IoT term is used to refer to - the resulting globlal network of connecting smart objects - technologies needed to realize such a vision - applications and services leveraging such technologies required features: - devices hetereogeneity - scalability - data ubiquitous data exchange - energy-optimized solutions key features: - localization and tracking (many applications require position and movement tracking) - self-organization capabilities (support ad-hoc networks) - semantic interoperability (standard formats for data) - embedded security and privacy-preserving mechanism #### Backscattering - allows devices to run without battery - only available at research level for now - use radio frequency signals as power source - two types - ambient - RFID ##### Ambient backscattering - devices harvest power from signals available in the environment - they use existing RF signals without requiring any additional - Performance drawbacks - low data rate (about 1kbps) - not suitable for real-time applications that continuously exchange data - availability of signals - signal may not be available indoor or not powerful enough ##### RFID backscattering - main advantage is the availability of RFID signal. Reader is always present in a RFID ##### Battery free smart home - in a smart home there may be a lot of smart devices - if every one of them has a battery, it's not good for the environment - we can deploy an RFID reader with multiple antennas that covers all the different rooms - of course RFID sensors can have very low capabilities, but they can run sensors! ### Communication add scheme slide RFID tags run EPC Global Standard - in a smart home we may want less bits dedicated to the tag id and more dedicated to the actual data - 8 bits for ID - 6 bits for data - 4 for CRC ### Infrastructure based wireless networks - base stations connected to wired backbone network - stations choses the closest base station - Limits - when no infrastructure is available - expensive/inconvenient to setup - when there is no time to set it up