A. Parameters

Fundamental parameters
$\rho_0$	$\triangleq {(m_1-m_0)^2\over\sigma_0^2+\sigma'^2}$	Slot SNR
$\rho_+$	$\triangleq {(m_1-m_0)^2\over\sigma_1^2-\sigma_0^2}$	Excess slot SNR
$\Delta$	$\triangleq \delta_1^2-\delta_0^2$	Difference of Webb skewness in signaling and nonsignaling slots
$\beta_0$	$\triangleq {\sigma_0^2\over\sigma_0^2+\sigma'^2}$	Fraction of APD output having Webb distribution
Channel desciption parameters
$m_0, m_1$		Mean of Webb component of nonsignaling, signaling slot statistic
$\sigma_0^2, \sigma_1^2$		Variance of Webb component of nonsignaling, signaling slot statistic
$m'$		Mean of AWGN component of slot statistic
$\sigma'^2$		Variance of AWGN component of slot statistic
$\delta_0^2, \delta_1^2$		Skewness of Webb component of nonsignaling, signaling slot statistic
Laser and Modulator parameters
$M$	2-256	PPM order
$T_s$	$3.125 \times 10^{-8}$	Width of the PPM slot required by laser, in seconds
APD detector parameters
$\eta$	38%	Quantum efficiency
$F$	2.2-3.4	Excess noise factor. $F=k_{eff} G+(2-1/G)(1-k_{eff})$
$I_b$	$4\times 10^{-14}$	Bulk leakage current, in Amperes
$I_s$	$2\times 10^{-9}$	Surface leakage current, in Amperes
$T$	300	Noise temperature, in Kelvin
$R_L$	179700	Load resistance (transimpedance model), $5.75\times 10^{12} \times T_s$, in Ohms
$B$	$1\over 2T_s$	Noise equivalent one-sided bandwidth, in Hz.
$G$	30-200	Gain
Other parameters
$\bar n_b$	0.001 - 10,000	Mean background photons incident on the photodetector, per slot
$\bar n_s$	100	Mean signal photons incident on the photodetector, per pulse
Physical Constants
$\kappa$	$1.38\times 10^{-23}$	Boltzmann's constant, in Joules/Kelvin
$e_-$	$1.6\times 10^{-19}$	Electron charge, in Coulombs