| 1. |
- Bengtsson, Daniel, et al.
(författare)
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Trellis coding in a discrete multitone modulation system
- 1996
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Ingår i: Proceedings of the 1996 SNRV and NUTEK Conference on Radio Sciences and Telecommunications in Luleå and Kiruna June 3-6, 1996. - Luleå : Luleå tekniska universitet. - 9163044552 ; , s. 668-672
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Konferensbidrag (refereegranskat)abstract
- Discrete Multitone (DMT) modulation is a multicarrier technique which makes efficient use of the channel, maximizing the throughput by sending different numbers of bits on different subchannels. The number of bits on each subchannel depends on the Signal-to-Noise Ratio of the subchannel. The performance of a DMT system can be further increased by using powerful coding techniques. This paper investigates an implementation of trellis coded modulation in a DMT system intended for transmission over short copper cables, less than 1000m. We suggested trellis code is Wei's 4-dimensional 16-state coder combined with trellis shaping. A single encoder is used which codes across the tones of each DMT-symbol. At a bit error probability of 10-7, the suggested code gains 4-5 dB over uncoded transmission.
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| 2. |
- Bengtsson, Daniel, et al.
(författare)
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Zipper performance when mixing ADSL and VDSL in terms of reach and capacity
- 1997
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this contribution we have examined how the maximum reach vary at different bit rates on a VDSL system, when different numbers of ADSL and VDSL systems share the same binder. In this context it is concluded that when using the Zipper duplex scheme, VDSL can coexist with ADSL in the same binder without a significant degradation in reach. Further, it is shown that the Zipper duplex scheme secure that ADSL is not disturbed by NEXT from VDSL The Zipper performance has also been compared with both a TDD proposal and a FDD proposal. The results from this comparison shows that Zipper outperforms FDD and TDD in terms of extended reach at all studied mixes of ADSL and VDSL sharing the same binder. For example with a moderate number (5) of ADSL disturbers, the Zipper reach is 150 meters longer than for TDD, and is 350 meters longer than for FDD when studying the medium range asymmetrical bit rate (26:3.2 Mbps).
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| 3. |
- Eskilson, Olof, 1992-, et al.
(författare)
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Nanocellulose composite wound dressings for real-time pH wound monitoring
- 2023
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Ingår i: Materials Today Bio. - : Elsevier. - 2590-0064. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- The skin is the largest organ of the human body. Wounds disrupt the functions of the skin and can have catastrophic consequences for an individual resulting in significant morbidity and mortality. Wound infections are common and can substantially delay healing and can result in non-healing wounds and sepsis. Early diagnosis and treatment of infection reduce risk of complications and support wound healing. Methods for monitoring of wound pH can facilitate early detection of infection. Here we show a novel strategy for integrating pH sensing capabilities in state-of-the-art hydrogel-based wound dressings fabricated from bacterial nanocellulose (BC). A high surface area material was developed by self-assembly of mesoporous silica nanoparticles (MSNs) in BC. By encapsulating a pH-responsive dye in the MSNs, wound dressings for continuous pH sensing with spatiotemporal resolution were developed. The pH responsive BC-based nanocomposites demonstrated excellent wound dressing properties, with respect to conformability, mechanical properties, and water vapor transmission rate. In addition to facilitating rapid colorimetric assessment of wound pH, this strategy for generating functional BC-MSN nanocomposites can be further be adapted for encapsulation and release of bioactive compounds for treatment of hard-to-heal wounds, enabling development of novel wound care materials.
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| 4. |
- Isaksson, Mikael, et al.
(författare)
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Pulse shaping with zipper : spectral compatibility and asynchrony
- 1998
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We have investigated what the effects of adding pulse shaping and windowing to a Zipper-VDSL system would be. By adding short, pulse-shaped wings to the DMT symbol and accepting the, say, 3 % efficiency loss, the spectral sidelobes of the DMT-symbol are reduced. This provides several attractive features including the following: · The pulse shaping in the transmitter reduces the out of band power of the DMT-signal. · The spectral compatibility with other systems such as ADSL and CAP-VDSL is enhanced. · It becomes feasible to use Zipper-VDSL in a time-asynchronous mode, where a VTU-R only synchronizes itself to its VTU-O, while the VTU-R / VTU-O pair may be asynchronous to all other transceiver pairs. · The pulse shaping gives some increase in the depth of spectral notches, for HAM-bands etc. The windowing is a part of a powerful RFI-ingress suppressing method as proposed by John Bingham, Amati.
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| 5. |
- Isaksson, Mikael, et al.
(författare)
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Zipper : a duplex scheme for VDSL based on DMT
- 1997
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A duplex scheme for DMT-based VDSL systems is presented here. It offers a solution to the problem with NEXT and near-echoes in broadband communications. The scheme has high duplex efficiency, low latency, and attractive transmit power features. However, hardware verification remains.
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| 6. |
- Sjöberg, Frank, et al.
(författare)
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Power back-off for multiple target bit rates
- 1998
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This contribution describes a new efficient method to perform power back-off in the upstream of a VDSL-system. The method gives higher data rates than the earlier proposals, i.e., the constant back-off method and the reference length method. One conceptual difference with this new method is that we are not using just one design parameter as with the reference frequency and reference length methods. With this new method all users are assigned a certain service class, a target bit rate. The method then performs the power back-off such that it tries to maximize the bit rate (the system margin) for all the other users. The method tries to create FEXT, at each NT, that has the same spectral shape as the background noise. Between 5% and 20% improvement in bit rates is achieved with this new method when using the FSAN models for cable, crosstalk and background noise. The larger improvements over the other methods appear when non-flat background is present. This is because the PSD of the background noise is included in the model used by method. For thinner wires, like the TP1 wire, the method can give more than 20% higher data rate for almost all users.
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