OFDM Multiple Antennas Cognitive Radio Relay Synchronization CDMA Channel Estimation Spectrum Sharing Interference Cancellation Spectrum Sensing Full duplex Neural Networks Resource Allocation Stochastic Geometry Equalizer Bi-Directional Feedback Heterogeneous Networks Energy Harvesting Femtocell Device-to-Device (D2D) Idle cells FBMC Ultra-dense small cell networks Cell Search Spectral efficiency SINR mismatch problem Cross-link interference HetNet Dynamic TDD self-interference cancellation full-duplex relay in-band full-duplex system automatic repeat request (ARQ) transmission capacity (TC) full-duplex cellular Two-way communications sensing duration selection diversity GFDM interference mitigation Correlated MIMO mode selection multi-spectral outage probability achievable sum rate Cognitive relay networks Vehicular and wireless technologies bursty traffic model UL grant free NOMA Asynchronized system Reliability Latency Cellular networks LTE-TDD Iterative decoder Bi-directional full-duplex OQAM UWB MU-MIMO coexistence Link adaptation beamforming Simultaneous Sensing and Transmission CP-OFDM Long Term Evolution-Advanced Aggregate interference singular value decomposition MIMO 5G networks time-frequency efficiency K-S statistics Time spreading Windowing Vehicle-to-vehicle communication LTE-based V2V interference coordination prototype filter pilot signal TS-W-OFDM eigen decomposition link reliability interference to noise ratio tabu-search resource size control C-V2V Coexistence scenarios interference management Resource management mixed numerology Vehicle-to-Vehicle massive connectivity Complexity non-orthogonal multiple access full-spreading NOMA Filtered OFDM Singular Vale Decomposition flexible duplex 5G Cooperative systems
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