Stochastic radio interferometric positioning with unsynchronized modulated signals in wireless sensor networks

Sensor localization problem is one of the fundamental issues in Wireless Sensor Networks (WSN). In this paper, we investigate this problem and present an innovative Radio Interferometric Positioning System (RIPS) for WSN - Stochastic Radio Interferometric Positioning System with Unsynchronized Modulated Signals (SRIPS_UMS). To the best of our knowledge, we are the first to utilize unsynchronized modulated signals for radio interferometric positioning and demonstrate its viability in theory. Although previous radio interferometric positioning methods provide centimeter accuracy, they are still not widely adopted due to (1) strict hardware requirements for Received Signal Strength Indicator (RSSI) circuitry (2) time synchronization problem between distributed hardware. SRIPS_UMS overcomes these limitations by using unsynchronized modulated signals. Its viability and advantages are demonstrated through mathematical models and simulations. Extensive simulations based on radio chip CC2420 demonstrate that SRIPS_UMS is an efficient positioning system for outdoor WSN.