A Generalized Time-Reversed Space-Time Block Code for Helicopter-to-Ground Communications

This paper introduces a generalized version of time-reversed, space-time block codes (TR-STBCs), called GTRSTBCs that operates with non-equal power allocation between two inter-symbol interference (ISI) channels in a 2 transmit, 1 receive antenna helicopter-to-ground radio link. The power allocation is parameterized by, the portion of the total available power allocated to channel 1. The criteria for selecting the optimum is minimizing the residual mean-squared error at the MMSE equalizer output. GTR-STBC is applied to measured channel impulse responses and a simple statistical channel model. The results show that 1) the optimum value of gives the best trade off between signal-to-noise ratio and ISI, 2) equal power allocation may not be the optimum power allocation when channel side information is available, and 3) the optimum profile of over measured channels channels is significantly different than from that in statistical channel models.