 |
|
|
|
|
|
 Title: |
US6075808:
Spread spectrum time diversity communications system
[ Derwent Title ]
|
| Country: |
US United States of America
|
| |
| Inventor: |
Tsujimoto, Ichiro; Tokyo, Japan
|
| Assignee: |
NEC Corporation, Tokyo, Japan
other patents from NEC CORPORATION (395735) (approx. 22,197)
News, Profiles, Stocks and More about this company
|
| Published / Filed: |
2000-06-13
/ 1998-02-05
|
| Application Number: |
US1998000018893
|
| IPC Code: |
Advanced:
H04B 1/707;
H04J 13/00;
Core:
more...
IPC-7:
H04B 1/707;
|
| ECLA Code: |
H04B1/707F3;
|
| U.S. Class: |
Current:
375/143;
375/152;
375/E01.032;
Original:
375/143;
375/152;
|
| Field of Search: |
375/140,141,142,143,147,150,152
370/320,335,342,441
|
| Priority Number: |
|
| Abstract: |
In a time diversity radio communications system, quadrature-modulated spread spectrum signals of different mutual time delay are combined into a code division multiplex signal and up-converted to a radio-frequency signal and transmitted. At a receive site, the signal is received by an antenna and down-converted to recover the code division multiplex signal. Quadrature-modulated component signals contained in the recovered code division multiplex signal are converted to baseband signals which are then time-aligned with each other. The time-aligned baseband signals are multiplied respectively by complex weighting factors and are combined together to produce an input signal for an adaptive equalizer. This input signal is also applied to an AGC amplifier where it is amplified and applied to correlation detectors where correlations between the amplified signal and the baseband signals are detected and the complex weighting factors are derived respectively from the correlations. In a modified embodiment, the quadrature-modulated component signals are fed into an adaptive RAKE matched filter where the output of the AGC amplifier is used for detecting the correlations.
|
| Attorney, Agent or Firm: |
Sughrue, Mion, Zinn, Macpeak & Seas, PLLC ;
|
| Primary / Asst. Examiners: |
Vo, Don N.;
|
| INPADOC Legal Status: |
None
Family Legal Status Report
|
|
|
|
|
|
|
| Parent Case: |
This is a divisional of application Ser. No. 08/620,246 filed Mar. 22, 1996 which is now U.S. Pat. No. 5,757,853.
|
| Family: |
Show 6 known family members
|
First Claim:
Show all 7 claims |
What is claimed is:
1. A radio communications system comprising:
- a multiplexer circuit for producing a plurality of quadrature-modulated spread spectrum information-bearing signals using quadrature carriers of single frequency and a plurality of spreading codes, and combining the quadrature-modulated spread spectrum information-bearing signals to produce a code division multiplex signal, there being a predetermined inter-signal time delay between said quadrature-modulated spread spectrum information-bearing signals;
- a transmitter for up-converting the code division multiplex signal to a radio-frequency signal;
- a transmit antenna for transmitting the radio-frequency signal;
- a receive antenna for receiving the transmitted signal;
- a receiver for down-converting the received signal to recover said code division multiplex signal;
- a demultiplexer circuit for converting a plurality of quadrature-modulated component signals contained in the recovered multiplex signal to a plurality of information-bearing signals using quadrature carriers of said single frequency and a plurality of despreading codes respectively identical to the spreading codes;
- a first combiner for combining said plurality of information-bearing signals into a combined information-bearing signal;
- a delay line having a plurality of successive taps for receiving the combined information-bearing signal, the delay time between the successive taps corresponding to said predetermined inter-signal time delay;
- a plurality of complex multipliers for respectively weighting tap signals from the taps of the delay line by complex weighting factors;
- a second combiner for combining the weighted tap signals to produce a combined weighted signal;
- an adaptive equalizer for producing a decision output from the combined weighted signal; and
- a plurality of correlation detectors for respectively deriving said plurality of complex weighting factors from correlations between the decision output of the adaptive equalizer and a plurality of delayed versions of tap signals at the taps of the delay line, one of the delayed versions being time coincident with said decision output.
|
| Background / Summary: |
Show background / summary
|
| Drawing Descriptions: |
Show drawing descriptions
|
| Description: |
Show description
|
| Forward References: |
Show 21 U.S. patent(s) that reference this one
|
|
