An optimal linear and elliptical antenna array design using black widow optimisation for 5G communication

This research illustrates a precise linear and elliptical antenna array design for synthesising the optimal far-field radiation pattern in the fifth-generation (5G) communication spectrum using a meta-heuristic optimisation technique known as black widow optimisation (BWO). 5G communication is an emerging technology with revolutionary changes in the wireless communication system with ultra-high data rate, enhanced capacity, low latency and good quality of service. An accurate antenna array design for an ideal far-field radiation pattern synthesis with a suppressed side lobe level (SLL) value and half power beam width (HPBW) is the most crucial aspect of 5G communications. A suppressed SLL is necessary to reduce interference in the entire side lobe region, whereas a low HPBW is required for long-distance communication. Here, the BWO is employed to find the optimal feeding current to each array element to lower the SLL and the HPBW value. The BWO algorithm sustains impeccable equity between the exploration and exploitation stages to impact different potential regions of the search space and generate new solutions to attain the global optima by evading the trap of local optima. The design examples of the linear antenna array (LAA) and elliptical antenna array (EAA) are illustrated in this article by applying the optimal feeding currents to each array element. Compared to the uniform antenna array and methodologies described in the recently published literature, the results obtained utilising the BWO algorithm for designing the LAAs and EAAs demonstrate a substantial development in the reduction of SLL and HPBW.     

Benefit-Based Data Caching in Ad Hoc Networks

Data caching can significantly improve the efficiency of information access in a wireless ad hoc network by reducing the access latency and bandwidth usage. However, designing efficient distributed caching algorithms is nontrivial when network nodes have limited memory. In this article, we consider the cache placement problem of minimizing total data access cost in ad hoc networks with multiple data items and nodes with limited memory capacity. The above optimization problem is known to be NP-hard. Defining benefit as the reduction in total access cost, we present a polynomial-time centralized approximation algorithm that provably delivers a solution whose benefit is at least 1/4 (1/2 for uniform-size data items) of the optimal benefit. The approximation algorithm is amenable to localized distributed implementation, which is shown via simulations to perform close to the approximation algorithm. Our distributed algorithm naturally extends to networks with mobile nodes. We simulate our distributed algorithm using a network simulator (ns2) and demonstrate that it significantly outperforms another existing caching technique (by Yin and Cao [33]) in all important performance metrics. The performance differential is particularly large in more challenging scenarios such as higher access frequency and smaller memory.     

Text extraction and document image segmentation using matched wavelets and MRF model.

In this paper, we have proposed a novel scheme for the extraction of textual areas of an image using globally matched wavelet filters. A clustering-based technique has been devised for estim ating globally matched wavelet filters using a collection of groundtruth images. We have extended our text extraction scheme for the segmentation of document images into text, background, and picture components (which include graphics and continuous tone images). Multiple, two-class Fisher classifiers have been used for this purpose. We also exploit contextual information by using a Markov random field formulation-based pixel labeling scheme for refinement of the segmentation results. Experimental results have established effectiveness of our approach.     

Development of Optical Code Division Multiple Access Based System Using Spectral Amplitude Coding via Fiber Bragg Gratings (FBGs)

Wireless Personal Communications - The multiple user’s based transmission systems are developed in the past using various multiple access techniques for fibre optic communications. Among...     

SIP-based vertical handoff between WWANs and WLANs

Future-generation wireless networks have been envisioned as the integration of various wireless access networks, including both wireless wide area networks and wireless local area networks. In such a heterogeneous network environment, seamless mobility support is the basis of providing uninterrupted wireless services to mobile users roaming between various wireless access networks. Because of transparency to lower-layer characteristics, ease of deployment, and greater scalability, the application-layer-based session initiation protocol has been considered the right candidate for handling mobility in heterogeneous wireless networks. However, SIP entails application-layer transport and processing of messages, which may introduce considerable delay. As a case study of the performance of mobility management protocols in the heterogeneous wireless networks, we analyze the delay associated with vertical handoff using SIP in the WLAN-UMTS internetwork. Analytical results show that WLAN-to-UMTS handoff incurs unacceptable delay for supporting real-time multimedia services, and is mainly due to transmission of SIP signaling messages over erroneous and bandwidth-limited wireless links. On the other hand, UMTS-to-WLAN handoff experiences much less delay, mainly contributed by the processing delay of signaling messages at the WLAN gateways and servers. While the former case requires the deployment of soft handoff techniques to reduce the delay, faster servers and more efficient host configuration mechanisms can do the job in the latter case.     

An architecture for next-generation radio access networks

With fourth-generation wireless technologies envisioned to provide high bandwidth for content-rich multimedia applications, next-generation mobile communication systems are well poised to lead the technology march. Incumbent with the new technology is the challenge of providing flexible, reconfigurable architectures capable of catering to the dynamics of the network, while providing cost-effective solutions for service providers. In this article we focus on IP-based radio access network architectures for next-generation mobile systems. We provide an insight into wireless mesh-based connectivity for the RAN network elements - using short high-bandwidth links to interconnect the network entities in a multihop mesh network for backhauling traffic to the core. A generic self-similar fractal topology, using optical wireless transmission technology, is described. We study the performance of the architecture and conclude that mesh-based architectures are well suited to provide highly scalable, dynamic radio access networks with carrier-class features at significantly low system costs.     

Energy Efficient Hardware Loop Based Optimization for CGRAs

Journal of Signal Processing Systems - Research interest and industry investment in edge computing solutions have increased dramatically in recent years. Consequent quest for balanced performance,...     

Electrical characterization and reliability study of integrated GaN power amplifier in multi-layer thin-film technology

In this work, the degradation of a GaN power amplifier (PA) integrated in a thin film multi-chip module (MCM-D) interconnect technology is investigated by means of DC and RF measurements. Failure analysis has demonstrated that improper thermal contact may cause the PA module performance degradation. Moreover, we have experimentally studied the thermal effects on the RF performance of MCM-D and low-temperature co-fired ceramic (LTCC) PAs. It shows that the device exhibits a higher output power density on a thinned MCM-D substrate than on an LTCC substrate with thermal vias, and also that the output power density can be further improved by reducing the heat spread distance between active devices and heat sink.     

Multiple-output parity bit signature for exhaustive testing

In this article we propose a multiple-output parity bit signature generation method for exhaustive testing of VLSI circuits. Given a multiple-output combinational circuit, a parity bit signature is generated by first EXORing all the outputs to produce a new output function and then feeding this resulting function to a single-output parity bit signature generator. The method preserves all the desirable properties of the conventional single-output circuits response analyzers and can be readily implemented using the current VLSI technology.