Abstract: An interleaving apparatus comprises a first storing unit for storing data to be transmitted and a first control unit for controlling the first storing unit so that the data to be transmitted is outputted from the first storing unit with the data to be transmitted arranged in a matrix and at least either columns or rows of the data to be transmitted randomly rearranged, facilitating the interleaving. The result is that biased distribution of data, which leads to degradation of the transmission quality, can be prevented relatively easily in a simple structure.

Abstract: In an interleaver for use in a turbo decoder, a deinterleaver, or an interleaver for use in a turbo encoder, an offset is set based on previously determined thresholds in accordance with symbol numbers generated by a counter. A symbol numbers inputted immediately before generating an address is corrected with the set offset, and the corrected symbol number is converted to generate an interleave read address.

Abstract: A circuit for controlling the random character of a bit flow, including an input shift register receiving the bit flow and having its outputs exploited in parallel, at least one element for comparing at least a partial content of the input register with predetermined patterns, a plurality of counters in a number at most equal to the number of predetermined patterns, and an element for detecting the exceeding of at least one threshold by one of the counters, the result of this detection conditioning the state of a word or bit indicative of the random or non-random character of the bit flow.

Abstract: A method for interleaving data frames transmitted via a modem pool, each of the data frames including a plurality of codewords having a predefined level of error correction, including assigning the data frames to corresponding modem timeframes, where codeword symbols in each of the data frames are assigned to time slots in the modems in the corresponding timeframes such that the level of error correction is sufficient to correct error/loss caused to any of the symbols given a predefined level of modem loss/malfunction, and moving any of the codeword symbols assigned to one of the timeframes to another of the timeframes such that the level of error correction is sufficient to correct error/loss caused to any of the symbols given a predefined level of cross-modem error burst while preserving the level of error correction sufficient to correct error/loss caused to any of the symbols given the level of modem loss/malfunction.

Abstract: A process and apparatus is described for recovering from optical transmission degradation due to scintillation effects in optical free space. A payload bit stream is encoded into Reed-Solomon codewords. These are fragmented and distributed as interleaved segments over a cell matrix of a SDRAM buffer store which is made large enough to correct a burst error occurring over 20 million consecutive bits. The rate imbalance between conventional read vs. write operations for SDRAM devices, which would otherwise obviate their use in this application by preventing real time operation, is overcome by an address remapping that avoids having to changing page addresses each time SDRAM memory is referenced. The remapping facilitates a more nearly equal allocation of READ overhead and WRITE overhead. An optical communications system employs at both the transmit and receive ends, substantially equivalent SDRAM buffer with address remapping capability.

Abstract: A data packet type communication system utilizes packet framing wherein preambles are split into two or more subpreambles, separated by a number of data or a priori known symbols. A receiver chooses among individual and combined subpreamble options for determining synchronization. When a noise impulse prevents detection of one subpreamble, the impulse is detected, and preamble correlation proceeds using an unaffected subpreamble. When no impulse is detected, combined subpreambles are used.

Abstract: A communication system 100 employs turbo encoding having a turbo interleaver 106 that interleaves input data 101 efficiently with little use of system resources. The turbo interleaver 106 reads address locations of the data bits into an interleaver matrix array 206 row by row and interleaves the address locations by bit reversal of the row indexes with accompanying permutation of the corresponding address locations in the rows of the matrix 206, bit reversal of the column indexes with accompanying permutation of the corresponding address locations in the columns of the matrix 206 and shifting the address locations within each row a predetermined number of column locations based on the particular row number.

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: A memory-efficient convolutional interleaver/deinterleaver with a memory array, a write commutator, and a read commutator wherein the commutators perform their respective write and read operations relative to a preselected memory cell after a predetermined delay. The delay is chosen using a modulo-based technique, such that an efficient implementation of a Ramsey Type-II interleaver is realized.

Abstract: Encoded data having a small code word weighting are not output. In a step S21, a sequence p[i] (0≦i<N) is set so that there is no duplication in the values from 0 to (N−1), in a step S22, all positions for which specific substitution patterns are generated in the sequence p[i] are examined, the information is stored in the sequence r[i], and the sum of this information is set as TOTAL. The routine proceeds to a step S24, positions which do not generate specific substitution patterns, i.e., predetermined values j not contained in r[i] (0≦j<N), are randomly selected, and processing which replaces p[r[i]] by p[j] for all r[i] is performed.

Abstract: The decoding method to which the present invention relates takes into account: at least one predetermined polynomial, and a received sequence r capable of being the result of the coding of a sequence of information symbols of polynomial representation u(x) representing a physical quantity, the coding including a turbocoding, and guaranteeing the divisibility of a sequence to be turbocoded, a(x) representing the sequence u(x), by each predetermined polynomial, This method includes: an operation of turbodecoding (601) the received sequence r into an estimated sequence â, at least one operation of calculating the remainder (602, 606) of the division of the polynomial representation â(x) of the estimated sequence â, by a said predetermined polynomial.

Abstract: The invention relates to a method and arrangement for advantageously decoding and channel correcting a convolutionally encoded signal received over a transmission path. The signal comprises code words and the arrangement comprises a neural network comprising a set of neurons which comprise a set of inputs and an output. The received code words (400) and at least some of the output signals (402) of the neural network neurons are connected to the inputs of the neurons, and the neurons comprise means (404) for multiplying at least some of the neuron inputs prior to combining means (406). The arrangement also comprises means (123) for estimating the transmission channel. Further, estimated channel data (400) is connected to the inputs of the neurons and a predetermined neuron is arranged to give an estimate of the channel-corrected and decoded symbol in its output signal.

Abstract: In an apparatus such as a turbo decoding apparatus in which it is necessary to carry out interleave operation and deinterleave operation, there are provided a memory unit (5) and a memory control unit (12) capable of changing data writing order and data reading order with respect to the memory unit (5) depending on whether data is to be interleaved or deinterleaved. With this arrangement, the single unit of memory (5) can function as an interleaver and a deinterleaver, thereby reducing the size and cost the device.

Abstract: The present invention provides a system and method for explicitly transmitting a block attribute in the data of a block. In one embodiment, a current block of data is randomized in accordance with an ID value from the current block and from at least one temporally adjacent block of data. The ID of the current block is selected such that when combined with determined bits of the data results in the value of the block attribute. During a decoding process, the block attribute is retrieved by accessing the determined bits of the data. In one embodiment, the data is then decoded by generating possible candidate decodings and evaluating the candidate decodings based upon confidence metrics.

Abstract: A system for memory word error correction that enables correction of burst errors in memory words. The system is based on an adaptation of two-error correction BCH code which yields burst error correction without increasing the number of error correction bits in the memory words over prior two-error BCH code error correction schemes. The adaptation of two-error correction BCH code when combined with additional techniques for detecting columns of burst errors enables the correction of burst errors and additional random bit errors in memory words.

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 method and system for locating control channels, particularly digital control channels, are described. By grouping the channels which are candidates for carrying supervisory messages in blocks indicative of their relative likelihood for being used as control channels, a mobile station can begin its search for a control channel with channels which are most likely to actually be control channels. Placing location information on other channels allows the mobile station to be redirected to a control channel when it reads one of these other channels. Similarly, by placing information describing the location of a control channel in a message associated with handoff, a mobile station avoids the necessity of having to relocate a new control channel associated with the base station to which the mobile has been handed off.

Abstract: In an interleaver for use in a turbo decoder, a deinterleaver, or an interleaver for use in a turbo encoder, an offset is set based on previously determined thresholds in accordance with symbol numbers generated by a counter. A symbol numbers inputted immediately before generating an address is corrected with the set offset, and the corrected symbol number is converted to generate an interleave read address.

Abstract: The present invention provides a method, a computer medium, and a device for a two stage S_Random interleaver that is constructed based on two optimization criteria. The distance spectrum properties of the code are maximized by designing an interleaver that increases the minimum effective free distance of the code. In addition, the interleaver is designed to reduce the correlation properties of the extrinsic information that is fed into the next stage decoder. Thus, the present invention utilizes the reduced correlation properties to provide a more efficient S-random interleaver with increased iterations, thus maximizing the bit error rate (BER) performance of the code with respect to iterative decoding.

Abstract: The present invention provides a system and method for the time-varying randomization of a signal stream to provide for a robust error recovery. A current block of data is randomized in accordance with data from the current block and data from at least one temporally adjacent block of data. The present invention also provides a system and method for time-varying derandomization of a randomized signal stream and alternately delayed-decoding of the signal stream. Randomized data is derandomized using the current block of data and data from at least one temporally adjacent block. In addition, decoding of the current block and the adjacent block is delayed in order to facilitate recovery of lost or damaged compression parameters of encoded data.

Abstract: A novel and improved method and apparatus for address generation in an interleaver is provided. In accordance with one embodiment of the invention, an address is generated using a random address fragment and a bit reversed address fragment. The bit reversed address fragment is selected by first generating two consecutive candidate bit reversed fragments. The second bit reversed address fragment is selected when the first bit reversed address fragment generates an address that is greater than a maximum address. The address generator allows address generation for interleaver and deinterleaver frame sizes of N, where N is not an integer power of two, without any cycle penalty.

Abstract: An apparatus for encoding digital data for storage on a data storage medium includes a non-deterministic randomizer code generator. The randomizer code generator may select different randomizer codes for different portions of the data to be stored. The randomizer code used to randomize a given portion of the data may be stored on the media for use in subsequent data retrieval.

Abstract: Data is encoded to maximize subsequent recovery of lost or damaged compression constants of encoded data. In one embodiment, a compression constant is used to define a randomization pattern and the data is randomized using the randomization pattern. In one embodiment, a bit reallocation process and code reallocation process are performed on the data to randomize the data.

Abstract: A method and apparatus for coding an information signal are provided. In accordance with one aspect of the invention, the method includes the step of encoding all or a portion of the information signal with a first encoder to generate a first set of redundant bits (preferably r.sub.1 bits). The method further includes the step of passing a portion of (and possibly all) the information signal through a structured interleaver to generate an interleaved signal. The method then encodes all or a portion of the interleaved signal with a second encoder to generate a second set of redundant bits (preferably r.sub.2 bits). Finally, the method includes the step of concatenating the information signal, the first set of redundant bits, and the second set of redundant bits to form an encoded output signal. A significant aspect of the present invention is the use of a structured interleaver in the encoder.

Abstract: A source sequence of information symbols is encoded according to each of a plurality of codes to produce a plurality of encoded sequences of symbols, a respective one of the plurality of codes producing a respective one of the plurality of encoded sequences of symbols from the source sequence of information symbols. The plurality of encoded sequences of symbols are combined to produce a sequence of communications symbols. The sequence of communications symbols is processed to produce a communications signal which is then communicated over a communications medium. The communicated communications signal is processed to produce an estimate of the source sequence of information symbols. The source sequence is preferably encoded according to a first error correction code to produce a first encoded sequence of symbols, and encoded according to a second error correction code to produce a second encoded sequence of symbols.

Abstract: A machine guard has an opening with a detachable door; i.e., sliding tracks and hinges are not used for door support. When an outside loader arm and its part grippers move to the door, the door is unlatched from the guard and attached to the arm. The arm and grippers then move through the opening, taking the door away from the opening.