Abstract:
A method for analog to digital conversion (ADC) characterised by; applying a non-linear transfer function to an input signal, such that the relation between the quantisation levels of the converter and the input signal vary as a non-linear function of the magnitude of the input signal. The non-linear transfer function is related to an at least approximate measurement of probability density function ‘p(x)’ of said input signal so that larger quantisation bins of the converter correspond to less probable values of the input signal.The relation is iteratively updated by updating quantisation levels.
Abstract:
A detector or a modulator for converting between optical and radio frequency signals comprising an optical guide (11 to 14) for propagating two optical signal components having frequencies that differ by an amount corresponding to a radio frequency and a microstrip radio signal guide (15, 16) for propagating a radio signal at the radio frequency, the microstrip radio signal guide being in travelling-wave coupling with an interaction one (14) of the optical guide comprising material in which interaction between the optical signal components and the radio signal occur. The microstrip radio signal guide element (15, 16) comprises an electrically conductive strip (15) juxtaposed with and extending along the interaction zone (14) on one side thereof and an electrically conductive ground plane (16) juxtaposed with and extending along the interaction zone (14) on an opposite side thereof. Transition radio signal guide elements (20,21) in the form of Vivaldi antennas extending transversely to the microstrip (15) connect the microstrip radio signal guide element (15,16) with a rectangular section wave-guide (18) and a matched load. Each of the transition radio signal guide elements (20, 21) comprises an opening of progressively varying width formed in the electrically conductive ground plane of the microstrip guide (16). Radio frequency signal resonators (24 to 27) extend the ends of the microstrip (15) and the small ends of the Vivaldi antennae.
Abstract:
A Multiple In Multiple Out (MIMO) communication system comprises an air interface scheduler for allocating air interface resource to a plurality of user equipments transmitting to a MIMO receiver. A vector processor of the scheduler determines a receive equalizer vector for the MIMO receiver for each of a plurality of user equipments in response to a channel matrix for the user equipment. The vector processor may specifically apply singular value decomposition to the channel matrix to determine the receive equalizer vector. An orthogonality processor then determines orthogonality measures between receive equalizer vectors for different sets of user equipments. A selection processor selects a set of user equipments to be allocated a shared MIMO air interface resource in response to the orthogonality measures. By scheduling in response to orthogonality of receiver operations, a reduced interference and/or reduced receiver complexity can be achieved.
Abstract:
A wireless transmitter includes a stream parser for generating a plurality of spatial streams from a digital signal and a space time block coder (STBC) for mapping each of the spatial streams to a plurality of space-time streams that each include data and a preamble for estimating a channel transfer function. The transmitter also includes a spatial mapper for spatially expanding each of the space-time streams by applying a spatial expansion matrix to data and to first training symbols used in the preamble to probe a channel experienced by the data and by applying an extension matrix to second training symbols used in the preamble to probe at least one additional dimension of the channel to enable use of beamforming to achieve range extension The spatial expansion matrix and the extension matrix form an overall matrix that has at least two orthogonal columns with different norms. The wireless transmitter also includes an analog front end for modulating the spatially expanded space-time streams onto a wireless carrier.
Abstract:
An optical to radio frequency detector comprising an optical guide (11 to 14) for receiving two optical signal components having frequencies that differ by an amount corresponding to a radio frequency, and a radio signal guide (15, 16) coupled with an interaction zone (14) of the optical guide for propagating a radio signal from the interaction zone at the radio frequency. the interaction zone (14) of the optical guide comprises an interaction material presenting a second-order non-linear optical polarisation characteristic to the propagatio of the optical signal components, and the radio signal guide (15,16) is in travelling-wave coupling with the interaction zone. the interaction material includes electrically orientated diazobenzene. The radio signal guide (15,16) comprises an electrically conductive strip (15) juxtaposed with and extending along the interaction zone (14) on one side thereof and an electrically conductive ground plane (16) juxtaposed with and extending along the interaction zone (14) on an opposite side thereof.
Abstract:
The card (40) is a plate in the form of a bank card which is provided with a power source, a microcontroller (144), a personal data memory (254), an acquired data memory (256), and a data-in-transit memory (212). Each card possesses two coupling members, i.e. a transmitter and a receiver on each of its faces, together with two manual activators (42-52) adapted to put it into operation. An operation of interchanging data between a plurality of cards (40.1, . . . , 40.4) comprises an initial step of checking feasibility in which a down stage during which the personal data in each card is accumulated (arrows 41.1, 41.2, 41.3) in the data-in-transit memories (212) of the cards disposed there beneath, and the other stage being an up stage symmetrical to the preceding stage. The end of this second stage triggers a down procedure in which the acquired data memories (256) are loaded. The last card in the stack issues an audible signal (58) to indicate that the operation has finished successfully. The card may be inserted in the appliance for making use thereof which is itself connectable to an external microcomputer, in order to display or process the acquired data, to modify the stored personal data, to enable or disable interchange thereof, or to apply a particular applications program thereto. Applications include intelligent calling cards and multipurpose cards.