A mobile network is a massive investment for a mobile operator as it consists of many network components that work together to enable cellular services for customers. A mobile network consists of a radio network and a core network at a high level. The radio network is the largest part of the overall mobile network and comprises cellular towers (radio base stations) that every mobile phone must be able to connect to in order to be in service. As a result, the radio base stations or radio nodes are deployed throughout towns and cities to provide full network coverage. If a mobile operator does not invest properly in the radio network, that can result in coverage holes. The radio network connects to the mobile core network which is like a telephone exchange or central office. The core network connects the mobile users to external networks to make calls or to access the internet. The diagram below provides a visual representation of this concept and also lists the nodes included in radio and core networks.
Node B is the radio base station in 3G UMTS networks; eNodeB is the radio base station in 4G LTE networks; gNodeB (gNB) is the radio base station in 5G NR networks. These radio base stations (nodes) are the cell towers mobile operators use to connect our mobile phones to 3G, 4G and 5G networks.
Radio network nodes
The radio network nodes in the second generation mobile networks (2G) are called Base Transceiver Station or BTS. In 3G, 4G and 5G networks, these nodes have different names, including Node B, eNodeB, gNB and ng-eNB. This post aims to focus on the radio network nodes that are employed by the 3G, 4G and 5G mobile networks. If you look at the 3G/4G network architecture below, you can see where Node B and eNodeB are situated. In 5G, we have new network nodes called gNB and ng-eNB.
What is Node B?
When 2G GSM networks (Global System for Mobile Communications) started in the early 1990s, wireless connectivity was enabled by the radio base stations, also known as Base Transceiver Stations or BTS. The word ‘transceiver’ suggests that the base station is capable of transmitting as well as receiving. When 3G UMTS networks came, the 3G base stations were assigned a new terminology, ‘Node B’. Node B, sometimes also written as NodeB, uses WCDMA – Wideband Code Division Multiple Access for the air interface to connect mobile phones to the network. In the overall UMTS network architecture, Node B is part of the UMTS Radio Access Network or UTRAN (UMTS Terrestrial Radio Access Network). If a mobile operator wants to provide nationwide 3G network coverage, it needs to deploy a large number of Node Bs throughout the country.
In 3G UMTS networks, Node Bs are controlled by another radio network entity called the Radio Network Controller- RNC. The 2G equivalent of RNC in the GSM network is the Base Station Controller or BSC. When your cell phone screen shows 3G or H or H+ symbol next to the signal bar, you are being served by a Node B. As shown in the network diagram above, Node B and RNC collectively represent the 3G UMTS radio access network. The RNC then connects through a backhaul link to the SGSN (Serving GPRS Support Node) to establish a connection between the 3G radio access network and the 3G mobile core. You can check out our dedicated post on UMTS to learn about the frequencies used by NodeB in 3G UMTS networks.
What is eNodeB?
The base stations in 4G LTE networks are called evolved Node B or eNodeB. In network architecture diagrams, eNodeB is often abbreviated as eNB. eNodeB is an essential part of the 4G LTE radio network and is capable of performing network control functions in addition to creating mobile network coverage. If you look at the network diagram above, you may notice that the 4G radio network does not have a separate network controller entity. This is different from GSM and UMTS networks that have BSC and RNC, respectively, for network control tasks. It means that for LTE, eNodeB is able to perform the radio access functions that are equivalent to the combined work that Node B and RNC do in 3G UMTS networks. eNodeB represents the 4G LTE radio access network E-UTRAN – Evolved UMTS Terrestrial Radio Access Network. It connects to the 4G LTE core network, the EPC – Evolved Packet Core.
|2G – GSM Radio Network||3G – UMTS Radio Network||4G – LTE Radio Network|
|Base Station – BTS||Base Station- Node B||Base Station and Controller – Evolved Node B|
|Base Station Controller – BSC||Radio Network Controller – RNC||N/A|
—GSM, UMTS and LTE radio network nodes—
In line with the LTE standard, eNodeB employs separate radio access technologies for the uplink and the downlink. The communication between eNodeB and the cell phone employs Orthogonal Frequency Division Multiple Access (OFDMA) for the downlink and Single Carrier Frequency Division Multiple Access (SC-FDMA) for the uplink. Have a look at our Mobile Networks Made Easy if you want to build an overall understanding of how the different network entities, including, eNodeB operate within a mobile network.
What is a 5G base station called?
In the context of 5G networks, two types of radio base station nodes are talked about: gNodeB (gNB) and next-generation Evolved Node B (ng-eNB). gNB is the 5G radio base station, whereas ng-eNB is an upgraded version of the 4G LTE base station.
5G networks use a radio technology called New Radio – NR. 5G NR and 4G LTE networks will co-exist for a long time to cater to a wide range of customer use cases. It means that 5G will not replace all 4G networks, but instead, a combination of 4G LTE and 5G NR networks will work together. Achieving that would require both 4G and 5G to be well-integrated to address deployment scenarios where a mix of gNB and ng-eNB is used.
There are two ways to deploy 5G networks: standalone mode and non-standalone mode. Standalone mode (SA) is where 5G networks operate entirely on their own without any legacy network, i.e. no 4G LTE network dependency. The non-standalone mode (NSA) is the more common one, especially for early adoption of 5G, where mobile operators add 5G NR to their existing 4G LTE infrastructure. NSA makes use of the LTE core network EPC (with some enhancements), whereas SA uses a new 5G core network called 5G Core or 5GC. In both cases, 5G uses a dedicated radio network for the air interface. The radio network for 5G NR is called Next-Generation Radio Access Network or NG-RAN.
Since NSA deployment takes advantage of the existing EPC for core network functions, both LTE and NR radio networks are required to connect to the same EPC. 4G LTE networks can operate the same way they do today by allowing eNB to communicate with EPC for control plane as well as user plane. In other words, all the radio network functions, as well as user functions (e.g. mobile data, QoS etc.), take place through eNB. The 5G radio network node gNB operates slightly differently and is only used for user-level functions. The control plane for 5G is still managed by eNB as part of a concept called dual connectivity.
What are gNodeB and ng-eNB?
5G Node B, abbreviated as gNodeB or gNB, is the radio base station in 5G New Radio networks. The counterpart of gNodeB in LTE networks is eNodeB. In non-stand-alone deployments, gNB is only employed for user-level functions. The control plane for 5G NR in NSA mode is still managed by eNB as part of a concept called dual connectivity. Next Generation Evolved Node B or ng-eNodeB or ng-eNB is an upgraded version of 4G LTE radio base station that can connect 4G LTE devices to the mobile network when a 5G Cloud-Native core network is used by the mobile network instead of a 4G Core network (EPC).
What is the difference between gNodeB and ng-eNodeB?
When the 5G Core network is used instead of EPC, the connectivity for any 5G devices uses the gNB node for both user and control planes. Any 4G LTE devices, on the other hand, use next-generation eNodeB instead of the regular eNodeB to be able to connect to the mobile network through a 5G Core network. The next-generation eNodeB is abbreviated as ng-eNB.
Node B, eNodeB and gNB are essential radio network components for 3G UMTS, 4G LTE and 5G NR mobile networks. Node B is the radio base station for UMTS networks (Universal Mobile Telecommunication System), eNodeB or eNB is the radio network node for LTE networks (Long Term Evolution), and gNB is the radio network node for 5G NR networks. These nodes are installed at the cell sites of mobile operators and can be seen as tall masts, also known as cellular towers.
|Generation||Technology||Base Station – Full Name||Base Station – Abbreviation|
|2G||GSM||Base Transceiver Station||BTS|
|3G||UMTS||Node B||Node B|
|4G||LTE||Evolved Node B|
Next Generation Evolved Node B
|5G||NR||5G Node B||gNodeB – gNB|
Here are some helpful downloads
Thank you for reading this post, I hope it helped you in developing a better understanding of cellular networks. Sometimes, we need some extra support, especially when preparing for a new job, studying a new topic, or maybe just buying a new phone. Whatever you are trying to do, here are some downloads that can help you:
Students & fresh graduates: If you are just starting, the complexity of the cellular industry can be a bit overwhelming. But don’t worry, I have created this FREE ebook so you can familiarise yourself with the basics like 3G, 4G etc. As a next step, check out the latest edition of the same ebook with more details on 4G & 5G networks with diagrams. You can then read Mobile Networks Made Easy, which explains the network nodes, e.g., BTS, MSC, GGSN etc.
Professionals: If you are an experienced professional but new to mobile communications, it may seem hard to compete with someone who has a decade of experience in the cellular industry. But not everyone who works in this industry is always up to date on the bigger picture and the challenges considering how quickly the industry evolves. The bigger picture comes from experience, which is why I’ve carefully put together a few slides to get you started in no time. So if you work in sales, marketing, product, project or any other area of business where you need a high-level view, Introduction to Mobile Communications can give you a quick start. Also, here are some templates to help you prepare your own slides on the product overview and product roadmap.