Synchronous transfer of streaming data in a distributed antenna system
Method and apparatus for generating a jitter reduced clock signal from signal transmitted over a communication medium includes receiving, with high speed data interface circuitry, a modulated signal that includes a binary encoded data stream. A recovered clock signal is generated from the modulated signal and tracks the long-term drift in the modulated signal. A jitter reduced clock signal is generated by filtering the recovered clock signal with a filtering circuit having a bandwidth sufficient to remove jitter while allowing the jitter reduced clock signal to track the drift in the modulated signal.
1. A method of generating a jitter reduced clock signal from a signal transmitted over a communication medium, the method comprising:
receiving a modulated signal that includes a binary encoded data stream; and
generating a jitter reduced clock signal by filtering a recovered clock signal with circuitry having a bandwidth sufficient to remove jitter while allowing the jitter reduced clock signal to track drift in the modulated signal, wherein the recovered clock signal is generated from the modulated signal, the recovered clock signal tracking long-term drift in the modulated signal.
2. The method of claim 1 , further comprising generating the jitter reduced clock signal by filtering the recovered clock signal using at least one of a phase-locked loop, a frequency-locked loop, or a narrowband filter.
3. The method of claim 1 , further comprising scaling a frequency of the jitter reduced clock signal to produce at least one scaled clock signal.
4. The method of claim 1 , wherein receiving the modulated signal that includes the binary encoded data stream comprises receiving the modulated signal using at least a one gigabit per second (Gbps) Ethernet interface.
5. The method of claim 1 , wherein the communication medium is a communication cable having at least one twisted pair cable.
6. The method of claim 4 , wherein the Ethernet interface is synchronous or asynchronous.
7. A distributed antenna system, comprising:
a master unit configured to clock a binary encoded data stream onto a data interface using a modulated signal; and
at least one remote unit configured to receive the modulated signal and binary encoded data stream from the master unit, the at least one remote unit including:
a circuit configured to filter a recovered clock signal, the circuit having a bandwidth sufficient to remove jitter while allowing a jitter reduced clock signal to track drift in the modulated signal in order to generate the jitter reduced clock signal, wherein the at least one remote unit is configured to generate the recovered clock signal from the modulated signal, the recovered clock signal tracking long-term drift in the modulated signal.
8. The system of claim 7 , wherein the circuit includes at least one of a phase-locked loop, a frequency-locked loop, or a narrowband filter.
9. The system of claim 7 , further comprising a scaling circuit configured to scale a frequency of the recovered clock signal to generate an output signal at a predetermined target frequency.
10. The system of claim 7 , wherein the data interface is coupled to a communication medium, between the master unit and the at least one remote unit, having at least one twisted pair cable.
11. The system of claim 7 , the master unit further including:
RF transceiver circuitry configured to communicate with a base transceiver station;
an auxiliary interface configured to communicate at least one of control data, maintenance data, Ethernet data, or WiFi data; and
a processor configured to multiplex data from the RF transceiver circuitry and the auxiliary interface for transmission to the at least one remote unit via the data interface, the processor further configured to de-multiplex data received from the data interface for transmission to the base transceiver station via the RF transceiver circuitry.
12. The system of claim 7 , wherein the data interface circuitry is an at least a one gigabit per second (Gbps) Ethernet interface.
13. A remote unit for use in a distributed antenna system comprising:
a data interface configured to couple the remote unit to a master unit of the distributed antenna system and to transceive a modulated signal with the master unit; and
a circuit configured to filter a recovered clock signal, the circuit having a bandwidth sufficient to remove jitter while allowing a jitter reduced clock signal to track drift in the modulated signal for generating a jitter reduced clock signal, wherein the remote unit is configured to generate a recovered clock signal from the modulated signal, the recovered clock signal tracking long-term drift in the modulated signal.
14. The remote unit of claim 13 , wherein the circuit includes at least one of a phase-locked loop, a frequency-locked loop, or a narrowband filter.
15. The remote unit of claim 13 , further comprising a scaling circuit configured to scale a frequency of the recovered clock signal to generate an output signal at a predetermined target frequency.
16. The remote unit of claim 13 , further comprising:
RF transceiver circuitry configured to communicate cellular and non-cellular data with a subscriber unit;
an auxiliary interface configured to communicate at least one of control data, maintenance data, Ethernet data, or WiFi data; and
a processing unit configured to de-multiplex data from the data interface for transmission by the RF transceiver circuitry or the auxiliary interface, the processing unit is further configured to multiplex data from the RF transceiver circuitry and the auxiliary interface for transmission on the data interface.
17. The remote unit of claim 16 , wherein the processing unit is configured to adjust the rate of data being transmitted on the data interface to match the capability of that data interface by excluding low priority data from the multiplexed stream.
18. The remote unit of claim 16 , wherein data communicated to the remote unit via the data interface includes at least one of digitized RF cellular voice data, digitized RF non-cellular voice data, digitized RF cellular data, digitized RF non-cellular data, control data, maintenance data, Ethernet data, or WiFi data.
19. The remote unit of claim 16 , wherein the data interface includes at least a one gigabit per second (Gbps) Ethernet interface.