Chirp Spread Spectrum For Narrow Band Long Range Bio Sensor Networks

The panoply of biosensors constituting Body Sensor Networks (BSN) is an imperative application of the Internet of Things (IoT) in Biomedical Engineering. Medical post-discharge monitoring is an emerging application of IoT where BSNs need to establish Low Power Networks (LPNs) for data exchange. Body sensors and radio forming BSNs are restricted in power especially when the patient is on the move. Power restrictions impose low computational capability of transceivers along with the need for low power connectivity with the monitoring hub. This study investigates the suitability of Chirp Spread Spectrum (CSS) as a modulation scheme for BSNs. CSS is characterized by inherent interference rejection properties and resilience to multipath fading and Doppler effects. Low power capability together with operation at Industry Scientific and Medical (ISM) band makes CSS ideal for setting up a low-cost ad-hoc network of bio-sensors in post-discharge monitoring. This study evaluates the suitability of CSS for establishing LPNs of bio-sensors through simulation of linear chirps at ISM band 868 MHz A mathematical model of chirp is explained and orthogonality with inverse chirps is demonstrated. Performances for Signal to Noise Ratio (SNR) are evaluated for different spreading factors (SF).

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