| 1. |
- Huang, Yezi
(författare)
-
Crosstalk in Wideband Wireline Systems -- Curse and Blessing
- 2015
-
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.
|
|
| 2. |
- 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.
|
|
| 3. |
- Huang, Yezi, et al.
(författare)
-
LTE Over Copper - Potential and Limitations
- 2015
-
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.
|
|
| 4. |
- 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).
|
|
