Spread spectrum communication method and system using diversity correlation and multi-user detection
View Patent ↗A communication system transmits and receives a plurality of spread-spectrum signals having differences in at least one diversity parameter. The signals are highly correlated when their diversity parameters are similar, and the signals are uncorrelated when at least one diversity parameter is different. Any combination of a transmitter, a receiver, and a communication channel may diversity-encode the signals to effect differences in their diversity parameters. A receiver diversity-decoder compensates for differences in a diversity-parameter of at least one received signal to make the signal highly correlated with at least one other received signal. A correlator combines at least two of the received signals to recover an embedded information signal. The communication system enables the use of true-noise signals for spreading information signals, provides simplified receiver designs, and enables antenna arrays to spatially process spread-spectrum signals.
1. A method comprising:
generating a spread information signal,
generating a despreading signal,
diversity-encoding at least one of the spread information signal and the despreading signal, and
transmitting diversity-encoded spread-spectrum signals by coupling the spread information signal and the despreading signal into a wireless communication channel, wherein the despreading signal is transmitted distinctly from the spread information signal.
2. The method of claim 1 wherein the despreading signal comprises a noise signal.
3. The method of claim 1 , further comprising duplicating the spread information signal.
4. The method of claim 1 wherein diversity encoded spread-spectrum signals recited in claim 1 wherein diversity-encoding includes at least one item of a set comprising providing a time offset, polarizing, applying a predetermined directionality, transmitting from a plurality of spatially separated transmitters, modulating with a predetermined carrier frequency, combining with a carrier having a predetermined mode, and transmitting signal in at least one predetermined subspace channel.
5. The method of claim 1 , further comprising a step of modulating the spread information signal or the despreading signal onto a carrier signal.
6. A method comprising:
generating an information-bearing wideband signal,
generating a decoding signal,
diversity-encoding at least one of the information-bearing wideband signal and the decoding signal, and
transmitting diversity-encoded spread-spectrum signals by coupling the information-bearing wideband signal and the decoding signal into a wireless communication channel, wherein the decoding signal is transmitted distinctly from the information-bearing wideband signal.
7. The method of claim 6 wherein the information-bearing wideband signal includes a noise signal.
8. The method of claim 6 wherein the step of diversity-encoding includes at least one item of a set including providing a time offset, polarizing, applying a predetermined directionality, transmitting from a plurality of spatially separated transmitters, modulating with a predetermined carrier frequency, combining with a carrier having a predetermined mode, and transmitting the signals in at least one predetermined subspace channel.
9. The method of claim 6 , further comprising a step of modulating the information-bearing wideband signal or the decoding signal onto a carrier signal.
10. A spread-spectrum transmitter comprising:
a wideband-signal generator to generate a plurality of wideband signals, at least one of the plurality of wideband signals being a despreading signal,
a modulator coupled to the wideband signal generator to modulate at least one information signal onto at least one of the plurality of wideband signals to generate a spread information signal,
a diversity processor to adjust at least one diversity parameter of at least one of the spread information signal and the despreading signal, and
a transmitter to transmit diversity-encoded spread-spectrum signals by coupling the spread information signal and the despreading signal into a wireless communication channel, wherein the despreading signal is to be transmitted distinctly from the spread information signal.
11. A spread-spectrum transmitter comprising:
a wideband-signal generator to generate a plurality of wideband signals, at least one of the plurality of wideband signals being a decoding signal,
a modulator coupled to the wideband signal generator to modulate information onto at least one of the plurality of wideband signals to generate an information-bearing wideband signal,
a diversity processor to adjust at least one diversity parameter of at least one of the information-bearing wideband signal and the decoding signal, and
a transmitter to transmit diversity-encoded spread-spectrum signals by coupling the spread information-bearing wideband signal and the decoding signal into a wireless communication channel, wherein the decoding signal is to be transmitted distinctly from the information-bearing wideband signal.