Abstract
How can different organizations in the same building each maintain security of their internal wifi communications? Part of the answer to this is for organizations on opposite sides of a single wall or floor to use distinct radio channels. How many channels may be needed to meet this requirement in a typical modern office building? Mathematically this channel assignment problem is a vertex colouring problem with the organizations as the vertices, joined if somewhere they are adjacent either wall-to-wall or floor-to-ceiling. The study group showed that there is no easy answer to this question, but that bounds can be obtained in particular cases. For instance if each company only occupies one floor of the building, 8 channels suffice. Public graph-colouring algorithms are quick and successful in finding minimal colourings for reasonably complex building layouts.