Abstract
We present a practical solution for dynamic spectrum management
(DSM) in digital subscriber line systems: the normalized-rate
iterative algorithm (NRIA). Supported by a novel optimization
problem formulation, the NRIA is the only DSM algorithm that
jointly addresses spectrum balancing for frequency division
duplexing systems and power allocation for the users sharing a
common cable bundle. With a focus on being implementable rather
than obtaining the highest possible theoretical performance, the
NRIA is designed to efficiently solve the DSM optimization problem
with the operators' business models in mind. This is achieved with
the help of two types of parameters: the desired network asymmetry
and the desired user priorities. The NRIA is a centralized DSM
algorithm based on the iterative water-filling algorithm (IWFA)
for finding efficient power allocations, but extends the IWFA by
finding the achievable bitrates and by optimizing the bandplan.
It is compared with three other DSM proposals: the IWFA, the
optimal spectrum balancing algorithm (OSBA), and the bidirectional
IWFA (bi-IWFA). We show that the NRIA achieves better bitrate
performance than the IWFA and the bi-IWFA. It can even achieve
performance almost as good as the OSBA, but with dramatically
lower requirements on complexity. Additionally, the NRIA can
achieve bitrate combinations that cannot be supported by any other
DSM algorithm.