| 1. |
- 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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| 2. |
- 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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| 3. |
- 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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