e 16 channels are shown in the spectrum analyzer with a high precision. By using of a powerful RF transmitter, all out of band frequencies are filtered and the main frequency is amplified. The receiver sensitivity is a critical parameter for correct operation of RF transceivers. In CC2530, the receiver sensitivity is –97 dBm . So, if the received signal strength (RSSI) becomes lower than this level, the receiver will not detect the signal properly. In Figure 11, the RSSI versus distance between the Reader and Tags is depicted in a practical test. For lower transmitter output power, the RSSI value is decreased. This reduction in RSSI is often more for long distances rather than short distances. As shown in Figure 11, the RSSI level is higher than the receiver sensitivity threshold for distances smaller than 80 meter. The PER (Packet Error Rate) is another significant parameter in RFIDs. It is expressed in the form of percentage. As shown in Figure 12, the PER is increased with increasing the distance, significantly. The experiments were performed for the two different TX output powers to ensure the proper operation of this system. As shown in Figure 13, round time for collecting 170 Tags data is near 1 second. In Table 2, important parameters of this system compared with similar works are shown.
In this work, a low-power high-range active RFID is implemented by using the chip CC2530. Without using any additional peripheral module, the identification process is
Figure 7. The reader flowchart.
Table 2. System characteristics of similar RFIDs.
Figure 8. The flowchart of tags operation.
Figure 9. The physical and MAC layers of IEEE 802.15.4 standard frames .
Figure 10. Frequency spectrum of the transmitting signal on spectrum analyzer.
Figure 11. Received signal strength (RSSI) versus distance.
Figure 12. Packet error rate versus distance.
Figure 13. Round time versus tag numbers.
executed with high accuracy and minimum PER. By programming Tags in the sleep mode in most of times, a lot amount of power is restored. This system is tested and its operation is verified at outdoor environment until 80 meter distances, successfully. With a range extender device, such as CC2591, the communication range up to 300 m can be achieved. In our work, the collection time for 170 Tags is near 1 second. By using of a low-power multi-purpose Chip, small dimensions for Tags are achieved. In this architecture, compacting Tags down to near 660 mm2 is possible, which is required in many practical environments. This system will be used for vehicle transportation and especially container tracking at commercial ports.