Abstract: An active radio frequency identification (RFID) apparatus having an additional transmitter in addition to a single transmitter is provided. The active RFID apparatus includes a first transmitter including a first pseudo noise (PN) code generator to generate a direct sequence spread spectrum (DSSS) introduced by ISO/IEC (International Organization for Standardization/International Electrotechnical Commission) 24730-2 or ISO/IEC 18185-5 type B; and a second transmitter including a second PN code generator to perform an AND operation on an initial value and a fed back value and shift the resultant value of the AND operation, to perform an XOR operation on particular bits from among the shifted bits and to perform an XOR operation again on the shifted bits and the resulting value of the XOR operation to finally generate a PN code.

Abstract: To track the location of a terminal in an indoor space by using a pseudo GPS signal transmitter, a GPS signal sent from an artificial satellite is received, and a clock signal of the artificial satellite is extracted from the received GPS signal to perform synchronization with the artificial satellite. Once synchronization with the artificial satellite is performed, a pseudo GPS signal is generated, and the transmission time of the pseudo GPS signal is controlled. The GPS signal is sent to the terminal located in the indoor space by a plurality of transmitting antennas based on the controlled transmission time, thereby enabling the terminal located in the indoor space to track its location.

Abstract: Real-time location tracking apparatus and method using a global positioning system (GPS) signal relay tag is provided. Here, a tag may receive a GPS signal and transmit the received GPS signal to a reader, and the reader may calculate a location of the tag, and thereby a real-time location tracking service may be provided.

Abstract: Disclosed is a method for improving accuracy of time measurement and a position tracking apparatus using the same. A method for improving accuracy of time measurement includes receiving a radio communication signal and obtaining timing information in a received signal; tracking a code that detects inconsistent timing between the received signal and a tracking signal generated for the received signal; storing history information on the inconsistent timing between the received signal and the tracking signal for each bit of the received signal; and arithmetically averaging the history information and updating the timing information of the received signal with the arithmetically averaged value.

Abstract: An apparatus and method of generating a pseudo noise (PN) code is provided. The apparatus for generating the PN code includes: a memory device unit including a plurality of memory devices; an exclusive-OR (XOR) operation unit receiving output values of at least two memory devices among output values of the plurality of memory devices to output an XOR operation value with respect to the received output values; and a PN code generation unit generating the PN code based on an output value of the XOR operation unit.

Abstract: Provided is an apparatus and method for transmitting packet data in a WSN. The apparatus for transmitting packet data in a WSN includes: a serial-to-parallel converter to parallel-convert information and output the converted information to two channel paths; a Walsh code pair generation unit to select an arbitrary Walsh code pair, mix the selected Walsh code pair with a pseudo noise (PN) code, and output one Walsh code to one channel path and the other Walsh code to the other channel path; a first mixer to mix the signals inputted to two channel paths, and generate a spread symbol for each path; a delay to delay the other channel path signal by a predetermined time; and a transmission unit to convert one channel path signal and the other channel path signal delayed by the delay into transmission frequency band signals, and transmit the converted signals as wireless signals.

Abstract: Proposed are a method and apparatus for real-time location tracking using Radio Frequency Identification (RFID), the apparatus including: a first reception information receiver to receive first reception information of a tag signal from a plurality of RFID readers that receives the tag signal from an RFID tag; a reader group generator to select, from the plurality of RFID readers, at least three RFID readers based on the first reception information and generate an RFID reader group including the selected at least three RFID readers; and a location calculator to calculate a location of the RFID tag based on first reception information that is received from the at least three RFID readers included in the RFID reader group.

Abstract: A multistage channel estimation method and apparatus is provided. The multistage channel estimation method includes: receiving a data frame to compensate for a distortion of the data frame based on a first channel estimation value associated with a corresponding section of the data frame; a first step of changing the corresponding section to calculate a second channel estimation value associated with the changed section; a second step of updating the first channel estimation value based on the calculated second channel estimation value; a third step of compensating for the distortion of the data frame based on the updated first channel estimation value to count a number of compensations; and repeating the first step through the third step, when the counted number of compensations does not match a predetermined numerical value.

Abstract: A freight container cargo-working management system and method which can use Radio Frequency Identification (RFID) technology for displaying a cargo-working location of a container by recognizing an RFID tag adhered to a container vehicle passing through a warehouse entrance is provided. A freight container cargo-working management system including: an RFID tag to include freight information and be adhered to a container; an RFID reader to be installed at a warehouse entrance for recognizing the freight information included in the RFID tag; a cargo-working location information transmitter to be installed at the warehouse entrance for wirelessly transmitting cargo-working location information of the container corresponding to the freight information recognized by the RFID reader; and a cargo-working location display to be included in a vehicle with the container attached for displaying the cargo-working location information wirelessly transmitted from the cargo-working location information transmitter.

Abstract: Provided are a Radio Frequency Identification (RFID) tag and apparatus and method for locating a RFID tag without comparing arrival times of blink signals transmitted from the RFID tag in order to quickly trace a location of the RFID tag. The RFID tag includes a tag ID generator configured to generate a tag ID of the RFID tag, a blink generator configured to generate a plurality of sub-blink signals that form the blink signal, a sub-blink ID generator configured to generate sub-blink IDs for the generated sub-blink signals, a sub-blink ID inserter configured to insert the generated sub-blink IDs into the sub-blink signals, and a transmitter configured to transmit the blink signal having the tag ID and the sub-blink IDs.

Abstract: Provided are an apparatus and a method for generating a return-to-zero (RZ) signal, including: a first modulator receiving a first signal having a predetermined frequency to modulate, compensate for and output a first laser beam; a second modulator receiving a second signal complementary to the first signal to modulate, compensate for, and output a second laser beam; a mixer mixing signals output from the first and second modulators to output a third signal; and a third modulator modulating the third signal into an RZ signal and outputting the RZ signal.

Abstract: Disclosed is a wireless signal receiving apparatus, and more particularly, disclosed is a parallel automatic frequency offset estimation apparatus and method for tracking a frequency offset in an early stage by calculating, in parallel, frequency offsets of a received signal. The parallel automatic frequency offset estimation apparatus includes a receiving unit to receive a data frame; and a frequency offset estimation unit to calculate, in parallel, frequency and phase deviations at different bit intervals within a particular section of the received data frame, to add together the frequency and phase deviations to obtain a first sum of the frequency and phase deviations, and to add the first sum to a frequency phase deviation calculated for each bit after the particular section in the received data frame to obtain a second sum of the frequency and phase deviations.

Abstract: An active radio frequency identification (RFID) apparatus having an additional transmitter in addition to a single transmitter is provided. The active RFID apparatus includes a first transmitter including a first pseudo noise (PN) code generator to generate a direct sequence spread spectrum (DSSS) introduced by ISO/IEC (International Organization for Standardization/International Electrotechnical Commission) 24730-2 or ISO/IEC 18185-5 type B; and a second transmitter including a second PN code generator to perform an AND operation on an initial value and a fed back value and shift the resultant value of the AND operation, to perform an XOR operation on particular bits from among the shifted bits and to perform an XOR operation again on the shifted bits and the resulting value of the XOR operation to finally generate a PN code.

Abstract: A positioning system is provided which is capable of calculating the position of a target object even though it does not detect some synchronous signal necessary for position calculation. A communication signal receiver which provides information used in the position calculation is also provided.

Abstract: Provided are an optical transponder that processes a G.709 frame that includes an overhead for operation, administration, and maintenance of an optical channel and an overhead for forward error correction, and a method of detecting and treating errors in optical-channel sublayers of the same. The method includes detecting an error signal or a maintenance signal from a G.709 frame that includes an overhead for operation, administration, and maintenance of an optical channel and an overhead for forward error correction; treating errors in a predetermined layer of a plurality of layers that requires error treatment when the error signal or the maintenance signal is detected or canceled; and investigating a reason for the errors in the predetermined layer.

Abstract: The method for operating an optical transponder, which performs maintenance of a signal in the optical transponder having a digital wrapper in an optical transmission system including multiple layers, includes (a) calling a processor for processing an interrupt when the interrupt is generated from the digital wrapper according to monitoring of a received signal; (b) the called processor detecting what defect is generated in the received signal and detecting whether or not the received signal requires maintenance; (c) performing defect processing in the case that a defect is detected at (b) or is cancelled; and (d) controlling the digital wrapper according to the defect and maintenance processing result.

Abstract: Disclosed herein is an apparatus for controlling a decision threshold voltage to an optical receiver, which is capable of automatically controlling the decision threshold voltage to the optical receiver appropriately to signal level decision on the basis of a low-frequency band signal component of an output signal from the optical receiver. The apparatus is adapted to control the level of the decision threshold voltage to the optical receiver, which converts an input optical signal into an electrical signal.

Abstract: An optical receiver in an optical communication system, and more particularly, to a method and an apparatus for optimizing a decision level of a signal output from an optical receiver to obtain a minimum bit error rate (BER) by measuring output characteristics of the optical receiver and adjusting a reference voltage of the optical receiver based on a measurement result. The provided method includes measuring the strength of an electric signal at a modulated frequency out of the frequency elements of the output electric signal in the optical receiver, generating a reference voltage based on the strength data of the electric signal, inputting the reference voltage to the optical receiver and re-measuring the strength of the electric signal output from the optical receiver to determine whether the strength of the signal is minimum, and maintaining the reference voltage when the strength of the signal is minimum and adjusting the reference voltage in other cases.

Abstract: Optical signals transmitted through an optical cable are converted into digital data of bits “1” and “0” on the basis of a reference voltage, and errors generated during transmission of the optical signals are corrected using Forward Error Correction (FEC). A method includes extracting numbers of occurrence of errors for bits “1” and “0” recovered through the FEC. Thereafter, the extracted numbers of occurrence of errors for bits “1” and “0” are compared with each other. A reference voltage used to judge levels of the signals to be level “1” or “0” is controlled if the numbers of occurrence of errors for bits “1” and “0” are not equal to each other. The current reference voltage is maintained if the numbers of occurrence of errors for bits “1” and “0” are rendered equal to each other.

Abstract: The present invention relates to a method for revising a wavelength of the EML by controlling a working temperature based on arithmetic functional relations between the DC-Offset voltage and the wavelength and between the working temperature and the wavelength, and a computer-readable recording medium thereof. The method includes the steps of: re-setting initial values of a working temperature, a amplifying voltage and the DC-Offset voltage; determining a wavelength with respect to the re-set DC-Offset voltage based on a functional relation between the DC-Offset voltage and the wavelength of the EML; and determining the revising working temperature for the determined wavelength based on the functional relation between the working temperature and the wavelength of the EML, and re-setting the working temperature with the revising working temperature.