Design and Application for Reliable Cooperative Networks

Abstract

The fast progress of mobile devices and modern wireless networks result in the explosive demand for wireless data transfer. Such wireless communications have to meet numerous challenges such as spectrum sharing, energy scarcity, and security to deal with the dramatic growth in wireless data which shift the focus of research directions to fifth-generation (5G) networks. To address these challenges in wireless design, researchers need to come up with energy and spectrum management solutions in 5G networks. The key technologies for 5G considering reliable cooperative networks such as full-duplex networks, energy-efficient communications so-called energy harvesting, and secure networks with physical layer considerations. In general, to guarantee quality-of-service (QoS) it is required high-speed data rate and reliable transmission in design of new paradigms in 5G networks. This chapter focuses on cooperative networks applied in several emerging wireless technology. In addition, these cooperative networks have been well-known models for improving the coverage of wireless systems. The key principle of cooperative network is that one or some relay nodes are installed to forward messages from the source node to its destinations in case of the direct transmission is inaccessible. As popular schemes, we introduce dual-hop scheme and multi-hop scheme with one or many relaying links from the source node to the destination node in this section. In each hop, the relaying node first process received signal of the signal from the previous hop and then used to relay the signal to the next hop. To examine the performance of relay networks, various relay selection protocols and key fundamental relaying schemes including amplify-and-forward (AF) and decode-and-forward (DF) are investigated. In recent applications of Internet of things (IoT) or wireless sensor networks (WSNs), the source and relay are usually energy-constrained nodes which result in limitation of operation time and the network performance. To overcome the challenge of replacing or recharging batteries in such wireless nodes, energy harvesting has been proposed architecture in relaying networks to prolonging the lifetime of these mobile nodes. Motivated by the recent benefits of self-interference elimination procedures of possible full-duplex (FD) transceivers. As an important model, this chapter further explores the reliable cooperative networks to enhance system performance. In such networks, FD entities and energy harvesting-assisted relay node can be examined to confirm advantages of FD transmission architecture. Furthermore, with the aim to deal with high traffic volume and optimize spectral efficiency, two-way relaying scheme is widely considered. In particular, this chapter presents system model of relaying networks to improve the spectral efficiency of the network, and the outage performance for the network is analyzed. Finally, due to the broadcast nature of wireless transmission, secure communication is compulsorily required in emerging network design, especially in scenarios of increasing number of the unintended receivers which is very challenging mission. Through this secure model, the physical layer without cryptography is investigated to examine positive secrecy capacity. In particular, the secrecy performance of an energy harvesting relay system is studied, in which a legitimate source transfers data to a legitimate destination via the support of unreliable relays.