Gigabit-Capable Passive Optical Network (GPON) reach extension using optical amplification is well established, yet validation of user-facing service performance at the Optical Network Terminal (ONT) Ethernet interface remains limited. This paper addresses this gap by experimentally validating a distributed, circulator-separated reach extender based on two Semiconductor Optical Amplifiers (SOAs) in a controlled laboratory testbed, comparing a passive 50 km baseline with a 60 km reach-extended link. Service performance was assessed at the ONT Ethernet interface using RFC 6349 TCP throughput testing and ITU-T Y.1564 Ethernet service activation testing, with values reported as medians from 10 independent runs. Internet Protocol Television (IPTV) quality was evaluated using estimated Mean Opinion Score—Video (MOS-V) and Estimated Peak Signal-to-Noise Ratio (EPSNR) for H.264 and MPEG-2 streams. The 60 km configuration preserved upstream TCP throughput while reducing downstream throughput from 765.650 to 721.900 Mbit/s. Median latency increased from 1.336 to 1.408 ms, jitter decreased from 0.076 to 0.057 ms, and video-profile frame loss increased from 0 to approximately 0.0064. MOS-V values remained predominantly in the good range. The results indicate feasible 60 km GPON operation with measurable downstream and loss-related trade-offs, providing repeatable service-level validation beyond optical-budget-only reporting rather than introducing a new optical reach-extender architecture.
Štípal et al. (Tue,) studied this question.