Enter search by name or keyword
Contact your local office
Enter search by name or keyword
.

 


 

Pilot Deployment of Coherent QSFP28 Transceivers on Unamplified Fiber Circuits 

Driven by a commitment to continuous innovation and intelligent investment, EPS Global partnered with Brasilnet to pilot a Coherent QSFP28 transceiver over a 60 km unamplified link in Cantagalo, a mountainous region of Rio de Janeiro. Brasilnet’s network spans remote areas of Rio de Janeiro, the Zona da Mata Mineira in Minas Gerais, and Paraná—territories marked by technical complexities, fluctuating temperatures, and aging “gray” fiber infrastructure. The objective was to validate a scalable, high-capacity upgrade that could be deployed without adding amplifiers or overhauling existing MUX and switch ports. 

 

Get Tech Advice

Executive Summary

 

In partnership with Coherent, EPS Global deployed the industry’s first QSFP28-form-factor Coherent transceiver—complete with embedded DSP and optional internal amplification—on Brasilnet’s 60 km unamplified backbone. The field trial confirmed error-free operation at an average 0.27 dB/km loss, stable thermal and power profiles even in non-air-conditioned POPs, and full compatibility with Brasilnet’s 100 GHz MUX modules and existing QSFP28 ports. This successful pilot demonstrates a clear path to a smarter, higher-capacity network without the expense of new shelters or inline amplifiers.

Challenge

 

Brasilnet’s existing backbone faced multiple hurdles that constrained capacity and reliability across its remote fiber network. The operator needed a solution that could deliver higher throughput without requiring new amplifiers, shelters, or replacement of its current MUX and switch infrastructure. 

Main Challenges:

 
  • Capacity ceiling on “gray” channels: Reliance on 1310 nm direct-detection transceivers and fixed-channel MUX cards limited per-fiber throughput and spectral efficiency. 
  • High attenuation over long spans: A 60 km circuit averaged 0.27 dB/km loss due to multiple fiber splices and aging cabling. 
  • Environmental extremes: Some POPs featured air conditioning, while others were only ventilated, exposing equipment to unregulated temperature swings. 
  • Infrastructure constraints: Budget and footprint restrictions ruled out adding inline amplifiers or swapping out existing QSFP28 ports and 100 GHz MUX gear. 

Solution


EPS Global introduced Coherent’s QSFP28 transceiver, which embeds a digital signal processor (DSP) inside the QSFP28 form factor and supports C-band tunability.

Key elements of the solution:

 
  • Coherent modulation: Each light pulse carries four dimensions of information—amplitude, polarization, phase and presence—quadrupling data density over traditional NRZ modules. 
  • Embedded DSP: Actively corrects for attenuation and dispersion, enabling reception of much weaker signals across long, unamplified spans. 
  • Backward compatibility: Plugs into existing QSFP28 ports on Brasilnet’s switches, drawing under 5 W and fitting within current power budgets. 
  • FlexTune tuning: Automatically scans and aligns to Brasilnet’s 100 GHz MUX channels, with manual fine-tuning available at the edge. 
  • Optional internal amplification: Offers nominal +0 dBm (typ. +1.5 dBm) output power and –28 dB sensitivity, extending reach without inline amps. 
     

Felipe, CTO of Brasilnet: “When we checked the equipment, it was like a light turned on, showing that there was a long path for us to work on together.” 

Implementation

 
  1. Pre-deployment configuration: EPS Global pre-loaded each module with Brasilnet’s channel plan, then ran environmental stress tests in both air-conditioned and ambient POPs to validate power and thermal behavior. 
  2. Field installation: Brasilnet engineers inserted the Coherent QSFP28 modules into existing QSFP28 ports and MUX slots, leveraging zero-touch provisioning via the FlexTune cloud controller. 
  3. Scenario testing: Over a 60 km unamplified link with multiple splices and aerial segments, the transceivers ran continuously—no manual adjustments required—even in locations without air conditioning. 
  4. Monitoring & validation: Real-time telemetry tracked optical power, temperature and current; throughout the test window, performance stayed within—or exceeded—the thresholds of comparable gray QSFP28 modules. 

Results

 
  • Link Integrity: Achieved error-free operation over 60 km at 0.27 dB/km average loss without inline amplification. 
  • Thermal Stability: Module temperatures stayed consistent from power-up to shutdown, running 2–3 °C cooler than gray QSFP28s under identical field conditions. 
  • Power Efficiency: Maintained consumption under 5 W, matching QSFP28 standards even with DSP active. 
  • Seamless Integration: Flexible channel tuning worked flawlessly on Brasilnet’s existing 100 GHz MUX infrastructure, requiring only manual fine-tuning at the POP. 
  • Strategic Growth: The trial proved that Brasilnet can scale capacity on its gray network without major hardware overhauls—fulfilling the goal to “go further” and invest intelligently. 

Brasilnet team: “We are very happy to be a partner… always seeking technological vanguard with excellence, quality and the best cost-benefit.

Future Outlook

 

Following these successful tests, Brasilnet plans to migrate its entire backbone to Coherent’s QSFP28 platform. EPS Global and Coherent will continue collaborating on advanced features—such as enhanced DSP algorithms and extended-reach variants—to further optimize network performance and cost-effectiveness.

Conclusion 

 

By combining cutting-edge Coherent modulation, embedded DSP and backward-compatible form-factor design, EPS Global and Coherent have enabled Brasilnet to leap ahead in capacity and reliability—without amplifiers or infrastructure rip-and-replace. This pilot marks a pivotal step in delivering smarter, more sustainable connectivity across Brazil’s most challenging terrains. 

Need Help?

We have local language and currency support in each of our 28 locations, ensuring you always have access to friendly customer support to deliver your hardware solutions regardless of your location.

Find your nearest eps global office

EMEA  
North America  
South America  
Asia