Synchronization and fault management in a distributed antenna system
In an embodiment, a distributed antenna system, comprises a master unit communicatively coupled to a base station; and a remote unit communicatively coupled to the master unit via a communication medium and located remotely from the master unit, wherein the remote unit includes an internal clock; wherein the master unit is configured to: send a message to the remote unit including a list of service frequencies and applied standards for the base station; send a downlink signal generated based on a base station signal to the remote unit; wherein the remote unit is configured to: decode the downlink signal based on the list of service frequencies and applied standards for the base station; extract a base station clock signal from the downlink signal; and synchronize the internal clock to the base station clock using the extracted base station clock signal.
1. A distributed antenna system, comprising:
a master unit communicatively coupled to a base station; and
a remote unit communicatively coupled to the master unit via a communication medium and located remotely from the master unit, wherein the remote unit includes an internal clock;
wherein the master unit is configured to:
send a message to the remote unit including a list of service frequencies and applied standards for the base station;
send a downlink signal generated based on a base station signal to the remote unit;
wherein the remote unit is configured to:
decode the downlink signal based on the list of service frequencies and applied standards for the base station;
extract a base station clock signal from the decoded downlink signal; and
synchronize the internal clock to the base station clock using the extracted base station clock signal.
2. The distributed antenna system of claim 1 , wherein the remote unit is configured to decode the downlink signal and extract the base station clock signal prior to filtering or buffering the downlink signal.
3. The distributed antenna system of claim 1 , wherein the remote unit is configured to send an uplink packet to the master unit at a scheduled time interval, wherein the uplink packet includes a residual timestamp and a remote unit identifier.
4. The distributed antenna system of claim 3 , wherein the master unit is configured to measure an amount of jitter or clock phase noise of the internal clock of the remote unit based on the residual timestamp.
5. The distributed antenna system of claim 4 , wherein the master unit is configured to provide correction information to the remote unit based on the measured jitter or clock phase noise of the internal clock of the remote unit.
6. The distributed antenna system of claim 3 , wherein the master unit is configured to determine a path delay from the remote unit to the master unit on a run-time basis based on the residual timestamp.
7. The distributed antenna system of claim 1 , wherein the remote unit comprises an intermediate unit, a remote antenna unit, an extension unit, or a remote radio head.
8. The distributed antenna system of claim 1 , further comprising an intermediate unit communicatively coupled between the master unit and the remote unit.
9. The distributed antenna system of claim 8 , wherein the intermediate unit is configured to measure an amount of jitter or clock phase noise of the internal clock of the remote unit based on the residual timestamp and remote unit identifier.
10. The distributed antenna system of claim 9 , wherein the intermediate unit is configured to provide phase locked loop correction information to the remote unit based on the measured jitter or clock phase noise of the internal clock of the remote unit.
11. The distributed antenna system of claim 1 , wherein the master unit comprises an analog radio frequency (RF) interface configured to receive an analog signal from the base station.
12. The distributed antenna system of claim 1 , wherein the master unit comprises a digital interface configured to receive a digital signal from the base station.
13. The distributed antenna system of claim 1 , wherein the list of service frequencies and applied standards includes one or more of: an absolute radio-frequency channel number; a frequency band; a frequency range; or a cell identifier.
14. The distributed antenna system of claim 1 , further comprising a second remote unit communicatively coupled to the master unit via a second communication medium and located remotely from the master unit, wherein the second remote unit includes an internal clock;
wherein the master unit is further configured to:
send a synchronization message to the second remote unit including information regarding the base station clock and measured jitter or clock phase noise of the internal clock of the second remote unit;
send a message to the second remote unit including adjustments to playout delay of a playout buffer of the second remote unit;
wherein the second remote unit is configured to:
synchronize the internal clock of the second remote unit to the base station clock using the information in the synchronization message received from the master unit; and
adjust the playout delay of the playout buffer of the second remote unit based on the message from the master unit.
15. A remote unit of a distributed antenna system, comprising:
an interface communicatively coupled to a front end unit over a communication medium, wherein the remote unit is configured to receive a message from a front end unit of the distributed antenna system that includes a list of service frequencies and applied standards for a base station, wherein the remote unit is configured to receive a downlink signal generated based on a base station signal to the remote unit, wherein the front end unit is communicatively coupled to the base station and the remote unit, wherein the remote unit is located remotely from the front end unit;
a processor coupled to a memory, wherein the processor is configured to:
decode the downlink signal based on the list of service frequencies and applied standards for the base station to produce a decoded downlink signal;
extract a base station clock signal from the decoded downlink signal to produce an extracted base station clock signal;
synchronize an internal clock of the remote unit to the base station clock using the extracted base station clock signal.
16. The remote unit of claim 15 , wherein the remote unit is further configured to send an uplink packet from the remote unit to at least one of the front end unit or an intermediate unit communicatively coupled to the remote unit at a scheduled time interval, wherein the uplink packet includes a residual timestamp and a remote unit identifier.
17. The remote unit of claim 16 , wherein the remote unit is further configured to adjust the internal clock of the remote unit based on correction information provided from at least one of the front end unit or the intermediate unit, wherein the correction information is based on a measured amount of jitter or clock phase noise of the internal clock of the remote unit.
18. The remote unit of claim 16 , wherein the remote unit identifier comprises a media access control address of the remote unit.
19. The remote unit of claim 15 , wherein the remote unit comprises an intermediate unit, a remote antenna unit, an extension unit, or a remote radio head.
20. The remote unit of claim 15 , wherein the list of service frequencies and applied standards includes at least one of: an absolute radio-frequency channel number; a frequency band; a frequency range; or a cell identifier.
21. A distributed antenna system, comprising:
a master unit communicatively coupled to a base station; and
a remote unit communicatively coupled to the master unit via a communication medium and located remotely from the master unit, wherein the remote unit includes an internal clock;
wherein the master unit is configured to:
send a synchronization message to the remote unit including information regarding the base station clock and measured jitter or clock phase noise of the internal clock;
send a message to the remote unit including adjustments to playout delay of a playout buffer of the remote unit;
wherein the remote unit is configured to:
synchronize the internal clock to the base station clock using the information in the synchronization message received from the master unit; and
adjust the playout delay of the playout buffer of the remote unit based on the message from the master unit.
22. The distributed antenna system of claim 21 , wherein the remote unit is configured to send an uplink packet to the master unit at a scheduled time interval, wherein the uplink packet includes a residual timestamp and a remote unit identifier;
wherein the master unit is configured to measure the amount of jitter or clock phase noise of the internal clock of the remote unit based on the residual timestamp.
23. The distributed antenna system of claim 21 , wherein information regarding the measured jitter or clock phase noise of the internal clock comprises correction information to minimize the jitter or clock phase noise of the internal clock of the remote unit.