Timing synchronization over cable networks

Abstract

In one embodiment, a method receives a first time from a network device. The first time is derived from a first timing source in a first domain. The method receives a second time in a second domain from a second timing source. A difference time value is calculated between the first time and the second time. The method then sends the difference time value to the network device where the network device uses the difference time value to send a delay value to other computing devices to synchronize timing of the other computing devices in the second domain. The other computing devices are configured to synchronize the respective time using the delay value with mobile network devices to allow timing synchronization between the mobile network devices.

1 - 20 . (canceled) 
     
     
         21 . A method implemented in a network device synchronized to a first time source, the method comprising:
 sending a message to a first downstream device and having a time stamp specifying a send time from the network device, the send time based on the first time source;   receiving a response to the message from the first downstream device, the response including a value of a one-way delay of the message sent from the network device to the first downstream device; and   sending the value of the one-way delay to a second downstream device.   
     
     
         22 . The method of  claim 21 , wherein the message was sent in a packet through a CATV network from at least one of a CMTS and an RPD. 
     
     
         23 . The method of  claim 21  where the message was sent using a packet-based protocol. 
     
     
         24 . The method of  claim 23 , wherein the packet based protocol is DOCSIS. 
     
     
         25 . The method of  claim 21  where the value of the one-way delay is based on a second time source independent of the first time source. 
     
     
         26 . The method of  claim 21  where the first time source is the Global Network Satellite System (GNSS).