Abstract: The invention relates to an encoding system and method for generating concatenated codes which utilize interleaving and data puncturing. The method includes selecting first and second puncture location sets defining desired puncture locations in non-interleaved and interleaved data sequences, respectively. A puncture-constrained interleaver is provided, which permutes the first puncture location set into the second puncture location set, so as to provide desired regular puncture patterns for all constituent codes. In a preferred embodiment, the puncture-constrained interleaving alters a symbol location relative to a puncture mask so as to satisfy a pre-defined spread or distance constraint.

Abstract: The invention relates to an encoding system and method for generating concatenated codes which utilize interleaving and data puncturing. The method includes selecting first and second puncture location sets defining desired puncture locations in non-interleaved and interleaved data sequences, respectively. A puncture-constrained interleaver is provided, which permutes the first puncture location set into the second puncture location set, so as to provide desired regular puncture patterns for all constituent codes. In a preferred embodiment, the puncture-constrained interleaving alters a symbol location relative to a puncture mask so as to satisfy a pre-defined spread or distance constraint.

Abstract: An interleaver for interleaving a set of K ordered elements is disclosed herein. The disclosed interleaver can be expressed as a single permutation that corresponds to two local dithering operations and a global permutation operation. The single permutation can be represented as a small collection of short vectors, and can be calculated recursively, allowing the interleaver to be both stored and implemented using a smaller amount of memory than conventionally possible.

Abstract: A system and method are provided for designing high-spread, high-distance interleavers for turbo-codes. The first approach is called high-spread random interleaving, and is based on a new and more effective definition of interleaver spread. The second approach is called dithered-diagonal interleaving. Both methods can be used to design interleaves of arbitrary length. The second approach can actually achieve the theoretical maximum spread for many specific block sizes, and at the same time include significant dither for the elimination of low-weight codewords. Both design methods are easy to implement and require very little processing. Also provided is a method for modifying any interleaver to improve the distance spectrum for a specific turbo-code. It is shown that, for a block size of only 512 data bits and for a code rate of ⅓, the flares in the packet error rate (PER) and bit error rate (BER) curves can be kept below 10−8 and 10−10, respectively.

Abstract: Digital signals transmitted on an RF carrier modulated in phase and amplitude and subject to noise constitute separate bursts each comprising information symbols of data and a pair of separated unique words. The signals are subjected to processing which involves reception of the signals and an initial conversion to approximate baseband and then analog to digital sampling. Quadrature and in phase samples are then stored in a buffer. The buffered samples are subjected to coarse timing, coarse frequency synchronization, a first phase correction, fine timing, further phase and amplitude correction and finally to fine frequency correction and subsequent reliability estimation.

Abstract: A method of creating tail-biting recursive systematic convolutional and turbo codes, and the associated encoders, are described herein. According to the method, symbols from the set of data to be transmitted are used to preset the starting state of the encoder, and are replaced in a systematic set by an equivalent number of tail-biting symbols that force the ending state of the encoder to be the same as the starting state. The presetting of the starting state allows for simpler calculations in choosing the tail-biting symbols, and allows a message to be transmitted with a reduced number of symbols The reduction in the number of symbols used for overhead in this invention provides an increase in the data transmission rate.

Abstract: An interleaver for interleaving a set of K ordered elements is disclosed herein. The disclosed interleaver can be expressed as a single permutation that corresponds to two local dithering operations and a global permutation operation. The single permutation can be represented as a small collection of short vectors, and can be calculated recursively, allowing the interleaver to be both stored and implemented using a smaller amount of memory than conventionally possible.

Abstract: Methods of reduced-complexity max-log-APP processing are disclosed for use with Turbo and Turbo-like decoders. The invented methods of decoding are derived from max-log-APP processing and significantly lower the processing required for decoding convolutional codes by eliminating a portion of the calculations conventionally associated with max-log-APP processing. The disclosed embodiments provide simplified methods of metric combining based on determining the bits of an MLSE sequence with different alternative approaches. Also disclosed is an early stopping method that uses the reduced-complexity max-log-APP decoder to reduce the average number of decoding operations required by an iterative Turbo decoder.

Abstract: A simplified method of history handling for the Viterbi decoding of convolutional codes is described herein. The state number, or one or more of the most-significant bits of the state number, is loaded into the corresponding state history. Each state number represents the sequence of data bits that, in convolutional encoding, would give rise to the corresponding state. The most recent data bit provides the least significant bit of the state number. This invention reduces the processing requirements associated with the handling of the history, and is especially useful for decoder implementations using general-purpose processors.

Abstract: A system and method are provided for designing high-spread, high-distance interleavers for turbo-codes. The first approach is called high-spread random interleaving, and is based on a new and more effective definition of interleaver spread. The second approach is called dithered-diagonal interleaving. Both methods can be used to design interleaves of arbitrary length. The second approach can actually achieve the theoretical maximum spread for many specific block sizes, and at the same time include significant dither for the elimination of low-weight codewords. Both design methods are easy to implement and require very little processing. Also provided is a method for modifying any interleaver to improve the distance spectrum for a specific turbo-code. It is shown that, for a block size of only 512 data bits and for a code rate of ⅓, the flares in the packet error rate (PER) and bit error rate (BER) curves can be kept below 10−8 and 10−10, respectively.

Abstract: Interleavers based on golden-section increments are disclosed for use with Turbo and Turbo-like error-correcting codes. The interleavers have a tendency to maximally spread the error-bursts generated by an error-burst channel or decoder, independent of the error-burst length. The code block size uniquely defines a golden section increment without having to perform a time consuming search for the best increment value. The disclosed embodiments include golden relative prime interleavers, golden vector interleavers and dithered golden vector interleavers. Also disclosed are methods to reduce the size of memory required for storing the interleaving indexes.

Abstract: A block decision feedback equalizer uses a Cholesky algorithm to factor a channel impulse response correlation matrix in order to solve for data received over a dispersive communications channel. While the Cholesky algorithm increases the computational complexity of the initial data symbol estimate (the result of a linear block estimation), its use allows the employment of a recursive update for computing successive data symbols with little additional computation. Further, the Cholesky algorithm is free of limitations that would restrict detection to cases where the channel span or memory is smaller than the probe segment following the data block to be detected. Additional functions such as diversity combining, incorporation of a time-varying channel response model and fractional baud-period sampling are provided in the block detector.

Abstract: A system for transmitting FM signals comprised of apparatus for receiving an input data signal, apparatus for precompensating the received data signal, apparatus for applying the precompensated data signal to a constant envelope modulator to provide a modulated signal, apparatus for applying the modulated signal to a power efficient non-linear amplifier and transmitting a signal resulting therefrom, apparatus for receiving the transmitted signal in an I-Q receiver, and apparatus for filtering the received transmitted signal for the precompensation, to obtain an output data signal representative of the input data signal.

Abstract: A system for transmitting FM signals comprised of apparatus for receiving an input data signal, apparatus for precompensating the received data signal, apparatus for applying the precompensated data signal to a constant envelope modulator to provide a modulated signal, apparatus for applying the modulated signal to a power efficient non-linear amplifier and transmitting a signal resulting therefrom, apparatus for receiving the transmitted signal in an I-Q receiver, and apparatus for filtering the received transmitted signal for the precompensation, to obtain an output data signal representative of the input data signal.