| 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. ; 25:5, s. 705-713
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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)
-
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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| 11. |
- Huang, Yezi, et al.
(författare)
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Rate-Boosting Using Strong Crosstalk in Next Generation Wireline Systems
- 2016
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Ingår i: 2015 IEEE Global Communications Conference (GLOBECOM). - 9781467395267 ; , s. 1-6
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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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| 12. |
- Huang, Yezi, et al.
(författare)
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Time-Domain Precoding for LTE-over-Copper Systems
- 2016
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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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| 13. |
- Huang, Yezi
(författare)
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Wireline Communications in a Wireless World
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The whole society is digitalizing, filled with streaming services, cloud computing and an ambition of ubiquitous connectivity. To address the data demand, ultra-fast broadband, at the speeds of 1Gbps and more, is developed and deployed. Optical fibers have been long viewed as a future-proof carrier for the ultra-fast broadband. However, the physical deployment of fiber networks, including digging, burying, rewiring, drilling, etc., is still an expensive and disruptive process. The economic concern repeatedly defers the delivery of end-to-end fiber connections to every premise while the 5G development cannot wait any longer. This dilemma motivates the industry to use the readily in-place copper-based network to deliver the last-mile communication which is the most expensive segment for fiber roll-outs. The challenge is: are the copper cables capable of offering a fiber-like experience?This thesis supports the answer: Yes. Focusing on the network side, where centralized cooperative processing is available, the potential of copper networks is explored in three subparts: evolution, maintenance and extension. The first subpart, devoted to DSL evolution, continues extracting available resources to increase network capacity. The main concept of the 4GBB is to further broaden bandwidth over shorter cables for loading more data. However, its effectiveness gets saturated after around 200MHz due to severe data channel attenuation and strong interference level. To cut this Gordian knot, a new precoding scheme combining beamforming and crosstalk mitigation is presented, improving the bit-loading capability at high frequencies via constructive crosstalk from adjacent twisted pairs.The second subpart addresses a newly observed disruption of the evolved broadband network to maintain the stability of services. The disruption, caused by sudden termination changes at user premises, significantly degrades performances at high frequencies, which are the key for the DSL evolution. A low-cost precoder updating procedure is proposed and applied to two types of common-used precoders. It enables quick retrieving of the normal operation state without the end-users experiencing any impairment on the quality of service.The third subpart extends the application from providing fixed access to fronthauling 4G and 5G mobile networks. In order to coordinate power and spectrum usage, the mobile network has its baseband unit (BBU) centralized, while pushing the radio unit (RU) closer to end-users with fronthaul links connected in between. Those links are then normally served by the fixed access network. In this regard, this thesis firstly sketches and analyzes the feasibility of an LTE-over-copper system considering the crosstalk issue. When it comes to 5G where the number of antennas scales up to be "massive", strategies of beneficial functional split are discussed to lessen the dramatically growing traffic on the fronthaul links.
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| 14. |
- Lei, Wanlu, et al.
(författare)
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Adaptive Beam Sweeping With Supervised Learning
- 2022
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Ingår i: IEEE Wireless Communications Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 2162-2337 .- 2162-2345. ; 11:12, s. 2650-2654
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Tidskriftsartikel (refereegranskat)abstract
- Utilizing millimeter-wave (mmWave) frequencies for wireless communication in mobile systems is challenging since continuous tracking of the beam direction is needed. For the purpose, beam sweeping is performed periodically. Such approach can be sufficient in the initial deployment of the network when the number of users is small. However, a more efficient solution is needed when lots of users are connected to the network due to higher overhead consumption. We explore a supervised learning approach to adaptively perform beam sweeping, which has low implementation complexity and can improve cell capacity by reducing beam sweeping overhead. By formulating the beam tracking problem as a binary classification problem, we applied supervised learning methods to solve the formulated problem. The methods were tested on two scenarios: ray-tracing outdoor scenario and over-the-air (OTA) testing dataset from Ericsson. Both experimental results show that the proposed methods significantly increase cell throughput comparing with existing exhaustive sweeping and periodical sweeping strategies.
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| 15. |
- Lei, Wanlu, et al.
(författare)
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Adaptive Beam Tracking With Supervised Learning
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Utilizing millimeter-wave (mmWave) frequencies forwireless communication in mobile systems is challenging sincecontinuous tracking of the beam direction is needed. For the purpose, beam sweeping is performed periodically. Such approachcan be sufficient in the initial deployment of the network whenthe number of users is small. However, a more efficient solutionis needed when lots of users are connected to the network due tohigher overhead consumption. We explore a supervised learningapproach to adaptively perform beam sweeping, which has lowimplementation complexity and can improve cell capacity byreducing beam sweeping overhead. By formulating the beamtracking problem as a binary classification problem, we appliedsupervised learning methods to solve the formulated problem.The methods were tested on two scenarios: ray-tracing outdoorscenario and over-the-air (OTA) testing dataset from Ericsson.Both experimental results show that the proposed methodssignificantly increase cell throughput comparing with existingexhaustive sweeping and periodical sweeping strategies.
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| 16. |
- Medeiros, Eduardo, et al.
(författare)
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Crosstalk Mitigation for LTE-over-Copper in Downlink Direction
- 2016
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Ingår i: IEEE Communications Letters. - 1089-7798. ; 20:7, s. 1425-1428
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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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