Abstract: A discrete multitone stacked-carrier spread spectrum communication method is based on frequency domain spreading including multiplication of a baseband signal by a set of superimposed, or stacked, complex sinusoid carrier waves. In a preferred embodiment, the spreading involves energizing the bins of a large Fast Fourier transform (FFT). This provides a considerable savings in computational complexity for moderate output FFT sizes. Point-to-multipoint and multipoint-to-multipoint (nodeless) network topologies are possible. A code-nulling method is included for interference cancellation and enhanced signal separation by exploiting the spectral diversity of the various sources. The basic method may be extended to include multielement antenna array nulling methods for interference cancellation and enhanced signal separation using spatial separation. Such methods permit directive and retrodirective transmission systems that adapt or can be adapted to the radio environment.

Abstract: According to a particular embodiment, a method for assisting in a handoff is provided that includes receiving signaling from one or more access points, which may transmit information to a mobile station. The information may be used to execute a handoff from an enterprise network to a cellular network or from the cellular network to the enterprise network.

Abstract: A method for evaluating number of additional admissible calls for use in call admission control includes tracking a percentage of channel busy time and transmission time of downlink and uplink voice packets, receiving a call admission request, and calculating the number of admissible calls. The number of admissible calls is calculated based on a channel bandwidth requirement determined from the percentage of channel busy time and a voice packet queuing requirement determined from the transmission time of downlink and uplink voice packets. The call admission request is approved if the number of admissible calls is greater than one and rejected if the number of admissible calls is less than one.

Abstract: An apparatus and method for switching a mobile processing device from communicating over a wireless connection with a first base unit to a second base unit based upon latency. In accordance with this invention, the mobile processing device determines latency information for packets being transmitted over the wireless connection to and from a base unit. The latency information is compared to a threshold value. If the latency information is greater than the threshold value, the mobile processing device adjusts parameters of the wireless connection between the mobile processing device and the network.

Abstract: A technique for network planning that includes an interface for guiding a network user through the network allocation process, such as defining groups of clients based on their capabilities. Portions of the wireless local area network infrastructure, e.g., access points, are allocated among the groups. When a client attempts to associate with an access point, the access point determines the client capabilities. If the client is supported by the access point, the access point allows the client to associate and sends the client a message that contains a prioritized list of other nearby access points allocated to service that client, otherwise the access point sends a prioritized roaming list of nearby access points to the client that are allocated to serve that type of client. Feedback is provided by the network infrastructure enabling a network user or the network to automatically reallocate resources based on the feedback.

Abstract: An expandable coupling arrangement for coupling first and second tubulars includes a male thread portion on an end of the first tubular and a female thread portion on an end of the second tubular. The thread portions comprise dovetail threads having flanks, roots and crests, wherein the flanks are inclined at an angle of greater than 10°.

Abstract: Interferometric apparatus and methods for reducing the effects of coherent artifacts in interferometers. Fringe contrast in interferograms is preserved while coherent artifacts that would otherwise be present in the interferogram because of coherent superposition of unwanted radiation generated in the interferometer are suppressed. Use is made of illumination and interferogrammetric imaging architectures that generate individual interferograms of the selected characteristics of a test surface from the perspective of different off-axis locations of illumination in an interferometer and then combine them to preserve fringe contrast while at the same time arranging for artifacts to exist at different field locations so that their contribution in the combined interferogram is diluted.

Abstract: A discrete multitone stacked-carrier spread spectrum communication method is based on frequency domain spreading including multiplication of a baseband signal by a set of superimposed, or stacked, complex sinusoid carrier waves. In a preferred embodiment, the spreading involves energizing the bins of a large Fast Fourier transform (FFT). This provides a considerable savings in computational complexity for moderate output FFT sizes. Point-to-multipoint and multipoint-to-multipoint (nodeless) network topologies are possible. A code-nulling method is included for interference cancellation and enhanced signal separation by exploiting the spectral diversity of the various sources. The basic method may be extended to include multielement antenna array nulling methods for interference cancellation and enhanced signal separation using spatial separation. Such methods permit directive and retrodirective transmission systems that adapt or can be adapted to the radio environment.

Abstract: A tubing expansion device (20) is adapted to be advanced axially, without rotation, through tubing (10) to be expanded. The device (20) comprises a body (22) and a plurality of expansion members (30,32,34) mounted on the body (22), the expansion members (30,32,34) being independently radially movable. The expansion members may be rotatable, or may be non-rotating.

Abstract: Interferometric apparatus and methods for reducing the effects of coherent artifacts in interferometers. Fringe contrast in interferograms is preserved while coherent artifacts that would otherwise be present in the interferogram because of coherent superposition of unwanted radiation generated in the interferometer are suppressed. Use is made of illumination and interferogrammetric imaging architectures that generate individual interferograms of the selected characteristics of a test surface from the perspective of different off-axis locations of illumination in an interferometer and then combine them to preserve fringe contrast while at the same time arranging for artifacts to exist at different field locations so that their contribution in the combined interferogram is diluted.

Abstract: A discrete multitone stacked-carrier spread spectrum communication method is based on frequency domain spreading including multiplication of a baseband signal by a set of superimposed, or stacked, complex sinusoid carrier waves. In a preferred embodiment, the spreading involves energizing the bins of a large Fast Fourier transform (FFT). This provides a considerable savings in computational complexity for moderate output FFT sizes. Point-to-multipoint and multipoint-to-multipoint (nodeless) network topologies are possible. A code-nulling method is included for interference cancellation and enhanced signal separation by exploiting the spectral diversity of the various sources. The basic method may be extended to include multielement antenna array nulling methods for interference cancellation and enhanced signal separation using spatial separation. Such methods permit directive and retrodirective transmission systems that adapt or can be adapted to the radio environment.

Abstract: A discrete multitone stacked-carrier spread spectrum communication method is based on frequency domain spreading including multiplication of a baseband signal by a set of superimposed, or stacked, complex sinusoid carrier waves. In a preferred embodiment, the spreading involves energizing the bins of a large Fast Fourier transform (FFT). This provides a considerable savings in computational complexity for moderate output FFT sizes. Point-to-multipoint and multipoint-to-multipoint (nodeless) network topologies are possible. A code-nulling method is included for interference cancellation and enhanced signal separation by exploiting the spectral diversity of the various sources. The basic method may be extended to include multielement antenna array nulling methods for interference cancellation and enhanced signal separation using spatial separation. Such methods permit directive and retrodirective transmission systems that adapt or can be adapted to the radio environment.

Abstract: A discrete multitone stacked-carrier spread spectrum communication method is based on frequency domain spreading including multiplication of a baseband signal by a set of superimposed, or stacked, complex sinusoid carrier waves. In a preferred embodiment, the spreading involves energizing the bins of a large Fast Fourier transform (FFT). This provides a considerable savings in computational complexity for moderate output FFT sizes. Point-to-multipoint and multipoint-to-multipoint (nodeless) network topologies are possible. A code-nulling method is included for interference cancellation and enhanced signal separation by exploiting the spectral diversity of the various sources. The basic method may be extended to include multielement antenna array nulling methods for interference cancellation and enhanced signal separation using spatial separation. Such methods permit directive and retrodirective rev transmission systems that adapt or can be adapted to the radio environment.

Abstract: The optical assembly of a GDI instrument is configured to deviate or steer stray beams away from the pupil of the instrument's imaging device and/or to suppress stray beams. Stray beam deviation is optimized by selecting particular wedge and/or tilt configurations that achieve the desired stray beam deviation while avoiding or at least minimizing phase offset at the optimum metrology plane. Stray beam suppression can be achieved by providing the diffractive groove profile of the instrument's optical assembly with smooth edges. The resultant profile facilitates effective diffraction order management as well as a reduction in back reflection. The invention is particularly well-suited for use with a GDI instrument in which the optical assembly comprises first and second diffraction gratings.

Abstract: A multi-element refractive/diffractive lens system, especially useful in an interferometer of the Fizeau type for forming a partially reflective end of the cavity and focusing collimated laser light at a focus in the cavity, uses a plurality of lens elements all of which are plano concave or plano convex singlets and may be either spherical or cylindrical. The lens has a diffractive element which compensates for aberrations due to the refractive elements of the lens system and enables the lens system to be formed from relatively few refractive elements which are all plano-convex or plano-concave singlets thereby providing cost savings arising out of the reduction in the amount of glass material and number of lens elements. Since the lens system is especially suitable for use in a Fizeau type interferometer, it may be of the type called a Fizeau lens.

Abstract: A dense carbon free surface is provided on a carbon bonded refractory shape which is particularly useful as a pouring tube liner to prevent the formation and build-up of alumina particles which may cause blockage of the tube. The carbon free, dense layer is also hard and erosion resistant making it ideal for use in other applications such as stopper rod noses. The material comprises a refractory mix having a major component of refractory oxides such as alumina and zirconia-mullite. Less than 10 wt. % carbon in the form of graphite and binder is in the mix plus about 2-5 wt. % of a metal such as silicon and an effective mount of sintering aids is also present. The pressed shape is preheated to a temperature of 1000.degree. -1400.degree. C. in air to oxidize the exposed surface of the shape and then to sinter the oxidized surface to form the desired dense, carbon free surface over the entire shape or on selected surface portions thereof.

Abstract: A coupling includes a pair of cup-shaped members with one mounted for sliding axial motion inside the other. The outside coupling acts as a support or base which is connected to a conveyor that moves the coupling between workpiece loading and unloading means. The inside member also carries detents which move radially in and out to grasp or release the workpiece in response to axial motion between the two cup-shaped members. When combined with a conveyor, appropriate cam and follower means are provided to cause the coupling to be operated for grasping and releasing the workpiece in a timed sequence and to move the coupling from a workpiece loading station to an unloading station. The coupling and conveyor are suited for use in handling soft or easily marked materials such as plastic, soft metals, and the like. A method for workpiece handling includes steps of rotating, advancing in stop-and-go fashion while continuously rotating, and unloading.