Tomoaki Ohtsuki

Performance of optical asynchronous code-division multiple-access (CDMA) systems with double optical hard-limiters is analyzed under the assumption of Poisson shot noise model for the receiver photodetector where the noise due to the detector dark currents exists. Optical orthogonal codes (OOC's) are employed as signature sequence codes. In the analysis, chips are assumed to be synchronous among users, that is, the chip synchronous case, because the effect of the interference is largest in the c

This paper deals with nonlinear networks which can be characterized by the equation ${\bf f}({\bf x}) = {\bf y}$, where ${\bf f}$ is a continuous piecewise-linear mapping from $R^n $ into itself. The main theorem asserts that the existence of solutions ${\bf x} \in R^n $ of ${\bf f}({\bf x}) = {\bf y}$ for an arbitrary given ${\bf y} \in R^n $ is guaranteed by fairly general conditions based on the theory of the degree of mapping. Then it is shown that an iterative algorithm (generalized Katzene

We propose atmospheric optical code-division multiple-access (CDMA) systems. We analyze the bit-error rate of the proposed system using pulse-position modulation (PPM) with considering the effects of the scintillation, avalanche photodiode noise, thermal noise, and multi-user interference. We show that the atmospheric optical CDMA systems can realize high-speed communications when the logarithm variance of the scintillation is small. When Σ/sub s/ <sup xmlns:mml="http://www.w3.org/1998/Math/Math

An optical code-division multiple-access (CDMA) system with double optical hard-limiters is proposed where the optical hard-limiters are placed before and after an optical correlator. Moreover, the-effect of the optical hard-limiter on the performance of the optical synchronous CDMA systems using modified prime sequence codes as signature codes is analyzed under the assumption of a Poisson shot noise model for the receiver photodetector where the noise due to the detector dark currents exists. W