Abstract: Aspects of the present disclosure include methods for communication using a MIMO channel, such as an acoustic channel for underwater communication. An acoustic receiver may receive a signal comprising information encoded in at least one transmitted symbol. Using a two-layer iterative process, the at least one transmitted symbol is estimated. The first layer of the two-layer process uses iterative exchanges of soft-decisions between an adaptive turbo equalizer and a MAP decoder. The second layer of the two-layer process uses a data-reuse procedure that adapts an equalizer vector of both a feedforward filter and a serial interference cancellation filter of the adaptive turbo equalizer using a posteriori soft decisions of the at least one transmitted symbol. After a plurality of iterations, a hard decision of the bits encoded on the at least one transmitted symbol is output from the MAP decoder.

Abstract: Aspects of the present disclosure include methods for communication using a MIMO channel, such as an acoustic channel for underwater communication. An acoustic receiver may receive a signal comprising information encoded in at least one transmitted symbol. Using a two-layer iterative process, the at least one transmitted symbol is estimated. The first layer of the two-layer process uses iterative exchanges of soft-decisions between an adaptive turbo equalizer and a MAP decoder. The second layer of the two-layer process uses a data-reuse procedure that adapts an equalizer vector of both a feedforward filter and a serial interference cancellation filter of the adaptive turbo equalizer using a posteriori soft decisions of the at least one transmitted symbol. After a plurality of iterations, a hard decision of the bits encoded on the at least one transmitted symbol is output from the MAP decoder.

Abstract: Systems and methods for underwater communication using a MIMO acoustic channel. An acoustic receiver may receive a signal comprising information encoded in at least one transmitted symbol. Using a two-layer iterative process, the at least one transmitted symbol is estimated. The first layer of the two-layer process uses iterative exchanges of soft-decisions between an adaptive turbo equalizer and a MAP decoder. The second layer of the two-layer process uses a data-reuse procedure that adapts an equalizer vector of both a feedforward filter and a serial interference cancellation filter of the adaptive turbo equalizer using a posteriori soft decisions of the at least one transmitted symbol. After a plurality of iterations, a hard decision of the bits encoded on the at least one transmitted symbol is output from the MAP decoder.

Abstract: Systems and methods for underwater communication using a MIMO acoustic channel. An acoustic receiver may receive a signal comprising information encoded in at least one transmitted symbol. Using a two-layer iterative process, the at least one transmitted symbol is estimated. The first layer of the two-layer process uses iterative exchanges of soft-decisions between an adaptive turbo equalizer and a MAP decoder. The second layer of the two-layer process uses a data-reuse procedure that adapts an equalizer vector of both a feedforward filter and a serial interference cancellation filter of the adaptive turbo equalizer using a posteriori soft decisions of the at least one transmitted symbol. After a plurality of iterations, a hard decision of the bits encoded on the at least one transmitted symbol is output from the MAP decoder.

Abstract: Systems and methods for underwater communication using a SISO acoustic channel. An acoustic receiver may receive a signal comprising information encoded in at least one transmitted symbol. Using a Bi-SDFE, the at least one transmitted symbol is estimated. The Bi-SDFE may include a SDFE and a time-reversed SDFE that each output bit extrinsic LLRs, which are combined into combined bit extrinsic LLRs. The estimated symbol is then mapped to the combined bit extrinsic LLRs, the result of which is de-interleaved. Iterative bit extrinsic LLRs are generated with a MAP and/or soft-decision decoder using the mapped, combined bit extrinsic LLRs as a priori LLRs for the Bi-SDFE in another iterative estimation. The iterative bit extrinsic LLRs are interleaved and transmitted for use by the Bi-SDFE in another iterative estimation. After a plurality of iterations, a hard decision of the transmitted symbol is generated with the MAP and/or soft-decision decoder.

Abstract: A method and an apparatus for detecting data symbols of a multiple-phase-shift-keying (MPSK) modulated slot used for radio reception of digital data are disclosed. The method and apparatus simultaneously accomplish signal equalization and symbol detection. A simplified algorithm is used which is sub-optimal but closely approximates an optimal solution which significantly reduces computational load. A solution vector is constructed and data symbol values in the solution vector are perturbated. After each perturbation, a solution error is computed to determine whether the perturbated value provides a better solution. Perturbation continues until an optimal solution is found or a maximum number of iterations have been performed. The advantage is an improved, cost-effective radio receiver which enables faster wireless data transfer.

Abstract: The present invention relates to a method and an apparatus for compensating a signal that has experienced fading distortion in a communication channel. The signal that can be a TDMA (Time Division Multiple Access) signal includes slots that carry data symbols. Non-uniformly spaced pilot symbols are also embedded in the slot structure. The receiver separates the incoming symbols stream in two parts namely a pilot symbols stream and data symbols stream. Since the transmitted pilot symbols are known, an estimate of the channel distortion on the pilot symbols locations can be computed. This estimate is then interpolated to provide an estimate of the fading distortion at the data symbols locations, thus allowing to compensate accurately for the fading distortion in the channel.

Abstract: For a hierarchical mobile cellular communications system comprising a plurality of microcells and overlaid macrocells, a method is disclosed for estimating the speed of a mobile. The speed estimate assists in the assignment of slow-moving mobiles to microcells and fast-moving mobiles to macrocells, thus keeping the cellular system in optimum utilization. The method first calculates a power signal of the received signals. The power signal is then filtered and decimated. The speed of a mobile is estimated from a determination of the offset autocorrelation of the filtered and decimated power signal.