Abstract: Embodiments relate to a baseband processing apparatus and a baseband processing method based on orthogonal frequency-division multiplexing (OFDM). In order to solve the problem of high PAPR in OFDM systems, the baseband processing apparatus and method generate a plurality of data with different peak to average power ratios (PAPRs) by modifying bit representations of the frozen bits used by a polar code encoder, and then select the one of the plurality of data with the smallest PAPR as an OFDM signal.

Abstract: An apparatus for generating a 2D spreading code and method for the same are proposed. The apparatus for generating the 2D spreading code includes a column counter, a row counter, a codeword selector, and a logic unit. The logic unit performs logic operations on the output of the column counter, the row counter, and the codeword selector to generate the 2D spreading code of desired order designated by the codeword selector. The 2D spreading code includes 4 2×2 initial matrixes for generating 4i codes for 4i users in the ith order. The apparatus for generating the 2D spreading code according to the present invention is advantageously used in OFDM system to increase the number of subscribers with reduced interference.

Abstract: At the transmitter of a transmitter and receiver apparatus for Multiple Input/Multiple Output MultiCarrier-Code Division Multiple Access (MIMO MC-CDMA) systems, modified orthogonal transmit diversity (MOTD) encoders are used for increasing space and time transmission diversity. A P-way combiner is used to connect the MOTD encoders and P multi-carrier modulators. Each modulator is connected to a set of antennas. At the receiver, each multi-carrier demodulator has an amplitude/phase compensator to compensate distortion at every sub-carrier. Similarly, a combiner is used to connect the demodulators and the MOTD decoders. As a result, space, time, and frequency diversity can be explored.

Abstract: The invention relates to an apparatus of transmitter and receiver for MIMO MC-CDMA systems. At the transmitter, modified orthogonal transmit diversity (MOTD) encoders are used for increasing space and time transmission diversity. A P-way combiner is used to connect the MOTD encoders and P multi-carrier modulators. Each modulator is connected to a set of antennas. At the receiver, each multi-carrier demodulator has an amplitude/phase compensator to compensate distortion at every sub-carrier. Similarly, a combiner is used to connect the demodulators and the MOTD decoders. Upon the invention, the space, time, and frequency diversity can be explored.

Abstract: The invention relates to an apparatus of transmitter and receiver for Multiple Input/Multiple Output MultiCarrier-Code Division Multiple Access (MIMO MC-CDMA) systems. At the transmitter, modified orthogonal transmit diversity (MOTD) encoders are used for increasing space and time transmission diversity. A P-way combiner is used to connect the MOTD encoders and P multi-carrier modulators. Each modulator is connected to a set of antennas. At the receiver, each multi-carrier demodulator has an amplitude/phase compensator to compensate distortion at every sub-carrier. Similarly, a combiner is used to connect the demodulators and the MOTD decoders. Upon the invention, the space, time, and frequency diversity can be explored.

Abstract: An equalization method suitable for use in a receiver in an orthogonal frequency division multiplexing (OFDM) system utilizing a plurality of sub-carriers. The receiver includes an outer receiver for decoding. The equalization method includes receiving an input signal including at least one preamble symbol containing a training sequence and a plurality of informative OFDM symbols each containing a serial stream of samples, and performing compensations for each of the informative OFDM symbols. Compensation for each of the informative OFDM symbols includes converting the serial stream of samples into parallel samples, performing a fast Fourier transform (FFT) of the parallel samples to obtain a plurality of data symbols, each data symbol corresponding to a sub-carrier, compensating the data symbols for at least one first phase distortion and at least one second phase distortion, and providing at least one amplitude distortion factor to the outer receiver.

Abstract: A PAPR reduction method using bit reallocation is disclosed, which is applied in a multi-carrier system. The lowest total transmission power P is achieved by a bit loading algorithm conditioned on the requirement of total D transmission bits per block. When the PAPR (peak to average power ratio) of the block is larger than a predetermined value A, the bit reallocation is performed to add ?d-bit transmitting data to one sub-carrier and subtract ?d-bit transmitting data from another sub-carrier, thereby continuing bit reallocation until the PAPR meets with the system requirement or an iteration number reaches a predetermined maximal number of iteration L.

Abstract: An apparatus for generating a 2D spreading code and method for the same are proposed. The apparatus for generating the 2D spreading code includes a column counter, a row counter, a codeword selector, and a logic unit. The logic unit performs logic operations on the output of the column counter, the row counter, and the codeword selector to generate the 2D spreading code of desired order designated by the codeword selector. The 2D spreading code includes 4 2×2 initial matrixes for generating 4i codes for 4i users in the ith order. The apparatus for generating the 2D spreading code according to the present invention is advantageously used in OFDM system to increase the number of subscribers with reduced interference.

Abstract: An equalization method suitable for use in a receiver in an orthogonal frequency division multiplexing (OFDM) system utilizing a plurality of sub-carriers. The receiver includes an outer receiver for decoding. The equalization method includes receiving an input signal including at least one preamble symbol containing a training sequence and a plurality of informative OFDM symbols each containing a serial stream of samples, and performing compensations for each of the informative OFDM symbols. Compensation for each of the informative OFDM symbols includes converting the serial stream of samples into parallel samples, performing a fast Fourier transform (FFT) of the parallel samples to obtain a plurality of data symbols, each data symbol corresponding to a sub-carrier, compensating the data symbols for at least one first phase distortion and at least one second phase distortion, and providing at least one amplitude distortion factor to the outer receiver.

Abstract: The invention relates to an apparatus of transmitter and receiver for MIMO MC-CDMA systems. At the transmitter, modified orthogonal transmit diversity (MOTD) encoders are used for increasing space and time transmission diversity. A P-way combiner is used to connect the MOTD encoders and P multi-carrier modulators. Each modulator is connected to a set of antennas. At the receiver, each multi-carrier demodulator has an amplitude/phase compensator to compensate distortion at every sub-carrier. Similarly, a combiner is used to connect the demodulators and the MOTD decoders. Upon the invention, the space, time, and frequency diversity can be explored.

Abstract: A PAPR reduction method using bit reallocation is disclosed, which is applied in a multi-carrier system. The lowest total transmission power P is achieved by a bit loading algorithm conditioned on the requirement of total D transmission bits per block. When the PAPR (peak to average power ratio) of the block is larger than a predetermined value A, the bit reallocation is performed to add ?d-bit transmitting data to one sub-carrier and subtract ?d-bit transmitting data from another sub-carrier, thereby continuing bit reallocation until the PAPR meets with the system requirement or an iteration number reaches a predetermined maximal number of iteration L.

Abstract: A method of automatically refreshing the display screen of a terminal and the computer program thereof is accomplished by incorporating a subroutine for periodically polling the connection status of a terminal into a main program running on host. A polling period is set in the main program, and a software interrupt is generated to invoke the execution of a corresponding interrupt service routine when the polling period is reached. The interrupt service routine contains a polling subroutine for polling the connection status of the terminal by sending a control string to the terminal and recording the polling result. The present polling result will be compared with the previous polling result to check whether the connection status of the terminal is changed. If the connection status of the terminal is changed from off-line to on-line, a display screen refresh subroutine is executed to refresh the display screen of the terminal.