Virtual group maintenance and security
View Patent ↗A method of providing security and maintenance of a group of devices using a group of tags. Each of the tags is attached to a device and includes a radio frequency transceiver for intercommunicating using ultra-wide band signals. Using the intercommunication, distance between two of the tags is determined and an alarm is triggered when the distance is greater than a previously defined threshold distance. The distance is preferably determined by measuring a round trip delay time between the transmission of a transmitted signal to the other tag and reception of a response signal in response to the transmitted signal from the other tag. The distance is preferably determined by measuring a time delay between transmitting a unicast ultra-wide band message and receiving a unicast response message. The intercommunication preferably uses ultra-wide band signals which relay information regarding completeness of the group between the tags of the group. A configuration mechanism is typically used for configuring the group. Upon completing the configuration, the configuration mechanism, e.g. reader or monitor, may be removed and the tags maintain the group and provide security by the intercommunication between the tags. The tags are preferably synchronized to transmit and receive solely during a previously determined periodic sequence of time intervals.
1. A method comprising:
intercommunicating with tags in a group of tags via a radio frequency transceiver;
implementing, by a given tag within the group of tags, an interrogator role that causes the given tag to interrogate the group of tags, wherein interrogating the group of tags includes:
determining a distance from at least a first tag to at least a second tag via said intercommunicating, wherein said distance is determined by measuring a round trip delay time between transmitting a transmitted signal from the first tag to the second tag and receiving a response signal in response to said transmitted signal from the second tag at the first tag, and
triggering an alarm when said distance is greater than a previously defined threshold distance; and
passing, by the given tag, the interrogator role to another tag within the group of tags.
2. The method, according to claim 1 , wherein said intercommunicating between the tags is based on ultra-wide band signals.
3. The method, according to claim 1 , wherein said determining is performed by measuring a time delay between transmitting a unicast ultra-wide band message and receiving a unicast ultra-wide band response message.
4. The method, according to claim 1 , wherein said intercommunicating relays information regarding completeness of the group between the tags of the group.
5. The method, according to claim 1 , further comprising:
providing a configuration mechanism for configuring the group;
said configuring the group of the tags by performing at least one task selected from the group of tasks consisting of (i) adding a tag to the group, (ii) removing at least one of the tags from the group, (iii) programming said at least one of the tags to intercommunicate with said at least one other tag and (iv) storing in said at least one of the tags a parameter proportional to said previously defined threshold distance; and
upon completing said configuring, removing said configuration mechanism, whereby said tags maintain security by said intercommunicating.
6. The method, according to claim 1 , further comprising:
synchronizing the tags wherein each of the tags transmits and receives during coinciding, periodic time intervals.
7. The method, according to claim 6 , said synchronizing is performed by transmitting beacon signals from at least one of the tags to at least one other of the tags.
8. The method, according to claim 6 , further comprising:
switching at least one of said tags into a sleep mode outside of said previously determined time interval and switching to an active mode during said previously determined time interval, thereby conserving battery power.
9. The method, according to claim 1 , wherein said intercommunicating includes selecting either multicast or broadcast transmitted messages, wherein a decision to transmit with a time frame is probabilistic based on an estimate of traffic within the group.
10. The method, according to claim 1 , wherein said intercommunicating includes selecting either multicast or broadcast transmitted messages, wherein a decision to transmit within a time frame is deterministic according to a previously defined ordering algorithm.
11. The method, according to claim 1 , wherein said intercommunicating includes using unicast ultra-wide band transmitted messages and receiving unicast response messages to relay information regarding completeness of the group, wherein said intercommunicating is performed during a time interval, wherein said time interval is sufficiently long so that a first tag of the group to interrogate receives an interrogation signal from a last of the group to interrogate, and wherein outside said time interval the tags within the group switch into a sleep mode, thereby conserving battery power.
12. The method, according to claim 1 , wherein said alarm is selected from a group consisting of a sound, a light, an alarm record stored in at least one of the tags, a transmitted alarm message, and a command disabling a device operatively attached to one of the tags.
13. The method, according to claim 1 , wherein said alarm is logged as an alarm record in memory of at least one of the tags, said alarm record is retrieved upon querying by a read in temporary communication with said at least one of the tags.
14. A tag comprising:
processing circuity;
a radio frequency transceiver; and
an alarm mechanism;
wherein the processing circuitry is configured to:
control the radio frequency transceiver to intercommunicate with a group of tags;
implement an interrogation role that causes the radio frequency transceiver to interrogate the group of tags, wherein being configured to interrogate the group of tags includes being configured to:
determine a distance to at least a second tag in the group of tags using said intercommunicating, wherein said distance is determined by measuring a round trip delay time between transmitting a transmitted signal to the second tag and receiving a response signal in response to said transmitted signal from the second tag, and
control the alarm mechanism to selectably trigger an alarm or modify an operation of a device operatively attached to the tag, in response to said distance being greater than a previously defined threshold distance; and
pass the interrogator role to another tag within the group of tags.
15. The tag according to claim 14 , wherein the tag is included with a system, the system further comprising a configuration mechanism operative to perform a task selected from the group of tasks consisting of:
(i) adding a tag to the group, (ii) removing at least one of the tags from the group, (iii) programming said at least one of the tags to intercommunicate with said at least one other tag, and (iv) storing in said at least one of the tags a parameter proportional to said previously defined threshold distance.
16. The tag according to claim 14 , wherein being configured to control the radio frequency transceiver to intercommunicate includes using unicast ultra-wide band transmitted messages and receiving unicast response messages to relay formation regarding completeness of the group, wherein said intercommunicating is performed during a time interval, wherein said time interval is sufficiently long so that a first tag of the group to interrogate receives an interrogation signal from a last of the group to interrogate, and wherein outside said time interval the tags within the group switch into a sleep mode, thereby conserving battery power.