Designing wireless metropolitan-area networks using mathematical optimization

Wireless metropolitan area networks usually rely on a network of microwave links created by mounting communication equipment on masts located at the sites to which they provide connectivity. Today microwave link design tools design only a single link pair at a time or, at most, a network of direct links between communicating sites. In many cases one can realize substantial savings in mast and equipment costs by routing the flows between communicating sites via third sites rather than via direct links. Furthermore, in some cases direct links may be infeasible due to technical or regulatory reasons, and rerouting flows via other sites may be necessary. To do this with today's tools, a wireless network design engineer is forced to manually try various combinations of direct links. This work describes a prototype system that automates this process by modeling it as a combinatorial optimization problem. (The underlying optimization problem is NP-Complete and in approximable.) We tested our system by using it to find high-quality solutions to several realistic problem instances.