Abstract: A method of resource allocation among mobile stations in distributed communication network enables a mobile station to perceive existence of another mobile station through a time slot for resource allocation without having to communicate with a sensor node. If perceiving another mobile station, the mobile station allocates time slot resources not to overlap with the time slot resources of another mobile station, and performs location measurement or media access and reception of service from the sensor node through the allocated time slot resources. Because the mobile stations of the network can perceive each other by communicating with each other, and accordingly allocate their own resources without overlapping with the resource of the others, frequent collision of the signal for location measurement can be prevented.

Abstract: Disclosed is a packet forwarding system having an efficient packet memory management unit and an operation method therefor. The packet forwarding system includes an input unit inputting data in unit of transmission; a packet memory management unit assembling the data into an Internet Protocol(IP) packet and loading the packet into a packet memory, and reading out pointers of an IP packet header and an IP packet trailer connected to the header; a header processing unit deciding a packet classification and a transmission destination by using the read header, and re-transmitting to the packet memory management unit the pointer of the trailer connected to the header; and an output unit dividing the trailer read from the packet memory management unit into data in units of transmission based on the pointers of the header transmitted from the header processing unit and the trailer, and outputting the divided data to a channel.

Abstract: Provided is a method for refining node position information in a wireless sensor network having an ultra wideband communication network and a wireless personal area network where the initial positions of respective nodes are set, by utilizing nodes at a 2-hop distance, or more than a 2-hop distance when the number of neighboring nodes at a 1-hop distance is not sufficient to perform triangulation, and to refine the position of nodes based on a distance measured between the respective nodes. Because the initial position is refined and confirmed in a wireless sensor network, a user node operates as a pseudo anchor node for the nodes which have no anchor node nearby. Furthermore, as a node has the refined position, it can act as a pseudo anchor node and be used to compute the position of the other nodes. Additionally, positions of nodes of the wireless sensor network can be estimated with more accuracy.

Abstract: A time synchronization method in a wireless sensor network, has an upper node that provides back-off scheduling to lower nodes in the wireless sensor network of a hierarchical structure. Each of the lower nodes synchronizes time according to the back-off scheduling based on its local clock. The time synchronous method also allows the number of packets required for synchronization in the wireless sensor network to sharply decrease, and the life time of the network to increase. Additionally, the time synchronous method provides a response packet from a lower node in response to a synchronization packet from an upper node, which is used as a synchronization start packet for secondary lower nodes, so that synchronization in the entire network is rapidly processed.

Abstract: A packet forwarding system to transfer packets through a plurality of interfaces by reading out information for the packet forwarding beforehand includes a packet processor that organizes and processes data to be transferred into packets, a packet memory storing the organized packets, a plurality of interfaces respectively transferring the packets stored in the packet memory depending on destinations of the packets, and a packet forwarding manager managing an packet information to transfer the packets through the plurality of the interfaces, respectively, and to control transfer of the packets immediately through a corresponding interface of the plurality of the interfaces by reading out the packet information before the packet forwarding. Accordingly, the fast packet forwarding is realized by processing the packet information read and the actual packet forwarding in parallel.

Abstract: A coordinator's data transmission method, a device's data reception method, a coordinator using the coordinator's data transmission method and a device using the device's data reception method are provided. In a Zigbee system including at least one device and a coordinator for coordinating the device, in a case where a frame pending bit in a beacon frame is determined to be a value representing a direct transmission method, a beacon frame containing an address of a device to receive data and a data transmission time is generated and data is transmitted from the coordinator at the data transmission time. Data transmission time and power consumption can be reduced.

Abstract: A packet classification apparatus and method using field level tries includes a main processing part for generating and maintaining the field level tries, which organize a multi-field packet by field in a hierarchical structure for classifications; and classification engines, each of which is provided with a first classification part for performing queries and updates and processing a prefix lookup represented by an IP source/destination address lookup, and a second classification part for proceeding with classifications by corresponding field based on a result of the first classification part in order to process a range lookup belonging to the result. Accordingly, tries in the unit of a field are developed so that packet classifications for high-speed networking with excellent query performance are secured, and wherein approximately a half-million classifier rules can be processed.

Abstract: An apparatus and a method for performing an efficient address search in an ethernet switch having a plurality of ports. Information packets where the source and destination addresses are one and the same are rejected and not processed. When destination address is not in a local port, the main look up table for the entire switch is then consulted. If the main look up table does not have the destination address, the main look up table learns the address and the port broadcasts the information packet to all ports in the switch. A hash algorithm is used to look up addresses in tables. Thus, more efficient processing of information in the switch can be realized.

Abstract: A time synchronization method in a wireless sensor network, has an upper node that provides back-off scheduling to lower nodes in the wireless sensor network of a hierarchical structure. Each of the lower nodes synchronizes time according to the back-off scheduling based on its local clock. The time synchronous method also allows the number of packets required for synchronization in the wireless sensor network to sharply decrease, and the life time of the network to increase. Additionally, the time synchronous method provides a response packet from a lower node in response to a synchronization packet from an upper node, which is used as a synchronization start packet for secondary lower nodes, so that synchronization in the entire network is rapidly processed.

Abstract: Provided is a method for refining node position information in a wireless sensor network having an ultra wideband communication network and a wireless personal area network where the initial positions of respective nodes are set, by utilizing nodes at a 2-hop distance, or more than a 2-hop distance when the number of neighboring nodes at a 1-hop distance is not sufficient to perform triangulation, and to refine the position of nodes based on a distance measured between the respective nodes. Because the initial position is refined and confirmed in a wireless sensor network, a user node operates as a pseudo anchor node for the nodes which have no anchor node nearby. Furthermore, as a node has the refined position, it can act as a pseudo anchor node and be used to compute the position of the other nodes. Additionally, positions of nodes of the wireless sensor network can be estimated with more accuracy.

Abstract: A method of resource allocation among mobile stations in distributed communication network enables a mobile station to perceive existence of another mobile station through a time slot for resource allocation without having to communicate with a sensor node. If perceiving another mobile station, the mobile station allocates time slot resources not to overlap with the time slot resources of another mobile station, and performs location measurement or media access and reception of service from the sensor node through the allocated time slot resources. Because the mobile stations of the network can perceive each other by communicating with each other, and accordingly allocate their own resources without overlapping with the resource of the others, frequent collision of the signal for location measurement can be prevented.

Abstract: Disclosed is a phase noise compensation apparatus to be applied to the OFDM system, comprising an ICI estimating unit for estimating inter carrier interference (ICI) using a pilot sub-carrier included in a reception signal, a estimating unit for estimating a common phase error (CPE), which is a phase noise from the reception signal as sampled, using the pilot sub-carrier, and estimating a transmission signal by removing the estimated CPE from the reception signal, a calculating unit for calculating phase change by the ICI in the reception signal by convoluting the ICI and the transmission signal, and an equalizer for compensating the calculated phase change by the ICI in the reception signal. Accordingly, phase noise can be exactly compensated by estimating as phase noise the result of convoluting a received signal where the CPE is removed in a frequency domain and the estimated ICI according to the present invention.

Abstract: A receiver having a low computation complexity so as to estimate a transmitted includes a likelihood function calculator calculating likelihoods of transmittable signals using a currently received signal, at least one previously received signal, and an estimated signal corresponding to the at least one previously received signal; and a maximum value output unit outputting a transmittable signal corresponding to a likelihood function of the likelihood functions having a maximum value. Thus, a currently received signal can be estimated using a previously received signal, a previously estimated signal, and the currently received signal. As a result, the reliability of the estimated signal can be improved. Also, the previously estimated signal can be stored to prevent the complexity of a computation from being increased.

Abstract: A method for forming a power-efficient network in a wireless sensor network including allowing a device connected to a first coordinator which configures a first wireless network to apply receiving-end power of the device for a predetermined time period intermittently; allowing the device to which the receiving-end power is applied to receive a beacon signal transmitted from a second coordinator which configures a second wireless network; and allowing the device to operate as a router after receiving the beacon signal. It extends a network effectively, while minimizing power consumption of a node, and extends the lifetime of a network by minimizing power consumption of node.

Abstract: A coordinator's data transmission method, a device's data reception method, a coordinator using the coordinator's data transmission method and a device using the device's data reception method are provided. In a Zigbee system including at least one device and a coordinator for coordinating the device, in a case where a frame pending bit in a beacon frame is determined to be a value representing a direct transmission method, a beacon frame containing an address of a device to receive data and a data transmission time is generated and data is transmitted from the coordinator at the data transmission time. Data transmission time and power consumption can be reduced.

Abstract: A method for forming a database to route a data packet from a plurality of prefixes and a method for routing and a router using the method thereof are disclosed. The method for forming the database including the steps of: forming a main-table by aligning the prefixes into a reference length, storing information about the prefixes when the length of the prefixes is shorter than the reference length, and storing connection information about a table from which information about the prefixes can be obtained when the length of the prefixes is longer than the reference length at an entry of the main-table, and forming a sub-table with respect to prefixes having longer length than the reference length by calculating a distance between a base point and the respective prefixes and arraying nodes having a same distance, the base point being a node indicated by the connection information.

Abstract: A packet forwarding system to transfer packets through a plurality of interfaces by reading out information for the packet forwarding beforehand includes a packet processor that organizes and processes data to be transferred into packets, a packet memory storing the organized packets, a plurality of interfaces respectively transferring the packets stored in the packet memory depending on destinations of the packets, and a packet forwarding manager managing an packet information to transfer the packets through the plurality of the interfaces, respectively, and to control transfer of the packets immediately through a corresponding interface of the plurality of the interfaces by reading out the packet information before the packet forwarding. Accordingly, the fast packet forwarding is realized by processing the packet information read and the actual packet forwarding in parallel.

Abstract: Disclosed is a packet forwarding system having an efficient packet memory management unit and an operation method therefor. The packet forwarding system includes an input unit inputting data in unit of transmission; a packet memory management unit assembling the data into an Internet Protocol(IP) packet and loading the packet into a packet memory, and reading out pointers of an IP packet header and an IP packet trailer connected to the header; a header processing unit deciding a packet classification and a transmission destination by using the read header, and re-transmitting to the packet memory management unit the pointer of the trailer connected to the header; and an output unit dividing the trailer read from the packet memory management unit into data in units of transmission based on the pointers of the header transmitted from the header processing unit and the trailer, and outputting the divided data to a channel.

Abstract: A packet classification apparatus and method using field level tries includes a main processing part for generating and maintaining the field level tries, which organize a multi-field packet by field in a hierarchical structure for classifications; and classification engines, each of which is provided with a first classification part for performing queries and updates and processing a prefix lookup represented by an IP source/destination address lookup, and a second classification part for proceeding with classifications by corresponding field based on a result of the first classification part in order to process a range lookup belonging to the result. Accordingly, tries in the unit of a field are developed so that packet classifications for high-speed networking with excellent query performance are secured, and wherein approximately a half-million classifier rules can be processed.

Abstract: A method for forming a database to route a data packet from a plurality of prefixes and a method for routing and a router using the method thereof are disclosed. The method for forming the database including the steps of: forming a main-table by aligning the prefixes into a reference length, storing information about the prefixes when the length of the prefixes is shorter than the reference length, and storing connection information about a table from which information about the prefixes can be obtained when the length of the prefixes is longer than the reference length at an entry of the main-table, and forming a sub-table with respect to prefixes having longer length than the reference length by calculating a distance between a base point and the respective prefixes and arraying nodes having a same distance, the base point being a node indicated by the connection information.