Experimental Verification of a Multiuser Detection Technique for Asynchronous UOWC Systems

In this paper, a multiuser detection technique is proposed and experimentally verified in underwater optical wireless communication (UOWC) under dynamic channel conditions, which incorporates subspace-based delay estimation and decorrelating multiuser detection methods for an asynchronous access system. The subspace-based delay estimation method necessitates only prior knowledge of user spreading codes. The decorrelating multiuser detector can suppress multiple access interference (MAI) and demonstrates superior detection performance in a dynamic channel. An underwater testbench that supports three-user asynchronous access is established to further validate the multiuser detection technique. Experimental results demonstrate the effectiveness of alleviating the negative effects of user asynchrony, MAI, and intensity fluctuation.