US 6,888,813 B1 · Code division multiple access (CDMA) transmission system

Abstract

A large-capacity CDMA transmission system that can realize communication with a moving unit such as an automobile, transmitting more quantity of information than the conventional system without increasing the occupied band width, using the same or narrower frequency band width. This system assumes the code division multiple access (CDMA) transmission system for simultaneous multiple communication, which performs phase modulation on a carrier signal while maintaining a phase of the carrier signal in a predetermined period at a predetermined value, so as to generate a primary modulated wave, and then, multiplies the obtained primary modulated wave by a spread code sequence. On the transmitting side, a differential coding phase modulation (DPSK) is employed to generate a primary modulated wave. On the other hand, on the receiving side, a quasi-synchronous detection and difference operation are utilized to detect the phase difference between the last symbol interval and the current symbol interval, and the detected phase difference is given as the information of the current symbol interval.

Claims17

Dependent claims

A code division multiple access transmission system, comprising:

on a transmitting side,
a means for obtaining a primary modulated wave by performing differential coding phase modulation on a carrier signal in accordance with information;
and
a means for generating a spread signal including a plurality of basic and virtual segments, by multiplying said primary modulated wave by a spread code repeatedly a plurality of times, changing a time region, via said basic and virtual segments, within a symbol period, and for transmitting said generated spread signal;
and
on a receiving side,
a means for detecting a phase difference between a past symbol and a present symbol, by performing quasi-synchronous detection and despreading, and difference operation;
and
a means for outputting the detected phase difference as information of said symbol.

6 more elements

A code division multiple access transmission system comprising:

on a transmitting side,
a means for obtaining a primary modulated wave by performing differential coding phase modulation on a carrier signal in accordance with information;
a means for excluding rapid fluctuation of a phase value in a symbol end area of said primary modulated wave;
and
a means for generating a spread signal including a plurality of transmission segments, by multiplying said primary modulated wave by a spread code repeatedly a plurality of times, changing a time region within a symbol period, and for transmitting said spread signal;
and
on a receiving side,
a means for detecting a phase difference between a past symbol and a present symbol, by performing quasi-synchronous detection and despreading, and difference operation of a received spread signal;
and
a means for outputting the detected phase difference as information of said symbol.

7 more elements

Dependencies are inferred from the claim text.

Code division multiple access (CDMA) transmission system

Life of this patent

Code division multiple access (CDMA) transmission system

Life of this patent

Abstract

Claims17