There are a multitude of layers, protocols, and wireless standards for IoT applications. The following blog gives a brief description of these layers and lists (with links!) to a variety of the leading protocols and standards relevant for IoT applications.
IoT Application Protocols
The Application layer protocols are typically responsible for data formatting and presentation, and are commonly based on the HTTP protocol. As HTTP may not be ideal for resource constrained applications, such as many IoT applications, many alternate application layer protocols have emerged.
MQTT *Message Queue Telemetry Transport
SMQTT *Secure MQTT
CoAP *Constrained Application Protocol
DDS *Data Distribution Service
XMPP *Extensible Messaging and Presence Protocol
AMQP *Advanced Message Queuing Protocol
REST *Representational State Transfer
MQTT-SN *MQTT for Sensor Networks
STOMP *Simple Text Oriented Messaging Protocol
SCMP *Simple Message Commerce Protocol
SNMP *Simple Network Management Protocol
LLAP *Lightweight Local Automation Protocol
SSI *Simple Sensor Interface
LWM2M *Lightweight M2M
ONS 2.0 *Object Name Service
SOAP *Simple Object Access Protocol
Network Layer Protocols
The network layer is an infrastructure layer within IoT reference architectures, and handles the addressing and routing of data packets. IPv6 is an anew standard that exceeds IPv4 in the total number of address spaces available.
6LoWPAN *IPv6 over Low-Power Wireless Personal Area Networks
6TiSCH *IPv6 over the TSCH Mode of IEEE 802.15.4e
6Lo *IPv6 over Networks of Resource-constrained Nodes
IPv6 over Bluetooth Low Energy
IPv6 over G.9959
IoT Wireless Standards
Wireless standards are the technologies that bridge wired connections/hardware through wireless transmission and reception medium. Similar to how Ethernet, Fiber-optic, USB, HDMI, and etc. are used for wired connections, there are a variety of wireless protocols designed to serve within a range of application requirements. Typically, these protocols can be broken into three categories; Medium/Short Range Wireless Standards that serve peer-to-peer (P2P), LAN, PAN, and HAN connectivity; Cellular and Mobile Wireless Standards that are generally WAN based standards that use the cellular network; and most recently, Low-Power Wide Area Network (LPWAN) standards that are designed to offer extremely wide coverage using low power and low data rate protocols.
Medium/Short Range IoT Wireless Standards (P2P, LAN, PAN, HAN)
EnOcean *Energy Harvesting
Cellular and Mobile Wireless Standards (WAN)
4G LTE Pro
5G Sub-1 GHz Low-Band
5G Sub-6 GHz Mid-Band
5G Millimeter-wave High-Band
LTE-M *Cellular for Machines
EC-GSM *Extended Range GSM also EC-GSM-IoT
Low-Power Wide Area Network (LPWAN) Wireless Standards/Protocols
NB-IoT *Narrow Band IoT
Though wireless technologies do use RF frequencies to send and receive information (wireless connection), they do require several critical physical RF signal chain components to do so. These components include antenna, RF transmission lines (coax and microstrip), baluns, resistors, capacitors, inductors, attenuators, low noise amplifiers (LNA), power amplifiers (PA), mixers, isolators, amongst a wide variety of testing instruments and components.