# A Survey on Open Radio Access Networks: Challenges, Research Directions, and Open Source Approaches
## 6 Challenges and Future Research Directions
### Open RAN Field Issues
Future research should mainly focus on improving the latency, stability, and scalability of BC, developing a green mining mechanism for power-limited node devices, and finding ways to lower the cost of incorporating BC into RAN technology [110; 117; 118]. The following paragraphs will discuss other Open Issues relating to the Open RAN field. A lot of challenges and future research directions for Open RAN and O-RAN have been covered in the previous paragraphs. However, issues related to Open RAN still do not belong in previous categories. This last part will discuss those challenges and future directions. As written in the previous implementation and standardization problems paragraphs, we can see that one challenge that needs to be researched deeply is the lack of accessible open hardware for software to run. The limited contributions to RAN open-source software intensify this issue. It seems like some more MNOs and vendors are trying to develop open-source CN and MANO frameworks, such as OMEC [119], Magma [120], Free5 GC [121], and Open5 GS [122]. At the same time, they are not trying to develop RAN-related project frameworks, like OAI-RAN or srsRAN. RAN development is mainly carried out by researchers and small companies with limited human resources and resources [4]. This limitation should be addressed because limited contributions result in limited feedback for the Open RAN standard developing organizations. It poses a severe problem since the organizations cannot verify the viability of the standard that has been developed. The major vendors and MNOs should be more involved in developing RAN-related projects because the RAN stack's lower layers have become increasingly important each day. These lower layers have become sources of telecommunication businesses' intellectual property and product-bearing revenues. Related to this contribution problem is the different licensing models for 3 GPP technologies. Different licensing models exist for 4G/5G technologies software, as shown in Figure 19. As mentioned, most RAN software, such as Amarisoft, Nokia, and Ericsson software, is closed-source, commercial, or copyrighted. Open-source software itself can be divided into permissive and copyright licenses. Both allow developers to copy, modify, and redistribute code freely on open-source or commercial products. However, a copyright license obligates the developer to open their altered source code under open source so it can be publicly available, such as the GNU General Public License (GPL), GNU Lesser General Public License (LGPL), GNU Affero General Public License (AGPL), and Mozilla Public License (MPL). This requirement is undesirable for companies using the source code because they must share their trade secrets. A permissive license does not require developers to release their source code using permissive licensed open-source software publicly. However, some permissive licenses do not retain the intellectual property rights. This creates potential future problems for companies using open-source software for their commercial products. Examples of this type of license are Berkeley Software Distribution (BSD), Massachusetts Institute of Technology (MIT), and Apache v1.1 License. Apache License v2.0 is an example of another type of permissive license that retains intellectual property rights. These different licensing models show that companies can suffer a loss when using the wrong open-source software. Tackling this obstacle, OAI has its software license model to take OAI-RAN to be licensed under OAI's public license, thus allowing their users to use their open-source software easily. The OAI public license allows parties to contribute to the source code while retaining their intellectual property rights. It effectively incentivizes the community to use OAI as a reference implementation in their research and development or productization. Responding to this problem, O-RAN Alliance has also made its initial step to deploy, open, and software RAN using Apache License v2.0.