Method and apparatus for time-of-day synchronization between network nodes
First Claim
Patent Images
1. In a communications network, a communication unit to transmit and receive information within said network comprising:
- a transmitter to transmit outgoing information to at least one other communication unit within said network;
a receiver to receive incoming information from at least one other communication unit within said network;
a clock generation unit to maintain a unit local time, wherein said unit local time initially varies from a common reference GPS time for said network maintained by another communication unit within said network; and
a processor to control said transmission and reception of said outgoing and incoming information and synchronize time between said communication units of said network, wherein said processor includes;
an update module to periodically update said unit local time by an update value and towards said common reference GPS time maintained by said other communication unit, wherein said periodic update is applied one or more times to pull said unit local time toward said common reference GPS time;
anda transition module to transition said updated unit local time of said communication unit to said common reference GPS time of said other communication unit prior to application of all of said periodic updates for completion of said pulling by setting said updated unit local time, varying from said common reference GPS time of said other communication unit by at least one of said periodic updates, directly to said common reference GPS time at a determined transition time and in accordance with conditions indicating that said transition maintains existing network communications.
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Abstract
A node with local GPS time in an ad-hoc wireless network synchronizes with the network time immediately and slowly pulls the network time to GPS time. However, network nodes may immediately transition to the common GPS time after an island or group head node determines that the transition in network time does not disturb the communication links.
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Citations
28 Claims
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1. In a communications network, a communication unit to transmit and receive information within said network comprising:
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a transmitter to transmit outgoing information to at least one other communication unit within said network; a receiver to receive incoming information from at least one other communication unit within said network; a clock generation unit to maintain a unit local time, wherein said unit local time initially varies from a common reference GPS time for said network maintained by another communication unit within said network; and a processor to control said transmission and reception of said outgoing and incoming information and synchronize time between said communication units of said network, wherein said processor includes; an update module to periodically update said unit local time by an update value and towards said common reference GPS time maintained by said other communication unit, wherein said periodic update is applied one or more times to pull said unit local time toward said common reference GPS time; and a transition module to transition said updated unit local time of said communication unit to said common reference GPS time of said other communication unit prior to application of all of said periodic updates for completion of said pulling by setting said updated unit local time, varying from said common reference GPS time of said other communication unit by at least one of said periodic updates, directly to said common reference GPS time at a determined transition time and in accordance with conditions indicating that said transition maintains existing network communications. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of synchronizing time for a communication units of a communications network, wherein said communication unit maintains a unit local time and said unit local time initially varies from a common reference GPS time for said network maintained by another communication unit within said network, said method comprising:
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(a) periodically updating said unit local time of said communication units by an update value and towards said common reference GPS time, wherein said periodic update is applied one or more times to pull said unit local time toward said common reference GPS time; (b) selectively determining a time to transition said updated local time of said communication units to said common reference GPS time for said network; and (c) transitioning said updated local time of said communication unit to said common reference GPS time of said other communication unit prior to application of all of said periodic updates for completion of said pulling by setting said updated unit local time of said communication units, varying from said common reference GPS time of said other communication unit by at least one of said periodic updates, directly to said common reference GPS time at said determined transition time and in accordance with conditions indicating that said transition maintains existing network communications. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A communications network comprising:
a plurality of communication units synchronizing time there between, wherein a communication unit comprising a processor configured to maintain a unit local time, initially varying from a common reference GPS time for said network maintained by another communication unit within said network, periodically updates said unit local time by an update value and towards said common reference GPS time, wherein said periodic update is applied one or more times to pull said unit local time toward said common reference GPS time, and wherein at least one communication unit determines a time to transition said updated unit local time of said communication unit to said common reference GPS time for said network and said communication unit transitions said updated unit local time to said common reference GPS time of said other communication unit prior to application of all of said periodic updates for completion of said pulling by setting said updated unit local time, varying from said common reference GPS time of said other communication unit by at least one of said periodic updates, directly to said common reference GPS time at said determined transition time and in accordance with conditions indicating that said transition maintains existing network communications. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28)
Specification