In this paper, three opportunistic pressure based routing techniques for underwater wireless sensor networks (UWSNs) are proposed. The first one is the cooperative opportunistic pressure based routing protocol (Co-Hydrocast), second technique is the improved Hydrocast (improved-Hydrocast), and third one is the cooperative improved Hydrocast (Co-improved Hydrocast). In order to minimize lengthy ...

In Wireless Local Area Network, wireless node will suffer due to the hidden terminal node. This hidden terminal node leads to high collision, high drop rate of packets and high delay. To avoid this hidden terminal node, wireless nodes use the control messages to know the status of the destination nodes. Another issue in the WLAN is less coverage range with lesser number of nodes. To increase th...

We treat the problem of cooperative multiple beamforming in wireless ad hoc networks. The basic scenario is that a cluster of source nodes cooperatively forms multiple data-carrying beams toward multiple destination nodes. To resolve the hidden node problem, we impose a link constraint on the receive power at each unintended destination node. Then the problem becomes to optimize the transmit po...

This paper studies polar coding for secure communications over the general two-way wiretap channel, where two legitimate users communicate with each other simultaneously while a passive eavesdropper overhears a combination of their exchanged signals. The legitimate users wish to design a coding scheme such that the interference between their codewords can be leveraged to jam the eavesdropper. T...

Cognitive radio (CR) and non-orthogonal multiple access (NOMA) have been deemed two promising technologies due to their potential to achieve high spectral efficiency and massive connectivity. This paper studies a multiple-input singleoutput NOMA CR network relying on simultaneous wireless information and power transfer (SWIPT) conceived for supporting a massive population of power limited batte...

This thesis focuses on cooperative relaying protocols employing a relay node that overhears data transmissions between a source and a destination nodes and retransmits the data when necessary. The achieved signal diversity at the destination improves the data recovery in fading-rich environments. While cooperative relay can improve communication on one link, the induced relay interference can d...

With development of wireless communications in the two last decades, new infrastructures have been developed. One of them is the Vehicular Ad hoc Networks (VANETs). They are considered as ad hoc networks with the particularity that the topology is always changed, that make more complicated the resource management and open some beaches in security. Specifically on the Physical andMAC layers that...