Why is the LTE Band B20 missing on many Chinese smartphones?

Chinese devices are typically characterized by the fact that their specs don’t include Band B20, and that’s why the type of internet connection available is also limited. Why is that?

Band B20: What is it?

LTE Band 20, also known as the B20 band or 800 MHz band, is a frequency band used for mobile communication in the LTE network (i.e., Long-Term Evolution). And LTE itself is a fourth-generation mobile technology (4G) that offers faster data transfer and better network coverage than its previous 3G and 2G.

The B20 band operates in the 832 – 862 MHz frequency range for uplink (UL) and 791 – 821 MHz for downlink (DL), with a total bandwidth of 30 MHz. Uplink refers to sending data from the mobile device to the network, while downlink is sending data from the network to the mobile device.

Using this band offers several advantages for mobile communication. First, the low frequency of 800 MHz enables better penetration indoors and stronger outdoor coverage compared to higher frequencies.

And secondly, it provides flexible bandwidth in the range of 1,4 MHz to 20 MHz, allowing mobile operators to adjust network capacity and power as needed.

TDD and FDD duplex in LTE Band 20

Mobile communication offers two main technologies for duplex data transmission: time-division duplex (TDD) and frequency-division duplex (FDD). LTE Band B20 supports both, enabling efficient use of the available spectrum.

TDD uses a single frequency band for uplink and downlink, with transmission taking place in consecutive time slots. That means uplink and downlink are broadcast alternately on the same frequency band. TDD duplex is especially useful in scenarios where traffic is uneven in both directions. Time segments can then be allocated dynamically as needed.

FDD uses two separate frequency bands for uplink and downlink, with transmission happening simultaneously on both bands. That means uplink and downlink are transmitted on different frequency bands, enabling continuous two-way communication under evenly balanced traffic.

In LTE Band B20, both TDD and FDD are used for efficient use of the available spectrum. The choice between TDD and FDD depends on various factors, including network topology, traffic patterns, and regulatory requirements.

Difference between Europe and China

In Europe, the B20 band is a very important frequency for mobile communication. It operates in the 800 MHz range and is often used in rural areas. There, mobile cells have to cover a slightly larger area. The lower 800 MHz frequency provides a longer reach and better penetration into the depths of buildings. In China, on the other hand, other LTE bands are preferred, which operate at higher frequencies and enable higher data transfer speeds.

Chinese smartphone manufacturers such as Xiaomi, Oppo, Vivo, Realme, Redmi and ZTE focus on the domestic market. And they tailor their devices to match, including LTE bands typical for China.

Since the B20 band is not used much in China and every frequency also comes with additional licensing fees, many manufacturers see no reason to support this band in their devices. However, this can lead to issues when these devices, originally “Chinese”, are used in Europe. The problem may occur especially in rural areas, where this band is used more often.

Lack of support for Band B20 can lead to limited connectivity and slower data transfer speeds. However, in urban areas where other LTE bands are available, this shouldn’t be too big of an issue. In addition, some Chinese smartphone manufacturers offer special global versions of their devices that support Band B20 and other LTE bands used in Europe.

This is how it compares to other bands

B20 spectrum is just one of many LTE bands used in mobile communication. Each band has its own frequencies, bandwidth, and applications. Below you’ll find their comparison:

• LTE Band 1 (2100 MHz) – Asia + Europe, a good mix of coverage and capacity. Prone to interference and weaker in-building coverage than B20
• LTE Band 3 (1800 MHz) – Worldwide, good performance in urban and populated areas. But it has shorter range and weaker in-building coverage than B20
• LTE Band 7 (2600 MHz) – Asia + Europe, high data capacity and transmission speed. Just like Band 3, it has shorter range and weaker in-building coverage than B20
• LTE Band 28 (700 MHz) – Some countries in Asia and South America, excellent range and strong penetration into buildings. However, it has lower capacity and speed than B20

Compared to these bands, Band B20 offers a very good combination of maximum range, capacity, and also indoor penetration.

What’s the future of LTE Band B20?

B20 is expected to play an important role in mobile communication for years to come. Despite the arrival of 5G, LTE will still be a very important type of connection. Especially in low-population-density areas and indoors, where higher-frequency bands are less effective.

This band is currently being replaced in many areas by 1, 3, 7 or 8. Higher data transmission speed over a smaller area means that in metropolitan areas you’ll get higher speeds and better reception. However, it’s important to know that it is precisely LTE that is spreading the most at the moment. And that comes at the expense of the older 3G, which is already being removed or these towers are being modernized to 4G in many countries.

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