Abstract: A tag transmitting apparatus of a passive RFID system generates a plurality of orthogonal square waves, converts tag data to a plurality of parallel data, and transmits the plurality of parallel data to a reader using a plurality of square waves as a subcarrier.

Abstract: Disclosed are an apparatus and method for constant amplitude encoding of a transmission signal in a CDM (Code Division Multiplexing) communication system. The apparatus for constant amplitude encoding of a transmission signal includes: an encoding module sequentially performing horizontal encoding and vertical encoding on an input signal; and a spreading and multiplexing module spreading the signal which has been encoded by the encoding module and multiplexing the spread signal in a vertical direction to output a data stream having a constant amplitude.

Abstract: A radio frequency identification (RFID) smart shelf system manages a product through communication with an RFID tag that is attached to the product on a shelf, and includes an RFID reader, a plurality of reader antennas, and an RF switch that is connected between the RFID reader and the plurality of reader antennas. The RF switch periodically varies a phase difference between RF signals of a portion of a plurality of output connection ports that set a connection to each of the plurality of reader antennas.

Abstract: Disclosed are a sensor node having a self localization function and a self localization method of the sensor node. The sensor node calculates a location thereof by receiving location information measured at each of two mobile nodes at different times and using four location information of the received location information. Additional cost and power consumption required for installing additional equipment such as an anchor node, a ultrasonic transceiver and a signal amplifier are reduced.

Abstract: A decentralized scheduling method in a wireless ad hoc network is provided which includes grouping nodes in the network cluster by cluster, determining a cluster head of each cluster, and sequentially performing scheduling cluster by cluster. Accordingly, it is possible to provide an efficient cluster-based scheduling method which quickly adapts to changes and reduces power consumption.

Abstract: Provided are an ad-hoc wireless communication method using a sector antenna, a recovery method in ad-hoc wireless communication, and an ad-hoc wireless communication system. The ad-hoc wireless communication method using a sector antenna according to an exemplary embodiment of the present invention, includes: transmitting a requesting message for setting a communication link while changing transmission power to each sector of the sector antenna; receiving a response message corresponding to the requesting message from a receiving node of each sector; configuring a routing table for the transmission power for each sector based on the received response message; and transmitting data at the transmission power for each sector by referring to the routing table.

Abstract: An RFID system using an M pulse amplitude modulation (M-PAM) or M quadrature amplitude modulation (M-QAM) scheme using a plurality of load-modulators, a plurality of antennas, and a communication method thereof are provided. The RFID system includes: an RFID tag; and a reader device communicating with the RFID device, wherein the RFID tag includes: N load-modulators an N antennas communicating with the reader device in any one scheme of M-pulse amplitude modulation (M-PAM) and M-quadrature amplitude modulation (M-QAM) in which modulation of an M level is performed and operated corresponding to the M level.

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: A method of storing sensor data in a sensor tag is provided. The method comprises receiving new sensor data output from a sensor, comparing the received new sensor data with immediately previous sensor data to determine whether the comparison result satisfies a predetermined criterion, and storing the new sensor data in a tag memory when it is determined that the criterion is satisfied. Accordingly, efficient use of the tag memory is possible.

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: Provided are a reader-tag integrated RFID apparatus and a method for controlling the same. The apparatus includes a tag unit for communicating with an external reader, and transmitting a response signal and data corresponding to a signal transmitted from the external reader to the external reader, a reader unit for selecting a channel between other reader and the reader-tag integrated RFID apparatus with a different delay time, and communicating with an external tag using a random value to minimize collision; and a controller for selectively activating one of the tag unit and the reader unit if it necessary.

Abstract: Provided is a method and apparatus for recognizing a radio frequency identification tag reader. In order to obtain protocol addresses of a plurality of radio frequency identification (hereinafter referred to as RFID) tag readers, a request message including a timestamp indicating a generation time is generated and transmitted, and a response message for the request message from one of the plurality of RFID readers is received. When the timestamp included in the response message satisfies a set condition, a hardware address and a protocol address of the RFID reader are extracted from the response message.

Abstract: A large data transmission method in a sensor network based on a media access control (MAC) is provided. The method includes dividing data to be transferred into a plurality of data segments; generating a plurality of media access control (MAC) segmented data frames by including in each data segment an indication that the data is generated by segmentation and assigning a sequence number to the data segment; transmitting the generated MAC segmented data frames sequentially; receiving a MAC reception failure frame indicating reception failure for a predetermined period of time from a receiving sensor node after completing the transmitting of all the MAC segmented data frames; and retransmitting the MAC segmented data frames which correspond to at least one sequence number included in the received MAC reception failure frame. Accordingly, large data transmission times can be reduced in a MAC for a sensor network.

Abstract: A distributed channel hopping communication method in a low power wireless ad-hoc network. A beacon transmission and reception scheduling method using a distributed channel hopping method in a wireless ad-hoc network, the method includes: transmitting beacons using channel hopping, before establishing the wireless ad-hoc network including a plurality of nodes having a BP including at least one time slot, and receiving beacons of a plurality of neighboring nodes of each of the plurality of nodes; collecting information about the wireless ad-hoc network and information about the plurality of neighboring nodes from the received beacons; scheduling the receiving of the beacons that are transmitted from the plurality of neighboring nodes in the BP, using TDMA in each of the at least one time slot based on the information about the plurality of neighboring nodes; and scheduling transmitting of a beacon in each of the at least one time slot.

Abstract: A passive phase jitter modulation (PJM) tag is charged with power in a continuous wave (CW) section. When receiving a command from a reader, the passive PJM tag must recognize the command and determine exactly when to begin demodulating the command. Only then can the passive PJM tag demodulate the command. To this end, a synchronization apparatus for accurately demodulating a signal input to a PJM tag includes a plurality of correlators correlating a received phase jitter-modulated signal with a template of an internal matched filter which is in the same form as at least a portion of a modified frequency modulation (MFM) flag.

Abstract: Provided are an apparatus and method for controlling a radiation direction. The apparatus includes parasitic elements disposed in proximity to the antenna, wherein each of the parasitic elements comprises an antenna; a first portion that is inclined with respect to a prepared ground surface at a first angle and a second portion that is inclined with respect to the first portion at a second angle; a lumped element having a variable reactance, which is disposed on each of the first and second portions; and a determination unit controlling the reactance of the lumped element so as to determine the radiation direction of the antenna. By using the apparatus and the method, the antenna has various radiation directions.

Abstract: Provided is a method and apparatus for managing a product distribution. The product distribution management method may include: reading a security key of a product from a security tag attached to the product; transferring the read security key to a security server; receiving, from the security server, first authentication information that is encrypted using the security key; receiving, from the security tag, second authentication information that is encrypted using the security key; and determining whether the security tag is duplicated, based on the first authentication information and the second authentication information.

Abstract: Provided is a resource allocation method performed in a wireless network formed of a plurality of nodes, the resource allocation method including the operations of forming clusters and electing cluster heads respectively for the clusters; determining whether a node from among the plurality of nodes forming the wireless network is an edge node; if the node is not the edge node according to a result of the determining, collecting link information related to other nodes in a cluster that comprises the node, and delivering the link information to a cluster head of the cluster; and if the node is the edge node according to a result of the determining, otherwise, obtaining link information and scheduling information from an edge node of another cluster within a communication range with the cluster comprising the edge node, and delivering the link information and scheduling information to the cluster head.

Abstract: Disclosed is a synchronization method between a reader and tag according to an example embodiment, the method including: transmitting, by the reader, a first write command message to the tag at a first time; detecting, by the tag, the first write command message from the reader at a second time and transmitting a first response message to the reader in response to the first write message; transmitting, by the reader, a second write command message including first time information of the first time to the tag; and correcting, by the tag, a clock offset using a difference between the first time and the second time.

Abstract: An apparatus and a method for demodulating a subcarrier tag signal in a radio frequency identification (RFID) reader is provided. The apparatus for demodulating the subcarrier tag signal in the RFID reader may include: an edge signal generation unit receiving a subcarrier tag signal and generating an edge signal with respect to the tag signal; an edge information extraction unit extracting edge information from the generated edge signal; and a decoding unit decoding the tag signal using the extracted edge information.