Method for handling collision in an identification system

An identification system comprising a reader device, a first transponder and a second transponder,

• wherein the reader device is arranged to transmit an initialization command to the first transponder and to the second transponder;
• wherein the first transponder and the second transponder are arranged to enter into a muted state upon receipt of the initialization command;
• wherein, in the muted state, the first transponder and the second transponder are arranged to refrain from responding to commands from the reader device;
• wherein, in a first start time slot randomly determined by the first transponder, the first transponder is arranged to enter into an un-muted state from the muted state and the first transponder is arranged to remain in the un-muted state until the reader device sends a mute command to the first transponder;
• wherein, in a second start time slot randomly determined by the second transponder, the second transponder is arranged to enter into an un-muted state from the muted state and the second transponder is arranged to remain in the un-muted state until the reader device sends a mute command to the second transponder;
• wherein, when the first start time slot and the second time slot occur at the same randomly determined time slot, then:
• when a transponder has a weaker signal modulation than another transponder, then the transponder with the weaker signal modulation re-enters into a muted state until a third start time slot randomly determined by the transponder corresponding to the weaker signal modulation;
• and
• when the signal modulation of the first transponder and the second transponder have substantially the same strength, then the first transponder and the second transponder re-enter into a muted state until a start time slot randomly determined by the corresponding transponder.

A method for handling collision by a transponder in an identification system, the method comprising:

• upon receiving an initialization command from a reader device, a transponder enters into a muted state and, in the muted state, the transponder does not respond to external commands;
• in a start time slot randomly determined by the transponder, the transponder enters into an un-muted state from the muted state and remains in the un-muted state until at least one of:
• a collision occurs with another transponder having a stronger modulated signal, upon which the transponder re-enters into a muted state until a second start time slot randomly determined by the transponder;
• or
• a collision occurs with another transponder having a substantially similar strength modulated signal, upon which the transponder re-enters into a muted state until a second start time slot randomly determined by the transponder.