In this tutorial, I’ll guide you through essential concepts in wireless networking, including CSMA-CA, RTS-CTS, CTS-to-Self, and Adaptive Noise Immunity. Understanding these features can help you design a more reliable and efficient wireless network. Let’s start by comparing the collision detection and avoidance methods used in wired and wireless networks.

1. CSMA-CD in Wired Networks

In a wired Ethernet network, we have CSMA-CD (Carrier Sense Multiple Access with Collision Detection), which manages data transmission by detecting collisions on the network and resolving them. To understand how this works, imagine a scenario with two computers (PC1 and PC2) connected to the same switch. If both PCs try to send data simultaneously, a collision occurs, disrupting the communication.

How CSMA-CD Works

CSMA-CD enables each computer to listen to the network segment before transmitting. If a collision is detected, both devices stop transmitting, wait for a random time, and then attempt to transmit again.

Diagram: CSMA-CD in Wired Networks

I’ll create a diagram illustrating two PCs connected to a hub, showing how they use CSMA-CD to detect and resolve collisions.

Here’s the CSMA-CD diagram illustrating two PCs connected to a switch in a wired network. It shows how simultaneous transmissions lead to a collision, which is detected and resolved by CSMA-CD. Next, I’ll continue with the explanation of CSMA-CA and create diagrams as needed.

2. CSMA-CA in Wireless Networks

Unlike wired networks, wireless networks cannot detect collisions because they operate in half-duplex mode (they can either send or receive data at one time, not both). This is where CSMA-CA (Carrier Sense Multiple Access with Collision Avoidance) comes in. Instead of detecting collisions after they occur, CSMA-CA tries to prevent collisions by requiring devices to check if the medium is free before transmitting.

In a wireless network, devices listen to the channel. If it is clear, they begin transmitting. If another device is already transmitting, they wait for it to finish, which helps reduce the likelihood of collisions.

How CSMA-CA Works

Consider a scenario with a phone and a PC on a wireless network. The PC listens to the channel and, finding it clear, begins transmitting data. Meanwhile, the phone observes a countdown and waits until the PC finishes before it starts sending its own data.

Let’s visualize this scenario with a phone and a PC using CSMA-CA in a wireless network.

Here’s the CSMA-CA diagram, illustrating a wireless network where a PC transmits data while a phone waits, avoiding a collision by listening to the medium.

Next, I’ll explain and create diagrams for the hidden node problem and RTS-CTS solution.

3. Hidden Node Problem and RTS-CTS Solution

In wireless networks, a hidden node problem occurs when devices cannot detect each other due to obstacles, such as walls. This can lead to collisions when two devices try to transmit at the same time, assuming the channel is free.

To solve this, RTS-CTS (Request to Send / Clear to Send) is used. This mechanism enables devices to notify others in the network about their intention to transmit, helping avoid hidden node collisions.

How RTS-CTS Works

When a device (e.g., a phone) wants to transmit, it sends an RTS signal to the access point (AP). The AP then broadcasts a CTS signal to all devices, indicating the channel is reserved. Once acknowledged, the phone sends its data, preventing other devices from transmitting at the same time.

Let’s visualize the hidden node problem and how RTS-CTS resolves it in a wireless network.

Here’s the diagram illustrating the hidden node problem and the RTS-CTS solution. It shows a phone sending an RTS request to the access point, which responds with a CTS to inform all devices, including the hidden PC, about the transmission.

Next, I’ll continue with an explanation and a diagram for CTS-to-Self and Adaptive Noise Immunity. Let’s proceed with these final sections to complete the tutorial.

4. CTS-to-Self: An Alternative Solution

CTS-to-Self is a faster alternative to RTS-CTS, where a device directly broadcasts a “clear to send” signal to notify other devices of its transmission intent. However, this method does not solve the hidden node problem as effectively, since devices that can’t hear the CTS-to-Self signal may still cause collisions.

I’ll create a diagram illustrating how CTS-to-Self works

Here’s the CTS-to-Self diagram, where a device (the phone) directly broadcasts a clear-to-send (CTS) signal to indicate its intent to transmit. This approach does not fully solve the hidden node problem, as other devices (like the PC) may not detect the CTS signal if obstructed.

Next, I’ll complete the tutorial with Adaptive Noise Immunity to show how it reduces noise in challenging environments.

5. Adaptive Noise Immunity

Adaptive Noise Immunity is a feature available on MikroTik devices to help reduce interference in noisy environments. When enabled, the router dynamically adjusts to filter out noise, improving the link’s quality. This option is beneficial in high-interference areas, though it requires additional processing power, increasing CPU load.

Configuring Adaptive Noise Immunity

On MikroTik devices, Adaptive Noise Immunity can be enabled in two modes:

• Access Point and Client Mode: Used on the access point.
• Client Mode Only: Used on the client device (station).

By selecting these settings appropriately, you can improve the connection quality between the access point and connected devices.