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| 4. |
- Sternad, Mikael, et al.
(författare)
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Towards systems beyond 3G based on adaptive OFDMA transmission
- 2007
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Ingår i: Proceedings of the IEEE. - 0018-9219 .- 1558-2256. ; 95:12, s. 2432-2455
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Forskningsöversikt (refereegranskat)abstract
- High data rates, high spectral efficiency, flexibility, and low delays over the air interface will be important features in next-generation wireless systems. The overall challenge will be packet scheduling and adaptive radio transmission for multiple users, via multiple antennas and over frequency-selective wideband channels. This problem needs to be structured to obtain feasible solutions. The basic simplifying assumptions used here are clustering of antennas into cells, orthogonal transmission by use of cyclic-prefix orthogonal frequency-division multiplexing (OFDM) and a time-scale separation view of the total link adaptation, scheduling and intercell coordination problem. Based on these assumptions, we survey techniques that adapt the transmission to the temporal, frequency, and spatial channel properties. We provide a systematic overview of the design problems, such as the dimensioning of the allocated time-frequency resources, the influence of duplexing schemes, adaptation control issues for downlinks and uplinks, timing issues, and their relation to the required performance of channel predictors. Specific design choices are illustrated by recent research within the Swedish Wireless IP program and the EU IST-WINNER project. The presented results indicate that high-performance adaptive OFDM transmission systems are indeed feasible, also for challenging scenarios that involve vehicular velocities, high carrier frequencies, and high bandwidths
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- Svensson, Tommy, 1970, et al.
(författare)
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Design and Performance of Constrained Envelope Continuous Phase Modulation
- 2009
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Ingår i: Proceedings IEEE 4th International Waveform Diversity and Design Conference, Orlando, Florida, USA. - 9781424429714 ; , s. 312-316
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Konferensbidrag (refereegranskat)abstract
- We have developed a coded modulation system withcontinuous phase and a small controlled envelope variation called Constrained Envelope Continuous Phase Modulation (ceCPM). For the spectrally efficient scenarios, within the ceCPM framework it is possible to find schemes with an SNR gain up to 2.5 dB over Continuous Phase Modulation (CPM) at symbol error probability 10−3, under the same requirement on spectral confinement and spectral efficiency as for the best CPM scheme. In this paper we discuss the design process for how to obtain such ceCPM schemes, and we elaborate on the properties of these ceCPM schemes.
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- Svensson, Tommy, 1970, et al.
(författare)
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Multi-pulse Continuous Phase Modulation
- 2002
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Ingår i: Proceedings 5th International Symposium on Wireless Personal Multimedia Communications, Honolulu, Hawaii, USA.
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Konferensbidrag (refereegranskat)
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| 11. |
- Svensson, Tommy, 1970, et al.
(författare)
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On Convolutionally Encoded Partial Response CPM
- 1999
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Ingår i: Proceedings IEEE Vehicular Technology Conference Fall, Amsterdam, the Netherlands. ; , s. 663-667
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Konferensbidrag (refereegranskat)
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- Wang, Wei, 1965, et al.
(författare)
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Evaluations of a 4G Uplink System Based on Adaptive Single-Carrier TDMA
- 2005
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Ingår i: Proceedings IEEE Vehicular Technology Conference Fall, Dallas, Texas, USA. - 1550-2252. - 0780391527 ; 3, s. 1667-1671
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Konferensbidrag (refereegranskat)abstract
- © 2005 IEEE. Recent research has shown that a single-carrier system with frequency domain equalization can be a potential alternative to an OFDM-based system in a single user case. In this paper we propose and evaluate an adaptive single-carrier TDMA uplink with scheduling for broadband cellular packet data systems. Frequency division duplex (FDD) is assumed. Multiuser channel estimation and channel prediction are considered. The adaptive modulation scheme is optimized to maximize the throughput including also the ARQ part of the transmission. Frequency domain equalization is employed to combat the inter-symbol-interference (ISI). With the proposed design, the simulation results show that the multiuser diversity gain in spectral efficiency is limited in a wideband system, which indicates that an OFDM based system might be a more favorable candidate.
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| 17. |
- Ahlén, Anders, et al.
(författare)
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Wireless IP - a new PCC project
- 1999
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Ingår i: Proc. PCC Workshop, Lund, Sweden. ; , s. 100-101
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Konferensbidrag (refereegranskat)
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| 18. |
- Alvarado, Alex, 1982, et al.
(författare)
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Exploiting UEP in QAM-based BICM: Interleaver and Code Design
- 2010
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Ingår i: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 58:2, s. 500-510
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we formally analyze the interleaver and code design for QAM-based BICM transmissions using the binary reflected Gray code. We develop analytical bounds on the bit error rate and we use them to predict the performance of BICM when unequal error protection (UEP) is introduced by the constellation labeling. Based on these bounds the optimum design of interleaver and code is found, and numerical results for representative configurations are presented. When the new design is used, the improvements may reach 2 dB, and they are obtained without any increase on the transceiver's complexity. We also introduce the concept of generalized optimum distance spectrum convolutional codes, which are the optimum codes for QAM-based BICM transmissions.
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| 19. |
- Alvarado, Alex, 1982, et al.
(författare)
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On BICM-ID with Multiple Interleavers
- 2010
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Ingår i: IEEE Communications Letters. - 1558-2558 .- 1089-7798. ; 14:9, s. 785-787
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, we study the performance of BICM-ID with multiple interleavers (BICM-ID-M) in terms of bit-error rate (BER), and show that BICM-ID-M is well-suited to exploit the unequal error protection (UEP) caused by the binary labeling. We show that BICM-ID-M should always be the preferred alternative for BICM-ID and that the gains obtained appear even for the simplest configuration (0.5-0.75 dB for a BER of 10-7). It is found that conventional design paradigms such as maximizing the free distance of the code should be modified.
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| 20. |
- Alvarado, Alex, 1982, et al.
(författare)
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On the Capacity of BICM with QAM Constellations
- 2009
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Ingår i: Proceedings International Wireless Communications and Mobile Computing Conference, IWCMC'09, Leipzig, Germany [Invited]. - New York, NY, USA : ACM. - 9781605585697 ; , s. 573-579
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Konferensbidrag (refereegranskat)abstract
- In this tutorial paper we analyze the capacity of bit-interleaved coded modulation (BICM) with quadrature amplitude modulation (QAM) constellations, and we pay special attention to different bit-to-symbol labeling strategies. The relation between the BICM capacity and the capacity of other CM schemes such as trellis coded modulation (TCM) and multilevel codes (MLC) is analyzed. Motivated by the fact that for BICM with some particular labelings, the same Eb/No maps to more than one BICM capacity value, we study the relation between the capacity and Eb/No. In particular, we present some analytical results on this relation, and we also give an intuitive explanation for the somehow contradictory behavior of these curves.
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| 21. |
- Alvarado, Alex, 1982, et al.
(författare)
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On the Design of Interleavers for BICM Transmission
- 2008
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Ingår i: Proceedings European Wireless Conference 2008, EW2008, Prague, Czech Republic. - 9783800731022
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Konferensbidrag (refereegranskat)abstract
- In this paper we design interleavers for bit-interleaved coded modulation (BICM) based on popular convolutional codes and quadrature amplitude modulation with Gray mapping. We analyze the so-called modular interleavers where the outputs of the convolutional encoder are appropriately matched with the input bits of the modulator. To quantify the achievable improvements we develop bounds on the coded BER using themultidimensional weight distribution spectrum of a code together with an equivalent QAM channel model. Based on these bounds, we show that the assignment of the encoder's output to the bit positions in the symbol significantly affects the system performance. The analytical developments are contrasted with numerical simulations. The improvements obtained through the proposed approach do not change the receiver's complexity and, depending on the system's parameters (rate, modulation, code's memory), they may be up to 1.7 dB!
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| 22. |
- Alvarado, Alex, 1982, et al.
(författare)
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Unequal Error Protection in BICM with QAM Constellations: Interleaver and Code Design
- 2009
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Ingår i: IEEE International Conference on Communications. - 1550-3607. - 9781424434350
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a general methodology for the interleaver and code design for QAM-based BICM transmissions. We develop analytical bounds on the bit error rate and we use them to predict the performance of BICM when unequal error protection (UEP) is introduced by the constellation labeling. Based on these bounds, the optimum design of interleaver and code is presented. The improvements obtained reached 2~dB for the analyzed cases, and are obtained without complexity increase. Although previous works noted the influence of the interleaver design and the UEP, to the best of our knowledge, this paper is the first to analyze formally this problem for BICM transmissions.
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| 23. |
- Anderson, John B, et al.
(författare)
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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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