Patent ID: 11966807
Assignee: NANJING UNIVERSITY OF INFORMATION SCIENCE AND TECHNOLOGY
Field: Computer technology (Electrical engineering)
Classification: CPC G  Y | IPC G

Claim 0:
1. A multi-tag concurrent identification method for a query tree based on feature groups, comprising:
dividing a whole data string space into a plurality of disjoint subsets according to features of data strings returned by tags, wherein each of the subsets contains several different data strings, each of the data strings in the each of the subsets is regarded as a complete tag ID or a partial ID, and the each of the subsets corresponds to a unique query prefix, and a length of the prefix is fixed and does not dynamically increase with an actual location of a collision, and when multiple data strings from a same subset return at a same time, a reader is capable of identifying them at a same time in a slot;
wherein the method comprises following steps:
step 1: the reader reads a frame prefix Fpre, a slot prefix spre and a flag bit flag from a stack, wherein both the frame prefix and the slot prefix are empty strings, and the flag bit is 0 in an initial state; and sends query commands of Query, QueryG, QueryR or QueryRep;
step 2: a tag to be identified within a coverage area of the reader receives the query commands sent by the reader, compares the extracted frame prefix Fpre with an own number ID of the tag by using an own matching circuit, and responds to the query commands of the reader if matching, wherein response data depends on the flag bit flag, the slot prefix is spre and a command type; when the flag bit is 0, the tag matches first K bits of the own ID with the spre; if the matching result is true, the tag returns matched Wi segment data, otherwise waits for a next query command; when the flag bit is 1, the tag matches the own ID with the spre, and maps the collision data of m bits into mapping data of M=2m bits according to collision position indication information in the spre, wherein 1<k<m, and returns the mapping data to the reader; if m=K, the tag generates a 2K-bit data string and returns to the reader;
step 3: the reader receives query responses from the tag; if tag responses are not received within a preset time period T, indicating that there is no tag to be identified within the coverage area of the reader; otherwise, a skip is made to a step 4;
step 4, the reader analyzes corresponding tag data according to the different flag bits; if the flag bit is 0, the reader first updates the Fpre to Fpre∥spre, and then parses a segment Wi returned by the tag; if the reader does not detect a collision in Wi, updating the Fpre to Fpre∥Wi, setting a query command flag to the Query command, and a skip is made to a step 5; otherwise, a skip is made to a step 6; if the flag bit is 1, a skip is made to a step 7;
step 5, the reader judges whether a length of Fpre at this moment is equal to a length L of the ID of the tag, and if equal, a current tag is successfully identified; if not equal, the reader pushes updated Fpre and spre parameters into the stack, and a skip is made to the step 1;
step 6: if only 1 bit of collision data in Wi is detected, the reader immediately terminates this slot and replaces the collision bit in Wi with 0 and 1 respectively, and then obtains Wi0 and Wi1; the reader updates Fpre=Fpre∥spre, spre0=Wi0 and spre1=Wi1, and sets the query command flag to QueryR, and a skip is made to the step 5; if m bits of collision data are detected in Wi, wherein 1<m<K, the reader immediately terminates this slot, records a collision position, sets the flag bit to 1, updates Fpre=Fpre∥spre, spre=Wi, sets the query command flag to the QueryRep command, and a skip is made to the step 5; if K bits of collision data are detected in Wi, the reader immediately terminates this slot, sets the flag bit to 1, sets the query command flag to the QueryG command, and a skip is made to the step 1;
step 7, the reader recovers original segment information Wo according to a mapped data string returned by the received tag and the collision information in the spre, and judges whether a length of Wo∥spre is equal to the length L of the ID of the tag; if equal, the reader is capable of identifying the corresponding tag; otherwise, the reader updates spre=Wo, sets the flag bit to 0, sets the query command flag to the QueryR command, and a skip is made to the step 1; and
step 8: repeating the above steps until all tags are identified.