Showing papers on "Concatenation published in 2001"

On the foundations of measurement

Abstract: The paper relates novel theories of one-dimensional measurement and scale type to earlier theories. A paper by J. Barzilai ( see ibid., p.395-400) presents definitions, notation, and further details regarding these new theories. The following areas are covered: inadequacy of the homomorphic model; terminology and notation; scale type; concatenation and Holder's axioms; and the foundations of decision theory.

VLSI architectures for iterative decoders in magnetic recording channels

Abstract: VLST implementation complexities of soft-input soft-output (SISO) decoders are discussed. These decoders are used in iterative algorithms based on Turbo codes or Low Density Parity Check (LDPC) codes, and promise significant bit error performance advantage over conventionally used partial-response maximum likelihood (PRML) systems, at the expense of increased complexity. This paper analyzes the requirements for computational hardware and memory, and provides suggestions for reduced-complexity decoding and reduced control logic. Serial concatenation of interleaved codes, using an outer block code with a partial response channel acting as an inner encoder, is of special interest for magnetic storage applications.

Computing the free distance of turbo codes and serially concatenated codes with interleavers: algorithms and applications

Abstract: We present a new algorithm for computing the free distance d/sub free/ of parallel and serially concatenated codes with interleavers, the parameter that dominates the code performance at very high signal-to-noise ratios (SNRs). The knowledge of d/sub free/ allows one to analytically estimate the error floor, which may prevent the use of concatenated codes in applications requiring very low error rates. The algorithm is based on the new notion of constrained subcodes, and permits the computation of large distances for large interleavers without a constraint on the input sequence weight (e.g., up to d/sub free/=40 for a rate-1/3 turbo code with interleaver length N=3568). Applications to practical cases of relevant interest, i.e., (1) the new Consultative Committee for Space Data Systems (CCSDS) standard for deep-space telemetry and (2) the new UMTS/3GPP standard for third-generation personal communications, are presented for the first time. Other related aspects, like a study on the free distance distribution of turbo codes with small/medium interleaver length, and a comparison between parallel and serial concatenation behavior, are also discussed.

Synthesis unit selection apparatus and method, and storage medium

Abstract: Input text data undergoes language analysis to generate prosody, and a speech database is searched for a synthesis unit on the basis of the prosody. A modification distortion of the found synthesis unit, and concatenation distortions upon connecting that synthesis unit to those in the preceding phoneme are computed, and a distortion determination unit weights the modification and concatenation distortions to determine the total distortion. An Nbest determination unit obtains N best paths that can minimize the distortion using the A* search algorithm, and a registration unit determination unit selects a synthesis unit to be registered in a synthesis unit inventory on the basis of the N best paths in the order of frequencies of occurrence, and registers it in the synthesis unit inventory.

Fast waveform synchronization for concatenation and time-scale modification of speech

Abstract: A synthesis method for concatenative speech synthesis is provided for efficiently concatenating waveform segments in the time-domain. A digital waveform provider produces an input sequence of digital waveform segments. A waveform concatenator concatenates the input segments by using waveform blending within a concatenation zone to synchronize, weight, and overlap-add selected portions o the input segments to produce a single digital waveform. The synchronizing includes determining a minimum weighted energy anchor in the selected portion of each input segment and aligning synchronization peaks in a local vicinity of each anchor.

Methods and apparatus for communicating changes between a user interface and an executing application using property paths

Abstract: In one aspect the invention relates to a method of associating an element of a user-interface to a current state of a property in a system including an application having a plurality of components, wherein at least one component has a property, wherein each property is identified with an identifier. The method comprises associating the element of the user-interface with a property path, the property path including a concatenation of a plurality of identifiers, the concatenation of identifiers defining a path through the components of the application to a property at the end of the concatenation, and mapping the property path to a current state of the property at the end of the path defined by the concatenation of identifiers, to associate the element of the user-interface with the current state of that property.

Moments of Opportunity: Recognizing Conditions of Ripeness for International Mediation between Enduring Rivals

Abstract: Some points in time are more favorable for mediation success than others and result from the concatenation of contextual factors that encourage movement toward more cooperative behavior by disputan...

Turbo-encoder design for symbol-interleaved parallel concatenated trellis-coded modulation

Abstract: This paper addresses turbo-encoder design for coding with high spectral efficiency using parallel concatenated trellis-coded modulation and symbol interleaving. The turbo-encoder design involves the constituent encoder design and the interleaver design. The constituent encoders are optimized for symbol-wise effective free distance, and each has an infinite symbol-wise impulse response. We identify the canonical structures for the constituent encoder search space. In many cases of practical interest, the optimal structure for these constituent encoders connects the memory elements in a single row. This single row generally applies to turbo code constituent encoders for parallel concatenation and is not restricted to symbol interleaving. To lower the error floor, a new semi-random interleaver design criteria and a construction method extends the spread-interleaver concept introduced by Divsalar and Pollara (1995). Simulation results show that the proposed system employing symbol interleaving can converge at a lower signal-to-noise ratio than previously reported systems. We report simulation results between 0.5 and 0.6 db from constrained capacity for rates of 2 and 4 bits/s/Hz.

Joint iterative decoding of serially concatenated error control coded CDMA

Abstract: Joint iterative decoding of multiple forward error control (FEC) encoded data streams is studied for linear multiple access channels, such as code-division multiple access (CDMA). It is shown that such systems can be viewed as serially concatenated coding systems, and that iterative soft-decision decoding can be performed successfully To improve power efficiency, powerful FEC codes are used. These FEC codes are themselves serially concatenated. The overall transmission system can be viewed as the concatenation of two error control codes with the linear multiple access channel, and soft-decision decoders are used at each stage. A variance transfer function approach applied to the analysis of this system captures the role of the component decoders in an overall iterative decoding system. We show that this approach forms a methodology to study the effects of the component codes as well as that of the iteration schedule. Analysis and simulation examples are presented for transmission systems that operate close to the Shannon limit and illustrate the accuracy of the analysis.

Nitroglycal Concatenation: A Broadly Applicable and Efficient Approach to the Synthesis of Complex O-Glycans.

Abstract: Base-catalyzed glycosylations provide the basis for a new and general entry to the synthesis of mucin-type O-glycans. The desired α-linked 2-acetamidoglycosyl amino acids B are accessible selectively starting from glycals of type A. Fmoc=9-fluorenylmethoxycarbonyl.

Control of spectral dynamics in concatenative speech synthesis

Abstract: Current speech synthesis methods based on the concatenation of waveform units can produce highly intelligible speech capturing the identity of a particular speaker. However, the quality of concatenated speech often suffers from discontinuities between the acoustic units, due to contextual differences and variations in speaking style across the database. In this paper, we present methods to spectrally modify speech units in a concatenative synthesizer to correspond more closely to the acoustic transitions observed in natural speech. First, a technique called "unit fusion" is proposed to reduce spectral mismatch between units. In addition to concatenation units, a second, independent tier of units is selected that defines the desired spectral dynamics at concatenation points. Both unit tiers are "fused" to obtain natural transitions throughout the synthesized utterance. The unit fusion method is further extended to control the perceived degree of articulation of concatenated units. A signal processing technique based on sinusoidal modeling is also presented that enables high-quality resynthesis of units with a modified spectral shape.

A very low bit rate speech coder based on a recognition/synthesis paradigm

Abstract: Previous studies have shown that a concatenative speech synthesis system with a large database produces more natural sounding speech. We apply this paradigm to the design of improved very low bit rate speech coders (sub 1000 b/s). The proposed speech coder consists of unit selection, prosody coding, prosody modification and waveform concatenation. The encoder selects the best unit sequence from a large database and compresses the prosody information. The transmitted parameters include unit indices and the prosody information. To increase naturalness as well as intelligibility, two costs are considered in the unit selection process: an acoustic target cost and a concatenation cost. A rate-distortion-based piecewise linear approximation is proposed to compress the pitch contour. The decoder concatenates the set of units, and then synthesizes the resultant sequence of speech frames using the harmonic+noise model (HNM) scheme. Before concatenating units, prosody modification which includes pitch shifting and gain modification is applied to match those of the input speech. With single speaker stimuli, a comparison category rating (CCR) test shows that the performance of the proposed coder is close to that of the 2400-b/s MELP coder at an average bit rate of about 800-b/s during talk spurts.

Trajectory Control and Interconnection of 1D and nD Systems

Abstract: In this paper we examine the relationship between control viewed as concatenation of trajectories and control viewed as interconnection of systems. We show that, for one-dimensional linear time-invariant systems, the ability to obtain a given subsystem by regular interconnection (a prerequisite for any feedback-type structure) is equivalent to the ability to drive any trajectory into that subsystem. However, in the case of multidimensional systems, the former is a stronger property than the latter. Trajectory controllability can, however, be expressed as a regular interconnection of behaviors in an extended variable space by introducing latent or auxiliary variables. This leads as a by-product to the notion of controlling a system by means of latent variables.

Removing linear phase mismatches in concatenative speech synthesis

Abstract: Many current text-to-speech (TTS) systems are based on the concatenation of acoustic units of recorded speech. While this approach is believed to lead to higher intelligibility and naturalness than synthesis-by-rule, it has to cope with the issues of concatenating acoustic units that have been recorded at different times and in a different order. One important issue related to the concatenation of these acoustic units is their synchronization. In terms of signal processing this means removing linear phase mismatches between concatenated speech frames. This paper presents two novel approaches to the problem of synchronization of speech frames with an application to concatenative speech synthesis. Both methods are based on the processing of phase spectra without, however, decreasing the quality of the output speech, in contrast to previously proposed methods. The first method is based on the notion of center of gravity and the second on differentiated phase data. They are applied off-line, during the preparation of the speech database without, therefore, any computational burden on synthesis. The proposed methods have been tested with the harmonic plus noise model, HNM, and the TTS system of AT&T Labs. The resulting synthetic speech is free of linear phase mismatches.

Concatenative speech synthesis using a finite-state transducer

Abstract: A method for concatenative speech synthesis includes a processing stage that selects segments based on their symbolic labeling in an efficient graph-based search, which uses a finite-state transducer formalism. This graph-based search uses a representation of concatenation constraints and costs that does not necessarily grow with the size of the source corpus thereby limiting the increase in computation required for the search as the size of the source corpus increases. In one application of this method, multiple alternative segment sequences are generated and a best segment sequence is then be selected using characteristics that depend on specific signal characteristics of the segments.

Toward fault-tolerant quantum computation without concatenation

Abstract: It is known that quantum error correction via concatenated codes can be done with exponentially small failure rate if the error rate for physical qubits is below a certain accuracy threshold. Other, unconcatenated codes with their own attractive features such as improved accuracy threshold, local operations, have also been studied. By iteratively distilling a certain two-qubit entangled state it is shown how to perform an encoded Toffoli gate, important for universal computation, on codes whose C-NOT operation is bitwise. For certain codes, over a very large range of block sizes, this technique requires at most one concatenation.

Convergence properties of iterative decoders working at bit and symbol level

Abstract: We compare the convergence thresholds of parallel and serially concatenated codes with interleaver that employ iterative decoding algorithms working at bit or symbol level. The analysis technique is an extension to that of the symbol-level decoder presented by S. ten Brink (see Electron. Lett., vol.35, no.10, p.806-8, 1999), and is valid for very large interleavers. The comparison shows that working at symbol level always yields a lower convergence threshold. In the serial concatenation, the advantage is quite significant.

Methods and apparatus for creating a user interface using property paths

Abstract: The invention relates to a system for creating a user-interface independently of an application with which the user interface interacts, wherein the application includes a plurality of components and at least one component (34) contains a property (38), wherein each property is identified with an identifier. The system includes a property connector module (22) to insert at least one element (46) into the user-interface (42), and to associate at least one property path with one inserted element (46), the property path including a concatenation of a plurality of identifiers, the concatenation of identifiers defining a path through the components (34) of the application to a property (38) at the end of the concatenation. A client node can include the user interface having one or more elements, and a client portion (22a) of the property connector module. A server node can include the application, and a server portion (22b) of the property connector module.

Concatenated nucleic acid sequences

Abstract: An in vitro method for constructing a concatenated head-to-tail repertoire of target nucleic acid sequences is revealed. In particular, the method relates to cycles of concatenation whereby after a single cycle of concatenation, not more than two identical copies of each target nucleic acid sequences are linked together head-to-tail on the same molecule of DNA. The present method ensures that each molecule of a concatenated repertoire is derived from a single template target sequence of the starting repertoire.

VLSI architectures for high-speed MAP decoders

Abstract: Soft-in/soft-out building blocks are becoming increasingly important in present and future communication systems as they enable better communications performance. The maximum a posteriori (MAP) algorithm is the best known soft-in/soft-out decoder: its performance is superior to the soft-out Viterbi algorithm (SOVA). However optimized high-speed MAP decoder implementation is widely unexplored. We present a novel VLSI high-speed MAP architecture with optimized memory size and power consumption suitable for decoding the revolutionary "Turbo-Codes" and related concatenation schemes. The architecture is highly scalable with respect to throughput, expanding its applicability over a wide range of throughput requirements (300 Mbit/s-45 Gbit/s and above). An in-depth design space exploration on multiple abstraction levels has been carried out. Area and power consumption are significantly reduced compared to the state-of-the-art.

Turbodecoding method with re-encoding of erroneous information and feedback

Abstract: A method of improving turboencoding by re-encoding erroneous information and subtracting their contribution at the input of the turboencoder. The subtraction of this contribution remedies the lack of convergence or convergence towards erroneous solutions observed in certain turbodecoding configurations. The method also applies to parallel concatenation turbodecoding, to serial concatenation turbodecoding, or to block turbodecoding. Different operations result according to the type of feedback envisaged.

Differential turbo space-time coding

Abstract: Serial concatenation of standard convolutional or block codes with differential space-time modulation is considered for flat fading multiple antenna channels. Extrinsic information transfer is used to predict thresholds for various outer codes. Using the differential structure of the inner code near coherent performance is obtained without the use of training symbols.

Concatenated code system design for storage channels

Abstract: A number of papers have been published on the concatenation of an outer code with a partial response (PR) channel, where the outer code is a turbo code, a convolutional code, or a low-density parity-check code. This paper deals with the second case, assuming EPR4 and modified extended EPR4 (MEEPR4) partial response (PR) targets. The goals in this work include (1) the joint optimization of interleaver and precoder for a fixed outer convolutional code and PR target, (2) the choice of optimal code rate for both PR targets assuming a Lorentzian model, and (3) an assessment of the performance of these codes in the presence of thermal asperities. We introduce mathematical and algorithmic tools for accomplishing these goals and present simulation results that support our approach. Among the positive results is the ability to lower the well-known error rate floor of these concatenated schemes for arbitrary PR channels.

Phonetic effects on listener detection of vowel concatenation.

Abstract: Concatenative speech synthesis quality depends in part on the minimization of audible discontinuities between two successive concatenated units. This study focuses on human detection of concatenation discontinuities in synthetic speech. Statistical analyses compared for various phonetic categories the results observed in perceptual tests with two voices – one female and one male. Neither a comprehensive phonetic analysis nor a comparison of discontinuity detection between voices has been reported previously. Although discontinuities were generally more detectable for the female than the male voice, there were many similarities between results obtained from the two speakers. A reliably higher rate of detection of discontinuities was observed for diphthongs than for monophthong vowels. Post-vocalic consonants influenced concatenation discontinuities significantly more than pre-vocalic consonants, and postvocalic sonorants were associated with higher detection rates than post-vocalic non-sonorants. The differences in discontinuity detection among vowels and among consonantal contexts for both voices consistently suggest that highly audible discontinuity is related to concatenation in regions of spectral change.

On turbo equalization of interleaved space-time codes

Abstract: Space-time coding over frequency selective time-varying fading channels is considered. The approach is based on deploying bit/symbol interleaved space-time codes. Decoding is based on the iterative concatenation of a soft-in soft-out MIMO equalizer with a soft-in soft-out decoder. The equalizer structure comprises a bank of matched filters followed by a maximum a posteriori processor with an appropriate metric. It does not require multiple receive antennas. Methods to reduce its complexity are devised. Finally, performance results are shown for ST bit-interleaved convolutional codes designed for the EDGE air interface with two transmit-single receive antennas.

Restoration by path concatenation: fast recovery of MPLS paths

Abstract: A new general theory about restoration of network paths is first introduced. The theory pertains to restoration of shortest paths in a network following failure, e.g., we prove that a shortest path in a network after removing k edges is the concatenation of at most k + 1 shortest paths in the original network.The theory is then combined with efficient path concatenation techniques in MPLS (multi-protocol label switching), to achieve powerful schemes for restoration in MPLS based networks. We thus transform MPLS into a flexible and robust method for forwarding packets in a network.Finally, the different schemes suggested are evaluated experimentally on three large networks (a large ISP, the AS graph of the Internet, and the full Internet topology). These experiments demonstrate that the restoration schemes perform well in actual topologies.

Transmit virtual concatenation processor

Abstract: A transmit virtual concatenation processor for multiplexing channelized data onto a SONET/SDH frame is disclosed. The processor is sealable and is able to handle mapping a number of data channels to a number of different frame sizes including STS-12, STS-48, STS-192 and STS-768. The processor supports virtual concatenation with arbitrary channel mapping at bath STS-1 and STS-3c granularities. The processor also supports contiguous concatenation with STS-12c, STS-24c, STS-48c, STS-192, etc-capacities (i.e., STS-Nc where N is a multiple of 3). In addition, the processor supports mixed concatenation where some channels are using contiguous concatenation and some other channels are using STS-3c-Xv virtual concatenation. Alternatively, the processor is able to support any virtual concatenation, any contiguous concatenation and any mixed concatenation. The processor terminates the H1, H2 and H3 bytes in the line overhead of a SONET/SDH frame and inserts the multi-frame indicator and sequence number in the H4 byte of the path overhead.

Inter-vehicle spread spectrum communication and ranging system with concatenated EOE sequence

Abstract: Proposes a method for designing spread sequences for a spread spectrum (SS) communication and ranging system. The proposed sequence is composed by concatenated equivalently odd and even (EOE) inner-sequences and an M outer sequence. We have previously proposed EOE sequences that have equivalently good properties of both even and odd correlation, what are important features for acquisition and demodulation in SS communications. Usually, simple concatenation of pseudonoise-sequences results in sequences with bad autocorrelation properties. Unlike the latter, concatenation of EOE inner sequences result in sequences with good correlation properties, exhibiting low sidelobe peaks, what is useful for achieving stable acquisition. The proposed sequences have long period. Therefore, the single concatenated EOE sequence is suitable for a spread spectrum system with both communication and ranging functions.

Turbo greedy multiuser detection

Abstract: Previously, a novel scheme for iterative multiuser detection and turbo decoding was proposed by Damnjanovic and Vojcic (2000, 2001). In this scheme, multiuser detection and single-user turbo decoding are tightly coupled to maximize the overall gain. The extrinsic probabilities for the coded bits of the interfering users, obtained after each turbo decoding iteration, are used as a priori probabilities in the following multiuser iteration and the extrinsic information for the systematic bits of the desired user is used as a priori information in the next single-user turbo decoding iteration. Turbo decoding of parallel concatenated convolutional codes is carried out in parallel fashion. It has been shown that the proposed detector approaches the multiuser capacity limit within 1 dB in the low signal-to-noise ratio region. However, the main drawback of the scheme is its exponential complexity in the number of users, which is due to the complexity of the maximum a posteriori probability (MAP) multiuser detector. In this paper, we show that the complexity of the scheme can be significantly reduced by replacing the (MAP) multiuser detector with an iterative detector derived from the greedy multiuser detector proposed by AlRustamani and Vojcic (2000). In this paper, we demonstrate that, for both the additive white Gaussian noise and the frequency-nonselective Rayleigh fading, the substantial reduction in complexity of the iterative scheme proposed by Damnjanovic and Vojcic when the greedy detector is utilized introduces a slight degradation in performance.