Interference Cancellation for UWA Random Access Data Packet Transmission

In underwater acoustic (UWA) random access communication networks with multiple users and data packet transmissions, the packet collisions are the main cause of the network performance degradation. The aim of this article is to investigate interference cancellation (IC) techniques capable of resolving such collisions in a low-complexity modem with single-carrier modulation and a single transducer. More specifically, in this modem, the IC is used at multiple stages of the receiver. First, the IC is performed for canceling the multipath interference to improve the equalization performance in comparison with the linear equalization and Rake combining. Second, the IC removes the interference from collided data packets within extracted signal segments after identifying the collisions. Finally, the IC is applied to the received baseband signal to improve the data packet detection. Numerical experiments are conducted to investigate the packet detection and decoding performance of the receiver with different channel equalizers. Numerical results indicate that the proposed Rake-IC equalizer provides the best performance among the equalizers considered. The receiver performance is further investigated in a lake experiment with intensive multipath interference. In the experiment, with a channel utilization of 23%, the receiver with the proposed IC techniques reduces the number of lost packets from 33% to 0.26%.