What is the Architecture of LTE SAE?
Let’s dive into the architecture of the LTE SAE (System Architecture Evolution), which is the backbone of LTE networks. As we explored earlier, LTE is designed to deliver high-speed mobile data, and to achieve that, the network architecture plays a crucial role. The LTE SAE architecture is designed to be more efficient, scalable, and optimized for high-throughput data transmission. I’ll break it down step by step to make it easier for you to understand.
The architecture of LTE SAE is based on a flat and simplified design that enables high performance and low latency. It’s different from older mobile network architectures (like those used in 2G and 3G) and is intended to support data-centric applications like video streaming, gaming, and web browsing. The LTE SAE architecture consists of three main components:
- User Equipment (UE): This is the device you use to access the LTE network, such as a smartphone or a tablet. It connects wirelessly to the LTE network and communicates with the eNodeB (evolved Node B).
- Evolved UMTS Terrestrial Access Network (E-UTRAN): This is the access network layer of LTE, which consists of the eNodeB. The eNodeB is responsible for managing the radio communication between the UE and the core network. It handles tasks like scheduling, resource allocation, and mobility management.
- Evolved Packet Core (EPC): The EPC is the core network of LTE. It consists of several important nodes that manage data transfer and signaling across the network. These nodes include:
- MME (Mobility Management Entity): The MME is responsible for the control plane, including signaling, mobility management, and user authentication.
- SGW (Serving Gateway): The SGW is responsible for data forwarding between the eNodeB and the core network. It handles the user plane traffic.
- PGW (Packet Gateway): The PGW connects the LTE network to external packet data networks, such as the internet. It is also responsible for IP address allocation and managing data traffic between the UE and external servers.
- PCRF (Policy and Charging Rules Function): The PCRF is responsible for enforcing policies related to billing, charging, and quality of service (QoS) within the network.
Now, let’s take a deeper look at the interaction between these components. When you use your mobile device (the UE), it connects to an eNodeB through radio waves. The eNodeB, which is part of the E-UTRAN, communicates with the EPC to establish the data path and manage signaling between your device and the network. The EPC, particularly the SGW and PGW, ensures that your data traffic is routed efficiently to its destination, whether it’s another mobile device or an external server on the internet.
One key feature of the LTE SAE architecture is that it supports IP-based communications end-to-end. Unlike older mobile network architectures, which used circuit-switched technology for voice calls and packet-switched technology for data, LTE exclusively uses a packet-switched network. This enables more efficient use of resources and a better experience for applications that require high data throughput, such as video calling and online gaming.
The architecture is also designed to be more flexible and scalable. As we discussed in previous articles, LTE is all about high capacity and low latency, which is why the flat architecture of the EPC helps minimize delays and simplifies the overall network design. The lack of a complex circuit-switched core allows for faster, more efficient communication across the LTE network.
In summary, the LTE SAE architecture is an advanced, streamlined design that allows for high-speed data transmission, low latency, and improved scalability. By utilizing a flat architecture with key components like the eNodeB, MME, SGW, and PGW, LTE achieves better performance and efficiency compared to older mobile network standards. This design is crucial for supporting the growing demand for mobile data services, including video streaming, gaming, and other bandwidth-intensive applications.