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EP0681376A2
Expired / Lapsed
EP
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Methods of and devices for spread spectrum communication systems using forward error correction
Assignee: AT&T Inc
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Filing: 1995-04-19
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Granted: —
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Expires: 2015-04-19
Abstract
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. The present invention's coding process (i.e.,UEP SSMA) utilizes bandwidth in a closer to optimal manner than known methods and may be implemented by applying a first and a second error protection process to one more and to one less significant portion of a signal wherein the first error protection process provides a greater amount of error protection than the second. The disclosure also describes a method and aparatus for generating a modulated signal having a first and second segment, the first segment being more significant than the second segment and comprising a first time portion of the signal and a second segment comprising a second time portion of the signal wherein the duration of the first time portion is increased relative to the duration of the second time portion (VT UEP). The present invention's coding process may be also implemented using combinations of variable time ("VT") UEP, variable code ("VC") UEP, or variable power ("VP") UEP methods.
Inventors
- 👤 Nambirajan Seshadri
- 👤 Carl-Erik Wilhelm Sundberg
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 11:22
CPC Classifications
H; H04; H04L; H04L1/00; H04L1/004; H04L1/0056; H04L1/0071; H03; H03M; H03M13/00; H03M13/35; H04B; H04B1/00; H04B1/69; H04B1/707; H04L1/0041; H04L1/0045; H04L1/007; H04L2001/0098
Claims Analysis
Total Claims: 58
Claim 1
Independent Claim
77 words
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.
Claim 2
Dependent Claim
26 words
The apparatus of claim 1 wherein the means for applying the spread spectrum encoding process comprises means for applying a code division multiple access coding process.
Claim 3
Dependent Claim
30 words
The apparatus of claim 2 wherein the means for applying the code division multiple access coding process comprises means for applying a direct sequence code division multiple access coding process.
Claim 4
Dependent Claim
73 words
In a method of processing a signal, the method including applying a spread spectrum coding 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.
Claim 5
Dependent Claim
24 words
The method of claim 4 wherein the step of applying the spread spectrum encoding process comprises applying a code division multiple access coding process.
Claim 6
Dependent Claim
28 words
The method of claim 5 wherein the step of applying the code division multiple access coding process comprises applying a direct sequence code division multiple access coding process.
Claim 7
Dependent Claim
60 words
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.
Claim 8
Dependent Claim
26 words
The apparatus of claim 7 wherein the means for applying the spread spectrum decoding process comprises means for applying a code division multiple access decoding process.
Claim 9
Dependent Claim
30 words
The apparatus of claim 8 wherein the means for applying the code division multiple access decoding process comprises means for applying a direct sequence code division multiple access decoding process.
Claim 10
Dependent Claim
56 words
In a method for processing a signal, the method including applying a code division 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.
Claim 11
Dependent Claim
24 words
The method of claim 10 wherein the step of applying the spread spectrum decoding process comprises applying a code division multiple access decoding process.
Claim 12
Dependent Claim
28 words
The method of claim 11 wherein the step of applying the code division multiple access decoding process comprises applying a direct sequence code division multiple access decoding process.
Claim 13
Dependent Claim
94 words
In a method of processing a signal including the steps of 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.
Claim 14
Dependent Claim
31 words
The method of claim 13 further comprising the step of spreading the modulated signal to generate a spread spectrum signal, the spreading comprising combining the modulated signal with a spreading signal.
Claim 15
Dependent Claim
36 words
The method of claim 13 further comprising the steps of: (a) modulating a radio frequency carrier with a spread spectrum signal to generate a modulated radio frequency signal; and (b) transmitting the modulated radio frequency signal.
Claim 16
Dependent Claim
59 words
The method of claim 13 wherein the signal is generated by: (a) receiving an analog voice signal at a transmitter; (b) coding the analog voice signal to generate a digitized voice signal; (c) applying a forward error correction code to the digitized voice signal to generate an intermediate signal; and (d) interleaving the intermediate signal to generate the signal.
Claim 17
Dependent Claim
36 words
The method of claim 13 wherein both the first segment and the second segment are modulated and wherein the increase in the first time portion is the same as the decrease in the second time portion.
Claim 18
Dependent Claim
24 words
The method of claim 16 wherein the step of interleaving comprises interleaving the intermediate signal based upon a basic time unit of the signal.
Claim 19
Dependent Claim
18 words
The method of claim 14 wherein the step of spreading comprises the use of an orthogonal spreading sequence.
Claim 20
Dependent Claim
100 words
In an apparatus for processing a signal including means for applying a spread spectrum coding process, the signal being a function of time, the improvement comprising: means for 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 means for modulating comprising means for increasing the duration of the first time portion relative to the duration of the second time portion.
Claim 21
Dependent Claim
32 words
The apparatus of claim 20 further comprising means for spreading the modulated signal to generate a spread spectrum signal, the means for spreading comprising combining the modulated signal with a spreading signal.
Claim 22
Dependent Claim
37 words
The apparatus of claim 20 further comprising: (a) means for modulating a radio frequency carrier with a spread spectrum signal to generate a modulated radio frequency signal; and (b) means for transmitting the modulated radio frequency signal.
Claim 23
Dependent Claim
67 words
The apparatus of claim 20 wherein the signal is generated by: (a) means for receiving an analog voice signal at a transmitter; (b) means for coding the analog voice signal to generate a digitized voice signal; (c) means for applying a forward error correction code to the digitized voice signal to generate an intermediate signal; and (d) means for interleaving the intermediate signal to generate the signal.
Claim 24
Dependent Claim
39 words
The apparatus of claim 20 wherein the means for modulating modulates both the first segment and the second segment and wherein the increase in the first time portion is the same as the decrease in the second time portion.
Claim 25
Dependent Claim
26 words
The apparatus of claim 23 wherein the means for interleaving comprises means for interleaving the intermediate signal based upon a basic time unit of the signal.
Claim 26
Dependent Claim
18 words
The apparatus of claim 21 wherein the means for spreading comprises means for using an orthogonal spreading sequence.
Claim 27
Dependent Claim
94 words
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.
Claim 28
Dependent Claim
47 words
The method of claim 27 wherein the step of variable time demodulating comprises: (a) despreading the signal to generate a despread signal; (b) deinterleaving the despread signal to generate a deinterleaved signal: and (c) demultiplexing the deinterleaved signal to generate a first signal and a second signal.
Claim 29
Dependent Claim
36 words
The method of claim 28 further comprising: (a) generating a first series of soft decision values based upon the first signal; and (b) generating a second series of soft decision values based upon the second signal.
Claim 30
Dependent Claim
41 words
The method of claim 27 wherein the step of variable time demodulating demodulates both the first segment and the second segment and wherein the increase in the second time portion is the same as the decrease in the first time portion.
Claim 31
Dependent Claim
24 words
The method of claim 28 wherein the step of deinterleaving comprises deinterleaving the intermediate signal based upon a basic time unit of the signal.
Claim 32
Dependent Claim
102 words
In an apparatus Including means for applying a spread spectrum decoding method to a signal, the signal being a function of time, the improvement comprising: means for 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 means for variable time demodulating comprising means for increasing the duration of the second time portion relative to the first time portion.
Claim 33
Dependent Claim
53 words
The apparatus of claim 32 wherein the means for variable time demodulating comprises: (a) means for despreading the signal to generate a despread signal; (b) means for deinterleaving the despread signal to generate a deinterleaved signal; and (c) means for demultiplexing the deinterleaved signal to generate a first signal and a second signal.
Claim 34
Dependent Claim
40 words
The apparatus of claim 33 further comprising: (a) means for generating a first series of soft decision values based upon the first signal; and (b) means for generating a second series of soft decision values based upon the second signal.
Claim 35
Dependent Claim
41 words
The apparatus of claim 32 wherein the means for variable time demodulating demodulates both the first segment and the second segment and wherein the increase in the second time portion is the same as the decrease in the first time portion.
Claim 36
Dependent Claim
26 words
The apparatus of claim 33 wherein the means for deinterleaving comprises means for deinterleaving the intermediate signal based upon a basic time unit of the signal.
Claim 37
Dependent Claim
99 words
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 power modulator; and (b) means for applying a variable time modulator.
Claim 38
Dependent Claim
99 words
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 power modulator; and (b) means for applying a variable rate coder.
Claim 39
Dependent Claim
99 words
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.
Claim 40
Dependent Claim
107 words
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 power modulator; (b) means for applying a variable time modulator; and (c) means for applying a variable rate coder.
Claim 41
Dependent Claim
28 words
The apparatus of claim 20,37,38,39 or 40 wherein the means for applying the spread spectrum encoding process comprises means for applying a code division multiple access coding process.
Claim 42
Dependent Claim
30 words
The apparatus of claim 41 wherein the means for applying the code division multiple access coding process comprises means for applying a direct sequence code division multiple access coding process.
Claim 43
Dependent Claim
118 words
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.
Claim 44
Dependent Claim
118 words
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 rate decoder.
Claim 45
Dependent Claim
82 words
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.
Claim 46
Dependent Claim
126 words
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.
Claim 47
Dependent Claim
28 words
The apparatus of claim 32,43,44,45 or 46 wherein the means for applying the spread spectrum decoding process comprises means for applying a code division multiple access decoding process.
Claim 48
Dependent Claim
30 words
The apparatus of claim 47 wherein the means for applying the code division multiple access decoding process comprises means for applying a direct sequence code division multiple access decoding process.
Claim 49
Dependent Claim
108 words
In a method of processing a signal, the method including the step of 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 time modulator to the signal to generate an intermediate modulated signal; and (b) applying a variable power modulator to the intermediate modulated signal.
Claim 50
Dependent Claim
108 words
In a method of processing a signal, the method including the step of 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 power modulator to the intermediate modulated signal.
Claim 51
Dependent Claim
107 words
In a method of processing a signal, the method including means for 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.
Claim 52
Dependent Claim
26 words
The method of claim 13,49,50 or 51 wherein the step of applying the spread spectrum encoding process comprises applying a code division multiple access coding process.
Claim 53
Dependent Claim
28 words
The method of claim 52 wherein the step of applying the code division multiple access coding process comprises applying a direct sequence code division multiple access coding process.
Claim 54
Dependent Claim
109 words
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.
Claim 55
Dependent Claim
109 words
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.
Claim 56
Dependent Claim
74 words
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.
Claim 57
Dependent Claim
26 words
The method of claim 27,54,55 or 56 wherein the step of applying the spread spectrum decoding process comprises applying a code division multiple access decoding process.
Claim 58
Dependent Claim
28 words
The method of claim 57 wherein the step of applying the code division multiple access decoding process comprises applying a direct sequence code division multiple access decoding process.
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