Multicode direct sequence spread spectrum
First Claim
1. A transceiver for transmitting a first stream of data symbols, the transceiver comprising:
- a converter for converting the first stream of data symbols into plural sets of N data symbols each;
first computing means for operating on the plural sets of N data symbols to produce modulated data symbols corresponding to an invertible randomized spreading of the first stream of data symbols; and
means to combine the modulated data symbols for transmission.
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Accused Products
Abstract
In this patent, we present MultiCode Direct Sequence Spread Spectrum (MC-DSSS) which is a modulation scheme that assigns up to N DSSS codes to an individual user where N is the number of chips per DSSS code. When viewed as DSSS, MC-DSSS requires up to N correlators (or equivalently up to N Matched Filters) at the receiver with a complexity of the order of N2 operations. In addition, a non ideal communication channel can cause InterCode Interference (ICI), i.e., interference between the N DSSS codes. In this patent, we introduce new DSSS codes, which we refer to as the "MC" codes. Such codes allow the information in a MC-DSSS signal to be decoded in a sequence of low complexity parallel operations which reduce the ICI. In addition to low complexity decoding and reduced ICI. MC-DSSS using the MC codes has the following advantages: (1) it does not require the stringent synchronization DSSS requires, (2) it does not require the stringent carrier recovery DSSS requires and (3) it is spectrally efficient.
246 Citations
32 Claims
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1. A transceiver for transmitting a first stream of data symbols, the transceiver comprising:
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a converter for converting the first stream of data symbols into plural sets of N data symbols each; first computing means for operating on the plural sets of N data symbols to produce modulated data symbols corresponding to an invertible randomized spreading of the first stream of data symbols; and means to combine the modulated data symbols for transmission. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A transceiver for transmitting a first stream of data symbols and receiving a second stream of data symbols, the transceiver comprising:
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a converter for converting the first stream of data symbols into plural sets of N data symbols each; first computing means for operating on the plural sets of N data symbols to produce sets of N modulated data symbols corresponding to an invertible randomized spreading of each set of N data symbols over N code symbols; means to combine the modulated data symbols for transmission; means for receiving a sequence of modulated data symbols, the modulated data symbols having been generated by an invertible randomized spreading of a second stream of data symbols over N code symbols; second computing means for operating on the sequence of modulated data symbols to produce an estimate of the second stream of data symbols; and means to combine output from the second computing means. - View Dependent Claims (18, 19, 20, 21, 22)
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23. A method of exchanging data streams between a plurality of transceivers, the method comprising the steps of:
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converting a first stream of data symbols into plural sets of N data symbols each; operating on the plural sets of N data symbols to produce modulated data symbols corresponding to a spreading of the first stream of data symbols over N code symbols; combining the modulated data symbols for transmission; and transmitting the modulated data symbols from a first transceiver at a time when no other of the plurality of transceivers is transmitting. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32)
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Specification