The objective of this research report is to identify the key requirements and architectural principles relevant to future Distributed Antenna Systems (DAS), which are expected to offer more advanced functionalities compared to those used in 3G and 4G networks. In terms of requirements, eight key aspects have been defined, including capacity expansion, infrastructure sharing, and energy saving. Additionally, eight design principles have been outlined, including compliance with 3GPP and O-RAN ALLIANCE specifications, as well as ensuring high reliability. To fulfill these principles, this report introduces Analog Radio over Fiber (A-RoF) as an effective technology, offering multiple options for various aspects such as frequency conversion, multiplexing techniques, and network topology.