Intelligent Reflecting Surfaces (IRSs) is a hot topic of nowadays. I would suggest to go for it. For further reading, please simply google and watch some videos on YouTube.
a broad topic for research in the field of Wireless Communication is the use of the idea of Software Defined Networking (SDN) to implement various services. My short list of literature should give you a little introduction.
Best regards and much success
Anatol Badach
Babedi Betty Letswamotse, Reza Malekian, Chi-Yuan Chen, Kgotlaetsile Mathews Modieginyane: „Software Defined Wireless Sensor Networks (SDWSN): A Review on Efficient Resources, Applications and Technologies“; Journal of Internet Technology, Vol. 19, No. 5, Sep 2018
https://jit.ndhu.edu.tw/article/view/1751
Muhammad Arif, Guojun Wang, at al.: "SDN-Based VANETs, Security Attacks, Applications, and Challenges"; Applied Sciences, Vol. 10, Issue 9, May 2020
https://www.mdpi.com/2076-3417/10/9/3217/html
Joseph Khoury, Hani Sami, Haidar Safa, Wassim El-Hajj: On The Use of Software Defined Wireless Network in Vehicular FogComputing Environments; 15th International Wireless Communications and Mobile Computing Conference (IWCMC), Jun 2019
José Quaresma Filho, Nailson Cunha, Robertson Lima, Eudisley Anjos, Fernando Matos: A Software Defined Wireless Networking Approach for Managing Handoff in IEEE 802.11 Networks; Wireless Communications and Mobile Computing , Vol. 2018, Nov 2018