Introduction

Internet of Things (IoT) is a network of devices that connect to and communicate via the internet or other communication networks. These devices collect, exchange, and act on data, often without human intervention. It enables enhanced interactivity and automation across various domains, from smart homes to industrial applications. A typical IOT deployment consists of:

  • Embedded devices / sensors.

  • Communication over an IP network (between the devices and to/from cloud servers).

  • Cloud services, Big Data, Analytics / Machine learning on the cloud.

In the context of NetSim, the sensors are abstract, which means that they could be any kind of sensor or embedded device. These sensors are assumed to sense some physical property or random field such temperature, pressure etc. After sensing the sensors transmit the sensed data in the form of “IP Packets” of user configurable size and interpacket arrival times. NetSim simulates the transmission of these IP packets over an IoT network and does not focus on either, the actual “application payload (or the sensed data)” being sent, or the data storage and analytics of this payload.

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Figure-1: A typical IOT scenario in NetSim

NetSim’s Internet of Things (IoT) and Wireless Sensor Network (WSN) libraries stack comprises of:

  • Application Layer: Sensor App as well as applications such as Voice, Video, CBR etc.

  • Transport Layer: UDP

  • Network layer: AODV and RPL

  • MAC and PHY layers: 802.15.4 Zigbee

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Figure-2: The Result dashboard and Plot window shown in NetSim after completion of simulation.

NetSim models IoT as a WSN that connects to an Internetwork through a LowPAN Gateway. The LowPAN Gateway uses two interfaces: a Zigbee (802.15.4) interface and a WAN Interface. The WSN sends data to a SinkNode. The Zigbee interface allows wireless connectivity to the WSN while the WAN interface connects to the external Internetwork.

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Figure-3: A typical application scenario that can be modeled in NetSim. Sensors can generate (measurement) packets that get queued in its packet buffer. These are then transmitted - directly or via hops - over a wireless link to a gateway that then forwards the packet via the internet to a server. Wireless links support various propagation models and ad hoc routing is supported for multi-hop communication. The MAC/PHY layer protocol supported is 802.15.4.

IEEE 802.15.4 uses either Beacon Enabled or Disabled Mode for packet transmission. In Beacon Enabled Mode, nodes use slotted CSMA/CA algorithm for transmitting packets else they use Unslotted CSMA/CA.