Methods of and devices for enhancing communications that use spread spectrum technology
First Claim
1. A method of processing a signal comprising applying a spread spectrum coding process, the signal being a function of time, the improvement comprising:
- modulating the signal to generate a modulated signal, the signal comprising a first segment and a second segment, the first segment being more significant than the second segment and comprising a first time portion of the signal, the second segment comprising a second time portion of the signal, the modulating increasing the duration of the first time portion relative to the duration of the second time portion and wherein the increase in the first time portion is substantially the same as the decrease in the second time portion.
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Accused Products
Abstract
We have invented methods of and devices for introducing unequal error protection into spread spectrum communication systems. One embodiment of the invention addresses certain inefficiencies of the standard known as IS-95 used, for example, in some mobile direct sequence code division multiple access ("DS-CDMA") phone systems. The invention allows for increased system capacity and/or improved quality. More specifically, spread spectrum multiple access ("SSMA") coding may be combined with the concept of unequal error protection ("UEP"), resulting in an UEP SSMA coding process. IS-95, in order to make significant portions of a signal highly immune to errors, has imposed the same high degree of error immunity on less significant portions of the signal (when, in fact, a lower degree would suffice) and, thus, wastes bandwidth. The present invention'"'"'s coding process (i.e., UEP SSMA) utilizes bandwidth in a closer to optimal manner than known methods.
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Citations
44 Claims
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1. A method of processing a signal comprising applying a spread spectrum coding process, the signal being a function of time, the improvement comprising:
modulating the signal to generate a modulated signal, the signal comprising a first segment and a second segment, the first segment being more significant than the second segment and comprising a first time portion of the signal, the second segment comprising a second time portion of the signal, the modulating increasing the duration of the first time portion relative to the duration of the second time portion and wherein the increase in the first time portion is substantially the same as the decrease in the second time portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 44)
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9. In a method including applying a spread spectrum decoding method to a signal, the signal being a function of time, the improvement comprising:
variable time demodulating the signal to generate a variable time demodulated signal, the signal comprising a first segment and a second segment, the first segment being more significant than the second segment and comprising a first time portion of the signal, the second segment comprising a second time portion of the signal, the variable time demodulating comprising increasing the duration of the second time portion relative to the first time portion, and wherein the increase in the second time portion is substantially the same as the decrease in the first time portion. - View Dependent Claims (10, 11, 12, 13, 14)
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15. In an apparatus for processing a signal, the apparatus including means for applying a spread spectrum encoding process to the signal, the improvement comprising:
means for applying a first error protection process to at least one more significant portion of the signal and a second error protection process to at least one less significant portion of the signal wherein the first error protection process provides a greater amount of error protection than the second error protection process, the means for applying comprising; (a) means for applying a variable time modulator; and (b) means for applying a variable rate coder. - View Dependent Claims (16, 17)
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18. In an apparatus for processing a signal, the apparatus including means for applying a spread spectrum encoding process to the signal, the improvement comprising:
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means for applying a first error protection process to at least one more significant portion of the signal and a second error protection process to at least one less significant portion of the signal wherein the first error protection process provides a greater amount of error protection than the second error protection process, the means for applying comprising; (a) means for applying a variable power modulator; (b) means for applying a variable time modulator; and (c) means for applying a variable rate coder. - View Dependent Claims (19, 20)
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21. In an apparatus for processing a signal, the apparatus including means for applying a spread spectrum decoding process to the signal, the improvement comprising:
means for decoding at least one more significant portion of the signal using a first error protection decoding process and at least one less significant portion of the signal using a second error protection decoding process, the means for decoding comprising; (a) means for demultiplexing a signal to generate a first segment of the signal and a second segment of the signal, means for decoding the first segment with a first channel decoder, and means for decoding the second segment with the second channel decoder; and (b) means for applying a variable time demodulator. - View Dependent Claims (22, 23)
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24. In an apparatus for processing a signal, the apparatus including means for applying a spread spectrum decoding process to the signal, the improvement comprising:
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means for decoding at least one more significant portion of the signal using a first error protection decoding process and at least one less significant portion of the signal using a second error protection decoding process, the means for decoding comprising; (a) means for demultiplexing a signal to generate a first segment of the signal and a second segment of the signal, means for decoding the first segment with a first channel decoder, and means for decoding the second segment with the second channel decoder; and (b) means for applying a variable rate decoder. - View Dependent Claims (25, 26)
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27. In an apparatus for processing a signal, the apparatus including means for applying a spread spectrum decoding process to the signal, the improvement comprising:
means for decoding at least one more significant portion of the signal using a first error protection decoding process and at least one less significant portion of the signal using a second error protection decoding process, the means for decoding comprising; (a) means for applying a variable time demodulator; and (b) means for applying a variable rate decoder. - View Dependent Claims (28, 29)
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30. In an apparatus for processing a signal, the apparatus including means for applying a spread spectrum decoding process to the signal, the improvement comprising:
means for decoding at least one more significant portion of the signal using a first error protection decoding process and at least one less significant portion of the signal using a second error protection decoding process, the means for decoding comprising; (a) means for demultiplexing a signal to generate a first segment of the signal and a second segment of the signal, means for decoding the first segment with a first channel decoder, and means for decoding the second segment with the second channel decoder; (b) means for applying a variable time demodulator; and (c) means for applying a variable rate decoder. - View Dependent Claims (31, 32)
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33. A method of processing a signal, comprising applying a spread spectrum encoding process to the signal, the improvement comprising:
applying a first error protection process to at least one more significant portion of the signal and a second error protection process to at least one less significant portion of the signal wherein the first error protection process provides a greater amount of error protection than the second error protection process, the step of applying comprising; (a) applying a variable rate coder to the signal to generate an intermediate modulated signal; and (b) applying a variable time modulator to the intermediate modulated signal. - View Dependent Claims (34, 35)
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36. In a method of processing a signal, the method including the step of applying a spread spectrum decoding process to the signal, the improvement comprising:
decoding at least one more significant portion of the signal using a first error protection decoding process and at least one less significant portion of the signal using a second error protection decoding process, the step of decoding comprising; (a) demultiplexing a signal to generate a first segment of the signal and a second segment of the signal, decoding the first segment with a first channel decoder, and decoding the second segment with the second channel decoder; and (b) applying a variable time demodulator. - View Dependent Claims (37, 38)
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39. In a method of processing a signal, the method including the step of applying a spread spectrum decoding process to the signal, the improvement comprising:
decoding at least one more significant portion of the signal using a first error protection decoding process and at least one less significant portion of the signal using a second error protection decoding process, the step of decoding comprising; (a) demultiplexing a signal to generate a first segment of the signal and a second segment of the signal, decoding the first segment with a first channel decoder, and decoding the second segment with the second channel decoder; and (b) applying a variable rate decoder. - View Dependent Claims (40, 41)
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42. In a method of processing a signal, the method including applying a spread spectrum decoding process to the signal, the improvement comprising:
decoding at least one more significant portion of the signal using a first error protection decoding process and at least one less significant portion of the signal using a second error protection decoding process, the step of decoding comprising; (a) applying a variable time demodulator; and (b) applying a variable rate decoder. - View Dependent Claims (43)
Specification