In this blog post, we’ll take a closer look at KT’s broadband LTE service—with the text edited and proofread for clarity—to help you understand the significance of frequencies and bandwidth in telecommunications.
In August 2013, South Korea’s three major mobile carriers—SK Telecom, KT, and LG Uplus—engaged in fierce competition to secure frequency bands for their LTE services. Over 2 trillion won was invested in the frequency auction at the time, and the media reported that, after ten days of intense competition, KT succeeded in securing its desired frequency bands. A look at the auction results from that time helps explain why this competition took place.
To someone unfamiliar with the importance of frequencies and bandwidth in telecommunications, the trillions of won mentioned in the auction results—along with terms like “C2 block” and “D2 block”—might seem like nothing more than a simple battle for money. However, to understand the context of this competition, we first need to examine what telecommunications, frequencies, and bandwidth actually are.
Today, wireless communication is a technology that transmits information by sending radio waves through the air. In that sense, humans can use “shouting” as the most primitive means of communication. However, since shouting is greatly affected by distance and the environment, it is difficult to transmit information over long distances. To overcome this, the voice must be converted into an electrical signal for transmission, and frequency is a key concept in this process.
Frequency refers to the number of times a signal oscillates in one second. For example, 2.6 GHz means the signal oscillates 2.6 billion times per second. The 2.6 GHz signal used in cell phones is not the human voice itself. Since the frequency range of sounds audible to humans is generally between about 20 Hz and 20 kHz, voice signals are not transmitted as-is but are instead carried on radio waves with much higher frequencies. This process is called “modulation.”
Modulation—the process of changing the frequency of the original signal—offers a very important advantage. When multiple signals are transmitted at different frequencies, they do not interfere with one another, enabling stable simultaneous communication. In other words, signals with different frequencies do not mix together even when transmitted simultaneously in the same space.
This principle is easy to understand in everyday life. Consider Park Kal-rin, who conducted a choir on the KBS2 program ‘A Man’s Qualifications’. Possessing perfect pitch, she was able to accurately identify choir members whose pitch was slightly off, even when numerous people were singing simultaneously. The principle behind this phenomenon is that sounds of different pitches have different frequencies, allowing them to be distinguished. Understanding these concepts of frequency and modulation naturally leads to an understanding of bandwidth, which is at the heart of this competition for frequencies.
The simplest analogy for explaining bandwidth is the lanes on a highway. A wide bandwidth is similar to having more lanes on a highway, allowing more vehicles to pass through at the same time. Here, the volume of traffic corresponds to the amount of data being transmitted. When considered alongside the fact that frequencies do not interfere with one another, bandwidth can be understood as the range of frequencies available for communication. In other words, the wider the bandwidth, the broader the range of frequencies that can be used simultaneously, allowing for the efficient transmission of more data through parallel transmission.
Since the D2 block secured by KT at the time was adjacent to the frequency band it was already using, the company was able to offer a “broadband LTE” service that utilized the two bands as a single, wide band. This was the primary reason KT viewed the results of the spectrum auction so positively at the time.
However, there was a misconception at the time that Broadband LTE was significantly faster than LTE-A. In reality, the two technologies are fundamentally different. LTE-A achieves higher transmission performance by simultaneously utilizing multiple frequency bands, whereas Broadband LTE enhances data transmission efficiency by securing a wide, contiguous frequency band. Although the two technologies differ in their implementation methods, from the users’ perspective at the time, both offered improved communication quality compared to standard LTE.
Ultimately, the broadband spectrum secured by KT served as a crucial foundation that enabled existing LTE users to access enhanced services. This was why KT and its users viewed the results of the spectrum auction so positively at the time, and it also served as an example demonstrating that spectrum and bandwidth are key factors in determining the quality of mobile communication services.
