We give sufficient conditions for the existence of positive travelling wave
solutions for multi-dimensional autonomous reaction-diffusion systems with
distributed delay. To prove the existence of travelling waves, we give an
abstract formulation of the equation for the wave profiles in some suitable
Banach spaces, and apply known results about the index of some associated
Fredholm operators.
In the early 2000's, Gourley (2000), Wu et al. (2001), Ashwin et al. (2002)
initiated the study of the positive wavefronts in the delayed
Kolmogorov-Petrovskii-Piskunov-Fisher equation. Since then, this model has
become one of the most popular objects in the studies of traveling waves for
the monostable delayed reaction-diffusion equations. In this paper, we give a
complete solution to the problem of existence and uniqueness of monotone waves
in the KPP-Fisher equation. We show that each monotone traveling wave can be
found via an iteration procedure.