3.1 - LTE 4G ARCHITECTURE BASICS - INTRODUCTION

Summary

This video introduces the LTE architecture series, highlighting the major reasons for LTE's development. It discusses the rapid growth in mobile subscribers from 2000 to 2010, leading to network congestion and the need for increased capacity. The video covers the evolution from 3G to LTE, including the redesign of the air interface with OFDM to reduce multipath fading and improve bandwidth utilization. It also touches on the shift to an all-IP core network for simplified design and the introduction of VoLTE. Lastly, it provides insights into the User Equipment, including the SIM card's role in LTE and the distinction between USIM and ISIM modules.

Takeaways

• 📱 The rapid growth in mobile subscribers from 500 million to 4.5 billion between 2000 and 2010, driven by devices like the iPhone and Android smartphones, led to network congestion and a need for increased network capacity.
• 🚀 To address congestion, 3GPP redesigned the Radio Access Network (RAN) and Core Network, leading to the development of LTE.
• 📶 LTE introduced OFDM technology to combat multipath fading and improve data rates, offering more efficient bandwidth utilization with support for bandwidths from 1.25 MHz to 20 MHz and beyond through Carrier Aggregation.
• 🌐 The shift to an all-IP based core network in LTE simplified network design and implementation, replacing the traditional circuit-switched core used for voice and SMS in 2G/3G with Voice over LTE (VoLTE).
• 🔄 LTE's all-IP approach, including for backhaul connections, offered significant simplification over previous technologies that used E-1, ATM, and frame relay links.
• 🔑 The Universal Integrated Circuit Card (UICC), or SIM card, in LTE can run applications like the Universal Subscriber Identity Module (USIM) for user-specific data and the IP Multimedia Private Identity (IMPI) module for secure VoLTE calls.
• 🏗️ The LTE architecture was designed with the Internet of Things (IoT) in mind, prioritizing lower latency and faster backhaul to support the expected 28 billion connected devices by 2021.
• 📡 The User Equipment (UE) in LTE, similar to UMTS and GSM, consists of Mobile Termination (MT) for communication functions, Terminal Equipment (TE) for data streams, and a UICC that can include a USIM or ISIM.
• 🛠️ LTE's air interface and network design improvements were necessary to meet the demands of increased data usage, higher quality voice services, and the integration of IoT devices.
• ⏳ LTE's maximum allowed delay ranges from 50ms to 300ms depending on Quality of Service (QoS), which is crucial for latency-sensitive IoT applications.

Q & A

What was the major reason for the development of LTE?

The major reason for the development of LTE was the need for increased network capacity due to the rapid growth in mobile subscribers and data usage, which led to network congestion around 2010.

How did the introduction of flat rate charging schemes affect mobile networks?

The introduction of flat rate charging schemes, which allowed unlimited data downloads, resulted in network congestion as users consumed more data.

What was the limitation of UMTS or 3G technology that necessitated the redesign of LTE?

UMTS faced design limitations, such as the interface with a carrier bandwidth of 5MHz in WCDMA, which did not scale well in practice and led to the need for a redesign of the RAN and core parts.

What is OFDM and how does it improve LTE performance?

OFDM (Orthogonal Frequency Division Multiplexing) is a technique where data is transmitted over many narrow bands of 180kHz instead of spreading a signal over the entire band. This reduces multipath fading and allows for more efficient bandwidth utilization.

How does LTE's bandwidth flexibility compare to UMTS?

LTE offers more bandwidth flexibility than UMTS, with bandwidth ranging from 1.25MHz to up to 20MHz, and the ability to further increase this through carrier aggregation.

What is the significance of the all-IP based core network in LTE?

The all-IP based core network in LTE simplifies the design and implementation of the air interface, radio network, and core. It also allows for the adoption of VoLTE, which is cheaper and more versatile than traditional circuit-switched voice calls.

Why is latency more important than bandwidth for IoT devices?

For IoT devices, latency is more important than bandwidth because these devices often require real-time or near-real-time communication, which is sensitive to delays in data transmission.

What is the maximum allowed delay in LTE for different QoS?

In LTE, the maximum allowed delay ranges from 50ms to 300ms depending on the Quality of Service (QoS) requirements.

How does the use of IP-based interfaces in LTE simplify network operations compared to earlier technologies?

Using IP-based interfaces in LTE simplifies network operations by replacing earlier technologies that were based on E-1, ATM, and frame relay links, which were narrowband, expensive, and more complex.

What is the role of the Universal Integrated Circuit Card (UICC) in LTE User Equipment?

The UICC, also known as the SIM card, plays a crucial role in LTE User Equipment by storing user-specific data, including the user's phone number, home network identity, and security keys. It can also run applications like the USIM for LTE-specific functionalities.

What are the main components of the Mobile Equipment (ME) in LTE User Equipment?

The main components of the Mobile Equipment (ME) in LTE User Equipment include Mobile Termination (MT), Terminal Equipment (TE), and the Universal Integrated Circuit Card (UICC), which encompasses the SIM card and its applications.

Outlines

00:00

📱 Introduction to LTE Architecture and Its Necessity

This paragraph introduces the audience to the LTE architecture series and explains the reasons behind the need for LTE. It highlights the significant growth in mobile subscribers from 2000 to 2010, driven by devices like the iPhone and Android smartphones. The script discusses how unlimited data plans led to network congestion, necessitating increased network capacity. It contrasts 3G's limitations with LTE's advancements, such as the introduction of OFDM to combat multipath fading and the flexibility of bandwidth allocation up to 20 MHz through carrier aggregation. The paragraph also covers the transition from a circuit-switched to an all-IP core network in LTE, simplifying network design and implementation, and the move towards VoLTE for cost and versatility benefits. Lastly, it touches on the importance of latency for IoT devices and the IP-based interfaces in LTE that simplify network connections compared to previous technologies.

05:00

🔐 Understanding LTE User Equipment and SIM Card Evolution

The second paragraph delves into the LTE user equipment, specifically the SIM card and its functionalities. It explains that the SIM card in LTE can run the Universal Subscriber Identity Module (USIM) application, which stores user-specific data like phone numbers, home network identity, and security keys. Additionally, the SIM card can have an ISIM module for SIP/IMS procedures, which is crucial for VoLTE calls. The paragraph concludes by summarizing the key points discussed and hints at the upcoming video's focus on the complex LTE Network Architecture. It ends with a note of encouragement for continued learning.

Keywords

💡LTE

LTE stands for Long-Term Evolution, which is a standard for wireless broadband communication for mobile devices and data terminals. It is a 4G technology that aims to improve the capacity and speed of wireless data networks using a different radio interface together with core network improvements. In the video, LTE is the central theme, as it discusses the evolution and architecture of the technology that led to the need for LTE, including its capacity to handle the exponential growth in mobile subscribers and data usage.

💡User Equipment (UE)

User Equipment, or UE, refers to the mobile devices used by consumers to access network services. In the context of LTE, UEs are designed to be compatible with the new network architecture, offering enhanced data rates and improved performance. The script mentions that the internal architecture of UE for LTE is similar to UMTS and GSM, highlighting the evolution from previous generations.

💡RAN (Radio Access Network)

The Radio Access Network is the part of a mobile network that connects mobile devices to the network's core. It includes the base stations and all radio transmission equipment. The video script discusses the redesign of the RAN as a major reason for the development of LTE, emphasizing the need for increased network capacity and improved performance.

💡Core Network

The Core Network is the central part of a telecommunications network, providing various services and connections to external networks. In the video, the shift to an all-IP based core network in LTE is highlighted as a significant change from 2G/3G, which used separate circuit-switched and packet-switched cores. This change simplifies network design and enables more efficient use of resources.

💡Carrier Aggregation

Carrier Aggregation is a technique used in LTE to increase data rates and improve network performance by combining two or more component carriers into a larger bandwidth. The script explains that LTE can have bandwidth from 1.25 MHz to up to 20 MHz, and this can be further increased through carrier aggregation, allowing for more efficient bandwidth utilization.

💡OFDM (Orthogonal Frequency-Division Multiplexing)

OFDM is a method of encoding digital data on multiple carrier frequencies, which is used in LTE to transmit data over many narrow bands instead of spreading it over the entire frequency band. The video script mentions that OFDM was introduced in LTE to reduce multipath fading and to provide flexibility in bandwidth allocation, which is crucial for the high data rates required by modern mobile networks.

💡Circuit Switched

Circuit Switched is a telecommunication technology where a dedicated physical circuit is established for the exclusive use of the communication session. The video script contrasts this with the Packet Switched core used for data in 2G/3G networks, explaining that LTE moved to an all-IP based core network, which is more efficient and flexible.

💡VoLTE (Voice over LTE)

VoLTE stands for Voice over LTE and refers to the technology that allows voice calls to be made over the LTE network using IP multimedia subsystem (IMS). The script discusses the transition from circuit-switched voice calls to VoLTE, which is more efficient and versatile, although it also notes the challenges in implementing VoLTE and the use of Circuit Switched Fall Back as a temporary solution.

💡IoT (Internet of Things)

The Internet of Things refers to the interconnection of various devices and sensors embedded in everyday objects, enabling them to send and receive data. The video script anticipates a significant increase in the number of connected IoT devices, emphasizing the importance of latency in LTE networks for these devices, which often require rapid response times.

💡QoS (Quality of Service)

Quality of Service is a set of techniques that ensure that certain data packets are given priority over others, ensuring that critical applications receive the necessary network resources. The video script mentions that QoS mechanisms in LTE ensure that voice calls can maintain quality even when network capacity is reached, which is important for maintaining service levels in a congested network.

Highlights

Introduction to a new series on LTE Architecture.

Discussing the major reason that gave rise to the need for LTE.

Between 2000 and 2010, mobile subscribers grew from 500 million to 4.5 billion due to the rise of devices like iPhone and Android-based smartphones.

Network congestion around 2010 led to a requirement to increase network capacity.

UMTS or 3G, though an upgrade to GSM/GPRS, faced design limitations, prompting 3GPP to redesign the RAN and Core Parts of the network.

OFDM was introduced to reduce multipath fading, improving data transmission over narrow bands of 180KHz.

LTE supports bandwidth from 1.25 MHz to up to 20 MHz, which can be further increased by Carrier Aggregation.

A major change in LTE was the adoption of an all-IP-based core network, leading to the use of Voice over LTE (VoLTE).

Quality of service mechanisms in LTE ensure that bandwidth and other requirements of voice calls are met, even under capacity limits.

The growth of IoT devices will lead to 28 billion connected devices by 2021, making latency a critical factor rather than bandwidth.

In LTE, the maximum allowed delay ranges from 50ms to 300ms, depending on the quality of service (QoS).

All interfaces between network nodes in LTE are now based on IP, simplifying the network compared to earlier technologies.

The user device in LTE is referred to as User Equipment, similar to UMTS, and consists of Mobile Termination (MT), Terminal Equipment (TE), and a SIM card.

The LTE SIM card can run the Universal Subscriber Identity Module (USIM), which stores user-specific data like phone number, home network identity, and security keys.

VoLTE calls are enabled by the ISIM module in the SIM card, which stores information for SIP/IMS procedures.

Transcripts

Hello Everyone!

Welcome back to the world of LTE.

Today we will start a new series on LTE Architecture.

Before we know the architecture we need to understand why do we need the LTE.

In this video, we will start with MAJOR REASON that gave rise to the need of LTE.

We will also discuss a little about the User Equipment before we can dive into the RAN

and Core parts in our subsequent videos.

The period of 2000 to 2010 saw a growth from 500 million to more than 4.5billion mobile subscribers

It was driven by user friendly and attractive devices such as iPhone in 2007 and Android

based smartphones which started from 2008.

Network operators had previously tried to encourage the growth of mobile data, by the

introduction of, flat rate charging schemes that permitted unlimited data downloads.

As a result of these networks started congesting in the years around 2010, leading to a requirement

of increase in network capacity.

The UMTS or 3G was a huge upgrade to GSM/GPRS or 2G.

But it was again facing some design limitations.

That’s why the governing body, 3GPP, decided to redesign the RAN and the Core Part.

For Example Specifying an Interface with a carrier BW

of 5Mhz in WIreless Code Division Multiple Access, was a bold step.

It performed well in limits but in practice it didn’t scale up very well.

We had discussed earlier that Higher the frequency means lower is the time between two transmission

steps which results in higher multipath fading.

That’s why Air interface was redesigned and OFDM was introduced.

where instead of spreading a signal over the entire band the data is transmitted over many

narrow bands of 180Khz.

As a result the attainable data rate compared to UMTS is similar for same BW but Multipath

fading is greatly reduced.

It also provides flexibility as LTE can have BW from 1.25Mhz to Upto 20Mhz which can be

further increased by Carrier Aggregation.

Thus providing more efficient BW utilization.

Now 2G/3G uses traditional Circuit switched core for voice and SMS, and Packet Switched

core for Data.

That means operator has to maintain two core networks simultaneously.

A major change in LTE was adoption of all-IP based core network.

Which means switching to VOIP or in this case Voice over LTE.

It greatly simplifies the design and implementation of Air interface, Radio Network and Core.

Quality of service mechanism on all interface ensures that Bandwidth and other requirements

of Voice Calls can be met even when the capacity limits are reached.

It is difficult to implement that’s why operators use Circuit Switched Fall Back to

2G or 3G for voice calls.

However operators are migrating to VoLTE as it is cheaper and more versatile.

With the advent of IOT devices the total number of connected devices is expected to reach

28 billion by 2021.

Now for these devices Latency is more important than bandwidth.

So a faster backhaul was need of the hour.

In LTE the maximum allowed delay is of the range 50ms to 300ms depending upon the QOS.

Also, all interfaces between network nodes in LTE are now based on IP, including the

back-haul connection to the radio base stations.

Again, this is a great simplification compared to earlier technologies that were initially

based on E-1, ATM and frame relay links, with most of them being narrowband and expensive.

Now you can see that major changes were done in the Radio Access Part.

but in order to access the Radio we need to have a device.

So before we can dive into the architecture let us understand the device used by an end

user.

In LTE Specification the Mobile Device is refereed to as User Equipment same as in UMTS.

The internal architecture of the user equipment for LTE is identical to the one used by UMTS

and GSM which is actually a Mobile Equipment (ME).

The mobile equipment comprised of the following important modules:

Mobile Termination (MT) : This handles all the communication functions.

Terminal Equipment (TE) : This terminates the data streams.

Universal Integrated Circuit Card (UICC) : Also known as the SIM card

The Mobile Termination and Terminal Equipment is basically the antenna.

In LTE the SIM Card can either- Run an application known as the Universal

Subscriber Identity Module (USIM).

A USIM stores user-specific data very similar to 3G SIM card.

This keeps information about the user's phone number, home network identity and security

keys.

It can also have ISIM module.

ISIM carry a lot of information used in SIP protocols such as your IP Multimedia Private

Identity (IMPI), domain, IP Multimedia Public Identity (IMPU) and cipher keys which are

used to encrypt information.

So, this application is used for SIP/IMS procedures - consequently, VoLTE calls.

So friends in this video we have seen what gave rise to the need of LTE.

We have also seen the functioning of User Equipment.

In our next video we will discuss the most complex section of the LTE Network Architecture.

Till then take care.

Happy Learning.