Method for managing access to a shared communication medium
AssigneeSagem Defense Securite
InventorAlain Chiodini
Life of this patent
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Abstract
The methods for managing access to a communication medium shared by a plurality of radio communication devices. The method of accessing a radio communication medium shared between a plurality of communication terminals. The method is based on a variant of the CSMA/CD access protocol. The method is based on monitoring of the medium and the emission of a token to request permission to emit. The terminals that receive this token then emit an acknowledgement intended to signal that the medium can be used, or a collision message if they receive a plurality of tokens simultaneously. In the latter case, the emitter retries its attempt to use the medium later on.
Claims6
A method for a communication terminal configured to send data over a broadcast channel of a radio communication medium shared between a plurality of communication terminals to access said broadcast channel and send said data to said plurality of communication terminals, said communication terminals performing the following steps comprising:
- a step of listening to the broadcast channel of the radio communication medium in order to determine whether said broadcast channel is free;
- a step of sending a token over said broadcast channel being performed when said step of listening determines that said broadcast channel is free;
- a step of receiving over said broadcast channel at least one response, if any, to the sent token from a communication terminal sharing said radio communication medium;
- and;
- a step of determining whether said received response is a collision message indicating that the communication terminal that has sent the response has received several tokens from at least two communication terminals;
- if said at least one response is a collision message, a step of waiting before restarting the listening step, otherwise;
- a step of sending the data to be sent over the broadcast channel of the radio communication medium;
- wherein said broadcast channel is divided into segments associated with each type of message, wherein the step of sending a token or the step of receiving a response to said sent token is performed in the segment with said token or said response;
- a step of pairing successive time slots constituting the broadcast channel into two sets of paired successive time slots;
- a step of splitting all the terminals into two subsets, a first subset of terminals referred to as greeted terminals where the first set of the paired successive time slots one is dedicated to sending and a second subset of terminals referred to as greeter terminals where the second pair of paired successive time slots is dedicated to receiving;
- and,
- prior to performing the step of sending data to be sent over the broadcast channel a greeter terminal, and all the greeted terminals switch and change their greeter-greeted status.
A terminal adapted to access to a broadcast of a radio communication medium shared between a plurality of communication terminals in order to send data said broadcast channel of the radio communication medium to said plurality of communication terminals, wherein said terminal comprises:
- circuitry for listening to the broadcast channel of the radio communication medium in order to determine whether said broadcast channel is free;
- circuitry for sending a token over the broadcast channel when the broadcast channel is determined as being free;
- circuitry for receiving over the broadcast channel at least one response, if any, to the sent token from communication terminal sharing said broadcast channel, and
- circuitry for determining whether a received response is a collision message indicating that the communication terminal that has sent the response has received several tokens from a number of communication terminals;
- circuitry for waiting before listening to the broadcast channel when said at least one received response is a collision message;
- circuitry for sending the data to be sent over the broadcast channel of the radio communication medium, when each received response is not a collision message;
- circuitry for pairing successive time slots constituting the broadcast channel into two sets of paired successive time slots;
- and
- circuitry for splitting all the terminals into two subsets, a first subset of terminals referred to as greeted terminals where the first set of the paired successive time slots one is dedicated to sending and a second subset of terminals referred to as greeter terminals where the second pair of paired successive time slots is dedicated to receiving;
- and,
- prior to performing the step of sending data to be sent over the broadcast channel a greeter terminal, and all the greeted terminals switch and change their greeter-greeted status;
- wherein said broadcast channel is divided into segments associated with each type of message, wherein the step of sending a token or the step of receiving a response to said sent token is performed in the segment with said token or said response.
Dependencies are inferred from the claim text.