Re-timing a packetized radio flow to clean noise induced by packet delay variation of a packet network
Techniques are described to provide for re-timing a packetized radio flow to clean noise induced by packet delay variation of a packet network. In one example, a method includes receiving, at a first node of a fronthaul network, a Radio over Ethernet (RoE) frame transmitted by a second node in which the RoE frame comprises a Common Public Radio Interface (CPRI) bit stream associated with a first radio device, a sequence number, and a first time stamp. The method may further include generating a second time stamp by the first node upon obtaining the RoE frame; calculating an induced delay value based, at least in part, on the first time stamp and the second time stamp; calculating a re-timing value based on a re-timing interval and the induced delay value; and transmitting the CPRI bit stream to a second radio device based on the re-timing value.
1. A method comprising:
obtaining a Radio over Ethernet (RoE) frame, wherein the RoE frame comprises a Common Public Radio Interface (CPRI) bit stream and a first time stamp;
determining an induced delay value associated with the RoE frame, wherein determining the induced delay value includes comparing a seconds-bit of the first time stamp to a seconds-bit of a second time stamp generated when the RoE frame is obtained to determine whether a second rollover has occurred and wherein based on determining that a second rollover has not occurred, the induced delay value is determined by calculating a difference between the first time stamp and the second time stamp, and based on determining that a second rollover has occurred, the induced delay value is determined by calculating a difference between a maximum counter value and the first time stamp and adding the second time stamp to the difference;
calculating a re-timing value based on a difference between a re-timing interval and the induced delay value; and
transmitting the CPRI bit stream based on the re-timing value.
2. The method of claim 1 , wherein the transmitting is performed using a re-timer buffer.
3. The method of claim 1 , wherein at least one of:
a sequence number and the first time stamp are contained within an ordering information field of the RoE frame;
the first time stamp is contained within a fixed-sized RoE extension header; and
the first time stamp is contained with a variable-sized RoE extension header list.
4. The method of claim 3 , wherein the first time stamp is contained within a q-bits counter field comprising the ordering information field and the sequence number is contained within a p-bits counter field comprising of the ordering information field.
5. The method of claim 4 , wherein the q-bits counter field is 16-bits and the p-bits counter field is 12-bits.
6. The method of claim 4 , wherein a most significant bit of the q-bits counter field represents a seconds-bit and a remaining number of bits of the q-bits counter field represent a microsecond counter value.
7. The method of claim 1 , wherein the RoE frame is obtained from a packet-switched network.
8. The method of claim 7 , wherein the re-timing interval is based on a maximum packet delay variation (PDV) of the packet-switched network.
9. One or more non-transitory computer readable storage media encoded with instructions that, when executed by a processor, cause the processor to perform operations, comprising:
obtaining a Radio over Ethernet (RoE) frame, wherein the RoE frame comprises a Common Public Radio Interface (CPRI) bit stream and a first time stamp;
determining an induced delay value associated with the RoE frame, wherein determining the induced delay value includes comparing a seconds-bit of the first time stamp to a seconds-bit of a second time stamp generated when the RoE frame is obtained to determine whether a second rollover has occurred and wherein based on determining that a second rollover has not occurred, the induced delay value is determined by calculating a difference between the first time stamp and the second time stamp, and based on determining that a second rollover has occurred, the induced delay value is determined by calculating a difference between a maximum counter value and the first time stamp and adding the second time stamp to the difference;
calculating a re-timing value based on a difference between a re-timing interval and the induced delay value; and
transmitting the CPRI bit stream based on the re-timing value.
10. The media of claim 9 , wherein at least one of:
a sequence number and the first time stamp are contained within an ordering information field of the RoE frame;
the first time stamp is contained within a fixed-sized RoE extension header; and
the first time stamp is contained with a variable-sized RoE extension header list.
11. The media of claim 10 , wherein the first time stamp is contained within a q-bits counter field comprising the ordering information field and the sequence number is contained within a p-bits counter field comprising of the ordering information field.
12. The media of claim 11 , wherein a most significant bit of the q-bits counter field represents a seconds-bit and a remaining number of bits of the q-bits counter field represent a microsecond counter value.
13. The media of claim 9 , wherein the re-timing interval is based on a maximum packet delay variation (PDV) of a packet-switch network from which the RoE frame is obtained.
14. A system comprising:
at least one memory element for storing data; and
at least one processor for executing instructions associated with the data, wherein executing the instructions causes the system to perform operations, comprising:
obtaining a Radio over Ethernet (RoE) frame, wherein the RoE frame comprises a Common Public Radio Interface (CPRI) bit stream and a first time stamp;
determining an induced delay value associated with the RoE frame, wherein determining the induced delay value includes comparing a seconds-bit of the first time stamp to a seconds-bit of a second time stamp generated when the RoE frame is obtained to determine whether a second rollover has occurred and wherein based on determining that a second rollover has not occurred, the induced delay value is determined by calculating a difference between the first time stamp and the second time stamp and based on determining that a second rollover has occurred, the induced delay value is determined by calculating a difference between a maximum counter value and the first time stamp and adding the second time stamp to the difference;
calculating a re-timing value based on a difference between a re-timing interval and the induced delay value; and
transmitting the CPRI bit stream based on the re-timing value.
15. The system of claim 14 , wherein the transmitting is performed using a re-timer buffer.
16. The system of claim 14 , wherein at least one of:
a sequence number and the first time stamp are contained within an ordering information field of the RoE frame;
the first time stamp is contained within a fixed-sized RoE extension header; and
the first time stamp is contained with a variable-sized RoE extension header list.
17. The system of claim 16 , wherein the first time stamp is contained within a q-bits counter field comprising the ordering information field and the sequence number is contained within a p-bits counter field comprising of the ordering information field.
18. The system of claim 17 , wherein the q-bits counter field is 16-bits and the p-bits counter field is 12-bits.
19. The system of claim 17 , wherein a most significant bit of the q-bits counter field represents a seconds-bit and a remaining number of bits of the q-bits counter field represent a microsecond counter value.
20. The system of claim 14 , wherein the re-timing interval is based on a maximum packet delay variation (PDV) of a packet-switched network from which the RoE frame is obtained.