Multiplex communications – Generalized orthogonal or special mathematical techniques – Particular set of orthogonal functions
Patent
1995-05-31
1997-11-11
Olms, Douglas W.
Multiplex communications
Generalized orthogonal or special mathematical techniques
Particular set of orthogonal functions
H04J 1100
Patent
active
056871660
ABSTRACT:
The OCDMA waveform of the present invention uses hi-phase PN modulation (BPSK PN chip modulation) in conjunction with MPSK or MQASK data modulation (QPSK data modulation is one preferred embodiment) to increase bandwidth efficiency. The number of orthogonal users that can be placed on a single carrier is equal to, at most, the length of the orthogonal binary sequence. The Radamacher-Walsh (RW) sequence chip rate must be 4" times the symbol rate (where n is a positive integer) since the symbol transitions must be synchronized to the RW period to guarantee orthogonality of the multiple users when data transitions are present. The symbol rate for QPSK modulation is one-half that for BPSK modulation. As a result, twice as many orthogonal functions are available for a given clock rate for QPSK as for BPSK modulation. That is, an OCDMA system with QPSK data can support twice as many users in a given bandwidth as an OCDMA system with BPSK data.
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Bustamante Herman A.
Magill David T.
Natali Francis D.
Olms Douglas W.
Patel Ajit
Stanford Telecommunications, Inc.
Zegeer Jim
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