| 1. |
- Acatauassu, Diogo, et al.
(författare)
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Experimental evaluation of fourth generation DSL in different DSM scenarios
- 2011
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Ingår i: [Host publication title missing]. - 9781467302777
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Konferensbidrag (refereegranskat)abstract
- Recently, the industry and the academy started to discuss the development of the fourth generation DSL systems. For example, within this context, ITU started working in G. fast DSL standard. A trend in this new generation is to increase the end-user bit rates by extending the frequency rage of transmission signals and reducing the copper loop length. For the frequency range being considered for use in G. fast for example, crosstalk is an even worse impairment than it is for current DSL deployments. Hence, it is sensible to study dynamic spectrum management (DSM) techniques to overcome the crosstalk effects. This work presents an experimental evaluation in order to verify the behavior of fourth generation DSL systems when different levels of DSM techniques are used, highlighting the coexistence of vectored, DSM level 3, and non-vectored sub-systems. The results were obtained based on short copper cable measurements and power spectrum density simulations.
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| 2. |
- Acatauassu, Diogo, et al.
(författare)
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KHM cable model parameters for ITU-T G.Fast reference loops
- 2016
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Ingår i: 2015 IEEE Conference on Standards for Communications and Networking, CSCN 2015. - 9781479989287 ; , s. 168-173
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Konferensbidrag (refereegranskat)abstract
- G.Fast is a new standard for fixed broadband access that aims at achieving bit rates of 1 Gb/s over short copper loops. In order to give support to simulation, design and performance evaluation tests, the G.Fast recommendation presents examples of some wiring topologies and reference loops describing configurations expected to be found in real G.Fast deployments. Our work describes results of modeling some types of lines adopted in these reference loops by means of a low complexity and causal parametric cable model. The results indicate that the modeling approach proposed in this work is accurate for all the analyzed cases, which include high quality, medium quality and low quality cables.
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| 3. |
- Acatauassu, Diogo, et al.
(författare)
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Simple and Causal Copper Cable Model Suitable for G.fast Frequencies
- 2014
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Ingår i: IEEE Transactions on Communications. - 0090-6778. ; 62:11, s. 4040-4051
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Tidskriftsartikel (refereegranskat)abstract
- G.fast is a new standard from the International Telecommunication Union, which targets 1 Gb/s over short copper loops using frequencies up to 212 MHz. This new technology requires accurate parametric cable models for simulation, design, and performance evaluation tests. Some existing copper cable models were designed for the very high speed digital subscriber line spectra, i.e., frequencies up to 30 MHz, and adopt assumptions that are violated when the frequency range is extended to G.fast frequencies. This paper introduces a simple and causal cable model that is able to accurately characterize copper loops composed by single or multiple segments, in both frequency and time domains. Results using G.fast topologies show that, apart from being accurate, the new model is attractive due to its low computational cost and closed-form expressions for fitting its parameters to measurement data.
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| 4. |
- Acatauassu, Diogo, et al.
(författare)
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Simple and Causal Twisted-Pair Channel Models for G.fast Systems
- 2013
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Ingår i: [Host publication title missing].
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Konferensbidrag (refereegranskat)abstract
- The use of a hybrid copper and fiber architecture is attractive in both fixed access and mobile backhauling scenarios. This trend led the industry and academia to start developing the fourth generation broadband system, which aims at achieving bitrates of 1 Gbps over short copper loops. In this context, accurate models of short twisted-pair cables operating at relatively high frequencies are key elements. This work describes new parametric cable models that incorporate four important characteristics: support of frequencies up to 200 MHz, few parameters, causal impulse responses and require relatively easy fitting procedures. The results show that the models achieve good accuracy for single segments, which are the expected topology for G.fast deployments.
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| 5. |
- Brito, Flavio, et al.
(författare)
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Compression of Activation Signals from Split Deep Neural Network
- 2022
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Ingår i: 2022 IEEE Latin-American Conference on Communications, LATINCOM 2022. - 9781665482257
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Konferensbidrag (refereegranskat)abstract
- The use of artificial neural networks for the purpose of image classification, together with the advancement in computational capabilities of edge devices, plays an important role in the new emerging 5G use case scenarios. However, one of the main challenges of applications involving the use of these networks in edge devices is still the limitation of computational resources. An alternative for saving resources and promoting privacy are the split learning (or split inference) techniques, in which a deep neural network is cut into two parts and executed in distinct devices. Most of these techniques rely on sending the activation signals (output of the cut layer) through the communication channel. This work proposes a new compression algorithm for decreasing the bit rate required for the transmission of the activation signals (or simply 'scores'). The presented results demonstrate that the transmission rate can be decreased without hurting the neural network accuracy.
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| 6. |
- Fonseca, Maria Nilma, et al.
(författare)
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DCT-based compression scheme for OFDM baseband signals
- 2018
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Ingår i: 2018 Wireless Days, WD 2018. - 9781538656327 ; 2018-April, s. 92-97
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Konferensbidrag (refereegranskat)abstract
- The requirements on the data rates of communication systems increase roughly an order of a magnitude at each new generation. This increase can be especially noticeable for the new centralized radio access networks (C-RAN) scenarios, considered for meeting the requirements of the fifth generation (5G) wireless systems. The general C-RAN architecture normally assumes data transmission in the form of digitized baseband, i.e. I/Q samples. This paper proposes a relatively low-complexity compression scheme for LTE OFDM baseband samples based on transform coding, using the discrete cosine transform (DCT). The compression method is evaluated in both downlink and uplink. The results show that this process can be configured to achieve compression ratio according with the load, for example, in the range of 5:1 to 31:1, with error vector magnitudes (EVMs) lower than 2.8%.
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| 7. |
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| 8. |
- Gomes, Ana, et al.
(författare)
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An hybrid evolutionary multiobjective algorithm for multiuser margin maximization in DSL
- 2016
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Ingår i: International Journal of Communication Systems. - : Wiley. - 1074-5351. ; 29:1, s. 194-209
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Tidskriftsartikel (refereegranskat)abstract
- This work describes and proposes the application of evolutionary algorithms on the multiuser spectrum and SNR margin optimization problem for multicarrier systems, such as digital subscriber line. The proposed method is designed such that it takes advantage of special characteristics of the well-known power adaptation techniques and uses them to solve the broader and more challenging problem of multiuser margin adaptation. Simulations show that the proposed method provides Pareto-optimal and diverse solutions when compared to a previous method to solve the same problem. Copyright (c) 2014 John Wiley & Sons, Ltd.
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| 9. |
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| 10. |
- Gomes, Diego, et al.
(författare)
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Mitigation of Alien Crosstalk for Downstream DSL Impaired by Multiple Interferers
- 2017
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Ingår i: IEEE Communications Letters. - 1089-7798.
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Tidskriftsartikel (refereegranskat)abstract
- Alien crosstalk is one of the major impairments for copper-based transmissions. This letter outlines a method for mitigating alien crosstalk for DSL downstream transmissions impaired by multiple interference sources. The method requires a reference channel, and includes a post processing stage in which induced correlation is applied to prepare the interference at the target channel to be reasonably removed by a prediction based mitigation step. The results show that the proposed method outperforms published alien crosstalk mitigation methods as the number of interference sources increase in G.fast scenarios.
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