Idelfonso Tafur Monroy's Lab

 

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Reconfigurable Microwave Filters

Posted in Ongoing projects

This project investigates short range 400G optical solutions for datacenters, which adopt polybinary modulation formats in order to increase the spectral efficiency. Data transmission experiments using polybinary signals have demonstrated that the selection of the microwave Low Pass Filter (LPF) required for the modulation of the polybinary signal is critical. Given this scenario the main problem that this PhD project tackles is the design of a reconfigurable microwave LPF optimized for the generation of polybinary signals for 100G and 400G optical solutions.

 

Main researcher:

Bruno Cimoli

Partial Response Advanced Modulation Formats for Bandwidth Limited Optical Links

Posted in Ongoing projects

The world is experiencing the era of the internet, where every device is connected via the world wide web and its many interfaces. The many connections and related applications puts a great pressure on the systems we use today in a call for higher bandwidth. This is an upcoming problem that needs an answer, not only for existing systems, but also future systems needs to be able to expand in bandwidth should the need arise. 

This PhD project focuses on optimizing and improving spectral efficiency for a large verity of bandwidth limited systems. This is done by applying advanced modulations formats to the transmitted signals. By studying advanced modulation format schemes capable of sustaining the increasing traffic demand, the energy required to convey data will be reduced. This will eventually lead to a green and affordable bandwidth for services and application that society demands.

The goals of this project is to study, propose and implement novel methods in the area of partial response advance modulation formats for bandwidth limited optical links. Polybinary signals will be investigated as the main modulation format to reduce the energy consumption in transmission links. The main topics the researcher will tackle within the project are:

  • System requriments for datacom and sensing applications.
  • Polybinary signaling to reduce energy consumption and to enable higer usage of the existing channels. 
  • Testbed design and implementation to experimentally demonstrate super high capacity fiber-wireless hybrid channels oprating at 100Gbit/s.

This project will assess how technologies developed in the area of microwave photonics and energy efficient advanced modulation formats can be used in the following scenarios:

  • High capacity wireless links operating in the low-terahertz regime.
  • W-bans photonic radars for transprotation applications.
  • Biomedical imaging for non-invasive invo analysis. 
  • imaging systems.
  • LIDAR monitoring. 

As seen from the list above, this project leans upon existing ongoing and completed projects as building foundation for improving towards a more spectral and energy efficient solution.

 

Main Researcher:

Peter Madsen

 

Supervisors:

Juan José Vegas Olmos

Idelfonso Tafur Monroy

HIGH CAPACITY OPTICAL COMMUNICATION LINKS FOR LARGE DATACENTERS

Posted in Ongoing projects

The market for fast and large datacenters is growing rapidly. More and more data are stored in the cloud. Companies such as Google, Apple, Microsoft, and Amazon are transferring their business into the cloud. It is noteworthy that the data-center companies in China are growing to become even larger than their US counterparts. Worldwide, the demand for switching and data transmission within data-centers is increasing rapidly. Thus, researches in boosting the performance, cost and energy efficiency and reliabilities in switches and transport modules (connecting switches with computers or storage systems) have a huge space and opportunities.

This project is about optical transport module technologies inside such large data-centers. Since a large data-center consists of a large number of computers and switches, the data rate of optical transport modules connecting these internal components is a key factor to determine the overall performance of the data-center.

The goal of this project is to study, propose and implement novel modulation formats and corresponding equalizer and transport scheme for applications in high speed optical transport modules for large data centers. The main topics the researcher will tackle within the project are:

  • System requirements for high speed active optical cables and Datacom links
  • Advanced modulation formats for high speed IM/DD optical transport links
  • Equalization techniques to compensate for nonlinear VCSEL behavior
  • Compensation techniques for mitigation of impairments of end-to-end link performance
  • Co-design and testing of system level features of developed integrated drivers, VCELs, and data-link
  • Testbed design and its implementation to experimentally demonstrate ultrahigh speed VCSEL based data links

The expected outcome of this project would be:

  • Experimental validation of VCSEL high speed optical short reach data link
  • Experimental performance evaluation of various modulation formats on short-reach data links
  • Analytic analysis and experimental validation of the concept for adaptive optical cable
  • Experimental validation novel transmission schemes on optical data links such as wireless OAM

PhD researcher: Xiaofeng Lu

Supervisor: Prof. Idelfonso Tafur Monroy

google-datacenter-tech-13.jpg

 A typical data centre from Google. Image source: google.com/datacenters

Flexible Multirate Access Networks based on Optical Code-Division Multiple-Access

Posted in Ongoing projects

Project Background 

Telecommunication service providers need to continually evolve their existing networks to withstand the rigors of ever-increasing traffic demand in forthcoming years. This new demand is mainly attributed to the increasing popularity of bandwidth-intensive networking applications, such as high-definition television (HDTV) over IPTV, interactive e-learning, e-health, cloud computing, video-on-demand, and 3-D/4K video streaming. Telecom providers expect a technology standard with potential of meeting the requirements of next generation passive optical network (NG-PON).

Optical code-division multiple-access (OCDMA) is an attractive architecture in all-optical networking gthat can be straightforwardly employed to support multiple rates and differentiated services transmissions at the physical layer. Unique features such as asynchronous tell-and-go multiple access capability (a key issue for practical network deployment), low-latency access, soft capacity on-demand, and high data confidentiality make OCDMA very attractive to implement Flexible Access Networks.

Project Scope

This Ph.D. project is being conducted within the Science without Borders (SwB) program of the Brazilian federal government in agreement between the University of São Paulo (USP) and DTU.

The goal of the project is to propose and implement new multirate transmission techniques in flexible OCDMA networks based on fiber Bragg gratings transceivers and modulation formats. It includes the experimental performance investigation of the following multirate network scenarios:

  • OCDMA networks based on OOK modulation format;
  • OCDMA networks based on PSK modulation formats;
  • Coherent and incoherent hybrid OCDMA networks.

Wavelet-based functionalities for high capacity hybrid fiber-wireless links

Posted in Ongoing projects

In wireless transmission, signal degradation caused by path loss and shadowing must be compensated by applying some type of diversity scheme that creates additional uncorrelated estimates of the signal. To overcome frequency selectivity, some pre-processing must be performed (spread spectrum, multi-carrier modulation etc.) or equalization will be needed.

Wavelet analysis provides an efficient universal representation for a wide class of functions, much larger than the class of square-integrable functions or finite energy signals. That covers, for instance, kinds of basis functions that are potentially realizable by physical devices. A particular contribution of far-reaching generalizations of orthogonal base functions is a systematic way to compactly support and overlap functions on unbounded domains. Such a feature can be very well suited for an efficient design of channel coding algorithms, making it easy to orthogonally overlap information avoiding redundancies. It also provides a coherent framework for the design of perfect reconstruction filter banks that can be used for subcarrier generation and data modulation.