An RSS Based Ranging Enhancement Method Using Multiple Frequency Bands

In recent years, received signal strength (RSS) based ranging method has become an important positioning technique for intelligent transportation systems due to its low cost. RSS based ranging using multiple frequency bands has attracted interest to reduce the influence of the RSS variation. The Log-distance path loss model is widely applied where the path loss exponent is usually considered as frequency independent. In this paper, a channel measurement based investigation reveals that the path loss exponent slightly depends on frequency, which results in the model mismatch for ranging methods using multiple bands. To overcome this mismatch, a simple RSS based ranging enhancement method is proposed. RSS measurements at different frequency bands are used to estimate the distance by considering frequency dependent path loss exponent. Furthermore, the covariance matrix of shadow fading factor at multiple frequency bands is incorporated. Measurement based evaluation shows the validity and outperformance of the proposed method.