PROJECT TITLE :

CDMA-Based Analog Network Coding for Underwater Acoustic Sensor Networks

ABSTRACT:

We have a tendency to propose ANC-CDMA, a CDMA-primarily based analog network coding scheme for underwater acoustic sensor networks (UW-ASNs) that may considerably improve the underwater acoustic channel utilization. First, we tend to analyze a unidirectional multihop network, in that 2 acoustic nodes separated by 2 hops are assigned the identical code-division channel (i.e., spreading code) to transmit concurrently. The packets transmitted by the 2 nodes can collide at the intermediate (relay) node. But, we tend to show that, by exploiting a priori data, i.e., the interfered packet previously received from one among the nodes, and applying joint channel estimation through pilot supervision together with a newly designed adaptive RAKE receiver, the relay node will cancel the interference before decoding the packet of interest. We then extend our analysis to a bidirectional network, in which 2 nodes initial concurrently transmit their packets to the relay using the same spreading code. The relay amplifies and forwards the received interfered packet to the two nodes. We have a tendency to show that either node will still decode the packet of interest once equalizing the channel effects introduced during the propagation from the relay to itself and jointly estimating multipath affected channels and suppressing the self-interference signal before applying the adaptive RAKE receiver. The proposed ANC-CDMA scheme is implemented in a very testbed primarily based on Teledyne Benthos Telesonar SM-975 underwater modems and tested extensively in Lake LaSalle. Experiments and simulations demonstrate that for a 1–a pair of dB tradeoff in signal-to-noise ratio (SNR), the proposed scheme can significantly improve the channel utilization of a unidirectional and bidirectional networks by up to 50% and a hundred%, respectively, compared with conventional multiuser DS-CDMA scheme.