초록 ▼

An optical fiber communications system using spread spectrum code division multiple access techniques to achieve better bandwidth utilization. A transmitting user in the system encodes the optical signal using a first coding mask, and a receiving user decodes the received signal using two decoding m

An optical fiber communications system using spread spectrum code division multiple access techniques to achieve better bandwidth utilization. A transmitting user in the system encodes the optical signal using a first coding mask, and a receiving user decodes the received signal using two decoding masks, all of the masks having lengths N. The first mask is divided into two sections of lengths N/2 each, one of the sections defining a first sub-code of length N/2, while the other section blocks light. Each of the second and third masks is also divided into two sections, which correspond to the two sections of the first mask. The section of the second mask corresponding to the coded section of the first mask has a second code that is identical to the first code, and the section of the second mask corresponding to the blocked section of the first mask is also blocked. The section of the third mask corresponding to coded section of the first mask has a third code that is complementary to the first code, and the section of the third mask corresponding to the blocked section of the first mask is also blocked. Some users on the system have masks in which the first of the two sections are blocked and the second of the two sections are coded, while other users have masks in which the second of the two sections are blocked and the first of the two sections are coded. The first codes used to code the encoding masks are selected from a set of unipolar codes that are derived from a set of balanced bipolar orthogonal codes.

대표청구항 ▼

[ What is claimed is:] [1.]1. In an optical code-division multiple access communication system in which a plurality of users are connected to an optical fiber, at least one user transmitting optical signals over the fiber and at least one user receiving optical signals from the fiber, an encoding ap

[ What is claimed is:] [1.]1. In an optical code-division multiple access communication system in which a plurality of users are connected to an optical fiber, at least one user transmitting optical signals over the fiber and at least one user receiving optical signals from the fiber, an encoding apparatus at the transmitting user for generating a modulated and encoded beam of light carrying a data signal, the encoding apparatus comprising:a broad band light source for providing a beam of light;an optical modulator for modulating the intensity of the beam of light according to the data signal;a first optical chamber having a first code, the first code having a sequence of digits each having one of at least two values, the first optical chamber defining a plurality of spectral components in the beam of light each corresponding to a digit of the first code, the first optical chamber attenuating the intensity of each spectral component of the beam of light according to the value of the corresponding digit of the first code to generate an encoded beam of light, wherein a spectral component is substantially completely removed when the corresponding code digit has a first value;wherein the first code comprises a first and a second section of identical lengths, wherein the first section defines a first sub-code and wherein each digit in the second section has the first value; andwherein the first sub-code is selected from a set of unipolar codes in which each code in the set is orthogonal to the difference between any other code in the set and the complement of the other code; andan optical coupler for injecting the modulated and encoded beam of light into the optical fiber.