RSSI-based location estimation method in Wireless Sensor Networks (WSNs) present some advantages in terms of complexity and energy consumption. However, the propagation of the radiofrequency signals in indoor environments is subject to fading induced by shadowing effect and multipath propagation. Accurate wireless location estimation can be achieved by employing multiple antennas. In this paper, we make a comparison among three system models in order to show the impact of using multiple antennas on position accuracy at either the transmitter, the receiver side or at the both sides. We use the multilateration as well as the trilateration algorithms to calculate the position error. The obtained results illustrate that the localization performance is improved when using multiple antennas. Specifically, using multiple antennas at the both sides present better performance than using multiple antennas at either the transmitter or the receiver.