Communication network with flexible handoff scheduling for mobile nodes
First Claim
1. In a communication network having a plurality of mobile nodes interconnected by constellation communication links and having a stationary node supporting a switchable communication link with one of said mobile nodes, a method for controlling handoff of said switchable link comprising the steps of:
- a) forming a schedule that identifies a point in time at which to handoff said switchable link from a departing mobile node to an arriving mobile node;
b) prior to said point in time, determining whether said stationary node can communicate with said arriving mobile node;
c) ignoring said schedule when said step b) determines that said stationary node cannot communicate with said arriving mobile node; and
d) sending a message from said stationary node to said departing node over said switchable link when said step (b) determines that said stationary node cannot communicate with said arriving mobile node, said message informing said departing mobile node that said stationary node cannot communicate with said arriving node.
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Accused Products
Abstract
A communication network (10) includes a constellation (12) of mobile satellites (14) in low earth orbits and stationary gateways (24) near the surface of the earth. Data packets are routed through the network (10) using communication paths that change from moment to moment due to satellite movement. The routing paths are scheduled in advance (58) in response to predictable orbital satellite movement. The constellation (12) is configured so that only a minor amount of overlap in radio range exists between adjacent satellites (14). Gateways (24) include multiple, spaced apart antennas (30) that may be used to acquire arriving satellites (14'"'"'). When a gateway (24) has trouble quickly acquiring an arriving satellite (14'"'"'), an exception handoff time may be substituted for the scheduled normal handoff time at the gateway (24), departing satellite (14), and arriving satellite (14'"'"') involved.
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Citations
14 Claims
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1. In a communication network having a plurality of mobile nodes interconnected by constellation communication links and having a stationary node supporting a switchable communication link with one of said mobile nodes, a method for controlling handoff of said switchable link comprising the steps of:
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a) forming a schedule that identifies a point in time at which to handoff said switchable link from a departing mobile node to an arriving mobile node; b) prior to said point in time, determining whether said stationary node can communicate with said arriving mobile node; c) ignoring said schedule when said step b) determines that said stationary node cannot communicate with said arriving mobile node; and d) sending a message from said stationary node to said departing node over said switchable link when said step (b) determines that said stationary node cannot communicate with said arriving mobile node, said message informing said departing mobile node that said stationary node cannot communicate with said arriving node. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. In a communication network having a plurality of mobile nodes interconnected by constellation communication links and having a stationary node supporting a switchable communication link with one of said mobile nodes, a method for controlling handoff of said switchable link comprising the steps of:
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a) forming a schedule that identifies a point in time at which to handoff said switchable link from a departing mobile node to an arriving mobile node; b) prior to said point in time, determining whether said stationary node can communicate with said arriving mobile node; c) ignoring said schedule when said step b) determines that said stationary node cannot communicate with said arriving mobile node; and d) routing communications among said mobile nodes, except for said departing mobile node, said arriving mobile node, and any bridging node between said departing and arriving mobile nodes, after said point in time the same as if said schedule were not ignored when said step b) determines that said stationary node cannot communicate with said arriving mobile node.
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14. In a communication network having a plurality of mobile nodes interconnected by constellation communication links and having a stationary node supporting a switchable communication link with one of said mobile nodes, a method executed by said stationary node for controlling handoff of said switchable link comprising the steps of:
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a) the stationary node forming a schedule that identifies a point in time at which to handoff said switchable link from a departing mobile node to an arriving mobile node; b) prior to said point in time, the stationary node determining whether communication can be established with said arriving mobile node; c) the stationary node ignoring said schedule when said step b) determines that communication cannot be established with said arriving mobile node; and d) the stationary node sending a message to said departing node over said switchable link when said step (b) determines that said stationary node cannot communicate with said arriving mobile node, said message informing said departing mobile node that said stationary node cannot communicate with said arriving node.
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Specification