Patent ID: 7477191

Claim:
An apparatus, comprising: a communication interface configured to receive data from a first wireless access point and a second wireless access point; and time difference of arrival logic operatively coupled to the communication interface; wherein the time difference of arrival logic is configured to receive data from the first access point representative of a time the first access point transmitted a first signal and a time the first access point received a second signal from a wireless device based on a first clock associated with the first access point; wherein the time difference of arrival logic is further configured to receive data from the second access point representative of a time the second access point received the first signal and the time the second access point received the second signal based on a second clock associated with the second access point; wherein the time difference of arrival logic is configured to calculate a first time difference, the first time difference being the difference between the time the first access point received the second signal and the time the first access point transmitted the first signal; wherein the time difference of arrival logic is configured to calculate a second time difference, the second time difference being the difference between the time second access point received the second signal and the time the second access point received the first signal; wherein the time difference of arrival logic is configured to calculate a relative frequency difference between the first clock and the second clock; wherein the time difference of arrival adjusts the second time difference by multiplying the second time difference by the relative frequency difference; and wherein the time difference of arrival logic determines a time difference of arrival for the second signal based on a difference between the first time difference and the adjusted second time difference.