| 1. |
- Aronsson, Daniel, et al.
(författare)
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Performance Evaluation of Memory-less and Kalman-based Channel Estimation for OFDMA
- 2009
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Ingår i: VTC Spring 2009 - IEEE 69th Vehicular Technology Conference; Barcelona; Spain; 26 April 2009 through 29 April 2009. - 1550-2252. - 9781424425174 ; , s. Art. no. 5073788-
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Konferensbidrag (refereegranskat)abstract
- The next generation wireless systems based onOrthogonal Frequency Division Multiple Access (OFDMA) needto operate in widely different deployment and usage scenarios. Thus, support for flexible resource allocation is important. In this paper we investigate the performance of different memory-less and memory-based channel estimators with different OFDMA subcarrier allocation schemes and different pilot patterns. We evaluate the performance in various fading environments and for different user terminal velocities. The results show that channel estimation can perform well enough for time-frequency localized resources as small as 22 channel symbols with two pilots in many important scenarios. The results provided can be used to identify appropriate subcarrier allocations for the next generation OFDMA based wireless systems.
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| 2. |
- 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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| 3. |
- Plass, Simon, et al.
(författare)
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High Spectral Efficient and Flexible Next Generation Mobile Communications
- 2007
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Ingår i: Proceedings 4th COST289 workshop.
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Konferensbidrag (refereegranskat)abstract
- In this paper we identify and describe the requirementsand challenges of next generation mobile communicationssystems. The so-called fourth generation (4G) aims at throughput rates of more than 100 MBit=s outdoors with high mobility and 1 GBit=s indoors. This requires new advanced techniques in the air interface of such a system. We outline new possible techniques and introduce a future basic physical layer concept. The adaptivity to the channel of all the modules in such a possible concept is highlighted. Since the needed large bandwidth for highdata rates is a very valuable resource, future communications systems need a high spectrum flexibility. Furthermore, 4G systems will face severe inter-cell interference scenarios that have to be tackled. Both challenges, i.e., spectrum flexibility and inter-cellinterference, are discussed in more detail in this paper. At the end, a possible time line for the evolution of a next generation mobile communications system is given.
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| 4. |
- Svensson, Tommy, 1970, et al.
(författare)
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B-IFDMA - A Power Efficient Multiple Access Scheme for Non-frequency-adaptive Transmission
- 2007
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Ingår i: IST Mobile Summit 2007, Budapest, July 2007..
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Konferensbidrag (refereegranskat)abstract
- Within the EU FP6 Integrated Projects WINNERand WINNER II, multiple access schemes for frequency-adaptive and non-frequency-adaptive transmission for a future broadband mobile wireless system are investigated. This paper presents a novel power effcient multiple access scheme for non-frequencyadaptive uplink transmission denoted Block Interleaved Frequency Division Multiple Access (B-IFDMA), which provides large frequency-diversity, potential power savings by user terminal sleep mode, modest high power amplifer backoff and robustness to frequency-offsets, and phase noise.
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| 5. |
- Svensson, Tommy, 1970, et al.
(författare)
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Block Interleaved Frequency Division Multiple Access for Power Efficiency, Robustness, Flexibility and Scalability. Nov 2009.
- 2009
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Ingår i: Eurasip Journal on Wireless Communications and Networking. - 1687-1499 .- 1687-1472.
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Tidskriftsartikel (refereegranskat)abstract
- The multiple access solution in an IMT-Advanced mobile radio system has to meet challenging requirements such ashigh throughput, low delays, high flexibility, good robustness, low computational complexity and a high power efficiency, especially in the uplink. In this paper a novel multiple access scheme for uplinks denoted as B-IFDMA is presented. We show that this scheme is able to provide equal or better error rate performance than the Single-Carrier Frequency Division Multiple Access (SCFDMA)schemes IFDMA and LFDMA, when considering realistic channel estimation performance at the receiver and no reliable channel state information at the transmitter. We also show that B-IFDMA provides better amplifier efficiency than OFDMA and can provide better end-to-end energy efficiency than IFDMA and LFDMA. Moreover, the scheme shows a promisingly high robustness to frequency-offsets and Doppler spread. Thus, this scheme can be regarded as a promising solution for the uplink of future mobile radio systems.
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| 6. |
- Svensson, Tommy, 1970, et al.
(författare)
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Coding and Resource Scheduling in Packet Oriented Adaptive TDMA/OFDMA Systems
- 2006
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Ingår i: Proceedings IEEE Vehicular Technology Conference Spring, Melbourne, Australia.
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Konferensbidrag (refereegranskat)abstract
- Within the EU FP6 Integrated Project WINNER, adaptive transmission is investigated as a key technology for boosting the spectral efficiency of a new radio interface for 4G systems. Adaptive allocation and link adaptation of time-frequency chunks based on channel prediction in an OFDM-based system offers a significant potential to design a spectrally efficient system. The chunk size is typically defined based on the minimum coherence time and coherence bandwidth of the targeted channels. it is important to allow efficient channel coding and link retransmission schemes without restricting the resource scheduler, even for systems using small chunk sizes, to achieve multi-user diversity gains. In this paper we introduce some possible approaches to implement FEC coding and Hybrid ARQ and analyze their interplay with resource scheduling in packet oriented adaptive TDMA/OFDMA.
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| 7. |
- 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 ; , 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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| 8. |
- Wijting, Carl, et al.
(författare)
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WINNER II System Concept: Advanced Radio Technologies for Future Wireless Systems
- 2008
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Ingår i: ICT Mobile Summit 2008, Stockholm, Sweden, June 2008.
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Konferensbidrag (refereegranskat)abstract
- WINNER has been an ambitious research project aiming at identification and assessment of key technologies for Beyond 3G mobile systems. The goal of the WINNER mobile access network is a system that is highly flexible and efficient and can provide a wide range of services to a multitude of users in many different environments. This paper provides a concise overview of the WINNER system concept and presents the main technical innovation areas addressed by the project.
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