Smart Roaming: How Operator Cooperation Can Increase Spectrum Usage Efficiency at Practically No Cost

We propose smart roaming (SR), a cooperation technique between cellular telcos operating in the same region, that enables users to roam for performance reasons (even if they are covered by their operator). Within a region, base stations of different operators are sometimes co-located but, in that case, the sectors are rarely aligned. SR leverages spatial diversity to enhance spectrum usage efficiency. Simply put, an edge user of an operator might be a “good user” for another one. This paper answers the following research questions: 1) Can significant gain be obtained with SR? 2) What are the factors that affect the gain? 3) How to manage operator heterogeneity to avoid that a large operator cross subsidizes a smaller one? and 4) How to implement and manage SR in an online fashion while keeping the signaling information manageable? We answer the first three questions by proposing a snapshot model for the downlink that shows that SR can indeed provide significant gain without yielding cross-subsidies if done properly. We then propose two schemes to implement and manage SR online and evaluate them via extensive simulations.