IoT-Networks

Hi All,

Welcome to this blog on Networking and Communication as part of our journey on connected world technologies.

Internet of Things is the future in which all kinds of smart devices and
sensors communicate with each other and with distant computers and other 
systems to operate in a seamless fashion.

All of that communication has to happen over some sort of network.Some 
devices might be hardwired into an existing network but others will need
to communicate wirelessly.

IoT networks typically connect to the Internet through the IP stack.This demands a large amount of power and memory from the connecting devices. Due to these high requirements,most of the IoT devices connect locally through non-IP networks,which consume less power and connect to the Internet via a smart gateway.Non IP communication channels such as Bluetooth,RFID,and NFC are fairly popular but are limited in their range.

So their applications are limited to small personal area networks.For increasing the range of such local networks,there was a need to modify the IP stack so as to facilitate low power communication using the IP stack.One of the solutions is 6LoWPAN.We will be discussing this in detail later in our blog on protocols.

IoT devices mainly communicate wirelessly because they are generally installed at geographically spread out locations.The wireless channels often are unreliable.In this scenario reliably communicating data without too many retransmissions is an important issue and so communication technologies are an integral part of the study of IoT.

General network topologies are Bus,Star,Mesh,Point to point as shown in figure.

The network topology selection varies from application to application. Ideal implementation  for IoT would be to create mesh networks.

These are networks in which nodes transfer information across the network. Various devices and sensors could operate as nodes making communication across the network robust.In meshed network even if one node fails,other nodes can route the information to its intended destination.

The nodes in an IoT network will be connected both wired and wireless depending on the need and feasibility. wireless protocols like Wi-Fi,Bluetooth and ZigBee communicate via radio waves in different ways.

The ITU-R(International Telecommunication Union’s Radio communication sector) which coordinates the shared global use of radio spectrum, has reserved several frequency bands for Industrial, Scientific and Medical (ISM) applications. ISM bands are unlicensed, and vary slightly from country to country.

The 2.4 GHz band became very popular because it is allowed for unlicensed use in all regions. The ubiquity of the 2.4 GHz band makes development and distribution of 2.4 GHz-based products across nations easier.

Communication systems utilize a set of rules and standards to format data and control data exchange. The most common model in data communication systems is the Open Systems Interconnection (OSI) model, which breaks the communication into functional layers allowing easier implementation of scalable and interoperable networks.

Open System Interconnection (OSI) model defines a networking framework to implement protocols in seven layers. A 4-layer simplified version of the model is also shown in figure along with example of the TCP/IP stack and wireless communication protocols.

The Link layer

Provides conversion of bits to radio signals (and vice versa), responsible for data framing and reliable wireless communication and manages the access to the radio channel.

The Network layer

Responsible for providing addressing and routing data through the network. IP (Internet Protocol) is the network layer protocol, providing an IP address to devices and carrying IP packets from one device to another.

The Transport layer

Generates communication sessions between applications running on two ends of the network. It allows multiple applications to run on one device, each using its own communication channel.

The Application layer

A popular application layer protocol in the TCP/IP stack is HTTP (or Hypertext Transfer Protocol) which was created to transfer web content over the Internet.

A layered network implementation introduces complexity and requires more code and memory. It also introduces data overheads because every layer requires additional framing and control messages.But layered networks enable more flexibility and scale.Most wireless networks today are designed using 4-layer approach.

The IoT is all about connecting things to the Internet. Devices that are (directly) connected to the Internet must use the IP protocol address to be able to exchange data with devices and servers over the Internet. But devices in a local network can use non-IP protocols to communicate within the local network. Connectivity to the Internet of non-IP devices can be achieved via an Internet gateway. The gateway communicates with local devices using a non-IP protocol on one side, and with other devices on the Internet using IP on the other side. The gateway in this case is an application layer gateway because it needs to strip down the data coming in from the local network and restructure it with a TCP/IP stack to enable communication with an Internet service.

That's all for the day.Have a nice day.We will be discussing more about these networks/protocols in our next posts.

Thanks,

Sailendra

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