As 5G technology continues to roll out, spectrum resources have become a key factor affecting network performance and coverage. Different frequency bands have distinct propagation characteristics and coverage capabilities, with 3500MHz and 2100MHz being two common 5G band choices. But why does the 3500MHz band generally provide weaker coverage than the 2100MHz band? This difference is closely related to the physical properties of radio waves and their propagation characteristics. In this article, we'll analyze the issue from several angles.

1. The Impact of Frequency on Propagation Distance

Higher frequencies result in weaker signal propagation. In other words, 3500MHz signals have shorter wavelengths compared to 2100MHz signals, and higher frequency signals experience more significant attenuation during transmission. Therefore, at the same transmission power, the 3500MHz signal will cover a shorter distance than the 2100MHz signal. Signal attenuation is not limited to free-space loss but also includes interference from obstacles like buildings, trees, and other structures.

    ● 3500MHz Band: Higher frequency signals have poorer penetration capabilities, particularly in urban environments, where they can be absorbed or reflected by buildings and walls, resulting in smaller coverage areas.

    ● 2100MHz Band: Lower frequency signals have better penetration capabilities, allowing them to pass through walls and other obstacles more effectively, which increases the signal's range and coverage.

2. Differences in Signal Attenuation Between High and Low Frequencies

According to the physical principles of radio wave propagation, signal frequency is directly related to its rate of attenuation. In other words, higher frequencies experience greater attenuation. Additionally, high-frequency signals are more susceptible to weather-related factors, such as humidity, rain, and snow. As a result, the 3500MHz signal tends to suffer more severe attenuation under adverse weather conditions compared to the 2100MHz signal.

3. Balancing Coverage and Capacity

While the 3500MHz band has weaker coverage, its high-frequency characteristics allow it to deliver higher data transfer speeds. Higher frequency bands provide more available spectrum, supporting more simultaneous users and faster data transfer rates. For this reason, 5G networks typically use the 3500MHz band to deliver high-speed data services, but due to its limited coverage, more base stations are needed to fill coverage gaps.

On the other hand, the 2100MHz band offers broader coverage but slower data speeds, making it ideal for providing stable signal coverage over a large area. To achieve a balance between coverage and capacity, 5G networks often combine different frequency bands. For example, low-frequency bands are used for wide coverage, while high-frequency bands deliver fast data services.

4. Base Station Density and Coverage Optimization

Due to the smaller coverage area of the 3500MHz band, it typically requires a denser deployment of base stations to ensure optimal coverage. This means that building a network using the 3500MHz band is more costly and requires a larger infrastructure investment. In contrast, the 2100MHz band, with its broader coverage, requires fewer base stations to achieve larger coverage areas.

5. 5G Frequency Band Allocation Strategy

To fully leverage 5G's potential, operators typically adopt a spectrum allocation strategy based on the unique characteristics of different frequency bands. 5G networks often use a combination of low, mid, and high-frequency bands to provide both broad coverage and high-speed services.

    ● Low-frequency bands (e.g., 700MHz, 800MHz): Provide wide coverage and strong penetration, suitable for rural areas and the outskirts of cities.

    ● Mid-frequency bands (e.g., 2100MHz, 3500MHz): Offer a good balance of coverage and high-speed data transfer, ideal for urban centers.

    ● High-frequency bands (e.g., millimeter-wave): Used in high-density and hotspot areas to deliver ultra-fast communication speeds.

6. Conclusion

In summary, the performance differences between the 3500MHz and 2100MHz bands in 5G networks stem primarily from the impact of frequency on radio wave propagation. While the 3500MHz band offers higher bandwidth and faster data rates, its signal has a shorter range and poorer penetration, leading to smaller coverage areas compared to the 2100MHz band. To optimize network performance, 5G networks typically use a combination of low, mid, and high-frequency resources, each serving a specific purpose in terms of coverage and data speed.

In real-world 5G network deployment, operators choose the most appropriate frequency bands based on geographical factors, user demands, and available spectrum resources to ensure a balanced approach to coverage and data rates.