The Best LTE Network Architecture Diagrams
Wireless operators are rapidly expanding their LTE networks to take advantage of additional efficiency, lower latency and the ability to handle ever-increasing data traffic. RCR Wireless presents a collection of LTE network architecture diagrams.
This diagram from standards body 3GPP shows network evolution from GSM to LTE. The core technologies have moved from circuit-switching to the all-IP evolved packet core (moving left to right). Meanwhile, access has evolved from TDMA (Time Division Multiple Access) to OFDMA (Orthogonal Frequency Division Multiple Access) as the need for higher data speeds and volumes as increased.
According to Chris Pearson, president of 4G Americas, there are currently 101 commercial LTE deployments around the world. “That’s one of the fastest mobile broadband technology deployments ever,” Pearson said.
Ceragon’s diagram of basic LTE architecture demonstrates how LTE flattens network architecture. The previous Gateway GPRS support node (GGSN) for connection between the GPRS network and the Internet, and the Serving GPRS support node (SGSN) for delivery of data packets from nodes within its reach, are replaced by an all-IP structure.
Previous generations of technology relied on a “hub and spoke” design where traffic from all base stations (NodeB) was sent to the Radio Network Controller (RNC). The diagram illustrates that in LTE, the enhanced nodes (eNodeB) have direct connectivity with each other (known as x2 traffic) that enable peer-to-peer applications without reaching deep into the network.
This LTE network architecture diagram (larger version) comes from testing company Breaking Point Systems. Again, it illustrates the connection points from the end user on the left, to the evolved base stations (eNodeB) and then traffic to and between the MME and SGW (Serving Gateway), to the HSS (Home Subscriber Servier) and ultimately to the Packet Data Network (PDN) on the right.
This diagram from Juniper Networks shows the relationship of the LTE radio access network (RAN) to the LTE Evolved Packet Core/System Architecture Evolution, with the PGW (packet data network gateway) connecting the EPC to the Internet in the user/data plane, which carries users’ data traffic. Dotted lines represent network connections within the control plane.
“Once past the cell site, it’s all IP,” said Kittur Nagesh, senior director of service provider solutions for Juniper Networks. “The migration to all-IP architecture mean better spectral efficiency, and a seamless migration for both CDMA and GSM is possible with LTE. There’s also a roadmap to higher performance.”
Interphase Networks’ diagram shows the complex reality in which LTE exists, where it must interact with pre-existing network elements, including 3G networks (and small cell deployments) and Internet Multimedia Subsystems (IMS). Real-world implementations are where the complexity and differences of LTE deployments show up. The MME (Mobility Management Entity, located in the blue 4G area) authenticates wireless devices and is involved in hand-offs between LTE and previous generations of technology.
This image from 4G Americas illustrates the future of LTE deployments, as the technology moves into later releases. A heterogeneous network, or HetNet, is a multi-layer, multi-mode, multi-band network architecture. HetNets involves the use of standard base stations (macro sites) to cover wide areas; microcells to cover individual buildings; picocells to offer wireless on the scale of separate floors of a building; and femtocells to cover small areas such as individual apartments/homes, home offices or home businesses. The goal of HetNets is to optimize spectrum use, increase network capacity and coverage, reduce capital and operating costs, and provide a consistent user experience. Future challenges for LTE HetNets include backhaul for the small cells and effective use of interference cancellation so that the various overlapping cells do not interfere with one another.
