Overcoming Cellular and Wi-Fi Coexistent Interference for Cellular Gateways

JUNE, 2024

The rapid evolution of cellular communication and transmission is driven by the increasing demand for higher data rates and reduced buffering times. As 5G technology emerges, promising unprecedented performance levels, the rush to deploy 5G handsets has overshadowed potential Wi-Fi coexistence issues. Despite Wi-Fi and 5G cellular technologies being complementary, their effective coexistence is crucial for enhancing the end-user experience. With Wi-Fi usage accounting for up to 92% of total smartphone data usage, the integration of both Wi-Fi and 5G spectrums can significantly improve data rates and reduce latency.

Wi-Fi, particularly in the 5 GHz band (802.11a/n/ac/ax), extends beyond the traditional 2.4 GHz spectrum, offering additional range and higher data rates. Combining this with the high speeds of 5G can result in substantial performance improvements. However, the proximity of cellular and Wi-Fi channels in the 2.4 GHz and 5 GHz spectrums poses significant interference threats due to transmit (Tx) leakage and Adjacent Channel Leakage Ratio (ACLR). For instance, the 2.4 GHz Wi-Fi channel is adjacent to the n41, n40, and n7 cellular spectrums, while the n79 band is adjacent to the 5 GHz Wi-Fi channel. Without appropriate filtering, this interference can drastically impact data rates and even cause hardware damage from high power signals reaching receive (Rx) paths.

Challenges and Solutions

Currently, there are no requirements from carriers or Original Equipment Manufacturers (OEMs) for n79 coexistence with 5 GHz Wi-Fi channels. This oversight has led to Radio Frequency Front-End (RFFE) implementations that do not account for this coexistence, resulting in significant desensitization of 5 GHz Wi-Fi channels.

To address these challenges, external high-rejection filters and antenna plexers can be utilized. These components offer rejection levels up to 25-35 dB, significantly improving desensitization and enabling effective coexistence of Wi-Fi and cellular spectrums. By incorporating these hardware solutions, devices can achieve higher throughput and faster data rates. Additionally, hardware filtering is platform-agnostic, allowing OEMs to use any transceiver platform, and it supports hotspot or external-AP modes. Crucially, this approach is future-proof, accommodating new band combinations as 5G evolves.

The implementation of hardware-based filtering solutions opens up potential application scenarios in NR/LAN interworking and NR/WLAN dual connectivity, currently discussed in the 3rd Generation Partnership Project (3GPP). These advanced capabilities would allow user equipment (UE) to leverage both Wi-Fi and cellular networks more effectively, further enhancing data rates and user experience.

Overcoming cellular and Wi-Fi coexistent interference in cellular gateways is critical for ensuring reliable and efficient wireless communication. As technology advances, the integration of cognitive radio, 5G, and AI-driven solutions will further revolutionize interference management, paving the way for a more connected and interference-free future. Emplus, as an OEM/ODM service provider, is at the forefront of this innovation, offering high-quality 5G gateways and Wi-Fi solutions that embody these advanced technologies. As 5G technology continues to evolve, ensuring effective coexistence with Wi-Fi will be critical for delivering the optimal user experience.