At&t Bell Laboratories

Bell Telephone Laboratories

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

At+t Corp.

Noach Amitay

Michael J Gans

Herman M Presby

Lawrence Joel Greenstein

A cellular switching system and architecture is described in which the switching associated with a call originated within one cell but now serviced within another cell is distributed among base stations which are interconnected with each other through a local area network or a packet switch. The routing procedure associated with the point of origin for a given call is stored in the memory of a switch of public switched telephone network. As an active subscriber crosses a cell boundary, the switch routes all packets of information for the given call to the originating base station for the duration of the call. Importantly, each base station then forwards each packet to the subscriber's current base station via the local area network or a packet switch. In this manner, the inventive architecture is unaffected by the increased crossing between cell boundaries since the switching associated with those calls not within the range of the initial base station is handled in a distributed manner by each base station via the local area network or a packet switch.

Distributed packetized switching cellular radio telephone communication

Fast resource assignments, especially needed in microcellular network architectures having many fast moving subscribers and high traffic volume, is provided through the use of a priority based resource assignment apparatus and procedure. Part of the communications resources in a cellular network, for example, one carrier frequency and/or one time slot, or particular code division multiple access sequences are dedicated to the execution of the assignment procedure. Available communications resources are auctioned to cellular subscribers contending for resources based upon a level of priority assigned to each contending subscriber. The priority level may be based on such things as the quality of service to which a customer subscribes or the particular needs of a subscriber at the time the subscriber is contending for resources, for example, the subscriber's request for resources may be prompted by a need to make a handoff. The procedure involves an auction period when a determination is made regarding which of a group of contending subscribers has the highest priority level. The procedure then enters a resource assignment period where an available communications resource is actually assigned to the subscriber having the highest priority level. The auction and assignment periods are then repeated for the remaining contending subscribers until there are no longer any contending subscribers or there are no longer any available resources. Fast resource assignment could be used to increase system capacity and efficiency of spectrum utilization through the ability to perform speech activity resource sharing.

Communications resource assignment in a wireless telecommunications

The present invention relates to a high-speed high-capacity Local Area Network (LAN) wherein each user, of a separate group of one or more of the network users, communicates cordlessly, using radio frequencies or infrared, with an assigned Regional Bus Interface Unit (RBIU) located in the proximity of the group. Each RBIU of the network interfaces with a high-speed serial or lower speed parallel bus of an open-ring network for purposes of transmitting information signals while receiving information signals via the high-speed serial network bus (es), Various communications protocols such as, for example, CSMA/CD, slotted ALOHA, etc. can be employed by the users in communicating with the associated RBIUs with high efficiency due to the short paths involved relative to the transmission frame durations used on the bus.

Cordless accessed high-speed high-capacity local area networks

An optical fiber is disclosed which comprises (a) a central core section of constant thickness which terminates in an outwardly gradually expanded end section, and (b) a cladding layer enveloping the core. Both the core and the cladding layer are of constant compositions throughout the fiber's length and width. Additionally, the difference between the refractive indices of the core and the cladding layer remains constant throughout the length of the fiber. Where the core gradually increases in width in the outwardly expanded end section of the fiber, the V number increases in like manner. In such optical fiber, propagation of a predetermined mode or modes is maintained throughout the entire length of the fiber, so long as the expansion of the end section occurs gradually over the order of many wavelengths.

Expanded end optical fiber and associated coupling arrangements

A canceller for eliminating the cross-polarization interference in incoming signals having polarizations which are orthogonal to one another is proposed. Each incoming signal is coupled to an associated adaptive filter. Each filter output is then summed with an associated one of the incoming signals which has a polarization orthogonal to that of the filter input signal. The signal sums formed are the canceller output signals. Adjustment of the adaptive filters so as to cancel the cross-polarization interference in each received signal is made in response to the incoming signals and the canceller output signals at selected times. During these times, circuitry for adjusting the adaptive filters examines spectral tones formed by the incoming signals and the canceller output signals.

Cross-polarization interference cancellation

The present invention relates to an antenna arrangement which includes a polarization diplexer capable of bidirectionally directing two orthogonally polarized signals along one path in the far field of the antenna arrangement and along two separate paths in the near field for interception along at least one of the paths by an array of feed elements. The array is arranged to provide a fixed linear phase taper along one axis across the array to produce or intercept a beam squinted at an angle 90 degrees-.alpha. to the face of the array and including a signal polarized in a first direction. Phase shifting means selectively produce a linear phase taper along a second axis across the face of the array orthogonal to the first axis to cause the beam to traverse a predetermined arc in the far field of view. Polarization mismatch at the array from the diplexer is overcome by providing a single properly inclined 90 degree polarization rotator or by two properly inclined 90 degree polarization rotators depending on the direction of polarization and whether the array is a linear or a two-dimensional array.

Phased array antenna employing linear scan for wide-angle arc coverage

The present invention relates to a technique for enabling an antenna system to linearly scan over a wide angle of an orbital arc segment from a terrestrial ground station to access or track satellites within the segment. The wide angle linear scan capability is achieved by orienting the antenna system at the ground station relative to the local terrestrial coordinate system such that the axis normal to the aperture plane of the antenna system is at a predetermined angle and lies in a plane substantially parallel to the plane of the orbital arc segment. Then, by squinting the beam toward the orbital arc segment by applying a fixed linear phase taper to the antenna elements of a planar phased array along one axis of the array, linear scanning of the orbital arc segment is possible by, for example, varying the linear phase taper applied to antenna elements along another axis of the array.

Phased array antenna employing linear scan for wide angle orbital arc

The present invention relates to phased array antenna arrangements which comprise a linear array of feed elements where the array has an aperture which is out at a bias angle along the minor axis of the array to produce a fixed linear phase taper along the minor axis by all elements. Then by linearly scanning the array along the major axis of the aperture of the array, a beam is scanned along an arc which can be made to correspond to an orbital arc segment around a celestial body and within the field of view of the antenna arrangement when the bias angle is properly chosen. The feed elements can comprise long feedhorns or horn antenna configurations which can be used in a separate array or disposed in an array on a conjugate plane of a main cylindrical reflector when used in multiple reflector phased array antenna arrangements.

The present invention relates to a driver for a diode switch comprising a complementary arrangement of a first and a second type of transistor across a voltage source. The first type of transistor is coupled to receive only a-c fluctuations in the input signal and is arranged to be not saturated but at cut off at the beginning of each switching subframe and be turned on for a very short time in response to a predetermined a-c input transition. The second type of transistor is coupled to receive a-c and d-c input signal fluctuations and has a resistive element for limiting the forward-biased current through the diode switch when turned on. A resistive element across the emitter collector terminals of the first type of transistor maintains the appropriate back-biasing potential on the diode switch when both transistors are cut off.

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Tinton Falls, NJ, United States of America

Noach Amitay