References of "Sorger, Ulrich 50003123"
     in
Bookmark and Share    
Peer Reviewed
See detailComputation of distributions and their moments in the trellis
Heim, Axel; Sidorenko, Vladimir; Sorger, Ulrich UL

in Advances in Mathematics of Communications (2008), 2(4), 373391

Consider a function whose set of vector arguments with known distribution is described by a trellis. For a certain class of functions, the distribution of the function values can be calculated in the ... [more ▼]

Consider a function whose set of vector arguments with known distribution is described by a trellis. For a certain class of functions, the distribution of the function values can be calculated in the trellis. The forward/backward recursion known from the BCJR algorithm [2] is generalized to compute the moments of these distributions. In analogy to the symbol probabilities, by introducing a constraint at a certain depth in the trellis we obtain symbol distributions and symbol moments, respectively. These moments are required for an efficient implementation of the discriminated belief propagation algorithm in [8], and can furthermore be utilized to compute conditional entropies in the trellis. The moment computation algorithm has the same asymptotic complexity as the BCJR algorithm. It is applicable to any commutative semi-ring, thus actually providing a generalization of the Viterbi algorithm [10]. [less ▲]

Detailed reference viewed: 75 (2 UL)
Peer Reviewed
See detailDoppler-Variant Modeling of the Vocal Tract
Heim, Axel; Sorger, Ulrich UL; Hug, Florian

in Proc. IEEE International Conference on Acoustics, Speech, and Signal Processing (2008)

A common technique to deploy linear prediction to non-stationary signals is time segmentation and local analysis. Variations of a process within such a segment cause inaccuracies. In this paper, we model ... [more ▼]

A common technique to deploy linear prediction to non-stationary signals is time segmentation and local analysis. Variations of a process within such a segment cause inaccuracies. In this paper, we model the temporal changes of linear prediction coef?cients (LPCs) as a Fourier series. We obtain a compact description of the vocal tract model limited by the predictor order and the maximum Doppler frequency. Filter stability is guaranteed by all-pass ?ltering, deploying the human ear?s insensitivity to absolute phase. The periodicity constraint induced by the Fourier series is counteracted by oversampling in the Doppler domain. With this approach, the number of coef?cients required for the vocal tract modeling is signi?cantly reduced compared to a LPC system with block-wise adaptation while exceeding its prediction gain. As a by-product it is found that the Doppler frequency of the vocal tract is in the order of 10 Hz. A generalization of the algorithm to an auto-regressive moving average model with time-correlated ?lter coef?cients is straight forward. [less ▲]

Detailed reference viewed: 62 (0 UL)
Peer Reviewed
See detailUnlinkable Communication
Fusenig, Volker UL; Staab, Eugen UL; Sorger, Ulrich UL et al

in Privacy, Security and Trust, 2008. PST '08. Sixth Annual Conference on (2008)

In this paper we present a protocol for unlinkable communication, i.e. where an attacker cannot map the sender and receiver node of a communication. Existing anonymity protocols either do not guarantee ... [more ▼]

In this paper we present a protocol for unlinkable communication, i.e. where an attacker cannot map the sender and receiver node of a communication. Existing anonymity protocols either do not guarantee unlinkability (e.g. Tor and Mix networks), or produce huge overhead -- the dining cryptographers network causes quadratic number of messages. Our protocol needs only a linear number of messages while it still guarantees unlinkability. We introduce a measure of unlinkability and show that our protocol offers the highest possible degree of unlinkability. We show how to use the protocol in practice by adapting it to internet and ad hoc communication. [less ▲]

Detailed reference viewed: 76 (1 UL)
Peer Reviewed
See detailTurbo Decoding: Why Stopping Criteria do Work
Heim, Axel; Sorger, Ulrich UL

in Proc. 5th International Symposium on Turbo Codes & Related Topics (2008)

The convergence of iterative decoding schemes is considered. The class of dually coupled codes is recalled, being a super class to both Turbo and LDPC codes. It is proven that the output L-values of a ... [more ▼]

The convergence of iterative decoding schemes is considered. The class of dually coupled codes is recalled, being a super class to both Turbo and LDPC codes. It is proven that the output L-values of a Turbo decoder cannot grow to in?nity, while those of an LDPC decoder can. Finally, a new decoder parameter is introduced by which the convergence behavior can be controlled. [less ▲]

Detailed reference viewed: 72 (0 UL)
Peer Reviewed
See detailHow Can Path Diversity Help Transmission Protocols in the Achievement of a Better Connection Qos?
Melakessou, Foued UL; Sorger, Ulrich UL; Suchanecki, Zdzislaw UL

in Proceedings of the 6th ACS/IEEE International Conference on Computer Systems and Applications AICCSA'08 (2008)

Detailed reference viewed: 57 (0 UL)
Peer Reviewed
See detailTime Operators and Approximation of Continuous Functions
Sorger, Ulrich UL; Suchanecki, Zdzislaw UL

in Int. J. Theor. Phys. (2008), 47

Detailed reference viewed: 62 (3 UL)
Peer Reviewed
See detailDoppler-variant Modeling of the Vocal Tract: Stability Considerations
Heim, Axel; Sorger, Ulrich UL

in Proc. 8th ITG Conference on Speech Communication (2008)

A common technique to deploy linear prediction to non-stationary signals is time segmentation and local analy-sis. In [1], the temporal changes of linear prediction coef?cients (LPCs) are modeled as a ... [more ▼]

A common technique to deploy linear prediction to non-stationary signals is time segmentation and local analy-sis. In [1], the temporal changes of linear prediction coef?cients (LPCs) are modeled as a Fourier series. This allows analysis and optimization of larger speech segments, i.e., virtually global analysis. Possibly resulting non-minimum-phase prediction error polynomials are subject to all-pass ?ltering. We show that introducing the stabilizing ?lter does not deteriorate the overall predictor performance. [less ▲]

Detailed reference viewed: 43 (1 UL)
Full Text
Peer Reviewed
See detailComputation of Moments in the Trellis
Heim, Axel; Sidorenko, Vladimir; Sorger, Ulrich UL

in Proc. IEEE International Symposium on Information Theory (2008)

Decisions on sources with memory transmitted over independent channels can be taken by employing trellis calculations. In this paper, it is shown that for a certain class of functions their moments can be ... [more ▼]

Decisions on sources with memory transmitted over independent channels can be taken by employing trellis calculations. In this paper, it is shown that for a certain class of functions their moments can be computed in the trellis, too. This is done by generalizing the forward/backward recursion known from the BCJR algorithm [1]. In analogy to the symbol probabilities, by introducing a constraint at a certain depth in the trellis we obtain symbol moments. These moments are required for an ef?cient implementation of the discriminated belief propagation algorithm in [2], and can furthermore be utilized to compute conditional entropies in the trellis. The moment computation algorithm has the same asymptotic complexity as the BCJR algorithm. It is applicable to any commutative semi-ring, thus also providing a generalization of the Viterbi algorithm [3]. [less ▲]

Detailed reference viewed: 64 (2 UL)
Full Text
Peer Reviewed
See detailRoute Diversity: A Future For Transmission Protocols
Sorger, Ulrich UL; Melakessou, Foued UL; Suchanecki, Zdzislaw UL et al

in Proceedings of the 2007 Fourth International Conference on Broadband Communications, Networks and Systems BROADNETS 2007 (2007)

Detailed reference viewed: 67 (0 UL)
Full Text
Peer Reviewed
See detailOn The Road Towards The Comprehension Of The Internet Traffic Behavior: Simulation And Analysis Of An End-To-End Connection With NS-2
Sorger, Ulrich UL; Melakessou, Foued UL; Suchanecki, Zdzislaw UL

in Abstract book of 10th Communications and Networking Simulation Symposium CNS'07 (2007), (Proceedings of the 10th Communications and Networking Simulation Symposium CNS'07 Norfolk Marriott Waterside, Norfolk, VA, USA, March 25 - 29, 2007),

Detailed reference viewed: 63 (1 UL)
Full Text
Peer Reviewed
See detailMPTCP: Concept of a Flow Control Protocol Based on Multiple Paths for the Next Generation Internet 2007
Sorger, Ulrich UL; Melakessou, Foued UL; Suchanecki, Zdzislaw UL

in Proceedings of the 7th International Symposium on Communications and Information Technologies ISCIT'07 (2007)

Detailed reference viewed: 60 (2 UL)