Robust, reliable and high data rate transmission systems are key components of underground information systems particularly in the case of driverless ones. In this context, wireless systems must be able to maximize data rate and/or robustness while avoiding increases in transmitting power and/or in transmission bandwidth. MIMO techniques are today well known in the scientific community for indoor applications where the propagation channel experiences multipath effects. The work presented in this paper concerns the evaluation of conventional MIMO techniques such as the Alamouti code, spatial multiplexing, and linear precoding in tunnels environments usually considered as correlated channels. After the choice of the best suited channel model and antenna configuration, the simulation of the physical layer based on Wi-Fi IEEE802.11a/g standards gives rise to the comparison of the MIMO algorithms.