I. Introduction
Problems that can be posed as that of finding fixed points of standard interference mappings are ubiquitous in communication systems [1]–[9], and, in particular, in planning and optimization of networks based on the orthogonal frequency division multiple access (OFDMA) technology [4]–[10]. In many of these applications, the mappings are positive concave mappings, which are a strict subclass of standard interference mappings [7].