Designing Radio Interferometric Positioning Systems with Undersampling Techniques

The associated location information is crucial for the data collected by wireless sensor newtworks (WSNs), and nodes have to locate themselves when they are deployed randomly. The radio interferometric positioning system (RIPS) provides high accuracy at low-complexity, which is suitable for cost-limited nodes in WSNs. In the RIPS, two transmitters transmit sinusoids at slightly different frequencies, and the received signal is squared to achieve a low-frequency differential signal at the receivers. The phase difference of the low-frequency differential signals at two receivers is estimated to achieve a range metric called the Qrange, which is a linear combination of distances among four nodes. The squaring operation, however, increases the noise power that degrades the range-estimation performance, and also the Qrange estimator with the traditional RIPS receivers consists of the approximation error. To overcome these drawbacks, we propose the RIPS receiver employing the under sampling techniques (RIPSu) that directly samples the received signal. By avoiding the squaring operation, the RIPS-u can achieve high accuracy and obtain the Q-range estimate without approximation. We provide the MATLAB simulation results to confirm the effectiveness of our proposed RIPS-u.