BWA must make sound business sense to be a successful 'last-mile' solution technology, for it faces stiff cost competition from phone-line and cable broadband-access alternatives. The challenge to modem designers is to develop technology which improves the BWA return-on-investment @OX), to wit minimize the installed equipment (total system, not just modem) cost while maximizing the data-bearing capacity of millimeter-wave links. Broadband wireless access (BWA) links exhibit pathologies and cost models distinct from those of wired links, and these distinctions should be reflected in a well-designed BWA modem. This tutorial paper discusses BWA ROI within the context of a system-level cost concept, relates this model to primary LMDS link pathologies, and suggests several modem-level features which will be required to address BWA ROI challenges. A few specific modem design approaches will be noted to demonstrate that these BWA design challenges are readily addressable.