Abstract: 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.

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 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: 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.

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: 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.

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 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: 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.

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.