March 4, 2026

Customer Premises Equipment (CPE) serves as the critical gateway between end users and the mobile network. In modern 5G and IoT deployments, these devices are expected to operate continuously and reliably in outdoor environments where conditions are anything but gentle.

As such, performance degradation is not an option when networks depend on these devices to maintain connectivity. Yet, maintaining consistent throughput becomes challenging when thermal constraints are introduced. Specifically, when modems and power amplifiers overheat, performance suffers.

Understanding why this happens, how to recognize it, and what solutions exist is vital for delivering reliable connectivity.

Causes of overheating

One of the primary challenges in outdoor CPE design is the requirement for fully sealed enclosures. The devices must protect sensitive internal components from moisture and dust. That means that ventilation openings are completely out of the question. The tradeoff to enable weather protection is a sealed environment where heat has no natural path to escape.

Inside these sealed units, two components generate the most heat during operation: The modem (MDM), processes data and manages communications. The power amplifier, or PA, boosts signals for transmission. Both are essential for performance, and both generate significant heat when working under load.

Symptoms of overheating

The effects of overheating are visible through device performance. When engineers conduct stress tests on CPE units, they observe that when modem and power amplifier temperatures exceed their derating thresholds, data throughput is reduced.

Derating thresholds are built in safety limits. Component manufacturers specify maximum temperatures for reliable operation. When those temperatures are exceeded, the system automatically reduces performance to protect the components from damage. In simple terms: the components run slower to stay safe. Users experience this as slower communication speeds.

Proven fixes

Solving overheating problems requires addressing the root causes identified through testing and analysis:

• One proven solution is to optimize the overall heat sink design. Improving the overall heat sink geometry makes the contact area of the heat sink larger, which decreases thermal resistance between the heat sink and the housing. With lower resistance, heat flows more easily from the internal components to the outer surface of the device, where it can dissipate into the surrounding air.

• Another effective measure involves reducing the thermal resistance between the heat source (modem and power amplifier) and the heat sink. Increasing the solder mask removal area on the back side of the 5G module expands the connection area between the PCBA and the heat sink. Better contact means better heat transfer. The module can now dissipate heat more effectively through the board and into the heat sink.
• These measures when correctly implemented ensure that temperatures remain below derating thresholds, consequently enabling the throughput to reach requested levels. The device performs as intended, even under continuous load in a sealed outdoor enclosure.

How Ikotek solves the CPE overheating challenge

In one of our recent 5G CPE projects, Ikotek engineers faced exactly this issue of reduced throughput caused by modem and power amplifier overheating. The unit was designed for outdoor use and had to be fully sealed, meaning ventilation openings were not an option.

Through careful testing and analysis, we identified that the temperature difference between the housing and the heat sink was too high. The root cause was an air gap between the heat sink and the plastic housing, which created high thermal resistance.

Our solution was to optimize the overall heat sink design by increasing the length of the cooling fins, making the contact area larger, and decreasing thermal resistance. We also increased the solder mask removal area on the back side of the 5G module to expand the connection between the PCBA and the heat sink, further optimizing heat dissipation.

After implementing these changes, temperatures stayed below derating thresholds, and throughput reached the requested levels.

This case study demonstrates how careful thermal optimization can eliminate throughput degradation in sealed outdoor 5G CPE, ensuring reliable operation under real world conditions.

Restoring throughput through thermal design

In conclusion: Thermal management is essential for reliable operation in real world conditions. By optimizing heat sink design, improving PCB contact, and reducing thermal resistance, it is possible to eliminate throughput degradation and deliver devices that perform as intended.

For more insights into CPE design and fixed wireless access solutions, explore these resources:

Blog:ODMs empower FWA providers to create differentiated CPE for market succes
Whitepaper: FWA White Paper
Contact:www.ikotek.com/contact