Wireless Pers Commun DOI 10.1007/s11277-015-2278-5 A Modified Low Complexity Based Distributed Iterative Water-Filling (IWF) Spectrum Management Algorithm Sunil Sharma · O. P. Sahu © Springer Science+Business Media New York 2015 Abstract In digital subscriber line (DSL) system, crosstalk created by electromagnetic interference among twisted pairs degrades the system performance. Very high bit rate DSL (VDSL), utilizes higher bandwidth of copper cable for data transmission. In upstream data transmission, a ‘Near–Far’ problem occurs in VDSL system. In this problem the far end crosstalk is produced from near end user degrades the data rate achieved at the far end user. Several dynamic spectrum management (DSM) algorithms were proposed in literature to remove this problem. In this paper, a new distributed DSM algorithm is proposed in which power from only those subcarriers of near end user are reduced which create interference to far end user. This power back off strategy takes place with the help of power spectral density masks at those interference creating subcarriers of near end user. The results after simulating the low complex proposed algorithm show an improvement in terms of data rate and approaches near the rate of highly complex optimal spectrum balancing algorithm. Keywords Digital subscriber line · Discrete multi-tone · Iterative water-filling · Optimal spectrum balancing · Dynamic spectrum management 1 Introduction DSL, a high speed broadband access technology uses copper twisted pairs of existing tele- phone lines. DSLs are of many types, referred as xDSL, which include basic rate DSL (ISDN), high-bit rate DSL (HDSL), single pair symmetric DSL (SDSL), asymmetric DSL (ADSL), and VDSL [1]. The highest performance VDSL based on discrete multi-tone (DMT) modulation can utilize frequencies up to 30 MHz [2]. DSL using DMT modulation can be considered multiuser DMT system [3]. At higher frequencies crosstalk becomes the major obstruction to achieve higher data rates [4, 5]. The high data rate demand over the past few S. Sharma (B ) · O. P. Sahu ECE Department, NIT, Kurukshetra, Haryana, India e-mail: ersunil0@gmail.com O. P. Sahu e-mail: OPS_nitk@yahoo.co.in 123