Abstract: In accordance with the invention, a high speed thermo-optic phase shifter comprises a length of optical waveguide including a waveguiding core of a first material having an index of refraction n1 and a first order temperature dependence |dn1/dT| and, optically coupled to the core, a length of a second material having an index n2 preferably greater than the core (n2>n1) and a first order temperature dependence |dn2/dT| than the core (|dn2/dT|>|dn1/dT|). Advantageously, the length of second material is adiabatically tapered at both ends. Upon heating, as by a resistance heater, the second material changes the optical pathlength by an amount predominantly determined by |dn2/dT| providing faster switching speed. In a preferred embodiment, the core comprises silica, and the second material comprises silicon to produce switching speeds up to a few hundred MHz.

Abstract: A method and apparatus for increasing in the data rate of a multiple-input and/or multiple-output system that has frequency selective fading by using training sequences with both low normalized auto-correlation and low normalized cross-correlation. Both 1) the sum of the square of the normalized auto-correlation of each training sequence over an auto-correlation window and 2) the sum of the square of the normalized cross-correlation of each pair of the training sequences over a cross-correlation window, are significantly less than unity. In one embodiment of the invention the training sequences are shifted versions of each other, and the low normalized cyclic-auto-correlation of cyclic sequences is significantly less than unity, with each cyclic sequence being N?, N?=N?L+1, symbols of one of the at least two training sequences.

Abstract: Techniques for use in designing, adjusting or operating a wireless network so as to provide a desired level of performance for the network. An optimization process is applied to a set of information characterizing the network. The optimization process is implemented as a multi-stage process which includes at least a frequency assignment stage and a post-frequency-assignment optimization stage, wherein the frequency assignment stage and the post-frequency-assignment stage are subject to iteration. For example, after an initial assignment of the frequencies in the frequency assignment stage, the post-frequency-assignment optimization stage may be performed, and based on the result of the optimization, at least one of the frequency assignment stage and the post-frequency-assignment optimization stage may be repeated. An output of the optimization process is utilized to determine one or more operating parameters of the wireless network, such as a base station transmit power or antenna orientation.

Abstract: A method and apparatus for performing discriminative training of, for example, call routing training data (or, alternatively, other classification training data) which improves the subsequent classification of a user's natural language based requests. An initial scoring matrix is generated based on the training data and then the scoring matrix is adjusted so as to improve the discrimination between competing classes (e.g., destinations). In accordance with one illustrative embodiment of the present invention a Generalized Probabilistic Descent (GPD) algorithm may be advantageously employed to provide the improved discrimination.

Abstract: An integrated device has a spring having at least two split parts that are not in direct electrical contact with each other. The integrated device also has a substrate and a movable part, where both parts of the spring are configured between the substrate and the movable part to support the movable part on the substrate. The two or more split parts of the spring enable two or more independent voltages to be applied to the movable part. The split spring of the invention may be used in MEMS devices for optical switches in order to provide independent voltages to the movable part(s) in those devices.

Abstract: A digital subscriber line (DSL) compatible plain old telephone service (POTS) line card that interface a telecommunications switching system to a subscriber over a two-wire subscriber line, wherein the subscriber line card detects whether a DSL line card is connected to the subscriber line. A digital signal processor on the POTS line card is configured to process voice-band signals with a first set of parameters if a DSL line card is connected to the subscriber line and to process voice-band signals with a second set of parameters if the DSL line card is not connected to the subscriber line. Detecting the presence of a DSL line card may be performed by sending a voice band tone on the subscriber line and the return loss measured. Additionally, a tone above voice band may be sent on the subscriber line and a return loss measured.

Abstract: The present system for providing presence enabled call forwarding serves to pass presence and supervision information relating to a user's wireless station set between a cellular communication network and an enterprise communication network, which typically includes a Private Branch Exchange system. The user is provided with the ability to control the forwarding of calls from the enterprise communication network to their cell phone. The user receives a query from the presence system when they activate their cell phone to indicate the availability of call forwarding blocking. The user can update their presence information to indicate that their cell phone is available to receive incoming calls directed to the cell phone, but not available to receive incoming calls that are forwarded from the enterprise communication network.

Abstract: A low-loss integrated optical coupler includes at least three substantially similar optical couplers, adjacent ones of the optical couplers interconnected via at least one set of waveguides, each of the sets of waveguides comprising a path-length difference between the waveguides therein. In one embodiment of the present invention, the multi-section optical coupler comprises at least two arms and the path-length differences are adjustable such that signals traversing the at least two arms undergo a relative phase shift, such that a desired output power splitting ratio for the multi-section optical coupler is achieved. Alternatively, the optical coupler is implemented in an inventive optical device that functions at least, as an optical switch or an optical splitter.

Abstract: A method includes epitaxially growing a semiconductor layer with a free surface and performing an anneal that reduces atomic roughness on the free surface. The free surface has an orientation with respect to lattice axes of the layer for which atoms in flat regions of the free surface have more chemical bonds to the layer than do, at least, some of the atoms at edges of monolayer steps on the free surface.

Abstract: A packaged MEMS device containing the micro mirrors has mounted on it at least two distinct integrated circuit chips, at least one of which contains the low-voltage digital-to-analog converts and at least one of which contains the high-voltage amplifiers. The integrated circuit chips may be mounted directly to the MEMS package, or they may be indirectly mounted thereto, e.g., by being directly mounted to a multi-chip module which is in turn mounted on the package. Thus, the MEMS package is employed in a dual role, 1) that of package for the MEMS device and 2) the role of a backplane in that it contains mounting places and the wires interconnecting the MEMS device and chips or modules containing the low-voltage digital-to-analog converters and the high-voltage amplifiers.

Abstract: An optical filter apparatus for processing an optical signal comprising a spectrum broadening device for spectrally dividing one or more channels of the optical signal into a discrete set of spectral components for each channel, a collector for collecting the spectral components on a discrete number of corresponding light channels, one or more processors for individually processing one or more of the spectral components on the light channels, and a combiner for recombining the spectral components on the light channels.

Abstract: An active balun circuit is provided for single-ended to differential RF signal conversion with enhanced common-mode rejection which suppresses common mode signal and which achieves phase and amplitude balance without sophisticated tuning or compensation methods. The circuit has a single-ended input and balanced output with phase and amplitude balance error less than 2° and 1.2 dB, respectively, measured from 1.5 GHz to 1.8 GHz at 5V supply. When supply voltage drops down to 1.5V, its phase and amplitude balance error remains within 5° and 2 dB, respectively. The circuit achieves a balanced output via an output network which behaves as an impedance matching network for differential mode signal and is grounded for common mode signal. As a result, common mode signal is suppressed and 180-degree phase balance at output is achieved. The circuit has high-linearity (P1 dBin=5 dBm, IIP3=16.

Abstract: An improved code acquisition scheme for faster acquisition of GPS “coarse acquisition” (C/A) codes leads to faster detection of GPS signals, and thereby a wireless terminal may determine its position in a shorter period of time. The scheme is a combination of a frequency-domain and time-domain code acquisition techniques. The scheme utilizes a frequency-domain code acquisition technique to detect one GPS signal and to create a precise timing reference at the wireless terminal, and then utilizes time-domain code acquisition techniques to detect other GPS signals from the same satellite or other satellites faster. The scheme has the advantage of being able to be used for any wireless communications system without the requirement of maintaining a precise timing reference in the wireless terminals, and without the requirement of heavy computational resources that are usually needed in systems that utilize frequency-domain code acquisition techniques.

Abstract: Signal construction, detection and estimation techniques for use in uplink timing synchronization and access control in an orthogonal frequency division multiplexed (OFDM) wireless system or other type of wireless communication system. In accordance with an illustrative embodiment of the invention, timing and access signals to be transmitted in designated timing and access intervals are constructed from orthogonal multitone signals. The multitone signals may be similar to multitone signals used in OFDM data transmission, except that a cyclic prefix associated with reception of the signals in a base station is extended to cover the timing errors of mobile stations not yet synchronized.

Abstract: An apparatus for providing at least first and second representations of an audio signal for use in a communications system is described. The apparatus comprises a first quantizer for quantizing at least a portion of the signal in accordance with a first multidimensional lattice to generate a first representation. The apparatus further comprises a second quantizer for quantizing at least a portion of the signal in accordance with a second, different multidimensional lattice to generate a second representation. In an illustrative embodiment, the first representation is a core representation containing core audio information. The second representation is an enhancement representation containing enhancement audio information. The core representation is necessary for recovering the audio signal with minimal acceptable quality. Audio quality is enhanced when the core representation, together with the enhancement representation, is used to recover the audio signal.

Abstract: The present invention is a method for improving data transfer performance over communications networks connecting data networks and users using adaptive communications formatting. Adaptive communications formatting includes encoding (or compressing) the data and applying error control schemes to reduce the amount of data being transmitted and to correct and/or conceal errors occurring during data transmission. In one embodiment, the present invention uses a set of transcoding techniques to encode (or compress) the data and a set of error control schemes to correct and/or conceal errors occurring during data transmission. The particular sets of transcoding techniques and error control schemes selected to format the data are adaptive to factors, such as the nature of the communications network connecting a user to an access server on the data network, the preferences of the user, and the data type of the data being transmitted to the user (or the access server).

Abstract: The invention pertains to methods and apparatus for determining when and how to perform communications network congestion control tactics, such as reconfiguring pipeline bandwidths, with respect to packet-based networks.

Abstract: The invention relates to a data transmission system for the frame-oriented digital data transmission of a plurality of useful signals embedded in a carrier signal, using time-division multiplex operation, rate matching being undertaken between the useful signals and the carrier signal by means of stuff locations. The data to be stuffed, and the management information for the reassignment are embedded in previously unused 8 bytes in the path layer overhead of the carrier signal superframe, and protected by an HC(6,3,3) code. Clear channel signals can advantageously be transmitted using the system, and the transmission is time-transparent and data-transparent.

Abstract: The present invention provides a method and apparatus for restricting call terminations for a roaming mobile unit. A serving MSC, which is an MSC providing call processing a mobile unit that is not the home MSC of the mobile unit, sends a registration notification request to the home location register (HLR). The HLR retrieves the termination access code parameter from the HLR and sends it to the serving MSC. The termination access code parameter includes a value that indicates if the mobile unit is allowed to roamer port calls. The parameter is stored at a VLR associated with the serving MSC. When a call request comes in to the serving MSC and requests a roamer port call with the mobile unit, the serving MSC checks the value of the termination restriction code to determine if it should terminate, or complete, the call.

Abstract: A method and apparatus for preserving call-state information on a wireless communication system is provided. The method includes periodically replicating stable call call-state information between a first and second processor via a network connection. The method also includes performing a transient clear to drop transient calls in existence at the time of an outage of an active first RCS application process or processor. The method also includes forming network-based active call facilities paths to a second RCS application instance and transitioning the second RCS application instance to an active state thereby avoiding a service interruption for the stable calls previously handled by the active first RCS application instance.