SARDANA: Single-fiber-tree Advanced Ring-based Dense Access Network Architecture

Kurzfassung

A research group from the Technical University of Catalonia has developed a network within the New Fibre-to-the-Home (FTTH) projects. This network includes scalability, flexibility and resiliency, as well as the number of served customers per PON (Passive Optical Network) and the distance reach increase. The research group is interested in licensing the patent with a technical cooperation in order to assist the company in getting a prototype for the field tests.

Details

The novel SARDANA network (Single-fibre Advanced Ring-based Dense Access Network Architecture), developed at UPC, and transparently combines the WDM (Wavelength Division Multiplexing) and the TDM (Time Division Multiplexing) dimensions to reach the extra-large user-density. It is based on a double-fibre-ring with single-fibre wavelength-dedicated trees connected to the main ring at the Remote Nodes (RN), which implement simplified optical Add & Drop multiplexers by means of splitters and fixed filters that distribute different wavelengths to each of the access trees. Remote amplification is introduced at the RN by means of Erbium Doped Fibres (EDFs) for compensating add/drop losses. Optical pump for the remote amplification is provided by the pumping lasers located at the Central Office (CO). The CO uses a stack of tuneable lasers for serving the different tree network segments on a TDM basis. Any laser can serve each network segment by tuning to the appropriate wavelength, using WDM for routing and using DBA techniques to concentrate the resources at the more demanding networks sections. The CO centralizes the light generation for the whole network and its control. On the other end, the user equipment (ONU) is colourless and maximally simplified, implemented with a single reflective semiconductor optical amplifier (RSOA) for upstream remodulation, on the same fibre. The completely passive FTTH network provides broadband to >1000 users, using 32 wavelengths at 2.5 Gbit/s each. An ultra-dense WDM version, for thousands of optical carriers, has also been demonstrated.

Innovative Aspects:
Innovations:

- The novel RN design allows to efficiently interface the single-fibre access-trees with the dual-fibre metro-ring, presenting add/drop capability with maximum transparency at the ring bypass.
- The remote amplification is incorporated for the first time in an extended PON access network, enabling to reach the high number of users and the long distances. The optical amplification takes place at the RN, while the pump lasers are located at the termination ends, thus maintaining the passiveness of the external plant.
- The RSOA device has been adopted for the ONU, thanks to its innovative operation and agile wavelength control, with hybrid modulation for down- and up-stream full-duplex transmission.
- The CO design features geographical dynamic bandwidth allocation (DBA).

Advantages:

- Broadband service to 1000 users from a minimum fibre infrastructure.
- Large capacity: bidirectional 100Mbit/s bandwidth per user.
- 100 Km distance reach.
- Smooth scalability, including traffic balancing, resiliency and geographical bandwidth allocation for optimum resource utilisation.
- Centralised light-generation and control.
- By concentrating the complexity at the CO, reducing it at ONU and fibre plant, and by maximising the number of users, the overall cost per user is potentially reduced, as compared to that of standard solutions.