Spectrum sensing is one of the essential tasks to have a Cognitive Radio (CR) system, which will allow an unlicensed user, called Secondary User (SU), to utilize the spectrum while the licensed user, called Primary User (PU), is not occupying it. The spectrum sensing approaches can be classified as blind and knowledge aided approaches. This tutorial summarizes blind spectrum sensing approaches that require no prior knowledge of the licensed user’s signal characteristics, specifically for an interweave cognitive radio Network (CRN) model. The tutorial provides a thorough background, major implementations, and limitations of the Blind Spectrum Sensing (BSS) approaches, which are Energy Detector (ED) approach, Maximum to Minimum Eigenvalue (MME) approach, Maximum Eigenvalue (ME) approach, Covariance Absolute Value (CAV) approach, and Covariance Frobenius Norm (CFN) approach. Moreover, the tutorial compares these approaches based on performance metrics and complexity requirements. Furthermore, for a higher interference protection, the combination of two different spectrum sensing approaches, namely two-stage detection technique is presented and discussed. Besides, the tutorial discusses the challenges and possible future research directions. The fundamental objective of this tutorial is to provide insightful views and design aspects of BSS approach to researchers. For this purpose, the tutorial includes pseudo codes and simulation examples to illustrate more about the practical aspects of the above-mentioned approaches.

Dedicated short range communication is proposed for vehicle to vehicle communications to learn about significant events in the network from neighboring vehicles. However, these neighbors may be malicious and report incorrect events in order to take advantage of the system. The malicious nodes may also provide incorrect recommendations about their peers in order to exert a stronger influence on the receiver's decision. Incorrect information and malicious nodes render the system unreliable for safety and emergency applications. In order to correctly identify the events as well as malicious nodes, a novel trust framework is proposed in this paper that studies all aspects of the trust in connected vehicle (CV) to CV communications. The nodes iteratively learn about the environment from received messages and then update the trust values of their neighbors. Nodes are classified on the basis of their trust values and reported events are also classified as true and false. Nodes advertise their recommendation about trusted and malicious neighbors. The proposed framework allows nodes to identify and filter recommendations from malicious nodes, and to discern true events. The performance of the proposed framework is evaluated experimentally using false and true positive rates, event detection probability and trust computation error. The proposed framework identifies malicious nodes and true events with high probability of more than 0.92 while keeping the trust computation error below 0.03.

A novel 3D real-time geographical routing protocol (3DRTGP) for wireless sensor networks is presented in this paper. 3DRTGP controls the number of forwarding nodes in the network by limiting forwarding to a unique packet forwarding region (PFR). PFR selection is based on the network density around each of the forwarding nodes, which reduces the number of redundant packet transmissions, collisions, and congestion. This enables 3DRTGP to meet the real-time requirements of a time sensitive application. In order to meet the packet delivery delay deadline, a forwarding node uses its own delay parameters, such as queuing and processing delays, and the expected number of hops to the destination to make a forwarding decision. 3DRTGP does not require an explicit exchange of neighboring information, such as location information. 3DRTGP is evaluated through extensive simulations under various network densities and traffic load conditions, which provides network tuning parameters to meet the real-time requirements of applications. 3DRTGP heuristically solves the void node problem (VNP) in 3-D deployments. It is demonstrated that 3DRTGP resolves VNP given that there is no network partitioning. 3DRTGP significantly outperforms similar 3-D geographical routing protocols in terms of end-to-end delay and miss ratio.

This article presents the design and implementation of modular customizable event-driven architecture with parallel execution capability for the first time with wireless sensor nodes using stand alone FPGA. This customizable event-driven architecture is based on modular generic event dispatchers and autonomous event handlers, which will help WSN application developers to quickly develop their applications by adding the required number of event dispatchers and event handlers as per the need of a WSN application. This architecture can handle multiple events in parallel, including high priority ones. Additionally, it provides non-preemptive operation which removes the timing uncertainty and overhead involved with interrupt-driven processor-based sensor node implementation, which is required in real-time wireless sensor networks (WSNs). Thus, higher computation power of FPGAs combined with the non-preemptive modular event-driven architecture with parallel execution capability enables a variety of new WSN applications and facilitates rapid prototyping of WSN applications. In this article, the performance of FPGA-based sensor device is compared with general purpose processor-based implementations of sensor devices. Results show that our FPGA-based implementation provides significant improvement in system efficiency measured in terms of clock cycle counts required for typical sensor network tasks such as packet transmission, relay and reception.

In this article, a new infrastructure of a combined Worldwide Interoperability for Microwave Access (WiMAX) and Dedicated Short-Range Communications (DSRC) link layer is proposed with the purpose of reducing simultaneous WiMAX connections. WiMAX offers wide area connectivity of vehicles to ground-based base stations, while DSRC offers relatively shorter communication that allows for vehicles in proximity of each other to communicate directly. The proposed design uses the fact that WiMAX amendments support the concept of a WiMAX relay node, and substitutes the WiMAX relay nodes with nodes that are capable of both WiMAX and DSRC communications. This change allows for the number of WiMAX connections to be concentrated while supporting more subscribing users via WiMAX tunnelled over DSRC relay. The focus of this design is on the use case of providing broadband Internet access to a large number of DSRC capable vehicles in a WiMAX served region. The design uses DSRC as a WiMAX tunnel, but with changes to the WiMAX protocol, specifically network entry and handover processes are redesigned to have different behaviour only when operating over DSRC. Network entry over DSRC modifications are described and illustrated with comparison to existing WiMAX standards. Handover process facilitated over both WiMAX and DSRC layers are described, illustrated and are also standard compliant. Unified modeling language is used to assist with the explanations of the components to improve understanding of the design in relation to existing WiMAX standards. In addition to standard WiMAX operability, the design can also support WiMAX data subscription using a software-defined WiMAX radio via DSRC relay connectivity. This proposed design improves WiMAX communication by reducing the number of WiMAX connections between vehicles. We plotted the throughput of various cluster sizes of WiMAX only mobile relay, versus our proposed DSRC-enabled WiMAX mobile relay in order to show the efficiency benefit of our design. We also provide a simulated curve of percentage improvement efficiency for varying amount of active users. We show that as the total number of users in the system increases, our proposed system significantly improves the overall system efficiency, especially in heavily congested traffic.