Localization for low cost sensor network

A wireless device including components configure to perform wireless communication, wherein the wireless device is configured to perform localization steps by the following steps:

• receiving a first beacon from a first anchor node, the first beacon including data packets generated as part of the first beacon, at least some of the data packets indicating the source of the data packets and the direction of the first beacon at the time they are generated;
• identifying a first data packet indicative of the direction of the first beacon at the time the first beacon is directed at the wireless device;
• receiving a second beacon from a second anchor node, the second beacon including data packets generated as part of the second beacon, at least some of the data packets indicating the source of the data packets and the direction of the second beacon at the time they are generated;
• and
• identifying a second data packet indicative of the direction of the second beacon at the time the second beacon is directed at the wireless device;
• wherein the step of identifying the first data packet includes:
• receiving the multiple data packets at different times, the multiple data packets indicating different directions of the first beacon;
• comparing received signal strengths for the first beacon at times corresponding to receipt of the multiple data packets;
• and
• selecting one of the multiple data packets that corresponds to higher received signal strength than others of the multiple data packets to be the first data packet.

A system configure to communicate wirelessly, the system comprising a number of anchor nodes having known locations and at least one distributed node, the system configured to determine the location of a first distributed node by the following steps:

• at least first and second anchor nodes generate first and second beacons, the first and second beacons being formed as directional beacons by the use of directional antennae, the first and second beacons being generated such that each is directed in a number of angles relative to the first and second anchor nodes, and the first and second beacons including data packets indicating the direction of the first and second beacons at the time of generation of the respective data packets;
• the first distributed node captures a first data packet from the first beacon indicative of the location of the first distributed node with reference to the first anchor node when the first beacon is directed toward the first distributed node;
• and
• the first distributed node captures a second data packet from the second beacon indicative of the location of the first distributed node with reference to the second anchor node when the second beacon is directed toward the second distributed node;
• wherein the first distributed node captures the first data packet by receiving at least two data packets at different times that indicate distinct angles of the first beacon from the first anchor node, observing which of the at least two data packets has a greatest signal strength, and identifying the data packet having the greatest signal strength as the first data packet.

A system configure to communicate wirelessly, the system comprising a number of anchor nodes having known locations and at least one distributed node, the system configured to determine the location of a first distributed node by the following steps:

• at least first and second anchor nodes generate first and second beacons, the first and second beacons being formed as directional beacons by the use of directional antennae, the first and second beacons being generated such that each is directed in a number of angles relative to the first and second anchor nodes, and the first and second beacons including data packets indicating the direction of the first and second beacons at the time of generation of the respective data packets;
• the first distributed node captures a first data packet from the first beacon indicative of the location of the first distributed node with reference to the first anchor node when the first beacon is directed toward the first distributed node;
• and
• the first distributed node captures a second data packet from the second beacon indicative of the location of the first distributed node with reference to the second anchor node when the second beacon is directed toward the second distributed node;
• wherein at least one distributed node is configured to generate a pulsed output in a data message, the pulsed output useful for localization by a time of arrival approach, and at least one anchor node is configured to receive a pulsed output from a distributed node and identify a time of arrival of the pulsed output.

A system for localization in a wireless sensor network having a plurality of wireless nodes configure to transceive wireless signals, the network comprising:

• a plurality of anchor nodes configure to be configured with reference positional information, the anchor nodes having at least one directional antenna to broadcast positional information through at least one unidirectional wireless signal path;
• a plurality of distributed nodes equipped with wireless transceivers for communication, the distributed nodes including a processor configured to capture directional and location information from at least two anchor nodes for determining the location of the distributed nodes, wherein at least one anchor node is configured to use a directional-output based localization approach in which a directional antenna is used to produce a directional output for use in determining the location of one or more anchor or distributed nodes;
• at least one anchor node is configured to identify a pulsed output from another node for use in a time-difference of arrival localization approach;
• and at least one node within the system is configured to determine, for a given node to be localized, which of the time-difference of arrival or directional-output localization approach is likely to be more accurate.