Full Duplex for Joint Communication and Sensing in 6G.

Abstract: Background: 6G mobile communication is one of the fastest-growing fields of technology. The present 5G mobile networks will not be adequate to meet society’s wireless connectivity demand in the near to mid-term future. A new generation of wireless mobile networks has to be developed to address this demand. With the current spectrum already congested in 5G networks, the future 6G networks will have to be operated in the high mmWave and sub-THz frequency bands. Along with this, the parallel advancement in wireless communication and sensing made the researchers understand that these two fields have a lot of things in common in terms of signal processing algorithms, devices and system architecture. This has motivated research on integrating communication and sensing into the same spectrum and system which is a major focus in 6G. Thus, the integration of mobile sensing and mobile communication known as Joint Communication and Sensing (JCAS) will be a key feature of 6G as it enhances spectral efficiency. The usage of higher frequency bands offers a wider bandwidth for the increasing data rate demands. This also enables transceivers to employ massive antenna arrays coupled with wider bandwidth to aid in high resolution sensing of the target devices.                    Objectives: The present research focuses on JCAS that allows a common transmission signal to be used jointly for both communication and sensing. The need for simultaneous transmission and reception on the same frequency and channel for sensing creates a full duplex problem. The foundation of current communication systems is either based on time division duplexing (TDD) or frequency division duplexing (FDD), which avoids simultaneous transmission and reception at the same frequency due to the significant self-interference that would need to be managed. A basic challenge involved while building a full duplex system is the self-interference reduction. The research addresses self-interference mitigation. Methods: Simulation is done in MATLAB to verify the objectives. Results: The suitable candidate spectrum bands for the potential applications ofJCAS along with their sensing profile were identified. A path loss model suitablefor JCAS applications was developed. NR waveform can be used for sensing andcommunication. The digital self- interference mitigation technique was able to handle the self- interference cancellation budget much greater than the self- interference cancellation budget that was allocated for it and establish full duplex. Conclusions: Thus, the thesis explored the candidate frequency bands suitable forJCAS applications, sensing profile of these frequency bands in terms of use cases that can be addressed. The thesis also developed a path loss model suitable for JCAS applications. NR signal performance was evaluated for sensing capability as well. A mono static sensing environment is modeled to study full duplex problem and a technique to handle self-interference mitigation is developed and evaluated