The arrival of 5G New Radio (NR) technology brings several exciting improvements, but it also introduces challenges, especially in the context of uplink coverage. While 5G promises faster speeds and higher frequencies (like the 3.5GHz and millimeter-wave bands), the coverage per cell in 5G networks is impacted, especially when compared to existing mobile technologies like LTE. So, now let us look into Understanding 5G NR Uplink Coverage along with Smart Mobile Network Monitoring Tools, Mobile Network Drive Test Tools, Mobile Network Testing Tools and Smart LTE RF drive test tools in telecom & Cellular RF drive test equipment in detail.

One of the main issues is that as 5G uses higher frequencies, the signal penetration indoors can be significantly reduced. Higher frequency signals have a harder time passing through walls and other obstacles, leading to higher penetration losses. Despite this, 5G networks on the 3.5GHz band often utilize active antenna configurations that help maintain downlink coverage similar to the 1.8GHz LTE systems. However, uplink coverage (the signal going from the device to the network) remains more limited, even when the transmission power is shared between LTE and 5G NR.

Key Limitations of 5G NR Uplink

In 5G NR, the power class for the user equipment (UE) is set to Power Class 3, which is similar to the setup used in LTE networks. To improve the coverage, 3GPP introduced Power Class 2 for the n78 frequency band in 5G NR. However, it’s important to note that the maximum power for dual connectivity (using both LTE and 5G NR at the same time) is not clearly defined in some cases.

For instance, when the device is transmitting over both 3.5GHz and 1.8GHz uplink carriers, they are considered as coming from the same cell, meaning the transmission power remains consistent across both carriers. This can limit the overall performance of the uplink in certain situations.

The number of power amplifiers (PA) available also influences how much power can be transmitted. For early 5G devices, most only support dual transmitters for various band combinations but do not include uplink MIMO (Multiple Input, Multiple Output) capabilities, which could have otherwise improved uplink performance. Additionally, most devices are designed with a single PA for each band group, keeping the costs low but limiting coverage and performance.

Dynamic Power Sharing in 5G Devices

Devices in 5G can fall into two main categories when it comes to power-sharing between LTE and 5G NR:

• Type 1 Devices: These are capable of dynamic power-sharing, which means the device can balance power between LTE and 5G NR, ensuring that the modem can handle both technologies at once.
• Type 2 Devices: These devices cannot dynamically share power between LTE and 5G NR. They rely on separate modems for each technology, which can limit their flexibility. For these devices to operate in dual connectivity (EN-DC mode), they need to ensure that the combined power used for both LTE and 5G NR does not exceed the defined limits.

When devices are operating in single uplink mode, where they transmit using only one technology at a time, the available power for transmission is reduced by around 3dB. This reduction in power impacts both LTE and 5G NR coverage and can negatively affect the overall performance and throughput.

Extending Uplink Coverage in 5G NR

To address uplink coverage challenges in 5G, several solutions have been proposed. Some of the key options include:

1. Uplink Split Bearer: This technique splits the uplink transmission between LTE and 5G NR, effectively combining the strengths of both technologies to improve coverage.
2. Carrier Aggregation: This allows multiple frequency bands to be used together to increase both the capacity and coverage of the uplink. For instance, using lower frequency bands like 1800MHz or 700MHz alongside 3.5GHz can extend coverage.
3. Supplemental Uplink (SUL): This advanced solution enhances the uplink signal by switching to lower frequency bands when necessary, improving overall network performance.

Uplink Fallback to LTE

In some cases, vendors are promoting the idea of falling back to LTE when the 5G uplink signal is too weak. The network can detect when the uplink signal quality is poor and redirect all data transmissions to LTE, while keeping the control signaling (NR PUCCH) on the 3.5GHz band. This allows the device to maintain a connection to the 5G network while utilizing LTE for the actual data transfer.

This fallback to LTE helps extend the uplink coverage by ensuring that the device can continue transmitting data even when the 5G NR signal is too weak, especially at the edge of the coverage area.

Carrier Aggregation Across Different Bands

Another method to improve uplink coverage is through inter-band carrier aggregation. This involves combining a low-frequency band (like 1800MHz or 700MHz) with a higher-frequency band (like 3.5GHz). The lower frequency band acts as the primary cell, providing strong coverage, while the higher frequency band provides additional capacity.

By aggregating these bands, operators can ensure that devices experience better uplink performance, even in areas where the 5G signal might be weaker.

However, one challenge with this approach is that it often requires vendor-specific solutions, as each vendor might implement spectrum sharing differently. In some cases, operators may also experience a slight reduction in downlink capacity due to the sharing of resources between LTE and 5G NR.

The Supplemental Uplink Solution

The most advanced solution for extending 5G uplink coverage is the use of supplemental uplink (SUL). When the 5G uplink signal quality is poor, the device can switch to a lower frequency band (like 1800MHz or 700MHz), which provides better coverage.

With this approach, the full transmission power of the device (23dBm) can be utilized, improving coverage significantly. In cases where Massive MIMO (Multiple Input, Multiple Output) and beamforming techniques are used on the 3.5GHz band, downlink coverage tends to extend farther than uplink coverage. By decoupling the uplink and downlink, the SUL solution ensures that the device can still transmit effectively, even when the 3.5GHz uplink signal is weak.

Making the Right Decision for Uplink Coverage

Ultimately, the decision on which uplink solution to use depends on the specific needs and network architecture of each mobile operator. Some operators may opt for vendor-specific solutions, while others may prioritize flexibility and interoperability.

Each vendor is developing its own approach to address these challenges, and operators will need to evaluate the best solution for their network. Additionally, the potential to avoid vendor lock-in could also play a significant role in the decision-making process, as operators strive to build networks that are flexible and future-proof.

In summary, while 5G brings exciting advancements in network speeds and capacity, uplink coverage remains a critical challenge that must be addressed. By leveraging a combination of technologies like carrier aggregation, supplemental uplink, and dynamic power-sharing, operators can ensure better performance and coverage for 5G users.

About RantCell

RantCell is a powerful mobile app designed to simplify and enhance the process of mobile network testing, monitoring, and reporting. Whether you’re a telecom operator, service provider, or enterprise, RantCell enables you to capture real-time insights into network performance directly from smartphones and other mobile devices. With its easy-to-use interface and robust features, the platform delivers precise data on signal strength, download speeds, latency, and more, helping organizations optimize their network quality and deliver superior service to users.

RantCell provides an affordable, cloud-based solution that eliminates the need for traditional, expensive testing equipment.  It supports a wide range of use cases—from urban to rural areas, indoors or outdoors—giving you the flexibility to monitor network performance in any environment. Also read similar articles from here.