This blog and the LTE Architecture Technical Poster we have produced were born out of a couple of conversations between the two of us. We were trying to find the best way to illustrate LTE networking, show the various network nodes, explain the many interfaces, acronyms and standards that surround LTE and what people really need to know about modern mobile networks. We quickly came to the conclusion that our previous poster, and many of the other publicly available documents explaining LTE architectures, do not do a good job of showing how the latest standards from 3GPP work together nor how LTE may be deployed as an overlay network while still inter-connecting with GSM/WCDMA and CDMA mobile and Wi-Fi networks. So we felt it was time to start again from scratch.
With that in mind we set about designing and producing the new Alcatel-Lucent LTE Architecture Technical Poster. We felt it would be useful to highlight the most important things that people need to know and understand about LTE – how LTE fits into existing mobile networks, how it interworks with Wi-Fi, how it extends to enable new services like VoLTE, eMBMS, and so on.
What we all need to know
In mapping out our comprehensive LTE network, we came to the conclusion that overall LTE architecture can be broken down into a few “blocks” of related functionality, so we’ve tried to communicate those in our poster. As we began whiteboard this idea, we quickly realised a few things. One was that we needed to map out the base LTE network as a central image and include the other blocks around it. Then another was that to help make it as engaging and comprehensible as possible we would need to colour-code it, so that radio, broadcast, packet core and other functions were clear and easy to identify. Next we felt that it would be useful to split the interfaces using dashed lines for those that only carry control plane information and plain lines for user plane connections.
Then other parts of the LTE map came into view – so we decided that we would include a table of the radio and network bearers, a table of standardized frequency bands and then a section which shows how the key LTE protocols and security work together.
Finally we decided that each block should have a short text explaining the alphabet soup of acronyms, the role of the key network elements and what this brings to the end-user.
All LTE, all in one place
With this plan in place we then began work on the poster itself. Firstly we placed the main LTE and Evolved Packet Core (EPC) networking functions into a large “global view” diagram. We then added the new broadcasting mode for LTE called eMBMS to this diagram, along with the charging nodes plus the way IP networking connects to the EPC.
Underneath we placed a more detailed view on mobility and roaming support plus the new VoLTE solution for voice over LTE which is now being deployed in commercial networks.
The top right-hand section of the poster illustrates how LTE can interwork with legacy 2G or 3G infrastructure that is already in place and here we covered both non-3GPP (CDMA and WLAN) and 3GPP (GSM, WCDMA and TD-SCDMA) legacy networks.
Finally in the top left corner we placed a large table listing the main radio bands, each with its band number and frequency ranges. It is interesting to note that before LTE was launched people tended to talk about radio bands by their frequencies – 850, 900, 1800, etc. With LTE however, we’ve noticed that people refer more to band numbers – band 2, band 17 and so on. Being able to look up the FDD and TDD bands, their commonly-used names and their frequencies seemed to us a smart idea. We also decided to highlight in bold the radio bands most commonly used in the networks.
So that was the target –provide the best possible supporting tool showing the network and how its components all fit together. . We hope you like it and will use it each time you need to review the exact role of any of those network entities and how it interworks with the others. If you would like to receive a hi-resolution hard copy of the LTE network poster in the mail, please click here and complete the form – please enter ‘I WANT A POSTER’ in the subject and we will be happy to send you one!