Northrop Grumman Systems Corporation

Trw Limited

Other

Harvey L Berger

Ronald P Smith

Dennis A Nivens

Mark Kintis

Stuart T Linsky

Reginald Jue

Eric R Wiswell

Daniel R Lane

Konstantinos Makrygiannis

Mark K Christopher

Robert W White

Allen F Conrad

Scott A Cooper

Craig A Hornbuckle

Oliver W Saunders

Gerald R Fischer

Garrick Jon Harmon

Kenneth E Westall

Esmaell Yousefi

James C Becker

Fred C Tramm

Ryan M Desrosiers

Samuel J Friedberg

A technique for enhancing the signal-to-noise performance of a digital communication link without affecting its power flux density. An information data stream has its original signaling rate selectively reduced prior to transmission, to enhance signal-to-noise performance. Then the reduced signaling rate information signal is combined with a pseudorandom data sequence at the original signaling rate, to provide a randomized data sequence to be transmitted at the original signaling rate, thereby maintaining power flux density levels below those permitted by regulatory limits.

Method and apparatus for reducing data rate transmitted in a beam without affecting its power flux density

A technique for reducing power requirements in a communication transponder by converting signals in multiple uplink channels carried in frequency division multiplexed (FDM) form on multiple uplink beams, to a lesser number of downlink beams that operate in time division multiplexing (TDM) but at a bandwidth different from and preferably greater than the bandwidth of the uplink channels. Because the TDM downlinks can utilize amplifiers operating at or near peak power, whereas conventional FDM downlinks must operate with amplifiers backed off to minimize intermodulation products, use of the TDM downlinks effects significant power savings.

Communication system and method using time division multiplexed (TDM) downlink

A power gated variable hop cycle beam laydown () manifests itself as first cells (C, D) supported by a first hop cycle, second cells (G, H) supported by a second hop cycle, and transition cells (E, F) supported by a transition hop cycle. The transition hop cycle uses power gating to transition the laydown () from cells (C, D) operating at the first hop cycle to cells (G, H) operating at the second hop cycle. To this end, the transition hop cycle power gates its downlink beam for a portion of time needed to reduce interference between nearby (e.g., adjacent) cells.

Beam laydown for hopped satellite downlink with adaptable duty cycle

A method for ultra wideband (UWB) communication in which UWB pulses encode binary data as either normal or inverted (anti-podal) pulses. In the case of pulses of a carrier signal, each pulse has the carrier signal either inverted or in phase, that is, shifted by 180&#xb0;, or not. For example, a binary '1' may be encoded as a normal or non-inverted pulse and a binary '0' as an inverted pulse. After each carrier pulse is rectified and filtered, detection is effected using a threshold value of zero, resulting in increased immunity to noise, compared with detection of unidirectional pulses. In one aspect of the invention, data pertaining to multiple communication channels are encoded in time-divided portions of each UWB pulse.

Bipolar waveform modulation for ultra wideband (UWB) communication networks

An improved decoding technique useful for hard decision decoding, such as quadrature phase shift keying (PSK) and quadrature amplitude modulation (QAM), as well as soft-decision techniques, such as Viterbi decoding and trellis decoding. The system in accordance with the present invention provides adaptive decision regions for hard-decision decoding techniques and adaptive metrics for soft-decision detection techniques in which the decision boundaries and reference constellations, respectively are optimized in order to minimize the bit error rate (BER). In particular, the decision boundaries and metrics are optimized based on the locations of the received constellation points. By adaptively adjusting the decision boundaries and metrics, the BER can be greatly improved with the need for nonlinear predistortion at the transmitter thus reducing the hardware complexity and weight of the transmitter which provides additional benefits in applications, such as satellite communication systems, where the transmitter is located on the satellite.

Adaptive decision regions and metrics

A method and apparatus are provided for supporting the transmission of communications data in a satellite communications networkbetween user terminalsand a ground stationvia a satellite. At least one carrier signal is generated in a beam spot and conveys communications data over at least one downlinkto the user terminals. The carrier signal is modulated simultaneously with independent communications data streams EDPand EDPover modulation channelsand, respectively, of a multi-dimensional modulator. By passing independent data streams over each dimension of an n-dimension modulation technique, different encoding schemes may be assigned to user terminalsbased upon the strength of the signal received by the user terminal

Method and apparatus for maintaining independent, parallel data streams over separate modulation channels of a multi-dimensional modulator

A data routing subsystem () for a communication satellite includes an inbound module () that accepts demodulated uplink data. The inbound module () includes a routing table () that stores queue tags () specifying downlink beam hop locations () for the uplink data. The subsystem () also includes a self addressed packet switch () having an input port coupled to the inbound module (), and an outbound module () coupled to an output port of the switch (). A memory () in the outbound module () stores the uplink data in accordance with the downlink beam hop locations (). A multiple beam array antenna () is coupled to the outbound module (). The multiple beam array antenna () includes a first feed element () assigned to a first downlink beam hop location () and a second feed element () assigned to a second downlink beam hop location ().

Beam hopping self addressed packet switched communication system with multiple beam array antenna

A method of packet concatenation in TDMA transmission is provided. The method includes the step of transmitting from a terminal in a first time slot ( ), including overhead information ( ) and symbols representing terminal data ( ). The method also includes the step of transmitting from a terminal (possibly the same terminal) in a subsequent time slot ( ), including a subset of the overhead information ( ) and symbols representing terminal data ( ). The subsequent time slot may be a consecutive time slot. The overhead information may include, for example, guard time ( ), ramp time beam settling time ( ) and a preamble ( ).

Packet concatenation for increased transmission capacity

Methods and devices for predistorted 12/4 Quadrature Amplitude Modulation that compensate for distortion from a nonlinear element. Modulator input bits are mapped ( ) to a plurality of nonreturn-to-zero (NRZ) modulator control bit ( ). The mapping is determined by desired points on a 12/4 QAM constellation. At least one phase shift device ( ) receives an input signal and at least one of the plurality of modulator control bit. At least two quaternary phase shift keying (QPSK) devices ( ) receive phase shifted signals from at least one phase shift device. Each of at least two QPSK devices receives at least one of the plurality of NRZ symbols. An attenuator ( ) that attenuates a first QPSK signal outputted from a first QPSK device of the at least two QPSK devices. A summer ( ) sums the attenuated first QPSK signal with a second QPSK signal. The second QPSK signal is outputted from a second QPSK device of the two QPSK devices. The summer outputs a predistorted 12/4-QAM signal. The plurality of modulator control bit control the at least one phase shift devices and the two QPSK modulators to achieve the desired points on the 12/4 QAM constellation.

Efficient pre-distorted 12/4 QAM modulator

A communication subsystem ( ) for transmitting error correction coded data in packets ( ) includes an input buffer ( ) storing unencoded data, a product coder ( ) coupled to the input buffer, and a time division transmitter ( ). The product coder ( ) outputs product coded data packets ( ) having a packet size, and the time division transmitter ( ) transmits the product coded data packets ( ) in a data section ( ) of a frame ( ). The data section ( ) has a length substantially equal to an integer multiple of the packet size. The communication subsystem ( ) may use a (s, t)&times;(n, m) product code specifically adapted to product code 53 byte ATM cells. A method for communicating error correction coded data in packets includes storing unencoded data in an input buffer ( ), product coding the unencoded data ( ), and outputting product coded data packets ( ) having a packet size. The method also includes time division transmitting ( ) the coded data packets in a data section ( ) of a frame ( ) where the data section length is substantially equal to an integer multiple of the packet size.

Burst and packet wireless transmission using product codes with iterative decoding

A ground terminal renders feasible a communications system that locates two satellites at the same node along the geostationary arc. Each satellite is capable of receiving RF signals through an uplink channel and transmitting RF signals through a downlink channel distinct from the uplink channels. The ground terminal is able to transmit RF signals to only one of the satellites, but can receive RF signals from both of the satellites. The ground terminal includes an antenna, an RF signal processor that includes two demodulators for processing signals from the two downlink channels, and a data processor.

Dual receive ground terminal for use in communication systems utilizing multiple satellites

A communications system includes two satellites located at the same node along the geostationary arc each capable of receiving RF signals through an uplink channel and transmitting RF signals through a downlink channel distinct from the uplink channels. At least two user terminals are in the system, with each user terminal able to transmit RF signals to only one of the satellites, but at least one of the user terminals is able to receive RF signals from both of the satellites.

Communication system utilizing multiple satellites without intersatellite crosslinks

A method and apparatus utilizing unbalanced modulation for providing users in a communication system with different amounts of effective communication energy according to their individual communication environments. A user's communication energy needs are determined based on conditions such as weather, signal-to-noise ratio, and cell location. Signals destined for a user are modulated according to the determined needs of the user. A signal destined for a user operating in a relatively friendly communication environment is modulated with less effective energy than a signal destined for a user operating in a relatively hostile communication environment.

Unbalanced quadrature waveform

An adaptive transceiver architecture which reallocates communications resources in real time based on the amount of bandwidth being used in communications channels in the system. The transceiver receives communications signals from a plurality of communications beam spots. Each communications beam spot has a predefined bandwidth divided into non-overlapping subbands. The transceiver further comprises a plurality of front end signal conditioners for receiving communications signals from an equal plurality of communications beam spots. A predetermined number of the conditioned signals are then combined by an interconnect. The interconnect receives composite signals from the front end signal conditioners, and it combines at least first and second communications signals from first and second respective composite signals to form an output processing signal. The first and second communications signals are received by the receiver from first and second communications beam spots, respectively, and the first and second composite signals are output from the first and second corresponding front end signal conditioners.

Adaptive transceiver architecture for real time allocation of communications resources in a satellite based telecommunication system

A dual phased array payload (,) for use onboard a communications satellite is disclosed. The payload includes one or more phased array receive antennas (,) including numerous individual receiving elements distributed in a predetermined configuration. Each of the individual radiating elements is selectively adjustable in amplitude and phase to achieve scanning beams for receiving information transmitted from the ground in an uplink beam. The payload includes a packet switch (,) connected to the phased array receive antennas (,). The packet switch (,) includes a set of inputs and a set of outputs. The set of inputs are selectively connectable to the set of outputs. The payload (,) includes one or more phased array transmit antennas (,) connected to the packet switch (,). The phased array transmit antennas (,) include numerous individual radiating elements distributed in a predetermined configuration.

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Redondo Beach, CA, United States of America

Harvey L Berger