In 2008, 3GPP came up with the fourth-generation wireless cellular network specification Release 8, known as 4G, which is currently the most widespread cellular network in the world. The first 4G network was launched in 2009 in the Swedish city of Stockholm and in the Norwegian city of Oslo under the name LTE. When switching to 4G, it was necessary for the device to fully support the given specification, only changing the SIM card was not enough. Compared to previous generations, 4G has a much smaller reach, especially in terms of availability in indoor spaces, the reason being the higher frequencies on which 4G transmits.

It was known that 3G and even 4G networks would not be able to support technologies such as IoT to such a large extent, therefore 5G was approached with this idea from the beginning. However, the first 5G networks were, or still are, dependent on existing 4G networks, because even though the network broadcast on 5G frequencies, the core of the architecture was still based on 4G.[V4]

Zjednodušená architektúra 4G mobilnej bunkovej siete [V12]

Fig. V2: Simplified 4G Mobile Cellular Network Architecture [V12].

In most cases, each new generation builds on the technology of the previous one, trying to improve in every way, and 5G is no exception. The main factors that 5G tries to improve compared to its predecessor are mainly those that are beneficial for end users and that will enable the full expansion of technologies such as the Internet of Things. A comparison of selected properties can be seen in Table 1. It is important to note that different sources give different values, taking the specifications from 3GPP as the authoritative sources. The values found in the table come from several sources, taking into account sources where the same values occur repeatedly.

4G

5G

Response

10 to 50 miliseconds

Less than 5 milliseconds

Potential download speed

1 Gigabit per second

20 Gigabits per second

Base stations

Cell towers

Small cells

Maximum bandwidth

20 MHz

400 MHz

Device density

4000 devices per km2

1 million devices per km2

Spectral efficiency

~15 bps/Hz

~30 bps/Hz


In addition, 5G also brings improvements such as much longer battery life in IoT devices (up to 10 years longer than 4G), a 100-fold increase in transmission capacity over 4G, and massive IoT support.[V7] [V1] From an architectural point of view, the individual parts of the 4G network design represent various limitations in terms of expanding the possibilities supported by the 4G network, such as the static layout of the supplier's equipment, or the use of monolithic functionality in places used by previous generations of mobile networks. The biggest weaknesses include low flexibility, unnecessary complexity, and a centralized user and control plane.[V9]

Low flexibility

Despite the fact that 4G networks are much more adaptable than 3G networks, the flexibility of the given network is significantly limited. Among the biggest weaknesses are the aforementioned static layout of the supplier's equipment, the use of proprietary equipment, or the general use of expensive and proprietary equipment, the use of inflexible signaling protocols with status information, and the fact that reconfiguration and updating is possible only with intensive integration within network operators. EPC elements are controlled through a standardized interface, and it is not possible to control them through an open interface or through an API, despite the fact that the standards for these interfaces are not secret. This results in equipment upgrades often requiring replacement even though the old equipment is still suitable for most purposes, resulting in high capital costs for expanding the network and for introducing new services, and generally high operating costs for network management. [V9]

Unnecessary complexity

In terms of functionality, the 4G architecture presents a separation of user and control planes, but these planes are often combined in the network, resulting in one device carrying user plane traffic and managing control plane signaling messages, causing increased response for both plains. Another problem is the use of GTP tunnels. These tunnels are based on previous generations, and allow the connection of different types of networks of different generations, but they add to the complexity of the network and limit its scalability, which results in increased costs for mobile operators.[V9]

Centralized user and control plane

Another limit for 4G networks is the use of a centralized user and control plane. The advantage of this solution is the mobility of the 3rd network layer, and it allows the simple implementation of backward compatibility with previous generations of mobile networks, which, however, results in the need for ad hoc solutions to determine the geographic location of user devices with such accuracy that it can be used for adaptation services.[V9]