WSNs are characterized by limited energy constraints. This characteristic poses considerable challenge on design of routing protocols. Therefore, many designers and researchers focus on architectures and algorithms that allow energy-efficient operation of WSNs. One of the popular algorithms in this regard is clustering algorithm. Thus, there are many routing protocols based on clustering algorithm has been proposed for WSNs, the functionality of these protocols is divided into cluster heads (CHs) selection and cluster formation. However, CHs selection is one of the very important problems in routing protocols applications and can drastically impact the network lifespan thereby energy conservation task for WSNs. In this paper, we propose a new routing approach called Energy-efficient fuzzy logic cluster head (EEFL-CH); it is an improvement of LEACH protocol. The goal of this approach is to decrease energy consumption in terms of network lifetime extension using three fuzzy parameters. These parameters are residual energy, expected efficiency, and closeness to base station. Simulation results show that EEFL-CH approach has the better result as compared with LEACH and LEACH-ERE routing protocols.

WSNs have many applications in modern life. Thus, optimization of the network operation is required to maximize its lifetime. The energy is a major issue in order to increase the lifetime of WSNs. The clustering algorithm is one of the proposed algorithms to enhance the lifetime of WSNs. The operation of the clustering algorithm is divided into cluster heads (CHs) selection and cluster formation. However, most of the previous works have focused on CHs selection, and have not considered the cluster formation process, which is the important issue in clustering algorithm based routing schemes, and it can drastically affect the lifetime of WSNs. In this paper, a Fuzzy Logic based Clustering Algorithm for WSN (CAFL) has been proposed to improve the lifetime of WSNs. This approach uses fuzzy logic for CHs selection and clusters formation processes by using residual energy and closeness to the sink as fuzzy inputs in terms of CH selection, and residual energy of CH and closeness to CHs as fuzzy inputs in terms of clusters formation. Simulation results justify its efficiency.

The QUIC protocol, which was originally proposed by Google, has recently gained a remarkable presence. Although it has been shown to outperform TCP over a wide range of scenarios, there exist some doubts on whether it might be an appropriate transport protocol for IoT. In this paper, we specifically tackle this question, by means of an evaluation carried out over a real platform. In particular, we conduct a thorough characterization of the performance of the MQTT protocol, when used over TCP and QUIC. We deploy a real testbed, using commercial off-the-shelf devices, and we analyze two of the most important key performance indicators for IoT: delay and energy consumption. The results evince that QUIC does not only yield a notable decrease in the delay and its variability, over various wireless technologies and channel conditions, but it does not hinder the energy consumption.

The design and simulation of a wideband four-port steerable beamforming networks using a 4×4 Butler matrix for the 2.4 GHz applications is presented. The aim of this work is to develop an antenna array feeding network based on Butler matrix with a large bandwidth in order to cover the IEEE 802.11b/g/n band. In order to achieve wideband features, the matrix uses two-section branch-line couplers and four-section branch-line crossovers instead of the standard ones. The proposed circuit exhibits a high isolation and wideband 4×4 Butler matrix designed and simulated by using a single-layer FR-4 substrate, which covers the frequency band ranging from 2.1 GHz to 2.75 GHz. The return losses and the isolation are better than 28 dB and 30 dB, respectively, with its good performance is more suitable for IEEE 802.11b/g/n and ISM applications.

Energy efficiency and throughput are critical factors in the design routing protocols of WSNs. Many routing protocols based on clustering algorithm have been proposed. Current clustering algorithms often use cluster head selection and cluster formation to reduce energy consumption and maximize throughput in WSNs. In this chapter, the authors present a new routing protocol based on smart energy management and throughput maximization for clustered WSNs. The main objective of this protocol is to solve the constraint of closest sensors to the base station which consume relatively more energy in sensed information traffics, and also decrease workload on CHs. This approach divides network field into free area which contains the closest sensors to the base station that communicate directly with, and clustered area which contains the sensors that transmit data to the base station through cluster head. So due to the sensors that communicate directly to the base station, the load on cluster heads is decreased. Thus, the cluster heads consume less energy causing the increase of network lifetime.