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This paper considers a secondary user (SU) sharing the spectrum licensed to a primary user (PU) if limited interference caused to the latter can be guaranteed. In particular, besides the interference power constraint at the PU to protect the PU, the transmit power of the SU is also considered. Under such a setup, we consider the average bit error rate (BER) as the performance metric for the SU, and...
Multiple input multiple output (MIMO) systems provide dramatic capacity gain through an increased spatial dimension. However, the capacity gain is reduced if the channel state information (CSI) is not perfect. The more exact the CSI is, the higher capacity gain we can obtain. In order to obtain higher capacity gain, this paper analyzes the two factors which mainly affect the reliability of CSI: the...
The multiple-input-multiple-output (MIMO) technique, combined with multi-level quadrature amplitude modulation (M-QAM), has been considered a potential scheme for high data rate transmission in next generation mobile communication systems. In this paper, the symbol error rate (SER) of M-QAM MIMO system based on spatial multiplexing is analyzed and closed-form results are given under rich scattering...
Power allocation problem in Decode and Forward (DF) wireless cooperative multiplexing communication systems is considered in this paper. We first derived an analytical bit error rate (BER) expression with BPSK modulation at the relays and Zero Forcing Successive Interference Cancellation (ZF-SIC) algorithm at the destination, which gives deep insight to how different power assignments among the source...
Information theory guides us to investigate the choice of quantizers for data hiding applications. In this paper, the design of the quantizer selection rule in trellis coded quantization (TCQ) based data hiding is discussed. A novel trellis branch quantizer selection rule which changes the old state transition function and takes advantage of all trellis states is proposed so as to increase robustness...
A novel pilot design scheme and simple channel estimation algorithm for an orthogonal frequency-division multiplexing (OFDM) system with two transmit antennas is proposed in this paper. The proposed algorithm takes advantage of the essence of SFBC to reduce the interantenna interference. In the proposed channel estimation scheme, the pilot sequences for two transmit antennas are carefully designed...
A LDPC-COFDM system model based on adaptive algorithm can allocate transmit power and bits among sub-carriers according to the channel gain of each sub-channel. An adaptive power allocation algorithm, which is beneficial for log likelihood ratio decoding of LDPC coded modulation, is proposed in this paper. The simulation results show that the model can effectively improve the bit-error-rate (BER)...
Since 3G long term evolution (LTE) is launched by 3GPP recently, many multiple access (MA) schemes have been proposed for 3G LTE, such as multi-carrier (MC) - WCDMA, MC-time duplex-synchronized CDMA (MC-TD-SCDMA), orthogonal frequency division multiple access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), which includes IFDMA (interleaved FDMA) and DFT-S OFDM (DFT-spreading...
In this contribution, a hybrid detection algorithm based on QR decomposition for MIMO systems is proposed to reduce the complexity of the MIMO detection algorithm. The proposed algorithm combines vector searching with DF (decision feedback) technique to improve the reliability of the detected signals and meanwhile holds a low computational complexity. The computational complexity and BER performance...
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