A multi-lag/multi-scale receiver for underwater acoustic communications

Wireless communications have numerous applications in terrestrial and space environments, but for one environment the number of civil wireless applications is small. This is the underwater environment where for wireless communications acoustic waves are used instead of electromagnetic waves. The underwater acoustic channel is a very difficult medium for wireless communications and is subject to severe multipath and Doppler effects. It is possible that each multipath component may have a unique delay and Doppler shift, so called multi-scale/multi-lag channels. This is at present a limiting factor for wireless communications underwater. At the moment always a single Doppler rate is assumed which converts to a narrowband system when re-sampled. In this report a receiver is introduced which can remove the effects of multipath and Doppler where the novelty lies in the fact that it is especially designed for a multi-scale/multi-lag channel. This is done by introducing equalizers followed by channel estimation which are both designed for a multi-scale/multi-lag channel. The designed receiver shows promising results and is able to recover the original transmitted symbols according to the simulations. A multi-lag/multi-scale receiver for underwater acoustic communications