Interference suppression methods for 802.11
View Patent ↗An 802.11 source station transmits a signal with the duration field other than that required for the transmission to prevent transmission by other stations during known sequences. Thus, the source station uses the duration field to spoof the actual time the medium will be occupied, to stations within range of the signal. A station within range of the transmitted signal will check the duration field of the transmitted signal, and update the station's network allocation vector. Thus, the station will not transmit because the station's network allocation vector indicates that the medium is in use, even though the station maybe unable to hear the carrier. Accordingly, spoofed stations may, for example, 1) delay transmission until a more critical transmission has completed, 2) allow unknown or foreign protocol to have preferential use of the medium, 3) prevent interference from hidden stations, and 4) allow sharing of the medium by overlapping basic service sets.
1. A method for spoofing stations while transmitting data through a medium, the method comprising:
setting a duration value to a value that is greater than a time period for a predetermined subsequent message transmission; and
sending a signal containing the duration value, wherein at least one of the stations is an obeying station that updates a network allocation vector in accordance with the duration value.
2. The method of claim 1 , wherein the duration value represents a time period for suppressing transmissions by the obeying station.
3. The method of claim 2 , wherein transmissions of unknown protocols are given preferential use of the medium when the transmissions by the obeying station are suppressed.
4. The method of claim 2 , wherein transmissions of hidden stations are given preferential use of the medium when the transmissions by the obeying station are suppressed.
5. The method of claim 2 , wherein critical transmissions are given preferential use of the medium when the transmissions by the obeying station are suppressed.
6. The method of claim 2 , wherein at least some of the stations are provided in an overlapping basic service set, and stations of the overlapping basic service set are given preferential use of the medium when the transmissions by the obeying station are suppressed.
7. The method of claim 2 , wherein stations of an enhanced version of a standard are given preferential use of the medium when the transmissions by the obeying station are suppressed.
8. The method of claim 1 , wherein the sent signal is a clear-to-send signal.
9. The method of claim 8 , wherein the sent signal further comprises a receiving station address.
10. The method of claim 9 , wherein the network allocation vector is updated if the receiving station address is a group address and the obeying station is in a group identified by the group address.
11. The method of claim 1 , wherein the sent signal is a request-to-send signal.
12. The method of claim 11 , wherein the sent signal further comprises a transmitting station address and a receiving station address.
13. The method of claim 12 , wherein the network allocation vector is updated if the receiving station address is a broadcast address.
14. A method for spoofing stations while transmitting data through a medium, the method comprising:
setting a duration value to a value that is greater than a time period for a predetermined subsequent message transmission; and
sending a clear-to-send signal containing a receiving station address and the duration value, wherein at least one of the stations is an obeying station that updates a network allocation vector in accordance with the duration value wherein the network allocation vector is updated if the receiving station address is a group address and the obeying station is not in a group identified by the group address.
15. A method for spoofing stations while transmitting data through a medium, the method comprising:
setting a duration value to a value that is greater than a time period for a predetermined subsequent message transmission; and
sending a clear-to-send signal containing a receiving station address and the duration value, wherein at least one of the stations is an obeying station that updates a network allocation vector in accordance with the duration value wherein the network allocation vector is updated if the receiving station address is a broadcast address and the obeying station is a legacy station.
16. A method for spoofing stations while transmitting data through a medium, the method comprising:
setting a duration value to a value that is greater than a time period for a predetermined subsequent message transmission; and
sending a request-to-send signal containing the transmitting station address, a receiving station address, and the duration value, wherein at least one of the stations is an obeying station that updates a network allocation vector in accordance with the duration value wherein the network allocation vector is updated if the transmitting station address is a unicast address, the receiving station address is a multicast address, and the obeying station is not in a group identified by the multicast address.
17. A method for spoofing stations while transmitting data through a medium, the method comprising:
setting a duration value to a value that is greater than a time period for a predetermined subsequent message transmission; and
sending a request-to-send signal containing the transmitting station address, a receiving station address, and the duration value, wherein at least one of the stations is an obeying station that updates a network allocation vector in accordance with the duration value wherein the network allocation vector is updated if the transmitting station address is a first unicast address, the receiving station address is a second unicast address, and the obeying station is not in a basic service set identified by the first unicast address.
18. A method for spoofing stations while transmitting data through a medium, the method comprising:
setting a duration value to a value that is greater than a time period for a predetermined subsequent message transmission; and
sending a request-to-send signal containing the transmitting station address, a receiving station address, and the duration value, wherein at least one of the stations is an obeying station that updates a network allocation vector in accordance with the duration value wherein the network allocation vector is updated if the transmitting station address is a multicast address, the receiving station address is one of a unicast address and a multicast address, and the obeying station is not in a group identified by the multicast address contained in the transmitting station address.
19. A method for spoofing stations while transmitting data through a medium, the method comprising:
setting a duration value to a value that is greater than a time period for a predetermined subsequent message transmission; and
sending a request-to-send signal containing the transmitting station address, a receiving station address, and the duration value, wherein at least one of the stations is an obeying station that updates a network allocation vector in accordance with the duration value wherein the network allocation vector is updated if the transmitting station address is a multicast address, the receiving station address is one of a unicast address and a multicast address, and the obeying station is in a group identified by the multicast address contained in the transmitting station address.
20. A method for spoofing stations while transmitting data through a medium, the method comprising:
setting a duration value to a value that is greater than a time period for a predetermined subsequent message transmission; and
sending a request-to-send signal containing the transmitting station address, a receiving station address, and the duration value, wherein at least one of the stations is an obeying station that updates a network allocation vector in accordance with the duration value wherein if the transmitting station address is a multicast address, the receiving station address is one of a unicast address and a multicast address, the obeying station responds to the group identified by the transmitting station address with a clear-to-send signal, ignores the network allocation vector for the clear-to-send signal, and obeys physical clear channel assessment if the obeying station is addressed in the receiving station address.
21. A method for spoofing stations while transmitting data through a medium, the method comprising:
setting a duration value to a value that is greater than a time period for a predetermined subsequent message transmission; and
sending a request-to-send signal containing the transmitting station address, a receiving station address, and the duration value, wherein at least one of the stations is an obeying station that updates a network allocation vector in accordance with the duration value wherein the network allocation vector is updated if the transmitting station address is a broadcast address, the receiving station address is a unicast address, and the obeying station is not in a basic service set identified by the unicast address.
22. A method for spoofing stations while transmitting data through a medium, the method comprising:
setting a duration value to a value that is greater than a time period for a predetermined subsequent message transmission; and
sending a request-to-send signal containing the transmitting station address, a receiving station address, and the duration value, wherein at least one of the stations is an obeying station that updates a network allocation vector in accordance with the duration value wherein the network allocation vector is updated if the transmitting station address is a broadcast address, the receiving station address is a multicast address, and the obeying station is not in a group identified by the multicast address.