Project Saradana

Project SARDANA was a major European research initiative focused on advancing next-generation fibre-optic broadband networks, particularly Fibre-to-the-Home (FTTH) systems. Conducted between 2008 and 2011, it aimed to design a highly efficient, scalable, and cost-effective optical access network architecture that could deliver ultra-high-speed internet to large numbers of users across extended distances. The project represented an important step in Europe’s efforts to build future-ready communication infrastructures.

Objectives of Project SARDANA

The project’s primary goal was to create a hybrid optical network architecture combining performance, flexibility, and affordability for large-scale deployment. It sought to bridge the gap between metropolitan and access networks by developing a passive dense access system that supports thousands of users simultaneously.
Key objectives included:

1. Designing a high-capacity optical access network combining both Wavelength Division Multiplexing (WDM) and Time Division Multiplexing (TDM).
2. Achieving longer transmission reach and higher user density without extensive electronic equipment in the field.
3. Ensuring cost-effectiveness and scalability suitable for both urban and rural broadband expansion.
4. Developing a reliable and resilient topology, capable of maintaining service continuity during failures.
5. Enhancing energy efficiency and reducing operational costs by keeping the network largely passive.

Architectural Design and Technical Approach

Project SARDANA’s design philosophy centred around a ring-based passive optical architecture that combined resilience and cost efficiency.

1. Hybrid Ring-Tree Topology

• The core of the network used a ring structure, providing redundancy and fault tolerance.
• The access portion employed tree branches connecting to end users, maintaining simplicity and low deployment cost.
• This hybrid design allowed both large coverage and reliability.

2. Use of WDM and TDM Technologies

• Wavelength Division Multiplexing (WDM): Enabled simultaneous transmission of multiple optical signals at different wavelengths, multiplying total capacity.
• Time Division Multiplexing (TDM): Allocated time slots for multiple users sharing the same wavelength, ensuring efficient bandwidth utilisation.
• Combining WDM and TDM allowed SARDANA networks to achieve high data rates and dense user connectivity.

3. Passive Optical Components

• The network relied primarily on passive devices such as optical splitters, filters, and amplifiers, reducing the need for powered equipment outside central offices.
• Technologies like reflective semiconductor optical amplifiers (RSOAs) and remote fibre pumping extended network reach while maintaining low power consumption.

4. Long-Distance Transmission

• SARDANA’s architecture was designed to cover tens of kilometres, connecting both metropolitan areas and remote users through a single integrated optical infrastructure.

Project Implementation and Development

• Timeline: The project was active from January 2008 to February 2011 under the European Union’s 7th Framework Programme (FP7).
• Coordination: It was led by the Universitat Politècnica de Catalunya (UPC) in Spain, with collaboration from research institutions, telecom operators, and industrial partners across Europe.
• Budget: The total project cost exceeded €4 million, with significant funding from the European Commission.

The project developed multiple proof-of-concept systems, successfully demonstrating high-speed optical transmissions and scalable designs that could support thousands of households.

Achievements and Outcomes

1. High-Speed Data Transmission:
   • Demonstrated 10 Gbps extended-reach networks capable of serving hundreds of users simultaneously.
2. Scalability and Resilience:
   • The ring-based structure allowed seamless expansion and quick recovery from link failures, ensuring high reliability.
3. Integration of Metro and Access Networks:
   • Bridged the traditional divide between core and access networks by creating a unified optical infrastructure.
4. Energy Efficiency:
   • Reduced the power requirement for external network components by maximising passive architecture usage.
5. Cost Optimisation:
   • Showed that high capacity and long reach could be achieved with only moderate increases in investment compared to conventional optical networks.
6. Foundation for Future Research:
   • SARDANA influenced subsequent research on next-generation Passive Optical Networks (PONs) and 5G backhaul systems.

Advantages of the SARDANA Approach

• High Capacity: Efficient utilisation of optical wavelengths and time slots to serve more users per fibre.
• Flexibility: Easily adaptable to different geographical areas and user densities.
• Reliability: Ring topology ensures fault tolerance and uninterrupted service.
• Energy Efficiency: Minimal need for powered equipment in the field.
• Cost-Effective Expansion: Uses existing fibre infrastructure while offering significantly greater bandwidth.

Challenges and Limitations

1. Complexity of WDM-TDM Integration: Managing multiple wavelengths and time slots required precise synchronisation.
2. Component Cost: Advanced optical components such as RSOAs and tunable lasers remained expensive during the experimental phase.
3. Compatibility: Integrating the architecture with legacy access systems and industry standards posed difficulties.
4. Commercial Viability: Transitioning from laboratory demonstration to large-scale deployment required further cost reduction and standardisation.

Significance and Legacy

Project SARDANA represented a milestone in the evolution of broadband optical access networks. It offered a sustainable solution to growing data demand by merging high-speed metropolitan infrastructure with local access systems.
Its innovations contributed to:

• The development of next-generation Passive Optical Networks (NG-PON2).
• Research into optical front/backhaul for 5G networks.
• Improved understanding of energy-efficient and resilient network architectures.

SARDANA’s success established a model for future optical network design — combining advanced technology, practical scalability, and environmental responsibility to meet the digital needs of modern societies.