This topic presents in a very simplified way all the main concepts that should be understood by those who know LTE.
LTE Uplink Transport Channels
LTE Uplink Transport Channels are pathways used by devices to communicate with the network. They include the UL-SCH, which carries large amounts of data like uploads, and the RACH, which is used to initiate connections. These channels help ensure that messages and data are sent efficiently and effectively.
In the LTE city, the Uplink Transport Channels are like the roads your car uses to travel. The UL-SCH is the busy highway that carries large trucks loaded with big packages, like photos and videos, to their destination (the network). The RACH, on the other hand, is like raising your hand to get the attention of a busy traffic officer when you want to enter the highway. Together, they keep the flow of information moving smoothly between your device and the network!
LTE Uplink Transport Channels with roads, trucks (representing data) and the RACH initiation process (connection initiation).
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UL-SCH
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The UL-SCH (Uplink Shared Channel) is the main channel used for sending large amounts of data from your device to the network. Think of it as a busy highway where cars (data) travel to reach their destination (the network). When you’re uploading photos, videos, or sending messages, the UL-SCH is the channel that carries all this information. It allows multiple devices to share the same road, making sure everyone gets their data to the network efficiently, just like cars using different lanes to avoid traffic. In LTE Uplink, the UL-SCH is the main channel for sending user data from your device to the network. It’s the backbone of data communication, ensuring that your information reaches its destination efficiently and reliably.
The UL-SCH is like a busy highway where cars (data) travel to reach the city center (the network). When your device needs to send large files, such as photos or videos, it takes this highway for a fast ride. Just as many cars can share the road without colliding, multiple devices can use the UL-SCH simultaneously, ensuring that everyone can send their data without delays. This highway is crucial because it guarantees that everything you send gets to its destination smoothly and quickly!
LTE Uplink UL-SCH as a busy highway with cars (data) traveling to the network.
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LTE UL-SCH 
RACH
The RACH (Random Access Channel) is like the initial knock on the door when your device wants to connect to the network. It’s used to request access and establish a communication link. Imagine you’re at a big event and you want to get the attention of the event organizers; you raise your hand (RACH) to let them know you need help. When your device uses the RACH, it’s signaling to the network that it wants to send data or needs to establish a connection. This channel is crucial for getting the conversation started between your device and the network. Alternatively, it is like the entrance gate to the city. When your device wants to start a conversation with the network, it uses the RACH to make the initial connection. It’s like knocking on the door or pressing the doorbell to get the network’s attention, allowing your device to join and communicate in the LTE network smoothly.
The RACH is like raising your hand to get someone’s attention in a crowded room. When your device wants to connect to the network, it sends a quick signal through the RACH, just like saying, “Excuse me, I need help!” This channel allows your device to grab the network’s attention so it can begin communicating. It’s the first step for your device to send messages and stay connected to the city (the network). Alternatively, you can think of the RACH as the city’s welcome gate. When your phone wants to start a conversation with the network, it uses the RACH to knock on the door and say, “Hey, can I come in?” It’s the initial step to joining the city’s conversation, ensuring your phone can start sending and receiving information.
LTE Uplink RACH as someone raising their hand to get the network’s attention.
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That’s it. 
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Continue reading: Roadmap to LTE - Uplink Channel Type Mappings
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