Showing papers on "Concatenation published in 2008"

Optimization of enzymatic biochemical logic for noise reduction and scalability: how many biocomputing gates can be interconnected in a circuit?

Abstract: We report an experimental evaluation of the "input-output surface" for a biochemical AND gate. The obtained data are modeled within the rate-equation approach, with the aim to map out the gate function and cast it in the language of logic variables appropriate for analysis of Boolean logic for scalability. In order to minimize "analog" noise, we consider a theoretical approach for determining an optimal set for the process parameters to minimize "analog" noise amplification for gate concatenation. We establish that under optimized conditions, presently studied biochemical gates can be concatenated for up to order 10 processing steps. Beyond that, new paradigms for avoiding noise buildup will have to be developed. We offer a general discussion of the ideas and possible future challenges for both experimental and theoretical research for advancing scalable biochemical computing.

Optimization of Enzymatic Biochemical Logic for Noise Reduction and Scalability: How Many Biocomputing Gates Can Be Interconnected in a Circuit?

Abstract: We report an experimental evaluation of the "input-output surface" for a biochemical AND gate. The obtained data are modeled within the rate-equation approach, with the aim to map out the gate function and cast it in the language of logic variables appropriate for analysis of Boolean logic for scalability. In order to minimize "analog" noise, we consider a theoretical approach for determining an optimal set for the process parameters to minimize "analog" noise amplification for gate concatenation. We establish that under optimized conditions, presently studied biochemical gates can be concatenated for up to order 10 processing steps. Beyond that, new paradigms for avoiding noise build-up will have to be developed. We offer a general discussion of the ideas and possible future challenges for both experimental and theoretical research for advancing scalable biochemical computing.

System and Methods for Receiving OFDM Symbols Having Timing and Frequency Offsets

Abstract: Systems and methods for receiving an OFDM preamble without knowledge of channel characteristics are provided. An OFDM preamble signal with frequency shifted cyclic extensions is received. Taken together the cyclic extensions form a frequency shifted version of the OFDM preamble signal. Frequency offsets and timing offsets are estimated and corrected in an efficient manner using a simple concatenation approach in the time domain, followed by a summation of the OFDM preamble signal and the concatenation after a transformation of the OFDM preamble and the concatenation into the frequency domain. Phase errors in the frequency domain are estimated and corrected after FFT transformations of the received signals. A valid preamble is detected and additional parameters for receiving subsequently transmitted OFDM symbols in a channel are extracted from the OFDM preamble. The methods are computationally efficient and robust. Receiver implementations for performing the methods in a DVB receiver are disclosed.

Efficient FEC for Optical Communications using Concatenated Codes to Combat Error-floor

Abstract: We propose concatenated LDPC(9252,7967)+RS(992,956) codes for application to systems beyond 40 Gb/s, taking practical implementation into account. Simulation shows that the Q limit is 7.1 dB, and that the concatenation effectively suppresses unwanted error-floor.

Conveyance of concatenation properties and picture orderness in a video stream

Abstract: Systems and methods that provide a video stream including a first video sequence followed by a second video sequence, and that provide a first information in the video stream pertaining to pictures in the first video sequence, wherein the location of the first information provided in the video stream is in relation to a second information in the video stream, wherein the second information pertains to the end of the first video sequence, wherein the first information in the video stream corresponds to a first information type and the second information in the video stream corresponds to a second information type different than the first information type, and wherein the first information corresponds to auxiliary information.

Operational State Complexity of Nested Word Automata.

Abstract: We introduce techniques to prove lower bounds for the number of states needed by finite automata operating on nested words. We study the state complexity of Boolean operations and obtain lower bounds that are tight within an additive constant. The results for union and complementation differ from corresponding bounds for ordinary finite automata. For reversal and concatenation, we establish lower bounds that are of a different order than the worst-case bounds for ordinary finite automata.

Scrambling methods for synchronization channels

Abstract: Systems and methods are provided that facilitate generation and detection of synchronization channels in a wireless communication system. A one-to-one relationship is established among a set of scrambling codes (SCs) and a set of primary synchronization channel (P-SCH) sequences which are determined by a reusable sector identifier that is determined through detection of the P-SCH channel. The set of scrambling codes are utilized to (i) scramble a secondary synchronization channel sequence which facilitates detection of the S-SCH sequence once the reusable sector identifier is detected, or (ii) compose an unscrambled S-SCH sequence through a sequential or interleaved concatenation of SCs wherein a concatenation indication is received in a mobile terminal. Cyclic shifts and sign-flip operations applied to a base sequence are employed to generate SCs. A lookup table and a library of SCs facilitate scrambling code determination in a mobile terminal that receives associated P-SCH and S-SCH sequences.

Packet concatenation at the IP level for performance enhancement in wireless local area networks

Abstract: Wireless local area networks experience performance degradation in presence of small packets The main reason for that is the large overhead added at the physical and link layers This paper proposes a concatenation algorithm which groups IP layer packets prior to transmission, called PAC-IP As a result, the overhead added at the physical and the link layers is shared among the grouped packets Along with performance improvement, PAC-IP enables packet-based fairness in medium access as well as includes QoS support module handling delay-sensitive traffic demands The performance of the proposed algorithm is evaluated through both simulations and an experimental WLAN testbed environment covering the single-hop and the widespread infrastructure network scenarios Obtained results underline significant performance enhancement in different operating scenarios and channel conditions

Concatenated codes can achieve list-decoding capacity

Abstract: We prove that binary linear concatenated codes with an outer algebraic code (specifically, a folded Reed-Solomon code) and independently and randomly chosen linear inner codes achieve the list-decoding capacity with high probability. In particular, for any 0 0, there exist concatenated codes of rate at least 1 -- H(ρ) -- e that are (combinatorially) list-decodable up to a fraction ρ of errors. (The best possible rate, aka list-decoding capacity, for such codes is 1 -- H(ρ), and is achieved by random codes.) A similar result, with better list size guarantees, holds when the outer code is also randomly chosen. Our methods and results extend to the case when the alphabet size is any fixed prime power q ≥ 2. Our result shows that despite the structural restriction imposed by code concatenation, the family of concatenated codes is rich enough to include capacity achieving list-decodable codes. This provides some encouraging news for tackling the problem of constructing explicit binary list-decodable codes with optimal rate, since code concatenation has been the preeminent method for constructing good codes over small alphabets.

Channel coding as a cryptography enhancer

Abstract: In this work, channel decoding is considered as a promising way for improvement of cryptographic functions. Use of MAC/H-MAC values and digital signatures is analyzed in a context of code concatenation, together with convolutional codes using MAP decoding algorithm. Soft Input Decryption method, which uses L-values from channel decoder, presents an efficient method for integrating cryptography into decoding. The results of computer simulations that implement this method have been also presented. Additionally, the number of L-values verifications has been tested and compared with the theoretical results.

H-index concatenation

Abstract: A method for the calculation of a ‘concatenated’ h-index of jointly ranked combined bibliographies is presented in the case when only size and h-index of the original publication sets are known.

Toward Better Chroma Subsampling: Recipient of the 2007 SMPTE Student Paper Award

Abstract: Chroma subsampling is a lossy process often compounded by concatenation of dissimilar techniques. This paper surveys common subsampling applications providing examples of the advantages and disadvantages of various approaches. It also outlines a novel chroma upsampling technique that minimizes erroneous out-of-gamut colors.

Reverse Concatenation with Maximum Transition Run (MTR) Codes for High-Density Perpendicular Recording

Abstract: We present a reverse concatenation (RC) architecture with maximum transition run (MTR) modulation codes and Reed-Solomon (RS) error-correction codes (ECCs). The scheme employs a high-rate primary (pre-RS) MTR code and a secondary (post-RS) MTR code, which controls error propagation. The two modulation codes are designed in such a way to maximize the overall code rate and maintain simple hardware implementation. Simulation results demonstrate superior performance compared to reverse concatenation with non-MTR codes, especially at a relatively high recording density.

Correctable noise of quantum-error-correcting codes under adaptive concatenation

Abstract: We examine the transformation of noise under a quantum error correcting code (QECC) concatenated repeatedly with itself, by analyzing the effects of a quantum channel after each level of concatenation using recovery operators that are optimally adapted to use error syndrome information from the previous levels of the code. We use the Shannon entropy of these channels to estimate the thresholds of correctable noise for QECCs and find considerable improvements under this adaptive concatenation. Similar methods could be used to increase quantum fault tolerant thresholds.

A geometric analysis of trajectory design for underwater vehicles

Abstract: Designing trajectories for a submerged rigid body motivates this paper. Two approaches are addressed: the time optimal approach and the motion planning approach using a concatenation of kinematic motions. We focus on the structure of singular extremals and their relation to the existence of rank-one kinematic reductions; thereby linking the optimization problem to the inherent geometric framework. Using these kinematic reductions, we provide a solution to the motion planning problem in the under-actuated scenario, or equivalently, in the case of actuator failures. We finish the paper comparing a time optimal trajectory to one formed by a concatenation of pure motions.

A Coded Modulation Scheme for Deep-Space Optical Communications

Abstract: A coded modulation scheme for deep-space optical communications is studied, which is a serial concatenation of an outer low-density parity-check (LDPC) code, an interleaver, a bit-accumulator, and pulse-position modulation (PPM). It is referred as LDPC-APPM. It is decoded with an iterative demodulator-decoder using standard turbo-decoding techniques. Simulation results show that the LDPC-APPM with an outer LDPC code of medium code length suffers a loss of about 0.7 dB at a bit-error rate of relative to the serially concatenated PPM (SCPPM) of similar parameters, which consists of the serial concatenation of an outer convolutional code, an interleaver, a bit-accumulator, and PPM; however, it has better code rate flexibility especially for high rates and simpler implementation structure than SCPPM. Further, it can achieve better performance than the LDPC-PPM of the same rate and length, which consists of the serial concatenation of an LDPC code and PPM.

A family of asymptotically good quantum codes based on code concatenation

Abstract: We explicitly construct an infinite family of asymptotically good concatenated quantum stabilizer codes where the outer code uses CSS-type quantum Reed-Solomon code and the inner code uses a set of special quantum codes. In the field of quantum error-correcting codes, this is the first time that a family of asymptotically good quantum codes is derived from bad codes. Its occurrence supplies a gap in quantum coding theory.

Adaptive Frame Concatenation Mechanisms for QoS in Multi-Rate Wireless Ad Hoc Networks

Abstract: Providing quality of service (QoS) to users in a wireless ad-hoc network is a key concern for service providers. With the availability of multiple rates in IEEE 802.11a/b/g wireless LANs, it is desirable to improve the network capacity and temporal fairness by sending multiple consecutive frames (also referred as frame concatenation mechanism) over high rate links, as proposed in opportunistic auto rate (OAR). However, OAR does not consider the effect of frame sizes and may yield unsatisfactory performance for high priority multimedia flows transmitting over low rate links. Therefore, a more appropriate frame concatenation strategy and a corresponding service differentiation scheme should be devised to provide better performance for high priority voice/video flows than low priority data flows, under various channel rate scenarios. In this paper, we first analyze the effect of frame size on the performance of OAR. Then, we propose a general concatenation mechanism (GCM), a more accurate frame concatenation mechanism for multi-rate MAC with better fairness. Finally, we propose two mechanisms: adaptive weighted fair frame concatenation mechanism (AWFCM) and adaptive QoS aware frame concatenation mechanism (AQCM), for supporting service differentiation and QoS in multi-rate wireless ad hoc networks. The primary idea is to adjust the number of concatenated frames based on flow weights/priorities, frame sizes, link rates, and network traffic. Simulation results show that the proposed mechanisms achieve desirable performance on supporting multimedia applications in multi-rate wireless ad-hoc networks.

Reverse Concatenation of Product and Modulation Codes

Abstract: Reverse concatenation (RC) architectures, which recently have been deployed in hard-disk-drive (HDD) products, offer crucial advantages in coding such as (i) avoiding error propagation through the modulation decoder, (ii) allowing the use of efficient high-rate modulation codes, and (iii) passing of soft information from the detector to the decoder, which facilitates parity-post processing and iterative coding schemes. In HDDs, error-correcting codes essentially consist of a single high-rate Reed-Solomon code, whereas in tape recording, large product codes are used that require a new RC architecture. Such a novel RC architecture for product codes is presented and illustrated by an example based on the linear tape open standard, generation 4 (LTO-4). Compared with the rate-16/17 modulation code of the LTO-4 standard, the proposed RC scheme has a modulation scheme of rate 0.9951, i.e., achieves 5.7% improvement in rate while maintaining the same interleaved I = 11 modulation constraint, but at the cost of a slight weakening of the G-constraint.

Concatenated eIRA Codes for Tamed Frequency Modulation

Abstract: A new scheme of the extended irregular repeat- accumulate (eIRA) coded tamed frequency modulation (TFM) for deep space communications is introduced in this paper. It is mainly based on the optimal concatenation of the eIRA code and the continuous phase encoder (CPE) decomposed from TFM. In order to obtain good performance of the eIRA coded TFM, the main principle of our scheme is to jointly optimize the concatenation by eliminating the short loops in the Tanner graph of the eIRA code and the coding part of TFM and to jointly decode between them. Then our scheme without interleaving and the contrast scheme with interleaving are simulated in an additive white Gaussian noise (AWGN) channel which is typical in deep space communications. Simulation results have shown that our scheme can obtain lower complexity and less decoding delay (due to the reduction of interleaving) at the cost of just 0.1-0.15 dB performance loss when compared to the scheme with interleaving given bit-error-ratio (BER) of 10 5. Therefore, our scheme can be used to implement the coded TFM system for deep space communications with good performance and low complexity.

Novel Words with Final Combining Forms in English. A Case for Blends in Word Formation

Abstract: Morphological theories that assume all word formation to consist in concatenation of morphemes run into difficulties stating the defining properties of the notion of final combining forms that can be used as constituents of novel words. The novel words under consideration are of two types: (a) nouns ending in forms like -ology, -ography, -ometer, -crat, -naut, -phile; (b) nouns ending in forms like -(a)holic, -(a)thon. Forms of type (b) are only roughly identifiable due to their indeterminable size of segmental material. In this paper the notion of final combining form is called into question and ultimately rejected on the grounds that words allegedly built with final combining forms of type (b), when analysed within the theory of universal, ranked and violable constraints in its OO Correspondence version, conform to the defining properties of blends.

Applications of Diamonded Double Negation

Abstract: Nested complementation plays an important role in expressing counteri.e. star-free and first-order definable languages and their hierarchies. In addition, methods that compile phonological rules into finite-state networks use double-nested complementation or “double negation”. This paper reviews how the double-nested complementation extends to a relatively new operation, generalized restriction (GR), coined by the author (Yli-Jyra and Koskenniemi 2004). This operation encapsulates a double-nested complementation and elimination of a concatenation marker, diamond, whose finite occurrences align concatenations in the arguments of the operation. The paper demonstrates that the GR operation has an interesting potential in expressing regular languages, various kinds of grammars, bimorphisms and relations. This motivates a further study of optimized implementation of the operator.

Spell Out Your Sister

Abstract: On the pages below the idea of intermodular argumentation is promoted. The article is a follow-up on Scheer (forth b), where Phase Impenetrability (PIC) was discussed along these lines. The subject matter of the present paper is what is known as the phase edge in current syntactic theory (both contributions are pieces of Scheer forth a). The minimalist focus on the interface has afforded a radical change in generative interface architecture. Since the 60s (Chomsky 1965:15ff), the inverted T model stands unchallenged (the generative semantics interlude lain aside): a concatenative device (morpho-syntax) feeds two interpretative devices, PF and LF. This architecture was supplemented with a proviso which requires that all concatenation be done before any interpretation. That is, the morpho-syntactic derivation is completed, and the result (S-structure) is then sent to PF and LF in one go. An alternative view of the communication between morpho-syntax and LF/PF was formulated in phonology in the early 80s: the backbone of Lexical Phonology (e.g. Kiparsky 1982), so-called interactionism, holds that concatenation and interpretation are intertwined. That is, first some pieces are merged, the result is interpreted, then some more pieces are concatenated, the result is again interpreted and so on. While GB-syntax of that time hardly produced any echo, generative orthodoxy in phonology reacted on this violation of "all concatenation before all interpretation": Halle & Vergnaud (1987) proposed a non-interactionist version of Lexical Phonology that restores the interface landscape of SPE to a large extent. Halle & Vergnaud (1987) also promote a new idea: selective spell-out. Since cyclic derivation was introduced by Chomsky et al. (1956:75) and formalized in Chomsky & Halle (1968:15ff), interpretation was held to run through the bracketed string (that is inherited from Sstructure) from inside out; (roughly) every morpheme break defined a cycle. Halle & Vergnaud dispense with this definition of what an interpretational unit is: they propose to grant cyclic status only to a subset of morpho-syntactic divisions. That is, some nodes trigger interpretation, others do not. The reader will have understood that selective spell-out is exactly what modern (syntactic) phase theory is about: in more familiar terminology, nodes may or may not be phase heads, hence their material may or may not be an interpretational unit. As far as I can see, the phonological heritage is left unmentioned in the syntactic literature since derivation by phase was introduced in Uriagereka (1999) and Chomsky (2000,2001 et passim). This is also true for interactionism: Uriagareka's multiple spell-out and Chomsky's derivation by phase make the generative interface architecture interactionist, exactly along the lines that Lexical Phonology had laid out: first you do some concatenation, then some interpretation, then some more concatenation etc. For (extra-linguistic) reasons of computational economy regarding the limited availability of active memory, a costly cognitive resource (e.g. Chomsky 2000:101, 2001:15), modern phase theory applies the interactionist world view. Here again, the phonological origin of the idea has gone unnoticed as far as I can see (let alone the anti-interactionist reaction of generative orthodoxy in the 80s). Elsewhere (Scheer forth b) I examine a question that is closely related to selective spell-out and interactionism: critical for current syntactic phase theory is a device which guarantees that previously interpreted strings do not burden further computation – in Chomsky's terms, strings that are returned from interpretation are "frozen" and "forgotten" when concatenation resumes. The history of no look-

Accurate visual speech synthesis based on diviseme unit selection and concatenation

Abstract: This paper presents a novel speech driven accurate realistic visual speech synthesis approach. Firstly, an audio visual instance database is built for different viseme context combinations, i.e. diviseme units, using 100 audio visual speech sentences of a female speaker. Then a diviseme instance selection algorithm is introduced to choose the optimal diviseme instances for the viseme contexts in the input speech, considering both the concatenation smoothness of the image sequences, and matching of the mouth movements to the acoustic pronunciation process, as well the intensity of the input speech. Finally mouth image sequences of corresponding viseme segments in the selected diviseme instances are time warped and blended to construct the mouth images of the final animation. Visual speech synthesis experiments and subjective evaluation results show that mouth animations can be obtained which are not only realistic with clear and smooth mouth images, but also in good accordance with the acoustic pronunciation and intensity of the input speech.

Speech driven realistic mouth animation based on multi-modal unit selection

Abstract: This paper presents a novel audio visual diviseme (viseme pair) instance selection and concatenation method for speech driven photo realistic mouth animation. Firstly, an audio visual diviseme database is built consisting of the audio feature sequences, intensity sequences and visual feature sequences of the instances. In the Viterbi based diviseme instance selection, we set the accumulative cost as the weighted sum of three items: 1) logarithm of concatenation smoothness of the synthesized mouth trajectory; 2) logarithm of the pronunciation distance; 3) logarithm of the audio intensity distance between the candidate diviseme instance and the target diviseme segment in the incoming speech. The selected diviseme instances are time warped and blended to construct the mouth animation. Objective and subjective evaluations on the synthesized mouth animations prove that the multimodal diviseme instance selection algorithm proposed in this paper outperforms the triphone unit selection algorithm in Video Rewrite. Clear, accurate, smooth mouth animations can be obtained matching well with the pronunciation and intensity changes in the incoming speech. Moreover, with the logarithm function in the accumulative cost, it is easy to set the weights to obtain optimal mouth animations.

Cross-virtual concatenation for Ethernet-over-SONET/SDH networks

Abstract: Ethernet-over-SONET/SDH (EoS) is a popular approach for interconnecting geographically distant Ethernet segments using a SONET/SDH transport infrastructure. It typically uses virtual concatenation (VC) for dynamic bandwidth management. The aggregate SONET/SDH bandwidth for a given EoS connection is obtained by “concatenating” a number of equal-capacity virtual channels. Together, these virtual channels form a virtually concatenated group (VCG). In this article, we introduce a new concatenation technique, referred to as cross-virtual concatenation (CVC), which involves the concatenation of virtual channels of heterogeneous capacities. We show that CVC can be implemented through a simple upgrade at the end node, thus utilizing the existing legacy SDH infrastructure. By employing CVC for EoS systems, we show that the SDH bandwidth can be harvested more efficiently than in conventional VC. We consider two problems associated with routing CVC connections: the connection establishment problem and the connection upgrade problem. The goal of the first problem is to compute a set of paths between two EoS end systems such that a total bandwidth demand and a constraint on the differential delay between the paths are satisfied. Among all feasible sets, the one that consumes the least amount of network bandwidth is selected. For this problem, we develop an integer linear program (ILP) and an efficient algorithm based on the sliding-window approach. For the connection upgrade problem, the goal is to augment an existing set of paths so as to increase the aggregate bandwidth, while continue to meet the differential-delay constraint. We model this problem as a flow-maximization problem with a constraint on the delay of the virtual channels with positive flow. We then consider the problem of path selection under imprecise network state information. Simulations are conducted to demonstrate the advantages of employing CVC and to evaluate the performance of the proposed algorithms.

An Improved Method for the Convergence of Iterative Detection in Turbo-CPM System

Abstract: Concatenated coding schemes with interleavers consist of a combination of two simple constituent encoders and an interleaver. The parallel concatenation known as "turbo code" has been shown to yield remarkable coding gains close to theoretical limits, yet admitting a relatively simple iterative decoding technique. Serially concatenated convolutional code (SCCC) proposed by S.Benedetto may offer performance superior to that of turbo codes. In order to solve the problem of positive feedback during iterative detection of short data frame SCCC system, a method based on weighed extrinsic information exchange is proposed. Theoretic analysis and simulation results in additive white Gaussian noise (AWGN) show that the proposed method can prevent the phenomena of positive feedback from taking place, reduce the error floor, and improve the convergence of iterative detection and the performance of bit error rate (BER).

Performance of unary bulk IO operations on virtual disks by interleaving

Abstract: A method and system are provided for executing a unary bulk input/output operation on a virtual disk using interleaving. The performance improvement due to the method is expected to increase as more information about the configuration of the virtual disk and its implementation are taken into account. Performance factors considered may include contention among tasks implementing the parallel process, load on the storage system from other processes, performance characteristics of components of the storage system, and the virtualization relationships (e.g., mirroring, striping, and concatenation) among physical and virtual storage devices within the virtual configuration.