Array of very light readers for active RFID and location applications
First Claim
1. A method of reducing collision occurrence in a network for communicating between multiple readers and a plurality of radio frequency (RF) tags, the method comprising:
- transmitting by at least one reader of at least one wide band interrogation signal;
receiving a response signal from a tag in response the interrogation signal;
estimating, by the reader, a quantity of wide band response signals received in response to the interrogation signal;
determining, by the reader, a round trip delay time of each of the wide band response signals;
estimating, by the reader, whether a collision occurred between a plurality of the wide band response signals;
when the collision is estimated to have occurred, transmitting, by the reader, at least one additional wide band interrogation signal, the additional wide band interrogation signal initiating a new communications session between the reader and the tag to reduce a collision probability between wide band response signals transmitted by the plurality of RF tags; and
transmitting, by the reader, an acknowledgment packet to the tag such that;
the tag will not answer again to that broadcast session in case a broadcast command has to be re-transmitted due to an estimation that some collisions occurred during a previous session; and
at least one other reader in the network receives the acknowledgement packet such that the other reader will not try again to reach the tag, thereby lowering congestion directed toward the tag from multiple reader transmissions.
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Accused Products
Abstract
The Very Light Readers of the present invention are based on an augmented Tag circuit with a preferred embodiment including at least one VLSI chip integrating a UWB front end, digital transceiver, and possibly an internal controller; a UWB Antenna; a power supply; a controller configured to implement the Media Access Control protocol of the system; a Communication Interface subsystem for connection to the system network and a clock source. Also described is a system capable of reducing collision occurrence in a network for communicating between multiple readers and a plurality of RF Tags. Tags are configured to receive interrogation signals and transmit response signals. Readers are configured to transmit interrogation signals, receive response signals, estimate the quantity of responses received to an interrogation, determine the round trip delay time of each response and estimates whether a collision between responses has occurred. If so, the Reader transmits an additional interrogation signal. The Reader also transmits an acknowledgment packet to responding Tags so responding Tag will not answer again to that broadcast session. Other Readers in the network also receive the acknowledge packet and do not try again to reach the responding Tags, thereby lowering congestion directed toward Tags from multiple Reader transmissions.
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Citations
14 Claims
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1. A method of reducing collision occurrence in a network for communicating between multiple readers and a plurality of radio frequency (RF) tags, the method comprising:
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transmitting by at least one reader of at least one wide band interrogation signal; receiving a response signal from a tag in response the interrogation signal; estimating, by the reader, a quantity of wide band response signals received in response to the interrogation signal; determining, by the reader, a round trip delay time of each of the wide band response signals; estimating, by the reader, whether a collision occurred between a plurality of the wide band response signals; when the collision is estimated to have occurred, transmitting, by the reader, at least one additional wide band interrogation signal, the additional wide band interrogation signal initiating a new communications session between the reader and the tag to reduce a collision probability between wide band response signals transmitted by the plurality of RF tags; and transmitting, by the reader, an acknowledgment packet to the tag such that; the tag will not answer again to that broadcast session in case a broadcast command has to be re-transmitted due to an estimation that some collisions occurred during a previous session; and at least one other reader in the network receives the acknowledgement packet such that the other reader will not try again to reach the tag, thereby lowering congestion directed toward the tag from multiple reader transmissions. - View Dependent Claims (2, 3)
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4. A system capable of reducing collision occurrence in a network for communicating between multiple readers and a plurality of radio frequency (RF) tags, the system comprising:
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a first one of the tags configured to receive at least one wide band interrogation signal and transmit a response signal in response the interrogation signal; a first one of the readers configured to transmit the interrogation signal and receive the response signal, the first one of the readers further configured to; estimate a quantity of wide band response signals received in response to the interrogation signal; determine a round trip delay time of each of the wide band response signals; estimate whether a collision between a plurality of the wide band response signals occurred and if so, transmit at least one additional wide band interrogation signal, the additional wide band interrogation signal initiating a new communications session between the first one of the readers and the first one of the tags to reduce a collision probability between the wide band response signals transmitted by the tags; and transmit an acknowledgment packet to the first one of the tags such that, the first one of the tags will not answer again to that broadcast session if a broadcast command is re-transmitted due to an estimation that some collisions occurred during a previous session; and at least a second reader in the network configured to receive the acknowledgement packet such that the second reader will not try again to reach the first one of the tags, thereby lowering congestion directed toward the at least one tag from multiple reader transmissions. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A reader to reduce collision occurrence in a network for communicating between multiple readers and a radio frequency tags, the reader comprising:
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communication hardware to; transmit a wide band interrogation signal; and receive response signals from one or more of the tags, the response signals being responsive to the wide band interrogation signal; and a processor to; estimate a quantity of the wide band response signals received in response to the interrogation signal; determine a round trip delay time of each of the wide band response signals; estimate whether a collision occurred between the response signals; when the collision is estimated to have occurred, provide at least one additional wide band interrogation signal to be transmitted by the communication hardware, the additional wide band interrogation signal configured to initiate a new communications session between the reader and the one or more of the tags to reduce a collision probability between response signals transmitted by the tags; and provide an acknowledgment packet to the one or more of the tags such that; the one or more of the tags will not answer again to that broadcast session in case a broadcast command has to be re-transmitted due to an estimation that some collisions occurred during a previous session; and at least one other reader in the network receives the acknowledgement packet such that the other reader will not try again to reach the one or more of the tags, thereby lowering congestion directed toward the one or more of the tags from multiple reader transmissions.
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Specification