In this work, a novel antenna structure has been proposed, which consists of multiple sub-array features i.e., a field selectable beam (90°, 180°, 270°, and 360°) and the choice of gain (11.16, 14.59 and 17.25 dBi) that can be easily adapted to cater for the dynamic scenarios in the transportation environment. The sub-arrays were designed using the microstrip patch antenna (MPA) concept with capacitive feed and dual substrate stacked up configuration for superior operating bandwidth covering the entire 802.11ac (5.17 to 5.85 GHz Industrial Scientific and Medical (ISM) band), in addition to the extended coverage for 4.92 to 4.98 GHz licensed band with narrow azimuth beamwidth of 24°. The sub-array was designed, simulated and experimentally evaluated and the beamforming results revealed that the antenna structure can be integrated with beamforming concepts to provide an enhanced wireless link between the ground base station and the mobile terminals that allows beam steering to focus on the targeted direction and null the interference directions with small beam width. It is expected that the proposed configurable gain/beam beamforming antenna array will further reduce the deployment cost and enhance the anti-interference performance by two-fold, and shall bring the user experience in the transportation market to the next level.

Flat top beam pattern synthesis is increasingly important for beamformer in high mobility scenarios due to the rapid change of Direction of Arrival (DOA). A Zero Placement for Flat Top (ZPFT) beam pattern synthesis algorithm is presented in this article. It works in Z domain directly and breaks down the total response into two portions. The first portion satisfies the beamwidth requirement with low Sidelobe Level (SLL) which is realized through algorithms like Dolph-Chebyshev algorithm. The second portion is then used to create a broadening effect. The location of the broadening zeros are derived using principles result from the broadening effect analysis of two quadratic functions. Compared to conventional Finite Impulse Response (FIR) method or iterative methods, the proposed method identifies the zeros of the array factor directly and computes the weight without iteration. Since it works in the spatial angle domain directly, the steering of the mainlobe beam could be implemented through a simple angle shift. Numerical simulation confirms the effectiveness of the algorithm. ZPFT can achieve 22dB lower SLL while maintaining the same main beam performance as compared with FIR method for an Uniform Linear Array (ULA) with 7 elements. It can achieve the same optimal performance as the iteration based global optimisation techniques like Semi-Definite Relaxation (SDR) with about 380 times less computing time in an Intel Core i7 Windows platform. ZPFT can steer the main beam easily in real time. All these make it an ideal candidate for high mobility applications where the DOA changes rapidly.

A fast algorithm to generate the Blocking Matrix for Generalized Sidelobe Canceller (GSC) beamforming is proposed in this paper. The proposed algorithm uses a Simplified Zero Placement Algorithm (SZPA) to directly generate the column vectors of the Blocking Matrix using the polynomial method. The constrained signal incoming angles are converted to spatial frequency and designated as zero locations in the Z domain. Independent vectors that span the whole left null space of the constraint matrix is then built using a simple shift operation. The algorithm also supports the derivative constraints used for robust beamforming. Compared to the conventional methods based on Singular Value Decomposition (SVD), the SZPA algorithm can generate Blocking Matrix more than 9 times faster for scenarios with 15 constraints and will be even more advantageous for more constraints. The Blocking Matrix generated by the SZPA and SVD methods is then implemented in the same GSC architecture for performance evaluation. The numerical simulation confirms that the same overall optimum state performance and learning speed can be achieved. By reducing the calculation time of blocking matrix from 1.541ms of SVD method to 0.168ms, the proposed SZPA algorithm is fast and insensitive to the number of constraints as the required calculation time incremental for each additional constraint with SZPA is only around 1/16 of SVD method. This makes it suitable for scenarios like train to infrastructure communication in High Speed Rail (HSR) where there are multiple constraints and frequent constraints update is required.

A unique and ideal integration of wavelet-based total variation (WATV) and empirical Wiener denoising method is proposed in this article to significantly enhance the signal-to-noise ratio (SNR) while preserving the characteristics of a lung sound signal. While individual wavelet-based denoising filters based on a single basis function have been employed in the past, the outcome has been unsatisfactory because only significant (signal) wavelet coefficients are considered for denoising analysis. The new wavelet-based empirical Wiener (WATV-Wiener) hybrid technique, proposed here, takes into account both significant and insignificant (noise) wavelet coefficients of the noisy signal. An intensive analysis of selecting and fine-tuning the WATV-Wiener filter parameters is presented here through the simulation studies. The WATV-Wiener filter applied here onto different 1-D lung sound signals of different noise levels has led to an optimal root mean square error (RMSE) compared with seven other state-of-the-art filters reported in the literature. The optimal parameters achieved through our simulation studies led to a 3–20-dB improvement in SNR, and the average SNR was improved by 4–30 dB in our experiment. We also observed that the WATV-Wiener filter is less sensitive to the variation of SNR values of the input signal. Furthermore, the WATV-Wiener filter obtains similar SNR performance between continuous piecewise signal (wheeze) and noncontinuous piecewise signal (crackle) in both simulation and experimental studies.

In the smart antenna system, the transmit and receive (T/R) module is one of the core components as it accounts for nearly 45% of the overall smart antenna system cost. Due to the high implementation cost of the T/R module, the literature was mainly centered around the military and satellite radar applications. However, over the years, the cost of the T/R module has been reduced drastically by leveraging on the advanced manufacturing technology, volume production pricing and adaptation of the commercially available off-the-shelf components, as a result, the adoption of the T/R module in commercial and industrial application become possible. In this work, we have proposed a commercially affordable T/R module that operates in 4.9-5.9 GHz band for commercial and industrial applications. The T/R module was designed, calibrated, and characterized for use in the beamforming smart antenna system. The design process including the circuit, schematic and printed circuit board (PCB) were highlighted. The proposed recursive calibration process managed to correct the phase error to ±1° and amplitude error to ±0.2 dB. In addition, the amplitude distribution of 0.5-1-1-0.5 combination has successfully suppressed the side-lobe level (SLL) to -28.7 dB for 0°, -22.71 dB for ±20° and -12.77 dB for ±40° beam steering. This work is aimed to promote the adoption of the T/R module into the commercial and industrial applications such as public or government infrastructure.