Channel state information

Imagine you are playing a game of catch with your friend, but sometimes they throw the ball really far and sometimes they throw it much closer to you. Now imagine you are trying to catch the ball with your eyes closed, and you have no idea how far your friend will throw it. That sounds pretty difficult, right? Well, that is kind of like how wireless communication works.

When you use your phone to send a message, it needs to travel through the air to the person you're texting. But just like throwing a ball, sometimes the signal travels very far and sometimes it doesn't travel very far at all. There are a lot of things that can affect how far the signal can travel and how strong it is when it gets to the other person's phone. Some examples include distance, obstacles in the way, and interference from other signals.

Now, let's imagine that you and your friend playing catch have a superpower that lets you know exactly how hard and far your friend is going to throw the ball before they even throw it. That would make it much easier to catch the ball, right? Well, in the world of wireless communication, this superpower is called channel state information (CSI).

CSI is a piece of information that tells your phone how the wireless signal is traveling through the air. It's kind of like your friend telling you how far and hard they're going to throw the ball before they actually throw it. By knowing this information, your phone can adjust how it sends out signals to make sure they get to the other person's phone as efficiently as possible.

CSI is really important for things like streaming video or making phone calls because it helps make sure the signal is strong and doesn't get lost or interrupted. Without channel state information, wireless communication would be like playing catch with your eyes closed and hoping for the best!