Abstract: The present disclosure relates to an organic electroluminescent compound and an organic electroluminescent device comprising the same. By comprising the compound according to the present disclosure, it is possible to produce an organic electroluminescent device having improved driving voltage, power efficiency, and/or lifetime properties compared to the conventional organic electroluminescent devices.

Abstract: A method and system for WiBro network interworking in a wireless terminal. The method includes: setting up, by a relay station for connecting the WLAN terminal with the WiBro network, a connection through an initial process with the WiBro network; performing, by an access router, Internet connection authentication on a user of the WLAN terminal in response to a request for Internet connection from the WLAN terminal; allocating, by the access router, an IP address in response to a request for IP address allocation from the WLAN terminal, and then allocating, by a WiBro radio access station, a unique Connection IDentification (CID) corresponding to a QoS level of the terminal user in response to a request from the relay station; and mapping, by the relay station, the allocated unique CID to the IP address of the WLAN terminal and providing Internet service.

Abstract: A communication method and apparatus using a virtual sink node in a wireless sensor network, in which location information about a destination node is acquired by a source node. If the location of the destination node is out of a transmission range of the source node, data including the location information about the destination node are transmitted from the source node to one of nodes adjacent to the source node, where the one node is typically closest to the destination node. The data are transmitted from the one node to another one of nodes adjacent to the one node, where another node is closest to the destination node, until the destination node is located within a transmission range of the one node. If the destination node is located within the transmission range of the one node, the data are transmitted from the one node to the destination node.

Abstract: A mobility management system and method is provided for efficiently support mobility to an IPv6 based LoWpan. The mobility management method for Internet Protocol version 6 (IPv6) based personal area network (PAN) moving with a mobile router according to the present invention includes detecting, at a mobile terminal, movement of the mobile router; determining whether the movement is an intra-network movement or an inter-network movement, transmitting, when the movement is an intra-network movement, a neighbor discovery request message to a gateway of a currently attached network and receiving a neighbor discovery response message containing a temporary address transmitted by the gateway in response to the neighbor discovery request message. When the movement is an inter-network movement, the gateway receives the binding acknowledgement message from a home agent and establishes a bidirectional tunnel with the home agent.

Abstract: A method of allocating logical channels in consideration of an interference range in a wireless sensor network includes defining logical channels to increase the number of available channels and determining the number of logical channels in accordance with the number of nodes within an interference range, allocating the logical channels to the nodes within the interference range so that the determined logical channels do not overlap each other, and exchanging data among the nodes using the allocated logical channels.

Abstract: A method is provided for synchronizing time between nodes in a wireless communication system. A reference node transmits a first packet to a correspondent node. Upon receiving the first packet, the correspondent node transmits a second packet with a reception time of the first packet recorded therein, to the reference node. Upon receiving the second packet, the reference node calculates a forward delay time using a transmission time and the reception time of the first packet. The correspondent node receives a third packet with the forward delay time from the reference node, and calculates a reverse delay time. The correspondent node calculates an offset value for the synchronization using the forward delay time and the reverse delay time.

Abstract: A method for controlling a camera through a Multi-Hop-based wireless sensor network includes: sensing whether an event occurs or not in a corresponding area and transmitting position information on the corresponding area and type information on the event, converting the received position information on the event into a movement control signal for the camera, calculating camera driving values in a left/right direction and an up/down direction using the converted signal, controlling a zoom-in operation of the camera lens using the calculated camera driving values according to the received event type and photographing an object located in the corresponding direction, and transmitting the photographed images over the outer network.

Abstract: Disclosed is a method of managing an allocated address through a coordinator in a Low Power Wireless Personal Area Network (LoWPAN) including receiving a first beacon data request message from a mobile node that has entered into a communication region of the coordinator; measuring a Link Quality Indication (LQI) of the first beacon data request message, setting the measured LQI as a minimum communication threshold value with the mobile node, and setting an alarm region that is an LQI range for sensing whether the mobile node leaves the communication region; if a second beacon data request message is received from the mobile node, measuring an LQI of the second beacon data request message, and checking whether the measured LQI of the second beacon data request message is included in the alarm region; and if the LQI is included in the alarm region, periodically transmitting a node alive check message to the mobile node.

Abstract: A multi-hop wireless network system and an authentication method thereof, wherein during initial mutual authentication between multi-hop nodes and a multi-hop wireless network, a shared key is acquired for hop-by-hop mutual authentication between the multi-hop nodes using a centralized authentication scheme. Using the acquired shared key, distributed authentication between the multi-hop nodes is performed.

Abstract: Disclosed is a time slot allocation method for reducing consumption of energy in a wireless sensor network, including transmitting and receiving, by an upper node, a report request and a response to and from at least one lower node in order to identify whether there is data to be transmitted between the upper node and the at least one lower node, transmitting, by the upper node, information required for data transmission to the at least one lower node based on the report request and response, and transmitting and receiving, by the upper node, data to and from the at least one lower node based on the information required for data transmission.

Abstract: A method and apparatus for a sensor network having a plurality of reference nodes and a sensor node that enables the sensor node to compute a relative position through transmission range control and position mapping. In transmission range control, each reference node sends location information signals to the sensor node while varying transmission power. In position mapping, the sensor node forms a grid of vertical and horizontal lines corresponding to a square area defined by the neighboring reference nodes, extracts coordinates of intersections in the grid belonging to a shared region between areas covered by location information signals of various transmit power levels from the neighboring reference nodes, and sets the position of the sensor node to the middle points of the extracted coordinates. Each reference node sends a location information signal when a random backoff time expires after reception of a location information request signal.

Abstract: A method and system for transmitting data from a base station to a mobile station in a wireless communication system using a multiple hop relay scheme is In a multi-hop system having a plurality of nodes, performing bidirectional data transmission between the nodes comprises: grouping the plurality of nodes into a first node group to a fourth node group, and assigning data transmission intervals to the grouped node groups at each frame, the data transmission intervals dividing each frame in time; receiving, by a second group node, data from an upper group node at a first frame and, at the same time, receiving, by a third group node, data from a lower group node; and transmitting by the second group node data to the upper group node at a second frame and, at the same time, transmitting by the third group node data to the lower group node.

Abstract: A method for performing communication in the wireless sensor network is disclosed. The upper node transmits a beacon message to the lower nodes, wherein the beacon message distinguishes an indirect transmission interval, in which the upper node transmits downlink data to the plurality of lower nodes, from a direct transmission interval adjacent to the indirect transmission interval, in which the upper node receives uplink data from the plurality of lower nodes. The lower nodes determine the indirect transmission interval and the direct transmission interval from the received beacon message. The downlink data is transmitted from the upper node to the lower nodes in the indirect transmission interval. The uplink data is transmitted from the lower nodes to the upper node in the direct transmission interval. When communication is performed between the upper node and the lower nodes, the data can be efficiently transmitted from the upper node to the lower nodes.

Abstract: A medium access control (MAC) frame provision method establishes security in an IEEE 802.15.4 network. A MAC frame is generated, which includes a MAC header, a payload field, and a frame check sequence (FCS) field, the payload field including relevant main data according to a frame type defined in the MAC header. A disguised decoy data sequence number (DSN) is generated and inserted into the MAC header. A real DSN, which is a corresponding transmission sequence number of the MAC frame, is generated and inserted into the payload field. The MAC frame is transmitted, including the encrypted payload field, to a counterpart node. A MAC ACK frame acknowledges reception of the transmitted MAC frame; and a DSN is compared in the received MAC ACK frame with the real DSN. An authentication of the counterpart node is performed when the received MAC ACK frame is equal to the real DSN.

Abstract: A packet transmission method for a WPAN that for alleviating traffic concentration in an active period and improving network throughput by controlling packet transmission timing in the active period. A packet transmission method for a wireless personal area network including a coordinator operating with a specific duty cycle and a plurality of devices includes determining, when a packet is generated, whether there is another packet waiting to be sent; determining, if there is no other packet waiting to be sent, whether the network is in an inactive period; setting, when network is in an inactive period, a backoff time; and sending the packet when the backoff time has expired. The packet transmission method controls an initial backoff value adaptively to a duty cycle of the network.

Abstract: An apparatus and method for providing data packet security in a wireless sensor network including a plurality of sensor nodes. The apparatus includes a memory unit for storing a plurality of node characteristic information and a plurality of settable security status information, each of the node characteristic information corresponding to at least one of the settable security status information; and a control unit for examining the node characteristic information of the control unit, if a data packet generation request is made, detecting the security status information corresponding to the examined node characteristic information from the memory unit, and generating data packets including the detected security status information.

Abstract: A method for reducing power consumption in a wireless sensor network is provided. An optimized path destined for a sink node is set using a common channel in which first and second nodes use a CSMA scheme. A first channel is set and transmission/reception slots for packet transmission/reception are allocated in the first channel. A packet is transmitted to the second node through a first transmission slot using a TDMA scheme. When a packet is not received from the second node through a first reception slot within a first set amount of time, the first reception slot is allowed to transition to an inactive state. The first node is one of the sink node, at least one parent node, and at least one child node of the parent node, and the second node is one of child nodes of the first node.

Abstract: A method, apparatus and system for displaying topology information of a wireless sensor network includes a plurality of sensor nodes. The method typically includes: receiving node information collected and extracted from the sensor nodes; comparing the received node information with stored node information; computing, when the received node information is unequal to the stored node information, visualization information on a sensor node whose information is not present in the stored node information; and displaying the sensor nodes on concentric circles using the visualization information.

Abstract: A hybrid channel assignment method comprising the steps of negotiating among routers to select one router to act as a central server; collecting, at the selected router, information on an entire network transmitted from the other routers, and assigning channels based upon the information on the entire network; and reassigning channels of respective routers based upon dynamically-changing traffic characteristics. The hybrid channel assignment method can assign channels using both centralized processing and distributed processing in order to ensure optimally correct channel assignment consistent with present traffic characteristics. This as a result can prevent network resources from being wasted and also increase network capacity, thereby optimizing effective use of the network resources.

Abstract: A method and a system for interworking with a Broadband Wireless Access (BWA) network in a Wireless Local Area Network (WLAN) terminal. According to the method, a relay station for connecting the Wireless Local Area Network (WLAN) terminal with the Broadband Wireless Access (BWA) network sets a connection with the Broadband Wireless Access (BWA) network through an initialization process. A user authentication with the Wireless Local Area Network (WLAN) terminal is performed by the relay station in compliance with a Wireless Local Area Network (WLAN) protocol. A user authentication with a Broadband Wireless Access (BWA) network Access Control Router (ACR) is performed in compliance with a Broadband Wireless Access (BWA) network protocol by the relay station in place of the Wireless Local Area Network (WLAN) terminal.