1,720,968 research outputs found
Comparison of DSP-based TDMA and FDMA channel aggregation techniques in mobile fronthauling
Full text linkCloud Radio Access Network (C-RAN) is perceived as a future essential technology to satisfy the ever-increasing demand of mobile data traffic. Considerable research efforts are expending in the optimization of C-RAN architecture. In this paper, we perform a comparison of two DSP-based fronthauling techniques for aggregation of radio waveforms: time division multiple access (TDMA) and frequency division multiple access (FDMA), in terms of error vector magnitude (EVM), spectral bandwidth efficiency and digital signal processing (DSP) complexity as a performance metrics. The two techniques are compared by means of simulation and validated experimentally on an intensity modulation and direct detection (IM-DD) optical fronthaul link capable of aggregating 48 and 96 LTE-A (20 MHz) channels. Moreover, we made simulation comparison on 24 (100 MHz) new radio (NR) waveforms which will be used in the upcoming 5G applications. We reveal that there is ~50% and ~20% spectral efficiency gain by TDMA aggregation on LTE-A and NR waveforms respectively. Hence TDMA gives slightly better performance in the case of 96 LTE-A channels which is attributed to slightly better linearity over the optical channel frequency response for larger number of channel. In addition, we show that TDMA is more efficient in terms of complexity than FDMA system that requires an additional pre-emphasis technique to equalize the overall per channel performance
An Analytical Model for Performance Estimation in Modern High-Capacity IMDD Systems
Full text linkIn this article, we propose an analytical model to estimate the signal-to-noise ratio (SNR) and then the Bit Error Rate (BER) at the output of a receiver adaptive equalizer in intensity modulation and direct detection (IMDD) optical transmission systems affected by optoelectronic bandwidth limitations, chromatic dispersion (CD), quantization noise, relative intensity noise (RIN), shot noise and thermal noise. We consider that the proposed model is a powerful tool for the numerical design of strongly band-limited IMDD systems using receiver equalization, as it happens in most of modern and future M-PAM solutions for short reach and access systems. We develop the model as an extension of a previously presented one, and then we test its accuracy by sweeping the main parameters of a 4-PAM-based communication system, such as RIN coefficient, extinction ratio (ER), accumulated CD, equalizer type and memory. Our findings show a remarkable agreement between time-domain simulations and analytical results, with SNR discrepancies below 0.1 dB in most cases, for both feed-forward and decision-feedback equalization. Moreover, we tested our model predictions against experimental measurements, confirming its accuracy
Filtering Power Penalty Evaluation of Coherent Systems Affected by ASE and Transceiver Noise
Full text linkWe experimentally evaluate the filtering penalties
of coherent transmission, for applications in future metro-access
converged systems limited by a mix of ASE and receiver noise.
We present and validate an analytical model to predict them
Filtering Effects Characterization in Metro-Access Networks and Future High-Speed Coherent Optical Communication Schemes
Full text linkWe present a detailed experimental analysis of the penalty introduced by optical filtering during propagation of a high-speed coherently detected signal. We investigate the performance penalty in terms of sensitivity reduction of a commercial coherent transceiver at a given bit error rate (BER) threshold, and resulting maximum achievable optical power budget, when transmitting a 400G PM-16QAM signal through an optical filter with variable parameters such as bandwidth, order and central frequency de-tuning. Moreover, we discuss an analytical method able to predict the experimental results with remarkable accuracy, even at variable optical signal to noise ratio (OSNR) levels and considerably low received optical power. Our analysis aims at improving our understanding of the impact of optical filtering on modern coherent communication schemes and, in particular, in the scenario of adoption of coherent detection in the short-reach transmission segment, for instance in future all-optical metro-access networks. Moreover, our analytical tool can be of great help in the design process of novel network configurations, thanks to its simplicity, reliability and speed
Analysis of 5G New Radio Uplink Signals on an Analogue-RoF System Based on DSP-Assisted Channel Aggregation
Full text linkThe 3rd Generation Partnership Project (3GPP) is in the process of developing 5th generation (5G) radio access technology, the so-called new radio (NR). The aim is to achieve the performance requirements forIMT-2020 radio interface technology. In this paper, we focus on the analysis of the transmission of 5G NR uplink physical channels, such as physical uplink shared channel (PUSCH) and physical uplink control channel (PUCCH), dedicated for data and control channels, respectively, as specified in the 3GPP standard, using digital signal processing (DSP)-assisted frequency division multiple access (FDMA) and time division multiple access (TDMA) channel aggregation techniques on an analogue radio-over-fiber (A-RoF) architecture. We verified that there is ~34% spectral efficiency gain and lower error vector magnitude (EVM) achieved using the TDMA technique
Upstream and Downstream Analysis of an Optical Fronthaul System Based on DSP-Assisted Channel Aggregation
Full text linkAbstract:
In this paper,we focus on a well-known optical fronthauling architecture based on frequency division multiplexed digital signal processing (DSP)-assisted channel aggregation, and we present new results related to the optimization of the optical setup, proposing an efficient technique for the optimization of the transmission. In particular, we report an original pre-emphasis technique to equalize the performance of the radio channels, especially focusing on the upstream (US) link that has more critical characteristics but has not typically been treated in detail in previous works on this topic. The effects of both radio and optical impairments on the error vector magnitude (EVM) are taken into account. An analytical description of our approach is provided, and then it is applied on an experimental setup (able to aggregate up to 96 20-MHz radio signals), showing the possibility of minimizing the maximum EVM at the output of the fronthauling link, for both downstream and US transmission. Additionally, a low complexity technique to practically estimate the EVM per channel by taking advantage of only the DSPaggregation/deaggregation functionalities is proposed and, again, experimentally demonstrated
Optimization of band-limited DSP-aided 25 and 50 Gbps PON using 10G-class DML and APD
Full text linkThe increasing demand for network capacity is driving the development of next-generation high-speed Passive Optical Networks (PON) supporting 25 and 50 Gbps. One solution to reduce transceiver cost is reusing the 10G-class optical transmitter (including Directly Modulated Lasers, DML, in O-band) and receiver components in combination with Digital Signal Processing (DSP) techniques to compensate for bandwidth limitations. In this paper, by means of both a set of laboratory experiments and a metropolitan field demonstrator, we discuss practical PON solutions at 25 and 50 Gbps per wavelength and per direction. In terms of modulation formats, we compare 2-level pulse amplitude modulation (PAM-2), 4-level PAM (PAM-4) and electrical duobinary (EDB) modulation formats, with feed-forward (FFE) and decision-feedback (DFE) adaptive equalizer at the receiver side. The novelty of our paper is manifold. First, we present an optimization in terms of optical receiver band requirements for the 50 Gbps transmission.We show, by means of experimental measurements and numerical simulations, the minimum required bandwidth for DML laser and APD receiver (with appropriate DSP techniques) to realize next generation 25 and 50 Gbps PON transceivers. Second, we discuss also the upstream point of view, with a specific focus on DSP, and in particular, we propose an experimental solution based on a burst mode receiver with memory-aided DSP technique, together with a novel DSP approach to overcome the typical AC coupling distortion due to the burst mode scenario. Finally, we show a coexistence experiment between XGS-PON and 25 Gbps PON on an installed metropolitan field trial
Current Trends towards PON systems at 50+ Gbps
Full text linkNext generation PON targeting 50 Gbit/s/lambda (50G-PON) based on intensity modulation and direct detection (IM-DD) will likely be under strong bandwidth limitations. We present a PAM-2 and Electrical DuoBinary performance analysis of 50 Gbps PON system by using 25G and 50G transceivers technology with several optical receiver architectures and study of the adaptive equalization impact
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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