  We present a Waveform Relaxation (WR) version of the Neumann-Neumann
algorithm for the wave equation in space-time. The method is based on a
non-overlapping spatial domain decomposition, and the iteration involves
subdomain solves in space-time with corresponding interface condition, followed
by a correction step. Using a Fourier-Laplace transform argument, for a
particular relaxation parameter, we prove convergence of the algorithm in a
finite number of steps for finite time intervals. The number of steps depends
on the size of the subdomains and the time window length on which the algorithm
is employed. We illustrate the performance of the algorithm with numerical
results, followed by a comparison with classical and optimized Schwarz WR
methods.
