| 1. |
- Huang, Yezi, et al.
(författare)
-
Enabling DSL and Radio on the Same Copper Pair
- 2015
-
Ingår i: 2015 IEEE International Conference on Communications (ICC). - 9781467364324 ; , s. 1031-1035
-
Konferensbidrag (refereegranskat)abstract
- To increase indoor coverage for mobile services, we propose a residential small cell infrastructure making use of the existing copper plant. The system is cabinet-based, collocated with VDSL2 and uses small pieces of spectrum next to VDSL2. Inspired by the Ericsson Radio Dot System, it challenges the femtocell paradigm offering full macro functionality in the small cells. An interesting service potential is offered albeit the added mobile traffic capacity is moderate as it is limited by the copper fronthaul.
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| 2. |
- Huang, Yezi, et al.
(författare)
-
LTE Over Copper - Potential and Limitations
- 2015
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Ingår i: 2015 IEEE 26th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC). - 9781467367820 ; , s. 1339-1343
-
Konferensbidrag (refereegranskat)abstract
- The densification of mobile networks in order to meet increased capacity demands is ongoing, needed and costly. A few papers have been published based on the insight that the fixed broadband networks offer a multitude of sites, for instance our homes, for potential small cell deployment providing backhaul capacity and power without site costs. However, in order to reach economical large-scale benefits, we explore the case when radio systems are deployed in coexistence with DSL. In this paper, we establish the feasibility of such a concept under constraints invoked by state-of-the-art and emerging systems (3GPP, VDSL2 and G.fast) and make statements about the required architecture. We also point out that the enthusiasm of previously published results should be lowered a notch.
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| 3. |
- Huang, Yezi, et al.
(författare)
-
Time-Domain Precoding for LTE-over-Copper Systems
- 2016
-
Ingår i: 2016 IEEE International Conference on Communications (ICC). - 9781479966646 - 9781479966653 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Crosstalk cancellation is a crucial issue for traditional digital subscriber line systems. For LTE-over-copper systems, however, the need for crosstalk cancellation varies depending on the analog fronthauling architecture and its parameters. A crosstalk handler that is decoupled as much as possible from the rest of the system architecture is thus preferred. Therefore, we propose a time-domain precoding scheme specifically in downstream direction to separate the precoding unit from the LTE signal flow, and perform crosstalk cancellation in an on-demand manner. Estimation of all direct and crosstalk paths is assisted by LTE cell-specific reference signals. The time-domain precoder transforms the interference channel into a crosstalk-free channel with identical direct paths, which allows for low-complexity inter-symbol interference mitigation. We evaluate the concept in terms of signal-to-noise ratio provided for LTE signals using measured wireline channel data.
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| 4. |
- Medeiros, Eduardo, et al.
(författare)
-
Crosstalk Mitigation for LTE-over-Copper in Downlink Direction
- 2016
-
Ingår i: IEEE Communications Letters. - 1089-7798. ; 20:7, s. 1425-1428
-
Tidskriftsartikel (refereegranskat)abstract
- Radio-over-copper is a niche idea that has potential to become a cornerstone in the deployment of dense 5G networks. We address one of the remaining hurdles and present an architecture for transparent crosstalk mitigation in LTE-over-copper systems. By taking advantage of reference symbols present in the downlink LTE signals we propose two methods for estimating the copper channel. System performance is evaluated using channel measurements and error vector magnitude calculations with promising results.
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| 5. |
- Acatauassu, Diogo, et al.
(författare)
-
KHM cable model parameters for ITU-T G.Fast reference loops
- 2016
-
Ingår i: 2015 IEEE Conference on Standards for Communications and Networking, CSCN 2015. - 9781479989287 ; , s. 168-173
-
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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| 6. |
- Andgart, Niklas, et al.
(författare)
-
Designing tone reservation PAR reduction
- 2006
-
Ingår i: Eurasip Journal on Applied Signal Processing. - 1110-8657.
-
Tidskriftsartikel (refereegranskat)abstract
- Tone reservation peak-to-average ( PAR) ratio reduction is an established area when it comes to bringing down signal peaks inmulticarrier (DMT or OFDM) systems. When designing such a system, some questions often arise about PAR reduction. Is it worth the effort? How much can it give? How much does it give depending on the parameter choices? With this paper, we attempt to answer these questions without resolving to extensive simulations for every system and every parameter choice. From a specification of the allowed spectrum, for instance prescribed by a standard, including a PSD-mask and a number of tones, we analytically predict achievable PAR levels, and thus implicitly suggest parameter choices. We use the ADSL2 and ADSL2+ systems as design examples.
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| 7. |
- Andgart, Niklas, et al.
(författare)
-
PSD-constrained PAR reduction for DMT/OFDM
- 2004
-
Ingår i: Eurasip Journal on Applied Signal Processing. - 1110-8657. ; 2004:10
-
Tidskriftsartikel (refereegranskat)abstract
- Common to all DMT/OFDM systems is a large peak-to-average ratio (PAR), which can lead to low power efficiency and nonlinear distortion. Tone reservation uses unused or reserved tones to design a peak-canceling signal to lower the PAR of a transmit block. In DMT ADSL systems, the power allocated to these tones may be limited due to crosstalk issues with many users in one twisted pair bundle. This PSD limitation not only limits PAR reduction ability, but also makes the optimization problem more challenging to solve. Extending the recently proposed active set tone reservation method, we develop an efficient algorithm with performance close to the optimal solution.
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| 8. |
- Börjesson, Per Ola, et al.
(författare)
-
A low-complexity PAR-reduction method for DMT-VDSL
- 1999
-
Ingår i: Proceedings of the 5th International Symposium on Digital Signal Processing for Communication Systems. ; , s. 164-169
-
Konferensbidrag (refereegranskat)abstract
- DMT-VDSL signals have a high peak-to-average power ratio (PAR). In the transmitters, the PAR governs the necessary resolution of the digital-to-analog converter (DAC) and is an important factor for the power consumption of the line-driver. Aiming at implementation in a specific system, we propose a low complexity PAR-reduction method based on the iterative algorithm derived in [5, 20, 24, 25]. We maintain good performance while stressing a straigthforward and low-complex implementation. Key elements of the method are: low latency; no loss in data rate; precalculated and stored peak-cancellation waveform; and bit-shifts (multiplication with powers of two) replacing the scaling of the waveform. Computer simulations show that, for a DMT frame length of 4096 samples and a frame clip rate of 10-4, the PAR can be reduced about 1.5 to 2.0 dB, depending on the number of peaks cancelled. When multiplication is replaced by bit-shifts, the reduction is still 1.5-1.7 dB.
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| 9. |
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| 10. |
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| 11. |
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| 12. |
- Börjesson, Per Ola, et al.
(författare)
-
Free-riding in Group Work - Mechanisms and Countermeasures
- 2006
-
Ingår i: [Host publication title missing].
-
Konferensbidrag (refereegranskat)abstract
- Studies have shown that group work offers great possibilities for deeper learning compared to some more traditional teaching formats [1], but it can also lead to some new problems such as free-riding. Different aspects of group psychology and behaviour as well as impropriate group sizes can be used to explain why and how free-riding develops in groups. With careful course planning teachers can seriously discourage students from free-riding. Especially the grading system should be carefully chosen not to promote free-riding but to stimulate deeper learning
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| 13. |
- Eriksson, Håkan, et al.
(författare)
-
A robust correlation receiver for distance estimation
- 1994
-
Ingår i: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - New York : Institute of Electrical and Electronics Engineers (IEEE). - 0885-3010 .- 1525-8955. ; 41:5, s. 596-603
-
Tidskriftsartikel (refereegranskat)abstract
- Many methods for distance estimation, such as the ultrasonic pulse-echo method, involve the estimation of a time-of-flight (TOF). In this paper, a signal model is developed that, apart from the TOF, accounts for an unknown, linear frequency dependent distortion as well as for additive noise. We derive a TOF estimator for this model based on the criteria of maximum likelihood. The resulting receiver can be seen as an extension or generalization of the well known cross-correlation, or "matched filter", estimator described, e.g., by Nilsson. The novel receiver is found to be more robust against unknown pulse shape distortion than the cross-correlation estimator, giving less biased TOF estimates. Also, bias versus noise sensitivity can be controlled by proper model order selection
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| 14. |
- Eriksson, Håkan B., et al.
(författare)
-
A genie-aided detector with a probabilistic description of the side information
- 1995
-
Ingår i: Proceedings. - Piscataway, NJ : IEEE Communications Society. - 0780324536 ; , s. 332-
-
Konferensbidrag (refereegranskat)abstract
- Building on Forney's concept of the genie (1972), and introducing the idea of an explicit statistical description of the side information provided to the genie-aided detector, we develop a generic tool for derivation of lower bounds on the bit-error rate of any actual receiver. With this approach, the side information statistics become design parameters, which may be chosen to give the resulting bound a desired structure. To illustrate this, we choose statistics in order to obtain a special case: the lower bound derived by Mazo (1975). The statistical description of the side information makes the lower bounding a transparent application of Bayesian theory
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| 15. |
- Eriksson, Håkan B., et al.
(författare)
-
Simultaneous time of flight and channel estimation using a stochastic channel model
- 1993
-
Ingår i: Radiovetenskaplig konferens på Lunds tekniska högskola 5-7 april 1993. - Lund : Lunds tekniska högskola. ; , s. 43-46
-
Konferensbidrag (refereegranskat)abstract
- In this paper we address the problem of estimating the Time-of-Flight of a transmitted signal when the shape of the received waveform is stochastic. Specifically, we examine the case when the transmission system model is stochastic, linear and time discrete, with additive Gaussian noise, and where the transmitted waveform is known to the receiver. The joint estimation is couched in terms of Maximum a Posteriori (MAP) and Maximum Likelihood estimation. When deriving the MAP estimator we assume a priori knowledge of the probability density of the transmission system impulse response. The MAP estimator is then compared to estimators derived using less a priori information and lower order system models. The ordinary correlation based Time-of-Flight estimator assumes knowledge of the received waveform, that is has a one-dimensional transmission system model. This investigation indicates that a more complex model structure is worthwhile when distortion in excess of low additive noise is present.
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| 16. |
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| 17. |
- Huang, Yezi, et al.
(författare)
-
Mitigating Disorderly Leaving Events in G.fast
- 2015
-
Ingår i: 2015 IEEE International Conference on Communications (ICC). ; , s. 939-944
-
Konferensbidrag (refereegranskat)abstract
- Vectoring is a vital component of wideband wire- line communication systems. A disorderly leaving event (DLE) disturbs the vectoring operation since the precoder, which was designed for the channel before the change, is no longer up to date. Measurements indicate that the impact of a DLE can be serious for frequencies beyond 30 MHz, which corresponds to the band used by emerging wideband communication systems over short multi-pair copper cables such as G.fast. As an alternative to the state-of-the-art update procedure, this paper presents an approach to mitigating the DLE problem. By interpreting DLE with the FEXT-reflected-NEXT (FRN) model, we propose a scheme that enables the showtime lines to return to disturbance-free transmission once the loss of signal on a certain line is detected while updating the precoder as a background process. Furthermore, the estimation complexity for a K-user vectoring group is reduced from O(K^2) to O(K).
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| 18. |
- Huang, Yezi, et al.
(författare)
-
Rate-Boosting Using Strong Crosstalk in Next Generation Wireline Systems
- 2016
-
Ingår i: 2015 IEEE Global Communications Conference (GLOBECOM). - 9781467395267 ; , s. 1-6
-
Konferensbidrag (refereegranskat)abstract
- Next-generation wireline systems may exploit fre- quencies up to several hundred MHz on short lines. Strong crosstalk coupling, comparable to the direct paths, is one of the main channel characteristics at high frequencies. Instead of fully cancelling all crosstalk, we utilize strong crosstalk paths to boost data-rate for active users. Two linear precoding schemes, based on maximum ratio-combining (MRC) and convex optimization, respectively, are proposed and applied to a common network topology. The precoding schemes exploit constructive crosstalk signals on unused lines or in unused parts of the spectrum on neighboring lines to boost data-rate while still complying with the regulated spectral power limits per line. More than 500 Mbps throughput gain per active user can be achieved compared to state-of-the-art linear precoding.
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| 19. |
- Isaksson, Mikael, et al.
(författare)
-
Zipper - a flexible duplex method for VDSL
- 1997
-
Ingår i: Proceedings of International Conference on Copper Wire Access Systems. ; , s. 95-99
-
Konferensbidrag (refereegranskat)abstract
- A novel duplex scheme for DMT-based VDSL systems on copper wire pairs is introduced. This method, named Zipper, uses different subcarriers in opposite transmission directions to divide the available bandwidth between the two directions. It provides exceptional versatility when it comes to dividing capacity between up and downstream. The scheme has high duplex efficiency, low latency, and most importantly good coexistence possibilities with other systems such as ADSL.
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| 20. |
- Landström, Daniel, et al.
(författare)
-
Symbol time offset estimation in coherent OFDM systems
- 1999
-
Ingår i: IEEE International Conference on Communications. - Piscataway, NJ : IEEE Communications Society. - 078035284X ; , s. 500-505
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Konferensbidrag (refereegranskat)abstract
- This paper presents a symbol time offset estimator for coherent OFDM systems. This estimator exploits both the redundancy in the cyclic prefix and the pilot symbols used for channel estimation. The estimator is robust against frequency offsets and is suitable for use in dispersive channels. We base the estimator on the ML estimator for the AWGN channel. Simulations of an example system indicate a system performance as close as 0.3 dB to a perfectly synchronized system. Compared to an estimator not using pilots, our estimator's performance could allow a shorter cyclic prefix and thus a more spectrally efficient system.
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| 21. |
- Landström, Daniel, et al.
(författare)
-
Symbol time offset estimation in coherent OFDM systems
- 2002
-
Ingår i: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778. ; 50:4, s. 545-549
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a symbol time offset estimator for coherent orthogonal frequency division multiplexing (OFDM) systems. The estimator exploits both the redundancy in the cyclic prefix and available pilot symbols used for channel estimation. The estimator is robust against frequency offsets and is suitable for use in dispersive channels. We base the estimator on the maximum-likelihood estimator for the additive white Gaussian noise channel. Simulations for an example system indicate a system performance as close as 0.6 dB to a perfectly synchronized system.
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| 22. |
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| 23. |
- Landström, Daniel, et al.
(författare)
-
Time and frequency offset estimation in OFDM systems employing pulse shaping
- 1997
-
Ingår i: Bridging the way to the 21st century. - Piscataway, NJ : IEEE Communications Society. - 0780337778 ; , s. 279-283, s. 279-283
-
Konferensbidrag (refereegranskat)abstract
- Time and frequency offset estimation is addressed in an OFDM system that uses a cyclic prefix and pulse shaping. Earlier work has presented a method that avoids the use of pilots by exploiting the inherent correlation in the cyclically extended OFDM symbol. In this paper this technique is extended to include systems with pulse shaping. The joint Maximum Likelihood estimator of time and frequency offsets for such systems is presented and evaluated. An implementable structure of the extended estimator is given. Simulations show that it is possible to maintain the performance when introducing pulse shaping into an OFDM system.
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| 24. |
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| 25. |
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| 26. |
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| 27. |
- Lindqvist, Fredrik, et al.
(författare)
-
Estimation of Nonhomogeneous and Multi-Section Twisted-Pair Transmission-Line Parameters
- 2015
-
Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480. ; 63:11, s. 3568-3578
-
Tidskriftsartikel (refereegranskat)abstract
- In emerging and future copper access networks, the trend goes towards exploiting higher transmission bandwidths on shorter twisted-pair cables. Methods to accurately determine relevant transmission-line parameters are a prerequisite to exploit the potential of these short-to-medium range access lines. In this paper, we propose a model-based space-frequency optimization approach initially developed for microwave applications. By utilizing the concept of capacitive length, two major advances are achieved. First, we overcome the requirement of a priori information of physical line length. Second, the number of parameters is reduced compared to prior art. We introduce two estimators to illustrate the concept. A low-complexity estimator with only two parameters per spatial unit primarily targets higher frequencies. A wideband estimator with three parameters per spatial unit extends to the lower frequencies used by operational digital subscriber line services. Performance and limitations of the approach are illustrated by both computer simulations and measurements.
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| 28. |
- Lindqvist, Fredrik, et al.
(författare)
-
Low-order and causal twisted-pair cable modeling by means of the Hilbert transform
- 2008
-
Ingår i: AIP Conference Proceedings. - : AIP. ; , s. 301-310
-
Konferensbidrag (refereegranskat)abstract
- A new low-order and causal twisted-pair cable model for the copper access network is derived. From the serial resistance of the widely used, but non-causal, BT0 model, the serial inductance is computed via the Hilbert transform. By doing so, a causal cable model is obtained containing fewer parameters compared to the BT0 model. The deviation between the two models is evaluated for the standardized ETSI cables.
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| 29. |
- Magesacher, Thomas, et al.
(författare)
-
A fair comparison of transmitter-based spectral shaping techniques
- 2006
-
Ingår i: 11th International OFDM-Workshop (InOWo'06).
-
Konferensbidrag (refereegranskat)abstract
- This paper addresses multicarrier communications over the additive white Gaussian noise channel under a power spectral density (PSD) constraint. Depending on the shape of the PSD mask, straightforward power loading according to the waterfilling principle may yield poor throughput results. Several information processing techniques have been proposed to enhance the spectral properties of a multicarrier transmit signal and consequently increase the resulting throughput. Two promising spectral shaping techniques that require information processing exclusively in the transmitter are spectral compensation and intersymbol transmit windowing. This work presents prerequisites for a fair comparison and a performance assessment of these techniques
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| 30. |
- Magesacher, Thomas, et al.
(författare)
-
Adaptive Interference Cancellation Using Common-Mode Information in DSL
- 2005
-
Ingår i: Proc. European Signal Processing Conference 2005.
-
Konferensbidrag (refereegranskat)abstract
- Exploiting the common-mode (CM) receive signal in wireline communication can yield significant improvements in terms of channel capacity compared to using only the differential-mode (DM) signal. Recently published, independent, scientific work proposed the employment of an adaptive CM-reference based interference canceller and reported performance improvements based on simulation results. Adaptive processing of correlated receive signals, however, bears the potential danger of cancelling the useful component—an undesired effect we will address. We present an analysis of the linear adaptive cancellation approach in this application. For a large class of practically relevant cases, it can be shown that a canceller, whose coefficients are adapted while the far-end transmitter is silent, yields a signal-tonoise-and-interference power ratio (SNIR) which is higher than the SNIR of the DM-only channel output. Moreover, the performance of a canceller with this tap-setting is close to the performance of the front-end that is optimum in the sense of maximising the SNIR at its output. Adaptation while the useful far-end signal is present yields a front-end whose output SNIR is considerably lower compared to the SNIR of the DM channel output. The results and their practical impact are demonstrated by an example.
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| 31. |
- Magesacher, Thomas, et al.
(författare)
-
An adaptive mixed-signal narrowband interference canceller for wireline transmission systems
- 2001
-
Ingår i: The 2001 IEEE International Symposium on Circuits and Systems, ISCAS 2001.. - 0780366859 ; , s. 450-453
-
Konferensbidrag (refereegranskat)abstract
- Narrowband radio transmitters like radio amateurs and broadcast radio stations are considered to be a serious problem for high-bitrate data transmission over twisted pairs. Due to its high power level, radio frequency interference (RFI) has the potential of overloading the receiver's analog-to-digital converter (ADC). Once the ADC is in saturation, any countermeasure taken in the digital domain will fail, so the problem has to be faced at least partly in the analog domain. This paper proposes an adaptive, mixed-signal, narrowband interference canceller employing a modified recursive least-squares (RLS) algorithm which is split into an analog and a digital part. The mixed-signal approach enables the circuit to generate an interference-cancelling signal of several MHz while operating the adaptive algorithm at some kHz. The structure is fast enough to prevent the ADC from overloading due to radio amateur interference, thus protecting the data transmission from interruption. Simulation results as well as measurements indicate a practical disturbance rejection potential of about 40-50 dB
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| 32. |
- Magesacher, Thomas, et al.
(författare)
-
Analysis of Adaptive Interference Cancellation Using Common-Mode Information in Wireline Communications
- 2007
-
Ingår i: Eurasip Journal on Advances in Signal Processing. - : Springer Science and Business Media LLC. - 1687-6172 .- 1687-6180.
-
Tidskriftsartikel (refereegranskat)abstract
- Joint processing of common-mode (CM) and differential-mode (DM) signals in wireline transmission can yield significant improvements in terms of throughput compared to using only the DM signal. Recent work proposed the employment of an adaptive CM-reference-based interference canceller and reported performance improvements based on simulation results. This paper presents a thorough investigation of the cancellation approach. A subchannel model of the CM-aided wireline channel is presented and the Wiener solutions for different adaptation strategies are derived. It is shown that a canceller, whose coefficients are adapted while the far-end transmitter is silent, yields a signal-to-noise power ratio (SNR) that is higher than the SNR at the DM channel output for a large class of practically relevant cases. Adaptation while the useful far-end signal is present yields a front-end whose output SNR is considerably lower compared to the SNR of the DM channel output. The results are illustrated by simulations based on channel measurement data.
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| 33. |
- Magesacher, Thomas, et al.
(författare)
-
Capacity of the swedish copper access network
- 2005
-
Ingår i: Proceedings of RVK 05 RadioVetenskap och Kommunikation.
-
Konferensbidrag (refereegranskat)abstract
- This paper aspires to indicate how much broadband communication the Swedish copper access network can offer when developed to its full potential. We look at a number of different infrastructure deployment scenarios and calculate the Shannon capacity of the copper loops using different deployment-dependent loop-length distributions with different deployment-dependent and technology-dependent noise models. We investigate both deployment from the central-office and from the cabinet. We consider non-cooperative scenarios, where the deployment is carried out system by system following only the mandatory standardised rules and every line is operated autonomously without cooperation of transceivers. We also investigate scenarios with mechanisms for better exploitation of the access plant through dynamic spectral management, multiple-input multiple-output techniques, and common-mode aided interference suppression. The choice of elementary parameters, like transmit power and background noise, is based on today’s digital subscriber line (DSL) standards. Statistical models are used for the main parameters of the network topology. Note that we are not calculating a capacity in an information theoretic sense, but rather a data rate under given constraints.
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| 34. |
- Magesacher, Thomas, et al.
(författare)
-
Exploiting the Common-Mode Signal in xDSL
- 2004
-
Ingår i: 12th European Signal Processing Conference, EUSIPCO 2004. - 9783200001657 ; , s. 1217-1220
-
Konferensbidrag (refereegranskat)abstract
- Communication over the copper twisted-pair channel is performed by transmitting and receiving differential-mode (DM) signals. In this paper, we extend the conventional DM receive scheme by incorporating the common-mode (CM) signal, which can be extracted at the end of every wire pair. We assess the potential of this idea for digital subscriber line systems (xDSL) in terms of channel capacity using channel measurement data. We show that especially those scenarios that suffer strong interference benefit most from joint DM-CM processing, since the interference at the DM port is strongly correlated with the interference at the CM port in these cases. Numerical evaluation of VDSL example scenarios shows that the capacity of the twisted-pair channel when using also the CM signal can exceed the capacity of the conventional DM channel by a factor of up to three.
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| 35. |
- Magesacher, Thomas, et al.
(författare)
-
Information rate bounds in common-mode aided wireline communications
- 2006
-
Ingår i: European Transactions on Telecommunications. - : Wiley. - 1541-8251 .- 1124-318X. ; 17:5, s. 533-545
-
Tidskriftsartikel (refereegranskat)abstract
- Communication over the copper twisted-pair channel is performed by transmitting and receiving differential-mode (DM) signals. In this paper, we extend the conventional DM receiver scheme by incorporating the common-mode (CM) signal, which is strongly correlated with the DM signal and can be extracted at the end of every wire pair. The wireline channel, including the CM receive signal, is modelled as a Gaussian vector (multiple-input multiple-output) channel with memory and an arbitrary number of disturbers that introduce interference which can be correlated both temporally and spatially. We investigate the potential of CM-aided reception in terms of information rate for single-user digital subscriber line systems (xDSL) operating on a single pair. Numerical results of information rate calculations using measured channel data are presented. The achievable information rate of the twisted-pair channel when incorporating the CM signal in practically relevant example scenarios can exceed the information rate of the conventional DM channel by a factor of up to two. Copyright (C) 2005 AEIT.
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| 36. |
- Magesacher, Thomas, et al.
(författare)
-
Limits of Ultra-Wideband Communication Over Copper
- 2006
-
Ingår i: Proc. Intl. Conference on Communication Technology (ICCT) 2006. - 1424408016 ; , s. 1437-1440
-
Konferensbidrag (refereegranskat)abstract
- Wireline communication using the copper plant is one of the major access techniques. The shorter the wires, the larger is the frequency band that can be exploited in an economically feasible way. Several technologies using frequency bands up to 30MHz have been standardized during the last decade. Properties of the wireline channel for frequencies above 30MHz are to a large extent unexplored. This paper investigates the limits of "ultra-wideband" communication over very short copper cables in terms of exploitable bandwidth and data rate. Extrapolations of standard cable models, whose validity has been verified by means of measurements, are used for channel modeling. The CISPR 22 standard forms the basis for the analysis of ingress and egress.
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| 37. |
- Magesacher, Thomas, et al.
(författare)
-
Measurement and modeling of short copper cables for ultra-wideband communication
- 2006
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 6390, s. 39006-39006
-
Konferensbidrag (refereegranskat)abstract
- High-speed communication using the copper network, originally installed for telephony, is one of the dominant Internet access techniques. Several variants of a technology referred to as digital subscriber line (DSL) have been developed, standardized and installed during the last two decades. Essentially, DSL achieves high rates by exploiting wide bands of the copper cable channel. The shorter the cable, the wider the band that can be used efficiently for communication. Current DSL standards foresee the use of bands up to 30MHz. Cable properties have been studied by means of measurements, characterization and modeling up to frequencies of 30MHz. Recent investigations have shown that it is feasible both from technical and from economical point of view to exploit very short cables (up to 200m) even further and use bands above 30MHz. A prerequisite for further evaluation and the design of such ultra-wideband copper (UWBC) systems is the extension of existing cable models to higher frequencies. This paper presents wideband measurement results of insertion loss and crosstalk coupling in a 10-pair cable of various length values for frequencies up to 200MHz. We compare the results with extrapolations of cable models that are established in the 30MHz-range.
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| 38. |
- Magesacher, Thomas, et al.
(författare)
-
Modeling and measurement of short copper cables for ultra-wideband communications
- 2006
-
Ingår i: Proc. SPIE OpticsEast Broadband Access Communication Technologies.
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Konferensbidrag (refereegranskat)abstract
- High-speed communication using the copper network, originally installed for telephony, is one of the dominant Internet access techniques. Several variants of a technology referred to as digital subscriber line (xDSL) have been developed, standardized and installed during the last two decades. Essentially, xDSL achieves high rates by exploiting wide bands of the copper cable channel. The shorter the cable, the wider is the band that can be used efficiently for communication. Current xDSL standards use bands up to 18MHz. Cable properties have been studied by means of measurements, characterization and modeling up to frequencies of 30MHz. Recent investigations have shown that is feasible both from technical and from economical point of view to exploit very short cable (up to 300m) even further and use bands above 30MHz. A prerequisite for further evaluation and the design of such ultra-wideband copper (UWBC) systems is the extension of existing cable models to higher frequencies. This paper presents wide-band measurement results of insertion loss and crosstalk coupling in a 10-pair cable of various length values for frequencies up to 400MHz. We compare the results to extrapolations of cable models that are established in the 30MHzrange.
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| 39. |
- Magesacher, Thomas, et al.
(författare)
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On the Capacity of the Copper Cable Channel Using the Common Mode
- 2002
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Ingår i: IEEE Global Telecommunications Conference GLOBECOM '02.. - 0780376323 ; 2, s. 1269-1273
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Konferensbidrag (refereegranskat)abstract
- The common-mode (CM) signal in wireline transmission systems has proven to provide valuable information exploited for mitigating narrowband noise at the receive side. We focus on the case of broadband noise. Treating the CM signal as an additional receive signal, we investigate the capacity of the copper cable channel for different levels of coordination among the users. We introduce a channel model which includes the common-mode paths and derive a suitable form of the channel capacity formula. CM crosstalk measurement results, essential for evaluation of the channel capacity, are presented. Using the measurement data, exemplary results of capacity gain achievable by CM-aided data transmission over the copper cable are shown.
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| 40. |
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| 41. |
- Magesacher, Thomas, et al.
(författare)
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Optimal intersymbol transmit windowing for multicarrier modulation
- 2006
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Ingår i: 2006 7th Nordic Signal Processing Symposium (IEEE Cat. No.06EX1392). - 1424404134 - 1424404126 ; , s. 70-73
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Konferensbidrag (refereegranskat)abstract
- Time-domain windowing of transmit blocks in multicarrier transmission is a technique frequently used to improve the properties of the transmit spectrum. An intersymbol window is longer than a multicarrier symbol including its cyclic extension. Before windowing, additional cyclic extensions at the beginning and at the end of each multicarrier symbol are introduced. Since the window only shapes these extended parts of each symbol, the orthogonality of the received basis functions is preserved. Most intersymbol transmit window designs exclusively focus on the spectral properties of the resulting basis functions. In this paper, we propose a window design that is optimal in the sense of maximising the information rate for a Gaussian channel with memory under power spectral density constraints and suggest some design guidelines
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| 42. |
- Magesacher, Thomas, et al.
(författare)
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Optimal intra-symbol spectral compensation for multicarrier modulation
- 2006
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Ingår i: International Zurich Seminar on Digital Communications. ; 2006, s. 138-141
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Konferensbidrag (refereegranskat)abstract
- Spectral compensation aims at maximising the throughput of a multicarrier transmission system under a given power spectral density (PSD) constraint. A set of carefully chosen tones, the so called compensation tones, is modulated with a linear combination of the data transmitted over the complementary set of tones. The compensation tones support shaping of the transmit PSD so that the overall transmit power and thus the throughput increase. The contribution of this paper is twofold. First, we compute the optimal solution for a given set of compensation tones - optimal in the sense of maximising the mutual information between transmit and receive blocks for a time-dispersive Gaussian channel known to the transmitter. Second, we present a low-complexity heuristic to find the set of compensation tones.
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| 43. |
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| 44. |
- Magesacher, Thomas, et al.
(författare)
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Splitting the Least-Mean-Square Algorithm
- 2002
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Ingår i: Proceedings of the 5th Nordic Signal Processing Symposium.
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Konferensbidrag (refereegranskat)abstract
- The least-mean-square (LMS) algorithm is an adaptation scheme widely used in practice due to its simplicity. In some applications the involved signals are continuous-time. Then, usually either a fully analog implementation of the LMS algorithm is applied or the input data are sampled by analog-to-digital (AD) converters to be processed digitally. A purely digital realization is most often the preferred choice, however, it becomes costly for high-frequency input signals since fast AD converters are needed. In this paper we propose a hybrid analog/digital approach allowing the AD conversion rate to be as low as the update-rate of the LMS algorithm. We demonstrate the advantage of this approach applying it to an interference cancellation problem occurring in wireline communications: the sampling rate of the AD converters is reduced by a factor of 250.
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| 45. |
- Magesacher, Thomas, et al.
(författare)
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Verification of multipair copper-cable model by measurements
- 2007
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - Piscataway, N.J. : IEEE Press. - 0018-9456 .- 1557-9662. ; 56:5, s. 1883-1886
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Tidskriftsartikel (refereegranskat)abstract
- Analysis, assessment, and design of advanced wire-line transmission schemes over multipair copper cables require accurate knowledge of the channel properties. This paper investigates modeling of multiconductor cables based on interpair impedance measurements. A unified approach to the application of the "Cioffi" model is introduced. The direct measurement approach of the underlying interpair impedances yields a good, match with the alternative approach suggested in the recent study of Cioffi et al. Crosstalk coupling functions derived from the model exhibit a good match with the corresponding direct measurements in the case in which the modeled length is close to the length of the interpair impedance measurements. However, the prediction power of this model,with respect to termination impedance is limited.
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| 46. |
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| 47. |
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| 48. |
- Medeiros, Eduardo, et al.
(författare)
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How Vectoring in G.fast May Cause Neighborhood Wars
- 2014
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Ingår i: [Host publication title missing]. - 9781479920037 ; , s. 3865-3870
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Konferensbidrag (refereegranskat)abstract
- Emerging wireline transmission systems such as G.fast use bands up to around 200 MHz on short cables. A key enabler for achieving the aspired throughput of several hundred Mbit/s is joint processing of transmit signals in downstream direction as well as joint processing of receive signals in upstream direction through techniques referred to as vectoring. A new challenge in such systems are sudden and severe changes in the channel matrix caused by changing terminations on lines outside the vectoring group. Such events can be caused by users disconnecting their modems, turning them on or off, or on-/off- hook events on lines that still support the plain old telephony service. This work presents channel measurements capturing the impact of termination changes caused by modems or handsets. An analysis of the impact of these sudden changes on the signal- to-noise-power-ratio in vectoring systems reveals that throughput and stability can be seriously degraded. The potential of decision- directed channel tracking based on least squares estimation is investigated.
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| 49. |
- Medeiros, Eduardo, et al.
(författare)
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Modeling Alien-Line Impedance Mismatch in Wideband Vectored Wireline Systems
- 2014
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Ingår i: IEEE Communications Letters. - 1089-7798. ; 18:9, s. 1527-1530
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Tidskriftsartikel (refereegranskat)abstract
- Sudden changes of channel coefficients in a wideband vectored wireline system (such as G.fast) due to changes in the terminating impedance of lines outside the vectored group can seriously degrade stability and throughput. This letter presents a model that predicts the impact of termination mismatch based exclusively on crosstalk data for the properly-terminated state. Experimental results confirm a tight fit between model and mea- surements. The model allows analysis of system performance and stability without dedicated crosstalk measurements for mismatch cases.
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| 50. |
- Nilsson, Rickard, et al.
(författare)
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A low complexity threshold detector making MLSD decisions in a multiuser environment
- 1998
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Ingår i: Pathway to a global wireless revolution. - Piscataway, NJ : IEEE Communications Society. - 0780343204 ; , s. 333-337
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a pipelined implementation of an iterative threshold detector, which makes the same decisions as a maximum likelihood sequence detector (MLSD) on some, but not necessarily all, bits. We apply this as a first stage detector in a direct sequence code division multiple access (DS-CDMA) interference-limited multiuser system. In combination with the single-user matched filter (MF) detector we obtain improved performance and lower complexity than with the decorrelating receiver for a limited number of simultaneous users, e.g. up to 25 users with a spreading factor of 127.
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