Abstract
In this chapter, we focus on a novel network architecture, UASN-MG, which has multiple surface gateways for underwater acoustic sensor networks. The surface gateways communicate with each other using surface radio and form a radio network on the water surface. Thus, two networks, an underwater acoustic network formed by underwater sensor nodes and a surface radio network formed by the surface gateways, are involved. Such a network architecture can bring about many benefits such as high throughput and energy efficiency. However, integrating multiple surface gateways into underwater acoustic sensor networks also incurs many new design challenges. In this chapter, we describe this new network architecture and its benefits in detail. Then we discuss the design challenges in this new architecture. Afterwards, three design examples are given, from different perspectives, to illustrate the techniques that cope with these challenges and optimize the network's performance. Finally, we conclude the chapter with discussions on possible future research directions.