In this letter, to overcome the drawbacks in reconfigurable antennas and maintain all the advantages in planar antennas, a compact 12 port integrated UWB and narrow band (NB)/wideband antennas for cognitive radio MIMO applications with polarisation diversity is presented. The proposed system has one pair of UWB antennas for sensing the spectrum and five pairs of NB/wideband antennas for communication. Each pair has two identical antennas, which are orthogonal to each other for polarisation diversity. Sensing antennas linked with ports (P1 and P7) have operating bandwidth of 3–11 GHz, whereas the antennas linked with ports (P2 and P8), (P3 and P9), (P4 and P10), (P5 and P11), and (P6 and P12) have operating bandwidths of 3.5–5.8 GHz, 2.8–3.5 GHz and 5.6–8 GHz (dual band), 8–8.4 GHz and 9–9.8 GHz (dual band), 8.4–9 GHz, and 9.8–11 GHz, respectively. Moreover, the overall volume of the antenna is 58mm × 50mm × 1.6 mm and the entire UWB spectrum is covered by NB/wideband antennas. Also, without any decoupling network, isolation of better than 20 and 15 dB is achieved between every two identical and non‐identical antennas, respectively.
Spectrum sensing is the main feature of cognitive radio technology. Spectrum sensing gives an idea of detecting the presence of the primary users in a licensed spectrum. In this paper we compare the theoretical results of detection probability of different fading environments like Rayleigh, Rician, Nakagami-m, Weibull fading channels with the simulation results using energy detection based spectrum sensing. The numerical results are plotted as f P Vs d P for different SNR values, fading parameters. It is observed that Weibull fading channel performance is better than other fading channels by using energy detection in spectrum sensing. A MATLAB simulation test bench has been implemented to know the performance of energy detection in different fading channel environment.
The modified generalized quadrature spatial modulation (mGQSM) scheme is introduced to improve the transmission rate of the spatial modulation (SM) and quadrature SM (QSM). In mGQSM, the information symbols are separated as real and imaginary coefficients, which are modulated on in-phase and quadrature dimensions, respectively. In addition, this scheme presented a novel codebook design to enhance the rate of 1 bit per channel use over generalized QSM (GQSM). In this paper, we present mGQSM and reduced codebook mGQSM (RC-mGQSM) system performances over Nakagami-m, Rayleigh, and Rician fading channels. However, the Rayleigh fading is a special case of Nakagami-m fading when m = 1. For the computer simulations, we use several values for the Nakagami parameter, m, and Rician factor, K. We present the mGQSM and RC-mGQSM system performances and compare them to the GQSM, QSM, and SM system performances, using the maximum-likelihood (ML) detection. For the RC-mGQSM scheme, we present a low-complexity detection method. We also present the performances of mGQSM and SM systems in the presence of imperfect channel conditions.
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