IoT-Oriented Protocols
We can divide protocols into two major categories: those that are tied to a specific physical layer and those that are not. Generally speaking, protocols that rely on a specific physical layer do not use the Internet Protocol, while protocols that are physical layer agnostic do use IP. Zigbee [Zig14, Far08] is a mesh network designed for low-power operation. IOT and AI Company in Australia
variety of derivative application standards specialize the protocol for applications such as smart homes and utilities. Zigbee is based on the IEEE 802.15.4 PHY and MAC standards. 802.15.4 operates in three bands: 868 MHz, 915 MHz, and 2.4 GHz. It delivers bit rates from 20 to 250 kbps, depending on the frequency band. The Zigbee NWK layer sits on top of the 802.15.4 MAC layer and provides data and management services. The APL layer includes three sections: the application support sublayer, the Zigbee Device Objects layer, and the application framework. Technology Services Company in Australia
Zigbee provides two types of network security models: a centralized security network can be started only by a Zigbee coordinator/trust center; distributed security networks do not have a central trust center. Nodes can join either type of network and adapt to the type of network they have joined. Networks are formed by either coordinators or routers after scanning to select an available channel. Coordinators form centralized security networks, while routers form distributed security networks. Network steering is the name for the process by which a node joins a network. After identifying an open network, the node associates with that network and receives a network key. Clusters define interfaces for features and domains. Bluetooth Low Energy (BLE) (https://www.bluetooth.com/what-is-bluetoothtechnology/how-it-works/low-energy) [Hay13] is a part of the Bluetooth standard designed for low-power operation such as devices powered from coin cell batteries. A BLE device can work as a transmitter, receiver, or both. Figure 2.3 illustrates the Bluetooth Classic protocol stack. The link layer provides an advertising service; devices can scan to identify nodes and networks. Devices can act as gateways to the Internet based on network address translation. The BLE protocol is stateful. BLE includes a number of optimizations to reduce power consumption. LoRa (http://lora-alliance.org) [LoR15] is designed for wide-area IoT applications with a base station covering hundreds of square kilometers. It is designed to support a network topology with gateways for end devices, with gateways organized into their own star network. Data rates range from 0.3 to 50 kbps. MQTT (http://www.mqtt.org) [IBM12, Oas14] is an IoT-oriented protocol with publish/subscribe semantics. The protocol is designed for low overhead and is agnostic to the data payload. MQTT provides three levels of quality of service: at most once provides best-effort service, at least once assures delivery but may incur duplicates, and exactly once ensures the message is delivered without duplication.
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