Method and apparatus for the deterministic capture of a communication channel shared among contention based technologies
View Patent ↗Communications with timeliness guarantees, also known as real-time communications are established in a shared medium with different contention based technologies. A real-time station is able to transmit a noise sequence before the intended data packet transmission. The noise sequence being is to occupy the communication medium during a period of time preferably larger than the maximum transmission time of any contention based technology that can have access to the medium, hereinafter designated alien. As such, even if an alien station is transmitting, it will finish its packet during the transmission of the noise sequence. The method prevents the alien stations from accessing the medium as these stations will sense the medium busy after the end of their packet transmissions. This method can be used to support master-multislave real-time communications on shared media in which contention based technologies operate.
1. Capture method of a shared communication medium comprising:
transmitting a noise sequence followed, in a period of time less than a period of time of an idle channel assessment, by a data packet transmission by a real-time station;
transmitting secondary and simultaneous noise in adjacent bands, low and high interference sub-bands, whenever alien communication technologies are operating on a data band, but employ larger bandwidths;
wherein a data transmission is initiated after said noise sequence, by a transceiver, within a time window whose duration is less than a duration of a minimum Clear Channel Assessment (CCA) time of any alien communication technology to be inhibited.
2. The method according to claim 1 , wherein said noise sequence is produced by a programmable noise synthesizer.
3. The method according to claim 1 , wherein transmission power is equal or higher than that of the alien communication technology that is to be inhibited.
4. The method according to claim 1 , comprising a duration more than the duration of a largest packet of any alien communication technology intended to be inhibited, or guaranteeing that said noise sequence always ends at a subsequent instant of any communication that has preceded said noise sequence.
5. The method according to claim 1 , wherein a transmission is applied in a frequency band that includes the data band and which results in an occupied medium assessment by all alien communication technologies that are to be inhibited.
6. A method of transmitting real-time data, comprising capturing the shared communication medium, by a master station, according to claim 1 , by the transmitting of a noise sequence in an interference band, followed by a trigger packet in a data band, and subsequent real-time data packet transmission by slave stations in the data band within an interference protected window.
7. The method according to claim 6 , wherein the temporal limits of the current elementary cycle and the scheduling of the transmissions in the protected window are defined immediately after the noise sequence.
8. The method according to claim 6 , wherein the transmission of real-time data packets takes place by slave stations in the instants defined by the trigger message, that occupy disjoint portions of time in the protected window, being separated by a minimum delay equal or more than a duration of an Inter Frame Space (IFS) of employed data communication technology.
9. The method for maintaining the capture of the communication medium within the protected temporal window between the trigger packet and the first data transmission of a slave station and between data transmissions from stations, according to claim 1 , wherein an injection of a noise sequence occurs in the interference band, which prevents alien stations from detecting the medium as idle and from initiating a transmission corrupting the protected window.
10. Capture method of a shared communication medium comprising:
transmitting a noise sequence followed, in a period of time less than a period of time of an idle channel assessment, by a data packet transmission by a real-time station;
transmitting secondary and simultaneous noise in adjacent bands, low and high interference sub-bands.
11. A method of protecting data communications of a shared communication medium in a contention window, the method comprising:
transmitting
a secondary noise sequence, in adjacent bands, low and high interference sub-bands, preventing alien stations from detecting the medium as idle and from initiating a transmission corrupting the contention window.