Geolocation of MIMO signals using the cross ambiguity function and TDOA/FDOA

The geolocation of RF signals has many civilian and military applications. One technique for geolocation involves using the cross ambiguity function (CAF) to calculate the time-difference-of-arrival (TDOA) and frequency-difference-of-arrival (FDOA) of the emitted signal using two receivers. Until recently most RF signals fell under the category of Single-Input-Single-Output (SISO). Now however, Multiple-Input-Multiple-Output (MIMO) technologies such as Wi-Fi´s IEEE 802.11n are becoming more ubiquitous. The inherent use of multiple antennas in MIMO technologies has an effect on the geolocation of these signals. This paper therefore explores the effect of spatially multiplexed MIMO signals on the cross ambiguity function in regards to the calculation of TDOA and FDOA, and the resulting effect on geolocation.