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In this paper, an adaptive tone reservation technique with optimal subcarrier allocation awareness for multi-user OFDMA systems is investigated. In general, a variety of approaches have been proposed to cope with the PAPR problem in OFDM systems. A tone reservation (TR) is an effective technique for reducing PAPR, in which it does not need to transmit any side information and there is no distortion...
Orthogonal frequency division multiple access (OFDMA) has been used for broadband wireless multiple access. The performance of OFDMA system can be improved by using multiple antennas with space time coding to get transmit and receive diversity. Channel information estimated at receiver for space time decoding can be used for sub-channels allocation at transmitter. In this paper, we propose a method...
In this paper, we study the power allocation scheme for a single user, multi-channel system, e.g. orthogonal frequency- division multiplexing (OFDM) systems, under time-variant wireless fading channels. We assume the receiver feeds back perfectly estimated channel state information (CSI) to the transmitter after a processing delay. The objective of the power allocation is to maximize physical (PHY)...
In this paper, we consider the uplink of a single cell network with K users simultaneously communicating with a base station using OFDM modulation over N carriers. In such a scenario, users can decide their power allocation based on three possible Channel State Information(CSI) levels, which are called complete, partial and statistical. The optimal solutions for maximizing the average capacity with...
Some communication applications, like multimedia, deliver data of different importance classes allowing unequal error protection (UEP) levels. In this paper, a multiple-input multiple-output (MIMO) system using orthogonal frequency division multiplexing (OFDM) is considered with a new UEP bit-loading algorithm based on the non-UEP algorithm by Chow, Cioffi, and Bingham. In the proposed bit-loading...
This paper investigates effects of pilot assisted channel estimation on dynamic resource allocation in a multiuser orthogonal frequency division multiplexing (OFDM) system. The channel estimation is done in each OFDM symbol through least-squared error (LSE) or minimum mean-squared error (MMSE) algorithm. The performance of each of these algorithms is evaluated through computer simulations. The maximal...
In this paper, we consider a new channel probing scheme for opportunistic scheduling in the uplink of orthogonal frequency division multiplexing (OFDM)-based wireless systems. To reduce signaling overhead for the probing, we consider a two-step channel probing process; called pre-probing and mainprobing. Good subchannels are first estimated through the pre-probing process using a probing signal transmitted...
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