172 results about "Ad hoc communication" patented technology

A heterogeneous wireless network topology suited for low-power, short-range and ubiquitous ad-hoc communication. The network topology integrates different wireless transmission technologies, in particular to a wireless sensor network including different node types and communication technologies. The network is highly heterogeneous and can be operated according to the master-slave principle. The nodes can have different wireless communication means tailored to their individual role in the network and other constraints, thus allowing different communication patterns.

A radio communication apparatus having a function for allowing it to be connected both to an ad hoc network and to a mobile communication network, yet having a structure that is not complicated with cost increases suppressed, and yet being capable of smoothly switching between the networks. The radio communication apparatus (10) uses a TDD-CDMA system for communication with a base station of the mobile communication network, and comprises ad hoc communication means for performing a radio communication with another neighboring radio communication apparatus by making an ad hoc network in conjunction with the other radio communication apparatus. This ad hoc communication means, when communicating with the other radio communication apparatus, uses the TDD-CDMA system common to the mobile communication network.

An object of the present invention is to improve the network usage efficiency and economy. There is provided a radio communication apparatus (10) having ad-hoc communication means for building an ad-hoc network with other nearby radio communication apparatus and performing communication with the other radio communication apparatus by radio. The ad-hoc communication means comprises: node type setting means for searching the ad-hoc network for the master and setting the node type of the radio communication apparatus (10) to any of the master and slave on the basis of the search result; set-up information acquisition means for, when the node type of the radio communication apparatus (10) is set to the slave, transmitting and receiving control signals to and from the master to acquire set-up information required for communication with any of the master and slave in the ad-hoc network and storing the set-up information in storage means; and data signal transmission means for directly transmitting and receiving data signals to and from any of the master and slave in the ad-hoc network in accordance with the set-up information acquired from the master.

Communication bands are effectively allocated to each communication station under a communication environment of an autonomous distributed type system such as an ad-hoc communication. Each communication station acquires a priority slot with which each communication station itself performs data transmission preferentially at predetermined time intervals, and releases or allocates its own priority slot to other communication station in response to a permission form upper layer of a communication protocol based on a fact that the transmission data is not in a buffer. Thereby, it is able to effectively utilize the communication bands, and to improve a throughput of the whole system.

The present invention is to provide each communication station with a transmission prioritised period without any useless latency in an ad-hoc communication environment including no control station. For this end, each communication station periodically transmits the beacon signal and acquires the transmission prioritised period immediately after transmission of the beacon. If the number of communication stations in the network is small, a communication station transmit a supplementary beacon within the super frame period, thereby effectively shortening the beacon interval and reducing latency at the start of transmission. At the time when a new communication station enters the network, the supplementary beacon is released in order to accommodate such new communication station.

Nodes (103a-d, 105, 107, 109a-c, 111a-c) in an ad hoc communication network are coordinated. The network includes the node (111b) and one or more neighbor nodes (103a-d, 105, 107, 109a-c, 111a,c). The node (111b) can sleep in a low duty cycle. Further, the node (111b) can awaken, responsive to a schedule; and register with a cluster head (101); listen for one or more neighbors, wherein the at least one neighbor can be active (103a-d, 105, 107) or idle (109a-c, 111a,c); and/or listen for one or more requests from the cluster head (101) or active neighbor(s) (103a-d, 105, 107). Responsive to the request(s), the idle node (111b) can become active on a communication link.

System and method for operating a smart phone and a smart watch connectable through an ad hoc communication link is provided. Operations of the smart watch can be controlled by employing a virtual watch user interface operated through the smart phone. The user interface is displayed in a synchronized manner between the phone and the watch. The user can switch freely between the phone and the watch employing the same user interfaces. In another aspect, the smart phone can be operated in a low power mode mimicking the operations of the smart watch.

Provided are a system and method for informing a vehicle accident using a telematics device. In an emergency, such as vehicle collision, etc., the system and method propagate information on the accident to vehicles around the accident scene, thereby informing the vehicles of traffic congestion. Since the vehicles continuously inform the same to vehicles behind through ad-hoc communication, a vehicle guided by a telematics device can recognize the traffic congestion ahead, re-search for a path, and thereby make a detour. Therefore, although vehicles behind the accident scene cannot see the occurrence of the accident on a foggy highway, etc., the risk of a chain-reaction crash is reduced. In addition, it is possible to avoid traffic congestion due to an accident in downtown.

A system and method for selecting an appropriate transmit power and data rate at which a communication signal is transmitted over a link between nodes in a wireless ad-hoc communication network based on factors such as variations in path loss in the link, fading conditions, noise level estimation and overall link quality. The system and method perform the operations of computing path loss in the link based on information provided to the source node from the destination node pertaining to characteristics of a message that was transmitted by the source node and received by the destination node, determining a noise factor at the destination node, and calculating the power level and rate at which the data is transmitted over the link from the source node to the destination node based on the path loss and the noise factor. More specifically, the method calculates the power level based on the path loss, the noise factor and signal fading, and determines the rate based on the calculated power level. Furthermore, the path loss is computed dynamically as conditions of said link change over time. Accordingly, the system and method are capable of determining the proper level of transmit power and data rate for assuring that the destination node will receive the data transmitted by the source node at a reliability of at least 90%.

Each terminal in a wireless ad-hoc communication system includes an encryption-key management list table 660. The encryption-key management list table 660 stores, in association with a terminal identifier 661 such as a MAC address, a unicast encryption key 662 for use in unicast communication with a terminal identified by the terminal identifier 661, and a broadcast encryption key 663 used when the terminal identified by the terminal identifier 661 performs broadcast communication. Therefore, a broadcast encryption key is provided for each terminal that performs broadcast communication, and the broadcast encryption keys are managed by the individual terminals in an independent and distributed manner. This allows independent and distributed management of broadcast encryption keys in a wireless ad-hoc communication system.

A system and method for data transmission in an ad hoc wireless communication network is useful for improving network efficiency. The method includes determining whether both high priority data and low priority data are queued for transmission from a sending node to a receiving node (step 620). When both high priority data and low priority data are queued for transmission, the high priority data and the low priority data are aggregated in an aggregated data frame (step 625). Finally, the aggregated data frame is transmitted to the receiving node (step 630).

A computer system, method, and computer program product for controlling access to an application program in a wireless device connected to an ad-hoc communications network. The method comprises sending an inquiry message to the network, receiving a response, choosing a selected application, and examining control parameters associated with the selected application. The control parameters dictate a behavior of the selected application such as allowing or refusing communication with the selected application. When a nearby wireless device includes a matching application, connecting the selected application and the matching application further comprises sending a connection request, receiving connection response, launching the selected application, and sending a service request. When the selected application closes, the method further comprises erasing the selected application. To choose the selected application, the method further comprises retrieving an entry from a distributed application directory or selecting the application based on a priority assigned to the entry.

A system and method wherein a master node 710 comprises, as its primary components, a protocol stack 715, a transceiver 720, a search scheduler 725, communication volume prediction means 730 and outside-channel, signal induced interference intensity measuring means 735. A slave node 750 comprises, as its primary components, a protocol stack 760, a transceiver 765 and a search routine 755. The signal induced interference intensity read by the signal induced interference intensity measuring means 735 is transmitted to the search scheduler 725. The search scheduler 725 then employs the signal induced interference intensity to determine the total amount of the resources that are to be allocated for a search.

A communication system (100) comprises a plurality of location enabled communication terminals (101, 103). The communication terminals (101, 103) comprise a GPS location processor (111) which generates a location estimate in response to signals received from satellite information data and a plurality of satellites (105). The communication terminals (101, 103) also comprise a transceiver (117, 119, 121) which can form ad-hoc communication links with other communication terminals (101, 103). An ad-hoc controller 123 controls the generation and transmission of a request for satellite information data to another communication terminal (101, 103). The transceiver (117, 119, 121) receives satellite information data from the other communication terminal (101, 103) and the location estimate is determined in response thereto. The ad-hoc controller (123) is furthermore operable to detect a request for satellite information data from another communication terminal (101, 103) and to transmit satellite information data over the ad-hoc communication link in response. Hence, satellite information data may be dynamically and opportunistically shared between communication terminals (101, 103).

An improved system and procedure for controlling the audio broadcast to users participating in a group conversation. In one embodiment, a communications server employs arbitration logic to decide which of the user has priority to speak, and accordingly mixes only the audio data steams for those users for broadcast to all users. The server can send notification to the user interfaces to inform the users of their current priority status and to allow the users to request that their priority be increased, decreased, eliminated, or passed on for the benefit of another user. A user may also attempt at his user interface to affect the priority of identified other users by informing the arbitration logic of a rating for that user. Additionally, a systems administrator may also arbitrate user priorities, either at his discretion or in conjunction with suggestions provided by the arbitration logic. Finally, and regardless of system-assessed priorities, a user may at his user interface tailor the group conversation broadcast to him by either blocking reception of audio from certain users or by reducing their volume, or may tailor his outgoing audio transmission so they are blocked from being received by selected group conversation participants.

A method for organizing a plurality of communication devices of an ad hoc communication system into a communication network. The devices are organized into one or more communication graphs where at least one of the graphs is a rooted tree. The invention also provides an ad hoc communication system wherein the devices are organized into one or more communication graphs, where at least one of the graphs is a rooted tree. A method for routing a communication session in the system is also provided where a session is routed from the calling node to the tree root and from the tree root to the called node. In a preferred embodiment, shortcuts are sought in the session route.

The invention provides a cooperative landing method for multiple unmanned aerial vehicles. The method comprises the followings steps of: establishing an Ad Hoc communication network for multiple unmanned aerial vehicles; searching for the self position and landing landmark of each unmanned aerial vehicle by using an onboard sensor, and transmitting a data packet to the neighboring unmanned aerial vehicle in a broadcasting way on the basis of the Ad Hoc communication network, wherein the data packet comprises position information and state information; calculating relative distances and relative angles between each unmanned aerial vehicle and the landing mark as well as between the unmanned aerial vehicle and the neighboring unmanned aerial vehicle in combination with self information of the unmanned aerial vehicle according to the received data packet; and constructing an environmental space potential field, calculating the attraction Fatt of the landing mark and repulsive force Frep from the neighboring unmanned aerial vehicles, calculating potential field resultant force, building a kinematic model, and determining the movement track of each unmanned aerial vehicle. Due to the adoption of the cooperative landing method, onboard sensor information can be shared and controlled cooperatively when an unmanned helicopter cluster performs a task, the safety of cluster landing is ensured, and high adaptability and expandability are achieved.

Systems and methods for providing access to a time-slotted communication channel are disclosed. Access to the channel is granted by possession of a pseudo-token transmitted between communication units with packets, such that the recipient of a data packet receives the pseudo-token with the packet. Communication units may be assigned reserved slots during which the pseudo-token automatically is assigned to the communication unit. Further, communication units may be assigned priority levels according to which contention contests may be resolved. Reserved slots and priority rankings may used in combination to accommodate varying levels of QoS required or requested by communication units on the channel.

Techniques for controlling access to a communication channel for each of a plurality of nodes in a wireless ad hoc communication network. According to one embodiment, each node uses a predetermined rule, such as a hash function, to compute which of a plurality of time slots during a contention window it is to attempt transmissions. Each node in the network follows the same rule to access the channel and as a result no additional overhead transmissions are required between the nodes. In addition, contention among different nodes is reduced when a node needs to repeat an attempt to make a transmission. When a node has data to transmit on the channel, it determines a time slot in the contention window period during which to attempt the transmission using a computation that is based on a number identifier assigned to the node, the number of time slots in the contention window period and a transmission count value that represents the number of attempts the node has made to make the transmission. According to another embodiment, nodes are assigned to slot groups based on the time slot computation and the groups are assigned to particular slots during successive blocks in a round robin fashion so as to ensure fair access to the communication channel.

A system and method for identifying potential hidden node problems in a multi-hop wireless ad-hoc communication network, such as an 802.11 network. The system and method evaluates the relationship between the neighbors of each respective node to identify nodes of a wireless ad-hoc communication network whose capabilities of receiving data packets can be adversely affected by hidden node problems in order to avoid selecting paths containing those potentially problem nodes for routing data packets. Specifically, for each node, the system and method generates a node metric identifying the relationship between the neighbors of a node. Each node can then transmit its respective metric with its routing advertisement data, so that other nodes can assess the degree of potential hidden node problem that may be experienced by that node, and can choose to avoid using that potentially problem node for routing data packets to other nodes.