OFDM Multiple Antennas Cognitive Radio Relay CDMA Synchronization Channel Estimation Spectrum Sharing Interference Cancellation Neural Networks Spectrum Sensing Full duplex Resource Allocation Stochastic Geometry Equalizer Feedback Bi-Directional Energy Harvesting Femtocell Heterogeneous Networks Device-to-Device (D2D) Cell Search FBMC HetNet Idle cells Ultra-dense small cell networks Spectral efficiency SINR mismatch problem automatic repeat request (ARQ) in-band full-duplex system Two-way communications transmission capacity (TC) Correlated MIMO sensing duration self-interference cancellation Simultaneous Sensing and Transmission full-duplex cellular multi-spectral beamforming UWB achievable sum rate outage probability Cognitive relay networks selection diversity full-duplex relay Latency Vehicular and wireless technologies Asynchronized system Cross-link interference Cellular networks coexistence Channel estimation error Ultra-dense small cell Shortened TTI UL grant free NOMA mode selection Bi-directional full-duplex OQAM Link adaptation Iterative decoder LTE-TDD Dynamic TDD bursty traffic model CP-OFDM MIMO singular value decomposition Time spreading K-S statistics interference coordination Vehicle-to-vehicle communication eigen decomposition 5G networks GFDM MU-MIMO TS-W-OFDM prototype filter pilot signal Windowing time-frequency efficiency Long Term Evolution-Advanced Aggregate interference LTE-based V2V Vehicle-to-Vehicle Coexistence scenarios resource size control interference to noise ratio interference management mixed numerology Cooperative systems Resource management link reliability Reliability non-orthogonal multiple access full-spreading NOMA massive connectivity Complexity Filtered OFDM C-V2V tabu-search Singular Vale Decomposition
Status : Published 
Date : 2012-12 
Title : OFDMA with Variable Tone Spaces 
Authors : Sungmook Lim, Gosan Noh, Jihaeng Heo, Hyungjong Kim and Daesik Hong 
Journal : IEEE Wireless Comm. Magazine 
Abstract : Next generation wireless networks such as 3GPP long term evolution - advanced (LTE-A) demand enhanced system capacity for high quality multimedia services. Carrier aggregation (CA) based on orthogonal frequency division multiple access (OFDMA) has been introduced to achieve this. In CA, each component carrier can be located on a different frequency band and each user utilizing it moves at a different speed. This results in different channel characteristics for each user. Enhancing the system capacity in this environment requires a multiple access scheme that considers different channel characteristics among users. However, conventional OFDMA using fixed tone space (called OFDMAFTS)does not consider user-specific channel characteristics, resulting in capacity degradation.
In this article, we propose a new OFDMA system with variable tone spaces (OFDMA-VTS) as an approach to enhancing the system capacity. OFDMA-VTS selects the tone space suitable for each user by considering user-specific channel characteristics in CA. When inter-symbol interference (ISI) is dominant due to a long delay spread, the small tone space is selected to eliminate severe ISI. Conversely, when inter-carrier interference (ICI) due to a large Doppler spread severely degrades the system performance, the large tone space is selected to compensate ICI. In the proposed OFDMA-VTS, each user adaptively selects the optimal tone space needed to minimize the total interference of ISI and ICI, therefore enhancing the system capacity. 
URL : http://ieeexplore.ieee.org/xpl/articleDe...er=6393526 
Download : http://mirinae.yonsei.ac.kr/?module=file...ff5b9ba7bb 

Lim, S.; Noh, G.; Heo, J.; Kim, H.; Hong, D.; , "OFDMA with variable tone spaces," Wireless Communications, IEEE , vol.19, no.6, pp.113-120, December 2012
doi: 10.1109/MWC.2012.6393526
keywords: {Bandwidth;Bit error rate;Delay;Doppler effect;OFDM;Synchronization;Transmitters;}
URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6393526&isnumber=6393507

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» [IEEE Wireless Commun. Mag.] Sungmook Lim, Gosan Noh, Jihaeng Heo, Hyungjong Kim and Daesik Hong,"OFDMA with Variable Tone Spaces", IEEE Wireless Comm. Magazine, Dec. 2012 file Published  2012-12