摘要:
Provided is a Media Access Control (MAC) forwarding method for multi-hop routing in a communication system between vehicles. The method includes the steps of: a) receiving a frame from all nodes and checking whether there are duplicate frames; b) partly updating forwarding cache table (FCT) information, or updating SNT information and checking whether a destination address is a corresponding node; c) updating the FCT information, transmitting an Ack signal and transferring the frame to the upper layer, or searching whether the destination address is registered as “d_addr”; d) updating the FCT information and transmitting a delay ACK frame or checking whether the transmitted frame is a flooding frame; and e) updating the FCT information, checking whether the other node does not transmit the “d_ack” and inserting a flooding frame, otherwise, updating the FCT information and abandoning the frame.
摘要:
Provided is a Media Access Control (MAC) forwarding method for multi-hop routing in a communication system between vehicles. The method includes the steps of: a) receiving a frame from all nodes and checking whether there are duplicate frames; b) partly updating forwarding cache table (FCT) information, or updating SNT information and checking whether a destination address is a corresponding node; c) updating the FCT information, transmitting an Ack signal and transferring the frame to the upper layer, or searching whether the destination address is registered as “d_addr”; d) updating the FCT information and transmitting a delay ACK frame or checking whether the transmitted frame is a flooding frame; and e) updating the FCT information, checking whether the other node does not transmit the “d_ack” and inserting a flooding frame, otherwise, updating the FCT information and abandoning the frame.
摘要:
A highly precise clock synchronization apparatus in a real-time locating system (RTLS), includes an optical transmitting/receiving unit for receiving a clock information frame from a clock synchronization server, converting the received clock information frame in series-parallel, and transmitting/receiving the clock information data and the clock information; an offset estimation unit for detecting a preamble signal and a clock information signal from the series-parallel converted clock information frame, calculating a phase difference value by comparing the detected preamble signal with the detected clock information signal, and outputting an offset value based on the calculated phase difference value; and a clock synchronization unit for updating a local clock value to a time of the clock synchronization server based on the offset value and the clock information frame.
摘要:
A highly precise clock synchronization apparatus in a real-time locating system (RTLS), includes an optical transmitting/receiving unit for receiving a clock information frame from a clock synchronization server, converting the received clock information frame in series-parallel, and transmitting/receiving the clock information data and the clock information; an offset estimation unit for detecting a preamble signal and a clock information signal from the series-parallel converted clock information frame, calculating a phase difference value by comparing the detected preamble signal with the detected clock information signal, and outputting an offset value based on the calculated phase difference value; and a clock synchronization unit for updating a local clock value to a time of the clock synchronization server based on the offset value and the clock information frame.
摘要:
Provided are a node synchronization system for low-power in a sensor network and a method thereof. The node synchronization system includes: a network transmitting means for transmitting information on a synchronization time difference to the sensing data collecting means and transmitting sensing data to a network; the sensing data collecting means for receiving synchronization time information from the network transmitting means, being synchronized with the network transmitting means, collecting the sensing data from a sensing means, and transmitting the sensing data to the network transmitting means; and the sensing means for receiving synchronization time information from the sensing data collecting means, being synchronized with the sensing data collecting means, sensing a sensing peripheral environment information, and transmitting the sensing data to the sensing data collecting means.
摘要:
Provided is a method for managing dormant nodes in a wireless sensor network. The method includes the steps of: a) acquiring and storing information on distance and location of sensor nodes registered in a corresponding cluster among at least one cluster managed by a managing node; b) selecting a dormant object node among the sensor nodes by the managing node; c) transmitting dormant information that the dormant object node should go into a dormant state for a predetermined period through a beacon message to the dormant object node and creating a dormant node management table; and d) updating a dormant time of the dormant node management table every beacon cycle by the managing node according to setup of a dormant time central managing function and notifying dormancy expiration to the corresponding dormant node.
摘要:
Provided is a method for managing dormant nodes in a wireless sensor network. The method includes the steps of: a) acquiring and storing information on distance and location of sensor nodes registered in a corresponding cluster among at least one cluster managed by a managing node; b) selecting a dormant object node among the sensor nodes by the managing node; c) transmitting dormant information that the dormant object node should go into a dormant state for a predetermined period through a beacon message to the dormant object node and creating a dormant node management table; and d) updating a dormant time of the dormant node management table every beacon cycle by the managing node according to setup of a dormant time central managing function and notifying dormancy expiration to the corresponding dormant node.
摘要:
Provided is a method for determining superframe to efficiently perform beacon scheduling by allocating superframe lengths which are different according to a routing depth of sensor nodes in a ZigBee based wireless sensor network. The method for determining a superframe for beacon scheduling, includes the steps of: receiving a beacon from a neighboring node and grasping information on a superframe used by the neighboring nodes; and determining a transmission time and a length of own superframe based on superframe information of the grasped neighboring node.
摘要:
A passive tag including a volatile memory is provided. The passive tag includes: a sensing unit which senses or measures information about environmental surroundings of the tag; a volatile memory; a non-volatile memory; and a control unit which firstly stores resultant data sensed or measured by the sensing unit in the volatile memory and then moves the data stored in the volatile memory to the non-volatile memory according to pre-set conditions. Therefore, the life of the tag is prolonged and stability of important data can be secured.
摘要:
Provided is an apparatus and method for computing the location of a radio beacon by using received signal strength (RSS) and multiple frequencies. The apparatus and method of the present invention computes the location of a radio beacon without limitation in distance by using multiple frequencies and received signal strength to resolve the problem of phase ambiguity. A radio beacon location computing system includes a plurality of base stations configured to receive signals of multiple frequencies transmitted from the radio beacon, and detect and output phase differences and received signal strength; and a location computing server configured to receive the phase differences and the received signal strength outputted from the respective base stations, acquire calculation distances based on the phase differences, remove phase ambiguity from the calculation distances based on the received signal strength, and compute the location of the radio beacon.