Abstract: A method and apparatus of an effective and reliable retransmission based on soft combining when using orthogonal frequency division multiplexing (OFDM) modulation technique in a contention based access system. The method includes receiving a data signal from a transmission node, performing soft combining the valid section part of the data signal which have been previously received and the data signal currently received, determining a collision section of the data signal which is currently received, and saving a valid section part except the collision section of the data signal which is currently received in a buffer. In the contention based access system that uses OFDM modulation technique, in case that data signal reception failure occurs due to a transmission collision, the valid part of the received data signal may be detected and effectively applied to the soft combining, and consequently, the reception probability of data signal can be increased.

Abstract: Disclosed is a data replication method in a Database Management System (DBMS). The data replication method includes generating a replication log through a transaction log of a master database to thereby transmit the generated replication log to a distributor, determining a slave host distributing the replication log to thereby distribute the replication log to the corresponding slave host, and reflecting the replication log in a slave database.

Abstract: A recursive demodulation apparatus is provided. Therecursive demodulation apparatus, including: a segment generation unit dividing data symbols with a residual frequency or phase error into a predetermined number of data symbols, and generating a plurality of segments, each of the plurality of segments including the predetermined number of data symbols; and a phase error correction unit sequentially correcting a phase error of each of the data symbols, included in the each of the plurality of segments, for each segment.

Abstract: A method and apparatus for a modulo N operation are provided. The method for a modulo N operation on a positive integer X includes converting the positive integer X into a binary number, determining whether a modulo N is expressed by a product of 2 to the mth power and a value obtained by adding or subtracting one to or from 2 to the nth power, calculating the positive integers m and n, if the modulo N is expressed by the product of 2 to the mth power and the value obtained by adding or subtracting one to or from 2 to the nth power, and grouping the binary number of the positive integer X into bit units varying according to the positive integers m and n to perform operation on the binary number of the positive integer X. Accordingly, it is possible to reduce complexity of a modulo operation using a simple adder and logic circuit.

Abstract: A method for slicing a symbol in a QAM digital demodulator, includes acquiring a digital integer value by sampling a symbol signal in an in-phase coordinate or a quadrature-phase coordinate; and extracting a symbol bit sequence in the in-phase coordinate or the quadrature-phase coordinate from a whole bit sequence of the digital integer value by using an LSB thereof. Further, a symbol slicer for detecting a QAM symbol, includes digital sampling units, each of which acquires a digital integer value by sampling a symbol signal in an in-phase coordinate or a quadrature-phase coordinate; and a symbol bit sequence extracting unit that extracts a symbol bit sequence in the in-phase coordinate or the quadrature-phase coordinate from a whole bit sequence of the digital integer value by using an LSB thereof.

Abstract: A recursive demodulation apparatus is provided. Therecursive demodulation apparatus, including: a segment generation unit dividing data symbols with a residual frequency or phase error into a predetermined number of data symbols, and generating a plurality of segments, each of the plurality of segments including the predetermined number of data symbols; and a phase error correction unit sequentially correcting a phase error of each of the data symbols, included in the each of the plurality of segments, for each segment.

Abstract: Disclosed is a data replication method in a Database Management System (DBMS). The data replication method includes generating a replication log through a transaction log of a master database to thereby transmit the generated replication log to a distributor, determining a slave host distributing the replication log to thereby distribute the replication log to the corresponding slave host, and reflecting the replication log in a slave database.

Abstract: A method for slicing a symbol in a QAM digital demodulator, includes acquiring a digital integer value by sampling a symbol signal in an in-phase coordinate or a quadrature-phase coordinate; and extracting a symbol bit sequence in the in-phase coordinate or the quadrature-phase coordinate from a whole bit sequence of the digital integer value by using an LSB thereof. Further, a symbol slicer for detecting a QAM symbol, includes digital sampling units, each of which acquires a digital integer value by sampling a symbol signal in an in-phase coordinate or a quadrature-phase coordinate; and a symbol bit sequence extracting unit that extracts a symbol bit sequence in the in-phase coordinate or the quadrature-phase coordinate from a whole bit sequence of the digital integer value by using an LSB thereof.

Abstract: Provided is a QAM (Quadrature Amplitude Modulation) symbol mapping method and apparatus for downstream transmission of a cable modem. The method includes the steps of: determining phase information on the basis of predetermined relations between two bits representing set partitioning information and two LSBs (Least Significant Bits) of bits representing amplitude information, among bits input for QAM symbol mapping; separating I and Q signals of a first quadrant from the bits representing the amplitude information; and mapping the I and Q signals of the first quadrant to actual positions on the basis of the determined phase information.

Abstract: A residual frequency offset compensation apparatus is provided. The residual frequency offset compensation apparatus includes: a basic phase offset compensation unit compensating input symbols using a previously stored basic phase offset and generating first symbols; a phase shift calculation unit calculating a phase shift value of each of a predetermined number of the first symbols using first detection symbols and the first symbols, the first detection symbols being generated by detecting the first symbols; a phase shift compensation unit compensating the first symbols based on an average of the phase shift values; and a basic phase offset update unit updating the basic phase offset based on the phase shift values.

Abstract: A method for providing a connection between a client and heterogeneous database management systems, includes the steps of: a) generating a thread in response to a request message transmitted from the client; b) determining what is the request message and operating a database driver to process the request message by referring to a client information management table; and c) registering identification information of a client and a database in the client information management table and transmitting an execution result corresponding to the request message from the database driver to the client.