Tags

(1) Tags (Transponder):-

- Consists of microchip (Silicon) that stores data and antenna.

 -  An Electronic Product Code (EPC) is one common type of data stored in a tag.

fig 1.2 Smart Labels

  

Tags are three types:-  And take brief idea of tags in   given below Fig 1.3

1) Passive

2) Active

3) Semi- passive

      The tag's information is stored electronically in a non-volatile memory.

      The RFID tag includes a small RF transmitter and receiver. 

       An RFID reader transmits an encoded radio signal to interrogate the tag.

           The tag receives the message and responds  with its  identification information.








Collision Problems in tags :-

How does collision occurs in tags

How to overcome this collision Problem in Tags

"Slotted ALOHA", which introduced discrete timeslots and increased the maximum throughput.A station can send only at the beginning of a timeslot, and thus collisions are reduced. In this case, we only need to worry about the transmission-attempts within 1 frame-time and not 2 consecutive frame-times, since collisions can only occur during each timeslot. Thus, the probability of there being zero 

If more than one station transmits packets in the same slot, there is a collision, and the Reader

cannot receive the Tags information correctly. Successful transmission happens only when there is exactly one tags.transmitted in a slot. If no tags is transmitted in a slot, the slot is called idle.

A,B,C,D are Tags