IoT is all about connecting different devices and multiple factors affects the working and performance of your model. One such factor is “Which TOPOLOGY to choose”. There are multiple options present in front of us to go for, but sometimes this becomes the most neglected thing in our design. We choose any random topology without analyzing the advantages and disadvantages of that particular topology.
One key point we forget while choosing the topology is that the description you find in different website is in respect with computer technology. When we are connecting our hardware device mostly we use cheap microcontrollers to save cost which is very low in performance as compared to computers. In this blog we will be telling you advantages and disadvantages of different topologies with respect to your hardware. Some key differences between to show how computer topology can differ from a simple microcontroller topology:-
Computers can easily embed complex wireless devices for transmission and reception, but for microcontrollers we mostly use single transceivers like nrf24l01. To operate this we have to keep switching the state between Transmitter and Receiver.
Computer can compute millions of bits in few seconds but microcontroller can barely do kilobits of data
Computers can easily be updated and many drivers are available but not in case of microcontrollers.
Different topology and there features from hardware perspective:-
BUS Topology:- This topology is unidirectional and uses a single cable to transmit data between different devices.
Use Case:- It is a kind of MASTER-SLAVE communication in which Master commands and Slave follows. If your Master module does not need the status update from the slave then it is best topology to choose.
Advantages:- The main advantage is that it is a wired transmission. It increases the data rate and minimizes the data loss. Adding an extra slave is very easy and sending broadcast messages is also very easy in this topology.
Disadvantages:– The wired feature restrict the area of usage. This network cannot be used where devices are kept far from each other. Even though the MASTER has transmitted the data he never knows the status, whether the command has been successfully implemented or not because of its unidirectional communication.
RING Topology:- The topology got its name because each node is connected to other two nodes in a form of ring/circle. This is a unidirectional communication system.
Advantages:– it is very easy to code as you just have to define the path for each node. In code you just have to check if this is your address, if not then send it to next node. It is very cost effective for smaller networks.
Disadvantages:– Adding new nodes to the topology is a big headache. If number of nodes in topology is =n then maximum number of nodes one data packet has to travel is n-1 because of its unidirectional characteristics.
MESH Topology:- It is a point-to-point connection to other nodes or devices. In this each devise is connected with all other devices and can send and receive data to and from any device. It has n*(n-2)/2 physical channels to link n devices.
Use Case:- This is the most trending topology in IoT. The basic advantage with this module is that every device is connected to every other device and data can easily be transmitted or received to or from any other device directly without any delay.
Advantages:- Each module can work as a central module and can talk to any other module at any instant of time. What makes it easy to use is that the library for this topology is easily available. Nearly for every wireless transceiver there are some libraries to provide mesh networking.
Disadvantages:– Very hard to implement from hardware perspective as each device must know the address of all other device. Similarly adding a new device is a big issue because you have to register the device address to all other devices one-by-one, you also have to hardcode the address of each device to the new one. This topology is easy to implement if you are using wireless communication like nrf24l01 RF module, but since each node has to connect all other node it restricts the distance.
STAR Topology:- This is also one of the most used network topology. In this type of topology all the computers are connected to a single hub through a cable. This hub is the central node and all others nodes are connected to the central node.
Advantages:– Adding a new module is very easy, you just have to register the device with the central module and he can update the address of the newly added module to every node. Similar case is with device deregistration. Implementation from hardware perspective.
Disadvantages:– As each device has to communicate with the central module the range of communication can decrease in case of wireless transmission system. The performance mostly depends on performance of HUB. If that gets damaged then the whole system will shut down.
CONCLUSION
When you are building IoT solution for Home or Car, there will be a module which will be connected to cloud so that you can remote access it and that module will send the data to other nodes. As far as best topology to choose the opinion may vary from person to person but STAR TOPOLOGY is most widely used. Reasons for choosing this topology are:-
For remote accessing the modules you need to connect it to cloud but if you connect each module with cloud, your cost will touch the sky. And implementing cloud connectivity for each module is expensive as it needs high functioning microcontrollers like Raspberry Pi or C.H.I.P computers.
Performance of Star topology depends on the central module (HUB). For this we can use Raspberry Pi and other nodes can simply run on Arduino or PIC microcontroller.
In connected Home or connected car solution each nodes work solely and barely needs to talk to each other for ex:- the fuel indicator has nothing to do with air pressure in tiers. Any computation will be done by the HUB.
At last the needs and requirement may vary so please choose you topology carefully and keep your hardware capabilities and cost in mind. Please share your views about the post and let me know if you have any better topology ideas to make communication faster and this world a better place.
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