On the capacity and energy efficiency of training-based transmissions over fading channels
IEEE Transactions on Information Theory
Optimal constellations for the low-SNR noncoherent MIMO block Rayleigh-fading channel
IEEE Transactions on Information Theory
The impact of hard-decision detection on the energy efficiency of phase and frequency modulation
IEEE Transactions on Wireless Communications
Bursty relay networks in low-SNR regimes
IEEE Transactions on Communications
High-order analysis of outage probability in OFDMA wireless networks
GLOBECOM'09 Proceedings of the 28th IEEE conference on Global telecommunications
Wideband fading channel capacity with training and partial feedback
IEEE Transactions on Information Theory
A unified treatment of optimum pilot overhead in multipath fading channels
IEEE Transactions on Communications
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Channel capacity in the limit of vanishing signal-to-noise ratio (SNR) per degree of freedom is known to be linear in SNR for fading and nonfading channels, regardless of channel state information at the receiver (CSIR). It has recently been shown that the significant engineering difference between the coherent and the noncoherent fading channels, including the requirement of peaky signaling and the resulting spectral efficiency, is determined by how the capacity limit is approached as SNR tends to zero, or in other words, the sublinear term in the capacity expression. In this paper, we show that this sublinear term is determined by the channel coherence level, which we define to quantify the relation between the SNR and the channel coherence time. This allows us to trace a continuum between the case with perfect CSIR and the case with no CSIR at all. Using this approach, we also evaluate the performance of suboptimal training schemes