erent vendors, while also allowing vendor-specific enhancements. An alternative approach that may lead to similar results is open source, where community members (vendors, academia, and volunteers) contribute source code to a common base, which everybody can then use to create products. These products would, at least in the- ory, be interoperable by virtue of the fact that they rely on the same code base (which may also include proprietary enhancements). Perhaps even more importantly, the open source approach helps reducing development and maintenance costs, as at least part of the cost is shared between multiple community members. This is generally in line with the desire of operators to lower NG-RAN deployment costs, and therefore we may see increased interest in open source as we move toward 5G. The open source approach has been hugely successful in some fields, for example in the case of the Linux operating system, which is used on most enterprise servers, and which is also at the core of all Android-based mobile phones. Given the above, it is not surprising that eventually the idea to apply the same concept in telecom emerged. While there are many open source projects and initiatives for various components of a wireless network (e.g. core, management, etc.), in the present section we focus on open source RAN projects, specifically: Open Air Interface Telecom Infrastructure Project (TIP) O-RAN. Before going into the details of RAN open source projects and related technologies, such as software-defined radio (SDR), it is important to discuss what is open source. As the name suggests, open source refers to a product (which may be a pure software or device with software components) for which the end user is able to access (and most importantly - modify) the software. Initially the term was coined for software and, at later stages, it was also extended to include open source hardware. However, since for obvious reasons modifying software is substantially easier than hardware, most open source projects are softwar