Artificial Noise Injection: Active Defense in 6G Wireless

Introduction : In traditional wireless security, we used mathematical encryption based keys to protect the data. In 6G , we will use physical approach by blinding the attacker to protect the data. Aritificial Noise Injection is used by physical layer to jam the transmission of eavesdropper while not affecting the legitimate user’s receiver.

How Artificial Noise Works

In this technique, core mechanism relies on beamforming and null space mathematics of beam pattern. Let us understand how it works.

• Setup : Assume that there is a transmitter (by name Alice) which has multiple antennas, legitimate receiver (of person by name Bob) and eavesdropper (by name Eve). Moreover Alice knows channel state information (CSI) of Bob.
• Alice transmits beam with data focused in the direction of Bob and artificial noise into the null space of the Bob’s location.
• Due to above beam pattern, noise at Bob’s location is cancelled out or it is orthogonal to Bob’s channel. Hence Bob receives clean high quality signal. At the same time, Eve has different channel compared to Bob. For Eve, noise does not cancel out and she receives mixture of data plus heavy noise. Due to this SINR drops drastically which makes it impossible to decode the data.

Usage in 6G wireless scenarios

Following are some of the 6G scenarios where aritificial noise is primary security enabler.

1. Securing Massive MIMO
2. Cooperative Jamming
3. Protecting wireless sensing
4. Non-Terrestrial Networks (NTN)
5. Reconfigurable Intelligent Surfaces (RIS)

Summary: The primary goal of artificial noise in 6G is to degrade eavesdropper’s channel quality without affecting the legitimate user by transmitting noise in null space. 6G uses multi-antenna systems and accurate channel state information. ANI method in 6G provides security for simple IoT devices that cannot handle complex encryption. It also enables secure radar sensing.