Results 161 to 170 of about 22,554 (188)
Some of the next articles are maybe not open access.
2006
Abstract In this paper we describe an adaptive method for maximizing the sumrate in the uplink of a multi-user multi-carrier system. Based on theoptimum power allocation, which is computed by the capacity-achievingiterative water-fllling algorithm, we accordingly assign the users to thecorresponding subcarriers.
S. Pfletschinger, F. Bader
openaire +1 more source
Abstract In this paper we describe an adaptive method for maximizing the sumrate in the uplink of a multi-user multi-carrier system. Based on theoptimum power allocation, which is computed by the capacity-achievingiterative water-fllling algorithm, we accordingly assign the users to thecorresponding subcarriers.
S. Pfletschinger, F. Bader
openaire +1 more source
Approximability of OFDMA Scheduling
2009In this paper, we study the complexity and approximability of the orthogonal frequency-division multiple-access (OFDMA) scheduling problem with uniformly related communication channels.
Marcel Ochel, Berthold Vöcking
openaire +1 more source
Coded Cooperation in OFDMA Systems
2006 40th Annual Conference on Information Sciences and Systems, 2006A novel time-frequency cooperative communication strategy is proposed for coded OFDMA system over quasi-static frequency-selective Rayleigh fading. To take advantage of the frequency dispersion, each user transmits his partner's and his own data on different subcarriers spreading over the entire available bandwidth.
Jun Niu, I-tai Lu
openaire +1 more source
2008
Let us give an overview how wireless technology takes a smooth coarse from singlecarrier to OFDMA to understand the necessity for robust communication and better efficiency.
openaire +1 more source
Let us give an overview how wireless technology takes a smooth coarse from singlecarrier to OFDMA to understand the necessity for robust communication and better efficiency.
openaire +1 more source
OFDMA for underwater acoustic communications
2011 49th Annual Allerton Conference on Communication, Control, and Computing (Allerton), 2011We investigate the possibility of using orthogonal frequency division multiple access (OFDMA) for design of efficient underwater acoustic (UWA) networks. The major challenge for the OFDMA-based UWA communication systems is the Doppler-induced frequency scaling, which may cause severe intercarrier interference (ICI), and depending on the particular user
Kai Tu +3 more
openaire +1 more source
2010
IEEE 802.16 physical (PHY) layer is characterized by Orthogonal Frequency Division Multiplexing (OFDM), Time Division Duplexing, Frequency division Duplexing, Quadrature Amplitude Modulation and Adaptive Antenna Systems. After discussing the basics of OFDM and Orthogonal Frequency division Multiple Access (OFDMA), scalable OFDMA is presented and ...
Ramjee Prasad, Fernando J. Velez
openaire +1 more source
IEEE 802.16 physical (PHY) layer is characterized by Orthogonal Frequency Division Multiplexing (OFDM), Time Division Duplexing, Frequency division Duplexing, Quadrature Amplitude Modulation and Adaptive Antenna Systems. After discussing the basics of OFDM and Orthogonal Frequency division Multiple Access (OFDMA), scalable OFDMA is presented and ...
Ramjee Prasad, Fernando J. Velez
openaire +1 more source
Efficient OFDMA for LiFi Downlink
Journal of Lightwave Technology, 2018Light-fidelity (LiFi) relies on visible light communication to provide multiuser access in a small cell. For higher throughput, this paper studies the resource allocation problem for an orthogonal frequency-division multiplexing access scheme for LiFi downlink transmissions and presents a joint design of the bias level, power and subcarrier allocation.
Xintong Ling +4 more
openaire +1 more source
Punctured pilots for OFDMA communications
2011 IEEE 54th International Midwest Symposium on Circuits and Systems (MWSCAS), 2011In this paper, we propose the punctured pilots for channel estimation in OFDMA systems. These are pilots additionally inserted, after puncturing the modulated OFDMA symbols, to enhance channel estimation performance, without lessening bandwidth efficiency.
Sung-Yoon Jung, Sunghwan Kim
openaire +1 more source
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
openaire +2 more sources
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
openaire +2 more sources
Opportunistic Feedback in OFDMA Downlink
IEEE GLOBECOM 2007-2007 IEEE Global Telecommunications Conference, 2007This paper presents an opportunistic feedback (OF) protocol that reduces the amount of channel-state-information (CSI) feedback for the OFDMA downlink system. The OF protocol associates a channel value instead of a user to each feedback slot. The users access the slots opportunistically based on their channel state measurement for each tone.
Rajiv Agarwal +3 more
openaire +1 more source