Achieving near-exponential diversity on uncoded low-dimensional MIMO, multi-user and multi-carrier systems without transmitter CSI

It is well-known that for single-input and single-output (SISO) narrow-band transmission on frequency-flat fading channels, uncoded communication with only receiver channel state information (Rx-CSI) leads to extremely poor reliability performance whereas transmitter CSI (Tx-CSI) allows us approach the reliability of an additive white Gaussian noise (AWGN) channel via power control. In this paper, we propose a novel approach to achieve reliability close to the AWGN channel for uncoded transmissions on SISO frequency-flat Rayleigh fading channels without Tx-CSI. Our approach employs pseudo-random phase precoding (PRPP) of modulation symbols prior to temporal multiplexing, and joint-detection at the receiver that has polynomial complexity in the precoder size. With a precoder size of 400 binary symbols, we demonstrate that the proposed system achieves performance within 0.1 dB of the AWGN channel at a bit error rate of 10^-5, and is also robust to fading correlation and channel estimation errors. Furthermore, we present extensions to multiple-user multiple-input and multiple-output (MU-MIMO) systems and wideband transmission schemes such as orthogonal frequency-division multiplexing (OFDM) and single-carrier frequency-domain multiple access (SC-FDMA) systems. We show, through extensive simulations, that i) with an 8-by-8 MIMO system per-stream AWGN channel reliability is achieved with 8 spatial streams and 50 channel uses, ii) for a 5 user multiple-access channel with one antenna per user and 5 antennas at the receiver, 80 channel uses eliminates fading and interference completely while simultaneously providing a power gain of approximately 6.9 dB, and iii) for OFDM and SC-FDMA systems with single antenna at the transmitter and two antennas at the receiver, within 0.1 and 0.3 dB of the matched-filter bound performance is achieved with a precoder size of 96 and 400 symbols, respectively.