The architecture of Metricom's MicroCellular Data Network/sup TM/ (MCDN) and details of its implementation as the second and third generation Ricochet/sup TM/ wide-area mobile data service

We describe the architecture of the MicroCellular Data Network/sup TM/ (MCDN) - a wide-area, wireless, data network. This network is designed to provide its users with fast, mobile, data access to any of the available wired data networks, typically the Internet or a corporate LAN, solving the first-mile problem. Metricom sold the first generation implementation of this architecture as the Utilinet line of private networks. We do not describe it here. We describe the second-generation implementation of this architecture, currently deployed in Washington DC, Seattle, and the San Francisco Bay Area and sold as a service under the brand name Ricochet. We also describe the third-generation implementation, based on the MCDN(3G) architecture, which provides 10x improvements in performance and is currently deployed nationwide in 14 metropolitan areas covering over 35 million people [1]. We show some laboratory measurements of the throughput and fairness of the system. Finally, we address the possibilities of extending the architecture to a fourth generation with another factor of 10x improvement.