What are the co-existence requirements between 5G NR and adjacent band satellite services?
5G-Satellite Coexistence
The C-band coexistence challenge is one of the most significant spectrum engineering problems in 5G deployment, requiring coordination between terrestrial mobile operators and satellite service providers.
- Performance verification: confirm specifications against the application requirements before finalizing the design
- Environmental factors: temperature range, humidity, and vibration affect long-term reliability and parameter drift
- Cost vs. performance: evaluate whether the application demands premium components or standard commercial grades
- Interface compatibility: verify impedance, connector type, and mechanical form factor match the system architecture
Frequently Asked Questions
How much do the C-band filters cost?
The C-band cavity filter for a 5G macro base station costs $50-150 per filter (8-element cavity design). For a 64T64R massive MIMO system: only 1-2 filters are needed (shared across multiple elements or placed after the PA combiner). If individual element filtering is required: $50-150 × 64 = $3,200-9,600, which is significant. This is why shared filtering architectures are preferred for massive MIMO.
Can software-defined filtering replace the cavity filter?
Partially. Digital filtering (DPD + crest factor reduction) can reduce the out-of-band emissions by 10-15 dB. But: the PA still generates analog emissions that are above the -13 dBm/MHz OOBE limit. A physical analog filter is still required for the final stage of rejection. The combination: DPD provides 10-15 dB of OOBE reduction + analog filter provides 40-50 dB = total 50-65 dB rejection. Without the analog filter, the OOBE limit cannot be met.
What about interference from satellite to 5G?
Satellite downlink signals can interfere with 5G NR reception on adjacent frequencies. But: satellite power flux density at the ground is very low (-120 to -140 dBm/m² in the 3.7-4.2 GHz band). The 5G base station receiver is relatively immune to this level (the sensitivity is approximately -96 dBm; the satellite signal is well below the noise floor). The interference is primarily one-directional: 5G → satellite (5G transmit power overwhelms the satellite receive sensitivity).