Maria Morant

Ultra-Wideband Radio Signals Distribution in FTTH Networks

The use of an ultra-wideband (UWB) radio technique is proposed as a viable solution for the distribution of high-definition audio/video content in fiber-to-the-home (FTTH) networks. The approach suitability is demonstrated by the transmission of standards-based UWB signals at 1.25 Gb/s along different FTTH fiber links with 25 km up to 60 km of standard single-mode fiber length in a laboratory experiment. Experimental results suggest that orthogonal frequency-division-multiplexed UWB signals exhibit better transmission performance in FFTH networks than impulse radio UWB signals.

Radio-over-fiber transport for the support of wireless broadband services [Invited]

Some of the work carried out within the EU Network of Excellence ISIS on radio-over-fiber systems for the support of current and emerging wireless networks is reviewed. Direct laser modulation and externally modulated links have been investigated, and demonstrations of single-mode fiber and multimode fiber systems are presented. The wireless networks studied range from personal area networks (such as ZigBee and ultrawideband) through wireless local area networks to wireless metropolitan area networks (WiMAX) and third-generation mobile communications systems. The performance of the radio-over-fiber transmission is referenced to the specifications of the relevant standard, protocol operation is verified, and complete network demonstrations are implemented.

Transmission impairment compensation using broadband channel sounding in multi-format OFDM-based long-reach PONs

A centralized impairment compensation technique using outband RF-pilots in OFDM-based long-reach PONs supporting quadruple-play services is proposed. With this technique, a 6.7dB EVM improvement is achieved, and all signals are EVM-compliant after 100km of SSMF.

Transmission of OFDM wired-wireless quintuple-play services along WDM LR-PONs using centralized broadband impairment compensation

The simultaneous transmission of four orthogonal frequency-division multiplexing (OFDM)-based signals used to provide quintuple-play services along wavelength division multiplexing (WDM) long-reach passive optical networks (LR-PONs) is demonstrated experimentally. Particularly, the transmission performance of custom signal bearing Gigabit Ethernet data, Worldwide Interoperability for Microwave Access, Long Term Evolution and Ultra Wideband (sub-bands 2 and 3) signals is evaluated for different LR-PONs reaches, considering single-wavelength and WDM transmission, and using a centralized impairment compensation technique at the central office that is transparent to the services provided.It is shown that error vector magnitude-compliant levels are obtained for all the OFDM-based signals in WDM LR-PONs reaching 100 km and that negligible inter-channel crosstalk is obtained for a channel spacing of 100 GHz regardless the OFDM-based signal considered. The successful multi-format OFDM transmission along the 100 km-long WDM LR-PON is achieved in the absence of optical dispersion compensation or single sideband modulation, and it is enabled by the performance improvement provided by the centralized impairment compensation realized.

Radio-Over-Fiber Optical Polarization-Multiplexed Networks for 3GPP Wireless Carrier-Aggregated MIMO Provision

This paper proposes and demonstrates experimentally the application of optical polarization-multiplexed radio-over-fiber wireless backhauling of fully standard 3GPP carrier-aggregated multiple-input multiple-output (MIMO) signals. The experimental work demonstrates successful long-reach optical transmission of 3GPP carrier-aggregated LTE-Advanced (LTE-A) signals using 2×2 MIMO spatial diversity. The suitability of MIMO provision using radio-over-fiber optical links is demonstrated over different E-UTRA frequency division duplex frequency bands. The performance of electrical carrier aggregation is evaluated in different configurations comprising one, three and five LTE-A component carriers of 10 and 20 MHz bandwidth each. The experimental results demonstrate successful 2×2 MIMO radio-over-fiber polarization-multiplexed transmission of five LTE-A carriers over 25 km, three LTE-A carriers over 75 km and an LTE-A carrier over 100 km of standard single mode fiber to provide pervasive MIMO wireless service to a large number of users.

Joint Distribution of Polarization-Multiplexed UWB and WiMAX Radio in PON

In this paper, the feasibility of the joint distribution of ultra-wideband (UWB) and WIMAX wireless using polarization multiplexing as a coexistence technique is proposed and experimentally demonstrated within the framework of passive optical networks (PON). Four single- and orthogonal-polarization multiplexing schemes are studied targeting to reduce the mutual interference when UWB and WiMAX are distributed jointly through standard single-mode fiber (SSMF) without transmission impairments compensation techniques and amplification. Experimental results indicate successful transmission up to 25 km, in SSMF exceeding the range in typical PON deployments. The radio link penalty introduced by optical transmission is also investigated in this paper.

Optical Distribution of OFDM and Impulse-Radio UWB in FTTH networks

Proposal, experimental demonstration and performance comparison of impulse-radio UWB and OFDM UWB distribution in FTTH networks for high-definition audio/video broadcasting is presented. OFDM-UWB exhibits better performance compared with its impulse- radio counterpart with better spectral efficiency.

Data Mining in Higher Education

Higher Education targets to develop complex theoretical, abstract and analytical reasoning capabilities in the alumni. This objective can be accomplished addressing four major steps: Theoretical foundation, practice, communication and assessment (Petry, 2002). Theoretical background and practical exercise comprise the basic knowledge building process at initial stages. Assessment guides the alumni through higher complexity studies permitting the student to identify the weak points in the knowledge building where further theory study and/or practice is required. Theoretical foundation and problem-solving practice are well known aspects in Higher Education. High-quality materials in printed and electronic format, sometimes including multimedia –audio, video or computer graphics–, sometimes delivered through the Internet are readily available today. Teaching-aids as computer-feed overhead projectors or electronic blackboards in the classroom are common place and facilitate the knowledgebuilding process. Moreover, computers in the classroom are a powerful tool linking theory and problem-solving practice in engineering studies (Beyerlein et al., 1993). On the other hand, the assessment process has been evolving slowly in the last decades. Pen-and-paper examination techniques have been translated to the computer-enabled classroom as software applications that present an exam in the screen and record the student answers. This process can be seen as an external assessment targeting to evaluate the skills of the student in order to give a pass/fail on a given subject. The external evaluation can be useful for the student in order to know the skill level, but usually fails short when the student wants to now “what’s wrong”, i.e. to know not only what question was missed but also what knowledge areas the student is finding difficulties. Weak areas identification cannot be done from a single question or set of questions. It requires the assessment process, examination or similar, to be considered as a whole. Student attention time or time spent thinking on a specific question –relative to the other question, as some students think faster than othersclearly indicates the areas where difficulties hide, by example. The pattern followed when answering the exam questions, by example, is another useful indicator. The student will try to answer first the questions he feels more comfortable with. Dubitation on the answer –change the answer several times– is another useful parameter. All these parameters and many others can be compiled and processed by the unprecedented analytic processing capabilities of modern data mining techniques. Collaborative assessment appears as a the natural evolution from the individual learning to the collaborative learning, which was proposed as a suitable technique to speed-up development of analytical reasoning as different approaches are continuously suggested

On the Suitability of Multicore Fiber for LTE–Advanced MIMO Optical Fronthaul Systems

This paper proposes and evaluates analytically and experimentally the suitability of spatial multiplexing in multicore fiber (MCF) for multiple-input multiple-output (MIMO) LTE-Advanced (LTE-A) optical fronthaul systems including carrier aggregation. The experimental test-bed comprises a 150-m optical fronthaul of four-core homogeneous MCF, which can be configured with different bending radius for analysis. Performance of linear crosstalk in MCF media is evaluated by simulation and validated by the experimental work in the laboratory with the radio-over-fiber transmission of full-standard LTE-A wireless signals considering both SISO and MIMO configurations. The optical fronthaul analysis evaluates both same-propagation and counter-propagation spatial multiplexing, i.e., all cores propagating in the same direction and two versus two cores propagating in opposite directions, corresponding to a dual LTE-A roof-mounted system. The performance of the MCF optical fronthaul system is evaluated using a single 20-MHz LTE-A carrier and also carrier-aggregated signals with 16QAM and 64QAM subcarrier modulation. The experimental results indicate that intercore crosstalk (IC-XT) increases up to 9.6 dB when raising the bending radius from 35 to 67 cm, being the bending radius a key parameter in MCF fronthaul systems. The demonstration performed at 1550.12 nm reported an increase of IC-XT of 4.6 dB with the bending radius, which deteriorates the quality of the SISO LTE-A signal up to 8.1 dB error vector magnitude (EVM). This IC-XT impairment can be mitigated using 2×2 MIMO processing, which reduces the EVM impact to less than 1 dB when increasing the MCF bending radius from 35 to 67 cm. The experimental results indicate that 3GPP MIMO LTE-A algorithms already in-place in the wireless LTE-A standard can be used to compensate the IC-XT in the 150-m multicore optical fronthaul system with spatial multiplexing.

Multistandard Wireless Transmission Over SSMF and Large-Core POF for Access and In-Home Networks

An end-to-end transmission of coexisting multistandard radio (LTE, WiMAX, and UWB) signals is demonstrated for the first time with the transmission over a combined access and in-home networks consisting of 25-km SSMF, 25-m large-core diameter polymethylmethacrylate graded-index plastic optical fiber link and 1-m wireless. The residential gateway includes O-E-O conversion to connect the access and in-home parts of the networks. This letter demonstrates a fully integrated radio signal distribution scenario from the central station to the end-user personal area networks.