Results 181 to 190 of about 8,421 (222)
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Opportunistic Beamforming in OFDMA Systems
2010 14th Panhellenic Conference on Informatics, 2010The opportunistic beamforming (OB) technique in multicellular OFDMA networks is investigated in this paper. For this reason, three cross-layer radio resource management (RRM) algorithms for OFDMA operational scenarios that are based on typical resource allocation targets such as minimization of transmit power, maximization of throughput and ...
Dimitra Zarbouti +3 more
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Limited access to OFDMA femtocells
2009 IEEE 20th International Symposium on Personal, Indoor and Mobile Radio Communications, 2009Femtocells are a promising solution for the provision of high indoor coverage and capacity. Furthermore, OFDMA-based femtocells have proven to be highly versatile when dealing with cross-layer co-channel interference thanks to the allocation of frequency subchannels. However, concerns still exist related to the impact of the different access methods to
Alvaro Valcarce Rial +3 more
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User Separation for OFDMA Uplink
VTC Spring 2009 - IEEE 69th Vehicular Technology Conference, 2009Separating user signals in the uplink (UL) of an orthogonal frequency division multiple access (OFDMA) system without access to the subcarrier assignment scheme (SAS) is a challenging task, but it can have a number of useful applica- tions. In this paper, a semi-blind user separation algorithm is proposed, which assumes time synchronization and ...
Mustafa Emin Sahin +3 more
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, 2008 Modern wireless communications are based on the exploitation of channel behavior and/or user requirements by adapting one or more transmission parameters. Amongst several systems the OFDMA offers a lot of capabilities to the system designer allowing adapting in several ways the communications.
FANTACCI, ROMANO +2 more
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OFDMA with variable tone spaces
IEEE Wireless Communications, 2012Next generation wireless networks such as 3GPP LTE-A demand enhanced system capacity for high-quality multimedia services. Carrier aggregation based on 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.
Sungmook Lim +4 more
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On the capacity of OFDMA 802.16 systems
2006 IEEE International Conference on Communications, 2006In this paper, we calculate analytically the capacity of an OFDMA 802.16 system. We consider a multi-cell network and obtain the expected number of collisions for an arbitrary number of users in each interfering cell. We next obtain, for different SNR ratios corresponding to different modulation schemes, the probability of QoS degradation when ...
Salah-Eddine Elayoubi +2 more
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Opportunistic Spectrum Multichannel OFDMA
2007 IEEE International Conference on Communications, 2007Opportunistic Spectrum Access (OSA) is being seriously considered for the future spectrum needs. In this paper we propose a simple and effective multichannel multiple access technique for OSA networks. In our design users of an OSA network must contact the OSA Base Station to gain access to the radio resources.
Przemyslaw Pawelczak +2 more
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Interference Management of OFDMA Uplinks
2007 IEEE 65th Vehicular Technology Conference - VTC2007-Spring, 2007The next generation of wireless networks will use OFDMA (orthogonal frequency division multiple access) technology in the uplink. In OFDMA, the uplink resources assigned to a user are called tiles each of which consists of a subset of consecutive subcarriers.
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Quantifying the Diversity of OFDMA Subchannels
2007 IEEE Wireless Communications and Networking Conference, 2007Orthogonal frequency division multiple access (OFDMA) has been chosen as the radio transmission technology for future 4G wireless networks. One important reason for this choice is that OFDMA offers various forms of diversity (time, frequency, space, etc).
Patrick Hosein, Jung-Woon Lee
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A novel iterative receiver for uplink OFDMA
GLOBECOM '05. IEEE Global Telecommunications Conference, 2005., 2005In this work we consider the uplink of an OFDMA system and present a novel receiver that performs joint frequency offset acquisition, channel estimation and data detection for each active user. The proposed receiver can be used with any subcarrier assignment scheme, and it operates in an iterative fashion.
Man-On Pun +2 more
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