Multiple-access noise rejection filter for a DS-CDMA system
US5377225A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 19, 1993 |
| Grant date | Dec 27, 1994 |
| Priority date | — |
| Expiry date | Oct 19, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B2201/709709
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A direct-sequence multiple-access code division (DS-CDMA) communication system accommodates a multiplicity of separate transmitters (12) and at least one base-station receiver (14). Each transmitter generates a transmitted signal (16) at a common carrier frequency. Each transmitter has an assigned spreading code. Each bit time within the transmitted signal includes a unique signature waveform (21) generated from the spreading code that identifies the source of the transmitted signal. For a given transmitter, the transmitted signals from the other transmitters represent "multi-access noise" that may adversely degrade the signal-to-noise ratio (SNR) of that transmitter's signal at the receiver. Each transmitter operates using a spectrally inefficient power spectrum, i.e., a non-flat power spectrum, that simplifies the transmitter circuits. Each transmitter includes a clock source (26), a signature waveform generator (28), a data generator (30, 32), a first multiplier (42), a low pass filter (44), and RF generator (46), a second multiplier (48), a bandpass filter (50), a power amplifier (52) and a broadcast antenna (54). The receiver processes the received waveform signal on a bit-by-…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.