# Employing Channel Probing to Derive End-of-Life Service Margins for Optical Spectrum Services. To appear in OPTICA Journal of Optical Communications and Networking

**Authors:** K. Kaeval, F. Slyne, S. Troia, E. Kenny, K. Große, H. Griesser, D. C. Kilper, M. Ruffini, J-J Pedreno-Manresa, S. K. Patri, G. Jervan  
**arXiv:** [2302.04623](https://arxiv.org/abs/2302.04623)  
**Date:** 2023-02-09  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/2302.04623v1/

## Key points

- The work explores the accuracy aspects of channel probing method used in GSNR-based OSaaS characterization in terrestrial brownfield systems.
- OSaaS services can reduce investment and operational costs by using reconfigurable transceivers and disaggregation trend in optical transport networks.
- The study experimentally derives OSaaS service margins to accommodate impacts from enabling neighboring channels and end-of-life channel loads in a systematic lab study carried out in the Open Ireland testbed.
- The applicability of these lab-derived margins is verified in the HEAnet production network using a 400 GHz wide OSaaS.
- A minimum of 0.92 dB and 1.46 dB of service margin allocation is recommended to accommodate impacts from enabling neighboring channels and end-of-life channel loads, respectively.
- Further 0.6 dB of GSNR margin should be allocated to compensate for probing inaccuracies.
- The study provides valuable insights into accurately characterizing OSaaS services' performance metrics and deriving appropriate service margins that can ensure reliable operation throughout their lifetime while minimizing operational costs.
- Future research directions include exploring alternative methods for characterizing OSaaS services that are more resilient against probing inaccuracies or developing machine learning-based algorithms for predicting end-of-life margins based on real-time monitoring data.

## Summary

This work explores the accuracy aspects of the channel probing method used in Generalized Signal to Noise Ratio (GSNR)-based Optical Spectrum as a Service (OSaaS) characterization in terrestrial brownfield systems. OSaaS services, which span over multiple transparent optical network domains, can significantly reduce investment and operational costs by utilizing reconfigurable transceivers and the emerging disaggregation trend in optical transport networks. The study experimentally derives OSaaS service margins to accommodate impacts from enabling neighboring channels and end-of-life channel loads in a systematic lab study carried out in the Open Ireland testbed. The applicability of these lab-derived margins is then verified in the HEAnet production network using a 400 GHz wide OSaaS. The probing accuracy is tested by depleting the GSNR margin through power adjustments utilizing the same 400 GHz OSaaS in the HEAnet live network. A minimum of 0.92 dB and 1.46 dB of service margin allocation is recommended to accommodate impacts from enabling neighboring channels and end-of-life channel loads, respectively. Additionally, further 0.6 dB of GSNR margin should be allocated to compensate for probing inaccuracies. The lab setup was connected to the ROADM C-ports in HEAnet production network through two dedicated fiber pairs with four link lengths achieved by looping the signal. The layout of the live network together with interconnection site is illustrated in Fig.2. This study provides valuable insights into accurately characterizing OSaaS services' performance metrics and deriving appropriate service margins that can ensure reliable operation throughout their lifetime while minimizing operational costs. Further elaborations on this work include recommendations for future research directions such as exploring alternative methods for characterizing OSaaS services that are more resilient against probing inaccuracies or developing machine learning-based algorithms for predicting end-of-life margins based on real-time monitoring data.