In the late 1990s, when Wi-Fi-equipped laptops were still a novelty, Narasimha Chari saw the possibility of creating large communications infrastructures using wireless mesh networks -- which at the time were the exclusive province of the military. In 18 months of moonlighting while a physics grad student at Harvard University, he created elegant algorithms that tailored mesh networking for routine civilian communications. Tropos Networks, the company Chari founded in 2000 with coinventor Devabhaktuni Srikrishna, helped launch commercial wireless mesh networking. With their straightforward installation -- routers attach to lampposts -- and attendant low cost, mesh networks have eased into plentiful use both outdoors (on campuses, in public safety networks, and at gatherings such as festivals) and in (in hospitals and factories). But Tropos is focusing on the rapidly growing market for networks that serve entire municipalities. Thats the application of choice for one-third of the companys 200 customers. Troposs services, which are built around Charis routing protocols, dominate the nascent mesh-networking industry. Telecommunications companies fear the proliferation of the technology, seeing it as a threat to their Internet access businesses. In fact, the telecommunications industry is lobbying for legislation granting them -- not local governments -- first dibs on municipal Wi-Fi installations. Meanwhile, Tropos is gaining customers at a rapid clip; 75 signed on in the first half of 2005. Troposs expansion is bringing Chari full circle. In 1992, after receiving the third-highest score out of 80,000 on the Indian Institutes of Technology entrance exam, Chari left India for Caltech. Later, while at Harvard, he had late-night talks with Caltech pal Srikrishna about providing anytime, anywhere communications in developing countries. Now, as Tropos ships its first systems to India, Chari is seeing his innovation connect back to his homeland.