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 P̅^γ, γ >; 0 and a forward data transmission power of P̅, our proposed scheme achieves an infinite diversity order for 0 ≤ gm <; L_c - L_B,τ/L_c min(γ,1) and r >; 2, where g_m is the multiplexing gain, L_c is the channel coherence time, L_B,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 (-P̅^E), where E =^Δ (γ-g_mL_c/L_c -L_B,τ), at high P̅. Thus, the proposed scheme achieves a significantly better DMT performance compared to the finite diversity order achieved by channel-agnostic, fixed-power RCT schemes.