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In this paper, we propose a p-weighted noise reduction algorithm to improve the accuracy of channel estimation in Orthogonal Frequency Division Multiplexing (OFDM) systems. A SNR and speed adaptive weighting factor p is introduced, which can efficiently reduce the noise. After that, an exact expression of the optimal value of p under piecewise linear interpolation in time domain are derived, as well...
This paper proposes a spatial time-division multiple access (STDMA) based scheme (STBS) to enhance the system throughput in cognitive radio wireless networks. Especially, the proposed scheme is suitable for the situation when the available number of channels is far less than the number of secondary users (SUs). The system design includes: 1) a novel criterion based on SINR constraint (SC) to determine...
We consider a two-user Gaussian interference channel with a relay. Specifically, two source-destination pairs and the relay share a single common channel, and the relay receives messages from both sources, and assists them in communicating the messages to their respective destinations. We propose two relaying schemes using "amplify-and-forward" (AF). For each of two modes considered, we...
In this paper, link adaptation, which dynamically selects modulation level and coding rate according to the channel condition, and several multi-input multi-output (MIMO) transmission modes are studied. As we know, the subchannels' signal-to-noise radio (SNR) by singular value decomposition (SVD) are unequal, which requires different modulation and coding schemes (MCS) to maximize the throughput....
In this paper, an autoregressive channel prediction model is presented for cognitive radio(CR) systems to estimate spectrum holes. This model adopts a second-order autoregressive process and a Kalman filter. A Bayes risk criterion for spectrum hole detection is presented by considering interference temperature and channel idle probability. Theoretical analysis and simulations show that CR systems...
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