For example, as tags have much similar IDs, delay
is increased.
8.3 Problems in Tree-Based Protocols
The reader performs tag identi?¬?cation frame repeatedly for object tracking and monitoring.*
Let ax denote tag x. For reader r, let Ar,i be the set of tags which dwell inside reader r??™s range
in the ith frame of reader r. To consider the tag??™s mobility, we classify tags into staying tags,
arriving tags, and leaving tags. For the given ith frame of reader r, the staying tag is the tag
which was recognized in the last frame by reader r and stays within the reader r??™s range in
the current frame, that is, a staying tag is one of {ax:ax 2 Ar,i1 \ Ar,i}. The arriving tag is the
tag which was not recognized in the last frame by reader r and has arrived in the reader r??™s
range before the starting of the current frame, that is, an arriving tag is one of {ax:ax 2 Ar,i Ar,i1}. The leaving tag is the tag which was recognized in the last frame by reader r and has
left from the reader r??™s range before the starting of the current frame, that is, a leaving tag is
one of {ax:ax 2 Ar,i1Ar,i}. Tag identi?¬?cation should recognize staying tags and arriving
tags quickly.
Staying tags have been recognized in the last identi?¬?cation frame and the reader will
rerecognize staying tags in the current identi?¬?cation frame. Since the reader already knows
information on staying tags, tag collision arbitration can prevent collisions between signals
transmitted by staying tags during the current frame.
Pages:
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291