Date Added: Nov 2012
The performance of multi-hop underwater acoustic network is known to be limited by the long propagation delays and by the limited bandwidth of the Under-Water Acoustic (UW-A) channel. Recent work on Analog Network Coding (ANC) has shown that significant throughput gains can be achieved in multi-hop wireless networks. However, implementing ANC for UW-A communications is very challenging as the UW-A channel is severely affected by multipath. In this paper, the authors propose CE-CDMA, a collision-enabling direct-sequence code-division multiple-access scheme for multi-hop Under-Water Acoustic Sensor Networks (UW-ASNs). In CE-CDMA two nodes, separated by two hops, are assigned the same code-division channel (i.e., spreading code) to communicate concurrently. The transmission of packets by the two nodes will therefore collide at the intermediate (relay) node.