This topic presents in a very simplified way all the main concepts that should be understood by those who know LTE.
LTE Fundamentals
LTE (Long-Term Evolution) is a 4G mobile communication technology designed for faster, more reliable data services. It provides high-speed internet on devices like smartphones and tablets, improving activities like video streaming and gaming. LTE operates across various frequency bands with features like Quality of Service (QoS) to prioritize traffic and Radio Resource Control (RRC) to manage connectivity and power use. With LTE Advanced, the system evolves further, enhancing speed and performance, especially in high-traffic areas.
LTE is like a well-organized highway system for data. The architecture guides traffic (data) efficiently between devices, while interfaces act as junctions connecting areas. Channel bandwidths are the number of lanes, with more lanes allowing faster data flow. FDD and TDD manage traffic flow, either separating or sharing lanes. Operating bands are like regions with specific rules, and bearer types prioritize important data. Radio Resource Control (RRC) states manage whether roads are open or idle. Signaling Radio Bearers organize the traffic signals. QoS prioritizes critical data, mobility management helps switch highways smoothly, and LTE Advanced adds more lanes for even faster traffic.
Skip to: Roadmap to LTE
- LTE, or Long-Term Evolution
- Architecture
- Interfaces
- Channel Bandwidths
- Frequency and Time Division Duplexing
- Operating Bands
- Bearer Types
- Radio Resource Control States
- Signalling Radio Bearers
- Quality of Service
- Mobility Management States
- Connection Management States
- 3GPP Specifications
- LTE Advanced
LTE, or Long-Term Evolution
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LTE (Long-Term Evolution) is a technology used to provide high-speed internet to mobile devices like phones and tablets. It’s part of 4G networks, allowing faster downloads, smoother streaming, and more reliable connections compared to older systems.
LTE (Long-Term Evolution) is like a super-fast highway for the internet on your phone. It helps you watch videos, play games, or browse the web without waiting too long. It’s much faster than the older, slower internet roads.
LTE as a super-fast highway within a city
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LTE, or Long-Term Evolution 
Architecture
Architecture in LTE refers to the way the entire LTE network is structured. This includes all the different parts that work together, like the base stations (cell towers) and the core network, ensuring that your device stays connected to the internet.
Architecture is the way this internet highway system is designed, like how a city’s roads are planned. Everything needs to be in the right place, so all the data on the network moves smoothly between your phone and the internet.
LTE architecture as a well-designed city road network.
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Interfaces
Interfaces are the connections between different parts of the LTE system. They allow the base stations and the core network to communicate and share data, helping to move information from one point to another efficiently.
Interfaces are like the intersections or connections between different roads. They let different parts of the network, like your phone and the network towers, communicate with each other and exchange information easily.
LTE interfaces as road intersections or connections in a city, where different parts of the network communicate efficiently.
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Channel Bandwidths
Channel Bandwidths are the widths of the pathways that data travels on. The larger the bandwidth, the more data can move at once, meaning faster internet speeds and less congestion on the network.
Channel Bandwidths are like the number of lanes on a road. More lanes (or bandwidth) means more cars (or data) can travel at the same time, making everything faster. If there are fewer lanes, the road can get crowded and slow down.
LTE channel bandwidths as lanes on a road, where more lanes represent higher bandwidth allowing smoother data flow.
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Frequency and Time Division Duplexing
LTE uses two methods to organize data flow: Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD). FDD uses separate frequencies for sending and receiving data, while TDD uses the same frequency but at different times.
In a simple way, FDD is like having separate lanes for incoming and outgoing traffic, while TDD uses the same lane but changes direction at different times.
LTE Frequency and Time Division Duplexing using the analogy of separate and shared lanes.
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Operating Bands
Operating bands are specific frequency ranges where LTE operates, which are allocated based on region and spectrum availability. These bands range from low-frequency bands (e.g., 700 MHz) to higher frequencies (e.g., 2.6 GHz), impacting coverage and capacity.
The operating bands are like the different neighborhoods where the city’s roads are built. Some neighborhoods are close together and busy (high frequencies), while others are more spread out (low frequencies), affecting how far and fast data can travel.
LTE Operating Bands as different neighborhoods, with some closer and busier and others more spread out.
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Bearer Types
In LTE, bearers refer to the data paths between the network and the user device. There are two main types: default bearers, which provide basic internet access, and dedicated bearers, which support specific services requiring higher performance.
Bearers are like buses or taxis in the city. Some are regular buses that carry all passengers (default bearers), and others are special taxis for specific people who need faster or more secure rides (dedicated bearers), like an express service for important data.
LTE bearer types, using the analogy of buses (default bearers) and taxis (dedicated bearers).
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Radio Resource Control States
LTE devices transition between different Radio Resource Control (RRC) states based on their activity. Key states include RRC_IDLE, where the device saves power, and RRC_CONNECTED, where active data transmission occurs.
These states are like traffic lights or stop signs. Sometimes, the traffic lights are green, and data moves fast (RRC_CONNECTED). Other times, they’re red or yellow, meaning the data is waiting or stopped to save energy (RRC_IDLE).
LTE Radio Resource Control (RRC) states as using traffic lights and stop signs to represent data flow.
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Signalling Radio Bearers
Signaling radio bearers (SRB) are specialized data channels used to carry critical control information between the user device and the network. These bearers manage tasks like handovers, connection setup, and quality of service (QoS) management.
Think of these as the walkie-talkies used by city traffic managers. They don’t carry passengers but help the city’s traffic controllers communicate and manage the flow of data, making sure everything is in order and moving properly.
LTE Signaling Radio Bearers (SRB) using the analogy of walkie-talkies for traffic managers.
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Quality of Service
QoS in LTE prioritizes traffic based on the type of service, ensuring that critical applications like voice or video calls receive the necessary bandwidth and low latency to function smoothly, while less critical data is deprioritized.
QoS is like giving VIP lanes to certain cars on the road. Important cars, like ambulances (your video calls or gaming), get priority and can go faster, while other cars (like regular browsing) have to wait their turn.
LTE Quality of Service (QoS) using the analogy of VIP lanes for prioritized data.
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Mobility Management States
LTE is a mobile network, and naturally, users can move. Therefore, mechanisms are needed to manage this mobility - managing devices in different states. Mobility management states, such as IDLE and CONNECTED, help the network track devices, allowing efficient handovers and maintaining the connection as users move between cells.
This is like figuring out whether people in the city are at home relaxing (IDLE) or driving around (CONNECTED). The city keeps track of where you are and what you’re doing to make sure everything works smoothly as you move.
LTE Mobility Management States, using the analogy of people at home (IDLE) and driving around (CONNECTED).
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Connection Management States
In addition to user mobility states, connections also need management. Connection Management States make sure your phone stays connected to the network, or goes to sleep to save battery when it’s not being used. It can wake back up whenever it needs to send or receive data again. These states govern how devices establish, maintain, or release connections. Examples are Attach (initial connection) and Detach (disconnect).
Connection Management States are like when your phone either stays on the road, pulls over to rest, or wakes up again when it needs to keep driving. These states help your phone save battery when it’s not actively being used.
LTE Connection Management States, using the analogy of a phone either driving, pulling over to rest, or waking up again.
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3GPP Specifications
As we’ve seen, LTE is standardized. This standardization is defined by the 3rd Generation Partnership Project (3GPP), which continuously updates and improves LTE (and other mobile) technology through specifications - comprehensive sets of standards and rules governing how LTE operates - ensuring interoperability between equipment from different vendors and across networks worldwide.
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It’s like a big rulebook everyone follows to make LTE work seamlessly.
LTE Advanced
LTE Advanced is an enhancement of the standard LTE network, offering even higher data speeds and improved capacity. It introduces features like carrier aggregation, allowing operators to combine multiple frequency bands for faster and more reliable data transmission.
LTE Advanced is like the city getting even better, adding more lanes to the roads and building shortcuts, so data (or cars) can travel even faster and more smoothly, especially during rush hour!
LTE Advanced, with the city adding more lanes and shortcuts to improve traffic flow (data).
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