The capacity of additive Gaussian noise (AGN) channels, $Y_t=X_t+V_t, t=1, \ldots, n$, $\frac{1}{n} {\bf E}\big\{\sum_{t=1}^n |X_t|^2 \big\}\leq \kappa, \kappa \in [0,\infty)$, with time-invariant channel input feedback strategies, is characterized and conditions are identified for entropy rates, and limit of average power to exist, when the noise is described by {\it stable and unstable} autoregressive models, AR$(c)$, $V_t=cV_{t-1}+ W_t, V_0=v_0, t=1, \ldots, n$, where $c\in (-\infty,\infty)$, $W_t, t=1,\ldots, n$, is a zero mean, variance $K_W$, independent Gaussian sequence, independent of $V_0$. For stable AR$(c), c\in (-1,1)$ the conditions are necessary and sufficient for asymptotic stationarity of the processes $(X_t, Y_t), t=1, 2, \ldots$. New closed form capacity formulas and lower bounds are derived, for the AR$(c), c\in (-\infty,\infty)$ noise, which are fundamentally different from existing formulas in the literature, and illustrate multiple regimes of capacity, as a function of the parameters $(c,K_W,\kappa)$, as follows.\\ 1) feedback increases capacity for the regime, $c^2 \in (1, \infty),$ for $\kappa > \frac{K_W\big(1+\sqrt{4c^2-3}\big)}{2\big(c^2-1\big)^2}$, \\ 2) feedback does not increase capacity for the regime $c^2 \in (1, \infty)$, for $\kappa \leq \frac{K_W\big(1+\sqrt{4c^2-3}\big)}{2\big(c^2-1\big)^2}$, and \\ 3) feedback does not increase capacity for the regime $c \in [-1,1]$, for $ \kappa \in [0,\infty)$.
翻译:添加高尔氏噪声( AGN) 频道的容量, $_ t=X_ t+Vt, t=1, rdots, n$, $\fc{c{sum_ 1\\n} {X_t ⁇ 2\2\\kapa\\ big ⁇ qleq\ kappa,\ kappa\ in [0,\infty], 具有时间变化频道输入反馈策略的特性, 确定通缩率和平均功率的限度, 当噪音由 rt稳定和不稳定的 自动递增模式描述, AR$(c) $, $t=v_ 0, t=1, \ kapots, n, 其中, yct\ft=ft 美元, ystations a.