The ability to connect machines, devices, sensors, and other everyday things into an intelligent network and make sense out of them, has huge promises to change everyday life. As can be expected by taking in our entire world and attempting to change it one stroke and with one magic wand is unrealistic, challenging and cause for chaos in the short term.
For business decision makers and technology providers, some measure of clarity and progress can be made by understanding how the world of IoT functions. Here is a list of the primary fundamentals that are defining the world of IoT today.
Networking topologies
A key consideration when designing IoT networks is the topology of the networks. There are two principal types of networks that are used in design of IoT related networks: star and mesh.
In a star network topology, all nodes are connected to one central node, which is typically the gateway to the Internet. A commonly used Wi-fi network is where the central node is called the access point and the connected nodes are called stations. Star networks are characterised by transfer of large data blocks, fast interconnect speeds, and quick response times.
On the other hand, a star network that uses Bluetooth for example, can only support a limited number of nodes. The cost of scaling and building redundancy within a star network is relatively expensive.
In a mesh network, every node is connected to each other. Out of the multiple nodes inside such local networks, a few of them act as Internet Gateways and relay data into and out off, the local proprietary network to the Internet. Since the process of communication is a large number of small hops, the speed of communication into and out of a local mesh network is relatively slow. They are also more complex to design than star networks.
On the other hand, mesh networks provide multiple internal paths for movement, require small amounts of power to transmit and compute, and can add nodes relatively easily. Hence, they are relatively less expensive to build, highly scalable and also highly redundant.
Types of networks
Personal Area Networks are usually wireless enabled and cover a range of about 10 meters. A common wireless PAN is a smartphone connected over Bluetooth to handful of accessories. Wireless PAN devices usually have low radio transmission power and run over small batteries.
Local Area Networks are either wired or wireless or a combination of both. Wireless LANs usually cover a range up to 100 meters. An example is the home Wi-Fi network providing Internet access to personal computers, smartphones, TVs and household IoT devices.
Neighborhood Area Networks are usually wireless enabled and can reach around 25 km. They use high power levels but transfer relatively low data blocks. An example of Neighborhood Area Network is a smart grid wireless network used to transfer data from home utility meters to the utility company using a selected frequency.
Wide Area Networks are spread across a very large area and can be as big as the world like the Internet.
Interoperability standards
One of the biggest challenges across IoT devices, sensors, networks and applications is the ability to understand and to communicate with each other. This is also called interoperability. A number of institutions, alliances, and forums have taken the lead in moving related industries forward in a cohesive manner.
The Institute of Electrical and Electronics Engineers has contributed to the IEEE 802.x family of standards. 802.3 is the Ethernet specification used for wired computer networks; 802.11 is the specification for wireless LAN; 802.15.4 is the specification for the PAN standard used in ZigBee, 6LoWPAN.
The Internet Engineering Task Force is an open standards organisation that is responsible for the Internet Protocol standards. In the past, its request for comments have been responsible for improvement of IPv4 protocol, TCP protocol, and HTTP/1.1 protocol.
Recently significant movements are taking place around wireless technologies including Wi-Fi Alliance, Bluetooth Special Interest Group and ZigBee Alliance. All three provide member companies, services like interoperability test plan and rights to wear their brand logos.
Wireless protocols
However, some of the most innovative changes are taking place with wireless networking protocols. They can be classified based on the following operating characteristics:
- Size of data transfer blocks
- Range of connectivity
- Power requirements
- Networking topology
Bluetooth Low Energy, Bluetooth Smart
Bluetooth is a short-range communications technology, which has become important in computing and consumer products. It will be the key for wearable products connecting to Internet of Things via smartphones in most cases. However, for IoT applications it is Bluetooth Low-Energy or Bluetooth Smart, which is more important since its power consumption is lower than Bluetooth.
Unlike Bluetooth, Bluetooth Smart cannot be used for file transfers and its data packet size is smaller. Industry forecasts expect 90% of Bluetooth-enabled smartphones to be also Bluetooth Smart ready by 2018.
- Frequency: 2.4GHz
- Range: less than 150m
- Data Rates: 1Mbps
Zigbee
ZigBee and its various industrial profiles are based on IEEE802.15.4 protocol, which is an industry-standard wireless networking technology. It is meant for applications requiring limited data transfers at low transfer rates within 100m range, typically in a home or building. It has advantages in complex systems requiring low-power operation, high levels of security, high scalability, high node counts and can support wireless control and sensor networks in IoT applications.
- Frequency: 2.4GHz
- Range: less than 100m
- Data Rates: 250kbps
Z-Wave
Z-Wave is a low-power, low data rate, communication technology, designed for home automation. It supports full mesh networks and is scalable allowing control of up to 232 devices. Z-Wave uses a simpler protocol than others allowing faster development.
- Frequency: 900MHz
- Range: 30m
- Data Rates: less than 100kbps
LoRaWAN
LoRaWAN targets wide-area network applications with low power requirements including mobile communication in IoT, smart city and industrial applications. It is specifically optimised for low-power consumption and supports networks with thousands and millions of devices. The data transfer rate is very low at less than 50 kbps.
- Frequency: Various
- Range: 2-5km urban, 15km suburban
- Data Rates: less than 50 kbps
6LowPAN
6LowPAN stands for IPv6 Low-power wireless Personal Area Network. 6LowPAN is a networking protocol and can be used across Ethernet, Wi-Fi, 802.15.4 and sub-1GHz industrial, scientific and medical bands. A key attribute is the IPv6 stack, which has been important to enable IoT. IPv6 is the successor to IPv4 and enables any object in the world to connect to the Internet with its own unique IP address. It has been designed for home and building automation, and is a transport mechanism connecting complex control systems with devices through a low-power wireless network.
Thread
Thread is based on IPv6 networking protocol and is meant for automating the home environment. It uses existing wireless silicon from chip vendors and supports a mesh network using IEEE802.15.4. It is capable of handling up to 250 nodes with high levels of authentication and encryption. It is based on 6LowPAN and designed to complement WiFi. It recognises that while WiFi is good for many consumer devices it has limitations for use in a home automation setup. A software upgrade allows users to run thread on existing IEEE802.15.4-enabled devices.
- Frequency: 2.4GHz
WiFi
WiFi connectivity is an obvious choice for developers, especially within home environments and LANs. It provides fast data transfer and can handle high quantities of data. But its power consumption is likely to be too high for many IoT applications.
- Frequencies: 2.4GHz and 5GHz bands
- Range: Approximately 50m
- Data Rates: 150-200Mbps is typical, 600 Mbps maximum, latest 802.11-ac offers 500Mbps to 1Gbps
Cellular
Any IoT application that requires operations over long distances can take advantage of Cellular GSM, 3G, 4G. Cellular is suitable for high volumes of data, but the cost and power consumption for managing high volumes of data transfer are likely to be too high for most IoT applications. Cellular is suitable for sensor driven, low data projects, transferred over the Internet.
- Frequencies: 900, 1800, 1900, 2100MHz
- Range: 35km max for GSM, 200km max for HSPA
- Data Rates: less than 170kps GPRS, less than 384kbps EDGE, less than 2Mbps UMTS, less than 10Mbps HSP, 3-10Mbps LTE
All the above parametres will find their way into IoT devices and applications based on the use cases. Future innovations rests in how they are combined and adapted to provide the best user experience in a cost-effective manner, with high levels of security and robustness.
Key takeaways
- A key consideration when designing IoT networks is the topology of the networks
- Any IoT application that requires operations over long distances can take advantage of cellular but the cost and power consumption are likely to be too high for most IoT applications
- In a mesh network every node is connected to each other
- In a star network topology all nodes are connected to one central node, which is typically the gateway to the Internet
- Industry forecasts expect 90% of Bluetooth-enabled smartphones to be also Bluetooth Smart ready by 2018.
- Mesh networks provide multiple internal paths for movement, require small amounts of power to transmit, and can add nodes relatively easily
- One of the biggest challenges across IoT devices, sensors, networks and applications is the ability to understand and to communicate with each other
Bruce Zhou of Axilspot gives an overview of key networking technologies and protocols that are being used to build IoT applications and devices today.