摘要:
A super frame structure supporting a mesh network, and a beacon scheduling method. The super frame structure and the beacon scheduling method may support a mesh topology in a beacon enabled mode, may have an algorithm that is simple and easily realized via beacon scheduling using a distribution method, and may easily adapt to changes in a network environment.
摘要:
A medium access control (MAC) technique of a multihop sensor network. In the multihop sensor network, the MAC technique may contribute to significantly reducing transmission delay, and allow real-time services to be provided to all nodes by extending a guaranteed time slot (GTS) restricted to one hop in a personal area network (PAN) coordinator (PNC) to all nodes. Furthermore, the MAC technique may allow the number of available GTSs to be significantly increased, by using all 16 frequency band channels instead of using only a single frequency band and setting a multi-superframe.
摘要:
There is provided a mesh routing method in beacon-enabled wireless AD-HOC networks that includes: broadcasting, by nodes constituting a wireless AD-HOC network, a beacon message loading neighbor node information on a beacon payload; managing, by a node receiving the broadcasted beacon message, its own neighbor node table by extracting the neighbor node information loaded on the beacon payload; and performing, by a source node attempting to transmit data or commands, mesh routing on the basis of its own neighbor node table.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
A method and apparatus using a synchronous sensor network medium access control (MAC) protocol, such as a ZigBee or IEEE 802.15.4 low-rate wireless personal area network (WPAN), is disclosed. A method and apparatus for constructing a ubiquitous sensor network (USN) of which a life is increased by using power beacons and reducing the number of unnecessary control packets (beacon packets), thereby reducing an initialization time between nodes and preventing beacon collision, is also disclosed. A beacon packet channel having a large output power and a data channel of which a transmission range is restricted by reducing an output power to be less than that of the beacon packet channel, may be simultaneously used.
摘要:
A wireless network system using a cyclic frame including a beacon period (BP), a mesh contention access period (MCAP), and a slot period (SP). The cyclic frame has a frame structure that shares a channel hopping sequence of a node, thereby sharing the channel hopping sequence that operates as an existing mesh node without generating an additional channel hopping sequence, and supporting mesh and star type topologies together in order to efficiently operate a network.