International Business Machines Corporation

Fritz R Gfeller

Walter Hirt

Peter Vettiger

Wolfgang H Schott

Pierre R Chevillat

Beat Eugen Weiss

Heinz Jaeckel

Mahmoud Naghshineh

Gian-Luca Bona

David J Webb

Claus Michael Olsen

Parviz Kermani

Peter Dirk Hortensius

Heinz P Meier

Johann R Mueller

Danny N McKay

Babak Rezvani

Patrick K Kam

Hans R Mueller

Armin U Blacha

Peter L Heinzmann

Daniel Wild

Urs H Bapst

Heinz Richard

Brian Richard Ingham

Hirt Walter

Oliver Martin

Martin De Lange

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 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 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

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 and a method for improved connectivity in wireless optical networks. Therefore at least two or more receiving units are used which receive an infrared signal and convert it to a digital signal. The digital signals represent data in the form of frames whereby each frame comprises at least a data field and a header field containing a preamble. A selector determines a measure related to the signal-to-noise ratio of the preamble and compares the measures in order to select the best suited signal for further processing.

Apparatus and method for improved connectivity in wireless optical communication systems

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

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

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

Disclosed are optical transmitter and transceiver modules for data communication. Such a transceiver module comprises an array of light emitting diodes mounted on a mounting base ( ) being arranged in a regular and symmetrical manner in a dome-shaped housing ( ). This housing ( ) comprises diffusor means for source enlargement. In addition to the transmitter part consisting of said diodes, the transceiver module comprises a receiver. The receiver has four photodiodes ( ) arranged below the mounting base ( ). These photodiodes are tilted and face in different directions to receive light from all around the module. The photodiodes are protected by a thin wire mesh ( ) which serves as Faraday cage to reduce electro magnetic interference. A substrate ( ) for electronic circuitry in SMD-Technology is situated underneath the photodiodes ( ).

Optical transmitter and transceiver module for wireless data transmission

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

In a wireless multi-rate communications system, a method for extending the range of communications in the system by dividing the physical layer frame into two portions: a robust header portion and a body, where the repetition rate of the data symbols in the header portion is greater than or equal to the repetition rate of the data symbols in the body of the frame. In this way the header can be received and decoded by all stations in the system with a high probability, while the body of the frame need only be received and decoded by the destination station to which the body of the frame is intended to be received and decoded.

Media access control protocols in a wireless communication network

Wireless optical communication system with adaptive data rates and/or

A semiconductor laser diode comprises a waveguide formed by an active layer sandwiched in between upper and lower cladding layers, wherein the cladding layers comprise a material having a bandgap that differs from that of the active layer. The waveguide is deposited on a structured substrate having a surface pattern that causes the waveguide to be bent near its ends, i.e., near cleaved or etched facets of the completed laser device thereby providing a non-absorbing mirror (NAM) window structure. A laser beam, generated in the center, planar waveguide section, leaves the waveguide at the bend, continuing substantially unabsorbed and undeflected through the wider bandgap cladding layer material towards the mirror facet. An amphoteric dopant, used during growth of the layered waveguide structure, causes a reversal of the conductivity-type within the semiconductor material deposited above inclined surface regions. Thus, a junction serving as current block is formed preventing lateral currents from reaching the facet region.

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Adliswil, Switzerland

Fritz R Gfeller