This paper proposes a new low complexity angle of arrival (AOA) method for signal direction estimation in multi-element smart wireless communication systems. The new method estimates the AOAs of the received signals directly from the received signals with significantly reduced complexity since it does not need to construct the correlation matrix, invert the matrix or apply eigen-decomposition, which are computationally expensive. A mathematical model of the proposed method is illustrated and then verified using extensive computer simulations. Both linear and circular sensors arrays are studied using various numerical examples. The method is systematically compared with other common and recently introduced AOA methods over a wide range of scenarios. The simulated results show that the new method has several advantages in terms of reduced complexity and improved accuracy under the assumptions of correlated signals and limited numbers of snapshots.

The scattering parameter formulation for the envelope correlation in an(N,N)MIMO antenna array has been modified to take the intrinsic antenna power losses into account. This method of calculation provides a major simplification over the use of antenna radiation field patterns. Its accuracy is illustrated in three examples, which also show that the locations of the correlation minima are sensitive to the intrinsic losses.

A modified indoor path loss prediction model is presented, namely, effective wall loss model. The modified model is compared to other indoor path loss prediction models using simulation data and real‐time measurements. Different operating frequencies and antenna polarizations are considered to verify the observations. In the simulation part, effective wall loss model shows the best performance among other models as it outperforms 2 times the dual‐slope model, which is the second best performance. Similar observations were recorded from the experimental results. Linear attenuation and one‐slope models have similar behavior, the two models parameters show dependency on operating frequency and antenna polarization.

Other than the conventional fast Fourier transform (FFT) for multicarrier modulation, a new approach for multicarrier modulation (MCM) has been known. Meanwhile, multicarrier modulation involves dividing the broadband channel into many orthogonal but overlapping narrowband carriers. In an OFDM modulation based multicarrier system using the FFT, a cyclic prefix (CP) is inserted after each symbol frame to combat the effects of inter symbol interference (ISI). By inserting the CP, which results in spectral inefficiency OFDM schemes trades up to 25% of the transmit bandwidth. A new MCM approach that is void of the expense is the wavelet transform-based systems. These systems also have very suppressed side-lobes and exhibit improved BER performance. In wavelet based systems, the latest challenge in its implementation is in the channel estimation. In this work we have studied the performance of the FFT based OFDM system against wavelet transform (WT) based multicarrier system using a simple zero forcing (ZF) equalization in time domain. The studied system shows some improved BER performance.

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In this paper, a simplified approach for implementing QO-STBC is proposed and evaluated with improved performance. It is based on the Hadamard matrix, in which the scheme exploits the Hadamard matrix property to attain full diversity. Hadamard matrix has the characteristic that diagonalizes a quasi-cyclic matrix and consequently, a decoding matrix so that a diagonal matrix which permits linear decoding is achieved. Using quasicyclic matrices in designing QO-STBC systems requires that the codes should be rotated to reasonably separate one code from another such that error floor in the design can be minimized. It will be shown that, orthogonalizing the secondary codes and then imposing the Hadamard criteria of the scheme can be well diagonalized. The results of this simplified approach demonstrate full diversity and better performance than the interference-free QO-STBC. Results show about 4 dB gain with respect to the interference-free QO-STBC scheme and it performs alike with the earlier Hadamard based QO-STBC designed with rotation. These results achieve the consequent mathematical proposition of the Hadamard matrix and its property is also shown in this study.

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