At&t Bell Laboratories

At+t Corp.

American Telephone & Telegraph Co., At&t Bell Laboratories

Lucent Technologies Inc.

Massachusetts Institute of Technology

Bell Telephone Laboratories

Digital Equipment Corporation

American Telephone and Telegraph, Co.

W. L. Keefauver, Bell Laboratories

Adel A Saleh

Greg E Blonder

Nicholas J Frigo

Patrick P Iannone

Lee-Fang Wei

Thomas Edward Darcie

Rodney C Alferness

Herwig Werner Kogelnik

Alan Joseph Kirby

Bertrand H Johnson

George Knoedl, Jr

Isam M Habbab

Leonard J Cimini

Donald C Cox

Robert G Gallager

Larry J Greenstein

Vincent W Chan

An improved communication arrangement includes a head station is connected to a router and delivers a signal to the router that is adjusted to the granularity of the free spectral range (FSR) of the router. At a minimum, a signal is broadcast to all outputs of the router, to which network interface units may be connected, with a modulated carrier that spans as little as one FSR interval. Two independent signals are delivered to the network interface units by adding a second carrier that may be as close as at an adjacent FSR interval. In a telecommunication environment, the head station may be a central office-like station which serves a plurality of customers and which provides the expected private communication. Additionally, it provides new broadcast services, such as TV broadcast (much like cable systems currently do) and other multi-media services.

Multiplicity of services via a wavelength division router

Wavelength division multiplexing, spatial switching cross-connect structures which may be deployed as intermediate nodes of an all optical network to route any input channel on any source fiber to any destination fiber at any available wavelength to achieve full connectivity between the nodes of the network. The non-blocking cross-connect structure comprises a wavelength division demultiplexer for receiving multiple wavelength channels from each source fiber and for separating received channels into N wavelengths so that the wavelengths are organized according to a corresponding fiber of origin, a nonblocking optical structure for spatially and independently rearranging the received wavelengths so that wavelengths having a common destination fiber are grouped together, and a wavelength division multiplexer for multiplexing together wavelengths having the same destination fiber.

Non-blocking optical cross-connect structure for telecommunications

A radiotelephone wrist device includes a case having a transceiver and a strap attached to the case for fastening the device to a user's wrist. The strap has a top layer and a bottom layer. The top layer is attached to the bottom layer by a pivot mechanism which facilitates rotating at least a portion of the top layer with respect to the bottom layer. A microphone is located on the strap and electrically connected to the transceiver. A speaker is located at an end of the top layer of the strap and electrically connected to the transceiver. A first antenna is located in the bottom layer of the strap. A second antenna is located in the rotatable portion of the top layer of the strap.

Diversity antenna for a wrist telephone

There is disclosed the architecture for an all optic network which employs a three level hierarchy using wavelength vision multiplexing. At the lowest level of the hierarchy are Level-0 all optical networks. The Level-0 networks are 'local' broadcast networks each of which supports a plurality of access ports and each access port can hear all the local traffic transmitted by all other access ports in the same Level-0 network. Each Level-0 network shares wavelengths internally, but there is extensive reuse of wavelengths among different Level-0 networks. The next higher level, which is the intermediate level, Level-1, is essentially a wavelength router coupled with one or more of the Level-0 networks to provide a wavelength path to one or more directly connect Level-0 networks or, in combination with a Level-2 network, a light path to one or more Level-0 network outside itself. The Level-2 are second level wavelength routing networks which provide light paths, as opposed to wavelength paths, between Level-1 networks. The Level-2 networks may be as simple as fiber trunks alone or they may employ frequency changing devices in addition to wavelength routers and/or spatial switches.

All-optical network architecture

In an optical arrangement for amplifying an input lightwave signal by a predetermined amount to a desired output level, an optical amplifier is connected to a loss element. The optical amplifier is pumped by an amount exceeding a nominal amount wherein the nominal amount is the amount of pumping needed to attain the desired output level at the optical amplifier output. By attenuating the signal output from the optical amplifier, the loss element generates an output signal from the optical arrangement at the desired output level. This optical arrangement is characterized by an improved noise performance (noise figure) over standard optical amplifiers.

Low noise, optical amplifier having post-amplification loss element

In a wireless local area network, predetermined interference-detection sequences of signal points, known at both the transmitter and receiver, are transmitted over a plurality of hopping frequencies along with a sequence of data signal points taken from a modulated code exhibiting built-in diversity. In the receiver, the extent to which there are errors in the received interference-detection signal points is used as a mechanism for identifying the likely occurrence of strong interference. If there are no, or few, errors, decoding proceeds normally. However, if the number of errors is above a predetermined threshold, it is assumed that the transmitted signal was subjected to significant interference and an erasure is declared. This is used as 'side' information by the decoder to improve its ability to accurately recover data in the presence of interference.

Wireless local area network

An optical equalization receiver for countering the effects of delay distortion is realized by utilizing dynamically controllable Fabry-Perot etalon structures. By dynamically adjusting the frequency response of an etalon that is in a feedback loop configuration, the associated delay characteristic of the etalon may be used to counter the effects of delay distortion, thereby allowing higher transmission rates and transmission distances to be achieved. In one exemplary embodiment, an optical receiver comprising a reflective Fabry-Perot etalon and a piezoelectric transducer is used in a feedback loop configuration wherein a feedback control circuit monitors an output signal from the etalon for generating a control signal representing the amount of delay needed to compensate for distortion in an optical signal incident on the etalon. Specifically, the control signal causes a change in the optical path length of the etalon that results in a shift in its frequency response for producing a delay substantially equal and opposite to the associated delay distortion.

Optical equalization receiver for lightwave communication systems

An improved optical amplifier is disclosed with reduced signal-induced, deleterious, nonlinear effects, such as crosstalk, inter-modulation distortion and other saturation-induced effects. The invention comprises an optical amplifier with a compensation loop, such as a feed-forward or a feed-backward loop. This loop provides additional pumping to the gain medium associated with the amplifier, thereby compensating for what would otherwise be deleterious, signal-induced variations in the gain of the optical amplifier.

Optical amplifier with reduced nonlinearity

The present invention relates to a N.times.N single-mode optical coupler employing evanescent wave coupling between mutually adjacent optical waveguides sufficiently close to one another to facilitate coupling among all the waveguides. An optical signal of a narrow frequency band, e.g. appreciably less than 100 gigahertz, introduced to an input port of one of the waveguides is found to be nonuniformly distributed among the output ports of the coupler. A first embodiment uses the nonuniform distributions of narrowband optical signals to the output ports of the coupler to enable the present invention to be used as essentially a selective switching device. A second embodiment introduces one or more predetermined broadband optical signals to one or more input ports of the coupler to produce an appreciably uniform power distribution among the output ports of the coupler. A third embodiment uses electrooptic or magnetooptic waveguides and the application of a high-frequency, continuously changing magnitude, oscillatory electric or magnetic field, respectively, throughout the coupling region of the waveguides to produce a substantially uniform power distribution among the output ports of the coupler for a narrowband optical signal applied to an input port of the coupler.

N.times.N single-mode optical waveguide coupler

A star coupler for a single-mode-fiber optical local area network which reduces the amount of fiber required by a factor of two and diminishes the number of components by one-half. This savings in fiber and components is effected by 'reflecting' signals which appear at various locations of the network back toward the input ports. The arrangement forms a broadcast-type of local area network where a message transmitted by any user can be received by all users.

Passive star coupler

The present invention relates to a technique for achieving cross-polarization interference (CPI) cancellation with or without equalization in a digital-radio, space-diversity communication system. More particularly, a present receiver includes a pair of spaced-apart diversity antennas, where each antenna is capable of receiving orthogonally polarized signals, e.g., Vertical and Horizontal polarizations, from a remote transmitter. The received orthogonally polarized signals from each antenna are separated and coupled to separate inputs of a separate cross-polarization canceler, where each canceler includes two straight-through and two cross-over paths including a separate complex gain multiplier disposed in each path. The correspondingly orthogonally polarized output signals from each of the cancelers are added to produce a first and a second orthogonally polarized overall canceler arrangement output signal. Power measurements are taken of the two overall output signals during predetermined periods of time to produce control signals in a Control and Dither means for appropriately adjusting the complex gain multipliers in each canceler and substantially cancel CPI while providing equalization where desired. Additionally, control signals can also be generated for transmission back to the remote transmitter for appropriately adjusting a canceler therein when CPI cancellation including a second order in frequency is desired.

Techniques for cross-polarization cancellation in a space diversity

The present invention relates to an FET power amplifier whose transfer characteristics are parabolic or have a pronounced parabolic region. The amplifier is capable of linear operation due to a drain electrode bias network which includes a pair of serially connected quarter-wave transmission line sections connected at one end thereof to the drain electrode, and the interconnection point of the two quarter-wave transmission line sections is connected to both (a) a bias supply which causes the FET to operate over at least a portion of the parabolic region and (b) to a means which prevents envelope-induced drain bias voltage variations and presents a short-circuit to the drain terminal at a second harmonic of the input signal.

Linear FET power amplifier

The present invention relates to a linear, class A FET amplifier circuit capable of providing linear amplifier of input signals with a time-varying envelope function. An envelope detector (12) is responsive to an input signal (v.sub.i (t)) for extracting the envelope signal (V.sub.i (t)) therefrom. A gate controller (16) subsequently adds the envelope signal to a predetermined gate bias voltage (E.sub.G) and applies the sum (E.sub.G (t)) as the 'd-c' gate input to the FET amplifier (14). Therefore, the gate bias voltage is dynamically controlled by the envelope of the input signal, resulting in a significant improvement in the power-added efficiency (.eta..sub.added) over prior art class A FET amplifiers.

Dynamic class-4 FET amplifier

The present invention relates to an N-way non-hybrid power combiner arrangement for microwave amplifiers. In operation, sensing means (19.sub.1, 19.sub.2, . . . , 19.sub.N) are coupled in a one-to-one relationship with the individual amplifiers (12.sub.1, 12.sub.2, . . . , 12.sub.N) to monitor amplifier performance and sense amplifier failure. In one embodiment of the present invention, shorting devices (20.sub.1, 20.sub.2, . . . , 20.sub.N) are disposed adjacent to the outputs of the individual amplifiers and coupled to the associated sensing means in a one-to-one relationship. In an alternative embodiment, open-circuiting devices (30.sub.1, 30.sub.2, . . . , 30.sub.N) are disposed at a predetermined distance from the amplifier outputs along the transmission lines (24.sub.1, 24.sub.2, . . . , 24.sub.N) and coupled to their respective sensing means. Upon identifying amplifier failure, the sensing means coupled to that particular amplifier activates either its associated short-circuiting or open-circuiting device, which in turn uncouples the failed amplifier and the transmission line associated therewith.

Power combiner arrangement for microwave amplifiers

The present invention relates to a class of adjustable microstrip and stripline tuners. An exemplary tuner comprises a pair of tuning elements, where each tuning element further comprises a pair of parallel spaced-apart conductive strips of equal length and at least one movable bridging wire connecting the two strips. The movement of the bridging wire will vary the output impedance of the tuning element, and a complementary arrangement of a pair of tuning elements will form a tuner capable of matching any impedance falling within the Smith chart.

Growing community of inventors

Holmdel, NJ, United States of America

Adel A Saleh