Optimal pilot spacing and power in rate-adaptive MIMO diversity systems with imperfect transmitter CSI

We analyze and optimize the performance of an adaptive coded modulation system with imperfect channel state information, operating on a multiple-input multiple-output channel where space-time block coding is utilized to exploit spatial diversity and, thereby combat fading in wireless channel communications. The pilot symbol period and the power allocated to pilot and data symbols are optimized in such a way that the average spectral efficiency is maximized. At the same time, the bit error rate is maintained below a desired level. A numerical example is given for independent flat Rayleigh fading subchannels with Jakes spectrum.