Abstract: A packet is transmitted from a source node to a destination node via a relay path in a multi-hop network. The packet is transmitted by cache routing or source routing, depending on the presence or absence of information identifying the destination node in a history table maintained at the source node. In source routing, relay path information is included in the packet. In cache routing, relay nodes obtain routing information from entries in their own cache routing tables. Each entry indicates only the destination node and the next relay node, and each cache routing table has a limited size. When a series of packets are transmitted to the second node, cache routing can be used for all but the first packet, thereby reducing packet overhead.

Abstract: In a communications apparatus, a communication controller transmits and receives signals on any of plural channels. A channel switching controller is responsive to channel switching information selectively defining plural reception-waiting periods using the channels to alter a channel to be used by the communication controller. A neighboring node channel controller exchanges channel switching information with other nodes to manage the channel switching information received from the other nodes. When transmitting transmission signals, a transmission controller refers to the channel switching information of the other nodes, and controls repetitive transmission of the transmission signals on the channel thus searched for.

Abstract: An intermittent operation communication device periodically repeats beacon transmission, data reception or data reception wait, and sleep to transmit data to any of reception side communication devices. The intermittent operation communication device includes a data transmitter for performing transmission when receiving a beacon from any of the reception side communication devices and having data traffic generated meant for a reception side communication device, a transmission announcer for intermittently transmitting a transmission announcement beacon while waiting for reception when having the data traffic generated, and an adjuster for monitoring a transmission announcement beacon from any other of the intermittent operation communication devices to adjust the transmission of the data traffic.

Abstract: An intermittent operative communication apparatus can send data, received from a source communication device, to any receiver communication device at a predetermined interval and wait for receiving data at the predetermined interval. The communication apparatus has a selector for selecting one or multiple receiver communication devices as a reference communication device that gives a reference timing at which the communication apparatus waits for receiving data, and a timing controller for setting a timing, at which the communication apparatus waits for receiving data, to a timing according to operation of any reference communication device.

Abstract: An information communication apparatus may include a request buffer, a request sorting device, a sending device, a frame generating device, and a frame transmitting device. A request buffer may store transmission requests corresponding to frames. A request sorting device may sort the transmission requests. A sending device may send the sorted transmission requests in accordance with a transmission timing that is determined based on destinations of the frames and in which a receiving node can receive the frames. A frame generating device may generate frames based on the received transmission requests. A frame transmitting device configured to transmit the generated frames.

Abstract: A wireless communication apparatus having a plurality of neighboring wireless communication apparatuses may includes a wireless transmitter, an information control storage member, and a transmitting power calculator. A wireless transmitter may transmit a wireless signal with a transmitting power to a destination wireless communication apparatus. An information control storage member may maintain first information of links between the wireless communication apparatus and the plurality of neighboring wireless communication apparatuses, and second information of a communication route between the wireless communication apparatus and the destination wireless communication apparatus. A transmitting power calculator may calculate the transmitting power based on the first and second information, so as to ensure reception of the wireless signal.

Abstract: A tree topology in a multi-hop wireless network is configured by having each node other than the root node select a parent node within direct communication range, thereby becoming a child node of the selected parent node. Neighboring nodes provide selection values such as routing costs and local structural information indicating the existing topology in their vicinities, including parent-child relationships. The selection of the parent node is based on the received selection values, but the local structural information is used to bias the selection in favor of neighboring nodes with at least one other child node. This selection strategy reduces the number of parent nodes in the network and enables more nodes to operate as end nodes, which can then conserve power by carrying out sleep control.

Abstract: In a wireless communication network system performing multi-hop wireless communications, a network node has a calculator for exchanging control packets with its neighboring nodes to calculate link cost values, another calculator for calculating path costs incurred on the way to a network node of interest, a manager for managing the number of downstream nodes subsidiary to each daughter node, and a downstream node adjuster for adjusting the number of the downstream nodes subsidiary to each daughter node. The adjuster produces control information, into which link cost and/or path cost information is inserted. The adjuster adjusts the contents of the link cost or path cost information, to be inserted into the produced control information, according to the numbers of the downstream nodes subsidiary to the daughter nodes.

Abstract: A wireless communication system includes a first node, multiple second nodes, and multiple third nodes that communicate with the first node through the second nodes. The second and third nodes transmit control information to their neighboring third nodes, which calculate link costs from the reception status of the control information. The control information transmitted by each node includes a path cost indicating the cost of a path between the transmitting node and the first node. From the path costs in received control information, each third node selects a second node through which to communicate with the first node, and selects a parent node as the destination of the first hop on the path through the selected second node to the first node. Routing is thereby accomplished autonomously without having the second nodes flood the system with routing requests.

Abstract: A packet is transmitted from a source node to a destination node via a relay path in a multi-hop network. The packet is transmitted by cache routing or source routing, depending on the presence or absence of information identifying the destination node in a history table maintained at the source node. In source routing, relay path information is included in the packet. In cache routing, relay nodes obtain routing information from entries in their own cache routing tables. Each entry indicates only the destination node and the next relay node, and each cache routing table has a limited size. When a series of packets are transmitted to the second node, cache routing can be used for all but the first packet, thereby reducing packet overhead.

Abstract: A packet relay system in which each node calculates a link cost of each adjacent node based on an arrival rate of a packet from each adjacent node, acquires an accumulated value of a link cost calculated by each node in a range of nodes from a sink node for each adjacent node, calculates, for each adjacent node, a path cost of the one adjacent node by adding the link cost calculated to the accumulated value, and relays a data packet to one adjacent node selected from among nodes adjacent to the node based on a path cost of each adjacent node. This enables establishment of an upstream path to a sink node without increasing the amount of communication in a network.

Abstract: A transmission timing control apparatus included in a network node constituting a telecommunications system is configured to use the reception timing of a timing signal from another node to determine the transmission timing of a timing signal of the own node and determine a time slot for transmission of a data signal in accordance with the transmission timing and the reception timing of a timing signal from the other node. A response timing signal transmitter transmits a response timing signal when received the timing signal from the other node. A transmission timing control circuit uses the reception timing of the timing signal and that of the response timing signal to determine the timing at which the own node transmits the timing signal.

Abstract: A telecommunications control apparatus is included in each of a plurality of nodes constituting a telecommunications system and includes a reception power decider for determining the reception power value of a control signal received from another node. A control signal decider decides, in accordance with the reception power value of the control signal thus determined, whether or not the own node should communicate with the other node in relation to interference at the own node. A communication controller controls communication between the own node and the other node in accordance with the result of decision made by the control signal decider.

Abstract: The communication apparatus intermittently carries out receiving operation during a predetermined reception period. The apparatus includes a wireless communication section for carrying out wireless communication, which includes a carrier sensor for sensing a carrier at the beginning of the communication, and a carrier sense switching section for using carrier sense levels different between packet transmission and reception to switch the carrier sense level of the carrier sensor according to the packet. Thus, the apparatus can use and flexibly adjust the optimum carrier sense level for the intermittent receiving operation within the reception period.

Abstract: Each node in a communication system operates on a repetitive internal timing cycle, at certain phases in which the node transmits data and state variable signals. The state variable signals indicate the node's data transmission timing. Each node has a virtual node calculator that simulates the timing cycles of neighboring nodes according to the state variable signals received from those nodes, and a phase calculator that varies the phase state of the node according to the simulated phase states of the neighboring nodes. Neighboring nodes can therefore interact continuously, even though they transmit state variable signals only intermittently. Consequently, a group of neighboring nodes can autonomously establish and maintain transmission time slots of equal length.

Abstract: An intermittent operative communication apparatus can send data, received from a source communication device, to any receiver communication device at a predetermined interval and wait for receiving data at the predetermined interval. The communication apparatus has a selector for selecting one or multiple receiver communication devices as a reference communication device that gives a reference timing at which the communication apparatus waits for receiving data, and a timing controller for setting a timing, at which the communication apparatus waits for receiving data, to a timing according to operation of any reference communication device.

Abstract: An intermittent operation communication device periodically repeats beacon transmission, data reception or data reception wait, and sleep to transmit data to any of reception side communication devices. The intermittent operation communication device includes a data transmitter for performing transmission when receiving a beacon from any of the reception side communication devices and having data traffic generated meant for a reception side communication device, a transmission announcer for intermittently transmitting a transmission announcement beacon while waiting for reception when having the data traffic generated, and an adjuster for monitoring a transmission announcement beacon from any other of the intermittent operation communication devices to adjust the transmission of the data traffic.

Abstract: Communication control apparatus provided in nodes forming a telecommunications network includes a transmission timing calculator responsive to the state of the phase of the own node to determine a timing at which the node transmits data. The calculator is responsive to a state variable signal transmitted by a neighboring node and reflecting the phase of the neighboring node to change the state of the phase of the own node in accordance with a time development rule. The calculator monitors a phase difference of the own node against the neighboring node to calculate, based on the difference, the ratio of collision on data transmission timing between the own and neighboring nodes. The stress value corresponding to the collision ratio is stored time-serially. A stress response function value is generated such that the stored stress value causes the time development rule to shift the phase with its value made at random.

Abstract: In a communication system including nodes laid out in a grid, each node operates on a repetitive internal timing cycle, at certain phases in which the node transmits data and state variable signals. The state variable signals transmitted by a node indicate its internal phase and its position in the grid. The advance of the phase at each node is governed by a phase response function, which drives neighboring nodes whose data transmissions could collide out of phase with each other, and a synchronization alliance function, which brings certain nodes having positional relationships that preclude data collisions into phase with each other. A highly efficient data transmission timing pattern can thereby be established autonomously.

Abstract: An inductive antenna device intervenes in communication between an RFID tag including an RFID chip and a tag antenna and an RFID access device for accessing the RFID tag. The inductive antenna device includes an access-device-side antenna that is electromagnetically coupled with the antenna of the RFID access device, and a tag-side antenna that is electromagnetically coupled with the tag antenna. The RFID chip and tag antenna in the RFID tag are in an electromagnetically shielded space. The inductive antenna device is attached to the RFID tag or the inductive antenna device is brought in a predetermined position to make communication possible between the RFID tag and RFID access device. An authorized access to the RFID tag is thereby permitted with easy operation with unlimited number of access times, and an illegal leak of the tag information is prevented with a low cost configuration.