In this blog post, we’ll examine the principles behind network overload that occurs when users suddenly flock to a specific area, and how load balancing technology works to resolve this issue.
You’ve likely been to places where huge crowds gather in specific areas—such as on days when university entrance exams are held, during concerts, or around Gangnam Station when English language classes are letting out. At such times, you may have experienced your cell phone not working properly or data connectivity being spotty. In this post, I’ll briefly explain how this phenomenon occurs and how it can be resolved.
First, let’s examine the causes of this issue. It’s easy to understand by thinking about a common everyday situation. Many people use the subway as public transportation. Normally, when you take the subway, you enter through a convenient entrance. In most cases, there are many entrances in the middle cars—excluding the first and last cars—and many people use those middle cars. But have you ever taken the subway at Gangnam Station on a day when a major baseball game is being played?
When there are large crowds, you’ll notice that people don’t just board the middle cars; instead, they line up evenly across the front and rear cars to board all at once. Load balancing operates on a principle similar to this situation. If the number of mobile phone users remains within the capacity of a typical cell tower, a single tower can handle the communications. However, if users suddenly become concentrated in one area, it becomes difficult for a single tower to process all the data traffic generated there, which can lead to an overload. In such cases, there are two main ways to address the issue. The first is to increase the processing capacity of the cell tower itself so it can accommodate more users, and the second is to utilize nearby cell towers. The second approach—similar to how subway passengers are evenly distributed across the front and rear cars—involves distributing some users from an overloaded base station to nearby base stations to ensure smooth handling of communication traffic. This technology is called load balancing. In actual mobile communication networks, load balancing is performed by using methods such as handover, based on load information from surrounding cells, to move some users from a congested cell to another cell.
For convenience, let’s call the area marked in blue “A” and the area marked in orange “B.” Area A represents an area currently crowded with people, while Area B represents a nearby area with relatively fewer people. In such cases, the base station in Area A generates a large volume of data traffic, making it difficult to handle the entire load at once. Therefore, by utilizing the capacity of the relatively less crowded Area B to process some of the users previously served by the base station in Area A, more users can simultaneously use communication services smoothly.
Now, let’s examine how load balancing technology can be applied.
With the advancement of mobile phone and internet technologies, it has become possible to access high-speed internet through mobile networks such as LTE and LTE-A. While load balancing for simple voice calls or text messages was important in the past, the importance of technologies that efficiently distribute data traffic is growing as more users utilize high-data-volume services such as video streaming. In particular, mobility-based load balancing—which evenly distributes the load across cells and redirects some traffic from congested cells to other cells—is being utilized even in today’s 5G mobile networks.
To illustrate with an example, consider a user located in an area where regions A and B overlap. If this user requests a large amount of data and relies solely on a base station in region A, the load on that base station will increase, potentially disrupting smooth data transmission. In such cases, the network can move the user to a cell in region B or apply a separate technology that efficiently utilizes communication resources across both cells, thereby enabling more efficient use of the network’s overall resources. However, the method in which a single user simultaneously receives data from base stations in both Area A and Area B should be distinguished from load balancing in the general sense. In LTE-Advanced, the technology that combines multiple frequency bands for a single user to increase data transmission speeds is defined as a separate technology, such as Carrier Aggregation.
Therefore, load balancing is not merely the act of distributing users across multiple base stations; rather, it can be viewed as a technology that ensures a more balanced utilization of the network’s overall resources by taking into account the communication load and wireless environment of each cell. By moving some users from a congested base station to a nearby base station, the load concentrated on that specific base station can be reduced, and by utilizing the spare resources of surrounding base stations, overall communication quality and network capacity can be managed efficiently.
