The connectivity provider infrastructure to provide connectivity to the mobile user includes the base station, the core network, and the intermediate routers/switches (which forward the networking packets across the physical distances after the base station). The lower row in Figure 1 depicts these entities from the user (left) to the cloud (right), where those between the base station and the core network are within the cellular service provider infrastructure. Beyond the core network is outside of the cellular service provider infrastructure and relies on the collaborations and agreements with other service provider entities.

The base station connects to the mobile user wirelessly and serves as the bridge gateway to transition to the wireless communications for the mobile users in telecommunications networking. Because the mobile user uses a wireless communication link, while the networking from the base station to the internet and cloud are in the form of wired communications, the base station serves as the gateway between wireless vs. wired networking. The user and the base station communicate via radio-frequency (RF) wireless communications, while communication from the base station to the core network and then to the cloud is via wired communications involving other nodes such as routers and switches. Therefore, the base station is the first and the last hop to the mobile users communicating in RF. Beyond the base station, the core network is responsible for much of the digital processing to set up the connectivity services to the mobile user, including user registration, security setup, and service as well as access control. The communications and packets from the user are processed by the core network before it leaves, e.g., to the public internet.

Figure 2 describes the logical interactions for the control communications between the user, base station, and core network. The brief description abstracts from the telecommunications implementations and details from ^[3][4][5] and focuses on the information needed to understand this research. The user and the base station require radio resource control (RRC) and a wireless channel for setting up the RF wireless communications, where the communication resources are shared with multiple other users coexisting in the nearby air medium. The RRC begins with the broadcasting messages by the base stations, including the master information block (MIB) and system information block (SIB). The MIB and SIB messages are publicly broadcasted and advertised as the base station is a public entity for serving the cellular connectivity, often serving a large number of mobile users freely entering and exiting the cell. Receiving and decoding the MIB and SIB enable the mobile user to attach to the base station and set up a communication channel, resulting in the user-dedicated cell radio network temporary identifier (C-RNTI). This wireless channel setup is followed by digital control including the registration and authentication verification as well as the security setup between the user and the core network. From the user and (universal) subscriber identity module (SIM or USIM) registration (which occur in advance before the user activation to receive the connectivity service and not drawn in Figure 2), the core network derives the mobile subscriber identification number (MSIN) and the more temporary ID of the temporary mobile subscription identifier (TMSI) and shares that with the user and the base station. The MSIN is not communicated in plain-text and rather is processed by an encryption function E, thus exchanging $E\left(\mathrm{MSIN}\right)$ . Afterward, the user can use the established RF and digital channel for data communications and networking applications.