Time slot allocation apparatus and method for preventing collisions between time slots in TDMA-based RFID network
First Claim
1. A time slot allocation apparatus for preventing collisions between time slots in a Time Division Multiple Access (TDMA)-based Radio Frequency Identification (RFID) network, the apparatus allocating time slots, obtained by dividing a same frequency band into unit time slots, to RFID readers for reading identification codes of RFID tags in the TDMA-based RFID network, comprising:
- a time slot allocation device configured to allocate time slots required for communication with the RFID tags to a plurality of RFID readers provided in the RFID network; and
a collision prevention device configured to perform control such that the time slot allocation device allocates time slots to the plurality of RFID readers while distributing different and non-sequential time slots to adjacent RFID readers, thus preventing collisions from occurring between time slots allocated to the RFID readers,wherein the collision prevention device perform the control by using a first constraint, a second constraint and a third constraint,wherein the first constraint indicates that at least two RFID readers, which are sets of variables having time slots, don'"'"'t use the same time slot as long as the at least two RFID readers are not spaced sufficiently far apart among the at least two RFID readers,wherein the second constraint indicates that non-sequential time slots are selected among time slots allocated to adjacent RFID readers,wherein the third constraint indicates that time slots are selected non-sequentially but as adjacently as possible among time slots allocated to adjacent RFID readers, andwherein the second constraint is given in the following;
|tsi−
tsj|≧
d(d≅
2)where tsi represents an arbitrary time slot allocated to an arbitrary RFID reader of the at least two RFID readers, tsj represents a different time slot from the time slot tsi that is allocated to another of the at least two RFID readers adjacent to the arbitrary RFID reader, and is non-sequential to the time slot tsi, and d represents the number of time slots interposed between allocated time slots tsi and tsj.
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Abstract
The present invention relates to a time slot allocation apparatus and method for preventing collisions between time slots in a TDMA-based RFID network. The time slot allocation apparatus allocates time slots, obtained by dividing a same frequency band into unit time slots, to RFID readers for reading identification codes of RFID tags (10) in the TDMA-based RFID network. A time slot allocation device (33a) allocates time slots required for communication with the RFID tags to a plurality of RFID readers (20) provided in the RFID network. A collision prevention device (33b) performs control such that the time slot allocation device allocates time slots to the plurality of RFID readers while distributing different and non-successive time slots to adjacent RFID readers, thus preventing collisions from occurring between time slots allocated to the RFID readers.
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Citations
15 Claims
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1. A time slot allocation apparatus for preventing collisions between time slots in a Time Division Multiple Access (TDMA)-based Radio Frequency Identification (RFID) network, the apparatus allocating time slots, obtained by dividing a same frequency band into unit time slots, to RFID readers for reading identification codes of RFID tags in the TDMA-based RFID network, comprising:
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a time slot allocation device configured to allocate time slots required for communication with the RFID tags to a plurality of RFID readers provided in the RFID network; and a collision prevention device configured to perform control such that the time slot allocation device allocates time slots to the plurality of RFID readers while distributing different and non-sequential time slots to adjacent RFID readers, thus preventing collisions from occurring between time slots allocated to the RFID readers, wherein the collision prevention device perform the control by using a first constraint, a second constraint and a third constraint, wherein the first constraint indicates that at least two RFID readers, which are sets of variables having time slots, don'"'"'t use the same time slot as long as the at least two RFID readers are not spaced sufficiently far apart among the at least two RFID readers, wherein the second constraint indicates that non-sequential time slots are selected among time slots allocated to adjacent RFID readers, wherein the third constraint indicates that time slots are selected non-sequentially but as adjacently as possible among time slots allocated to adjacent RFID readers, and wherein the second constraint is given in the following;
|tsi−
tsj|≧
d(d≅
2)where tsi represents an arbitrary time slot allocated to an arbitrary RFID reader of the at least two RFID readers, tsj represents a different time slot from the time slot tsi that is allocated to another of the at least two RFID readers adjacent to the arbitrary RFID reader, and is non-sequential to the time slot tsi, and d represents the number of time slots interposed between allocated time slots tsi and tsj. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A time slot allocation method for preventing collisions between time slots in a Time Division Multiple Access (TDMA)-based Radio Frequency Identification (RFID) network, the method allocating time slots, obtained by dividing a same frequency band into unit time slots, to RFID readers for reading identification codes of RFID tags in the TDMA-based RFID network, comprising:
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(a) allocating, using a time slot allocation device that allocates the time slots for communication with the RFID tags to a plurality of RFID readers provided in the RFID network, an arbitrary time slot to an arbitrary RFID reader; and (b) allocating a time slot to an RFID reader adjacent to the arbitrary RFID reader using a collision prevention device to allocate the time slot that is different from the arbitrary time slot and is non-sequential to the arbitrary time slot to the adjacent RFID reader in order to eliminate temporal interference between respective RFID readers provided in the RFID network, wherein allocating time slots to the arbitrary RFID reader and the adjacent RFID reader comprises allocating so that a number of time slots is interposed between the time slots allocated to the arbitrary RFID reader and the adjacent RFID reader in order to read a moving RFID tag, wherein allocating time slots to the arbitrary RFID reader and the adjacent RFID reader further comprises using a first constraint, a second constraint and a third constraint, wherein the first constraint indicates that at least two RFID readers do not use the same time slot as long as the at least two RFID readers are not spaced sufficiently far apart among the at least two RFID readers, wherein the second constraint indicates that non-sequential time slots are selected among time slots allocated to adjacent RFID readers, wherein the third constraint indicates that time slots are selected non-sequential but as adjacently as possible among time slots allocated to adjacent RFID readers, and wherein the second constraint is given in the following;
|tsi−
tsj|≧
d(d≅
2)where tsi represents the arbitrary time slot allocated to the arbitrary RFID reader, tsj represents the time slot allocated to the adjacent RFID reader, and d represents the number of time slots interposed between allocated time slots tsi and tsj. - View Dependent Claims (12, 13, 14, 15)
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Specification