Asymptotic Behavior of Error Exponents in the Wideband Regime
<|reference_start|>Asymptotic Behavior of Error Exponents in the Wideband Regime: In this paper, we complement Verd\'{u}'s work on spectral efficiency in the wideband regime by investigating the fundamental tradeoff between rate and bandwidth when a constraint is imposed on the error exponent. Specifically, we consider both AWGN and Rayleigh-fading channels. For the AWGN channel model, the optimal values of $R_z(0)$ and $\dot{R_z}(0)$ are calculated, where $R_z(1/B)$ is the maximum rate at which information can be transmitted over a channel with bandwidth $B/2$ when the error-exponent is constrained to be greater than or equal to $z.$ Based on this calculation, we say that a sequence of input distributions is near optimal if both $R_z(0)$ and $\dot{R_z}(0)$ are achieved. We show that QPSK, a widely-used signaling scheme, is near-optimal within a large class of input distributions for the AWGN channel. Similar results are also established for a fading channel where full CSI is available at the receiver.<|reference_end|>
@article{wu2005asymptotic,
    title={Asymptotic Behavior of Error Exponents in the Wideband Regime},
    author={X. Wu and R. Srikant},
    journal={arXiv preprint arXiv:cs/0509001},
    year={2005},
    archivePrefix={arXiv},
    eprint={cs/0509001},
    primaryClass={cs.IT math.IT}
}