Distributed Spatial Diversity Enabled Receiver System For An Underwater Acoustic Link

The prime functionality of underwater acoustic modems is communication. It is known that spatial diversity can provide improved communication performance, in the form of increased data rate or extended range. While spatial diversity is traditionally harnessed by having multiple antennas connected to a single modem, we show that multiple receiver modems can also be used cooperatively to leverage spatial diversity. One can also get much larger separation between modems than possible with multi-antenna systems. We present the design framework, protocol implementation and the performance results of a distributed spatial diversity receiver system. The system comprises of spatially separated receivers exchanging the information received over the long-range underwater acoustic link to cooperatively decode the received information. We demonstrated this technique in Singapore marina with one modem as a transmitter and two modems as receivers. The receivers cooperate over a short-range wired/wireless network to share the received copy of signals and decode the information transmitted. The advantages of such a system are observed in the performance analysis presented.