Interference suppression methods for 802.11
View Patent ↗An 802.11 source station transmits a message, such as a CF-End message, to reset a network allocation vector at a time other than that required for indicating the end of the contention free period. That is, the source station uses the CF-End message to spoof stations within range of the message into resetting the stations' network allocation vectors as if the contention free period were active. Thus, the spoofing source station is allowed to release the medium for general use after the medium has been reserved for a specific use, for a greater time than necessary. 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. After the specific use, if the medium is still reserved, the medium may be released for general use.
1. A method for spoofing stations while transmitting data through a medium, the method comprising:
sending a message to reset a network allocation vector at a time other than an end of a contention free period, wherein at least one of the stations is an obeying station that resets a network allocation vector of the obeying station in accordance with the sent message, wherein the sent message is a CF-End message wherein the sent message indicates an end of a time period for suppressing transmissions by the obeying station and transmissions of unknown protocols are given preferential use of the medium when the transmissions by the obeying station are suppressed.
2. A method for spoofing stations while transmitting data through a medium, the method comprising:
sending a message to reset a network allocation vector at a time other than an end of a contention free period, wherein at least one of the stations is an obeying station that resets a network allocation vector of the obeying station in accordance with the sent message, wherein the sent message further comprises a transmitting station address and a receiving station address wherein the sent message indicates an end of a time period for suppressing transmissions by the obeying station and transmissions of unknown protocols are given preferential use of the medium when the transmissions by the obeying station are suppressed.
3. The method of claim 2 , wherein the network allocation vector is reset if the transmitting station address is a unicast address, the receiving station address is a multicast address, and the obeying station is in a group identified by the multicast address.
4. The method of claim 2 , wherein the network allocation vector is reset if the transmitting station address is a unicast address, the receiving station address is the unicast address, and the obeying station is in a basic service set identified by the unicast address.
5. The method of claim 2 , wherein the network allocation vector is reset if the transmitting station address is a first unicast address, the receiving station address is a second unicast address, and a station addressed by the receiving station address is at the second unicast address.
6. The method of claim 2 , wherein the network allocation vector is reset if the transmitting station address is a first multicast address, the receiving station address is a second multicast address, and the obeying station is in a group identified by the second multicast address.
7. The method of claim 2 , wherein the network allocation vector is reset if the transmitting station address is a multicast address, the receiving station address is a unicast address, and the obeying station is in a group identified by the multicast address.
8. The method of claim 2 , wherein the network allocation vector is reset 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.
9. The method of claim 2 , wherein the network allocation vector is reset 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.
10. The method of claim 1 , wherein the sent message indicates an end of a time period for suppressing transmissions by the obeying station and transmissions of hidden stations are given preferential use of the medium when the transmissions by the obeying station are suppressed.
11. The method of claim 1 , wherein the sent message indicates an end of a time period for suppressing transmissions by the obeying station and critical transmissions are given preferential use of the medium when the transmissions by the obeying station are suppressed.
12. The method of claim 1 , wherein the sent message indicates an end of a time period for suppressing transmissions by the obeying station and 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.
13. The method of claim 1 , wherein the sent message indicates an end of a time period for suppressing transmissions by the obeying station and stations of an enhanced version of a standard are given preferential use of the medium when the transmissions by the obeying station are suppressed.
14. A machine-readable medium having stored thereon a plurality of executable instructions, the plurality of executable instructions comprising instructions to:
send a message to reset a network allocation vector at a time other than an end of a contention free period, wherein at least one of a plurality of stations is an obeying station that resets a network allocation vector of the obeying station in accordance with the sent message, wherein the sent message further comprises a transmitting station address and a receiving station address wherein the sent message indicates an end of a time period for suppressing transmissions by the obeying station and transmissions of unknown protocols are given preferential use of the medium when the transmissions by the obeying station are suppressed.
15. The machine-readable medium of claim 14 , wherein the sent message is a CF-End message.
16. The machine-readable medium of claim 14 , wherein the network allocation vector is reset if the transmitting station address is a unicast address, the receiving station address is a multicast address, and the obeying station is in a group identified by the multicast address.
17. The machine-readable medium of claim 14 , wherein the network allocation vector is reset if the transmitting station address is a unicast address, the receiving station address is the unicast address, and the obeying station is in a basic service set identified by the unicast address.
18. The machine-readable medium of claim 14 , wherein the network allocation vector is reset if the transmitting station address is a first unicast address, the receiving station address is a second unicast address, and a station addressed by the receiving station address is at the second unicast address.
19. The machine-readable medium of claim 14 , wherein the network allocation vector is reset if the transmitting station address is a first multicast address, the receiving station address is a second multicast address, and the obeying station is in a group identified by the second multicast address.
20. The machine-readable medium of claim 14 , wherein the network allocation vector is reset if the transmitting station address is a multicast address, the receiving station address is a unicast address, and the obeying station is in a group identified by the multicast address.
21. The machine-readable medium of claim 14 , wherein the network allocation vector is reset 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. The machine-readable medium of claim 14 , wherein the network allocation vector is reset 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.