Power Controlled Reverse Channel Training Achieves an Infinite Diversity Order in a TDD-SIMO System with Perfect CSIR.

In this letter, we analyze the Diversity Multiplexing-gain Tradeoff (DMT) performance of a training-based reciprocal Single Input Multiple Output (SIMO) system. Assuming Channel State Information (CSI) is available at the Receiver (CSIR), we propose a channel-dependent power-controlled Reverse Channel Training (RCT) scheme that enables the transmitter to directly estimate the power control parameter to be used for the forward-link data transmission. We show that, with an RCT power of \bar P^γ, γ>0 and a forward data transmission power of \bar P, our proposed scheme achieves an infinite diversity order for 0 ≤ g_m < \fracL_c - LB,τ{L_c}\min(γ,1) and r > 2, where g_m is the multiplexing gain, L_c is the channel coherence time, LB,τ is the RCT duration and r is the number of receive antennas. We also derive an upper bound on the outage probability and show that it goes to zero asymptotically as \exp\lb -\bar P^{E}\rb, where E \triangleq (γ-\frac{g_m L_c}{L_c -LB,τ}), at high \bar P. Thus, the proposed scheme achieves a significantly better DMT performance compared to the finite diversity order achieved by channel-agnostic, fixed-power RCT schemes. [ABSTRACT FROM PUBLISHER]