Abstract: Methods and systems for estimating range between a first device and a second device using at least one wireless communication channel defined between the first and second devices are disclosed. The method comprises: obtaining a set of range measurements, wherein the range measurements include measurements associated with multiple paths taken by signals between the first and second devices; discarding over-ranges caused by multiple signal paths using a variable threshold; and processing the remaining range measurements to obtain an estimated range.

Abstract: Disclosed herein is a method and system for determining plausibility of intelligent transport system (ITS) messages via a wireless communications channel at one or more message receivers. The method includes receiving a first ITS message having a first characteristic and receiving a second associated ITS message having a second characteristic. The method uses the first characteristic and the second characteristic to satisfy at least one predetermined criterion and determines plausibility of at least one of the first ITS message, the second ITS message and a third ITS message. The characteristic includes a PHY-layer or MAC-layer characteristic. The method is used to distinguish between genuine and spoofed messages to reduce the possibility of an attack.

Abstract: 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.

Abstract: Methods and systems for estimating the position of an object such (as a vehicle) are disclosed. The method comprises transmitting a first V2X message from the object to a plurality of spaced apart units; and receiving a set of V2X response messages from at least two units in response to the first V2X message. Each response message comprises an identifier of the object, an identifier of the unit from which the response message was sent, and temporal information associated with the times of receiving a previous V2X message at the unit and transmitting a previous V2X response message from the unit. The position of the object is estimated based on the information contained in the set of V2X response messages and the times of transmitting the previous V2X message from the object and receiving the previous set of V2X response messages at the object.

Abstract: 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.

Abstract: Methods and systems for estimating the position of an object such (as a vehicle) are disclosed. The method comprises transmitting a first V2X message from the object to a plurality of spaced apart units; and receiving a set of V2X response messages from at least two units in response to the first V2X message. Each response message comprises an identifier of the object, an identifier of the unit from which the response message was sent, and temporal information associated with the times of receiving a previous V2X message at the unit and transmitting a previous V2X response message from the unit. The position of the object is estimated based on the information contained in the set of V2X response messages and the times of transmitting the previous V2X message from the object and receiving the previous set of V2X response messages at the object.

Abstract: 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.

Abstract: Methods and systems for estimating range between a first device and a second device using at least one wireless communication channel defined between the first and second devices are disclosed. The method comprises: obtaining a set of range measurements, wherein the range measurements include measurements associated with multiple paths taken by signals between the first and second devices; discarding over-ranges caused by multiple signal paths using a variable threshold; and processing the remaining range measurements to obtain an estimated range.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Disclosed herein is a method and system for determining plausibility of intelligent transport system (ITS) messages via a wireless communications channel at one or more message receivers. The method includes receiving a first ITS message having a first characteristic and receiving a second associated ITS message having a second characteristic. The method uses the first characteristic and the second characteristic to satisfy at least one predetermined criterion and determines plausibility of at least one of the first ITS message, the second ITS message and a third ITS message. The characteristic includes a PHY-layer or MAC-layer characteristic. The method is used to distinguish between genuine and spoofed messages to reduce the possibility of an attack.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Methods and apparatus are described for improving receiver performance in a multicarrier communication network in which an encoded symbol is transmitted over a transmission channel in the communications system. A model of the transmission channel is estimated, said model characterising an effect of intercarrier interference on at least one carrier in the multicarrier system. The received symbol is decoded using the estimated model to remove a predicted effect of intercarrier interference. A pre-processor is also described for operation in conjunction with a communications receiver in the network. The pre-processor includes a channel estimator operable to estimate at least one feature of the communication channel based on a received signal. The pre-processor modifies the received signal dependent on the at least one estimated feature and provides the modified signal to the communications receiver.

Abstract: 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.

Abstract: Methods and apparatus are described for improving receiver performance in a multicarrier communication network in which an encoded symbol is transmitted over a transmission channel in the communications system. A model of the transmission channel is estimated, said model characterising an effect of intercarrier interference on at least one carrier in the multicarrier system. The received symbol is decoded using the estimated model to remove a predicted effect of intercarrier interference. A pre-processor is also described for operation in conjunction with a communications receiver in the network. The pre-processor includes a channel estimator operable to estimate at least one feature of the communication channel based on a received signal. The pre-processor modifies the received signal dependent on the at least one estimated feature and provides the modified signal to the communications receiver.