In this chapter, we investigate the problem of physical-layer security in wireless networks with cooperative relays. In Sections 11.2 and 11.3, we study the notion of deaf cooperation to reinforce security of transmission in wireless relay networks. We distinguish between two main approaches to deaf cooperation, namely, the cooperative jamming (CJ) approach and the noise forwarding (NF) approach. In a CJ scheme, a helping interferer transmits Gaussian noise when it can hurt the eavesdropper more than it can hurt the legitimate receiver, and hence improves the achievable secure information rate. The idea of introducing artificial noise in a Gaussian wiretap channel by a helper node was introduced in References 5-7. In relay networks with secrecy constraints, the role of CJ was further investigated, e.g., in References 8-10. References 11-13 proposed CJ strategies for multiple-antenna relay networks. On the other hand, in the NF scheme which was introduced in Reference 14, the relay node sends a dummy (context-free) codeword drawn at random from a codebook that is known to both the legitimate receiver and the eavesdropper to introduce helpful interference that would hurt the eavesdropper more than the legitimate receiver.

Chapter Contents:

• 11.1 Introduction
• 11.2 Deaf cooperation in multiple relay networks
• 11.2.1 CJ versus NF
• 11.2.2 Deaf helpers selection
• 11.2.2.1 Single deaf helper selection strategy
• 11.2.2.2 Multiple deaf helpers selection strategy
• 11.2.3 Empirical evaluation
• 11.3 Deaf cooperation with multiple antennas
• 11.3.1 CJ versus NF in multi-antenna deaf cooperation
• 11.3.2 The reversely degraded multi-antenna relay-eavesdropper channel
• 11.3.3 Empirical evaluation
• 11.4 Active cooperation in multiple relay networks
• 11.4.1 DF with multiple relays
• 11.4.1.1 A single-hop strategy
• 11.4.1.2 A multiple hop strategy
• 11.4.1.3 A multiple hop strategy with full ZF
• 11.4.2 Empirical evaluation
• 11.5 Conclusions
• References

Inspec keywords: radio receivers; relay networks (telecommunication); Gaussian noise; Gaussian channels; cooperative communication; telecommunication security; antennas; jamming

Other keywords: artificial noise; relay node; secrecy constraints; helper node; context-free codeword; dummy codeword; Gaussian noise; eavesdropper; NF approach; CJ scheme; cooperative jamming; physical layer security; noise forwarding; cooperative relays; multiple-antenna relay networks; wireless relay networks; Gaussian wiretap channel; deaf cooperation

Subjects: Single antennas; Radio links and equipment; Electromagnetic compatibility and interference; Codes