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T Aulin - One of the best experts on this subject based on the ideXlab platform.
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on analysis and design of low density generator matrix codes for Continuous Phase modulation
IEEE Transactions on Wireless Communications, 2007Co-Authors: Ming Xiao, T AulinAbstract:We investigate the analysis and design of low density generator matrix (LDGM) codes for Continuous Phase modulation (CPM). The system uses LDGM codes as an outer code for CPM. For additive white Gaussian noise channels, we derive the union bound to analyze the error floor performance. Design principles for lowering error floors are suggested from this analysis. We propose a design approach of jointly considering the LDGM code degree and the CPM modulation index. Then we consider the rate-adaptive system for slowly fading channels. By changing the rate of the LDGM codes, the information rate of the CPM signals is adapted according to channel variations. We use a low-rate LDGM code as the mother code. Higher rates are achieved by puncturing the output of these codes. To exploit the rate-flexible property of punctured LDGM codes, a rate function is proposed to calculate the rate of each transmitted block. Thus, we can have a quasi-Continuous information rate. Numerical results show that this approach can improve the energy efficiency from a discrete-rate adaptation. Using the rate-adaptive approach, up to 11 dB transmitted energy gain can be achieved from the non-adaptive scheme in the low bit-error-rate region (smaller than 10-3) for minimum shift keying (MSK).
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serially concatenated Continuous Phase modulation with symbol interleavers performance properties and design principles
European Transactions on Telecommunications, 2006Co-Authors: Ming Xiao, T AulinAbstract:Serially concatenated Continuous Phase modulation (SCCPM) systems with symbol interleavers are investigated. The transmitted signals are disturbed by additive white Gaussian noise (AWGN). Compared to bit interleaved SCCPM systems, this scheme shows a substantial improvement in the convergence threshold at the price of a higher error floor. In addition to showing this property, we also investigate the underlying reason by error event analysis. In order to estimate bit error rate (BER) performance, we generalise traditional union bounds for a bit interleaver to this non-binary interleaver. For the latter, both the order and the position of permuted non-zero symbols have to be considered. From the analysis, some principal properties are identified. Finally, some design principles are proposed. Our paper concentrates on SCCPM, but the proposed analysis methods and conclusions can be widely used in many other systems such as serially concatenated trellis coded modulation (SCTCM) et cetera. Copyright © 2006 AEIT
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serially concatenated Continuous Phase modulation with low density generator matrix codes property optimization and performance analysis
Information Theory Workshop, 2005Co-Authors: Ming Xiao, T AulinAbstract:We propose a new scheme of serially concatenated Continuous Phase modulation (SCCPM) by using nonsystematic low density generator matrix (LDGM) codes as the outer code. A property of the LDGM code degree is investigated. We use the exit chart/function to optimize the LDGM codes. The exit function of CPM with a fixed SNR (signal-to-noise-ratio) is shown. We derive the union bound to analyze the error floor performance. Design principles are proposed from the analysis process. Numerical results show that this scheme converge earlier (lower SNR) than previous SCCPM for iterative decoding.
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serially concatenated Continuous Phase modulation with symbol interleavers performance properties and design principles
Global Communications Conference, 2004Co-Authors: Ming Xiao, T AulinAbstract:Serially concatenated Continuous Phase modulation (SCCPM) systems with symbol interleavers are investigated. The transmitted signals are disturbed by additive white Gaussian noise (AWGN). Iterative detection with extrinsic information is used at the receiver side. Compared to bit interleaved SCCPM systems, this scheme shows a substantial improvement in convergence threshold at the price of a higher error floor. In addition to showing this property, we also investigate the underlying reason by error event analysis. In order to estimate bit error rate performance, we generalize traditional union bounds for a bit interleaver to the non-binary interleaver. For the latter, both the order and the position of permuted non-zero symbols have to he considered. From the analysis, some principal properties are presented. Finally some design principles are proposed. The paper concentrates on SCCPM, but the proposed analysis methods and conclusions can he widely used in many other systems such as serially concatenated trellis coded modulation, et cetera.
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serially concatenated Continuous Phase modulation with iterative decoding
Encyclopedia of Telecommunications, 2003Co-Authors: Par Moqvist, T AulinAbstract:Serially concatenated Continuous Phase modulation (SCCPM), or coded and interleaved CPM, is examined. Like turbo codes, SCCPM allows for iterative decoding based on a posteriori probability algorithms. The system is analyzed through an upper bound on the average bit error probability with maximum likelihood sequence detection, showing that SCCPM is capable of providing interleaver gain - and thus turbo-like performance - if a proper mapping of the CPM symbols is used. Simulations indicate that firstly, the analysis gives a satisfactory view of system performance when equal outer codes are used, and secondly, that remarkably good performance can be obtained with some simple systems. For unequal outer codes, the convergence of the iterative decoder will also have a significant effect on performance. Finally, a bandwidth/performance comparison of some selected systems shows that SCCPM can achieve large gains compared to the best known coded CPM systems without interleaving. Keywords: concatenated codes; serial concatenation; Continuous Phase modulation; iterative decoding; APP algorithm
Eric A Decker - One of the best experts on this subject based on the ideXlab platform.
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role of Continuous Phase anionic polysaccharides on the oxidative stability of menhaden oil in water emulsions
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Bingcan Chen, David Julian Mcclements, Eric A DeckerAbstract:The antioxidant role of selected polysaccharides was studied in the Continuous Phase of a Menhaden oil-in-water emulsion coated by polyoxyethylene(23) lauryl ether (Brij 35) at neutral pH. The addition of low-methoxyl (LM) and high-methoxyl (HM) pectin (0.02−0.1 wt %) reduced the formation of lipid hydroperoxides and thiobarbituric acid reactive substances with an inhibition that increased with increasing polysaccharide concentration in the Continuous Phase. α-Carrageenan and sodium alginate were less effective antioxidants than pectin and were prooxidative under certain conditions. None of the polysaccharides impacted the physical properties of the emulsions as determined by droplet particle size (d43 ∼ 0.32 μm) and creaming index. LM and HM pectins had higher iron-binding capacities as compared to α-carrageenan and sodium alginate, which may relate to their higher antioxidant activities. These results suggest that the addition of anionic polysaccharides to the Continuous Phase of oil-in-water emulsions ...
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antioxidant activity of cysteine tryptophan and methionine residues in Continuous Phase β lactoglobulin in oil in water emulsions
Journal of Agricultural and Food Chemistry, 2005Co-Authors: Ryan J Elias, Julian D Mcclements, Eric A DeckerAbstract:Proteins dispersed in the Continuous Phase of oil-in-water emulsions are capable of inhibiting lipid oxidation reactions. The antioxidant activity of these proteins is thought to encompass both free radical scavenging by amino acid residues and chelation of prooxidative transition metals; however, the precise mechanism by which this occurs remains unclear. In this study, the oxidative stability of cysteine, tryptophan, and methionine residues in Continuous Phase beta-lactoglobulin (beta-Lg) in a Brij-stabilized menhaden oil-in-water emulsion was determined. The presence of low concentrations of Continuous Phase beta-Lg (250 and 750 microg/mL) significantly inhibited lipid oxidation as determined by lipid hydroperoxides and thiobarbituric acid reactive substances analysis. It was observed that cysteine oxidized before tryptophan in beta-Lg, and both residues oxidized before lipid oxidation could be detected. No oxidation of the methionine residues of beta-Lg was observed despite its reported high oxidative susceptibility. It is conceivable that surface exposure of amino acid residues greatly affects their oxidation kinetics, which may explain why some residues are preferentially oxidized relative to others. Further elucidation of the mechanisms governing free radical scavenging of amino acids could lead to more effective applications of proteins as antioxidants within oil-in-water food emulsions.
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antioxidant activity of cysteine tryptophan and methionine residues in Continuous Phase β lactoglobulin in oil in water emulsions
Journal of Agricultural and Food Chemistry, 2005Co-Authors: Ryan J Elias, Julian D Mcclements, Eric A DeckerAbstract:Proteins dispersed in the Continuous Phase of oil-in-water emulsions are capable of inhibiting lipid oxidation reactions. The antioxidant activity of these proteins is thought to encompass both free radical scavenging by amino acid residues and chelation of prooxidative transition metals; however, the precise mechanism by which this occurs remains unclear. In this study, the oxidative stability of cysteine, tryptophan, and methionine residues in Continuous Phase β-lactoglobulin (β-Lg) in a Brij-stabilized menhaden oil-in-water emulsion was determined. The presence of low concentrations of Continuous Phase β-Lg (250 and 750 μg/mL) significantly inhibited lipid oxidation as determined by lipid hydroperoxides and thiobarbituric acid reactive substances analysis. It was observed that cysteine oxidized before tryptophan in β-Lg, and both residues oxidized before lipid oxidation could be detected. No oxidation of the methionine residues of β-Lg was observed despite its reported high oxidative susceptibility. It...
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role of Continuous Phase protein on the oxidative stability of fish oil in water emulsions
Journal of Agricultural and Food Chemistry, 2004Co-Authors: Habibollah Faraji, Julian D Mcclements, Eric A DeckerAbstract:Whey protein isolate (WPI), soy protein isolate (SPI), and sodium caseinate (CAS) can inhibit lipid oxidation when they produce a positive charge at the interface of emulsion droplets. However, when proteins are used to stabilize oil-in-water emulsions, only a fraction of them actually absorb to the emulsion droplets, with the rest remaining in the Continuous Phase. The impact of these Continuous Phase proteins on the oxidative stability of protein-stabilized emulsions is not well understood. WPI-stabilized menhaden oil-in-water emulsions were prepared by high-pressure homogenization. In some experiments WPI was removed from the Continuous Phase of the emulsions through repeated centrifugation and resuspension of the emulsion droplets (washed emulsion). Unwashed emulsions were more oxidatively stable than washed emulsions at pH 7.0, suggesting that Continuous Phase proteins were antioxidative. The oxidative stability of emulsions containing different kinds of protein in the Continuous Phase decreased in t...
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role of Continuous Phase protein on the oxidative stability of fish oil in water emulsions
Journal of Agricultural and Food Chemistry, 2004Co-Authors: Habibollah Faraji, Julian D Mcclements, Eric A DeckerAbstract:Whey protein isolate (WPI), soy protein isolate (SPI), and sodium caseinate (CAS) can inhibit lipid oxidation when they produce a positive charge at the interface of emulsion droplets. However, when proteins are used to stabilize oil-in-water emulsions, only a fraction of them actually absorb to the emulsion droplets, with the rest remaining in the Continuous Phase. The impact of these Continuous Phase proteins on the oxidative stability of protein-stabilized emulsions is not well understood. WPI-stabilized menhaden oil-in-water emulsions were prepared by high-pressure homogenization. In some experiments WPI was removed from the Continuous Phase of the emulsions through repeated centrifugation and resuspension of the emulsion droplets (washed emulsion). Unwashed emulsions were more oxidatively stable than washed emulsions at pH 7.0, suggesting that Continuous Phase proteins were antioxidative. The oxidative stability of emulsions containing different kinds of protein in the Continuous Phase decreased in the order SPI > CAS > WPI, as determined by both hydroperoxide and headspace propanal formation. Iron-binding studies showed that the chelating ability of the proteins decreased in the order CAS > SPI > WPI. The free sulfhydryls of both WPI and SPI were involved in their antioxidant activity. This research shows that Continuous Phase proteins could be an effective means of protecting omega-3 fatty acids from oxidative deterioration.
Ming Xiao - One of the best experts on this subject based on the ideXlab platform.
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on analysis and design of low density generator matrix codes for Continuous Phase modulation
IEEE Transactions on Wireless Communications, 2007Co-Authors: Ming Xiao, T AulinAbstract:We investigate the analysis and design of low density generator matrix (LDGM) codes for Continuous Phase modulation (CPM). The system uses LDGM codes as an outer code for CPM. For additive white Gaussian noise channels, we derive the union bound to analyze the error floor performance. Design principles for lowering error floors are suggested from this analysis. We propose a design approach of jointly considering the LDGM code degree and the CPM modulation index. Then we consider the rate-adaptive system for slowly fading channels. By changing the rate of the LDGM codes, the information rate of the CPM signals is adapted according to channel variations. We use a low-rate LDGM code as the mother code. Higher rates are achieved by puncturing the output of these codes. To exploit the rate-flexible property of punctured LDGM codes, a rate function is proposed to calculate the rate of each transmitted block. Thus, we can have a quasi-Continuous information rate. Numerical results show that this approach can improve the energy efficiency from a discrete-rate adaptation. Using the rate-adaptive approach, up to 11 dB transmitted energy gain can be achieved from the non-adaptive scheme in the low bit-error-rate region (smaller than 10-3) for minimum shift keying (MSK).
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serially concatenated Continuous Phase modulation with symbol interleavers performance properties and design principles
European Transactions on Telecommunications, 2006Co-Authors: Ming Xiao, T AulinAbstract:Serially concatenated Continuous Phase modulation (SCCPM) systems with symbol interleavers are investigated. The transmitted signals are disturbed by additive white Gaussian noise (AWGN). Compared to bit interleaved SCCPM systems, this scheme shows a substantial improvement in the convergence threshold at the price of a higher error floor. In addition to showing this property, we also investigate the underlying reason by error event analysis. In order to estimate bit error rate (BER) performance, we generalise traditional union bounds for a bit interleaver to this non-binary interleaver. For the latter, both the order and the position of permuted non-zero symbols have to be considered. From the analysis, some principal properties are identified. Finally, some design principles are proposed. Our paper concentrates on SCCPM, but the proposed analysis methods and conclusions can be widely used in many other systems such as serially concatenated trellis coded modulation (SCTCM) et cetera. Copyright © 2006 AEIT
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serially concatenated Continuous Phase modulation with low density generator matrix codes property optimization and performance analysis
Information Theory Workshop, 2005Co-Authors: Ming Xiao, T AulinAbstract:We propose a new scheme of serially concatenated Continuous Phase modulation (SCCPM) by using nonsystematic low density generator matrix (LDGM) codes as the outer code. A property of the LDGM code degree is investigated. We use the exit chart/function to optimize the LDGM codes. The exit function of CPM with a fixed SNR (signal-to-noise-ratio) is shown. We derive the union bound to analyze the error floor performance. Design principles are proposed from the analysis process. Numerical results show that this scheme converge earlier (lower SNR) than previous SCCPM for iterative decoding.
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serially concatenated Continuous Phase modulation with symbol interleavers performance properties and design principles
Global Communications Conference, 2004Co-Authors: Ming Xiao, T AulinAbstract:Serially concatenated Continuous Phase modulation (SCCPM) systems with symbol interleavers are investigated. The transmitted signals are disturbed by additive white Gaussian noise (AWGN). Iterative detection with extrinsic information is used at the receiver side. Compared to bit interleaved SCCPM systems, this scheme shows a substantial improvement in convergence threshold at the price of a higher error floor. In addition to showing this property, we also investigate the underlying reason by error event analysis. In order to estimate bit error rate performance, we generalize traditional union bounds for a bit interleaver to the non-binary interleaver. For the latter, both the order and the position of permuted non-zero symbols have to he considered. From the analysis, some principal properties are presented. Finally some design principles are proposed. The paper concentrates on SCCPM, but the proposed analysis methods and conclusions can he widely used in many other systems such as serially concatenated trellis coded modulation, et cetera.
G L Stuber - One of the best experts on this subject based on the ideXlab platform.
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frequency domain equalization for Continuous Phase modulation
IEEE Transactions on Wireless Communications, 2005Co-Authors: Jun Tan, G L StuberAbstract:Single-carrier frequency-domain equalization (SC-FDE) is proposed for Continuous Phase modulation (CPM). Two different discrete representations of the CPM signal are obtained. One is an orthogonal representation obtained from the Gram-Schmidt orthonormalization procedure, and the other is obtained from Laurent's decomposition for binary CPM. The methodology for maintaining Phase continuity with a cyclic guard interval is presented. Various optimal and suboptimal reduced-complexity approaches are suggested for SC-FDE of CPM signals. General full- and partial-response CPM waveforms, and specific examples of minimum-shift keying (MSK) and Gaussian MSK (GMSK) with BT=0.3 are investigated. Simulation results show that SC-FDE for CPM is an effective approach for CPM on channels having long impulse responses.
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frequency domain equalization for Continuous Phase modulation
Personal Indoor and Mobile Radio Communications, 2004Co-Authors: Jun Tan, G L StuberAbstract:Frequency-domain equalization for Continuous Phase modulation (CPM) is investigated. A discrete representation of the CPM signal is obtained by using the Gram-Schmidt orthonormalization procedure. The CPM discrete signal representation admits frequency-domain equalization for the purpose of mitigating intersymbol interference. General full- and partial-response CPM waveforms, and specific examples of MSK and GMSK with BT=0.3 are considered. Frequency-domain equalization is shown to be effective for CPM on severe frequency-selective fading channels.
Don Torrieri - One of the best experts on this subject based on the ideXlab platform.
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Coherent Continuous-Phase frequency-shift keying: Parameter optimization and code design
IEEE Transactions on Wireless Communications, 2009Co-Authors: Shi Cheng, Matthew C Valenti, Don TorrieriAbstract:The symmetric information rate of a modulation-constrained transmission system is the information-theoretic limit on performance under the assumption that the inputs are independent and uniformly distributed. The symmetric information rate for Continuous-Phase frequency-shift keying (CPFSK) over an AWGN channel may be estimated by considering the system to be a finite-state Markov channel and executing a BCJR-like algorithm. In this paper, the estimated symmetric information rate is used along with the exact expression for the 99% power bandwidth to determine the information-theoretic tradeoff between energy and spectral efficiency for CPFSK modulation. Using this tradeoff, the code rate and modulation index are jointly optimized for a particular spectral efficiency and alphabet size. Codes are then designed for the optimized system. The codes are comprised of variable nodes (which represent irregular repetition codes), check nodes (which represent single parity-check codes), and an interleaver connecting the variable and check nodes. The degree distributions of the code are optimized from the system's EXIT chart by using linear programming. Additional details of the code design, including labeling and interleaver design, are also discussed. Simulation results show that the optimized coded systems achieve bit error rates within 0.4 dB of the information-theoretic limits at BER = 10-5.
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the capacity of noncoherent Continuous Phase frequency shift keying
Conference on Information Sciences and Systems, 2007Co-Authors: Shi Cheng, Matthew C Valenti, Rohit Iyer Seshadri, Don TorrieriAbstract:Capacity analysis is used to determine the fundamental tradeoff between power and spectral efficiency for coded Continuous-Phase frequency shift keying (CPFSK). The modulation may use an arbitrary modulation index h and the number of tones M may be any power of two. Detection is noncoherent and the channel is either AWGN or fully-interleaved (ergodic) Reyleigh fading. Numerical results demonstrate the advantage of using nonorthogonal modulation and multiple tones when the bandwidth requirement is tight.
