Method and device for time synchronization in a TDMA multi-hop wireless network
First Claim
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1. Method for synchronizing clocks of a set of nodes in a TDMA (“
- Time Division Multiple Access”
) communication network comprising a plurality of nodes, among which some called time reference (TR) nodes are synchronized to a common time reference through a predetermined out-of-band synchronization mechanism, other nodes being called non-TR nodes, each node comprising an internal clock, wherein that it comprises the steps of;
transmitting, at the level of at least one of said TR nodes, a broadcast beacon packet during a given time slot of sub-frames, each sub-frame comprising a plurality of time slots;
propagating among the remaining nodes said beacon packet using the slotted structure of the TDMA protocol, each node being pre-assigned a conflict-free time slot in a sub-frame to broadcast said beacon packet received from another node in a previous slot of said sub-frame; and
updating in at least two of said non-TR nodes the internal clock based on an updated offset estimate, upon reception of said beacon packet.
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Abstract
The invention concerns a method for synchronizing clocks of a set of nodes in a TDMA (“Time Division Multiple Access”) communication network comprising a plurality of nodes, among which some called time reference (TR) nodes are synchronized to a common time reference through a predetermined out-of-band synchronization mechanism, other nodes being called non-TR nodes, each node comprising an internal clock, characterized in that it comprises the steps of:
- transmitting, at the level of at least one of said TR nodes, a broadcast beacon packet during a given time slot of sub-frames, each sub-frame comprising a plurality of time slots;
- propagating among the remaining nodes said beacon packet using the slotted structure of the TDMA protocol, each node being pre-assigned a conflict-free time slot in a sub-frame to broadcast said beacon packet received from another node in a previous slot of said sub-frame; and
- updating in at least two of said non-TR nodes the internal clock based on an updated offset estimate, upon reception of said beacon packet.
The invention also concerns a communication device in a TDMA communication network.
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Citations
17 Claims
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1. Method for synchronizing clocks of a set of nodes in a TDMA (“
- Time Division Multiple Access”
) communication network comprising a plurality of nodes, among which some called time reference (TR) nodes are synchronized to a common time reference through a predetermined out-of-band synchronization mechanism, other nodes being called non-TR nodes, each node comprising an internal clock, wherein that it comprises the steps of;transmitting, at the level of at least one of said TR nodes, a broadcast beacon packet during a given time slot of sub-frames, each sub-frame comprising a plurality of time slots; propagating among the remaining nodes said beacon packet using the slotted structure of the TDMA protocol, each node being pre-assigned a conflict-free time slot in a sub-frame to broadcast said beacon packet received from another node in a previous slot of said sub-frame; and updating in at least two of said non-TR nodes the internal clock based on an updated offset estimate, upon reception of said beacon packet. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
- Time Division Multiple Access”
Specification