tailieunhanh - Báo cáo hóa học: " The Worst-Case Interference in DSL Systems Employing Dynamic Spectrum Management"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: The Worst-Case Interference in DSL Systems Employing Dynamic Spectrum Management | Hindawi Publishing Corporation EURASIP Journal on Applied Signal Processing Volume 2006 Article ID 78524 Pages 1-11 DOI ASP 2006 78524 The Worst-Case Interference in DSL Systems Employing Dynamic Spectrum Management Mark H. Brady and John M. Cioffi Department of Electrical Engineering Stanford University Stanford CA 94305-9515 USA Received 1 December 2004 Revised 28 July 2005 Accepted 31 July 2005 Dynamic spectrum management DSM has been proposed to achieve next-generation rates on digital subscriber lines DSL . Because the copper twisted-pair plant is an interference-constrained environment the multiuser performance and spectral compatibility of DSM schemes are of primary concern in such systems. While the analysis of multiuser interference has been standardized for current static spectrum-management SSM techniques at present no corresponding standard DSM analysis has been established. This paper examines a multiuser spectrum-allocation problem and formulates a lower bound to the achievable rate of a DSL modem that is tight in the presence of the worst-case interference. A game-theoretic analysis shows that the rate-maximizing strategy under the worst-case interference WCI in the DSM setting corresponds to a Nash equilibrium in pure strategies of a certain strictly competitive game. A Nash equilibrium is shown to exist under very mild conditions and the rate-adaptive waterfilling algorithm is demonstrated to give the optimal strategy in response to the WCI under a frequency-division FDM condition. Numerical results are presented for two important scenarios an upstream VDSL deployment exhibiting the near-far effect and an ADSL RT deployment with long CO lines. The results show that the performance improvement of DSM over SSM techniques in these channels can be preserved by appropriate distributed power control even in worst-case interference environments. Copyright 2006 M. H. Brady and J. M. Cioffi. This is an open access article distributed under the .