From the course: NB-IoT (Narrowband IoT) Engineering: Deployment, Configuration, Call Flow Analysis

NB-IoT network architecture (LTE-based core)

From the course: NB-IoT (Narrowband IoT) Engineering: Deployment, Configuration, Call Flow Analysis

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NB-IoT network architecture (LTE-based core)

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We are moving beyond our smartphones to talk about connecting sensors and meters that make up the Internet of Things and are connected to the network. To meet these needs, 3GPP introduced Narrowband IoT as a part of LTE standard. So it is not a brand new network, it is a brilliant optimization of the existing 4G architecture. Your journey begins with the user, in this case, an NB-IoT device. It could be smart parking meter or utility monitor. To get online, its first interaction is with the base station, which is termed as eNodeB in LTE. A crucial process called radio resource management happens here. The device and the base station establish a radio link, and the base station assigns the device a temporary ID. Now the information from the base station moves into the core network. It arrives at its first stop, which the Mobility Management Entity, or MME. Think of MME as a security chief and traffic controller. It has two critical jobs. First is the authentication and second is the coordination with the database storage, which is home subscriber server. The HSS holds all the secret keys and authentication vectors for every legitimate device. It also knows what service each device is allowed to use. The MME and HSS work together to securely authenticate the IoT sensor. Once authenticated, the MME starts building a data path. It initiates the creation of session towards the serving gateway, which is SGW. So serving gateway is the first point for user data. Its responsibility is routing and forwarding the actual data packets. It then further helps establish a connection to the packet data network gateway, which is PGW. So this is the border gateway, the critical link between our mobile network and the outside world like the public internet. But before that, there is another node comes into picture, which is the policy and charging rules function or PCRF. This is the brain of quality of service and data policies. For our IoT sensors, PCRF tells the PGW about the different rules for IoT devices such as this device is a low power, low data rate sensor. It doesn't need high bandwidth but it must be very power efficient. All these policies are enforced by PGW ensuring that the network resources are used smartly. Then PGW connects with the internet which is the external network. Overall, if we recap, the MME is the control master handling authentication and session management with the HSS. SGW and PGW form the data highway, routing packets and connecting to the internet. PCRF provides the smart policies for quality of service and charging. And this elegant separation of control plane and the user plane makes LTE and by extension NB-IoT so scalable and efficient for connecting millions of devices.

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