###### Abstract  
In the next-generation communication systems, multiple access (MA) will play a crucial role in achieving high throughput to support future-oriented services. Recently, rate-splitting multiple access (RSMA) has received much attention from both academia and industry due to its ability to flexibly mitigate inter-user interference in a broad range of interference regimes. Further, with the growing emphasis on spectrum resource utilization, integrated sensing and communication (ISAC) technology, which improves spectrum efficiency by merging communication and radar signals, is expected to be one of the key candidate technologies for the sixth-generation (6G) wireless networks. In this paper, we first investigate the evolution of existing MA techniques and basic principles of RSMA-assisted ISAC systems. Moreover, to make the future RSMA-assisted ISAC systems, we highlight prime technologies of 6G such as non-terrestrial networks (NTN), reconfigurable intelligent surfaces (RIS), millimeter wave (mmWave) and terahertz (THz) technologies, and vehicular-to-everything (V2X), along with the main technical challenges and potential benefits to pave the way for RSMA-assisted ISAC systems. multiple access; rate-splitting multiple access; integrated sensing and communication; non-terrestrial networks; reconfigurable intelligent surfaces; millimeter wave and terahertz technologies; vehicular-to-everything +
Footnote †: journal: Electronics Electronics  
1
Footnote 1: email: [EMAIL_ADDRESS]  
Footnote †: journal: Electronics Electronics  
1
Footnote 1: email: [EMAIL_ADDRESS]  
RSMA is that it divides the user's message into common and private parts. Private parts from all the users are separately encoded into the corresponding private message as in SDMA. On the other hand, common parts are jointly encoded into a common message. With this message construction, firstly, each user decodes and removes the common message using the SIC operation. After that, each user decodes the private message as in SDMA. By allocating power to a common message according to the dynamic interference level, RSMA can cover SDMA and NOMA as a special case. It is worth noting that RSMA empowers more efficient, robust, scalable, and flexible communication in various environments over conventional MA schemes [3]. In [4], the authors developed the RSMA power allocation to maximize the sum rate for all users with perfect channel state information (CSI). In [5], RSMA with the max-min fairness (MMF) metric was proposed for imperfect CSI conditions to maximize the minimum rate among all users. Sixth-generation wireless networks are expected to be commercialized in the 2030s. The IMT-2030 Framework has completed the draft of 6G vision, including six usage scenarios [6]. Three of these usage scenarios are advanced versions of the enhanced mobile broadband (eMBB), massive machine-type communication (mMTC), and ultra-reliable and low-latency communication (URLLC) [7], and there are three newly introduced usage scenarios. These include (1) immersive communication, (2) massive communication, (3) hyper-reliable and low-latency communication (HRLLC), (4) ubiquitous connectivity, (5) integrated sensing and communication (ISAC), and (6) integrated AI and communication. Among these, ISAC, also referred to as joint communication and radar (JCR), radar communications (RadComs), or dual-function radar communications (DFRCs), is regarded as one of the key candidate solutions to efficiently exploit the limited spectrum resources with the explosively increasing number of connected machines. A key feature of ISAC is to operate both sensing and communication using a shared spectrum [8]. ISAC is expected to provide not only hyper-connectivity but also robust sensing capabilities. However, a main challenge that arises from ISAC is the interference between communication and sensing due to the overlapping spectrum as well as interference between communication users, making interference management strategies crucial [9].