| 1. |
- Fertner, Antoni, et al.
(författare)
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Applications of Backscattering for the Study of Twisted Pair Transmission Lines
- 2018
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480. ; 66:12, s. 5230-5237
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Tidskriftsartikel (refereegranskat)abstract
- The phenomenon of backscattering in copper cables has been recently observed and initially explicated. It can provide promising techniques to address the problem of loop diagnostic and maintenance. The backscattering is analyzed both in frequency and time domains. To demonstrate the practical use of the phenomenon, we estimate certain properties of the loop using wideband, high-frequency $\selevenf(f)$ measurements performed in the laboratory on real cables. The results corroborate the usefulness and accuracy of the investigated method.
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| 2. |
- Fertner, Antoni, et al.
(författare)
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Backscattering in Twisted-Pair Nonhomogeneous Transmission Lines
- 2018
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480. ; 66:6, s. 2674-2682
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Tidskriftsartikel (refereegranskat)abstract
- The development of the communication networks tends gradually toward exploiting higher frequencies, sometimes even reaching the lowest microwave band (P-band). As the signal bandwidth used for transmission over twisted-pairs increases, as recommended by G.fast and other broadband systems, new phenomenon was observed, namely, backscattering. Motivated by the measurements of copper cables in frequency band up to 400 MHz, we propose a novel backscattering model. It may be productively applied to the problem of loop diagnostics. The methods to accurately and reliable determine the relevant transmission-line parameters are sine qua non condition to appropriately exploit the potential of short-to-medium range access lines. In this paper, a recursive formulation of the frequency-domain response of the backscattering is used for a space-time characterization. To confirm the practical use of the finding, we evaluate the properties of a loop using wideband, high-frequency S₁₁ measurements of the real cables. These laboratory results confirm the effectiveness and accuracy of the proposed method.
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| 3. |
- Huang, Jing, et al.
(författare)
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The correlation between drivers’ road familiarity and glance behavior using real vehicle experimental data and mathematical models
- 2024
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Ingår i: Traffic Injury Prevention. - 1538-957X .- 1538-9588. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Road familiarity is an important factor affecting drivers’ visual features. Analyzing the quantitative correlation between drivers’ road familiarity and visual features in complex environment is of great help to improve driving safety. However, there are few relevant studies. This paper takes urban plane intersection as the environmental object to explore the correlation between drivers’ glance behavior and road familiarity, and conducts research on the quantitative evaluation model of road familiarity based on this correlation. Method: First, a real vehicle experiment was carried out to record the eye movement data of 24 drivers with different road familiarity. The driver’s visual field plane was divided into 10 areas of interest (AOIs) based on the driver’s perspective. Three measures, including average glance duration, number of glances, and fixation transition probabilities between AOIs at urban plane intersections, were extracted. Finally, based on the experimental results, the driver road familiarity evaluation model was constructed using the factor analysis method. Results: There are significant differences between unfamiliar and familiar drivers regarding the average glance duration toward the forward (FW) area, the left window (LW) area, the left rearview mirror (LVM) area and the left forward (LF) area, the number of glances toward the other (OT) area, and the fixation transition probabilities of LW→RF (right forward), LF→LF, LF→FW, FW→LW, FW→FW, FW→RVM (right rearview mirror). The comprehensive evaluation results show that the accuracy rate of the driver road familiarity evaluation model reached 83%. Conclusions: This paper revealed that there is a strong correlation between drivers’ road familiarity and drivers’ glance behavior. Based on this correlation, we can include road familiarity as a part of drivers’ working status and establish a high accuracy evaluation model of driver road familiarity. The conclusion of this paper can provide some reference for the humanized design and improvement of advanced driving assistance system, which is of great significance for reducing the driving workload of drivers and improving the driving safety.
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| 4. |
- Huang, Yezi
(författare)
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Crosstalk in Wideband Wireline Systems -- Curse and Blessing
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The fourth generation broadband (4GBB) concept aims for ubiquitous and high-speed data communication over the existing twisted copper pairs between the last distribution point and the customer premise equipment. Although it saves deployment cost for the last-mile communication, using the existing copper infrastructure makes the system vulnerable to crosstalk due to electro-magnetic coupling from the neighboring pairs. Crosstalk is frequency-dependent and its interfering effects vary with implementation scenarios. When exploring higher frequencies and more functionality for the copper-based infrastructure, new practical problems emerge which opens up a space of unknowns to be investigated. This thesis deals with crosstalk, its effects, its mitigation, and approaches to exploit it in emerging systems and applications. Dividing the frequency range into three bands and taking into account the respective architecture’s characteristics, precoding schemes are proposed that properly process the crosstalk to improve end-users’ quality of experience. Chapters I–III of this thesis cope with sudden termination changes that significantly degrade the delivered throughput to active users when using a frequency range from 30 MHz to 180 MHz. A general model that interprets the changed coupling environment is presented and analyzed. Efficient precoder updating procedures are proposed for both linear and non-linear precoding systems which minimize the disturbed period to active end-users. Chapter IV designs modified linear precoders for rate-boosting by utilizing strong crosstalk between 150 MHz and 300 MHz. Taking advantage of a common network topology in a novel way, the proposed precoding schemes can add a decent amount of extra data-rate to target end-user(s) on top of the normal precoding schemes. Finally, Chapters V–VII revisit the frequencies below 30MHz and investigate the potential of using the existing copper-based infrastructure as the analog fronthaul for small-cell densification of the mobile networks. An LTE-over-copper system is sketched and analyzed invoking 3GPP requirements. A time-domain precoding scheme is proposed that performs channel estimation using carried LTE signals and yields an effective channel that is crosstalk-free and has identical direct paths.
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| 5. |
- Huang, Yezi, et al.
(författare)
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Enabling DSL and Radio on the Same Copper Pair
- 2015
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Ingår i: 2015 IEEE International Conference on Communications (ICC). - 9781467364324 ; , s. 1031-1035
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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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| 6. |
- Huang, Yezi, et al.
(författare)
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Fast Mitigation of Sudden Termination Changes in Wideband Wireline Systems
- 2016
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Ingår i: IEEE Transactions on Communications. - 0090-6778. ; 64:6, s. 2610-2621
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Tidskriftsartikel (refereegranskat)abstract
- Vectoring enables cooperative crosstalk mitigation in wideband wireline systems. A sudden termination change within a vectored group alters the entire perceived channel matrix and thus disturbs the vectoring operation since the precoder, which is tuned to the channel before the change, is no longer up to date. We analyze the resulting residual crosstalk and its impact on performance degradation during showtime for both linear and non-linear precoding systems. To cover, a new channel matrix must be estimated to update the precoder accordingly. We use a model-based approach to track a vector instead of estimating the full matrix. Based on this vector, simplified precoder updating methods for both precoding systems are presented accounting for a sudden line deactivation or (re)activation in a vectored group. As an alternative to the state-of-the-art methods, the proposed procedures significantly reduce the complexity of both channel estimation and precoder updating and minimize the disturbed period for active users.
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| 7. |
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| 8. |
- Huang, Yezi, et al.
(författare)
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Functional Split of Zero-Forcing Based Massive MIMO for Fronthaul Load Reduction
- 2018
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Ingår i: IEEE Access. - 2169-3536. ; 6, s. 6350-6359
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Tidskriftsartikel (refereegranskat)abstract
- The evolution towards centralized radio access network (C-RAN) for 5G is driven by the need for improved network performance and reduced total-cost-of-ownership (TCO). In CRAN, physically separated remote radio units (RRUs) and baseband units (BBUs) are connected via fronthaul (FH) links, which are capacity constrained. When base-station antennas are upgraded to support massive MIMO techniques, an intra PHY split between RRU and BBU becomes favorable to avoid the dramatic rate growth on the FH links. In this paper, we present a new uplink functional split alternative that decomposes the massive MIMO processing, on the basis of zero-forcing (ZF) equalization, into two phases: dimension-reduction phase and interference cancellation phase, which are implemented in RRU and BBU respectively. Compared with the traditional C-RAN architecture having all baseband processing in the BBU, the new scheme largely alleviates the FH load by reducing the number of FH streams to be equal to the number of MIMO user layers. Compared with an existing split that places all MIMO processing in RRU, the new scheme reduces the RRU complexity without compromising the post-processing performances.
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| 9. |
- Huang, Yezi, et al.
(författare)
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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
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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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| 10. |
- Huang, Yezi, et al.
(författare)
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Mitigating Disorderly Leaving Events in G.fast
- 2015
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Ingår i: 2015 IEEE International Conference on Communications (ICC). ; , s. 939-944
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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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