Figure 5
From: Bit Level Synchronized MAC Protocol for Multireader RFID Networks
Working example of sequential operation of three readers. The lower part of figure shows the layout of readers and tags within the read range of each. The upper part shows in detail the progression of reading tags as the readers operate one by one in the order R1, R2, and then R3. In a query round, each reader sends a query of bits and awaits responses over a frame of time slots. Each reader chooses its query independently based on its estimate of tags in its reading range. All tags are read after a total of 5 rounds of querying requiring 11-tag response time slots (4,2,2,2,1 in those rounds) in all.