Patent ID: 7826343

Claim:
A method of transmitting position location signals in a wireless communication system, the method comprising: generating, by a first position location beacon, a first Orthogonal Frequency Division Multiplex (OFDM) symbol based, at least in part, on a first subset of orthogonal frequencies selected from a plurality Q of orthogonal frequencies, wherein the Q orthogonal frequencies are separated from one another by a multiple of a fixed frequency spacing w, wherein the first subset of orthogonal frequencies are associated with the first position location beacon that is in a first geographical location, and wherein the first position location beacon further comprises generating a nonbinary signal and modulating frequencies in the first subset of orthogonal frequencies based in part on the nonbinary signal, wherein the nonbinary signal comprises a constant signal over a period at least 1/w; generating, by a second position location beacon, a second Orthogonal Frequency Division Multiplex (OFDM) symbol based, at least in part, on a second subset of orthogonal frequencies selected from the plurality Q of orthogonal frequencies, wherein the first OFDM symbol is substantially orthogonal to the second OFDM symbol and wherein the second position location beacon is in a second geographical location that is distinct from the first geographical location, and wherein each of the first and second subsets of orthogonal frequencies comprise different randomly spaced orthogonal frequencies or pseudorandomly spaced orthogonal frequencies; and transmitting wirelessly from the first position location beacon, a first position location signal comprising the first OFDM symbol to a receiving mobile device; and transmitting wirelessly from the second position location beacon, a second position location signal comprising the second OFDM symbol to the receiving mobile device, wherein the first and second position location signals are transmitted and configured to allow the receiving mobile device to determine a time difference of arrival.