Cohda Wireless Pty Ltd.

Myriota Pty Ltd

University of South Australia

Agere Systems Inc.

Cohda Wireless

Alexander James Grant

David Victor Lawrie Haley

Robert George McKilliam

Paul Dean Alexander

William George Cowley

John Lawrence Buetefuer

Andre Pollok

Gottfried Lechner

Ingmar Rudiger Land

Linda Mary Davis

Stephen Peter Jakas

Robert George Mckilliam

Marc Pierre Denis Lavenant

Sorin Adrian Barbulescu

Lars Kildehoj Rasmussen

Ho Leung Chan

Joshua Charles Sutton

Ricky Rocco Luppino

Wade Nicholas Farrell

Ivan Curtis

Graeme Woodward

Malik Khan

Adriel P Kind

Paul Kingsley Gray

Ying Chen

Jayant Baliga

David Victor Haley

Phuc Ngoc Pham

Martin Suter

Nick Letzepis

John L Buetefuer

Ying Cheng

Andre Pollock

Ian Anthony Curtis

A multiple access slotted wireless communication system comprising a plurality of terminals and a multi-access receiver is described. The multi-access receiver can decode multiple transmissions in each slot of a frame from terminals in its field of view. Each terminal has an active state for transmitting and an inactive state. After receiving acknowledgement of a successful transmission by the terminal, the terminal enters the inactive state for at least a transmission delay time. This may be the remaining time that the terminal is in the field of view of the multi-access receiver. This may be achieved by the terminal using a probability of transmission to determine whether or not to transmit in the next frame. The terminal may also be configured to select the slot in a frame, and this may be based upon information such as which slots were acknowledged. The receiver may use compression to transmit acknowledgement messages.

Multi-access communication system

The invention relates to method and apparatus for improving the performance of communication systems using Run length Limited (RLL) messages such as the existing Automatic Identification System (AIS). A binary data sequence is Forward Error Correction (FEC) coded and then the sequence is compensated, for example by bit-erasure, so that either bit-stuffing is not required, or a bit stuffer will not be activated to ensure that the coded sequence meets the RLL requirement. Various embodiments are described to handle different architectures or input points for the FEC encoder and bit erasure module. The bit erasure module may also add dummy bits to ensure a RLL compliant CRC or to selectively add bits to a reserve buffer to compensate for later bit stuffing in a header. Additional RLL training sequences may also be added to assist in, receiver acquisition.

Enhanced automatic identification system

A multiuser communication system comprises multiple transmitters and a multiuser receiver that detects multiple transmissions via iterative soft interference cancellation. An initial acquisition module and single user decoder module are also described. The multiuser receiver acquires and subtracts known users in the residual signal before acquiring new users in the residual signal, which is performed iteratively until no new users are detected or a stopping criterion is met. To aid receiver acquisition, the transmitters insert discrete tones into the transmitted signals. These allow the multiuser receiver to obtain initial estimates of the frequency, time, gain, and/or phase offset for each user. To improve the quality of cancellation the receiver refines estimates of gain, time, frequency and phase offsets for each user after each iteration, and calculates time varying SINR estimates for each user. The multiuser receiver may be satellite based, may be a distributed receiver, or process users in parallel.

Multiuser communications system

A method for estimating the position of a terminal in a satellite communication at either the ground station or in the satellite is described. The method uses estimates of the time delay, Doppler and/or Doppler Rate of signals transmitted from the terminal to the satellite together with an estimate of the satellite position. The method can be used with both synchronised terminals and unsynchronised terminals provided they have a stable time or frequency reference as well as with low earth orbit satellites both with and without on-board global position and timing references. Additionally the method can also use estimates of the time delay, Doppler or Doppler rate of beacon signals received by either the satellite or terminals. These beacon signals may include GPS L1 signals. In contrast to standard GPS receivers, the method does not require the terminal to store GPS ephemeris data or to operate continuously.

Position estimation in a low earth orbit satellite communications system

A method and system for generating extended satellite ephemeris data for a satellite for use by a terminal apparatus is described. Historical orbital parameter data (e.g. from historical TLEs) are used to build a predictor for future values of the orbital parameters. The orbital parameter prediction model is then stored on the terminal apparatus (or an existing model can be updated), and at a desired epoch the pre-stored orbital parameter predictor is used to produce estimates of the orbital parameters for the satellite for that epoch (ie synthetic or predicted TLEs). These predicted orbital parameters (predicted TLE) are then used as input to a standard orbit predictor to produce an estimate of the satellite's location, for example to determine satellite pass times. This method allows generation satellite ephemeris data which is valid out to a year or more as compared to the normal validity of ephemeris data of a few hours or days.

System and method for generating extended satellite ephemeris data

A method is for communicating by tracking time varying channels in a multiple access packet based communication network. Each packet includes a preamble portion including a data symbol, and a data portion including data symbols. The method may include initializing a channel estimate reference from an initial channel estimate based upon the data symbol in a preamble portion of a received packet, and updating the channel estimate reference based upon a channel estimate of a current data symbol and a previously received data symbol from the data symbols in a data portion of the received packet. The method may also include repeating the updating upon receipt of a subsequent data symbol from the data symbols in the data portion of the received packet.

Filter structure for iterative signal processing

A communication system is disclosed. In an embodiment, the communication system includes a user node for receiving data from a remote application program, the data including message data for communication to a central application program operatively associated with the remote application program; plurality of geographically distributed gateway nodes; one or more access nodes for receiving the message data from the user node via a first communications interface, and communicating the message data via a second communications interface to one or more of the plurality of geographically distributed gateway nodes; and a hub for communicating with the one or more of the plurality of geographically distributed gateway nodes to receive the message data for communication to the central application.

Communication system and method

A method of scheduling wake up times for terminals in a satellite communication system using satellite ephemeris data in order to extend battery life of terminals is described. The terminal periodically evaluates the stored ephemeris data to determine whether it is valid, recently valid, or invalid. When the ephemeris data is valid the terminal can schedule wake up times to either transmit or receive updated ephemeris data. For recently valid ephemeris data the terminal calculates possible satellite pass windows and schedules wake up time. For invalid data the terminal wakes and listens periodically with a period that is less than the expected satellite pass duration. It may repeat this process several times before sleeping for an amount of time less than the expected satellite pass duration and repeating. Additional gateway beacons may be used to provide ephemeris data, and satellites may also provide information on beacon locations.

Terminal scheduling method in satellite communication system

A vehicle or other mobile communication entity () locates objects using received (typically radio frequency) signals (). These received signals included multi-path versions of the transmitted signals (). The received signals may include packets having location information of the transmission source. The receiving vehicle may track, or know, its own position. The receiving entity may determine properties for a multi-path version of the signal (). These properties may include a delay, a Doppler and an angle of reception () for one or more multi-path versions of the received signal. The receiving entity may also measure an imbalance () induced between a pair (or more) of antenna elements () for a particular multi-path version of the signal received. This imbalance may be dependent on the angle of arrival of the particular signal being received. In some embodiments of the invention, the measured imbalance includes two parts: a delta phase (dPhase,) and a delta Gain (dGain,). These delta values may be considered as a complex number with phase dPhase and magnitude dGain.

Passive radar location of objects

Methods and apparatus for communication between terminals and an access node in a multiuser multicarrier communications network are described. The access node may be a satellite access node. Terminals are configured to perform initial estimation and tracking of channel offsets and to estimate channel offsets for future packets to be transmitted by the terminal. In some embodiments the channel offsets comprise mobility related channel offsets due to the relative movement between the access node and the plurality of terminals. Transmissions from the terminals to the access node are pre-compensated for the channel offsets, so that the aggregate signal received by the access node occupies a bandwidth greater or equal to the maximum signal bandwidth of any individual terminal. Terminal transmissions may overlap in frequency and time on the ground, but arrive orthogonally at the access node.

Multicarrier communications system

The invention relates to method and apparatus for improving the performance of communication systems using Run Length Limited (RLL) messages such as the existing Automatic Identification System (AIS). A binary data sequence is Forward Error Correction (FEC) coded and then the sequence is compensated, for example by bit-erasure, so that either bit-stuffing is not required, or a bit stuffer will not be activated to ensure that the coded sequence meets the RLL requirement. Various embodiments are described to handle different architectures or input points for the FEC encoder and bit erasure module. The bit erasure module may also add dummy bits to ensure a RLL compliant CRC or to selectively add bits to a reserve buffer to compensate for later bit stuffing in a header. Additional RLL training sequences may also be added to assist in, receiver acquisition.

Growing community of inventors

Adelaide, Australia

Alexander James Grant