| 1. |
- Agrell, Erik, 1965, et al.
(författare)
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Gray coding for multilevel constellations in Gaussian noise
- 2007
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 53:1, s. 224-235
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Tidskriftsartikel (refereegranskat)abstract
- The problem of finding the optimal labeling (bit-to-symbol mapping) of multilevel coherent phase shift keying (PSK), pulse amplitude modulation (PAM), and quadrature amplitude modulation (QAM) constellations with respect to minimizing the bit-error probability (BEP) over a Gaussian channel is addressed. We show that using the binary reflected Gray code (BRGC) to label the signal constellation results in the lowest possible BEP for high enough signal energy-to-noise ratios and analyze what is "high enough"in this sense. It turns out that the BRGC is optimal for PSK and PAM systems whenever the target BEP is at most a few percent, which covers most systems of practical interest. New and simple closed-form expressions are presented for the BEP of PSK, PAM, and QAM using the BRGC. © 2007 IEEE.
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| 2. |
- Eriksson, Thomas, 1964, et al.
(författare)
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Compression of feedback for adaptive modulation and scheduling
- 2007
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Ingår i: IEEE Proceedings. ; 95:12, s. 2314-2321
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Tidskriftsartikel (refereegranskat)abstract
- For wireless systems with adaptive modulation and/or scheduling, feedback of channel quality information is often necessary. It has been questioned whether the increased system performance is worth the additional feedback rate and the increased algorithm complexity.
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| 3. |
- Eriksson, Thomas, 1964, et al.
(författare)
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Compression of Feedback in Adaptive OFDM-Based Systems using Scheduling
- 2007
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Ingår i: IEEE Communications Letters. - 1558-2558 .- 1089-7798. ; 11:11, s. 859-861
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Tidskriftsartikel (refereegranskat)abstract
- In wirelesscommunication, adaptive modulation and scheduling are promisingtechniques for a substantially increased spectral efficiency. Toachieve the throughput gain, it is necessary to feedback channelquality information. The required feedback rate may beprohibitively high in many applications, and compression of thefeedback information is normally required.In this paper, we propose a novel channel quality feedback scheme tobe used in a wireless OFDM system, based on a data compressionapproach, and show that the channel information can be compressed by afactor of 5-30 with virtually no loss of system throughput.
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| 4. |
- Falahati, Sorour, 1971, et al.
(författare)
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EU FP6 IST-2003-507581 WINNER, D2.4 Assessment of adaptive transmission technologies, Feb 2005
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This document contains a first assessment of adaptive transmission schemes and how these fitto the different WINNER scenarios. It focuses on an adaptation due to the channel properties that mayvary both in time and frequency or, with respect to the selected antennas, in an OFDM-based air interface.Besides the evaluation by analysis, link simulation and multilink simulation, first detailed designs arepresented of adaptive transmission feedback systems for the WINNER FDD and TDD physical layermodes.
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| 5. |
- Gil Jiménez, Victor P., et al.
(författare)
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Methods for Compression of Feedback in Adaptive Multi-carrier 4G Schemes
- 2008
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Ingår i: Wireless Personal Communications. - : Springer Science and Business Media LLC. - 1572-834X .- 0929-6212. ; 47:1, s. 101-112
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, several algorithms for compressing the feedback of channel quality information are presented and analyzed. These algorithms are developed for a proposed adaptive modulation scheme for future multi-carrier 4G mobile systems. These strategies compress the feedback data and, used together with opportunistic scheduling, drastically reduce the feedback data rate. Thus the adaptive modulation schemes become more suitable and efficient to be implemented in future mobile systems, increasing data throughput and overall system performance.
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| 8. |
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| 9. |
- Persson, Anders, 1975, et al.
(författare)
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A unified analysis for coded DS-CDMA with equal-gain chip combining in the downlink of OFDM systems
- 2005
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Ingår i: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 53:2, s. 289-298
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel unified analysis for the bit-error rate in the downlink of convolutionally coded and single-user detected multicarrier code-division multiple access (CDMA), multicarrier direct-sequence CDMA, time and frequency-domain spreading CDMA, and orthogonal frequency-division multiple access. Performance is analyzed under the assumption of Hadamard spreading codes, equal-gain chip combining, and a highly correlated frequency-selective Rayleigh-fading channel. Closed-form expressions are presented for the cumulative distribution function, probability distribution function, and moment-generating function for the signal-to-noise plus interference ratio after despreading. The presented results assume error-free channel estimates, a perfectly synchronized receiver, and are found to reasonably well agree with simulation results. © 2005 IEEE.
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