Received signal strength (RSS) has been attractive for localization in wireless sensor network (WSN) for simplicity and cost. It is one of the simplest methods for ranging. However, in wireless communication channel, especially in indoor communication, the received signal is much fluctuated by multipath fading and shadowing problem. These causes make RSS measurement incur more errors and consequentially much faults in ranging. It results in low precision for location detection process. To be one of the methods to improve the limitation of RSS method, in this paper we propose using direction calibration to obtain better performance. Sequentially, a multilateration is the next step for carrying out the location of nodes. We also propose to use weighted least squares (WLS) method to solve the overdetermined problem in lateration with weighting matrix composed of reliability factors in conjunction with conventional RSS weighting. Our scheme has much improvement shown by simulation results.