Devices and system for fiber access
View Patent ↗Devices and a system for synchronizing time between a centralized controller device and at least one subscriber device on a fiber access network. The control layer of a network device is expanded, and additional messaging control is added via the transmission of data frames. The expansion prevents reliance on a physical layer signal. The time synchronization also allows a time stamp to be incorporated into a message. Thus, bandwidth is not wasted by simply transmitting a time stamp by itself. In an embodiment, the centralized controller device measures the time difference between the time at which a particular ranging request is transmitted and the time at which the particular ranging request is received. The time difference represents the time adjustment value for the particular subscriber device and allows the device to synchronize its time with that of the centralized controller device.
1. A fiber access system optical line terminator, comprising:
(a) a control layer configured and arranged to:
(i) transmit a transmit/wait timing signal from the control layer to a physical layer, wherein the signal represents an active or passive state of a laser;
(ii) transmit a timing and synchronization message to a subscriber device through transmission of data frames;
(iii) allocate a ranging interval specified by the optical line terminator;
(iv) transmit a ranging interval message to the subscriber device through the transmission of data frames; and
(v) receive a ranging request from the subscriber device through the transmission of data frames,
(b) wherein the subscriber device is in optical communication with the optical line terminator.
2. The fiber access system optical line terminator of claim 1 , wherein the control layer is further configured and arranged to:
(a) determine a time adjustment period corresponding to a difference in time between a clock at the optical line terminator and a clock at the subscriber device;
(b) allocate a token specifying an assigned time interval to the subscriber device based on the time adjustment period; and
(c) transmit the token to the subscriber device through the transmission of data frames.
3. The fiber access system optical line terminator of claim 2 , wherein the time adjustment period is derived from a time difference between a message timestamp and a message arrival time at the optical line terminator.
4. The fiber access system optical line terminator of claim 2 , wherein the token specifies a sequence number of an encryption key to be used by the subscriber device, a time offset value, a type of region, a priority of the token, and a size value of the region.
5. The fiber access system optical line terminator of claim 2 , wherein every message from the optical line terminator to the subscriber device contains synchronization information.
6. The fiber access system optical line terminator of claim 2 , wherein the optical line terminator specifies a grant assignment adjusted by a corresponding subscriber device adjustment period to represent the grant assignment in subscriber device local time.
7. The fiber access system optical line terminator of claim 6 , wherein the optical line terminator specifies the grant assignment according to the time at the optical line terminator and the subscriber device adjusts its local time based on the received adjustment period.
8. A fiber access system optical network unit, comprising:
(a) a control layer configured and arranged to:
(i) transmit a transmit/wait timing signal from the control layer to a physical layer, wherein the signal represents an active or passive state of a laser;
(ii) receive a timing and synchronization message from a centralized controller device through transmission of data frames;
(iii) receive a ranging interval message from the centralized controller device through the transmission of data frames; and
(iv) transmit a ranging request to the centralized controller device through the transmission of data frames,
(b) wherein the optical network unit is in optical communication with the centralized controller device.
9. The fiber access system optical network unit of claim 8 , wherein the control layer is further configured and arranged to:
(a) request a token from the centralized controller device through the transmission of data frames;
(b) monitor tokens broadcast from the centralized controller device through the transmission of data frames; and
(c) receive the token from the centralized controller device through the transmission of data frames,
(d) wherein the token specifies an assigned time interval to the subscriber device based on a time adjustment period corresponding to a difference in time between a clock at the optical network unit and a clock at the centralized controller device.
10. The fiber access system optical network unit of claim 9 , wherein the optical network unit transmits in the active state only.
11. The fiber access system optical network unit of claim 9 , wherein the time adjustment period is derived from a time difference between a message timestamp and a message arrival time at the optical line terminator.
12. The fiber access system optical network unit of claim 9 , wherein the token specifies a sequence number of an encryption key to be used by the optical network unit, a time offset value, a type of region, a priority of the token, and a size value of the region.
13. The fiber access system optical network unit of claim 9 , wherein every message from the centralized controller device to the optical network unit contains synchronization information.
14. The fiber access system optical network unit of claim 9 , wherein the centralized controller specifies a grant assignment adjusted by a corresponding optical network unit adjustment period to represent the grant assignment in optical network unit local time.
15. The fiber access system optical network unit of claim 14 , wherein the centralized controller device specifies the grant assignment according to the time at the centralized controller device and the optical network unit adjusts its local time based on the received adjustment period.
16. A fiber access system, comprising:
(a) a centralized controller device including a first control layer;
(b) a subscriber device including a second control layer capable of optical communication with the centralized controller device,
(c) wherein each of the first and second control layers is configured to:
(i) transmit a transmit/wait timing signal to a physical layer, wherein the signal represents an active or passive state of a laser;
(ii) transmit a timing and synchronization message from the centralized controller device to the subscriber device through transmission of data frames;
(iii) transmit a ranging interval message from the centralized controller device to the subscriber device through transmission of data frames; and
(iv) transmit a ranging request from the subscriber device to the centralized controller device through transmission of data frames.
17. The fiber access system of claim 16 , wherein the first control layer is further configured to:
(a) allocate a ranging interval specified by the centralized controller device;
(b) determine a time adjustment period corresponding to a difference between a clock at the centralized controller device and a clock at the subscriber device;
(c) transmit a time adjustment message from the centralized controller device to the subscriber device based on the time adjustment period through transmission of data frames; and
(d) allocate a token from the centralized controller device to the subscriber device specifying a time interval assigned to the subscriber device through transmission of data frames.
18. The fiber access system of claim 17 , wherein the second control layer is further configured to:
(e) request the token from the centralized controller device through transmission of data frames;
(f) monitor tokens broadcast from the centralized controller device through transmission of data frames;
(g) receive the token from the centralized controller device through transmission of data frames; and
(h) receive the time adjustment message from the centralized controller device based on the time adjustment period corresponding to the difference in time between the clock at the subscriber device and the clock at the centralized controller device through transmission of data frames.
19. The fiber access system of claim 18 , wherein the time adjustment period is derived from a time difference between a message timestamp and a message arrival time at the centralized controller device.
20. The fiber access system of claim 18 , wherein the token specifies a sequence number of an encryption key to be used by the subscriber device, a time offset value, a type of region, a priority of the token, and a size value of the region.
21. The fiber access system of claim 18 , wherein every message from the centralized controller device to the subscriber device contains synchronization information.
22. The fiber access system of claim 18 , wherein the centralized controller device specifies a grant assignment adjusted by a corresponding subscriber device adjustment period to represent the grant assignment in subscriber device local time.
23. The fiber access system of claim 18 , wherein the centralized controller device specifies a grant assignment according to a time at the centralized controller device and the subscriber device adjusts its local time based on the received adjustment period.
24. The fiber access system of claim 18 , wherein the centralized controller device is an optical line terminator.
25. The fiber access system of claim 18 , wherein the subscriber device is an optical network unit.
26. The fiber access system of claim 18 , wherein the subscriber device transmits in the active state only.