Mode Group Diversity Multiplexing Research Articles

Studying the effect of changing Input conditions on MMF using MGDM technique

The mode group diversity multiplexing (MGDM) multicast technology uses optical multiple input and output (O-MIMO) technology to provide greater capacity and the ability to transmit information over multi-mode fiber (MMF). The MGDM system has a benefit in terms of capacity expansion, which led to interest in its use in most optical communications. The MGDM exploits the optical fiber bandwidth by inserting spatial light detection, which increases the capacity of the MMF. This research aims to study the optical systems used for the MGDM technology, and to identify the methods of their analysis and design of O-MIMO systems to increase the amplitude of this signal. The conditions of light entry into the optical fiber such as typical spot size, radial displacements, angle, wavelength, and radius of the detectors sections are improved. Numerical MATLAB simulation is used to improve the amplitude of graded index multimode fiber (GI-MMF) and compared to the existing aggregation systems. Moreover, this method was simulated to improve the input and detection conditions to increase the O-MIMO capacity using the MGDM technique. Finally, the capacity of the MGDM system was studied and compared with different channels, and it is noticed that the capacity of the system increases with increasing the number of channels.

Novel Method for Improving the Capacity of Optical MIMO System Using MGDM

In current local area networks, multimode fibers (MMFs), primarily graded index (GI) MMFs, are the main types of fibers employed for data communications. Due to their enormous bandwidth, it is considered that they are the main channel medium that can offer broadband multiservices using optical multiplexing techniques. Amongst these, mode group diversity multiplexing (MGDM) has been proposed as a way to integrate various services over an MMF network by exciting different groups of modes that can be used as independent and parallel communication channels. In this paper, we study optical multiple-input–multiple-output (O-MIMO) systems using MGDM techniques while also optimizing the launching conditions of light at the fiber inputs and the spot size, radial offset, angular offset, wavelength, and the radii of the segment areas of the detectors. We propose a new approach based on the optimization of launching and detection conditions in order to increase the capacity of an O-MIMO link using the MGDM technique. We propose a (3 $\times$ 3) O-MIMO system, where our simulation results show significant improvement in GI MMFs' capacity compared with existing O-MIMO systems.

De-multiplexing based on complex ICA for mode group diversity multiplexing system

In order to mitigate the crosstalk in mode group diversity multiplexing (MGDM) system, the fixed-point complex ICA algorithm (T-CMN) based on negative entropy maximization is proposed to implement de-multiplexing in a 2 $$\times $$ 2 MGDM system in which two QAM signals are transmitted. The performance of this algorithm is compared with the DD-LMS (Decision-directed Least Mean Square Algorithm). The results indicate that the T-CMN algorithm separates the signals successfully and achieves a better de-multiplexing performance than DD-LMS.

New Passenger Services in Railway Stations Based on Mode Group Diversity Multiplexing Optical Fiber Communications

Nowadays, because of its wide bandwidth and high communication capability, the optical fiber is more and more used for high data rate transmission of information in railway environments. Conventionally, only one service is sent over the fiber at a time. However, many different services can be simultaneously conveyed in railway stations such as passenger information service, cellular phone, Wi-Fi… The objective of the work proposed in this paper is to demonstrate the potential benefits of transmitting radio signals over fiber in a railway environment. The main idea is to exploit the full capacity of the fiber by transmitting multiple services using the same fiber. Since, different services are operating in different frequency bands; we propose a new multiplexing technique called Mode Group Diversity Multiplexing (MGDM) to ensure the transmission of multiple services using the same fiber, without additional infrastructure. There are numerous advantages of the proposed technique, e.g., faster and reliable data exchange, high resolution video surveillance capability, high data rate information exchange in railway stations. We present, in this paper, the physical characteristics of optical fibers, performance of MGDM multiplexing technique, and the influence of the laser excitation conditions at the entrance of the fiber on the performances of the system.

Adaptation of the Mode Group Diversity Multiplexing Technique for Radio Signal Transmission Over Multimode Fiber

The large bandwidth of multimode fiber (MMF) makes it a very attractive medium for multiservice transmission in building networks at low cost. The mode group diversity multiplexing (MGDM) technique in graded-index multimode fiber (GI-MMF) has been shown to be less expensive with simpler transmitters and receivers, keeping the same information capacity. However, the classic transmission in MGDM complicates the integration of radio-over-fiber (RoF) services. In this paper, we propose a wired and a RoF model dedicated to broadband indoor applications. This model is based on a modified MGDM where we employ a variation of the transmission power technique and a selection algorithm for the optimal transmitter. To evaluate our system, the bit error rate and symbol error rate have been computed.

Mode Group Diversity Multiplexing communication system based on FastICA algorithm

Mode Group Diversity Multiplexing (MGDM) aims at creating independent and parallel communication channels over a single Multimode Fiber (MMF) by exciting several groups of modes. It can significantly improve the capacity of short-reach Multimode Fiber networks. One of the key techniques involves demultiplexing the mixed signals from the output. In this paper, we proposed a fast independent component analysis (FastICA) algorithm to demultiplex the output signals of a 2 × 2 MGDM system more efficiently. The performance of this algorithm is evaluated and compared with the zero-forcing method. Our results indicate that FastICA can demultiplex the mixed signals, improve the eye opening of the eye diagram and achieve the similar results as zero-forcing method.

The inter-modes mixing effects in Mode Group Diversity Multiplexing

Multiplexing technology in indoor optical networks with multimode fibres allows the integration of several services to the end user. The Mode Group Diversity Multiplexing technique (MGDM) in Graded-Index Multi-Mode (GI-MMF) fibre makes the system less expensive with simpler transmitters and receivers, keeping the same information capacity as other multiplexing techniques. The capacity conservation and transmission quality obtained using MGDM technique depends on the transmission conditions and the state of fibre. Bending of the fibre can affect the system by changing modes excited for the different propagation channels in the fibre. In this paper an analytical modelling method for MGDM will be presented. Improvements in system sending and receiving conditions are studied. Modelling of the fibre curvature as well as the effects of coupling patterns on the MGDM are discussed.

Influence of mode coupling on mode group diversity multiplexing in multimode fibers

In this paper, the influence of mode coupling on mode group diversity multiplexing (MGDM) in multimode fibers is investigated. It is found experimentally, that in step index fibers mode coupling is very strong among the lowest mode groups. It is confirmed that mode coupling in graded index fibers is negligible. Theoretical and numerical investigation of the system performance in strong mode coupling conditions, indicates need for greater separation of the lowest MGDM channels.

Mitigation of Impairments in MGDM Transmission With Mode-Selective Spatial Filtering

A model for a mode group diversity multiplexing (MGDM) transmission system is derived. The factors that may limit MGDM transmission are identified. An optical method to reduce the spatial overlap among the fields of the detected mode groups could mitigate impairments that may occur in MGDM transmission. Mode-selective spatial filtering (MSSF) is such an optical method. Experimental results support that a robust five-channel MGDM system could be realized with MSSF, as long as modal noise is limited. MSSF facilitates the combination of MGDM with wavelength-division multiplexing.

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多模光纤模式群分集复用系统

Mode-selective spatial filtering for increased robustness in a mode group diversity multiplexing link

We propose a very simple optical method to reduce the cross talk among the channels of a mode group diversity multiplexing (MGDM) link. MGDM is an intensity modulation, direct detection, multiple-input, multiple-output technique that creates independent communication channels over a multimode fiber (MMF). The cross talk among the channels is mitigated electronically. However, by properly employing a lens between the output of a graded-index MMF and the detectors, we achieve mode-selective spatial filtering (MSSF) and optically reduce the cross talk. The robustness of the link is then increased when compared with an implementation without MSSF. This allows for a larger number of channels.

Temporal Stability of a Transparent Mode Group Diversity Multiplexing Link

The temporal behavior of a mode group diversity multiplexing (MGDM) link is examined. MGDM has been proposed as a way of creating parallel, independent communication channels over multimode fiber (MMF) links using different groups of modes. When the effect of dispersion can be neglected, the output electrical signals of an MGDM link are related to the input ones via a real-valued transmission matrix. The transmission matrix is vulnerable to changes in the modal spectrum of the propagating mode groups as well as to the coupling of light at the input and output of the MMF. Measurements of the transmission matrix of a two-input two-output system over 12.7 h show that an MGDM link can be very stable

Design Considerations for a Transparent Mode Group Diversity Multiplexing Link

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Mode group diversity multiplexing (MGDM) is an optical multiple-input–multiple-output technique that aims at creating independent communication channels over a multimode fiber, using subsets of propagating modes. This letter deals with the analysis of an MGDM point-to-point link, transparent to the transmission format. The geometry of a mode-group selective multi/demultiplexer is optimized in order to minimize the crosstalk among the channels. The power penalty is calculated when a zero-forcing algorithm is used to mitigate the crosstalk. </para>