A Linear Chirp Wireless Transmission Method utilizing Doppler Effect

Abstract

The Chirp Spread Spectrum(CSS) based wireless communication has been widely used in Wireless Sensor Network(WSN). These sensors generally have slow speed, and is becoming more demand for higher data rate. However, due to the low transmission rate of CSS, there are still many problems to be studied. A new modulation method based on the linear chirps is introduced in this paper. Unlike the BOK(Binary Orthogonal Keying) and DM(Direct Modulation) methods, this modulation technique is to implant Doppler frequency shift into the linear chirps. M-ary modulation is realized in a single pulse by this proposed modulation technique. Demodulation is accomplished by calculating the position of the compress pulse peak within the pulse duration, or by using different reference chirp signals in the matching filter.

M-Ary Direct Modulation Chirp Spread Spectrum for Spectrally Efficient Communications

“…A DM scheme may lead to more complexity compared to BOK, but it can ensure higher spectral efficiency if a powerful modulator is used. Paper [11] presents a linear-chirp-based modulation technique, different from BOK and DM CSS, in which a Doppler frequency shift is implanted in the chirp signal at the transmitter. The M-ary chirping is achieved in a single impulse with this proposed modulation technique, and the peak position in the pulse duration is used for demodulation.…”