A method for compensating for non-line-of-sight "NLOS" bias in time difference of arrival "TDOA" estimate between a first anchor and a second anchor in a network having an obstacle in the line-of-sight therebetween, the method comprising: transmitting , by the first anchor, a first packet "REQ packet" from the first anchor; receiving the first packet by the second anchor via a non-line-of-sight path between the first anchor and the second anchor; transmitting a second packet "RSP packet" by the second anchor, responsive to receiving the first packet; receiving the second packet by the first anchor via the non-line-of-sight path between the first anchor and the second anchor; receiving the first packet and the second packet by a mobile device ; estimating , by the first anchor, a round trip fly-time of the first packet and the second packet between the first anchor and the second anchor; estimating , by the first anchor, the non-line-of-sight bias in time of flight of one of the first packet or the second packet between the first anchor and the second anchor, based on the estimated round trip fly-time; transmitting , by the first anchor, the estimated non-line-of-sight bias to the mobile device; estimating , by the mobile device, the time difference of arrival at the mobile device between a direct path and an indirect path, wherein the direct path is the path followed by the first packet sent directly by the first anchor to the mobile device, and wherein the indirect path is the path between the mobile device and the first anchor via the second anchor; using , by the mobile device, the estimated non-line-of-sight bias to correct the time difference of arrival estimated at the mobile device to calculate a corrected time difference of arrival; and estimating , by at least one of the mobile device or an external computing device, a position of the mobile device based on the corrected time difference of arrival. transmitting , by the first anchor, a first packet "REQ packet" from the first anchor; receiving the first packet by the second anchor via a non-line-of-sight path between the first anchor and the second anchor; transmitting a second packet "RSP packet" by the second anchor, responsive to receiving the first packet; receiving the second packet by the first anchor via the non-line-of-sight path between the first anchor and the second anchor; receiving the first packet and the second packet by a mobile device ; estimating , by the first anchor, a round trip fly-time of the first packet and the second packet between the first anchor and the second anchor; estimating , by the first anchor, the non-line-of-sight bias in time of flight of one of the first packet or the second packet between the first anchor and the second anchor, based on the estimated round trip fly-time; transmitting , by the first anchor, the estimated non-line-of-sight bias to the mobile device; estimating , by the mobile device, the time difference of arrival at the mobile device between a direct path and an indirect path, wherein the direct path is the path followed by the first packet sent directly by the first anchor to the mobile device, and wherein the indirect path is the path between the mobile device and the first anchor via the second anchor; using , by the mobile device, the estimated non-line-of-sight bias to correct the time difference of arrival estimated at the mobile device to calculate a corrected time difference of arrival; and estimating , by at least one of the mobile device or an external computing device, a position of the mobile device based on the corrected time difference of arrival. <EOS>