Successive interference cancellation in spatially multiplexed fiber-optic transmission

Abstract

The multiple-input multiple-output (MIMO) concept is of high interest in fiber-optic communication since it is able to overcome the capacity limits of current transmission systems. In this work different receiver-side interference compensation techniques are studied in a spatially multiplexed fiber-optic transmission through 0.5 km multi-mode fiber with a gross bit-rate of 5 Gbps using intensity modulation and direct detection. Broadband successive interference cancellation (SIC) and broadband zero forcing (ZF) equalization are compared as electronic interference compensation methods in a (2×2) MIMO transmission. The results show that ordered SIC can significantly improve the transmission quality compared to the ZF equalization approach in the studied testbed configuration. Also, spatial filtering as an interference reduction technique is studied with respect to its effect on the bit-error rate (BER) performance, showing that in the analyzed channel scenario the use of such a filter is beneficial. Using a spatial filter improves the mode group separation at the receiver and hence reduces the MIMO signal processing complexity.