The overhead and delay of data fusion and medium access control is dispensed with in this physical layer technique for collecting the statistics of the values measured by a cluster of sensors. The reader node transmits a beacon signal. Each sensor synchronizes to the carrier frequency of the beacon carrier signal, and then transmits back a response whose carrier frequency is shifted relative to the beacon frequency, such that the frequency shift amount represents the sensor’s data. The sensors transmit simultaneously, so that the reader node receives a signal that appears to have a Doppler spread. In binary detection, a threshold is applied to the received signal spectrum to detect target presence. When the sensors are measuring an analog value, the mean of the FFT of the received signal is proportional to the distribution of the sensors’ values. Figure 6 shows a sketch of the aerial reading scenario, in which the technique has been shown via simulation to use from 30% to 85% less energy than MAC-aided techniques, for the same quality of parameter estimate. The technique has also been shown in simulation to work for terrestrial reading in the presence of multipath fading.
- A. Akanser and M.A. Ingram, ”Semi-Cooperative Spectrum Fusion (SCSF) for Aerial Reading of a Correlated Sensor Field,” First International Conference on Wireless VITAE, (Outstanding Paper Award), Aalborg, Denmark, May 2009.
- A. Akanser and M.A. Ingram, “MAC-free reading of a sensor network,” Military Communications Conference (MILCOM), October 2007.
Last revised on August 9, 2010.