The main purpose of this book is to study a new mitigation scheme for re-entry blackout via numerical simulation in order to demonstrate the possibilities of the suggested schemes.When a radio wave frequency becomes greater than the plasma frequency, radio wave transmission is possible. Since the plasma frequency is related to the plasma number density of the plasma layer, the manipulation of the plasma density is a useful method for solving the communication blackout problem. To manipulate the plasma density, this book considers two schemes, one involving an electrostatic sheath and the other an electromagnetic or ExB layer.This book provides a series of models that were developed for the ExB layer and the electrostatic sheath, and compares these models to data obtained from experiments that were conducted to explore the use of electric and magnetic fields to manipulate a plasma layer. The book demonstrates that an applied ExB layer can manipulate plasma density in a localized region to reduce radio wave attenuation in a plasma layer, thus enabling communication during radio blackout.