Mid-Band Spectrum (e.g., 1-6 GHz)

[taniyabithi]

Low-Band Spectrum (e.g., below 1 GHz): These frequencies travel very long distances and penetrate buildings well. They are excellent for providing wide-area coverage, especially in rural areas. However, they have less capacity (lower bandwidth).
High-Band Spectrum (e.g., above 24 GHz, or "mmWave"): These frequencies offer enormous capacity and blazing-fast speeds. The downside is their very short range and poor penetration of obstacles like walls or even leaves.
The Journey of a Data Packet: A Step-by-Step Guide
Let's trace the path of your request when you tap a link to watch a cat video on YouTube.

Request Initiation: Your phone's browser creates a data request. The phone's operating system passes this request to the modem.
Modulation and Transmission: The modem converts the digital data (ones and zeros) of your request into a complex radio signal. This process is called modulation. It uses techniques like QAM (Quadrature phone number database Amplitude Modulation) to pack as much data as possible onto the radio wave. A common modern technique is 256−QAM, which can encode 8 bits of data per symbol. The phone's antenna then broadcasts this radio signal.
Reception at the Cell Tower: The nearest cell tower with the strongest signal from your carrier receives your radio signal.
Demodulation and Backhaul: The tower's equipment demodulates the signal, converting it back into digital data. It then sends this data packet through the high-speed fiber optic backhaul network toward the core network.
Navigating the Core Network: The data packet arrives at a Mobile Switching Center (MSC) and then a gateway router (like a Packet Data Network Gateway or PGW). This gateway authenticates that you are a valid subscriber and checks your data plan.
Reaching the Public Internet: The gateway acts as the bridge to the public internet. It routes your request to the correct destination—in this case, one of YouTube's (Google's) servers.
The Server Responds: The YouTube server receives your request, finds the cat video data, breaks it into small packets, and sends them back addressed to your phone's unique IP address.
The Return Journey: These packets travel back across the internet, through your carrier's core network, over the backhaul to your cell tower.
Final Transmission: The cell tower modulates the video data onto radio waves and beams them to your phone.
Display: Your phone's modem receives these waves, demodulates them back into the original data packets, reassembles them in the correct order, and your browser displays the streaming video.
This entire round-trip happens in milliseconds. The time it takes is called latency.