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This paper proposes a low complexity peak-to-average power ratio estimation scheme for OFDM systems. The new scheme introduces a non-equal-distance estimation based on triangle interpolation, which approximates higher oversampling samples by lower oversampling samples. Simulation shows the new scheme can achieve a good approximating to signal distribution of the real over-sampled OFDM signal. Furthermore,...
This paper presents a performance analysis of vector orthogonal frequency division multiplexing (VOFDM) in multipath fading channel to investigate its diversity gain, performance limitation and the choice of dimension in the vector block for the design of a low-complexity receiver. Based on the analytically derivation, it is first verified that VOFDM can realize the maximum diversity gain while the...
Partial transmit sequences (PTS) is a class of distortless PAPR reduction techniques for OFDM systems. However, the high complexity of PTS remains a problem. In the work by Baxley and Zhou (2007), the authors show that the PAPR reduction performance of PTS is not as good as that of another distortless technique-selected mapping (SLM) with the same computational complexity. To alleviate this problem,...
Partial transmit sequence (PTS) is an attractive distortless peak-to-average power ratio (PAPR) reduction technique for orthogonal frequency division multiplexing (OFDM) system. However, the complexity of PTS increases exponentially with the number of sub-blocks as it requires an exhaustive searching over all phase factor combinations. In this paper, we explored the correlation among the multiple...
Selected mapping (SLM) is a promising peak-to-average power ratio (PAPR) reduction technique for orthogonal frequency division multiplexing (OFDM) system. In SLM, phase sequences are combined with the data for generating alternative signals, so as to reduce the PAPR. In this paper, a new criterion is developed to examine the effects of different phase sequence sets in SLM-OFDM based on the mathematical...
In interference-limited wireless cellular systems, interference avoidance and interference averaging are widely adopted to combat co-channel interference. In different types of wireless networks, these two basic frequency planning methods are implemented under variable system deployment strategies. With respect to the IEEE 802.16 OFDMA network, interference avoidance is usually carried out by carefully...
In this paper, the problem of cell search for IEEE 802.16e OFDMA systems is addressed, which includes two steps: frame detection and cell ID identification. We propose two novel frame detection algorithms: one is based on the pseudo-periodicity property of the preamble signal in time-domain (TD algorithm), and the other one is based on the Euclidean distance in frequency-domain (FD algorithm). In...
In this paper, we present and analyze an interference avoidance scheme for OFDM cognitive radio systems. From an active suppression point of view, it effectively prevents the negative effect of intercarrier interference that a cognitive radio may inflict on primary transmission due to frequency offset. At the same time, it ensures bandwidth efficiency of secondary transmission. Based on the least...
The rate adaptive resource optimization problem in OFDMA systems is addressed. A novel cross-layer subcarrier and bit allocation algorithm is proposed, which aims to maximize the system throughput with the overall transmit power constraint and user rate proportionality constraint. Different from existing non-cross-layer methods, the algorithm makes allocation policy based on not only channel condition...
A novel subcarrier and bit allocation algorithm for multiuser OFDM system is presented in this paper. The algorithm aims to achieve a maximum transmit rate subject to the overall transmit power constraint and user rate proportionality constraint. The algorithm consists of two steps. In the subcarrier allocation step, the power is assumed to be uniformly allocated on each subcarrier and the subcarriers...
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