  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 paper is to
investigate interference cancellation (IC) techniques capable of resolving such
collisions in a low-complexity modem with single-carrier modulation and single
transducer. More specifically, in this modem, the IC is used at multiple stages
of the receiver. Firstly, the IC is performed for cancelling the multipath
interference to improve the equalization performance in comparison with the
linear equalization and Rake combining. Secondly, 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. The modem performance is
investigated in a lake experiment with intensive multipath channels. The
experimental results demonstrate high detection performance of the proposed
modem design and show that the proposed IC techniques can significantly improve
the throughput of random access UWA networks.
