International Business Machines Corporation

Lenovo (singapore) Pte. Ltd.

Walter Hirt

Fritz R Gfeller

Richard Leo Galbraith

Jonathan Darrel Coker

Evangelos Stavros Eleftheriou

Martin Aureliano Hassner

Nyles Heise

Hendrik F Hamann

Mircea R Gusat

Barry Marshall Trager

Reto Josef Hermann

Wolfgang H Schott

Francois Bernard Dolivo

David James Stanek

Kevin Roy Vannorsdel

Beat Eugen Weiss

Yasuo Amemiya

Martin De Lange

Maria Soimu

Jing Shen

Ying Hung

Mark D Warne

Fritz Rudolf Gfeller

Martin Weisenhorn

Techniques for monitoring and predicting environmental operating conditions in a data center are provided. In one aspect, a method for real-time, three-dimensional analysis of environmental operating conditions in a data center includes the following steps. High spatial resolution three-dimensional measurements of one or more environmental variables in the data center made at a time tare obtained. Real-time measurements of the environmental variables in the data center made at a time t, wherein tis later in time than t, are obtained. The high spatial resolution three-dimensional measurements are combined with the real-time measurements to derive a model for the environmental variables in the data center at the time t. The model is used to predict three-dimensional distributions of the environmental variables in the data center at the time t. A base model can be created and used to derive the model for the data center at the time t.

Techniques to predict three-dimensional thermal distributions in real-time

The present invention is related to an apparatus and method for determining the location of a communication device within a wireless network in order to provide a geolocation functionality to the communication device participating under an access protocol of a wireless local-area network (WLAN) infrastructure such as IEEE 802.11 or Hiperlan. The apparatus comprises at least two transponder units for communicating with the communication device when the communication device is situated in a coverage area of the wireless network and a processing unit for deriving the location of the communication device within the coverage area in dependence on information received from the transponder units.

Transponder subsystem for supporting location awareness in wireless networks

The present invention relates to a method and system for displaying a video signal in dependence on a user interaction. The system comprises a display for receiving the video signal, at least one transmitter for transmitting location signals, and at least three transceivers for receiving the location signals from the transmitter and for transmitting modified location signals. The geometric locations of the at least three transceivers are known to a computing device. The computing device is then able to derive a transmit location of the location signals based on the received modified location signals, wherein the computing device is adapted to modify the content of the video signal in response to the derived transmit location in dependence on the user interaction.

Method and system for user-aware video display

The invention relates to a conversion of a pulse modulated signal to a radio frequency signal enabling use of applications and protocols designed for wireless optical links on radio frequency channels. The method comprises receiving the pulse modulated input signal, decoding the received pulse modulated input signal into a decoded data bit-stream, encoding the decoded data bit-stream into a recoded data bit-stream, under use of the recoded data bit-stream modulating a radio frequency signal, and transmitting the modulated radio frequency signal. In the receiver path a received radio frequency signal is converted to a pulse modulated output signal by the steps of demodulating the received radio frequency signal into a demodulated data bit-stream, decoding the demodulated data bit-stream into a received data bit-stream, encoding the received data bit-stream into a pulse modulated output signal, and forwarding the pulse modulated output signal.

Method and apparatus for converting optical signals to radio channels

The present invention is related to an apparatus and method for determining the location of a communication device within a wireless network in order to provide a geolocation functionality to the communication device participating under an access protocol of a wireless local-area network (WLAN) infrastructure such as IEEE 0.802.11 or Hiperlan. The apparatus comprises at least two transponder units for communicating with the communication device when the communication device is situated in a coverage area of the wireless network and a processing unit for deriving the location of the communication device within the coverage area in dependence on information received from the transponder units.

An apparatus and method for determining the quality of a digital signal. The incoming digital signal is sampled with a number n of samples per defined pulse width, where N is greater than or equal to one, using clock cycles. An edge detector detects the edge position of a pulse of the sampled digital signal and a counter counts the clock cycles between at least a first edge and a second edge detected by the edge detector. A deviation detector then compares the counted clock cycles with a prestored reference-value in order to provide a deviation value as a measure for the instantaneous quality of the digital signal. The deviation value is then fed to a rework unit that outputs a value that is a measure for the quality of the digital signal.

Apparatus and method for determining the quality of a digital signal

The present invention provides an apparatus and a method for determining a pulse position for a signal encoded by a pulse modulation. The signal being receivable as at least a first component (PCS) and a second component (DCS). A first storage unit () stores at least one symbol of the first component (PCS) and a second storage unit () at least one symbol of the second component (DCS). A determination unit () comprises a probability table (), which in case that the first and second components (PCS, DCS) are received is addressed with the at least one symbol of the first component (PCS) and the at least one symbol of the second component (DCS). Thereby, the probability table () provides a value that is defined as the pulse position (DDS).

Apparatus and method for determining a pulse position for a signal encoded by a pulse modulation

The present invention provides an apparatus, method, and system for determining a time of arrival (TOA) and time differences of arrival (TDOA) of a transmitted signal &lcub;S&rcub; receivable at different locations of known spatial coordinates. The system comprises a first transmitter with a respective antenna feed point positioned at an a priori unknown location P and emitting a first signal &lcub;S&rcub;. The system includes furthermore a set of transceivers or transponder units comprising first receivers for receiving first signals &lcub;S&rcub; by means of respective antennas with feed points located at known locations L . Such system also comprises second transmitters emitting respective derived second signals &lcub;{tilde over (S)} &rcub; after known and scheduled respective time intervals &dgr; as measurable between the feed points of said respective first receiving antennas located at known locations L and respective second transmitting antenna located at locations L&prime; . A set of second receivers receives respective second signals &lcub;{tilde over (S)} &rcub; after known respective time intervals &tgr; measured between the feed points of the second transmitting antennas and feed points of second receiving antennas. A controller terminates the measurement cycle for each first transmitter to define total signal transfer times and then sends to a processing unit an ensemble of derived third signals &lcub;&Scirc; &rcub;, after some known respective delay times &Dgr;T . Said delay times &Dgr;T are measured between the time one third signal &lcub;&Scirc;&rcub; passes the feed point of the respective second receiving antenna and the time instant where the respective single time reference T issued by the controller terminates the measurement cycle. The set of third signals &lcub;&Scirc; &rcub; received by the processing unit contains sufficient information for determining the time of arrival (TOA) and time differences of arrival (TDOA) and to compute {circumflex over (P)}, an estimate of the a priori unknown location P of a mobile radio terminal or radio tag emitting the first signal &lcub;S&rcub;.

Determining a time of arrival of a sent signal

Method for wireless optical communication between a transmitting station and a receiving station, whereby the transmitting station provides a Request-to-Send (RTS) frame to the receiving station to announce the transmission of a data frame, the receiving station provides a Clear-to-Send (CTS) frame to the transmitting station in case of correct reception of the RTS frame, and the transmitting station subsequently sends the data frame to the receiving station. The RTS frame comprises Preamble (PA), Synchronization (SYNC), and Robust Header (RH) fields. The RTS frame further comprises a Source Address/Destination Address field (SA/DA) and a Cyclic Redundancy Check field (CRC). Adjusting the power level of the RTS frame to be different from the nominal transmission power level at which the data frame is sent, and by variable repetition coding within the Robust Header (RH) field of the RTS frame, allows a larger dynamic range of link quality estimation and improved collision avoidance properties. Depending on the chosen power level which can be higher or lower than the nominal transmission power level of the data transmission and a repetition coding depending on the chosen power level, a number of different possibilities to improve the connection between the participating stations are proposed and claimed.

Method for improved wireless optical communication and frames for use in a wireless optical communication system

In a maximum likelihood sequence detector for symbol sequences which were equalized in a PR4 equalizer, noise prediction means ( ) are provided including infinite impulse response (IIR) filtering, which have noise-whitening capabilities and are imbedded into the maximum likelihood detection process. The resulting INPML detector ( ) can be implemented in digital or analog circuit technology. In addition, a DC-notch filter ( ) and a stochastic gradient procedure can be provided for DC offset compensation and for MR head or signal asymmetry compensation.

Apparatus and method for noise-predictive maximum likelihood detection

Disclosed is an optical communication system enabling communication between several co-existing transmitting and receiving stations. In order to allow communication between the co-existing stations, a robust physical layer header (RPLH; ) is employed which can be understood by all participating stations. This robust header ( ) at least comprises a preamble ( ) consisting of frames forming a periodic sequence of pulses, the number of slots per frame and the frame content being known to all participating stations. The preamble ( ) serves for relative synchronization and carrier detection of the receiving stations. The robust header ( ) further comprises a unique synchronization word ( ) used for absolute synchronization of the receiving stations. This synchronization word ( ) is followed by a control field ( ) of fixed length and known structure. By means of this control field ( ) the receiving stations are informed which modulation method will be used for the transmission of data. Under certain circumstances it is also useful to provide other control information in said control field ( ) for communication link and network control. Furthermore, information may be exchanged to allow negotiation and/or adaptation of the data rate used for transmission. This allows to optimize the throughput depending on the conditions (quality) on the channel.

Robust method and apparatus enabling multi-mode wireless optical communication

The invention involves an optical wireless communication system comprising a transmitter and a receiver wherein the transmitter has a three-dimensional optical emission characteristic and the receiver has a three-dimensional optical reception characteristic. According to the present invention, the shape of the optical emission characteristic matches the shape of the optical reception characteristic at least within one two-dimensional plane.

Optoelectronic transceiver having emission angle equal to reception angle

A packet-frame generator for creating an encoded packet frame comprising encoded control data and encoded utilizable data. A non-encoded packet frame comprising non-encoded control data and non-encoded utilizable data is providable by an assembling means. The packet-frame generator comprises a modulation encoder for encoding the non-encoded control data by a first modulation code and the non-encoded utilizable data by a second modulation code thereby providing the encoded packet frame.

Packet-frame generator for creating an encoded packet frame and method thereof

A method and means for reducing high-duty-cycle unconstrained binary signal sequences in storage and communications processes and systems by invertibly mapping such sequences into a (1, k) rate &frac23; RLL codestream constrained to a duty cycle substantially approximating one-third. That is, binary sequences ordinarily mapping into high-duty-cycle RLL-code sequences are either inhibited from repeating indefinitely or excluded.

Method and means for invertibly mapping binary sequences into rate 2/3 (1,K) run-length-limited coded sequences with maximum transition density constraints

The invention is family of noise predictive maximum liklihood (NPML) symbol detectors that are particularly useful in direct access storage devices. Various embodiments representative of the family of detectors are described. In general, the NPML detectors include a sequence detector with imbedded feedback which may be preceded by a filter, e.g., a prediction error filter. The sequence of detectors, which may be Viterbi detectors, have an imbedded filter whose coefficients are determined by the convolution of the partial response (PR) or generalized PR function with the predictor coefficients and do not require multiplications and, thus, allows a simple RAM look-up for intersymbol-interference ISI cancelation. In one class of embodiments, the NPML detector comprises a prediction error filter of length N, cascaded with a sequence detector having 2.sup.K states, and a feedback filter imbedded in the sequence detector, having a length N+P-K, where P is length of the generalized PR shaping polynomial (P=2 yields PR4), and 0.ltoreq.K.ltoreq.N+P.

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Wettswil, Switzerland

Walter Hirt