Recent developments in electronics and wireless communications have enabled the improvement of low-power and low-cost wireless sensors networks (WSNs). One of the most important challenges in WSNs is to increase the network lifetime due to the limited energy capacity of the network nodes. Another major challenge in WSNs is the hot spots that emerge as locations under heavy traffic load. Nodes in such areas quickly drain energy resources, leading to disconnection in network services. In such an environment, cross-layer cluster-based energy-efficient algorithms (CCBE) can prolong the network lifetime and energy efficiency. CCBE is based on clustering the nodes to different hexagonal structures. A hexagonal cluster consists of cluster members (CMs) and a cluster head (CH). The CHs are selected from the CMs based on nodes near the optimal CH distance and the residual energy of the nodes. Additionally, the optimal CH distance that links to optimal energy consumption is derived. To balance the energy consumption and the traffic load in the network, the CHs are rotated among all CMs. In WSNs, energy is mostly consumed during transmission and reception. Transmission collisions can further decrease the energy efficiency. These collisions can be avoided by using a contention-free protocol during the transmission period. Additionally, the CH allocates slots to the CMs based on their residual energy to increase sleep time. Furthermore, the energy consumption of CH can be further reduced by data aggregation. In this paper, we propose a data aggregation level based on the residual energy of CH and a cost-aware decision scheme for the fusion of data. Performance results show that the CCBE scheme performs better in terms of network lifetime, energy consumption and throughput compared to low-energy adaptive clustering hierarchy (LEACH) and hybrid energy-efficient distributed clustering (HEED).

Recent development in electronics and wireless communications has enabled the improvement of low-power and low cost wireless sensors networks. Wireless Sensor Networks(WSNs) are a combination of autonomous devices transmitting locally gathered information to a so-called sink node by using multihop wireless routing. One of the most important challenges in WSNs is to design energy efficient routing mechanism to increase the network lifetime due to the limited energy capacity of the network nodes. Furthermore, hot spots in a WSNs emerge as locations under heavy traffic load. Nodes in such areas quickly drain energy resources, leading to disconnection in network services. Cluster based routing algorithms in WSNs have recently gained increased interest, and energy efficiency is of particular interest. A cluster head (CH) represents all nodes in the cluster and collects data values from them. To balance the energy consumption and the traffic load in the network, the CH should be rotated among all nodes and the cluster size should be carefully determined at different parts of the WSNs. In this paper, we proposed an cluster based energy efficient routing algorithm (CBER), CBER elects CH based on nodes near to the optimal cluster head distance and residual energy of the nodes. In WSNs energy is mostly consumed for transmission and reception, it is a non linear function of transmission range. In this paper, the optimal cluster head distance which links to optimal energy consumption is derived. In addition, residual energy is considered in the CH election in order to increase the network lifetime. Furthermore, the energy consumption of being a CH is equally spread among the cluster members. Performance results show CBER scheme reduces the end to end energy consumption and prolong the network lifetime of multi hop network compared to the well-known clustering algorithms LEACH and HEED.

Recently, we are witnessing increased interest in the research of Vehicular Ad-hoc Networks (VANETs). Traffic safety applications using VANETs aim to improve traffic safety in the road using messages which have to meet high reliability, low and predictable delay constraints. Moreover, due to characteristics of VANETs, such as high speed, unstable communication link, and network partitioning, information transfer becomes inevitably challenging. The effectiveness of traffic safety applications using VANETs depends up on the performance of medium access protocol (MAC). Vehicles using CSMA/CA (IEEE 802.11p) MAC algorithm the time to channel access increases randomly every time when the channel is sensed busy. The main challenge for the design of MAC protocol for VANETs is to achieve reliable delivery of messages within the time limit even when the density of vehicles varies rapidly in the network. Furthermore, MAC algorithms with good scalability, fairness, and predictable delay are needed to fulfill the requirements of traffic safety applications. Therefore, cluster-based MAC protocols that can avoid or limit channel contention, provide fairness to channel access, increases radio capacity by the spatial reuse of network resources and effectively control the topology of the network. However, due to the high mobility characteristics of VANETS, vehicles frequently join and leave clusters affects the stability of network. Furthermore, the stability become worse if the cluster heads (CH) elected are not stable. Therefore, maintaining cluster stability can increase performance of safety applications in VANETs. Finally, we propose two cluster based MAC protocols (D-CBM) based on contention based carrier sense multiple access (CSMA) and collision free time division multiple access (TDMA) in order to achieve high stability, low communication overhead and real time delivery of safety messages. Simulation results indicate the proposed protocols are able to achieve the above requirements. Furthermore, we analyze the performance of the proposed MAC design with SBCA protocol.

A growing demand for well‐defined telematics systems in the intelligent transport distribution of pharmaceutical drugs is envisaged driven by legislative demands to enable the safe handling of medicines in automotive distributions. The provision is accomplished by providing virtual intelligence to vehicles designated for this form of smart freight transportation. The system provides anytime/anywhere assets tracking while on the move, from departure to destination, supporting reliable courier operation at low labour. The tracking and tracing system provides the vehicle with sufficient intelligence to: be located remotely, track and trace assets and provide incidence reports. The authors’ architecture is intended to automatically broadcast adaptive logistic‐distribution‐plans between a central office and a vehicle. The proposed system represents an inexpensive and non‐intrusive solution that exploits advanced technologies such as smart environment sensing, radio frequency identification, Wireless Fidelity (WiFi) and global positioning system, to support modern industrial needs. The authors describe and discuss the motivation and the benefits of using the system, including new hardware and software developments.

This paper proposes a direction based clustering and multi-channel medium access control (DA-CMAC) protocol for Vehicular Ad Hoc Networks (VANETs). Vehicles travelling in the opposite direction may result in a short communication period. Clustering based on the direction of travel can reduce the cost of reconfiguration due to the short communication period. Each cluster consists of Cluster Head (CH), and Cluster Members (CMs). CH calculates priorities based on the eligibility function and assign each CM with a unique priority based on the number of connected neighbours, average speed deviation, and the average distance between neighbours and itself. Clusters are independently managed and locally reconfigured as vehicles travel. Moreover, the CH manages the channel access and allocates time slots to its CMs. DA-CMAC aims to reduce access and merging collisions in the channel, by grouping the time slots into two sets based on the direction of movement. Each CM is allocated with one time slot in both Control Channel Period (CCP) and Service Channel Period (SCP) to achieve fairness in channel access. Simulation results show that the proposed protocol will increase the reliability of packets and reduce the access collisions due to vehicular mobility.