The same smartphone, on the same network, can download at hundreds of megabits per second in the town square and struggle to load a page in the basement. Next to the "5G" icon the connection can be slower than a strong 4G one. To understand why, you need to look beyond the label and at how frequencies, cells and technologies work.
The fundamental rule of frequencies
Mobile networks transmit on several frequency bands, and each band has a precise trade-off:
- low frequencies (below 1 GHz): cover long distances and pass well through walls and floors, but offer little capacity;
- mid frequencies (roughly between 1 and 6 GHz): a good balance between coverage and speed;
- very high frequencies, known as millimetre waves: enormous capacity, but short range and trouble even with light obstacles such as a window or the human body.
In practice, the higher the frequency, the faster the connection can be and the shorter the useful distance. An operator combines different bands to get both widespread coverage and speed in crowded areas.
4G LTE: the foundation that holds everything up
4G is still the backbone of mobile networks. It uses several bands at once thanks to carrier aggregation: the phone connects to two, three or more frequencies at the same time and adds up the capacity. That is why two 4G phones can get very different speeds in the same spot: it depends on how many bands and which combinations they support.
4G also carries voice calls with VoLTE, which offers better audio quality and keeps the data connection active during a call.
5G: what really changes
5G introduces a new radio interface, called NR (New Radio), which uses spectrum more efficiently and can handle many more devices per cell with lower latency. But the benefit depends on the band in use:
| 5G on... | Coverage | Typical speed | Where you find it |
|---|---|---|---|
| low bands | wide, indoors too | similar to good 4G | large areas, interiors |
| mid bands | good | much faster than 4G | cities, covered areas |
| millimetre waves | a few to tens of metres | very high | stadiums, specific spots |
A "5G" icon on a low band can therefore deliver performance comparable to well-aggregated 4G. The leap is felt mainly on mid bands.
NSA and SA
Many 5G networks started in non-standalone (NSA) mode: the phone relies on a 4G connection for control and uses 5G to boost data speed. In standalone (SA) mode the network core is 5G too, enabling lower latency and advanced features. For ordinary users the most visible difference is often in power consumption and connection stability, which vary with the operator's implementation and the phone model.
Why speed varies so much
The main factors are:
- distance from the antenna: the signal weakens and the phone switches to more robust but slower modulations;
- obstacles: reinforced concrete walls, low-emissivity glass and basements strongly attenuate mid and high frequencies;
- cell congestion: a cell's capacity is shared among all connected users; in the evening or during an event individual speed drops;
- phone compatibility: supported bands and combinations vary widely between models, even from the same manufacturer;
- tariff plan: some plans cap maximum speed or do not include 5G.
How to read your phone's signal
The bars are a rough indicator and each manufacturer calculates them its own way. Many phones show more precise values in status menus or hidden settings:
- RSRP, the received signal power, expressed in dBm: values closer to zero mean a stronger signal;
- SINR or RSRQ, the signal quality relative to noise and interference.
A strong but noisy signal can perform worse than a weaker but clean one. Noting these values in different parts of the house helps you see where the phone works best.
Does 5G use more battery?
It depends. In early NSA deployments the phone had to keep two connections active and power use was higher. With newer chips and more mature networks the difference has narrowed. If battery life is an issue, many phones let you use 5G only when needed, falling back to 4G for light tasks.
In short
- Low frequencies cover more ground; high frequencies are faster but reach less far.
- 4G with carrier aggregation remains the foundation of mobile networks and VoLTE calls.
- 5G on low bands resembles 4G; the real leap comes on mid bands.
- Distance, obstacles, congestion and phone model explain most speed differences.
- RSRP and SINR say far more than the bars about real signal quality.
