How can mobile communication devices be made resistant to interference and noise?

Yes a great way. Successive interference cancellation (SIC) is one way exploited in NOMA can significantly reduce the interference and increase the number of active users given limited number of channels. Another way is to use signal spreading and de-spreading to minimise the interference.

The main issue with SIC in NOMA is the issue of Security. The near user can decode the messages of the far user. If the issue of security is handled well, NOMA is a good candidate for the 5G network as it's multiple access technology

This is true for H2H communication case as number of active users are relatively less as compared to number of channels available. However, imagine a typical scenario in a massive M2M communication case, less number of channels and more number of active users. In that case it would be great to mitigate the interference using intelligence, machine intelligence to be more specific. Also, SIC based NOMA can help to minimise interference. Beamforming is one more way to cater multiple users with same frequency separated in space.

Another technology that can reduce noise and interference is called the Beam-forming technique. Beamforming ensures that antennas are designed to be unidirectional instead of omnidirectional. When transmitting antennas are unidirectional, it is easy to direct the desired information directly to the receiving antenna without interference or noise.

Current cellular systems are not smart and their antenna radiate in all directions and receive from all direction without considering the location or direction between user and BS. In upcoming generation using MIMO, beam can be directed and gain can be increased multiple folds at the same time can minimise the interference. However, at the cost of complexity and cost of signal processing.

Interference and Noise can be problematic in wireless communications. ?? Adjust transmit power and Antenna gain ?? Optimizing signal to noise ratio(SINR). This leads to more BTS capacity, allowing higher QAM modulation, leading to fewer dropped calls. SINR = Signal power ÷ (Noise + Interference power) ?? Fractional Frequency Reuse (FFR) is also a mitigatiin scheme. Transmitting at different frequencies, in different places, and at different times.

I would like to add a nice piece of work that my team has published on random access mechanism (RACH). Devices use many handshakes before being allocated a channel for communication. These handshakes happen on a set of channels called control channels. There are fewer control channels as compared to the communication. Hence, when an M2M device wakes up to communicate it has to compete with millions of such devices and that too over limited control channel. Once the device gets a successful handshaking it is allowed to transmit its data on an assigned communication channel. We have proposed to allow multiple requests by a device and apply SIC at the BS to resolve the contention. It has a significant improvement. doi: 10.1109/TVT.2021.3055286

Apart from cryptographic approach of security, physical layer security (PLS) can also be added to enhance the secrecy performance. Use of diversity methods such as transmitter, antenna, channel, destination selections can improve the PLS. There are number of papers that describe about PLS and I have worked closely with Dr. Chinmoy Kundu to show how PLS can be improved using various approaches. In short, PLS exploits randomness and reciprocity in PHY layer to achieve security without the need of key management infrastructure.

Multiple input multiple output (MIMO) technology is a great way of reducing noise and interference. MIMO technology increases diversity and increases quality of service. MIMO ensures that there are many path in which the desired information can move from the transmitter to the receiver unlike a single input single output (SISO) technique