Literature Review: IoT Architecture

Chapter 2: Literature Review
2.1. IoT Architecture
The first IoT architectural component is the perception layer, whose role is to collect information using sensors as the key IoT drivers. The technique of smart sensors was developed in the 70s, a time when the processing capabilities based on readout combined with signal processing was less complex in terms of surveillance and warning. The smart sensor technology was restricted to the military environment in its application up until the 90s, following the excellent improvments in the integrated signal readout and processing presented by the CCD-CMOS technologies in FPA (Corsi, 2014). The rapid improvements in the “very large scale integration” (VLSI) processor technology and mosaic EO detector array technology provided for the advancement of Smart Sensors with better signal processing via integration of microcomputers and other VLSI signal processors. Currently, both new and future technologies are creating a new generation of Smart Sensors that are have become more applicable in people’s daily lives unlike in the previous instances.
These Smart Sensors have continued to improve with new sensors being unveiled. According to Swan (2012), there is a wide range of sensors in the IoT ecosystem that connects real-world objects, such as buildings, roads, household appliances, and human bodies, to the internet, allowing the transfer of information among these bodies. The most common type of sensor currently available in the market is the smrrtphone. The smartphone has various types of sensors incorporated in it, such as the camera, the light sensor, microphone, proximity sensor, magnetometer, the GPS, and the movement sensors. Different types of sensors continue to be used, for example the temperature sensors, temperature sensors, himdity sensors, and medical sensors.
2.1.1. Mobile Phone-Based Sensors
The mobile phone is an ubiquitous tool and has several types of sensors embedded in it. The smart phone is a common device in the modern world of technology that is equipped with complex communication and data processing features. Following the increasing adoption of smart phones by the people, researchers in technology continue to show increasing interest in developing smart IoT solutions compatible with smartphones. The smartphones can also be modified to operate additional sensors, which makes them more suitable for IoT applications. Among the useful sensors in the modern smartphones include the accelerometer, the gyroscope, the camera and microphone, the magnetometer, the GPS, the light sensor, and the proximity sensor. The accelerometer senses motion, the gyroscope helps in detecting the precise orientation of the phone, the camera and microphone capture visual and audio information, the magnetometer detects magnetic fields, the light sensor detects intensity of ambient light, and the proximity sensor applies the infrared LED to detect objects.
2.1.2. Medical Sensors
The IoT has also found use in human health improvement. Medical service providers now use sensors to measure and monitor medical parameters of the human body. According to Bui and M. Zorzi (2011), the IoT communication framework has become the main facilitator for distributed worldwide healthc...