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Correlation difference timing scheme (CDTS) algorithm based on cross-correlation difference and correlation summation peak protection is proposed to address the critical issue of symbol timing synchronization for MB-OFDM based UWB systems. The two step synchronization scheme attempts to locate the start sample of the frame sequence (FS) by firstly calculating the cross correlation difference of received...
In cooperative relay systems, relayed signals propagate through different channels and are received at the destination node with distinct timing and carrier frequency offsets (CFOs). This feature makes synchronization a rather challenging task as compared with centralized multiple-input multiple-output systems. Unlike conventional preamble designs with good correlation properties only in time domain...
In this paper, an iterative interference suppression algorithm based on energy spreading transform (EST) is proposed. The performance of interference suppression can be significantly improved by our proposed iteration scheme between demodulator and parameter estimator. The energy of residual interference after initial narrowband interference (NBI) suppression is spread over the whole band by EST,...
A novel chaotic FH-OFDM communication system based on OFDM (Orthogonal Frequency Division Multiplexing) and FH (Frequency Hopping) is presented. The carriers frequency of OFDM are controlled by chaotic pseudo random sequences. In every iteration period, the method adopts the different keys. It analyzes the balance, the distance and the maximum Hamming correlation of this FH sequences in theory and...
This paper investigates the sidelobe suppression techniques of orthogonal frequency division multiplexing (OFDM) based cognitive radio (CR) systems. We firstly argue that the existing sidelobe suppression algorithms cannot satisfy the special requirements of CR systems. Then we formulate the interference suppression problem of CR systems into two algorithms from capacity perspective, namely, average...
This paper investigates the problem of resource allocation in spatial multiuser access cognitive OFDM (orthogonal frequency division multiplexing) systems. The objective is to maximize the cognitive users' weighted rate sum, which is constrained by the licensed users' (LU) interference temperatures. The spatial multiuser access using singular value decomposition (MU-SVD) model is introduced to the...
A new method is proposed to construct space-frequency (SF) codes for multiple-input-multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems undergoing frequency-selective fading. The new design exploits the geometric relationship of coherent and noncoherent SF codes, and each codeword is constructed as a product of a noncoherent SF codeword and an information-bearing square...
Partial transmit sequence (PTS) is a promising technique for reducing the high peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. In PTS, multiple candidate signals are generated and the optimal signal with the lowest PAPR is selected for transmission. One drawback of PTS is that parts of the candidate signals are strongly correlated so as to degrade the...
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