System and method of secure ranging measurement
Methods and apparatus for performing secure ranging measurements between wireless devices are disclosed herein according to embodiments of the present invention. The described embodiments use key values to indicate which LTF sequence (e.g., LTF measurement exchange) to use for performing wireless ranging measurements. A LTF sequence that is received by a wireless device that does not correspond with the associated key value is determined to be invalid. Invalid LTF sequences may be disregarded as signal noise.
1. A method of performing a ranging measurement using a wireless access point, the method comprising:
a) transmitting a key management frame from a first wireless device, wherein the key management frame comprises a plurality of key values and associated long training field (LTF) Generation SACs;
b) receiving a first null data packet (NDP) announcement frame comprising the LTF Generation SACs from a second wireless device;
c) receiving an UL-NDP frame from the second wireless device, wherein the UL-NDP frame comprises a first LTF sequence determined according to a first key value of the plurality of key values;
d) transmitting a DL-NDP frame transmitted from the first wireless device, wherein the DL-NDP frame comprises a second LTF sequence determined according to a second key value of the plurality of key values; and
e) computing ranging measurements between the first wireless device and the second wireless device using the first and second LTF sequences;
f) determining that the first LTF sequence is invalid based on the key values;
g) the first wireless device transmitting a second NDP announcement frame indicating that new LTF generation information is needed responsive to the determining;
h) receiving a third LTF sequence responsive to the second NDP announcement frame.
2. A method as described in claim 1 , further comprising authenticating that the first LTF sequence and the second LTF sequence are generated from reliable LTF Sequence Generation Information using the associated LTF Generation SACs.
3. A method as described in claim 1 , further comprising determining that the first LTF sequence is invalid based on the key values.
4. A method as described in claim 3 , further comprising disregarding the first LTF sequence as signal noise when the first LTF sequence is determined to be invalid.
5. A method as described in claim 1 , further comprising transmitting an acknowledgement frame responsive to the key management frame.
6. A method as described in claim 1 , wherein the first NDP announcement frame comprises a VHT First NDP announcement frame.
7. A method as described in claim 1 , wherein the first NDP announcement frame comprises an HE First NDP announcement frame.
8. A device for performing a ranging measurement using a wireless access point, the device comprising:
a memory for storing data; and
a processor communicatively coupled to the memory and configured to execute instructions for performing a method of ranging measurement, the method comprising:
a) receiving a key management frame, wherein the key management frame comprises a plurality of key values and associated LTF Generation SACs;
b) transmitting a first NDP announcement frame, wherein the First NDP announcement frame comprises the LTF Generation SACs;
c) transmitting a UL-NDP frame, wherein the UL-NDP frame comprises a first LTF sequence determined according to a first key value of the plurality of key values;
d) receiving a DL-NDP frame from a first wireless device, wherein the DL-NDP frame comprises a second LTF sequence corresponding to a second key value of the plurality of key values;
e) receiving a ranging measurements between the first wireless device and the second wireless device, wherein the ranging measurement is computed using the first and second LTF sequences;
f) determining that the first LTF sequence is invalid based on the key values;
g) the first wireless device transmitting a second NDP announcement frame indicating that new LTF generation information is needed responsive to the determining; and
h) receiving a third LTF sequence responsive to the second NDP announcement frame.
9. A device as described in claim 8 , wherein the method further comprises receiving an acknowledgement frame responsive to the key management frame.
10. A device as described in claim 8 , wherein the first NDP announcement frame comprises a VHT NDP announcement frame.
11. A device as described in claim 8 , wherein the first NDP announcement frame comprises an HE NDP announcement frame.
12. A device for performing a ranging measurement between wireless devices, the device comprising:
a memory for storing data; and
a processor communicatively coupled to the memory and configured to execute instructions for performing a method of ranging measurement, the method comprising:
a) transmitting a key management frame from a first wireless device, wherein the key management frame comprises a plurality of key values and associated long training field (LTF) Generation SACs;
b) receiving a first null data packet (NDP) announcement frame comprising the LTF Generation SACs from a second wireless device;
c) receiving an UL-NDP frame from the second wireless device, wherein the UL-NDP frame comprises a first LTF sequence corresponding to a first key value;
d) transmitting a DL-NDP frame transmitted from the first wireless device,
wherein the DL-NDP frame comprises a second LTF sequence corresponding to a second key value;
e) authenticating that the first LTF sequence and the second LTF sequence are generated from reliable LTF Sequence Generation Information using the associated LTF Generation SACs; and
f) computing ranging measurements between the first wireless device and the second wireless device using the first and second LTF sequences;
g) determining that the first LTF sequence is invalid based on the key values:
h) the first wireless device transmitting a second NDP announcement frame indicating that new LTF generation information is needed responsive to the determining: and
i) receiving a third LTF sequence responsive to the second NDP announcement frame.
13. A device as described in claim 12 , wherein the method further comprises determining that the first LTF sequence is invalid based on the key values.
14. A device as described in claim 13 , wherein the method further comprises disregarding the first LTF sequence as signal noise when the first LTF sequence is determined to be invalid.
15. A device as described in claim 12 , wherein the method further comprises transmitting an acknowledgement frame responsive to the key management frame.
16. A device as described in claim 12 , wherein the first NDP announcement frame comprises a VHT NDP announcement frame.
17. A device as described in claim 12 , wherein the first NDP announcement frame comprises an HE NDP announcement frame.