Abstract: A communication system and method is disclosed, applicable to the mobile communication using pilot-free channel estimation. In the uplink multiple access, the present invention utilizes the gain division multiple access (GDMA) technology to allow multiple users to share the same resource by utilizing the knowledge of different channel coefficients (channel gains) to distinguish signals transmitted by different users when the transmissions are over different and independent fading channels. Without using pilot signals for channel estimation, the present invention uses the clustering algorithm and the geometrical configuration of the superimposed signals for the superimposed signal sequence received by the base station to implement the estimation of channel gains corresponding to multiple users, and, according to the estimated channel gains, the GDMA technology is utilized to recover the original message transmitted by each user.

Abstract: A communication system and method is disclosed, applicable to the mobile communication using pilot-free channel estimation. In the uplink multiple access, the present invention utilizes the gain division multiple access (GDMA) technology to allow multiple users to share the same resource by utilizing the knowledge of different channel coefficients (channel gains) to distinguish signals transmitted by different users when the transmissions are over different and independent fading channels. Without using pilot signals for channel estimation, the present invention uses the clustering algorithm and the geometrical configuration of the superimposed signals for the superimposed signal sequence received by the base station to implement the estimation of channel gains corresponding to multiple users, and, according to the estimated channel gains, the GDMA technology is utilized to recover the original message transmitted by each user.

Abstract: A receiver for decoding a Raptor code comprises a first decoder, for performing following operations: receiving a first plurality of coded symbols encoded from a message according to the Raptor code; decoding the first plurality of coded symbols into a first plurality of decoded symbols; determining whether a second plurality of coded symbols are needed for the Raptor code according to a function of the first plurality of decoded symbols; and receiving the second plurality of coded symbols and decoding the first plurality of coded symbols and the second plurality of coded symbols into the first plurality of decoded symbols, if the second plurality of coded symbols are needed; and a second decoder, coupled to the first decoder, for decoding the first plurality of decoded symbols into a second plurality of decoded symbols.

Abstract: A multiple access communication system in which receiving devices equipped with a method of differentiating signals from multiple users assigned with the same signature, the method comprising steps of determining a plurality of hypothetical signal levels according to a plurality of channel information; obtaining a pre-processed signal according to a received signal received by the receiving device, wherein the pre-processed signal comprises a mixture of a plurality of transmitted signals, and the transmitted signals are generated according to a plurality of signatures and encoded according to a plurality of data signals; calculating a plurality of symbol-level probabilities according to the pre-processed signal and the hypothetical signal levels, wherein the number of signatures may be less than the number of users; obtaining a plurality of log-likelihood ratios, corresponding to the users, and generating a plurality of decoded signals corresponding to the plurality of data signals according to the log-likeli

Abstract: A tree decoding method for decoding a linear block code is provided. According to the tree decoding method, an estimated path metric of node v is f(v)=g(v)+h(v), where g(v) represents a sum of bit metrics of all bits on a path from the root node to the node v, and h(v) represents a lowest bound of estimated accumulated bit metrics from the node v to the goal node. The present invention creatively improves the approach for calculating h(v). According to the present invention, some parity bits are only related to a part of the information bits, according to which the edge metric h(v) of the parity bits can be preliminarily incorporated into the path metric of the part of the information bits. As such, some nodes having inferior path metric could be eliminated in advance, thus minimizing the searching range and simplifying the decoding complexity.

Abstract: The method contains the following steps. First, in a MCM system with N sub-carriers, the baseband signal blocks Xj, j=1, 2, . . . ,B are supplemented with zeros and processed with LN-point IFFT, respectively, to obtain L-time oversampled time-domain signal blocks xj, j=1,2, . . . ,B. Then, xj undergoes Q Time Domain Circular Shifts or Frequency Domain Circular Shifts to obtain Q signal blocks {tilde over (x)}j(ij), ij=1, ?, Q. Subsequently, a B×B unitary transform is performed against ( x1, {tilde over (x)}2(i2), . . . , {tilde over (x)}B(iB)). After the unitary transform, for each (i2, . . . , iB) a combination having B time-domain signal blocks is obtained as follows: ({tilde over (y)}1(i2, . . . , iB), {tilde over (y)}2(i2, . . . , iB), . . . , {tilde over (y)}B(i2, . . . ,iB))=( x1, {tilde over (x)}2(i2), . . . , {tilde over (x)}B(iB)) cU where U is the B×B unitary matrix, and c is an arbitrary constant (c?0).

Abstract: A tree decoding method for decoding a linear block code is provided. According to the tree decoding method, an estimated path metric of node v is f(y)=g(v)+h(v), where g(v) represents a sum of bit metrics of all bits on a path from the root node to the node v, and h(v) represents a lowest bound of estimated accumulated bit metrics from the node v to the goal node. The present invention creatively improves the approach for calculating h(v). According to the present invention, some parity bits are only related to a part of the information bits, according to which the edge metric h(v) of the parity bits can be preliminarily incorporated into the path metric of the part of the information bits. As such, some nodes having inferior path metric could be eliminated in advance, thus minimizing the searching range and simplifying the decoding complexity.

Abstract: The method contains the following steps. First, in a MCM system with N sub-carriers, the baseband signal blocks Xj, j=1, 2, . . . ,B are supplemented with zeros and processed with LN-point IFFT, respectively, to obtain L-time oversampled time-domain signal blocks xj, j=1,2, . . . ,B. Then, xj undergoes Q Time Domain Circular Shifts or Frequency Domain Circular Shifts to obtain Q signal blocks {tilde over (x)}j(ij), ij=1,?,Q. Subsequently, a B×B unitary transform is performed against ( x1,{tilde over (x)}2(i2), . . . ,{tilde over (x)}B(iB)). After the unitary transform, for each (i2, . . . ,iB) a combination having B time-domain signal blocks is obtained as follows: ({tilde over (y)}1(i2, . . . ,iB),{tilde over (y)}2(i2, . . . ,iB), . . . ,{tilde over (y)}B(i2, . . . ,iB)=( x1,{tilde over (x)}2(i2), . . . ,{tilde over (x)}B(iB)) cU where U is the B×B unitary matrix, and c is an arbitrary constant (c?0).

Abstract: A method for reducing the peak-to-average power ratio of the time-domain signal in a communication system using multi-carrier modulation is provided herein. The present invention is based on the method of recursive clipping and filtering to reduce the peak-to-average power ratio and out-of-band spectrum, but during the recursive process, the distortion of the multi-carrier modulated signal is controlled to be bounded within a specific region. In an additive white Gaussian noise channel with high signal-to-noise ratio, the present invention could achieve significantly lower error rate and the error floor phenomenon is almost completely removed. Therefore the power amplifier could be operated at higher average output power and a smaller range of linearity.

Abstract: A trellis code of a special class is encoded by employing a binary convolutional code with a small constraint length, followed by a convolutional processor and a signal mapper. The trellis code is decoded by the trellis of the binary convolutional code.

Abstract: This invention is a method for detecting received signal sequences of a communication system transmitting differentially encoded MPSK (Multiple Phase Shift Keying) signal sequences. This invention uses previously received signal samples and previously decided data phases to generate a phase reference for the current operation of detecting the received signal sample. The phase reference can be easily generated by a recursive form.

Abstract: This invention is a method for the detecting received signal sequences of a communication system transmitting a differentially encoded MPSK (Multiple Phase Shift Keying) or a differentially encoded 2MAPSK (2M-level Amplitude/Phase Shift Keying) signal sequence. The operation of detecting the currently received signal sample is based on a signal reference which is recursively generated by two or more previously generated signal references.

Abstract: This invention is a decoding method for a special class of trellis codes which have large free distances. The encoding of the trellis code to be decoded can be implemented by employing a single binary convolutional code followed by more than one processor. The decoding can be implemented by using the trellis of the binary convolutional code and additional processors.

Abstract: This invention is a multilevel trellis coding method which employs a single binary convolutional code and is called a single-stage and multilevel trellis coding. This invention can be generalized by combining several single-stage multilevel codings together to form a multilevel trellis coding for which the number of stages is less than the number of coding levels. New trellis coded modulation systems and binary trellis coding systems which are designed by the aforementioned trellis coding method are better than the currently known coding systems if the communication channels are additive white Gaussian noise (AWGN) channels.