Physical Design of IoT Part 1

Physical design of IoT refers to Things in IoT and IoT Protocols. Things are node device which have unique identities and can perform remote Sensing, activation and monitoring capabilities. Iot protocols helps communication established between things and cloud based server over the internet.

1. Things in IoT

Things in IoT refers to IoT devices which have unique identities that can perform sensing, activation and monitoring capabilities. IoT can be various type, sensing devices, smart electronic appliances, wearable sensors, and industrial machines.

Above picture shows a generic block diagram of IoT device. An IoT device Mein consist of several interfaces for connections to other devices, wired and wireless.

• I/O interfaces for sensors.
• Interfaces for internet connectivity.
• Memory and storage interfaces.
• Audio/ video interfaces.
• IoT devices collect data from on board or attached sensors and sensed data communicated either to other device or cloud based server. Today many cloud server available for especially IoT system. These platform known as IoT platform. These cloud especially design for IoT purpose. So we can analysis and processed data easily.

How does it work?

For example, if a relay switch connected to an IoT device can turn ON/OFF an appliance on the commands sent to the IoT device over the internet.

2. IoT Protocols

IoT Protocols help to establish communication between IoT device (node device) and cloud based server over the internet. An image is given below buy this image you can understand which protocols used.

i. Link Layer

Link layer protocols determine how data is sent over the network's physical layer or medium (wired or wireless). Link layer determines how the packets are coded and signalled by a hardware device over the medium to which the host is attached.

• Ethernet (802.3): Ethernet is a set of technologies and protocols that are used primarily in wired LANs. It was first standardized in the 1980s in the IEEE 802.3 standard. IEEE 802.3 defines the physical layer and the Media Access Control (MAC) of data link for wired Ethernet networks.
  
• WiFi (802.11): IEEE 802.11 is a part of the IEEE 802 set of LAN protocols, and specifies the set of media Access control (MAC) and physical layer (PHY) protocols for implementing wireless Local area network (WLAN) Wi-Fi computer communication in various frequencies, including but not limited to 2.4 GHz, 5 GHz and 60 GHz frequency bands.
  
• WiMax (802.16): The standard of WiMax technology is a standard for Wireless Metropolitan Area Network (WMANs) that has been developed by Working Group Number 16 of IEEE 802, specializing in point-to-multipoint broadcast wireless access. Initially, 802.16a was developed and launched, but now it has been further refined.802.16d or 802.16-2004 was released as a refined version of 802.16a standard aimed at fixed applications. Another version of standard, 802.16e or 802.16- 2005, was also released and aimed at the roaming and mobile markets.
  
• LR-WPAN (802.15.4): Collection of standards for low-rate wireless personal area networks. Basis for high-level communication protocol, such as Zigbee. Data rates from 40kb/s to 250kb/s provide low-cost and low-speed communication for power-constrained devices.
• Cellular communication (2G/3G/4G): Is a different type of Telecommunication generation. IoT devices are based on standards and communicate over cellular networks.
  

ii. Network/ Internet Layer

This layer responsible for sending IP datagram from source to destination network. It performs the host addressing and packet routing. It's host identification is done using hierarchical IP addressing scheme such as IPv4 or IPv6.

• IPv4: An Internet Protocol Address (IP address) is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. An IP address serves two main functions: Host or network interface identification and location addressing. It uses 32 bit address scheme.
• IPv6: Internet Protocol Version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communication protocol that provides an identification and location system for computers on networks and routers traffic across the Internet. Uses 128-bit address scheme.

Difference Between IPv6 and IPv4

6LoWPAN

It stands for IPv6 over low-power wireless personal area network. It is a very popular standard for wireless communication. It was really the first wireless connectivity standard that was created for the IoT. 6LoWPAN gives IoT connectivity to very small, low-power devices to directly communicate with any other IP-based (Ethernet or Wi-fi) device on the internet. The main name of the protocol is to enable the smallest device to use the Internet Protocol. This takes into consideration the low power working condition and the low bandwidth of the devices. Thus, developing a protocol that acts as a bridge between the bigger and smaller devices was very hard. It operates in 2.4Ghz and data rates of 250 kb /s.

Advantage of 6LoWPAN

• It is a mesh network which is robust and scalable.
• It offers a long range of communication that detects signals below noise level.
• It consume less power as it uses reduced transmission time (using short time pulses). Hence this saves energy and consecutively battery that can be used for very long duration.
• It offers a large network, which can be used by millions of devices.
• It delivers low-cost and Secure communication in IoT devices.
• It offers one-to-many and many-to-one routing. Hence, transparent internet integration is possible.
• It uses IPv6 Protocol and hands can be routed directly to cloud platforms.

Disadvantages of 6LoWPAN

• It is less secure than Zigbee.
• It has less immunity to interference than Wi-Fi or Bluetooth devices.
• Support short range without mesh topology.

iii. Transport layer

This layer provides and to end message transfer capability independence of the underlying network. It provides function such as error control, segmentation, flowchart and congestion control.

TCP (transmission control protocol)

This protocol is a connection-oriented protocol. TCP is a standard that defines how to establish and maintain a network conversation through which application programs can exchange data. TCP works with the Internet Protocol ( IP), which defines how computers send packets of data to each other. Together, TCP and IP are the basic protocols defining the Internet. The Internet Engineering Task Force ( IETF) defines TCP in the Request For Comment (RFC) standard document number 793.

Advantages of TCP

• It helps to establish/set up a connection between different type of computer and retransmit the data. When the centre does not get an acknowledgement tera certain period of time, it will asume that the packet got lost on its way. So it will send it again.
• It ensures reliable transmission and ensures that the data that arrives out of sequence should put back into the order.
• Delays transmission when the network is congested.
• Provide error detection.
• It has the capability to ensure no duplicacy of packets and retransmit lost packets.

Disadvantages of TCP

• Data doesn't always get sent out immediately.
• TCP is comparatively slower than UDP.
• TCP cannot be used for broadcast and multicast connections.

UDP (user datagram protocol)

This protocol is a connectionless protocol. It does not ensure reliable transmission. It does not provide proper ordering of messages. And it is transaction-oriented and stateless. UDP is a transport layer protocol. UDP is a part of the Internet Protocol suite. Refers to UDP/IP suite. Unlike TCP, it is unreliable and does not use acknowledgement packets to confirm successful packet delivery.

Advantages of UDP

• Small packet size than TCP.
• It is connectionless, which means no connection to create and maintain.
• You don't have to create a connection first before sending out data.
• You have more control over when data is being sent out.

Disadvantages of UDP

• Data corruption is a common occurrence on the internet; UDP has a primitive form of error detection.
• No compression for lost packets.
• Packets can arrive out of order.
• No congestion control.

Difference Between TCP and UDP

iv. Application layer

HTTP, CoAP, Websockets, MQTT, XMPP, DDS, AMQP - Their works, Advantages, and Disadvantages we will cover in the next part of this article.

Conclusion

In this article, we have learned about Physical design of IoT, covering its two components that are Things in IoT and IoT Protocols. Readers learn about IoT devices (that can perform sensing, acuating and monitoring capabilities) and differerent types of IoT Protocols in four different layers that is the Link Layer (Ethernet, WiFi, WiMAX, LR-WPAN, and Cellular networks), the Network Layer (IPv4, IPv6, and 6LoWPAN), the Transport Layer (TCP and UDP) .

Fourth layer that is Application layer ( includes HTTP, CoAP, Websockets, MQTT, XMPP, DDS, AMQP, with their work, advantages, and disadvantages), we will cover in the next part of this article. So Stay Tuned and keep Learning!

Thank you for reading this Article!