Analog distributed antenna systems (DASS) supporting distribution of digital communications signals interfaced from a digital signal source and analog radio frequency (RF) communications signals
View Patent ↗Embodiments disclosed in the detailed description include analog distributed antenna system (DAS) supporting distribution of digital communications signals interfaced from a digital signal source and analog radio frequency (RF) communications signals. Analog RF communications signals received from analog RF signal sources are distributed in the analog DAS without being digitized. The analog DAS is also configured to interface with digital signal sources and compatibly distribute digital communications signals. Hence, a digital signal interface in head-end equipment (HEE) is configured to convert downlink digital communications signals to downlink analog RF communications signals for distribution to a plurality of remote units. The digital signal interface is also configured to convert uplink analog RF communications signals to uplink digital communications signals for distribution to the digital signal source(s). By providing the digital signal interface in the HEE, the analog DAS can be configured to distribute digital communications signals to analog DAS components.
1. A method for distributing analog radio frequency (RF) communications signals and digital communications signals in an analog distributed antenna system (DAS), comprising:
distributing downlink analog RF communications signals and downlink digital communications signals in the analog DAS, comprising:
receiving at least one first downlink analog RF communications signal from at least one analog RF signal source;
receiving at least one downlink digital communications signal from at least one digital signal source;
converting the at least one downlink digital communications signal to at least one second downlink analog RF communications signal;
modulating the at least one first downlink analog RF communications signal and the at least one second downlink analog RF communications signal to generate at least one combined downlink analog RF communications signal; and
distributing the at least one combined downlink analog RF communications signal to at least one remote unit among a plurality of remote units in the analog DAS over a downlink communications medium; and
distributing uplink analog RF communications signals and uplink digital communications signals in the analog DAS, comprising:
receiving at least one combined uplink analog RF communications signal from the at least one remote unit among the plurality of remote units in the analog DAS over an uplink communications medium;
demodulating the at least one combined uplink analog RF communications signal to generate at least one first uplink analog RF communications signal and at least one second uplink analog RF communications signal;
providing the at least one first uplink analog RF communications signal to the at least one analog RF signal source;
converting the at least one second uplink analog RF communications signal to at least one uplink digital communications signal; and
providing the at least one uplink digital communications signal to the at least one digital signal source,
wherein converting the at least one downlink digital communications signal to the at least one second downlink analog RF communications signal further comprises:
receiving formatted downlink data packets from the at least one downlink digital communications signal;
de-capsulating the formatted downlink data packets into consecutive downlink digital words;
modulating the consecutive downlink digital words to generate at least one downlink digital intermediate frequency (IF) signal;
converting the at least one downlink digital IF signal to at least one downlink analog IF signal;
attenuating unwanted products and harmonics in the at least one downlink analog IF signal;
modulating the at least one downlink analog IF signal to generate the at least one second downlink analog RF communications signal;
attenuating unwanted products and harmonics in the at least one second downlink analog RF communications signal; and
adjusting the at least one second downlink analog RF communications signal to a first predetermined power level.
2. The method of claim 1 , further comprising receiving common public radio interface (CPRI) formatted downlink data packets from the at least one downlink digital communications signal.
3. The method of claim 1 , further comprising converting the at least one downlink digital IF signal to the at least one downlink analog IF signal using a digital-to-analog converter (DAC).
4. The method of claim 1 , further comprising modulating the at least one downlink analog IF signal to generate the at least one second downlink analog RF communications signal based on a mixing frequency provided by a first local oscillator.
5. The method of claim 1 , wherein converting the at least one second uplink analog RF communications signal to the at least one uplink digital communications signal further comprises:
adjusting the at least one second uplink analog RF communications signal to a second predetermined power level;
attenuating unwanted products and harmonics in the at least one second uplink analog RF communications signal;
modulating the at least one second uplink analog RF communications signal to generate at least one uplink analog intermediate frequency (IF) signal;
attenuating unwanted products and harmonics in the at least one uplink analog IF signal;
converting the at least one uplink analog IF signal to at least one uplink digital IF signal;
demodulating the at least one uplink digital IF signal to generate consecutive uplink digital words;
encapsulating the consecutive uplink digital words in formatted uplink data packets; and
providing the formatted uplink data packets in the at least one uplink digital communications signal.
6. The method of claim 5 , further comprising providing common public radio interface (CPRI) formatted uplink data packets in the at least one uplink digital communications signal.
7. The method of claim 6 , further comprising converting the at least one uplink analog IF signal to the at least one uplink digital IF signal using an analog-to-digital converter (ADC).
8. The method of claim 6 , further comprising modulating the at least one second uplink analog RF communications signal to generate the at least one uplink analog IF signal based on a mixing frequency provided by a second local oscillator.
9. The method of claim 1 , wherein converting the at least one downlink digital communications signal to the at least one second downlink analog RF communications signal further comprises:
receiving formatted downlink data packets from the at least one downlink digital communications signal;
de-capsulating the formatted downlink data packets into consecutive downlink digital words represented in at least one quadrature (Q) stream and at least one in-phase (I) stream;
modulating the at least one Q stream and the at least one I stream to generate at least one downlink digital baseband quadrature (Q) signal and at least one downlink digital baseband in-phase (I) signal, respectively;
converting the at least one downlink digital baseband Q signal and the at least one downlink digital baseband I signal to at least one downlink analog baseband Q signal and at least one downlink analog baseband I signal, respectively;
attenuating unwanted products and harmonics in the at least one downlink analog baseband Q signal and the at least one downlink analog baseband I signal;
combining the at least one downlink analog baseband Q signal and the at least one downlink analog baseband I signal to generate the at least one second downlink analog RF communications signal;
attenuating unwanted products and harmonics in the at least one second downlink analog RF communications signal; and
adjusting the at least one second downlink analog RF communications signal to a first predetermined power level.
10. The method of claim 9 , further comprising receiving common public radio interface (CPRI) formatted downlink data packets from the at least one downlink digital communications signal.
11. The method of claim 10 , further comprising converting the at least one downlink digital baseband Q signal and the at least one downlink digital baseband I signal to the at least one downlink analog baseband Q signal and the at least one downlink analog baseband I signal, respectively, using digital-to-analog converters (DACs).
12. The method of claim 10 , further comprising modulating the at least one downlink analog baseband Q signal and the at least one downlink analog baseband I signal to generate the at least one second downlink analog RF communications signal based on a mixing frequency provided by a first local oscillator.
13. The method of claim 1 , wherein converting the at least one second uplink analog RF communications signal to the at least one uplink digital communications signal further comprises:
adjusting the at least one second uplink analog RF communications signal to a second predetermined power level;
attenuating unwanted products and harmonics in the at least one second uplink analog RF communications signal;
separating the at least one second uplink analog RF communications signal to generate at least one uplink analog baseband quadrature (Q) signal and at least one uplink analog baseband in-phase (I) signal;
attenuating unwanted products and harmonics in the at least one uplink analog baseband Q signal and the at least one uplink analog baseband I signal;
converting the at least one uplink analog baseband Q signal and the at least one uplink analog baseband I signal to at least one uplink digital baseband Q signal and at least one uplink digital baseband I signal, respectively;
demodulating the at least one uplink digital baseband Q signal and the at least one uplink digital baseband I signal to generate consecutive uplink digital words represented in at least one Q stream and at least one I stream, respectively;
encapsulating the at least one Q stream and the at least one I stream into formatted uplink data packets; and
providing the formatted uplink data packets in the at least one uplink digital communications signal.
14. The method of claim 13 , further comprising providing common public radio interface (CPRI) formatted uplink data packets in the at least one uplink digital communications signal.
15. The method of claim 14 , further comprising converting the at least one uplink analog baseband Q signal and the at least one uplink analog baseband I signal to at least one uplink digital baseband Q signal and at least one uplink digital baseband I signal, respectively, using analog-to-digital converters (ADCs).
16. The method of claim 14 , further comprising modulating the at least one second uplink analog RF communications signal to generate the at least one uplink analog baseband Q signal and the at least one uplink analog baseband I signal based on a mixing frequency provided by a second local oscillator.