JRC Tech Seminar Vol.0
JRC Tech Seminar has been updated with two articles, do you like them? Now, we would like to briefly introduce the basics of LTE, including some technical terms such as UE and eNodeB definitions, for your better reading. So for this reason we would like to release the chapter Vol.0.
In this chapter, we will focus on the definition of the LTE system, its features, its basic components, and so on. Some of the content is described in more detail in our previous blogs, and we will attach links for your reference. So without further ado, let's get started!
What is LTE (Long Term Evolution)?
Mobile communication systems are transitioning to a new generation in a span of about 10 years, aiming to improve the efficiency of communication methods over time.
3GPP (3rd Generation Partnership Project)
3GPP (3rd Generation Partnership Project) determines the technical specifications of mobile communication systems for the 3rd generation and beyond.
The original purpose of the project was to develop standards for 3G cell phones (W-CDMA), but the project is also studying specifications for 4G (LTE) and 5G.
About the generational transition of mobile communication systems and 3GPP, you can refer to our previous blog.
https://www.jrclte.com/blogs/generational-transition-of-mobile-communication-systems
What is Release?
Specifications specified by 3GPP are given the standard name "3GPP Release X" (X is a number). For example, 3GPP Release 8 specifies the specifications for LTE. Each time a new specification is added, a new release is created. Newer release always contains the specifications of older releases. In release 15 and beyond, the specifications for 5G are specified.
3GPP release numbers for each decade and their specifications
Comparsion of Wi-Fi/LTE(4G)/5G
Features of Wi-Fi
No license is required for radio stations, coverage (communication range) is narrow, and because the 2.4GHz/5GHz frequency is shared by various devices, communication stability is reduced due to interference.
Features of LTE (4G)
LTE (4G) needs a radio station license, wider coverage, and more stable communications due to the use of licensed frequencies.
Features of 5G
Although the coverage is narrow, the communication speed is much faster than Wi-Fi and LTE, and it can be used for applications such as IoT, telemedicine, and automated driving.
| Wi-Fi | 4G LTE, LTE-A | 5G | |
| Communication Speed |
～ 1 Gbps |
～ 1 Gbps |
～ 20 Gbps |
| Coverage |
0.2km |
2km |
Hundreds of meters |
| Communication Quality | Not guaranteed | Guaranteed | Guaranteed |
| Applications | Data | Audio, data, video |
Audio, data, video, IoT |
Frequencies and Bandwidths Used in LTE
Frequency
In LTE, the frequencies are divided by numbers called Bands. Whether the communication method is TDD or FDD depends on the Band. Bands 1, 3, 28, 39, 41, and 42 are the most commonly used bands and are also used by Japanese carriers. JRC's private LTE system has many achievements in band 20 and band 28.
| Band | Frequency | Communication Method |
| 1 |
2100MHz |
FDD |
| 3 | 1800MHz | FDD |
| 20 | 800MHz | FDD |
| 28 | 700MHz | FDD |
| 39 | 1900MHz | TDD |
| 41 | 2500MHz | TDD |
| 42 | 3500MHz | TDD |
Bandwidth
Bandwidth is the range of frequencies that can be used for communication. LTE has 1.4MHz, 3MHz, 5MHz, 10MHz, 15MHz, and 20MHz bandwidths.
The wider the bandwidth, the more data can be sent at once, and thus the faster the communication speed. The bandwidths mainly used by JRC customers are 5, 10, and 20MHz.
LTE Communication Method TDD/FDD
There are two communication methods in LTE: TDD (Time Division Duplex) and FDD (Frequency Division Duplex).
Features of TDD
- Transmission and reception are separated by time on a single frequency.
- Only one frequency needs to be allocated.
- Since transmission and reception cannot be performed simultaneously, delays occur.
Features of FDD
- Transmission and reception occur on separate frequencies.
- Since transmission and reception can be done separately, there is less delay.
- Frequencies need to be allocated separately for transmission and reception.
Equipment structure of LTE network
An LTE network consists of three main devices: User Equipment (UE), Evolved Node B (eNodeB), and Evolved Packet Core (EPC).
The part that directly exchanges radio waves between the UE and eNodeB is called RAN (Radio Access Network), and the part that handles UE connection and data routing is called CN (Core Network).
For specifics, please refer to the previous blog.
https://www.jrclte.com/blogs/jrc-tech-seminar-vol.1-lte-attach-sequence-procedure-part-2
UE
User Equipment (UE) is used by end-users to communicate with the LTE network. The UE communicates with nearby eNodeBs using its antenna to send and receive radio signals (control signals and data such as voice and images). UE includes smartphones, tablet devices, and CPE (Customer Premises Equipment).
eNodeB
A base station (eNodeB) consists of a Radio Unit (RU) and a Base Band Unit (BBU). The RU is mainly responsible for transmitting and receiving RF signals and converting baseband signals to RF signals. The BBU mainly controls the entire eNodeB and the conversion process between baseband signals and IP packets.
EPC
The EPC consists mainly of the MME, HSS, S-GW, and P-GW.
- MME (Mobility Management Entity): Control of the UE's location information and packet communication path, and authentication of the UE
- HSS (Home Subscriber Server): A database that stores user subscriber information, location information, and authentication information.
- S-GW (Serving Gateway): Routes packets according to instructions from the MME
- P-GW (Packet Data Network Gateway): Forwarding of packets to external networks such as the Internet
