an integer not less than 3, are converted into three (p+1) string signals, which are then allocated to three phase planes, time-division multiplexed and multi-level modulated to realize QAM modulation in which the n-ary number may be set to approximately 2(p+3/4).

Abstract: The multilevel data encoding and modulation technique uses a pair of complementary logic sets. In its most basic form, the sets are binary sets each containing a line level for a logical one and a line level for a logical zero for a total of four logic levels. The encoding technique requires a polar change in the line level after every bit. An optional fifth level may be used in order to skew the frequency or to enable automatic gain control circuitry to ensure consistent level discrimination. The encoding technique may be used in a bipolar device, or a bias level may be applied to the signal for unipolar transmission. The encoding technique involves inverting the polarity of alternating bits, filtering out all odd harmonics, transmitting and receiving the waveform, and decoding the demodulated waveform by comparing the absolute value of the half-cycle peak-to-peak voltage gain to a predetermined table.

Abstract: The present invention provides a system and method for implementing a new TEQ training approach that trains TEQ coefficients by exploiting both time-domain and frequency-domain information. An advantage of this technique is that it reduces memory usage due to the training process. In addition, the complexity of the training process is simplified, and the associated computational work is reduced. The reduction of memory usage and computational work in turn may lead to cost savings, power consumption savings and other advantages.

Abstract: This disclosure describes a flexible digital transmission system that improves upon the ATSC A/53 HDTV signal transmission standard. The system includes a digital television signal transmitter for generating a first Advanced Television Systems Committee (ATSC) standard 8-VSB bit stream and, for generating an encoded new bit stream capable of transmitting high priority information bits, wherein symbols of the new bit stream are capable of being transmitted according to a transmission mode selected from group comprising: a 2-VSB mode, a 4-VSB mode, and a hierarchical-VSB (H-VSB) transmission mode. Each respective 2-VSB, 4-VSB, and H-VSB mode is characterized as having symbols mapped according to possible symbol values from an alphabet comprising respectively, {?7, ?5, 5, 7}, {7, 3, ?3, ?7}, and {7, 5, 3, ?3, ?5, ?7}. The standard 8-VSB bit stream and new bit stream may be simultaneously transmitted over a terrestrial channel according to a broadcaster defined bit-rate ratio.

Abstract: RF communications received by a wireless terminal from a servicing base station are used to determine the channel quality such as reported bit error probability (BEP). The RF communications may be in the form of RF bursts that are part of a data frame. An estimated BEP may be determined from the signal to noise ratio (SNR) of the RF bursts and or a sequence of soft decisions extracted from the RF bursts, and their historical performance. The SNR maps to an estimated BEP based upon the modulation format of the RF bursts. The soft decisions decode to produce a data block. When the soft decisions decoded favorably, the re-encoded data block produces a sequence of re-encoded decisions. Comparing the re-encoded decisions to the soft decisions yields a re-encoded bit error (RBER). The reported BEP may be based upon the estimated BEP, RBER, and/or RBER threshold. The RBER threshold may be adaptively incremented or decremented depending upon whether or not the RF communications were properly decoded.

Abstract: In digital communications, a multi-mode block-coded modulation/demodulation method carries out adaptive one-way transmission of a multi-mode digital signal by using, between at least two different modes, different settings for level number, level code, set-partitioning method and modulation method that are component elements of a multi-level block-coded modulation system.

Abstract: A coding method for modulating carrier signals with 16 different digital states (4 bit signals) possesses a high synchronicity robustness and an at least partially improved coding gain. The coding parameters are obtained by the following steps: a) using a 2 ASK/8 PSK coding; b) choosing a convolutional code and determining all possible code word sequences with the free distance of the convolutional code; c) producing possible mappings by allocating a partial quantity of the 2 ASK/8 PSK channel bits to subsets; d) choosing the mapping at which, after determination of the optimum radii of the two amplitudes for every possible mapping, the resulting minimum Euclidean distance takes a maximum value between two possible subset sequences code word sequence.

Abstract: A coding apparatus capable of preventing deterioration in demodulation performance without increasing interfering power. In the apparatus, a turbo coding section (100) performs turbo coding on transmission data, and outputs systematic bits and parity bits. A selecting section (200) selects either of two parity bit sequences output from the turbo coding section (100) to output to a mapping section (300-2). Another mapping section (300-1) modulates the systematic bits and performs symbol mapping. The mapping section (300-2) modulates the parity bits and performs symbol mapping. At this time, mapping sections (300-1 and 300-2) perform modulation in modulation schemes instructed from a modulation scheme instructing section (500). The modulation scheme instructed to the mapping section (300-2) is different from the modulation scheme instructed to another mapping section (300-1).

Abstract: A communication system for transmitting a six-phase modulated signal and including an efficient error correction system suitable for the six-phase modulated signal is disclosed. A transmitting apparatus comprises a ternary error correction encoding circuit for generating a ternary transmit sequence, a parity generation circuit for generating a parity, a parity insertion circuit for inserting the parity into a binary transmit sequence, and a six-phase modulator for performs six-phase modulation.

Abstract: A multi-tone modulation method is provided which reduces a peak average power ratio. The method involves defining a respective signal constellation for each center frequencies having redundant mappings for each set of input elements, and then selecting a particular permutation of mappings having a reduced peak power for the multi-tone signal. A method of shaping is also employed in which a hierarchy of blocks are defined, each layer having fewer blocks than each previous layer. The hierarchy is used to select a particular subset of an expanded constellation.

Abstract: An OFDM baseband signal that has undergone a synchronization carrier modulation or a differential carrier modulation is inputted to a complex signal converter for nonlinear distortion equalization so as to be converted according to the N-th order function conversion characteristics (N>1). Then, nonlinear distortion in the OFDM baseband signal is compensated for. At this time, the following is used as a conversion equation: y(n)=x(n)+?am(n)xm(n)(m>1) wherein the values of the input signal, the output signal and the coefficient for m-th order distortion equalization at time n are, respectively, x(n), y(n) and am(n).

Abstract: A signal constellation is optimized for trellis coded modulation in fast fading channels, where the receiver does not have perfect knowledge of the channel parameters. Specifically, the signal constellation is partitioned into 2n mutually exclusive subsets, each preferably defining two points. Points within each subset are separated from one another by a distance between conditional distributions, preferably a Kullback-Leibler (KL) distance. For a block m=k1+k2 of information bits input into a trellis coder 30, the k1 bits are trellis encoded into n bits (n>k1) and used to select a subset of the constellation. The k2 bit(s) is/are used to select a particular point within the subset. Because the inter-subset distance between points is a KL distance that is effectively greater than a Euclidean distance, error at the receiver is substantially reduced, especially at higher SNR. Using a KL distance ensures statistics of channel fading are inherent within the signal constellation.

Abstract: Disclosed is a method for providing first and second interleaved bit streams to a modulator in order to transmit the first and second interleaved bit streams through at least two antennas in a mobile communication system. An encoder encodes a transmission data stream into a first bit stream with first priority and a second bit stream with second priority being lower than the first priority. An interleaver interleaves the first and second bit streams into the first and second interleaved bit streams. The modulator modulates the first and second interleaved bit streams.

Abstract: A transmitting circuit apparatus has a first digital modulator and a second digital modulator for modulating an I signal and a Q signal which are multi-valued digital baseband modulation signals, into a digital I signal and a digital Q signal, respectively, having the number of bits smaller than that of the baseband modulation signals; and a quadrature modulator for outputting a signal synthesized from the signals generated by modulating (two) carrier waves each having a phase perpendicular to each other by using the modulated I and Q signals, respectively.

Abstract: A method and a circuit arrangement for efficient use of multistage modulation methods using orthogonal base functions for the representation of a signal to be transmitted. Signal points of a signal constellation are selected according to a respective predetermined and/or selected probabilities so as to optimize a respective signal energy and/or a respective signal data rate, the selected signal points each having a defined respective energy. A 16-QAM signal constellation can be used, for example, for transmitting at low data rates. In the circuit arrangement, a source (1) which supplies a data stream (2) and is connected to a code converter (3) for converting the data stream. The output of the code converter (3) is connected to a modulator (4) in which the corresponding signal points are selected according to the respective probabilities. The data stream (2) is then transmitted over a channel (5), and a demodulator (6) situated downstream from a code converter (7) carries out the inverse operation.

Abstract: A method is presented for increasing data throughput in a communications channel comprising the steps of selecting a first data packet from a queue of data packets to be transmitted over a communications channel, modulating said first data packet using a first modulation scheme, selecting a second data packet from a queue of data packets to be transmitted over the communications channel, modulating the second data packet using a second modulation scheme overlaying the first data packet on a symbol by symbol basis, transmitting the first data packet overlaid with second data packet over the communications channel, determining whether the first data packet was received by monitoring using the first modulation scheme for an acknowledgment for the first data packet before expiration of a timeout period, determining whether the second data packet was received by monitoring using the first modulation scheme for an acknowledgment for the second data packet before expiration of the timeout period and repeating the st

Abstract: The invention enables a communication device to efficiently communicate large circular signal constellations by embedding a square signal constellation in each of the circular signal constellation points. By embedding a square signal constellation in the error free slicing region associated with each circular constellation signal point, the beneficial shape of the circular constellation is retained while significantly increasing the amount of information that can be transmitted in each constellation. The invention allows the communication of high bit-per-symbol signal constellations (on the order of 15 or more bits-per-symbol) without the added cost of external memory for large look-up tables or the cost and power consumption of line drivers required to communicate high peak factor square signal constellations.

Abstract: Disclosed is a method for wireless signal transmission of signals from an array of two or more antennas, in which each signal to be transmitted is selected from a constellation of unitary space-time signals. Each unitary space-time signal is a unitary matrix, in which each column represents a respective antenna, each row represents a respective time interval, and each element represents a complex amplitude to be transmitted by a given antenna during a given time interval. In specific embodiments of the invention, the matrices of the signal constellation form a non-Abelian group having a positive diversity product, or a coset of such a group. In other embodiments, the signal constellation is a subset of such a group, and its multiplicative closure forms a finite non-Abelian group having a positive diversity product.

Abstract: The invention relates to a method for improving the performance of data transmissions over a communications channel, wherein data is coded and modulated for transmission, wherein coding said data results in differently coded bits. In order to allow for a simple way of a more flexible coding, it is proposed that said differently coded bits are mapped for modulation to different modulation symbols of a symbol alphabet, to which modulation symbols different relative reliabilities are assigned, and wherein by mapping said coded bits to said modulation symbols, different reliabilities are associated to differently coded bits depending on the conditions on said communications channel. The invention equally relates to a corresponding communications system and to elements of such a communications system.

Abstract: A digital wireless communication apparatus includes a first modulator that modulates a pilot symbol according to a first modulation scheme, and a second modulator that modulates specific symbols according to a second modulation scheme, the second modulation scheme being different than the first modulation scheme. A third modulator modulates symbols other than the pilot symbol and the specific symbols according to a third modulation scheme, the third modulation scheme being different than the first and second modulation schemes. A timing controller controls timing such that the specific symbols are inserted immediately before and after the pilot symbol. The signal points of the specific symbols are allocated on an imaginary line that connects the origin point and a signal point of the pilot symbol on a signal space diagram.

Abstract: A duplicating section 11 duplicates a bit sequence to be input, and a 16QAM section 121 modulates a bit sequence of a duplicating source to form a symbol, a 16QAM section 122 modulates the duplicated bit sequence to form a symbol, an S/P section 13 parallel converts the symbol sequence input in series, an S/P section 14 parallel converts the symbol sequence input in series, and an IFFT section 15 provides IFFT processing to the input symbol sequence. Since each of multiple same bits duplicated by the duplicating section 11 is included in a different symbol, each of the multiple same bits is allocated to each of multiple subcarriers each having a different frequency by IFFT processing. As a result, a multicarrier signal including the multiple same bits each having a different frequency is generated.

Abstract: An wireless terminal includes a demodulating unit which comprises an FV (fading vector) estimating unit for receiving a CPICH spread/demodulated signal to output an FV signal with a reduced noise ratio; a phase synchronization unit for multiplying a PDSCH spread/demodulated signal with a complex conjugate of the FV signal to correct the phase offset of the PDSCH I and Q signals to send the resulting PDSCH I and Q signals to a multi-level QAM amplitude synchronization detection unit and to an amplitude demodulating unit; a first-quadrant transformation unit for collecting the second to fourth quadrant signals of the phase-synchronized PDSCH I and Q signals; and a threshold value detecting unit for calculating a multi-level QAM threshold value from the first quadrant signals and the FV signals to send the threshold signal to an amplitude demodulating unit. The amplitude demodulating unit effects amplitude demodulation to output multi-level QAM demodulated signals.

Abstract: A method of encoding a plural-bit data word as a plurality of multi-level symbols, where each of the plurality of multi-level symbols has a value selected from a predetermined plurality of levels. The method includes first translating each one of the selected bit positions of the plural-bit data word to one of the levels. When the contents of a predetermined one of the bits of the data word is a predetermined value, the method provides a second translation of each of the selected bit positions of the plural-bit data word to one of the levels. The method further includes generating a plural-bit offset word from predetermined bit positions of the data word and generating the multi-level symbols by addition of the offset word to the translated levels. One embodiment of the invention provides that the multi-level symbols are assigned a five-level code and the codes are treated as twos-complement numbers.

Abstract: In some embodiments of the present invention, there is a system and method of synchronizing a QAM demodulator by determining a phase offset error value between an actual phase shift of a received symbol and an estimated phase shift value.

Abstract: A modulation device comprises a modulation unit (2) that modulates data in a hierarchical manner using multiple types of modulation techniques, and a transmission unit (3) that transmits the hierarchically modulated data. A demodulation device comprises a receiving unit (4) that receives the hierarchical modulation data having been subjected to hierarchical modulation using multiple types of modulation techniques, and a demodulation unit (6) that demodulates the hierarchical modulation data using a demodulation technique corresponding to a specific hierarchy of the hierarchical modulation data.

Abstract: A communication system (20) employs fixed rate channel-optimized, trellis-coded quantization (COTCQ) at a plurality of diverse encoding bit rates. COTCQ is performed through a COTCQ encoder (40) and COTCQ decoder (54). The COTCQ encoder and decoder (40,54) each include a codebook table (62) having at least one codebook (64) for each encoding bit rate. Each codebook (64) is configured in response to the bit error probability of the channel (26) through which the communication system (20) communicates. The bit error probability influences codebooks through the calculation of channel transition probabilities for all combinations of codewords (90) receivable from the channel (26) given all combinations of codewords (90) transmittable through the channel (26). Channel transition probabilities are responsive to base channel transition probabilities and the hamming distances between indices for codewords within subsets of the transmittable and receivable codewords.

Abstract: A method and apparatus for deshuffling received shuffled data in a communication system supporting multi-level modulation. A transmitter encodes information bits and shuffles code symbols so that systematic symbols having a relatively high priority are disposed at high-transmission reliability positions and parity symbols having a relatively low priority are disposed at low-transmission reliability positions in a modulation symbol. A receiver demodulates received data and outputs a modulation symbol having a plurality of code symbols, stores the code symbols separately as systematic symbols and parity symbols in corresponding memory areas according to a deshuffling order corresponding to the shuffling, reads the stored code symbols, decodes the stored code symbols at a predetermined code rate, and thus outputs an packet.

Abstract: For conveying coded digital information in the form of multiple-valued symbols from a transmitter to a receiver, the steps of a) encoding digital information in a Hybrid Concatenated Code encoder (501), b) mapping the encoded digital information into multiple-valued symbols in a Multi-Level Coding encoder (511, 512a-d, 513, 514), c) transmitting the multiple-valued symbols, d) receiving the multiple-valued symbols, and e) decoding the received multiple-valued symbols in a Multi-Stage Decoder (800) are employed.

Abstract: The present invention concerns a method for detecting a plurality of symbols (dk(i)) transmitted by or for a plurality K of users, each symbol belonging to a modulation constellation, said method comprising a filtering step filtering a received signal for supplying a vector (z) each component of which being related to a user, said method further comprising a searching step for searching the closest neighbour of said vector among candidates belonging to a lattice of points generated by said modulation constellations, the search being limited to a volume centered around said vector and being carried out by sequentially selecting a coordinate (bk) of a candidate for each dimension of said vector. The components of said vector are reordered according to an ordering rule prior to said search, the ordering rule being chosen so as to eliminate a higher rate of candidates for a first dimension than for a subsequent dimension to be searched.

Abstract: A highly modular PACS-based system that combines the advantages of Optical Frequency Division Multiplexing (OFDM) and Personal Access Communication System (PACS) with Time Division Multiple Access (TDMA) technology. The system is arranged to support high-speed (higher than the 32 kbps of PACS) wireless access services to fixed and mobile users. For example, nominal user data rates of 32-to-356 kbps are attainable, and ever the higher speed of 768 kbps is possible for short ranges.

Abstract: Methods for bit allocation and power tuning for optimizing a setup time in a multi-channel communication system. In one aspect, a bit allocation method includes measuring a signal-to-noise ratio (SNR) of each subchannel of a channel, determining a greatest allocable bit number of each subchannel using the measured SNR of the subchannels, determining a sum of the greatest allocable bit numbers of the subchannels, and determining a difference between the sum of the greatest allocable bit numbers of the subchannels and a target bit number. For each subchannel, a currently allocated bit number of the subchannel is set equal to the greatest allocable bit number of the subchannel, if the difference between the sum of the greatest allocable bit numbers and the target bit number is less than or equal to a predetermined value.

Abstract: A method for determining the signal constellation of a received signal establishes a moment based on each waveform, squares the moment, fourth powers the moment, divides the fourth power by the square to obtain a ratio, and compares the ratio to a threshold. If the ratio is less than threshold, the signal constellation corresponds to a first type, and if greater than the threshold, the signal constellation corresponds to a second type. The method can be generalized to a magnitude mean in place of a second moment.

Abstract: A system for the estimation of the complex gain of a transmission channel is designed for parallel type modulators/demodulators that can be used in digital radio broadcasting. The system includes a given number N of sets of interpolators to estimate the gain on a useful symbol from known symbols constituting gain references evenly positioned in the transmitted signal, each set of interpolators being adapted to a particular situation of reception, ranging from a stable single-path channel to a channel with high temporal dispersion and high instability. The outputs of the interpolators are coupled to a selection device programmed to choose the set of interpolators that gives the weakest estimated noise during a specified length of time. Such a system may find application to digital radio transmission.

Abstract: At a transmitting end, a selector multiplexes a command and data inputted from different systems to generate a multiplexed signal string(s). An encoding portion determines an amplitude value of a current multilevel code according to predetermined encoding rules based on a detected symbol and the amplitude value of a multilevel code generated immediately before and generates a multilevel code string. A transmitting portion transmits the generated multilevel code string to a receiving end through a transmission path. A decoding portion of the receiving end decodes and reproduces the command and the data with an amplitude value of the multilevel code string outputted from a receiving portion and the amplitude value of the multilevel code immediately before received according to predetermined decoding rules. The decoding portion separately outputs the command and the data. This allows various types of information to be multiplexed and transmitted with small delay.

Abstract: A multi-tone modulation method is provided which reduced a peak average power ratio. The method involves defining a respective signal constellation for each center frequencies having redundant mappings for each set of input elements, and then selecting a particular permutation of mappings having a reduced peak power for the multi-tone signal. A method of shaping is also employed in which a hierarchy of blocks are defined, each layer having fewer blocks than each previous layer. The hierarchy is used to select a particular subset of an expanded constellation.

Abstract: At the transmitter side, carrier waves are modulated according to an input signal for producing relevant signal points in a signal space diagram. The input signal is divided into, two, first and second, data streams. The signal points are divided into signal point groups to which data of the first data stream are assigned. Also, data of the second data stream are assigned to the signal points of each signal point group. A difference in the transmission error rate between first and second data streams is developed by shifting the siganl points to other positions in the space diagram expressed at least in the polar coordinate system. At the receiver side, the first and/or second data streams can be reconstructed from a received signal. In TV broadcast service, a TV signal is divided by a transmitter into low and high frequency band components which are designated as first and second data streams respectively.