System for maintaining synchronization between multiple asynchronous communication links
View Patent ↗An apparatus for maintaining synchronization with a plurality of asynchronous communication links includes a first counter that generates a first local network clock, and a second counter that generates a second local network clock. The apparatus also includes an offset controller coupled with the first counter and coupled with the second counter, the offset controller configured to load a current network clock value of a first network clock of a first communication link into the first counter, and to load a current network clock value of a second network clock of a second communication link into the second counter. The apparatus further includes a drift controller coupled with the first counter and with the second counter, the drift controller configured to correct a drift between the first local network clock and the first network clock and to correct a drift between the second local network clock and the second network clock. The first local network clock approximates the first network clock of the first communication link and the second local network clock approximates the second network clock of the second communication link.
1. A system for communicating over a first communication link and a second communication link that are asynchronous, the system comprising:
a transceiver configured to receive and transmit data over the first communication link and the second communication link;
a network link controller configured to generate control signals to control when the transceiver receives and transmits data over the first communication link based upon a first local network clock and over the second communication link based upon a second local network clock;
a first counter that generates the first local network clock, wherein the first counter is configured to be programmed to count at any one of a plurality of different rates and have any one of a plurality of different roll over values; and
a second counter that generates the second local network clock,
wherein the first local network clock approximates a first network clock of the first communication link and the second local network clock approximates a second network clock of the second communication link.
2. The system of claim 1 , further comprising:
an offset controller coupled with the first counter and coupled with the second counter, the offset controller configured to load a current network clock value of the first network clock into the first counter, and to load a current network clock value of the second network clock into the second counter.
3. The system of claim 2 , wherein the first counter includes a parallel load input and the second counter includes a parallel load input, and wherein the offset controller is coupled with the parallel load input of the first counter and with the parallel load input of the second counter.
4. The system of claim 2 , wherein the offset controller is configured to determine the current network clock value of the first network clock and to determine the current network clock value of the second network clock.
5. The system of claim 4 , wherein the offset controller determines the current network clock value of the first network clock based upon a time stamp of a transmission received via the first communication link.
6. The system of claim 1 , further comprising:
a drift controller coupled with the first counter and with the second counter, the drift controller configured to correct a drift between the first local network clock and the first network clock and to correct a drift between the second local network clock and the second network clock.
7. The system of claim 6 , wherein the drift controller is configured to determine an expected receive time of a transmission via the first communication link and to compare the expected receive time with an actual receive time of the transmission.
8. The system of claim 1 , further comprising a clock generator that generates a first clock and a second clock, the first clock coupled with the first counter and driving the first counter at a first rate, and the second clock coupled with the second counter and driving the second counter at a second rate.
9. The system of claim 1 , wherein data is transmitted and received over the first communication link and the second communication link based on a communication protocol that utilizes time division duplexing.
10. A system for communicating over a first communication link and second communication link that are asynchronous, the system comprising:
a transceiver configured to receive and transmit data over the first communication link and second communication link;
a network link controller configured to generate control signals to control when the transceiver receives and transmits data over the first communication link based upon a first local network clock and over the second communication link based upon a second local network clock;
a first counter that generates the first local network clock; and
a second counter that generates the second local network clock; and
an offset controller coupled with the first counter and coupled with the second counter, the offset controller configured to load a current network clock value of a first network clock of the first communication link into the first counter, and to load a current network clock value of a second network clock of the second communication link into the second counter.
11. The system of claim 10 , wherein the first counter includes a parallel load input and the second counter includes a parallel load input, and wherein the offset controller is coupled with the parallel load input of the first counter and with the parallel load input of the second counter.
12. The system of claim 10 , wherein the offset controller is configured to determine the current network clock value of the first network clock and to determine the current network clock value of the second network clock.
13. The system of claim 12 , wherein the offset controller determines the current network clock value of the first network clock based upon a time stamp of a transmission received via the first communication link.
14. The system of claim 10 , further comprising:
a drift controller coupled with the first counter and with the second counter, the drift controller configured to correct a drift between the first local network clock and the first network clock and to correct a drift between the second local network clock and the second network clock.
15. The system of claim 14 , wherein the drift controller is configured to determine an expected receive time of a transmission via the first communication link and to compare the expected receive time with an actual receive time of the transmission.
16. The system of claim 10 , further comprising a clock generator that generates a first clock and a second clock, the first clock coupled with the first counter and driving the first counter at a first rate, and the second clock coupled with the second counter and driving the second counter at a second rate.
17. The system of claim 10 , wherein data is transmitted and received over the first communication link and the second communication link based on a communication protocol that utilizes time division duplexing.