  In this paper we use game theoretic techniques to study the value of
cooperation in distributed spectrum management problems. We show that the
celebrated iterative water-filling algorithm is subject to the prisoner's
dilemma and therefore can lead to severe degradation of the achievable rate
region in an interference channel environment. We also provide thorough
analysis of a simple two bands near-far situation where we are able to provide
closed form tight bounds on the rate region of both fixed margin iterative
water filling (FM-IWF) and dynamic frequency division multiplexing (DFDM)
methods. This is the only case where such analytic expressions are known and
all previous studies included only simulated results of the rate region. We
then propose an alternative algorithm that alleviates some of the drawbacks of
the IWF algorithm in near-far scenarios relevant to DSL access networks. We
also provide experimental analysis based on measured DSL channels of both
algorithms as well as the centralized optimum spectrum management.
