Smart green ocean underwater IoT network by ICA-based acoustic blind MIMO OFDM transceiver

Abstract

Multi-Input Multi-Output (MIMO) telecommunication systems with Orthogonal Frequency Division Modulation (OFDM) scheme support high rate data exchange which can be efficiently applied to the fast-growing networks of Internet of Things (IoT). In the case of Underwater IoT (UIoT) where the strength of electromagnetic waves rapidly falls off, the MIMO network can be effectively implemented by substitute of acoustic OFDM instead of the normal one. Due to these advantages, this research work suggests ICA based acoustic MIMO OFDM for UIoT wherein the data rate is further improved as the MIMO OFDM is implemented based on blind channel estimation and multi-user identification without the need for using any pilot and preamble data. Also, theoretical analysis shows the data rate increases and energy consumption decreases due to ICA-based MIMO acoustic channel estimation. In the case of the under-work UIoT network, it achieves 52.38% higher data rate, and 41.67% less energy consumption. As another specific result, the proposed method shows high efficiency on sparse underwater channels and as the channel sparseness gets lower, the efficiency decreases.

Appendix

Energy Consumption Decrease Percentage (ECD%)

At each SISO channel of underwater acoustic OFDM, the energy consumption is decreased by using the blind channel estimation with the percentage given in Eq. 12 as it is obtained in the sequence. As in the proposed technique, all the K sub-carriers are used for data and there is not any need for pilot and null sub-carriers. Thus, if for each data sub-carrier one energy unit is consumed in a transmission over a link, then in average for each data symbol, $\frac {K}{K}=1$ energy unit is consumed. In the case of dedicating K_pilot and K_null number of sub-carriers to pilot and null ones out of each K total ones, the data transfered by each K sub-carriers is K − K_pilot − K_null symbols and since the each pilot sub-carrier requires 1.5 times more energy, the consumed corresponding energy is K + 0.5K_pilot. In average, for each data symbol, $\frac {K+ 0.5 K_{\text {pilot}}}{K-K_{\text {pilot}}-K_{\text {null}}}$ energy unit is consumed. Therefore the decrease percentage in consumption of energy for data transmission over each SISO underwater acoustic OFDM channel is:

$$ \begin{array}{@{}rcl@{}} ECD<percent>&=&\left( 1- \frac{1}{\frac{K+0.5 K_{\text{pilot}}}{K-K_{\text{pilot}}-K_{\text{null}}}}\right)\times 100<percent> \end{array} $$

(13)

$$ \begin{array}{@{}rcl@{}} &=& \frac{1.5 K_{\text{pilot}}+K_{\text{null}}}{K+0.5 K_{\text{pilot}}} \times 100<percent> \end{array} $$

(14)

That is indicated in Eq. 12.