MAC Protocols enables sensor nodes of the same WSN to access a common shared communication channel. Many researchers have proposed different solutions explaining how to design and implement these protocols. The main goal of most MACs protocols is how to prolong lifetime of the WSN as long as possible by reducing energy consumption since it is often impossible to change or to recharge sensors' batteries. The majority of these protocols designed for WSN are based on "duty-cycle" technique. Every node of the WSN operates on two periods: active period and sleep period to save energy. Until now (to our knowledge) there is no ideal protocol for this purpose. The main reason relies on the lack of standardization at lower layers (physical layer) and (physical) sensor hardware. Therefore, the MAC protocol choice remains application-dependent. A useful MAC protocol should be able to adapt to network changes (topology, nodes density and network size). This paper surveys MAC protocols for WSNs and discusses the main characteristics, advantages and disadvantages of currently popular protocols.

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In recent years, vehicular communication systems have taken an important place in Intelligent Transport Systems (ITS). These systems are designed on self-organizing networks, known as Vehicular Ad hoc NETworks (VANETs). Their objective is to struggle against road safety problems and road traffic congestion by integrating information and communication technologies in road infrastructures and vehicles. VANET differs from other types of ad hoc networks by high mobility and very dynamic topology. Consequently, the design of an efficient VANET routing protocol becomes a challenging task. Many routing schemes with QoS (Quality of Service) have been proposed in the literature for VANET, to satisfy the performances required by the different applications running upon such networks. Cross-layer designs, which make it possible to exchange and share information between the different layers of the network, have shown to be efficient in VANETs. This paper proposes an improved version of the geographic Greedy algorithm as a cross-layer routing protocol for VANETs. The cooperation between the network layer and the lower layers involves three cyber-physical parameters: Speed, position and Signal-to-Noise Ratio (SNR). The simulation results over the Network Simulator-3 (NS3) demonstrated the effectiveness of the proposed solution in terms of end-to-end delay, throughput and packet delivery ratio.

Cryptographic circuits are essential in systems where security is the main criteria. Therefore, it is crucial to ensure the correctness of not only the cryptographic algorithms, but also their hardware implementations. Formal methods, unlike the other validation techniques, guarantee the absence of errors.The problem is that designers still use conventional imperative Hardware Description Languages (HDLs), which are poorly suited for formal verification. This paper presents an automatic verification methodology for the pipelined cryptographic circuits using formal methods. It consists of using the functional HDL Lava to describe and verify the equivalence between the behavioural specification and structural implementation of a circuit. To the best of our knowledge, we are the first to use this functional HDL for that purpose. To show the features of the proposed approach, it was applied to verify the pipelined implementation of the cryptographic circuit AES (Advanced Encryption Standard).Povzetek: Za namene preverjanja formalne pravilnosti delovanja vezij je opisan funkcionalni pristop.

A Vehicular Ad hoc Network (VANET) is an interconnection of vehicles that communicate through wireless technologies. It offers to road users a wide variety of applications which can be classified into four main categories: safety, road traffic, comfort and infotainment. This paper deals with safety applications. Their main goal is to detect critical road conditions (e.g. accidents, black ice, etc.) and/or send notifications to other vehicles in the network. An effective dissemination of such a message relies on multi-hop retransmissions. Thus an explicit or implicit cooperation between vehicles is needed in order to relay the message over a wide area. The main challenge is to avoid the broadcast storm problem. This paper proposes an efficient segment-delay based method that divides the road into several segments depending on the network density and utilises a waiting time update technique to expedite the dissemination process with respect to network performance.