Internet of Things

IoT Fundamentals

The first computer network derives from the mainframe architecture. Mainframe computers contained massive amounts of processing power, storage, and memory. Mainframes were very expensive to acquire and operate, but they could run multiple programs simultaneously, making them cheaper than other computer systems at the time. Direct console access to the mainframe was limited, and users were force to connect to the mainframe from “thin” (dumb) terminal clients via the first computer network.

As processors became more powerful and easier to manufacture, personal computers provided a lot of functionality at a smaller cost, allowing smaller companies to have access to the benefits of a computer without the costs associating with owning and maintaining a mainframe. Computer networks evolved as they no longer connected thin terminal clients in a small network, instead connecting multiple devices spread across large geographical boundaries.

The protocols to communicate between devices evolved and became more complicated, and they could no longer be managed by the mainframe team. Today, most corporate computer networks are managed by the information technology (IT) departments.

Just as the design of these IT networks evolved as more and more computers were connected to them, the network architecture for IoT networks must evolve too. Traditional IT networks follow the common Access-Distribution-Core model that can connect thousands of devices.

An IoT network is often associated with operational technology (OT), which is defined as the hardware/software that influences physical processes through direct monitoring and/or control. OT networks exist in manufacturing facilities. For example, a programmable logic controller (PLC) is responsible for controlling the movement of motors in robots or conveyors based on feedback from sensors. The OT network connects the PLCs, robots, and sensors together.

An IoT network must be able to scale to handle hundreds of thousands of devices or possibly more. IoT networks become more complicated because they can be large scale (hundreds of thousands) and consist of different devices that communicate with different protocols.

IoT Architecture Models

IoT networks are similar to the first computer networks, which ran multiple network protocols like IPX/SPX, NetBEUI, and TCP/IP. IoT networks must support a range of devices that use a variety of protocols. This is because the hardware refresh cycle is longer than corporate IT systems. As new systems are installed in some parts of a facility, the older systems using different protocols are not updated. Connecting devices that use different protocols requires some skill, and the architecture must also be able to scale to thousands of things while providing security.

Some common IoT architecture models are discussed next.

Machine-to-Machine (M2M) IoT Architecture

In 2013, the European Telecommunications Standards Institute (ETSI), 13 of the founding members, launched an initiative to generate a reference M2M IoT architecture. A key concept was the use of stacks, similar to that of the Open Systems Interconnection (OSI) model used in networking. A key benefit to using stacks is that a component in a stack can be swapped out without impacting the components of the stack next to it.

This provides benefits in the IoT space, considering that multiple things made by different manufacturers often must communicate using different protocols. The M2M IoT architecture focuses on IoT services, applications, and networks by providing interoperability through a variety of application programming interfaces (APIs):

• The IoT M2M application layer is focused on providing connectivity of things to the applications. A key component is that the application layer is responsible for tying into other business intelligence (BI) systems.

• The services layer refers to the logical components of the network and the management protocol they use.

• The network layer refers to the realm in which the things and other devices communicate. It includes the physical network that links them together.

Figure 1-1 demonstrates the machine-to-machine IoT reference architecture.

Figure 1.1 Machine-to-Machine IoT Architecture

The IoT World Forum (IoTWF) Architecture

In 2014, while in Chicago, the IoTWF created a seven-layer architectural reference model. This model provides clarity and simplicity through visualization of all the IoT components: sensors, network, computing, and storage. The model consists of the following seven layers:

• Physical Devices (Layer 1): The bottom layer, which contains things (devices, sensors, and so on).

• Connectivity (Layer 2): This layer provides connectivity among things in Layer 1, Layer 2, and Layer 3. Communications and connectivity are concentrated in this one level.

• Edge Computing (Layer 3): The functions in this level are determined by the need to convert data into information that is ready for processing at a higher level.

• Data Accumulation (Layer 4): This layer is responsible for storing data that was traditionally transmitted live across the wire. The storage of the data allows for analysis or computation at a later time.

• Data Abstraction (Layer 5): This layer is responsible for rendering data and its storage in ways that enable the development of faster or simpler applications. It is responsible for reconciling multiple data formats from different sources, assuring consistent semantics, and confirming that the data is complete.

• Application (Layer 6): This layer is where information is analyzed and interpreted.

• Collaboration and Processes (Layer 7): This layer encompasses people and processes. In essence, this layer is responsible for providing people the right data, with the right analysis, at the right time so that they can engage the correct process.

Figure 1-2 demonstrates the IoT World Forum Reference Architecture.

Figure 1-2 IoT World Forum Reference Model

Common IoT model

Multiple other IoT reference models have continued to evolve over the years. Some of the models have minor differences between them, whereas others have major differences in how they interact. A simplified IoT Architecture consists of the following:

• Things

• Communications

• IoT applications

Figure 1-3 demonstrates the components of the Common IoT model that will be discussed in the following sections.

Figure 1-3 Common IoT Model

Things

As a simple definition, a thing is a device that provides relevant information. The intelligence on a thing can vary from device to device. Communication between things can occur in the following manners:

• Unidirectional: A temperature sensor collects the current temperature from its local thermometer and sends the temperature to a management device for analysis.

• Local: A manual thermostat can collect the current temperature for its internal thermometer and then turn on or off an HVAC (heating, ventilation, and air conditioning) unit.

• Bidirectional: An electronic thermostat can collect the current temperature from its internal thermometer and then send the data to a management device for analysis. The management device could send a signal back to the thermostat to turn on or off the HVAC unit.

A smart thing (also known as a smart object) can take relevant information from the data it receives and take appropriate action after analysis of that information. Some of the newer wireless electronic thermostats are examples of a smart things because they have the capability to be programmed remotely.

Some electronic thermostats can poll a remote temperature sensor and average the temperature of its local sensor to identify the average temperature before turning the HVAC unit on or off. To some people that might not seem very “smart.” However, what if the electronic thermostat could check two different types of sensors? The electronic thermostat could check a temperature sensor and a sensor attached to a door to see if the door is open. If the door is open, turning on the HVAC system would result in a waste of electricity, and now the thermostat has relevant information about whether the cooled air would just flow out through the open door.

Here are some of the common sensors used in an IoT infrastructure:

• Temperature: These sensors collect temperature and report temperature at set intervals.

• Vibration: These sensors collect movement across one, two, or three axes. Vibration sensor is a generic term for proximity sensor, displacement sensor, and accelerometer. The frequency of the vibration and application depends on which sensor is used.

• Pressure: These sensors can report back liquid or air pressure.

• Air quality: These sensors can report air quality, or the chemical breakdown in a specific area. They can be used to detect chemicals that are harmful to humans without protective gear, an improper balance of chemicals for a specific manufacturing process, or the release of toxins into the air that do not meet governmental standards so that the general public can be informed.

• Water quality: These sensors report water quality, or the chemical breakdown in the water. Water is a vital component for manufacturing. It can be used for cooling of equipment, for washing of material as a phase of manufacturing, and for the cleanup process. Generally, manufacturers try to reuse their water supply when they can, but certain processes require the water to have an acceptable level of nonstandard components, which could result in the water needing further treatment before reuse.

• Energy consumption: Energy consumption is observed and reported as electricity is consumed from the perspective of a wire, electrical component (such as a circuit breaker), or the motor itself.

• Location: Location sensors could be GPS sensors that provide specific latitude and longitude, or they could be enabled with a unique wireless signature (Wi-Fi, Bluetooth, and so on) where they can be detected via antennas by an existing wireless infrastructure, and the location can then be calculated using triangulation based on signal strength at multiple radio towers.

• Occupancy: Occupancy sensors can track if an area is being occupied or the number of occupants in an area. This information can be correlated with occupancy in an area at a specific time, which is helpful for identifying resource utilization. Some occupancy sensors have mechanisms to identify one person from another to track repetitive occupancy/utilization.

• Video: Video can be used as a livestream camera or can be stored for analysis or replay at a specific point-in-time. Video sensors can be used for a variety of use cases, from physical security to occupancy sensors, for assisting with the visual inspection of manufacturing processes, and for locating a specific person for law enforcement reasons.

Table 1-1 provides a high-level overview of typical IoT sensors used in various market verticals.

Table 1-1 Things and Market Segment Consumption

A variety of variables and factors need to be taken into account concerning the type of smart thing that should be used. Specifically, the type of data and business use cases should always dictate which sensors are to be used. The selection of things used should also take into account the following items:

• Power source: Is the power source wired or battery driven? If battery driven, how long can the battery last, and how often does it need to be replaced or recharged?

• Ability to move: Is the thing physically attached to an immovable object (steel beam, pole, and so on) or is it mobile via a wearable, attached to an animal or a cart?

• Frequency that data is transmitted: How often is data expected to be transmitted from the thing? The amount of data and frequency can directly correlate to the life of the thing before a temporary power source must be recharged or replaced.

• Connectivity method (wired or wireless): How does the thing communicate with other devices? Does it use a wired technology (serial, Ethernet, and so on) or does it use a wireless technology? The transmission rate for that media and distance to the next upstream network device should be accounted for, too.

• Density of things: How many things are needed in an area to effectively capture data? Can data be transmitted through other things like a mesh network?

• Processing capability: Not all IoT devices have the same amount of processing power or storage. These components vary based on the function and size of the device and directly correlate to the cost.

Communications

This layer provides a mechanism to communicate with other things or external sensors. This layer contains the following constructs:

• Access network (medium)

• Gateways

• Network protocols

• Data exchange protocols

Access Network (Medium): This sublayer refers to the physical medium or wireless technology that is used to provide connectivity between things. Specifically, it is connectivity for thing-to-thing communication, or it provides a centralized aggregation on the network. Physical cables provide consistent availability and bandwidth but are not always available because of cost (initial procurement and/or installation) or not feasible for things that are mobile.

In these circumstances, wireless technologies are commonly deployed. As a general rule of thumb, bandwidth decreases as the wireless range increases. Figure 1-4 demonstrates some common wireless technologies that correlate with a technology’s ability to cover bandwidth against the range available. It is important to take into consideration power consumption and cost when selecting a technology. In general, power consumption and cost increase with high throughput and higher distances.

Figure 1-4 The Effect of Wireless Range on Bandwidth

This sublayer consists of networks that group things as follows:

• Personal area network (PAN): The network around a person. Bluetooth is a common technology used in PANs.

• Home area network (HAN): The network around a home. This includes Bluetooth Low Energy (BLE), ZigBee, and 802.11 Wireless.

• Local area network (LAN): Network around local devices. Most IoT environments prefer to use Category 5/6 cabling because most electricians can repair replace this cabling. Category 5/6 cables are restricted to 100m for signal integrity. Fibre optic cable can be used to exceed this restriction but is not as commonly used in a LAN environment because of the limited workforce that can service this medium.

• Field area network (FAN): Network around a large field area. In general, the FAN is a wide-open area that covers less than 4km.

• Wide area network (WAN): Network that provides connectivity between sites kilometers apart.

• Low-power wide area network (LPWAN): Wireless network that is designed for long-range communications using low power because devices are powered by battery. LoRaWAN and SIGFOX are common LPWAN technologies.

Gateways: As a simple definition, gateways provide a method of connecting different technologies together through translation at the highest portion of the networking stack. Gateways map semantics between two different things and perform translation between devices. It is important to note that gateways do not just provide protocol translation, but that they can merge different architectures.

From the connectivity context, the gateway connects PANs, HANs, LANs, FANs, LANs, LPWANs to the backbone network. Gateways connect to a backbone network to provide a high-speed and hierarchical architecture.

Gateways can provide a method of aggregation of things and for processing data at the edge of the network. This concept is explained further in the “Data Transportation and Computation” section.

Network Protocols: The network protocol is an essential component for all network transmissions. It is responsible for locating things on the network and controlling the flow of data. The transport layer collects all the data and prepares it into a format that can be presented to an application.

The network protocol should be an open standard considering that most IoT networks come from devices and things from different manufacturers. Proprietary protocols would require translation and introduce complexity when things communicate with proprietary protocols with other manufacturers’ things that do not have access to them. The Internet Protocol (IP) has been well established and has become one of the de facto network protocols for IoT.

Data Exchange Protocols: The flow of data between things and systems must either be initiated or requested. Some sensors will push data at regular intervals, whereas other sensors require polling of information (also known as a pull). Table 1-2 displays multiple data exchange protocols and some key factors used for selecting a data exchange protocol.

Table 1-2 Well-Known Data Exchange Protocols Consumption

IoT Applications

Now that all of these smart things can communicate with each other, the true power of IoT can be realized with the usage of applications. IoT applications are classified as analytic and control applications.

IoT Analytic Application: This type of application collects information from multiple things and organizes it in a manner such that calculations can be made easily. Analytic applications can provide historical data, trends, and suggestions based on the results calculated.

An example of an IoT analytic application could be one that collects the amount of energy consumed in a manufacturing plant on a thing-by-thing basis. The analytic application could provide reports that contain power consumption on a daily basis that could be correlated with the types of machines and product yield for that day. The plant planner could make changes to his schedule or process based on this information to improve efficiency.

IoT Control Application: This application controls smart things. A key concept is that the IoT control application contains the ability to process logic that the smart thing does not contain, or to provide a level of orchestration across multiple things.

An example of an IoT control application comes from the oil and gas segment, where oil needs to be moved from one location to another. The application would open the necessary valves in the pipeline and then start the pumps so that oil can flow from one location to another. In this example, the valves would not have any knowledge of the pumps, or vice versa, and the control application would orchestrate turning the pumps on/off or making the valves opened/closed.

It is important to note that some IoT applications can perform both control and analytic functions.

The design of an IoT application must take into account the data structure, frequency, size, and volume of the data transmitted. All of this information directly correlates to the volume of the data transmitted from things to the IoT applications:

• Structure: Data exists in either a structured or unstructured format when it is transmitted and stored. Structured data is organized in a logical manner and provides a consistent form of data entry. Unstructured data comes from human language. The same data that is sent in structured format could be sent in unstructured format, but would require context to understand where that data maps.

• Frequency: The timeframe in which a thing will transmit data to another thing.

• Size: The size of the data correlates to whether the data is structured or unstructured. If the data is structured, then every field should be examined to identify whether or not it truly is necessary, because every field will contribute to the size of the update sent from thing to thing.

• Volume: The volume directly correlates with the type of data, frequency of transmission, size of the data, and the number of devices. If a thing transmits 10KB of data every 5 seconds, this might not seem like a large amount of data. However, if there are 1,000 such things, then the total amount of daily data is 172.8GB.

On the other hand, if a thing transmits 100KB of data every minute and there are 1,000 such things sending data; then the daily data amounts to only 144GB. So even if a thing sends more data, if the frequency is lower, then the overall amount of data is lower.

Data Transportation and Computation

Normal corporate networks use a hierarchical network model that divides the network into three layers: core, distribution, and access. Most end-user devices connect to the access layer, and the data center (DC) connects to the core devices (or a server switch block that connects to the core). Most of the data is generated, stored, and processed in the data center.

However, IoT networks generate almost all of their data at the access layer. IoT networks are generally very large, and they must scale appropriately to handle the data from all of the smart things. The data structure and number of smart things directly correlate to the volume of traffic that is analyzed.

A large IoT network with a million sensors that transmit 15KB of data every 30 seconds can result in 1.8 terabytes (1,800,000MB) of data on an hourly basis (~16 petabytes of data annually). IoT networks of this size must take into account the amount of available bandwidth the access layer has. Depending on the physical access medium, an update could saturate the link.

Figure 1-5 demonstrates four things that transmit via radio towers that can only support 150KB of network traffic. The size of an update is 45KB, which can easily pass across a 150KB link. However, when Thing 1’s packet is combined with the updates for Things 2, 3, and 4, the total data exceeds the supported speed of the radio towers. There is not enough bandwidth for all four things’ updates.

Figure 1-5 Link Saturation

Connected vehicles can generate large amounts of data that exceed 20GB per day. The transfer of this data to the manufacturer on a daily basis is not necessary because most of the relevant processing should be performed within the vehicle. Only a small subset of the data generated is needed by the manufacturer to understand how the vehicle can be improved based on its usage.