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 healthcare applications. From the modern availability of wireless medical sensor prototypes to a diverse group of electronic healthcare record databases, IoT has helped ensure that medical service providers do not only diagnose diseases correctly but also ensured that the medical services reach a wide group of people. These wearable devices include smart watches, wristbands, smart textiles, and monitoring patches. The popularity of smart watches and wristbands is gradually but steadily increasing as major technology companies such as Apple, Samsung, and Sony strive to develop such wearables with innovative features. For example, the modern smart watch includes important monitoring sensors such as the accelerometer, and the heart rate monitor.
2.1.3. Neural Sensors
Medical researchers are teaming up with technological scientists to develop devices that has more impact on people’s lives. Currently, there is extensive research on devices that can monitor neural signals in the brain and give information regarding the state of the brain. These devices are also being designed to boost the brain’s operation, such as training it for better attention and focus through a process called neurofeedback. Neurofeedback is a type of biofeedback that trains self-control of the brain functions to the subjects through measurement of brain waves and providing feedback signal. The technique also reads the brain signals using a technology called electroencephalogaphy (EEG) or a brain computer interface. The process is characterized by electronic communication of the neurons inside the brain, creating an electric field that can be measured through assessment of its frequencies. The technology classifies the brain into alpha, beta, gamma, theta, and delta waves based on the frequency recorded. The type of wave recorded then helps determine whether the brain is calm or laden with thoughts. This neurofeedback can be utilized in training the brain to focus or paying better attention towards specific issues. Besides, it can also help in stress management and in bettering mental health.
2.1.4. Chemical and Environmental Sensors
Technology has also been useful in monitoring important environmental parameters, such as temperature, humidity, pressure, and water and air pollution. The simplest technology tools used to measure physical environment parameters include the thermometer and the barometer. Similarly, the air quality is assessed using sensors that measure the presence of gases and other particulate matter in air. Researchers use these tools to measure air pollution and the presence of other environmental contaminants. For example, with the increasing industrialization, the world continues to become more and more contaminated. Some of the gasses emitted into the environment interfere with the ozone layer, contributing to global warming and environmental change. Similarly, chemical sensors play an essential role in detecting the amount of chemicals and biochemical substances in the environment. These sensors comprose of recognition element and a transducer. It also contains the electronic nose and the electronic tongue that sense chemicals through the odor and taste.
2.2. Radio Frequency Identification (RFID)
The RFID is an identification technology that operates on radio frequencies. The technology works by transmitting data stored in a container through radio waves. It operates on the same mechanism as a bar code technology. However, in its case, there is no need for the line of sight communication between the tag and the reader. Besides, it can identify itself from a distance without requiring human intervention. The RFID tags are of two types, the active tags and the passive ones. The former have a power source whereas the later do not have any power source. Instead, the passive tags obtain their power from the electromagnetic waves that the reader emits and are hence cheap and last longer. There are two types of RFID technologies: near and far, the technology utilizes a coil in which alternating current passes and generates a magnetic field. The far RFID has a dipole antenna in the reader that propagates EM waves.
Tracking and monitoring systems using RFID’s has significantly increased as more people and companies adopt technology. The prominence in using these technologies emanates from the fact that they are free from human intervention and hence can help monitor certain trends without the need for constant checks. A study by Boonsong and Ismail (2014) conducted a study to assess how to improve machine to machine communication with the help of active RFID with wireless sensor networks. The purpose of the study was to monitor and identify household electrical consumption. The researchers embedded an in-house built-in tag into the target houses’ electrical power meter with a power management circuit that passed relevant information to the reader. The researchers successfully show the effectiveness of the embedded tags in monitoring power consumption in households. In another instance, Boonsong, Ismail, and Adeleke (2018) propose power monitoring and management as a way of conserving power usage in households. The researchers propose the use of embedded RFID with Wireless Sensor network (WSN) and Internet of Things (IoT) technologies to monitor and manage power consumption in the house. The process is to occur through automated systems.
2.2.1. Challenges of the Technologies
One challenge that this study faces is the tendency to record inaccurate power readings. According to Teymourzadeh, R., Iwan, S. M., & Abueida, A. J. (2013, December), inaccurate meter readings is a common problem for many electric power meters. This problem has been common among many power users and is likely to be a problem in this study as it focuses on household usage of electricity. The RFID technology is expected to eliminate this error by providing accurate readings of the meters. The RFID reader will read the valid card and activate the power meter to turn on the power. When the credit runs low, or before the power is disconnected, the user will receive an SMS message for the alert. The findings of this study show that the use of RFID will be appropriate as it will ensure that there are no interruptions in monitoring the power usage among the households. Simple incidents, such as power cuts because of failure to pay for the electricity will negatively affect the findings of this research. The role of the RFIDs in this study is to track the devices whereas the WSNs will help in gathering and providing information from the various interconnected sensors.
While the use of RFIDs and WSNs will present an excellent opportunity for the study to eliminate any errors that may arise from human intervention and other automated occurrences, the technologies require care as they are also prone to challenges and obstacles in their usage. Landaluce et al. (2020) analyzes six main challenges that the use of the RFID technology is likely to pose. The authors classify these challenges according to the RFID components that include the reader, passive sensor, and the communication protocol that they affect. One of these challenges is the limited energy harvester and read range associated with RFID. According to Kantareddy et al. (2019), the RFID tags are made of scarce materials. The modern RFID platforms mainly applied in the IoT are mostly passive, which means that they cannot operate or sense data when placed out of the reader’s reading range. The reason for this limitation is that the manufacturers opted to reduce the manufacture costs of the integrated circuit, which, unfortunately, limits the power available at the tag.
Another challenge associated with the RFID usage is the potential to lead to sensor responses collisions. Landaluce et al. (2020) notes that RFID sensing application comprises at least one reader and several Rfid sensors that also include at least one sensor. Consequently, when assembling the tags, a collision course may occur because the tags share the communication channel and hence the likelihood of registering simulatenious responses. Khalil (2018) notes that the problem is one of the key casues of energy waste. Besides, it increases the identification time and reduces the read time. Such errors can negatively affect the findings of the study. This research requires a great level of accuracy because it will require determination of the slightest change in electricity consumption among the respondents. Therefore it will be important to avoid instances of power wastes from the tracking devices.
The RFID sensors also suffer from another challenge, which is the lack of flexibility. According to Khalil (2018), the commercial RFID readers are black box systems that only allow limited configuration, and only have the potential to implement the current UHF RFID communication standard called the EPC global class. Consequently, it is impossible to implement new communication protocols beyond those already installed. This may pose a challenge especially if the users opt to introduce new appliances during the study process. For example, the user may opt to introduce a new device in the course of the study, which will definitely increase the power consumption. It will be impossible to assess the consumption of the new device installed for purposes of obtaining the actual consumption of the household without the new device. Such discrepancies may interfere with the results of the study.
RFID usage also faces the danger of high implementation costs. The costs are especially high for the RFID readers compared to that of sensors and tags. Besides, the reader lacks a suitable smartphone platform on which it can operate and is also inflexible. All these challenges will negatively affect the experiment as each of the RFID components will has some weakness that will accumulate the amount of errors. Therefore, the study will demand more resources because monitoring all the household power expenditure using the RFID sensors may be extremely expensive.
2.2.2. Applications of RFID
The RFID technology has found a wide range of applications in sensing events in the physical world. The new applications based on this technology utilize both digital and analogue sensing techniques to identify any variations and send the information to the relevant bodies. A major area where the technology has had a significant impact is in the healthcare sector (Rashee et al., 2017; Yang et al., 2018). The wearable devices operate on this technology to provie efficient medical monitoring. The devices allow the medical providers to gather relevant information about an individual and undertake appropriate inter-departmental communication. It also allows them to provide emergency services more efficiently and effectively. The technology has also revolutionalized the agriculture sector by providing efficient solutions to the problems affecting farmers (Bothe, Bauer, & Aschenbruck, 2019; Saggin et al., 2019). Given the projected increase in the world’s population, several researchers have advocated for an increase in the world’s food production by 2050. The recommendations of these researchers is for the farmers to rely on these technologies and sensors to achieve the productivity goals.
The RFID technology is also being adopted in the transport sector as smart roads and infrastructure continue to develop. Researchers in the automotive sector are also developing self-driving and environment-connected vehicles to facilitate transportation of people and goods. In the retail sector, the RFID tags help identify each product in a store through a unique identifying number, which reduces the need for human intervention. The retail sector relies on this technology to eliminate automation errors. Finally, the RFID technology has also found significant use in the indoor positioning (IP Systems), which has been chosen as one of the indoor wireless location technologies. The technology has found significant uses for positioning, highlighting low costs, and various aspects of tag identification (Zhou, Zhang, & Mo, 2011). Therefore, the RFID sensing technology has found usage in various aspects of human environment including health, agriculture, transportation, retail, industry, ...