Method for managing collisions in a contactless data exchanging system

A system where data is interchanged between a plurality of portable objects and a data transceiver terminal suitable for cooperating with the plurality of portable objects simultaneously present in a field of action of the terminal, comprising:

• means for setting in the terminal a collision probability modulation parameter (PMP), the value of which is a function of a mean number of said portable objects likely to be found in a field of action of said terminal;
• means for transmitting a general call message from the terminal to the portable objects, the general call message including said PMP set in the terminal;
• means for determining which portable objects will respond to the general call message based on the PMP;
• means for transmitting a general response message by each portable object determined to respond to the general call message, each of the general response messages including an identifier uniquely identifying the respective portable object transmitting the general response message;
• upon the one terminal receiving the general call message and the absence of a collision between the general response messages of portable objects, means for establishing a specific data communication link between the one terminal and each of the plurality of portable objects transmitting the general call message;
• wherein when the terminal determines at least one of a collision between the general response messages of portable objects and not receiving the general call message from any of the plurality of objects, the means for transmitting is configured to transmit another subsequent general call message.

A method of controlling collisions in a system of interchanging data between a plurality of portable objects and at least one data transceiver terminal suitable for co-operating with the plurality of portable objects simultaneously present in a field of action of the at least one terminal, the method comprising the following steps:

• a) setting in the terminal a collision probability modulation parameter (PMP), the value of which is a function of a mean number of said portable objects likely to be found in a field of action of said terminal;
• b) transmitting a general call message from the at least one terminal to the plurality of portable objects, the general call message including said PMP set in the terminal;
• c) receiving a general response message from each of the plurality of portable objects determined to respond to the general call message, each of the general response messages including an identifier uniquely identifying the respective portable object transmitting the general response message;
• d) upon the at least one terminal determining the general response message and the absence of a collision between the general response messages of portable objects, establishing a specific data communication link between the at least one terminal and each of the plurality of portable objects transmitting the general response message, respectively, and repeating steps b) through d), for a new iteration;
• e) upon the at least one terminal determining at least one of a collision between the general response messages of portable objects and not receiving the general response message from any of the plurality of objects, repeating steps (b) through (e) for a new iteration.

A method of controlling collisions in a system of interchanging data between a plurality of portable objects and at least one data transceiver terminal suitable for co-operating with the plurality of portable objects simultaneously present in a field of action of the at least one terminal, the method comprising the following steps:

• a) setting in the terminal a collision probability modulation parameter (PMP), the value of which is a function of a mean number of said portable objects likely to be found in a field of action of said terminal;
• b) transmitting a general call message from the at least one terminal to the plurality of portable objects, the general call message including said PMP set in the terminal;
• c) determining which ones of the plurality of portable objects will respond to the general call message based on the PMP;
• d) transmitting a general response message by each of the plurality of portable objects determined to respond to the general call message, each of the general response messages including an identifier uniquely identifying the respective portable object retransmitting the general response message;
• e) upon the at least one terminal receiving the general response message and the absence of a collision between the general response messages of portable objects, establishing a specific data communication link between the at least one terminal and each of the plurality of portable objects transmitting the general response message, respectively, and repeating steps b) through e), for a new iteration;
• f) upon the at least one terminal determining at least one of a collision between the general response messages of portable objects and not receiving the general response message from any of the plurality of objects, repeating steps b) through f) for a new iteration.