Coherently Radiating Periodic Structures for Feeding Concentric Rings Array with Reduced Number of Phase Shifters.

This paper presents the application of CORPS (coherently radiating periodic structures) for feeding CRA (concentric rings array) with a reduced number of phase shifters. The proposed design technique for the structure of concentric rings provides a better scanning capability with respect to other existing configurations. This design technique utilizes 2 × 3 or 4 × 7 CORPS networks depending on the configuration or the number of antenna elements in the phased array system. These CORPS networks are set strategically in the feeding network to provide several advantages with respect to others in the scanning capability and the reduction of the number of phase shifters of the array system. The contribution of this paper is the full antenna system design of phased CRA for analyzing scanning and the reduction of phase shifters. The proposed phased array reduces the number of phase shifter devices in CRA for a scanning range of ±25° in the elevation plane. Differential evolution (DE) was applied to optimize the amplitudes of the proposed system. Several design cases were analyzed using full-wave simulation results to verify the phased array model and to take mutual coupling into account. Full-wave simulation results provide radiation patterns with low SLL in all scanning directions. The proposed phased array was validated by experimental measurements of the full antenna system prototype.

Novel Design Techniques for the Fermat Spiral in Antenna Arrays, for Maximum SLL Reduction.

This paper presents novel design techniques for the Fermat spiral, considering a maximum side lobe level (SLL) reduction. The array system based on a Fermat spiral configuration considers techniques based on uniform and non-uniform amplitude excitation. The cases of uniform amplitude excitation are the golden angle and the optimization of the angular separations. The cases of non-uniform amplitude excitations consider a raised cosine distribution and the optimization of the amplitude excitations through the Fermat spiral array. In this study, the method of genetic algorithms (GA) was used in the cases to find the values of the angular separations and the amplitude excitations of the Fermat spiral array. A performance evaluation was conducted for all these design cases, considering the Fermat spiral geometry. These design cases were validated using electromagnetic simulation to take mutual coupling into account and consider the effect of the antenna element pattern in each proposed design case.

Coherently Radiating Periodic Structures to Reduce the Number of Phase Shifters in a 2-D Phased Array.

This paper illustrates the application of CORPS (coherently radiating periodic structures) for feeding 2-D phased arrays with a reduced number of phase shifter (PS) devices. Three design configurations using CORPS are proposed for 2-D phased arrays. The design model of phased array for these configurations considers the cophasal excitation required for this structure to set a strategic way for feeding the antenna elements and reducing the number of PS devices. Blocks of 2 × 3 and 4 × 7 CORPS networks depending on the configuration in the 2-D phased array are set strategically in the feeding network to generate the cophasal excitation required in the antenna elements. These design configurations used for feeding the antenna elements in the planar array geometry provide several advantages with respect to others in the scanning capability and the reduction of the number of PS devices of the array system. The full-wave simulation results for the proposed configurations in 2-D phased arrays provide a reduction in the number of PSs of until 69% for a scanning range of ±25° in elevation and ±40° in azimuth. The application of the raised cosine amplitude distribution could generate radiation patterns with a SLL_PEAK ≈ -19 dB and SLL_PEAK ≈ -23 dB for the design proposed configurations in all the scanning range.

Distributed Algorithm for Base Station Assignment in 4G/5G Machine-Type Communication Scenarios with Backhaul Limited Conditions.

A progressive paradigm shift from centralized to distributed network architectures has been consolidated since the 4G communication standard, calling for novel decision-making mechanisms with distributed control to operate at the network edge. This situation implies that each base station (BS) must manage resources independently to meet the quality of service (QoS) of existing human-type communication devices (HTC), as well as the emerging machine type communication (MTC) devices from the internet of things (IoT). In this paper, we address the BS assignment problem, whose aim is to determine the most appropriate serving BS to each mobile device. This problem is formulated as an optimization problem for maximizing the system throughput and imposing constraints on the air interface and backhaul resources. The assignment problem is challenging to solve, so we present a simple yet valid reformulation of the original problem while using dual decomposition theory. Subsequently, we propose a distributed price-based BS assignment algorithm that performs at each BS the assignment process, where a novel pricing update scheme is presented. The simulation results show that our proposed solution outperforms traditional maximum signal to interference plus noise ratio (Max-SINR) and minimum path-loss (Min-PL) approaches in terms of system throughput.

Non-Uniform Concentric Rings Design for Ultra-Wideband Arrays.

This paper presents the design of aperiodic concentric ring arrays for ultra-wide bandwidths (UW-ACRA). This design of ultra-wideband arrays considers the synthesis of concentric rings in two cases: 1) non-uniform spacing between rings with non-uniform spacing between antenna elements of the same ring (UW-ACRAelements); and 2) non-uniform spacing between rings assuming that spacing between antenna elements of the same ring to be equal (UW-ACRArings). This is in order to eliminate the occurrence of grating lobes and generating array structures with useful ultra-wideband properties. The synthesis process is carried out by the well-known method of differential evolution (DE). Wireless sensor networks can take advantage of these properties to achieve less data traffic, efficient delivery of information and better energy efficiency.