The Experts below are selected from a list of 1413 Experts worldwide ranked by ideXlab platform
J.m. Cioffi - One of the best experts on this subject based on the ideXlab platform.
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ICC - Margin Optimization in Digital Subscriber Lines Employing Level-2 Dynamic Spectrum Management
2008 IEEE International Conference on Communications, 2008Co-Authors: S Jagannathan, Chan Soo Hwang, J.m. CioffiAbstract:This paper investigates the optimization of margins in Digital Subscriber Lines employing level-2 dynamic spectrum management, where Lines are jointly optimized with an emphasis on their stability, throughput-guarantee, and politeness. A new definition of noise margin and the concept of probability of outage are introduced, which allow for an easier formulation of the problems of joint margin and spectra optimization of the Lines taking into account their stabilities. The solutions to the highly-coupled optimization problems are simplified using noise margins instead of signal-to-interference-and-noise-ratio margins. The presented algorithms provide up to 100% improvements in the data-rates or a reduction in the probability of outage by an order of magnitude, thus improving the stability of the Lines at high data rates.
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ICC - Multiuser Discrete Bit-loading for Digital Subscriber Lines
2007 IEEE International Conference on Communications, 2007Co-Authors: Kibeom Seong, J.m. CioffiAbstract:This paper proposes an efficient algorithm that produces near-optimal discrete bit-loading for a Gaussian interference channel that models a DSL network. It first takes a continuous bit-loading initialization, and then rounds one user's bits in each tone independently, with rounding direction determined by evaluating a weighted sum rate objective function. After adjusting all the tones of a user, that user's power constraint is met by a power tightening procedure; then, the algorithm moves to the next user. Convergence of the proposed algorithm is proved. This algorithm can be made distributed by only allowing rounding DOWN the bits, and it can be also applied to Gaussian Multiple Access Channel (MAC) and Gaussian Broadcast Channel (BC) with slight modifications.
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A multi-user power control algorithm for Digital Subscriber Lines
IEEE Communications Letters, 2005Co-Authors: Jungwon Lee, R.v. Sonalkar, J.m. CioffiAbstract:The paper investigates the power control problem in a frequency-selective interference channel. A centralized power control algorithm is developed with the objective of maximizing the achievable rate region given an average power constraint for each user. The proposed algorithm is based on the multi-user discrete bit-loading algorithm that considers the power allocation over frequency and users simultaneously. Simulation results for very high-speed Digital Subscriber line (VDSL) systems show that the proposed algorithm achieves a larger rate region than that achieved by a power control algorithm based on iterative waterfilling.
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Encyclopedia of Telecommunications - Very high-speed Digital Subscriber Lines (VDSL)
Wiley Encyclopedia of Telecommunications, 2003Co-Authors: J.m. CioffiAbstract:Very high-speed Digital Subscriber Lines (VDSL) is overviewed with an emphasis on the basic architecture, applications, and data rates, as well as the technological challenges of the design. A discussion of the telephone line environment, radio interference implications, impulse noise, symmetric and asymmetric multiplexing, and concentration is also included, with the consequent description of a popular implementation.
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distributed multiuser power control for Digital Subscriber Lines
IEEE Journal on Selected Areas in Communications, 2002Co-Authors: George Ginis, J.m. CioffiAbstract:This paper considers the multiuser power control problem in a frequency-selective interference channel. The interference channel is modeled as a noncooperative game, and the existence and uniqueness of a Nash equilibrium are established for a two-player version of the game. An iterative water-filling algorithm is proposed to efficiently reach the Nash equilibrium. The iterative water-filling algorithm can be implemented distributively without the need for centralized control. It implicitly takes into account the loop transfer functions and cross couplings, and it reaches a competitively optimal power allocation by offering an opportunity for loops to negotiate the best use of power and frequency with each other. When applied to the upstream power backoff problem in very-high bit-rate Digital Subscriber Lines and the downstream spectral compatibility problem in asymmetric Digital Subscriber Lines, the new power control algorithm is found to give a significant performance improvement when compared with existing methods.
M. Moonen - One of the best experts on this subject based on the ideXlab platform.
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low complexity dynamic spectrum management algorithms for Digital Subscriber Lines
International Conference on Acoustics Speech and Signal Processing, 2008Co-Authors: Paschalis Tsiaflakis, M. MoonenAbstract:Modern DSL networks suffer from crosstalk between different Lines in the same cable bundle. By carefully choosing the transmit power spectra, the impact of crosstalk can be minimized leading to spectacular performance gains. This is also referred to as dynamic spectrum management (DSM). This paper presents three novel low-complexity DSM algorithms with a different level of required message-passing. This level ranges from fully autonomous and distributed to semi-centralized execution. Simulations show good performances compared to existing state-of-the-art DSM algorithms.
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Autonomous Spectrum Balancing for Digital Subscriber Lines
IEEE Transactions on Signal Processing, 2007Co-Authors: Raphael Cendrillon, Jianwei Huang, Mung Chiang, M. MoonenAbstract:The main performance bottleneck of modern Digital Subscriber line (DSL) networks is the crosstalk among different Lines (i.e., users). By deploying dynamic spectrum management (DSM) techniques and reducing excess crosstalk among users, a network operator can dramatically increase the data rates and service reach of broadband access. However, current DSM algorithms suffer from either substantial suboptimality in typical deployment scenarios or prohibitively high complexity due to centralized computation. This paper develops, analyzes, and simulates a new suite of DSM algorithms for DSL interference-channel models called autonomous spectrum balancing (ASB). The ASB algorithms utilize the concept of a "reference line," which mimics a typical victim line in the interference channel. In ASB, each modem tries to minimize the harm it causes to the reference line under the constraint of achieving its own target data-rate. Since the reference line is based on the statistics of the entire network, rather than any specific knowledge of the binder a modem operates in, ASB can be implemented autonomously without the need for a centralized spectrum management center. ASB has a low complexity and simulations using a realistic simulator show that it achieves large performance gains over existing autonomous algorithms, coming close to the optimal rate region in some typical scenarios. Sufficient conditions for convergence of ASB are also proved.
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Optimal multiuser spectrum balancing for Digital Subscriber Lines
IEEE Transactions on Communications, 2006Co-Authors: R. Cendrillon, J Verlinden, M. Moonen, T. BostoenAbstract:Crosstalk is a major issue in modern Digital Subscriber line (DSL) systems such as ADSL and VDSL. Static spectrum management, which is the traditional way of ensuring spectral compatibility, employs spectral masks that can be overly conservative and lead to poor performance. This paper presents a centralized algorithm for optimal spectrum balancing in DSL. The algorithm uses the dual decomposition method to optimize spectra in an efficient and computationally tractable way. The algorithm shows significant performance gains over existing dynamics spectrum management (DSM) techniques, e.g., in one of the cases studied, the proposed centralized algorithm leads to a factor-of-four increase in data rate over the distributed DSM algorithm iterative waterfilling.
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iterative spectrum balancing for Digital Subscriber Lines
International Conference on Communications, 2005Co-Authors: Raphael Cendrillon, M. MoonenAbstract:Dynamic spectrum management (DSM) is an important technique for mitigating crosstalk in DSL. One of the first DSM algorithms proposed, iterative waterfilling (IW), has a low complexity and demonstrates the spectacular performance gains that are possible. Unfortunately IW tends to be highly sub-optimal in mixed CO/RT deployments and upstream VDSL. Another DSM algorithm, optimal spectrum balancing (OSB), uses a weighted rate-sum to find the theoretically optimal transmit spectra. Unfortunately its complexity scales exponentially with the number of Lines in the binder N. Typical binders contain 25-100 Lines, for which OSB is intractable. This paper presents a new iterative algorithm for spectrum management in DSL. The algorithm optimizes the weighted rate-sum in an iterative fashion, which leads to a quadratic, rather than exponential, complexity in N. The algorithm is tractable for large N and can be used to optimize entire binders. Simulations show that the algorithm performs very close to the theoretical optimum achieved by OSB.
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optimal multiuser spectrum management for Digital Subscriber Lines
International Conference on Communications, 2004Co-Authors: M. Moonen, T. Bostoen, Jan Sylvia Verlinden, Wei YuAbstract:Crosstalk is a major issue in modern DSL systems such as ADSL and VDSL. Static spectrum management, the traditional way of ensuring spectral compatibility, employs spectral masks which can be overly conservative and lead to poor performance. In this paper we present a centralized algorithm for optimal spectrum management (OSM) in DSL. The algorithm uses a dual decomposition to solve the spectrum management problem in an efficient and computationally tractable way. The algorithm shows significant performance gains over existing DSM techniques, e.g. in a downstream ADSL scenario the centralized OSM algorithm can outperform a distributed DSM algorithm such as iterative waterfilling by up to 135%.
J M Cioffi - One of the best experts on this subject based on the ideXlab platform.
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margin optimization in Digital Subscriber Lines employing level 2 dynamic spectrum management
International Conference on Communications, 2008Co-Authors: S Jagannathan, Chan Soo Hwang, J M CioffiAbstract:This paper investigates the optimization of margins in Digital Subscriber Lines employing level-2 dynamic spectrum management, where Lines are jointly optimized with an emphasis on their stability, throughput-guarantee, and politeness. A new definition of noise margin and the concept of probability of outage are introduced, which allow for an easier formulation of the problems of joint margin and spectra optimization of the Lines taking into account their stabilities. The solutions to the highly-coupled optimization problems are simplified using noise margins instead of signal-to-interference-and-noise-ratio margins. The presented algorithms provide up to 100% improvements in the data-rates or a reduction in the probability of outage by an order of magnitude, thus improving the stability of the Lines at high data rates.
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multiuser discrete bit loading for Digital Subscriber Lines
International Conference on Communications, 2007Co-Authors: Kibeom Seong, J M CioffiAbstract:This paper proposes an efficient algorithm that produces near-optimal discrete bit-loading for a Gaussian interference channel that models a DSL network. It first takes a continuous bit-loading initialization, and then rounds one user's bits in each tone independently, with rounding direction determined by evaluating a weighted sum rate objective function. After adjusting all the tones of a user, that user's power constraint is met by a power tightening procedure; then, the algorithm moves to the next user. Convergence of the proposed algorithm is proved. This algorithm can be made distributed by only allowing rounding DOWN the bits, and it can be also applied to Gaussian Multiple Access Channel (MAC) and Gaussian Broadcast Channel (BC) with slight modifications.
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very high speed Digital Subscriber Lines
IEEE Communications Magazine, 1999Co-Authors: J M Cioffi, Vladimir Oksman, J J Werner, Thierry Pollet, Paul Marie Pierre Spruyt, J S Chow, Krista S JacobsenAbstract:VDSL services are overviewed with an emphasis on the basic architecture, applications, and data rates, as well as the technological challenges of design. Discussions of the telephone line environment, radio-band interference ingress and egress, impulse noise, and symmetric and asymmetric multiplexing are included, along with brief descriptions of two popular implementations.
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very high speed Digital Subscriber Lines vdsl
International Symposium on Circuits and Systems, 1998Co-Authors: J M CioffiAbstract:Very high-speed Digital Subscriber Lines (VDSL) are overviewed with an emphasis on the basic architecture, applications, and data rates, as well as the technological challenges of the design. Discussions of the telephone line environment, radio-band interference ingress and egress, impulse noise, and symmetric and asymmetric multiplexing are included along with the consequent description of a popular implementation.
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performance evaluation of a multichannel transceiver system for adsl and vhdsl services
IEEE Journal on Selected Areas in Communications, 1991Co-Authors: Peter Chow, J M CioffiAbstract:The authors study the performance of a multichannel modulation method for asymmetric Digital Subscriber Lines (ADSLs) and very high-speed Digital Subscriber Lines (VHDSLs). In the ADSL case, over all unloaded North American Subscriber Lines in the test set, a unidirectional 1.536 Mb/s data rate service from the end office to the customer premises is possible on a single twisted pair at an error rate of 10/sup -7/ with at least a 6 dB margin used coded multichannel modulation with sufficient transmit power. In the VHDSL case, data rates in excess of 100 Mb/s can be transmitted reliably, at an error rate of 10/sup -7/, using uncoded multichannel modulation on a single twisted pair over a distance >
M. Barton - One of the best experts on this subject based on the ideXlab platform.
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Performance study of high-speed asymmetric Digital Subscriber Lines technology
IEEE Transactions on Communications, 1996Co-Authors: M. Barton, L. Chang, T.r. HsingAbstract:Computer simulation results are presented for the loop range coverage of an asymmetric Digital Subscriber Lines (ADSL) system that uses the quadrature amplitude modulation (QAM) signaling scheme, ADSL performance is evaluated in the presence of background additive white Gaussian noise (AWGN), and crosstalk noise from existing services in the local telephone loop plant. It is shown that coverage of the extreme carrier serving area (CSA) is possible at transmission rates that are well above the existing T1 rate.
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Impulse noise performance of an asymmetric Digital Subscriber Lines passband transmission system
IEEE Transactions on Communications, 1995Co-Authors: M. BartonAbstract:This letter presents an analytical method to numerically evaluate the bit error Probability (BEP) performance of a quadrature amplitude modulation (QAM) transmission system in the presence of impulse noise. This work facilitates characterization of the two-wire twisted-pair loop plant for high-speed Digital communications. Simulation results are presented to demonstrate the effectiveness of this approach using parameters that are typical of the recently proposed Asymmetric Digital Subscriber Lines (ADSL) for high-speed Digital transmission over local copper telephone loops. >
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Impulse noise performance of an asymmetrical Digital Subscriber Lines passband transmission system
[Conference Record] GLOBECOM '92 - Communications for Global Users: IEEE, 1Co-Authors: M. BartonAbstract:An analytical method for estimating the bit error probability performance of a quadrature amplitude modulation (QAM) transmission system in the presence of impulse noise is presented. Numerical results are demonstrated, using parameters that are typical of the recently proposed asymmetrical Digital Subscriber Lines (ADSLs) for Digital transmission over the local copper telephone loop plant. It is shown that impulse noise can significantly affect the performance of QAM systems, such as the QAM-based ADSL, when they operate on local telephone loops. >
S Olcer - One of the best experts on this subject based on the ideXlab platform.
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Application of capacity approaching coding techniques to Digital Subscriber Lines
IEEE Communications Magazine, 2004Co-Authors: Evangelos Eleftheriou, S Olcer, Hamid R. SadjadpourAbstract:The use of coding error control is an integral part of the design of modern communication systems. Capacity-approaching codes such as turbo and LDPC codes, discovered or rediscovered in the past decade, offset near-Shannon-limit performance on the AWGN channel with rather low implementation complexity and are therefore increasingly being applied for error control in various fields of data communications. This article describes a generic multilevel modulation and coding scheme based on the use of turbo-like, or LDPC codes for DSL system. It is shown that such codes provide significant gains in performance and allow an increase in data rate and/or loop reach that can be instrumental to the widespread deployment of future DSL services. Such techniques are also suitable for general multilevel modulation system in other application areas.
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filtered multitone modulation for very high speed Digital Subscriber Lines
IEEE Journal on Selected Areas in Communications, 2002Co-Authors: Giovanni Cherubini, Evangelos S Eleftheriou, S OlcerAbstract:A filter-bank modulation technique called filtered multitone (FMT) and its application to data transmission for very high-speed Digital Subscriber line technology are described. The proposed scheme leads to significantly lower spectral overlapping between adjacent subchannels than for known multicarrier techniques such as discrete multitone (DMT) or discrete wavelet multitone. FMT modulation mitigates interference due to echo and near-end crosstalk signals, and increases the system throughput and reach. Signal equalization in an FMT receiver is accomplished in the form of per-subchannel symbol-spaced or fractionally spaced linear or decision-feedback equalization. The problem of channel coding for this type of modulation is also addressed, and an approach that allows combined removal of intersymbol-interference via precoding and trellis coding is described. Furthermore, practical design aspects regarding filter-bank realization, initial transceiver training, adaptive equalization, and timing recovery are discussed. Finally, simulation results of the performance achieved by FMT modulation for very high-speed Digital Subscriber line systems, where upstream and downstream signals are separated by frequency-division duplexing, are presented and compared with DMT modulation.
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low density parity check codes for Digital Subscriber Lines
International Conference on Communications, 2002Co-Authors: Evangelos Eleftheriou, S OlcerAbstract:The paper investigates the application of low-density parity-check (LDPC) codes to Digital Subscriber-line (DSL) transmission systems that employ discrete multitone modulation. A family of linear-time encodable binary LDPC codes that are well-suited for DSL transmission is introduced. Encoding and symbol mapping for multilevel modulation are described. Simulation results show that even under tight latency constraints good net coding gains can be achieved. Implementation complexity is analyzed and compared with that of trellis-coded modulation as employed in current asymmetric DSL transceivers. The incorporation of powerful LDPC coding techniques into next-generation DSL modems appears to be possible with reasonable increase in transceiver complexity.
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ICC - Low-density parity-check codes for Digital Subscriber Lines
2002 IEEE International Conference on Communications. Conference Proceedings. ICC 2002 (Cat. No.02CH37333), 1Co-Authors: Evangelos Eleftheriou, S OlcerAbstract:The paper investigates the application of low-density parity-check (LDPC) codes to Digital Subscriber-line (DSL) transmission systems that employ discrete multitone modulation. A family of linear-time encodable binary LDPC codes that are well-suited for DSL transmission is introduced. Encoding and symbol mapping for multilevel modulation are described. Simulation results show that even under tight latency constraints good net coding gains can be achieved. Implementation complexity is analyzed and compared with that of trellis-coded modulation as employed in current asymmetric DSL transceivers. The incorporation of powerful LDPC coding techniques into next-generation DSL modems appears to be possible with reasonable increase in transceiver complexity.
