Pulse or digital communications – Repeaters – Testing
Patent
1993-10-19
1994-12-27
Cangialosi, Salvatore
Pulse or digital communications
Repeaters
Testing
H04L 2730
Patent
active
053772253
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-bit basis in the absence of knowledge of the other transmitters' spreading codes. An adaptive linear filter (66) included within the receiver (14) operates to make the SNR for the spectrally-inefficient transmitted signals approach asymptotically the SNR that would be received from a spectrally-efficient transmitted signal. Additionally, the receiver rejects narrowband interference, thereby providing superior performance over a spectrally-efficient system with no narrowband noise rejection.
REFERENCES:
patent: 5103459 (1992-04-01), Gilhousen et al.
patent: 5185762 (1993-02-01), Schilling
patent: 5208829 (1993-05-01), Soleimani et al.
patent: 5276705 (1994-01-01), Higgins
Cangialosi Salvatore
Denson-Low Wanda K.
Hughes Aircraft Company
Lindeen III Gordon R.
Streeter William J.
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