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In cognitive radio (CR) networks, unlicensed (cognitive) users can exploit the licensed frequency bands by using spectrum sensing techniques to identify spectrum holes. This paper proposes a distributed compressive spectrum sensing scheme, in which the modulated wide-band converter can apply compressed sensing (CS) directly to analog signals at the sub-Nyquist rate and the central fusion receives...
This paper offers a study on Rayleigh channel capacity of opportunistic cooperative networks in conjunction with adaptive transmission where the source adapts its rate and/or power level according to the changing channel conditions while the best relay simply amplifies and forwards the signals. To this end, the upper and lower bound of the end-to-end effective signal-to-noise ratio (SNR) for an arbitrary...
This paper provides a complete study on the end-to-end performance of multi-hop wireless communication systems equipped with re-generative (decode-and-forward) relays over Rayleigh fading channels assuming single-antenna terminals. More specifically, the probability density function (pdf) of the tightly approximated end-to-end SNR of the systems is derived. Using this approximation allows us to avoid...
Cooperative transmission is an efficient solution to improve the performance of wireless communications over fading channels without the need for physical co-located antenna arrays. Current cooperative transmission schemes for two users can only achieve maximum diversity order of 2. In this paper, we propose a novel cooperative transmission scheme with amplify-and-forward relay which can obtain the...
This paper studies the application of coded cooperation in wireless relay network. In wireless relay network only one user transmit data and the cooperative users assist the active user to get the spatial diversity. Exploit the idle time of active user we get the time diversity along with the spatial diversity. We investigate the rate compatible puncture convolutional (RCPC) code based coded cooperation...
Signal distortion due to the path loss, shadow, and multi-path fading is very serious in radio channel. In this paper, we propose CDMA-OFDM cooperative communication system based on DFP (decode and forward protocol) to overcome these phenomena using spread spectrum technique, orthogonal subcarrier, and the space diversity. We simulated proposed system under Rayleigh flat fading channel environment...
Decode-and-forward cooperative communications protocol (DFP) allows single-antenna wireless users to obtain the powerful benefits of multi-antenna systems without physical antenna arrays. In addition, the sum-product algorithm (SPA) is extremely efficient for decoding the linear block codes with sparse parity-check matrix. Therefore, we propose a combination of DFP with the modified SPA where only...
Cooperative communications among the users in the multiple access wireless environments is an efficient way to obtain the powerful benefits of multi-antenna system without the demand for physical arrays. This paper proposes a solution to optimize the weights of partnering user's signal for the minimum error probability at the output of maximum likelihood (ML) detector. Found weights adapt the propagation...
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