Optimal Dynamic Spectrum Management Algorithms for Multi-User Full-Duplex DSL

Driven by the exceedingly high data rates achieved in single-user implementations, interest in a multi-user (MU) full-duplex (FDX) transmission for digital subscriber line (DSL) networks is surging. However, near-end crosstalk (NEXT) is no longer avoided in such networks, and hence, appropriate dynamic spectrum management (DSM) techniques are needed. Therefore, this paper proposes three novel DSM algorithms for the MU FDX DSL network. First, an optimal spectrum balancing (OSB) algorithm is derived that calculates the globally optimal resource allocation but does so at an exceedingly high computational cost. The key to this algorithm is a novel multiple access channel broadcast channel (MAC-BC) duality for the specific case of perfect NEXT cancellation at the distribution point unit. The two low-complexity distributed spectrum balancing (DSB) algorithms are then proposed, for which simulations show that their performance is very close to what is achieved by the OSB algorithm. Therefore, these DSB algorithms can be used to estimate the achievable performance of an MU FDX DSL network. Such performance estimations show that the FDX transmission can indeed lead to significant gains in MU DSL networks as well.