TY - GEN
T1 - Structured spectrum balancing in DSL multiuser communications
AU - Huang, Yao
AU - Gohary, Ramy H.
AU - Luo, Zhi Quan
PY - 2009
Y1 - 2009
N2 - Finding the power allocations that maximize the sum-rate of a Kuser N-tone Digital Subscriber Line (DSL) system is known to be NP-hard. In this paper we devise a polynomial-time algorithm to approximate the maximum sum rate of the system. The development of this algorithm is guided by the fact that, to approach the sumrate maximum, the users should operate in an FDMA-mode over frequency tones where the crosstalk coefficients exceed a certain threshold, and should share the tones for which the crosstalk coeffi-cients are sufficiently small. Drawing on this insight, the algorithm partitions the N tones into three sections and imposes an appropriate signalling structure on each section. The first section contains those tones for which the crosstalk coefficients are small and uses an iterative water-filling technique to determine the power allocations. The second section contains the tones with intermediate crosstalk coefficients and uses a primal-dual algorithm, and the third section contains the tones with large crosstalk coefficients and uses a dual FDMA algorithm. To decouple the overall optimization of power allocation across the three sections, we use tools from Lagrangian duality and sensitivity analysis to devise an iterative scheme that can optimally allocate each user's power budget to the three sections. Our numerical simulations, show that the sum-rate of the proposed algorithm is very close to that of the 'optimal' spectrum balancing algorithm, but requires considerably less computational effort.
AB - Finding the power allocations that maximize the sum-rate of a Kuser N-tone Digital Subscriber Line (DSL) system is known to be NP-hard. In this paper we devise a polynomial-time algorithm to approximate the maximum sum rate of the system. The development of this algorithm is guided by the fact that, to approach the sumrate maximum, the users should operate in an FDMA-mode over frequency tones where the crosstalk coefficients exceed a certain threshold, and should share the tones for which the crosstalk coeffi-cients are sufficiently small. Drawing on this insight, the algorithm partitions the N tones into three sections and imposes an appropriate signalling structure on each section. The first section contains those tones for which the crosstalk coefficients are small and uses an iterative water-filling technique to determine the power allocations. The second section contains the tones with intermediate crosstalk coefficients and uses a primal-dual algorithm, and the third section contains the tones with large crosstalk coefficients and uses a dual FDMA algorithm. To decouple the overall optimization of power allocation across the three sections, we use tools from Lagrangian duality and sensitivity analysis to devise an iterative scheme that can optimally allocate each user's power budget to the three sections. Our numerical simulations, show that the sum-rate of the proposed algorithm is very close to that of the 'optimal' spectrum balancing algorithm, but requires considerably less computational effort.
KW - DSL systems
KW - Dual algorithms
KW - Multi-tone communications
KW - Spectrum balancing
KW - Water-filling
UR - http://www.scopus.com/inward/record.url?scp=70349208570&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=70349208570&partnerID=8YFLogxK
U2 - 10.1109/ICASSP.2009.4960097
DO - 10.1109/ICASSP.2009.4960097
M3 - Conference contribution
AN - SCOPUS:70349208570
SN - 9781424423545
T3 - ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings
SP - 2369
EP - 2372
BT - 2009 IEEE International Conference on Acoustics, Speech, and Signal Processing - Proceedings, ICASSP 2009
T2 - 2009 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2009
Y2 - 19 April 2009 through 24 April 2009
ER -