Capacity analysis of underwater acoustic MIMO communications

Abstract

Multi-Input Multi-Output (MIMO) principle is based on transmitting digital data from Nt transmitters to Nr receivers within a frequency band. In the last decade, theoretical works and practical experiments in wireless and cellular networks have convincingly proved that MIMO
has been a real find in digital communications.
Nowadays, MIMO principle is being applied to underwater acoustic communications (UAC) and it is showing encouraging results. But very few research has been done on the relation
between different parameters of MIMO and its gain. Our primary purpose in this project is to analyse the MIMO gain theoretically using Shannon capacity analysis and suggest ways to maximize capacity with limited bandwidth by varying other parameters . As we will show in the later pages of this project that underwater acoustic channel (UAC) is
highly selective in frequency, data transmission cannot be increased by simply increasing the transmission bandwidth. This difficult situation can be found in wireless communication where there is an increasingly large requirement in high speed data transfer but available bandwidth is constrained by the frequency allocation law. In those communication fields where radio frequency is used , this bandwidth limitation problem has been overcome by introducing MIMO techniques, which provide significant gain in data transmission rate while keeping the transmission Bandwidth constant.In the previous years, the contribution of MIMO to UAC systems has mostly been
thoroughly analyzed via spatial modulation or multi-carrier modulation. Initial simulation and experimental results have showcased a larger gain over conventional single input single output (SISO) but the results strongly vary depending on the modulation scheme chosen by us and the
receiver algorithm as well as the underwater channel environment.