Abstract: Wireless communications for frequency-selective fading channels is realized by employing a system including orthogonal frequency division multiplexing (OFDM) in combination with an at least two antenna transmit diversity arrangement. Specifically, OFDM converts a multipath channel into a plurality of narrowband subchannels each having flat fading. Then, the signals on the same frequency subchannels of the at least two antennas are grouped together. Considering a first frequency subchannel, during a first OFDM time interval, a first signal and a second signal are transmitted on the first frequency subchannel from a first antenna (0) and from a second antenna (1), respectively. During a second OFDM time interval, a reverse sign (?) complex conjugate of the second signal and a complex conjugate of the first signal are transmitted from the first antenna and the second antenna, respectively.

Abstract: A differential FM detection of signals uses in-phase and quadrature phase signal components of a received signal in the detection process, wherein the in-phase and quadrature phase signal components are at a low intermediate frequency (IF). The in-phase and quadrature phase signal components are each amplitude limited, sampled at a prescribed sampling rate and filtered in a prescribed manner. Delayed versions of the filtered in-phase and quadrature phase signal components are generated and, then, signal products are generated of the delayed in-phase signal component and quadrature phase signal component, and the delayed quadrature phase signal component and in-phase signal component. The algebraic difference of the generated signal products is obtained to yield the desired data signal, e.g., symbols.

Abstract: Interactive services are provided by employing a modular approach to implementing interactive services with multiple interfaces. Such an approach facilitates supporting natural language understanding interaction with users through use of interfaces that allow at least different ordering of inputs, and/or incomplete information, and/or correction of information, and/or the return of control to prior points in the service. This is realized, in an embodiment of the invention, by employing a single interactive service logic that uses “reactive constraint graphs”, i.e., a form of event-driven graph, in which nodes contain a set of constraints on events. Specifically, control progresses from a node to a derivative node, i.e., “child”, only when all the constraints in the set on the node have been satisfied. A single set of constraints implicitly supports a significant number of the possible different orderings of inputs.

Abstract: A multilevel coded modulation scheme is provided in which a first portion of input data is encoded by a first-level code and a second portion of input data is encoded by an second-level code, the second-level code being such that the overall multilevel code exhibits a desired level of time diversity of at least 2 and the minimum distance of the overall code is not increased by virtue of the presence of the second-level code.

Abstract: Interacting call appearances are realized by enabling voice input/output to be simultaneously available on any combination of call appearances at a given time on a given terminal. Consequently, a user may, for example, listen to the voice output of one or more call appearances that are active at the terminal at a given time. Additionally, the user may direct voice input to one or more call appearances that are active at the terminal at a given time. Thus, the user, at any given time, may listen or speak to one or more parties on unrelated calls. Additionally, a user can employ more than one voice input/output device at his/her terminal. Specifically, the ability to simultaneously use more than one call appearance at a terminal at a given time is realized by separating call control from media routing and input/output control. Thus, the appearance of a call at a terminal is separated from the voice input/output that is required for the call.

Abstract: A method and apparatus for a fault injection tool having greater flexibility, ease and portability in realizing the basic functionality of the fault injection. The basic functionality of the fault injection process is abstracted into three base classes, namely, a fault injector (FI), a workload generator (WG) and a data collector (DC). A control class performs configuration and management of the objects that are instantiated from the base classes. The control class also implements a graphical user interface. For each base class there is a corresponding core class that performs control and management of a so-called associated “plugin”. Each of the core classes can be implemented as a single class or as a pair of distributed classes. If a core class is implemented as a pair, the FI, WG, or DC object controls operation of the FIRemote, WGRemote or DCRemote object, respectively. For each core class, the associated plugin performs the actual functionality.

Abstract: Advantageous error rate performance, high bandwidth efficiency, low delay and reduced error floor are achieved at an acceptable level of decoding complexity via the use of serial concatenated turbo codes. These are codes for which at least some of the output bits, including at least one redundant bit, provided by a first, outer encoder are, after interleaving, further processed by a second, inner encoder. The resulting data and redundant bits then select a symbol from a predetermined constellation for transmission. In the receiver, the turbo code is decoded using a corresponding number of soft output decoders which operates iteratively in such a way that improved performance as compared to a single encoding can be achieved. The turbo codes can be of various dimensionalities and can be used as a component of a multilevel code to achieve a desired level of bandwidth efficiency.

Abstract: A fault monitoring, performance monitoring and fault tolerance apparatus and method for target target application programs is realized in an application supervisor by employing a supervisor agent, modified application programming interfaces (APIs), a generic application wrapper and a shell script that operate interactively to detect and automatically resolve reliability and performance problems occurring in executing the target application program. This is realized, in accordance with the invention, without the need to access, modify or have knowledge of the source code of the target application program to be supervised. In a specific embodiment of the invention, Java™ programming language target application programs are supervised. This is realized by employing the supervisor agent that attaches to a Java virtual machine through two virtual machine native interfaces. One interface is the Java Virtual Machine Profiler Interface (JVMPI) and the other is the Java Native Interface (JNI).

Abstract: Computer users may utilize different web browsers to access a server system on the World Wide Web (WWW) to create or join a collaborative session. One or more controllers connect the users or collaborators in a session in the server system. This is realized by establishing a so-called “shared Web-top”, i.e., a work space, in which different in-document applications can be run and can be interactively, collaboratively shared by a plurality of users. Specifically, this is realized by employing a surrogate that includes a polling loop which periodically checks a shared document structure for changes in prescribed properties, and transmits the detected changes to surrogates of other users, i.e., at least one other collaborator, via a communication channel. To this end, a prospective user of the shared Web-top accesses a system, which transmits mobile code to the user's computer to create a surrogate thereon.

Abstract: A frequency offset estimation is generated without explicitly generating a channel estimation for a frequency selective fading communication channel. This is realized by recognizing that, in the absence of additive noise, the channel output at a time n depends only on the last previous predetermined number, L, of data symbols, and that a “state” is a sequence of the last L symbols. Specifically, in a receiver, a received signal is mixed with a locally generated frequency corresponding to a frequency offset to generate a mixed signal. A calculation is made on the mixed signal in which channel outputs of the same state are combined and accumulated. Then, a summation is made over all possible states of the combined and accumulated channel outputs to yield a so-called metric calculation value for that mixed signal. The metric calculation is then repeated for a plurality of different locally generated frequencies corresponding on a one-to-one basis with a plurality of frequency offsets.

Abstract: A telephone instrument is disclosed which includes a swivel visual display module overcome by employing a telephone base having upper and lower housings. A swivel visual display module is pivotally mounted and supported by pivot points in both the upper and lower base housings. At least one cantilever snap member is molded into one of the base housings, for example, the upper base housing, and is employed to engage indents molded into an outer convex surface of the visual display module to hold the visual display module in several angular positions. Additionally, the at least one cantilever snap member is employed to engage a lower edge of the visual display module and in conjunction with stop members on the visual display module to secure the visual display module in a full upright position.

Abstract: A new filter that may be employed in timing recovery circuits, and automatic gain control circuits, employs a so-called vector tracking filter (VTF). The VTF includes a complex filter with a time constant so long that it might be considered a leaky integrator. In operation, the VTF builds up an average vector (timing (gain) estimate vector) having a direction that is the average of the estimated timing (gain) error, which is stored in the VTF. When the VTF is employed in an automatic gain control arrangement, the vector becomes a scalor and only the amplitude is tracked. When an arbitrary timing (gain) correction is made, to the incoming signal, this causes a rotation of the timing (gain) estimate vector. In order to track this rotation, a comparable rotation is made to the stored timing (gain) estimate vector.

Abstract: An apparatus is provided for adding a dither signal to an optical carrier modulated with an information signal. The apparatus includes a dithering element having an input and an output in series with an optical carrier modulated with an information signal. A differential element having an inverting input, a non-inverting input, and an output is coupled to the input of the dithering element. A signal generator, which is provided for producing a desired dither signal to be added to the modulated optical carrier, is coupled to the non-inverting input of the differential element. A feedback element produces a signal related to the output of the dithering element and couples the signal related to the output of the dithering element to the inverting input of the differential element.

Abstract: An optical line protection switching system is realized by employing a plurality of rare earth-doped fiber optical amplifiers as gain-switched optical connections, for example gain-switched optical distributors, i.e., commutators, and/or gain-switched optical selectors in a gain switched optical line protection switching system. In one embodiment, at least one or more gain switched optical distributors are employed to realize so-called head-end switching of an incoming optical signal and one or more gain switched optical selectors are employed to realize so-called tail-end switching of the optical signal to form a 1.times.1 (1.times.N) optical line protection switching system. In another embodiment, an incoming optical signal is bridged to one or more optical paths, while the tail-end switching is realized by employing one or more gain-switched optical selectors to form a 1+1 (1+N) optical line protection switching system.

Abstract: Timing recovery circuits, automatic gain control circuits and the like, employ a so-called vector tracking filter (VTF) in conjunction with other timing recovery techniques. The VTF includes a complex filter with a time constant so long that it might be considered a leaky integrator. In operation, the VTF builds up an average vector (timing (gain estimate vector) having a direction that is the average of the estimated timing (gain) error, which is stored in the VTF. When an arbitrary timing (gain) correction is made, to the incoming signal, this causes a rotation of the timing (gain) estimate vector. In order to track this rotation, a comparable rotation is made to the stored timing (gain) estimate vector. This allows the stored timing (gain) estimate vector to build up, and at any time the stored timing (gain) estimate vector will be the same as if the current incoming phase had been constant for all previous time.

Abstract: A telephone base includes a base module and a rotatable base stand module. The base module may be elevated to a plurality of inclined positions by employing in the base stand modules the plurality of cantilever snap members each of which has a protruding locking member. The telephone base module includes a plurality of locking apertures which correspond to the locking members on the cantilever snap members. The desired inclined positions are obtained by rotating the base module around pivot elements in the base stand module and inserting the locking members on the cantilever snap members into appropriate ones of the locking apertures in the base module. Additionally, the base stand module may be rotated and locked in place to the base module by additional locking members to orient the telephone base for wall mounting. Advantageously all the elements required for the above features are integrally molded into the base module and the base stand module.

Abstract: A gain-switched optical distributor, i.e., commutator, is realized by employing an optical rare earth-doped fiber optical amplifier as the switching element per se. Each of the optical rare earth-doped fiber optical amplifiers acts as an ON/OFF switch. Also, the gain-switched optical distributor of this invention is a natural fit into today's optically amplified optical communication systems. In one embodiment, this is realized by employing a pump select circuit in conjunction with a plurality of pumps and a plurality of corresponding rare earth-doped fiber optical amplifiers. The particular pump and corresponding amplifier is selected by use of a monitor arrangement to determine which signal is to be selected and routed to an output. In another embodiment, a so-called tuned pump arrangement is employed in conjunction with a plurality of filters and a corresponding plurality of rare earth-doped fiber optical amplifiers.

Abstract: The problem of tracking rapid changes in the echo signals associated with modems is eliminated by using an echo canceler consisting of cascaded adaptive filters. Each filter in the structure contributes to the modeling of the overall echo path impulse response, with a longer filter providing the ability to model long echo path impulse responses and a shorter filter providing the ability to track changes in the echo path impulse response over time.

Abstract: An apparatus is provided for adding a dither signal to an optical carrier modulated with an information signal. The apparatus includes a dithering element having an input and an output in series with an optical carrier modulated with an information signal. A differential element having an inverting input, a non-inverting input, and an output is coupled to the input of the dithering element. A signal generator, which is provided for producing a desired dither signal to be added to the modulated optical carrier, is coupled to the non-inverting input of the differential element. A feedback element produces a signal related to the output of the dithering element and couples the signal related to the output of the dithering element to the inverting input of the differential element.

Abstract: Provisioning a Central Office (CO) Basic Rate Interface (BRI) access is a complex procedure which involves hundreds, and potentially thousands, of parameters that must be asserted to configure the CO for a particular users service profile. In such a complex procedure, errors in the provisioning may be introduced which are difficult and costly to detect and correct. To solve this problem, a provisioning tool which exercises BRI lines i.e., digital subscriber lines (DSLs) from a CO to a premises switch is defined which validates that transport related restrictions and permissions are properly administered at the CO. This is achieved by the system calling itself over such lines, and varying the types (e.g., voice, digital, data, 3.1 kHz audio, et al.) of call attempts that are placed to ensure that all lines support the intended services.