Lucent Technologies Inc.

At&t Bell Laboratories

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

At+t Corp.

Andrew Corporation

At&t Company

Matthews Research & Development Corp.

Robert Evan Myer

Jack Chi-Chieh Wen

Mohan Patel

Jack C Wen

Reza Ghanadan

Louis J Lanzerotti

Qi Bi

Robert Keith Montgomery

Norman Gerard Ziesse

Edward Vincent Louis

Loren Francis Root

Krishnamurthy Sreenath

George Kenneth Kannell

Clifford W Schaible

Koon Whye Loh

Jimmie L Donaldson, Jr

John N Hines

Edward V Bacher

Paul L Bartley

Farid Firouzbakht

A cellular-type wireless communications system, comprising: an airborne platform that reflects wireless communication signals; and a centralized base station associated with at least one cell, each cell corresponding to a geographic area, the centralized base station configured to send wireless communication signals to the airborne platform and receive wireless subscriber signals which have reflected down off of the airborne platform.

Telecommunications system with reflective airborne platform

A control system comprising an electrical circuit that produces distortion where the electrical circuit has a frequency band of operation. A pilot modulated carrier signal is frequency hopped about the frequency band of operation. The hopping pilot modulated carrier signal does not interfere with any signal applied to or generated by the electrical circuit as it is not at any time located within the frequency band of operation. Information obtained from the hopping pilot modulated carrier is provided to the control system which uses such information to cancel the distortion produced by the electrical circuit.

Pilot signal cycling technique for a control system that reduces distortion produced by electrical circuits

An amplifier includes a main amplifier circuit and at least one auxiliary amplifier circuit. Portions of an RF signal to be amplified are delivered to the main and auxiliary amplifiers. The auxiliary amplifier circuit is selectively operable to operate in combination with the main amplifier circuit, such as based on the level of the RF signal. At least one hybrid coupler circuit has input ports coupled with outputs of the main amplifier circuit and auxiliary amplifier circuit. The hybrid coupler circuit is operable to combine amplifier circuit output signals at a coupler first output port. A coupler second output port is terminated with one of an electrical short and an electrical open circuit.

High efficiency amplifier

A multiple input/output switch includes a plurality of transmission control logic units and a plurality of reception control logic units. Each of the transmission control logic units is associated with a transmission data path, and each of the reception control logic units is associated with a reception data path. Each transmission control logic unit outputs a destination code on a communication medium when the transmission control logic unit receives data. The destination code identifies a reception data path to which the data is to be sent. The reception control logic units monitor the communication medium for their respective destination codes, and when detected, send a confirmation signal to the transmission control logic unit via the communication medium. Upon receipt of the confirmation signal, the transmission control logic unit outputs the received data to the reception control logic unit via the communication medium.

Multiple input/output switch

An inexpensive RF test probe provides consistent monitoring of an RF signal while having minimal effect on the circuit under test. In one embodiment, an RF test probe comprises a return conductor and a probing conductor. The probing conductor is positioned within an insulator and a termination such as a 50 ohm resistor is electrically positioned between the ground conductor and probing conductor. The probe is used by placing a portion of the insulating material surrounding the probe conductor in contact with a circuit such as an RF microstrip carrying an RF signal to be monitored.

RF test probe

A wireless communications technique enables direct call set up and communication between wireless subscribers without involving network infrastructure. A mobile is modified to perform like a network base station during a local calling mode initiated by a user, thereby reversing transmit and receive frequency bands and allowing the mobile to set up and carry out a call as if it were a network base station. The mobile initially performs a communication channel or frequency sweep sequence to determine an idle traffic channel, thereby preventing interference with other subscribers. After a local call is established, the transceiver monitors call quality, and performs another communication channel or frequency sweep sequence to select a new traffic channel when call quality drops below a threshold level to ensure a certain level of call quality between the first and second mobiles.

System and method for mobile controlled direct mode wireless local calling

A wireless communication system or method capable of providing both a two-way telephone service and a two-way paging service on the same infrastructure. The system or method is capable of distinguishing whether a subscriber is a telephone or paging subscriber. If the subscriber is a two-way paging subscriber, the system or method allows the calling party to have the capability of conversing directly with the called party for a limited time or the options of leaving voice, numeric or alphanumeric messages for the called party to retrieve later.

Two-way telephone and two-way paging service on the same wireless infrastructure

Frequency hop pilot technique for a control system that reduces distortion produced by electrical circuits

A gain and phase control system performs a gain (or phase) adjustment based on the results of a previous gain (or phase) adjustment after an intervening phase (or gain) adjustment. A gain adjustment is based on the results of a previous gain adjustment rather than on the results of an intervening phase adjustment. A phase adjustment is based on the results of a previous phase adjustment rather than the results of an intervening gain adjustment. As such, the above-mentioned increase in error signal does not occur because a gain adjustment is based on the results of the previous gain adjustment, and a phase adjustment is based on the results of the previous phase adjustments. In accordance with another aspect of the present invention, the gain and phase control system makes a gain (or phase) adjustment in parallel with detecting the results from a previous phase (or gain) adjustment, thereby taking advantage of the delay between adjustment and detection of the resulting error signal to improve the convergence rate. For example, the gain and phase control system can perform single alternating gain and phase adjustments and make a gain (or phase) adjustment while detecting the error signal resulting from a preceding phase (or gain) adjustment. When the error signal resulting from the gain (or phase) adjustment is being detected, the gain and phase control system makes a phase (or gain) adjustment using the results detected from the preceding phase (or gain) adjustment.

Alternating gain and phase control system and method

A frequency mixing system provides an expanded dynamic range when compared to the dynamic range(s) of an individual mixer(s) that make up the arrangement. The frequency mixing system uses a feed-forward arrangement to reduce the distortion emanating from a single mixer due to a signal power level which would result in a frequency converted signal outside the dynamic range of the mixer. For example, the frequency mixing system splits an input signal onto a first path and a second path. On the first path, a first mixer frequency mixes the signal to produce a frequency converted signal with distortion, such as intermodulation distortion. On the second path, the amplitude of the signal is attenuated then frequency mixed by a second mixer to produce a frequency converted signal with a low and/or insignificant level of distortion. The first mixer element produces a frequency converted signal with distortion because the signal on the first path enters the first mixer at a power level resulting in a frequency converted signal outside the dynamic range of the first mixer. As such, the higher power level of the signal into the first mixer creates distortion that emanates from the first mixer along with the frequency converted signal. Since the attenuated signal on the second path enters the second mixer at a lower power level resulting in a frequency converted signal within the dynamic range of the second mixer, the second mixer produces the frequency converted signal with the low and/or insignificant level of distortion. After the signals on the first and second paths are frequency converted, the frequency converted signal and distortion are coupled from the first path and combined with the frequency converted signal on the second path, producing the distortion as the prominent signal on the second path. The distortion on the second path is then combined with the frequency converted signal and distortion on the first path to cancel the distortion on the first path and produce the desired frequency converted signal with reduced distortion as compared to the distortion produced if the original input signal would be frequency converted using only the first mixer.

Apparatus and method for extending the dynamic range of a mixer using feed forward distortion reduction

Method and apparatus for substantially eliminating distortion produced by a processing circuit where the distortion produced by a first circuit with similar characteristics as the processing circuit is modified and the modified distortion is applied to the processing circuit. The distortion produced by the first circuit is modified based on information derived from distortion produced by the processing circuit. The modified distortion, when applied to the processing circuit, combines destructively with distortion produced by the processing circuit.

Method and apparatus for an automatic predistortion system

A frequency mixing system that provides an expanded dynamic range when compared to the dynamic range(s) of an individual mixer(s) that makes up the frequency mixing system. The frequency mixing system adjusts the amplitude of an input signal to be frequency mixed to produce a frequency converted signal with an acceptable and/or lower (when compared to the amplitude of intermodulation distortion produced by mixing the input signal without amplitude adjustment) amplitude of intermodulation distortion. If the input signal were frequency mixed without the amplitude adjustment, an unacceptable and/or higher level of intermodulation distortion would result (when compared to the corresponding intermodulation distortion if the amplitude-adjusted signal were mixed by an individual mixer). Adjusting the amplitude of the input signal creates an adjusted signal with signal distortion on the first path. The frequency mixing system uses a feed-forward arrangement to reduce the signal distortion created by adjusting the amplitude of the input signal, thereby producing the desired frequency converted signal with the lower and/or acceptable level of intermodulation distortion. For example, the signal distortion from the first path can be placed on a second path, frequency converted using a second mixer on the second path, and subsequently put back into the first path to combine with the signal distortion on the first path to provide the desired frequency converted signal with the acceptable and/or lower level of intermodulation distortion. By increasing the relative difference between the amplitudes of the desired frequency converted signal and of the intermodulation distortion, the frequency mixing system provides an expanded dynamic range.

Method and apparatus for extending the dynamic range of a frequency mixer

A wireless telecommunications system with a base station positioned on an airborne platform is provided. The system utilizes a ground-based wireless switching center which communicates via a microwave link with a plurality of airborne base stations positioned above a geographic area being serviced by the telecommunications system. The base stations are supported on an airborne platform having a propulsion system designed to maintain the platform and the base stations in position above the geographic area being serviced. Advantageously, the platform may be positioned in the stratonull which is generally very stable and is located above the troposphere, wherein weather variations occur.

Wireless telecommunications system having airborne base station

An adaptive gain and/or phase control system adapts the gain and/or phase adjustment resolution to provide improved performance. For example, the adaptive gain and/or phase control system can dynamically adjust the adjustment resolution for gain and/or phase adjustments as a function of the error signal(s). In response to a large error signal(s) (far from the null), the adaptive gain/or phase control system decreases the adjustment resolution, resulting in a faster convergence rate. In a feed forward distortion reduction system, decreasing the adjustment resolution improves the transient response of the amplifier (for example, given any set of operating conditions, how quickly the amplifier responds to a changing input). As phase or gain adjustments are made to approach the null, the error signal reduces, and the adaptive distortion reduction system increases the adjustment resolution. By increasing the adjustment resolution as the error signal approaches the null, finer phase or gain adjustments can be made which further reduce the error signal. For example, in a feed forward distortion reduction system, such a scheme prevents the error signal from repeatedly jumping over the null due to limited resolution without sacrificing the transient response of the amplifier.

Adaptive gain and/or phase adjustment control system and method

A pilotless feed forward distortion reduction system uses phase and gain control based on the phases and amplitudes of combining signals prior to a distortion isolation point to maintain the relationship between the phase and amplitudes of combining signals. For example, the feed forward arrangement receives a signal to be amplified on a main signal path and replicates the signal onto a main signal path and a feed forward path. The signal on the main signal path is applied to a gain & phase circuit. The output of gain & phase circuit is applied to the amplifier whose output comprises the amplified signal and distortion signals produced by the amplifier. A portion of the output of the amplifier is placed on a coupling path and combined at the distortion isolation point with a delayed version of the signal on the second path to isolate the distortion produced from the amplifier. The gain & phase circuit is controlled to adjust the gain and phase of the signal such that the signal at the distortion isolation point is substantially the inverse (equal in amplitude but 180.degree. out of phase) of the delayed input signal on the feed forward path. The control signal appearing on the control path of the gain & phase circuit is derived from the portion of the amplified signal with distortion on the coupling path and the delayed version of the signal on the feed forward path.

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Denville, NJ, United States of America

Robert Evan Myer