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1077 results about "Received signal strength indication" patented technology

In telecommunications, received signal strength indicator (RSSI) is a measurement of the power present in a received radio signal. RSSI is usually invisible to a user of a receiving device. However, because signal strength can vary greatly and affect functionality in wireless networking, IEEE 802.11 devices often make the measurement available to users.

Transceiver control with sleep mode operation

A transceiver which keeps circuitry associated with a receiver in a powered down state during periods when a Received Signal Strength Indicator (RSSI) indicates that a signal being received is below a pre-determined threshold level, and which begins to power up the transmitter as soon as it is determined that a packet being received requires a response. The RSSI signal represents the strength of any signal current being received, and if the RSSI signal falls below a given threshold level, digital circuitry associated with the back-end circuitry of the receiver system is disabled. If the RSSI signal rises above the threshold level, the digital circuitry of the receiver is enabled. A control circuit within the transceiver processes the packet as it is received to determine whether the packet requires a response. If it is determined that a response is necessary, the control circuit provides a control signal to the transmitter to power up the transmitter from a sleep mode even before the entire packet has been received and processed. The control circuit then continues to process the remainder of the packet as it is received while the transmitter powers up from the sleep mode. In this manner, the transmitter will become stabilized much earlier. Accordingly, the transceiver is able to respond more quickly than conventional devices and is thus able to increase response times and overall data exchange rates. Moreover, battery power of the transceiver is utilized more efficiently compared to devices which must continuously maintain the receiver and transmitter in fully powered modes.
Owner:TELXON INC

System and method for ensuring handoffs across heterogeneous networks

This invention provides a system, method and apparatus for facilitating handoffs from a first communication network to a second communication network, the first communication network and second communication network being heterogeneous with respect to each other. The system, method and apparatus may further include a contextual information server, which stores contextual elements corresponding to a user device and the operating environment of the user device, and a handoff decision function module that evaluates at least one of the contextual elements to determine whether to handoff user device communications from the first communication network to the second communication network. The method and apparatus may further include obtaining at least one contextual element corresponding to a user device and the operating environment of the user device, evaluating the at least one contextual element with a handoff decision function module to establish a handoff decision, establishing a handoff decision, and notifying the user device of the handoff decision. The method for facilitating handoffs from a first communication network to a second communication network may further include receiving a received signal strength indication, receiving a link quality determination, receiving a characteristic of the user device, and determining the location of the user device.
Owner:APPLE INC

Apparatus and method for searching a base station in an asynchronous mobile communications system

Disclosed is an apparatus and method for searching a base station in a mobile communications system, in which a mobile station acquires slot timing synchronization from a first signal on a primary sync channel (P-SCH) out of the P-SCH and a secondary sync channel (S-SCH) used for base station search, acquires frame timing synchronization (Fsync) from a second signal on the S-SCH, and determines a primary scrambling code group (PSCG) corresponding to the scrambling codes used by the respective base stations. The method comprises calculating and accumulating P-SCH RSSI values from the first signal at every slot and comparing the accumulated P-SCH RSSI values with first and second accumulation thresholds and providing the first and second search commands; and calculating S-SCH channel received signal strength indicator (RSSI) values from the second signal at every slot in one frame, and updating S-SCH RSSI values corresponding to the one frame as energy matrix values; calculating energy hypotheses corresponding to the energy matrix values using the energy matrix values and a predetermined secondary sync code (SSC) table in response to a first search command, and determining energy hypotheses having a value higher than a predetermined threshold as passed hypotheses; and calculating energy values for the passed hypotheses using the determined passed hypotheses and the SSC table in response to a second search command, and determining an energy hypothesis having a maximum energy as the Fsync and the PSCG.
Owner:SAMSUNG ELECTRONICS CO LTD

Centroid location algorithm based on RSSI (Received Signal Strength Indication) correction for wireless sensor network

The invention discloses a centroid location algorithm based on RSSI (Received Signal Strength Indication) correction for a wireless sensor network, and the centroid location algorithm comprises: (1) anchor nodes periodically broadcast information around, wherein the information contains respective node ID (identity) and coordinates; and ordinary nodes average the RSSI of the same anchor node after receiving the information; (2) the ordinary nodes do not receive new information any more after collecting the information of n anchor nodes, wherein n is greater than 3 and less than or equal to 100; the ordinary nodes sort the anchor nodes according to the RSSI from strong to weak and establish mapping of the RSSI value and the distance from the nodes to the anchor nodes; (3) the anchor nodes with the RSSI value greater than or equal to minus 93dbm and less than or equal to minus 113dbm is selected for self-location calculation; and (4) the calculated unknown node coordinate set is aggregated and averaged to obtain the unknown node coordinates. In the invention, the point-to-point distance between the nodes is measured by correcting an RSSI ranging technology, and a triangle centroid location algorithm is adopted for location, thus the measurement error of the RSSI is reduced. Compared with the triangle centroid location algorithm based on the RSSI, the centroid location algorithm provided by the invention has the advantage that the location accuracy is greatly improved.
Owner:SHANDONG UNIV

Radio frequency fingerprint positioning method and system as well as access controller (AC) and positioning server

ActiveCN102056293AAchieve positioningGuaranteed minimum requirementsWireless communicationFeature vectorWireless control
The invention provides a radio frequency fingerprint positioning method and system as well as an access controller (AC) and a positioning server. The method comprises the following steps: the positioning server sends a first positioning indication message which contains an identifier of the appointed equipment to an access point (AP) through the AC, so the AP can collect the received signal strength indication (RSSI) of the appointed equipment; the AC receives the RSSI of the appointed equipment fed back from the AP, filters the RSSI of the appointed equipment according to a preset dimensional threshold value and an RSSI threshold value to generate a fingerprint feature vector at least containing the preset dimensional threshold value number of the RSSI, and sends the fingerprint feature vector to the positioning server; and the positioning server positions the appointed equipment according to the fingerprint feature vector and a preserved standard fingerprint feature vector containing at least the preset dimensional threshold value number of the RSSI and position coordinates. By utilizing the technical scheme of the invention, the complexity of positioning by using a radio frequency fingerprint technique can be decreased, and the positioning precision can be increased.
Owner:BEIJING XINWANG RUIJIE NETWORK TECH CO LTD

Indoor positioning method for goal nodes of mobile social network

The invention discloses an indoor positioning method for goal nodes of a mobile social network. The indoor positioning method comprises the following steps of: respectively placing at least three access points AP in different positions, using known coordinate points as anchor nodes, obtaining a relational model between signal strengths and distances of all the anchor points, obtaining the signal strength value of each signal by using a mobile smart terminal, selecting the anchor nodes with the strongest signal strengths as the nodes needing to particle in positioning, respectively putting the three anchor nodes into the relational model between the RSSI (Received Signal Strength Indication) and the distances of the corresponding anchor nodes, and working out the distances from the mobile smart terminal to the corresponding anchor nodes; and working out the position coordinates of the mobile smart terminal by using an angular positioning algorithm. According to the indoor positioning method, the positioning of mobile nodes can be realized in a mobile social network environment, the impact of the environment on positioning is overcome to a certain extend, thereby the positioning accuracy is improved, and the positioning requirement can be basically satisfied in the mobile social network environment.
Owner:NORTHWESTERN POLYTECHNICAL UNIV
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