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
_m
L
_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.