Synchronization and fault management in a distributed antenna system
In an embodiment, a method comprises: sending a message from a master unit of a distributed antenna system to a remote unit of the distributed antenna system, wherein the message includes a list of service frequencies and applied standards for a base station; sending a downlink signal generated based on a base station signal from the master unit to the remote unit; decoding the downlink signal based on the list of service frequencies and applied standards for the base station; extracting a base station clock signal from the decoded downlink signal; and synchronizing an internal clock of the remote unit to the base station clock using the extracted base station clock signal.
1. A method, comprising:
sending a message from a master unit of a distributed antenna system to a remote unit of the distributed antenna system, wherein the message includes a list of service frequencies and applied standards for a base station;
sending a downlink signal generated based on a base station signal from the master unit to the remote unit;
decoding, at the remote unit, the downlink signal based on the list of service frequencies and applied standards for the base station;
extracting, at the remote unit, a base station clock signal from the decoded downlink signal to produce an extracted base station clock signal; and
synchronizing, at the remote unit, an internal clock of the remote unit to a base station clock using the extracted base station clock signal.
2. The method of claim 1 , further comprising decoding the downlink signal and extracting the base station clock signal prior to filtering or buffering the downlink signal.
3. The method of claim 1 , further comprising sending an uplink packet from the remote unit to the master unit at a scheduled time interval, wherein the uplink packet includes a residual timestamp and a remote unit identifier.
4. The method of claim 3 , further comprising measuring an amount of jitter or clock phase noise of the internal clock of the remote unit based on the residual timestamp.
5. The method of claim 4 , further comprising providing 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 method of claim 3 , further comprising determining a path delay from the remote unit to the master unit on a run-time basis based on the residual timestamp.
7. The method 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 method of claim 1 , further comprising communicatively coupling an intermediate unit between the master unit and the remote unit.
9. The method of claim 8 , further comprising measuring, with the intermediate unit, an amount of jitter or clock phase of the internal clock of the remote unit based on a residual timestamp and remote unit identifier.
10. The method of claim 9 , further comprising providing phase locked loop correction information from the intermediate unit to the remote unit based on the measured jitter or clock phase noise of the internal clock of the remote unit.
11. The method of claim 1 , further comprising receiving an analog signal from the base station with an analog radio frequency (RF) interface of the master unit.
12. The method of claim 1 , further comprising receiving a digital signal from the base station with a digital interface of the master unit.
13. The method 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 method of claim 1 , further comprising:
sending a synchronization message to a second remote unit of the distributed antenna system, wherein the second remote unit is 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;
sending a message to the second remote unit including adjustments to playout delay of a playout buffer of the second remote unit;
synchronizing the internal clock of the second remote unit to the base station clock using information in the synchronization message; and
adjusting the playout delay of the playout buffer of the second remote unit based on the message.
15. A method, comprising:
receiving a message from a front end unit of a distributed antenna system, wherein the message includes a list of service frequencies and applied standards for a base station;
receiving a downlink signal that is generated based on a base station signal;
decoding, at a remote unit communicatively coupled to the front end unit, the downlink signal based on the list of service frequencies and applied standards for the base station to produce a decoded downlink signal;
extracting, at the remote unit, a base station clock signal from the decoded downlink signal to produce an extracted base station clock signal; and
synchronizing, at the remote unit, an internal clock of a remote unit to a base station clock using the extracted base station clock signal.
16. The method of claim 15 , further comprising sending an uplink packet to at least one of the front end unit or an intermediate unit at a scheduled time interval, wherein the uplink packet includes a residual timestamp and a remote unit identifier, wherein the remote unit identifier comprises a media access control address of the remote unit.
17. The method of claim 16 , further comprising adjusting 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. A method, comprising:
sending a synchronization message from a master unit of a distributed antenna system to a remote unit of the distributed antenna system, wherein the synchronization message includes information regarding a base station clock and measured jitter or clock phase of an internal clock of the remote unit;
sending a message to the remote unit including adjustments to playout delay of a playout buffer of the remote unit;
synchronizing the internal clock to the base station clock using the information in the synchronization message received from the master unit; and
adjusting the playout delay of the playout buffer of the remote unit based on the message from the master unit.
19. The method of claim 18 , further comprising:
sending 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; and
measuring an amount of jitter or clock phase of the internal clock of the remote unit based on the residual timestamp.
20. The method of claim 18 , wherein information regarding the measured jitter or clock phase of the internal clock comprises correction information to minimize the jitter or clock phase of the internal clock of the remote unit.