Call for Papers - Special Issue on Advanced Signal Processing Techniques for Digital Subscriber Lines

The recent deployment of digital subscriber line (DSL) technology around the world is rapidly making broadband access for the mass consumer market a reality. DSL allows telephone operators to get maximum leverage out of their existing infrastructure by delivering broadband access over existing twisted-pair telephone lines. At the heart of DSL lies a plethora of advanced signal processing techniques which enable such high-speed transmission to be achieved over a medium originally designed with only voice-band transmission in mind. As DSL networks are deployed, customer demand for ever higher data rates is growing. This has been fueled by the increasing popularity of applications like peer-to-peer (P2P) file-sharing networks, video streaming, and HDTV. Achieving such high data rates will require the development of new, advanced signal processing techniques to address many issues that still exist in DSL networks such as crosstalk, impulse noise, high peak-to-average power ratios (PAPR), intersymbol / intercarrier interference (ISI/ICI), and radio frequency interference (RFI). The goal of this special issue is to discuss the state of the art in signal processing techniques for DSL. Topics of interest include (but are not limited to): - Dynamic spectrum management - Vectoring, bonding, and phantom-mode transmission - Alien crosstalk cancelation - Other multiuser techniques - Turbo/LDPC codes for DSL - Ethernet in the first mile (EFM) - Advanced modulation techniques for DSL - PAPR reduction - Windowing and RFI cancelation - Equalization and echo cancelation - Impulse noise mitigation - Synchronization - Wavelets and filterbank

Investigation of Accurate Far-End Crosstalk Modeling in Metallic Cables

Crosstalk and especially far-end crosstalk (FEXT) represents the most serious source of disturbance in today’s digital transmission systems. It mostly limits the information capacity of current xDSL digital subscriber lines and also of local data networks with unshielded and or shielded twisted pairs (UTP/STP). The elimination of FEXT will require the implementation of advanced methods for its modeling to obtain required predictions of crosstalk behavior in a cable. The standard simple FEXT model and ITU-T FEXT model are not very accurate and do not provide realistic results. That is why a new method for modeling of FEXT was developed and is presented in this paper. The results of the model are also compared with measured characteristics for a typical UTP cable and several other cables. The proposed advanced FEXT model with minor modifications is applicable for any metallic cable to provide accurate and realistic FEXT characteristics

Real-time dynamic spectrum management for multi-user multi-carrier communication systems

Dynamic spectrum management is recognized as a key technique to tackle interference in multi-user multi-carrier communication systems and networks. However existing dynamic spectrum management algorithms may not be suitable when the available computation time and compute power are limited, i.e., when a very fast responsiveness is required. In this paper, we present a new paradigm, theory and algorithm for real-time dynamic spectrum management (RT-DSM) under tight real-time constraints. Specifically, a RT-DSM algorithm can be stopped at any point in time while guaranteeing a feasible and improved solution. This is enabled by the introduction of a novel difference-of-variables (DoV) transformation and problem reformulation, for which a primal coordinate ascent approach is proposed with exact line search via a logarithmicly scaled grid search. The concrete proposed algorithm is referred to as iterative power difference balancing (IPDB). Simulations for different realistic wireline and wireless interference limited systems demonstrate its good performance, low complexity and wide applicability under different configurations.Comment: 14 pages, 9 figures. This work has been submitted to the IEEE for possible publicatio

Guest Editorial: Nonlinear Optimization of Communication Systems

Linear programming and other classical optimization techniques have found important applications in communication systems for many decades. Recently, there has been a surge in research activities that utilize the latest developments in nonlinear optimization to tackle a much wider scope of work in the analysis and design of communication systems. These activities involve every “layer” of the protocol stack and the principles of layered network architecture itself, and have made intellectual and practical impacts significantly beyond the established frameworks of optimization of communication systems in the early 1990s. These recent results are driven by new demands in the areas of communications and networking, as well as new tools emerging from optimization theory. Such tools include the powerful theories and highly efficient computational algorithms for nonlinear convex optimization, together with global solution methods and relaxation techniques for nonconvex optimization