Method and apparatus for an optical cdma system
OwnerOlli-Pekka Hiironeninventor
Life of this patent
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Abstract
A method and an apparatus for transmitting an optical signal in an optical CDMA system. The system comprises transceivers (101 to 104) capable of sending and receiving optical signal sent and received through an optical fibre network. The optical signal is generated in a transmitter (100) where a digital data signal is at first pulse position modulated as a data symbol. Frequency hopping coding is conducted for the data symbol, and thereafter the data symbol is sent to a receiver (106) where the frequency hopping decoding and PPM demodulation are conducted.
Claims20
A method for generating an optical data signal of a digital data signal comprising at least two data bits, where said data signal is converted into a data symbol of the M-ary number system, characterized by comprising the steps of
- pulse position modulating said data symbol to an optical pulse sequence, and
- frequency hopping coding said optical pulse sequence to an optical data signal.
A method for generating a digital data signal of a received optical data signal, characterized in that said optical data signal is pulse position modulated and coded using frequency hopping and comprises at least two frequency pulse components, and the method comprises the steps of
- receiving frequency pulse components,
- converting said frequency pulse components into electrical pulses,
- performing frequency hopping decoding for said received frequency pulse components or for said electrical pulses by delaying said frequency components or said electrical pulses in relation to one another to the same instant of time,
- calculating the number of said electrical pulses in the different pulse positions of the PPM sequence,
- selecting the pulse position in the PPM sequence with most pulses as the data symbol, and
- pulse position demodulating said data symbol to a data bit string.
A transmitter apparatus (100) for sending an optical data signal in an optical CDMA system, the apparatus comprising a data source (313) for generating a data signal comprising at least two data bits, a light pulse source (315) for presenting said data signal as an optical signal, transmission means (317) for sending said optical signal from the transmitter apparatus (100), and conversion means for converting said data signal into a data symbol of the M-ary number system, characterized in that said transmitter apparatus (100) further comprises
- modulation means (314) for pulse position modulating said data symbol to an optical pulse sequence, and
- a frequency hopping encoder (316) for coding said optical pulse sequence to an optical data signal in time and frequency domain.
A receiver apparatus (106) for receiving an optical data signal in an optical CDMA system, the receiver apparatus (106) comprising means (413) for receiving the optical data signal at the receiver apparatus (106), characterized in that said optical data signal is pulse position modulated and coded using frequency hopping and comprises at least two frequency pulse components, and the receiver apparatus further comprises
- reception means (413) for receiving at least two optical frequency pulse components,
- conversion means (416) for converting the frequency pulse components into corresponding electrical pulses,
- decoding means (414) for conducting frequency hopping decoding for said received frequency pulse components, for said divided frequency pulse components or for said electrical pulses by delaying said frequency pulse components or said electrical pulses in relation to one another to the same instant of time,
- calculation means (417, 418) for calculating the number of said electrical pulses in the different pulse positions of the PPM sequence.
A system comprising an optical fibre network (105) at least two transceiver apparatuses (101 to 104), which are able to send and receive optical data signals through said fibre network, a data source (313) for generating a data signal comprising at least two data bits, a light pulse source (315) for presenting said data signal as an optical signal, transmission means (317) for sending said optical signal, and means (413) for receiving the optical data signal, and conversion means for converting said data signal into a data symbol of the M-ary number system, characterized in that said optical data signal is pulse position modulated and coded using frequency hopping and comprises at least two frequency pulse components, and that the system also comprises
- modulation means (314) for pulse position modulating said data symbol to an optical pulse sequence,
- a frequency hopping encoder (316) for coding said optical pulse sequence in time and frequency domain to an optical pulse signal,
- reception means for receiving at least the optical pulse signal comprising at least two optical frequency pulse components,
- conversion means for converting said frequency pulse components using said frequency pulse detectors into corresponding electrical pulses,
- coding means for conducting frequency hopping decoding for said received frequency pulse components or for said electrical pulses by delaying said frequency pulse components or said electrical pulses in relation to one another to the same instants of time,
- calculation means for calculating the number of said electrical pulses in the different pulse positions of the PPM sequence,
- selection means for selecting a data symbol by selecting the pulse position with most pulses as the data symbol, and
- demodulation means for demodulating said data symbol to a data bit string.
Dependencies are inferred from the claim text.