101 results about "Radiowave propagation" patented technology

Provided are a sensor node device and method for supporting mobility of a mobile node in a sensor network. The sensor node device includes: a network interface for communicating with a sink node, at least one neighboring sensor node, and the mobile node; a mobility supervisor for detecting a location of the mobile node, and deciding a sensor node for a service of a data packet received through the network interface on the basis of the detected location; a transmission decision maker for deciding a transmission mode for the data packet received through the network interface according to the location of the mobile node; and a state reporter for reporting a transmission state of the data packet through the sensor node device. When the mobile node moves to a place where radio wave propagation areas of sensor nodes overlap each other, the radio wave intensity of each sensor node is detected to perform a handoff to the sensor node of the area having the strongest radio wave intensity. Thus, a ping-pong problem caused by unnecessary repeated handoff, and a delay problem caused by too slow handoff, can be prevented.

A method for measuring a radio wave propagation environment includes installing radio signal transmission and reception apparatuses where a radio network system is to be constructed and obtaining an electromagnetic wave measured value of a signal between transmission and reception apparatuses; estimating an electromagnetic wave propagation state of the signal using an electrical property and information on a three-dimensional structure at the site to obtain an electromagnetic wave estimated value; making a comparison between measured and estimated values for each time of day to determine when errors between measured and estimated values exceed a reference value; obtaining an electromagnetic path between transmission and reception apparatuses; and modifying structure information in the wave path to re-obtain the estimated value; and comparing the measured re-obtained estimated value to modify the three-dimensional structure information so that the error value becomes smaller.

To provide a terminal location estimation method capable of accurately estimating a location of a mobile terminal when providing information services according to the location of the terminal in a radio communication system. A positioning server sends a location measurement probe message to the mobile terminal in order to measure the location of the terminal. Each of base stations receives a response message broadcasted from the terminal, measures the reception level and delay spread and sends the measurement results to the positioning server. The positioning server has a radio wave propagation estimating portion and a database for storing estimation results thereof. The server estimates the location of the terminal by checking the measurement results of the base stations against the estimation results on radio wave propagation stored in the database.

A wireless line control system capable of reducing control signals to wireless nodes with high loads as well as reducing instantaneous interruption or disconnection at user terminals connected to the wireless nodes is provided. In a1 to a3, centralized control node requests reception levels which indicate radio wave propagation states between wireless nodes from each wireless node and acquires the reception levels, and calculates and stores average values thereof. In a4 to a6, the centralized control node requests traffic information from each wireless node and acquires the traffic information, and calculates and stores average values thereof. Based on the averaged historical traffic information and reception levels between wireless nodes, in a7 and a8, the centralized control node determines a configuration of a wireless mesh network which is appropriate from the present to the future, and transmits configuration instructions to each wireless node according to the determined wireless mesh network configuration.

A wireless communication system comprises a base station (4) and terminals (1)-(3). The base station (4) and the terminals (1)-(3) perform a space division multiplex wireless transmission. Each of the base station (4) and the terminals (1)-(3) comprises a multi-beam antenna for a space division multiplex. A beam pattern formed by the multi-beam antenna of the base station (4) is orthogonalized based on transfer function values of a radio-wave-propagation characteristic formed between antenna elements of the multi-beam antenna of the base station (4) and antenna elements of multi-beam antenna of the terminals (1)-(3).

A radio transmitting apparatus that has a plurality of antennas and changes the number of modulated signals transmitted simultaneously according to the propagation environment and so forth. A transmission power changing section 12 of a radio transmitting apparatus of the present invention adjusts the pilot symbol signal level so as to match the data symbol composite signal level according to the number of transmit modulated signals set by a modulated signal number setting section 11. By this means, the operating range of received pilot symbols and the operating range of received data symbols become approximately the same on the receiving side, enabling pilot symbol quantization error to be reduced. As a result, the precision of radio wave propagation environment estimation, time synchronization, and frequency offset estimation using pilot symbols improves, and consequently data reception quality improves.

The invention discloses an air-ground channel modeling method and apparatus. The method comprises the following steps: determining surface terrain feature information affecting air-ground channel transmission in the current environment; obtaining known information of a transmitting end and a receiving end, weather information of the current environment and confidence coefficient information of a channel simulation scene, wherein the known information of the transmitting end and the receiving end comprises: position information of the transmitting end and the receiving end, related indexes of a transmitting and receiving antenna and related features of radio waves; extracting influence parameters affecting air-ground modeling according to the surface terrain feature information, the known information of the transmitting end and the receiving end, the weather information of the current environment and the confidence coefficient information of the channel simulation scene, wherein the influence parameters comprise transmission loss corresponding to a radio wave transmission mode and transmission attenuation corresponding to transmission path shielding; and constructing an air-ground channel model based on the influence parameters. The influence of the surface terrain in the vicinity of the receiving end to the radio wave transmission is considered in the model, thereby improving the validity of the model.

LF antennas are mounted respectively on the corners of a rear bumper of a vehicle. Radio waves radiated from the LF antennas mounted respectively on the corners of the rear bumper are propagated to the both surfaces of the vehicle on the opposite sides of the corner, providing effective transmission ranges. The remaining LF antennas are mounted respectively on the side surfaces of the vehicle such that their effective transmission ranges overlap the effective transmission ranges of the LF antennas mounted respectively on the corners of the rear bumper.

A MIMO decoder, which is capable of changing a search area of a transmission signal vector in accordance with a change in a channel matrix, includes: a generalized inverse vector matrix calculation unit for calculating a generalized inverse matrix of Moore-Penrose derived from a channel matrix indicative of a radiowave propagation environment; a search area limiting processing unit for performing weighting for each eigenvector calculated from the channel matrix in inverse proportion to a square root of an eigenvalue corresponding to the eigenvector, and determines the search area of the transmission signal vector centered at the generalized inverse matrix solution of Moore-Penrose based on the weighted result; and a most likelihood estimation unit for searching for a transmission signal vector by use of a most likelihood estimation based on the search area determined by the search area limiting processing unit.

A wireless communication apparatus and method are provided. The wireless communication apparatus includes: a transmission/reception side location recognizing unit recognizing the location of a transmission side and that of a reception side; a transmission power determining unit recognizing radio wave propagation characteristics according to the locations of the transmission side and the reception side, and determining transmission power in consideration of the radio wave propagation characteristics; a transmission time determining unit analyzing a transmission signal service type and determining a transmission time in consideration of a frequency usage fee if the transmission signal is not required to be transmitted in real time; and a transmission and reception unit transmitting the transmission signal according to the transmission power and the transmission time determined by the transmission power determining unit and the transmission time determining unit.

A nonreflective waveguide terminator includes a waveguide portion and an electromagnetic wave absorber. The portion has a rectangular opening in a plane perpendicular to a radio-wave propagation direction. The portion has one open end in the direction and the other end closed by a terminating metal internal wall. The portion has a radio-wave propagation space surrounded by first and second metal internal walls parallel to a radio-wave electric field, and third and fourth metal internal walls perpendicular to the field. The exterior shape of the absorber is a parallelepiped. The absorber has a rear-end surface positioned at a predetermined distance from the terminating wall and parallel to the terminating wall or is provided against the terminating wall. The surface of the absorber having the largest rectangular area is on the third or the fourth metal internal wall.

A data packet multi-access communicating method and a receiving and transmitting apparatus therefor comprising: receiving a transmission demand from each of a plurality of mobile stations at a base station; determining a maximum transmission rate for each mobile station by taking account of radio wave propagation condition under which each mobile station is presently situated, a data size associated with each transmission demand, a transmission error ratio and a priority order of each mobile station at the base station; and notifying each mobile station of the maximum transmission rate determined at the base station.

A base station communicates with a user device transmitting an uplink signal based on a single-carrier transmission scheme. The base station includes a frequency hopping determining unit configured to determine whether to apply frequency hopping to the user device based on radio-wave propagation information from the user device and a traffic type of data to be transmitted by the user device; a scheduler configured to allocate frequencies to the user device based on uplink channel reception conditions of the user device; and a reporting unit configured to report allocation information indicating resource units allocated by the scheduler to the user device. When the frequency hopping determining unit determines to apply the frequency hopping to the user device, the scheduler allocates, to the user device, resource units with different frequency bands in different slots.

The invention discloses an electromagnetic wave propagation property analysis method and an analysis system. That prediction and analysis are performed on radio wave propagation property in indoor environment can be achieved. Research and analysis can be performed on indoor wireless communication property through initialization modeling of indoor communication environment, establishing of an emission ray tube, intersection test of a ray tube, determination of a reflection ray tube, judgement of a receiving ray tube and calculation of field strength at receiving points based on an shooting andbouncing ray method and a mirror image method (SBR/IM) in a ray tracing method. Through the calculation of the analysis system, a time domain waveform diagram of an emission signal, a received signalpower diagram, a path loss diagram and propagation animation demonstration of electromagnetic waves in the indoor environment can be obtained. The method and system are convenient, fast and economic in operation, have good auxiliary predictive functions for the propagation and distribution of the electromagnetic wave in buildings, and play an important role of the placing and optimization of indoor signal emitters.