International Business Machines Corporation

Wolfgang H Schott

Simeon Furrer

Pedro E Coronel

Francois Bernard Dolivo

Beat Eugen Weiss

Fritz R Gfeller

Pierre R Chevillat

Dietrich G Maiwald

Roy Daron Cideciyan

Richard Leo Galbraith

Jens Jelitto

Sedat Oelcer

Jonathan Darrel Coker

Pablo A Ziperovich

Walter Hirt

Andrea Munari

Marcel Rupf

Andreas Rungeler

Techniques for routing data from a source to a destination in a wireless network are provided. The techniques include broadcasting one or more messages in a network to identify a set of one or more nodes that can be used to forward data towards a destination, routing data from a source to the destination by way of a sequence of one or more data transmissions involving the one or more identified nodes, wherein each data transmission comprises a node that has data addressed to the destination to trigger a distributed procedure among the one or more identified nodes to select a relaying node, and sending the data to the selected relaying node until the destination is reached.

Method for dynamic routing using tunneling

Packets are periodically transmitted by a plurality of radio beacons deployed at known positions over a location estimation area. Monitoring is conducted for incoming packets. Upon receipt of a packet from a kone of the beacons, received signal strength, RSSI, is measured at each of the antenna outputs, the packet is decoded to obtain the unique identifier and the unique sequence number, and the received signal strength at each of the antenna outputs is spatially averaged. The measuring, decoding, and spatial averaging are repeated for additional packets from the kone of the beacons during a pre-defined time window T. The plurality of spatially averaged received signal strengths are temporally averaged over the pre-defined time window T, to obtain a spatially and temporally averaged value of received signal strength. The distance dfrom the apparatus to the kone of the beacons is approximated based on the spatially and temporally averaged value of received signal strength. The approximate distance dis designated as {circumflex over (d)}. This is repeated for the K beacons that have successfully transmitted packet(s) during the pre-defined time window, k=1 to K. The location of the object is estimated as an approximate intersection of spheres with radii {circumflex over (d)}. Each sphere is centered at the known position of the kone of the beacons.

Estimating location using multi-antenna radio receiver

A wireless sensor network includes a controller connected with multiple antennas for sending out a beacon signal at different instants into different directions and for receiving a sensor signal. Furthermore, the wireless sensor network comprises a sensor having a receiver connected with a sensor antenna for receiving the beacon signal, a transmitter connected with the sensor antenna for sending out the sensor signal, and a control unit which takes care that the sensor signal is transmitted after the beacon signal has been received.

Signal transmission between a sensor and a controller device in a wireless sensor network

Communication device for processing outgoing and incoming packets. The device includes a plurality of signal processing units connected in sequence, each signal processing unit being clocked by a common clock signal. The device further includes a mode line connected to each signal processing unit for switching each signal processing unit between a transmit mode and a receive mode. The device further includes a control line to which each signal processing unit is connected. The control line communicating flow control information either in the transmit mode to at least one of the preceding signal processing units or in the receive mode to at least one of the following signal processing units.

Digital baseband system

System and program product for signal transmission between a sensor and a controller in a wireless sensor network

An apparatus and method is disclosed for efficiently sensing and tracking objects in an indoor environment by simultaneously measuring the object movement with an inertial navigation system and a reference location positioning system. By combining the measurements obtained with accelerometers, gyroscopes, angle estimators and the reference system using an extended Kalman filter based approach, a position estimate is obtained with high reliability and precision accuracy. Improvement in performance is obtained by the incorporation of dynamic mode switching and forward-backward smoothing in the location position estimator.

Apparatus and method for measuring the accurate position of moving objects in an indoor environment

Provides: methods for transmission of signals between a sensor and a controller in a wireless sensor network; methods for operating the controller in the wireless sensor network; and methods for transmitting a sensor signal in the wireless sensor network from the sensor to the controller. A wireless sensor network includes a controller connected with multiple antennas for sending out a beacon signal at different instants into different directions and for receiving a sensor signal. Furthermore, the wireless sensor network comprises a sensor having a receiver connected with a sensor antenna for receiving the beacon signal, a transmitter connected with the sensor antenna for sending out the sensor signal, and a control unit which takes care that the sensor signal is transmitted after the beacon signal has been received.

Transmission between a sensor and a controller in a wireless sensor network

The present invention discloses a method and apparatus for adjusting gain setting, receiver clock frequency, and symbol timing in an OFDM radio receiver. The method is based on the reception of a preamble with known periodic training sequences transmitted prior to user data over the radio channel. By computing a periodicity metric, an inner receiver detects the presence of periodic signals in the received data sequence, provides means to set the Variable Gain Amplifier VGA gain in the radio frontend, and estimates frequency offsets between the transmit and receive clock. Matched filters are used to determine the symbol timing. A finite-state-machine schedules various tasks during the receiver startup.

Acquisition and adjustment of gain, receiver clock frequency, and symbol timing in an OFDM radio receiver

An apparatus and method for setting a transfer rate of information units in a variable data-rate transmission scheme for a wireless communication system is disclosed. For that, a total counter for counting a total number of received information units, an error counter for counting an error number of received invalid information units, a division unit for dividing the error number by the total number, and a decision unit for setting a transmission-rate parameter are utilizable. The division result is providable as a link-quality measure at an output of the division unit. This link-quality measure is comparable with at least one predefined value depending on the result of which, the transmission-rate parameter is setable.

Apparatus and method for setting a data rate in a wireless communication system

The present invention provides apparatus and methods for determining a propagation time of a signal transmitted from a first location to a second location as a request signal and received as a response signal by the first location via a channel. In an example embodiment, a method comprises the step of determining the propagation time of the signal based on a local counter value that represents the time between transmission of the request signal and reception of the response signal, a remote counter value that depends on the request signal and being known to the first location, and a determinable time-delay value. The remote counter value represents an inter-time-delay between the reception of the request signal and the start of transmission of the response signal at the second location.

Geolocation subsystem

Packet data transmission in code-division multiple access communication systems

A method and apparatus for detection of a timing data sequence and an end-of-preamble (EOP) flag based on a maximum-likelihood (ML) test performed on received data timing samples after synchronization has been achieved is described. The preamble preceding transmitted user data consists of a timing sequence followed by a known sequence of bits marking its end. After detection of synchronization, the receipt of the timing data sequence is recognized when an ML test detects no more than n.sub.V violations during a sequence of n.sub.l received samples. Similarly, the receipt of the EOP flag is recognized as soon as n.sub.F violations an ML test have occurred in the received sample sequence after recognition of the timing data sequence.

Preamble recognition and synchronization detection in partial-response

A method and apparatus are provided for controlling a digital filter function included in a data path within gain and timing control loops of a PRML magnetic recording channel. The digital filter function is removed from the data path during an acquisition mode and the digital filter function is restored to the data path during a tracking mode. A predetermined gain and a quantized delay at a synchronization frequency are provided when switching from acquisition mode to tracking mode. A unity gain and a delay of an integer number of sample periods are provided at a synchronization frequency when switching from acquisition mode to tracking mode.

Method and apparatus for digital filter control in a partial-response

The channel characteristics of magnetic-disk storage devices vary with track radius. An adaptive three-tap transversal equalizer that compensates these variations for systems using partial-response signaling is presented. The equalizer coefficients are updated by applying a procedure that is related to the recursive least-squares algorithm. This new updating procedure does not require multiplications and is well suited for high-speed implementation. Results obtained by computer simulations and measurements with a prototype have shown that the proposed adaptive equalizer can effectively compensate variations in magnetic-disk channel characteristics with track radius.

Adaptive equalization for recording systems using partial-response

In the readback apparatus of magnetic recording system operating in accordance with the partial-response maximum-likelihood (PRML) technique, a variable-gain amplifier (VGA) and a maximum-likelihood sequence detector (ML DET) plus a gain control loop are provided. The detector (19) is designed to operate on input signals (y') having nominal discrete signal amplitudes (a, 0, -a) and it furnishes discrete output signals (y) having such nominal signal amplitudes. The gain control loop is responsive to input (27) and output (29) signals of the detector, and it has charge-pump circuitry (37, 39, 41, 43) for generating a gain control signal (V.sub.c =V.sub.g) for the variable gain amplifier (35). To enable proper operation of the system even in case of short-time signal amplitude drops due to media defects, biasing means (49) are provided such that the gain (g) is adjusted to a value which causes the signal amplitudes at the input (27) of the detector to be weighted multiples (ca, 0, -ca) of the nominal amplitude values (a, 0, -a).

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Rueschlikon, Switzerland

Wolfgang H Schott