A Survey on Fluid Antenna Multiple Access for 6G: A New Multiple Access Technology That Provides Great Diversity in a Small Space

In recent times, a fluid antenna system (FAS) has gained attention as a potential contender for 6G wireless networks. Fluid antenna multiple access (FAMA) is a new technology that allows each user to constantly move to the position with the strongest signal-to-interference ratio (SIR) by means of a single RF-chain port fluid antenna. Research works in FAMA mainly focus on propose models and solutions linked to the enhancement of FAMA from several aspects, including FAS system, enhancing orthogonal and non-orthogonal multiple access, channel modeling, diversity gain, artificial intelligence (AI) techniques, FAMA with other emerging technologies for 6G such as intelligent reflecting surface (IRS), multiple-input multiple-output (MIMO), terahertz (THz) communication, etc. There is no survey which covers all these important aspects of FAMA. Based on several concerns, a comprehensive taxonomy of FAMA has been presented in this study. First, FAS system is discussed. Then, FAMA mechanism is presented with its channel modeling and diversity gain. After that, FAMA is investigated with other emerging technologies such as IRS, MIMO, THz communication, etc. AI approaches to enhance FAMA are provided. In the end, we cover the potential research directions for further study in all areas. When designing and enhancing the FAS system, facilitating communication via FAMA, and integrating it with other cutting-edge technologies for 6G, this article may serve as a reference or guidance.