Recent Advances in DSP Techniques for Mode Division Multiplexing Optical Networks with MIMO Equalization: A Review

Abstract

This paper provides a technical review regarding the latest progress on multi-input multi-output (MIMO) digital signal processing (DSP) equalization techniques for high-capacity fiber-optic communication networks. Space division multiplexing (SDM) technology was initially developed to improve the demanding capacity of optic-interconnect links through mode-division multiplexing (MDM) using few-mode fibers (FMF), or core-multiplexing exploiting multicore fibers (MCF). Primarily, adaptive MIMO filtering techniques were proposed to de-multiplex the signals upon different modes or cores, and to dynamically compensate for the differential mode group delays (DMGD) plus mode-dependent loss (MDL) via DSP. Particularly, the frequency-domain equalization (FDE) techniques suggestively lessen the algorithmic complexity, compared with time-domain equalization (TDE), while holding comparable performance, amongst which the least mean squares (LMS) and recursive least squares (RLS) algorithms are most ubiquitous and, hence, extensively premeditated. In this paper, we not only enclose the state of the art of MIMO equalizers, predominantly focusing on the advantage of implementing the space–time block-coding (STBC)-assisted MIMO technique, but we also cover the performance evaluation for different MIMO-FDE schemes of DMGD and MDL for adaptive coherent receivers. Moreover, the hardware complexity optimization for MIMO-DSP is discussed, and a joint-compensation scheme is deliberated for chromatic dispersion (CD) and DMGD, along with a number of recent experimental demonstrations using MIMO-DSP.

Advances in local area optical data communication systems

“…At the other extreme if large core, few mode, MMF is used, then each mode of the fibre could be used to create a communication channel and the capacity is increased by the number of modes. Due to mode coupling effects, few mode MMF requires multiple-input multipleoutput (MIMO) digital signal processing methods to recover the data from the various modes [40].…”

Special Issue on Advanced DSP Techniques for High-Capacity and Energy-Efficient Optical Fiber Communications

“…• Recent Advances in DSP Techniques for Mode Division Multiplexing Optical Networks with MIMO Equalization: A Review [3] This paper provides a technical review regarding the latest progress on multi-input multi-output (MIMO) DSP equalization techniques for high-capacity fiber-optic communication networks. The authors discuss state of the art of MIMO equalizers, predominantly focusing on the advantages of implementing the space-time block coding (STBC)-assisted MIMO technique.…”

Optical MIMO communication with unequal power allocation to channels

“…The corresponding techniques are referred to as time-division multiplexing (TDM), wavelength-division multiplexing (WDM), polarization-division multiplexing (PDM), and phase modulation (PM) [1][2][3][4][5][6]. Yet another approach to enhance the capacity of optical communication is via space division multiplexing (SDM), which relies on tightly packing several spatial channels with the aid of multimode or multicore fibers [6,7]. In this context, one has to naturally deal with the multiple-input multiple-output (MIMO) approach in optical communication.…”

“…It offers several advantages such as higher data rate, lower bit error rate (BER), higher reliability, lower susceptibility of tapping, and supports a large number of users. While it does come with some drawbacks also, such as the requirement of complicated hardware and software, etc., the advantages weigh more and consequently MIMO approach has attracted a lot of interest in the recent years [7][8][9][10][11][12][13][14][15][16][17][18].…”