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Updated: Jun 12, 2026

Continuous-Wave Propagation Channel-Sounding Measurement System - Testing, Verification, and Measurements
Published on: June 25, 2021
LFM-pilot-based localization and monitoring of multiple-spot multipath interference in discrete multitone systems
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The short-reach optical transmission systems based on intensity modulation and direct detection (IM/DD) have been widely adopted in intra-datacenter networks. Multipath interference (MPI) introduces irregular power fluctuation in IM/DD signals, thereby degrading transmission performance. This paper proposes an MPI localization and power monitoring method in a discrete multitone (DMT) system by using a specially designed linear frequency-modulated (LFM) pilot sequence that is also utilized for frame synchronization. Among IM/DD modulation formats, DMT provides flexible encoding capabilities and is particularly well-suited for MPI localization while maintaining high spectral efficiency. In a DMT transmission system with an effective bandwidth of 14 GHz, numerical and experimental results show that the proposed scheme can achieve precise MPI localization with an error of less than 0.16 m at any location and enables reliable power monitoring without introducing any power penalty. Furthermore, the system supports simultaneous localization of multiple reflected signals, with a localization accuracy of 1 m in an experiment.
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