Abstract: A differential orthogonal modulation method and a differential orthogonal modulation apparatus using a repetition time interval difference of a chirp signal are disclosed. Such a differential orthogonal modulation method performed in a transmitter unit of a digital communication system comprises the steps of converting data having a serial bit format to be transmitted in the transmitter unit into a parallel format to create parallel input data, inputting the parallel input data into a symbol mapper, orthogonally modulating the parallel input data inputted into the symbol mapper to create modulated data comprised of differential bi-orthogonal functions, differentially encoding the modulated data to output encoded data, converting the encoded data into a serial bit format to create a baseband signal, and processing the baseband signal to create a transmission signal in a form of a chirp signal having a specific repetition time interval difference.

Abstract: Disclosed is a method and an apparatus for channel estimation regarding electromagnetic wave multi-path characteristics between a sender and a receiver by using a chirp signal.

Abstract: Disclosed is a method and an apparatus for channel estimation regarding electromagnetic wave multi-path characteristics between a sender and a receiver by using a chirp signal.

Abstract: A differential orthogonal modulation method and a differential orthogonal modulation apparatus using a repetition time interval difference of a chirp signal are disclosed. Such a differential orthogonal modulation method performed in a transmitter unit of a digital communication system comprises the steps of converting data having a serial bit format to be transmitted in the transmitter unit into a parallel format to create parallel input data, inputting the parallel input data into a symbol mapper, orthogonally modulating the parallel input data inputted into the symbol mapper to create modulated data comprised of differential bi-orthogonal functions, differentially encoding the modulated data to output encoded data, converting the encoded data into a serial bit format to create a baseband signal, and processing the baseband signal to create a transmission signal in a form of a chirp signal having a specific repetition time interval difference.

Abstract: A method and device for communicating data within a packet frame unit between a terminal and a base station are disclosed. The terminal communicates the packet data to the base station. In response, the base station transmits a channel occupying signal, if the data transmission from the terminal is perceived by the base station. The terminal continues the communication of the packet data, while the channel occupying signal is active, determines whether the base station receives the communicated packet data, and ends the process for communicating the packet data if the base station receives the communicated packet data. If the base station fails to receive the communicated packet data, the terminal is informed through the channel occupying signal. Thereafter, the terminal discontinues its communication and then re-attempts to communicate the packet data from the beginning.

Abstract: A WLL (wireless local loop) system using a CDMA (code division multiple access) method includes a data transmitter, a data receiver, a data transmission/reception buffer, and a controller. The system implements a voice and data communication which includes the steps of performing a voice communication through a plurality of voice communication channels assigned to respective subscribers by a circuit switching method during a transmission/reception of the voice signal, and performing a data communication by a packet switching method in a way in which a plurality of subscribers share in common predetermined data communication channels during the transmission/reception of the data signal.

Abstract: A data transmission apparatus for a CDMA communication system and a method are disclosed. The apparatus includes a digital combiner for combining a plurality of digital signals spread by a plurality of CDMA spreader, a digital filter for filtering a signal inputted from the digital combiner, a D/A converter for converting the filtered digital signal into an analog signal, and an analog filter for filtering the converted analog signal, for thereby performing a combining in a digital region before a plurality of CDMA signals are converted into an analog form.

Abstract: A transmission apparatus for a CDMA communication system. The apparatus includes a multiplexer for multiplexing CDMA signals inputted through a plurality of channels, a voltage limiter for limiting a voltage of the multiplexed signal to a predetermined voltage level, an up-converter for up-converting the signal inputted from the voltage limiter into a high frequency signal, and a high power amplifier for amplifying the up-converted signal to a predetermined power level, for thereby decreasing an input voltage inputted into a high output amplifier, being used for a plurality of subscriber channels and using a low price high output amplifier.

Abstract: A method and device for communicating data within a packet frame unit between a terminal and a base station are disclosed. The terminal communicates the packet data to the base station. In response, the base station transmits a channel occupying signal, if the data transmission from the terminal is perceived by the base station. The terminal continues the communication of the packet data, while the channel occupying signal is active, determines whether the base station receives the communicated packet data, and ends the process for communicating the packet data if the base station receives the communicated packet data. If the base station fails to receive the communicated packet data, the terminal is informed through the channel occupying signal. Thereafter, the terminal discontinues its communication and then re-attempts to communicate the packet data from the beginning.

Abstract: A transmission power control method in a mobile communication system using a code division multiple access (CDMA) method includes: a power control process in an access mode having: a step of measuring a transmission power of an initial access channel transmitted from a terminal; a step of comparing the measured transmission power level with a pre-setted adequate power level; a step of transmitting a transmission power adjusting message to the terminal according to the comparison result; and a step of the terminal adjusting the transmitting power of the traffic channel to the adequate power level according to the transmission power adjusting message transmitted from a base station; and a power control process in a traffic mode having: a step of measuring the transmission power level of the traffic channel transmitted from the terminal; a step of comparing the measured transmission power level with the pre-setted adequate power level; a step of transmitting an one-bit power control bit to the terminal according