The rapid evolution of the mobile internet, mini- hardware manufacturing, micro-computing, and machine to machine (M2M) communication has enabled the IoT technologies. According to Gartner, IoT is currently on the top of their hype-cycle, which implies that a large amount of money is being invested on it by the industry. Billions of dollars are being spent on IoT enabling technologies and research while much more is expected to come in the upcoming years. Many communication technologies are well known such as WiFi, Bluetooth, ZigBee and 2G/3G/4G cellular, but there are also several new emerging networking options such as Thread as an alternative for home automation applications, and Whitespace TV technologies being implemented in major cities for wider area IoT-based use cases. Depending on the application, factors such as range, data requirements, security and power demands and battery life will dictate the choice of one or some form of combination of technologies. The underlying technologies of ubiquitous computing, embedded sensors, light communication and internet protocols allow IoT to provide its significant, however, they impose lots of challenges and introduce the need for specialized standards and communication protocols. we highlight IoT protocols that are operating at different layers of the networking stack, including: Medium Access Control (MAC) layer, network layer and session layer.
IoT Data Link Protocol
An important short-range communications technology is of course Bluetooth, which has become very important in computing and many consumer product markets. It is expected to be key for wearable products in particular, again connecting to the IoT albeit probably via a smartphone in many cases. Bluetooth is a global 2.4 GHz personal area network for short-range wireless communication. Device-to-device file transfers, wireless speakers, and wireless headsets are often enabled with Bluetooth. Bluetooth Low Energy, also known as “Bluetooth Smart,” was developed by the Bluetooth Special Interest Group. It has two parts: controller and host. The physical and link layer are implemented in the controller. The controller is typically a SOC (System on Chip) with a radio. The functionalities of upper layers are included in the hostThe main difference is that BLE does not support data streaming. Instead, it supports quick transfer of small packets of data (packet size is small) with a data rate of 1 Mbps.
ZigBee, like Bluetooth, has a large installed base of operation, although perhaps traditionally more in industrial settings. ZigBee PRO and ZigBee Remote Control (RF4CE), among other available ZigBee profiles, are based on the IEEE802.15.4 protocol, which is an industry-standard wireless networking technology operating at 2.4GHz targeting applications that require relatively infrequent data exchanges at low data-rates over a restricted area and within a 100m range such as in a home or building. There are three types of devices in a Zigbee network: FFD (Fully Functional Device), RFD (Reduced Functional Device), and one Zigbee coordinator. A FFD node can additionally act as a router. Zigbee supports star, tree, and mesh topologies. The routing scheme depends on the topology. Other features of Zigbee are discovery and maintenance of routes, support for nodes joining/leaving the network, short 16-bit addresses, and multihop routing.
Z-Wave is a sub-GHz mesh network protocol, and is a proprietary stack. It’s often used for security systems, home automation, and lighting controls. Z-Wave is a low-power MAC protocol designed for home automation and has been used for IoT communication, especially for smart home and small commercial domains. It covers about 30-meter point-to-point communication and is suitable for small messages in IoT applications, like light control, energy control, wearable healthcare control and others. It uses CSMA/CA for collision detection and ACK messages for reliable transmission. It follows a master/slave architecture in which the master control the slaves, send them commands, and handling scheduling of the whole network.
Dash7 is an open-source wireless network protocol with a huge RFID contract with the U.S. Department of Defense. It is mainly designed for scalable, long range outdoor coverage with higher data rate compared to traditional ZigBee. It is a low-cost solution that supports encryption and IPv6 addressing. It supports a master/slave architecture and is designed for burst, lightweight, asynchronous and transitive traffic.
Filtering: Incoming frames are filtered using three processes; cyclic redundancy check (CRC) validation, a 4-bit subnet mask, and link quality assessment. Only the frames that pass all three checks are processed further.
Addressing: DASH7 uses two types of addresses: the unique identifier which is the EUI-64 ID and dynamic network identifier which is 16-bit address specified by the network administrator.
Frame format: The MAC frame has a variable length of maximum 255 bytes including addressing, subnets, estimated power of the transmission and some other optional fields.
WirelessHART is a datalink protocol that operates on the top of IEEE 802.15.4 PHY and adopts Time Division Multiple Access (TDMA) in its MAC. It is a secure and reliable MAC protocol that uses advanced encryption to encrypt the messages and calculate the integrity in order to offer reliability. The standard offers end-to-end, per-hop or peer-to- peer security mechanisms. End to end security mechanisms enforce security from sources to destinations while per-hop mechanisms secure it to next hop only
LoRaWAN is a newly arising wireless technology designed for low-power WAN networks with low cost, mobility, security, and bi- directional communication for IoT applications. It is a low-power consumption optimized protocol designed for scalable wireless networks with millions of devices. It supports redundant operation, location free, low cost, low power and energy harvesting technologies to support the future needs of IoT while enabling mobility and ease of use featuresOptimized for low-power consumption and supporting large networks with millions and millions of devices, data rates range from 0.3 kbps to 50 kbps.
HomePlugGP is designed for IoT generally and specifically for home automation and smart grid applications. It is basically designed to reduce the cost and power consumption of HomePlug-AV while keeping its interoperability, reliability and coverage. Hence, it uses OFDM, as in HomePlug, but with one modulation only. In addition, HomePlugGP uses Robust OFDM coding to support low rate and high reliability transmission. HomePlug-AV uses only CSMA as a MAC layer technique while HomePlugGP uses both CSMA and TDMA. Moreover, HomePlugGP has a power-save mode that allows nodes to sleep much more than Home Plug by synchronizing their sleep time and waking up only when necessary.
Long-Term Evolution Advanced (LTE-A) is a set of standards designed to fit M2M communication and IoT applications in cellular networks. LTE-A is a scalable, lower- cost protocol compared to other cellular protocols. LTE-A uses OFDMA (Orthogonal Frequency Division Multiple Access) as a MAC layer access technology, which divides the frequency into multiple bands and each one can be used separately. The architecture of LTE-A consists of a core network (CN), a radio access network (RAN), and the mobile nodes. The CN is responsible for controlling mobile devices and to keep track of their IPs. RAN is responsible for establishing the control and data planes and handling the wireless connectivity and radio-access control.
Network Layer Routing Protocols
Routing Protocol for Low-Power and Lossy Networks (RPL) is distance-vector protocol that can support a variety of datalink protocols. It builds a Destination Oriented Directed Acyclic Graph (DODAG) that has only one route from each leaf node to the root in which all the traffic from the node will be routed to. The node sends a Destination Advertisement Object (DAO) to its parents, the DAO is propagated to the root and the root decides where to send it depending on the destination. When a new node wants to join the network, it sends a DODAG Information Solicitation (DIS) request to join the network and the root will reply back with a DAO Acknowledgment (DAO-ACK) confirming the join. RPL nodes can be stateless, which is most common, or stateful. A stateless node keeps tracks of its parents only. Only root has the complete knowledge of the entire DODAG.
Channel-Aware Routing Protocol (CARP) is a distributed routing protocol designed for underwater communication. It can be used for IoT due to its lightweight packets. It considers link quality, which is computed based on historical successful data transmission gathered from neighboring sensors, to select the forwarding nodes. There are two scenarios: network initialization and data forwarding. In network initialization, a HELLO packet is broadcasted from the sink to all other nodes in the networks. In data forwarding, the packet is routed from sensor to sink in a hop- by-hop fashion.
Network Layer Encapsulation Protocols
6LoWPAN uses a lightweight IP-based communication to travel over lower data rate networks. It is an open IoT network protocol like ZigBee, and it is primarily used for home and building automation. The standard has the freedom of frequency band and physical layer and can also be used across multiple communications platforms, including Ethernet, Wi-Fi, 802.15.4 and sub-1GHz ISM. for example, IPv6 provides a basic transport mechanism to produce complex control systems and to communicate with devices in a cost-effective manner via a low-power wireless network.
A very new IP-based IPv6 networking protocol aimed at the home automation environment is Thread. Based on 6LowPAN, and also like it, it is not an IoT applications protocol like Bluetooth or ZigBee. it is primarily designed as a complement to WiFi as it recognises that while WiFi is good for many consumer devices that it has limitations for use in a home automation.
Near field communication is precisely as it sounds—IoT network protocols used for very close communication. it extends the capability of contactless card technology and enables devices to share information at a distance that is less than 4cm.
SigFox is a global IoT network operator. It uses differential binary phase-shift keying (DBPSK) in one direction and Gaussian frequency shift keying (GFSK) in the other direction. SigFox and their partners set up antennas on towers (like a cell phone company) and receives data transmissions from devices such as parking sensors or water meters.
IPv6 over Networks of Resource-constrained Nodes (6Lo) working group in IETF is developing a set of standards on transmission of IPv6 frames on various datalinks. Although, 6LowPAN and 6TiSCH, which cover IEEE 802.15.4 and IEEE 802.15.4e, were developed by different working groups, it became clear that there are many more datalinks to be covered and so 6Lo working group was formed.
Session Layer Protocols
MQTT (Message Queue Telemetry Transport)
Message Queue Telemetry Transport (MQTT) was introduced by IBM in 1999 and standardized by OASIS in 2013. It is based on the ‘Publish Subscribe’ communication model, where a broker is responsible for relaying messages to MQTT clients. This allows multiple clients to post messages and receive updates on different topics from a central server known as the MQTT broker. This is similar to subscribing to a YouTube channel, where you get notified whenever a new video is posted.
The Constrained Application Protocol (CoAP) is another session layer protocol designed by IETF Constrained RESTful Environment (Core) working group to provide lightweight RESTful (HTTP) interface. Representational State Transfer (REST) is the standard interface between HTTP client and servers. CoAP is designed for use between devices on the same constrained network, between devices and general nodes on the Internet, and between devices on different constrained networks joined by the Internet.
IoT Communication Protocol Market
The IoT communication protocol market is expected to grow from USD 11.44 Billion in 2015 to reach USD 15.80 Billion by 2022, at a CAGR of 4.7% during the forecast period. To define, describe, and forecast the IoT communication protocol market on the basis of connectivity technology, end-use application To provide detailed information regarding the major factors influencing the growth of the market (drivers, restraints, opportunities, and industry-specific challenges) To strategically analyze the micro-markets with respect to the individual growth trends, future prospects, and contribution to the total market. The IoT Communication Protocol Market report also provides an in-depth survey of key players in the market which is based on the various objectives of an organization such as profiling, the product outline, the quantity of production, required raw material, and the financial health of the organization.