Exploitable results Broadband access for all Europeans The U-BROAD project is addressing the following IST strategic objectives for Broadband for All: - Network technologies and architecture enabling broadband access to European users. - Low cost access network equipment for legacy and new operating environments and services. - Increased bandwidth capacity to the access network. Major project's results - Derived a theoretical bound on the number of samples required in blind separation using general cost functions to achieve a specified performance with a specified probability - Put actual numbers on the capacity that can be expected from these short broadband copper loops, for both single-line and vectored transmission. This is the first time that the capacity of very short twisted copper channels is assessed based on measured data. Going beyond mean per-loop capacity, we have obtained hard data for minimum and maximum capacity (and thus capacity spread); plus estimates of the outage capacity. - Derived algorithms for adaptive interference cancellation of forward (FEXT) crosstalk using limited feedback of the CPEs - Were able to prove that downstream rates of 200 Mbps per pair are achievable on a coordinated binder for distance of 250m.This opens the possibility to Giga-Bit transmission over low number of pairs - All results have been verified on measured binders of 28 channels. This is the first publicly available extensive study of multichannel techniques using real life measured data - We have investigated the combination of shaped spectra and advanced coding, and shown that the reach can be improved significantly by a proper transmission shape design. ??Developed a prototype transceiver system that includes hw, sw and algorithms implementation. The results obtain in WP4, and that are summarized in D4.3 show that the UBROAD transceiver prototype has achieved 100 Mbps DS transmission up-to reach of 350m. Further more the results show that the transceiver can achieve rates of 100Mbps US transmission up-to 300m as well. - The prototype transceiver which was developed is capable of up-to 100Mbps both in US and in DS at reach from 300m up to 1Km - Created a significant list of journal and conference publications and contribution to standards as described in WP09 Dissemination and use ??Obtained VDSL2 crosstalk models derived from measured data for lengths between 75 and 590 meters and frequencies up to 30 MHz. The results indicate that the log-normal model (with a simple parametric law for the frequency-dependent mean) fits well up to 30 MHz. This further qualifies earlier log-normal modeling and validation results for bandwidths in the order of a few MHz. The fitted crosstalk power spectra are useful for modem design and simulation. Insertion loss, phase, and impulse response duration characteristics of the direct channels were also obtained. The results are summarized in a journal paper, to be published in EURASIP Journal on Applied Signal Processing, special issue on DSL - Two algorithms for adaptive FEXT cancellation using precoding. The purpose of the first algorithm is to estimate, at the CO, the forward (FEXT) channels of all the crosstalk channels to all CPEs, without the use of training periods, but by using limited feedback from the CPEs to the CO. The precoder can be obtained by inverting the estimated crosstalk channel matrix. The purpose of the second algorithm is similar but avoids the matrix inversion step by directly designing and adapting the precoder such that forward (downstream) interference to each user CPE is minimized. This is an adaptive algorithm also relying on limited feedback of the received signal by each CPE, hence avoiding training overhead. The algorithms are developed by TUD. The results may be exploited by MTLK, in an implementation of vectored DSL (this is not planned as part of the UBROAD project). A software implementation of the results may be exploited as part of DSL network equipment. The algorithms will be published, making its use public domain. A further development may affect standardization, but this is not expected in the near future. Further research is needed to identify the preferred implementation details, and to derive alternative algorithms. - Assessed single-pair and multi-pair VDSL2 channel capacities using the measured channel data. Key statistics (minimum, mean, maximum per-loop capacity) were obtained for both uncoordinated and vectored transmission, and the vectoring benefit was evaluated. The results provide useful bounds for developers and providers alike. Buscando datos de OpenAIRE... Se ha producido un error en la búsqueda de datos de OpenAIRE No hay resultados disponibles
