An analysis of the home PNA collision resolution mechanism

In this paper, we present an analysis of the collision resolution mechanism in the Home Phone-line Networking Alliance (Home PNA) 2.0 MAC protocol. We begin with a brief description of the collision resolution (CR) mechanism, bringing out the differences with respect to other CR mechanisms. We show that the mechanism can be modeled as a recursive one, with each CR cycle consisting of smaller CR cycles. This recursive model is then used to relate CR cycle periods with different variables in collision resolution. These relations form the basis of a numerical method to find the mean of CR cycle periods, as functions of initial collision multiplicity, the number of CR slots, and the priority class of traffic. Thus, having characterized the CR mechanism, we discuss how to operate it optimally, given the network conditions. We show that the choice of three slots for CR, as in the standard, is sub-optimal in many cases. We conclude with a proposal for a dynamic CR mechanism, in which the number of CR slots can be varied dynamically. Without going into the implementation details, we discuss how the analysis results can be used in this new mechanism.