The communication layer is regarded as the backbone of IoT systems. Among the main operational activities of IoT systems, it enables sensing data, processing data, etc.
The physical system is loaded with data and information which needs to be shared with other nodes. To communicate with other nodes and the outside world (Internet), a communication protocol is needed. Depending on the user’s preference, this communication can be wired or wireless.
Types of Communication Protocols in IoT
Following are the communication protocols which can be used for communication between nodes or for connecting the IoT systems with the Internet:
Wired communication is reliable, secure, and supports high data rates. It is the best option for stationary/fixed devices. However, it has a higher cost of cable implementation and a lack of support for mobility and scalability.
Following are the wired communications for IoT:
This is the most commonly used wired communication in LAN (Local Area Network). It provides wired connectivity through the Ethernet switch and only to fixed/stationary IoT devices.
IoT devices need to be connected to the Ethernet switch using cables. Hence, the IoT device and the switch need to be placed close to each other.
Other than that, it can provide network connectivity with low latency and fast data rates.
The advancement in DSP (Digital Signal Processors) has made it possible for IoT devices to utilise power-line for data transmission. Power-Line Communication is a wired medium which minimises the cost of deploying infrastructure for wired connectivity.
The data rates of narrow-band PLCs can reach hundreds of Kbps, and their range can extend to several kilometres. They operate at frequencies between 3 kHz and 500 kHz. They also can communicate through transformers.
In contrast, broadband PLCs work at 1.8MHz to 250MHz and offer data rates up to several hundred Mbps over short distances.
Narrow-band PLCs, which are installed in the basements of apartments, are used for smart metering, allowing real-time data transmission from residential units to utilities.
The main advantage of PLC over wireless is the high attenuation of wireless signals in dense urban and metropolitan areas.
Nodes/devices in wireless communication are mobile. In addition to being easy to expand without incurring additional costs, wireless communication is more cost-effective due to the ease of installation.
WiFi is based on IEEE 802.11n/IEEE 802.11-ac standard. In IEEE 802.11n and IEEE 802.11-ac, data rates are up to 600Mbps and 1 Gbps, respectively with a range up to several metres. As it runs on TCP/IP, the complexities of the Internet are abstracted once configured. However, it requires significant power, so it is not suitable for battery-operated devices.
Bluetooth is based on IEEE 802.15.1 standard and has data rates up to 1Mbps, with a range up to several metres. This is a low-power wireless protocol. Communication is established between a master and up to seven slaves (maximum) based on a Master-Slave configuration.
Zigbee is based on IEEE 802.15.4 standard. It has data rates up to 250 Kbps with a range up to several metres. Designed for low-power, low-bandwidth communication, it allows devices to communicate directly with each other to increase speed as well as security. Due to the lack of direct Internet protocol support, it requires a router to connect to the Internet.
The LoRaWAN standard supports data rates up to 50 kbps and a range of several kilometres, making it ideal for IoT applications requiring low bandwidth. Due to its long range and low bandwidth, it is suitable for long-range line-of-sight devices that have only small messages to exchange.
NFC (Near-Field Communication)
Commonly used in contactless payments, NFC is a very short-range wireless communication technology based on ISO/IEC 18000-3 standard. It has data rates up to 420 Kbps with a range up to a few centimetres and uses electromagnetic communication between antennas of two devices located next to each other. Besides being used for identification, it can also be used for two-way communication, as it can store small amounts of data. There are two types of NFC tags: read-only tags and rewritable tags. In addition, it supports P2P (point-to-point) network topologies as well.
NB-IoT and LTE-M
NB-IoT and LTE-M fall under the category of M2M (i.e. Machine to Machine) communication and have proven to be very useful in applications like smart city, asset tracking, etc. They are specifically designed for IoT devices that communicate small amounts of data over long periods. Simpler than other cellular protocols, they have much fewer overheads. Although they allow the battery-operated devices to run for months without recharging, they have very limited bandwidth.
RFID (Radio Frequency Identification Tags)
RFID doesn’t require a close connection between the tag and the reader, as it has the capability of identifying itself from a distance without any human interference
After knowing about the different types of protocols used in IoT systems it is important to know which protocol to use for a particular IoT application. When deciding on an IoT communication protocol, questions like the following will make the selection easier:
- Power Consumption and Range:
- Will the nodes operate on Battery?
- Will the device work on high frequency, thus requiring high power?
- Operating Frequency
- What environment will it be used in?
- Data Throughput
- Are we sending small packets of data or large files?
- Will it be a continuous transmission/reception or intermittent communication?
- Network Topology
- Will you be using point-to-point, one-to-many, or many-to-one communication?
- How easily do you want the protocol to be scalable?
- What is your budget?
- Do you want a direct or indirect connection to the internet?
- Percentage-wise, how reliable do you want the protocol to be?
As per the above discussion, we can see that selection of IoT protocol involves a series of trade-offs. For example, You can work at higher frequencies that require high power consumption for the required range of transmission but also provide high data rates.
The communication layer in IoT is an extensive topic with various bifurcations that cannot be covered in one blog. However, this blog has attempted to thoroughly explain the various protocols of the Communication Layer used in IoT and how to choose the appropriate one for your application.