In this blog post, we’ll explore the reasons behind slow network speeds on smartphones and the wireless communication technologies that have been developed to address this issue.
We’re often referred to as living in the “smart era.” There are tens of millions of smartphones in use in South Korea alone, and new models with even better performance and a wider range of features continue to be released. The “smart” craze that began with smartphones has spread to other home appliances—from smart TVs to smart refrigerators—to the point where it’s now hard to find a product that doesn’t carry the “smart” label. Most of you reading this are likely using a smartphone as well.
However, if you’re a smartphone user, you’ve probably experienced—at least once or twice, if not quite frequently—situations where your mobile network speed slows down to the point of being inconvenient, or where the connection drops entirely. It’s frustrating for anyone to be in the middle of an important conversation on a messaging app only to have the message fail to send, with the “Sending…” icon spinning endlessly. This has led to complaints that, despite living in the “smart era,” our communication infrastructure isn’t keeping up. In this article, we’ll explore the reasons behind slow smartphone network speeds and the various technologies designed to address them.
It goes without saying that smartphones communicate via wireless networks. Wireless networks are characterized by transmitting the signals necessary for communication through space. If you’ve ever thrown a stone into a body of water, you’ll remember how the ripples it creates spread across the surface, gradually weakening until they disappear. Wireless communication signals spread through space in a similar way, gradually weakening as they travel. However, in the real three-dimensional space—as opposed to a two-dimensional plane like the surface of water—signals weaken much more rapidly. Therefore, as the distance between the cell tower and the smartphone increases, the signal strength reaching the cell tower weakens, and this is one of the causes of slow network speeds.
This issue has been recognized since the early days of wireless networks, and researchers have sought solutions by improving the base stations that receive signals. The physical area covered by a single base station is called a “cell.” By arranging these cells continuously, one cell can take over communication at the boundary where another cell’s signal weakens, thereby reducing the speed loss caused by the distance between the base station and the device. In addition, researchers introduced directional cell technology, which involves installing antennas on base stations that cover multiple directions. You’ve probably seen multiple antennas on top of a base station pointing in different directions—this is directional cell technology. With this technology, instead of a single antenna receiving signals from all directions simultaneously, each antenna receives only the signals from its designated direction, allowing even weaker signals to be received reliably.
Another characteristic of wireless networks is that collisions occur when multiple devices send signals to the base station at the same time. Think about a conversation with friends. There’s no problem when one person is speaking, but if two or more people speak at the same time, it’s hard to understand anyone clearly. In wireless networks, this phenomenon is also called a collision. In such situations, the most effective solution is to have people take turns speaking one at a time. However, this inevitably causes frustration for those waiting for their turn. The reason mobile network speeds are particularly slow in crowded places is that the base station adjusts the transmission order of devices to prevent collisions.
In a wireless network, a device first sends a short signal to the base station indicating its intention to transmit. Once the base station sends an authorization signal granting permission to transmit, the device begins sending the signal containing the actual data. If n devices attempt to send data simultaneously within a single cell, they must share the limited network resources, causing the speed available to each device to drop to 1/n or lower.
To overcome this limitation, researchers have developed alternative solutions.
Just as we can distinguish who is speaking by the characteristics of their voice even when multiple people are talking at the same time, a base station can also analyze the characteristics of the signals sent by terminals to identify which terminal sent the signal. Furthermore, the base station pre-specifies rules so that each device uses a different signal generation method. This allows the base station to separate the signals and distinguish the data from each device, even when multiple devices transmit simultaneously. Of course, since there are limits to the available signal generation rules, if the number of devices becomes very large, some may end up using the same rule. Nevertheless, this approach achieves much higher transmission efficiency than a method where only one device transmits at a time. This technology is based on QAM (Quadrature Amplitude Modulation), a type of modulation technique. In LTE, 64QAM is widely used, while more advanced modulation technologies, such as 256QAM, are widely utilized in LTE-Advanced and 5G.
Those who switched from 3G smartphones to LTE smartphones in the past likely noticed a significant improvement in network speed. Subsequently, with the commercialization of 5G beyond LTE, even faster speeds and lower latency have become available. In this way, the advancement of smartphones has gone hand in hand with the process of gradually overcoming the limitations of wireless network technology. Even now, researchers are developing new technologies to create a faster and more stable wireless communication environment. Mobile communication technology will continue to advance, evolving toward transmitting even more data faster and more reliably.
