# Simulation Framework for Detection and Localization in Integrated Sensing and Communication Systems
## 1 Introduction  
The transition from Fifth Generation (5G) to next generation communication systems (NGCS) marks the evolution towards a fully connected, intelligent society. This evolution is distinguished by the integration of artificial intelligence (AI) and sensing technologies into Sixth Generation (6G) networks [1, 2], aiming to address the growing demands for higher speeds, lower latency, and greater reliability in mobile communications. A key innovation in this context is the development of Integrated Sensing and Communication (ISAC) systems. By merging sensing and communication functionalities within a single framework, ISAC systems promise to efficiently share spectrum and hardware resources. ISAC leverages millimeter Wave (mmW) and Super High Frequency (SHF) bands, whichoffer wide bandwidths and enhanced spatial resolution, enabling precise sensing and high-speed communication [3]. This integration paves the way for diverse and novel applications anticipated in 6G networks. In recent years, within the ISAC framework, recent technical advances in ISAC include signal processing methods [4], ISAC channel modeling [5; 6; 7], channel estimation techniques built on Machine Learning (ML)-based compressed sensing [8], or even novel protocols that involve Quantum-ISAC [9]. In addition, the International Telecommunications Union (ITU) has declared it as one of the main trends in International Mobile Telecommunications (IMT)-2030 [10]. Given all the attention, the research community has primarily focused on advancements, often overlooking the need for a standardized framework to evaluate ISAC. In this context, [11] proposes a methodology to evaluate ISAC, highlighting the main factors that must be considered in channel modeling, i.e., channel correlation between communication and sensing and spatial consistency. Even though the mentioned contribution describes one of the main elements of the physical layer, the authors do not mention any computational reduction solution for the simulation process. As we progress toward emulating a more comprehensive system, we anticipate increased complexity and higher computational costs, just like in predecessor technologies of Fourth Generation (4G) or 5G. Evaluation through simulations has been segmented into link-level and system-level simulations in the literature and previous standardization [12]. According to the ITU, the link level evaluates aspects of the physical layer, and the system level assesses overall network conditions. In the context of system-level simulations, the physical layer abstraction has been instrumental in simplifying the detailed and exhaustive process of physical aspects like modulation or channel effects. Therefore, this abstraction process has been introduced to reduce the computational cost of system-level simulations in IMT-2020, enabling comprehensive evaluations of system performance and optimization strategies [13; 14]. Given this background, it is reasonable to expect a similar trajectory for ISAC, as it remains a wireless technology. The abstraction of the physical layer should now be included in the ISAC framework. Moreover, ISAC is not only a technology that encompasses communication capabilities, but also sensing ones. Therefore, considering this concept, evaluating sensing services must be included in the evaluation process. In sensing services, positioning and detection are highlighted in the literature [1] and in the Third Generation Partnership Project (3 GPP) Technical Specification (TS) 22.137 [15] as the most prominent ISAC use cases. These services can serve as a starting point and be integrated into Physical Layer Abstraction (PLA). Nevertheless, the aforementioned intentions have not been found in the literature. PLA might have been neglected within the ISAC framework. New efforts and novel types of simulations are essential to provide future system simulators with abstractions that facilitate the analysis of ISAC systems.