In this lesson, I will explain to you about the MikroTik Wireless Chain. So what is a chain exactly? A chain is a place on the wireless radio when you can plug the antenna on it. It can be that a chain has an internal built-in antenna, or that you can plug on it an outdoor antenna. To make it more clear for you, let me show you this one a MikroTik board:

You can see, this board has a dual chain and those chains are connected to the same wireless radio.

If I look to one of the wireless routers that I am using in this course, I see that they have also 2 chains as the following:

You can see clearly that I have Chain 0 and Chain 1 and each one is being used for Tx (Transmission) and Rx (Receive). But why do you have 2 chains on the same radio? Well that’s because we have have more throughput and we have use 802.11 standards that can provide us more bandwidth such as 802.11n and 802.11ac. Got it?

Now if you want to use 1 chain for transmit and 1 chain for receive, you can just do the following:

By doing so, you will have Chain 0 used to transmit the wireless and Chain 1 is fully used to receive the wireless – this is called SISO (Single Input Single Outpout). Remember, in this case you will have much less throughput than using both chains for both Tx and Rx.

The fact of using multiple chains for Tx and Rx is called MIMO (Multiple Input Multiple Output). Let me explain more about SISO and MIMO.

SISO vs MIMO

As already explained, SISO is single input single output. This technolog is old and mostly using with old wireless standards, TV’s, GSM, satellite, etc…

SISO is half duplex, this means that when an antenna is transmitting, the other antenna should wait until the 1st antenna has finished its transmission so it can transmit back.

While MIMO is totally different, same antenna can send and receive at the same time and that’s what we have seen on our MikroTik router:

In MIMO, there are 2 different types which are:

• SU-MIMO
• MU-MIMO

On SU-MIMO (Single User MIMO), the antennas are fully using for only 1 user. While on the MU-MIMO (Multipler Users MIMO) than the antennas are being used for more than 1 users.

Who will define if the antenna is SU-MIMO or MU-MIMO? Well that’s the antenna manufacturer.

This is all what I wanted to show you in this lesson, I hope you enjoyed it and see you in the upcoming one.