Wider Adoption of Radio Interferometric Positioning in Wireless Sensor Applications
Gao, Ruiling.
2018
-
Abstract: Self-location awareness of sensors plays a significant role in many Wireless Sensor Network (WSN) applications such as sensor network-based counter-sniper systems, habitat monitoring in the wild, and energy-efficient surveillance system. Positioning using Received Signal Strength (RSS) and trilateration are suitable for sensor networks but can only provide coarse location information. On... read morethe other hands, methods relying on Time Difference of Arrival (TDOA), Time of Flight (TOF), and Angle of Arrival (AOA) are more accurate than the RSS methods but need expensive specialized hardware. Radio Interferometric Positioning Systems (RIPS) provides centimeter accuracy, but is still not widely adopted in wireless sensor applications due to the limited set of suitable radio platforms. As a result, sensor localization remains a challenging problem. The objective of this dissertation is to decrease hardware requirements for Radio Interferometric Positioning while providing sufficient positioning accuracy so that this technology can be realized on a broader set of radio platforms and be widely adopted in a variety of wireless sensor applications. The basic idea behind RIPS is to calculate the position from the phase of an interference signal created by two unmodulated signals at slightly different frequencies. The original RIPS has stringent hardware requirements on the radio platform, including fine frequency tuning, 2-Frequency-Shift-Keying (2-FSK) modulation, and continuous RSS reporting. As a result, only the discontinued Mica2 with CC1000 has been proven to support RIPS so far. As a successor of RIPS, Stochastic Radio Interferometric Positioning System (SRIPS) shortens the measurement time of RIPS at a price of decreasing the positioning accuracy from 3 cm to 30 cm. Many current radio platforms cannot support RIPS/SRIPS because of removal of hardware features needed by these methods, such as the replacement of 2-FSK modulation with Direct Sequence Spread Spectrum Offset-Quadrature Phase Shift Keying (DSSS O-QPSK) modulation. Hence, we introduce Stochastic Radio Interferometric Positioning System with Modulated Signals (SRIPS-MS) to realize Radio Interferometric Positioning on a broader set of radio platforms for a wider adoption of Radio Interferometric Positioning in wireless sensor applications, by altering FSK modulation phase to DSSS O-QPSK modulation, with measured positioning accuracy as 25 cm. In the first part of this dissertation, we present mathematical models of SRIPS-MS based on a signal propagation model in free space and signal processing principles to circumvent the hardware restriction problem in the original RIPS. We perform a theoretical demonstration of the proposed SRIPS-MS by deriving the equation between the phase offset and the distance relationship. In the second part of this dissertation, extensive Matlab simulations are performed to study the performance of SRIPS-MS with different parameter settings in a variety of scenarios. DSSS O-QPSK packet-related parameters are carefully examined and the parameter settings yielding the most accurate phase offsets are chosen for hardware experiments of SRIPS-MS. The third part of this dissertation focuses on designing and implementing a hardware prototype of SRIPS-MS based on CC2420. Experiments in a 20 m × 20 m experimental set-up show that SRIPS-MS CC2420 implementation provides better accuracy than SRIPS (from 25 cm to 30 cm).
Thesis (Ph.D.)--Tufts University, 2018.
Submitted to the Dept. of Electrical Engineering.
Advisor: Chorng Hwa Chang.
Committee: Alva Couch, Byung Guk Kim, and Mohammed Afsar.
Keyword: Computer engineering.read less - ID:
- 6m312179m
- Component ID:
- tufts:25018
- To Cite:
- DCA Citation Guide EndNote
