Noise shaping technique for spread spectrum communications
AssigneeInterDigital Technology Corporation
InventorTimothy F. Moore, III
Life of this patent
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Abstract
A spread spectrum noise shaper uses a modulation technique to achieve a greater signal-to-noise or signal-to-interference ratio (SNR or SIR). The technique doubles the system SIR, in principle. This doubling yields a doubling in system capacity. SNR is increased by receiving the spread spectrum signal in the presence of less noise near the edge of the spread spectrum bandwidth. The technique requires only small additions to a conventional spread spectrum system, in the form of an extra modulator at the transmitter, and an extra demodulator and filter at the receiver.
Claims35
A method for transmitting a signal from a transmitting site to a receiving site, comprising:
- at the transmitting site:
- a. frequency translating the signal to a translated signal;
- b. spread spectrum encoding the translated signal into a spread signal;
- c. transmitting the spread signal;
- and at the receiving site:
- d. receiving the spread signal as a received signal;
- e. spread spectrum decoding the received signal into an intermediate frequency signal;
- and
- f. frequency translating the intermediate frequency signal to a replica of the signal.
A method for transmitting a signal, comprising:
- a. frequency translating the signal to a translated signal;
- b. spread spectrum encoding the translated signal into a spread signal;
- and
- c. transmitting the spread signal.
A method for receiving a signal that has been frequency translated and spread spectrum encoded, comprising:
- a. receiving the frequency translated and spread spectrum encoded signal as a received signal;
- b. spread spectrum decoding the received signal into an intermediate frequency signal;
- and
- c. frequency translating the intermediate frequency signal to a replica of the signal.
A system for transmitting a signal from a transmitting site to a receiving site, comprising:
- a. a transmit frequency translator for translating the signal to a translated signal;
- b. a spread spectrum encoder for spreading the spectrum of the translated signal to a spread signal;
- c. a transmitter for transmitting the spread signal;
- d. a receiver for receiving the spread and transmitted signal as a received signal;
- e. a spread spectrum decoder for decoding the received signal into an intermediate frequency signal;
- and
- f. a receive frequency translator for translating the intermediate frequency signal to a replica of the signal.
A system for transmitting a signal, comprising:
- a. a frequency translator for translating the signal to a translated signal;
- b. a spread spectrum encoder for encoding the translated signal into a spread signal;
- and
- c. a transmitter for transmitting the spread signal.
A system for receiving a signal that has been translated in frequency and spread spectrum encoded, comprising:
- a. a receiver for receiving the translated and spread signal as a received signal;
- b. a spread spectrum decoder for decoding the received signal into an intermediate frequency signal;
- and
- c. a frequency translator for translating the intermediate frequency signal to a replica of the signal.
An improved method for transmitting a source signal, in a system having a spread spectrum encoder for encoding a spread signal from a signal input, and a transmitter for transmitting the spread signal, wherein the improvement comprises frequency translating the source signal to a translated signal and inputting the translated signal to the spread spectrum encoder.
An improved method for receiving a signal that has been spread spectrum encoded, in a system for receiving the spread spectrum encoded signal as a received signal, and spread spectrum decoding the received signal into an output signal, wherein the improvement comprises frequency translating the output signal.
An improved system for transmitting a source signal, having a spread spectrum encoder for encoding a spread signal from a signal input, and a transmitter for transmitting the spread signal, wherein the improvement comprises a frequency translator for translating the source signal to a translated signal and inputting the translated signal to the spread spectrum encoder.
An improved system for receiving a signal that has been spread spectrum encoded, having a receiver for receiving the spread spectrum signal as a received signal, and a spread spectrum decoder for decoding the received signal into an output signal, wherein the improvement comprises a frequency translator for translating the output signal.
An improved system for modulating a signal exhibiting a bimodal power spectrum with a pseudo random signal to spread the power spectrum of said signal throughout a predetermined bandwidth, the improvement comprising reducing the effect of receiver correlation noise by pre-modulating the signal with a further signal to effect a separation of the bimodal portions of said power spectrum so that said bimodal portions lie outside the region of greatest correlation noise.
Dependencies are inferred from the claim text.