“…The observations can be carried out through measurement of Angle of Arrival (AoA) [3], [4], [5], Time Difference of Arrival (TDoA) [6], [7], [8], or Received Signal Strength (RSS) [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23]. When the sensors are mobile, Frequency Difference of Arrival (FDoA) can also be used as an additional source of information [24], [25], [26]. AoA, TDoA and FDoA approaches require sophisticated sensors, and, therefore do not fit well within the limitations of wireless sensor networks, specifically for energy and complexity constraints of the nodes.…”