| 1. |
- Anderson, John B., et al.
(författare)
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Ross Sea paleo-ice sheet drainage and deglacial history during and since the LGM
- 2014
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 100, s. 31-54
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Tidskriftsartikel (refereegranskat)abstract
- Onshore and offshore studies show that an expanded, grounded ice sheet occupied the Ross Sea Embayment during the Last Glacial Maximum (LGM). Results from studies of till provenance and the orientation of geomorphic features on the continental shelf show that more than half of the grounded ice sheet consisted of East Antarctic ice flowing through Transantarctic Mountain (TAM) outlet glaciers; the remainder came from West Antarctica. Terrestrial data indicate little or no thickening in the upper catchment regions in both West and East Antarctica during the LGM. In contrast, evidence from the mouths of the southern and central TAM outlet glaciers indicate surface elevations between 1000 m and 1100 m (above present-day sea level). Farther north along the western margin of the Ross Ice Sheet, surface elevations reached 720 m on Ross Island, and 400 m at Terra Nova Bay. Evidence from Marie Byrd Land at the eastern margin of the ice sheet indicates that the elevation near the present-day grounding line was more than 800 m asl, while at Siple Dome in the central Ross Embayment, the surface elevation was about 950 m asl. Farther north, evidence that the ice sheet was grounded on the middle and the outer continental shelf during the LGM implies that surface elevations had to be at least 100 m above the LGM sea level. The apparent low surface profile and implied low basal shear stress in the central and eastern embayment suggests that although the ice streams may have slowed during the LGM, they remained active. Ice-sheet retreat from the western Ross Embayment during the Holocene is constrained by marine and terrestrial data. Ages from marine sediments suggest that the grounding line had retreated from its LGM outer shelf location only a few tens of kilometer to a location south of Coulman Island by similar to 13 ka BP. The ice sheet margin was located in the vicinity of the Drygalski Ice Tongue by similar to 11 ka BP, just north of Ross Island by similar to 7.8 ka BP, and near Hatherton Glacier by similar to 6.8 ka BP. Farther south, Be-10 exposure ages from glacial erratics on nunataks near the mouths of Reedy, Scott and Beardmore Glaciers indicate thinning during the mid to late Holocene, but the grounding line did not reach its present position until 2 to 3 ka BP. Marine dates, which are almost exclusively Acid Insoluble Organic (AIO) dates, are consistently older than those derived from terrestrial data. However, even these ages indicate that the ice sheet experienced significant retreat after similar to 13 ka BP. Geomorphic features indicate that during the final stages of ice sheet retreat ice flowing through the TAM remained grounded on the shallow western margin of Ross Sea. The timing of retreat from the central Ross Sea remains unresolved; the simplest reconstruction is to assume that the grounding line here started to retreat from the continental shelf more or less in step with the retreat from the western and eastern sectors. An alternative hypothesis, which relies on the validity of radiocarbon ages from marine sediments, is that grounded ice had retreated from the outer continental shelf prior to the LGM. More reliable ages from marine sediments in the central Ross Embayment are needed to test and validate this hypothesis.
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| 2. |
- Anderson, John B
(författare)
-
A review of faster than Nyquist signaling with an extension to four-level modulation
- 2016
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Ingår i: 9th International Symposium on Turbo Codes and Iterative Information Processing (ISTC), 2016. - 9781509034024 - 9781509034017 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- A survey of faster than Nyquist results over the last 15 years, with and extension of earlier binary modulation/convolutional coding results to four-level modulation.
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| 3. |
- Anderson, John B, et al.
(författare)
-
An optimal circular Viterbi decoder for the bounded distance criterion
- 2002
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Ingår i: IEEE Transactions on Communications. - 0090-6778. ; 50:11, s. 1736-1742
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Tidskriftsartikel (refereegranskat)abstract
- We propose a Viterbi-type decoder for tailbiting trellis codes that works by traversing the tailbiting circle somewhat more than once. The traversal is the least possible for any bounded distance Viterbi decoder. Procedures are given that compute this minimum. Unlike previous decoders of the type, the new scheme does not suffer limit cycles or from pseudocodewords. The bit-error rate is compared to that of Bahl-Cocke-Jelinek-Raviv and maximum-likelihood decoding.
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| 4. |
- Anderson, John B, et al.
(författare)
-
Analysis of Best High Rate Convolutional Codes for Faster than Nyquist Turbo Equalization
- 2014
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Ingår i: 2014 IEEE International Symposium on Information Theory (ISIT). ; , s. 1987-1991
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Konferensbidrag (refereegranskat)abstract
- We find good rate 2/3 and 3/4 convolutional codes for use with iterative decoding (turbo equalization) of coded intersymbol interference with AWGN. The method is based on the input-output bit error rate characteristic of the convolutional BCJR decoder module. An analysis leads to an equivalent minimum distance under the required intrinsic subtraction, which depends on free distance and an input-output LLR correlation parameter.
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| 5. |
- Anderson, John B
(författare)
-
Bandwidth Efficient Coding
- 2017
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Bok (refereegranskat)abstract
- Methods for energy and bandwidth efficient coded digital communication, including pulse design, non-orthogonal signaling methods, and the faster than Nyquist signaling method.
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| 6. |
- Anderson, John B, et al.
(författare)
-
Best Rate 1/2 Convolutional Codes for Turbo Equalization with Severe ISI
- 2012
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Ingår i: 2012 IEEE International Symposium on Information Theory Proceedings (ISIT). - 9781467325806 ; , s. 2366-2370
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Konferensbidrag (refereegranskat)abstract
- We give a procedure to find good convolutional codes for use with iterative decoding (turbo equalization) of the coded AWGN intersymbol interference (ISI) channel. The method is based on the input-output bit error rate characteristic of the convolutional BCJR module in the iterative decoder, in combination with the code minimum distance. Both are essential to find best codes. Best feedforward and recursive systematic codes are listed for memories 2-4, and some individual good codes at memory 5. Codes are tested over a root raised-cosine faster than Nyquist channel with severe ISI. Turbo BER performance reaches 0.8-1.6 dB from capacity with a 4-16 state codes. Feedforward codes perform better than recursive systematic.
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| 7. |
- Anderson, John B
(författare)
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Coded modulation by outright filtering
- 2002
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Ingår i: Proceedings 2002 IEEE International Symposium on Information Theory (Cat. No.02CH37371). - 0780375017 ; , s. 471-471
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Konferensbidrag (refereegranskat)abstract
- We investigate the bandwidth and distance of codes created by ordinary lowpass filtering of a pulse stream. The encoder is thus a convolution, but over the reals. Performance of these codes is compared to the TCM and PRS code families; despite their simplicity, the new codes perform equally well. Since a simple decoder exists, these are attractive codes.
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| 8. |
- Anderson, John B, et al.
(författare)
-
Coded Modulation Systems
- 2003
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Ingår i: Kluwer Academic / Plenum Publishers. - 0306472791
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- This textbook studies the 3 main types of coded modulation: trellis-coded modulation (TCM), continuous-phase modulation (CPM) codes, and linear modulation codes like those that arise from filtering and intersymbol interference. In 2 final chapters, code-division multiple-access receivers are discussed. The book begins with a review of coding, modulation and information theory.
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| 9. |
- Anderson, John B
(författare)
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Digital Transmission Engineering
- 2005
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- This textbook is a 4th year(Sweden)/5th year (USA) text in digital communication theory and practice. Chapters include baseband pulse transmission, carrier transmission, synchronization, channels, coding and information theory, and advanced topics. Each chapter ends with 25 home exercises. Worked examples and Matlab tools are integrated with the text.
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| 10. |
- Anderson, John B, et al.
(författare)
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Faster-Than-Nyquist Signaling
- 2013
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Ingår i: Proceedings of the IEEE. - 0018-9219. ; 101:8, s. 1817-1830
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we survey Faster-than-Nyquist (FTN) signaling, an extension of ordinary linear modulation in which the usual data bearing pulses are simply sent faster, and consequently are no longer orthogonal. Far from a disadvantage, this innovation can transmit up to twice the bits as ordinary modulation at the same bit energy, spectrum, and error rate. The method is directly applicable to orthogonal frequency division multiplex (OFDM) and quadrature amplitude modulation (QAM) signaling. Performance results for a number of practical systems are presented. FTN signaling raises a number of basic issues in communication theory and practice. The Shannon capacity of the signals is considerably higher.
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