## 4 Proposed Orchestrator
The ideal, in this case, is to have access to the operational information of the MNO in question, which would be accomplished through agreements, and the use of isomorphic encryption is foreseen to _guarantee_ the security and privacy of the data from User Equipment (UE) to gNodeB at the application layer, but it can also be employed in the aggregation and transport networks. If it is not possible to use this information, a predictive algorithm may be used based on data from operations already performed and present in the Orchestrator's Big Data and AI techniques, which will calculate the risks of not meeting the requirements during the provision of the service to the end-user. In other words, the handover risk must be calculated. Again, simulation tools should be used to simulate the operation of the NSs at this point to estimate the prices offered by the MNOs involved in the candidate NS. This simulation will be carried out for each of the candidates, and the lowest price will be listed. The others are on the waiting list so that in case there is a need for handover, it is not necessary to repeat the whole process but just confirm it. In the next step, the _Network Slice Negotiation_ block sends the SLAs to MNOs, and then negotiates and accepts them by those MNOs. This is a sensitive point of the proposed solution because it is currently necessary to have specific solutions for each set of network equipment until there is a standardization of the interfaces. It is noteworthy that 5G-Horizontal will not act directly on the hardware, but rather, it should invoke the Orchestrators/local solutions in their respective domains, that is, invoke the APIs of each local solution to establish the NSs E2E. For the design and implementation of the _Network Slice Negotiation_ block, it will be necessary to have tested the APIs from network equipment manufacturers [34; 82]. Conversely, to close the control loop, the **Network Slice Negotiation** block will collect QoS information from 5G QoS Identifier (5 QI) or even, if possible, QoS offered by the networks that make up each NS in operation to perform simulations and predict the future situation of each. If there is a probability above a particular critical value (which will be defined and adjusted throughout the operation of 5G-Horizontal, using AI and Big Data tools), a handover procedure will be performed to avoid discontinuity of service or loss of quality. The collected QoS data will be stored in the Orchestrator's Big Data structure and will be used by the _Network Slice Negotiation_ and _Network Slice Definition_ blocks to define the NSs when it is not possible to use the operation databases of MNOs. The feedback of the QoS values, associated with the possibility of horizontal handover oriented to the end-user during the execution of the service, provides the dynamic characteristic of the 5G-Horizontal. 10. Finally, the existence of the Big Data structure is essential, where information about services and operation is stored, from which data parameters are collected using NetOps and DevOps techniques, populating relational or non-relational bases. Hence, the AI algorithms will consume the dump and make the prediction analysis based on the defined periodicity or business analysis (operation costs), defined periods (historical analysis), and future operations. It is expected that the more the Orchestrator is used, the more precisely and faster it operates. The private distributed cloud computing environment adopted will allow the Orchestrator, which is implemented in software, to operate adequately and safely.