Relay Placement for Physical Layer Security: A Secure Connection Perspective

TL;DR

This paper investigates relay placement strategies to enhance physical layer security in cooperative wireless networks, demonstrating that randomize-and-forward relays outperform decode-and-forward, especially under severe path loss conditions.

Contribution

It derives optimal power allocation for decode-and-forward relays and shows that relay placement significantly improves secure connections in cellular networks.

Findings

RF strategy outperforms DF in secure connection enhancement

Relay placement benefits increase with severer path loss

Secure connections are difficult without relays at cell edges

Abstract

This work studies the problem of secure connection in cooperative wireless communication with two relay strategies, decode-and-forward (DF) and randomize-and-forward (RF). The four-node scenario and cellular scenario are considered. For the typical four-node (source, destination, relay, and eavesdropper) scenario, we derive the optimal power allocation for the DF strategy and find that the RF strategy is always better than the DF to enhance secure connection. In cellular networks, we show that without relay, it is difficult to establish secure connections from the base station to the cell edge users. The effect of relay placement for the cell edge users is demonstrated by simulation. For both scenarios, we find that the benefit of relay transmission increases when path loss becomes severer.