Secure Wireless Communications via Cooperative Transmitting

TL;DR

This paper investigates how cooperative transmitting in wireless networks enhances secrecy regions against passive eavesdroppers, combining information theoretic and cryptographic methods, with analysis of spatial distributions and numerical simulations.

Contribution

It introduces a secret-key exchange protocol using cooperative transmitting and analyzes its effectiveness with different spatial distributions and network configurations.

Findings

Deterministic transmitter distributions increase secrecy probability.

Cooperative transmitting significantly enlarges secrecy regions compared to jamming and relaying.

Upper bounds closely estimate actual secrecy probabilities.

Abstract

Information theoretic secrecy is combined with cryptographic secrecy to create a secret-key exchange protocol for wireless networks. A network of transmitters, which already have cryptographically secured channels between them, cooperate to exchange a secret key with a new receiver at a random location, in the presence of passive eavesdroppers at unknown locations. Two spatial point processes: homogeneous Poisson process and independent uniformly distributed points are used for the spatial distributions of transmitters and eavesdroppers. We analyse the impact of the number of cooperating transmitters and the number of eavesdroppers on the area fraction where secure communication is possible. Upper bounds on the probability of existence of positive secrecy between the cooperating transmitters and the receiver are derived. The closeness of the upper bounds to the real value is then estimated by means of numerical simulations. Simulations also indicate that a deterministic spatial distribution for the transmitters e.g. hexagonal and square lattices, increases the probability of existence of positive secrecy capacity compared to the random spatial distributions. For the same number of friendly nodes, cooperative transmitting provides a dramatically larger secrecy region than cooperative jamming and cooperative relaying.