1. Chapter 12 – Optimal Tag Coverage and Tag Report Elimination

2. Figure 12.1 Example of network device equipped with RFID reading capabilities
Example of network with multiple device types equipped
with RFID reading capabilities as well as other wireless communication
capabilities. R1 is a traditional RFID reader, R2, R3 and
R4 are Mica Motes extended with reader circuits and S is
a reader equipped cellphone. Tags are denoted by small rectangles.
Interrogation zones of readers are simplistically denoted by disks
centered at readers. S T4 T3 R4 R6 R8

3. Figure 12.2 (a) Direct reporting reader network
Reader network examples. Readers are denoted by black dots and their RF interrogation zones by irregular shapes. Dotted arrows represent cellular links and plain arrows represent reader-to-reader wireless links. Tags are denoted by small crosses.
B. Carbunar, M. K. Ramanathan, M. Koyuturk, S. Jagannathan, and A. Grama. Efficient tag detection in rfid systems. J. Parallel Distrib. Comput., 69(2): , 2009.

4. Figure 12.2 (b) Ad hoc reader network
Reader network examples. Readers are denoted by black dots and their RF interrogation zones by irregular shapes. Dotted arrows represent cellular links and plain arrows represent reader-to-reader wireless links. Tags are denoted by small crosses.
(b) Ad hoc reader network. The same reader and tag placement butwireless readers may now communicate with each other and with the host
system. The sink node R6 needs to communicate with the host system.
All other readers route the identified tags toward R6.
B. Carbunar, M. K. Ramanathan, M. Koyuturk, S. Jagannathan, and A. Grama. Efficient tag detection in rfid systems. J. Parallel Distrib. Comput., 69(2): , 2009.

5. Figure 12.3 (a) Example WSN coverage
(a) Example WSN coverage. The sensing (coverage) areas of sensors are shown as disks centered at the sensors. The central sensor is defined to be redundant since its sensing disk is completely subsumed by the other sensors.

6. Figure 12.3 (b) Example RFID coverage
The interrogation zones of readers are shown as regions of irregular shapes, around the locations of the readers. Tags are denoted by x marks. The coverage of a reader is defined as a discrete set of elements, the tags in its interrogation zone. The central reader, whose interrogation zone is not completely covered by the interrogation zones of the other readers, is still defined to be redundant. This is because the tags covered by its interrogation zone are also covered by other readers

7. Figure 12.4 (a) GREEDY
RFID system where greedy provides an optimal tag coverage solution, by detecting reader R2 to be redundant.

8. Figure 12.4 (b) RRE
RFID system where RRE provides an optimal tag coverage
solution

9. Figure 12.5 Reader duty cycle
Example reader duty-cycle with a 1:1 ratio of sleep to active intervals. Each active interval consists of a first, shorter sub-interval for reseting all tags to 0, followed by a longer sub-interval dedicated to running RRE. The duty-cycles of two readers shown are off by at most ε,due to clock drifts